A study of compact thermal model topologies in CFD for a flip chip plastic ball grid array package

A previously validated detailed model of a 119-pin Flip-Chip Plastic Ball Grid Array (FC-PBGA) package was created and validated against experimental data for natural convection and forced convection environments. Next, two compact models were derived, a two-resistor model (created using the JEDEC-standard based computational approach), and a multi-resistor model (created using the DELPHI optimization approach that was boundary condition independent within engineering accuracy). The compact models were placed in natural convection and forced convection (velocities of 1 and 2 m/s) environments with and without a heatsink. Based on the agreement obtained between the detailed model and compact model simulations, the accuracy and validity of the two compact models was assessed. Of the two compact thermal models considered, the Delphi multi-resistor model provided the same predictive estimates (within 5%) as simulations involving a detailed thermal model of the package in natural and forced convection environments both with and without attached heatsinks. Some thermal modeling issues were addressed with respect to implementation of compact thermal models with attached heatsinks.