Interface behavior and performance of Sn–Ag–Cu lead-free solder bearing Tb

To further improve the performance of the Sn–3.5Ag–0.5Cu solder, trace amount of rare earth Tb was added. The wettability, shear strength and interface compounds (IMCs) were investigated in this work. The finding indicated that the addition of the Tb element in the Sn–Ag–Cu solder could delay the formation of IMCs during soldering, and the thinner IMC layers were obtained. The maximum shear strength can be found with 0.025 wt% Tb addition, and the wettability of the solder could be somewhat improved. Moreover, the addition of 0.025 wt% Tb could slow down the growth of IMC during aging, which was of great significance to extend the reliability of the joint interface and the service life of the solder joint. This work has provided a theoretical basis for the development and application.