Low- and Mid-Temperature Pb-Free Solder Preform Technology in Substrate Attach Application for Improved Thermomechanical Performance

New and emerging technologies such as e-mobility have a demand for higher power density, increased heat dissipation and higher reliability. The switch from Si die to SiC die to meet this requirement have placed importance on the selection of interconnect material within the power module package. In this paper, low to mid temperature Pb-free soldering solutions high-reliability alloys for high power density power electronics substrate attach to baseplate is discussed. Low temperature SAC-In alloys solution in solder preform configuration that can be used with reflow temperatures around 215-230 degree C in substrate attach soldering applications was presented to prevents re-melting of the interconnect soldering materials at die attach / clip attach during the step soldering process assembly. A mid temperature, high reliability Sn-based alloy solutions with reflow temperature around 260-270 degree C will also be presented as drop-in replacement for standard Pb- free SAC305 alloy for robust lifecycle performance comparable or better as shown by thermal shock testing data of -40°C to +125°C.