Effects of Cu and Ni additions to eutectic Pb-Sn solders on Au embrittlement of solder interconnections

Effects Cu and Ni additions on Au embrittlement of eutectic Sn-Pb solder interconnections during a solid-state aging treatment were evaluated using a ball shear testing method. The addition resulted in a formation of Au-containing ternary intermetallic compounds, either Au-Sn-Cu or Au-Sn-Ni phase, inside the solder matrix during aging treatment. The fracture energy of the solder interconnection containing 2.9 wt% Cu remained almost the same up to 200 h of aging treatment at 150 °C, demonstrating the possibility of suppressing the Au embrittlement by forming ternary intermetallic phases inside the solder matrix.