Interfacial microstructure and properties of Sn–0.7Cu–0.05Ni/Cu solder joint with rare earth Nd addition

Abstract Interfacial microstructure and properties of Sn–0.7Cu–0.05Ni/Cu solder joints with trace amounts Nd additions have been investigated in this paper. The evolution of interfacial morphology of SCN solder joints with and without the presence of Nd under long-term room ambience was also studied. The greatest improvement to the solderability and tensile strength of SCN- x Nd are obtained at 0.05 wt.% Nd. Meanwhile, the morphology and growth of interfacial intermetallic (IMC) layer are greatly improved by adding Nd, and the propensity for IMC spalling from the interface of solder joint is definitely reduced with the presence of rare earth Nd, since the sponge-like structure was completely inhibited in the solder joint containing Nd. In addition, a significant amount of Sn whiskers were present on the surface of NdSn 3 phases in the SCN0.15Nd/Cu solder joints, and the reason for this phenomenon has been briefly discussed.