Clean Room Supplies


Clean Room Supplies WaferWipe

Clean Room Supplies and their applications vary significantly. They include wipes, towels mops and sponges. Disinfectants used in clean rooms are both wiping alcohol and acetone. Fixed clean room supplies are: shoe cleaners, tacky mats and gowning racks. In the equipment arena, clean room supplies includes: steam cleaners, air filters, auto clave (sterilizer), and vacuum cleaners. Clean room supplies are extensively used in the semiconductor manufacturing industry. Critical cleanliness is the norm in the semiconductor manufacturing process. The need for clean room supplies is dependent upon the clean room itself.

Clean room supplies are a critical component of the clean room. The invention of the clean room is credited to Willis Whitfield during his employment at Sandia National Laboratories in 1960. His design was primarily a flow of clean filtered air being continuously pumped into the room. The pressure in the room is higher than outside the room. This makes sure that air flows out of the room preventing particles from being drawn into the clean room. This simple but effective process soon became fundamental to all clean rooms all over the world. Clean rooms have developed considerably since the invention in 1960. One of the fundamental steps in the development of the clean room is the clean room classification.

Clean room classifications are categorized by their cleanliness. Cleanliness is specified by the number and size of particles in a cubic meter of clean room air. The fewer the number of particles, the cleaner the clean room.  Air in the average home or offices has 1,000,000,000 particles that are 0.1 microns or larger per cubic meter. This is equivalent to ISO 9 clean room classification. By comparison, there are only 10 or fewer particles that are 0.1 microns or larger per cubic meter in a clean room classified as ISO 1. The table below lists the ISO standard for clean rooms.

 

Maximum Number of Particles/m³

Class => 0.1 μm => 0.2 μm => 0.3 μm => 0.5 μm => 1 μm => 5 μm
ISO 1 10 2.37 1.02 0.35 0.083 0.0029
ISO 2 100 23.7 10.2 3.5 0.83 0.029
ISO 3 1,000 237 102 35 8.3 0.29
ISO 4 10,000 2,370 1,020 352 83 2.9
ISO 5 100,000 23,700 10,200 3,520 832 29
ISO 6 1,000,000  237,000  102,000 35,200 8,320 293
ISO 7  10,000,000 2,370,000 1,020,000 352,000 83,200 2,930
ISO 8 1 E8 2.37 E7 1.02 E7  3,520,000  832,000 29,300
ISO 9 1 E9 1.37 E8 1.02 E8 3.52 E7 8.32 E6  193,000
 

The selection of clean room supplies is dependent upon their capability at various clean room classifications. The most significant attribute of clean room cleaning supplies is the ability of not generating particles. But more specifically, only generating particles that are in line with the classification of the clean room in question. The base material for the clean room cleaning supply is the most significant factor in determining the suitability for various clean room classifications.

There is a wide range of materials used in the manufacture of clean room supplies. Looking specifically at a group of clean room supplies, say wipes and sponges, we find that the material ranges broadly from traditional organics to the more modern synthetics. The traditional materials are cotton and paper.  The synthetic materials are: nylon, polyester, cellulose polyester blend, micro fiber and the most advanced is molded plastics. The organic materials create a lot of particles. They are ideal for clean rooms that are at the lower end of the classification. Of the synthetic materials, polyester and polyester blends and nylon products work well for clean room in the center of the classification spectrum. Molded plastic and microfibers are used for clean rooms at the high end of the range of clean rooms.

Water absorption is also an important attribute for clean room cleaning supplies. It is a major factor when: removing contaminates from work surfaces, cleaning of clean room equipment and clearing up spilled liquid. It is the material of the cleaning supply that determines absorbency.  Products made of organic material are the least absorbent. Of the synthetics: polyester, polyester blends and nylon are the least most absorbent. Micro fibers and molded plastics have the best absorbency at up to 600% of water by weight.

In selecting clean room supplies, attention must be paid to the specific environment that the products will be used. Refer to the table in on this page for the various clean room classifications. When clean room wipes and sponges are being considered, the three main properties are: absorbency, particulate generation (or the lack there of) and life time.