5.3. Improving Switched-Mode Power Supplies Performance with Modified Thermal Interface Material
Speaker: Victor Solera; University of Valencia; Spain
Improving Switched-Mode Power Supplies Performance with Modified Thermal Interface Material
The trend that electronics is following is the use of switched-mode power supplies (SMPS) in more devices. This is due to an issue with energy efficiency. SMPS is closely related to the concept of power density. Power density is defined as the equipment’s power output per unit volume. Therefore, SMPS are required to take up a small space, high power density. This requirement or trend of SMPS can be achieved by using high switching speeds, high dv/dt.
The high switching speeds enable the SMPS’ components, primarily the inductor, to have lower inductance and, therefore, be smaller. Thus, by requiring less space, the power density is higher.
Voltage converters use a switching element, in most cases this component is the mosfet. The mosfet can reach high temperatures during operation. Therefore, heatsinks are added to reduce the temperature. Additionally, a thermal interface material (TIM) foil is used in conjunction with the heatsink. This foil is placed between the mosfet’s thermal pad and the heatsink to prevent electrical conductivity for safety reasons.
However, the use of high frequencies improves the power density but worsens the electromagnetic compatibility (EMC) aspect of the circuit. This is because fast switch speed is a source of electromagnetic interference (EMI). The effect of fast switch speeds is more significant when heatsinks with a TIM foil are used to reduce the mosfet temperature. This is due to a parasitic capacitance that is formed, whose current increases with high dv/dt. Thus, generating high levels of common-mode (CM) current.
Most EMI solutions typically compromise the device’s thermal performance, and vice versa. Therefore, an attempt is made to reach a trade-off between the two topics. In this paper, a hybrid solution is proposed to achieve a favorable trade-off between thermal and EMI aspects. This solution consists of a copper foil between two TIM foils. Allowing, firstly, to maintain the electrical isolation between the mosfet and the heatsink. And, finally, to reduce conducted CM interferences while the thermal aspect is not significantly deteriorated.
The tested and modelled passive component for thermal management and common-mode current filtering is capacitor.
Victor Solera, Jose Torres, Adrian Suarez, Pedro A. Martinez, Andrea Amaro, Roberto Herraiz; University of Valencia, Spain
Sebastian Mirasol, Jorge Victoria, Würth Elektronik eiSos
Víctor Solera (speaker) received the B.S. and M.S. degrees in electronics engineering from the University of Valencia, Valencia, Spain, in 2023 and is currently pursuing the Ph.D. degree in electronics engineering from University of Valencia, Valencia. Since 2023, he has been working as Research Assistant with EMC Catedra University of Valencia-Würth Elektronik eiSos, Electronics Engineering Department, University of Valencia, Valencia.
Sebastián Mirasol received the B.S. degree in telematic engineering from the University of Valencia, Valencia, Spain. He is currently pursuing the M.S. degree in electronics engineering at University of Valencia, Valencia, Spain.
He is Product Manager & Thermal Management Engineer for EMC Shielding & Thermal Materials Team at Würth Elektronik eiSos.
José Torres received the B.S. and M.S. degrees in electronics engineering from the University of Valencia, Valencia, Spain, in 2000 and the Ph.D. degree in electronics engineering from University of Valencia, Valencia, in 2005. This author became a Member (M) of IEEE in 2002 and a Senior Member (SM) in 2012.
From 2013 to 2015, he was a Research Assistant with the Design of Communication and Digital Systems Research Group, University of Valencia. Since 2015, he has been working as Research Assistant with EMC Catedra University of Valencia-Würth Elektronik eiSos, Electronics Engineering Department, University of Valencia, Valencia. He has been part of more than 20 national and international projects as a researcher and coordinator. He is co-author of more than 30 scientific papers and reviewer of several IEEE journals.
Jorge Victoria received the Laurea degree in electrical engineering from the University of Valencia, Valencia, Spain, in 2005 and the Industrial Ph.D. degree in electronics engineering at University of Valencia, Valencia, Spain.
Since 2014 he is Co-Director of the EMC Catedra University of Valencia-Würth Elektronik eiSos. He is Team Leader for EMC Shielding & Thermal Materials Team at Würth Elektronik eiSos. His research interests include the advanced characterization of shielding materials to manage EMI interferences, specifically those based on magnetic sheets such as sintered ferrite sheets or noise suppression absorbers.
Adrián Suárez has been an Assistant Professor at the Electronic Engineering Department of the University of Valencia (UV), Spain, since 2022. He developed his research as a member of the Communications and Digital Systems Design Group – DSDC at the UV. Dr. Suarez received the B.S. and M.S. degrees in Electronic Engineering from the University of Valencia in 2013 and the Ph.D. in Electronic Engineering from the University of Valencia in 2021. He has worked as a Research Engineer within the Cátedra EMC. Since 2017, he has worked as an Adjunct Professor with the Electronics Engineering Department at the University of Valencia.
Pedro A. Martínez received the B.S. and M.S. degrees in electronics engineering from the University of Valencia, Valencia, Spain, in 2012 and is currently pursuing the Ph.D. degree in electronics engineering from University of Valencia, Valencia. This author became a Member (M) of IEEE in 2012. Since 2016, he has been working as Research Assistant with EMC Cátedra University of Valencia-Würth Elektronik eiSos, Electronics Engineering Department, University of Valencia, Valencia
Andrea Amaro was born in Alicante, Spain, in 1998. She received the B.S. degree in electronics and telecommunications engineering in 2020 and the M.S. degree in electronics engineering in 2021 from the University of Valencia, Valencia, Spain, where she is currently working toward the Ph.D. degree in electronics engineering. Since 2021, she has been working as a Researcher with the Electronics Engineering Department, University of Valencia. Her Ph.D. is related to the study of EMI shielding effectiveness in new alternative materials for mobility applications. She belongs to the EMC Society.
Roberto Herráiz holds a degree in Physics, a degree in Telecommunications Electronics Engineering, and a Master’s degree in Medical Physics and Electronics Engineering. He is currently a researcher in the Digital Communication Systems Design (DSDC) group and a professor in the Department of Electronic Engineering at the University of Valencia.