The measurements of electrical and thermal conductivity variations with temperature and phonon component of the thermal conductivity in Sn–Cd–Sb, Sn–In–Cu, Sn–Ag–Bi and Sn–Bi–Zn alloys

Abstract

The electrical and thermal conductivity variations with temperature for lead-free ternary solders, namely Sn-41.39 at.% Cd-6.69 at.% Sb, Sn-49 at.% In-1 at.% Cu, Sn-50 at.% Ag-10 at.% Bi and Sn-32 at.% Bi-3 at.% Zn alloys, were measured by the d.c. four-point probe method and radial heat flow apparatus, respectively. The contributions of electrons and phonons to the thermal conductivity were separately determined by using the measured values of the thermal and electrical conductivities obtained by the Wiedemann–Franz law in the lead-free ternary solders. The percentages of the phonon component of thermal conductivity were found to be in the range of 46–55%, 46–50%, 38–47% and 69–73% for Sn-41.39 at.% Cd-6.69 at.% Sb, Sn-49 at.% In-1 at.% Cu, Sn-50 at.% Ag-10 at.% Bi and Sn-32 at.% Bi-3 at.% Zn alloys at the ranges of 318–443 K temperature, respectively. The temperature coefficients (α) of electrical conductivity for the lead-free ternary solders were found to be 2.47 × 10−3, 4.97 × 10−3, 1.14 × 10−3 and 1.00 × 10−3 K−1, respectively. The thermal conductivities of the solid phases at their melting temperature and the thermal temperature coefficients for the lead-free ternary solders were also found to be 47.72 ± 2.38, 68.57 ± 3.42, 73.52 ± 3.67, 37.53 ± 1.87 W/Km and 1.47 × 10−3, 1.48 × 10−3, 1.85 × 10−3 and 2.21 × 10−3 K−1, respectively.