Direct-cooled power module with a thick Cu heat spreader featuring a stress-suppressed structure for EV/HEV inverters

This paper presents direct-cooled power module technologies that satisfy the requirements for lower thermal resistance and stress relaxation, especially for small die size semiconductors (e.g. Silicon Carbide (SiC)). The power module structure features a thick Copper (Cu) heat spreader located under the semiconductor chip for lower thermal resistance and a thin closed Aluminum (Al) water jacket for stress relaxation. And a prototype power module was fabricated using a thick Cu heat spreader that reduces thermal resistance by 34% compared with conventional direct-cooled power modules. It was also shown that using a thin closed Al water jacket (multi-port tube) achieves the same level of stress as conventional power modules, thereby mitigating the stress-strain and solder cracking induced by the metal junctions with a thick Cu structure.