Study On Microstructure, Properties And Electromigration Behavior Of Al₂O₃anoparticles Reinforced Sn3.0Ag0.5Cu Solder

With the sustained trend towards more portable, miniaturization and high performance of electronic device, electronic packaging develop toward high-density packaging. The most widely used SnAgCu solder alloys were challenged due to reliability issues in high density packaging. Introducing nanoparticles into solder matrix is an effective way to improve performance and electromigration resistance of solder.In this study, Sn3.0Ag0.5Cu(SAC) and Al2O3 nanoparticles were respectively chosen to be solder matrix and reinforcement to prepare SAC-XAl2O3(X = 0.2, 0.4, 0.6, 0.8) composite solders through the powder metallurgy route. The effect of ball milling during composite solders preparation, microstructures of composite solders and intermetallic compound(IMC) evolution of solder joint during aging were investigated. Al2O3 nanoparticles were found embedded into the surface of SAC solder powder after ball milling, which illustrating that Al2O3 nanoparticles and SAC solder powder formed a close combination. On the other hand, the addition of Al2O3 nanoparticles refined the microstructure of composite solders and retarded the growth of IMC during aging. And with the content of Al2O3 nanoparticles increases, this effect of microstructure refinement and IMC growth retardation was stronger.Thermal analysis, wettability, microhardness and shear strength of composite solders were also observed. With addition of Al2O3 nanoparticles, the change on melting temperature was less than 1 ℃ while undercooling was considerably reduced. With Al2O3 nanoparticles content increasing, wettability of composite solders increased first and then decreased; While microhardness and shear strength increased.To analyze effect of Al2O3 nanoparticles on electromigration behavior, in-situ observation and non in-situ observation of microstructure evolution of Cu/SAC/Cu and Cu/SAC-0.8Al2O3/Cu solder joint during several periods(0, 40 h,110 h, 190 h) when1.35×104 A/cm2 current applied were conducted. The result shows that 0.8wt.% Al2O3 nanoparticles addition retarded the electromigration of solder joint.