Cleanroom Packaging
Films: Beyond Clean

An AeroPackaging White Paper
By Stephen W. Van Someren

Quality Control Manager, AeroPackaging

Although he may not have realized it at the time, the wise old sage Francis Bacon was quite possibly the first person to recognize the importance of a higher standard of clean when he coined the phrase “Cleanliness is next to Godliness” nearly four-hundred years ago.

      And while Bacon may not necessarily have had cleanroom packaging in mind when he spoke those well-known words, he wasn’t far off the target when it comes to the significance of unyielding devotion to contamination control.

      As the requirements to identify and control all forms of contamination in the cleanroom environment have grown rapidly in the last ten years, the quest for control now encompasses many aspects, including the structural components, garments, cleaning chemicals, wipers, filtration media, and all process-related supplies used in the cleanroom environment. Users with critical needs are now also looking at the performance parameters of cleanroom packaging films with the same intensity.

A typical packaging application showing a wafer boat vacuum sealed in a clean poly bag

Consider your packaged product as a “traveling cleanroom,” basically a mini-environment providing protection from the outside world.

      These needs have reached a point where cleanroom bags labeled “Cleanroom Prepared,” “Packaged In A Class 100 Cleanroom” or “Cleanroom Admissible” does not achieve the real needs of most manufacturers in today’s swiftly changing world. Cleanroom packaging users must invest the energy to craft specifications and processes that will insure the integrity, quality and consistency of performance that the product demands, and that the customer expects. Only by taking steps to advance the science can the consistent quality of a packaged product be guaranteed.

      The advancement of product definitions and standards are being led by the users of cleanroom packaging in silicone wafer and hard disk media manufacturing, and in the vacuum deposition equipment industry. These users have a huge stake in high quality and absolute consistency with no room for “wild card” contamination from the packaging film being used. The products being packed by this class of user have the possibility of long-term contact with the packaging film; as a result, all contamination issues are amplified by the exposure time.

      Other industrial segments that are becoming more concerned with these same issues are also driven by the need to preserve the quality and consistency of their products, which include optics and lasers, critical filtration, wafer mask, high purity metal targets and any low ionic content product, such as PVA scrubbers.

      “Killer Contamination” does not refer simply to particles any longer. Previously, cleanroom packaging was evaluated by how clean it tested or — in the case of the labeling statements noted above — by feeling comfortable because the product was packed in a so-called “Cleanroom.” In the past decade, the challenges for total contamination control have evolved as quickly in cleanroom packaging as they have in the new ISO Global Cleanroom Standards.

      In his article “Saving The Most Complex For Last” (Cleanroom, December 2000), Richard A. Matthews discussed ISO’s recognition of the issue and the need for controlling outgassing, surface contamination transfer and airborne molecular contamination in the cleanroom. Quite simply, cleanroom packaging acts as a “mobile cleanroom” surrounding that critical product you have spent so much time engineering and producing. That mobile cleanroom — a bag — has the job of protecting your product from the very dirty outside world and, just as importantly, not causing degradation of the enclosed product.

      Clean film manufacturers have been investigating these issues as they have a direct impact on the packaged product, due not only to intimate contact with the packaging, but — in some cases — long-term contact as well. In studies performed by research scientists at Applied Materials, it was discovered that visible black contamination on wipers used to clean components prior to installation was residue from the use of anti-static polyethylene packaging. As a result, in 1997 a vigorous investigation was launched to understand the problem, with the result being an all-encompassing specification for all clean components. This is just one action being taken by very astute users.

      What was impressive about the Applied Materials specification was the effort that went into fully understanding the exact protection needs of each component, and the subsequent tailoring of the solution to the specific need. This is important for two reasons: the first being not to under-protect a product now or in its future development; the second being packaging cost control.

      Low particulate count may not be the only performance parameter to define in your packaging specification. Without question, particulate contamination is the first priority in cleanroom packaging. Most users have come to understand that they can expect and demand cleaner films now than they could in the past. Due to this, many critical users’ application specifications are calling for packaging films to qualify at a particulate level tested down to .5 microns instead of the more common NASA specifications, such as JSCM 5322, that at their most critical levels only test down to 5 microns. This is a strong example of how a packaging user has identified the “killer contamination” particle size and taken the steps to control it.

      Additionally, a new question about particulate is being asked: “What is the make up of the particles?” With the understanding that chemical contamination is a component of the particles being found in testing, we are now looking at ways to identify its composition. This information is critical for some medical device packaging and challenges involving chemical purity.

      All flexible cleanroom supplies wipers, gloves, garments and packaging films have physical limits to how clean they can be produced. Moreover, the flexible materials break down as they are used, releasing fibers or discharging small amounts of latex or vinyl from abrasion. Packaging films can also be abraded by the packaged product, releasing sub-micron particles. Standards and qualifications of all such products must consider these limitations, while the proper use of vacuum packaging procedures will greatly reduce the opportunity for abrasion from the film and reduce any internal abrasion between products.

“Beyond Clean” Continues…

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