Anyone who has navigated the wonderful world of standards will appreciate “The Awful German Language,” Mark Twain’s iconic essay about the challenges in navigating sentence structure. The English language can be even more awful, even more subject to interpretation. There is a need for simplicity and clarity in standards and specifications. Understanding the nuances of complex documents, especially those written by individuals with diverse backgrounds, takes a bit of concentration. This is particularly important where standards are used for many different types of high-value product that are used in microelectronics, medical, and aeronautic applications.
With this in mind, consider a concentrated review of ISO 14644, Parts 9, 10, and 13.1-3 All three parts are concerned with surface cleanliness in the cleanroom. Then, consider partnering with your supply chain to assure that everyone is on the same page, and that you are using the documents in a consistent, coordinated manner.
Parts 9, 10, and 13 are all concerned with surface cleanliness in cleanrooms and controlled environments. Part 9 classifies concentration of particles on surfaces. Part 10 classifies surface cleanliness by chemical concentration. Part 13, still in the final approval cycle, deals with approaches to cleaning of surfaces to achieve desired levels of surface cleanliness in terms of particles and chemicals.
As a U.S. ISO expert involved in standard development, specifically in the working group developing Part 13,4 Barbara made what we consider to be an astonishing discovery. In the course of standard development, Barbara discovered that all three parts are meant to specifically exclude the actual product produced in the cleanroom. While the standards contain phraseology that some could interpret as the product surface, it was made clear that the product produced in the cleanroom is excluded. One reason we were both astonished is that we expect that cleanrooms and controlled environments are not ends in themselves — rather, they are tools to achieve and maintain cleanliness of the product being produced within that environment.
Another reason that we are astonished at the product exclusion has to do with a lack of coherence with other significant iconic and even relatively recent standards. While some parts of ISO 14644 mesh relatively well with other long-established standards, Parts 9, 10, and 13 do not. Federal Standard 209 specifically dealt with airborne particles in cleanrooms and clean zones; the 1992 version E was the last version before it was retired; we traced it back to 1963.5
The conversion to ISO 14644 (Part 1) conceptually and philosophically stays on the same page in terms of scope. In contrast, MIL-STD-1246C,6 which also traces back to the 1960s, specifies product cleanliness levels in terms of particles and non-volatile residue (NVR). In the late 1990s, the military commissioned the Institute of Environmental Sciences and Technology (IEST) to move 1246 to an industry standard. As indicated in the 2013 version,7 IEST-STD-CC1246E deals specifically with product cleanliness and it also quantifies levels of particle contamination and molecular contamination. When we get to surface contamination, moving to ISO results in a disconnect; this disconnect means a lack of clarity.
What’s the product surface?
We have voiced our concerned about this lack of clarity; we are happy to report that, as of the time of writing, the latest version of Part 13 includes an unambiguous exclusion of the product. While we don’t agree with this exclusion, we think it is important to clearly state any intended exclusions to allow good discussions to take place.
We are concerned about excluding product, because cleaning is a continuum.8 Where do you draw the line between product, product contact, and equipment? Based on our own informal inquiries, great minds may not think alike.
Communicate and clarify
The ISO 14644 series is very general, and it can be used in many different types of manufacturing. We live in a global economy; many manufacturers of high-value product employ a global supply chain. Specialized contract manufacturers may supply components to a wide variety of customers including aerospace, military, microelectronics, and medical. As wide-ranging documents, ISO standards may be used in setting contracts. It seems to us that a final assembler could specify a 14644 ISO standard in terms of product surface quality whereas the supplier could understand it to mean cleanroom surface quality only. The undesirable consequences of a disconnect in the supply chain in understanding and expectations of standards could be enormous.
As we indicated, we were astonished by the exclusion of product produced in the cleanroom or controlled environment. However, many people may expect that product produced in the cleanroom is excluded from Parts 9, 10, and 13. This difference in understanding is where we may have unacceptable ambiguity in the fabrication and assembly process.
Parts 9 and 10 have been published; and they may be used to specify cleanliness levels in critical applications such as microelectronics, avionics, military, and medical applications. We are hopeful that the scope of Parts 9 and 10 will be clarified as expeditiously as possible, even if it means that product surfaces are excluded. In the meantime, these problems with “the awful English language” provide an opportunity for clarifying discussions throughout the supply chain. In a recent column,9 experts in the field of contract manufacturing, including auditors and manufacturers, discussed the growing trend toward third party auditing and the importance of partnering. Because language can be subtle and nuanced, “command and control” type audits can be counterproductive. By partnering and by clarifying requirements, we can help assure that everyone is on the same page — or at least on the same surface!
1. ISO 14644-9:2012 “Cleanrooms and associated controlled environments — Part 9: Classification of surface cleanliness by particle concentration.”
2. ISO 14644-10:2013 “Cleanrooms and associated controlled environments — Part 10: Classification of surface cleanliness by chemical concentration.”
3. ISO/DIS 14644-13 “Cleanrooms and associated controlled environments — Part 13: Cleaning of surfaces to achieve defined levels of cleanliness in terms of particle and chemical classifications” (being finalized as of writing).
5. FED-STD-209E, Federal Standard: Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones, Sept. 11, 2992 [S/S BY ISO14644-1 AND ISO14644-2], http://everyspec.com/FED-STD/FED-STD-209E_21739/.
6. MIL-STD-1246C Product Cleanliness Levels and Contamination Control Program (Military Standard).
7. IEST-STD-CC1246E: Product Cleanliness Levels- Applications, Requirements, and Determination (2013).
8. B. Kanegsberg and E. Kanegsberg, “Clean the Cleanroom, Clean the Product,” Controlled Environments, July/August 2014. http://www.cemag.us/article/2014/07/clean-cleanroom-clean-product
9. B. Kanegsberg and E. Kanegsberg, “20/20 Vision: Higher Expectations for Contract Manufacturers,” Controlled Environments, March/April 2016. http://www.cemag.us/articles/2016/03/2020-vision-higher-expectations-contract-manufacturers
Barbara Kanegsberg and Ed Kanegsberg (the Cleaning Lady and the Rocket Scientist) are experienced consultants and educators in critical and precision cleaning, surface preparation, and contamination control. Their diverse projects include medical device manufacturing, microelectronics, optics, and aerospace. They can be reached at [email protected].