Interfacial morphology and reliability of GaN nanocomposite Sn-Ag-Cu lead-free braze joints

Abstract

GaN nanoparticles, in varying mass fractions (0 wt%, 0.20 wt%, 0.40 wt%, 0.60 wt%, and 0.80 wt%), were integrated into a Sn-3.0Ag-0.5Cu lead-free solder using mechanical mixing followed by reflow soldering. The solders underwent isothermal aging at 170°C for different durations to assess the influence of GaN content on the melting characteristics, wettability, and growth behavior of the intermetallic compound (IMC) in the Sn-3.0Ag-0.5Cu solder. Findings indicate that GaN incorporation does not markedly alter the melting point of SAC305. However, a moderate GaN addition enhances the wettability of Sn-3.0Ag-0.5Cu, with the optimal effect observed at 0.40 wt% GaN, where the wettability is improved by 61.5% relative to the base solder. Furthermore, GaN addition serves to curtail the IMC layer’s growth, which, while it thickens with prolonged isothermal aging, does so at a rate governed by diffusion. At 0.40 wt% GaN, the diffusion coefficient is determined to be 1.453×10-15 m2/s, underscoring the superior performance of the novel SAC305-0.4GaN composite solder.