Abstract: A process for producing circuit boards involves the coating of a temporary substrate with a fluid mixture of an epoxy polymer component and a rubber polymer which is interactive therewith at temperatures of at least 180.degree. F. Preferably the rubber is a low molecular weight polyfunctional reactive butadiene/acrylonitrile interpolymer which is terminated by vinyl or carboxyl functional groups. The rubber component comprises at least 70 percent by weight of the epoxy polymer component, and the coating has a thickness of 0.001-0.015 inch. The coating is air dried upon the temporary substrate, and then the coating is transferred to the resinous substrate of the circuit board by heat and pressure. The coating is partially cured to effect partial polymerization of the epoxy prepolymer, further polymerization of the rubber, if it is of low molecular weight, and interaction of the rubber and epoxy polymer to form a matrix of the interacted rubber/epoxy.

Abstract: A process for producing circuit boards involves the coating of a resinous substrate with a fluid mixture of an epoxy polymer component and a rubber polymer which is interactive therewith at temperatures of at least 180.degree. F. Preferably the rubber is a low molecular weight polyfunctional reactive butadiene/acrylonitrile interpolymer which is terminated by vinyl or carboxyl functional groups. The rubber component comprises at least 70 percent by weight of the epoxy polymer component, and the coating has a thickness of 0.001-0.015 inch. The coating is partially cured to effect partial polymerization of the epoxy prepolymer, further polymerization of the rubber, if it is low molecular weight, and interaction of the rubber and epoxy polymer to form a matrix of the interacted rubber/epoxy. The exposed surface of this coating is then etched, and metal is deposited on the surface to form a conductive layer.

Abstract: A process for producing circuit boards involves the coating of a resinous substrate with a fluid mixture of an epoxy polymer component and a rubber polymer which is interactive therewith at temperatures of at least 180.degree. F. Preferably the rubber is a low molecular weight polyfunctional reactive butadiene/acrylonitrile interpolymer which is terminated by vinyl or carboxyl functional groups. The rubber component comprises at least 70 percent by weight of the epoxy polymer component, and the coating has a thickness of 0.001-0.015 inch. The coating is partially cured to effect partial polymerization of the epoxy prepolymer, further polymerization of the rubber, if it is low molecular weight, and interaction of the rubber and epoxy polymer to form a matrix of the interacted rubber/epoxy. The exposed surface of this coating is then etched, and metal is deposited on the surface to form a conductive layer.

Abstract: The present invention provides a process for making a thermosetting resin article which comprises (a) impregnating a compressible opencell sheet with a thermosetting resin (b) applying a fibrous layer to at least one side of the sheet, (c) allowing the assembly to cure. The invention further is directed to thermosetting articles made by this process.

Abstract: This invention is an improvement in a process for making a thermosetting resin article.In the process of producing an article of thermosetting resin which comprises (a) impregnating a sheet having an open-cell structure with a curable thermosetting resin, (b) applying a layer of fibrous reinforcing material to at least one side of the impregnated sheet, (c) compressing the sheet and reinforcing layer to the extent that resin is expelled from the sheet into the fibrous reinforcing layer and (d) allowing the resin in the sheet and layer to cure while maintaining the compression, the improvement which comprises uniformly incorporating a gas release agent into the curable thermosetting resin to promote the expulsion of resin from the sheet into the reinforcing layer.The invention also includes an open-cell sheet impregnated with a mixture of a curable thermosetting resin, an effective curing agent for said resin, and a compatible gas release agent.

Abstract: This invention relates to an improvement in the process of preparing an article of a reinforced thermosetting resin. The known process comprises a) impregnating a foam sheet with a curable thermosetting resin, b) applying a layer of fibrous reinforcing material to a side of the impregnated foam sheet, c) compressing the impregnated foam sheet so that the resin impregnates the fibrous material, and d) allowing the sheet and layer to cure while compressed. The improvement of this invention comprises effecting the compression of the foamed sheet and fibrous material by the expansion pressure of a foaming composition.

Abstract: This invention is an improvement in a process for making a thermosetting resin article.In the process of producing an article of thermosetting resin which comprises (a) impregnating a sheet having an open-cell structure with a curable thermosetting resin, (b) applying a layer of fibrous reinforcing material to at least one side of the impregnated sheet, (c) compressing the sheet and reinforcing layer to the extent that resin is expelled from the sheet into the fibrous reinforcing layer and (d) allowing the resin in the sheet and layer to cure while maintaining the compression, the improvement which comprises uniformly incorporating a gas release agent into the curable thermosetting resin to promote the expulsion of resin from the sheet into the reinforcing layer.The invention also includes an open-cell sheet impregnated with a mixture of a curable thermosetting resin, an effective curing agent for said resin, and a compatible gas release agent.