Steady-State Heat Transfer in Class I MLCCs for Resonant Power Converter Applications

Resonant power converters utilize Class I multilayer ceramic capacitors (MLCCs) to create resonant LC circuits which enable power conversion at high levels of efficiency. MLCCs in such an application will dissipate power which causes component temperatures to rise. Loss in the dielectric and electrodes are the primary contributors to this heat generation, and the dominant loss mechanism depends on the frequency of operation. Heat generated by the MLCC is conducted by the metal electrodes to the terminations of the MLCC. From the terminations, heat is transferred into the PCB assembly and surrounding environment. An efficient thermal management solution is required to ensure the MLCC device temperature does not exceed the maximum allowable temperature rise for the part. This paper seeks to explain how MLCC construction methods and operating conditions effect the way heat is generated in the MLCC and transferred through the MLCC structure into the external environment. A thermal resistance model and an in-situ method for estimating the power dissipation and thermal resistance of MLCCs is also presented.