Abstract: In an aspect, a circuit material comprises a multilayer stack comprising alternating layers of a reinforcing layer and a fluoropolymer layer; wherein the fluoropolymer layer comprises a fluoropolymer other than a biaxially-oriented polytetrafluoroethylene; wherein the reinforcing layer comprises a biaxially-oriented polytetrafluoroethylene; and wherein an conductive layer is in direct physical contact with an outer surface of the multilayer stack. In another aspect, an article comprises the circuit material. In yet another aspect, a method of making the circuit material comprises laminating the multilayer stack and the conductive layer to form the circuit material; or laminating a layered stack comprising the conductive layer and alternative layers of the fluoropolymer layers and the reinforcing layer to form the circuit material.

Abstract: A method for enhancing the adhesion between a metal surface and a circuit board substrate comprises contacting the metal surface with adhesion promoting solution comprising poly(vinyl butyral) having a molecular weight of about 70,000 to about 200,000 and a carrier; allowing the carrier to evaporate and forming an adhesion promoting layer; contacting the adhesion promoting layer with a curable thermosetting circuit board substrate composition; and curing the thermosetting composition. Use of an adhesion promoting layer comprising poly(vinyl butyral) having a molecular weight of about 70,000 to about 200,000 causes a large increase in both the tensile bond strength between the metal surface and thermoset resin and the uniformity of the tensile bond strength.