Packaging technology for IBM's latest mainframe computers (S/390/ES9000)

The IBM system 390/ES9000 mainframe computers are significantly enhanced by a set of packaging materials, glass ceramic and copper conductors. The substrate is based on the crystallization of an unique glass to form a glass-ceramic with a dielectric constant of 5.2 relative to 9.4 with the previous alumina material. The copper conductor exhibits a three-fold improvement in electrical conductivity over molybdenum used in the alumina vintage substrates. The thermal expansion of the substrate, 30*10/sup -7// degrees C, closely matches the silicon chip to which it is solder bonded, thereby enhancing the reliability of the 648 chip-to-substrate connections. A novel sintering process provides the industry's best dimensional control, and results in the closest placement of metal vias to date. The cooling technology has been enhanced to accommodate 16.7 W/cm/sup 2/. The design is comprised of a multifaceted cooling system and an attached cold plate. The model's ability to dissipate heat is augmented by use of oil rather than the helium used in previous models.<
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