Macdermid, Incorporated

Richard L Kremer

Donald R Ferrier

Gary B Larson

John L Cordani

William J Decesare

Edward T Donlon

Donald P Cullen

For attaining adhesion between copper circuitry innerlayers and pre-preg layers in a multilayer printed circuit, a conversion coating of copper oxide is provided on the metallic copper surfaces in a manner which develops an altered topography of the underlying metallic copper surfaces. Thereafter, a controlled dissolution and removal of a substantial amount of the copper oxide is effected, in a manner which does not adversely affect the already-developed topography of the underlying metallic copper, and such that the innerlayer, at the time of assembly with the pre-preg layers, has copper surfaces consisting of the topographically altered metallic copper and a relatively small amount of copper oxide thereon. Excellent bonding strengths are achieved with decreased incidence of pink ring formation as compared to conventional processes utilizing copper oxide for adhesion promotion. In addition, the copper ion containing solutions resulting from the controlled dissolution and removal of copper oxide can be economically utilized in formulating electroless copper plating baths.

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Simsbury, CT, United States of America

Richard L Kremer