Abstract: Disclosed is a composition and process for the treatment of metallic surfaces, which comprises treating said surface with an aqueous solution comprising a benzimidazole compound which has at least one carboxylic or sulfonic acid group directly or indirectly attached to said benzimidazole compound.

Abstract: The adhesion between surfaces of polyimide, particularly the through hole surfaces of polyimide-based multilayer laminates used in the fabrication of multilayer printed circuits, is improved by pretreatment of the surfaces with an essentially non-alkaline aqueous permanganate solution.

Abstract: Disclosed herein are compositions for use in a process for preparing the surfaces of through-holes in printed circuit boards (especially multilayer printed circuit boards) preparatory to a treatment of the through-holes with an alkaline permanganate solution, the composition being in the form of a substantially homogeneous, substantially clear mixture comprised of a substantially water-immiscible organic material which acts upon the insulating substrate of the circuit board, water, an alkakli metal compound and a surfactant component. The composition is useful as a pretreatment prior to the use of an alkaline permanganate solution in a desmearing and/or etch-back process, a combined desmearing-conditioning process, or a conditioning process following a separate desmearing process.

Abstract: An electroless metal plating process, particularly for use in plating through-holes in printed circuit substrates, and more particularly for additively depositing copper metal on through-hole surfaces, in which the substrate is at least intermittently subjected to vibrating motion in contact with the electroless depositing bath, and an electroless metal depositing apparatus for carrying out the process.

Abstract: A composition for cleaning and improving the adhesion characteristics of a copper surface (which is in turn adhered to an underlying substrate) so as to enable a coating, e.g., of photoresist, to be adhered easily and completely to the copper surface, the cleaning and adhesion promoting composition consisting essentially of an aqueous solution of an alkane sulfonic acid, a surfactant and an oxidizing agent of a type, and present in an amount, sufficient to provide controlled conversion of the copper surface to a substantially clean, micro-roughened surface, without removing the copper surface from the underlying substrate, so that the adhesion characteristics of the copper surface are substantially increased for receiving and securely adhering a subsequently applied coating.

Abstract: Disclosed herein is a process for preparing the surfaces of through-holes in printed circuit boards (especially multilayer printed circuit boards) for subsequent metallization, in which the through-hole surfaces are treated with a substantially water-immiscible organic liquid which acts upon the insulating substrate of the board, and preferably in the form of a substantially homogeneous, clear mixture comprised of the water-immiscible organic liquid, water, an alkali metal compound and a surfactant component, followed by treatment of the through-hole surfaces with an alkaline permanganate solution. The process can be used as a desmearing and/or etch-back process, a combined desmearing-conditioning process, or a conditioning process following a separate desmearing process.

Abstract: Non-conductive surfaces, particularly through-hole surfaces in double-sided or multi-layer printed circuit board, are treated (conditioned) to receive void-free, adherent electroless metal coatings by contact of the surfaces with an organosilane preparatory to catalyzation and metallization.

Abstract: Non-adherent copper metal particles ("fines") formed in a plating bath during the course of autocatalytic electroless copper deposition onto activated substrate surfaces are oxidized and redissolved in the bath by brief application of current between an anode element and a cathode element immersed in the bath, the anode element being comprised of an anode surface substantially parallel and proximate to the bottom surface of the vessel containing the bath.

Abstract: Printed circuit boards containing thru-holes requiring metallization are manufactured by first applying to the board material an alkaline strippable resist in a predetermined desired pattern, thereafter applying material catalytic to subsequent metallization, thereafter treating the board with an aqueous alkaline solution to remove catalytic material from resist surfaces without adversely affecting the catalyst at non-resist areas, and then metallizing the non-resist areas. The ability to preliminarily apply the resist pattern before catalyst application, metallization, etc., yet prevent metallization of the resist, enables the manufacturing process to proceed straight through the activation, metallization, etc. steps without need for interruption for resist application.

Abstract: A composition for stripping tin, lead or solder, as well as any underlying copper-tin alloy, from copper surfaces, containing an alkane sulfonic acid, preferably methane sulfonic acid, an inorganic nitrate, preferably ferric nitrate, and an inhibitor component. The composition effects rapid stripping without any appreciable formation of sludge or precipitate or suspended particles, and without any substantial attack on the underlying copper surface.

Abstract: The thru-holes of a multilayer printed circuit board, comprised of a laminate of epoxy resin and metal innerlayers, are provided with a conductive metal coating by a process in which the holes are first subjected to a desmearing process to remove smear from the copper innerlayers, followed by treatment of the hole surfaces with a solvent for the resin, treatment of the hole surfaces with a highly alkaline permanganate solution, and deposition of a conductive metal layer on the hole surfaces.

Abstract: A method of preparing printed circuit boards is described in which the solder mask on the circuit pattern and, optionally, the solder on the through-holes surrounding pads, and like areas to receive solder, is applied over a layer of lead covering the copper layer at said loci. This method eliminates the need to strip tin-lead alloy etch resist which step is commonly employed in prior processes. The method overcomes the problems associated with migration of tin into the copper layer which can occur when tin-lead alloys are applied directly over copper.

Abstract: A method of electroless deposition of metal on a non-conductive substrate is disclosed and comprises treating a substrate prior to electroless deposition with a catalyst composition containing a mixed tin-palladium catalyst. An improvement in metal deposition is obtained by contacting the treated substrate with an alkaline accelerator bath containing an agent which oxidizes the tin.

Abstract: The thru-holes of a multilayer printed circuit board, comprised of a laminate of epoxy resin and metal innerlayers, are provided with a conductive metal coating by a process in which the holes are first subjected to a desmearing process to remove smear from the copper innerlayers, followed by treatment of the hole surfaces with a solvent for the resin, treatment of the hole surfaces with a highly alkaline permanganate solution, and deposition of a conductive metal layer on the hole surfaces.

Abstract: A method of continuously depositing a metallic plating on the surface of a workpiece from a non-autocatalytic electroless plating bath that is normally inherently self-limiting as to the thickness of metal which can be deposited by electrolessly plating by applying an electric potential on the workpiece in the electroless bath. The method provides non-autocatalytic baths, such as hypophosphite-reduced electroless copper baths, with the ability to plate on nonconductors to a desired thickness which increases with time at a rate dependent on the amount of current applied. A more uniform thickness of deposit over the workpiece being plated and greater deposit penetration into blind holes, deep recesses and tubular portions of complex-shaped parts is obtainable by the method.

Abstract: Electroless copper deposition solutions, and method of electrolessly depositing copper onto a workpiece using these solutions, are disclosed. The solutions contain, in addition to water as the usual solvent, a soluble source of copper ions, a complexing agent or mixture of agents to maintain the copper in solution, and a copper reducing agent effective to reduce the copper ions to metallic copper as a deposit or plating on a prepared surface of a workpiece brought into contact with the solution.

Abstract: Electroless copper deposition solutions, and method of continuously electrolessly depositing copper onto a workpiece using these solutions, are disclosed. The solutions contain, in addition to water as the usual solvent, a soluble source of copper ions, a complexing agent or mixture of agents to maintain the copper in solution, a non-formaldehyde copper reducing agent, such as hypophosphite, effective to reduce the copper ions to metallic copper as a deposit or plating on a prepared surface of a workpiece brought into contact with the solution, and a soluble source of non-copper metallic ions, such as nickel or cobalt ions, which act as an autocatalysis promoter to enable continuous plating using the solutions. The solutions are maintained in an alkaline condition and preferably in a pH range of 11-14 through the addition of pH adjusters.

Abstract: Electroless copper deposition solutions, and method of electrolessly depositing copper onto a workpiece using these solutions, are disclosed. The solutions contain, in addition to water as the usual solvent, a soluble source of copper ions, a complexing agent or mixture of agents to maintain the copper in solution, and a copper reducing agent effective to reduce the copper ions to metallic copper as a deposit or plating on a prepared surface of a workpiece brought into contact with the solution.

Abstract: Circuit boards for electronic equipment are produced in which the circuit-forming conductor metal is deposited on a suitably catalyzed and masked resin substrate by all-electroless deposition techniques, wherein the characterizing feature of the invention is the use of a separate acceleration step after catalyzing and prior to application of a resist mask, supplementary of the usual post-masking accelerating step. Improved surface resistivity or insulation resistance in the printed circuit board and improved adhesion of the electrolessly deposited metal are achieved.

Abstract: Circuit boards for electronic equipment are produced in which the circuit-forming conductor metal is deposited on a suitably catalyzed and masked resin substrate by an all-additive electroless deposition technique, in which the characterizing feature is the use of a two-stage metal deposition to build up the desired total thickness of metal. In the first stage a fine grained, thin deposit of metal is produced on the substrate which is then water rinsed and immersed in a second metal bath having a sufficiently high rate of deposition to produce the desired total thickness of metal in a commercially practical period of time. Improved adhesion of plated metal to the resin substrate, both before and after thermal shock, is achieved by resort to this two-stage plating procedure.