Effect of Measurement Conditions on Low-Level Contact Resistance

The degradation of low-level contacts can be characterized the evaluation of their contact resistance with time. There is no doubt, vever, that the measurement conditions have a definite influence on the faults. This has been shown by tests made in a polluted atmosphere containing 0.5 ppm hydrogen sulfide and 1 ppm sulphur dioxide under controlled temperature and relative humidity Conditions. Contact resistance measurements were made on significant samples at a low-level voltage mV) and with direct currents ranging from 0.1 to 100 mA. This enabled contact resistance distribution to be determined and its evolution followed by day for silver contacts. It was found that a test current of 100 mA, not suitable for characterization of low-level contacts over a period of ee weeks.