A Module-Level Spring-Interconnected Stack Power Module

This paper presents the design, fabrication, and characterization of a module-level spring-interconnected stack power module for power semiconductor devices. The benefit of multilayer design capability offered by a low-temperature cofired ceramic (LTCC) substrate is used for this module-level power module structure. A half-bridge configuration is demonstrated using two standalone wire-bondless power modules with parallel power semiconductor devices stacked on top of each other. An interconnection scheme consisting of conductive copper clamps and a spring-loaded LTCC interposer is adopted to form a module-level 3-D package structure. The low loop and stray parasitic inductances for the 3-D stack are achieved using an antiparallel current path configuration along with the wire-bondless approach and a low-profile spring interposer. For demonstration, silicon insulated-gate bipolar transistors and silicon carbide (SiC) Schottky barrier diodes are used to fabricate the hybrid 3-D stack. Static and transient electrical characteristics of the 3-D stack power module are evaluated through simulation and experimental measurements and compared with a wire-bonded half-bridge power module to investigate the performance improvement in switching characteristics of the 3-D module. High-voltage isolation test, leakage current test, and thermal cycling are performed to validate the spring-interconnected module-level 3-D stack structure.