Low thermal resistance thermal pad for power converter modules

Thermal Interface Material (TIM) is used between power converter module base plate and a heat sink to minimize thermal contact resistance. In harsh operating conditions, power modules experience large temperature swings causing TIM degradation, gradual increase in device temperature over the life of the module, and ultimately a catastrophic failure of the module. Therefore a reliable TIM, with slow degradation, is an important component of a power module assembly. This article reports evaluation of five TIMs under power cycling conditions that lead to module base plate temperature swings between 15 and 110°C. Each TIM was tested with three IGBT modules. Two of the TIMs tested were Phase Change Material thermal pads, two were a high performance thermal greases, and one was a new thermal pad, marked here as Teledyne-Rockwell Pad (T-PAD). The study demonstrated that T-PAD results in the lowest rate of degradation over the entire duration of the test.