How Does Cleanroom Achieve Cleanliness?

Due to the complexity of the external environment, it is not easy to realize the actual cleanliness of Fab. The main sources of contamination are particles, metal elements and organic matter from personnel activities. Particles and metal elements from equipment operation. Particles, metal elements and organic matter from raw and auxiliary materials. Particles of oxidized organic matter from operating methods. And particles from the workshop environment. Of these, particulate matter accounts for about 37-70%, liquid particles for about 10-30%, and microorganisms for about 5-20%.

To achieve different levels of cleanliness, Fab usually requires the preparation of a complex system, somewhat similar to the fresh air systems currently used in homes, through the addition of different sized filters with different pore sizes in between the intake and exhaust. Usually, the air pressure in the Fab is higher than the outside atmospheric pressure to avoid spontaneous inflow of pollutants to contaminate.

In addition to high-volume filtration of outside contaminants, complex systems are required inside the Cleanroom to further improve the cleanliness of the Cleanroom. Typically, a large number of air conditioning systems are required to filter the air through High Efficiency Particulate Air Filters (HEPA) and to control the temperature and humidity accordingly (the cleanroom temperature is 20-26℃ and the humidity is less than 70%). The cleanliness requirements of different process plants are realized by different systems.

For areas with high cleanliness requirements, ULPA (Ultra Low Permeability Air Filter) systems are often used, i.e., horizontal or vertical unidirectional laminar flow as well as control of the number of personnel, a form of airflow that helps to maintain an even distribution of airborne particles and minimize the spread of particles in the space. By controlling the direction and velocity of airflow, a more stable and uniform laminar airflow can be achieved. For other shop requirements, HEPA (High Efficiency Particulate Air) filters are often used to achieve this, i.e. by simple turbulence.

In order to prevent outside contamination from invading the clean room, need to ensure that the indoor static pressure is higher than the outside world static pressure, the pressure difference should be maintained in line with the following principles:

1.Clean Room is higher than the non-clean area.

2.high cleanliness of the room static pressure is higher than the adjacent cleanliness of the room.

3.The Cleanroom Door of the clean room should be opened to the high cleanliness level of the region.