Clean Room Considerations for Avoiding Molecular Contamination

Abstract

Control of contamination for optical products, especially those operating in the ultraviolet spectrum, is examined from three perspectives: materials involved, personnel controls, and environmental conditions. These control functions assume even greater significance when large clean room facilities are required for complex aerospace assemblies, and many clean room products or industry standard practices are not necessarily applicable. Every material introduced into a clean room environment is a potential contaminant, and must be reviewed as part of the operational screening process. Plastics commonly used in the design of clean room products can sometimes outgas and thus degrade optical performance. Facilities rework modifications, local or remote, can introduce contaminants into the air handling system which could produce deleterious effects on critical hardware. Lessons learned and the solutions that have been developed at Perkin-Elmer are discussed in several key areas: modular clean room procurement, verification of HEPA filters, clean room maintenance, design and operational certification and materials controls.