Abstract: A method of improved control of recycle of ammoniacal copper etchant which uses metallic aluminum to remove copper without substantially adding undesirable byproducts. The very rapid reaction can be controlled by using a diluent of copper-free etchant, eliminating overheating. The separated copper and aluminum hydroxide sludge are easily filtered from the etchant. The purified etchant is now suitable for chemical adjustment and reuse.

Abstract: An electroless gold plating solution comprising a gold(I) complex, a thiosulfate, a sulfite, a pH regulator and an oxidation controller. The electroless gold plating solution uses a novel reducing agent system, the thiosulfate-sulfite-sulfate system. It shows a plating rate and a plating solution stability comparable to those of conventional gold plating solutions containing borohydride, thiourea, hydrazine, and other reducing agents.

Abstract: This invention relates to electroless nickel plating of metals which are normally noncatalytic for electroless nickel initiation. It is especially useful in the electronics industry, such as for production of electroless nickel/electroless gold tabs or surface mount pads on printed circuit boards, and for use in electroless nickel plating over copper for radiofrequency interference shielding. More particularly, it comprises ammonium halide salt solutions of a palladium salt with another Group VIII precious metal salt and acid and optionally an alkali halide salt for effectively and completely catalyzing the initiation of electroless nickel plating on copper substrates.

Abstract: An improved method for rapidly stripping solder or tin from a substrate, such as copper, without adversely affecting the substrate. This is especially useful in the preparation of printed circuit boards. The composition comprises an acidic solution of an iron salt, a nitrate, at least one complexing agent such as gluconate, citrate, or EDTA, and at least one acid source. The acid source can comprise any mixture of compatible mineral and organic acids in any combination. The organic acids can include soluble aliphatic, substituted aliphatic, aromatic, or mixed acids. The mixture should be substantially free of halides and sulfates. This highly stable, rapid stripping rate formulation gives no attack on exposed glass fibers or epoxy printed circuit laminate material. It can operate over a wide temperature range without needing close temperature control.

Abstract: This invention relates to electroless nickel plating of metals which are normally noncatalytic for electroless nickel initiation. It is especially useful in the electronics industry, including production of electroless nickel/electroless gold tabs or surface mount pads on printed circuit boards, and for use in electroless nickel plating over copper for radiofrequency interference shielding. More particularly, it comprises alkali halide salt solutions of a palladium salt with another Group VIII precious metal salt in an inorganic acid solution for effectively and completely catalyzing the initiation of electroless nickel plating on copper substrates.