Thermal contact resistance between ceramic and metallic surfaces with applications in power electronics

In power electronic systems, aluminum oxide (alumina) is frequently used to electrically isolate high voltage devices mounted onto touch safe heat sinks for cooling. The thermal contact resistance (TCR) developed between the aluminum oxide and the metallic surfaces may significantly increase the thermal resistance between the heat generating device and the heat sink. In this thesis, the thermal contact resistance between ceramics and metals is explored analytically and experimentally. The TCR between polished ceramics and bead-blasted metals was first measured under uniform contact pressures (0.25 – 1.5 MPa) in both atmospheric and vacuum conditions. These results are compared with existing metallic surface TCR models to validate their use with metallic-ceramic surfaces. TCR measurements of as-fired, lapped and polished aluminum oxide in contact with machined, cast and anodized extruded aluminum surfaces with thermal interface materials (TIMs) are also presented.