Faults Detection in the Heatsinks Mounted on Power Electronic Transistors

Nowadays, power electronics is widely used in many applications, e.g., in industrial field, transport field and household appliances used daily. Considering the high temperature reached in power circuits, it is necessary to introduce some heat dissipation systems able to transfer heat to the surrounding environment. The correct mounting of the heatsink or its physical deterioration over time can affect the operation of the system. The overheating may lead to an ageing acceleration of the power devices or to their permanent damage. This greatly influences the reliability and safety of power systems used in safety-critical applications, e.g., for automotive, rail or industrial environments. Hence, it is necessary to introduce some test strategies to identify those heatsinks that do not operate correctly, e.g., because they are not correctly assembled during the production of the Printed Circuit Board (PCB). This paper proposes a methodology to test the assembly of heatsinks on power devices. The proposed approach relies on an in-circuit test method at the end-production on the final PCB. The test is carried out without resorting to thermal measurements. Generally, the thermal measurements cannot be performed by the modern Automatic Test Equipment (ATE). The proposed test methodology was evaluated experimentally on a power MOSFET in TO220 package; the MOSFET considered is used in a half bridge.