GaAs multichip module for a parallel processing system

The module described is a high-speed data transfer network for a parallel processing system. The high-speed data transfer network connecting multiple processor units was realized in a module using 8-bit slice GaAs bus logic (BL) LSIs which operate at 100 MHz. The GaAs multichip module consists of 12 GaAs BL LSIs in a 3×4 matrix. Each GaAs chip is sealed in a chip carrier with bumps. The chip carrier is flip-chip bonded to a copper/polyimide thin-film multilayer substrate. The characteristic impedance of the signal lines on the module is controlled to 75 Ω to be compatible with the GaAs original interface level. The thin film termination resistors are made of Ni/Cr in the substrate to prevent reflections. Heat generated from the module, which has a total of 90 W of power dissipation, is transferred through four heat pipes with fins by forced-air cooling at <2 m/s. A 3-Gbit/s data transfer rate can be realized by four stacked modules of 38 GaAs BLs