Influence of Complexing Agents on Attaining Homogeneous Composition in SnAg Electroplating

The precise control of alloy composition during electrodeposition is crucial for obtaining desired material properties. In this study, a sequential electrodeposition approach was adopted to prevent the sedimentation of silver (Ag) species during the fabrication of tin-silver (SnAg) alloy. The addition of 1-allyl-2-thiourea (ATU) to the Ag bath prior to introducing the Sn bath effectively mitigated Ag precipitation. The reduction potential of Ag was influenced by ATU concentration, with higher concentrations leading to lower onset reduction potentials. The reduction potential stabilizes at 4 g/L ATU concentration, suggesting an optimization for the complexation effect.