Warpage Evaluation of Double-Side Cooled Power Modules with Ceramic Stiffeners

Abstract

Double-side cooled (DSC) power modules enable improvements in thermal performance and power density for automotive traction inverters; however, the removal of the baseplate and the introduction of dual cooling interfaces make these structures highly sensitive to warpage and interface non-uniformity. This work experimentally investigates the relationship be tween module rigidity, warpage behavior, thermal performance, and reliability in baseplate less DSC SiC power modules. Four module configurations with varying rigidity were fab ricated using combinations of soft encapsulants, rigid encapsulants, and ceramic stiffeners. Warpage evolution throughout fabrication was characterized using 3D optical profilometry, while transient thermal measurements were used to evaluate thermal resistance and inter face performance. Results showed that increasing module rigidity reduced post-fabrication warpage magnitude, improved warpage consistency, and promoted more uniform contact at the module-to-cold-plate interface, resulting in lower thermal resistance. Reliability evalu ation further showed that stiffener configurations maintained stable electrical and thermal performance after thermal cycling, while soft encapsulant modules exhibited significant ther mal degradation and rigid encapsulant modules experienced wirebond failures. The results demonstrate that module rigidity can be used as a controllable design parameter to influence warpage behavior, thermal interface performance, and thermo-mechanical reliability in high power density DSC power modules.