A thermal model for the PCB structure including thermal contribution of traces and vias

The present model is mainly targeted at thermal simulation of multilayer PCB structure, realizing 2-D layout analysis and taking into account temperature-dependent Joule heating in traces as well as thermal conduction in traces and vias. The structure is analyzed by loading 2-D layout bitmaps of each metal layer in the program, and heat sources as well as traces are meshed in square elements due to the requirement of rectangular heat-source elements in the derivation of analytical solution of the temperature in dielectric layers. The main calculation process is in matrix operation and the model is programmed in the Matlab. The model runs in an iterative way by exchanging heat density and temperature distribution between two main programs, electric solver and thermal solver. The electric solver is able to analyze electrical distributions in each trace as long as there are sufficient known conditions of rms electric potentials or rms branch currents for some pads connected to the trace. The thermal solver integrates both the analytical solution of the rectangular homogeneous structure with square heat sources and the numerical analysis of non-uniform heat transfer coefficient (HTC) distribution and thermal conduction in traces and vias. In order to examine the algorithm in the model, the comparison between the model and a CFD software is given for a two-layer structure. Particularly, the model is more efficient in analyzing the structure with LDR (large dimension ratio) between the whole structure and heat sources.