Session: 12-13-01: Heat Transfer in Electronic Equipment I

Paper Number: 163732

Electro-Thermal Analysis of an Air-Cooled TO-247 SiC MOSFET: Heat Flux Distribution and Cooling Performance 

Recent advancements in wide bandgap semiconductor materials, such as Gallium Nitride (GaN) and Silicon Carbide (SiC), allow power-switching devices to operate at higher frequencies and power levels. Effective thermal management is of vital importance for ensuring the reliability and efficiency of high-frequency, high-power semiconductor devices. Inadequate thermal design can lead to excessive temperature rises, degrade performance, reduce lifespan, and potentially cause system failure. Conversely, operating at temperatures significantly below the optimal range can result in suboptimal system performance and reduced power density. Therefore, maintaining an appropriate thermal environment is crucial for ensuring system reliability and efficiency. This study investigates the thermal behavior of a TO-247 package SiC MOSFET switch equipped with a finned heatsink, using air cooling under steady-state and dynamic conditions at various power ratings. A comprehensive thermal analysis is conducted to evaluate key thermal characteristics, including heat source temperature, temperature gradients, and heat flux distribution within the package. Both manufacturer datasheets and analytical models are employed to calculate power losses, which serve as input for thermal simulations. ANSYS Fluent is utilized to perform detailed thermal simulations and evaluate cooling effectiveness.

Power loss in GaN-based power switches consists of two main components: switching loss and conduction loss. These losses occur in different regions of the switching die and are influenced by the direction of electrical current flow. During operation, current passes either through the main switch or the anti-parallel diode, each contributing differently to overall power dissipation. This paper analyzes these effects and their impact on total power loss. Additionally, heat generated in the GaN die transfers through mechanical, insulation, and substrate layers before reaching the Drain surface. The Drain is thermally connected to an air-cooled heatsink, which serves as the primary heat dissipation mechanism.

This study provides a first-of-a-kind heat flux distribution analysis to characterize how heat propagates from the switching die to many layers of the switch structure through the heatsink and into the surrounding air, identifying potential hotspots. By analyzing temperature gradients at different power levels, this research aims to establish trends in thermal performance and assess the feasibility and limitations of air cooling for high-power applications. In addition, the study focuses on analyzing heat dissipation pathways and assessing the capability of air cooling with variable air flow rates to regulate device temperature. The role of the finned heatsink in improving thermal performance is thoroughly analyzed, with particular attention given to its impact on thermal resistance and temperature dispersion. By modeling convective heat transfer from the heatsink to the surrounding air, the study quantifies the influence of air cooling on temperature distribution.

The results of this study will provide a deeper understanding of the electro-thermal interactions in power devices and serve as a reference for optimizing air-cooled configurations for power electronic MOSFETs. This research helps identify key parameters that influence thermal performance and reliability by analyzing temperature distribution and heat dissipation pathways.  By establishing a clear correlation between power dissipation, temperature rise, and heat transfer efficiency, this study aims to guide the development of more efficient thermal management strategies. The insights gained will be valuable in designing reliable cooling solutions that ensure the longevity and performance stability of power semiconductor devices operating under demanding thermal conditions.

Presenting Author: Hooman Taghavi University of South Carolina

Presenting Author Biography: Hooman Taghavi holds a Bachelor's degree in Mechanical Engineering from Shomal University, Amol, Iran (2012–2016). In 2021, he began his Master's in Mechanical Engineering at the University of South Carolina (USC), focusing on water-based cooling systems for high-power applications. During the final semester of his Master's, he started his PhD in Mechanical Engineering, specializing in thermal management and air- and water-based cooling systems for high-frequency switching devices. His research interests include thermal management, mechanical design, and cooling system development. Currently, he is a Graduate Research Assistant at USC and an Advanced Development Engineering Intern at Flanders.

Authors:

Hooman Taghavi University of South Carolina
Reza Mounesi University of South Carolina
Jamil A. Khan University of South Carolina
Adel Nasiri University of South Carolina