In a complex multichip carrier such as the thermal conduction module (TCM) of IBM high-performance mainframe processors, the interfaces between chips and their substrate as well as between the substrate and its printed circuit board must support a large number of electrical connections. Since chip, substrate, and board typically comprise very different materials, the electrical connections between them must be able to accommodate considerable thermally induced mechanical stress during assembly and use. This paper describes the pin attachment, chip attachment, wire bonding, and laser deletion processes used for forming the electrical connections to the glass-ceramic/copper/polyimide /copper substrate of the thermal conduction modules of the IBM Enterprise System/9000™ water-cooled processors.
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