Two-dimensionally patterned electrodeposition of Sn film from aqueous acid bath

The electrodeposition of two-dimensional Sn micropatterns without whisker growth was investigated using an aqueous acid bath. Polyethylene glycol suppressed the growth of Sn normal to the surface of a Cu foil substrate and flat Sn micropatterns were successfully obtained on various different photoresist-patterned Cu foils. The current efficiency of Sn electrodeposition was higher than 97% for all samples, although the pH of the solution was about 0.0, indicating that the overpotential of H2 evolution on the Sn/Cu substrate was quite large. Sn micropatterns, in the form of both lines and circles, showed a slight macroscopic stress relaxation effect.