A gowning room at the entrance of a microelectronics factory in southern England, on a steel rail a row of hanging clean-room smocks of pale blue slightly glossy fabric with a fine dot pattern, each with a stand-up collar, a central zip and an elastic hem, beside them pale blue hoods with shoulder capes and a rectangular face opening, on a white bench folded pale blue trousers, white nylon gloves and pale blue overshoes, a person in a pale blue smock seen from behind pulling a hood down over the head, behind a glass door a corridor glowing amber yellow, white walls, bright fluorescent light from above.
What it was used for
A cleanroom suit does not protect the person from the room; it protects the room from the person. The cleanroom builder Schilling Engineering states that a person standing still in cotton clothing releases over 800,000 particles larger than 0.5 micrometres per minute, about 35 million per minute at a leisurely walk, and still about 10,000 per minute standing still in a cleanroom coverall with eye cover. A single sneeze, on the same account, releases up to 1.4 million particles. The clothing is therefore not an accessory to production but part of it.
What was new
What is characteristic is that the demand for cleanliness is driven by feature size, not by hygiene. On 13 February 1987 Computerwoche wrote of the Siemens memory with 1.2 micrometre features that air filtration had to be markedly improved, because smaller particles sharply raised reject rates. The barb: by Schilling's account most of the small, invisible particles that can contaminate a product come from people - that is, from the person operating the wafer. The suit cuts that output, by Schilling's figures, from 800,000 to about 10,000 particles per minute, but does not remove it.
What the sources leave open: The particle figures come from a present-day cleanroom builder's page, not from a 1980 measurement; no source with period measurements was found. The page gives no percentage for the share of contamination caused by people. This entry documents no particular garment model or maker.