Crosstalk issues in flip chip multichip modules

A multilayer 2.5 Gbit/sec superconducting Multichip Module (MCM) has been modeled to investigate the feasibility of meeting specified performance goals. Due to the high speeds required flip chip bonding of the Josephson Junction Integrated Circuits (IC's) is used. The MCM is comprised of both Polyimide (PI) dielectric and Mullite ceramic substrates, forming in effect an MCM-D/MCM-C hybrid structure. Niobium (Nb) low temperature superconductor (LTS) is used on the PI dielectric layers to form IC-data and IC-control nets that connect from chip to chip with transmission-line impedance of 2 and 8 ohms, respectively. In the Mullite layers, Tungsten (W) is used for clock, data in, data out, and control lines, all of 32 ohms, that connect from the IC's to the MCM I/O ports.