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

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 mu m to 1.27 mu m after 288 aging hours at 85 degrees C. Furthermore, after electromigration test under a current density of 5 x 10(3) A/cm(2) at 85 degrees 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. (C) 2015 Elsevier Ltd. All rights reserved.