Effect of P and Ge doping on microstructure of Sn-0.3Ag-0.7Cu/Cu solder joints

The microstructure and interfacial IMC layer of Cu/SACPG/Cu and Cu/SAC0307/Cu solder joints were comparatively investigated after thermal aging at 150°C for 0h, 24h, 168h and 500h, respectively. Results show that the morphology of IMC at the interface of Cu/SAC0307/Cu solder joint was consistent with that at the interface of Cu/SACPG/Cu joint, which indicates that the addition of P and Ge had little effect on the IMC formation. The tiny particles attached to the Cu
₆
Sn
₅
were Ag
₃
Sn phase and Ge from the study of three dimensional morphology of IMC. The addition of trace P and Ge in the alloy reduced the thickness of IMC layer and decreased the growth rate of IMC layer with aging time increasing, and had lower impact on the growth rate of IMC layer of Cu
₃
Sn.