The effect of test environment on the creep of base metal surface films over precious metal inlays

An evaluation of two precious-metal inlays, WE #1 (69Au25Ag6Pt) and diffused gold-palladium-silver, in combination with several base metals (C72500, C52100, C65400, C17200), which were exposed to a range of severe environments, is discussed. The materials were exposed as (a) bare coupons and (b) assembled connectors. The environmental exposures were carried out in a laboratory test chamber using Battelle Class II and III atmospheres, respectively. The chamber test periods simulated outdoor life exposures of 2-20 yr for Battelle Class II and 1-10 yr for Battelle Class III. Sample coupons and connectors are characterized by measurements of contact and low-level circuit resistance, respectively. The beneficial effects of a protective layer over copper alloys to prevent creep of corrosion products were demonstrated. Two methods, the use of a commercial lubricant and the shielding of a connector housing, were used to retard corrosive attack and creep