THERMAL STRATEGY FOR MODELING THE WIREBONDED PBGA PACKAGES

The Plastic Ball Grid Array (PBGA) package attracts considerable interest, being one of the most promising packaging technologies of the moment. Thermal analysis of a package and a Printed Circuit Board (PCB) stack-up is performed for a better understanding of package constitutive elements, allowing an enhanced thermal coupling of package and board for cost effective thermal management. A commercial Computational Fluid Dynamics (CFD) software was applied for thermal simulation. The study focuses on detailed thermal modeling of a 256 Wirebonded PBGA (depopulated bump array) package in a natural convection setup. The model was refined to include all the features, and the calculated junction-to-ambient thermal resistance for each simulation was compared to available experimental data. The order of creating the internal structures in the model has a strong impact on the package thermal characteristics. The calculated errors varied from 5% (detailed model) to 43% (simplified model).