Effect of thiourea on electrochemical nucleation and electrochemical impedance spectroscopy of electrodeposited tin on a copper substrate in a sulfate bath.

The effect of thiourea on the electrochemical nucleation of tin on a copper substrate from a sulfate bath was studied using voltammetry, chronoamperometry, electrochemical impedance spectroscopy, and scanning electron microscopy. Without thiourea, electrodeposition of tin showed very poor surface coverage. However, re-nucleation and growth of tin occurred after the addition of thiourea. In particular, very rapid re-nucleation and growth behavior of tin were observed when up to 6 g/L of thiourea was added. Furthermore, impedance analysis allowed the estimation of the change in the growth behavior of tin when up to 6 g/L of thiourea was added.