Advanced ceramic substrates for multichip modules with multilevel thin film interconnects

Two ceramic materials systems, cofired 99.6% alumina/tungsten and aluminum nitride, are presented as options for use as multichip modules bases. The 99.6% alumina system addresses the limitations of conventional 90-94% alumina systems by providing +or-0.2% dimensional control combined with a smooth, defect-free surface. The 99.6% alumina/tungsten system exhibits an enhanced flexural strength. The injection-molded aluminum nitride produced using the binderless injection molding process is characterized by an average thermal conductivity of 230 W/mK with a standard deviation of 7.3. The controlled microstructure of the AlN material results in a smooth, defect-free surface after lapping and polishing for thin film compatibility. Precise dimensional tolerance control of +or-0.2% for substrate features such as cavities or through holes is provided.<
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