Cleanroom Classifications

Cleanroom

Cleanroom classification Cleanrooms are designed to provide this by meeting purity classes of various degrees based on ISO and cGMP standards, as directed by the given applications at rest conditions

A cleanroom is an environment, typically used in manufacturing or scientific research, that has a low level of environmental pollutants such as dust, airborne microbes, aerosol particles and chemical vapors. More accurately, a cleanroom has a controlled level of contamination that is specified by the number of particles per cubic meter at a specified particle size. To give perspective, the ambient air outside in a typical urban environment might contain as many as 35,000,000 particles per cubic meter, 0.5 µm and larger in diameter, corresponding to an ISO 9 cleanroom.

Overview Cleanrooms can be very large. Entire manufacturing facilities can be contained within a cleanroom with factory floors covering thousands of square meters. They are used extensively in semiconductor manufacturing, biotechnology, the life sciences and other fields that are very sensitive to environmental contamination. The air entering a cleanroom from outside is filtered to exclude dust, and the air inside is constantly recirculated through high efficiency particulate air (HEPA) and/or ultra low penetration air (ULPA) filters to remove internally generated contaminants. Staff enter and leave through airlocks (sometimes including an air shower stage), and wear protective clothing such as hats, face masks, gloves, boots and cover alls. Equipment inside the cleanroom is designed to generate minimal air contamination. There are even specialised mops and buckets. Cleanroom furniture is

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also designed to produce a minimum of particles and to be easy to clean. Common materials such as paper, pencils, and fabrics made from natural fibers are often excluded; however, alternatives are available. Cleanrooms are not sterile (i.e., free of uncontrolled microbes) and more attention is given to airborne particles. Particle levels are usually tested using a particle counter. Some cleanrooms are kept at a positive pressure so that if there are any leaks, air leaks out of the chamber instead of unfiltered air coming in. Some cleanroom HVAC systems control the humidity to relatively low levels, such that extra precautions are necessary to prevent electrostatic discharge (ESD) problems. These ESD controls ("ionizers") are also used in rooms where ESD sensitive products are produced or handled. Low-level cleanrooms may only require special shoes, ones with completely smooth soles that do not track in dust or dirt. However, shoe bottoms must not create slipping hazards (safety always takes precedence). Entering a cleanroom usually requires wearing a cleanroom suit. In cheaper cleanrooms, in which the standards of air contamination are less rigorous, the entrance to the cleanroom may not have an air shower. There is an anteroom, in which the special suits must be put on, but then a person can walk in directly to the room . Some manufacturing facilities do not use fully classified cleanrooms, but use some cleanroom practices together to maintain their cleanliness requirements.

Maximum allowable particle count per M

Air Particle Count ISO a) 14644-1

US Fedral Standard a) 209 Si

> 0.1 um

> 0.2 um

> 0.3 um

> 0.5 um

3

> 1.0 um

ISO Class 1

10

2

ISO Class 2

100

24

10

4

1000 1240

237 265

102 106

35 35

8

10000 12400

2370 2650

1020 1060

352 353

83

3520 3530 3500

ISO Class 3

M1.5 (1) b)

ISO Class 4

M2.5 (10) b)

ISO Class 5

M3.5 b) (100)

100000

23700 26500

10200 10600

ISO Class 6

M4.5 (1000)

1000000

237000

102000

ISO Class 7

M5.5 (10000)

ISO Class 8

M6.5 (100000)

b)

b)

b)

ISO Class 9

35200 35200

> 5.0 um

832

29 0

8320

293 247

352000 353000 350000

83200

2930 2470 2000

3520000 3530000 3500000

832000

29300 24700 20000

35200000

8320000

293000

a) At rest conditions b) Class division in cubic feet

For Guidance Class 1 and 10 (the highest specification) are generally used for integrated circuit and semi-conductor manufacture. Class 100 (BS. 5295 equivalent classifications E and F) are often used by the electronics industry along with some applications within pharmaceutical facilities. Class 1,000 to 10,000 are used by manufacturers of the highest specification fibre optics, precision engineering, sterile packaging and pharmaceutical manufacturing. Class 100,000 is adequate for general component assembly and packaging.

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