Cyanide-free electrogilding solution as well as preparation method and application thereof
By using a cyanide-free gold plating solution formulation, which incorporates soluble gold salts and nitrogen-based macrocyclic complexing agents, the problems of toxicity and poor stability of traditional cyanide plating solutions are solved, resulting in high-quality plating and improved product performance.
Patent Information
- Application Number
- CN202511565345.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-30
- Publication Date
- 2026-02-03
AI Technical Summary
Traditional cyanide electroplating solutions for gold plating are highly toxic, cause serious pollution, and have poor coating stability, leading to problems such as rust in the later stages of product use.
A cyanide-free electroplating gold plating solution is used, employing soluble gold salts, a first complexing agent, and a second complexing agent (a nitrogen-based macrocyclic complex) to form a stable complex. This complex is combined with conductive salts, buffers, brighteners, wetting agents, and titanium ion chelating agents to ensure the stability of the plating solution and the quality of the plating layer.
It achieves stability and coating density in cyanide-free electroplating gold solutions, improves the conductivity and corrosion resistance of electronic materials, extends product life, and avoids the toxicity and pollution problems of traditional cyanides.
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of electroplating, in particular to a cyanide-free electroplating gold plating solution and a preparation method and application thereof. BACKGROUND
[0002] Gold is widely used in the field of electronic devices as a surface treatment material, mainly due to its excellent electrical conductivity and corrosion resistance, which can effectively protect products from oxidation and wear. Electroless gold plating is a common surface treatment technology, which deposits a gold layer on the substrate through electroplating or electroless plating process, thereby achieving the purpose of protection or enhancing electrical performance. As a core component of this technology, the stability of the electroplating gold solution and the quality of the plated layer directly affect the performance and service life of electronic components.
[0003] In traditional gold plating solution formulations, cyanide ions (CN-) are usually used as ligands to form stable complexes with gold ions (Au + ), effectively improving the service life of the plating solution, which has been widely used in industrial applications for many years. However, cyanide is a highly toxic substance, posing a serious threat to human health (such as acute poisoning through inhalation or skin contact) and the ecological environment (such as persistent pollution caused by wastewater discharge). Therefore, to meet environmental and safety requirements, the most commonly used gold salt for existing cyanide-free electroless gold plating is Na3Au(SO3)2, but the plating solution of this system has poor stability, and the plated layer is relatively loose, leading to rust and other phenomena during the later use of the product, seriously affecting the performance of the product. SUMMARY
[0004] In order to improve the density of the plated layer and prolong the service life of the product, the present application provides a cyanide-free electroplating gold plating solution and a preparation method and application thereof.
[0005] In a first aspect, the present application provides a cyanide-free electroplating gold plating solution, which adopts the following technical solution: A cyanide-free electroplating gold plating solution, prepared from the following raw materials by weight: 0.1-0.3 g / L of soluble gold salt, 5-10 g / L of first complexing agent, 1-2 g / L of second complexing agent, 10-20 g / L of buffer, 0.05-0.2 g / L of brightener, 0.01-0.05 g / L of wetting agent, 0.01-0.03 g / L of titanium ion chelating agent, 0.01-0.03 g / L of antioxidant, 2-4 g / L of conductive salt, and the balance being deionized water; The first complexing agent is disodium ethylenediaminetetraacetate; The preparation raw materials of the second complexing agent include azamacrocyclic complex and sodium hydroxide, and the mass ratio of the azamacrocyclic complex to sodium hydroxide is 1: (1-2).
[0006] By adopting the technical scheme, the soluble gold salt can not only serve as a metal source, but also has certain conductivity, thereby ensuring the smooth progress of the electroplating process; the conductive salt can increase the ion concentration of the electrolyte, thereby helping to reduce the resistance between the electrolyte and the electrode, promoting the deposition of metal ions in the electroplating solution and the electrochemical reaction, and enhancing the conductivity of the electrolyte, while also stabilizing the electrolytic conditions of the electroplating solution and maintaining a stable current density and potential.
[0007] The first complexing agent and the second complexing agent have a synergistic effect, the disodium salt of ethylenediaminetetraacetic acid preliminarily combines with gold ions to form a relatively stable basic complex, thereby providing a stable gold ion environment for subsequent reactions, and the second complexing agent further combines with gold ions and optimizes the complex structure by virtue of its special structure and performance, the two work together to reduce the concentration of free metal ions and improve the cathode polarization, so that the influence of the current density on the deposition rate becomes smaller, the deposition rate of the metal becomes relatively uniform at the protruding parts with high current density and the recessed parts with low current density, and the metal can well cover all corners of the gold-plated parts with complex shapes, thereby reducing the problems of excessive thickness at the edges, excessive thinness at the center, and no plating layer in deep holes.
[0008] Preferably, the preparation method of the second complexing agent comprises the following steps: Sodium hydroxide is added to water to form a sodium hydroxide solution, the azamacrocyclic complex is added to water, the sodium hydroxide solution is added, heating is performed until the reaction is completed, the pH of the solution is adjusted to 4-5, heating is performed until the solution is concentrated to 80-90℃, filtration is performed, the filtrate is cooled, the crystals are filtered out, water washing is performed, and drying is performed to obtain the second complexing agent.
[0009] Preferably, the azamacrocyclic complex comprises one or both of 1,4,7,10-tetraazacyclododecane tetraacetic acid and 1,4,7-triazacyclononane-1,4,7-triacetic acid.
[0010] By adopting the technical scheme, the two azamacrocyclic complexes are both macrocyclic multidentate complexing agents, which can "wrap" metal ions in the ring cavity in a multidentate coordination manner to form extremely stable complexes, thereby finally obtaining a high-quality plating layer that is fine and uniform in crystallization, bright, and excellent in covering capacity, by stabilizing the complexed metal ions, reducing the concentration of free ions, and significantly improving the cathode polarization.
[0011] Preferably, the soluble gold salt is potassium aurate.
[0012] By adopting the technical scheme, the use of potassium aurate as the soluble gold salt can avoid the use of traditional highly toxic cyanide, meet the environmental protection and safety requirements, and improve the stability of the plating solution and the quality of the plating layer.
[0013] Preferably, the buffer agent comprises one or both of disodium hydrogen phosphate and sodium dihydrogen phosphate.
[0014] Preferably, the buffer includes disodium hydrogen phosphate and sodium dihydrogen phosphate in a mass ratio of 1: (0.6-1).
[0015] By adopting the technical scheme, the disodium hydrogen phosphate and the sodium dihydrogen phosphate have a synergistic effect, the disodium hydrogen phosphate is weakly alkaline, the sodium dihydrogen phosphate is weakly acidic, and they can adjust the pH value of the plating solution to each other, so that the pH value of the plating solution is stabilized in a suitable range, the stability of the plating solution and the quality of the plated layer are avoided from being affected by the large fluctuation of the pH value, and thus the cyanide-free electroplating gold plating solution can continuously and stably work in the electroplating process, which helps to improve the compactness and uniformity of the plated layer.
[0016] Preferably, the titanium ion chelating agent is one or both of di(acetylacetone) titanium diisopropyl titanate and di(triethanolamine) titanium diisopropyl titanate.
[0017] By adopting the technical scheme, the addition of the titanium ion chelating agent expands the application range of the plating solution to the surface treatment of special alloy materials and improves the plating effect on complex substrates such as titanium alloys.
[0018] Preferably, the brightener includes one or more of polyethyleneimine, o-phenanthroline and 2,2-bipyridine; the wetting agent includes one or both of polyethylene glycol and fatty alcohol polyoxyethylene ether; and the antioxidant includes one or more of sodium formate, sodium hypophosphite and sodium sulfite.
[0019] By adopting the technical scheme, the brightener accelerates the formation of crystal nuclei, so that the generation rate of the crystal nuclei is greater than the growth rate of the crystal grains, the crystallization is refined, and the smoothness of the plated layer surface is improved; the wetting agent can better wet the surface of the plated workpiece by reducing the surface tension of the plating solution system interface, so that the solution can more easily enter the blind hole, the generation of bubbles is reduced, the mass transfer effect is increased, the integrity and uniformity of the plated layer are ensured, and defects such as plating leakage and pinholes are avoided; and the antioxidant can reduce the oxidation of metal ions, thereby improving the stability of the plating solution and prolonging the service life of the plating solution.
[0020] In a second aspect, the application provides a preparation method of the cyanide-free electroplating gold plating solution, which adopts the following technical scheme: A preparation method of a cyanide-free electroplating gold plating solution, comprising the following steps: The soluble gold salt and the conductive salt are added to the deionized water, and stirred until no solid is formed to form a gold solution; the first complexing agent and the second complexing agent are added to the gold solution, and stirred at a speed of 150-200 rpm for 1-2 h; the buffer, the brightener, the wetting agent, the titanium ion chelating agent and the antioxidant are continuously stirred for 1-2 h; the pH value is adjusted to 5.0-7.0; and the volume is fixed to obtain the cyanide-free electroplating gold plating solution.
[0021] By adopting the technical scheme, the cyanide-free electroplating gold plating solution prepared by the preparation method has good stability, the components are fully mixed and reacted, the gold-plated electronic material part can effectively improve the plating layer quality, thereby protecting the product from oxidation and wear, enhancing the electrical performance, and improving the product performance and service life.
[0022] In a third aspect, the application provides an application of the cyanide-free electroplating gold plating solution, which adopts the technical scheme as follows: An application of a cyanide-free electroplating gold plating solution in a gold-plated electronic material part.
[0023] By adopting the technical scheme, the cyanide-free electroplating gold plating solution is applied to the gold-plated electronic material part, the harm of the traditional cyanide gold plating solution to the human body and the environment is avoided, the plating solution has good stability and forms a dense plating layer, the conductivity and corrosion resistance of the gold-plated electronic material part can be improved, oxidation and wear can be reduced, and the performance and service life thereof can be improved.
[0024] The application has the following beneficial effects: The soluble gold salt can not only serve as a metal source but also has a certain conductive effect, ensuring the smooth progress of the electroplating process; the conductive salt can increase the ion concentration of the electrolyte, help to reduce the resistance between the electrolyte and the electrode, promote the deposition of metal ions in the electroplating solution and the electrochemical reaction, enhance the conductivity of the electrolyte, and stabilize the electrolytic conditions of the electroplating solution, maintaining a stable current density and potential.
[0025] The first complexing agent and the second complexing agent have a synergistic effect, the ethylenediaminetetraacetic acid disodium salt first preliminarily combines with gold ions to form a relatively stable basic complex, providing a stable gold ion environment for subsequent reactions, and the second complexing agent further combines with gold ions and optimizes the complex structure by virtue of its special structure and performance, the two together reduce the concentration of free metal ions, improve the cathode polarization degree, and make the influence of the current density on the deposition rate smaller, so that the deposition rate of the metal becomes relatively uniform at the convex part with high current density and the concave part with low current density, the metal can well cover all corners of the gold-plated part with a complex shape, reducing the problems of over-thick edges, over-thin center, and no plating layer in deep holes. DETAILED DESCRIPTION
[0026] The application will be further described in detail below in combination with examples.
[0027] Preparation Example
[0028] Preparation Example 1 The preparation method of the second complexing agent is as follows: Sodium hydroxide solution was prepared by adding 10 g of sodium hydroxide into water. 1,4,7,10-tetraazacyclododecane tetraacetic acid was added into water, stirred uniformly, and then the sodium hydroxide solution was added. The mixture was heated until the reaction was completed. Hydrochloric acid was added to adjust the pH of the solution to 4. The solution was heated to 80℃ for concentration. The filtrate was cooled, and the crystals were filtered out. The crystals were washed with water and dried to obtain the second complexing agent.
[0029] Preparation Example 2 The preparation method of the second complexing agent is as follows: Sodium hydroxide solution was prepared by adding 15 g of sodium hydroxide into water. 1,4,7-triazacyclononane-1,4,7-triacetic acid was added into water, stirred uniformly, and then the sodium hydroxide solution was added. The mixture was heated until the reaction was completed. Hydrochloric acid was added to adjust the pH of the solution to 4.5. The solution was heated to 85℃ for concentration. The filtrate was cooled, and the crystals were filtered out. The crystals were washed with water and dried to obtain the second complexing agent.
[0030] Preparation Example 3 The preparation method of the second complexing agent is as follows: Sodium hydroxide solution was prepared by adding 20 g of sodium hydroxide into water. 1,4,7-triazacyclononane-1,4,7-triacetic acid was added into water, stirred uniformly, and then the sodium hydroxide solution was added. The mixture was heated until the reaction was completed. Hydrochloric acid was added to adjust the pH of the solution to 5. The solution was heated to 90℃ for concentration. The filtrate was cooled, and the crystals were filtered out. The crystals were washed with water and dried to obtain the second complexing agent.
[0031] Example
[0032] Example 1 A cyanide-free gold plating solution, comprising: potassium aurate 0.1 g / L, potassium chloride 2 g / L, disodium ethylenediaminetetraacetate 5 g / L, second complexing agent 1 g / L, sodium hydrogen phosphate 6.5 g / L, sodium dihydrogen phosphate 3.5 g / L, polyethyleneimine 0.05 g / L, polyethylene glycol 0.01 g / L, di(triethanolamine) titanium diisopropylate 0.01 g / L, sodium formate 0.01 g / L, and the rest is deionized water.
[0033] The second complexing agent is prepared according to Preparation Example 1. The polyethyleneimine is a commercially available product of Ranabai CAS No. 9002-98-6. The number average molecular weight of the polyethylene glycol is 1000. The preparation method of the cyanide-free gold plating solution of the present example comprises the following steps: According to the above-mentioned component allocation ratio, potassium aurate and potassium chloride are added to 30 L of deionized water, stirred until no solid, form a gold solution, add disodium ethylenediaminetetraacetate and the second complexing agent to the gold solution, stir at a speed of 150 rpm for 1 h, add disodium hydrogen phosphate, sodium dihydrogen phosphate, polyethyleneimine, polyethylene glycol, titanium diisopropyl bis(triethanolamine) phosphate, sodium formate, continue to stir for 1 h, adjust the pH to 5.0, and the balance is made up to 50 L with deionized water to obtain the cyanide-free electroplating gold plating solution.
[0034] Example 2 A cyanide-free electroplating gold plating solution comprises: Potassium aurate 0.2 g / L, potassium chloride 3 g / L, disodium ethylenediaminetetraacetate 8 g / L, the second complexing agent 1.5 g / L, disodium hydrogen phosphate 7.5 g / L, sodium dihydrogen phosphate 7.5 g / L, o-phenanthroline 0.1 g / L, fatty alcohol polyoxyethylene ether 0.03 g / L, titanium diisopropyl bis(acetylacetone) phosphate 0.02 g / L, sodium hypophosphite 0.02 g / L, and the balance is made up to 50 L with deionized water.
[0035] The second complexing agent is prepared by the preparation example 2; The fatty alcohol polyoxyethylene ether is a commercially available product of BASF type A 3065; The preparation method of the cyanide-free electroplating gold plating solution of the embodiment comprises the following steps: According to the above-mentioned component allocation ratio, potassium aurate and potassium chloride are added to 30 L of deionized water, stirred until no solid, form a gold solution, add disodium ethylenediaminetetraacetate and the second complexing agent to the gold solution, stir at a speed of 150 rpm for 1 h, add disodium hydrogen phosphate, sodium dihydrogen phosphate, polyethyleneimine, polyethylene glycol, titanium diisopropyl bis(triethanolamine) phosphate, sodium formate, continue to stir for 1 h, adjust the pH to 5.0, and the balance is made up to 50 L with deionized water to obtain the cyanide-free electroplating gold plating solution.
[0036] Example 3 A cyanide-free electroplating gold plating solution comprises: Potassium aurate 0.2 g / L, potassium chloride 3 g / L, disodium ethylenediaminetetraacetate 8 g / L, the second complexing agent 1.5 g / L, disodium hydrogen phosphate 7.5 g / L, sodium dihydrogen phosphate 7.5 g / L, o-phenanthroline 0.1 g / L, fatty alcohol polyoxyethylene ether 0.03 g / L, titanium diisopropyl bis(acetylacetone) phosphate 0.02 g / L, sodium hypophosphite 0.02 g / L, and the balance is made up to 50 L with deionized water.
[0037] The second complexing agent is prepared by the preparation example 3; The fatty alcohol polyoxyethylene ether is a commercially available product of BASF type A 3065; The preparation method of the cyanide-free gold plating solution in the embodiment includes the following steps. According to the allocation ratio of each raw material component, potassium aurate and potassium chloride are added to 30 L of deionized water, stirred until no solid is formed, to form a gold solution, and then disodium ethylenediaminetetraacetate and a second complexing agent are added to the gold solution, stirred at a speed of 200 rpm for 2 h, and then disodium hydrogen phosphate, sodium dihydrogen phosphate, 2,2-bipyridine, fatty alcohol polyoxyethylene ether, titanium diisopropyl bis(acetylacetone) phosphate, and sodium sulfite are continuously stirred for 2 h, the pH is adjusted to 7.0, and the remaining amount is made up to 50 L with deionized water to obtain the cyanide-free gold plating solution.
[0038] Example 4 The embodiment differs from Example 2 in that the sodium dihydrogen phosphate is replaced with an equal amount of disodium hydrogen phosphate.
[0039] Example 5 The embodiment differs from Example 2 in that the disodium hydrogen phosphate is replaced with an equal amount of sodium dihydrogen phosphate.
[0040] Comparative Example
[0041] Comparative Example 1 A cyanide-free gold plating solution differs from Example 2 in that the disodium ethylenediaminetetraacetate is replaced with an equal amount of the second complexing agent obtained in Preparation Example 2.
[0042] Comparative Example 2 A cyanide-free gold plating solution differs from Example 2 in that the second complexing agent is replaced with an equal amount of disodium ethylenediaminetetraacetate.
[0043] Comparative Example 3 A cyanide-free gold plating solution differs from Example 2 in that the second complexing agent is replaced with an equal amount of 1,4,7,10-tetraazacyclododecane tetraacetic acid.
[0044] Comparative Example 4 A cyanide-free gold plating solution differs from Example 2 in that the second complexing agent is replaced with an equal amount of 1,4,7-triazacyclononane-1,4,7-triacetic acid.
[0045] Comparative Example 5 A cyanide-free gold plating solution differs from Example 2 in that the titanium diisopropyl bis(acetylacetone) phosphate is replaced with an equal amount of disodium ethylenediaminetetraacetate.
[0046] Comparative Example 6 A cyanide-free gold plating solution differs from Example 2 in that the disodium ethylenediaminetetraacetate is replaced with an equal amount of sodium cyanide.
[0047] Performance detection test Preparation of samples: the plated parts were respectively placed into the electroplating tank containing the cyanide-free gold plating solution of each example and the comparative example, and electroplated with the gold plate as anode and the plated part as cathode, to obtain the gold-plated parts after electroplating. The electroplating parameters during electroplating were as follows: temperature 55℃, current density 1 ASD, and electroplating time 20 min. The electroplated performance of the gold-plated parts in each example and the comparative example was tested.
[0048] 1. Coating adhesion test: the adhesion of the coating to the substrate was tested by thermal shock method and bending test method (GB / T 5270-2005). Thermal shock method: after electroplating of the substrate, it was kept at 200℃ for 2h, and then was quickly cooled in cold water, to observe whether there were phenomena such as blistering and peeling of the coating; bending method: the plated sample was bent 90° twice and observed whether there were phenomena such as peeling and stripping.
[0049] 2. Porosity test: the porosity of the substrate after electroplating was determined by filter paper method. The number of characteristic spots per unit area was taken as the evaluation index for testing.
[0050] 3. Ten samples were randomly selected from each example and the comparative example, the thickness of each sample was tested, then the average thickness μ of the gold-plated layer of the same group of samples was calculated, and the standard deviation α of the thickness of the gold-plated layer of the same group of samples was calculated, then the uniformity coefficient CV of the gold-plated layer of each group of samples was calculated. The uniformity coefficient of the gold-plated layer = (α / μ)*100%. The smaller the uniformity coefficient, the better the uniformity of the gold-plated layer. In actual production process, the uniformity coefficient CV less than 8% is qualified.
[0051] 4. Corrosion resistance test: neutral salt spray test was used. The results of the neutral salt spray test can reflect the Cl - The time of the coating reaching the substrate. The substrate was subjected to neutral salt spray test according to the standard specified in GB / T 6458, and the neutral salt spray (NSS) test was carried out in YWX-60 salt spray corrosion test chamber. A NaCl solution with mass fraction of 5% and pH of 6-7 was settled on the sample by a spraying device, the temperature was 30℃, the relative humidity was greater than 95%, the fogging amount was 1-2 mL / (h·cm 2 ), and the nozzle pressure was 70-137 kPa.
[0052] According to the comparison of Example 2 and Examples 4-5, it can be seen that disodium hydrogen phosphate and sodium dihydrogen phosphate have a synergistic effect, disodium hydrogen phosphate is weakly alkaline, sodium dihydrogen phosphate is weakly acidic, and they can adjust the pH value of the plating solution to each other, so that the pH value of the plating solution is stabilized in a suitable range, avoiding the influence of large fluctuations of the pH value on the stability of the plating solution and the quality of the plated layer, so as to ensure that the cyanide-free gold plating solution can work continuously and stably during the electroplating process, and help to improve the density and uniformity of the plated layer. In Example 4, sodium dihydrogen phosphate is used as a buffer alone, and in Example 5, disodium hydrogen phosphate is used as a buffer alone, and the stability of the plating solution in both is poorer than that in Example 2, which affects the quality of the plated layer.
[0053] According to the comparison of Example 2 and Comparative Examples 1-4, it can be seen that the first complexing agent and the second complexing agent have a synergistic effect, disodium ethylenediaminetetraacetate first combines with gold ions to form a relatively stable basic complex, providing a stable gold ion environment for subsequent reactions, and the second complexing agent further combines with gold ions in a multi-dentate coordination manner and optimizes the complex structure, both of which work together to reduce the concentration of free metal ions and improve the cathode polarization degree, which is conducive to forming a plated layer with small crystal nucleus and dense structure. In Comparative Examples 1-4, there may still be some free metal ions, and Comparative Example 3 and Comparative Example 4 will reduce the pH of the plating solution, affecting the stability of the plating solution, and further affecting the quality of the plated layer.
[0054] According to the comparison of Example 2 and Comparative Example 5, it can be seen that the titanium ion chelating agent can further form a stable chelate, reduce hydrolysis or precipitation in the plating solution, thereby improving the stability of the plating solution, ensuring uniform dispersion of each component in the plating solution, making the plated layer more dense and uniform, and avoiding rust and other phenomena in the later use of the product.
[0055] According to the comparison of Example 2 and Comparative Example 6, it can be seen that sodium cyanide is a highly toxic compound that seriously endangers human health and the ecological environment, and the treatment of waste liquid will also increase the production cost of the enterprise, and the gold-plated parts in Comparative Example 6 still have rust spots, and the surface quality of the gold-plated parts is not as good as that of the gold-plated parts in Example 2.
[0056] The specific embodiment is only an explanation of the present application, which is not a limitation of the present application, and those skilled in the art can make modifications to the specific embodiment without creative contribution after reading the present specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.
Claims
1. A cyanide-free electroplating gold plating solution, characterized by, The composition comprises the following components: 0.1-0.3 g / L of soluble gold salt, 5-10 g / L of first complexing agent, 1-2 g / L of second complexing agent, 10-20 g / L of buffer, 0.05-0.2 g / L of brightener, 0.01-0.05 g / L of wetting agent, 0.01-0.03 g / L of titanium ion chelating agent, 0.01-0.03 g / L of antioxidant, 1.5-2 g / L of conductive salt, and the rest is deionized water; The first complexing agent is disodium ethylenediaminetetraacetate; The raw materials for preparing the second complexing agent include azamacrocyclic complex and sodium hydroxide, and the mass ratio of the azamacrocyclic complex to the sodium hydroxide is 1: (1-2).
2. The cyanide-free electro-gold plating solution according to claim 1, wherein, The preparation method of the second complexing agent comprises the following steps: The sodium hydroxide is added into water to form a sodium hydroxide solution, the azamacrocyclic complex is added into water, the sodium hydroxide solution is added, heating is performed until the reaction is completed, the pH of the solution is adjusted to 4-5, heating is performed until the concentration is 80-90 ℃, filtration is performed, the filtrate is cooled, the crystals are filtered out, water washing is performed, and drying is performed to obtain the second complexing agent.
3. The cyanide-free electroplating gold plating solution of claim 1, wherein, The azamacrocyclic complex includes one or both of 1, 4, 7, 10-tetraazacyclododecane tetraacetic acid and 1, 4, 7-triazacyclononane-1, 4, 7-triacetic acid.
4. The cyanide-free electroplating gold plating solution of claim 1, wherein, The soluble gold salt is potassium aurate.
5. The cyanide-free electroplating gold plating solution of claim 1, wherein, The buffer includes one or both of disodium hydrogen phosphate and sodium dihydrogen phosphate.
6. The cyanide-free electro-gold plating solution according to claim 1, wherein, The buffer includes disodium hydrogen phosphate and sodium dihydrogen phosphate at a mass ratio of 1: (0.6-1).
7. The cyanide-free electroplating gold plating solution of claim 1, wherein, The titanium ion chelating agent is one or both of di (acetylacetone) titanium diisopropyl titanate and di (triethanolamine) titanium diisopropyl titanate.
8. The cyanide-free electro-gold plating solution of claim 1, wherein, The brightener includes one or more of polyethyleneimine, o-phenanthroline and 2, 2-bipyridine; the wetting agent includes one or both of polyethylene glycol and fatty alcohol polyoxyethylene ether; and the antioxidant includes one or more of sodium formate, sodium hypophosphite and sodium sulfite.
9. A process for the preparation of a cyanide-free electroplating gold bath according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: The soluble gold salt and the conductive salt are added into deionized water, stirring is performed until there is no solid, a gold solution is formed, the first complexing agent and the second complexing agent are added into the gold solution, stirring is performed at a rotation speed of 150-200 rpm for 1-2 h, the buffer, the brightener, the wetting agent, the titanium ion chelating agent and the antioxidant are added and continue to be stirred for 1-2 h, the pH is adjusted to 5.0-7.0, and the volume is adjusted to obtain the cyanide-free gold plating solution.
10. Use of a cyanide-free electro-gold plating bath according to any one of claims 1 to 8, characterized in that, The method is used for plating gold on electronic material parts.