“Flexible” approach to contamination control meets goals

MT. PLEASANT, PA.-At the Sony Technology Center- Pittsburgh (STC-P; Mt. Pleasant, Pa.), the liquid crystal display (LCD) rear projection televisions and plasma-based direct view televisions assembled there contain extremely precise components; the slightest speck of dust or dirt can wreak havoc.

When considering contamination-control strategies, Sony opted out of a traditional hard-wall set-up in favor of curtain walls. Although curtain walls don’t offer the tightly sealed environment of a hard-wall cleanroom, Sony was able to enhance their performance by strategically positioning airflow in the space. Fan filter units (FFUs) fitted with HEPA filters force the dirt and dust in a specific direction, away from and out of the clean area.

According to Scott Olsen, manager of production support at STC-P, “Our ability to keep dirt, dust and debris out of the sets and off the optics is crucial to the production process for our products. If quality control spots any dirt on the set, we have to completely disassemble the set.”

Made of tear-resistant vinyl reinforced with polyester, curtain walls, manufactured by Goff’s Enterprises (Pewaukee, Wisc.; www.goffscurtainwalls.com), offer high tensile strength while remaining flexible. The polyvinyl material is water repellent, mildew- and rot-resistant, and is impervious to most harsh chemicals. It can withstand temperatures ranging from -40°F to +180°F, and has been certified flame retardant by the California State Fire Marshall’s office.

Cleaning Curtains from Golf’s Enterprises can be tailored to a desired height or width to match the needs of any location. Courtesy of Golf’s Enterprises.
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In the Sony facility, the curtain walls enclose a set of rooms within the assembly area. By erecting two 100-foot-long walls in two locations, Sony was able to divide the area into zones. The LCD television projection assembly area is housed in an 80-foot by 120-foot enclosure with an attached changing area for use by the 50 or so gowned employees accessing the space. An air shower in the floor of the changing area blows dust and debris off workers’ shoes, and workers are required to don booties, before entry into the assembly area. The conditions match that of an ISO Class 7 (Class 10,000) cleanroom.

Products and parts enter the room through a double-door interlock system. Goff’s motorized Power Roll roll-up doors are configured so that only one door can be open at a time. Once the inner door opens, dirt is pushed out of the room by the fans.

Opting for the curtain wall approach offered Sony a number of benefits. “Unlike the construction of a solid-wall cleanroom, we used our own labor to hang the curtain walls,” Olsen explains. In addition to the obvious cost savings, this approach affords flexibility down the road. “If we change our manufacturing arrangement, we take down the curtains and use new space that matches our needs.” III


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