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Publication numberUS2243429 A
Publication typeGrant
Publication dateMay 27, 1941
Filing dateJan 11, 1938
Priority dateJan 13, 1937
Publication numberUS 2243429 A, US 2243429A, US-A-2243429, US2243429 A, US2243429A
InventorsRudolf Laux
Original AssigneeLangbein Pfanhauser Werke Ag
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electroplating of nonconductive surfaces
US 2243429 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

this is brought about Patented May l'2' 7, 1941 ELECTROPLATING F NONCONDUCTI-VE SURFACES Rudolf Laux, Leipzig, Germany, assignor to Langbein Pfanhauser Leipzig, Germany N 0 Drawing.

rial No.

Claims.

Various processes are known for producing metal coatings electrolytically on objects of insulating material or on objects with a nonconducting surface. For carrying out such electroplating processes, the insulating surface of the object must first be made conductive, e. g. by graphiting or by depositing an exceedingly thin Werke Aktiengesellschaft,

Application January 11, 1938, Se- 184,392. In Germany January 13,

metal coating (metal mirror) from a reducible metal salt solution. on to this first conductive surface coating, a copper layer is then usually first electrolytically deposited from alkali cyanide or acid copper galvanoplastic baths, and finally a further electrolytic deposit of another metal is produced.

The present invention refers particularly to those processes in which the first conductive surface coating on the object consists of an exceedingly thin metal coating, e. g. a silver mirror or a copper mirror which is deposited from a corresponding metallic salt solution by chemical v reduction. It has been proved that, when the object is suspended in those galvanic baths which usually serve for the electrolytic separation of copper, namely acid galvanoplastic copper baths or also alkali cyanide copper baths, an exceedingly thin metal coating of this kind is attacked by these baths in a manner which causes solution, so that considerable wastage occurs because the galvanoplastic copper deposits then turn out irregular or incomplete.

The purpose of th invention is to remove these drawbacks. According'to the invention, owing to the fact that the object, which is provided for instance with a silver mirror, is treated cathodically for some time in an aqueous copper sulphate solution before suspension in one of the usual galvanic copper baths, the pH value of the copper. sulphate solution amounting to about 3.4 to 1.8. This corresponds to aqueous solutions of copper sulphate which contain only up to about 2.5 gms. of free sulphuric acid per litre. In so doing, the concentration of the copper sulphate preferably amounts to only about 40 to 100 gms. per litre. In baths of .this kind, a satisfactory electrolytic coppering of the exceedingly thin metal surface is obtained without risk of its partial solution 'or injury in any other manner during suspension. Objects with an exceedingly thin silver layer can even be suspended in the copper sulphate solution for several hours without current.

After the metal surface is well covered with copper in the copper bath constructed according to the invention, the further thickening of the copper deposit can be effected in one of the usual galvanic copper baths, for instance in one of the acid copper baths, usual in galvanoplastics, containing about 200 to 300 gms. of copper sulphate and about 15 to 40 gms. of free'sulphuric acid per litre and of which the pH value amounts to about 1.1 to0.9.

I claim:

1. Process for .the production of a conductive coating on an object having a nonconductive surface, which comprises reducing a solution of a copper salt while in contact with said surface, thereby producing a thin copper deposit thereon, then electrolytically depositing further copper on said copper deposit from solution containing copper sulphate and some free sulphuric acid and having a pH value of from about 3.4 to about 1.8, and finally building up the copper coating by electrolytic deposition from a solution containing a higher concentration of copper sulphate and of free acid than said last mentioned solution.

2. Process for the production of a conductive coating on an object having a nonconductive surface, which comprises providing a thin metal deposit on said surface and then electrolytically depositing copper on said metal deposit from an aqueous solution containing copper sulphate and some free sulphuric acid and having a pH value from about 3.4 .-to about 1.8 and.finally building up the copper coating by electrolytic deposition from a solution containing about 200 grams to about 300 grams of copper sulphate and about 15 grams to about 40 grams of free sulphuric acid per litre.

3. Process for the electrolytic production of'a metal coating on an object having a noncondu'ctive surface which comprises providing a thin metal deposit on said surface, then electrolytically depositing copper on said metal deposit from an aqueous solution containing copper sulphate and some free sulphuric acid and having a pH value of from about 3.4 to about 1.8, and finally electrolytically depositing metal on the copper coating, from a solution containing a higher confrom an aqueous centration of metal salt and of free acid than said last-mentioned solution.

4. Process for the electrolytic production of a metal coating on an object having a nonconductive surface which comprises providing a thin silver deposit on said surface and then electrolytically depositing copper on said silver deposit solution containing copper sulphate and some free sulphuric acid and having a pH value of from about 3.4 to about 1.8 and finally depositing metal on the copper coating tion of a salt 01 a metal while in contact with p said surface thereby producing a thin metal deposit thereon then electrolytically depositing copper on said metal deposit from an aqueous solution conteiningcoppcr sulphate and some free sulphuric acid and having a pH value of irom about 3.4 to about 1.8 and. finally electrolytically depositing metal on said copper coating, from a solution containing a higher concentration of metal salt and of free acid than said last-mentioned solution. v

RUDOLF LAUX.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4619741 *Nov 29, 1985Oct 28, 1986Olin Hunt Specialty Products Inc.Process for preparing a non-conductive substrate for electroplating
US4622107 *May 5, 1986Nov 11, 1986Olin Hunt Specialty Products Inc.Process for preparing the through hole walls of a printed wiring board for electroplating
US4622108 *May 5, 1986Nov 11, 1986Olin Hunt Specialty Products, Inc.Process for preparing the through hole walls of a printed wiring board for electroplating
US4631117 *May 5, 1986Dec 23, 1986Olin Hunt Specialty Products Inc.Electroless plating process
US4684560 *May 1, 1986Aug 4, 1987Olin Hunt Specialty Products, Inc.Printed wiring board having carbon black-coated through holes
US4718993 *May 29, 1987Jan 12, 1988Olin Hunt Specialty Products Inc.Process for preparing the through hole walls of a printed wiring board for electroplating
US4724005 *May 1, 1986Feb 9, 1988Olin Hunt Specialty Products Inc.Liquid carbon black dispersion
US4964959 *Apr 12, 1990Oct 23, 1990Olin Hunt Specialty Products Inc.Process for preparing a nonconductive substrate for electroplating
US4969979 *May 8, 1989Nov 13, 1990International Business Machines CorporationDirect electroplating of through holes
US4994153 *Jun 28, 1990Feb 19, 1991Olin CorporationProcess for preparing nonconductive substrates
US5106537 *Jul 23, 1990Apr 21, 1992Olin Hunt Sub Iii Corp.Liquid dispersion for enhancing the electroplating of a non-conductive surface
US5139642 *Aug 19, 1991Aug 18, 1992Olin CorporationProcess for preparing a nonconductive substrate for electroplating
US5476580 *May 3, 1994Dec 19, 1995Electrochemicals Inc.Processes for preparing a non-conductive substrate for electroplating
US5674372 *Sep 24, 1996Oct 7, 1997Mac Dermid, IncorporatedProcess for preparing a non-conductive substrate for electroplating
US5690805 *Jun 7, 1995Nov 25, 1997Electrochemicals Inc.Direct metallization process
US5725807 *Jun 7, 1995Mar 10, 1998Electrochemicals Inc.Carbon containing composition for electroplating
US6171468Nov 21, 1997Jan 9, 2001Electrochemicals Inc.Direct metallization process
US6303181Mar 17, 2000Oct 16, 2001Electrochemicals Inc.Direct metallization process employing a cationic conditioner and a binder
US6710259Sep 17, 2001Mar 23, 2004Electrochemicals, Inc.Printed wiring boards and methods for making them
US20040084321 *Dec 5, 2003May 6, 2004Thorn Charles EdwinPrinted wiring boards and methods for making them
USRE37765Feb 22, 1999Jun 25, 2002Macdermid, IncorporatedProcess for preparing a nonconductive substrate for electroplating
Classifications
U.S. Classification205/159, 205/182, 205/291
International ClassificationC25D5/54, H05K3/18
Cooperative ClassificationH05K3/188, C25D5/54
European ClassificationH05K3/18C, C25D5/54