SiC die-attachment with minor elements added pure Zn under formic acid reflow

Pure Zn is one of the best candidates, as it has a high melting, good electrical/thermal conductivity, and excellent thermal shock resistance. To improve the properties of pure Zn, the effect of the addition of 0.1 mass% Cr and Ti was examined the formic acid reflow soldering. The minor elements are expected to form a surface protective oxide layer on Zn and the formic acid reflow soldering can replace the hydrogen reduction treatment. The addition of 0.1 mass% Cr or with 0.1 mass% Ti to pure Zn improves ductility and oxidation resistance. Among the solder alloys, the addition of Cr has the most effective improvement of ductility and oxidation resistance. The Pure Zn and Zn-X solders exhibit the excellent heat-cycle resistance for the DBC die-attach structure between −50 °C and 300 °C.