Re: IC ISO Cleanroom Classification - ISO Class 7 (10k), ISO Class 8 (100K), ISO Clas
The classification of air cleanliness is very simple as the class equates to the number of particles per cubic foot of air equal to or greater than 0.5µ (micron). I have attached a simple matrix that details the particles per cubic foot of air with particle size from 0.1µ to 5µ for class 1 to 100K.
In the microelectronics industry, we are concern with static as well as contaminations caused by particles, fibers and electrostatic charges where it will cause malfunction of the product.
A clean room can be divided into critical and general area. The critical area near the point of production where contamination can cause direct contact with the process and products. The critical area will often need to be protected by localised laminar flow.
The general area is the rest of the clean room where contamination will not have direct contact to the products but should be kept clean because of the transfer of contamination into the critical area.
My company also provides modules and wafer testing services to the industry. The clean room class we have for modules testing is at 100K 0.5µ and wafer test is set to class 10K 0.5µ but for wafer test, there are some specific requirements from our customer where they required the area surrounding the probers, transfer tools and scanners to be at class 1K 0.5µ. Note the critical and general area mentioned above to serve as a guideline.
The clean room class to follow will depend very much on the code of practise in your company as well as the product or services requirements.
thks.
jeffrey.