Effect of Ni nanoparticles reinforcement on wettability, microstructure and mechanical properties of SAC387 lead-free solder alloy

Abstract

The study investigates the influence of nickel (Ni) nanoparticles on the wettability, microstructure, and mechanical properties of Sn-3.8Ag-0.7Cu (SAC387) lead-free solder alloy. Nanocomposite solders containing 0.3 wt% and 0.5 wt% Ni were prepared and reflowed at temperatures of 230 °C, 250 °C, and 270 °C to evaluate their performance on copper substrates with a surface roughness (Ra) of 0.01 ± 0.002 ?m. Wettability improved with increasing reflow temperature; however, the addition of Ni nanoparticles had minimal direct impact on spreading behavior. Microstructural analysis revealed enhanced formation of interfacial intermetallic compounds (IMCs), particularly (Cu,Ni)<inf>6</inf>Sn<inf>5</inf> which contributed to improved joint stability. The optimal mechanical performance was observed at 250 °C with 0.3 wt% Ni addition, yielding a 51.14 % increase in shear strength compared to the unreinforced solder. Microhardness also improved significantly by 43.7 % at the IMC layer and 18.3 % in the solder bulk. Weibull analysis further confirmed higher joint performance with Ni nanoparticle incorporation. These findings highlight the potential of addition of Ni nanoparticles in improving the performance of SAC387 solder joints in electronic packaging. © 2025 Elsevier Ltd