<p>Coarse Ag₃Sn IMCs are a major issue impairing the reliability of Sn–Ag–Cu alloys in electronic packaging. This work examines the influence of Zn additions on the microstructural evolution and properties of Sn–2Ag–0.7Cu (SAC207) alloy. Results indicate that microalloying of 1.5 wt.% Zn significantly refines the β-Sn phase, inhibits the growth of Ag₃Sn and Cu₆Sn₅ phases, enhances the eutectic fraction, and promotes the formation of fine Ag–Zn–Sn-rich particles. Consequently, notable improvements are achieved in electrical conductivity, undercooling characteristics, pasty range, hardness, yield and ultimate tensile strength, and Young’s modulus, while elongation is slightly reduced and the melting temperature remains largely unaffected. In contrast, at a higher Zn concentration of 3.0 wt.%, the fine Ag–Zn–Sn precipitates are replaced by coarse γ-(Cu,Ag)₅Zn₈ phases with flower-like and dendritic morphologies, resulting in reduced microstructural uniformity and deterioration of mechanical and electrical performance compared with the 1.5 wt.% Zn alloy. Zn-containing alloys exhibit a&#xa0;reduction in aging-induced normalized resistivity change (Δρ/ρ₀) up to 66%&#xa0;compared to the Zn-free SAC207 alloy, while the absolute room-temperature resistivity shows a moderate reduction of 6–9%. The formation mechanism of coarse Ag₃Sn is primarily ascribed to the low solubility of Ag in both the β-Sn and Cu₆Sn₅ phases, leading to the precipitation of coarse Ag₃Sn rather than fine eutectic Ag₃Sn.</p>