Thermo-Mechanical Investigations for PCB Assemblies Using Top-side Cooled Power Devices

In modern power electronics, the push for high density power converters and resulting increase in loss densities within semiconductor devices necessitate the optimization of Thermal Interface Materials (TIMs). This need is particularly critical with the adoption of wide-bandgap semiconductors, where the reduction in active semiconductor volume heightens the influence of TIMs on overall system performance. The TIM plays a pivotal role in thermal management, directly affecting the electrical performance, thermal behaviour at the semiconductor junction, and ultimately, the system's longevity. Since high thermal conductivity TIMs for cutting edge applications are showing strong pressure dependent characteristics, any mechanical deformations in the mounting setup of the TIM will negatively impact thermal performance. This paper examines the impact of PCB warpage on thermal resistance from top-side cooled semiconductors to cooling system, highlighting how such deformations can compromise cooling efficiency. Furthermore, it provides recommendations for TIM modelling, emphasizing its pressure-sensitive behaviour, and compares these models with empirical measurements.