A Comparative Study of Electroplated Palladium as a Contact Finish

In this study a lower cost replacement for gold as an electrical contact material has been investigated. In the initial phase of the study, the performance of hard gold, palladium, and palladium-nickel alloy both with and without a Soft go1d overlay were compared. ACtual connector hardware using these contact finishes were subjected to two tests: wear at elevated temperature and humidity and exposure tO a humid chlorine and hydrogen sulfide environment. The results of these tests were compared on the basis of resistance measurements of the connector contacts. As interest foCused on the use of a proprietary Bell System palladium with a gold overlay as a substitute finish, other connectors were evaluated including round and square pin contacts, bifurcated and trifurcated socket contacts, button type contacts, printed wiring board fingers, and card edge connectors. For all the cases studied a finish of 25-µ in pa!ladium With 1-µ in gold overlay has been found to be a suitable replacement for the gold contacts used on these devices and is now in use in several contact applications.