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#3- Diffused Gold R156 a New Inlay Contact Material for Bell System Connectors from Materion Technical Materials

Abstract: This Materion Technical Materials paper explores field and laboratory investigations which indicated that Palladium and R156 (Pd40Ag) have marginal performance for high reliability connector applications because of contact resistance (CR) instability due to micromotions and/or atmospheric corrosion in some environments.

A series of binary and ternary inlay alloys with gold were developed to minimize these problems, and subjected to a screening evaluation consisting of corrosion, wear, thermal aging and micromotions due to vibration.

Diffused Gold R156

One alloy, having a gold rich surface, with an interior of R156, proved to have excellent contact properties combined with low cost. This material, called Diffused Gold R156 (DGR156), was selected for a comprehensive qualification test on the printed circuit board (PCB) connectors used in BellPac™ equipment. Its performance was virtually indistinguishable from plated cobalt hardened gold. Western Electric has switched from plated gold to the DGR156 inlay on the connector contact, resulting in significant savings in precious metal cost, as well as processing advantages.