A kind of polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt and its preparation method and application

Abstract

The invention discloses a polymethacrylate (N, N-dialkylaminoethyl) quaternary ammonium salt and a preparation method and application thereof, and relates to the technical field of polymer synthesis. The polymethacrylate (N, N-dialkylaminoethyl) quaternary ammonium salt of the invention is a nitrogen-containing oligomer quaternary ammonium salt synthesized based on a quaternary ammonium salt structure, which can effectively combine the inhibitory effect of polyether, use the nitrogen-containing oligomer quaternary ammonium salt as a leveling agent skeleton structure, utilize the synergistic effect of key functional groups and copper ions, improve the glossiness of the copper-plated surface, and the TP value of micropore electroplating with an aspect ratio of 6:1 can reach more than 80%. At the same time, the amount of the leveling agent is greatly reduced, and the concentration in the electroplating solution can be reduced to 3ppm. The invention can be widely used in the electroplating industry to prepare a printed circuit board with a bright surface.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer synthesis, and more specifically to a polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt and a preparation method and application thereof. Background Art

[0002] As an important carrier of information transmission, high-density interconnected circuits are a frontier topic of concern and research in academia and industry. Compared with ordinary printed circuits, they have higher electronic interconnection density, but the miniaturized through-holes put forward higher requirements on the all-plating ability of the plating solution. As an important component of the copper plating solution, the leveling agent can effectively improve the current distribution during the electroplating process, control the transportation and electrocrystallization process of copper ions from the solution body to the reaction interface, thereby affecting the electrochemical deposition rate of the micro-concave and micro-convex parts of the board surface, and effectively improve the all-plating ability of the plating solution in through-holes and blind holes. The leveling agent is easily adsorbed on the surface of the plated part with strong electronegativity or strong convection, increasing the reaction resistance in the high current density area, and is a key component affecting the current distribution of through-hole and hole-filling electroplating. Traditional leveling agents include dye-type quaternary ammonium salts such as janna green and methylene blue, which have excellent hole-filling performance, but have problems such as high cost, poor high temperature resistance, and inactivation of accelerators under high current density.

[0003] The prior art discloses a quaternary ammonium salt leveler, and a method for preparing the quaternary ammonium salt leveler, comprising the following steps: (1) reacting a nitrogen-containing heterocyclic compound and an epoxy compound at 60°C to 95°C for 8 to 12 hours to polymerize a tertiary amine compound; the molar ratio of the nitrogen-containing cyclic compound to the epoxy compound is controlled to be 1:0.3 to 1:1; (2) adding an alkyl halide to complete a quaternization reaction; the molar ratio of the tertiary amine compound to the alkyl halide is controlled to be 1:0.5 to 1:1. Although the quaternary ammonium salt leveler prepared by the prior art has a certain pore-filling effect, it does not improve the glossiness of the copper-plated surface, and the amount of the leveler used is too large, reaching 100 mg.

[0004] / L. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of excessive dosage of leveling agent in the existing electroplating process and poor glossiness of the copper-plated surface, and to provide a polymethacrylate (N, N-dialkylaminoethyl ester) quaternary ammonium salt as an electroplating leveling agent, which not only has a dosage as low as 3ppm, but also has a TP value of more than 80% for micropore electroplating.

[0006] Another object of the present invention is to provide a method for preparing polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt.

[0007] Another object of the present invention is to provide a use of polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt in electroplating.

[0008] Another object of the present invention is to provide an electroplating solution.

[0009] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0010] A polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt, the structural formula of which is as follows:

[0011]

[0012] Wherein, n is 5 to 50,

[0013] R1 is one of a hydrogen proton, a phenyl group, a benzyl group, a pyridyl group, a 2-ethylpyridyl group, a 4-ethylpyridyl group, a methylcyclohexyl group, a tert-butyl group, an isopropyl group or a tri-n-butylphosphine group;

[0014] R2 is one of methyl, ethyl or propyl;

[0015] X- is one of fluoride anion, chloride anion, bromide anion, iodide anion, tetrafluoroborate, p-toluenesulfonate or imidazolium anion.

[0016] The polymethacrylate (N, N-dialkylaminoethyl) quaternary ammonium salt of the present invention is a nitrogen-containing oligomer quaternary ammonium salt synthesized based on a quaternary ammonium salt structure, and the nitrogen-containing oligomer quaternary ammonium salt is used as a leveler skeleton structure. Since the polymer flexible chain is more stable than traditional rigid Janus green and methylene blue, and has good heat resistance, the introduction of related groups can adjust its heat resistance, effectively combining the inhibitory effect of polyether, and achieving better electroplating leveling. On the other hand, by utilizing the synergistic effect of heteroatom functional groups and copper ions, the quaternary ammonium functional groups are improved according to the electroplating properties of the leveler to achieve the balance of the current inside and outside the hole during the electroplating process, thereby achieving a good electroplating effect, and the TP value of micropore electroplating can reach more than 80%.

[0017] In a specific embodiment, the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt of the present invention can be any one of the following structural formulas:

[0018]

[0019] n is 5 to 50. More preferably, the degree of polymerization is 20 to 25.

[0020] The present invention also specifically protects a method for preparing a polymethacrylate (N,N-dialkylaminoethyl) quaternary ammonium salt, comprising the following steps:

[0021] S1. Quaternization reaction of methacrylic acid (N, N-dialkylaminoethyl ester): quaternization reaction of methacrylic acid (N, N-dialkylaminoethyl ester) and a quaternization agent under an inert gas atmosphere, removing the solvent after the reaction, and extracting the product to obtain a polymer monomer;

[0022] S2. Polymerization reaction of methacrylate (N,N-dialkylaminoethyl) quaternary ammonium salt monomer: methacrylate (N,N-dialkylaminoethyl) quaternary ammonium salt monomer, free radical initiator, and chain transfer agent are mixed in a reaction solvent, and polymerization reaction is carried out under an inert gas atmosphere. After the reaction, purification is performed to obtain polymethacrylate (N,N-dialkylaminoethyl) quaternary ammonium salt.

[0023] Among them, it should be noted that:

[0024] In the preparation method of the present invention, the reaction progress in S1 can be detected by thin layer chromatography TLC, and the solvent can be removed by rotary evaporation after the reaction is completed. The product can be extracted with water / ethyl acetate, and the aqueous phase mixture is collected, and the water is removed by rotary evaporation to obtain the polymer monomer.

[0025] The quaternization reaction solvent in S1 may be a conventional solvent in the art, for example, methanol, ethanol, isopropanol, preferably ethanol.

[0026] The polymerization reaction in S2 is monitored by GPC for the molecular weight of the polymerization product until the reaction is completed, and a polymerization inhibitor is added to terminate the reaction. The product is dialyzed in a dialysis bag to remove the monomer, and the dialysate is rotary evaporated to remove the water phase. The light brown solid product is purified and dried to obtain polymethacrylate (N, N-dialkylaminoethyl ester) quaternary ammonium salt. The molecular weight cutoff of the dialysis bag is 1KD to 5KD.

[0027] The free radical initiator in S2 may be a conventional free radical initiator in the art, for example, it may be one of azobisisobutyronitrile, azobisisoheptanenitrile, tert-butyl benzoyl peroxide, and benzoyl peroxide, preferably azobisisobutyronitrile.

[0028] The chain transfer agent in S2 may be a conventional chain transfer agent in the art, for example, it may be one of butyl 3-mercaptopropionate, trichloroethylene, dodecyl mercaptan, and α-methylstyrene dimer, preferably α-methylstyrene dimer.

[0029] The polymerization inhibitor in S2 may be a conventional polymerization inhibitor in the art, for example, it may be one of phenol, p-methylphenol, hydroquinone, and 2,6-di-tert-butyl-p-cresol, preferably hydroquinone.

[0030] The polymerization reaction solvent in S2 can be a conventional solvent in the art, such as methanol or ethanol.

[0031] The inert gas described in the present invention is a conventional inert gas in the art, for example, nitrogen or argon.

[0032] In a specific embodiment, preferably, the molar ratio of methacrylic acid (N,N-dialkylaminoethyl ester) to the quaternizing agent in S1 is 1:0.9-1.4, more preferably 1:1.05.

[0033] The quaternizing agent needs to be slightly excessive. Too low an amount will easily lead to a low quaternization rate and thus affect the performance of the polymer. Too high an amount will increase the difficulty of purification and waste drugs.

[0034] In a specific embodiment, preferably, the temperature of the quaternization reaction in S1 is 50-80°C, more preferably 70°C.

[0035] In a specific embodiment, preferably, the temperature of the polymerization reaction in S2 is 60-80°C, preferably 80°C.

[0036] The polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt of the present invention has a good leveling effect, can effectively improve the micropore current distribution in the electroplating process, and enhance the all-plating ability of the plating solution on tiny through holes at a low concentration. It has good application potential in reducing the cost and increasing the efficiency of electroplating additives, can be used as an electroplating leveling agent, and is widely used in the electroplating industry.

[0037] The present invention also specifically protects an electroplating solution, wherein the leveling agent of the electroplating solution is the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt.

[0038] In some specific embodiments, preferably, the concentration of the leveler in the electroplating solution is 1-3 ppm, more preferably 1 ppm.

[0039] The electroplating solution of the present invention can be the base metal electroplating solution used herein, and the electroplating additive polymethacrylate (N, N-dialkylaminoethyl ester) quaternary ammonium salt is added as a leveling agent, for example, it can be:

[0040] The electroplating solution includes the following components: 240 g / L sulfuric acid, 80 g / L copper sulfate pentahydrate, 80 ppm chloride ion, 1-2 ppm accelerator, 100-400 ppm inhibitor, and 1-3 ppm leveler.

[0041] The brightener may be SPS or the like, and the inhibitor may be PEG8000, PEG10000 or 50HB-400.

[0042] The electroplating solution of the present invention is used for electroplating, and the through-hole electroplating conditions of the Haring tank electroplating are: the DC current density is 1A / dm 2 -10A / dm 2, bubbling and mixing are uniform, the through-hole plating time is 30min-60min, and the suitable temperature is 15-40℃.

[0043] By using the polymethacrylate (N, N-dialkylaminoethyl ester) quaternary ammonium salt of the invention as an electroplating additive, a printed circuit board test board with a bright surface and a TP value of 80%-90% can be obtained.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt leveler of the invention improves the glossiness of the copper-plated surface, and the TP value of micro-hole electroplating with a thickness-to-diameter ratio of 6:1 can reach more than 80%. At the same time, the dosage of the leveler is greatly reduced, and the concentration in the electroplating solution can be reduced to 3ppm. The leveler can be widely used in the electroplating industry to prepare a printed circuit board with a bright surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the infrared spectrum of polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt of Example 1.

[0047] Figure 2 This is the through-hole morphology under a metallographic microscope in the electroplating application of Example 1 (1 ppm).

[0048] Figure 3 This is the through-hole morphology under a metallographic microscope in the electroplating application of Example 1 (0.1ppm).

[0049] Figure 4 This is the through-hole morphology under a metallographic microscope in the electroplating application of Example 1 (3ppm).

[0050] Figure 5 This is the through-hole morphology under a metallographic microscope in the electroplating application in Example 2.

[0051] Figure 6 This is the through-hole morphology under a metallographic microscope in the electroplating application in Example 3.

[0052] Figure 7 This is the through-hole morphology under a metallographic microscope in the electroplating application of Example 4.

[0053] Figure 8 This is the through-hole morphology under a metallographic microscope in the electroplating application of Example 5.

[0054] Fig. 9 This is the through-hole morphology under a metallographic microscope in the electroplating application of Example 6.

[0055] Fig.10 This is the metallographic microscope through-hole morphology in the electroplating application of Comparative Example 1.

[0056] Fig.11This is the metallographic microscope through-hole morphology in the electroplating application of comparative example 2. DETAILED DESCRIPTION

[0057] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0058] Example 1

[0059] A polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt, number average molecular weight 6860, its structural formula is:

[0060] n=20.

[0061] The preparation method of the polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt of Example 1 is as follows:

[0062] S1. Quaternization reaction of methacrylic acid (N,N-dialkylaminoethyl ester):

[0063] In a 250 ml reaction bottle, 15.7 g of methacrylic acid (N, N-dimethylaminoethyl ester) and 17.1 g of benzyl bromide were added, the molar ratio of methacrylic acid (N, N-dialkylaminoethyl ester) to the quaternary ammonium agent was 1:1.05, 15 ml of anhydrous ethanol was added as a solvent, heated and stirred at 70 ° C for 24 h under a nitrogen atmosphere, and post-processed to obtain 29.52 g of quaternary ammonium salt monomer with a yield of 90%;

[0064] S2. Polymerization of quaternary ammonium salt monomer of methacrylate (N,N-dialkylaminoethyl ester):

[0065] The polymerization reaction was carried out with the quaternary ammonium salt monomer as the polymerization monomer. 32.8 g of monomer, 164 mg of free radical initiator AIBN, 1.42 g of chain transfer agent α-methylstyrene dimer, and 15 ml of anhydrous ethanol were added to a 100 ml reaction bottle. The reaction was carried out at 70° C. for 2 hours under a nitrogen atmosphere. After the reaction, 110 mg of inhibitor phenol was added. The product was dialyzed to obtain 19.7 g, with a yield of 60%.

[0066] The polymethacrylate (N, N-dialkylaminoethyl) quaternary ammonium salt of Example 1 was subjected to infrared detection, and the specific detection results are as follows:

[0067] IR(KBr,cm -1 )3420.24,2970.17,2823.34,2772.05,1728.46,1634.31,1456.17,1384.83,123.4.74,1149.58,766.52,716.09,457.43. Infrared spectrum as Figure 1 shown.

[0068] Example 2

[0069] A polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt, number average molecular weight 6578, its structural formula is:

[0070] n=22.

[0071] The preparation method of polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt in Example 2 is substantially the same as that in Example 1, wherein methacrylic acid (N, N-dimethylaminoethyl ester) is The quaternizing agent is

[0072] Example 3

[0073] A polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt, with a number average molecular weight of 5400, and a structural formula of:

[0074] n=18.

[0075] The preparation method of polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt in Example 3 is substantially the same as that in Example 1, wherein methacrylic acid (N, N-dimethylaminoethyl ester) is The quaternizing agent is

[0076] Example 4

[0077] A polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt, number average molecular weight 7725, its structural formula is:

[0078] n=25.

[0079] The preparation method of polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt in Example 3 is substantially the same as that in Example 1, wherein methacrylic acid (N, N-dimethylaminoethyl ester) is The quaternizing agent is

[0080] Example 5

[0081] A polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt, number average molecular weight 7420, its structural formula is:

[0082] n=20.

[0083] The preparation method of polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt in Example 3 is substantially the same as that in Example 1, wherein methacrylic acid (N, N-dimethylaminoethyl ester) is The quaternizing agent is

[0084] Example 6

[0085] A polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt, number average molecular weight 6560, its structural formula is:

[0086] n=20.

[0087] The preparation method of polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt in Example 3 is substantially the same as that in Example 1, wherein methacrylic acid (N, N-dimethylaminoethyl ester) is The quaternizing agent is Comparative Example 1

[0088] Commercially available leveling agent 1: Rhodamine B quaternary ammonium salt, derived from Aladdin, with the structure of Rhodamine B quaternary ammonium salt and a molecular weight of 650.

[0089] Comparative Example 2

[0090] Commercially available leveling agent 2: Methylene blue quaternary ammonium salt, derived from Aladdin, with a structure of methylene blue quaternary ammonium salt and a molecular weight of 545.

[0091] Results

[0092] (1) Plating solution configuration

[0093] 240 g of sulfuric acid, 80 g of copper sulfate pentahydrate, 80 ppm of sodium chloride, 2 ppm of brightener SPS, 200 ppm of polyether PEG8000, and leveling agent (the concentrations of Example 1 were 1 ppm, 0.1 ppm, and 3 ppm, respectively, and the concentrations of other examples and comparative examples were all 1 ppm) were added to a 2-liter beaker in sequence, and stirred evenly to obtain a plating solution. The effects of using different leveling agents under the same experimental conditions are compared, as shown in Table 1.

[0094] (2) Haring tank electroplating test

[0095] Plating solution was added to the Haring tank, and a 10cm*5.5cm*0.15cm test piece was tested, with a DC current density of 2A / dm2, gas stirring of 2.0L / min, electroplating time of 60min, and temperature controlled at 25°C. The diameter of the plated through hole in the embodiment and the comparative example was 250um, the hole depth was 1500um, and the thickness-diameter ratio was 6:1. After the electroplating, the TP values ​​of the comparative example under the same conditions were 68.5% and 58.5% respectively, while the plated surface of the embodiments 1-6 was smooth and bright, and the TP value was between 80-90%, which was much better than the comparative example.

[0096] For details of the through hole morphology under metallographic microscope, see Figure 2-11 .

[0097] Hole mouth TP value test: TP value is a numerical value obtained by using the ratio between the average thickness of metal plating at the corner of the through hole mouth and the average thickness of metal plating on the surface of the test board. It can be used to indicate the deep plating ability of the through hole mouth corner. The closer the ratio is to 100%, the better the leveling and deep plating ability of the electroplating additive.

[0098] Figure 2 The metallographic microscope through-hole morphology in the electroplating application with the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt leveler added at a concentration of 0.1ppm of Example 1 shows that the leveler has a certain leveling ability at this concentration, but the TP value is less than 80%, which cannot meet the production requirements, indicating that the leveler concentration is too low to improve the effect of the additive system.

[0099] Figure 3 The metallographic microscope through-hole morphology in the electroplating application with the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt leveler added at a concentration of 1 ppm in Example 1 shows that the leveling ability of the leveler can be effectively improved using the optimal concentration conditions, indicating that the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt leveler has good leveling ability.

[0100] Figure 4 The metallographic microscope through-hole morphology in the electroplating application with the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt leveler added at a concentration of 3 ppm of Example 1 shows that the leveling ability of the leveler is slightly reduced when the concentration increases, indicating that there is an optimal concentration for the use of the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt leveler. Excessive additives not only cause waste, but also reduce the overall effect of the electroplating system.

[0101] Figure 5The metallographic microscope through-hole morphology in the electroplating application of the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt leveler of Example 2 shows that the hole mouth angle TP value can reach 84.8% after using the additive, which meets the production requirements, indicating that the leveling ability of the electroplating additive system can be greatly improved after the addition of the additive.

[0102] Figure 6 The metallographic microscope through-hole morphology in the electroplating application of the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt leveler of Example 3 shows that the hole mouth angle TP value can reach 89.6% after using the additive, which meets the production requirements, indicating that the leveling ability of the electroplating additive system can be greatly improved after the addition of the additive.

[0103] Figure 7 The metallographic microscope through-hole morphology in the electroplating application of the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt leveler of Example 4 shows that the hole mouth angle TP value can reach 83.5% after using the additive, which meets the production requirements, indicating that the leveling ability of the electroplating additive system can be greatly improved after the addition of the additive.

[0104] Figure 8 The metallographic microscope through-hole morphology in the electroplating application of the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt leveler of Example 5 shows that the hole mouth angle TP value can reach 86.3% after using the additive, which meets the production requirements, indicating that the leveling ability of the electroplating additive system can be greatly improved after the addition of the additive.

[0105] Fig. 9 The metallographic microscope through-hole morphology in the electroplating application of the polymethacrylate (N,N-dialkylaminoethyl ester) quaternary ammonium salt leveler of Example 6 shows that the hole mouth angle TP value can reach 88.7% after using the additive, which meets the production requirements, indicating that the leveling ability of the electroplating additive system can be greatly improved after the addition of the additive.

[0106] Fig.10 This is the metallographic microscope through-hole morphology in the leveling agent electroplating application of comparative example 1. It can be seen that the hole mouth angle TP value after using the additive is only 68.5%, which is far less than 80%, and does not meet the production requirements. This shows that the commercially available leveling agent Rhodamine B quaternary ammonium salt used in comparative example 1 cannot meet the requirements of deep hole uniform plating.

[0107] Fig.11 This is the metallographic microscope through-hole morphology in the leveling agent electroplating application of Comparative Example 2. It can be seen that the hole mouth angle TP value after using the additive is only 58.5%, which is far less than 80%, and does not meet the production requirements. This shows that the commercially available leveling agent methylene blue quaternary ammonium salt used in Comparative Example 2 cannot meet the requirements of deep hole plating.

[0108] Table 1.

[0109]

[0110] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A use of polymethacrylate (N, N-dialkylaminoethyl ester) quaternary ammonium salt as a leveling agent in electroplating, characterized in that: The structural formula of the polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt is as follows: n is 5-50.

2. A polymethacrylate (N, N-dialkylaminoethyl ester) quaternary ammonium salt, characterized in that: The structural formula is as follows: Where n is 5-50, R1 is one of pyridyl, 2-ethylpyridyl and 4-ethylpyridyl; R2 is one of methyl, ethyl or propyl; X - It is one of fluoride anion, chloride anion, bromide anion, iodide anion, tetrafluoroborate, p-toluenesulfonate or imidazolium anion.

3. The polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt as claimed in claim 2, characterized in that: Any of the following structural formulas: n is 5-50.

4. A method for preparing the polymethacrylic acid (N, N-dialkylaminoethyl ester) quaternary ammonium salt according to claim 2 or 3, characterized in that: The steps include: S1. Quaternization reaction of methacrylic acid (N, N-dialkylaminoethyl ester): quaternization reaction of methacrylic acid (N, N-dialkylaminoethyl ester) and a quaternization agent under an inert gas atmosphere, removing the solvent after the reaction, and extracting the product to obtain a polymer monomer; S2. Polymerization reaction of methacrylate (N,N-dialkylaminoethyl) quaternary ammonium salt monomer: methacrylate (N,N-dialkylaminoethyl) quaternary ammonium salt monomer, free radical initiator, and chain transfer agent are mixed in a reaction solvent, and polymerization reaction is carried out under an inert gas atmosphere. After the reaction, purification is performed to obtain polymethacrylate (N,N-dialkylaminoethyl) quaternary ammonium salt.

5. The preparation method according to claim 4, characterized in that: The molar ratio of methacrylic acid (N,N-dialkylaminoethyl ester) to the quaternary ammonium agent in S1 is 1:0.9-1.

4.

6. The preparation method according to claim 4, characterized in that: The temperature of the polymerization reaction in S2 is 60-80°C.

7. An electroplating solution, characterized in that The electroplating solution contains a leveling agent, and the leveling agent is a quaternary ammonium salt of polymethacrylate (N,N-dialkylaminoethyl ester) with the structural formula shown below: Where n is 5-50, R1 is one of pyridyl, 2-ethylpyridyl and 4-ethylpyridyl; R2 is one of methyl, ethyl or propyl; X - It is one of fluoride anion, chloride anion, bromide anion, iodide anion, tetrafluoroborate, p-toluenesulfonate or imidazolium anion.

8. The electroplating solution according to claim 7, characterized in that: The concentration of the leveler in the electroplating solution is 1-3 ppm.

9. The electroplating solution according to claim 7, characterized in that: The electroplating solution includes the following components: 240 g / L sulfuric acid, 80 g / L copper sulfate pentahydrate, 80 ppm chloride ion, 1-2 ppm accelerator, 100-400 ppm inhibitor, and 1-3 ppm leveler.

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