Clean room refers to a well sealed space that controls air cleanliness, temperature, humidity, pressure, noise and other parameters as required

The development of clean room is closely related to modern industry and cutting-edge technology. Due to the environmental requirements of precision machinery industry (such as gyroscope and micro bearing processing) and semiconductor industry (such as large-scale integrated circuit production), the development of clean room technology is promoted. According to domestic statistics, the qualified rate of MOS circuit die production in the environment without clean level requirements is only 10% ~ 15%, and 64 is only 2% of memory. At present, clean rooms are widely used in precision machinery, semiconductor, aerospace, atomic energy and other industries

According to the flow state of air flow

According to the flow state of air flow, there are mainly three types of clean rooms with air flow distribution [1]:

(1) Non unidirectional flow clean room: it was often called turbulent flow clean room, and the air flow in the room does not flow in a single direction. The non unidirectional flow clean room has several common characteristics: the terminal filter (high efficiency or sub high efficiency) is close to the clean room as much as possible, which can be the air supply outlet or directly connected to the air supply outlet, or connected to the air supply static pressure box of the room; The return air outlets are set at the lower part of the clean room to avoid the phenomenon of "ash lifting". Vortex exists in non unidirectional flow clean rooms, which is not suitable for clean rooms with high cleanliness, but for clean rooms with grade 6 ~ 9.

(2) Unidirectional flow clean room: the air flow in unidirectional flow clean room is characterized by parallel flow lines, flow in a single direction, and consistent wind speed on the cross section. There are vertical unidirectional clean room, quasi vertical unidirectional flow, horizontal unidirectional flow clean room, etc.

(3) Vector clean room: fan-shaped high-efficiency filter can be used for air supply at the upper corner of the room, or ordinary high-efficiency filter can be used with fan-shaped air supply outlet, and air return outlet is set at the lower part of the other side. The height length ratio of the room is generally between 0.5 ~ 1. This kind of clean room can also achieve grade 5 (Grade 100) cleanliness.