Cleanroom: A Brief Introduction.
A typical Cleanroom is an enclosed area in which the concentration of airborne particles is controlled to a desirable level. Cleanroom classifications are based on the number of particle counts per cube of air.
- Class 1 - 1 count/ cubic air ( particle size >/ = 0.5micron )
- Class 10 - 10 counts/ cubic air ( particle size >/ = 0.5micron )
- Class 100 - 100 counts/ cubic air ( particle size >/ = 0.5micron )
- Class 1000 - 1000 counts/ cubic air ( particle size >/ = 0.5micron )
Disk drives are commonly manufactured in Class 10 or Class 100 Cleanrooms whereby cleanliness is a critical factor. e.g particles may cause head crash when particle sizes are larger than distance between head and platter ( 0.25micron ) For comparison purposes: our hair is 100micron = 0.1mm
Basic Cleanroom Regulations / Common causes of contamination:
- Do not run as such actions cause greater air turbulence.
- No cosmetics allowed such as powder.
- Do not talk with face mask not covering mouth.
- Proper gowning procedures to be followed.
- Do not bring "unqualified" materials into Cleanroom.
Basic Products required for cleanliness control in a Cleanroom:
This mat is placed at door entrances to remove or minimize dust collected by the soles whenever personnel enter the cleanroom. Dust on the soles are attracted to the adhesive layer on the mat.
Usually installed at the entrance to Cleanrooms, the air shower or chamber is an efficient way to remove or minimize dust that are accumulated on the surface of the garments/ gloves.
Clean gloves serve as the first protection for products from contamination introduced by bare hands. Bare hands contain contaminants such as chloride and sodium. Common types of clean gloves include Nitrile, Latex and Vinyl.
A good garment system prevents the shedding of particles from civilian clothing to the environment. Common sources of particulation are cotton/jeans ( jumpsuit ), hair ( hood ), shoes ( booties ), facial hair/ skin cells( mask).
Clean wipers are ideal for general cleaning of parts, workstation and machines. Wipers designed for Critical Environment applications do not shed particles or experience linting. Most wipers consist of polyester or microfiber.
Cleanroom stationeries are specially formulated materials that are suitable for Critical Environment applications. These stationeries are different from the normal ones in terms of outgassing, particulation and ionic contamination. Examples of Cleanroom stationeries are Cleanroom paper, Cleanroom Files and Cleanroom pens.
Packaging serves as a mobile Cleanroom, protecting and transporting products from a location to another. The packaging correct material prevents the products from exposing to normal environment which is heavily contaminated. Ideal materials for Cleanroom packaging include LDPE bags, Nylon PE bags, Aluminium Moisture Barrier bags and Static Shielding bags.
Air ionizing systems generate large quantity of positive and negative ions to increase conductivity of air. As ions flow through the air, they are attracted to oppositely charged particles and surfaces. Neutralization of charged surfaces thus reduces the attraction of dust. Dust will be removed through air circulation by means of HEPA/ ULPA filters.