| 摘要 |
PROBLEM TO BE SOLVED: To provide an enectrolytic silver plating bath with which plating stage is simplified, and also, electrical contacting properties and corrosion resistance of a plating film can be improved, and to provide a silver plating method. SOLUTION: In this free cyanogen electrolytic silver plating bath for stainless steel, tin or a tin alloy, concentration of silver ions is 0.02 to 55 g/L, concentration of halide ions is 1 to 550 g/L, and pH is controlled to -1.0 to 2.0. Thus, by using stainless steel, tin and a tin alloy having high contact resistance as a base material and depositing a silver plating film on the base material, its electrical contacting properties can be improved. Further, by adding a crystal controlling agent, uniformity of the film thickness is improved, and, since the silver plating film having high adhesion is directly deposited on the base material, the plating stage can be simplified. Moreover, even if an acidic solution infiltrates through the pinholes of the silver plating film in an acidic atmosphere, the base material itself has corrosion resistance, and, therefore, the adhesion of the silver plating film is not damaged by the corrosion of the base material, so that the increase of its contact resistance can be suppressed.
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