Power MOSFET active power cycling for medical system reliability assessment

High voltage generator is one of the critical subsystems of a medical system. So, a methodology assessing its reliability from component to system is proposed. In this context, N-channel power MOSFETs that are used in high frequency inverter for supplying high voltage transformer is tested. These MOSFETs are subjected to power cycling test in order to reveal thermo-mechanical failure modes and at the same time evaluate their lifetime using DoE. The test is done by using an external current supply to induce self-heating through the component. Heating and cooling phase are controlled by a logic controller. The ON state resistance (R-DSON) is monitored during the test as the failure indicator and different imaging methods are used for failure analysis and observed failures mechanism are discussed. (C) 2013 Elsevier Ltd. All rights reserved.