Identifying Unequal Temperature Distributions in SiC MOSFET Power Modules

In today’s power modules, single SiC MOSFET dies are connected in parallel to increase the current carrying capability of power modules. However, geometrical asymmetries of the module and tolerances in the manufacturing process of the semiconductor devices, lead to an unequal loss distribution among the individual dies. This in turn leads to different thermal stress of the individual dies and thus to different aging which requires a de-rating of the MOSFETs. In this work, a SiC power module with a nominal voltage of 1200 V and a nominal current of 300 A is investigated. An unequal temperature distribution among the parallel dies is identified and the root causes are discussed. Therefore, this research provides valuable insights in the design of more efficient, more reliable and more durable power modules.