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Publication numberUS2742413 A
Publication typeGrant
Publication dateApr 17, 1956
Filing dateApr 13, 1953
Priority dateJul 5, 1952
Also published asDE940860C, DE962129C, US2742412
Publication numberUS 2742413 A, US 2742413A, US-A-2742413, US2742413 A, US2742413A
InventorsOosterhout Hendricus Andreas V, Rolf Cransberg
Original AssigneeMetallic Industry Nv
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Bright copper plating bath
US 2742413 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Unitedtsratesfi Patent Claims priority, application Netherlands July5j1952 9 Claims. (ClIZM -SZ) The electrolytic deposition of copper is an operation. whichds appliedv very frequently.- in the. metal industry and is carried out either to embellish the surface of the treatedwbjects or to increase the corrosion resistance thereof," while the electro-de'posited" copper als'o serves as a base for a further treatment such-as the electrolytic depositionof nickel. ln'pra'ctice hig'hdemands are made on the appearance of the treated objects'so' that theseup" till now had to be ground and polished in an earlier-or later stageofthe'treatment which entails a number of operations, of whiehithe cost connect'ed therewith form a greatpart of the total cost of the surface:treatment,.theelectrolytic deposition of copper formsa-part of I Mdstelectfolyti'ci baths have the property that they do not fill up unevennesses in -the' metalsurface such as scratches and-the like but rather accentuate them, .and especially the baths for the electro-deposition of bright metal layers, from which a very fine crystalline metal deposit is precipitated, have the property that they, besides covering the uneven metal surface with a bright metal layer, also cover the unevennesses only with a thin layer, due to which the latter, although lustrous, remain visible in an undiminished degree.

It has now been found that the acid copper bath in so far makes a favorable exception on the baths, that it has some filling action, in other words, partially fills up gaps, pits and other unevennesses in the surface so that one aimed at improving the filling action of the copper bath, while maintaining other favorable properties such as the capacity to deposit a soft coating on the metal, etc.

It has been proposed to meet the above-described need by adding an organic substance to the copper bath. It is known e. g. from the U. S. P. 1,903,860 to add thiourea or a water-soluble derivative of thiourea, such as methylthiourea, to metal baths. It has been found, however, that the copper coating which is precipitated from the copper baths thus prepared, is very hard, so that it easily springs off on bending and moreover has a very small lustrous range which is considered as a very serious drawback of these baths. Moreover, the action of a copper bath containing exclusively thiourea as an organic compound decreases very soon. 7

It has now been found that a soft copper layer is obtained if the combination of thiourea or a water-soluble derivative of thiourea and a water-soluble heterocyclic nitrogen compound is added to an acid copper bath. The bath thus prepared displays moreover an excellent filling capacity and has a wide lustrous range.

According to the invention objects, particularly metal objects, are electrolytically provided with a copper deposit with the aid of an acid bath by using a bath con taining the combination of a water-soluble derivative of thiourea and a water-soluble heterocyclic nitrogen compound.

The invention extends to the preparation of an acid copper bath containing the combination of thiourea or a added tothe-bath in combination with the heterocyclic nitrogen compounds allyl thiourea is preferred as well" I 2,742,413 Patented Apr. 17,1956

water-soluble "derivative of thiourea and a water-soluble heterocyclic"nitrogencompound, as well'as to objects electrolyticallyprovided with a copper layer with the aidbf are bath:

Of themvatensoluble hetero'cyclic nitrogen compounds which are*used'in combinatiomwith thiourea or a watersoluble iderivative' of thiourea in theacid copper bath,

compoundsioflthe :xanthine group, particularly-the methyl 1 nonro1ogues'; --sueh as caffeine (l,3;7-trimethylxanthine),-

theophyllirie (1,3-dimethylxanthine) and" theobromine (3,f7-'dimethy1xanthine) are preferred," as well as hexa-=- methylene itetr'ami'ne; morpholine' and pyridine; as well as the ring systems, containing the pyridine nucleus,-=such as quinoline.

Of the'water-soluble thiourea derivatives -which are as acetylthiourea, ,while the thiourea itself, possible;

still exceeds in activity, these two. above-mentioned thiourea derivatives.

The invention is elucidated by the followingsiexarnpleszi' I Example I V Am -"acid copper batha of the following composition was preparedt cuso s aq.... a.;-fi.. ==a..a..agr/l 200 HaSQt. g. /Lt... ,Thiourea g 10 Pyridine mg./l 40 This bath was brought at a temperature of 30 C. and was kept in motion by blowing in a current of air. The anode was of copper. As the cathode a 50 cm. long iron tube with a diameter of 3.5 cm. and a wall thickness of 2 mm. was connected after it having been subjected as a short pretreatment in a cyanidic copper bath to a socalled copper strike" in which a copper layer of very slight thickness was deposited on the outer wall and on a small part of the inner surface adjacent to the ends. The cathode current density of the main treatment in 1 the acid copper bath according to the invention was adjusted to 8 a./dm. and in 20 minutes 32; of copper was deposited on the tube. The copper layer was soft and lustrous, and the numerous unevennesses originally present on the surface of the tube, had substantially disappeared after the electro-deposition of the copper in the above-described bath.

' Example II An acid copper bath of the following composition was prepared: 7

015045 aq g./l. 250 H2804 ..g./l 2,0 Ammonium sulphate g./l 20 Acetyl thiourea mg./1 20 Caffeine rng./l 50 In this bath an iron plate of 4.5 x 25 dm. was provided with a copper layer at a bath temperature of 25 C. and

Example III An acid copper bath of the following composition was prepared:

Copper fiuoborate ..g./l 400 Fluoboric acid g./l 50 Thiourea mg./l 12 Hexamethylene tetramine mg./l 800 An acid copper bath of the following composition was prepared:

CuSO4.5 aq g./l 250 H2804 g./l 20 Ammonium sulphate g./l 20 Allyl thiourea mg./l 20 Morpholine mg./l 45 A number of small iron plates of 6 x 6 cm. (thickness 0.2 cm.) which had been ground with emery beforehand were provided with a copper layer during 40 minutes at 26 C. in the above-mentioned bath which was kept in motion with air. The cathode current density amounted to 6 a./dm. and the duration of the treatment was 35 minutes. The thickness of the layer was 4211.,

but it is more important that nothing could be seen anymore of the grinding scratches originally present.

What is claimed is:

1. A bright copper plating bath comprising copper sulfate, sulfuric acid, a brightener in proportion of 5 to mg. per liter of solution, said brightener being selected from the group consisting of thiourea, allylthiourea and acetylthiourea, and a filler selected from the group consisting of xanthine and its methyl homologues, hexamethylene tetramine, pyridine and morpholine.

2. A bath according to claim 1, wherein said brightener is thiourea.

3. A bath according to claim 1, wherein said brightener is allylthiourea.

4. A bath according to claim 1, wherein said brightener is acetylthiourea.

5. A bath according to claim 1, wherein said filler is xanthine.

6. A bath according to claim 1, caffeine.

7. A bath according to claim 1, theobromine.

8. A bath according to claim 1, theophylline.

9. A bath according to claim 1, hexamethylene tetramine.

wherein said filler is wherein said filler is wherein said filler is wherein said filler is References Cited in the file of this patent UNITED STATES PATENTS 2,391,289 Beaver Dec. 18, 1945 2,700,020 Pierce Jan. 18, 1955 FOREIGN PATENTS 461,186 Canada Nov. 22, 1949

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2391289 *Sep 15, 1941Dec 18, 1945Beaver Jr John FBright copper plating
US2700020 *Jun 2, 1952Jan 18, 1955Houdaille Hershey CorpPlating copper
CA461186A *Nov 22, 1949John Franklin Beaver JrBright copper plating
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3075899 *Apr 20, 1959Jan 29, 1963Dehydag GmbhBaths for the production of metal electroplates
US4009087 *Dec 24, 1975Feb 22, 1977M&T Chemicals Inc.Electrodeposition of copper
US6113771 *Jul 13, 1998Sep 5, 2000Applied Materials, Inc.Electro deposition chemistry
US6350366Jan 18, 2000Feb 26, 2002Applied Materials, Inc.Electro deposition chemistry
US6478937Jan 19, 2001Nov 12, 2002Applied Material, Inc.Substrate holder system with substrate extension apparatus and associated method
US6551484Jan 18, 2001Apr 22, 2003Applied Materials, Inc.Reverse voltage bias for electro-chemical plating system and method
US6571657Sep 18, 2000Jun 3, 2003Applied Materials Inc.Multiple blade robot adjustment apparatus and associated method
US6576110Feb 28, 2001Jun 10, 2003Applied Materials, Inc.Coated anode apparatus and associated method
US6610189Jan 3, 2001Aug 26, 2003Applied Materials, Inc.Method and associated apparatus to mechanically enhance the deposition of a metal film within a feature
US6610191Nov 13, 2001Aug 26, 2003Applied Materials, Inc.Electro deposition chemistry
US6808612May 10, 2001Oct 26, 2004Applied Materials, Inc.Method and apparatus to overcome anomalies in copper seed layers and to tune for feature size and aspect ratio
US6911136Apr 29, 2002Jun 28, 2005Applied Materials, Inc.Method for regulating the electrical power applied to a substrate during an immersion process
US6913680Jul 12, 2000Jul 5, 2005Applied Materials, Inc.Method of application of electrical biasing to enhance metal deposition
US20040200725 *Apr 9, 2003Oct 14, 2004Applied Materials Inc.Application of antifoaming agent to reduce defects in a semiconductor electrochemical plating process
US20040206628 *Apr 13, 2004Oct 21, 2004Applied Materials, Inc.Electrical bias during wafer exit from electrolyte bath
US20050092601 *Aug 26, 2004May 5, 2005Harald HerchenElectrochemical plating cell having a diffusion member
US20050092602 *Aug 26, 2004May 5, 2005Harald HerchenElectrochemical plating cell having a membrane stack
EP0952242A1 *Nov 16, 1998Oct 27, 1999Applied Materials, Inc.Electro deposition chemistry
Classifications
U.S. Classification205/296, 205/297, 205/298
International ClassificationC25D3/38
Cooperative ClassificationC25D3/38
European ClassificationC25D3/38