Development of RC network compact models of IC packages using multigrid method

The need for compact models of Integrated circuits (IC) is a well-recognized problem in electronics cooling simulations of electronic systems. Simplified thermal models have been reported in the literature to simulate the transient thermal behavior of IC devices. Most of the simplification approaches require a pre-determined topology of a resistance-capacitance (RC) network. Multigrid technique allows for automatically constructing both the topology and characteristics of the reduced-order or compact models of devices (primarily IC packages) for use in system-level simulations. In this study, we report an approach where the topology and the nodal RC values of the network are automatically generated. The procedure is also applicable for complex IC sub-systems or systems like multi-chip modules, stacked die package, system-in-package, and CPU module, and hard drives. In the study report herein, the method is applied to three types of IC packages. The first package is a 196-pin fine pitch ball grid array (FBGA15×15_196 L) package. The second package is a 480-pin plastic ball grid array (PBGA+HS37.5×37.5_480 L_extHS) package with drop-in heat spreader. An external heat sink is attached to the top surface of the package. The third package is an 8-pin small outline IC (SOIC_480 L) package with a total power dissipation of 0.5 W. RC networks are created for these packages and then used in CFD simulations for different boundary conditions, corresponding to single phase natural and forced convective cooling. The simulation results are compared to the corresponding detailed package simulations.