The First Thin Film Electronic Package: From Invention to Manufacturing
An important new application of electroplating technology was in the fabrication of the multichip module. In advanced computers, these modules were multilayer ceramic structures that provided the power connections to the circuit chips and had a top layer of copper strip lines for data transmission between chips. The strip lines consisted of copper conductors with a rectangular cross-section that might be 6 µm high and 10 to 20 µm wide embedded in polyimide between two ground planes. These structures, which were essentially low-loss transmission lines, had to have precisely controlled propagation characteristics to minimize pulse distortion. Plating through a lithographic mask was an effective way of insuring the tight control on the geometry of the lines necessary to meet this requirement. One aspect of this talk will be to highlight the technical aspects of integrating electrochemical technology into the fabrication process for the transmission lines. The other will address how the scientists and engineers from the IBM T.J. Watson Research Center who had created the thin film head, worked with the development and manufacturing engineers at IBM’s East Fishkill plant to bring electrochemistry into their production line.
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