SiC Power Device Die Attach for Extreme Environments

Silicon carbide power diodes and transistors are enabling technology for power electronics capable of operating in extreme environments. In this paper, a AgBiX solder paste has been studied for SiC power device die attach to power substrates for 200 °C use in vehicle and downhole well logging applications. The solder paste has a controlled amount of Sn, which limits the amount of Sn intermetallic formation. This produces a stable solder joint as a function of time at high temperature. The die shear strength remained at ~38 MPa through 2000 h of storage at 200 °C. After 1000 thermal cycles from -55°C to 195 °C, the percent die attach area reduction due to solder cracking was