Phase field simulation of interface evolution behavior of copper–tin micro-solder joints under thermal–mechanical–electrical coupling

Abstract

The thermal–mechanical–electrical-diffusion strongly coupled equations are established, and the phase field method is employed to investigate the dynamic simulation of intermetallic compound (IMC) evolution at the Cu/Sn/Cu micro-solder joint interface. By comparing with experimental results on IMC evolution in micro-solder joints, this study explores the evolution law of IMCs under the influence of current, temperature, and applied load coupling. Both simulation and experimental findings indicate that higher current density promotes IMC formation, with the largest average thickness observed at a current density of 5000 A/m2. When the analog current density is 5000 A/m2, the anode IMC has a rapid growth period at 62 h, and the corresponding cathode has a rapid consumption period; when the analog current density is 4000 A/m2, the anode has the same phenomenon in 95 h; when the analog current density is 3000 A/m2, this phenomenon is not evident. The observed phenomena are consistent with the evolutionary trend of IMC from the fourth to the fifth day of the experiment, considering it may be affected by ‘electronic wind stress’ which makes the cathode IMC migrate to the anode. The average thickness of IMCs with an analog ambient temperature of 323–353 K is the largest, which is most suitable for the growth of IMCs. The experimental results also indicate that IMC growth is the fastest at 353 K. The anode IMC was inhibited by tensile stress and shear stress, but the effect on cathode was not obvious.