Electrodeposition of Pd-Ag alloy for electrical contacts

초록

Pd-Ag alloy electrodeposit was proposed as a protective coating for electrical contacts. Before Pd alloy deposition, Ni was electroplated on a Cu substrate to limit Cu diffusion into the Pd coating. Pd-Ag alloy coatings with different Ag content were obtained using electrodeposition. Ag atomic per cent in the coatings was changed by varying the Ag mass concentration in the bath solution. Subsequently, the coated substrate experienced heat treatment at 260 degrees C for 600 s. The contact resistance of the Pd-based coatings decreased along with the increase in the Ag content, but that of heated coatings increased. Furthermore, the wettability of the Pd-based coatings with solder was enhanced owing to the increase in Ag quantity. The qualitative analysis indicated that Pd-Ag coatings inhibited Ni diffusion to the surface, which would be oxidized during heat treatment, diminishing contact resistance and wettability.

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