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#2- A Comparison of Precious Metal Contact Materials from Materion Technical Materials

Abstract: Two of the preferred methods of reducing the cost of electronic connectors are:

  • To minimize the thickness of the precious metal contact materials.
  • 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.

Precious Metal Comparison

In this Materion Technical Materials work, a series of gold and gold alloys, palladium, palladium silver and gold and palladium silver combinations were produced as inlay clad materials and were then 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 thicknesses of 30, 50 and 100 micro-inches 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
  • Pd40Ag