Electrical and thermal characterization of lead-free Sn-Zn-Cu solder alloys

Sn-Zn-Cu alloys have emerged as promising candidates to replace conventional lead-containing solder systems due to their environmentally favorable characteristics. In this study, four different phases within the Sn-Zn-Cu alloy system were investigated in terms of their thermal and electrical properties. Temperature-dependent thermal conductivity was measured using the linear heat-flow method, and the corresponding conductivity coefficients were derived from the collected data. Differential Scanning Calorimetry (DSC) was employed to determine melting temperatures, enthalpies of fusion, and specific heat differences between the liquid and solid phases. Electrical conductivity values were obtained using the four-point probe technique. Compared to commonly used Pb-free solder systems reported in the literature, the investigated Sn–Zn–Cu alloys exhibit a favorable combination of lower melting temperatures, stable thermal behavior, and controlled electrical conductivity, which are critical for ensuring reliable heat dissipation and electrical performance in advanced electronic and energy-related soldering applications. These characteristics highlight the potential of Sn–Zn–Cu alloys as cost-effective and high-performance alternatives to conventional Pb-free solders.