Cleanroom in a box
01/01/2001
by Mark A. DeSorbo
Kit concept brings oven maker into realm of contamination control
These days, it isn't a stretch to have a softwall cleanroom project that goes together like an Erector Set or Lincoln Logs. And that's how Gus Rotstein, test area coordinator for Despatch Industries (Minneapolis), describes the high-performance industrial oven manufacturer's first cleanroom venture.
"We bought a special assembly," Rotstein says of the in-house project. "We already had the fans, filters and lights. We bought the frame and softwalls, which attached to the existing ceiling. It took us about three weeks, and we put [the pieces] together like they were Legos."
 Despatch Industries' ISO Class 7 softwall cleanroom. |
The frame and softwalls of the 600-square-foot ISO Class 7 (Class 10,000) cleanroom were purchased from Clean Air Products Inc. (Brooklyn Park, MN). Fans were purchased from Twin City Fan (Minneapolis). The cleanroom now enables Despatch to produce, test, deep clean and package the industrial ovens it sells to electronic, semiconductor, pharmaceutical and medical product manufacturers.
According to Rotstein, it is not common for industrial oven companies to have cleanrooms, mainly because normally targeted markets are not required to follow contamination control protocols.
Despatch customers began insisting on "deep cleaning" ovens before shipping. That required a controlled environment along with a process that uses solutions, such as isopropyl alcohol and deinonized water, as well as lint-free wipers and vacuuming.
"Deep cleaning allows us to get rid of any oily residues and, once the cleaning is approved, the oven is triple-wrapped in vacuum-sealed bags," Rotstein adds. "By building a cleanroom, we were not responding to competition, we were responding to our customer needs. When we ship an oven, it's turnkey."
Despatch allotted $70,000 for the project. The cleanroom, Rotstein says, is a vertical flow enclosure that has the characteristic plastic strip walls of a softwall environment. The floor received several coats of non-flaking white epoxy paint, making it easier to detect contaminants.
A positive air pressure environment, with an RH of 40 to 50 at temperature of 65 degrees Fahrenheit, is maintained 24 hours a day with fans within the 16-foot ceiling. HEPA filters clean external air drawn into the space.
The clean space, which is conveniently located next to the shipping area, is outfitted with filtered de-ionized water, dry air and dry nitrogen systems. Telephone and computer networking connects the cleanroom to the rest of the Despatch plant. A full range of tools and equipment, from low-particle-generation wipers to pump-carts for moving heavy equipment, is also on hand.
Like any project, there were some challenges, Rotstein says. "Suspending the ceiling was a challenge. We had to use ropes to bring one side up, hang it up, and then hang the other side. We had never done it before, so we were only doing five or six feet at a time. It took some time," he adds.
Another challenge was drafting cleanroom instructions for the 10 workers authorized to enter the space. "It wasn't an easy transition, but people have been good about following the protocol," Rotstein says.
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Personnel, he says, wear lab coats, foot covers and gloves, but head covers and full gowns are on hand just in case. Despite the softwalls, the cleanroom has one entrance, and anyone walking in will find himself on a sticky mat.
"We take precautions to keep the area clean. Any equipment that's brought into the cleanroom for testing, deep cleaning or packaging must first be thoroughly cleaned and inspected," Rotstein says, adding that the cleanroom was inspected by the Occupational Safety and Health Administration (OSHA) and built following Department of Labor regulations.
Despatch's cleanroom may get a facelift in the future by replacing the softwalls with a solid cleanroom structure.
According to Dr. Ken Goldstein, principal of Cleanroom Consultants Inc. (Scottsdale, AZ), this type of modular cleanroom is an economical way to retrofit a facility. However, it can never take the place of a conventional cleanroom utilized to manufacture semiconductors, pharmaceuticals and flat panel displays. Softwall cleanrooms are meant to be temporary, used for one to three years because components, such as the plastic sheet walls, dry out and crack over time. According to Goldstein, storage, assembly and testing are practical applications for softwall cleanrooms.