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

Airborne particles range in size from 0.001 microns to several hundred microns. A typical HEPA(High Efficiency Particulate Air) filter would be able to filter 99.97% of 0.3 microns or bigger particles. A similar analogy would be if there are 10,000 fishes (particles) of various sizes but minimum 30 cm long( 0.3micron). If all the fishes swim towards a fishing net(HEPA filter) only 3 fishes will be able to swim pass the net.

For higher grade filters, there is the ULPA (Ultra Low Penetration Air) filters that have a efficiency of 99.999% at 0.1 microns.

The key to creating and maintaining a clean environment is to isolate and dilute all internal and external sources of particulate matter.

The selection of materials used in a cleanroom will vary with the different cleanliness class. The 2 most commonly used standards are Federal Standards 209E and ISO 14-644.