Circuits Assembly - December 2008

Analyzing Pb-Free Wave Soldering Defects, pg. 34

DECEMBER 2008

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Plexus

on the Move A Look Inside Our EMS Company of the Year Flux’s Role in HIP Defects Pb-Free Wetting Tests Predicting Lean Outcomes Covers_CA-0812.indd C1

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DECEMBER 2008

circuitsassembly.com

Photo courtesy of Plexus Corp.

Analyzing Pb-Free Wave Soldering Defects, pg. 34

Plexus

on the Move A Look Inside Our EMS Company of the Year

DECEMBER 2008 – Vol. 19 No. 12

Flux’s Role in HIP Defects Pb-Free Wetting Tests

FIRST PERSON 6 Caveat Lector Foxconn goes south of the border. Mike Buetow

MONEY MATTERS 17 Global Sourcing

Predicting Lean Outcomes

ON THE COVER: Plexus has perfected the art of the workcell.

FEATURES COVER STORY

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The best-performing publicly held EMS company is not Jabil, Benchmark nor Flextronics, but a quiet Midwestern entity with a primarily North American footprint and “too many” engineers. Why Plexus is our 2008 EMS Company of the Year. By Mike Buetow

Relationship ruiners. Jennifer Read

TECH TALK 18 Screen Printing

Retrospective

26

What I don’t like about you. Dr. H.J. Zapfardt III

32 Tech Tips Solder wetting tests. American Competitiveness Institute

In Memoriam CIRCUITS ASSEMBLY recalls friends and industry colleagues who won’t see 2009.

Post-print inspection. Clive Ashmore

19 Better Manufacturing

The Plexus Rx

Solder Joint Reliability

28

HIP Defects in BGAs Solder joints afflicted with head-in-pillow lack strength, and the components may fail under minimal mechanical or thermal stress. HIP is now known to be caused by certain process variables, including the BGA ball alloy, reflow process type, reflow profile and solder paste chemistry. The role each of these variables plays, and certain mitigation techniques, are identified in this study. By Karl Seelig

33 Test and Inspection In support of DfT. Stacy Kalisz Johnson

34 Wave Soldering Drop-ins are out. Ursula Marquez de Tino

36 Process Doctor Analyzing SEM and EDX. Terry Munson

37 Pb-Free Lessons Learned The HIP epidemic proliferates. Chrys Shea

39 The Defects Database Paste residue and solvent incompatibilities. Dr. Davide Di Maio

40 Standards All marked up. John Perry

This month at PCDandF.com Electronic System Design ECAD-MCAD collaboration supports bidirectional communication that can shorten design times, reduce errors and bring products to market faster. By John Isaac

PCB Dielectric Materials for High-Speed Applications The glass weave in a laminate can affect the propagation velocity and loss profile, leading to signal loss and skew in differential pairs. By Ravindra Gali

PCB Designers Take on Technology Challenges in 2008 Decisions made in the design seat determine not only the size and shape of the PCB, but also the technology type and materials used to build the board. By Kathy Nargi-Toth

42 Getting Lean Predicting outcomes. Robert Hemmant

43 Eastern Advances Soldering terminations, part 2. Sanqiang Cai

48 Technical Abstracts

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DEPARTMENTS 8 Industry News 16 Market Watch 44 Product Spotlight

46 Ad Index 47 Assembly Insider

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Caveat Lector

Crapshoot in Juárez he city of Juárez, Mexico, sits to the south and west of the US, sharing a jagged border – otherwise known as the Rio Grande – with the state of Texas. The Juárez Mountains rise to the west, abutting the sprawling home of some 1.3 million residents. It’s also the home to an estimated 300 maquiladoras, or assembly plants, and that’s where our story really begins. For those feeling the pinch – or is that squeeze? – of the financial markets, the news Foxconn is investing a reported $185 million in a massive electronics manufacturing campus on the Mexico-US border must come with mixed blessings. As we reported in July, the new site will eventually house more than 3 million sq. ft. of industrial space in 12 buildings spread across some 440 acres. The Foxconn campus will include cafeterias, a nursery and a mall, and once finished, will dwarf those of other nearby electronics manufacturers. Flextronics’ site in Ciudad Juárez, for example, which opened in 2006, will top out at 1.9 million sq. ft. and will employ roughly 4,000 workers at peak, according to company statements. Swedish white goods manufacturer Electrolux has two factories totaling more than 2 million sq. ft. and employing 4,000 workers. Other well-known EMS companies and ODMs dot the Juárez landscape. They include Acer, Asus, Bizlink, ECS, Elite, Enlight, EPIC Technologies, Inventec, Keytronic EMS, Mack Technologies, Tatung and Plexus (see this month’s cover story). Some have left, only to return. Elcoteq, for instance, shut down its settop production site in 2007, purchased from Thomson in 2004, then bought Philips’ flat-screen TV operations this fall. Even Foxconn is already there: In 2005 it opened a 2,000-employee plant on a 43-acre site. Taiwanese-owned companies employed an estimated 8,000 workers in the area as of last year, the El Paso Times reports. Still, what Foxconn now proposes is on an altogether different scale: 20,000 workers or more at full capacity. Across the border in Santa Teresa, Jerry Pacheco is executive director of the New Mexico International Business Accelerator, a state administered group that aids local companies looking to expand globally. He says the labor market has loosened because of the softness in the economy. Still, skilled labor is at a premium, he asserts. In today’s market, line workers make close to $3 an hour fully loaded. For more skilled labor, the rate is close to $5.

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Circuits Assembly DECEMBER 2008

The Foxconn site sits in San Jerónimo, on the relatively undeveloped western edge of Juárez. For its first phase, Foxconn is expected to hire 9,300 workers, Pacheco says. And while dorms are the norm at Foxconn “cities” in China, in Mexico the company will have to bus in employees. Yet Pacheco believes the area can absorb Foxconn’s projected needs, as Juárez grows by several thousand people each year. “All the maquilas compete against each other, but Juárez is such a big city,” he says. “There are times when the labor gets tight.” But this isn’t one of them, he adds. Foxconn plans to have the first phase completed in February and production launched during the first quarter. The current softening hasn’t impacted its plans, Pacheco says. The main products will be laptops, desktops and printers, and the top customers, if this reporter were to guess, would be H-P and Dell. Violence is always a concern south of the border. The notorious Juárez Cartel is brutal and murderous, and just last month, the bodies of two men were found, executed and decomposing, just outside one of Electrolux’s plants. While it’s nothing like a Latin America drug cartel, the Foxconn name sends shudders down many competitors’ spines as well. Like a black hole, the company tends to gobble up everything around it. Even in a down economy, the impact will be felt broadly on everything from human capital to sales. And this page has been directly critical of Foxconn’s approach to business and its treatment of workers. But is there a silver lining? I think so. Foxconn’s investment can – and should – be seen as a concrete affirmation of the potential of the North American market, both as a purchasing power and as a manufacturing center. This bodes well for suppliers, especially given the less-than-pretty forecast for 2009. It bodes well for those concerned with workers’ rights; while Mexico isn’t perfect, it is easier for committed OEMs to keep an eye on their contractors in Juárez than, say, Shenzhen. And it bodes well for the American psyche as proof we can profitably build something more than weapon systems and high-IP medical devices. It’s something of a crapshoot, but I think this will turn up a winner. Happy holidays. All our best for a healthy and happy 2009!

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Mike Buetow, Editor-in-Chief [email protected]

circuitsassembly.com

11/19/08 4:31:20 PM

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Industry

NEWS

Recession Spells End of Foxconn Effect, Analyst Says

In Brief Digi-Key Corp. (digikey.com) has expanded its line of Tyco Electronics Raychem Circuit Protection Products to include PolyZen Zener diodes. SMTC (smtc.com) cut 276 full-time staff and approximately 100 temporary staff, mainly in Mexico, as it moved production to the company’s facility in China. A-Laser (a-laser.com), a provider of laser-cutting services, has expanded its hours of operations to meet demands of just-in-time manufacturers. The firm is now running three shifts to enable 24-hr. capacity. A-Laser is a division of FCT Assembly. Sunburst Electronics (sunburstelectronics.com) is in the final stages of gaining ISO 13485 certification, a quality management standard for medical device manufacturing. The company plans to extend its medical device industry reach as a result. Indium Corp. (indium.com) named EMC3 Group (emc3group.com) its sales channel partner in Florida. Ellsworth Corp. (ellsworth.com) opened a wholly owned subsidiary, Ellsworth Latin America Adesivos LTDA, in Sao Paulo, Brazil, to provide adhesives, sealants, coatings, encapsulants, tapes, and dispensing and curing equipment to Latin America. Manufactured Assemblies Corp. (mac-cable.com), a provider of EMS and other products and services, will build a 40,000 sq. ft. office and production facility in Vandalia, OH, with the planned opening early next year. MAC, which has operations in Dayton, OH, and suburban Atlanta, has 55 employees. The company plans to hire up to 25 more over the next three years, according to reports. Cobar Europe (cobar.com) appointed Prosem Technology India (prosemtechnology.com) its representative in India. ACD (acd.biz) has selected Optimal Electronics’ (optelco.com) Optel MES software.

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Edited by Chelsey Drysdale

SAN JOSE – The top 10 EMS firms showed collective first-half growth of 4.3%, down from 20% last year, and the forecast, if not dire, is dimmer than before. In an economic wrap-up of the electronics industry, iSuppli Corp. in October said EMS/ODM firms have been hit hard by macroeconomic concerns and drops in demand. The environment has led the firm to lower its growth outlook for the sector to 8.2% CAGR. The subprime mortage resets peak during the second quarter, coupled with problems at Fannie Mae and Freddie Mac, loom large over economy, iSuppli noted. Said Adam Pick, principal analyst, EMS/ODM services, “In a recession, the Dow [Jones] drops 48 to 49%, so it could still get worse.” There’s no question the broader economic situation is being felt at the EMS/ODM level. ODM shipments are dropping tremendously this year. The No. 1 company, Compal Communications, a supplier to Motorola, Nokia and LG, has seen shipments drop 33.3% from last year. No. 2 Quanta has dropped 7.5%, while Qisda is down a whopping 50%. TPV has dipped 14.3%, and Asus is down 6.1%. “ODMs are definitely getting hit,” Pick said. “Revenues are down; shipments are down; forecasts are down.” The big question now is, Which of the EMS companies and ODMs will survive? Are there any likely bankruptcies? According to a new report by iSuppli, most firms are OK. However, without naming names, Pick suggested some firms could be in trouble during a recession. (The report, “Recession Hits EMS/ODMs,” was due out Nov. 7.) On the flip side, some CEOs are saying a recession is good for contract manufacturers because OEMs are rethinking their strategies, and Flextronics is positioned to be a prime beneficiary of a new wave of outsourcing. iSuppli thinks otherwise. “Is the rubber-band effect fact or fiction?” asked Pick. “The rubber-band effect was material during the last recession. But today is not 2001.” Jeffrey Wu, senior analyst, EMS/ODM services, pointed to the recent postponement of a major joint EMS/ODM investment in Russia. That deal, between Foxconn and HP, would have invested $50 million in a new 400,000 sq. ft. site in St. Petersburg, capable of producing 40,000 PCs per month. The opening was scheduled for early 2009, and its postponement shows even the largest EMS provider is now “feeling the hurt.” Said Pick, “Weaker demand is having impact on OEMs and EMS providers alike.” iSuppli predicts one of two scenarios: Electronics will either grow at a slower rate or contract altogether. Pick advises OEMs to reduce outsourced production and prepare for supplier consolidation. OEMs also need to ask how they can best reduce capacity. “This is reminiscent of post 2001,” he said. For EMS firms, he mentioned the seasonality of the first half of the year as a problem. “It’s time for EMS to back off.” While margins are actually stabilizing and restructurings are slowing, according to Pick, “consolidation is a definite need to know.” “The Foxconn effect is pretty much over,” he added. Its revenues at the beginning of the decade were $3 billion and grew to $50 billion last year, but “Foxconn has hit some hiccups. Their stock was down 63% in the last 18 months.” Feeling the biggest hiccup, however, has been Benchmark, whose sales are down 10% sequentially. SanminaSCI’s sales have beat expectations, and Celestica is seeing a turnaround in Europe and Mexico, while its “ROI continues to go up and up,” said Pick. For ODMs, the global trend toward mobile computing has been good for growth. The top 10 firms were up 21.3% last quarter, said Pick. Inventec, for instance, has seen a 28% spike in revenue on higher HP and Toshiba orders. Nevertheless, Quanta has had issues with R&D, labor and material, while Compal has struggled with contraction. – Chelsey Drysdale

New IIT Factory Could Double Capabilities POST FALLS, ID – Integrated Ideas & Technologies Inc. (integratedideas.com) recently completed construction and moved into a 23,000 sq. ft. manufacturing facility. The new facility is expected to help the SMT stencil and metal fabrication

Circuits Assembly DECEMBER 2008

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Industry

NEWS In Brief FCT Solder, a division of FCT Assembly, named Ally Jakusovas its representative in California, Oregon, Washington, Colorado and Utah. EMS firm Enics (enics.com) could lay off more than 185 workers in Varkuas, Finland, as it moves operations to other company factories. The company is engaged in negotiations with workers over the layoffs. It currently employs 500 in Finland and 2,700 worldwide. Adeptron Technologies (adeptron. com) will provide $15 million a year in electronics manufacturing services to an undisclosed Canada-based OEM. The deal also has “the potential to increase significantly.” Full ramp is expected to take place during the first quarter 2009. BPM Microsystems (bpmmicro.com) named Lynxtron Inc. its representative in southern Wisconsin, Indiana and northern Illinois. Vicor Corp. (vicr.com) recently added Koh Young Technology benchtop and inline solder paste inspection capability. EMS provider Scanfil (scanfil.com) has begun a 70,000 sq. ft. expansion to its Hangzhou, China, production facilities. The company’s China subsidiaries account for 36% of its overall sales. PartnerTech’s (partnertech.fi) Norfolk, England, manufacturing facility has received ISO 13485:2003 medical certification. The firm, the largest EMS company in Scandinavia, also reduced headcount by 65 during the September quarter. Flex Interconnect Technologies (fit4flex.com) has received International Traffic in Arms Regulations (ITAR) registration from the US Department of State. The Eagle Group named Bliss Industries (blissindustries.com) to represent its line of wire carts for ESD electronics and general material handling.

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provider achieve a 50% increase in production capabilities over the next two years. “We were at maximum capacity in our previous facility and did not have the space for the new equipment required for advancement of our SMT stencil and metal fabrication divisions,” said Michael Ray, president and owner of IIT. The new plant is located eight miles west of the company’s previous facility in Coeur D’Alene. – Mike Buetow

IPC Criticizes TBBPA Inclusion in RoHS Draft BANNOCKBURN, IL – IPC (ipc.org) is taking issue with the inclusion of the flame retardant chemical known as Tetrabromobisphenol A on a draft list of substances that could be added to the EU RoHS Directive, firing off a letter requesting the EU commissioners “reconsider” its potential ban. The trade group had previously made its case to the Öko-Institut (oeko.de), which was charged with drafting the list. TBBPA, a reactive flame retardant used in most printed circuit board laminates, has been reported to be included among five substances for priority assessment and potential inclusion in RoHS by media who claimed to have seen the proposal. It is reportedly used in more than two-thirds of electrical and electronics appliances. Citing the strong body of technical evidence, IPC claims TBBPA is not a risk and should not be included in future RoHS documents. “TBBPA has already undergone a comprehensive EU Risk Assessment and, therefore, is not expected to be subject to authorization under REACH,” IPC said in the letter. “The recommendation for priority review of TBBPA under RoHS seemingly undermines the EU’s emerging chemicals policy and law under REACH. We urge the commission to reconsider the inclusion of TBBPA in its list of ‘priority review’ substances under RoHS.” Following interagency review of the proposal, the EU Commission will present the proposed RoHS Revision to the European Parliament. – Mike Buetow

H.I.G. Chemicals Holdings Acquires Petroferm GURNEE IL – H.I.G. Chemicals Holdings Corp. (higcapital.com) has acquired Petroferm Inc. Terms of the transaction were not disclosed. Petroferm (petroferm.com), a specialty SMT In PICTurES chemical manufacturer and formulator, had been privately held. The acquisition by the private equity firm includes Petroferm’s operations in Gurnee, IL and Fernandina Beach, FL. The Joseph Storey (UK) division will be spun off to Petroferm shareholders. H.I.G. acquired the North American oleochemical business Uniqema Americas earlier this year. The firm plans to maintain the two as distinct operating subsidiaries. The two businesses will have combined sales in excess of $300 million, the firm says. – Chelsey Drysdale

Newview EMS Has Shades of Past WOBURN, MA – From the ashes of MassTech EMS and Neo Nano Electronics has come a new electronics manufacturing company, Newview EMS Corp. Paul Walker, former founder and CEO

Circuits Assembly DECEMBER 2008

Ovation Product’s Grid-Lok substrate support, shown on an Assembléon MX placement machine.

circuitsassembly.com

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Industry

NEWS People EFD International named Philippe Mysson business development manager, solder paste Europe. He holds a master’s in chemistry from Dijon (France) University and has 24 years in solder manufacturing with Thomson Passive Components. roger Taylor has been named senior vice president Group Operations of Elcoteq. He has held senior operational management positions within Nokia and Motorola.

of SMTC (smtc.com), is involved with the new company, as is Jerry Panos, the former CEO of MassTech and Neo Nano. The new company (newviewems.com) is located at the former Nexus Electronics site on New Boston St. in Woburn, MA. This development marks an end to the various incarnations of Neo Nano. Last November, Titan Global Holdings purchased the assets of Nexus Nano, including the former Nexus Electronics site in Woburn and the Nexus operations in Brandon, VT. The division was renamed Neo EMS shortly thereafter. However, Titan quickly decided to sell the division. The Neo EMS facility in Vermont was closed Aug. 13. The site’s answering service references callers to Titan Global Holdings’s corporate headquarters in Richardson, TX. Calls to Titan’s headquarters were not returned. Nexus had revenues of $12 million in the period ended June 30, 2007. Titan has not reported the group’s revenues for fiscal 2008. – Mike Buetow

Industrial Electronics Services Expands in TN

Indium Corp. promoted David McKee to key and direct accounts manager in Europe, responsible for Europe, the Middle East and Africa, with a focus on solder products.

GRAY, TN – EMS provider Industrial Electronics Services Inc. (iesgray.com) will break ground this month on a 40,000 sq. ft. building, the company’s fourth building. The firm employs 67 workers and projects 2008 sales of $6.5 million, up 44%. It expects to hire up to 100 more workers over the next three years. The company, which performs smaller runs of SMT products and various box-build and other services, recently was named a certified supplier by Siemens Medical Solutions. – Mike Buetow

Mydata named Pelle Wennerlund managing director in the China region. He has China experience with a trading company and with plastics machinery manufacturer Krauss Maffei, where he focused on EMS/electronics and automotive.

Fine Line Stencil Opens Memphis Plant

Axiom Electronics named Keya Bhattacharyya Six Sigma Manager. Dr. Bhattacharyya previously worked as a quality/ reliability contractor for Celerity, Planar, and Flextronics. Datron Dynamics named William “Bill” King president. He has been with the company since 1996 and in manufacturing for 25 years. Kester promoted Stephen Santangelo operations manager in North America, responsible for production and quality of solder paste products. The 30-year Kester veteran was most recently Asian Operations Manager for the solder paste business unit.

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COLORADO SPRINGS, CO — Fine Line Stencil (finelinestencil.com), a leading manufacturer of stencil products, has opened a stencil manufacturing facility in Memphis, the company said today. The site will meet demand for quickturn stencils, and gives the company the ability to ship stencils up to midnight Central time. “The quickturn demands on the contract manufacturing industry are increasing rapidly and our Memphis facility gives us the ability to accept and ship stencil orders much later in the day,” said Robert Dervaes, vice president of technology and engineering, in a press release. Fine Line Stencil is a division of FCT Assembly. – Mike Buetow

MPC Files for Bankruptcy NAMPA, ID – MPC Corp. (mpccorp.com), one of the world's largest PC makers, has filed for Chapter 11 bankruptcy protection. The company has been delisted from the NYSE and says it doesn't expect equity holders to receive any distributions in conjunction with the bankruptcy cases. MPC has played in the corporate and government PC space for 17 years. In October 2007, it purchased the professional business unit of Gateway. That acquisition may have been the root of MPC's downfall, however. In a statement, chief executive John Yeros blamed "unforeseen issues surrounding the integration of the Gateway Professional business unit, combined with adapting the operations of our manufacturing partner to additional customized requirements have proven more challenging than originally anticipated, and have contributed to extensive losses. We evaluated all strategic alternatives, and concluded the filing was necessary at this time." MPC outsourced production to Flextronics (flextronics.com), but the latter terminated the deal in mid November, according to a report in the Sioux City Journal. The company has laid off more than 400 workers in the past month, including more than 300 in mid November and has "only a few employees left" at its Nampa site, according to published reports. However, Yeros added company's operations are expected to continue during reorganization efforts. – Mike Buetow

Circuits Assembly DECEMBER 2008

circuitsassembly.com

11/19/08 4:31:51 PM

12News.indd 13

11/20/08 10:31:15 AM

Industry

NEWS Cletronics to Expand Plant, Staff

People Salcomp named Jari Saarinen chief financial officer, effective Jan. 25, 2009. The company also promoted Pekka Kyyriäinen to vice president, global operations, superseding Osmo Oja, who is retiring. He was general manager of Salcomp’s plant in China since 2006. Sunburst Electronics hired Ken Votruba as manager of sales and service in Ohio. Krayden appointed Eric Monson salesman for Utah, Idaho and New Mexico, and Ken Vitale as sales representative in Richmond, VA. J. Mike Sapienti joined Sanmina-SCI as PCB senior business development manager for defense and aerospace. He has 25 years’ experience in manufacturing, defense and aerospace to Sanmina-SCI, including at Intrinsix Corp., Zycon, Parlex and Teradyne. Axis Electronics promoted Paul Jackson to manufacturing director and Chris nye to materials director. AdoptSMT Group appointed Barry Clark managing director for its London-based AlternativeSMT group. He was previously with Universal Instruments Corp. Synchronized Manufacturing Technologies named Jolene Schofield program manager and Steve Cahalane operations manager. Schofield has 20 years’ experience, including her tenure with SanminaSCI. Cahalane has been an engineer, materials and operations manager at Wang and Celestica. Unisem promoted Mike Griffin to corporate vice president of marketing and business development, Gil Chiu to vice president and region head of business development for North America, and S.C. Lim to vice president and region head of business development for Asia.

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CA-0812.indb 14

MEDINA, OH – Cletronics Inc., a small EMS company and manufacturer of coils and inductors, will add 12,000 sq. ft. to its factory here as part of a $960,000 expansion. The company (cletronics.com) will hire three new full-time workers, bringing its total headcount to 16 (not including two part-timers). The local county granted the company a 40% tax abatement for 10 years, under terms of the Community Reinvestment Act, according to reports. – Mike Buetow

Ayrshire Electronics Buys ACT Plant in Corinth CORINTH, MI – Ayrshire Electronics (ayrshireusa.com) has acquired ACT Electronics' facility here for an undisclosed amount. In doing so, Ayrshire saved the largest EMS factory in the US – some 350,000 sq. ft. – and the jobs of about 200 full-time workers and 50 more part-timers. In a statement, the office of Gov. Haley Barbour said, "Ayrshire Electronics ... is expected to keep 200-plus workers on the job under the umbrella of a new corporate structure and new management effective as early as (today)." ACT put the plant, formerly owned by ITT, up for sale in September. It also closed a site in Hudson, MA. The phone at its San Jose site, the former GSS Array, has been disconnected. Calls to the company's Hudson site were not returned. Ayrshire operates five plants in the Midwest and Mexico. – Mike Buetow

Orbotech Pulling Out of Assembly AOI Biz YAVNE, ISRAEL – Beset by losses, Orbotech (orbotech.com) in mid November announced plans to drop out of the PCB AOI equipment business and reduce its workforce by 15%. Starting in the third quarter, the company began scaling back its activities in the assembled PCB business. By year-end, the company will no longer develop and market assembled PCB equipment, but will continue to service its installed base of products. AOI for assemblies make up a small portion of Orbotech's revenues. Sales for the segment were $3.9 million during the September quarter, down 31.6%. Orbotech reported overall sales of $94.8 million for the period. Among the charges taken by the company were a one-time charge of $5.4 million to write off remaining goodwill within its PCB assembly business, and $3.7 million in restructuring charges. Orbotech also announced plans to cut about 15% of its worldwide workforce in the third and fourth quarters, a 15% reduction in corporate management salaries, smaller reductions in other salaries, and other cost-cutting measures. – Mike Buetow

Nanowires Ideal for EMS, Say Researchers YORKTOWN HEIGHTS, NY – IBM (ibm.com) and Purdue University (purdue.edu) researchers have discovered tiny silicon nanowires might be ideal for manufacturing in computers and consumer electronics because the structures repeatedly form the same way. According to a Purdue spokesperson, the researchers used a transmission electron microscope to observe nanowires made of nucleate. Silicon nanowires form from gold nanoparticles ranging in size from 10 to 40 nm. This is the first time researchers have made such precise measurements of the nucleation process in nanowires, a participating researcher said, according to published reports. The researchers studied silicon; however, the findings could be applied to manufacturing nanowires made from other semiconducting materials, published reports say. Nanowires could aid the semiconductor industry’s ongoing need to place more transistors in smaller spaces. The challenge will be to replace gold with other metals used in electronics, according to the researchers. The National Science Foundation is funding the program. – Chelsey Drysdale

Circuits Assembly DECEMBER 2008

circuitsassembly.com

11/19/08 4:31:55 PM

CA-0812.indb 15

11/19/08 4:31:55 PM

Market

WATCH

Edited by Chelsey Drysdale

More Storage in Store

Gartner: 2009 Semi Growth Just 1%

Trends in the U.S. electronics equipment market (shipments only). ------------- % Change -------------July

Augr

Sept*

YTD

Computers and electronics products

6.0

-5.6

-2.3

0.0

Computers

-2.5

-4.9

-2.2

-6.9 -2.8

Storage devices

-1.6

-8.2

11.6

Other peripheral equipment

-11.2

1.5

1.9

0.2

Nondefense communications equipment

-3.0

-7.5

2.2

-1.3

Defense communications equipment

11.1

-14.2

6.8

24.6

A/V equipment

-3.2

-7.7

2.6

-14.4

Semiconductors

38.9

-18.6

-13.6

-8.4

Components1

-1.9

-0.9

-2.2

-2.6

Nondefense search and navigation equipment

-5.4

0.5

-1.3

0.3

Defense search and navigation equipment

-3.6

1.7

0.8

3.3

Medical, measurement and control

13.4

-1.2

-2.6

11.3

rRevised.

*Preliminary. 1Includes semiconductors. Seasonally adjusted. Source: U.S. Department of Commerce Census Bureau, November 4, 2008

October Manufacturing Reaches New Low TEMPE, AZ – The manufacturing sector in October failed to grow for the third consecutive month, says the Institute for Supply Management (ism.ws), while the overall economy concluded 83 consecutive months of growth. The manufacturing PMI dropped to 38.9%, a 26-year low. A reading above 50% indicates expansion. It was the lowest level for the PMI since September 1982, when it registered 38.8%. New orders fell 6.6 points to 32.2%, while production plummeted to 34.1%, down 6.7 points. Export orders contracted for the first time in 71 months. Backlogs dropped to 29.5%, down 5.5 points. “The PMI indicates a significantly faster rate of decline in manufacturing when comparing October to September. It appears manufacturing is experiencing significant demand destruction as a result of recent events, with members indicating challenges associated with the financial crisis, interruptions from the Gulf hurricane, and the lagging impact from higher oil prices,” says ISM spokesperson Norbert J. Ore. “We see inflationary pressures dissolving as the prices index fell to 37%, the lowest since December 2001 when it registered 33.2%.” June

July

Aug.

Sept.

Oct.

PMI

50.2

50.0

49.9

43.5

38.9

New orders

49.6

45.0

48.3

38.8

32.2

Production

51.5

52.9

52.1

40.8

34.1

Inventories

51.2

45.0

49.3

43.4

44.3

Customer inventories

55.0

47.0

54.5

53.5

55.0

Backlogs

47.5

43.0

43.5

35.0

29.5

STAMFORD, CT – The economic crisis is having a significant impact on the semiconductor industry, as worldwide semiconductor revenue growth in 2009 is expected to be 1%, down approximately seven points from previous estimates, says Gartner Inc. (gartner. com). The research firm lowered its previous 2009 estimate of $307.7 billion, up 7.8% from 2008, to $282 billion, up 1%. Semiconductor revenues grew 5% quarter-over-quarter in the September period, but fourth-quarter guidance continues to drop. Gartner estimates worldwide semiconductor revenue in 2008 will total $279.4 billion, up 2%.

Report: Communications Production Halved this Year LOS ALTOS, CA – Although capital investment outlays will slow, the communications equipment industry will survive the economic downturn in reasonable shape, says Henderson Ventures (hendersonventures.com). Worldwide equipment production will slow from a 6.8% rate in 2007 to a 3.2% pace this year, according to the research firm. Growth will drop 2.7% next year before rebounding to 9.6% in 2010. China is expected to achieve a solid 9.6% gain this year. Even so, that pales before the 19.8% burst chalked up during 2007, says Henderson. The company says the diminishing unserved cellphone market coupled with the poor economic environment will likely result in a drop in new subscribers. Unit growth is predicted to drop from 15.1% in 2007 to 7.8% in 2008 and 3.9% next year.

Down Market Could Boost EMS EL SEGUNDO, CA – EMS and ODM firms will continue to grow, albeit at a slower rate, during the current recession. In fact, research firm iSuppli (isuppli.com) believes a recession may offer opportunities, pointing to the 2001-2003 recession, when a “rubber band effect” stimulated significant revenue growth for EMS/ ODM firms emerging from the downturn. Top ODMs increased their annual sales from $12 billion to $37 billion during 2001-2004, while EMS providers had a CAGR of 11% during the period.

Source: Institute for Supply Management, Nov. 3, 2008

Metals Index

Industry Market Snapshot

Price Per Lb.

Book-to-bills of various components/equipment. May Semiconductor equipment1

June

July

Aug.

Sept.

0.78

0.81

0.83

0.81r

0.76p

4.18%

5.91%

7.11%

7.02%r

4.82%p

Rigid PCBs3 (North America)

0.95

0.94

0.94

0.95

0.96

Flexible PCBs3 (North America)

1.01

1.02

1.01

0.90

0.94

5.08

5.27r

5.34p

Semiconductors2

Computers/electronic

products4

5.07

5.21

Sources: 1SEMI, 2SIA (3-month moving average growth), 3IPC , 4Census Bureau, ppreliminary, rrevised

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Circuits Assembly DECEMBER 2008

Date

11/12/07

8/4/08

9/8/08

10/6/08

11/3/08

LME Cash Seller and Settlement for Tin

$7.64

$9.84

$8.68

$7.69

$6.35

LME Cash Seller and Settlement for Lead

$1.58

$0.98

$0.84

$0.76

$0.66

Handy and Harman Silver (COMEX Silver)

$215.79

$253.83

$184.48

$160.20

$144.40

$3.07

$3.67

$3.17

$2.70

$1.80

LME Cash Seller and Settlement for Copper

circuitsassembly.com

11/19/08 4:31:56 PM

Why Pride and Outsourcing Don’t Mix

Global Sourcing

Root problems tend to be everyday business issues. So why do some parties give up? any of the less successful electronics manufacturing outsourcing relationships at their core have problem behaviors very similar to the age-old character flaws known as the Seven Deadly Sins. In the old days, when good character was considered an essential part of civilized behavior (and was that such a bad thing? Listen up, bankers!), a helpful mnemonic device was designed to help us remember what to avoid: SALIGIA. As explained in our October column, SALIGIA is derived from the first letters (in Latin) of the Seven Deadly Sins: 1. Superbia (pride). 2. Avaritia (greed). 3. Luxuria (lust). 4. Invidia (envy). 5. Gula (gluttony). 6. Ira (wrath). 7. Acedia (sloth). It is our contention that each of these sins has an analogous bad behavior in outsourcing that leads to failed cases, as outlined in Table 1. This month we are focusing on the first, and arguably most destructive, of the problem behaviors: pride/ self-righteousness. Known in Greek drama as hubris, it has led to many an heroic downfall. Our company tracks a wide spectrum of actual electronics manufacturing programs of all sizes in a variety of end-markets. The failures are most instructive. And we have found the root cause of most failures is Superbia, or pride/ self-righteousness. Failed outsourcing programs are expensive. It can cost millions to change EMS suppliers. When we interview management teams on both sides to determine what went wrong, we often find that at some point in the relationship, the parties just stopped communicating. Typically, nothing else changed: the capabilities and expertise of the EMS provider, the projected market, the IP that drove the potential success of the product – none of these basic elements changed. But communications simply broke down about the everyday issues or practice of doing business because of pride/ self-righteousness on the part of one or both parties. Since the two parties in an outsourcing relationship are business entities, presumably their primary reason for existence is to make money. If true openness and humility were practiced, solutions could be worked out that would enable reasonable margins and profitability on both sides. Yet that’s not what we hear from our clients. Usually the OEM will say things like, “They have just nickled and dimed me to death.” Or the EMS

M

circuitsassembly.com

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Table 1. ‘Sins’ and Virtues of Outsourcing Deadly Sin

Outsourcing Equivalent

Holy Virtue

Outsourcing Equivalent

Superbia (pride)

Selfrighteousness

Humility

Openness

Avaritia (greed)

Asymmetry

Liberality

Reciprocation

Luxuria (lust)

Lavishness

Chastity

Conservation

Invidia (envy)

Imitation

Kindness

Innovation

Gula (gluttony)

Gamesmanship

Temperance

Restraint

Ira (wrath)

Impatience

Patience

Resolution

Acedia (sloth)

Apathy

Diligence

Consistency

will complain the OEM is requesting continuous cost reductions when direct costs are increasing. More often than not, the root problems tend to be everyday business issues that are the same for everyone, and presumably are solvable. Yet in the failed cases, the parties simply just give up. Sometimes the parties give up long before the relationship formally ends, because material liability or other contractual issues prevent them from walking away when things start to get rough. The failure (lack of communication) gets more catastrophic – even though in most cases it was entirely avoidable if less ego (pride and self-righteousness) were the order of the day. Case in point: In discussions with an OEM – a litany of complaints was unleashed about the EMS supplier’s incompetence regarding a particular issue or problem. One specific detail was in dispute, but the OEM thought the EMS should have known a key fact that would have made it clear what the OEM expected. When we asked the OEM if they had communicated the expectations to the “clueless” EMS, the OEM said, “Yes.” They distinctly remembered a time when the EMS firm had proposed a solution, the OEM had “raised an eyebrow.” When asked why they hadn’t simply explained what they expected or wanted to solve the problem, the OEM blustered something like the EMS “should have known,” and changed the topic. It’s that kind of gamesmanship that arises from pride and self-righteousness. Behavior like that has a tendency to eat away at perfectly good business relationships, and the result tends to be damaging and expensive. Transparency, openness and truthfulness, arising out of humility, lead to much more profitable and successful outsourcing programs and relationships. Just think what a wonderful place the economy would be in if we had seen a little of that in the financial industry. n Circuits Assembly DECEMBER 2008

Jennifer Read is cofounder of Charlie Barnhart and Associates (charliebarnhart.com); [email protected]

17

11/19/08 4:31:58 PM

Screen Printing

A Simple Economic Stimulus Package Inspection can reveal post-print problems or help analyze DoEs. t’s as predictable as the sunrise. When the economy struggles, efforts to optimize line yields and reduce manufacturing costs become, well, let’s just say a bit more intense. I’ve been through many a slow cycle, and the cost-cutting pattern repeats with each economic swing. This behavior, while understandable and necessary, is also a little curious, as many of these measures should probably be employed as normal practice regardless of the macro economy. Process optimization tenets are something I shout about constantly and, apparently, sometimes my enthusiastic ramblings have fallen on deaf ears. But, these auditory channels are now remarkably keen to hear what can be done to maximize resources. In the case of screen-printing, that means getting the absolute most out of your machine. For the past five or six years, electronics assemblers have installed a plethora of new SMT lines to achieve required volumes. (Don’t get me wrong; I’m not complaining, as we have all benefited.) What happens, unfortunately, is that in an effort to reach certain volumes, sometimes quantity – not necessarily quality – becomes the driving force. It’s not to say manufacturers are putting out sub-par products. They’re not. But what has been happening is first-pass yields have suffered, with some firms running at sub-80%. That’s a lot of money wasted and that’s where screen-print optimization can pay dividends. If you consider the cost of an assembly increases logarithmically as the board travels down the line, when you start putting on chips, reflowing and testing, then printer investments include the cost of the bare board, solder paste and stencil. Relatively speaking, the assembly value at the printing phase is at its lowest. If you can capture any problems coming in before or after the print, then it will save you a heap of money down the line where, at best, any mistakes will be found by test and, at worst, discovered by a consumer. Taking some time upfront to fully analyze a new product run – or even an existing one that’s not up to par – can go a long way toward saving significant costs. It’s a fairly simple proposition when employing productivity enhancing tools available with many screen printers. One such tool is 2-D inspection, which offers a two-fold solution: use as a production tool (its

I

common function), or as a useful aide for Design of Experiment (DoE) exercises to optimize the process. The DoE route is what we recently took with a manufacturing operation that was experiencing some issues. A customer was manufacturing an assembly that had a CSP placed right next to a large RF shield. As we’ve discussed in this column (“Heterogeneous Assembly,” September 2007), optimizing heterogeneous assemblies is essential in today’s miniaturized world. Because of the large component, a goodly amount of solder paste had to be deposited to ensure a robust solder joint. But, when placed next to the fine-pitch CSP, this customer’s current process wasn’t cutting the mustard, and the small CSP deposits were struggling to release from the stencil. The customer’s inspection equipment was indicating major fails on the CSP. Using 2-D technology, we took the customer’s multi-board panel and created a few different stencil/paste volume scenarios to analyze which architecture yielded the better result. After about an hour’s time running that board, we had enough data to predict which stencil design would produce the best results. By slightly enlarging the CSP apertures so as to take them to the aspect ratio limit, we were able to solve the problem, and this customer’s process was suddenly running at much higher yields, and therefore much more cost-effectively. While inspection can output production data on post-print problems or help analyze DoEs, it can also shed light on and accurately set other critical printing inputs such as cleaning frequency, print speeds and pressures. If you’re cleaning too early, you’re wasting money. If you clean too late, you may potentially be sending defective boards down the line. 2-D inspection can indicate where certain areas of the print are out of control, help determine inadequate or excessive tooling, evaluate whether print pressures are too high or too low and so on. Driving your printing equipment to reduce production costs isn’t difficult. The tools are there and, if you just use them, you’ll realize a very fast financial return on your investment of time. It’s a lesson particularly relevant for today’s economic situation, but one that should be employed even when the economy is humming. n

Inspection sheds light on print, cleaning, speeds and pressure.

Clive Ashmore is global applied process engineering manager at DEK (dek.com); [email protected]. His column appears bimonthly.

18

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Circuits Assembly DECEMBER 2008

circuitsassembly.com

11/19/08 4:31:59 PM

A Few of My Least Favorite Things

Better Manufacturing

The industry’s leading curmudgeon is back and ornery as ever. Ed: It’s December and the weather is turning cold in many parts of the land. Who better to warm things up than our favorite industry curmudgeon, Dr. Helmsley J. Zapfardt III?

ike a tented via with flux trapped inside, I have to vent. Hey, a little outgassing can be a good thing. Here are a few things that really pull my rickshaw.1 Egomaniacs. We love going to conferences. But our craws stick thinking of audience members who ask questions just for the sake of asking questions. What are you, running for office? We’re not going to make the 11 o’clock news. So can we just get on with the talks already? (And no, I’m definitely not referring to the editor of this esteemed publication. I need this job.) Industry awards. Your product has won an “important award.” Hoo-hah! But just how did you win this prestigious prize? Was it through innovation, global recognition or forward vision? Or was it – and this is a rhetorical question – that entry fee you paid? Whatever happened to the Malcolm Baldridge Award? That was a truly coveted award, one that spoke volumes about a company. Accordingly, very few earned it. Our industry seems a little looser with the judging, if you ask me. Well, at least those trophies look good in the lobby. I say save your money and put it toward something useful, like R&D. Unsupported equipment. Hey, that was one heckuva deal you got on that new wave solder machine. It was made in China and bears a remarkable resemblance to a higher-cost Euro-American-Asian machine in features, industrial design, even graphics. But from whom did you actually buy it? How long have they been “distributing” this brand of machine? Did you buy it from a catalog or on the Internet? Are they specialists in wave soldering, or do they also sell microscopes or catapults? In fact, as you read this, are they still distributing it? Further, where are you going to get service and applications support? To be honest, I’ve seen some pretty good knockoffs of wavesolder machines and reflow ovens coming from China; they’re relatively good at cloning these. But unless you’re incredibly self-sufficient, you need to depend on local applications, training and service support. Yet, once that crate leaves the People’s Republic, you are often on your own. So much for that bargain. You wouldn’t buy a car under these conditions, so why stake your production line, your company and your reputation on a piece of process equipment purchased that way? Advertising in movie theatres. Nothing to do with our industry, but it jerks my chain that, after paying over $10 a ticket to see “Mama Mia”2 I have to sit through the same stupid advertisements for cellphone service, cars, video games and other crap I can see for free at home on TV.

L

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CA-0812.indb 19

You can keep the Coming Distractions, but get rid of those damn commercials and bring back some good cartoons (showing my age here). Bluetooth sanctimonia. You see these jerks everywhere: downtown, airports, etc. Mostly male, they walk around oblivious to the world with their Bluetooth devices in their ears, talking loudly and looking sanctimonious and important, like cyberheads with high-tech earrings. Annoying! Cellphone distractia. Technology can be a wonderful thing and what our industry has accomplished in telecommunications is nothing short of a marvel. Cellphones and PDAs are, for the most part, a wonderful technological contribution (except for those aforementioned Bluetooth dingdongs). But cellphone use and automobile driving is a bad combination. So is texting while driving a car, truck or train. Hang up and drive! Counterfeit components. You thought RoHS was a crisis. Ha! Compared to the new plague upon our industry, Pb-free conversion is a minor annoyance. Welcome to the scary world of counterfeit components – already in a product near you. It has been estimated that 12 to 14% of electronics products in the field contain counterfeit components. And not just cellphones, PCs and TVs, but highrel products, including automotive, avionics and medical devices. According to the head of research for Naval Air Systems Command’s Aging Aircraft Program, “up to 15% of all spare and replacement components purchased by the Pentagon are counterfeit.”3 In most cases they resemble the “real” component in every detail, including logo and serialization. But they are bogus and will not function as their real counterparts, assuming there is anything in them at all. They’re manufactured everywhere, from “real” factories with “fourth shifts” to back-alley hovels with blacked-out windows. And they include everything from expensive ICs and memory devices to passives. We heard of one case where what the assembler thought were tantalum capacitors didn’t contain tantalum (which became apparent during burn-in). Why, you ask, would anybody counterfeit a $3 component? It’s like counterfeiting $1 bills. Because it was an order for two million parts. We’re talking about an industry worth $10 billion – and growing. Gather all the information and learn what you can. And be afraid, very afraid. n

Dr. H.J. Zapfardt is a member of the National Academy of Arrogant Engineering and an inductee of GIT’s International Hall of Fame. He is a sought-after advisor to industry and government, or basically anyone who will put up with him. A popular speaker on the SMT “rubber chicken circuit,” he was recently cited as “a personality to avoid.” He has written more than 300 articles and textbooks, including the acclaimed A Children’s Garden of Flux. Dr. Zapfardt holds a doctorate in metaphysics from the University of Bonghit; [email protected].

References 1. This is a common colloquial expression and not a socioeconomic statement concerning our trading partners in Asia. (That will come later.) 2. A funny movie, although no one admits to having liked ABBA. 3. Brian Grow, et al, “Dangerous Fakes,” BusinessWeek, Oct. 2, 2008.

Circuits Assembly DECEMBER 2008

19

11/19/08 4:32:00 PM

Cover Story

The Plexus Rx For its operational excellence and financial performance, Plexus is our first EMS Company of the Year. By Mike Buetow manufacturing technology and quality Steve di Loreto says. “From uick: Name the best-performing publicly held EMS comwomb to tomb, plus after-market services and end-of-life. There pany. Jabil? Not anymore. Benchmark. Wrong again. Flexare a lot of aspects to it.” tronics? Not even close. Overseeing the vast terrain, customer manager (CMVP) runs That would be Plexus. teams made of not just program managers but supply chain manThe 28-year-old EMS company has shown gross margins of agers and scheduling and production engineers, all of whom may 10.9% over the past three years and a compound annual growth directly interface with a customer. This alignment pushes execurate of 14.4%. This despite having what in some circles would tion to the site level, Plexus believes. The CMVPs act as farmers, be considered excessive overhead: too many engineers and a footprint heavy on North American operations. Yet, in this era, where it seems the only solution is a “China solution,” Plexus stands as one of the few billion-dollar EMS players that can afford such a setup. One reason is the company’s heavy drive to sell end-to-end services. “We focus on broad service offerings and points of engagement (with customers),” explains Mike Buseman, senior vice president of global manufacturing Figure 1a. Plexus Building 5 once had a traditional setup. operations. Engagement starts upfront (to say the company emphasizes design would be an understatement: Plexus’ Technology Group has some 350 design and test engineers) and continues through procurement, supply chain management, assembly, test and box build, with a hard push ongoing in the backend and chassis build, followed with direct ship to OEM customers and follow-on field services. “It’s more complex than people appreciate,” vice president of Figure 1b. Today, the site emphasizes workcells and modularity.

Q

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Circuits Assembly DECEMBER 2008

circuitsassembly.com

11/19/08 4:32:26 PM

Cover Story nurturing the accounts, while market sector VPs (MSVPs) are the “hunters,” working closely with customer managers to refine service and support needs and define market opportunities. Those hunters have been working overtime. For its fiscal year ended Sept. 27, Plexus’ revenue jumped 19% to $1.84 billion, bringing its five-year organic revenue CAGR to 18%. The return on invested capital was 20.1%. Yet for a company whose revenue has grown $600 million over the past three years, the customer base is practically going the opposite direction. The big switch came in 2003, after Plexus recorded a net loss of $68 million. The number of customers dropped from 238 in fiscal 2002 to 107 in fiscal 2006, when it recorded sales of $884 million. The sales per customer, however, jumped almost fourfold to $13.3 million during that time. Today, Plexus is on track to generate an average $14.1 million per customer, based on about 131 accounts, primarily in the networking, wireless infrastructure, defense and security, aerospace, and of course, medical sectors. Growth has traditionally been organic, not via acquisition. Stanford professor and business author Jim Collins, who teaches focus and execution are keys to long-term success, is a strong influence, company executives say. Like Jabil and Benchmark, and unlike most other large Tier EMS players, the majority of Plexus’ manufacturing space remains in North America, where it hosts seven of its 13 sites (not including the just-shuttered plant in Ayer, MA). About 56% of the company’s 2.1 million sq. ft. of plant space is in the US and another 5% in Mexico, versus 35% in Asia and 4% in Europe. And most of the Asia capacity is not in China but in Malaysia, where the firm has 696,087 sq. ft. across three sites. Plexus signed a lease in September to bring a plant online in Hangzhou, its second in China; the additional 106,000 sq. ft. will bring its Asian footprint to 948,000 sq. ft. Production is expected to begin late in January 2009. Relative to other top-tier EMS companies, Plexus’ disinterest in China is noteworthy. Why hasn’t Plexus followed the herd East? Ultimately, the mix didn’t match the locale. While every Top Tier EMS firm was under pressure from customers and Wall Street to offer a China "solution," for a low-volume, high-mix company like Plexus the math doesn't always work. Several competitors suffered deeply trying to establish local supply chains in Southeast Asia. Plexus navigated those obstacles with the skill of a brain surgeon, focusing on more established, lower risk areas like Malaysia. As logistics and other costs rose, the EMS firm looks more and more prescient. Over time the trend for products where IP protections are paramount or end-product weight is a factor – in short, Plexus’ main markets – has become to build product close to where it will be consumed, putting Plexus in a great competitive position. “We really need to think about the customer,” adds Kirk Van Dreel, global process owner, PCBA. “You can sacrifice customer service [when you move programs around] if not managed and executed effectively. We utilize a dedicated transition team and process to ensure we maintain customer service levels during these types of transitions.” Expansion is inevitable, although the locations being considered aren’t so easily predictable. Besides the new factory in Hangzhou, Plexus is considering various sites in Eastern Europe circuitsassembly.com

CA-0812.indb 21

and perhaps additional capacity in Mexico. Romania, Poland and Slovakia are current contenders, while the Czech Republic has been ruled out as “overbuilt.” Says di Loreto, “We’re walking the balance between where labor is low cost – but not the lowest – but focused on customer service.” The company estimates a worldwide footprint of 2.6 million sq. ft. by 2012, up about 44% over 2007. Embedded in that estimate are 250,000 sq. ft. in Eastern Europe and 1.4 million sq. ft. in Asia-Pacific. South of the border, some longtime employment struggles have been worked out. Turnover has dropped from 10% per month to 1%. A decision will be made in the next six to 12 months whether to add capacity in Mexico, di Loreto says. It very well may be that placed programs tend to stay in one spot. But at Plexus, designs fly around the globe. Over the course of a day, the company has in-process coverage for about 20 hours, six to seven days a week. ASIC designs have given way to FPGA, primarily Xtera and Xilinx. Libraries are designed to retain customer “building blocks” to encourage design reuse. The smallest piece would be component footprints and geometries. On top of that would be process and DfM guidelines. The next level of reuse is more of a fine line. “We looked at it from a technical and legal standpoint to be able to reuse these [process technology] building blocks without getting into confidentiality problems. We don’t cross-pollinate engineers,” says Van Dreel. Design teams are kept

Circuits Assembly DECEMBER 2008

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11/19/08 4:32:28 PM

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11/19/08 4:32:29 PM

Cover Story

Figure 2. An SMT line at Plexus' Neenah campus.

Figure 3. A subassembly line in Building 5.

separate to ensure the security of customer IP. “We pride ourselves on keeping that information separate.” Reuse is important to the medical OEMs that make up more than 20% of Plexus’ annual sales. (Plexus has a long history as an EMS to medical OEMs, although Juniper Networks is the firm’s largest customer, at 19% of sales.) These OEMs take the platform approach whereby a concept can be leveraged and reused across various products. Test strategies are a collaborative effort between manufacturing engineers and customers, as well as the test equipment OEMs. The Plexus workcell approach is a sight to behold. Don’t expect long, parallel SMT lines. In Building 5 at the company’s Neenah, WI, headquarters, the layout is such that within the 100,000 sq. ft. manufacturing plant are four distinct factories – each complete with an SMT line (Figure 1). (Staff must swipe their employee badges before passing ESD testing and entering the factory floor, only the second time in 17 years I’ve seen that clever setup.) Inside, banners outline each “factory’s” borders. “We blended a dedicated factory with a cellular model,” explains Kim Debenack, engineering manager. “This model makes us less rigid because we can run product anywhere, on any line. What we are going for is product velocity, not just velocity of placement.” Building 5 handles 10,000 part numbers across five to six customers, at a rate of 15,000 assemblies per month. Nearly everything built is a system with direct order fulfillment. Debenack says board build cycle time has dropped to two days from 21 since this novel setup was implemented several years ago. A separate focused factory is integrated into Building 5 to handle repair services. Adds Buseman, “We’re looking at what the next level of service would be.” Process optimization across Plexus’ far-flung operations is driven by Van Dreel. Twice a year, he organizes summits involving representatives from engineering and quality. The group has two goals: to prioritize needed activities and processes, then formalize them into projects and execute them around the globe. Flexibility is key. The number of engineering change orders in Building 5 tops 100 per month. The Neenah site uses DEK printers, Universal placement, Electrovert reflow, Vitronics Delta-Max selective solder, Agilent 3070 and Teradyne test equipment. Oracle

and Agile ERP systems, coupled with homegrown MES tools, round out the picture. The organic supply chain management tools develop sourcing solutions based on such factors as component cost, variability and lead times. Equipment evaluations are performed all over the world. However, there is limited variation from plant to plant. For example, Plexus’ Buffalo Grove, IL, site uses Assembléon A5 placement

circuitsassembly.com

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Mission Possible. Versatility that beats complexity. It’s not just a promise, it’s a fact! assembleon.com/facts

assembleon.com/facts

Circuits Assembly DECEMBER 2008

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11/19/08 4:32:30 PM

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11/19/08 4:32:36 PM

Cover Story

Figure 4. Vertical storage units adjacent to SMT lines support full lineside stocking for Lean manufacturing.

machines. Assessments are conducted every three years on where Plexus’ key markets are headed and the types of equipment needed to stay in step. Keeping with the site model, each factory develops its own value stream fashioned by data from on-time deliveries, labor contribution, cycle time, overall equipment effectiveness (OEE), and defects per million opportunities (DPMO). Plexus manages its own raw material inventory, with each factory determining what’s ideal for its flow. To shorten cycle time, 85% of parts are kept line-side (Figure 4), with 80 to 90% of all parts stocked dock-to-stock. Parts are bar coded and set up offline. The factory averages five to six changeovers per line per day, taking less than 60 minutes per line on average. “Nearly all of what we build, we also configure and test before we ship,” says Debenack. Building 5’s on-time delivery on several DOF product lines: 99.8%. Customer visibility into the factory is linked to demand and flow. Customers can view inventories and processes, and can get data, as desired. Lean plays heavily into the Plexus model. According to Debenack, Building 5 performs a minimum of 32 Kaizen events per year, with teams crossing operational and functional lines. Bulletin boards showing the status of active programs are placed on the factory floor and in the corporate buildings. All associates are trained in Lean techniques, and all salaried employees are Yellow belts. “We want everyone to understand the tools,” says di Loreto. “And we get everyone focused on the business, not just what they are building that day.” Failure analysis is conducted in two locales: Neenah and Penang, Malaysia, where the Plexus campus houses its largest building, at some 400,000 sq. ft. Future developments may include micro-engineering (“microE,” in Plexus parlance), or packaging. Says di Loreto: “We see some potential for micro-E. Bumped die is becoming more mainstream, and I think engineers will glom onto that.” He says better understanding of miniature solder structures of tiny chips, including 01005s, is needed to mainstream new micro technologies like 01005s and system-in-package solutions. Over the past three years, Plexus has done a superb job at forging its own path for success. For its sustained performance, financircuitsassembly.com

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Figure 5. Workstations adhere to "5S" protocols and have online documentation.

cially and operationally, and its forward-looking strategy, Plexus is Circuits Assembly’s first EMS Company of the Year. n Mike Buetow is editor in chief of Circuits Assembly; [email protected].

Mission Possible. Versatility that beats complexity. It’s not just a promise, it’s a fact! assembleon.com/facts

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Retrospective

In Memoriam Remembering friends and colleagues who passed away in 2008.

Les Hymes was one of the pioneers of surface mount, and cowrote several industry standards.

Sean McShefferty was a beloved fixture around the industry for two decades.

e it in global matters like finance and politics, or in more regional events within our industry, 2008 will be remembered as a year of transition. CirCuits Assembly would like to reflect on some of our friends and industry colleagues who helped get us where we are today, but sadly won’t be with us to witness the next chapter in our industry’s remarkable history. Alden Johnson, 64, former chemical and metallurgical engineer, Speedline Technologies. Sean McShefferty, 48, national sales manager, Kyzen Corp. Ed Turney, 79, cofounded Advanced Micro Devices. Les Hymes, 77, SMT specialist with GE Medical Systems and Plexus, and author. Marty Heimer, 44, program manager, Benchmark Electronics. Norbert Socolowski, 85, longtime Alpha Metals chemist and inventor. Richard I. Hustvedt, 62, computer software engineer at Digital Equipment Corp., original architect of the VAX/VMS operating system.

B

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Circuits Assembly DECEMBER 2008

Norb Socolowski (at left, shown receiving an award from the late IPC chairman Peter Sarmanian, and below) said he could distinguish solders by how the flux smelled. He was the first president of the SMTA, and received that organization's Founder's Award in 1998.

circuitsassembly.com

11/19/08 4:32:48 PM

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Atlanta Office: 3030 Business Park Drive, #3030-B Norcross, GA 30071 Phone: (770) 446-3116 Fax: (770) 446-3118

11/19/08 4:32:48 PM

Solder Joint Reliability

L

A

HIP Defects in BGAs A study shows two significant factors are solder paste flux chemistry and BGA alloy ball wetting. By Karl Seelig ead-in-pillow (HIP), also known as head-on-pillow or ball-in-socket, is a solder joint defect in which the solder paste deposit wets the pad, but does not fully wet the ball. This results in a solder joint with enough connection to have electrical integrity, but lacking sufficient mechanical strength. Because of the lack of solder joint strength, these components may fail under minimal mechanical or thermal stress. This potentially costly defect is not usually detected in functional testing, but rather shows up as a field failure after the assembly has been exposed to physical or thermal stress. HIP defects have become more prevalent since BGA components have been converted to Pb-free alloys. The defect possibly can be attributed to a chain reaction of events that begins as the assembly reaches reflow temperatures. Components generally make contact with solder paste during initial placement, and start to flex or warp during heating, which may cause some individual solder spheres to lift.

H

 

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Figure 1. SAC 305 with SnAg intermetallic and coarse grain structure that leads to fractures during drop.

Circuits Assembly DECEMBER 2008

This unprotected solder sphere forms a new oxide layer. As further heating takes place, the package may flatten, again making contact with the initial solder paste deposit. When solder reaches the liquidus phase, there isn’t sufficient fluxing activity left to break down this new oxide layer, resulting in possible HIP defects. Since component warpage is unpredictable and inconsistent, the focus must turn to the interaction of process variables and those that can be altered to reduce the incidence of HIP defects. These variables include BGA ball alloy, reflow process type, reflow profile and solder paste chemistry. Each of these variables is studied and discussed below. With the need for better drop resistance, many Pb-free BGAs are being made in alloys other than SAC 305. Because SAC 305 has significantly lower drop resistance than SnPb37 (Figure 1), component manufacturers have been moving away from this type of alloy and toward alternatives such as SAC 105 (composed of tin plus 1% silver and 0.5% cop-

  Figure 2. Further inspection shows grain

structure differences and chemical composition differences. circuitsassembly.com

11/19/08 4:32:51 PM

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Solder Joint Reliability

Table 1. Relationship Between Certain Variables and HOP Variable (s)

Impact

Reflow profile

1

BGA ball alloy

4

Reflow profile plus BGA ball alloy

4

Solder paste chemistry

8

Solder paste chemistry plus reflow profile

8

BGA ball alloy plus solder paste chemistry

10

 

Figure 4a. EDS spectrum no.1, shiny ball of BGA 1 (Sn and C).

 

Figure 4b. EDS spectrum no. 8, matte ball of BGA 4 (Sn, Si and C).  

 

 Figure

3. BGA (top), b) matte BGA (middle) and c) spotted BGA (bottom).

per). Many varieties of SAC 105 include a fourth element, often referred to as a dopant, such as antimony, magnesium, nickel, cobalt or indium. These additives create finer grain boundaries and reduce the intermetallic formations of the tin with silver or copper, resulting in a more reproducible grain, as well as a more uniform grain formation in the Pb-free alloy. These also yield a different oxide and surface condition, depending on the element used and cooling rate during assembly. This different oxide and surface condition can cause issues with the flux activity and impact solder wetting and complete joint formation of the BGA. Solder sphere (ball) issues. Figures 2 and 3 are analyses of BGAs known to have had HIP problems. Using SEM, it was determined there are very distinct grain structure variations within the balls (Figure 2). Inspecting these components reveals three distinct classifications of balls on the component; these were labeled shiny, matte and spotted 30

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Circuits Assembly DECEMBER 2008

 

Figure 4c. Spotted with Sn, Ag and C.

(Figure 3). (As a point of clarification, the large dimples on the ball surfaces are from test probes that easily penetrated any of the surface irregularities or containments during component testing by the manufacturer.) The spectrums of the BGA balls also are different (Figure 4). On this single BGA there exist three different grain structures and surface elements. One theory explains this is caused by variations in cooling rates when the solder ball was initially formed. We developed a test procedure to understand the interaction of these elements with specific paste chemistries. This permitted a classification of reactivity levels of some of these dopants. It was discovered very low levels of magnesium (in the 30 ppm level) directly affect standard solder paste flux chemistries, while indium affects them in the 500 ppm range, nickel and cobalt in the 400 ppm range, and antimony in the 1000 ppm range. Although the grain structures all circuitsassembly.com

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Solder Joint Reliability

 Figure 6. A HOP defect formed using a lowtemperature activation system.

 

 

Figure 5b. Void-reducing profile for Pb-free pastes with BGAs and CSPs.

Figure 5a. Ramp-soak-spike recommended profile.

appeared similar, the flux interaction was different. This difference was determined by a viscosity test conducted while the paste medium was in contact with the solder alloy doped with the aforementioned elements. Other factors that appear to influence HIP include types of reflow, reflow profiles and solder paste chemistry. 1,2 Some data obtained suggest vapor phase reflow may result in more HIP defects than convection reflow. It is not clear whether this is truly related, however, as it has only been seen as a trend. An experiment was performed to measure the impact of reflow profile on HIP solder joint formation. The experiment utilized two different reflow profiles. The first profile was a standard ramp-soak-spike (Figure 5a). The second profile (Figure 5b) included a hotter soak zone and longer dwell time at liquidus. There was no perceived difference in the defect rate, depending on the profile; each resulted in

Figure 7. A joint formed with a high-temper  ature activation system; no evidence of HOP.

random cases of HIP, depending on the component tested. Solder paste chemistry was the next factor tested to determine impact on HIP. During this experiment, it was found solder paste chemistry appears to have the single greatest effect on the HIP defect. When changing from an older Pb-free solder paste to a new higher-temperature activation paste, the defect, in many cases, was eliminated. In other cases, it was more difficult to remove. However, in the experiment run, the solder paste chemistry appears to have the largest impact on HIP. An experiment was conducted using various solder paste chemistries to measure their effect on HIP incidents. It was determined that, regardless of the reflow profile used, the novel solder paste eliminated HIP. Although this solder paste is halidefree, a solder paste containing >0.5% halide also was used in this experiment, and the defect was once again eliminated. Continued on pg. 46

circuitsassembly.com

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Tech Tips

Pb-Free Solder Wetting Tests A novel test vehicle and methodology for solderability evaluations. e recently performed an experiment for a customer interested in comparing Pb-free solder wetting with varying temperature profiles and atmospheric conditions. To deliver an objective measurement of solder wetting (in addition to subjective inspection analysis), a simple wetting indicator pattern was added to the solder stencil in an area with exposed and unused copper on the test vehicle. This pattern comprised two rows of 22 printed solder deposits. Each individual deposit is 0.025" x 0.050". The deposits are paired in sets of two with decreasing gaps among each pair. The gap between each pair is constant (Figure 1). Two rows are included in the pattern to give two replications of the measurement on each test vehicle. This pattern permits two different measurements to be taken from the test vehicles after processing has been completed. The first evaluation is a count of the number of wetting pattern pairs that shorted together during reflow. As each pair of deposits is spaced farther apart than the last, the number of pairs that bridge can be used to compare solder wetting

W

Figure 1. Wetting test pattern (mm).

Figure 2. Post-assembly wetting pattern. The American Competitiveness Institute (aciusa.org) is a scientific research corporation dedicated to the advancement of electronics manufacturing processes and materials for the Department of Defense and industry. This column appears monthly.

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Figure 3. Wetting pattern gap measurement. Circuits Assembly DECEMBER 2008

under different conditions – an increasing number of bridged patterns indicates increasing wetting. Figure 2 shows an example of a wetting pattern after reflow, with four shorted patterns. The second evaluation is a measurement of the gap between the paste deposit pair that is spaced farthest apart. This gap will decrease during reflow as the paste wets to the underlying copper, and thus a smaller gap is an indication of greater solder wetting. Figure 3 shows an example of a paste deposit gap measurement. (Note: The PCB test vehicle was finished with OSP over bare copper, and the gaps were designed with that in mind. Other surface finishes would require gaps of different sizes because of the expected wetting and spread of solder on the particular surface finish.) If all the deposits bridge, the count of bridged deposit pairs is no longer valid as a measurement, and there is no gap to measure between the last pair. For example, an ENIG finish permits solders to wet and spread to a much higher degree than bare copper and would require much larger gaps to produce useable measurements. The solder alloy can also affect that proper spacing of this type of pattern: SnPb solders are generally expected to wet and spread to a greater degree than their Pb-free counterparts. However, when this type of pattern is properly designed for a specific combination of materials and processes, it can be a useful tool for testing the general wetting properties under varying processing environments. This evaluation method can be used on both purpose-built test vehicles and incorporated into an unused area of a production assembly for an easy indicator of the degree of wetting between the solder and PCB surface. n

Free ACI Workshops

ACI this month will sponsor a pair of free workshops. On Dec. 11, ACI will team with Aqueous Technologies, Kyzen and Technical Devices to present the Low Stand-Off Cleaning Symposium. The one-day program includes training on practical approaches in cleaning the z-axis using inline and batch processes. On Dec. 3, ACI will partner with Dage Precision Industries for a special half-day workshop on x-ray inspection criteria and common defect analysis, covering solder-related defects such as head-on-pillow, BGA and substrate opens. Both workshops are free and will be held at ACI in Philadelphia, and lunch will be provided. RSVP to registrar@ aciusa.org or at aciusa.org/workshop.

circuitsassembly.com

11/19/08 4:32:59 PM

Pushing Test and Testability Up the Chain

Test and Inspection

How a grassroots organization can help get managers on board. very company always looks to improve their bottom line, but I would venture to say doing so becomes even more important in times of economic turmoil. In the past few years, companies have embraced defect detection; even prevention and process control have become givens. It is only lately, however, that design for test (DfT) and design for testability are becoming prevalent. Defective products not properly tested because they lacked DfT can cut into revenue generation through slower time-to-market, recalls, rework, extension of the warranty period and premature product termination.1 As a concept, DfT is not new. I would argue, however, the financial upside of these implementations is only now really being acknowledged. For example, we’ve given lip service over and again to reducing returns, yet new examples of products coming out with huge warranty return rates continue to surface. By embracing DfT and testability concepts, these situations would be avoided or, at the very least, reduced. Let’s explore cost, as it is an interesting factor. Let’s say the designer is designing a microprocessor with >1000 pins and choosing not to use boundary scan. Then the in-circuit test system will need a >1000 pin bed-of-nails fixture. Let’s say the boundary scan microprocessor was going to be $50 and the non-boundary scan was $30. The cost savings is $20 per processor, but where does the added complexity from using that >1000 pin fixture and the fixture cost break even? The added cost for the boundary scan processor will pay off (and then some!), but decisionmakers tend to get caught up with initial pricing at the expense of big-picture items such as return over time and return on investment. In fact, this is an issue that faces all

E

Benefits of DfT2

• Reduces the time required to pass the design into manufacturing • Lowers manufacturing cost • Minimizes the design engineer’s involvement in production setup • Improves cross-functional communication and cooperation between design, engineering and manufacturing • Lowers both initial and lifecycle costs • Decreases test times and virtually eliminates harrowing production delays • Guarantees more efficient diagnosis and repair in the field • Provides more accurate diagnostics to the part.

circuitsassembly.com

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test – regardless of quality of the design. Understanding the initial investment will pay off and then some is the concept every inspection and test supplier is trying to demonstrate all the time. At this point, I suspect the test engineers are nodding and saying, “I know all this, but how do I convince management?" and in fact, that’s exactly what needs to be done to make DfT a success. Management teams must embrace the long-term gain (shorter time to market, less warranty return, less rework, etc.). This is one of the main goals of the Testability Management Action Group, or TMAG (tmag4dft.org). Its grassroots efforts are targeting management on all levels to get the message out to positively impact future products. From a practical perspective, what can the average test engineer do? As with anything design-related, one of the biggest drivers needs to be collaboration across organizations. I can remember several examples from when I was a process development engineer where a design came my way for build/test and there were no fiducials on the board, thus eliminating any hope of a robust solder paste or optical inspection. Another example: If a product is designed such that it is to be tested by AXI only, and the designer throws it over the wall to the test group, which in turn expected an ICT implementation, there will be issues that cost money and time. The SMTA (smta.org) has partnered with TMAG and is working on a refreshed Testability Guideline. Be sure you and your design engineers have a working copy. This will prevent simple mistakes from entering in product designs and will permit standardizations that will reduce design time over time. Within these guidelines you’ll find instructions for keep-outs, clearances, tolerances, carrier recommendations, and so on. In general, be proactive. Partner with your design counterparts. Join TMAG and learn how to approach management to sign on the dotted line. Incorporating design for test and testability will bring things further upstream and will standardize on many aspects, thus making the implementation phase easier and more robust. n

Stacy Kalisz Johnson is Americas marketing development manager at Agilent (agilent. com); stacy_johnson@ agilent.com.

References 1. Louis Y. Ungar, “The Economics of Harm Prevention Through Design for Testability,” International Test Conference Proceedings, October 2008. 2. Thomas J. Coughlin, “Designing for Testability… The Technology, the Technique, and the Economics,” July 30, 1996 Web posting, http://members.aol.com/prpca/designof.htm.

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Wave Soldering

Analyzing Pb-Free Defects Using Partial DoE Optimal assemblies don’t come about from drop-in materials replacement. n important step in reducing and preventing defects during soldering is defining the correct process settings. It’s a good practice to design proper experiments and analyze their results to help determine these settings. When the number of test boards and components for experimentation are limited, use of Partial Factorial, Taguchi or Response Surface Experiments makes for a good approach. These techniques permit end-users to understand the process by minimizing time, resources and cost. The objective of these experiments is to determine the factors and their levels that minimize the variation of a product around a target response. The champion settings will result in robust products resistant to change in operational and environmental conditions. The experiment begins with a brainstorming session where the problem is stated; the factors are selected; the measurable output is chosen, and the experimental design is selected. Then the experiment is run and output measured. Data are analyzed and the best settings are identified. It is important to schedule confirmation runs based on the champion settings; if these results are good, the settings can be implemented into production. To illustrate the concept, a Taguchi experiment was used to develop a robust process for Pbfree wave soldering. The control factors selected were solder temperature, contact time, preheat temperature and flux amount.

A

Ursula Marquez de Tino is a process and research engineer at Vitronics Soltec, based in the Unovis SMT Lab (vitronics-soltec.com); [email protected].

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Circuits Assembly DECEMBER 2008

For practical Table 1. Factors and Levels for the Taguchi Experiment reasons, there Level 1 Level 2 Factors Level 3 were no “noise” Solder 250 (A1) 260 (A2) 275 (A3) Temperature (˚C) elements in 1.8 (B1) 3 (B2) Contact Time (s) 4.2 (B3) this experiPreheat ment. The 90 (C1) 110 (C2) 130 (C3) Temperature (˚C) output charFlux Amount 355 (D1) 474 (D2) 639 (D3) (mg/cm2) acteristic was the number of pins without bridges (maximum 200 pins/ board) and through-hole penetration (2 = 100%, 1 = partially wetted, 0 = Figure 1. Taguchi analysis for bridging. Higher scores are not wetted). better. This experiment used an L9 orthogonal array design, which means nine experimental runs with four factors and three Figure 2.Taguchi analysis for through-hole penetration. levels investiHigher scores are better. gated (Table 1). are shown in Figures 1 and Ma te r i a l s used for 2, respectively. In both analythis ex p er i m en t were ses, higher scores meant betSnAg3.8Cu0.7Sb0.25% alloy ter results. (Table 1 also shows with a VOC-free flux (<2% codes used in the graphics.) solids). The test board was For bridging, contact time double-sided (160 x 100 x 1.6 and preheat temperature were mm) with plated through-holes more important, while for and Cu OSP Entek Plus surface through-hole penetration, prefinish. A Delta wave soldering heat temperature was the main machine equipped with a spray contributor. The optimal setnozzle fluxer, three bottom side tings are not the same for bridgpreheaters, and nitrogen was ing and through-hole penetraused. tion. Therefore, some sacrifices Eighteen boards were run must be made. For our analysis, (nine runs with one repetithrough-hole penetration was tion). The results for bridging more important. and through-hole penetration circuitsassembly.com

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The impact of solder temperature was minor relative to its effect on bridging, while for through-hole penetration a higher solder temperature was preferred (275 oC). However, this option could potentially damage components during soldering. Therefore, a solder pot temperature between 265 o and 270 oC was chosen. In addition, shorter contact time yielded better results. This might be attributable to the characteristics of the flux, which were compromised at the higher preheat and solder pot settings. The champion setting was 1.8 sec. In terms of preheating, a setting of 110 oC was the champion for this process. Calrod IR elements were used in the first heating zone, which provided the adequate heat to start the flux activity without forcing the water to boil out. Forced convection heaters were used in the second and third zones to eliminate excess water before entering the solder wave and to inhibit solder balling. For the flux, a wet flux amount of 474 mg/dm 2 was the champion setting. A continuous and uniform spray across the board is essential. Higher settings may cause a droplet bouncing effect rather than improved wetting of the board surface. All these settings were validated with confirmation runs. Reduced bridging and good through-hole penetration were achieved. Optimal Pb-free assemblies are not a simple replacement of fluxes and materials. This review can be done in a proper and fast way by conducting Partial Factorial, Taguchi or Response Surface experiments. The outcome of the experimentation will provide a practical understanding of important factors and settings by using just a small number of test boards, reducing cost and minimizing resource use. n circuitsassembly.com

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Process Doctor

Electronics Residues Testing Methods, Part 2 This month’s analysis: SEM and EDX. Ed.: This continues a four-part series on typical analysis techniques and their pros and cons in regard to understanding electronics residues.

ficult. Because EDX uses a single electron beam to release the elemental shell and bounces this shell to the detector, it will burn through a thin film of organic and ionic residues on the surface of whatever is cut up and placed into the vacuum chamber. Because SEM/EDX is a destructive test – requiring either cutting, coating or scraping – it must be the last test run on the area of investigation. Thin-film materials, such as chloride and sulfate, can be volatilized under sublimation where the thin materials will be carried away in the vacuum and not detected. n

nergy dispersive x-ray spectroscopy (also known as EDS or EDX) is an analytical technique used for elemental analysis or chemical characterization. The elemental matter is hit with charged particles, and EDX analyzes the x-rays emitted. There are four primary components of the EDX setup: beam source, x-ray detector, pulse processor and analyzer. Most often, EDS is part of scanning electron microscope or electron microprobe (Figure 1). A SEM comes with cathode and magnetic lenses to create and focus a References beam of electrons. (It also has elemental analysis capabilities.) A detector converts x-ray energy into voltage 1. Wikipedia. signals; this information is sent to a pulse processor, which measures the signals and passes them on to an analyzer for data display and analysis.1 Applications and limitations. The use of SEM identification of metal elements with only gross high levels of ionic elements. The EDX scan of this contact brush on a motor (Figure 2) shows carbon, oxygen, copper, silver, aluminum (part of the detector), silica, gold (sputter coating to protect and test sample), but it does not show the chloride and succinic acid from a water-soluble flux used to solder wires on the motor and let it flow into the motor. The SEM/EDX analysis shows elemental information, but quantification is dif-  Figure 1. EDS is typically part of a SEM.

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Terry Munson is with Foresite Inc. (residues.com); tm_foresite@ residues.com. This column appears monthly.

 Figure 2. This EDX scan fails to show chloride and succinic acid, which would limit   its usefulness as an analytical tool for process-related residues. 36

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Head-In-Pillow and Hybrid Solder Pastes

Pb-Free Lessons Learned

The HIP epidemic proliferates, but the cure must not create new problems. arlier this year I reported on the head-inpillow epidemic affecting many assembly lines running Pb-free reflow processes (“HOP-ping Mad,” July 2008). I postulated that a combination of circumstances was occurring simultaneously to create this plague: The higher surface-area-to-volume ratios of progressively smaller paste deposits and BGA balls create a higher proportion of exposed (readily oxidizable) exterior solder to (protected) interior solder, which accelerates flux consumption; reflow processes with extended pre-liquidus thermal exposures that also help to exhaust the flux; and Pb-free oxide films that are more difficult for fluxes to break through than SnPb ones. Since those initial observations, reports of HIP defects continue to increase, and not just in Pb-free soldering. My completely unscientific, statistically insignificant polls indicate the incidence of HIP in SnPb processes is also rising. When we remove Pb-free alloy from the HIP equation, we’re basically left with flux exhaustion as the root cause. No-clean fluxes are designed to activate and deactivate under certain time-temperature conditions. If their thermal exposure limits are exceeded, their effectiveness wanes. Whether it’s from running too hot in the soak zone, taking too long to reach liquidus temperatures, or exposing too much surface area to heat and airflow – either from package warpage or questionable stencil design – spent flux is spent flux, and there’s no reviving it. The first line of defense in SnPb HIP should be profile adjustment to limit the thermal energy input, and in the majority of cases, it works. But what if it doesn’t? Luckily, solder paste manufacturers have a solution at the ready – what I like to refer to as hybrid solder pastes. These products are a blend of flux designed for Pb-free solder paste combined with SnPb solder powder. When we bring together the more thermally tolerant (Pb-free) flux with the SnPb powder, voilà! A SnPb solder paste that really can take the heat, so to speak. These hybrid pastes were introduced in 2007 to address mixed metals soldering, primarily for SAC 305/405 BGA balls on SnPb assemblies. The logic behind the blend is straightforward and with obvious advantages: Fluxes devised for Pb-free soldering would better facilitate wetting to Pb-free surfaces than those designed for SnPb alone, and these fluxes

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are sufficiently thermally robust to perform in the top quartile of the SnPb peak temperature range typically associated with mixed metals assembly. Henkel was one of the first to introduce this hybrid solder paste, and according to Dr. Brian Toleno, global director of technical services, the blends were devised specifically to provide increased activity over a larger thermal window. He explains that “the increased activity over a wider profile range permits assemblers to push SnPb’s traditional top-end temperature and time above liquidus limitations, thereby extending the conventional process of solder joint formation to accommodate the differences in the alloys.” Since those first few formulations hit the market early last year, many suppliers have followed suit. Nearly every major player now offers a paste that blends SnPb solder powder with a flux designed for Pb-free. Although the original intent of these products was to facilitate mixed metals soldering, they do provide a seemingly handy solution for problems related to flux exhaustion. Toleno adds, “In the case of head-in-pillow, the increased activity is more effective at penetrating the oxide films, and can substantially increase the probability of forming good, reliable solder joints.” With many of last year’s mixed metals dilemmas now resolved, some suppliers are specifically marketing hybrid pastes as tools to help mitigate HIP defects. When the solder paste supply base introduced these products, I cautioned the higher temperature flux might not be a foolproof drop-in lower temperature SnPb flux. Three performance attributes concerned me, and since then a fourth point of interest has emerged. The initial concerns centered on electrochemical reliability, voiding and intrusive reflow. The latest concern is the inclusion of halogenated materials in flux products. As I described in June 2007, the two most notable risks of hybrid pastes include lower electrical reliability and increased voiding rates (“Lead Spread,” June 2007). A Pb-free flux designed to run in a hotter reflow process may not provide the desired electrical reliability when run in a SnPb process. Recall noclean pastes are designed to activate and deactivate under certain ranges of thermal energy. Running a higher temperature paste may prevent it from burning out prematurely in a hot process, but if it runs Circuits Assembly DECEMBER 2008

Chrys Shea has 20 years’ experience in electronics manufacturing and is founder of Shea Engineering; [email protected].

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Pb-Free Lessons Learned

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on the cool side, it may not be fully deactivated in the reflow cycle, thereby posing a potential reliability threat in service. In the context of mixed-metals systems, the paste flux is exposed to peak temperatures above 220°C for at least 30 sec., relatively close to its design specification. If broadly deployed as a SnPb alternative, however, the probability it is exposed to smaller amounts of thermal energy in the reflow process is much higher. To err on the side of safety, I would suggest subjecting the product to SIR or electrochemical migration tests when processed under the coolest anticipated SnPb profile – with an adequate safety margin – before it is introduced into production. Voiding concerns remain relatively the same whether the paste is used as a vehicle to solder mixed metals systems or to address HIP. For the most part, voids are created when the volatile materials in the flux portion of the paste cannot outgas before the metal melts. A flux designed for Pb-free processing can volatilize and vent until 217°C when used with SAC alloys, but its outgassing paths will close off at 183°C if used with SnPb solders. A faster/cooler profile may permit more gasses to be trapped than a slower/hotter profile, but a paste’s behavior with respect to voiding can be formulation-dependent and difficult to predict. The best thing an assembler can do is run the paste candidate at the fastest/coolest thermal profile they expect to use in production, measure the voiding rates and decide if they are acceptable. The third concern was pin-in-paste processing. If using intrusive reflow processes, examine the ability of the paste overprints to pull back to the PTHs. We know different pastes have different sweet spots in the reflow window with respect to pull back, and users should make sure the candidate hybrid paste will support pin-in-paste without leaving random solder balls on the board. And again, we’re not just looking at the high end of the SnPb window like we were with mixed metals; we’re looking at the whole window if we want to qualify these products for general production use. Finally, the newest worry: halogenated materials in the flux. When I mention halogenated materials, I mean non-ionic halogenated compounds, not the ionic halides we are accustomed to in the world of flux. (Halides make great flux activators because they are keen at reducing metal oxides, and our industry has long-established methods of identifying and communicating their presence in soldering fluxes.) Here, I’m referring to those compounds often used as flame-retardants in all types of electronics components, most notably printed circuit boards, molding compounds and connectors. They are sometimes used in small quantities in soldering chemistries to improve a flux’s survivability under extended therCircuits Assembly DECEMBER 2008

mal stresses. They can be found in both SnPb and Pb-free fluxes, but they are not necessarily required for successful soldering. Some fluxes have them; some don’t. Some have such a small amount that they squeak under the 1500 ppm threshold and are therefore considered halogen-free. Given the thermal sustainability demands put on Pb-free fluxes, they are slightly more likely to contain halogens than their SnPb counterparts. If the assembler has no concerns about halogenated materials, this point is entirely moot. But looking down the road at green initiatives and potential environmental legislation surrounding halogenated compounds, qualifying a new process chemistry that contains these materials may be a decision that could backfire in a few years’ time. And let’s not overlook the public relations implications: Who wants to be the target of a one-sided Internet video that opines a product is not “green enough,” but neglects to mention the often irreplaceable safety factor the halogens provide? The lesson to be learned with hybrid solder pastes is to ask a few key questions prior to making the switch: • Can the Pb-free flux provide the necessary electrochemical reliability when processed on the relatively faster, cooler profiles associated with SnPb reflow? • Will the new SnPb paste create more voids than the incumbent one? • Will the solder coalesce properly in the intrusive reflow process? • Does the product contain any materials that are politically controversial or under consideration for near-term elimination? Hybrid pastes now appear to address two widespread issues for assemblers: improving BGA soldering in both mixed metals and SnPb systems. They show promise for improving yield and reliability, but should not be implemented without due consideration and appropriate testing. As engineers, we must make sure that when we fix one problem, we don’t create another. In other words, look before we leap. n circuitsassembly.com

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White Residue Rings

The Defects Database

What happens when paste residues and cleaning solvents are incompatible? also been through a standard immersion cleanliness s debuted in these pages last month, the National testing process for ionic residues. Some combinations Physical Laboratory’s new interactive assembly of paste residue and cleaning soland soldering defects datavents are not compatible and leave base lists problems and solutions. a white- or brown-like dust on the The database permits searching and board surface. In this case, the comviewing of countless defects and bination of 75% IPA and 25% water solutions. Users also can submit has failed to dissolve or displace the defects online for recommendations residues from around the base of at http://defectsdatabase.npl.co.uk/. the ball and pad interface and creThis month we feature one ates a most interesting image. recent submission: white residue This issue was only seen on a rings on BGA joints. All BGA solder few boards intended for a consumer joints featured a white ring around Figure 1. Following Pb-free reflow, application, and as such, there was each ball termination. The ring was solder paste residues can form white no specific corrective action. The perfectly formed and not like nor- residue rings on BGA joints. paste was a no-clean material; the mal white residue often seen from a cleanliness testing was just part of a process evaluation standard cleaning operation (Figure 1). and created these unique rings that did not prove to be In fact, the ring consisted of solder paste residues harmful to the application. found after Pb-free reflow. The sample in this case had n

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Dr. Davide Di Maio is with the National Physical Laboratory Industry and Innovation division (npl. co.uk); [email protected].

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“Charlie Barnhart continues to provide the best data of its kind available to the industry. Anyone involved in the offshoring of electronics manufacturing would benefit from the data and insights the Leading Indicators Monthly Report contains. Charlie began his work in this area while working with me at Technology Forecasters, where it quickly became the most pertinent and valuable data we had to offer customers. I am glad to see him continuing and extending his work now that he is independent. It is current, insightful, and well organized which makes it very easy to access and utilize.” Eric Miscoll, Vice President & General Manager, TXP Corporation

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Standards

The Legend of the New Marking Inks Standard Released in May, IPC-4781 resolves longstanding test issues. Type 2: Permanent legend and marking ink without egend and marking inks, marking pens, and ink direct metal contact (e.g., ink over solder mask). stamp products are integral parts of PCB fabricaType 3: Semi-permanent legend and marking ink. tion, yet industry has lacked a standard for the Type 4: Temporary legend and marking ink. manufacture and testing of these products, some of which Recognizing the types of inks covered is significant are known to cause long-term reliability issues. because there is a tendency to mark printed boards For years, the need for such a specification was raised in with whatever marking tool is readily available, thereby Solder Mask Performance Task Group meetings. Although raising failure rates. For example, certain color marksolder masks and legend inks are typically intended for ers, such as yellow, have high ionic content, creating different purposes, some board fabricators use legend ink electromigration and, potentially, field failures. Other in place of solder mask. These inks are not subjected to the chemicals cause corrosion and low insulation resisrigorous testing conducted on solder masks, which must tance. have specific electrical properties because they bridge elecAs with most standards, the key concerns were the trical conductors. In addition, solder masks are qualified properties to specify for testing and the requisite paramfor flammability performance as a permanent coating with eters. The standard had to balance what would be conUnderwriters Laboratory, while legend inks typically are sidered a fair amount of testing to levy against the matenot. However, the breadth of any such standard for legend rial manufacturer with the kinds of tests that should be and marking ink qualification was beyond the scope of performed by the material user. Material compatibility the task group, which was chartered to maintain the IPCwas another item. The specification was intended to SM-840 solder mask qualification specification. cover all products used for permanent, semi-permanent The urgency for a standard intensified as printed board and temporary applications, not just legend ink prodgeometries changed and continued to shrink. When spaces ucts. As new technology developed, such as inkjet legend between conductive patterns were large, there weren’t inks, the text was modified to include the latest available many problems caused by ink coming in contact with the information, right up to the standard’s adoption. circuits. With smaller spaces, the ink could easily encroach One of the key aspects of IPC-4781 is that it is perforon the electrical connections, causing failures. In 2004, mance-based. Performance criteria are spelled out, as are these issues came to a head and the IPC Legend Inks Task the different types of legend inks, which heretofore was Group was formed. And in May, IPC-4781, Qualification lacking. It gives some definition to terms loosely used in and Performance Specification of Permanent, Semi-Permanent and Temporary Legend and/or Marking Table 1. IPC-4781, Table 3-1, Requirements of Qualification Inks, became a reality. Requirement for Marking Type Testing and Inspection IPC-4781 defines Type 1 Permanent the criteria for, and Permanent No Type 3 IPCType 4 Other Test Requirement Direct Electrical SemiParagraph TM-650 method of, obtaining Temporary Methods Metal Metal Permanent Method the maximum inforContact Contact mation about and conPhysical ASTM fidence in legend and D3363, marking ink material Hardness Yes Yes Yes No 3.5.1 None Scratch Hardness under evaluation. This Test specification covers the Adhesion to four ink types (appliSolder Mask Yes Yes Yes AABUS* 3.5.2.1 2.4.28.1 – Materials cations): Conformal Type 1: Permanent Coating AABUS AABUS AABUS No – None AABUS Adhesion legend and marking Flammability Yes Yes Yes No 3.6.3 None UL94 ink with some areas FTIR Yes Yes Yes Yes 3.2.3.1 None – of direct metal conEnvironmental tact between electrical AABUS AABUS AABUS AABUS 3.12 None – Compliance nodes. *AABUS: As agreed between user and supplier.

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John Perry is technical projects manager at IPC (ipc.org); [email protected].

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Table 2. IPC-4781, Table 3.3 Test Responsibility for Qualification

defines the requirement and the right side specifies the materials and the tests to be performed. Requirement Material Supplier Fabricator End User Other aspects found in the complete version of Physical Hardness X X N/R the chart include chemical resistance, electrical Adhesion to requirements, environmental requirements and Solder Mask X X N/R materials. Table 2 features the top of Table 3-2, Materials depicting who is responsible for each test and Conformal Coating N/R AABUS* X qualification. Adhesion Military adoption? The significant issue to be Flammability X N/R N/R decided is whether the US military will adopt *AABUS: As agreed between user and supplier. the new specification. Three government specifications (MIL-I-43553, A-A-56032 and MIS37271) predate IPC-4781, but in our opinion do not meet regard to legend inks. These definitions are important, as Project2:Layout 1 4/14/08 11:42 AM Page 1 industry needs. much confusion has arisen over language issues. IPC-4781 will be useful for the commercial sector, but The heart of IPC-4781 is Table 3-1. IPC-TM-650, Test for companies that fabricate boards for the DoD, military Methods Manual, is referenced for testing and measurrequirements dominate legend and marking ink selection. ing performance in a broad range of characteristics. No It is hoped the Defense Department will adopt IPC-4781. specific chemistry or application method is called out or IPC-4781 mirrors other IPC specifications in terms excluded; any that meet the requirements are approved for of material qualification and conformance, such as IPCuse. Material compatibility of all inks is documented. Of SM-840 and IPC-CC-830 for conformal coatings, so commajor significance is assignment of responsibility between pliance should be user friendly. vendor and user for each specified formulation or varian tion of legend or marking ink material. In some cases, a designation of AABUS (as agreed between user and supAcknowledgments plier) is given, ensuring these issues are defined in the user/ supplier contract. A sample of the top of the chart, physical Doug Pauls of Rockwell Collins, Henry Sanftleben of Delphi Electronics & aspects, can be seen in Table 1. In this table, the left side Safety and Dave Vaughan of Taiyo America contributed to this column. Column A

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Column B

Standards

Column C

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Getting Lean

Processes and Outcomes If a task is performed different ways, the process – and therefore the result – is unpredictable. hy should people follow a process? So they can deliver a predictable outcome. And if the outcome is not adequate, we improve it. The right process will deliver the right results. And the right result is a predicable outcome. But can you create a standard work procedure (for more on this, see “Standard Work Procedures,” May 2008) without first examining the current process? In other words, can you start with invention? If it’s conceptual, you don’t really know until you try it. And once you try, you are creating a process by which the outcome can be examined. A principle of Lean is anything can be improved. The standard is a tool we use to make problems visible. To understand how to improve, something must be measured. This is done by exploring the weaknesses of the current process to understand the data and the facts. The current process is baselined to understand where it is, where the weaknesses are and if the changes lead to better results. Precisely what to do depends on the scope of the change. If an operator or office worker can examine their current work and see one piece that can be improved, they can change. That’s a process known as self-evaluation, and it underscores that anyone can participate in continuous improvement. An operator, for example, could make a change to their standard work by repositioning material so it’s easier to reach. It’s a new standard and it’s something they can do themselves. It’s a small, incremental change. They would evaluate how they do things today, and maybe conclude that moving a bin reduces their reach and shaves off a second of time. For a process with many pieces, however, such as many individuals or an entire value stream, change begins with a cross-functional team that examines the current state. As opposed to a transactional process, for example, the approval process may go through many levels of approvals, and the team may decide there are too many. Then there’s the issue of whether to use a Design of Experiments. The purpose of a DoE is to confirm the understanding of the problem, to pinpoint the problem that must be resolved. A DoE allows understanding of the part of the process or variable that is having the greatest impact on the outcome. Once this is known, those attempting to solve the problem could focus on that particular variable. In short, the DoE helps focus on where the biggest opportunity is, but it doesn’t play a role in making the actual change. The latter is the

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Robert Hemmant is global Lean architect at Celestica (celestica.com). His column appears bimonthly.

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Kaizen, the “change for the better.” Diffusion of standards. In an organization, the greatest challenge is to sustain the standard; the second is to diffuse the standard, so the same lesson isn’t learned over and over again. The larger the company, the more difficult it is to diffuse standards. Even within Toyota, from which many Lean principles are derived, there’s a constant puzzle of how to take the standard work they diffuse in Japan and translate that process to other factories without having to relearn the standard. The difficulty is, How do different workers learn the same lessons? Classically, as we age, we learn by failure. One way to overcome this is to raise awareness of the best ways to do things, to help others on the work level to learn the best ways of doing things and take that knowledge back to their teams, where they could possibly improve the standard. These “people systems” require maintenance. Taking a message and translating it down to the floor – to ensure it was adopted per its intent – requires checking. That process is called the management standard work. Determining whether the standards are being implemented and upheld is a component of the management standard work. All other tools we use in Lean – making the process visual so you can see the problems; making the process flow in a straight line with known customersupplier relationships – make it possible to see when there is a problem, so the management system can see the problems at a glance and determine whether a standard exists, if it is being followed, and whether it is adequate. Management needs to be able to do that as quickly as possible because they have a lot of processes to maintain. Similarly, this process is followed when diffusing a new strategy. One must look at the process by which the strategy is diffused throughout the organization. As changes are made to the strategy, there needs to be a check that the action is delivering the desired results. This all ties into the “Plan, Do, Check, Act” methodology of quality. It’s all interwoven to help management get results. At its core, Lean is a management system to help problem-solve in a sustainable way. It is very management – or leadership – intensive. It’s actually respectful to check. Standards aren’t used to be punitive, as in “you must do it this way.” In fact, they are team-based: Follow the standard as it is today because we want to know if it works. And if you have ideas to improve it, diffuse those ideas because the goal is to always do it better. n circuitsassembly.com

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论SMT生产中的细节问题 ——焊盘与孔 这篇文章从10月2008日问题继续。 当设计失误时，防堵的临时对策大至有以下几 种： 从焊接面以高温胶纸封住PAD。 从元件面插入护孔工装（如高温塑料排针、塗硅 胶的镙钉）。 单面板时，可在元件面用透明胶带封孔。 从焊接面点阻焊胶封住PAD及孔。 从焊接面印蓝胶封住PAD及孔。 做PCB托盘工装过波峰焊。 以上方法中生产成本自低到高大至是 C、E、B、A、D、F，值得一提的是印蓝胶工艺。由 于是采用印刷方式涂覆，预留孔越多，性价比越 高。当使用点胶机完成红胶工艺或PCB印胶面与印焊 膏面不是同一平面时，蓝胶固化与红胶固化或焊膏 回流可同时完成，使采用蓝胶保护PAD的成本相对较 低。 二、可靠性方面的考虑 1、PTH的焊锡垂直填充率 a)隔热设计是保证垂直填充率最重要条件，除PCB 的表面线路外与PTH相连的各层铜箔线路，都要以“ 花PAD”的形式与PTH相连，以提高热阻。需关注的 是相当多的设计者对此领悟有误，其细节是，焊 接起始面的PAD不可作隔热设计，且PAD环宽尽可能 大，以利于热量吸收，同时焊接终止面的PAD应尽可 能小，且是“花PAD”。这对质量大、热容量大的器 件是成功焊接的关键，参考一失败的案例，如图Figure 14。此款产品的设计上，在焊接起始面错用“ 花PAD”，使热量吸收受阻，如图Figure 15。焊热终 止面的“花PAD”形成的热阻又不足够大。元件是卧 式电解，其负极铝外壳有良好的散热性，且跨距设 计过短（应加10mm）、使引线热阻过小，导致外壳 的散热性被强化，结果此类PTH的填充率都较差。 b) 无铅工艺导入后的填充率，当PCB厚度>1.6mm 时，按IPC-A-610D的II、III级的要求，焊接时的 填充率应≥75%，在某些情况下是很难实现的，一 些大品牌公司，从分析填充率与可靠性的关系入 手制定了具有可操作性的企业标准，实验结果是 可靠性仅与焊锡垂直填充高度密切相关，当其达到 1.6mm*75%=1.2mm时，对厚度是2.5或3.3mm的PCB，焊 点强度没有问题，这对引入无铅工艺后的EMS厂是个 利好消息。 c)孔径对填充率的影响也是要关注的，我们定 义孔径与插件引脚的尺寸差为⊿T。一般有铅工艺 时，⊿T一般取0.2~0.3mm，当用冲孔工艺满足插件 机时，孔应是锥型。若NC钻孔时应取略大些。无铅 工艺导入后，⊿T还应稍大，板厚增加时，⊿T也 应加大，以保证填充率。一般取0.25~0.4mm。无铅 时，较大的⊿T使空洞减少，较小的⊿T可使缩痕减 弱，当然把锡银铜焊料换成锡铜，也可使缩痕改 善。 2、零件孔： a) NPTH的优先采用原则与PTH焊接终止面PAD环宽 circuitsassembly.com

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的最小化 出于rework后可靠性方面的考虑，PTH不宜作为零 件孔。但当晶振（金属外壳卧式）、中周、微动开 关、直插的PLCC插座等用于波峰焊工艺，并且助焊 剂涂覆方式是发泡时，NPTH当是唯一选择。从生产 实践及客户反馈可看到，焊接终止面的助焊剂残余 不会像焊接初始面的助焊剂那样，在经过250℃4秒 的加热后,其中的助焊物质已基本挥发。它会在环 境（湿度、盐雾、高温、尘土…）的作用下，影响 电路绝缘阻抗或使触点不可靠。此时的临时对策首 选是在元件面预涂助焊剂阻断剂，此方法在实用上 效果极佳，且费用低、省工时，缺点是此法对PTH无 效。当助焊剂的涂覆形式是喷雾时，助焊剂量虽可 控制，但如卧式晶振插入PCB后，当引脚PAD元件面 环宽偏大，且孔径与引脚的⊿T也大时，引脚PAD会 与外壳短路，此种不良设计对于EMS厂来说，并不少 见。即使短路未发生，由于PAD与外壳的间隙偏小， 助焊剂残余也容易导致功能性缺陷。当一定要使用 PTH时，解决方案是使元件面PAD环宽为零，就是用 阻焊或白油墨覆盖PAD。图Figure 16是一款电器产 品的 PCB，采用了焊接起始面与焊接终止面PAD环 宽差异设计，尤其是X301位置,元件面环宽为零。还 有一种常见的设计失误是LED紧贴板面插装，且采用 PTH。一般LED要求焊点距本体应≥2mm，常见的LED 亮度不稳定或不亮时重焊后就可改善，多数是没有 遵守上述要求，当采用NPTH时，PCB厚度可起到防呆 型的焊接安全距离的作用。无铅化后，PAD环宽最小 化及NPTH的额外好处是极大地减少Lift-off发生的可 能。 b) 零件孔（焊点）尽可能少地承受元件的重量 以往我们的工艺审查项有一条是当元件重量大于9 克时，其重量不能仅由焊点承受。在实际工作中， 数次见过典型的失效案例，外因多与震动相关，内 因多为元件过重，且除焊接点外无其他对元件的支 撑。当产品与手持或车载相关时，这一点尤为重 要。 c) 双径孔形状如图Figure 17，多为PTH，除保证 焊点的可靠外，还可使焊点不高于PCB表面，在电源 模块或手持产品中多有采用。孔径大的一面一般为 焊接起始面，基于这个特点，孔径大的一面设为元 件面时，若用在手工插件的通孔回流焊工艺中，可 提高焊膏量并使手插易于操作。 3、导通孔无铅化后的设计理念 在无铅波峰焊接中铜蚀现象是个比较严重的问 题。波峰焊接用PCB应把所有导通孔以阻焊覆盖，杜 绝铜蚀产生。图Figure 18是一种无铅化的汽车的电 子产品用PCB，其导通孔直径选得较大，这样可降低 对PCB材料的过高要求，如Z向的CTE。对PCB制造厂 而言，厚板的小孔电镀一直是个质量难题，在可能 情况下，导通孔径的变大是保证可靠性最经济的解 决方案。

Sanqiang Cai is an engineer with Beijing Brio (brio-tech.com/ egsjg.htm). Contact: Amy Dai; amydai@ brio-tech.ca.

Continued on pg. 47

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Product

SPOTLIGHT High-Power Soldering and Rework System Metcal MX-5000 Series is coupled with 80W of power for quick response to load conditions with high levels of control. Is microprocessor-controlled; incorporates a built-in digital power indication display. Hand-piece choices include Advanced Soldering and Rework hand-piece, UltraFine soldering hand-piece for micro-soldering applications, MX-PTZ precision tweezers hand-piece for SMD rework, and MX-DS1 through-hole desoldering hand-piece. Includes TipSaver Workstand with auto-sleep function. OK International, okinternational.com

Automated Moisture Analyzer PMD300 moisture analyzer uses microwave resonance technology. Analyzes core and surface moisture content; data can be obtained automatically or manually. Temperature in the oven, air supply and conveyor belt speed can be automatically adjusted to the current moisture content of the product. Measurable range lies between 0.1 and 60% moisture content. Sartorius Mechatronics, sartorius.com

IDF Plug-In for PCB123 v. 3.1 Self-Cleaning Squeegee Permalex Paste Manager runs on microprocessor-controlled torque actuators and reportedly resolves solder paste sticking to squeegees inside printers. Is said to achieve 90% cleaning action in 3.9 sec. for a 14” long squeegee. Runs on a variety of SMT printing platforms. Transition Automation, permalex.com

Free intermediate data format plug-in is the first module for PCB123 based on Software Developer’s Kit v. 3.1. Enables import of PCB designs for use in mechanical and electrical CAD systems in a bidirectional, neutral format within the ECOsystem Design Environment. Imports outline definitions of the PCB as specified by the mechanical CAD tool, synchronizing the mechanical design work with the PCB development work. Sunstone Circuits, sunstone.com/

‘All Axes’ Vision Sensor Checker 252 vision sensor includes all inspection capabilities of the Checker vision sensor family, plus additional software sensors that verify height, width, and diameter and deliver pass/fail results on high-speed production lines. Has one-click setup; clicking on the center of the part feature to be inspected, an image of a familiar caliper appears and locks on the edges of the part feature, sets the min. and max. thresholds, and learns edge polarity automatically. Cognex Corp., cognex.com

products-services/cad-software.aspx

200+ I/O LGA Connector W-Series Matrix Connector is for interconnecting LGAs with 200 or more board I/ Os. Reportedly eliminates need to solder or rework components. Is embedded with 300 to 2,000 gold-plated wires per cm2 and provides a carrying capacity of 500 mA/mm2. Comes in sizes up to 50 x 50 mm and thicknesses of 0.50 or 1.0 mm. Fujipoly America, fujipoly.com

2D Inspection for Printers Selective Soldering with Wave Height Measurement mySelective 6748 selective soldering system now features a wave height measurement system. Ensures a specific predetermined wave height for every PCB by automatically adjusting the solder pump RPMs. Uses a laser-based sensor to detect, measure, and monitor SelectWave height. Is said to prevent loss of cycle time. Stores individual PCB settings in the management info database. Combines SelectWave and MultiWave soldering technology; has on-the-fly reconfigurability, inline fluxing and preheating.

2D Inspection (2Di) V9 software tool monitors the print process. Is said to inspect boards or stencils to determine print quality. Identifies when stencil cleaning or paste dispensing is required, and prevents bridging, misalignment, stencil smear, stencil blockage and reduced paste volume. Includes simple setup, on-board guidance, enhanced operator prompts and automated post-print inspection feedback highlighting sites requiring attention. DEK, dek.com

Vitronics Soltec, vitronics-soltec.com

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Product

SPOTLIGHT Ergonomic Workbench Easy Lift has 20” of adjustable work surface. Serves as a workbench, assembly station and adjustable desk. Table moves vertically and has a 250 lb. load capacity. Comes standard with a 24 x 30” static dissipative powder-coated steel tabletop with ESD-safe Blue Softsurface matting material. Has foot pedal and adjusts from 19” to 39”.

‘Constant Vacuum’ Pickup Tip Stealth-Vac operates directly on 30 to 70 psi compressed air or nitrogen. The normally open vacuum pen contains a venturi vacuum generator. With compressed air supplied at the rear of the tool, the pickup tip is said to have constant vacuum available. Includes 6’ of 1/16” coiled vacuum hose, 1/8” NPT to 1/16” barb adapter for the supply line, and vacuum-generating handle. Virtual Industries, virtual-ii.com

Bliss Industries, blissindustries.com

Boundary Scan I/O Digital Module CION Module/DIMM240 enables testing of all signal and voltage supply pins of Jedec-compliant DIMM240 sockets for DDR2 SDRAM. Several boards of the same or different types can be cascaded in a daisy chain configuration. All channels can be independently switched as Input/ Output/Tristate. Provides special safety mechanisms. Goepel electronic, goepel.com

Pb-free Wave Solder Machine C250 is 50” x 30” and handles boards up to 10” wide in its adjustable corrosion-resistant finger conveyor. Is equipped with automatic defluxing, IR preheating, air-knife cooling and a low-volume solder pot. Is available in single or dual wave configurations for through-hole and surface mount assemblies. Includes built-in solder pot loading, a maintenance platform with locking support mechanism and dial-adjustable wave height control. Manncorp, manncorp.com/wave-solder/c250/

400-lb. Loader/Unloader BlissLift now has a wider base for assembly applications. Reportedly doubles the speed of repetitive load/unload tasks. Permits loading of 19” rackmount chassis into a 19” rack on a shipping pallet; legs straddle the pallet. Is said to be ideal for loading chassis onto storage carts and racks. Lifts loads up to 400 lb. Bliss Industries, blissindustries.com

FPD, CRY Display Tester U8101A display tester is for custom setups for visual testing of up to five major display formats. For testing FPD and CRT displays, and LCD panels in PC and TV manufacturing. Is said to support all major analog and digital interfaces and permits future upgrades. Has multiple plug-in card slots to customize instrument configuration. Uses a 5.7” color LCD display and Windows-based GUI. Can select different display formats, test configurations and other frequently used functions on front panel. Has capability to recall up to 16 test sequences and patterns. Agilent Technologies, agilent.com

Fast-Setup Selective Soldering Rhythm EX offers a selective soldering range of 24 x 24”; no manual rotation or adjustment is required. Offers closed-loop servo-driven X, Y, and Z-axis motion that articulates the solder wave and flux beneath the PCB. Designed for high-mix or highvolume production. Reportedly programs in minutes. Includes independently heated and programmable nitrogen inertion and quick-change solder nozzles for keep-away (less than 1.5 mm) and lead protrusion clearance (6 mm). Wave height management, system standby and startup, conveyor width and vision are automated. rPS Automation LLC, rpsautomation.com

Rework, Re-solder Unit PC-controlled Martin “Expert” Pb-free rework station version 9.6 is said to automatically accomplish any stage of SMT repair, from removal to replacement, as well as the re-solder of BGAs, CSPs, µBGAs and other SMDs. A high-res camera combined with auto-vision placement controls component positioning in full and continuous view of the operator. IR underheating unit adjusts to exact board size. Manncorp, manncorp.com

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Ad Index ADVERTISER INFO: To learn about the advertisers in this issue, go to circuitsassembly.com and select “Advertiser Index” in the gray horizontal menu bar at the top of the page. This will provide you with direct links to the home or product pages of each advertiser in this index. Company

Page No.

Assembléon, www.assembleon.com . . . . . . . . . . . . . . . . . 21, 23, 25 Bare Board Group, www.bareboard.com. . . . . . . . . . . . . . . . . . . . 47 BEST, Inc., www.solder.net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Charlie Barnhart & Associates, www.charliebarnhart.com . . . . . 39 Cookson Electronic Assembly Materials, www.cooksonelectronics.com . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 CyberOptics, www.cyberoptics.com . . . . . . . . . . . . . . . . . . . . . . . C3 Digi-Key, www.digikey.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Electronics West Show, www.electronicswestshow.com . . . . . . . . 22 Green Rules!, www.envisionrules.com . . . . . . . . . . . . . . . . . . . . . 35 Grid-Lok, www.grid-lok.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . C4 Imagineering, Inc., www.pcbnet.com . . . . . . . . . . . . . . . . . . . . . . 1

Solder Joint Reliability Continued from pg. 31

This indicates solder pastes with an activation system able to provide sustainable high-temperature fluxing activity are capable of creating a homogenous connection beyond the ball and the paste alloy interface. Figure 6 shows a HIP formed using a lower-temperature activation system. Figure 7 is a joint formed with a high-temperature activation system; no evidence of HIP is seen. Based on these experiments, Table 1 was generated to show the relative impact of variable(s) that contribute to HIP, rated on a scale of one to 10, with 10 as the most likely to eliminate the issue. Conclusions Based on this preliminary study, it appears the two significant factors are solder paste flux chemistry and BGA alloy ball wetting. Frosty, non-uniform structures appear to perform the worst for BGA HIP. This is logical, as these are intermetallic regions on the surface of the solder ball. The intermetallic connection of AgSn and CuSn possesses much higher melting temperatures than the alloy themselves. They are also crystalline in structure and can repel wetting. Although additional studies are necessary to corroborate these results, there is a strong indication this surface structure is one of the leading causes of the HIP defect. n

References 1. Chrys Shea, “HOP-ping Mad,” CirCuits Assembly, July 2008. 2. American Competitiveness Institute, “Stop the HOP,” CirCuits Assembly, August 2008.

Indium Corporation of America, www.indium.com . . . . . . . . . . . . 7 JETPCB Inc., www.jetpcb.com . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Juki Automation Systems, www.jas-smt.com . . . . . . . . . . . . . . . . 11 MIRTEC Corp., www.mirtecusa.com . . . . . . . . . . . . . . . . . . . . . . . 15

Karl Seelig is vice president of technology at AIM (aimsolder.com); [email protected].

United States Postal Service Statement of Ownership, Management, and Circulation 1. Publication Title: CIRCUITS ASSEMBLY 2. Publication No.: 1054-0407

Nihon Superior Co., Ltd., www.nihonsuperior.co.jp . . . . . . . . . . . 13 PCB East, www.pcbeast.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 PCB Phoenix, www.pcbshows.com/phoenix . . . . . . . . . . . . . . . . . . 4 Powell-Mucha Consulting, www.powell-muchaconsulting.com . . . . . . . . . . . . . . . . . . . . . 41 Precision Placement Machines, Inc., www.goppm.com . . . . . . . . 47 Seika Machinery, www.seikausa.com . . . . . . . . . . . . . . . . . . . . . . 27

3. Filing Date: 10/01/2008 4. Issue Frequency: Monthly 5. No. of Issues Published Annually: 12 6. Annual Subscription Price: $80.00 7. Complete Mailing Address of Known Office of Publication: UP Media Group Inc. - 2400 Lake Park Drive, Suite 440 - Smyrna, GA 30080; Contact Person: Jennifer Schuler; Telephone: 918496-1476 8. Complete Mailing Address of Headquarters or General Business Office of Publisher (Not printer): 2400 Lake Park Drive, Suite 440 - Smyrna, GA 30080 9. Full Names and Complete Mailing addresses of Publisher, Editor, and Managing Editor: Publisher, Pete Waddell - 2400 Lake Park Drive, Suite 440 - Smyrna, GA 30080; Editor, Mike Buetow - 2400 Lake Park Drive, Suite 440 - Smyrna, GA 30080; Managing Editor, Javier Longoria - 2400 Lake Park Drive, Suite 440 - Smyrna, GA 30080

(3) Paid Distribution Outside the Mails Including Sales Through Dealers and Carriers, Street Vendors, Counter Sales and Other Paid Distribution Outside USPS: 24,638; 20,543 (4) Paid Distribution by Other Classes Mailed Through the USPS: 0; 0 c. Total paid and/or Requested Circulation (Sum of 15b (1), (2), (3), and (4): 43,023; 43,076 d. Free or Nominal Rate Distribution (By Mail and Outside the Mail): (1) Free or Nominal Rate Outside-County Copies Included on Form 3541: 0; 0 (2) Free or Nominal Rate In-County Copies Included on PS Form 3541: 0; 0 (3) Free or Nominal Rate Copies Mailed at Other Classes Through the USPS (e.g. First-Class Mail): 0; 0 (4) Free or Nominal Rate Distribution Outside the Mail (Carriers or other means): 603; 594 e. Total Free or Nominal Distribution (Sum of 15d (1), (2), (3) and (4)): 603; 594

SMTA - Pan Pac Conference, www.smta.org. . . . . . . . . . . . . . . . . 24

10. Owner: UP Media Group, Inc., 2400 Lake Park Drive, Suite 440 - Smyrna, GA 30080

Speedline Technologies, www.speedlinetech.com . . . . . . . . . . . . 5

11. Known Bondholders, Mortgagees, and Other Security Holders Owning or Holding 1 Percent or More of Total Amount of Bonds, Mortgages, or Other Securities: None

Ticona Engineering Polymers, www.ticona.com/halogenfree . . . C2

12. Does not apply

h. Total (Sum of 15f, and g): 43,672; 43,709

13. Publication Name: CIRCUITS ASSEMBLY

i. Percent Paid and/or Requested Circulation (15c. Divided by 15f times 100): 98.61779673; 98.63979849

Virtual PCB, www.virtual-pcb.com . . . . . . . . . . . . . . . . . . . . . 29, 35

14. Issue Date for Circulation Data Below: October 1, 2008 15. Extent and Nature of Circulation:

Advertising Sales North UP Media Group, Inc. America: 2400 Lake Park Drive, Suite 440

Average No. copies Each Issue During Preceding 12 Months; No. Copies of Single Issue Published Nearest to Filing date a. Total Number of Copies (Net Press Run): 43,672; 43,709 b. Paid and/or Requested Circulation:

Smyrna, GA 30080 Krista Fabian Sales Associate, (678) 589-8840 email: [email protected]

Asia: Korea: Young Media, 82 2 756 4819 email: [email protected]

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(1) Mailed Outside-Country Paid Subscriptions Stated on PS Form 3541 (include paid distribution above nominal rate, advertiser's proof copies, and exchange copies) 0, 0 (2) Mailed In-Country Paid Subscriptions Stated on PS Form 3541 (Include paid distribution above nominal rate, advertiser's proof copies, and exchange copies): 18,385; 22,533

f. Total Distribution ( Sum of 15c and 15e): 43,626; 43,670 g. Copies not Distributed (See Instructions to Publishers #4 (page #3)): 46; 39

j. Percent Paid and/or Requested Circulation (15c. Divided by 15g times 100): 99.00763887; 98.15612 16. If the publication is a general publication, this statement is required. Will be printed in the December 2008 issue of this publication. 17. Signature and Title of Editor, Publisher, Business Manager, or Owner: I certify that all information furnished on this form is true and complete. I understand that anyone who furnishes false or misleading information on this form or who omits material or information requested on the form may be subject to criminal sanctions (including fines and imprisonment) and/or civil sanctions (including civil penalties). (signed) Pete Waddell, October 1, 2008.

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Eastern Advances

Special Advertising Section

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Continued from pg. 43

4、安装孔的设计理念 a) 当安装孔是冲制的，并是方孔 时，注意设计时4角R的取值，PCB基 材优选室温冲裁型，以杜绝裂纹的产 生，R的取值一般是0.2-0.5mm。 b) 安装孔周边区域与其支撑面间除 了SM外，还应有白标志油墨做为保护 层。从可靠性出发，PCB与其所有支 撑面间都应有尽可能多的防护设计。 c) 安装孔周边受组装时的应力会造 成附近焊点在震动时早期失效，在手 持或车载产品中屡见不鲜，要正确应 对，设立元器件避让区。 d) 安装孔是PTH时，且被借用于定 位。当定位销是用于丝印的平顶销 时，过盈的配合会产生刮挤下的铜屑 制成短路，我公司加工的某款产品在 这方面造成了非常大的麻烦。 e) 安装孔需手工补焊的加强PAD， 应有如图Figure 19的设计。 在电子组装业高速发展的今天，大 规模量产的实战技术（细节）的获 取十分不易，若能处处对那些看似奇 怪且不理解的设计及方法潜心琢磨， 当能对大品牌公司的Know-How略窥一 斑，其次是关注失败，不论是他人的 还是自己的，力求涉及根本原因，并 制定有效的不重犯对策，希望今后在 上述两方面与同行们多做交流，共同 进步。 例证是可利用的在 circuitsassembly.com/cms/images/stories/ ArticleImages/0810/0810eastern_ online.pdf n

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Circuits Assembly DECEMBER 2008

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Technical Abstracts

In Case You Missed It Cleaning “Cleaning Qualification Methodology for Inline Aqueous Assembly Process” Author: Steven Perng; [email protected]. Abstract: This assessment of the cleanliness of the area beneath a component uses an 8"×9"×0.093" test vehicle with FR-4 laminate, OSP surface finish, and 21 package types. The TVs underwent assembly and inline aqueous cleaning. The two test methodologies used were ion chromatography and electromigration. Based on the test results, most of components pass the criteria, except three high-pin-count LBGAs, which showed high levels of bromide using a certain paste. No significant differences were found between the low standoff components group and other groups. Among the four low standoff components, LGA133, which has the lowest standoff, shows a higher total anion level. Test results also verified that, within the similar package types, the ionic level is likely proportional to the stencil paste volume. There were no statistical differences among the three time-towash cases: If the board is washed within 72 hrs., there is no significant difference on ionic level. (IPC Midwest, September 2008)

CirCuits Assembly

provides abstracts of papers from recent industry conferences and company white papers. With the amount of information increasing, our goal is to provide an added opportunity for readers to keep abreast of technology and business trends.

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Environmental Compliance “REACH for Electronics Manufacturers” Author: John Fox; [email protected]. Abstract: REACH presents a new set of direct and indirect risks for article manufacturers. Direct risks arise from obligations explicitly outlined in the REACH regulation itself: article 7 and article 13. Indirect risks arise from upstream and downstream supply chain ripple effects caused by REACH. These ripple effects will impact article manufacturers, including those who do not import directly into the EU. Article manufacturers – particularly those with complex products and supply chains – are adopting data-driven risk management approaches to help ensure the future viability and profitability of their products. This presentation presents a framework to identify and mitigate REACH risks, both direct and indirect. It outlines a fact-based and systematic approach, describing what product and supply chain data are needed and how to make decisions based on these data. This paper is based in part on the REACH initiatives underway at several large MNCs. (IPC Midwest, September 2008) Nanotechnology “Large Scale 3-D Vertical Assembly of Single-Wall Carbon Nanotubes at Ambient Temperatures” Authors: Evin Gultepe, Dattatri Nagesha, Bernard Didier Frederic Casse, Selvapraba Selvarasah, Ahmed Busnaina and Srinivas Sridhar; [email protected]. Abstract: The authors demonstrate 3-D directed Circuits Assembly DECEMBER 2008

assembly of single-wall carbon nanotubes (SWNT) into porous alumina nanotemplates on silicon substrates by means of electrophoresis and dielectrophoresis at ambient temperatures. Assembled SWNT provided an interconnection between the surface and base of the nanotemplate. I–V measurements clearly show that the connection between silicon and SWNT is established inside the templates. This technique is particularly useful for large-scale, rapid, 3-D assembly of SWNT over centimeter square areas under mild conditions for nanoscale electronics applications. (Nanotechnology, Oct. 8, 2008) Solder Joint Reliability “1st Order Failure Model for Area Array CSP Devices with Pb-Free Solder” Authors: Nathan Blattau, Joelle Arnold, Gerd Fischer, Craig Hillman; [email protected]. Abstract: The thermomechanical reliability of solders with little or no silver is not well known because the main focus has been on improving the solder interconnects’ mechanical shock/drop performance. This study presents preliminary thermal cycling data for a SnNiCusoldered area array CSP. These data are then used to develop a first-order analytical model to make thermal mechanical fatigue life predictions. The model uses basic distance to neutral point and continuous attach type equations to predict the strain energy dissipated by the solder joint. The energy dissipation is used to make fatigue predictions. (IPC Midwest, September 2008) Wave Soldering “Design for Manufacturability in Lead-Free Wave Solder Process” Author: Ramon Mendez; [email protected]. Abstract: The effect of pin-to-hole ratio, quantity of large copper planes connected to a pin through-hole barrel, connection types for PTH and land patterns for glue and wave chip components are some of the main features that require further investigation for design optimization. It is also important to determine if a set of DfM guidelines result in similar results among the various Pb-free alloys. This paper discusses the outcome of a study of several DfM features incorporated on an internally designed test vehicle created to evaluate alternative Pb-free alloys. DfM features included land pattern design and varying component spacing for chip components, pin-to-hole ratio and its interaction with the quantity of large copper planes connected to a PTH, quantity of large copper planes connected to a PTH and its interaction with the type of connection either solid or four spokes. The TV was assembled with four Pb-free alloys (SnCuNi, SnAgCuBi, SnCuX and SAC 405) and SnPb37 alloy as a baseline. (IPC Midwest, September 2008) circuitsassembly.com

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