International Business Machines Corporation

Leann G Keim

Krystyna Waleria Semkow

Daniel C Van Hart

Peter J Duke

Ralph S Paonessa

Disclosed is a method of fabricating a microelectronic package, especially a microelectronic package having gold plated copper circuitization on a polyimide substrate. The method includes the steps of forming a pattern of copper circuitization on the selected portions of the polyimide substrate, and thereafter depositing a gold thin film of selected portions of the copper circuitization layer. The gold thin film is electrodeposited from an electrodeposition solution of KAu(CN).sub.2, K.sub.2 HPO.sub.4, and KH.sub.2 PO.sub.4, modified by the addition of an effective amount of NH.sub.4.sup.+.

Gold plating bath additives for copper circuitization on polyimide

Disclosed is a method of fabricating a microelectronic package having least one layer formed of a Cu-Invar-Cu core encapsulated between a pair of dielectric films. The package is intended to carry surface circuitization on an external surface, with internal circuitization from the surface circuitization passing through the core. The method includes contacting the copper within the Cu-Invar-Cu core with a copper etching aqueous solution of a strong base and a strong oxidizing acid, while maintaining the copper anodic. This electrolytically converts the copper to soluble copper oxides. In a separate step the Invar of the Cu-Invar-Cu core is electrolytically etched with an Invar etching aqueous solution of sodium chloride. This step is carried out under conditions to electrolytically form soluble iron and nickel chlorides while passivating the copper.

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Endicott, NY, United States of America

Leann G Keim