Press-sinter-repress Ag-SnO/sub 2/ contacts with lithium and copper sintering additives for contactor applications

Ag-SnO/sub 2/ contacts have been made by extrusion for several years because it is easier to achieve high density by this method. However, the brittle nature of this material, especially with 12% or more oxides, resulted in high manufacturing cost. This paper discusses a patented material that uses sintering aids and special silver morphology to assist sintering to high densities. By this method, discrete contacts can be made by powder metal mixing, pressing, sintering and repressing to high densities. Electrical performance similar to extruded materials was obtained. Electrical test results including life testing at 90 A 240 VAC and weld strength comparisons are reported. The erosion process is discussed.

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