High-stability chemical copper plating solution and preparation method thereof

Abstract

The invention relates to the technical field of chemical copper plating, in particular to a high-stability chemical copper plating solution and a preparation method thereof. The invention relates to a high-stability chemical copper plating solution, which comprises the following preparation raw materials by mass concentration: 12-20 g / L of copper sulfate pentahydrate, 24-30 g / L of a reducing agent, 40-45 g / L of a complexing agent, 20-25 g / L of a buffer agent, 0.45-0.55 g / L of a stabilizer, 2-3 g / L of an accelerator, and 0.010-0.013 g / L of a surfactant, and the reducing agent is composed of sodium hypophosphite and pyrrolidine tetrafluoroborate according to a mass ratio of 3: 4. According to the high-stability chemical copper plating solution, the high deposition rate is ensured, meanwhile, the excellent stability is achieved, the maintenance frequency is reduced, the service life of the chemical copper plating solution is prolonged, the decomposition time of the plating solution is prolonged, and the production efficiency is improved while the good quality of a copper deposition layer is obtained.

Description

Technical Field

[0001] The present application relates to the technical field of chemical copper plating, and in particular to a high-stability chemical copper plating solution and a preparation method thereof. Background Art

[0002] PCB chemical copper plating is a self-catalytic redox reaction. A thin layer of chemical copper is chemically deposited on the wall of the non-conductive hole metallization product that has been drilled. As the base for electroplated copper, chemical copper plating accounts for 20%-35% of the cost of the copper plating process.

[0003] The basic components of PCB chemical copper plating solution are: copper salt, complexing agent, reducing agent and additives. The copper salt is CuSO4·5H2O. The commonly used reducing agent is formaldehyde. The reducing ability of formaldehyde increases with the increase of pH value, so NaOH needs to be added to maintain the pH value. The complexing agent is a multi-component complexing agent system of ethylenediaminetetraacetic acid (EDTA), potassium sodium tartrate and triethanolamine. One is to reduce the amount of EDTA and reduce costs, and the other is to improve the stability of the plating solution and improve the quality of the coating.

[0004] The process flow of PCB chemical copper deposition is: bulking - degumming - pre-neutralization - neutralization - water washing for hole filling - micro-etching - pre-dip - activation - acceleration - copper deposition. Except for the process from pre-dip to activation, water washing is required after the other processes. Chemical copper deposition is the last step of chemical copper deposition for circuit boards and is the key to ensuring the quality of hole metallization in the PCB manufacturing process.

[0005] After the PCB board passes through the activation tank to adsorb colloidal palladium, the palladium nucleus adsorbed on the inner wall of the hole is exposed after the colloidal palladium is debonded in the acceleration tank. After each batch of boards enters the copper plating tank, the palladium nucleus acts as a catalyst to catalyze the deposition of copper on the substrate board, but the palladium exposed in the hole is leached, peeled off and diffused into the copper plating solution to varying degrees. With the increase in the batch (quantity) of board making, the cumulative concentration of palladium in the chemical plating solution will form multiple active sites for the precipitation of copper ions in the plating solution, and the stability of the chemical plating solution will decrease, which will eventually lead to the precipitation of copper powder in the plating solution during the copper deposition process and copper on the tank wall, seriously affecting the service life of the chemical copper plating solution.

[0006] In addition, the current copper plating process technology has two problems. One is to increase the deposition rate, but the chemical copper plating solution is unstable. The other is to increase the stability of the chemical copper plating solution, but the deposition rate will decrease. Summary of the invention

[0007] The purpose of the present application is to provide a high-stability chemical copper plating solution and a preparation method thereof in view of the deficiencies in the current technology. The high-stability chemical copper plating solution of the present application ensures excellent stability while maintaining a high deposition rate, reduces the frequency of maintenance while obtaining a good copper deposition layer quality, increases the service life of the chemical copper solution, prolongs the decomposition time of the plating solution, and promotes production efficiency.

[0008] In a first aspect, the present application provides a high-stability chemical copper plating solution, which adopts the following technical solution: A high-stability chemical copper plating solution comprises the following raw materials, measured by mass concentration: 12-20 g / L of copper sulfate pentahydrate, 24-30 g / L of a reducing agent, 40-45 g / L of a complexing agent, 20-25 g / L of a buffer, 0.45-0.55 g / L of a stabilizer, 2-3 g / L of an accelerator, and 0.010-0.013 g / L of a surfactant, wherein the reducing agent is composed of sodium hypophosphite and pyrrolidine tetrafluoroborate in a mass ratio of 3:4.

[0009] By adopting the above technical scheme, copper sulfate pentahydrate: as a copper source, provides copper ions for deposition. Reducing agent: composed of sodium hypophosphite and pyrrolidine tetrafluoroborate (mass ratio 3:4). Sodium hypophosphite is the main reducing agent, responsible for reducing copper ions to metallic copper; pyrrolidine tetrafluoroborate not only participates in the reduction of copper ions, but also improves the stability of the plating solution and the quality of the coating at low temperatures. Complexing agent: used to complex copper ions, prevent their precipitation, and adjust the deposition rate. Buffer: maintain the pH value of the plating solution stable to ensure the consistency of chemical reaction conditions. Stabilizer: improves the tolerance of the plating solution to leached palladium, prolongs the decomposition time of the plating solution, and enhances the service life of the plating solution. Accelerator: accelerates the reduction rate of copper ions and improves deposition efficiency. Surfactant: reduces the surface tension of the plating solution and improves the uniformity and adhesion of the coating. In short, the sodium hypophosphite and pyrrolidine tetrafluoroborate in the reducing agent work together to not only promote the reduction of copper ions, but also improve low-temperature stability. Stabilizers, complexing agents, buffers, accelerators and surfactants work together to ensure the stability of the plating solution and the quality of the coating. The present application uses a scientific formula design to ensure that the copper plating solution can still maintain good stability and durability at a high deposition rate, thereby improving production efficiency and coating quality.

[0010] Preferably, the preparation method of the pyrrolidine tetrafluoroborate is as follows: according to molar fractions, 10 parts of 1,4-dichlorobutane, 12 parts of diethylamine, 10 parts of sodium carbonate, and 10 parts of tetrafluoroboric acid are added to 80-85 parts of acetonitrile, heated to 80-90°C and reacted for 28-32 hours, cooled to room temperature to obtain a reaction solution, the reaction solution is filtered to obtain a filtrate, the filtrate is concentrated under reduced pressure, and then 70 parts of anhydrous ethanol is added for recrystallization, and a filter cake is obtained after filtration, and the filter cake is vacuum dried to constant weight to obtain pyrrolidine tetrafluoroborate.

[0011] By adopting the above technical scheme, the preparation method of pyrrolidine tetrafluoroborate involves a series of chemical reaction steps, firstly, 1,4-dichlorobutane, diethylamine, sodium carbonate and tetrafluoroboric acid are heated in acetonitrile for reaction, cooled and filtered to obtain the filtrate after a specific time, and then pyrrolidine tetrafluoroborate is obtained by reduced pressure concentration and recrystallization. This compound has multiple functions in chemical copper plating solution, including promoting the reduction deposition of copper ions together with sodium hypophosphite as a reducing agent, improving the stability of the plating solution and the quality of the coating at low temperature, and improving the stability and service life of the overall plating solution through synergistic effects with other components, thereby improving production efficiency and coating quality. Pyrrolidine tetrafluoroborate is used in combination with sodium hypophosphite to effectively promote the reduction deposition of copper ions, thereby increasing the deposition rate of chemical copper plating. Pyrrolidine tetrafluoroborate can maintain the stability of the plating solution at a lower temperature, avoiding the degradation of the coating quality caused by temperature fluctuations. Through the synergistic effect with other ingredients such as complexing agents, buffers, etc., pyrrolidine tetrafluoroborate can improve the stability of the entire chemical copper plating solution system, extend the service life of the plating solution, and reduce the maintenance frequency. Since pyrrolidine tetrafluoroborate can increase the deposition rate and maintain the stability of the plating solution, it can improve production efficiency: at the same time, a stable plating solution also helps to obtain a more uniform and dense coating, thereby improving the quality of the coating. In summary, pyrrolidine tetrafluoroborate plays a key role in the chemical copper plating process. It not only participates in the reduction deposition of copper ions as a reducing agent, but also improves the overall performance and production efficiency of the plating solution through various mechanisms.

[0012] Preferably, the stabilizer is composed of 2-amino-5-mercapto-1,3,4-thiadiazole, S-adenosyl-L-homocysteine ​​(I) and S-carboxymethyl-L-cysteine ​​(II) in a mass ratio of 4-7:5:2-4.

[0013] Preferably, the stabilizer is composed of 2-amino-5-mercapto-1,3,4-thiadiazole, S-adenosyl-L-homocysteine ​​(I) and S-carboxymethyl-L-cysteine ​​(II) in a mass ratio of 6:5:3.

[0014] By adopting the above technical scheme, 2-amino-5-mercapto-1,3,4-thiadiazole, as a sulfur- and nitrogen-containing heterocyclic compound, can form a stable complex with palladium, thereby reducing the negative impact of palladium on the plating solution. S-adenosyl-L-homocysteine ​​(I): contains adenosine and cysteine ​​structures, and can form a complex with palladium through the thiol group in its molecule, further enhancing the anti-palladium performance of the plating solution. S-carboxymethyl-L-cysteine ​​(I): the carboxylmethyl and cysteine ​​parts in its molecule can form a stable complex with palladium ions, further protecting the plating solution from palladium contamination. These three compounds work together to capture and isolate palladium ions by forming a stable complex to prevent them from interfering with the copper deposition process. This stability allows the plating solution to maintain good performance during long-term use. Extend the service life of the plating solution: Since the above compounds can effectively inhibit the destructive effect of palladium on the plating solution, the service life of the plating solution can be significantly extended, reducing the frequency of replacement and maintenance. Improve the quality of the coating: A stable plating solution environment helps to obtain a more uniform and dense coating, thereby improving the quality of the coating. This is particularly important for applications that require high precision and reliability, such as electronic products. The synergistic effect between 2-amino-5-mercapto-1.3.4-thiadiazole, S-adenosyl-L-homocysteine ​​(I) and S-carboxymethyl-L-cysteine ​​(I) is manifested in that their respective unique functions complement each other and together form a powerful protection system. This synergistic effect not only improves the overall performance of the plating solution, but also enhances its resistance to external interference (such as palladium contamination). In summary, this stabilizer composed of 2-amino-5-mercapto-1.3.4-thiadiazole, S-adenosyl-L-homocysteine ​​(I) and S-carboxymethyl-L-cysteine ​​(I) in a mass ratio of 6:5:3 plays a key role in the chemical copper plating solution, improving the stability and service life of the plating solution through multiple mechanisms, while ensuring the quality of the coating.

[0015] Preferably, the complexing agent is composed of ethylenediaminetetraacetic acid and tetrahydroxypropylethylenediamine in a mass ratio of 3:2.

[0016] By adopting the above technical scheme, ethylenediaminetetraacetic acid (EDTA): As a strong chelating agent, EDTA can form stable complexes with a variety of metal ions, especially copper ions. This helps to prevent copper ions from forming precipitation in the solution, thereby maintaining the stability and activity of the plating solution. Tetrahydroxypropylethylenediamine (TEA): TEA is also an effective chelating agent that can form stable complexes with metal ions. It can not only chelate copper ions, but also form complexes with other metal ions to further stabilize the plating solution. EDTA and TEA work together to stabilize copper ions and other metal ions through chelation to prevent them from forming insoluble precipitation in the solution. This stability allows the plating solution to maintain good performance during long-term use. The synergy between EDTA and TEA is manifested in that their respective unique functions complement each other and form a powerful combined system together. This synergy not only improves the overall performance of the plating solution, but also enhances its resistance to external interference (such as metal impurities). Since EDTA and TEA can effectively chelate metal ions and prevent them from forming precipitation in the solution, the service life of the plating solution can be significantly extended and the frequency of replacement and maintenance can be reduced. Stable plating solutions and high-quality coatings help improve production efficiency and reduce production interruptions and quality problems caused by unstable plating solutions. In summary, this complexing agent composed of ethylenediaminetetraacetic acid (EDTA) and tetrahydroxypropylethylenediamine (TEA) in a mass ratio of 3:2 plays a key role in chemical copper plating solutions, improving the stability and service life of the plating solution through multiple mechanisms while ensuring the quality of the coating. This synergistic effect enables the plating solution to perform well in practical applications and meet the requirements of high stability and high efficiency.

[0017] Preferably, the accelerator consists of 2-mercaptobenzothiazole and L-malic acid in a mass ratio of 2:1.

[0018] Preferably, the surfactant is polyoxyethylene fatty acid ester.

[0019] Preferably, the buffer is sodium carbonate.

[0020] In a second aspect, the present application provides a method for preparing a high-stability chemical copper plating solution, using the following technical solution: As a general technical concept, the present application also provides a method for preparing the above-mentioned high-stability chemical copper plating solution, comprising the following steps: 12-20g of copper sulfate pentahydrate, 24-30g of reducing agent, 40-45g of complexing agent, 20-25g of buffer, 0.45-0.55g of stabilizer, 2-3g of accelerator and 0.010-0.013g of surfactant are sequentially added to an appropriate amount of deionized water and mixed evenly, and then the mixed solution is fixed to 1L to obtain a high-stability chemical copper plating solution.

[0021] In summary, the beneficial technical effects of this application are: 1. High deposition rate: By using sodium hypophosphite and pyrrolidine tetrafluoroborate as reducing agents, the chemical copper plating solution can ensure the uniformity and density of the copper layer while maintaining a high deposition rate. This is crucial to improving production efficiency and product quality. 2. Excellent stability: Various components in the plating solution, such as complexing agents (ethylenediaminetetraacetic acid and tetrahydroxypropylethylenediamine), buffers, stabilizers, etc., work together to significantly improve the stability of the plating solution. This stability makes the plating solution less likely to decompose or deteriorate during use, reducing the frequency of maintenance.

[0022] 3. Good coating quality: High-stability chemical copper plating solution can form a uniform, dense and highly adherent copper layer on the substrate. This high-quality coating is particularly important for applications such as electronic products that require high precision and high reliability, and can significantly improve product performance and life.

[0023] 4. Extend the service life of the plating solution: Due to the excellent stability of the plating solution, its service life has been significantly extended. This not only reduces the frequency of replacement and maintenance, reduces production costs, but also improves the continuity and efficiency of the production process.

[0024] 5. Improve the tolerance to palladium leaching: 2-amino-5-mercapto-1.3.4-thiadiazole, S-adenosyl-L-homocysteine ​​(1) and S-carboxymethyl-L-cysteine ​​(I) in the stabilizer work synergistically to improve the tolerance of the plating solution to palladium leaching. This allows the plating solution to maintain good plating activity and throwing power at high palladium leaching concentrations, further extending the service life of the plating solution. DETAILED DESCRIPTION

[0025] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0026] Preparation Example 1 Preparation of pyrrolidine tetrafluoroborate The preparation method of pyrrolidine tetrafluoroborate is as follows: according to the molar fractions, 10 mol of 1,4-dichlorobutane, 12 mol of diethylamine, 10 mol of sodium carbonate and 10 mol of tetrafluoroboric acid are added to 83 mol of acetonitrile, heated to 90°C and reacted for 30 hours, cooled to room temperature to obtain a reaction liquid, the reaction liquid is filtered to obtain a filtrate, the filtrate is concentrated under reduced pressure, and then 70 mol of anhydrous ethanol is added for recrystallization, a filter cake is obtained after filtration, and the filter cake is vacuum dried to constant weight to obtain pyrrolidine tetrafluoroborate.

[0027] Example 1 A high-stability chemical copper plating solution comprises the following raw materials, measured by mass concentration: 12 g / L of copper sulfate pentahydrate, 24 g / L of a reducing agent, 40 g / L of a complexing agent, 20 g / L of sodium carbonate, 0.45 g / L of a stabilizer, 2 g / L of an accelerator, and 0.010 g / L of fatty acid polyoxyethylene ester, wherein the reducing agent is composed of sodium hypophosphite and pyrrolidine tetrafluoroborate in a mass ratio of 3:4, the stabilizer is composed of 2-amino-5-mercapto-1,3,4-thiadiazole, S-adenosyl-L-homocysteine ​​(I) and S-carboxymethyl-L-cysteine ​​(II) in a mass ratio of 4:5:2, the complexing agent is composed of ethylenediaminetetraacetic acid and tetrahydroxypropylethylenediamine in a mass ratio of 3:2, and the accelerator is composed of 2-mercaptobenzothiazole and L-malic acid in a mass ratio of 2:1; The method for preparing the above-mentioned high-stability chemical copper plating solution comprises the following steps: 12 g of copper sulfate pentahydrate, 24 g of reducing agent, 40 g of complexing agent, 20 g of sodium carbonate, 0.45 g of stabilizer, 2 g of accelerator and 0.010 g of fatty acid polyoxyethylene ester are successively added to an appropriate amount of deionized water and mixed evenly, and then the mixed solution is fixed to 1 L to obtain a high-stability chemical copper plating solution.

[0028] Example 2 A high-stability chemical copper plating solution comprises the following raw materials, measured by mass concentration: 20 g / L of copper sulfate pentahydrate, 30 g / L of a reducing agent, 45 g / L of a complexing agent, 25 g / L of sodium carbonate, 0.55 g / L of a stabilizer, 3 g / L of an accelerator, and 0.013 g / L of fatty acid polyoxyethylene ester, wherein the reducing agent is composed of sodium hypophosphite and pyrrolidine tetrafluoroborate in a mass ratio of 3:4, the stabilizer is composed of 2-amino-5-mercapto-1,3,4-thiadiazole, S-adenosyl-L-homocysteine ​​(I) and S-carboxymethyl-L-cysteine ​​(II) in a mass ratio of 7:5:4, the complexing agent is composed of ethylenediaminetetraacetic acid and tetrahydroxypropylethylenediamine in a mass ratio of 3:2, and the accelerator is composed of 2-mercaptobenzothiazole and L-malic acid in a mass ratio of 2:1; The method for preparing the above-mentioned high-stability chemical copper plating solution comprises the following steps: 20 g of copper sulfate pentahydrate, 30 g of reducing agent, 45 g of complexing agent, 25 g of sodium carbonate, 0.55 g of stabilizer, 3 g of accelerator and 0.013 g of fatty acid polyoxyethylene ester are successively added to an appropriate amount of deionized water and mixed evenly, and then the mixed solution is fixed to 1 L to obtain a high-stability chemical copper plating solution.

[0029] Example 3 A high-stability chemical copper plating solution comprises the following raw materials, measured by mass concentration: 16 g / L of copper sulfate pentahydrate, 27 g / L of a reducing agent, 43 g / L of a complexing agent, 23 g / L of sodium carbonate, 0.5 g / L of a stabilizer, 2.3 g / L of an accelerator, and 0.012 g / L of fatty acid polyoxyethylene ester, wherein the reducing agent is composed of sodium hypophosphite and pyrrolidine tetrafluoroborate in a mass ratio of 3:4, the stabilizer is composed of 2-amino-5-mercapto-1,3,4-thiadiazole, S-adenosyl-L-homocysteine ​​(I) and S-carboxymethyl-L-cysteine ​​(II) in a mass ratio of 6:5:3, the complexing agent is composed of ethylenediaminetetraacetic acid and tetrahydroxypropylethylenediamine in a mass ratio of 3:2, and the accelerator is composed of 2-mercaptobenzothiazole and L-malic acid in a mass ratio of 2:1; The method for preparing the above-mentioned high-stability chemical copper plating solution comprises the following steps: 16 g of copper sulfate pentahydrate, 27 g of reducing agent, 43 g of complexing agent, 23 g of sodium carbonate, 0.5 g of stabilizer, 2.3 g of accelerator and 0.012 g of fatty acid polyoxyethylene ester are successively added to an appropriate amount of deionized water and mixed evenly, and then the mixed solution is fixed to 1 L to obtain a high-stability chemical copper plating solution.

[0030] Comparative Example 1 The same as Example 3, except that the stabilizer is 2-amino-5-mercapto-1,3,4-thiadiazole.

[0031] Comparative Example 2 The same as Example 3, except that the stabilizer is S-adenosyl-L-homocysteine ​​(I).

[0032] Comparative Example 3 The same as Example 3, except that the stabilizer is S-carboxymethyl-L-cysteine ​​(II).

[0033] Comparative Example 4 The same as Example 3, except that the complexing agent is ethylenediaminetetraacetic acid.

[0034] Comparative Example 5 The same as Example 3, except that the complexing agent is tetrahydroxypropylethylenediamine.

[0035] Comparative Example 6 The same as Example 3, except that the reducing agent is sodium hypophosphite.

[0036] Comparative Example 7 The same as Example 3, except that the reducing agent is pyrrolidine tetrafluoroborate.

[0037] Performance Testing The high stability chemical copper plating solutions prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were respectively subjected to chemical copper plating. The process conditions were: temperature 35° C., time 20 minutes, the part to be plated was a resin board, and after the conventional chemical copper plating process, the surface palladium activation treatment and reduction treatment, the chemical copper plating process can be directly carried out to carry out the above-mentioned chemical copper plating; and the following tests were carried out, and the test results are shown in Table 1.

[0038] 1. Sedimentation rate test: The sedimentation rate is determined by the weight gain method, and the calculation formula is as follows: v=(m1-m0)×10000 / (ρ×A×t); Where v is the deposition rate, μm / h; m0 and m1 are the masses of the plated part before and after plating, respectively, g; ρ is the relative density of copper, 8.93 g / cm 3 ; A is the surface area of ​​the plated part, cm 2 ; t is the plating time, h; 2. Adhesion test: Use the 100-grid test method, use 3M610 tape to tear, no peeling is OK, and peeling is NG; 3. Plating solution stability test: Since it takes a long time for the plating solution to decompose naturally, an accelerated method is used to shorten the experimental time. This application uses a palladium chloride accelerated test to test the stability of the plating solution: add 15mL PdCl2 (0.18g / L) to 50mL of plating solution at a temperature of 60°C, and record the decomposition time of the plating solution, that is, the time required to produce a large amount of red copper powder and hydrogen; 4. Backlight level: After copper deposition, place the test piece in a slicer and cut it. Grind it with a grinder to grind off 1 / 2 of the hole diameter of the slice, and grind the other side of the slice to about 2mm from the edge of the hole. After grinding, wipe the copper chips and glue residue in the hole with a soft cloth, and use a microscope to magnify 50 times to detect the condition in the hole. Use the backlight principle (if the chemical copper is deposited evenly, the lower light cannot be seen through, the entire hole wall appears completely black, and the backlight level is 10) to check the uniformity of chemical copper deposition on the hole wall of each hole. The backlight level is required to reach above level 8.

[0039] Table 1 Performance test project Deposition rate (μm / h) Backlight level / level Decomposition time / min Coating bonding strength Example 1 3.2 10 852 OK Example 2 3.5 10 835 OK Example 3 3.3 10 839 OK Comparative Example 1 2.8 8.5 627 OK Comparative Example 2 2.9 9 582 OK Comparative Example 3 2.7 9 675 OK Comparative Example 4 3.8 8.5 602 OK Comparative Example 5 4.1 8.5 579 OK Comparative Example 6 2.4 10 775 OK Comparative Example 7 2.8 10 792 OK Analyzing the data in Table 1, we can see that: 1) The high-stability chemical copper plating solution prepared in Examples 1 to 3 ensures excellent stability while ensuring a high deposition rate, reduces the frequency of maintenance while obtaining a good quality copper deposition layer, increases the service life of the chemical copper solution, prolongs the decomposition time of the plating solution, and promotes production efficiency.

[0040] 2) The performance comparison analysis of the high stability chemical copper plating solution prepared in combination with Example 3 and Comparative Examples 1-3 shows that the stabilizer is composed of 2-amino-5-mercapto-1,3,4-thiadiazole, S-adenosine-L-homocysteine ​​(I) and S-carboxymethyl-L-cysteine ​​(II) in a mass ratio of 6:5:3. These three compounds work together to capture and isolate palladium ions by forming a stable complex to prevent them from interfering with the copper deposition process. This stability allows the plating solution to maintain good performance during long-term use. Extend the service life of the plating solution: Since the above-mentioned compounds can effectively inhibit the destructive effect of palladium on the plating solution, the service life of the plating solution can be significantly extended, and the frequency of replacement and maintenance can be reduced. Improve the quality of the coating: A stable plating solution environment helps to obtain a more uniform and dense coating, thereby improving the quality of the coating. This is particularly important for applications such as electronic products that require high precision and high reliability. In summary, the synergistic effect between 2-amino-5-mercapto-1.3.4-thiadiazole, S-adenosyl-L-homocysteine ​​(I) and S-carboxymethyl-L-cysteine ​​(I) is manifested in that their unique functions complement each other and together form a powerful protection system. This synergistic effect not only improves the overall performance of the plating solution, but also enhances its resistance to external interference (such as palladium contamination), improves the stability and service life of the plating solution through multiple mechanisms, and ensures the quality of the coating.

[0041] 3) The performance comparison analysis of the high stability chemical copper plating solution prepared in combination with Example 3 and Comparative Examples 4-5 shows that the complexing agent is composed of ethylenediaminetetraacetic acid and tetrahydroxypropylethylenediamine in a mass ratio of 3:2, which can form a stable complex with copper ions, which can not only further improve the copper deposition rate and the stability of the coating, but also improve the physical properties of the coating and enhance the backlight level.

[0042] 4) The performance comparison analysis of the high stability chemical copper plating solution prepared in combination with Example 3 and Comparative Examples 6-7 shows that by using sodium hypophosphite and pyrrolidine tetrafluoroborate as reducing agents, the chemical copper plating solution can ensure the uniformity and density of the copper layer while maintaining a high deposition rate.

[0043] The above embodiments are only used to explain the technical solutions of the present application rather than to limit them. Although the above embodiments provide a specific description of the present application, relevant technical personnel should understand that the specific implementation modes of the present invention can still be modified or replaced by equivalents, and any modifications and equivalent replacements that do not depart from the spirit and scope of the present application should be included in the scope of protection of the present application.

Claims

1. A high stability chemical copper plating solution, characterized in that: Measured by mass concentration, the preparation raw materials include: 12-20 g / L of copper sulfate pentahydrate, 24-30 g / L of reducing agent, 40-45 g / L of complexing agent, 20-25 g / L of buffer, 0.45-0.55 g / L of stabilizer, 2-3 g / L of accelerator, and 0.010-0.013 g / L of surfactant, wherein the reducing agent is composed of sodium hypophosphite and pyrrolidine tetrafluoroborate in a mass ratio of 3:

4.

2. A high stability chemical copper plating solution according to claim 1, characterized in that: The preparation method of pyrrolidine tetrafluoroborate comprises the following steps: according to molar fractions, 10 parts of 1,4-dichlorobutane, 12 parts of diethylamine, 10 parts of sodium carbonate and 10 parts of tetrafluoroboric acid are added to 80-85 parts of acetonitrile, heated to 80-90° C. and reacted for 28-32 hours, cooled to room temperature to obtain a reaction liquid, filtered the reaction liquid to obtain a filtrate, concentrated the filtrate under reduced pressure, added 70 parts of anhydrous ethanol to recrystallize, filtered to obtain a filter cake, and vacuum dried the filter cake to constant weight to obtain pyrrolidine tetrafluoroborate.

3. A high stability chemical copper plating solution according to claim 1, characterized in that: The stabilizer is composed of 2-amino-5-mercapto-1,3,4-thiadiazole, S-adenosyl-L-homocysteine ​​(I) and S-carboxymethyl-L-cysteine ​​(II) in a mass ratio of 4-7:5:2-4.

4. A high stability chemical copper plating solution according to claim 3, characterized in that: The stabilizer is composed of 2-amino-5-mercapto-1,3,4-thiadiazole, S-adenosyl-L-homocysteine ​​(I) and S-carboxymethyl-L-cysteine ​​(II) in a mass ratio of 6:5:

3.

5. A high stability chemical copper plating solution according to claim 1, characterized in that: The complexing agent is composed of ethylenediaminetetraacetic acid and tetrahydroxypropylethylenediamine in a mass ratio of 3:

2.

6. A high stability chemical copper plating solution according to claim 5, characterized in that: The accelerator is composed of 2-mercaptobenzothiazole and L-malic acid in a mass ratio of 2:

1.

7. A high stability chemical copper plating solution according to claim 1, characterized in that: The surfactant is polyoxyethylene fatty acid ester.

8. A high stability chemical copper plating solution according to claim 1, characterized in that: The buffer is sodium carbonate.

9. A method for preparing a high-stability chemical copper plating solution according to any one of claims 1 to 8, characterized in that: include: 12-20g of copper sulfate pentahydrate, 24-30g of reducing agent, 40-45g of complexing agent, 20-25g of buffer, 0.45-0.55g of stabilizer, 2-3g of accelerator and 0.010-0.013g of surfactant are sequentially added to an appropriate amount of deionized water and mixed evenly, and then the mixed solution is fixed to 1L to obtain a high-stability chemical copper plating solution.