Reducing Conducted Emissions at Switched-Mode Power Supplies with a Thermal Interface Material

Electromagnetic interference (EMI) tends to be more numerous today due to the current trend in electronics. In addition, designers are becoming increasingly aware of equipment efficiency and thermal management, especially in switched-mode power supplies (SMPS). In most designs, a heatsink is used to reduce the temperature of the components. In addition, a sheet thermal interface material (TIM) is used to provide electrical insulation between the switching component and the heatsink. TIM improves the thermal conductivity too. However, the combination of heatsink and TIM is a source of EMI due to the generation of parasitic capacitances. Therefore, in this study, EMI caused by common-mode (CM) currents generated when a heatsink is used to reduce the temperature of the mosfet is investigated. This study aims to evaluate a solution based on a hybrid material to reduce thermal and EMC problems. The proposed experimental solution is a combination of TIM and copper sheets. The study will be carried out by measuring the CM currents on a DC-DC boost converter. It will evaluate how it influences the use of the heatsink with TIM and the proposed hybrid solution.