MCM technology and design for the S/390 G5 system

The multichip module (MCM) that contains the central electronic complex (CEC) of the S/390® G5 system is described in this paper. The glass-ceramic module, topped with six layers of polyimide full-field thin-film wiring for chip-to-chip interconnection, represents IBM's most advanced packaging technology. This MCM provides a large wiring capacity, with 595 meters of routed interconnection; it supports the highest synchronous interconnection performance in the industry at 300 MHz; and it allows for cooling flexibility at the system level—either a heat sink for air-cooled systems or a cooling “hat” for systems using refrigeration cooling. The physical and electrical characteristics of this packaging technology, necessary to support the aggressive system performance goals (1040 MIPS) of the IBM G5 Enterprise Servers, are presented here. In addition, the approach used to produce a robust electrical and physical design is described.