Material Characterization of Advanced Cement-Based Encapsulation Systems for Efficient Power Electronics with Increased Power Density
The paper introduces novel phosphate cement- and calcium aluminate cement-based material systems with enhanced thermal, mechanical and thermomechanical properties for the encapsulation of power electronic devices and modules. These materials are aiming at improving the high-temperature operation potential of power electronic systems and thus, to promote a successful application of wide bandgap power devices in power electronics. The main focus of the study consists in a thorough material characterization of the novel cement-based encapsulants including high resolution microstructural analysis combined with a modelling approach to support material design optimization. A second task consists in the analysis of interactions of the encapsulants with the electronic material interfaces, e.g. the top-side metallization of power semiconductors, substrate metallizations and bonding wires. Furthermore, power cycling tests coupled with a comprehensive failure analysis have been carried out comparing IGBT power modules with standard silicone gel encapsulation and cement-based encapsulation. The results highlight the potential of the novel cement-based encapsulants on reliability improvements at high-temperature operation.