Aqueous cleaning of vacuum tube components, replacing 1,1,1, trichloroethane

The first process step in the production of a specialty vacuum tube at the Hewlett-Packard Santa Clara Division has been to clean all of the hardware in a 1,1,1, trichloroethane (TCA) degreaser. However, due to the inclusion of TCA in the Montreal protocol and in the proposed EPA labeling regulations, a permanent environmentally suitable solution had to be found. The challenge was to find commercially available aqueous cleaners (saponifiers) that would remove light machine shop oils and particulates so that the parts would be clean enough to be placed in moderate (10^-6 torr) vacuum atmosphere with no functional degradation. Sample parts and subassemblies were contaminated with sample soils and then cleaned with candidate cleaners. Detailed analyses have shown aqueously cleaned parts to have lower contamination levels than the vapor degreased parts. Details of the materials cleaned, saponifiers used, and test results are presented