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WASTE MINIMIZATION ASSESSMENT FOR A MANUFACTURER OF SILICON-CONTROLLED RECTIFIERS AND SCHOTTKY RECTIFIERS
Citation:
Edwards, H., M. Kostrezewa, P. Miller, AND G. Looby. WASTE MINIMIZATION ASSESSMENT FOR A MANUFACTURER OF SILICON-CONTROLLED RECTIFIERS AND SCHOTTKY RECTIFIERS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/S-92/036 (NTIS 93-123099), 1992.
Impact/Purpose:
to inform the public
Description:
The U.S. Environmental Protection Agency (EPA) has funded a pilot project to assist small- and medium-size manufacturers who want to minimize their generation of waste but who lack the expertise to do so. In an effort to assist these manufacturers Waste Minimization Assessment Centers (WMACs) were established at selected universities and procedures were adapted from the EPA Waste Minimization Opportunity Assessment Manual (EPA/625/7-88/003, July 1988). The WMAC team at Colorado State University performed an assessment at a plant manufacturing devices for converting alternating current into direct current (silicon-controlled rectifiers and Schottky rectifiers) — approximately 2.5 million units per year. Rectifier manufacture is a two step process: wafer fabrication and assembly. Silicon wafers are doped, spin coated, cleaned, and rinsed. Next, the wafers are etched and the resist is stripped to produce a final groove pattern. Layers of polysilicate and silicon nitride are deposited via chemical vapor deposition, silicon glass is fused to the surface ground, and then the wafer is cut into chips or dice. The dice are tested, sorted, and evaluated and then transferred to assembly. The team's report, detailing findings and recommendations, indicated that the majority of waste was generated by the stack scrubbers used to remove contaminants from exhausted plant air and that the greatest savings could be obtained by redirecting reject water from the reverse osmosis unit to the stack scrubbers to eliminate the wastewater stream from the reverse osmosis unit. This Research Brief was developed by the principal investigators and EPA's Risk Reduction Engineering Laboratory, Cincinnati, OH, to announce key findings of an ongoing research project that is fully documented in a separate report of the same title available from University City Science Center Colorado State University, Department of Mechanical Engineering University City Science Center, Philadelphia, PA.