Motherboard heat transfer modeling methodology

A standard modeling method to represent conduction in motherboard (MB) for predicting a ball-grid array package temperature is developed. It is shown that discrete representation of individual copper and FR4 layers within MB rather than an effective block is needed for accurate thermal prediction. The MB signal layers consists of set of parallel copper traces and are represented by orthotropic layer to capture direction-sensitive thermal conduction along the traces. The role of through-hole vias in MB is captured by augmenting the through-plane conductivity of FR4 layers. The methodology uses a set of prismatic and/or polygon blocks with orthotropic thermal conductivities and can be implemented in existing computational fluid dynamic (CFD) and heat transfer tools. A MB-level test set-up is developed to validate the proposed modeling methodology under a range of airflow conditions and it is shown that the model results match the test data with maximum error of 14%