Growth kinetics of intermetallic compounds and tensile properties of Sn–Ag–Cu/Ag single crystal joint

The growth kinetics and interfacial morphologies of intermetallic compounds (IMCs) and tensile properties of single crystal Ag/Sn–3.8Ag–0.7Cu (SAC) solder joint were investigated by solid-state aging at 170 °C and liquid-state aging at 250 °C. It is found that the growth kinetics of IMCs under both solid- and liquid-state aging conditions follow parabola relationship. Accordingly, the diffusion coefficients under the two conditions were calculated to be about 2.50 × 10−17 m2 s−1 and 1.60 × 10−14 m2 s−1, respectively. With increasing aging time, the scallop-like morphology of the IMC gradually evolved into planar type after solid-state aging; but it became rougher after liquid-state aging. Meanwhile, the average grain size of IMC also increases with increasing aging time. The tensile strength of the Sn–Ag–Cu/Ag single crystal joints did not decrease seriously with increasing aging time and the corresponding tensile fracture mechanism was discussed.