Effects of nano-SiO2 particles addition on the microstructure, wettability, joint shear force and the interfacial IMC growth of Sn3.0Ag0.5Cu solder

In the present study, the nano-composite solder with SiO2 nanoparticles into eutectic Sn3.0Ag0.5Cu solder were prepared. The addition concentration of SiO2 nanoparticles ranges from 0 to 1 wt%. The effects of SiO2 on the microstructure, the wettability, joint shear force of the composite solder under different working temperature and the growth of interfacial intermetallics compounds (IMCs) at solder/Cu substrate during thermal cycling were investigated respectively. The results show that appropriate addition of nano-SiO2 particles can refine the beta-Sn matrixes and enhance the wettability of nano-SiO2 composite solder. Additionally, slight addition of nano-SiO2 particles can inhibit the formation and the growth of the interfacial IMCs layer between the solder and Cu substrate during reflow and thermal cycling. Moreover, nano-SiO2 can also increase the shear force of composite solder joint. However, excessive addition of SiO2 nanoparticles in the Sn3.0Ag0.5Cu solders degrade the wettability, joint shear force and the inhibition effect on the interfacial IMCs. There is an optimum addition concentration of SiO2 nanoparticles in Sn3.0Ag0.5Cu solder alloys, which is 0.05 wt%, and Sn3.0Ag0.5Cu-0.05 wt% SiO2 solders possess the biggest wetting force, highest shear force and the best inhibition effect on the interfacial IMCs formation and growth.