Thermal and thermo-mechanical design of an integrated substrate and heat sink for planar power module

We report on the development of an integrated substrate and heat sink for a planar power module with the aim of improving the thermal and reliability performance whilst reducing the manufacturing cost. Finite element modelling and simulations have been used to verify the selection of the materials and optimise the structure of the integrated substrate and heat sink. The simulation results reveal that replacing the Al alloy and Al-SiC composite with ceramic in the heat sink can significantly reduce the creep strain accumulation, and thus improve the reliability of the solder joint mounting the DBC substrate on the heat sink. Impinging jet coolers (heat sinks) can achieve better thermal performance than U-shape channel coolers but require increased pumping power. Plastic coolers are only effective with high flow rate and high pumping power, while a strong ceramic and Al alloy impinging jet cooler has excellent thermal performance, e.g. achieving coefficeint of heat exchange 7500 to 31,100 W.m-2.°C(Exp -1) under flow rate of 7 to 26 mL/s and pumping power of 0.06 to 3.4 W. The good agreement between the simulations and thermal test results validates that the simulations are accurate enough to investigate the effects of the materials, structure and flow rates on the thermal performance.