Whisker growth on tin finishes of different electrolytes

Whisker growth on tin finishes produced by three different plating baths (sulfate-based, alkaline stannate-based and stannous chloride-based) was observed by both optical and scanning electronic microscopy (SEM), the results showed that whisker growth on the finish plated by alkaline stannate bath is easier and faster than that on the finish plated by sulfate-based bath or stannous chloride-based bath. Furthermore, the alkaline stannate bath showed the lowest cathode current efficiency, and micro-nodules were observed after plating when using this bath. The reason for alkaline stannate bath to promote whisker growth is also discussed.