Electrogilding liquid as well as preparation method and application thereof

Abstract

The invention relates to the technical field of electroplating, and discloses an electrogilding solution as well as a preparation method and application thereof. The electrogilding liquid comprises the following components by concentration: 3-15 g / L of gold salt, 30-100 mg / L of an accelerator, 10-20 g / L of a complexing agent, 15-50 mg / L of a stabilizer, 10-50 mg / L of an inhibitor, 30-70 mg / L of a dispersing agent and 10-20 g / L of conductive salt. The solvent of the electrogilding liquid is water; the accelerator is prepared from 3-amino-6-methylpyridazine. According to the gold electroplating solution provided by the invention, the 3-amino-6-methylpyridazine is used as an accelerator, so that gold ion sedimentation can be promoted, and the electroplating efficiency is improved; cyanogen-containing raw materials are not used in the electrogilding liquid, and the environmental protection property is good; the electrogilding liquid is good in stability, low in rejection rate and beneficial to cost saving; the electrogilding liquid is reasonable in components and working parameters, can form a uniform and bright plating layer without folding and plating cracks, and can be applied to electrogilding surface treatment of a ceramic substrate.

Description

Technical Field

[0001] The invention relates to the technical field of electroplating, and in particular to a gold electroplating solution and a preparation method and application thereof. Background Art

[0002] Electroplated gold coating has strong corrosion resistance, good conductivity, high temperature resistance, easy welding, and certain wear resistance (such as hard gold doped with a small amount of other elements). It also has good anti-discoloration ability. At the same time, gold alloy coatings have a variety of tones, and gold plating on silver can prevent discoloration.

[0003] Electroplated gold has good ductility and is easy to polish, so it is often used as a decorative coating, such as jewelry, watch parts, artworks, etc. It is also widely used in the electroplating of parts that require long-term stable electrical parameter performance, such as precision instruments, printed circuits, integrated circuits, electronic tube shells, and electrical contacts. Although electroplated gold can ensure excellent corrosion resistance and firmness, it has defects such as high cost and serious environmental problems with the raw materials used in the electroplating solution. Therefore, solving the environmental protection problem of raw materials and improving the performance of electroplated gold solution and coating are of great significance to reducing pollution, reducing raw material waste, and saving costs. Summary of the invention

[0004] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, one of the purposes of the present invention is to provide a gold electroplating solution; the second purpose of the present invention is to provide a method for preparing the gold electroplating solution; the third purpose of the present invention is to provide an application of the gold electroplating solution.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The first aspect of the present invention provides a gold electroplating solution, which comprises the following components in terms of concentration: 3-15 g / L of gold salt, 30-100 mg / L of accelerator, 10-20 g / L of complexing agent, 15-50 mg / L of stabilizer, 10-50 mg / L of inhibitor, 30-70 mg / L of dispersant, and 10-20 g / L of conductive salt; the solvent of the gold electroplating solution is water; and the accelerator comprises 3-amino-6-methylpyridazine.

[0007] Preferably, in terms of concentration, the gold electroplating solution includes the following components: 3-10 g / L of gold salt, 30-90 mg / L of accelerator, 10-15 g / L of complexing agent, 15-45 mg / L of stabilizer, 10-40 mg / L of inhibitor, 30-60 mg / L of dispersant, and 10-15 g / L of conductive salt; the solvent of the gold electroplating solution is water; and the accelerator includes 3-amino-6-methylpyridazine.

[0008] Preferably, the gold salt is selected from at least one of sodium gold sulfite, gold chloride, and potassium gold citrate; further preferably, the gold salt is sodium gold sulfite.

[0009] Preferably, the complexing agent is selected from at least one of 3,5-pyridinedicarboxylic acid, sulfite, citrate, and tartrate; further preferably, the complexing agent is 3,5-pyridinedicarboxylic acid.

[0010] Preferably, the conductive salt is selected from at least one of sodium sulfate, sodium chloride, potassium chloride and ammonium chloride; further preferably, the conductive salt is sodium sulfate.

[0011] Preferably, the stabilizer is selected from at least one of N-methylpyridazine-4-amine and 5-aminotetrazole; further preferably, the stabilizer is N-methylpyridazine-4-amine.

[0012] Preferably, the inhibitor is selected from 1-(4-[1-pyrrolidinyl]-2-butynyl)-2-pyrrolidone fumarate, 7H-pyrrolo[2,3-D]pyrimidin-2-amine or a combination thereof.

[0013] Further preferably, the inhibitor is a mixture of 1-(4-[1-pyrrolidinyl]-2-butynyl)-2-pyrrolidone fumarate and 7H-pyrrolo[2,3-D]pyrimidin-2-amine in a mass ratio of (1-2):1.

[0014] More preferably, the inhibitor is a mixture of 1-(4-[1-pyrrolidinyl]-2-butynyl)-2-pyrrolidone fumarate and 7H-pyrrolo[2,3-D]pyrimidine-2-amine in a mass ratio of (1-1.5):1.

[0015] Preferably, the dispersant is selected from at least one of ethyl 3-hydroxypyridazine-4-carboxylate and sodium polyacrylate; further preferably, the dispersant is ethyl 3-hydroxypyridazine-4-carboxylate.

[0016] Preferably, the pH of the gold electroplating solution is 5.0-6.0; further preferably, the pH of the gold electroplating solution is 5.2-6.0.

[0017] Preferably, the pH of the electroplating solution is adjusted by a sodium hydroxide solution with a mass concentration of 4-6% and / or a sulfuric acid solution with a volume concentration of 4-6%.

[0018] Preferably, the working parameters of the gold electroplating solution include at least one of the following:

[0019] 1) Working temperature is 20-40℃;

[0020] 2) Current density is 0.1-7A / dm 2 ;

[0021] 3) Working time is 20-40min.

[0022] Further preferably, the working parameters of the gold electroplating solution include at least one of the following:

[0023] 1) Working temperature is 25-35℃;

[0024] 2) Current density is 0.2-6.5A / dm 2 ;

[0025] 3) Working time is 20-30min.

[0026] The second aspect of the present invention provides a method for preparing the gold electroplating solution according to the first aspect of the present invention, comprising the following steps:

[0027] The components including gold salt, accelerator, complexing agent, stabilizer, inhibitor, dispersant and conductive salt are mixed with solvent according to concentration ratio to obtain the gold electroplating solution.

[0028] The third aspect of the present invention provides the use of the gold electroplating solution described in the first aspect of the present invention in the surface treatment of a ceramic substrate.

[0029] Preferably, the surface treatment is gold electroplating surface treatment.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1) The gold electroplating solution provided by the present invention uses 3-amino-6-methylpyridazine as an accelerator, which can promote the precipitation of gold ions and improve the electroplating efficiency;

[0032] 2) The electroplating gold solution provided by the present invention does not use cyanide-containing raw materials and is environmentally friendly; the electroplating gold solution has good stability and a low scrap rate, which is beneficial to cost saving;

[0033] 3) The composition and working parameters of the electroplating gold solution provided by the present invention are reasonable, and can form a coating with good uniformity and brightness and no folding cracks, which can provide the product with a beautiful appearance and improve corrosion resistance and firmness;

[0034] 4) The gold electroplating solution provided by the present invention does not corrode the nickel plating layer of the ceramic substrate, and can be applied to the gold electroplating surface treatment of the ceramic substrate, which is conducive to further expanding the application of the ceramic substrate. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0036] Example 1

[0037] This embodiment provides a gold electroplating solution, the components and contents of which are shown in Table 1:

[0038] Table 1 Components and contents of gold plating solution in Example 1

[0039]

[0040] The electroplating gold solution is prepared by the following steps:

[0041] The gold salt, accelerator, complexing agent, stabilizer, inhibitor, dispersant and conductive salt are mixed with deionized water according to the concentration ratio, and the pH value is adjusted to 5.6 using a sodium hydroxide solution with a mass concentration of 5% and / or a sulfuric acid solution with a volume concentration of 5% to obtain a gold electroplating solution.

[0042] Example 2

[0043] This embodiment provides a gold electroplating solution, the components and contents of which are shown in Table 2:

[0044] Table 2 Components and contents of gold plating solution in Example 2

[0045]

[0046] The electroplating gold solution is prepared by the following steps:

[0047] The gold salt, accelerator, complexing agent, stabilizer, inhibitor, dispersant and conductive salt are mixed with deionized water according to the concentration ratio, and the pH value is adjusted to 5.6 using a sodium hydroxide solution with a mass concentration of 5% and / or a sulfuric acid solution with a volume concentration of 5% to obtain a gold electroplating solution.

[0048] Example 3

[0049] This embodiment provides a gold electroplating solution, the components and contents of which are shown in Table 3:

[0050] Table 3 Components and contents of gold plating solution in Example 3

[0051]

[0052] The electroplating gold solution is prepared by the following steps:

[0053] The gold salt, accelerator, complexing agent, stabilizer, inhibitor, dispersant and conductive salt are mixed with deionized water according to the concentration ratio, and the pH value is adjusted to 5.6 using a sodium hydroxide solution with a mass concentration of 5% and / or a sulfuric acid solution with a volume concentration of 5% to obtain a gold electroplating solution.

[0054] Comparative Example 1

[0055] This comparative example provides a gold electroplating solution, the components and contents of which are shown in Table 4:

[0056] Table 4 Components and contents of gold plating solution in comparative example 1

[0057]

[0058] The electroplating gold solution is prepared by the following steps:

[0059] The gold salt, accelerator, complexing agent, inhibitor, dispersant and conductive salt are mixed with deionized water according to the concentration ratio, and the pH value is adjusted to 5.6 using a sodium hydroxide solution with a mass concentration of 5% and / or a sulfuric acid solution with a volume concentration of 5% to obtain a gold electroplating solution.

[0060] Comparative Example 2

[0061] This comparative example provides a gold electroplating solution, the components and contents of which are shown in Table 5:

[0062] Table 5 Components and contents of gold plating solution in comparative example 2

[0063]

[0064]

[0065] The electroplating gold solution is prepared by the following steps:

[0066] The gold salt, accelerator, complexing agent, stabilizer, dispersant and conductive salt are mixed with deionized water according to a concentration ratio, and a sodium hydroxide solution with a mass concentration of 5% and / or a sulfuric acid solution with a volume concentration of 5% is used to adjust the pH to 5.6 to obtain a gold electroplating solution.

[0067] Comparative Example 3

[0068] This comparative example provides a gold electroplating solution, the components and contents of which are shown in Table 6:

[0069] Table 6 Components and contents of gold plating solution in comparative example 3

[0070]

[0071] The electroplating gold solution is prepared by the following steps:

[0072] The gold salt, accelerator, complexing agent, stabilizer, inhibitor and conductive salt are mixed with deionized water according to the concentration ratio, and the pH value is adjusted to 5.6 using a sodium hydroxide solution with a mass concentration of 5% and / or a sulfuric acid solution with a volume concentration of 5% to obtain a gold electroplating solution.

[0073] Performance Testing

[0074] The electroplating gold solution in Examples 1-3 and Comparative Examples 1-3 was used to perform electroplating gold surface treatment on the nickel plating layer of the ceramic substrate. Each electroplating gold solution was used to treat 5 substrates. The working temperature of the electroplating gold solution was 30° C. and the current density was 2.5 A / dm 2 , time is 25min, to form a coating.

[0075] 1. Coating uniformity and brightness: Take the coating thickness of 5 substrates treated with each electroplating gold solution, calculate the extreme value and average value to evaluate the coating uniformity, observe the surface brightness of the coating and whether there are gold nodules. The uniformity and brightness evaluation standards are shown in Table 7.

[0076] Table 7 Evaluation criteria for coating uniformity and brightness

[0077]

[0078] 2. Use SEM to observe whether the coating has fold-plating cracks. The grade is divided according to the magnification required to observe the fold-plating cracks. The evaluation criteria for the fold-plating crack phenomenon are shown in Table 8.

[0079] Table 8 Evaluation criteria for fold-plating crack phenomenon on coating surface

[0080] Evaluation indicators grade Dense and smooth without folding cracks excellent Occasionally, fine cracks are seen, which can be seen when SEM is magnified 3000 times good The crack is large and can be seen at 1000 times SEM magnification. Poor There are many cracks, which can be seen when SEM is magnified 500 times Difference There are many cracks, which can be seen at SEM magnification of 200 times or less Very bad

[0081] 3. Gold cylinder stability test: The experimental amount of each electroplating gold liquid is 5 tanks of liquid, which are used normally for three months. The state of the electroplating gold liquid in the gold cylinder (including turbidity, tank liquid color, and whether precipitation occurs) is observed to evaluate its stability. The evaluation criteria are shown in Table 9.

[0082] Table 9 Evaluation criteria for stability of gold cylinder

[0083] Evaluation indicators grade The solution remains clear and transparent within three months without discoloration excellent The solution is clear within three months, with a little red solid precipitated on the tank wall good The solution is slightly red within three months Poor The solution becomes noticeably red within three months Difference The solution becomes turbid and discolored severely within three months Very bad

[0084] 4. Gold corrosion test: Electroplating gold is normally performed on the nickel-plated layer of the ceramic substrate. After stripping the gold, the corrosion phenomenon of the nickel surface is observed using SEM at a magnification of 3000 times to evaluate the nickel corrosion of the electroplating gold solution. The evaluation criteria are shown in Table 10.

[0085] Table 10 Nickel corrosion test evaluation standard

[0086] Evaluation indicators grade Nickel layer has no corrosion spots excellent Occasional corrosion spots on the nickel layer good There are some corrosion spots on the nickel layer Poor Nickel layer has many corrosion points Difference Nickel layer has dense corrosion points Very bad

[0087] The performance test results are shown in Table 11:

[0088] Table 11 Performance test results of gold plating solution in Examples 1-3 and Comparative Examples 1-3

[0089]

[0090] Table 11 is the performance test results of the electroplating gold solution in Examples 1-3 and Comparative Examples 1-3. It can be seen from Table 11 that the electroplating gold solution prepared in Examples 1-3 can be used for electroplating gold surface treatment of ceramic substrates, and the formed coating has good uniformity and brightness, and there is no folding crack, which is conducive to providing a uniform, beautiful, protective and decorative surface for the product; the gold surface of the electroplated product has no defects, which is more conducive to improving corrosion resistance and firmness, ensuring the stability and reliability of the product during use, and extending the service life. In the gold cylinder stability test of the electroplating gold solution in Examples 1-3, the solution is clear and transparent within three months, does not change color, and the electroplating gold solution has good stability; in the corrosion test, the electroplating gold solution has no corrosion on the nickel coating of the substrate, which is conducive to reducing the waste of electroplating gold solution and substrate caused by poor stability of the electroplating gold solution or corrosion of the nickel coating of the substrate, and can save the cost of electroplating gold. In addition, compared with the existing electroplating gold solution, the electroplating gold solution provided by the present invention does not contain gold salt potassium gold cyanide, does not use cyanide complexing agent, and does not use other cyanide-containing components. It is an environmentally friendly cyanide-free gold plating solution.

[0091] The difference between Comparative Example 1 and Example 1 is that the stabilizer N-methylpyridazine-4-amine is not added. Due to the lack of stabilizer to inhibit the precipitation of gold ions, the uniformity and brightness of the coating are reduced, the stability of the gold plating solution deteriorates, and the solution is clear within three months, but a little red solid is precipitated on the tank wall, and slight corrosion is caused to the nickel coating of the substrate.

[0092] The difference between Comparative Example 2 and Example 1 is that no composite inhibitor is added. Since the growth of gold particles is not inhibited and grows too fast, the uniformity and brightness of the coating are reduced, a few gold nodules are occasionally seen on the surface of the coating, and SEM magnification of 3000 times shows that there are fine cracks on the surface. The stability of the gold plating solution is deteriorated, and the corrosion effect of gold ions is not inhibited, so that the electroplating solution causes slight corrosion to the nickel plating layer of the substrate, and the overall performance of the gold plating solution is reduced.

[0093] The difference between Comparative Example 3 and Example 1 is that no dispersant is added. Due to poor dispersion of gold ions, the uniformity and brightness of the coating are reduced, there are a few cracks on the surface, the stability of the gold plating solution is deteriorated, and slight corrosion is caused to the nickel coating of the substrate.

[0094] It can be seen that the gold electroplating solution provided by the present invention uses cyanide-free gold salts and complexing agents, so that the environmental friendliness of the electroplating solution is improved; 6-methyl-3-aminopyridazine is used as an accelerator to accelerate the passage of gold ions through the double electrical layer. The aminopyridazine structure accelerator will coordinate with the gold ions to form particles with weak positive charges under weak acidic conditions. Under the Brownian motion of the particles, the particles are continuously transported to the surface of the substrate, thereby accelerating deposition; 1-(4-[1-pyrrolidinyl]-2-butynyl)-2-pyrrolidone fumarate and 7H-pyrrolo[2,3-d]pyrimidine-2-amine are used as The composite inhibitor can solve the problem of excessive growth of gold particles at the current density, improve the structure of the grains, improve the distribution efficiency of the current density, and inhibit the corrosion effect of gold ions on the surface of the nickel plating of the substrate; N-methylpyridazine-4-amine is selected as a stabilizer. The stabilizer forms positively charged particles under weak acidic conditions. Gold ions will attract hydroxide ions in water and stabilizers to obtain particle groups wrapped, thereby preventing gold ions from being accelerated by external conditions. Preparing 3-hydroxypyridazine-4-carboxylic acid ethyl ester as a dispersant can provide the dispersion of gold ions and improve the uniformity of the plating. Through the synergistic effect of multiple components and combined with reasonable process parameters, the electroplating gold solution has good environmental protection, excellent stability and low corrosion to the nickel plating of the substrate, so that the plating has no folding cracks and has high uniformity and brightness, reducing the scrap rate of the electroplating gold solution and the nickel-plated substrate, reducing the waste of raw materials, and saving the cost of electroplating gold; when applied to the electroplating gold surface treatment of ceramic substrates, it can form a uniform, bright, crack-free plating layer.

Claims

1. A gold electroplating solution, characterized in that: The gold electroplating solution comprises the following components in terms of concentration: 3-15 g / L of gold salt, 30-100 mg / L of accelerator, 10-20 g / L of complexing agent, 15-50 mg / L of stabilizer, 10-50 mg / L of inhibitor, 30-70 mg / L of dispersant and 10-20 g / L of conductive salt; the solvent of the gold electroplating solution is water; the accelerator comprises 3-amino-6-methylpyridazine.

2. The gold electroplating solution according to claim 1, characterized in that: The gold salt is selected from at least one of sodium gold sulfite, gold chloride, and potassium gold citrate; and / or, the complexing agent is selected from at least one of 3,5-pyridinedicarboxylic acid, sulfite, citrate, and tartrate; And / or, the conductive salt is selected from at least one of sodium sulfate, sodium chloride, potassium chloride and ammonium chloride.

3. The gold electroplating solution according to claim 1, characterized in that: The stabilizer is selected from at least one of N-methylpyridazine-4-amine and 5-aminotetrazole.

4. The gold electroplating solution according to claim 1, characterized in that: The inhibitor is selected from 1-(4-[1-pyrrolidinyl]-2-butynyl)-2-pyrrolidone fumarate, 7H-pyrrolo[2,3-D]pyrimidin-2-amine or a combination thereof.

5. The gold electroplating solution according to claim 4, characterized in that: The inhibitor is a mixture of 1-(4-[1-pyrrolidinyl]-2-butynyl)-2-pyrrolidone fumarate and 7H-pyrrolo[2,3-D]pyrimidine-2-amine in a mass ratio of (1-2):

1.

6. The gold electroplating solution according to claim 1, characterized in that: The dispersant is selected from at least one of ethyl 3-hydroxypyridazine-4-carboxylate and sodium polyacrylate.

7. The gold electroplating solution according to any one of claims 1 to 6, characterized in that: The pH of the gold electroplating solution is 5.0-6.

0.

8. The gold electroplating solution according to claim 7, characterized in that: The working parameters of the gold electroplating solution include at least one of the following: 1) Working temperature is 20-40℃; 2) Current density is 0.1-7A / dm 2 ; 3) Working time is 20-40min.

9. The method for preparing the gold electroplating solution according to any one of claims 1 to 8, characterized in that: The following steps are involved: The components including gold salt, accelerator, complexing agent, stabilizer, inhibitor, dispersant and conductive salt are mixed with solvent according to concentration ratio to obtain the gold electroplating solution.

10. Use of the gold electroplating solution according to any one of claims 1 to 8 in surface treatment of ceramic substrates.

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