Abstract: A method for producing circuit boards in which a plurality of planar circuit board bases having a circuit pattern thereon are interconnected at predetermined points. The method includes the steps of applying a mask over the circuit pattern on a base leaving, at the points to be interconnected, a window in the mask; applying an adhesive coating over the mask with the adhesive coating extending over the mask windows and onto the circuit pattern metal to form a second smaller window; treating and depositing metal on said adhesive coating to form a second circuit pattern on the plane of said adhesive and interconnecting the second circuit pattern with the first circuit pattern at said second windows; and, repeating said steps until a circuit board of the desired number of planar circuit patterns is produced.

Abstract: The present invention relates to a semi-additive or full-additive process for producing printed circuit or conductor boards having improved electrical resistance in which the coating of adhesive medium exposed between the trains of conductors is removed or partially removed without corroding the base material or copper of the conductor trains by a treatment with an alkaline permanganate or chromic acid solution and suitable washing steps carried out subsequently.

Abstract: A method for producing printed circuit boards with holes having walls provided with a metal coating on base material provided with an adhesive layer which, in turn, is covered by a masking foil composed of plastic material or metal. Following the preparation of the pattern of holes and prior to the removal of the masking foil, the layer of adhesive coating is removed at the edges of the holes by chemical action, so that an annular zone free of adhesive is formed underneath the masking foil. The masking foil is subsequently removed and the metallization of the pattern of conductors and walls of the holes is produced by currentless deposition alone or combined with galvanic precipitation.

Abstract: Metal-complex compounds suitable for use in the electroless deposition of said metal are formed in aqueous solution by a method which comprises providing an aqueous solution of the complexing agent, immersing in the solution at least one anode comprising the metal to be deposited and at least one cathode, the anode and cathode being connected to an adjustable current source, applying a current to the anode and cathode to create a voltage difference therebetween which is sufficient to dissolve metal from the anode into the aqueous solution of the complexing agent and thereby form a compound of the metal and complexing agent, and depositing a lesser amount of metal from solution onto the cathode to enrich the solution in the metal-complex compound. In other embodiments of the invention, devices for carrying out the process are also provided.

Abstract: There is provided an improvement in the method of preparing printed circuit boards by chemically catalyzing the surface of an insulating material, electrolessly depositing a layer of copper thereon, masking selected areas of the copper layer not correspnding to the desired pattern of conductor lines, electrolytically depositing additional copper on the unmasked areas, removing the masking material and etching away the copper from the previously masked areas. The improvement comprises the steps of forming an etch-resistant protective layer of oxide on the surface of the electrolytically deposited copper layer before removing the masking material, then removing the masking material and etching away the electrolessly deposited copper from the previously masked areas.