An examination of the metallic bonding of a clad material and two gold plating systems under constant force fretting conditions

Metallic bonding (cold welding) comparisons were made between a clad and two different gold plated contact materials under constant force fretting conditions. Previous experiments conducted at the Advanced Interconnections Laboratory showed that various material systems had different tendencies for metallic bonding. Three different material systems were selected to study this phenomenon. They were a thick gold plating, a gold flash over 80% palladium 20% nickel and a clad material (WE 1 over R156). Four different normal forces: 20, 50, 100 and 200 grams were used in this research project. Contact resistance data were collected using a four-wire measurement system with the open circuit voltage limited to 0.02 volts. Relative humidity was controlled to be 40%. The procedure for each experiment was as follows: tangential force was increased until the static coefficient of friction was exceeded, then a constant displacement was maintained until a wear track was established, then a constant force was maintained throughout the remainder of the experiment. Two sets of data were collected during each experiment: fret amplitude and contact resistance. The three material systems were statistically compared using analysis of variance techniques. They were compared on the number of fretting cycles needed to stop fretting motion, after a wear track was established.