Polystrate and Ultrastrate: Complementary Multichip Module Technologies

CMOS devices are approaching the 50 MHz threshold at which conventional electronic assemblies—based on packaged components (SMD, PGA, etc.) mounted on high‐density printed circuit boards—impose a serious penalty on the speed of the raw die provided by the semiconductor vendors. To improve the packaging density and to reduce the resistive and capacitive loads as well as signal delays at the second level of interconnection, new packaging concepts for VLSI and ULSI components are imperative. Multichip modules (MCM) seem to be the only adequate solution to the interconnect problem. Ultrastrate—the author's company's MCM technology with multilayer thin‐film build‐ups—is briefly presented. Life cycles for products in the electronics industry are becoming ever shorter. Electronics engineers must package more complicated circuits in smaller volumes and in a shorter time. On the other hand, prototyping an MCM from the electrical schematic takes at least 12 weeks. There is as yet no equivalent of a PCB breadboard for MCMs! In response to this situation, Polystrate is a new process which has been developed to provide a flexible and fast prototyping tool for MCMs. It satisfies the most stringent requirements with regard to performance, economics and ease of modification, and offers a very fast turn‐around time. The technological synergies between Ultrastrate and Polystrate allow for a smooth transition between the prototyping and production phases.