Heat dissipation design for a high density-high power chip package

In this paper several heat dissipation mechanisms are studied in an effort to improve heat dissipation of a high-power packaged chip in its environment. Specifically we examine a cavity-down structure consisting of a copper plate in thermal contact with the back side of the chip. In order to evaluate the thermal performance of the cavity-down approach, three structures are compared via simulation. Heat transport occurs by conduction, radiation and convection. The first depends on material properties, thickness and temperature gradient. The second is only effective if the temperature of the radiator is much higher than that of the absorber and the two are in close proximity. Convection is most effective at high mass flow and large differential temperatures. For the problem at hand we consider, several different thicknesses of the copper heat spreader to optimize conduction within the bounds of the package. In addition, forced air convection is optimized, within the package limitations. Optimum cooling conditions are obtained by parameterization of variables: air flow direction, fan position, and package placement.