Non-cyanide copper plating crystal grain refinement agent, non-cyanide copper plating solution, preparation method thereof and application

Abstract

The present invention relates to a grain refinement agent for non-cyanide copper plating. The grain refinement agent for non-cyanide copper plating contains water, N-methylpiperazine dissolved in water, and 2-methyltetrahydrofuran. The concentration of N-methylpiperazine in the grain refinement agent for non-cyanide copper plating is (0.1 to 0.5) g / L, and the concentration of 2-methyltetrahydrofuran in the grain refinement agent for non-cyanide copper plating is (1 to 5) g / L. By adding the above-mentioned grain refinement agent for non-cyanide copper plating to the base plating solution to form a non-cyanide copper plating solution, the dispersibility and glossiness of the copper plating layer in the copper plating product can be significantly improved, achieving and even exceeding the effects of the conventional cyanide copper plating process, and there is a possibility of replacing the cyanide copper plating process, which promotes the development of the non-cyanide copper plating process.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytic copper plating, and particularly relates to a cyanide-free copper plating crystal grain refinement agent, a cyanide-free copper plating solution, a preparation method thereof, and an application.

Background Art

[0002] Electrolytic plating is a process of plating a thin layer of another metal or alloy on the surface of a specific metal by utilizing the electrolysis principle, and is a process of attaching a metal film to the surface of a part manufactured by a metal or other material by utilizing the electrolysis action. It plays a role in preventing the oxidation of the metal and can also play a role in improving wear resistance, electrical conductivity, reflectivity, corrosion resistance, etc. The process of electrolytic plating is basically as follows. The plating metal is at the anode, the material to be plated is at the cathode, the cathode and the anode are placed in an electrolyte solution (i.e., plating solution), and after being energized by a DC power supply, the metal at the anode is oxidized (loses electrons), and the positive ions in the solution are reduced to atoms at the cathode (gain electrons) and adhere to the surface layer of the cathode.

[0003] Copper cyanide plating is a common electrolytic copper plating process. The plating solution uses sodium cyanide as a complexing agent to complex copper ions to form a copper cyanide complex. Its composition mainly consists of a copper cyanide complex and a certain amount of free cyanide compounds. It shows strong alkalinity, has strong activation ability and complexing ability, has excellent uniform plating ability and coating ability, and can form a copper plating layer with good bonding force on a plurality of metal substrates such as steel and zinc alloy. The surface of the plating layer obtained by copper cyanide plating has good glossiness, crystallinity and dispersibility.

[0004] Copper cyanide plating has good electrolytic plating effects. However, due to the high toxicity of cyanide compounds, the wastewater and exhaust gas generated in the copper cyanide plating process both require strict treatment. To solve this problem, numerous studies have been conducted to search for a non-toxic plating solution that does not contain cyanide compounds. By using this plating solution, cyanide-free copper plating can be achieved instead of the conventional copper cyanide plating process. However, in the technologies developed so far, compared with the copper cyanide plating process, the copper plating layer formed by electrolytic plating in the cyanide-free copper plating process is inferior in terms of glossiness and dispersibility, and it has been difficult to replace the conventional copper cyanide plating process.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of such a situation, it is necessary to provide a cyanide-free copper plating crystal grain refiner that can be applied to the cyanide-free copper plating process as an important component of the cyanide-free copper plating solution and can improve the dispersibility and glossiness of the copper plating layer.

[0006] Furthermore, it is necessary to provide a cyanide-free copper plating solution, its preparation method, and its application.

Means for Solving the Problems

[0007] One embodiment of the present invention provides a cyanide-free copper plating crystal grain refiner, which includes water, N-methylpiperazine dissolved in the water, and 2-methyltetrahydrofuran. The concentration of N-methylpiperazine in the cyanide-free copper plating crystal grain refiner is (0.1 - 0.5) g / L, and the concentration of 2-methyltetrahydrofuran in the cyanide-free copper plating crystal grain refiner is (1 - 5) g / L.

[0008] In one embodiment, the concentration of N-methylpiperazine in the non-cyanide copper plating crystal grain refiner may be (0.1 to 0.3) g / L, and the concentration of 2-methyltetrahydrofuran in the non-cyanide copper plating crystal grain refiner may be (1 to 3) g / L.

[0009] One embodiment of the present invention provides a non-cyanide copper plating solution, which includes a base plating solution, N-methylpiperazine and 2-methyltetrahydrofuran dissolved in the base plating solution, wherein the concentration of N-methylpiperazine in the non-cyanide copper plating solution is (0.5 to 30) mg / L, the concentration of 2-methyltetrahydrofuran in the non-cyanide copper plating solution is (5 to 300) mg / L, and the solvent of the base plating solution is water.

[0010] In one embodiment, the concentration of N-methylpiperazine in the non-cyanide copper plating solution may be (0.8 to 25) mg / L, and the concentration of 2-methyltetrahydrofuran in the non-cyanide copper plating solution may be (8 to 250) mg / L.

[0011] In one embodiment, the base plating solution contains at least one of basic copper carbonate, potassium sodium tartrate, citric acid and sodium carbonate.

[0012] In one embodiment, the base plating solution contains basic copper carbonate, potassium sodium tartrate, citric acid and sodium carbonate, Optionally, the concentration of basic copper carbonate in the base plating solution is (50 to 60) g / L, Optionally, the concentration of potassium sodium tartrate in the base plating solution is (20 to 40) g / L, Optionally, the concentration of citric acid in the base plating solution is (250 to 300) g / L, Optionally, the concentration of sodium carbonate in the base plating solution may be (10 to 15) g / L.

[0013] One embodiment of the present invention is a method for preparing a non-cyanide copper plating solution described in any of the above embodiments, wherein a method for preparing a non-cyanide copper plating solution is further provided, which includes a step of mixing the N-methylpiperazine and the 2-methyltetrahydrofuran with the base plating solution.

[0014] In one embodiment, the above method includes a step of dissolving the N-methylpiperazine and the 2-methyltetrahydrofuran in water to prepare a non-cyanide copper plating crystal grain refiner described in any of the above embodiments, and a step of mixing the non-cyanide copper plating crystal grain refiner with the base plating solution.

[0015] One embodiment of the present invention further provides an electroplating method, which includes a step of preparing a non-cyanide copper plating solution, and a step of placing a material to be plated in the non-cyanide copper plating solution to electroplate a copper layer, and the non-cyanide copper plating solution may be the non-cyanide copper plating solution described in any of the above embodiments.

[0016] One embodiment of the present invention further provides a copper-plated product, and the electroplating process may include the steps of the electroplating method described in any of the above embodiments, or the step of performing electroplating using the non-cyanide copper plating solution described in any of the above embodiments.

[0017] The above non-cyanide copper plating crystal grain refiner contains N-methylpiperazine and 2-methyltetrahydrofuran. By adding them to the base plating solution to form a non-cyanide copper plating solution, the dispersibility and glossiness of the copper plating layer in the copper-plated product can be significantly improved, achieving and even exceeding the effects of the conventional cyanide copper plating process. It is expected to promote the development of the non-cyanide copper plating process to replace the cyanide copper plating process.

Embodiments for Carrying out the Invention

[0018] To facilitate the understanding of the present invention, the present invention will be described in more detail below with reference to embodiments. In the present invention, preferred embodiments are shown. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of presenting these embodiments is to make the understanding of the disclosure of the present invention clearer and more detailed.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the associated items.

[0020] One embodiment of the present invention is a cyanide-free copper plating crystal grain refiner, which includes water, N-methylpiperazine dissolved in water, and 2-methyltetrahydrofuran. The concentration of N-methylpiperazine in the cyanide-free copper plating crystal grain refiner is (0.1 to 0.5) g / L, and the concentration of 2-methyltetrahydrofuran in the cyanide-free copper plating crystal grain refiner is (1 to 5) g / L. A cyanide-free copper plating crystal grain refiner is provided.

[0021] The structural formula of N-methylpiperazine is as follows.

[0022]

Chemical formula

[0023] N-methylpiperazine is also called 1-methylpiperazine. It is a colorless and odorless transparent liquid, with a melting point of -6°C, soluble in water, and showing alkalinity in aqueous solution.

[0024] The structural formula of 2-methyltetrahydrofuran is as follows.

[0025]

Chem.

[0026] 2-Methyltetrahydrofuran has a melting point of -136 °C, is a colorless transparent liquid, and has a certain solubility in water.

[0027] Both N-methylpiperazine and 2-methyltetrahydrofuran are important organic synthesis intermediates. Mixing them at a specific concentration forms a cyanide copper plating crystal grain refiner, and adding them to the base plating solution of cyanide copper plating makes them an important component of the cyanide copper plating solution. Using the cyanide copper plating process, the compactness of the crystal of the copper plating layer on the surface of the workpiece to be plated can be significantly improved. The crystal grains of the copper plating layer can be further refined, and the crystal grains can be uniformly dispersed around the surface of the workpiece to be plated, with higher dispersibility. The roughness of the entire copper plating layer can be reduced, which is beneficial for improving the glossiness of the copper plating layer.

[0028] Furthermore, in one embodiment of the present invention, the concentration of N-methylpiperazine in the cyanide copper plating crystal grain refiner is (0.1 - 0.5) g / L. The concentration of N-methylpiperazine in the cyanide copper plating crystal grain refiner may be, for example, 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, etc., but is not limited thereto. Preferably, the concentration of N-methylpiperazine in the cyanide copper plating crystal grain refiner is (0.1 - 0.3) g / L.

[0029] Furthermore, in one embodiment of the present invention, the concentration of 2-methyltetrahydrofuran in the non-cyanide copper plating crystal grain refiner is (1 to 5) g / L. The concentration of 2-methyltetrahydrofuran in the non-cyanide copper plating crystal grain refiner may be, for example, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, etc., but is not limited thereto. Preferably, the concentration of 2-methyltetrahydrofuran in the non-cyanide copper plating crystal grain refiner is (1 to 3) g / L.

[0030] Preferably, the water is distilled water.

[0031] One embodiment of the present invention provides a non-cyanide copper plating solution, which comprises a base plating solution, N-methylpiperazine and 2-methyltetrahydrofuran dissolved in the base plating solution, wherein the concentration of N-methylpiperazine in the non-cyanide copper plating solution is (0.5 to 30) mg / L, the concentration of 2-methyltetrahydrofuran in the non-cyanide copper plating solution is (5 to 300) mg / L, and the solvent of the base plating solution is water. By adding N-methylpiperazine and 2-methyltetrahydrofuran to the base plating solution to form a non-cyanide copper plating solution, both N-methylpiperazine and 2-methyltetrahydrofuran can refine the crystal grains of the copper plating layer within a specific concentration range, which is advantageous for improving the dispersibility of the crystals of the copper plating layer and making the glossiness of the copper plating layer better.

[0032] Furthermore, in one embodiment of the present invention, the concentration of N-methylpiperazine in the non-cyanide copper plating solution may be, for example, 0.5 mg / L, 1 mg / L, 1.5 mg / L, 2 mg / L, 2.5 mg / L, 3 mg / L, 3.5 mg / L, 4 mg / L, 4.5 mg / L, 5 mg / L, 5.5 mg / L, 6 mg / L, 6.5 mg / L, 7 mg / L, 7.5 mg / L, 8 mg / L, 8.5 mg / L, 9 mg / L, 9.5 mg / L, 10 mg / L, 10.5 mg / L, 11 mg / L, 11.5 mg / L, 12 mg / L, 12.5 mg / L, 13 mg / L, 13.5 mg / L, 14 mg / L, 14.5 mg / L, 15 mg / L, 15.5 mg / L, 16 mg / L, 16.5 mg / L, 17 mg / L, 17.5 mg / L, 18 mg / L, 18.5 mg / L, 19 mg / L, 19.5 mg / L, 20 mg / L, 20.5 mg / L, 21 mg / L, 21.5 mg / L, 22 mg / L, 22.5 mg / L, 23 mg / L, 23.5 mg / L, 24 mg / L, 24.5 mg / L, 25 mg / L, 25.5 mg / L, 26 mg / L, 26.5 mg / L, 27 mg / L, 27.5 mg / L, 28 mg / L, 28.5 mg / L, 29 mg / L, 29.5 mg / L, 30 mg / L, etc., but is not limited thereto. Preferably, the concentration of N-methylpiperazine in the non-cyanide copper plating solution is (0.8 to 25) mg / L.

[0033] Furthermore, in one embodiment of the present invention, the concentration of 2-methyltetrahydrofuran in the non-cyanide copper plating solution may be, for example, 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, 40 mg / L, 45 mg / L, 50 mg / L, 55 mg / L, 60 mg / L, 65 mg / L, 70 mg / L, 75 mg / L, 80 mg / L, 85 mg / L, 90 mg / L, 95 mg / L, 100 mg / L, 105 mg / L, 110 mg / L, 115 mg / L, 120 mg / L, 125 mg / L, 130 mg / L, 135 mg / L, 140 mg / L, 145 mg / L, 150 mg / L, 155 mg / L, 160 mg / L, 165 mg / L, 170 mg / L, 175 mg / L, 180 mg / L, 185 mg / L, 190 mg / L, 195 mg / L, 200 mg / L, 205 mg / L, 210 mg / L, 215 mg / L, 220 mg / L, 225 mg / L, 230 mg / L, 235 mg / L, 240 mg / L, 245 mg / L, 250 mg / L, 255 mg / L, 260 mg / L, 265 mg / L, 270 mg / L, 275 mg / L, 280 mg / L, 285 mg / L, 290 mg / L, 295 mg / L, 300 mg / L, etc., but is not limited thereto. Preferably, the concentration of 2-methyltetrahydrofuran in the non-cyanide copper plating solution is (8 - 250) mg / L.

[0034] Note that the composition of the base plating solution is a normal composition in the non-cyanide copper plating process. For example, the base plating solution contains at least one of basic copper carbonate, potassium sodium tartrate, citric acid, and sodium carbonate.

[0035] Furthermore, the base plating solution may simultaneously contain basic copper carbonate, potassium sodium tartrate, citric acid, and sodium carbonate. Preferably, the concentration of basic copper carbonate in the base plating solution may be, for example, (50 to 60) g / L. Preferably, the concentration of potassium sodium tartrate in the base plating solution may be, for example, (20 to 40) g / L. Preferably, the concentration of citric acid in the base plating solution may be, for example, (250 to 300) g / L. Preferably, the concentration of sodium carbonate in the base plating solution may be, for example, (10 to 15) g / L.

[0036] One embodiment of the present invention further provides a method for preparing a non-cyanide copper plating solution according to any of the above embodiments, the method comprising: It may include the step of mixing N-methylpiperazine and 2-methyltetrahydrofuran with the base plating solution.

[0037] In addition, the charging masses of both can be directly calculated from the concentrations of N-methylpiperazine and 2-methyltetrahydrofuran in the non-cyanide copper plating solution, weighed at a specific charging mass, and then directly added to the base plating solution for non-cyanide copper plating and mixed to form a non-cyanide copper plating solution.

[0038] In addition, N-methylpiperazine and 2-methyltetrahydrofuran may be mixed with a solvent to prepare a preparation in advance, and the preparation may be added to the base plating solution during electrolytic plating and mixed to form a non-cyanide copper plating solution. In addition, N-methylpiperazine and 2-methyltetrahydrofuran may be mixed with a solvent to prepare a preparation in advance, and the preparation can be sold as a single product. In addition, the preparation prepared in advance by mixing N-methylpiperazine and 2-methyltetrahydrofuran with a solvent may be, for example, a non-cyanide copper plating crystal grain refiner according to one embodiment of the present invention, but is not limited thereto.

[0039] In addition, the method for preparing a non-cyanide copper plating solution according to one embodiment of the present invention may further include the following steps 1 to 2.

[0040] In step 1, N-methylpiperazine and 2-methyltetrahydrofuran are dissolved in water to prepare the cyanide-free copper plating crystal grain refiner according to the above embodiment.

[0041] In step 2, the cyanide-free copper plating crystal grain refiner is mixed with the base plating solution.

[0042] One embodiment of the present invention further provides an electroplating method, which method includes: step 1 of preparing a cyanide-free copper plating solution; and step 2 of putting the material to be plated into the cyanide-free copper plating solution and electroplating a copper layer.

[0043] The cyanide-free copper plating solution may be, for example, the cyanide-free copper plating solution described in any of the above embodiments.

[0044] The material to be plated may be made of, for example, materials such as iron and zinc.

[0045] One embodiment of the present invention further provides a copper-plated product, and the electroplating process may include the steps of the electroplating method described in any of the above embodiments, or the step of performing electroplating using the cyanide-free copper plating solution described in any of the above embodiments.

[0046] First, N-methylpiperazine and 2-methyltetrahydrofuran are prepared into a cyanide-free copper plating crystal grain refiner. Next, the cyanide-free copper plating crystal grain refiner is added to a base plating solution to form a cyanide-free copper plating solution. Alternatively, N-methylpiperazine and 2-methyltetrahydrofuran are directly mixed with the base plating solution to form a cyanide-free copper plating solution. Using the cyanide-free copper plating solution, a copper layer is electrolytically plated on a material to be plated by a cyanide-free copper plating process. Thereby, the crystal grains of the copper plating layer become finer, the dispersibility becomes higher, and further, the surface of the copper plating layer is smoother and more lustrous. The electrolytic plating effect can achieve and even exceed the effect of the conventional copper cyanide plating process. Also, since highly toxic reagents such as cyanide compounds are not added, it is more environmentally friendly and safe, and it is expected to promote the development of the cyanide-free copper plating process to replace the copper cyanide plating process.

Example

[0047] Specific examples are shown below. (Example 1)

[0048] Step 1: Preparation of cyanide-free copper plating crystal grain refiner Weigh 1 g of N-methylpiperazine and 10 g of 2-methyltetrahydrofuran respectively, dissolve them in distilled water, stir until the solution becomes clear, then add distilled water to make the volume up to 10 L, continue stirring, and uniformly mix N-methylpiperazine and 2-methyltetrahydrofuran in distilled water. After preparation, the concentration of N-methylpiperazine in the cyanide-free copper plating crystal grain refiner is 0.1 g / L, and the concentration of 2-methyltetrahydrofuran in the cyanide-free copper plating crystal grain refiner is 1 g / L.

[0049] Step 2: Preparation of cyanide-free copper plating solution Take 1 L of the base plating solution. The solvent of the base plating solution is distilled water, and the base plating solution contains basic copper carbonate with a concentration of 40 g / L, potassium sodium tartrate with a concentration of 30 g / L, citric acid with a concentration of 280 g / L, and sodium carbonate with a concentration of 13 g / L.

[0050] Next, add 10 mL of the cuprous cyanide plating grain refinement agent prepared in Step 1 to the base plating solution and stir until uniform.

[0051] Step 3: Electroplating Immerse the iron workpiece to be plated in the cuprous cyanide plating solution prepared in Step 2 and perform electroplating for 30 minutes under the conditions of a current density of 1 A / dm 2 and a temperature of 55°C. (Example 2)

[0052] Step 1: Preparation of cuprous cyanide plating grain refinement agent Weigh 3 g of N-methylpiperazine and 30 g of 2-methyltetrahydrofuran respectively, dissolve them in distilled water, stir until the solution becomes clear, then add distilled water to make the volume up to 10 L, continue stirring, and uniformly mix N-methylpiperazine and 2-methyltetrahydrofuran in distilled water. After completion of the preparation, the concentration of N-methylpiperazine in the cuprous cyanide plating grain refinement agent is 0.3 g / L, and the concentration of 2-methyltetrahydrofuran in the cuprous cyanide plating grain refinement agent is 3 g / L.

[0053] Step 2: Preparation of cuprous cyanide plating solution Take 1 L of the base plating solution. The solvent of the base plating solution is distilled water, and the base plating solution contains basic copper carbonate with a concentration of 40 g / L, potassium sodium tartrate with a concentration of 30 g / L, citric acid with a concentration of 280 g / L, and sodium carbonate with a concentration of 13 g / L.

[0054] Next, add 30 mL of the cuprous cyanide plating grain refinement agent prepared in Step 1 to the base plating solution and stir until uniform.

[0055] Step 3: Electroplating Immerse the iron workpiece to be plated in the cuprous cyanide plating solution prepared in Step 2 and perform electroplating for 30 minutes under the conditions of a current density of 1 A / dm 2 and a temperature of 55°C. (Example 3)

[0056] Step 1: Preparation of a grain-refining agent for non-cyanide copper plating Weigh 5 g of N-methylpiperazine and 50 g of 2-methyltetrahydrofuran respectively, dissolve them in distilled water, stir until the solution becomes clear, then add distilled water to make a constant volume of 10 L, continue stirring to uniformly mix N-methylpiperazine and 2-methyltetrahydrofuran in distilled water. After completion of the preparation, the concentration of N-methylpiperazine in the non-cyanide copper plating grain-refining agent is 0.5 g / L, and the concentration of 2-methyltetrahydrofuran in the non-cyanide copper plating grain-refining agent is 5 g / L.

[0057] Step 2: Preparation of a non-cyanide copper plating solution Take 1 L of the base plating solution, with the solvent of the base plating solution being distilled water. The base plating solution contains basic copper carbonate with a concentration of 40 g / L, potassium sodium tartrate with a concentration of 30 g / L, citric acid with a concentration of 280 g / L, and sodium carbonate with a concentration of 13 g / L.

[0058] Next, add 50 mL of the non-cyanide copper plating grain-refining agent prepared in Step 1 to the base plating solution and stir until it becomes uniform.

[0059] Step 3: Electroplating Immerse the iron workpiece to be plated in the non-cyanide copper plating solution prepared in Step 2, and perform electroplating for 30 minutes under the conditions of a current density of 1 A / dm 2 and a temperature of 55 °C. (Comparative Example 1)

[0060] Step 1: Preparation of a cyanide copper plating solution Take 1 L of the cyanide copper plating solution, with the solvent of the cyanide copper plating solution being distilled water. The cyanide copper plating solution contains basic copper carbonate with a concentration of 40 g / L, potassium sodium tartrate with a concentration of 30 g / L, citric acid with a concentration of 280 g / L, sodium carbonate with a concentration of 13 g / L, cuprous cyanide with a concentration of 30 g / L, and sodium cyanide with a concentration of 50 g / L.

[0061] Step 2: Electroplating Immerse the iron substrate to be plated in the copper cyanide plating solution prepared in Step 1, and perform electroplating for 30 minutes under the conditions of a current density of 1 A / dm 2 and a temperature of 55°C. (Comparative Example 2)

[0062] Step 1: Preparation of non-cyanide copper plating solution Take 1 L of the base plating solution, where the solvent of the base plating solution is distilled water, and the base plating solution contains basic copper carbonate with a concentration of 40 g / L, potassium sodium tartrate with a concentration of 30 g / L, citric acid with a concentration of 280 g / L, and sodium carbonate with a concentration of 13 g / L.

[0063] Step 2: Electroplating Immerse the iron substrate to be plated in the non-cyanide copper plating solution prepared in Step 1, and perform electroplating for 30 minutes under the conditions of a current density of 1 A / dm 2 and a temperature of 55°C.

[0064] Compare the copper plating layers of the iron substrates to be plated in Examples 1 to 3 after electroplating with the copper plating layers of the iron substrates to be plated in Comparative Examples 1 to 2 after electroplating, and the comparison results are as follows.

[0065] When comparing Example 1 with Comparative Examples 1 to 2, the roughness of the copper plating layer of the iron substrate in Example 1 < the roughness of the copper plating layer of the iron substrate in Comparative Example 1 < the roughness of the copper plating layer of the iron substrate in Comparative Example 2.

[0066] When comparing Example 2 with Comparative Examples 1 to 2, the roughness of the copper plating layer of the iron substrate in Example 2 < the roughness of the copper plating layer of the iron substrate in Comparative Example 1 < the roughness of the copper plating layer of the iron substrate in Comparative Example 2.

[0067] When comparing Example 3 with Comparative Examples 1 and 2, the roughness of the copper plating layer of the iron workpiece to be plated in Example 3 = the roughness of the copper plating layer of the iron workpiece to be plated in Comparative Example 1 < the roughness of the copper plating layer of the iron workpiece to be plated in Comparative Example 2.

[0068] Therefore, N-methylpiperazine and 2-methyltetrahydrofuran are added to the base plating solution to form a non-cyanide copper plating solution, which is applied to the non-cyanide copper plating process. It can be concluded that the roughness of the copper plating layer in the electroplated product is weaker, smoother, has better dispersibility and glossiness, and its effect reaches and even exceeds the effect of cyanide copper plating.

[0069] The technical features of the above embodiments can be arbitrarily combined. For the sake of brevity, not all possible combinations of the technical features in the above-described embodiments have been described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0070] The above embodiments merely show some embodiments of the present invention, and their descriptions are more specific and detailed, but do not limit the scope of the claims. A person skilled in the art can make some modifications and improvements without departing from the idea of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention is based on the scope of the claims.

Claims

1. A cyanide-free copper plating crystal grain refiner, comprising water, N-methylpiperazine dissolved in the water, and 2-methyltetrahydrofuran, wherein the concentration of the N-methylpiperazine in the cyanide-free copper plating crystal grain refiner is (0.1 to 0.5) g / L, and the concentration of the 2-methyltetrahydrofuran in the cyanide-free copper plating crystal grain refiner is (1 to 5) g / L. A cyanide-free copper plating crystal grain refiner characterized by this.

2. The concentration of the N-methylpiperazine in the cyanide-free copper plating crystal grain refiner is (0.1 to 0.3) g / L, and the concentration of the 2-methyltetrahydrofuran in the cyanide-free copper plating crystal grain refiner is (1 to 3) g / L. The cyanide-free copper plating crystal grain refiner according to Claim 1, characterized by this.

3. A cyanide-free copper plating solution, comprising a base plating solution, N-methylpiperazine dissolved in the base plating solution, and 2-methyltetrahydrofuran, wherein the concentration of the N-methylpiperazine in the cyanide-free copper plating solution is (0.5 to 30) mg / L, the concentration of the 2-methyltetrahydrofuran in the cyanide-free copper plating solution is (5 to 300) mg / L, and the solvent of the base plating solution is water. A cyanide-free copper plating solution characterized by this.

4. The concentration of the N-methylpiperazine in the cyanide-free copper plating solution is (0.8 to 25) mg / L, and the concentration of the 2-methyltetrahydrofuran in the cyanide-free copper plating solution is (8 to 250) mg / L. The cyanide-free copper plating solution according to Claim 3.

5. The base plating solution contains at least one of basic copper carbonate, potassium sodium tartrate, citric acid, and sodium carbonate. The cyanide-free copper plating solution according to Claim 3 or 4, characterized by this.

6. The base plating solution contains basic copper carbonate, potassium sodium tartrate, citric acid, and sodium carbonate, Optionally, the concentration of the basic copper carbonate in the base plating solution is (50 to 60) g / L, Optionally, the concentration of the potassium sodium tartrate in the base plating solution is (20 to 40) g / L, Optionally, the concentration of the citric acid in the base plating solution is (250 to 300) g / L, Optionally, the concentration of the sodium carbonate in the base plating solution is (10 to 15) g / L, and the non-cyanide copper plating solution according to claim 5 is characterized in that.

7. A method for preparing a non-cyanide copper plating solution according to any one of claims 3 to 6, The method for preparing a non-cyanide copper plating solution is characterized by including a step of mixing the N-methylpiperazine and the 2-methyltetrahydrofuran with the base plating solution.

8. A step of dissolving the N-methylpiperazine and the 2-methyltetrahydrofuran in water to prepare the non-cyanide copper plating crystal grain refiner according to claim 1; The method for preparing a non-cyanide copper plating solution according to claim 7 is characterized by including a step of mixing the non-cyanide copper plating crystal grain refiner with the base plating solution.

9. A step of preparing a non-cyanide copper plating solution; A step of putting a material to be plated into the non-cyanide copper plating solution and electrolytically plating a copper layer, and The non-cyanide copper plating solution is the non-cyanide copper plating solution according to any one of claims 3 to 6, and the electrolytic plating method is characterized in that.

10. The electroplating process includes the steps of the electroplating method according to claim 9, or the step of performing electroplating using the non-cyanide copper plating solution according to any one of claims 3 to 6, and the copper plating product is characterized in that.

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