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

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-xNd 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 NdSn3 phases in the SCN0.15Nd/Cu solder joints, and the reason for this phenomenon has been briefly discussed.

► The combined effects of rare earth Nd and Ni elements on Cu–Sn interfacial IMC layer of solder joint are discussed for the first time. The research investigates the effects of trace amounts of Nd on properties and microstructure of Sn–0.7Cu–0.05Ni solder. Afterwards, the evolution of interfacial microstructures and properties of SCN solder joints with and without the presence of Nd under long-term room ambience condition was studied, which is essential for the property stability and reliability of solder joint.