Palladium with a Thin Gold Layer as a Sliding Contact Material

A study has been carried out to evaluate two types of palladium contacts as a substitute for gold contacts presently used in connectors. Both types are electroplated palladium, one with a thin gold layer over it and the other without, Platings in this experiment were pure palladium from an alkaline bath (pH = 8.8) and pure gold from an acid bath (pH = 5.0). Although the gold was rather soft, its sliding properties, even with the thicker deposit, were as good as the acid hard gold deposits. Friction coefficients of the electroplated palladium investigated were 0.4-0.7. These values were quite large compared with the 0.15-0.3 of electroplated gold, and resistance to wear of the electroplated palladium was very poor. The proposed multilayer contact, which consists of electroplated palladium with a thin gold layer over it, exhibited friction properties similar to conventionally available gold contacts. The thin gold layer over the palladium acts as a lubricant between the harder palladium electroplates. Palladium itself showed good results in corrosion test performed in an 80%N2-20%O2 atmosphere containing 10 ppm H2S with a relative humidity of 90 percent at room temperature for 1000 h, and the palladium with the thin gold layer over it showed even better results.