Effects of Ag3Sn nanoparticles and isothermal aging on IMC layer growth, mechanical properties, and life prediction of SAC305/Cu solder joints

In this paper, Ag3Sn nanoparticles were prepared by chemical method and added into SAC305 solder in different proportions to explore the effects of the Ag3Sn on the wettability, melting performance, metallographic structure, and mechanical property of the solder. The results show that a small amount of Ag3Sn nanoparticles were able to reduce the wetting time, increase the maximum wetting force, and expand the spreading area. The melting performance was also improved. Ag3Sn nanoparticles were also found to significantly refine the solder structure in the metallographical. The best comprehensive performance was achieved with the addition of 0.5% Ag3Sn nanoparticles. These Ag3Sn nanoparticles effectively improved the morphology of the IMC at the interface and effectively reduced the thickness of the IMC layer. The addition of nano Ag3Sn increased the diffusion activation energy and stabilized the interface. Moreover, the growth of the IMC layer was inhibited by 0.5% Ag3Sn, as indicated by aging results. The addition of Ag3Sn nanoparticles increases the tensile strength and Vickers hardness of the solder joint. When the amount of Ag3Sn nanoparticles was 0.5 wt%, the tensile strength reached the maximum of 17.45 MPa. The microhardness value of the solder is greatly increased, which reaches 311 HV. Finite element simulation showed that the service life of the solder was prolonged by adding the appropriate amount of Ag3Sn nanoparticles. The paper demonstrates a method of "nano" solder paste preparation. Results show that the addition of Ag3Sn nanoparticles plays an important role in the interfacial reaction and mechanical properties between the SAC solder and Cu substrate.