SELECTION OF APPROPRIATE THERMAL MODEL FOR PRINTED CIRCUIT BOARDS IN CFD ANALYSIS

Electric circuits in printed circuit boards (PCBs) are made of intricate patterns of copper traces organized in several layers within the substrate – usually FR4. Creating exact CFD or numerical models of the actual traces is computationally expensive and impractical today. Abstract representations are therefore used. Two commonly used models are the lumped (compact) PCB model and the layer-wise lumped (LL) model. The LL model, sometimes called “detailed” model, is generally considered as more accurate but is also computationally more expensive. This work presents a numerical and analytical study of the two models. Results from the two models are compared in an extensive parametric study with heat transfer coefficient, number of trace layers, trace coverage, and PCB to source size, as the variable parameters. It is hoped that this study and the analytical solutions can serve as insightful tools in predicting the error between the compact and the LL model of any given PCB.