Solder Preform Technology for Improved Thermomechanical Performance in Molded Power Module Package-Attach

Abstract:
For power modules, the attach to the heat sink plays a major role in overall performance. Soldering is a cost effective and reliable solution, and SnSb5 is most commonly used in this application. Nevertheless, state-of-the-art SnSb5 alloys can cause mold delamination of the module due to the high peak temperature required. Therefore, a low-temperature Pb-free alloy alternative offering similar reliability is discussed. This SAC-In alloy technology reduces peak temperatures, removing the risk of delamination with molded package power modules. This Bi-free alloy provides favorable mechanical properties to achieve reliability performance that is comparable to SnSb5 for thermal shock testing -40deg/+125deg C.