Accelerated Voltage Endurance Test and Insulation Lifetime Estimation of Silicone-Gel Encapsulated Direct-Bond-Copper Substrates for Medium-Voltage Power Module Packaging

The advent of medium-voltage silicon carbide devices presents the potential to significantly improve the efficiency and simplicity of power electronics for grid-tied applications. However, the frequent occurrence of insulation failure in me-dium-voltage power modules undermines their reliability and hampers their widespread adoption. There is a lack of research on the insulation characteristics of the module under long-term high voltage stresses. In this work, an accelerated voltage endurance test was conducted on alumina direct-bond copper substrates encapsulated in a silicone gel to establish an insulation lifetime model for medium-voltage power modules. Based on the test data and the model, to achieve an insulation life exceeding one year for the substrate under a constant voltage stress, the maximum operating voltage is recommended to be lower than 49% of its partial discharge inception voltage.