Abstract: A process used during manufacture of printed circuit boards comprises protecting metal pads and/or through-holes to provide a tarnish-resistant and solderable coating. In the method, the pads and/or through-holes are bright-etched, metal plated, preferably by an immersion process, and treated with a tarnish inhibitor. The tarnish inhibitor may be incorporated into the immersion plating bath. The metal plating is usually with silver or bismuth and the pads and/or through-holes comprise copper.

Abstract: A method for producing extremely smooth metal coatings on zincated aluminum substrates using a special double zincating procedure and/or a specially formulated electroless metal plating bath employing a unique plating process.

Abstract: A method and apparatus is provided for applying liquid coatings such as solder masks sequentially to both sides of a printed circuit board substrate whereby only one drying operation would be needed to dry the liquid coatings. An isolation platen having openings corresponding to the coated parts of the board is used to provide a space between the coated part and the opposite side of the platen.

Abstract: A method for waste treating metal containing solutions comprising decomposing the metal from the solution in the substantial absence of air and separating the decomposed (precipitated) metal from the solution.

Abstract: The permanganate process for treating plastics, e.g., printed circuit boards, to enhance the adhesion of metal plating to the plastic is improved by employing electrolysis to either maintain a certain permanganate level in the operating bath or to regenerate a spent or used bath.

Abstract: A process is provided for improving the electroless nickel plating of aluminum which has been pretreated with a barrier coating such as zinc by employing multiple plating baths under controlled operating conditions.

Abstract: Process for the plating of through-holes in an epoxy printed circuit board base material in the manufacture of printed circuit boards. The treatment process is designed to increase adhesion between the epoxy board material and a subsequently deposited metal plate. The process is characterized, in part, by the use of an activated permanganate solution.

Abstract: A process for specially conditioning and etching a polycarbonate resin prior to metal plating to enhance the coverage and adhesiveness of metal plating to the resin. The swellant composition comprises a compound represented by the general formula,R.sub.1 (OC.sub.n H.sub.2n).sub.m O--R.sub.2wherein R.sub.1 and R.sub.2 are independently selected from the group consisting of aryl groups and alkyl groups of 1-4 carbon atoms, n is 2 to 4 and m is 1 to 5.The swelled resin is then etched using, preferably, a highly alkaline composition such as a solution containing greater than about 100 g/l NaOH. Other etchants such as chromic acid may also be used.The resin is now ready for plating using conventional techniques.

Abstract: Acidic stripping solutions comprising hydrogen peroxide as oxidant, either at least one phosphorous-oxy acid, or the addition of nitric acid, together with accelerators and surface active agents, are effective for the rapid and selective removal of protective hard surface coatings and nickel-base brazes from a variety of metal surfaces.

Abstract: A composition and process is disclosed for improving the leach resistance of the copper oxide coating on the copper circuitry of printed circuit boards to solutions used in their preparation which comprises contacting the copper oxide of the circuit board with a solution containing an amphoteric element which forms an acidic oxide, such as selenium dioxide.

Abstract: A method for the regeneration of a spent aqueous ammonium bifluoride-hydrogen peroxide solder stripping solution containing contaminant tin ions comprising adding potassium ions to the solution to precipitate a filterable tin-potassium compound.

Abstract: An RFI shielded enclosure and a process for making same are disclosed. The process comprises coating at least one surface of the enclosure with a fluid organic binder having a substantial percentage of catalytic particles suspended therein. The particles used cause the electroless deposition of copper or nickel to produce an RFI shielded enclosure having in excess of 40 dB's shielding at frequencies above 10 kiloHertz.

Abstract: An improved alkaline permanganate composition for etching printed circuit boards is provided by incorporating a secondary oxidant in the solution capable of oxidizing manganate ion to permanganate ion.

Abstract: Acidic stripping solutions comprising hydrogen peroxide as oxidant, either at least one phosphorous-oxy acid, or the addition of nitric acid, together with accelerators and surface active agents, are effective for the rapid and selective removal of protective hard surface coatings and nickel-base brazes from a variety of metal surfaces.

Abstract: A method for the recovery and reuse of an expensive palladium-tin catalyst whereby alkali hydroxide or carbonate is added to the exhausted catalytic solution and/or the spent rinse water solution to precipitate out a catalyst residue, which is then filtered, collected, washed, and dissolved in a hydrohalide acid and adjusted to a predetermined concentration.

Abstract: An improved alkaline permanganate composition for etching printed circuit boards is provided by incorporating a secondary oxidant in the solution capable of oxidizing manganate ion to permanganate ion.

Abstract: A process is provided for improving the electroless nickel plating of aluminum which has been pretreated with a barrier coating such as zinc by employing multiple plating baths under controlled operating conditions.

Abstract: Stripping solutions comprising hydrogen peroxide and sulfamic acid in correlated amounts are effective for the rapid and selective removal of nickel from mild steel surfaces and nickel, nickel alloy and nickel reaction products from alloy substrates. The compositions contain sulfamate, nitrate and chloride and peroxide ions and, preferably, an iron complexing agent such as ethylene diamine tetraacetic acid.

Abstract: Aqueous, acid zinc electroplating solutions and method for electroplating zinc coatings are provided. The plating solutions of the invention contain a source of zinc ions, an electrolyte, at least one organic acid or salt thereof, and a novel grain-refining agent comprising a substituted polyhydric alcohol having three or more ethoxylated and/or propoxylated hydroxyl groups. Bright and lustrous zinc coatings can be electroplated from such solutions at temperatures ranging from between about 50.degree. to 100.degree. F., with the plating solutions exhibiting no significant cloud point.

Abstract: An improved process for dissolution of metals by etching, and particularly the etching of copper in printed circuit board processing or the like, using an aqueous H.sub.2 O.sub.2 --H.sub.2 SO.sub.4 etching solution, in which the concentration of H.sub.2 SO.sub.4 in the etching solution is allowed to decrease during use of the etching solution from an initial, relatively high level at the time the etching solution is put into use, to a final, relatively low level. When a predetermined concentration of dissolved etched metal exists in the etching solution, the etching solution is removed from use, H.sub.2 SO.sub.4 is added to increase the concentration of H.sub.2 SO.sub.4 in the etching solution to approximately the initial, relatively high level, and the metal is precipitated out of the etching solution.