Abstract: A process for control of recycle of ammoniacal copper etchant which uses metallic aluminum to remove copper without substantially adding undesirable byproducts, by controlling the temperature and mixture rate of the removal process. The very rapid reaction can be controlled by using a diluent of copper-free etchant, heating to process temperature, then adding spent, copper containing etchant at a controlled rate while actively cooling the system to control the temperature. The copper concentration can be monitored by colorimetry while maintaining the pH above pH 8. The separated metallic copper and aluminum hydroxide sludge are easily filtered from the etchant. The purified etchant is now suitable for chemical adjustment and reuse.

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: This invention relates to the removal of lead from spent ferric nitrate based solder strippers, the regeneration of the spent ferric nitrate based solder strippers, and the reuse of these solutions at least one time. It comprises a method and process for precipitating lead salts from used acidic solder strippers which are employed to strip solder coatings, including the underlying tin-copper alloy, from the copper substrate of a printed circuit board. The method includes the use of sulfate ions which are directly added to an aqueous solution of spent solder stripper, without neutralization of the spent solder stripper, optionally in combination with nitric or methylsulfonic acid addition. After precipitation and removal of the lead salts, additional components of the solder stripper composition may be added to substantially restore the initial functioning of the solder stripper.

Abstract: An electroless silver plating solution comprises a silver(I) complex, a thiosulfate salt, and a sulfite salt. This electroless silver plating solution uses a novel reducing agent combination of thiosulfate and sulfite. It shows a plating rate and a plating solution stability far superior to those of conventional silver plating solutions containing formaldehyde, reducing sugars, borohydride, hydrazine, and other reducing agents.

Abstract: An electroless silver or gold plating solution comprising a noncyanide metal complex, a thiosulfate, a sulfite, and at least one amino acid. These electroless plating solutions containing an amino acid exhibit an accelerated plating rate compared to identical solutions lacking amino acids.

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: 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, 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: 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.