A Statistical Evaluation of Contact Resistance in Silver and Silver Alloys

For the purpose of a statistical evaluation of dynamic contact resistance in a medium energy range, a new automatic test instrument was designed. Using this instrument, contact resistance was automatically measured and the data were punched into paper tape which was subsequently processed by a computer. Reproducibility of the data was examined for pure silver contacts under various test conditions. This method was applied to the test of Ag-CuO and Ag-Fe2O3alloy contacts. The results are summarized as follows. 1) The reproducibility of the data is very good in view of the statistics. The influence of the test conditions is discussed in detail. 2) Contact resistance in Ag-CuO alloy contacts containing up to 10 percent CuO is lower than that of pure silver contacts. 3) In Ag-Fe2O3alloy contacts, an unusual contact resistance distribution with two separate peaks was observed. Further, we discussed a model explaining the wide scattering of dynamic contact resistance.