<p>In this study, as an alternative to the low-melting-point eutectic tin-bismuth (Sn-Bi) solder alloy for electronic applications, a Sn-45wt.%-Bi-3wt.% Sb (tin-bismuth-antimony) solder alloy was produced by reducing the bismuth content, which has a brittle structure. Zn (zinc) was added to Sn-45Bi-3Sb-based alloys at concentrations of 1&#xa0;wt.% and 2 wt.%. Subsequently, the temperature-dependent variation in thermal conductivity was carefully examined using the linear heat flow method. The temperature-dependent electrical conductivity was assessed using the four-point probe method, while microhardness properties were analysed with the Vickers microhardness testing technique. The thermal and electrical conductivities of Sn-45Bi-3Sb-[<i>x</i>]Zn (<i>x</i> = 0, 1, 2) alloys at 298.15&#xa0;K were measured as 36.09, 37.05, and 37.32 W/mK, and 0.03495, 0.03587, and 0.03692 × 10⁸/Ωm, respectively. It was observed that adding Zn enhanced the thermal conductivity, electrical conductivity, and hardness. These findings indicate that Zn-doped Sn-45Bi-3Sb solder alloys have advantageous thermal, electrical, and mechanical properties, making them suitable candidates for electronic packaging and lead-free soldering uses, where high reliability and thermal efficiency are essential.</p> Graphic Abstract <p></p>