Application of FFU Fan Filter Unit Inpurifying Air Conditioning System

With the continuous updating of the production process, the FFU fan filter unit in theproduction process of semiconductor microelectronics, the yield and reliability of its productsdepend largely on the cleanliness and equipment of the workshop.

Clean room refers to the room where the concentration of airborne particles and bacteriais controlled.Generally, afterthe clean room is built, the layout can not be changed at will, but dueto the continuous updating of the production process,the cleanliness layout of the original cleanroom workshop cannot meet the needs of the new process, resulting in frequent changes of theclean room workshop due to the replacement of products,which wastes a lot of financial andmaterial resources.The purification of the traditional air conditioning system mainly usEs thecentral supply way, by air treatment equipment (heater, cooler, humidifier, effective/efficient filter,etc.) in the early and fan are concentrated in air conditioning room installation, high efficiency filterinstalled in the system, at the end of use centralized send and return air duct connected the airhandling equipment and clean room.This approach has a significant disadvantage of poor flexibility.Once the production process adjustment leads to the need to adjust the cleanliness of theworkshop, it is almost impossible to achieve.

As a new type of purification equipment, FFU occupies an important position in the cleanfield.FFU has a high degree of flexibility in the control of cleanliness in the clean workshop.Byincreasing and decreasing the number of FFU purification and filtration units, it is the adjustmentand layout of local cleanliness in the workshop，which can meet the changes in clean room needsbrought about by production process changes.At the same time, THEFFU purification and filtrationunit has its own power, tuyere and lamps, which can save a lot of investment.

Purification air conditioning adopts FFU air supply mode, FFU is distributed on the top, FFU actsas purification cycle group in the purification air conditioning system, and the circulating air volumein the clean room is equaltothe totalair volume of the CLEAN room FFU.FFU clean waycan achieveair clean level requirements in lSO3-ISO9 (that is, 1~1 million) between the clean room.

The advantages and disadvantages of FFU ventilation mode and traditional centralized air supplymode are analyzed

(1) FFU ventilation system is flexible and can be adjusted at any time

Because the panels of the clean room are arranged in modules of the ceiling grid, due to

the structure of its special nodes,the panels of the clean room can be adjusted at any time tochange the layout. Ilf the cleanliness of the workshop needs to be adjusted, it can be achieved byincreasing or decreasing the number of FFUs.

(2)Low energy consumption

From the components of FFU, only the micro fan needs to consume energy.The FFU system hasfew air ducts. In addition to the fresh air delivered by air ducts, a large number of return air isrunning in the way of small circulation, which greatly reduces the resistance consumption of airducts.Although the initial investment of the FFU fan filter system is higher than that of the air duct

ventilation, in the later operation, FFU generally saves more than 30% energy than the centralizedair supply purification system, which is more energy saving and maintenance-free.

(3)The outlet air is uniform and stable

FFU has its own fan, and the sound system has uniform and stable air output, which avoidsthe problem of balance of air volume ateach air outlet of the centralizedair supply system.

(4) Save space

The FFU purification system eliminates the returnair duct, which can save installation space.(5) negative pressure seal

The plenum of FFU air supply system is negative pressure, so even if there is leakage oftuyere, the clean room leaks to the plenum, which will not lead to pollution of the clean room.

Disadvantages of FFU system: large number of fans, large probability of failure.And FFU isarranged on the ceiling，maintenance is difficult.The centralized air supply system is easy tomaintain due to its concentration of equipment and small quantity.lt is because the FFU system isnumerous and scattered, generally a small amount of FFU failure will not have a great impact onthe cleanliness of the whole workshop, and centralized air supply system as long as an AHU failure,will cause a large area of clean room stop running.