Electrodeposition of Sn-Ag-Cu solder alloy for electronics interconnection

A pyrophosphate and iodide based bath was investigated for the electrodeposition of near-eutectic Sn-Ag-Cu alloy, which is one of the promising lead-free solder candidates for electronics interconnection. The bath contained pyrophosphate and iodide as chelating agents. The composition of electrodeposits were measured by wavelength dispersive X-ray spectroscopy (WDS). Different morphologies of deposited films were analysed using scanning electron microscopy (SEM). X-ray diffraction (XRD) data indicated that Sn, Ag
₃
Sn and Cu
₆
Sn
₅
were present in the ¿as-electroplated¿ film. The proposed bath was capable of fine pitch near-eutectic Sn-Ag-Cu solder bumps as demonstrated on a glass test wafer.