Effect of nano Al₂O₃ particles doping on electromigration and mechanical properties of Sn-58Bi solder joints

Abstract In the present study, the effect of Al₂O₃ nanoparticles on performances of Sn-58Bi solder were investigated in aspects of electro-migratio, shear strength and microhardness. The experimental results show that the Al₂O₃ nanoparticles significantly improved microstructure and mechanical performances of solder joints. With the addition of 0.5 wt% Al₂O₃, the intermetallic compounds (IMC) reduced from 2.5 μm to 1.27 μm after 288 aging hours at 85 °C. Furthermore, after electromigration test under a current density of 5 × 10³ A/cm² at 85 °C, Bi-rich layers formed at the anode side of both Al₂O₃ doped and plain solder. Moreover, the addition of Al₂O₃ nanoparticles reduced the mean thickness of Bi-rich layer. In addition, the growth rate of the IMC layer of Al₂O₃ doped solder decreased by 8% compared with the plain solder. Besides, the Al₂O₃ doped solder exhibited better performance than plain solder in microhardness after different aging times. While, the addition of Al₂O₃ significantly impeded the degradation of the shear strength of solder joint after aging for 48 and 288 h. Furthermore, it was worth noting that the fracture surface of doped solder showed a typical rough and ductile structure. However, plain solder exhibited a relatively smooth and fragile surface.