抄録
Pulse plating of tin in an acidic stannous sulfate bath without the presence of additives was studied with regards to the polarization curve, current efficiency, and the morphology of deposit. The polarization curves exhibit a well-defined Tafel line with a slope of 54-67mV/decade at high current densities. The minimum current density, where the Tafel relation holds, increased with decreasing pulse ratio (on-time/off-time). On the other hand, current efficiency decreased with decreasing pulse ratio, mainly because of the charging of the double layer. The deposits plated with long pulse time or direct current were of either needle-type or dendrite. Smooth deposits were obtained at the conditions of short pulse time and high current density. The conditions for obtaining the smooth tin deposits of fine grains were discussed in terms of current density and pulse time.
