A gold plating solution, its preparation method and application

Abstract

This invention relates to the field of electroplating technology, and discloses an electroplating gold solution, its preparation method, and its application. The electroplating gold solution, by concentration, comprises the following components: 3-15 g / L gold salt, 30-100 mg / L accelerator, 10-20 g / L complexing agent, 15-50 mg / L stabilizer, 10-50 mg / L inhibitor, 30-70 mg / L dispersant, and 10-20 g / L conductive salt; the solvent of the electroplating gold solution is water; the accelerator includes 3-amino-6-methylpyridazine. The electroplating gold solution provided by this invention, using 3-amino-6-methylpyridazine as an accelerator, can promote gold ion precipitation and improve electroplating efficiency; the electroplating gold solution does not use cyanide-containing raw materials, thus having good environmental friendliness; the electroplating gold solution has good stability and a low scrap rate, which helps to save costs; the composition and working parameters of the electroplating gold solution are reasonable, and it can form a uniform, bright coating without plating cracks, and can be applied to the electroplating gold surface treatment of ceramic substrates.

Description

Technical Field

[0001] This invention relates to the field of electroplating technology, and in particular to an electroplating gold solution, its preparation method, and its application. Background Technology

[0002] Electroplated gold coatings are highly corrosion-resistant, have good electrical conductivity, are resistant to high temperatures, are easy to weld, and have a certain degree of wear resistance (such as hard gold mixed with a small amount of other elements). They also have good resistance to discoloration. In addition, gold alloy coatings come in a variety of shades, and plating gold on silver can prevent discoloration.

[0003] Electroplated gold coatings have good ductility and are easy to polish, making them commonly used as decorative coatings, such as for jewelry, watch parts, and artwork. They are also widely used in precision instruments, printed circuit boards, integrated circuits, electron tube housings, and electrical contacts—parts requiring long-term stable electrical parameters. Although electroplated gold offers excellent corrosion resistance and durability, it suffers from drawbacks such as high cost and serious environmental concerns regarding the raw materials used in the plating solution. Therefore, addressing the environmental issues of raw materials and improving the performance of the electroplating solution and the coating are crucial for reducing pollution, minimizing material waste, and saving costs. Summary of the Invention

[0004] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, one objective of the present invention is to provide an electroplating gold solution; a second objective is to provide a method for preparing such an electroplating gold solution; and a third objective is to provide applications of such an electroplating gold solution.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A first aspect of the present invention provides an electroplating gold solution comprising, by concentration: 3-15 g / L gold salt, 30-100 mg / L accelerator, 10-20 g / L complexing agent, 15-50 mg / L stabilizer, 10-50 mg / L inhibitor, 30-70 mg / L dispersant, and 10-20 g / L conductive salt; wherein the solvent of the electroplating gold solution is water; and the accelerator comprises 3-amino-6-methylpyridazine.

[0007] Preferably, the electroplating gold solution comprises, by concentration, the following components: 3-10 g / L gold salt, 30-90 mg / L accelerator, 10-15 g / L complexing agent, 15-45 mg / L stabilizer, 10-40 mg / L inhibitor, 30-60 mg / L dispersant, and 10-15 g / L conductive salt; the solvent of the electroplating gold solution is water; and the accelerator comprises 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; more 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; more 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; more preferably, the conductive salt is sodium sulfate.

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

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

[0013] 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 (1-2):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; more preferably, the dispersant is ethyl 3-hydroxypyridazine-4-carboxylate.

[0016] Preferably, the pH of the gold plating solution is 5.0-6.0; more preferably, the pH of the gold plating 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 operating parameters of the electroplating gold solution include at least one of the following:

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

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

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

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

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

[0024] 2) Current density is 0.2-6.5 A / dm² 2 ;

[0025] 3) The working time is 20-30 minutes.

[0026] A second aspect of the present invention provides a method for preparing the electroplating gold solution described in the first aspect of the present invention, comprising the following steps:

[0027] The electroplating gold solution is obtained by mixing the components, including gold salt, accelerator, complexing agent, stabilizer, inhibitor, dispersant and conductive salt, with a solvent according to the concentration ratio.

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

[0029] Preferably, the surface treatment is an electroplated gold surface treatment.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] 1) The electroplating gold 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 this invention does not use cyanide-containing raw materials, which is environmentally friendly; the electroplating gold solution has good stability and low scrap rate, which helps to save costs;

[0033] 3) The electroplating gold solution provided by this invention has reasonable composition and working parameters, which can form a coating with good uniformity and brightness and no plating cracks, providing the product with an aesthetic appearance and improving corrosion resistance and durability;

[0034] 4) The electroplating gold solution provided by this invention does not corrode the nickel plating layer on the ceramic substrate and can be applied to the electroplating gold surface treatment of the ceramic substrate, which is beneficial to further expand the application of the ceramic substrate. Detailed Implementation

[0035] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0036] Example 1

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

[0038] Table 1. Components and content of electroplating gold solution in Example 1

[0039]

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

[0041] Gold salt, accelerator, complexing agent, stabilizer, inhibitor, dispersant, and conductive salt are mixed with deionized water according to the concentration ratio. The pH is adjusted to 5.6 using a 5% (w / w) sodium hydroxide solution and / or a 5% (v / v) sulfuric acid solution to obtain the gold plating solution.

[0042] Example 2

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

[0044] Table 2. Components and content of electroplating gold solution in Example 2

[0045]

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

[0047] Gold salt, accelerator, complexing agent, stabilizer, inhibitor, dispersant, and conductive salt are mixed with deionized water according to the concentration ratio. The pH is adjusted to 5.6 using a 5% (w / w) sodium hydroxide solution and / or a 5% (v / v) sulfuric acid solution to obtain the gold plating solution.

[0048] Example 3

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

[0050] Table 3. Components and content of electroplating gold solution in Example 3

[0051]

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

[0053] Gold salt, accelerator, complexing agent, stabilizer, inhibitor, dispersant, and conductive salt are mixed with deionized water according to the concentration ratio. The pH is adjusted to 5.6 using a 5% (w / w) sodium hydroxide solution and / or a 5% (v / v) sulfuric acid solution to obtain the gold plating solution.

[0054] Comparative Example 1

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

[0056] Table 4. Components and content of electroplating gold solution in Comparative Example 1

[0057]

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

[0059] Gold salt, accelerator, complexing agent, inhibitor, dispersant, and conductive salt are mixed with deionized water according to the concentration ratio. The pH is adjusted to 5.6 using a 5% (w / w) sodium hydroxide solution and / or a 5% (v / v) sulfuric acid solution to obtain the gold plating solution.

[0060] Comparative Example 2

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

[0062] Table 5. Components and content of electroplating gold solution in Comparative Example 2

[0063]

[0064]

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

[0066] Gold salt, accelerator, complexing agent, stabilizer, dispersant, and conductive salt are mixed with deionized water according to the concentration ratio. The pH is adjusted to 5.6 using a 5% (w / w) sodium hydroxide solution and / or a 5% (v / v) sulfuric acid solution to obtain the gold plating solution.

[0067] Comparative Example 3

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

[0069] Table 6. Components and content of electroplating gold solution in Comparative Example 3

[0070]

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

[0072] Gold salt, accelerator, complexing agent, stabilizer, inhibitor, and conductive salt are mixed with deionized water according to the concentration ratio. The pH is adjusted to 5.6 using a 5% (w / w) sodium hydroxide solution and / or a 5% (v / v) sulfuric acid solution to obtain the gold plating solution.

[0073] Performance testing

[0074] The electroplating gold solutions from Examples 1-3 and Comparative Examples 1-3 were used to perform electroplating gold surface treatment on nickel-plated ceramic substrates. Five substrates were treated with each electroplating gold solution. The operating temperature of the electroplating gold solutions was 30°C, and the current density was 2.5 A / dm³. 2 The coating is formed in 25 minutes.

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

[0076] Table 7 Evaluation Criteria for Coating Uniformity and Brightness

[0077]

[0078] 2. Use SEM to observe whether there are plating cracks in the coating. The level is determined by the magnification required to observe the plating cracks. The evaluation criteria for plating crack phenomenon are shown in Table 8.

[0079] Table 8 Evaluation Criteria for Plating Surface Cracking Phenomena

[0080] Evaluation indicators grade Dense, smooth, and free of plating cracks excellent Occasionally, minute cracks are observed; they can be seen under 3000x SEM magnification. good The crack is quite large and can be seen under 1000x SEM magnification. Poor There are many cracks, which can be seen under SEM magnification of 500x. Difference Numerous cracks are visible under SEM magnification of 200x or less. Very bad

[0081] 3. Gold plating tank stability test: The experimental quantity of each gold plating solution is 5 tank solutions. The tanks are used normally for a period of three months. The state of the gold plating solution in the gold tank is observed (including turbidity, tank color, and whether separation occurs) to evaluate its stability. The evaluation criteria are shown in Table 9.

[0082] Table 9 Stability Evaluation Standards for Gold Cylinders

[0083] Evaluation indicators grade The solution remains clear and transparent and does not change color within three months. excellent Within three months, the solution became clear, with a small amount of red solid precipitating on the tank walls. good The solution turned slightly red within three months. Poor The solution turned noticeably red within three months. Difference The solution became severely cloudy and discolored within three months. Very bad

[0084] 4. Gold corrosion test: Gold was electroplated normally on the nickel-plated layer of the ceramic substrate. After the gold was removed, the corrosion phenomenon on the nickel surface was observed using SEM at 3000x magnification to evaluate the nickel corrosion of the gold plating solution. The evaluation criteria are shown in Table 10.

[0085] Table 10 Evaluation Criteria for Nickel Corrosion Testing

[0086] Evaluation indicators grade The nickel layer has no corrosion spots excellent Occasional corrosion spots are observed in the nickel layer. good The nickel layer has some corrosion spots. Poor There are many corrosion pits in the nickel layer Difference Nickel layer corrosion pits are dense Very bad

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

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

[0089]

[0090] Table 11 shows the performance test results of the electroplating gold solutions in Examples 1-3 and Comparative Examples 1-3. As can be seen from Table 11, the electroplating gold solutions prepared in Examples 1-3 can be used for electroplating gold surface treatment of ceramic substrates. The resulting coating has good uniformity and brightness, and is free of plating cracks, which is beneficial for providing products with a uniform, aesthetically pleasing surface with protective and decorative properties. The gold surface of the electroplated product is defect-free, which further enhances corrosion resistance and durability, ensuring the stability and reliability of the product during use and extending its service life. In the gold plating tank stability test of Examples 1-3, the solution remained clear and transparent without discoloration within three months, indicating good stability. In the corrosion test, the electroplating gold solution did not corrode the nickel plating layer of the substrate, which helps reduce waste of electroplating gold solution and substrate caused by poor stability of the electroplating gold solution or corrosion of the nickel plating layer, thus saving electroplating gold costs. Furthermore, compared with existing gold plating solutions, the gold plating solution provided by this invention does not contain gold salt potassium gold cyanide, does not use cyanide complexing agents, and does not use other cyanide-containing components, making it 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 was not added. Due to the lack of stabilizer to inhibit the precipitation of gold ions, the uniformity and brightness of the plating layer decreased, the stability of the gold plating solution deteriorated, the solution became clear within three months, but a little red solid precipitated on the tank wall, and it would cause slight corrosion to the nickel plating layer of the substrate.

[0092] The difference between Comparative Example 2 and Example 1 is that no composite inhibitor was added. Since the growth of gold particles was not inhibited, the growth was too fast, which reduced the uniformity and brightness of the coating. Occasionally, a few gold nodules were seen on the coating surface. When magnified by 3000 times with SEM, fine cracks were visible on the surface. The stability of the gold plating solution deteriorated, and the corrosion effect of gold ions was not inhibited, which caused slight corrosion of the nickel coating on the substrate by the electroplating solution. The overall performance of the gold plating solution decreased.

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

[0094] As can be seen, the electroplating gold solution provided by this invention uses cyanide-free gold salts and complexing agents, thus improving the environmental friendliness of the electroplating solution; 6-methyl-3-aminopyridazine is used as an accelerator, which can accelerate the passage of gold ions through the double layer. The aminopyridazine accelerator coordinates with gold ions, forming particles with a weak positive charge under weakly acidic conditions. Under Brownian motion of the particles, the particles are continuously transported to the substrate surface, 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 solves the problem of excessively rapid gold particle growth at current densities, improves grain structure, enhances current density distribution efficiency, and inhibits the corrosive effect of gold ions on the nickel plating surface of the substrate. N-methylpyridazine-4-amine is used as a stabilizer; in weakly acidic conditions, the stabilizer forms positively charged particles, which attract hydroxide ions from the water, encapsulating the gold ions into particle clusters, thus preventing accelerated gold ion precipitation due to external conditions. Ethyl 3-hydroxypyridazine-4-carboxylate is used as a dispersant, improving the dispersion of gold ions and the uniformity of the plating layer. Through the synergistic effect of multiple components and combined with reasonable process parameters, the electroplating gold solution exhibits good environmental friendliness, excellent stability, and low corrosion of the nickel plating substrate. This results in a plating layer free of plating cracks, with high uniformity and brightness, reducing the scrap rate of the electroplating gold solution and the nickel plating substrate, minimizing raw material waste, and saving electroplating gold costs. When applied to the electroplating gold surface treatment of ceramic substrates, it can form a uniform, bright, and crack-free plating layer.

Claims

1. A gold plating solution, characterized in that, The electroplating solution comprises the following components by concentration: gold salt 3-15 g / L, accelerator 30-100 mg / L, complexing agent 10-20 g / L, stabilizer 15-50 mg / L, inhibitor 10-50 mg / L, dispersant 30-70 mg / L, and conductive salt 10-20 g / L; the solvent of the electroplating solution is water; wherein the gold salt is sodium gold sulfite; the accelerator is 3-amino-6-methylpyridazine; the complexing agent is 3,5-pyridinedicarboxylic acid; the conductive salt is selected from at least one of sodium sulfate, sodium chloride, potassium chloride, and ammonium chloride; the stabilizer is N-methylpyridazine-4-amine; and the inhibitor has a mass ratio of (1-2): A mixture of 1-(4-[1-pyrrolidinyl]-2-butynyl)-2-pyrrolidone fumarate and 7H-pyrrolo[2,3-D]pyrimidine-2-amine; the dispersant is ethyl 3-hydroxypyridazine-4-carboxylate; the pH of the gold plating solution is 5.0-6.

0.

2. The electroplating gold solution according to claim 1, 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 (1-1.5):

1.

3. The electroplating gold solution according to claim 1, characterized in that, The pH of the electroplating gold solution is 5.2-6.

0.

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

5. The method for preparing the electroplating gold solution according to any one of claims 1-4, characterized in that, Includes the following steps: The components, including gold salt, accelerator, complexing agent, stabilizer, inhibitor, dispersant and conductive salt, are mixed with solvent according to the concentration ratio, and the pH is adjusted to obtain the electroplating gold solution.

6. The application of the electroplating gold solution according to any one of claims 1-4 in the surface treatment of ceramic substrates.

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