IEST thanks US WG 1 expert Joe Gecsey for his contribution to this article:
The community of cleanroom and clean device users have long relied on the ISO 14644-1 standard (and the United States Federal Standard 209E preceding it) to gain assurance that their working environment is suitable for the intended use.
ISO 14644-1 was released in 1999 and a revision process was started after the end of the Systematic Review period in 2005. Now, Working Group 1 (WG1) of the Technical Committee 209 has completed an update to this important document and a new version of ISO 14644-1 – known as ISO 14644-1:2015 – has been published.
Lively debates within the revision group of international experts and users revolved around the need to put the classification method on a more solid statistical foundation without significantly affecting the historical data users already had for their classified areas. The end result requires a modest increase in the number of sample positions for almost all areas; the fundamental data gathering method remains unchanged. In order to make new users more comfortable with the classification process, more
guidance is now provided, such as examples of assessing PASS/FAIL of various sets of particle counts.
Another notable shift is the increased emphasis on monitoring the cleanroom environment between the formal classification events so as to provide an on-going sense of the area’s suitability for the intended purpose. Thus ISO 14644-2:2015 contains more details on developing and executing a monitoring plan, including informative appendices on monitoring differential pressure and particle counts. The challenges of setting alarm values such as Alert and Action limits for these parameters are outlined; the appendices offer some possible approaches to accomplish effective sampling and for setting alarm values.
Cleanrooms and clean devices are used in many, many industries and in many different ways; authoring a document that takes into account all these users and applications was a daunting task. With this latest revision, users will be able to have greater confidence that their cleanroom or clean device will support the intended use.