CA1053174A - Bath for the electrodeposition of gold - Google Patents
Bath for the electrodeposition of goldInfo
- Publication number
- CA1053174A CA1053174A CA235,878A CA235878A CA1053174A CA 1053174 A CA1053174 A CA 1053174A CA 235878 A CA235878 A CA 235878A CA 1053174 A CA1053174 A CA 1053174A
- Authority
- CA
- Canada
- Prior art keywords
- bath
- gold
- thiosulphate
- process according
- sodium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/48—Electroplating: Baths therefor from solutions of gold
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electroplating And Plating Baths Therefor (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A cyanide-free bath for the electrodeposition of gold includes a conductive salt such as the ammonium or alkali metal salt of an inorganic or weak organic acid, e.g., sulphuric, sulphurous, carbonic, boric, sulphamic, acetic or citric acid;
and gold in the form of a thiosulphato-complex in a concentration of 3 to 30 g/litre, the complex being sodium dithiosulphato-aurate (I) or sodium heptathiosulphato-aurate (I). The bath may also contain, as a reducing agent, an alkali metal nitrite or sulphite, and, as a buffer or pH regulator, sodium borate, potas-sium metabisulphite or a mixture of boric acid and ethylene glycol.
A cyanide-free bath for the electrodeposition of gold includes a conductive salt such as the ammonium or alkali metal salt of an inorganic or weak organic acid, e.g., sulphuric, sulphurous, carbonic, boric, sulphamic, acetic or citric acid;
and gold in the form of a thiosulphato-complex in a concentration of 3 to 30 g/litre, the complex being sodium dithiosulphato-aurate (I) or sodium heptathiosulphato-aurate (I). The bath may also contain, as a reducing agent, an alkali metal nitrite or sulphite, and, as a buffer or pH regulator, sodium borate, potas-sium metabisulphite or a mixture of boric acid and ethylene glycol.
Description
~135~
This invention xel~tes to a cyanide-free bath for ~ ~
the electrodeposition o~ gold and to the electrodeposition of ` ~-gold in such baths.
Alkaline cyanidic baths for electrogilding are known.
They are distinguishèd by excellent stability and robustness, and are frequently used. However, the disadvantage of such baths lies in the extraordinary toxicity of the cyanides, as a result ~;~
of which they pose a health hazard to those working with them and the disposal of their waste liquors gives rise to technical problems.
Neutral gold electrolytes containing an aurocyanide, trivalent arsenic and, as sulphur donor, an alkali metal thio~
sulphate, are also known (German Patent Publication No. 20 10 725).
However, such electrolytes also contain cyanide and have the further disadvantage of being neither ~loss-forming nor gloss-maintaining, and having no levelling effect.
Finally, cyanide-free gold baths containing gold in the form of sulphite and gloss-increasing additives have been proposed (German Patent Publication No. 16 21 180)~ Howe~er, such gold sulphito-complexes are not sufficiently stable, and ~ ~
when the solution stands for a long time elementary gold is ~ -formed, even with a very large excess of free sulphite ions, with the result that the solution becomes unusable.
The present Lnvention provides a process for the electrodeposition of gold, wherein electric current is passed ~;
through an electrodeposition bath free from cyanide ions and -`;
containing gold in the form of a thiosulphato-complex.
The present invention also provides a bath for the electrodeposition of gold, wherein the bath is free from cyanide ions and is an~aqueous solution of at least one conductiye salt - and gold in the form of a thiosulphato-complex.
This bath is generally stable and substantially c.. ~ ,,, - - - , ~3~
overcomes the disadvantages of the known gold baths. Thus, it ~ ;
is generally possible by a relatively non-toxic electrodeposition process to obtain gold deposits having good technological and decorative properties, and at the same time a high degree of purity.
The gold thiosulphato-complexes are complexes of vari-able composition containing gold as the central atom and at least one thiosulphate ligand. The approximate composition of the comp-lexes may correspond to the formula M3 12[Aul 2(S2O3)2 7~, in which M represents one equivalent o~ a metal, for example a sodium atom. The gold thiosulphato-complexes are known and may be made `;~
by methods in themselves known.
Sodium dithiosulphato-aurate (I) (Na3CAU(s23)2]~2H2o) may be made, for example, by the reduction of sodium tetrachloro-aurate (III) in neutral aqueous solution with thiosulphate, and precipitation of the resulting complex with alcohol.
In a similar manner, the compound sodium heptathio-sulphato-diaurate (I) (Nal2~Au2(S2O3)7]) may be made and isolated ~rom aqueous solution.
The gold thiosulphato-complexes to be used in accordance with the invention are generally readily soluble in water. The concentration of gold in the bath of the invention is advantageously from 0~1 g ofgold per litre up to saturation, and preferably `
. ;: ., from 3 to 30 g of gold per litre.
The gold thiosulphato-complexes may be added preformed to the bath or may be produced in the bath itself.
The present invention further provides a mixture of compounds suitable for making up a bath free from cyanide ions for the electrodeposition of gold which comprises a gold thiosul-phato-complex or its precursors and one or more ingredients suit-able for incorporation into electrodeposition baths.
Advantageously, the electrodeposition bath or mixture ~ ~-,''`'' '~; '
This invention xel~tes to a cyanide-free bath for ~ ~
the electrodeposition o~ gold and to the electrodeposition of ` ~-gold in such baths.
Alkaline cyanidic baths for electrogilding are known.
They are distinguishèd by excellent stability and robustness, and are frequently used. However, the disadvantage of such baths lies in the extraordinary toxicity of the cyanides, as a result ~;~
of which they pose a health hazard to those working with them and the disposal of their waste liquors gives rise to technical problems.
Neutral gold electrolytes containing an aurocyanide, trivalent arsenic and, as sulphur donor, an alkali metal thio~
sulphate, are also known (German Patent Publication No. 20 10 725).
However, such electrolytes also contain cyanide and have the further disadvantage of being neither ~loss-forming nor gloss-maintaining, and having no levelling effect.
Finally, cyanide-free gold baths containing gold in the form of sulphite and gloss-increasing additives have been proposed (German Patent Publication No. 16 21 180)~ Howe~er, such gold sulphito-complexes are not sufficiently stable, and ~ ~
when the solution stands for a long time elementary gold is ~ -formed, even with a very large excess of free sulphite ions, with the result that the solution becomes unusable.
The present Lnvention provides a process for the electrodeposition of gold, wherein electric current is passed ~;
through an electrodeposition bath free from cyanide ions and -`;
containing gold in the form of a thiosulphato-complex.
The present invention also provides a bath for the electrodeposition of gold, wherein the bath is free from cyanide ions and is an~aqueous solution of at least one conductiye salt - and gold in the form of a thiosulphato-complex.
This bath is generally stable and substantially c.. ~ ,,, - - - , ~3~
overcomes the disadvantages of the known gold baths. Thus, it ~ ;
is generally possible by a relatively non-toxic electrodeposition process to obtain gold deposits having good technological and decorative properties, and at the same time a high degree of purity.
The gold thiosulphato-complexes are complexes of vari-able composition containing gold as the central atom and at least one thiosulphate ligand. The approximate composition of the comp-lexes may correspond to the formula M3 12[Aul 2(S2O3)2 7~, in which M represents one equivalent o~ a metal, for example a sodium atom. The gold thiosulphato-complexes are known and may be made `;~
by methods in themselves known.
Sodium dithiosulphato-aurate (I) (Na3CAU(s23)2]~2H2o) may be made, for example, by the reduction of sodium tetrachloro-aurate (III) in neutral aqueous solution with thiosulphate, and precipitation of the resulting complex with alcohol.
In a similar manner, the compound sodium heptathio-sulphato-diaurate (I) (Nal2~Au2(S2O3)7]) may be made and isolated ~rom aqueous solution.
The gold thiosulphato-complexes to be used in accordance with the invention are generally readily soluble in water. The concentration of gold in the bath of the invention is advantageously from 0~1 g ofgold per litre up to saturation, and preferably `
. ;: ., from 3 to 30 g of gold per litre.
The gold thiosulphato-complexes may be added preformed to the bath or may be produced in the bath itself.
The present invention further provides a mixture of compounds suitable for making up a bath free from cyanide ions for the electrodeposition of gold which comprises a gold thiosul-phato-complex or its precursors and one or more ingredients suit-able for incorporation into electrodeposition baths.
Advantageously, the electrodeposition bath or mixture ~ ~-,''`'' '~; '
- 2 -for its preparation may contain an excess of thiosulphate, for ` example, in a ratio by weight of metal:thiosulphate o~ up to substan-tially 1:20. The concentration of thiosulphate in the bath solution is advantageously at least 1 g/l and preferably 20 to 500 g/l.
The thiosulphate is an ammonium and/or alkali metal salts, preferably a sodium or potassium salts, of thiosulphuric acid or their adducts with basic compounds such as, for example, amines or polyamines. - ~
When the mixture of compounds for making up the bath ~ `
contains excess thiosulphate, the mixture may include cyanide-containing salts, provided the thiosulphate is sufficient to ~ ;
convert the cyanide into the less toxic thiocyanate in the bath.
Since the anodic solubility of gold in thiosulphate solutions is low, insoluble anodes, for example, platinized titanium, should generally be used and, if desired, reducing agents, for example, nitrites, oxalates or sulphites, preferably the alkali metal salts, for example, the sodium or potassium salts, may be added to the bath.
The bath also contains one or more additi~es commonly used in electrodeposition baths, including the conductive salt, e.g., ammonium or alkali metal salts of inorganic or weak organic acids such as, for example, sulphuric acid, sulphurous acid, carbonic acid, boric acid, sulphamic acid, acetic acid and citric ~ ;~acid. The bath may aiso contain substances that regulate the pH, , advantageously the usual organic and/or inorgainc buffer mixtures such as, for example, disodium phosphate, alkali metal carbonate, , ~`
alkali metal borate r alkali metal acetate or citrate, alkali metal metabisulphite or a mixture of boric acid and ethylene glycol.
The pH of the bath is in the range of from 4 to 13, preferably 5 to 11. It is advantageous to work at a temperature in the range of from 10 to 80C, preferably 20 to 55C, and at a
The thiosulphate is an ammonium and/or alkali metal salts, preferably a sodium or potassium salts, of thiosulphuric acid or their adducts with basic compounds such as, for example, amines or polyamines. - ~
When the mixture of compounds for making up the bath ~ `
contains excess thiosulphate, the mixture may include cyanide-containing salts, provided the thiosulphate is sufficient to ~ ;
convert the cyanide into the less toxic thiocyanate in the bath.
Since the anodic solubility of gold in thiosulphate solutions is low, insoluble anodes, for example, platinized titanium, should generally be used and, if desired, reducing agents, for example, nitrites, oxalates or sulphites, preferably the alkali metal salts, for example, the sodium or potassium salts, may be added to the bath.
The bath also contains one or more additi~es commonly used in electrodeposition baths, including the conductive salt, e.g., ammonium or alkali metal salts of inorganic or weak organic acids such as, for example, sulphuric acid, sulphurous acid, carbonic acid, boric acid, sulphamic acid, acetic acid and citric ~ ;~acid. The bath may aiso contain substances that regulate the pH, , advantageously the usual organic and/or inorgainc buffer mixtures such as, for example, disodium phosphate, alkali metal carbonate, , ~`
alkali metal borate r alkali metal acetate or citrate, alkali metal metabisulphite or a mixture of boric acid and ethylene glycol.
The pH of the bath is in the range of from 4 to 13, preferably 5 to 11. It is advantageous to work at a temperature in the range of from 10 to 80C, preferably 20 to 55C, and at a
- 3 -; "
7~ :
current density of from 0.1 to 2 amper~s per dm . ~ ;~
The bath of the invention is used in a known manner.
The gold coatings deposited from the bath of the inven-tion are generally highly glossy and show outstanding ductility "~
in thick coatings. Moreover, the bath has a le~elling ef~ect even from 3 ~m, and is suitable for the deposition of both thin and thick gold layers. By using low current densities, for example, 0.1 - 0.5 amperes per `dm , high purity gold coatings o~ :
excellent e]ectrical conductivity are obtained. When carrying out electrolysis at 0.4 - 1.2 ampexes per dm2, gold coatings of high hardness (120 - 160 Vickers) coupled with good resistance -to abra~ion are obtained. Finally, the bath of the invention has the special advantage of being cyanlde-free and thus relatively non~toxic, whereby a reduction in health risks and a decrease in expenditure in disposing of waste liquors are achieved.
The following examples illustrate the invention. `~
Example 1 ~-Bath composition~
Gold in the form of sodium dithiosulphato-aurate (I) ~ `
Na3~Au(S2O3)2].2H2O : 0.04 molar = 7.9 g of gold/litre. , ~;
Sodium thiosulphate Na2S23 5H2 : 0.5 molar = ll9 g/litre.
Sodium sulphite `
Na2S3 : 0.06 molar = 7.6 g/litre.
Sodium borate Na4B4O7.1O~I2O : 0.015 molar = 6.4 g/litre.
Operating conditions~
pH (ad~usted with NaOH): 9.0 ~ ~
Temperature: 25C. ~--Stirring the electrolyte and cathode mo~ement.
Current density: 0.1 to 1.5 A/dm :,- .
Anode: platinized titanium. `~ ~
,,. :. ~ '
7~ :
current density of from 0.1 to 2 amper~s per dm . ~ ;~
The bath of the invention is used in a known manner.
The gold coatings deposited from the bath of the inven-tion are generally highly glossy and show outstanding ductility "~
in thick coatings. Moreover, the bath has a le~elling ef~ect even from 3 ~m, and is suitable for the deposition of both thin and thick gold layers. By using low current densities, for example, 0.1 - 0.5 amperes per `dm , high purity gold coatings o~ :
excellent e]ectrical conductivity are obtained. When carrying out electrolysis at 0.4 - 1.2 ampexes per dm2, gold coatings of high hardness (120 - 160 Vickers) coupled with good resistance -to abra~ion are obtained. Finally, the bath of the invention has the special advantage of being cyanlde-free and thus relatively non~toxic, whereby a reduction in health risks and a decrease in expenditure in disposing of waste liquors are achieved.
The following examples illustrate the invention. `~
Example 1 ~-Bath composition~
Gold in the form of sodium dithiosulphato-aurate (I) ~ `
Na3~Au(S2O3)2].2H2O : 0.04 molar = 7.9 g of gold/litre. , ~;
Sodium thiosulphate Na2S23 5H2 : 0.5 molar = ll9 g/litre.
Sodium sulphite `
Na2S3 : 0.06 molar = 7.6 g/litre.
Sodium borate Na4B4O7.1O~I2O : 0.015 molar = 6.4 g/litre.
Operating conditions~
pH (ad~usted with NaOH): 9.0 ~ ~
Temperature: 25C. ~--Stirring the electrolyte and cathode mo~ement.
Current density: 0.1 to 1.5 A/dm :,- .
Anode: platinized titanium. `~ ~
,,. :. ~ '
- 4 - ~ ~
~L~53~1~4 :~
A care~ully de~atted w~tch lunette of lead-containing brass was immersed in the above solution and electrolyzed for about 20 minutes under the above operating conditi~ns. A 6 to 7 ~m thick glossy gold layer free from pores was deposited on the lunette.
Example 2 Bath composition~
Gold in the form of sodium heptathiosulphato-aurate (I) Nal2cAu2(s2O3)7~ 1H2 : 0.04 molar = 15.7 g of gold/lltre.
Potassium thiosulphate ;~
K2S23 : 0.8 molar = 240 g/litre.
Sodium sulphite Na2S3 : 0.1 molar = 12.6 g/litre.
Boric acid B(OH)3 : 0.3 molar = 18.6 g/litre.
Ethylene glycol HO-CH2-CH2-OH : 0.6 molar = 37.2 g/litre.
Operating conditions:
~ pH; 6.8 Temperature: 23C
Anode: platinized titanium.
Current density: 0.3 to 1.5 A/dm2. l ;-A scratched copper plate having an area of about 1 dm2 was gilded in the above electrolyte under the above operating conditions for 15 minutes. The fine grooves caused by the scratch- ;
ing were distinctly levelled. ~;
Example 3 Bath composition~
Gold in the form of sodium dithiosulphato-aurate (I) Na3~AU(s2o3)2~ 2H2o : 0.05 molar = 10 g/litre.
Sodium thiosulphate Na2S2O3 : 0.5 molar = 119 g/litre. --~(~53~
Sodium sulphite ;~ `
Na2S3 : 0.05 molar = 6.3 g/litre.
Potassium dihydrogen phosphate KH2PO4 : 0.02 molar = 2.7 g/litre. ~
Potassium metabisulphite -K2S25 : 0.05 molar = 11.1 g/litre.
Operating conditions:
6.9 Temperature: 20C.
Anode: carbon. ;
Current density 0.1 to 1.2 A/dm .
A printed circuit having a total area of about 0.7 dm2 was gilded in the solution under the above conditions for 6 minutes. The resulting gold coating about 2.5 ~m thick was pore-free and could be soldered extremely well.
Example 4 Bath composition:
Gold in the form of sodium dithiosulphato-aurate (I) Na3~AU(s2o3)2] 2H2 : 0.05 molar~ = 9.85 g~1itre. -Sodium thiosulphate Na2S2O3 : 1.0 molar = 156 g/litre.
Sodium sulphite Na2S3 : 0.1 molar = 12.6 g/litre. ; ~; ;
Potassium metabisulphite ` ~.
K2S2O5 : 0.01 molar = 2.2 g/litre. -~
Boric acid B(OH)3 : 0.15 molar = 18.6 g/litre. ~.
Ethylene glycol 2 2 : 0.3 molar = 37.2 g/litre.
Operating conditions:
pH: 6.5 Temperature: 22C.
: . , - .. . . . . : ~. .. -, , :
~ 53~74~ :
node: Plantinized ti.tanium.
Diode leads having a kotal surface area of 1 m2 were' gilded ln a drum at an average current density of 0.1 A/dm2 under ~
the above conditions. The resulting 2 ~m thick coatings were ~ :;
pore-free and could be soldered well even after a long storage period of a few months.
` - '' ; ' ~'' '''` '~ ' , -:
,~
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.' ,`,~
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, ' ' ' . '., ~' : ' , ' ' - ,
~L~53~1~4 :~
A care~ully de~atted w~tch lunette of lead-containing brass was immersed in the above solution and electrolyzed for about 20 minutes under the above operating conditi~ns. A 6 to 7 ~m thick glossy gold layer free from pores was deposited on the lunette.
Example 2 Bath composition~
Gold in the form of sodium heptathiosulphato-aurate (I) Nal2cAu2(s2O3)7~ 1H2 : 0.04 molar = 15.7 g of gold/lltre.
Potassium thiosulphate ;~
K2S23 : 0.8 molar = 240 g/litre.
Sodium sulphite Na2S3 : 0.1 molar = 12.6 g/litre.
Boric acid B(OH)3 : 0.3 molar = 18.6 g/litre.
Ethylene glycol HO-CH2-CH2-OH : 0.6 molar = 37.2 g/litre.
Operating conditions:
~ pH; 6.8 Temperature: 23C
Anode: platinized titanium.
Current density: 0.3 to 1.5 A/dm2. l ;-A scratched copper plate having an area of about 1 dm2 was gilded in the above electrolyte under the above operating conditions for 15 minutes. The fine grooves caused by the scratch- ;
ing were distinctly levelled. ~;
Example 3 Bath composition~
Gold in the form of sodium dithiosulphato-aurate (I) Na3~AU(s2o3)2~ 2H2o : 0.05 molar = 10 g/litre.
Sodium thiosulphate Na2S2O3 : 0.5 molar = 119 g/litre. --~(~53~
Sodium sulphite ;~ `
Na2S3 : 0.05 molar = 6.3 g/litre.
Potassium dihydrogen phosphate KH2PO4 : 0.02 molar = 2.7 g/litre. ~
Potassium metabisulphite -K2S25 : 0.05 molar = 11.1 g/litre.
Operating conditions:
6.9 Temperature: 20C.
Anode: carbon. ;
Current density 0.1 to 1.2 A/dm .
A printed circuit having a total area of about 0.7 dm2 was gilded in the solution under the above conditions for 6 minutes. The resulting gold coating about 2.5 ~m thick was pore-free and could be soldered extremely well.
Example 4 Bath composition:
Gold in the form of sodium dithiosulphato-aurate (I) Na3~AU(s2o3)2] 2H2 : 0.05 molar~ = 9.85 g~1itre. -Sodium thiosulphate Na2S2O3 : 1.0 molar = 156 g/litre.
Sodium sulphite Na2S3 : 0.1 molar = 12.6 g/litre. ; ~; ;
Potassium metabisulphite ` ~.
K2S2O5 : 0.01 molar = 2.2 g/litre. -~
Boric acid B(OH)3 : 0.15 molar = 18.6 g/litre. ~.
Ethylene glycol 2 2 : 0.3 molar = 37.2 g/litre.
Operating conditions:
pH: 6.5 Temperature: 22C.
: . , - .. . . . . : ~. .. -, , :
~ 53~74~ :
node: Plantinized ti.tanium.
Diode leads having a kotal surface area of 1 m2 were' gilded ln a drum at an average current density of 0.1 A/dm2 under ~
the above conditions. The resulting 2 ~m thick coatings were ~ :;
pore-free and could be soldered well even after a long storage period of a few months.
` - '' ; ' ~'' '''` '~ ' , -:
,~
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.' ,`,~
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Claims (46)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A cyanide-free bath for the electrodeposition of gold comprising an aqueous solution of a conductive salt and gold in the form of a thiosulphato-complex.
2. A bath according to Claim 1, wherein the concentra-tion of gold is from 0.1 g/l to saturation.
3. A bath according to Claim 1, wherein the concentra-tion of gold is from 3 to 30 g/l.
4. A bath according to Claim 1, 2 or 3, which contains excess thiosulphate.
5. A bath according to Claim 1, having a concentration of thiosulphate of at least 1 g/l.
6. A bath according to Claim 1, having a concentration of thiosulphate from 20 to 500 g/l.
7. A bath according to Claim 1, wherein thiosulphate is present in the form of ammonium thiosulphate or an alkali metal thiosulphate.
8. A bath according to Claim 7, wherein the alkali metal thiosulphate is sodium or potassium thiosulphate.
9. A bath according to Claim 1, including a reducing agent.
10. A bath according to Claim 1, including, as a reducing agent, a compound selected from the group consisting of an alkali metal nitrite or sulphite.
11. A bath according to Claim 1, including a buffer.
12. A bath according to Claim 11, wherein the pH is in the range of from 4 to 13.
13. A bath according to Claim 11, wherein the pH is in the range of from 5 to 11,
14. A bath according to Claim 1, wherein the gold thiosulphato-complex has the formula M3-12 Au1-2(S2O3)2-7, in which M represents one equivalent of a metal
15. A bath according to Claim 1, wherein the thiosul-phato-complex is sodium dithiosulphato-aurate (I) or sodium heptathiosulphato-aurate (I).
16. A bath according to Claim 1, 3 or 15, wherein the conductive salt is an ammonium or alkali metal salt of an inorganic or weak organic acid.
17. A bath according to Claim 1, 3 or 15, wherein the conductive salt is an ammonium or alkali metal salt of an acid selected from the group consisting of sulphuric, sulphurous, carbonic/ boric, sulphamic, acetic and citric acid.
18. A bath according to claim 1, wherein the conductive salt is sodium or potassium thiosulphate.
19. A bath according to Claim 1, including, as a reducing agent, sodium sulphite.
20. A bath according to Claim 1, 15 or 18, including, as a pH regulator, sodium borate, potassium metabisulphite or a mixture of boric acid and ethylene glycol.
21. A process for the electrodeposition of gold com-prising passing an electric current through an electrodeposition bath free from cyanide ions and containing gold in the form of a thiosulphato-complex.
22. A process according to Claim 21, wherein the concentration of gold in the bath is from 0.1 g/l to saturation.
230 A process according to Claim 21, wherein the concentration of gold in the bath is from 3 to 30 g/l.
24. A process according to Claim 21, 22 or 23, wherein the bath contains excess thiosulphate
25. A process according to Claim 21, 22 or 23, wherein the bath has a concentration of thiosulphate of at least 1 g/l.
26. A process according to Claim 21, 22 or 23, wherein the bath has a concentration of thiosulphate from 20 to 500 g/l.
27. A process according to claim 21, 22 or 23, wherein thiosulphate is present in the form of ammonium thiosulphate or an alkali metal thiosulphate.
28. A process according to claim 21, 22 or 23, wherein thiosulphate is present in the form of sodium or potassium thiosulphate.
29. A process according to claim 21, 22 or 23, wherein the bath contains a reducing agent.
30. A process according to claim 2], 22 or 23, wherein the bath contains, as a reducing agent, an alkali metal nitrite or sulphite.
31. A process according to claim 21, 22 or 23, wherein the bath contains a conductive salt.
32. A process according to claim 21, 22 or 23, wherein the bath contains a buffer.
33. A process according to claim 21, 22 or 23, wherein the pH of the bath is from 4 to 13.
34. A process according to claim 21, 22 or 23, wherein the pH of the bath is from 5 to 11.
35. A process according to claim 21, 22 or 23, wherein the electrodeposition is carried out at a temperature of from 10 to 80°C.
36. A process according to claim 21, wherein the electrodeposition is carried out at a temperature of from 20 to 55°C.
37. A process according to claim 21 or 36, wherein a current density of from 0.1 to 2 A/dm2 is used.
38. A process according to claim 21 or 36, wherein a platinized titanium anode is used for the electrodeposition.
39. A process according to claim 21 or 36, wherein the gold thiosulphato-complex has the formula M3-12[Au1-2(S2O3) 2-7], in which M represents one equivalent of a metal.
40. A process according to claim 21 or 36, wherein the gold thiosulphato-complex is prepared in the electrodeposi-tion bath.
41. A cyanide-free bath for the electrodeposition of gold consisting essentially of an aqueous solution of a gold alkali thiosulfate compound of the formula:
M3-12Au1-2 (S2O3)2-7 wherein gold is the central atom and M is an alkali metal or ammonium, the gold concentration being from about 0.1 g/liter up to saturation, the concentration of thiosulfate being at least 1 g/liter and up to about 500 g/liter, said bath having a pH
value between 4 and 13.
M3-12Au1-2 (S2O3)2-7 wherein gold is the central atom and M is an alkali metal or ammonium, the gold concentration being from about 0.1 g/liter up to saturation, the concentration of thiosulfate being at least 1 g/liter and up to about 500 g/liter, said bath having a pH
value between 4 and 13.
42. A bath as defined in Claim 41 which contains-excess thiosulfate in a weight ratio of metal:thiosulfate up to about 1:20.
43. A bath as defined in Claim 41 in which M is selected from the group consisting of sodium, potassium and ammonium.
44. The bath as defined in claim 41, 42, or 43 wherein the gold is present in a concentration from 3 g to 30 g gold/liter.
45. The bath as defined in claim 41, 42 or 43 wherein the thiosulphate is present in concentrations from 20 g to 500 g per liter.
46. The bath as defined in claim 41, 42 or 43 wherein the bath has a pH value from 5 to 11.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19742445537 DE2445537A1 (en) | 1974-09-20 | 1974-09-20 | BATH FOR GALVANIC DEPOSITION OF GOLD |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1053174A true CA1053174A (en) | 1979-04-24 |
Family
ID=5926580
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA235,878A Expired CA1053174A (en) | 1974-09-20 | 1975-09-19 | Bath for the electrodeposition of gold |
Country Status (21)
| Country | Link |
|---|---|
| JP (1) | JPS5147539A (en) |
| AR (1) | AR206828A1 (en) |
| AT (1) | AT335813B (en) |
| BR (1) | BR7505838A (en) |
| CA (1) | CA1053174A (en) |
| CH (1) | CH614240A5 (en) |
| CS (1) | CS181784B2 (en) |
| DD (1) | DD118124A5 (en) |
| DE (1) | DE2445537A1 (en) |
| ES (1) | ES438407A1 (en) |
| FR (1) | FR2285473A1 (en) |
| GB (1) | GB1526215A (en) |
| HU (1) | HU172424B (en) |
| IE (1) | IE41859B1 (en) |
| IT (1) | IT1042698B (en) |
| NL (1) | NL7511062A (en) |
| RO (1) | RO69581A (en) |
| SE (1) | SE408436B (en) |
| SU (1) | SU923375A3 (en) |
| YU (1) | YU36050B (en) |
| ZA (1) | ZA755978B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5845026B2 (en) * | 1979-05-29 | 1983-10-06 | 松下電器産業株式会社 | electrophotographic equipment |
| JPS55157773A (en) * | 1979-05-29 | 1980-12-08 | Matsushita Electric Ind Co Ltd | Toner recovery device |
| DE4226167C2 (en) * | 1992-08-07 | 1996-10-24 | Sel Alcatel Ag | Method for electrically conductive connection using flip-chip technology |
| DE19546325C1 (en) * | 1995-12-12 | 1997-06-05 | Benckiser Knapsack Ladenburg | Process for coloring ceramic surfaces |
| KR20040093095A (en) | 2002-03-13 | 2004-11-04 | 미쓰비시 가가꾸 가부시키가이샤 | Gold plating solution and method for gold plating |
| CN108441901A (en) * | 2018-04-18 | 2018-08-24 | 中国工程物理研究院激光聚变研究中心 | A kind of gold-plating solution of no cyanogen organic solvent |
| EP4245893A1 (en) | 2022-03-15 | 2023-09-20 | Université de Franche-Comté | Gold electroplating solution and its use for electrodepositing gold with an aged appearance |
| CN115627505B (en) * | 2022-12-19 | 2023-04-28 | 深圳创智芯联科技股份有限公司 | Pulse cyanide-free gold electroplating liquid and electroplating process thereof |
| CN115821341B (en) * | 2023-01-06 | 2023-04-28 | 深圳创智芯联科技股份有限公司 | Environment-friendly cyanide-free electroplating solution and electroplating process thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5513318B2 (en) * | 1973-12-27 | 1980-04-08 |
-
1974
- 1974-09-20 DE DE19742445537 patent/DE2445537A1/en not_active Withdrawn
-
1975
- 1975-01-01 AR AR260458A patent/AR206828A1/en active
- 1975-04-25 YU YU1061/75A patent/YU36050B/en unknown
- 1975-05-04 CS CS7500003071A patent/CS181784B2/en unknown
- 1975-05-05 DD DD185844A patent/DD118124A5/xx unknown
- 1975-06-10 ES ES438407A patent/ES438407A1/en not_active Expired
- 1975-08-16 RO RO7583184A patent/RO69581A/en unknown
- 1975-08-20 JP JP50101081A patent/JPS5147539A/en active Pending
- 1975-09-11 BR BR7505838*A patent/BR7505838A/en unknown
- 1975-09-16 IE IE2018/75A patent/IE41859B1/en unknown
- 1975-09-17 SU SU752172438A patent/SU923375A3/en active
- 1975-09-18 SE SE7510455A patent/SE408436B/en unknown
- 1975-09-18 GB GB38392/75A patent/GB1526215A/en not_active Expired
- 1975-09-18 CH CH1214575A patent/CH614240A5/en not_active IP Right Cessation
- 1975-09-19 ZA ZA00755978A patent/ZA755978B/en unknown
- 1975-09-19 AT AT722575A patent/AT335813B/en not_active IP Right Cessation
- 1975-09-19 IT IT27420/75A patent/IT1042698B/en active
- 1975-09-19 HU HU75SC00000536A patent/HU172424B/en unknown
- 1975-09-19 FR FR7528741A patent/FR2285473A1/en active Granted
- 1975-09-19 CA CA235,878A patent/CA1053174A/en not_active Expired
- 1975-09-19 NL NL7511062A patent/NL7511062A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| ES438407A1 (en) | 1977-02-01 |
| YU106175A (en) | 1981-04-30 |
| AR206828A1 (en) | 1976-08-23 |
| AU8506575A (en) | 1977-03-31 |
| BR7505838A (en) | 1976-08-03 |
| JPS5147539A (en) | 1976-04-23 |
| SE408436B (en) | 1979-06-11 |
| DE2445537A1 (en) | 1976-04-08 |
| NL7511062A (en) | 1976-03-23 |
| ATA722575A (en) | 1976-07-15 |
| IE41859B1 (en) | 1980-04-09 |
| DD118124A5 (en) | 1976-02-12 |
| SU923375A3 (en) | 1982-04-23 |
| HU172424B (en) | 1978-08-28 |
| SE7510455L (en) | 1976-03-22 |
| GB1526215A (en) | 1978-09-27 |
| AT335813B (en) | 1977-04-12 |
| IT1042698B (en) | 1980-01-30 |
| CS181784B2 (en) | 1978-03-31 |
| IE41859L (en) | 1976-03-20 |
| ZA755978B (en) | 1976-08-25 |
| YU36050B (en) | 1981-11-13 |
| RO69581A (en) | 1980-08-15 |
| CH614240A5 (en) | 1979-11-15 |
| FR2285473B1 (en) | 1979-06-22 |
| FR2285473A1 (en) | 1976-04-16 |
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