STUDY OF EFFECTS AND CONTROL OF SURFACE CONTAMINANTS ON ELECTRICAL MATERIALS
Abstract
The cause of objectionable contact resistance was studied in relay contacts used in millivoltmicroampere switching. Organic deposits form spontaneously on noble metal contact surfaces. Deposits formed over a period of weeks or months from a number of pure organic compounds and, as well, from rosin flux and from Teflon and Kel-F. Insulating deposits were detected with a fine wire probe and with the electron microscope. Frictional polymer, formed when metals are rubbed together in an organic environment developed from outgassing rosin flux and Teflon and Kel-F. Four metals were found to generate decreasing amounts of frictional polymer in the order: Pd, Au-alloy, Au, Ag, with the following approximate activity ratios: 100, 10, 2, 0.1. A non-destructive relay test for contact contamination was developed based on monitoring at dry circuit load levels and a contact resistance sensitivity of 0.1 ohm. The relays were put through a 7step schedule in which time, temperature, and relay cycling were varied. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 10, 1961
- Accession Number
- AD0261743
Entities
People
- Saul W. Chaikin
Organizations
- SRI International