Kernforschungsanlage Julich Gesellschaft MIT Beschrankter Haftung

Kernforschungsanlage Julich

Elo-chem Atztechnik Gmbh

Wolfgang Faul

Bertel Kastening

Leander Furst

Walter Holzer

Jiri Divisek

Heiko Barnert

Harald Luft

Ammoniacal etching solution containing metal ions as the result of etching is withdrawn from an etching bath and while part of it goes to an electrolysis cell for removal of metal ion, the remainder goes back to the etching bath through a liquid jet pump in which it serves as the working liquid, while the pump sucks in from the electrolysis cell the anodically evolved oxygen. The thorough mixing of the oxygen into the etching solution performed by the pump results in oxidation so rapid that in many cases it becomes unnecessary to suspend catalyst particles in the electrolyte to accelerate the oxidative regeneration of the etching solution. Where use of such particles is still desired, the solution drawn from the etching bath goes through a cylindrical filter unit from which a filtrate is drawn off laterally for the electrolysis cell, while the remainder of the input goes to the jet pump. Controls are provided for using the electrolysis cell only when the metal ion concentration is above a predetermined value, for adding ammonia to the oxygen line in order to maintain a particular value of pH and for controlling the temperature of the electrolyte in the electrolysis cell in order that a desired quantity of water can be condensed from the oxygen line for use in rinsing the work pieces after they are taken out of the etching bath.

Method and apparatus for regenerating an ammoniacal etching solution

A plate or hollow cylinder of coarsely porous graphite is coated with a layer of finely porous activated carbon that has previously been heat-treated. The fine layer is impregnated with a catalyst either before or after application to the graphite body. A gas is caused to flow through the graphite body and out through the finely porous layer containing the catalyst, to react with substances in a solution in which the carrier body is immersed. For oxidation, air can be used, and for reduction, hydrogen. In this manner, sulfite can be oxidized or chromate reduced and hydrogen gas can also be used to precipitate platinum, rhodium, copper and other metals from solution. Electro-chemical activation or regeneration of the catalyst is possible by applying a potential to the carrier body. The reaction can be carried on in solutions in which solids are suspended without clogging the catalyst.

Apparatus for oxidation or reduction process in water solution with

In addition to catalyzing the reoxidization of spent alkaline etching age the suspension of activated carbon powder in the etching solution also increases the speed of etching when the etching solution is recirculated in the etching of printed circuit boards. The ammonium sulfate etching solution is set to a pH of about 9 by the addition of ammonia gas. In the recirculation of the etching solution, a part of the solution can be freed by filtration from suspended carbon particles and passed through the cathode and anode chambers of an electrolysis cell for the recovery of the etched metal by deposition on the cathode. The activated carbon powder for this purpose is calcined before use, at a temperature of between 900.degree. and 1200.degree. C. in vacuum or in an atmosphere that is inert, reducing, or only slightly oxidizing as in the case of an atmosphere containing carbon dioxide, water vapor or both, in a concentration that does not appreciably oxidize the carbon particles.

Method of regenerating an ammoniacal etching solution

Method and apparatus for regenerating etching solutions obtained by chemily processing metallic surfaces, which solutions contain cupric chloride and/or ferric chloride. The apparatus includes between the anode and the cathode a diaphragm or an ion exchange membrane. The etching solution is passed through the electrolysis cell for anodic oxidation of the cuprous and/or ferrous ions obtained by etching of the metallic surface of a workpiece. An effective quantity of activated pulverous carbon particles is suspended at least in the anode compartment of the electrolysis cell, which cell is in communication with an etching chamber in such a way so as to allow circulating flow of solution.

Method for regenerating a cupric chloride and/or ferric chloride

Method of etching of surfaces of copper or copper alloys by way of an aci solution containing an oxidizing agent. After removal of the copper surface, the etching solution is passed for regeneration of the oxidizing agent through an electrolysis cell having an anode and a cathode, with copper being deposited on the cathode. The etching solution is maintained free of chloride ions and contains as the oxidizing agent ferric sulfate in a concentration of up to about 140 g of Fe/1 etching solution, whereby the copper content of the etching solution is adjusted to at least 10 g Cu per liter etching solution, while the current density in the electrolysis cell is maintained at at least 2A/dm.sup.2.

Method of processing the surface of workpieces including particularly

Method of electrochemically processing metallic surfaces of workpieces wh are arranged in an electrolyte of an electrolysis cell in such a way that the workpiece does not contact the anode and the cathode, with pulverous particles of one of the group consisting of graphite and activated carbon being suspended in the electrolyte, with the pulverous particles being charged on the anode for transfer of an electric charge to the workpiece. The pulverous particles are shielded by a diaphragm or an ion exchange membrane so that the charged pulverous particles cannot discharge at the cathode. In the electrolyte there is dissolved one of the group consisting of a V.sup.+5 compound and a vanadium-containing compound adapted to form V.sup.+5 ions at the anode of the electrolysis cell.

Method of electrochemically processing metallic surfaces of workpieces

A method of generating oxygen and hydrogen from water in which an acidic electrolyte containing formaldehyde is electrolyzed and produces oxygen and a gas which contains a low molecular-weight hydrocarbon. The low molecular-weight hydrocarbon is subjected to a catalytic conversion with water to produce synthesis gas consisting predominantly of hydrogen and carbon monoxide which are reacted to yield methanol. The methanol, in turn, is reacted to produce formaldehyde which is introduced into the electrolysis itself and hydrogen which is recovered.

Method of generating hydrogen and oxygen from water

Reducible pollutants can be detoxified by reduction and metals can be recred by reduction of the corresponding metal ions by bringing into contact a catalyst with the solution which is suitable for the electrochemical reduction of the ions in question, and mixing into the solution (or bubbling therethrough in the case of a gas) a reducing agent that has a redox potential in the redox system of the reducing agent and its oxidation product that is more negative than the redox potential of the substance to be reduced and its reduction product. The catalyst is a material that is suitable for use as an anode material at which hydrogen can be oxidized in a fuel cell. Such catalysts include finely divided platinum, activated carbon coated with platinum, tungsten carbide and activated carbon coated with tungsten carbide, particularly. Hydrogen is a good reducing agent for the purpose.

Process for the catalytic reduction of reducible compounds in solution

An electrolytic cell which between the anode and cathode includes a diaphm dividing the electrolytic cell into two chambers. In one of these chambers there is provided an electrolyte which contains the suspension of electrically conductive bodies. The apparatus includes a treatment chamber for workpieces to be arranged in a contact-free manner with regard to the cathode and anode. A conveying line for the electrolyte containing the electrically conductive bodies extends between on one hand that chamber of the electrolytic cell in which the electrode charging the electrically conductive bodies is arranged, and on the other hand the treatment chamber. One portion of said conveying line outside the electrolytic cell includes a porous wall which is permeable for the electrolyte but retains electrically conductive bodies. The annular chamber formed by a surrounding outer pipe and porous wall which surrounds the conveying line communicates with the chamber containing the counter-electrode in the electrolytic cell for exchanging electrolyte.

Apparatus for electrochemically processing metallic surfaces

An electrode especially adapted for the electrolytic production of hydrogen peroxide is made by heating activated carbon powder to a temperature above 900.degree. C. and mixing it with a binder and a hydrophobic additive, an electrically conductive network being embedded in the mixture. According to the invention, the activated carbon is heated to incandescence in a hydrogen atmosphere.

Process for producing an electrode for use in the electrolytic

A method of electrochemically processing metallic surfaces of workpieces ch are arranged so as not to contact the cathode and anode. The processing is done with an electrolyte which, for conducting an electric charge to the surface to be processed, contains electrically conductive bodies suspended in the electrolyte. The electrically conductive bodies, in an electrolysis cell, are charged on the electrode intended for processing the surface and are protected against discharging on the counterelectrode of the electrolysis cell by a diaphragm which shields the counterelectrode. As electrically conductive bodies, particles of activated carbon powder heated at above 700.degree. C in an inert atmosphere are suspended in the electrolyte.

Method of electrochemically processing metallic surfaces

Method of and apparatus for processing the surface of bodies, especially of lectrically non-conductive material. A body is brought into contact with an electrolyte liquid, e.g. by immersing the body; simultaneously the surface to be processed contacting by means of electric conductors continuously or temporarily a portion only of the surface to be processed in contact with an electrode of dimensions corresponding to the surface to be processed.

Method of and apparatus for processing the surface of bodies

A method of making an electrode for preparing hydrogen peroxide, according o which active carbon during application of heat is mixed with a binder and a hydrophobic substance of addition. The thus obtained mixture is applied to an electrically conductive carrier structure. More specifically, active carbon is glowed in a vacuum at a temperature above 900.degree., preferably at a temperature of from 1000.degree. to 1250.degree.C. After the active carbon powder has been cooled in a vacuum, the active carbon powder is mixed with a solvent containing the binder and the hydrophobic substance of addition. The thus obtained mixture is applied to the electric conductive carrier substance. Finally, the mixture thus applied to the carrier structure is dried. The thus produced electrode is arranged in an electrolytic cell filled with an electrolyte. This cell comprises a gas permeable carbon cathode communicating with a gas chamber in which a pressure higher than atmospheric pressure prevails and also comprises an anode separated from the carbon cathode by a diaphragm. As carbon electrode there is used a carrier structure coated with active carbon powder which by means of a non-coated side facing away from the gas chamber rests on a metallic grate.

Growing community of inventors

Julich, Germany

Wolfgang Faul