Dye And Pry Procedure

Dell Controlled Print

Dye and Pry Failure Analysis Procedure Number: REL### Revision: A00

Engineers/Owners: Dell Reliability Organization & Component/Materials Failure Analysis Lab

DELL CONFIDENTIAL THIS ITEM IS THE PROPERTY OF DELL CORPORATION, AUSTIN, TEXAS AND CONTAINS CONFIDENTIAL AND TRADE SECRET INFORMATION. THIS ITEM MAY NOT BE TRANSFERRED FROM THE CUSTODY OF DELL COMPUTER CORP., AND THEN ONLY BY WAY OF LOAN FOR LIMITED PURPOSES. IT MUST NOT BE REPRODUCED IN WHOLE OR IN PARTS AND MUST BE RETURNED TO DELL COMPUTER CORP. UPON REQUEST AND IN ALL EVENTS UPON COMPLETION OF THE PURPOSE OF THE LOAN. NEITHER THIS ITEM NOR THE INFORMATION IT CONTAINS MAY BE USED BY OR DISCLOSED TO PERSONS NOT HAVING A NEED FOR SUCH USE OR DISCLOSURE CONSISTENT WITH THE PURPOSE OF THE LOAN WITHOUT THE PRIOR WRITTEN CONSENT OF DELL COMPUTER CORPORATION.

WWW.DELL.COM

Dye and Pry Procedure 1. Purpose The purpose of this document is to describe in detail the Dye and Pry procedure that is required to be used on products evaluated for Dell. Modifications to this procedure are acceptable if such modifications are shared with Dell and approved.

2. Minimum Requirements 1. 2. 3. 4. 5.

Machinist’s dye (recommendation is Red Steel Dykem). Vacuum pump and chamber (typically a mechanical pump and bell jar). Stereo microscope with digital camera Baking oven capable of 100C Ability to section out desired components from board without exerting excessive stress on the solder joints. 6. Tool to pry the component from the board. 7. Flux cleaning solvent. 8. Trained operators.

3. Procedure 1. Identify components to be “Dye and Pry” evaluated (consult test plan). 2. Section out the desired component leaving about 1.5 to 2 inches of board around the part. 3. Clean any flux residue from around joints using a solvent (recommend using a Flux Remover spray - Isopropyl alcohol alone is not acceptable). Removing any flux residues and other particles/oils enables the dye to more easily penetrate the fractures. Failure to completely remove flux from around the BGA bumps may prevent ink penetration and give false indications of a good solder joint. 4. Rinse well with water (followed by isopropyl alcohol if desired). Allow to completely dry. 5. Immerse the sectioned sample in the dye (typically in a small tray). 6. Place the tray and sectioned sample into a vacuum chamber. Draw a vacuum for 3 to 4 minutes. Partially vent and reapply vacuum to the chamber a few times to aid in dye penetration. 7. Turn off vacuum pump and leave the sample in the dye for several minutes under vacuum. 8. Vent any remaining vacuum and remove sample. Allow the excess dye to drain off the sample. 9. Dry the sample in an oven by baking at 100°C for up to 30 minutes depending on the amount of dye under and around the device. The dye must be completely dried. Wet dye can smear during component removal resulting in false conclusions. 10. Following removal from the oven, allow the part to cool.

11. The component is then mechanically removed. It can be pried off with a chisel but this may damage bumps on the outer one or two rows. The board can also be repeatedly flexed until the device “pops” off. 12. After the component is removed, the board and part are to be examined. Fractured wetting pad surfaces on either the board or the component will be dyed red. 13. Take photos of dyed regions and plot results in a matrix chart.

Immerse in dye and place in vacuum.

Remove component by prying or, Photos from Universal Instruments.

Ensure dye is completely dry.

remove component by twisting.

Cracked/open prior to testing

PWB

Partially cracked but still conductive prior to testing

Example of solder joints after component removal.

Example of a dye and pry matrix map which reveals the location of the fracture when component is removed from the PCB. A similar map is required that shows the magnitude of the ink penetration for each solder ball (> 25%, >50%, >75%, 100%).