Preparation, microstructure and properties of Sn-Ag-Cu solder reinforced with Al2O3 nanoparticles

Sn3.0Ag0.5Cu(SAC)-XAl₂O₃(X = 0.2, 0.4, 0.6, 0.8 wt.%) composite solders reinforced with Al₂O₃ nanoparticles were prepared through the powder metallurgy route (ball milling, compacting and sintering). After ball milling, the morphology of composite powder was studied by scanning electron microscopy (SEM). In addition, the prepared composite solders were characterized in terms of their microstructure, wettability and microhardness. After mixing by ball milling, the Al₂O₃ nanoparticles were found embedded into the surface of Sn-Ag-Cu solder powder. Moreover, microstructure observation proved Al₂O₃ nanoparticles were successfully incorporated into the SAC solder. Finer microstructure with smaller β-Sn grains was achieved with the addition of Al₂O₃ nanoparticles. On the other hand, wettability was improved by moderate addition of Al₂O₃ nanoparticles. 12.6% decrease in contact angle was achieved with 0.4 wt.% Al₂O₃ nanoparticles addition. Microhardness of composite solders increased with the increasing content of Al₂O₃ nanoparticles. This improved mechanical property can be attributed to the refined microstructure and the dispersed Al₂O₃ nanoparticles.