Lubricant-induced corrosion in copper electrical contacts

We report that a high performance switch grease tested by the standard ASTM method for corrosivity to copper produced little visual tarnish. However, when tested in thin layers, as would occur in the application, corrosion layers occur in excess of that seen using the ASTM method. Optical and electrical measurements were used to characterize the layer. Contact resistance measurements with and without wiping action are reported. Infrared absorption spectra of the thin layer of lubricant on copper show changes in the lubricant after thermal aging as compared with aged material not in close proximity with the metal. It will be discussed that for a thin layer of lubricant on copper experiences a more accelerated corrosion.