Electro-Thermal Scaling Limits in Ultra-High-Density SiC Power Modules

Abstract

Aggressive power-density targets for next-generation SiC traction inverters are driving highly integrated bare-die power modules in which losses are concentrated over extremely small footprints. Conventional copper heat spreaders, commonly employed to mitigate localized hotspots, introduce additional electrical parasitics and exhibit diminishing thermal benefit as geometric scaling continues. This paper systematically analyzes the coupled electrical and thermal trade-offs associated with heat spreader integration in ultra-high-power-density SiC modules using a representative bare-die half-bridge structure. The analysis identifies electrically and geometrically imposed limits on spreading-based hotspot mitigation, beyond which further performance improvement through conduction enhancement alone becomes ineffective. The derived scaling boundary suggests a transition beyond practical single-phase cooling limits, where higher-HTC approaches such as two-phase cooling may become necessary.