IBM System/390 air-cooled alumina thermal conduction module

Advances in multilayer ceramic (MLC) processing, the use of thin-film metallurgy wiring, and enhancements in thermal dissipation, all described in this paper, represent significant milestones in the evolution of microelectronic packaging technology. The IBM System/390™ air-cooled alumina thermal conduction module (S/390™ alumina TCM) utilizes a 127.5 × 127.5-mm MLC substrate to interconnect as many as 121 VLSI devices and 144 substrate-mounted decoupling capacitors. The substrate provides an array of 648 pads for solder connections to each device, an array of 16 pads for solder connections to each capacitor, and an array of 2772 pins for interconnection with the next package level, and contains approximately 400 m of wiring. The reduced thermal resistance design permits up to 600 W of air-cooling capacity. This paper describes the S/390 alumina TCM fabrication processes and discusses the advances they represent in processing technology, packaging density, and performance. Comparisons to prior technology are made.