High-density multichip interconnect (HDMI)

The operating speeds of VHSIC II ICs require a systems approach to packaging wherein the chip and package must be characterized as a single entity. The package interconnects must be correctly matched to the chip in terms of impedance. The high-density multichip interconnect (HDMI) program is an approach to satisfying these requirements. The emphasis here is on the choice of substrate technology, but the total concept would not be viable without the developments in large ceramic packages, self-testing of ICs, and developments in large-scale multilayer routing programs. The rationale for using a polyimide dielectric is given. A detailed description of the HDMI approach is presented, covering the substrate, the signal dielectric, the interconnect and vias, and the base and package. Computer-aided design and testing are discussed, and the relationship of packaging density to functionality and performance is examined. Some of the constraints, problems, and areas that need further characterization are outlined. The tradeoffs allowed the production of useful circuits