Influence of acid copper plating additives on void formation during high temperature storage

Formation of voids at the interface between Cu/Cu₃Sn or within Cu₃Sn phase can be observed when Sn plated on electrolytic copper surface is subjected to High Temperature Storage of 150°C for 1000 hours. In this study, acid copper plating system consists of organic additives was used for the copper plating process. Without copper plating additives brightener and leveller, minimum voids were distributed uniformly at Cu₃Sn phase. Addition of SPS or brightener to the system without leveller or PEG showed the density of voids became more and distributed along the Cu/Cu₃Sn interface. However, when leveller been introduced to the system containing the brightener, the cross section showed the voids were reduced and uniformly distributed along the Cu₃Sn layer.