Reaction of Contact Materials With Vapors Emanating from Connector Products

The interaction of organic vapors, evolving from connector housings, printed Wiring boards (PWB's), and wire insulations, etc., with the connector contact materials may cause the formation Of surface films and a contact resistance (CR) increase. In this study, the results of an experiment to study the effects of outgassing of different plastics on various contact materials are presented. The contact materials used in this study were Au, WE #3 metal (70Au, 30Ag), Pd, R156 (60pd, 40Ag), DG Pd (diffused gold palladium), and DG R156 (diffused gold R156); the plastics employed were from connectors used in BELLPAC® backplanes, PWB's, and polyvinyl chloride (PVC) coated wires. The material systems Were exposed up to four months at two different environmental conditions: a) 120°C and b) 60°C at 95 percent RH. Condition a) was found to be more severe on material systems from a contact resistance standpoint than condition b). Recommendations for the appropriate acceleration tests are made based upon these experimental results.