Relay Contact Behavior Under Non-Eroding Circuit Conditions

When palladium or platinum-family metal contacts are operated in an environment which includes organic vapors, the performance of the contacts may be seriously degraded. If the contacts open and close currents, the contact erosion may be increased enormously. On the other hand, if the contacts merely prepare the circuit and do not directly open or close the current flow, no erosion will take place. The contacts may then fail to conduct the circuit current satisfactorily, because of the formation of an insulating polymer-like film. This latter type of failure has been the subject of extensive studies at Bell Telephone Laboratories for the past several years and is the subject of this article. These studies have yielded a new understanding of the contact problem and resulted in certain changes in relay contacts to improve their performance under service conditions.