Evaluation of Leadframe Power Modules for Automotive Drive Applications

Abstract:
The thermal performance of a novel copper leadframe IGBT half-bridge power module with an epoxy based insulation sheet and a second leadframe module with an insulated graphite sheet is compared. Thermal simulation as well as computational fluid dynamic (CFD) simulation with COMSOL Multiphysics are performed in order to determine the thermal resistance of both leadframe module variations at different coolant temperatures and fluid flow rates. The simulations show the thermal performance of the leadframe module with epoxy insulation to be better by approximately 40 % compared with a DCB-based direct liquid cooling power module. The leadframe power module with insulated graphite sheet is built-up and characterized. The measured thermal resistance of the static characterization differs from the simulated results by 6 % to 11.8 % due to the deviating thermal properties of the materials and the measurement errors. The electromagnetic simulation yields a parasitic stray inductance of 12.1 nH which is roughly 40 % less than the stray inductance of a comparable standard DCB-based power module. The double pulse test shows a low voltage overshoot of less than 25 V during the turn-off phase of the IGBT for a collector current of IC=58 A.