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 β-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.