COMPOSITION AND COATING TO PREVENT CURRENT INDUCED ELECTRO-CHEMICAL DENDRITE FORMATION BETWEEN CONDUCTORS ON DIELECTRIC SUBSTRATE

• Main Authors: BREWER, WILLIAM DEAN, NOYAN, ISMAIL CEVDET, HORTON, RAYMOND ROBERT, PALMER, MICHAEL JON
• Format: Patent
• Language: English
• Published: 04.03.1992
• Edition: 5
• Subjects: BASIC ELECTRIC ELEMENTS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; PRINTED CIRCUITS; SEMICONDUCTOR DEVICES

The present invention comprises the use of a copper/ nickel containing alloy composition or application of a protective nickel alloy coating to copper current-carrying leads to prevent electrolytic migration between tape automated bonding (TAB) package leads. One embodiment of the invention comprises a substrate having adhered thereon a plurality of nickel-copper alloy current-carrying leads. Option-lly, an intermediate adhesion promoting layer is located between the substrate and the leads. Another embodiment relates to electronic circuit packages comprising a substrate (11) and copper current-carrying leads (13) wherein the exposed area of the copper current-carrying leads is overplated with a more durable metal, such as a noble metal (14), to thereby enhance the circuits' corrosion resistance, solderability and bondability. This durable metal layer is in turn plated with a nickel-containing barrier layer (15). By virtue of the alloy composition or the protective coating materials applied to the copper current-carrying leads in accordance with the present invention, electrolytic migration can be substantially reduced or eliminated.