Effect of nano-Al₂O₃ particles on the microstructure and mechanical performance of melt-spun process Sn–3.5Ag composite solder

The addition of Al₂O₃ nanoparticles with 0.01, 0.03, 0.05, 0.07, and 0.1 wt% to eutectic solder Sn–3.5Ag was studied so as to be aware of the influence of Al₂O₃ addition as the particulate reinforcement to the microstructure, microhardness, and mechanical properties. By adding 0.1 wt% Al₂O₃ nanoparticles, the intermetallic compounds (IMCs; Ag₃Sn) decreased from 95.55 to 45.22 nm. Additionally, the IMCs growth rates diminished by 30% to the plain solder. As a whole, the Al₂O₃ nanoparticles-embedded solder displayed better properties than plain solder in micro-creep and microhardness. Al₂O₃ nanoparticles fixed in the lead-free solder matrix impede the movement of dislocations by sticking and also stuck grain boundaries so as to enhance the mechanical properties of the lead-free solder matrix. The Sn–3.5Ag/Al₂O₃ lead-free solder showed improved properties compared with the traditional solder Sn₆₃Pb₃₇, which could substitute some Pb holding solder alloys in micro-electronic components and interconnections. The Scanning Electron Microscope (SEM) was carried out to study the morphology of the fabricated solders. The SEM revealed that the microstructure of solders was improved by doping Al₂O₃. According to X-ray diffraction analysis, the β-Sn (tetragonal phase) was formed as the main phase for all solders in addition to the peaks related to some intermetallic compound phase Ag₃Sn. The results indicated that higher mechanical properties were obtained for composite solder Sn–3.5Ag/Al₂O₃ compared with plain solder. The melt-spun process is more resistant to indentation creep.