A copper surface chemical silver plating solution and its preparation method and use method as well as silver plating layer

Abstract

The present invention provides a copper surface chemical silver plating solution, comprising 0.1-100 g / L of silver (II) pyridine-2-carboxylate, 0.1-10 g / L of a complexing agent, 0.1-100 mL / L of an organic acid, 0.5-10 g / L of a surfactant, 0.2-8 g / L of an accelerator, 5-100 g / L of a corrosion inhibitor, and water. The present invention improves the chemical silver plating solution formula and adopts divalent silver ions Ag. 2+ It has a higher redox potential and a fast oxidation deposition speed, which makes the silver ion deposition rate fast and the silver plating layer can be deposited thicker. At the same time, the deposition rate is fast, and the attack on the circuit side corrosion position is small, which can avoid side corrosion. By combining with other additives, the deposition rate of silver ions can be further accelerated, the deposition thickness can be increased, and side corrosion can be avoided, thereby solving the side corrosion problems of thin silver thickness and strong acid corrosion of copper surface in chemical silver plating in the existing technology.

Description

Technical Field

[0001] The invention belongs to the technical field of surface treatment, and in particular relates to a copper surface chemical silver plating solution, a preparation method and a use method thereof, and a silver plating layer. Background Art

[0002] Printed circuit boards (PCBs) are the support for electronic components and the carrier for their electrical connections. Among PCB surface treatment processes, immersion silver offers a smooth surface, making it suitable for direct assembly and applications such as BGA, SMT, and high-density circuit design. It also offers excellent solderability, low process cost, and simple operation, making it suitable for large-scale production. Both horizontal and vertical processes are possible, and the equipment required is also relatively small, making immersion silver a promising application market.

[0003] In recent years, electroless silver plating has become increasingly popular in the final surface treatment of PCBs due to its ease of operation, reasonable price, and excellent performance. Currently, the deposition thickness of electroless silver plating solutions is thin, typically 0.1 to 0.6 μm, and there is a problem of undercutting of the copper surface by strong acid. With increasing customer demand, deposition thicknesses must exceed 1 μm, and some even reach 4 μm. Therefore, increasing deposition thickness and preventing undercutting have become pressing challenges in this field. Summary of the Invention

[0004] The present invention aims to provide a solution for electroless silver plating on copper surfaces, its preparation and use methods, and a silver-plated layer. The silver plating solution provided by the present invention can address the existing problems of thin silver plating thickness and side corrosion caused by strong acid attack on the copper surface during electroless silver plating.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The invention provides a copper surface chemical silver plating solution, which comprises 0.1-100 g / L of silver (II) pyridine-2-carboxylate, 0.1-10 g / L of a complexing agent, 0.1-100 mL / L of an organic acid, 0.5-10 g / L of a surfactant, 0.2-8 g / L of an accelerator, 5-100 g / L of a corrosion inhibitor and water.

[0007] Preferably, the method comprises 1-50 g / L of silver (II) pyridine-2-carboxylate, 1-8 g / L of a complexing agent, 5-50 mL / L of an organic acid, 1-8 g / L of a surfactant, 1-6 g / L of an accelerator, 10-50 g / L of a corrosion inhibitor and water.

[0008] Preferably, the complexing agent includes at least one of ethylenediamine, picoline, aminopyridine, glycine, aminosulfonic acid, malic acid, triethanolamine, acetic acid, ethylenediaminetetraacetic acid, lactic acid, aminosalicylic acid, diethylenetriamine, triethylenetetramine, triammonium citrate and sulfosalicylic acid.

[0009] Preferably, the organic acid comprises at least one of methanesulfonic acid, aminosulfonic acid and trifluoroacetic acid.

[0010] Preferably, the surfactant includes at least one of a carboxylate fluorocarbon surfactant, a sulfonate fluorocarbon surfactant, a phosphate fluorocarbon surfactant, a quaternary ammonium salt fluorocarbon surfactant and a nonionic fluorine-based surfactant.

[0011] Preferably, the accelerator comprises at least one of formic acid, formaldehyde, acetaldehyde, sodium hypophosphite and glucose.

[0012] Preferably, the corrosion inhibitor includes at least one of benzotriazole, 2-mercaptobenzothiazole, 2-amino-5-mercapto-1,3,4-thiadiazole, 2-mercaptothiazoline and 5-mercapto-1-phenyltetrazole.

[0013] The present invention also provides a method for preparing the copper surface chemical silver plating solution described in the above technical solution, comprising the following steps:

[0014] (1) mixing silver (II) pyridine-2-carboxylate, a complexing agent, an organic acid, a surfactant, a corrosion inhibitor, and water to obtain a mixed solution;

[0015] (2) mixing the mixed solution obtained in step (1) with an accelerator to obtain a copper surface chemical silver plating solution.

[0016] The present invention also provides a method for using the copper surface chemical silver plating solution described in the above technical solution or the copper surface chemical silver plating solution prepared by the preparation method described in the above technical solution, comprising the following steps:

[0017] The copper substrate is immersed in a copper surface chemical silver plating solution.

[0018] The present invention also provides a silver plating layer, which is prepared by the method described in the above technical solution.

[0019] The present invention provides a copper surface chemical silver plating solution, comprising 0.1-100 g / L of silver (II) pyridine-2-carboxylate, 0.1-10 g / L of a complexing agent, 0.1-100 mL / L of an organic acid, 0.5-10 g / L of a surfactant, 0.2-8 g / L of an accelerator, 5-100 g / L of a corrosion inhibitor, and water. The present invention improves the chemical silver plating solution formula and adopts divalent silver ions Ag. 2+, it has a higher redox potential and a fast oxidation deposition rate, which enables a faster silver ion deposition rate and a thicker silver coating. At the same time, the fast deposition rate reduces the attack on the circuit lateral corrosion position and can avoid lateral corrosion. By combining with other additives, the silver ion deposition rate can be further accelerated, the deposition thickness can be increased, and lateral corrosion can be avoided, thus solving the problems of thin silver plating thickness in the prior art and lateral corrosion caused by strong acid attack on the copper surface during chemical silver plating. Experimental results show that the coating thickness obtained by the chemical silver plating solution on copper surface provided by this application reaches 20μm without lateral corrosion. DETAILED DESCRIPTION

[0020] The invention provides a copper surface chemical silver plating solution, which comprises 0.1-100 g / L of silver (II) pyridine-2-carboxylate, 0.1-10 g / L of a complexing agent, 0.1-100 mL / L of an organic acid, 0.5-10 g / L of a surfactant, 0.2-8 g / L of an accelerator, 5-100 g / L of a corrosion inhibitor and water.

[0021] The copper surface chemical silver plating solution provided by the present invention comprises 0.1 to 100 g / L of silver (II) pyridine-2-carboxylate, preferably 1 to 50 g / L, more preferably 1 to 25 g / L, and more preferably 1 to 5 g / L. In the present invention, silver (II) pyridine-2-carboxylate contains divalent silver ions Ag. 2+ It has a higher redox potential (+1.987V, 25℃), and the effectiveness of high-valent silver ions is 300 to 17,000 times that of metallic silver or silver salts. Due to the extremely high reduction potential of high-valent silver ions, they are also called active silver ions. The oxidation potential of divalent silver ions is high, the oxidation deposition rate is fast, and the corresponding silver ion deposition rate is fast, so the silver plating can be deposited thicker; the deposition rate is fast, and the attack on the circuit side corrosion position is small; pyridine has strong complexing properties, which can reduce the hydrolysis of silver ions.

[0022] The copper surface chemical silver plating solution provided by the present invention also includes a complexing agent of 0.1 to 10 g / L, preferably 1 to 8 g / L, more preferably 3 to 5 g / L, and more preferably 4 to 5 g / L. In the present invention, the complexing agent preferably includes at least one of ethylenediamine, picoline, aminopyridine, glycine, aminosulfonic acid, malic acid, triethanolamine, acetic acid, ethylenediaminetetraacetic acid, lactic acid, aminosalicylic acid, diethylenetriamine, triethylenetetramine, triammonium citrate, and sulfosalicylic acid, more preferably 3-picoline. In the present invention, the complexing agent mainly complexes silver ions, and also complexes metal impurities in the plating solution, such as copper ions. The concentration of the complexing agent cannot be too high, as it will hinder the replacement of silver ions with copper, and too low a concentration will lead to solution instability.

[0023] The copper surface chemical silver plating solution provided by the present invention further includes 0.1 to 100 mL / L of an organic acid, preferably 5 to 50 mL / L, more preferably 10 to 25 mL / L, and more preferably 15 to 20 mL / L. In the present invention, the organic acid preferably includes at least one of methanesulfonic acid, aminosulfonic acid, and trifluoroacetic acid. In the present invention, the organic acid is a complexing agent that can maintain the stability of the solution, enable the chemical replacement reaction to proceed under acidic conditions, and maintain the acidity of the solution.

[0024] The copper surface chemical silver plating solution provided by the present invention further comprises 0.5 to 10 g / L of a surfactant, preferably 1 to 8 g / L, more preferably 3 to 5 g / L, and even more preferably 4 to 5 g / L. In the present invention, the surfactant preferably comprises at least one of a carboxylate fluorocarbon surfactant, a sulfonate fluorocarbon surfactant, a phosphate fluorocarbon surfactant, a quaternary ammonium salt fluorocarbon surfactant, and a nonionic fluorine-based surfactant. The fluorocarbon surfactant in the present invention has characteristics not possessed by other surfactants. It can reduce the surface tension of deionized water solutions to a very low level at very low concentrations (50 to 100 ppm); it has high thermodynamic and chemical stability and can be used in systems such as high temperature, strong acid, strong base, and strong oxidizing media; it has excellent compatibility and can be widely used in various pH ranges, various deionized water-based, solvent-based, powder or radiation-curing systems, and is well compatible with other surfactants and components in the system; due to its good wettability, it can accelerate the replacement of silver ions on the copper surface and has a better wetting effect on small solder pads; it can improve the problem of uneven deposition in chemical silver plating, and due to the low solubility used, the surfactant is easy to clean and can also improve the problem of plating penetration.

[0025] The copper surface chemical silver plating solution provided by the present invention also includes an accelerator of 0.2 to 8 g / L, preferably 1 to 6 g / L, more preferably 3 to 5 g / L, and more preferably 4 to 5 g / L. In the present invention, the accelerator preferably includes at least one of formic acid, formaldehyde, acetaldehyde, sodium hypophosphite, and glucose. The accelerator in the present invention is mainly an aldehyde-containing substance with weak reducing properties, which can accelerate the rate of chemical silver deposition, thereby increasing the thickness of the deposited silver.

[0026] The electroless silver plating solution for copper surfaces provided by the present invention also includes a corrosion inhibitor at 5 to 100 g / L, preferably 10 to 50 g / L, more preferably 20 to 25 g / L, and even more preferably 22 to 24 g / L. In the present invention, the corrosion inhibitor preferably includes at least one of benzotriazole, 2-mercaptobenzothiazole, 2-amino-5-mercapto-1,3,4-thiadiazole, 2-mercaptothiazoline, and 5-mercapto-1-phenyltetrazole. The corrosion inhibitor in the present invention is a nitrogen- and sulfur-containing substance that can be adsorbed on the copper surface to prevent Galvanic corrosion at the interface between the copper surface and the silver layer.

[0027] The copper surface chemical silver plating solution provided by the present invention also includes water. In the present invention, the water is preferably deionized water. In the present invention, water is a solvent.

[0028] The present invention has no particular limitation on the sources of the above raw materials, and commercially available products known to those skilled in the art may be used.

[0029] The present invention improves the chemical silver plating solution formula and adopts divalent silver ions Ag 2+ It has a higher redox potential and a fast oxidation deposition speed, which makes the silver ion deposition rate fast and the silver plating layer can be deposited thicker. At the same time, the deposition rate is fast, and the attack on the circuit side corrosion position is small, which can avoid side corrosion. By combining with other additives, the deposition rate of silver ions can be further accelerated, the deposition thickness can be increased, and side corrosion can be avoided, thereby solving the side corrosion problems of thin silver thickness and strong acid corrosion of copper surface in chemical silver plating in the existing technology.

[0030] The present invention also provides a method for preparing the copper surface chemical silver plating solution described in the above technical solution, comprising the following steps:

[0031] (1) mixing silver (II) pyridine-2-carboxylate, a complexing agent, an organic acid, a surfactant, a corrosion inhibitor, and water to obtain a mixed solution;

[0032] (2) mixing the mixed solution obtained in step (1) with an accelerator to obtain a copper surface chemical silver plating solution.

[0033] The invention mixes silver (II) pyridine-2-carboxylate, a complexing agent, an organic acid, a surfactant, a corrosion inhibitor and water to obtain a mixed solution.

[0034] The present invention has no special limitation on the mixing operation of the silver (II) pyridine-2-carboxylate, complexing agent, organic acid, surfactant, corrosion inhibitor and water, and the technical scheme for preparing the mixed material well known to those skilled in the art can be adopted.

[0035] After obtaining the mixed solution, the present invention mixes the mixed solution with an accelerator to obtain a copper surface chemical silver plating solution. The present invention adopts a step-by-step feeding method and adds the accelerator later, which can increase the chemical silver plating deposition rate, thereby increasing the thickness of the precipitated silver, while also ensuring the stability of the plating solution.

[0036] The present invention has no special limitation on the operation of mixing the mixed solution with the accelerator, and the technical scheme for preparing the mixed material well known to those skilled in the art can be adopted.

[0037] The present invention also provides a method for using the copper surface chemical silver plating solution described in the above technical solution or the copper surface chemical silver plating solution prepared by the preparation method described in the above technical solution, comprising the following steps:

[0038] The copper substrate is immersed in a copper surface chemical silver plating solution.

[0039] The present invention immerses the copper substrate in a copper surface chemical silver plating solution.

[0040] In the present invention, the copper substrate is preferably degreased and micro-etched before use. The present invention has no particular limitation on the degreasing and micro-etching operations, and operations well known to those skilled in the art can be used.

[0041] In the present invention, the immersion temperature is preferably 25 to 40° C., more preferably 30 to 35° C.; the immersion time is preferably 3 to 20 minutes, more preferably 6 to 10 minutes.

[0042] The present invention also provides a silver plating layer, which is prepared by the method described in the above technical solution.

[0043] The silver plating provided by the present invention has a relatively thick deposition thickness, which can reach 20 μm.

[0044] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] Example 1

[0046] The electroless silver plating solution on copper surface is: 1g / L silver (II) pyridine-2-carboxylate, 5g / L 3-methylpyridine as complexing agent, 10mL / L methylsulfonic acid as organic acid, 0.8g / L ammonium perfluorooctanesulfonate as surfactant, 4g / L formic acid as accelerator, 8g / L benzotriazole as corrosion inhibitor and deionized water;

[0047] The preparation method of the chemical silver plating solution on the copper surface is as follows:

[0048] Silver (II) pyridine-2-carboxylate is first added, then 3-methylpyridine, methanesulfonic acid, ammonium perfluorooctanesulfonate, phenyltriazole and deionized water are added, and finally formic acid is added to obtain a chemical silver plating solution on a copper surface.

[0049] Example 2

[0050] The electroless silver plating solution on copper surface is: 1g / L silver (II) pyridine-2-carboxylate, 5g / L malic acid as a complexing agent, 10mL / L sulfamic acid as an organic acid, 0.8g / L ammonium perfluorooctanesulfonate as a surfactant, 2g / L formic acid as an accelerator, 5g / L 2-mercaptobenzothiazole as a corrosion inhibitor, and deionized water.

[0051] The preparation method of the chemical silver plating solution on the copper surface is as follows:

[0052] Silver (II) pyridine-2-carboxylate is first added, then malic acid, aminosulfonic acid, ammonium perfluorooctanesulfonate, 2-mercaptobenzothiazole and deionized water are added, and finally formic acid is added to obtain a copper surface chemical silver plating solution.

[0053] Example 3

[0054] The electroless silver plating solution on copper surface is: 50g / L silver (II) pyridine-2-carboxylate, 5g / L malic acid as a complexing agent, 10mL / L sulfamic acid as an organic acid, 4g / L ammonium perfluorooctanesulfonate as a surfactant, 2g / L formic acid as an accelerator, 24g / L benzotriazole as a corrosion inhibitor, and deionized water.

[0055] The preparation method of the chemical silver plating solution on the copper surface is as follows:

[0056] First, silver (II) pyridine-2-carboxylate is added, followed by malic acid, aminosulfonic acid, ammonium perfluorooctanesulfonate, benzotriazole and deionized water, and finally formic acid is added to obtain a chemical silver plating solution on the copper surface.

[0057] Example 4

[0058] The electroless silver plating solution on copper surface is: 100g / L silver (II) pyridine-2-carboxylate, 5g / L malic acid (chelating agent), 10mL / L sulfamic acid (organic acid), 4g / L ammonium perfluorooctanesulfonate (surfactant), 2g / L sodium hypophosphite (accelerator), 24g / L benzotriazole (corrosion inhibitor), and deionized water.

[0059] The preparation method of the chemical silver plating solution on the copper surface is as follows:

[0060] First, silver (II) pyridine-2-carboxylate is added, followed by malic acid, aminosulfonic acid, ammonium perfluorooctanesulfonate, benzotriazole and deionized water, and finally sodium hypophosphite is added to obtain a chemical silver plating solution on the copper surface.

[0061] Application Example 1

[0062] Copper substrate processing:

[0063] 1. First, place the substrate in a degreasing solution (15 mL / L sulfuric acid + 12 g / L malic acid + 0.05 g / L sodium dodecylbenzenesulfonate) and soak it at 45°C for 5 minutes. After taking it out, rinse it twice with deionized water, each time for 1 minute.

[0064] 2. Soak in the micro-etching tank for 3 minutes for micro-etching treatment. After taking out, rinse twice with deionized water, each time for 1 minute. The solution used for micro-etching treatment is a mixed solution of sulfuric acid 10mL / L + hydrogen peroxide 1g / L + 1,4-butanediol 1g / L;

[0065] 3. Soak the micro-etched copper substrate in 7.5 mL / L methanesulfonic acid for 2 minutes;

[0066] The treated copper substrate was immersed in the copper surface chemical silver plating solution prepared in Example 1 at 40° C. for 6 min. After being taken out, it was washed twice with deionized water, each time for 1 min, to obtain a silver plating layer.

[0067] The silver coating prepared in Example 1 was analyzed using an optical microscope. It was found that there was no undercut at the junction of the circuit and the green oil (undercut), and the thickness of the immersion silver was 1 μm.

[0068] Application Example 2

[0069] On the basis of Application Example 1, the copper surface chemical silver plating solution in Example 1 was replaced with the copper surface chemical silver plating solution in Example 2 to obtain a silver plating layer.

[0070] The silver coating prepared in Example 2 was analyzed using an optical microscope, and it was found that there was no undercut at the junction of the circuit and the green oil, and the thickness of the immersion silver was 1.5 μm.

[0071] Application Example 3

[0072] On the basis of Application Example 1, the copper surface chemical silver plating solution in Example 1 was replaced with the copper surface chemical silver plating solution in Example 3 to obtain a silver plating layer.

[0073] The silver coating prepared in Example 3 was analyzed using an optical microscope. It was found that there was no undercut at the junction of the circuit and the green oil (undercut), and the thickness of the immersion silver was 5 μm.

[0074] Application Example 4

[0075] On the basis of Application Example 1, the copper surface chemical silver plating solution in Example 1 was replaced with the copper surface chemical silver plating solution in Example 4 to obtain a silver plating layer.

[0076] The silver coating prepared in Example 4 was analyzed using an optical microscope. It was found that there was no undercut at the junction of the circuit and the green oil (undercut), and the thickness of the immersion silver was 20 μm.

[0077] Comparative Example 1

[0078] The electroless silver plating solution for copper surface is: 1 g / L silver nitrate, 5 g / L 3-methylpyridine, 10 mL / L sulfamic acid, 0.8 g / L perfluorooctanesulfonic acid, 2 g / L formic acid, 5 g / L 2-mercaptobenzothiazole, and deionized water.

[0079] The preparation method of the chemical silver plating solution on the copper surface is as follows:

[0080] Silver nitrate is first added, then citric acid, 3-methylpyridine, ammonium perfluorooctanesulfonate, 2-mercaptobenzothiazole and deionized water are added, and finally formic acid is added to obtain a copper surface chemical silver plating solution.

[0081] Comparative Application Example 1

[0082] On the basis of Application Example 1, the copper surface chemical silver plating solution in Example 1 was replaced with the copper surface chemical silver plating solution in Comparative Example 1 to obtain a silver plating layer.

[0083] The silver plating obtained in Comparative Application Example 1 was analyzed using an optical microscope, and it was found that there was slight undercut at the junction of the circuit and the green oil, and the thickness of the immersion silver was 0.2 μm.

[0084] Comparative Example 2

[0085] The electroless silver plating solution for copper surface is: silver nitrate 1g / L, complexing agent 2-aminopyridine 5g / L, organic acid aminosulfonic acid 10mL / L, surfactant ammonium perfluorooctanesulfonate 0.8g / L, accelerator formic acid 2g / L, corrosion inhibitor 2-mercaptobenzothiazole 5g / L and deionized water;

[0086] The preparation method of the chemical silver plating solution on the copper surface is as follows:

[0087] Silver nitrate is first added, then 2-aminopyridine, aminosulfonic acid, ammonium perfluorooctanesulfonate, 2-mercaptobenzothiazole and deionized water are added, and finally formic acid is added to obtain a copper surface chemical silver plating solution.

[0088] Comparative Application Example 2

[0089] On the basis of Application Example 1, the copper surface chemical silver plating solution in Example 1 was replaced with the copper surface chemical silver plating solution of Comparative Example 2 to obtain a silver plating layer.

[0090] The silver plating prepared in Comparative Application Example 2 was analyzed using an optical microscope, and it was found that there was slight undercut at the junction of the circuit and the green oil (undercut), and the thickness of the immersion silver was 0.1 μm.

[0091] It can be seen from the above comparative examples and embodiments that the silver plating solution provided by the present invention can solve the problems of thin silver thickness and side corrosion caused by strong acid corrosion of the copper surface in chemical silver plating in the prior art.

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A copper surface chemical silver plating solution, comprising 0.1-100 g / L of silver (II) pyridine-2-carboxylate, 0.1-10 g / L of a complexing agent, 0.1-100 mL / L of an organic acid, 0.5-10 g / L of a surfactant, 0.2-8 g / L of an accelerator, 5-100 g / L of a corrosion inhibitor, and water; The complexing agent is at least one of ethylenediamine, picoline, aminopyridine, glycine, malic acid, triethanolamine, acetic acid, ethylenediaminetetraacetic acid, lactic acid, aminosalicylic acid, diethylenetriamine, triethylenetetramine, triammonium citrate and sulfosalicylic acid; The organic acid is at least one of methanesulfonic acid, aminosulfonic acid and trifluoroacetic acid.

2. The copper surface chemical silver plating solution according to claim 1, wherein The preparation method comprises 1~50g / L of silver (II) pyridine-2-carboxylate, 1~8g / L of complexing agent, 5~50mL / L of organic acid, 1~8g / L of surfactant, 1~6g / L of accelerator, 10~50g / L of corrosion inhibitor and water.

3. The copper surface chemical silver plating solution according to claim 1 or 2, characterized in that The surfactant includes at least one of a carboxylate fluorocarbon surfactant, a sulfonate fluorocarbon surfactant, a phosphate fluorocarbon surfactant, a quaternary ammonium salt fluorocarbon surfactant and a nonionic fluorine-based surfactant.

4. The copper surface chemical silver plating solution according to claim 1 or 2, characterized in that The accelerator includes at least one of formic acid, formaldehyde, acetaldehyde, sodium hypophosphite and glucose.

5. The copper surface chemical silver plating solution according to claim 1 or 2, characterized in that The corrosion inhibitor includes at least one of benzotriazole, 2-mercaptobenzothiazole, 2-amino-5-mercapto-1,3,4-thiadiazole, 2-mercaptothiazoline and 5-mercapto-1-phenyltetrazole.

6. The method for preparing the copper surface chemical silver plating solution according to any one of claims 1 to 5, comprising the steps of: (1) mixing silver (II) pyridine-2-carboxylate, a complexing agent, an organic acid, a surfactant, a corrosion inhibitor, and water to obtain a mixed solution; (2) The mixed solution obtained in step (1) is mixed with an accelerator to obtain a copper surface chemical silver plating solution.

7. A method for using the copper surface chemical silver plating solution according to any one of claims 1 to 5 or the copper surface chemical silver plating solution prepared by the preparation method according to claim 6, comprising the following steps: The copper substrate is immersed in a copper surface chemical silver plating solution.

8. A silver plating layer prepared by the method according to claim 7.