Design consideration of high temperature SiC power modules

Abstract

SiC power semiconductors can safely operate at a junction temperature of 500degC. Such a high operating temperature range can substantially relax or completely eliminate the need for bulky and costly cooling components commonly used in silicon-based power electronic systems. However, a major limitation to fully realizing the potential of SiC and other wide band-gap semiconductor materials is the lack of qualified high-temperature packaging systems, particularly those with high-current and high-voltage capabilities required for power conversion applications. This paper proposes a new hybrid power module architecture that allows wide bandgap semiconductor power devices to operate at a junction temperature of 300degC. The concept is based on the use of double metal or DCB leadframes, direct leadframe-to-chip bonding, and high temperature encapsulation materials. The leadframes, serving as both the external leads and the internal interconnect to the semiconductor chips, need to provide excellent high temperature stability, adequate electrical and thermal conductivity, and a coefficient of thermal expansion (CTE) closely matching that of SiC. The SiC chips are sandwiched between and bonded to the top and bottom leadframes using a brazing or adhesion process. Extensive electrical, thermal, and mechanical modeling has been performed on this new concept. Several prototypes are fabricated, and a finite element model is evaluated. Packaging architecture and materials considerations are discussed.