The authors describe an ATM (asynchronous transfer mode) switch constructed of copper polyimide multilayer multichip modules (MCMs). High-throughput ATM switching systems require high-speed interconnections and high-density packaging to reduce the interconnection lengths. An ATM prototype switching system which consists of two ATM switch MCMs was developed. The ATM switch MCM contains 24 LSIs and a multilayer substrate with polyimide dielectric and a fine pattern copper conductor. A fine pitch flexible lead 680-way connector was developed to achieve a high-speed interconnection between the MCM and the printed circuit board. TAB (tape-automated-bonding) was used to allow pretesting of the LSI devices and to mount high pin count LSI devices onto the MCM. This system performed 16*16 ATM cell switching at 150 Mb/s. Furthermore, it transmitted NRZ (nonreturn-to-zero) signals of up to 800 Mb/s between MCMs via fine-pitch flexible lead connectors and a 40-cm line in the printed circuit board.
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