Thermal simulation and validation of the fast static RAM 164-lead FC-PBGA package with investigations of package thermal performance in a generic CPU module

Abstract

The steady-state thermal performance of the 164-lead flip chip plastic ball grid array (FC-PBGA) under low to moderate convective air cooling conditions has been simulated through finite element (FE) methods and computational fluid dynamics (CFD) methods. Experimental measurements taken with thermal test vehicles of this package were used to validate the simulations. Packages with three different substrates were investigated. Package performance has been presented in the form of a linear relationship between the normalized junction-to-ambient thermal resistance (/spl theta//sub JA/) versus the normalized board-to-ambient thermal parameter (/spl psi//sub BA/). Results cast in this form represent a first-order thermal figure of merit for packages. Such a figure of merit can be used to rank in a consistent manner the thermal performance of different package types. A CFD study was performed to investigate the thermal performance of the package on a central processing unit (CPU) module assembly. A parametric study was performed to investigate the die temperatures as a function of thermal interface materials and heat sink configuration. Sink solutions were studied. The results of those board-level simulations give a reasonable indication of how the package would perform in a workstation environment.