Innovative packaging solution for power and thermal management of wide-bandgap semiconductor devices in space applications

Devices based on wide-bandgap semiconductors such as SiC or GaN allow high power densities and elevated working temperatures. Here we present an innovative package for high-power electronics, within the framework of an ESA-contracted project. The paper shows the housing concept, design study, materials selection, manufacturing method and first test results. Materials are selected for their high thermal conductivity (TC) and low coefficient of thermal expansion (CTE). Several materials were selected: AlN was selected as substrate material, and novel metal-matrix composites (MMCs) based on Cu–diamond and Cu–vapour grown carbon nanofibres (VGCNFs) were evaluated as heat-sink materials. Subsequently, a complete bonding study between ceramic materials and MMCs was performed. In order to obtain fully dense materials AlN was manufactured by pressureless sintering, while the MMC parts were manufactured by hot-pressing. The MMC powders were obtained by an electroless plating process. Preliminary characterisation of the housing and its parts show encouraging results as a solution for high-power devices working at temperatures up to 300 °C. TC near 500 W/mK and CTEs of around 10 ppm/K have been obtained. These are comparable to the state-of-the-art materials. Out-gassing, thermal cycling and hermeticity tests of the packages were performed. The presented new packaging solutions show great promise for space applications such as high-frequency power amplifiers for satellite communications and for radar transmitters, and have started to generate an interest from commercial space-system manufacturers.