High cycle fretting corrosion studies on tin-coated contact materials

The high-cycle (above 20,000) fretting contact characteristics of matte tin-plated copper are reported in this paper. Current loads extended from 0.1 mA to 100 mA with an open circuit voltage of 12 V. As observed in the past, there is a plateau in the contact resistance versus fretting cycles above 20,000 cycles. Here, we report on changes in the plateau as a function of load current. Box plots of the median values of the distribution of contact resistances show a dramatic decrease with increasing current. Contact voltages are also seen to range from 1 to 12 V, depending on the current. These results are discussed in terms of changes in the granular interface between the contacts with increasing current.