Factory workshop purification Engineering has to maintain the original set by the required cleanliness, temperature and humidity and pressure performance, such as the main role is to control product cleanliness and temperature and humidity, such as silicon chips are in contact, make the product in a good environment space production, manufacturing, it is divided into four levels as below:

1.The maximum permissible particle concentration of 0.5 micron for a Class 100 clean room is less than 3520 (pc/m3) and the maximum allowable particle concentration for 5 micron is less than 293 (pc/m3).

2.The 0.5-micron maximum allowable particle concentration of the Class 1000 clean room is less than 35200 (pc/m3), and the maximum allowable particle concentration of 5 microns is less than 2930 (pc/m3).

3.The maximum permissible particle concentration of 0.5 μm in a dust-free workshop is less than 352,000 (pc/m3), and the maximum allowable particle concentration of 5 μm is less than 29300 (pc/m3).

4.The maximum allowable particle concentration of 0.5 micron in a class 100,000 clean room is less than 3,520,000 (pc/m3), and the maximum allowable particle concentration in micrometer is less than 293,000 (pc/m3).