Thermal characterization for a modular 3-d multichip module

NASA Goddard Space Flight Center has designed a high-density modular 3-D multichip module (MCM) for future spaceflight use. This MCM features a complete modular structure, i.e., each stack can be removed from the package without damaging the structure. The interconnection to the PCB is through the Column Grid Allay (CCA) technology. Because of its high-density nature, large power dissipation from multiple layers of circuitry is anticipated and CVD diamond films are used in the assembly for heal conduction enhancement. Since each stacked layer dissipates certain amount of heat, designing effective heal conduction paths through each stack and balancing the heal dissipation within each stack for optimal thermal performance become a challenging task. To effectively remove the dissipated heat front the package, extensive thermal analysis has been performed with finite element methods. Through these anal),ses, we are able to improve the thermal design and increase the total wattage of the package for maximum electrical performance. This paper provides details on the design-oriented thermal analysis and performance enhancement. It also addresses issues relating to contact thermal resistance between the diamond film and the metallic hear conduction paths.