2014 Volume 55 Issue 9 Pages 1513-1516
Each electrical resistivity of the ternary solder alloy of tin–copper–sulfur was compared to that of the binary solder alloy of tin–copper. A mixture of various tin, copper, and sulfur powder compositions was prepared by adding different amounts of sulfur into a eutectic composition of tin and copper. After each specimen axially compressed with 10 MPa was sintered at 250°C, tin sulfide was induced in the solder alloy because sulfur reacted with tin. Simultaneously, the oxide layers of the solder alloy were removed through a complicated combustion reaction between tin sulfide and tin oxide. As a result, the electrical resistivity of the ternary solder alloy (Sn-0.70Cu-0.32S) having 0.32 mass% of sulfur was reduced to at most 10.56 µΩ·cm, compared to 12.47 µΩ·cm of the binary solder alloy (Sn-0.70Cu) without sulfur.