A thin film multichip module which utilizes very high density wiring on a silicon substrate has been developed. The technology has been demonstrated using the IBM RISC (reduced instruction set computer) System/6000 processor as a vehicle. The prototype module contains a RISC processor consisting of nine CMOS VLSI chips. The package also contains decoupling capacitors and has 684 I/O. The substrate consists of a thin film structure fabricated on a silicon wafer using a polyimide dielectric and aluminum metal. All fabrication was done in an existing CMOS manufacturing line. IBM's C4 (controlled collapse chip connection) flip chip bonding technique was used to connect the CMOS VLSI chips to the package. The silicon substrate was packaged nonhermetically and connected to the next level of packaging using very high density surface mount flex cables. A clip-on heatsink was attached to the finished module, which allows for up to 30 W of power dissipation in the air flow found in a typical workstation environment.
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