Thermal characterization of vias using compact models

Thermal vias and balls are key elements in plastic ball grid array (PBGA) package thermal design as they enhance the package performance. Simulation is a versatile design optimization tool for characterizing the thermal vias and balls. However, the finer geometric details of the vias require excessive memory and modeling and simulation time. Different modeling concepts are being tried in the industry to include finer geometries in the package. This paper shows a methodology of developing compact thermal via models and validating the same with detailed models. The accuracy of compact thermal via models with respect to the detailed models has been determined using PBGA 352 as the test vehicle. It is found that the accuracy is within 3%. The simulation models of PBGA 352 have been validated by measurements and found that the accuracy of model is within 10%. Two and four layer PBGA 352s with different via configurations have been characterized with compact thermal via models, and design guidelines for PBGA 352 packages have been obtained.