Abstract
Two of the preferred methods of reducing the cost of electronic connectors are: a) to minimize the thickness of the precious metal contact materials and b) to select lower cost materials. Although the search continues for a suitable non precious contact material, the requirements of high reliability connectors dictate the selection of precious metals for most applications. Although gold remains the industry standard, gold and gold alloys added as a cover over palladium and palladium silver alloys continue to gain acceptance as lower cost alternatives.
Pure gold has optimum nobility for contact corrosion resistance. When lower cost alternatives are used, their performance in potentially corrosive environments is of major concern and interest. In this work, a series of gold and gold alloys, palladium, palladium silver and gold, palladium silver combinations were produced as inlay clad materials and exposed to battelle environmental gas mixtures containing H2S, Cl2 and NO2. The data subsequently generated is offered for possible assistance in contact material selection.
Precious metal performance was compared by measurement of contact resistance. To avoid the complication of creep corrosion products from copper alloy base metals, all precious metal combinations were inlaid into a wrought nickel. A manufacturing sequence typical of inlay cladding for connector spring materials was used for all metal combinations. Precious metal thickness of 30, 50 and 100 microinches were evaluated. The following alloys, listed in order of increasing contact resistance, were tested; Au, Au"capped"Pd40Ag, Au4Ni"capped"Pd40Ag, Au4Ni"diffused"Pd40Ag, WE#1"capped"Pd40Ag, WE#1, Au25Ag, WE#1:diffused"Pd40Ag, 70Au24Ag6Cu, Pd, and Pd40Ag.
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