Cleanroom Technology

Cleanroom technology has evolved over the years. With more stringent requirements governing manufacturing products, we have progressed to using higher efficiency filters to satisfy production requirements.

Airborne particulates range in sizes from 0.001 microns to several hundred microns. A typical High Efficiency Particulate Air (HEPA) filter is rated to filter out 99.97% of 0.3 microns (or larger) particles. For higher grade filters, there are Ultra-Low Penetration Air (ULPA) filters that have a minimum efficiency 99.999% at 0.1 microns.

The key to creating and maintaining a clean environment is based on the principles of:

• Isolating the clean environment to prevent ingress of contaminants from the external environment

• Diluting the air within the environment with clean air to keep the particle concentration low

• Minimizing the generation and accumulation of contaminants within the clean environment itself

The selection of materials used in a cleanroom varies with the cleanliness class of the environment and the specific requirements of the end-user. The most commonly used standard is ISO 14644: (2015), which has replaced the long-standing US Federal Standards (FS209E). However, many still find it easier to refer to the cleanliness classes with their FS209E designations. This table shows the current ISO classifications and their equivalent FS209E designations:

Airborne Particulate Cleanliness Classes (ISO 14644: 2015)

ISO CLASS NO.	0.1µm^	0.2µm^	0.3µm^	0.5µm^	1µm^	5µm^	FS209E Designation*
1	10	-	-
2	100	24	10				Class 1
3	1,000	237	102	35			Class 10
4	10,000	2,370	1,020	352	83		Class 100
5	100,000	23,700	10,200	3520	832		Class 1,000
6	1,000,000	237,000	102,000	35,200	8,320	293	Class 10,000 ​
7				352,000	83,200	2,930	Class 100,000
8				3,520,000	832,000	29,300
9				35,200,000	8,320,000	293,000

^ Maximum allowable concentrations (particles/m³) for particles equal to and greater than the considered sizes, shown below

* FS209E Designations are near-equivalent and not exact