Effect of doping Ni nanoparticles on microstructure evolution and shear behavior of Sn–3.0Ag–0.5Cu(SAC305)/Cu–2.0Be solder joints during reflowing

The Cu–2.0Be alloy is widely used as the substrate in aircraft electronic device, which has a potential trend to replace the pure Cu substrate. However, few studies have investigated the influence of the doped Ni nanoparticles on interfacial reaction between Cu–2.0Be substrate and the SAC305 solder during reflowing. In this study, the effect of Ni nanoparticles on wettability, microstructure evolution and mechanical behavior of SAC305/Cu–2.0Be solder joint was investigated. The results showed that a certain amount of Ni nanoparticles could increase the spreading area and mechanical property of the SAC305/Cu–2.0Be solder joint. The interfacial intermetallic compound (IMC) layer thickness could be reduced significantly by adding Ni nanoparticles. Moreover, the interfacial IMC layer thickness of SAC305/Cu–2.0Be solder joint was obviously thicker than that of SAC305-0.1Ni/Cu–2.0Be solder joint after different soldering times, which meant that a certain amount of Ni nanoparticles could hinder the IMC growth during soldering process. The growth kinetic of interfacial IMC layer after adding 0.1 wt% Ni nanoparticles showed that the growth coefficient of interfacial IMC layer changed from 1.21 µm/s^0.28 to 1.82 µm/s^0.32. In addition, the value of the shear strength of SAC305-0.1Ni/Cu–2.0Be solder joint was larger than that of SAC305/Cu–2.0Be solder joint with a typical mixture ductile and brittle fracture mode, which contributed to increasing the shear strength. Therefore, SAC305-0.1Ni solder alloy is a promising potential solder alloy in aircraft electronic device.