High Thermal-Transient Packaging for a SiC-Based Solid State Circuit Breaker

Abstract

Solid-State Circuit Breakers (SSCBs), or Contactors, are critical components in next generation electric aircraft, and must be small in size, fast in response, and have high reliability. Silicon Carbide (SiC) semiconductor switches provide a series of improvements over traditional silicon-based breakers in both electrical and thermal performances. The reported SSCB uses SiC MOSFETs mounted on cast-aluminum traces, cast onto an aluminum nitride (AlN) ceramic co-captured in an aluminum composite baseplate. The system is similar to an AlSiC and Direct-Bonded-Aluminum (DBA) approach. This presentation details the transient thermal characterizations of an SSCB having the highest density in development. Previous work focused on a 30A SSCB that was constructed and tested to show a 300A, 500ns circuit breaking capability. The high density comes from allowing the SiC junctions to pulse to ∼350°C (in 5ms) from a 105°C ambient baseplate. The 30A/300A module was reported in IMAPS HiTEC’10 “Development of a SiC SSPC Module with Advanced High Temperature Packaging,” This paper builds on that paper adding the mechanical results and all new data on the larger, high energy density module with larger die. The objective of the presentation is to introduce (or update) the use of cast composite metal-ceramic structures for high thermal transient applications and document the mechanical stress/strain performance through simulations. The module is in development for military applications and has not been field-tested. This is also developed for Smart-Grid applications in local distribution systems.