Numerical-Analytical Modeling Method for Steady-State Thermal Analysis of the “Core Build” Multilayer Pcb Structure

A modeling method is proposed for steady-state thermal analysis of the “core-build” multilayer PCB structure based on coupling the analytical solution and the Finite Volume Method. The analytical solution of the core in the PCB is expressed according to the Fourier-series solution of temperature and the superposition theorem of thermal effect. The tangential heat-spreading through the metal-foil layer and the vertical thermal conduction through vias are approximately taken into account based on the Finite Volume Method under Cartesian grid. The matrix equations describing the analytical solution and the numerical approximation can be coupled together. Due to the insignificant thickness of the prepreg layer and its much lower thermal conductivity compared to the attached metal-foil layer, the prepreg layer is assumed as a “thermally thick” layer through which only the vertical thermal conduction is taken into account. In this way, the heat-transfer matrix equations for each core can be further coupled to solve the solution of the whole structure. To testify the feasibility of the modeling method, the model of a “core build” four-layer PCB structure is compared with a model built in COMSOL Multiphysics.