Al-SiC IMPROVES RELIABILITY OF IGBT POWER MODULES

SUMMARY: Aluminium alloys reinforced by high volume fractions of SiC particulates are candidate materials for base plates of high power electronic modules. Such Al-SiC metal matrix composites exhibit low thermal expansion and high thermal conductivity similar to Cu-Mo alloys. The thermal expansion has to be matched to the ceramic substrate within the electronic package and has to be homogeneous over the plate to avoid degradation by thermally induced stresses. Three differently produced AlSiC base plates are investigated with respect to quality criteria like uniformity in micro-structure, as well as thermal and mechanical properties. The SiC volume fractions vary between 60 and 73 % revealing different particle distributions. The linear coefficient of thermal expansion is decreasing with increasing SiC content from 7,9 to 6,5 ppm/K between room temperature and 150°C. The thermal conductivity, the Young's modulus and the elastic limit increase with increasing SiC volume fraction. The bending strength is related to the ductility