US 5,045,141 AGranted

Method of making solderable printed circuits formed without plating

AssigneeAmoco Corporation

InventorsGeorge A. Salensky, Stephen B. Rimsa

Life of this patent

Estimating the term…

Loading patent…

Abstract

Described herein is a composite structure comprising a dielectric substrate surface with an electrically conductive layer or pathway thereon. The pathway comprises a thermoset resin and sufficient electrically conductive metal, in the configuration of an electric circuit element, to provide desired properties and direct solderability. Direct solderability is achieved without plating the electric circuit element. It has a low surface resistivity, preferably less than 10 m ohm per square. Also described are conductive, thixotropic inks for printed circuit devices which include silver powder and silver flake in its composition. A thixotropic adhesive for bonding the electric circuit element to the dielectric substrate surface is also taught. A method for making the composite structure is further disclosed.

Claims32

Dependent claims

A process for forming a directly solderable printed circuit article which comprises:

(1) providing a release surface;
(2) applying an ink comprising a thixotropic thermosetting resin composition containing a desired amount of an electrically conductive metal powder and high surface area metal flake to the release surface in a configuration of an unplated, solderable electric circuit element;
(3) the thermosetting resin comprising a mixed resin composition of a cross-linkable resin and a thermoplastic resin possessing functionally reactive groups capable of reacting with functionally reactive groups in the cross-linkable resin;
(4) drying the ink;
(5) printing in registration with the ink circuit element a reactive thixotropic adhesive interface capable of interacting with the thermosetting resin composition of step (2) and a dielectric surface;
(6) drying the thixotropic adhesive;
(7) bringing together the release surface and the dielectric surface so that the unplated, solderable electrical circuit element is facing the dielectric surface and is separated therefrom by the thixotropic adhesive interface;
and
(8) applying sufficient heat and pressure to form a composite structure whereby the thermosetting resin is cured and the adhesive is interacted whereby the solderable electrical circuit element is transferred from the release surface to become bonded to the dielectric surface.

6 more elements

Dependencies are inferred from the claim text.