Importance of boundary conditions for optimizing the thermal dimensioning of PCB traces

The thermal design of a converter requires a correct estimation of the temperature of each and every component that is part of it to guarantee the lifetime of the system. In this paper, the focus is put on the printed circuit board (PCB). The literature presents different approaches for the prediction of the temperature distribution on the PCB, which consider both the contribution of the number and thickness of the copper layers and the quantity of current that is fed. The simulations and fitting equations usually calculate the temperature increase without considering the effect of connections, vias, or components on the trace. This paper will show emblematic examples of how these elements are boundary conditions that can affect the temperature profile, the position and the value of the hotspot. Therefore they can´t be ignored for a proper, optimized thermal design of PCB traces.