Cleanroom

A cleanroom or clean room is a laboratory facility ordinarily utilized as a part of specialized industrial production or scientific research, including the manufacture of pharmaceutical items and microprocessors. Cleanrooms are designed to maintain extremely low levels of particulates, such as dust, airborne organisms, or vaporized particles. Cleanrooms typically have a cleanliness level quantified by the number of particles per cubic meter at a predetermined molecule measure. The ambient outdoor air in a typical urban area contains 35,000,000 particles for each cubic meter in the size range 0.5 μm and bigger in measurement, equivalent to an ISO 9 cleanroom, while by comparison an ISO 1 cleanroom permits no particles in that size range and just 12 particles for each cubic meter of 0.3 μm and smaller.b These concentrations will lead to large air sample volumes for classification. Sequential sampling procedure may be applied; see Annex D.c Concentration limits are not applicable in this region of the table due to very high particle concentration.d Sampling and statistical limitations for particles in low concentrations make classification inappropriate.e Sample collection limitations for both particles in low concentrations and sizes greater than 1 μm make classification at this particle size inappropriate, due to potential particle losses in the sampling system.f In order to specify this particle size in association with ISO Class 5, the macroparticle descriptor M may be adapted and used in conjunction with at least one other particle size. (See C.7.) A cleanroom or clean room is a laboratory facility ordinarily utilized as a part of specialized industrial production or scientific research, including the manufacture of pharmaceutical items and microprocessors. Cleanrooms are designed to maintain extremely low levels of particulates, such as dust, airborne organisms, or vaporized particles. Cleanrooms typically have a cleanliness level quantified by the number of particles per cubic meter at a predetermined molecule measure. The ambient outdoor air in a typical urban area contains 35,000,000 particles for each cubic meter in the size range 0.5 μm and bigger in measurement, equivalent to an ISO 9 cleanroom, while by comparison an ISO 1 cleanroom permits no particles in that size range and just 12 particles for each cubic meter of 0.3 μm and smaller. The modern cleanroom was invented by American physicist Willis Whitfield. As employee of the Sandia National Laboratories, Whitfield created the initial plans for the cleanroom in 1960. Prior to Whitfield's invention, earlier cleanrooms often had problems with particles and unpredictable airflows. Whitfield designed his cleanroom with a constant, highly filtered air flow to flush out impurities. Within a few years of its invention in the 1960s, Whitfield's modern cleanroom had generated more than US$50 billion in sales worldwide (approximately $398 billion today). The majority of the integrated circuit manufacturing facilities in Silicon Valley were made by three companies: MicroAire, PureAire, and Key Plastics. These competitors made laminar flow units, glove boxes, clean rooms and air showers, along with the chemical tanks and benches used in the 'Wet Process' building of integrated circuits. These three companies were the pioneers of the use of Teflon for airguns, chemical pumps, scrubbers, water guns, and other devices needed for the production of integrated circuits. William (Bill) C. McElroy Jr. worked as engineering manager, drafting room supervisor, QA/QC, and designer for all three companies and his designs added 45 original patents to the technology of the time. McElroy also wrote a four page article for MicroContamination Journal, wet processing training manuals, and equipment manuals for wet processing and clean rooms. Cleanrooms can be very large. Entire manufacturing facilities can be contained within a cleanroom with factory floors covering thousands of square meters. They are used extensively in semiconductor manufacturing, Solar panel, rechargeable battery, LED, LCD and OLED display manufacturing, biotechnology, the life sciences, and other fields that are very sensitive to environmental contamination. There are also modular cleanrooms. The air entering a cleanroom from outside is filtered to exclude dust, and the air inside is constantly recirculated through high-efficiency particulate air (HEPA) and/or ultra-low particulate air (ULPA) filters to remove internally generated contaminants. Staff enter and leave through airlocks (sometimes including an air shower stage), and wear protective clothing such as hoods, face masks, gloves, boots, and coveralls. Equipment inside the cleanroom is designed to generate minimal air contamination. Only special mops and buckets are used. Cleanroom furniture is designed to produce a minimum of particles and is easy to clean. Common materials such as paper, pencils, and fabrics made from natural fibers are often excluded, and alternatives used. Cleanrooms are not sterile (i.e., free of uncontrolled microbes); only airborne particles are controlled. Particle levels are usually tested using a particle counter and microorganisms detected and counted through environmental monitoring methods. Polymer tools used in cleanrooms must be carefully determined to be chemically compatible with cleanroom processing fluids as well as ensured to generate a low level of particle generation. Some cleanrooms are kept at a positive pressure so if any leaks occur, air leaks out of the chamber instead of unfiltered air coming in.