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INVENTION
Patent of the Russian Federation RU2114213
SOLUTION OF CHEMICAL GOLD
Applicant's name: Joint Stock Company "Scientific Research Institute of Radio Components"
The name of the inventor: Gavrilina M.I .; V.Ya. Cilinsky; Valeeva EV; A. Frolikov; Mejaylova A.V .; Molina V.M.
Name of the patent holder: Joint Stock Company "Research Institute of Radio Components"
Address for correspondence:
Date of commencement of the patent: 1996.04.11
The invention relates to the deposition of metal coatings on. Metal surfaces, in particular, to chemical gilding, and can be used in microelectronics, radio engineering, computer technology, jewelry industry, etc. SUMMARY OF THE INVENTION: the solution of chemical gilding contains cyanoautrate in an amount of 0.5-1.0 g / l ( In terms of gold), complexing agent in an amount of 8.0-21.0 g / l and demineralized water. The solution may further contain a lower alcohol in an amount of 15-25 g / l and / or an alkali metal or ammonium carbonate in an amount of 0.003-0.015 g / l . The technical result of the invention is the production of a thin, non-porous, dense, mechanically strong gold coating with a decorative effect.
DESCRIPTION OF THE INVENTION
The invention relates to the application of metal coatings on metal surfaces, in particular to chemical gilding, and can be used in microelectronics, computers, jewelry, etc.
A chemical gilding solution is known (US Patent No. 3,588,916, class C 23 C 3/02, 1971) containing a water-soluble gold salt, a reducing agent, a complexing agent. This solution is not stable in operation, is difficult to manufacture, the resulting gold coating is loose, contains many pores and requires post-treatment.
A chemical gilding solution is also known (US Patent 4,142,902, Class C 23 C 3/02, 1979) containing non-cyanide gold salts and as a reducing agent, a tertiary aminoborate. Although this solution is not toxic, which refers to its advantages, but the resulting gold coating has the same drawbacks as the previous analog.
The closest analogue to the present invention is a chemical gilding solution (US Pat. No. 4,830,668, class C 23 C 18/44, 1989) containing water, an alkali metal cyanaurate (III) , and a complexing agent, which can be ethylenediaminotetramethylene phosphoric acid or 1-hydroxyethyl-1,1-diphosphoric acid. The resulting gold layer is loose and porous.
The technical problem, the solution of which is directed to the present invention, is to develop a chemical composition of gold plating that is stable in time with a reduced gold content, which allows obtaining thin gold coatings on metals.
The technical result obtained as a result of the realization of the invention consists in obtaining a thin, nonporous, dense, mechanically strong gold coating with a decorative effect.
The solution of chemical gilding contains cyanoaurat in the amount of 0.5-1.0 g / l , in terms of gold, a complexing agent in an amount of 8.0-21.0 g / l and demineralized water. Lithium and / or sodium and / or potassium and / or ammonium can be used as cations. Gold (i) and (III) cyanoaurates can be used. Ethylene glycol-bis (2-aminoethyl ester) - N, N, N ', N' -tetraacetic acid ( EGTA ), triethylenetetraaminohexaacetic acid (TGAA) , Nitrilotriacetic acid, ethylenediaminetetraacetic acid / edta) or their salts. The solution may further contain a lower alcohol / methanol, ethanol, isopropanol / in an amount of 15-25 g / l and / or an alkali metal or ammonium carbonate in an amount of 0.003-0.015 g / l .
The selected ratios of gold complexes to complexing agents, which are corrected depending on the chosen gold complex and a specific complexing agent, lead to the formation of a stable system in the solution, which is a complex of gold, containing as a ligand a cyanide and a complexin which, under the action of a catalyst, , Is capable of oxidizing cyanide, forming on the surface of the catalyst metal a dense, non-porous, thin, mechanically strong coating.
The applicant submits that the totality of features introduced by him into the independent claim is necessary and sufficient to obtain the above technical result. The features introduced by the applicant in the dependent claims are developed and supplemented by a combination of features introduced into an independent claim.
The chemical gilding solution is prepared by dissolving the components in the demineralized water.
Example. A metal component made of copper and copper alloys is placed in a prepared and preheated to 85 ° C solution containing 0.8 g / l of potassium cyanoaaurate (III) and 13 g / l of EGTA . The part is kept in a solution for 10 minutes . The coating thickness is 0.2 μm . Coatings are compact, non-porous, have good adhesion to the base, have a decorative appearance.
Specific examples of obtaining coatings with chemical gold at different concentrations and on different substrates are given in Table. 1, 2 .
Technical and economic efficiency lies in the fact that a thin ( 0.2 μm ) gold coating can be used as:
- Outer layer for platinum metals, nickel and its alloys, copper and its alloys, silver clad surfaces for giving anticorrosive and functional properties;
- Sublayer for thicker gold layers and platinum metals to ensure the porosity of the coating system and to prevent corrosion of the base metal and sublayer.
Application of the proposed solution of chemical gilding for various functional coatings reduces the consumption of gold by 5 to 10 times while maintaining quality.
CLAIM
A solution of chemical gilding containing cyanoaurate, a complexing agent and demineralized water, characterized in that the components are used in the following ratio, g / l;
Cyanoaurate (for gold) - 0.5 - 1.0
Complexifier - 8.0 - 21.0
Demineralized water - Other
2. A solution according to claim 1, characterized in that as the complexing agent, ethylene glycol-bis (2-aminoethyl ester) -N, N, N, N- tetraacetic acid, or triethylene tetraaminohexaacetic acid or nitrilotriacetic acid or ethylenediaminetetraacetic acid, or Their salts.A solution according to claim 1, characterized in that it further comprises a lower alcohol in an amount of 15-25 g / l .
A solution according to claim 1, characterized in that it further comprises an alkali metal or ammonium carbonate in an amount of 0.003-0.015 g / l .
print version
Date of publication 16.11.2006гг
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