The ability to count unwanted particles is of prime importance in “cleanrooms”— controlled environments where electronic, aerospace, pharmaceutical, and other products are tested or assembled. Cleanroom wipers, manufactured for these environments, must be carefully tested for particle count and fiber contamination. They are used to clean surfaces, apply liquids, and handle components.

As opposed to existing test methods that examine limited sizes, a new ASTM standard counts all sizes of wiper-particulates released, from <5mm to >100 mm. Now available,
E 2090, Standard Test Method for Size-Differentiated Counting of Particles and Fibers Released From Cleanroom Wipers Using Optical and Scanning Electron Microscopy, has been issued by ASTM Committee E21 on Space Simulation and Applications of Space Technology.

The test method was initially developed by wiper manufacturers’ technologists and submitted to ASTM to promote uniform methodologies and consistent data. After review and validation by space-industry scientists working on ASTM Subcommittee E21.05 on Contamination, it was balloted by the Society and approved in May.

According to the subcommittee, E 2090 provides a credible evaluation of the amount of particle and fiber contamination in wipers used in cleanrooms, and allows users of the wipers to reliably compare products in order to determine the risk factor when using such products in critical environments.

Over 20 pages of documentation are provided on test method procedures, apparatus, and materials used, etc. “When performed correctly, this counting method is sensitive enough to quantify very low levels of total particle and fiber burden,” the subcommittee stated in the document. “[The results] are not influenced by artifact or particle-size limitations. A further advantage to this technique is that it allows for morphological as well as X-ray analysis of individual particles.”

Robert Moss, the subcommittee chair, is organizing a round robin to garner valid interlaboratory comparisons and statistical analysis. “We recommend that anybody who is interested in particle counts on fabrics take a look at this,” said Moss, principal engineer, Space Systems/Loral, Palo Alto, Calif. “We think it’s worth at least trying on your products, and seeing how it works.” Wiper manufacturers, representatives of the electronics, aerospace, pharmaceutical industries, and other interested parties are invited.

To participate in the round robin, or for further technical information, contact Robert Moss, Space Systems/Loral, 3825 Fabian Way, Palo Alto, Calif. 94303-4604 (650/852-6018; fax: 650/852-6441). Committee E21 and Subcommittee E21.05 meet Oct. 24-25 during the IEST Space Simulation Conference Oct. 23-27 at the Radisson Hotel in Annapolis, Md. Conference registration is not needed to attend the ASTM meetings, which are free and open to the public. For meeting or membership information, contact Staff Manager Nancy McAvey, ASTM (610/832-9736). For IEST conference registration contact IEST (847/255-1561; or fax: (847/255-1699). //

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