Silver tin oxide contact erosion in automotive relays

Abstract

The erosion properties of a silver tin oxide contact material used in automotive DC relays were evaluated as a function of current and life cycles in lampload switching. The eroded surfaces were analyzed and an erosion mechanism based on transfer interface fracture was presented to explain the contact resistance, material transfer and welding properties of the silver tin oxide contact material. Pip and crater formation in silver tin oxide are small because of a weak deposit/cathode interface that resulted in delamination of pips.