Purdue University recently honored W. L. Gore & Associates, Inc, at a reception in the Birck Nanotechnology Center, for a donation of clean room garments to be used in the semiconductor research space of the center's Scifres Nanofabrication Laboratory, an ISO Class 3 (Class 1) facility.

"I have used Gore™ clean room garments since they were first designed," said John Weaver, facility manager of the center. "When I heard about this donation, I was thrilled, because these are state-of-the-art garments that will help us to achieve the maximum level of cleanliness in the clean room. These garments reduce contaminants, increase safety, and provide greater comfort for the researcher, which means that they can conduct more accurate and efficient research."

Gore™ clean room garments provide a more comfortable fit for the wearer for several reasons:

• First, the garments are made with a special Gore™ fabric that allows heat and moisture to escape.


• Second, the suits are available in 16 sizes plus custom, if necessary, minimizing spilling and tripping hazards caused by baggy sleeves and legs. The wearer is able to move about more freely, eliminating the "bellow effect," which can cause additional particle contaminants to be expelled into the clean room air.


• Third, because of superior filtration, a designated undergarment is not required. Unlike polyester garments, Gore™ clean room garments can be worn directly over street clothes, saving time and money.

The garments are made with a proprietary expanded polytetrafluoroethylene (ePTFE) membrane laminated to a 100% polyester knit. The ePTFE membrane does not allow particulates to pass through, making it an ideal protective barrier in a clean room garment. This membrane provides filtration efficiency of 99.9999% or better for particles measuring 0.12 micrometer or greater. However, the microporous structure of the membrane allows air to flow freely through the garment so that the wearer does not retain so much heat. These garments are non-shedding, and flame and chemical resistant. During testing, Gore™ clean room garments dissipated static in less than 0.1 second at 500-5,000 V when the wearer was making contact with grounded or antistatic flooring.

Weaver says that his first experience with the Gore™ clean room garments was a bit unusual. At the time, he managed Delco's advanced development facility, which was the first lab to be certified as a Class 10 (ISO Class 4) clean room. After talking with a Gore representative, Weaver decided to test the representative's claims about the effectiveness of these garments.

"To say that I came into this as a skeptic is an understatement. I was determined to design tests with a practical focus to see if these garments really performed the way Gore claimed," he said. Weaver worked closely with Gore's engineers to create a test protocol for the front-end and back-end of wafer manufacturing, including movement in and around the clean room. "I was astounded by the test results," he continued. "The cleanliness improved by orders of magnitude when Gore™ clean room garments were used. I was definitely convinced that this was a great product. This was the beginning of a 20-year relationship."

In the late 1990s, Weaver upgraded an entire manufacturing clean room to ISO Class 3 (Class 1) performance. By this time Gore™ ULPA filters had been introduced, and Weaver had installed them in various wet stations at Delphi. As part of the ISO Class 3 upgrade, Weaver converted these to Gore™ ULPA filters, rebalanced the airflow, and changed from polyester suits to Gore™ clean room garments.

"Again, I was in for a surprise," Weaver said. "We had a yield increase of three times what we had expected. It took us only four months to get the payback we had expected in one year."

Tests have shown that Gore™ clean room garments retain their filtration efficiency far better than polyester. Over the lifetime of a garment, with repeated washings, the weave of polyester tends to open up. According to Weaver, tests he did at Delphi Corp show that the barrier properties of the garments do not degrade. "We found that repairing Gore™ clean room garments provided us with a perfectly good product to use for at least three years. We saw no change in the filtration efficiency between a brand new garment and one that had been used and laundered for three years."

Drawing on almost 50 years of research in the field of fluoropolymers, W. L. Gore has proven experience in developing the state-of-the-art products needed in a clean room environment.

"During the 20 years I have worked with Gore engineers, I have found them to be very strong technically and extremely responsive to ideas about their products," Weaver concludes. "They have worked closely with me in every clean room project I have managed to make sure that we had the best production or research facility possible."