Smooth and semibright to bright Pd-Ag alloy electrodeposits were obtained from an ammoniacal alkaline solution. Silver co-deposition took place under mass-transport-controlled conditions. The Pd-Ag alloy system conformed to the regular type of alloy deposition, one of the five types of alloy-plating processes classified by A. Brenner, and, in this plating bath, Ag, the less noble metal in the standard electrode potential, behaved as the more noble one, as was clearly shown by polarization behavior.
To evaluate Pd-Ag alloy deposits from an applicational viewpoint, properties such as contact resistance, solderability, hardness, and corrosion resistance were compared with those of hard gold. In conclusion, Pd-Ag alloy plating is a useful substitute for hard gold in contact application.