CN118812835A - A leveling agent containing 2-substituted benzimidazole groups and its preparation method and application - Google Patents

Abstract

The invention discloses a leveling agent containing 2-substituted benzimidazole groups, which comprises functional components, wherein the functional components are polymers obtained by reacting 2-substituted benzimidazole compounds with diglycidyl ether compounds. The 2-substituted benzimidazole group enables the leveling agent to have higher positive charge amount, be easier to adsorb on copper surface and further inhibit deposition of copper ions, and have higher binding force on copper surface. Meanwhile, the existence of the 2-substituent group can further lead the leveling agent to have a molecular structure with larger steric hindrance, further increase the difficulty of the leveling agent entering and being adsorbed in the hole, and lead the inside and outside of the blind hole to form larger deposition speed difference, thereby leading the blind hole electroplating to have the effects of high copper filling speed, lower surface copper thickness, basically no gap in filling and good appearance state, meeting the production requirement of blind hole electroplating, improving the production efficiency and reducing the process cost.

Description

A leveling agent containing 2-substituted benzimidazole groups and its preparation method and application

Technical Field

The invention belongs to the technical field of electroplating, and in particular relates to a leveling agent containing 2-substituted benzimidazole groups and a preparation method and application thereof.

Background Art

With the continuous development of thinner, integrated and multifunctional consumer electronic products, the wiring density and hole density of printed circuit boards are becoming higher and higher, and their manufacturing is becoming more and more complicated. In order to achieve high-density wiring of circuit boards, the method of increasing the number of blind holes or buried holes is generally adopted. Therefore, blind hole electroplating filling technology has become an effective means to solve this problem, and it has also become one of the key technologies for the development of high-density interconnection boards.

In order to ensure the reliability of circuit connection, ensure the yield of circuit production and reduce the cost and difficulty of subsequent etching and copper reduction, the blind hole is required to be completely filled with electroplated copper, without defects such as cladding or cracks, and the copper surface is as thin as possible. In this process, the filling rate of the blind hole (generally expressed as a depression value (Dimple value), when the center of the blind hole plating layer is depressed downward after copper plating, the Dimple value is positive, and if the center of the plating layer protrudes from the copper surface, the Dimple value is negative.) and the copper thickness after electroplating are important indicators for measuring the performance of the copper plating solution.

There are three main types of copper plating organic additives used in the blind hole filling electroplating process: accelerators, inhibitors and levelers. Accelerators (also known as brighteners) mainly include SPS (sodium polydisulfide propane sulfonate) and MPS (sodium 3-thiopropane sulfonate). Inhibitors (also known as carriers) are mostly polyether compounds, and commonly used ones are polyethylene glycol, PO/EO block polyether, etc. Levelers are crucial additives for filling blind holes. They are generally nitrogen-containing heterocyclic compounds or quaternary ammonium salt compounds. Their molecules themselves are positively charged and can be easily adsorbed on the protruding areas of the board surface, that is, high current density areas, which slows down the electroplating speed there and inhibits the deposition of copper in the high current density area. However, there is less adsorption in the concave areas of the board surface and in the blind holes, so that the copper deposition effect here is not affected, thereby achieving the effect of filling the blind holes. Quaternary ammonium salt compound levelers are one of the research hotspots of electroplating additives. Current studies have found that the polymer levelers obtained by the reaction of nitrogen-containing heterocyclic small molecules with diglycidyl ether compounds can not only play an inhibitory role similar to that of inhibitor polyethers, but also have the leveling effect of quaternary ammonium salts and have good filling capacity.

"The Effect of Phenyl-Modified Nitrogen-Containing Leveler on Copper Plating of High Aspect Ratio Blind Holes" discloses a phenyl-modified nitrogen-containing leveler. In this document, water-soluble imidazole, 4-phenylimidazole, 2-phenylimidazole and benzimidazole are selected as raw materials, respectively, and reacted with 1,4-butanediol diglycidyl ether and secondary amine to synthesize a quaternary ammonium salt leveler. The prepared levelers all have good blind hole filling ability, and the surface copper thickness is about 16μm. Among them, benzimidazole has a stable planar structure, and the imidazole ring and the benzene ring are coplanar to form a highly conjugated π system, so that the area of parallel adsorption on the copper surface of the benzimidazole-type quaternary ammonium salt is larger than that of other phenylimidazoles. When used as a leveler in blind hole filling electroplating, it can achieve a higher filling rate and a lower surface copper thickness than other phenylimidazole-type quaternary ammonium salts.

At present, the research on quaternary ammonium salt compound levelers is mainly focused on the screening of existing commercial nitrogen-containing heterocyclic compounds and the exploration of their through-hole filling effects. Less attention is paid to the study of the influence of the structure or substituents of the leveler on the leveling ability. In order to meet the increasing industrial demand, it is particularly important to develop and design the synthesis of new high-efficiency levelers to further improve the blind hole filling electroplating performance.

Summary of the invention

The primary purpose of the present invention is to provide a leveling agent containing a 2-substituted benzimidazole group. The leveling agent is applied to blind hole electroplating and can achieve the effects of low depression value, small surface copper thickness, uniform and flat copper layer, and good appearance within a reasonable current density range, thereby meeting the production requirements of blind hole electroplating, improving production efficiency, and reducing process costs.

The second object of the present invention is to provide a method for preparing a leveler containing 2-substituted benzimidazole groups.

A third object of the present invention is to provide an electroplating solution.

The above-mentioned object of the present invention is achieved by the following technical solutions:

A leveler containing 2-substituted benzimidazole groups, the leveler containing 2-substituted benzimidazole groups comprising an effective component, the effective component is a polymer obtained by reacting a 2-substituted benzimidazole compound with a diglycidyl ether compound, the structural formulas of the 2-substituted benzimidazole compound and the diglycidyl ether compound are shown in Formula I and Formula II, respectively:

Wherein, _R1 of the 2-substituted benzimidazole compound is one of _C5 - _C10 alkyl, p-halobenzyl, 2,4-dihalobenzyl, and 3,4-dihalobenzyl;

R ₂ of the diglycidyl ether compound is a C ₁ -C ₁₀ alkyl group.

Preferably, the polymer can be obtained by reacting one or more 2-substituted benzimidazole compounds with one or more diglycidyl ether compounds.

Preferably, the number average molecular weight of the polymer is 500-25000.

More preferably, the number average molecular weight of the polymer is 500-10,000.

A method for preparing a leveler containing a 2-substituted benzimidazole group comprises the following steps:

The 2-substituted benzimidazole compound is dissolved in a solvent, a diglycidyl ether compound is added dropwise to carry out a condensation reaction to obtain a polymer, and after distilling and recovering the solvent, appropriate amounts of water and sulfuric acid solution are added to the polymer to adjust the pH to acidic to obtain the leveling agent containing the 2-substituted benzimidazole group.

Preferably, the molar ratio of the 2-substituted benzimidazole compound to the diglycidyl ether compound is 0.5-2:1.

Preferably, the mass ratio of the 2-substituted benzimidazole compound to the solvent is 1:1-10.

Preferably, the solvent is one or more of methanol, ethanol, isopropanol, ethyl acetate, chloroform, tetrahydrofuran, toluene and xylene.

Preferably, the mass fraction of the acid solution is 20%-50%.

Preferably, the pH of the leveler containing 2-substituted benzimidazole groups is 1-4.

Some polymers prepared from 2-substituted benzimidazole compounds and diglycidyl ether compounds have poor solubility in water under neutral pH conditions, but have good solubility in water under acidic pH conditions. The plating solution used for blind hole electroplating is acidic, and preparing the leveling agent into an acidic solution helps it to be better dispersed in the plating solution.

Specifically, the solvent is recovered by distillation at normal pressure or reduced pressure below 100°C.

An electroplating solution contains the above-mentioned leveler containing 2-substituted benzimidazole groups.

Preferably, the content of the leveler in the electroplating solution is 0.5-10 ppm.

Preferably, the electroplating solution contains, in addition to the leveler, a copper ion source, a halide ion source, an inhibitor, a brightener and an electrolyte.

More preferably, the copper ion source is selected from copper sulfate pentahydrate, the halide ion source is selected from hydrochloric acid, the inhibitor is selected from polyethylene glycol (PEG-10000), the brightener is selected from sodium polydisulfide propane sulfonate (SPS), and the electrolyte is selected from sulfuric acid.

Further preferably, the concentration of the copper ion source is 190-260 g/L (calculated as copper sulfate pentahydrate), the concentration of the halide ion source is 50-80 ppm (calculated as chloride ions), and the concentration of the electrolyte is 40-100 g/L (calculated as sulfuric acid).

Further preferably, the content of the inhibitor in the electroplating solution is 200-600 ppm, and the content of the brightener in the electroplating solution is 0.5-4 ppm.

Application of the above electroplating solution in blind hole copper electroplating.

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

(1) The group at the 2-substituted position in the leveling agent containing 2-substituted benzimidazole groups of the present invention plays an electron-withdrawing role in the benzimidazole ring. In the process of polymerizing the 2-substituted benzimidazole compound and the diglycidyl ether compound to form the polyquaternary ammonium salt, the positive charge of the polyquaternary ammonium salt is further enhanced compared with the benzimidazole quaternary ammonium salt without a substituent, so that the leveling agent is more easily adsorbed on the surface copper and thus inhibits the deposition of copper ions. The 2-substituted benzimidazole group can be complexed with the copper surface to form a dipole bond, and has a higher binding force to the copper surface. The high binding force makes it difficult for the leveling agent to be desorbed once it is bound to the surface copper. At the same time, the presence of the group at the 2-substitution position can also make the leveler have a molecular structure with a large steric hindrance, further increasing the difficulty of the leveler entering and adsorbing in the hole, making the concentration of the leveler in the hole much less than that outside the hole, resulting in the leveler being difficult to inhibit the hole, and the deposition in the hole is fast, and the deposition outside the hole is slow, so that a large deposition rate difference is formed inside and outside the blind hole, so that the blind hole electroplating has the effects of fast copper filling speed, low surface copper thickness, basically no gaps in filling, and good appearance, which meets the production requirements of blind hole electroplating, improves production efficiency, and reduces process costs.

(2) The present invention innovatively uses 2-substituted benzimidazole as a monomer, uses a solvent to dissolve the water-insoluble 2-substituted benzimidazole, and then adds a diglycidyl ether compound for homogeneous polymerization. As the polymerization proceeds, the N-quaternary ammonium salt on the benzimidazole ring and the epoxy structure are opened to generate hydroxyl groups, so that the water solubility of the polymer is continuously enhanced. Finally, the solvent is recovered and water and acid are added to form a homogeneous aqueous solution to obtain a leveling agent, thereby expanding a new series of blind hole leveling agents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a plated part obtained after blind hole electroplating using the leveler obtained in Example 1.

FIG. 2 is a cross-sectional view of a plated part obtained after blind hole electroplating using the leveler obtained in Example 2.

FIG3 is a cross-sectional view of a plated part obtained after blind hole electroplating using the leveler obtained in Comparative Example 1.

FIG. 4 is a cross-sectional view of a plated component obtained after blind hole electroplating using the leveler obtained in Comparative Example 2.

FIG5 is a cross-sectional view of a plated part obtained after blind hole electroplating using the leveler obtained in Comparative Example 3.

FIG. 6 is a cross-sectional view of a plated part obtained after blind hole electroplating using the leveler obtained in Comparative Example 4.

FIG. 7 is a board surface diagram after blind hole electroplating using the leveling agent obtained in Example 1.

FIG8 is a board surface diagram after blind hole electroplating using the leveler obtained in Comparative Example 2.

FIG. 9 is a board surface diagram after blind hole electroplating using the leveler obtained in Comparative Example 4.

DETAILED DESCRIPTION

In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

Example 1

Take 21.8g (0.1mol) of 2-heptylbenzimidazole and add it to a 250mL round-bottom flask equipped with a stirrer, a condenser, a thermometer, and a dropping funnel. Add 130.8g of methanol, heat to 40°C, slowly drop 20.4g (0.1mol) of 1,4-butanediol diglycidyl ether, and after the dropwise addition completes the reaction to a homogeneous system, continue to heat and reflux to continue the reaction for 2h, recover the methanol by atmospheric distillation, cool to room temperature, add 90g of water and 12mL of 50% sulfuric acid solution to the polymer and adjust to pH = 1 to obtain a yellow liquid, which is a leveler containing 2-heptylbenzimidazole groups, and the number average molecular weight of the polymer contained in the leveler is 2130.

Example 2

Take 19.0g (0.1mol) of 2-pentylbenzimidazole and add it into a 250mL round-bottom flask equipped with a stirrer, a condenser, a thermometer, and a dropping funnel. Add 95g of methanol, heat to 40°C, and slowly drop 20.4g (0.1mol) of 1,4-butanediol diglycidyl ether. After the dropwise addition is completed and the reaction becomes a homogeneous system, continue to heat and heat to reflux and continue the reaction for 2h. Recover methanol by atmospheric distillation, cool to room temperature, add 90g of water and 12mL of 50% sulfuric acid solution to the polymer and adjust to pH=1 to obtain a yellow liquid, which is a leveler containing 2-pentylbenzimidazole groups. The number average molecular weight of the polymer contained in the leveler is 1886.

Example 3

Take 23.2g (0.11mol) of 2-octylbenzimidazole and add it to a 250mL round-bottom flask with a stirrer, a condenser, a thermometer, and a dropping funnel. Add 139.2g of ethanol, heat to 40°C, slowly drop 20.4g (0.1mol) of 1,4-butanediol diglycidyl ether, and after the dropwise addition completes the reaction to a homogeneous system, continue to heat and reflux to continue the reaction for 3h, recover the ethanol by atmospheric distillation, cool to room temperature, add 90g of water and 12mL of 50% sulfuric acid solution to the polymer and adjust to pH = 1.5 to obtain a yellow liquid, which is a leveler containing 2-octylbenzimidazole groups. The number average molecular weight of the polymer contained in the leveler is 2417.

Example 4

Take 22.0g (0.09mol) of 2-p-chlorobenzylbenzimidazole and add it to a 250mL round-bottom flask with a stirrer, a condenser, a thermometer, and a dropping funnel. Add 154g of ethanol, heat to 50°C, and slowly drop 20.4g (0.1mol) of 1,4-butanediol diglycidyl ether. After the dropwise addition is completed and the reaction is a homogeneous system, continue to heat and heat to reflux and continue the reaction for 4.5h. Recover the ethanol by atmospheric distillation, cool to room temperature, add 90g of water and 10mL of 50% sulfuric acid solution to the polymer and adjust the pH to 1.3 to obtain a yellow liquid, which is a leveler containing 2-p-chlorobenzylbenzimidazole groups. The number average molecular weight of the polymer contained in the leveler is 3674.

Example 5

Take 22.4g (0.08mol) of 2-(2,4-dichlorobenzyl)benzimidazole and add it into a 250mL round-bottom flask equipped with a stirrer, a condenser, a thermometer, and a dropping funnel. Add 134.4g of tetrahydrofuran, heat to 50°C, slowly drop 20.4g (0.1mol) of 1,4-butanediol diglycidyl ether, and after the dropwise addition is completed and the reaction is a homogeneous system, continue to heat and heat to reflux and continue the reaction for 5h, recover tetrahydrofuran by atmospheric distillation, cool to room temperature, add 90g of water and 10mL of 50% sulfuric acid solution to the polymer and adjust the pH to 1.5 to obtain a yellow liquid, which is a leveler containing 2-(2,4-dichlorobenzyl)benzimidazole groups. The number average molecular weight of the polymer contained in the leveler is 4821.

Example 6

Take 28.0g (0.1mol) of 2-(3,4-dichlorobenzyl)benzimidazole and add it into a 250mL round-bottom flask equipped with a stirrer, a condenser, a thermometer, and a dropping funnel. Add 140g of toluene, heat to 50°C, slowly drop 23.2g (0.1mol) of 1,6-hexanediol diglycidyl ether, and after the dropwise addition is completed and the reaction is a homogeneous system, continue to heat and heat to reflux and continue the reaction for 2h, recover the toluene by vacuum distillation, cool to room temperature, add 90g of water and 12mL of 50% sulfuric acid solution to the polymer and adjust the pH to 1 to obtain a yellow liquid, which is a leveler containing 2-(3,4-dichlorobenzyl)benzimidazole groups, and the number average molecular weight of the polymer contained in the leveler is 2747.

Example 7

10.9 g (0.05 mol) of 2-heptylbenzimidazole and 12.2 g (0.05 mol) of 2-p-chlorobenzylbenzimidazole were added to a 250 mL round-bottom flask equipped with a stirrer, a condenser, a thermometer, and a dropping funnel. 138.6 g of ethanol was added, and the temperature was raised to 40°C, and 23.2 g (0.1 mol) of 1,6-hexanediol diglycidyl ether was slowly added dropwise. After the addition was completed and the reaction was completed to a homogeneous system, the temperature was continued to be raised to reflux and the reaction was continued for 3 hours. The ethanol was recovered by atmospheric distillation, and the polymer was cooled to room temperature. 90 g of water and 12 mL of 50% sulfuric acid solution were added to the polymer to adjust the pH to 1 to obtain a yellow liquid, which was a leveler containing 2-heptylbenzimidazole and 2-p-chlorobenzylbenzimidazole groups. The number average molecular weight of the polymer contained in the leveler was 2674.

Example 8

10.54 g (0.05 mol) of 2-octylbenzimidazole and 14.0 g (0.05 mol) of 2-(3,4-dichlorobenzyl)benzimidazole were added to a 250 mL round-bottom flask equipped with a stirrer, a condenser, a thermometer, and a dropping funnel. 128.4 g of toluene was added, and the temperature was raised to 50° C., and 23.2 g (0.1 mol) of 1,6-hexanediol diglycidyl ether was slowly added dropwise. After the addition was completed and the reaction was completed to a homogeneous system, the temperature was continued to be raised to reflux and the reaction was continued for 6 hours. The toluene was recovered by vacuum distillation, and the polymer was cooled to room temperature. 90 g of water and 12 mL of 50% sulfuric acid solution were added to the polymer to adjust the pH to 1 to obtain a yellow liquid, which was a leveler containing 2-octylbenzimidazole and 2-(3,4-dichlorobenzyl)benzimidazole groups. The number average molecular weight of the polymer contained in the leveler was 8314.

Comparative Example 1

Take 14.65g (0.1mol) of 2-phenylimidazole and add it to a 250mL round-bottom flask equipped with a stirrer, a condenser, a thermometer, and a dropping funnel. Add 130.8g of methanol, heat to 40°C, and slowly drop 20.4g (0.1mol) of 1,4-butanediol diglycidyl ether. After the dropwise addition completes the reaction to a homogeneous system, continue to heat and heat to reflux and continue the reaction for 2h. Recover methanol by atmospheric distillation, cool to room temperature, add 90g of water and 12mL of 50% sulfuric acid solution to the polymer and adjust to pH = 1 to obtain a yellow liquid, which is a leveler containing 2-phenylimidazole groups. The number average molecular weight of the polymer contained in the leveler is 1673.

Comparative Example 2

This comparative example provides a leveling agent, and its preparation process is basically the same as that of comparative example 1, except that: 2-phenylimidazole is replaced by 4-phenylimidazole, and the number average molecular weight of the polymer contained in the leveling agent is 1641.

Comparative Example 3

This comparative example provides a leveler containing 4-phenylimidazole groups purchased from the market, which is prepared from 4-phenylimidazole and 1,4-butanediol diglycidyl ether in a molar ratio of 1:1 using water as a solvent. The number average molecular weight of the polymer contained in the leveler is 1577.

Comparative Example 4

This comparative example provides a leveling agent, and its preparation process is basically the same as that of comparative example 1, except that: 2-phenylimidazole is replaced by benzimidazole, the added mass of benzimidazole is 11.93g, and the number average molecular weight of the polymer contained in the leveling agent is 1518.

Performance Testing

Preparation of electroplating solution: The leveling agents in Examples 1 to 8 and Comparative Examples 1 to 4 were respectively prepared into electroplating solutions according to the formulas in Table 1.

Table 1. Via-filling copper plating solutions

Electroplating method: In a 1.5L Haring trough equipped with an aeration stirring device (aeration rate: 4L/min) and having a phosphor copper plate as an anode and containing the electroplating solutions obtained in Examples 1 to 8 and Comparative Examples 1 to 4, a blind hole double-sided board with a hole diameter of 100μm and a boundary thickness of 80-90μm was placed after chemical copper deposition (chemical copper deposition is to deposit a copper layer of less than 1μm in the originally non-conductive blind hole to make the hole conductive, which is convenient for subsequent blind hole electroplating.) and electroplated for 60min under direct current and a current density of 1.6ASD to obtain each test board.

Among them, before the blind hole double-sided board test, it was degreased (40℃) for 1min, washed with water, micro-etched (persulfate system) for 1min, washed with water, and pickled for 1min.

After the electroplating is completed, each test board is sliced, and the Dimple value (depression value) and the surface copper thickness of the blind hole in each test board are calculated based on the blind hole slice diagram test, and the results are shown in Table 2. In addition, the blind hole slice diagrams obtained by electroplating in Example 1-Example 2 are shown in Figures 1-2, the blind hole slice diagrams obtained by electroplating in Comparative Example 1-Comparative Example 4 are shown in Figures 3-6, the board surface diagram of the blind hole after electroplating in Example 1 is shown in Figure 7, and the board surface diagrams of the blind holes after electroplating in Comparative Example 2 and Comparative Example 4 are shown in Figures 8 and 9.

Among them, the Dimple value reflects the blind hole filling ability, that is, the depression value of the copper thickness deposited in the blind hole relative to the copper layer deposited on the surface of the test board. If the center of the blind hole plating layer is depressed downward after copper plating, the Dimple value is positive, and if the center of the plating layer protrudes from the copper surface, the Dimple value is negative. The closer the Dimple value is to 0 in the positive range, the better the filling ability of the electroplating solution and the leveler therein.

Calculation method of Dimple value: Dimple value = thickness of copper layer from bottom of blind hole to surface - height of copper inside blind hole.

The surface copper thickness is the thickness of the copper layer covering the surface of the test board after blind hole electroplating. If the surface copper thickness is too thin, it is easy to cause a large concave value, requiring additional subsequent processing (increasing the surface copper thickness), and then thinning the copper process to reduce the concave problem, resulting in an increase in production procedures and costs. If the surface copper thickness is too thick, it is impossible to prepare fine circuits during the circuit etching process due to the influence of side etching, and it is impossible to produce precision process products, which is not conducive to the production of fine circuits.

Table 2. Electroplating test results

It can be seen from Table 2 and Figures 1, 2 and 7 that after the electroplating solution containing the leveler obtained in Examples 1-8 of the present invention is used for blind hole electroplating, the depression value of the blind hole is between 4μm and 10μm, and the surface copper thickness is between 15μm and 18μm, and there is no hole packing phenomenon in the hole, and the board surface is smooth and free of copper nodules, which meets the production requirements. This shows that the leveler prepared by the present invention has good hole filling performance. When the hole filling effect is good, the surface copper thickness is low, the amount of copper can be reduced in production, and the production cost and difficulty can be effectively reduced.

From the electroplating results of the levelers synthesized in Comparative Examples 1 and 2, it can be seen that although the depression value and the surface copper thickness can meet the production requirements, they are still significantly inferior to those of Examples 1-8, and the phenomena of hole inclusion in the hole and copper nodules on the board surface appear respectively. The copper nodules are shown as the raised dots in FIG8 and are scattered in the center and edge of the board surface. It can be seen that, under the same preparation method, the leveler containing 2-substituted benzimidazole groups is significantly superior to the leveler containing substituted imidazole groups in terms of board surface and hole filling properties.

From the electroplating results of the leveler purchased from the market in Comparative Example 3, it can be seen that the depression value is 15.97 μm and the copper surface thickness is 19.79 μm, which are obviously inferior to the levelers of Examples 1-8, and the hole filling depression value is also worse than that of Comparative Example 2. This shows that the leveler prepared by the preparation method of the present invention is superior to the leveler prepared by the currently commonly used water solvent synthesis method in terms of hole filling performance.

It can be seen from the electroplating results of the leveling agent of comparative example 4 and Figure 9 that the depression value is 10.07 μm and the copper surface thickness is 19.62 μm, which is also significantly inferior to the leveling agents of Examples 1-8. In addition, copper nodules appear on the board surface. A large number of copper nodules are scattered at the edge of the board surface, and a small number are scattered in the center of the board surface. This shows that the substituent at the 2-substitution position on the benzimidazole plays a role in significantly improving the hole filling efficiency and optimizing the board surface.

In summary, whether in terms of the structure or preparation method of the leveling agent, the present invention is innovative and has superior performance compared to the structures and preparation methods currently commonly used in the industry.

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 (9)

1. A leveling agent containing 2-substituted benzimidazole groups, characterized in that the leveling agent containing 2-substituted benzimidazole groups comprises an effective component, the effective component is a polymer obtained by reacting a 2-substituted benzimidazole compound with a diglycidyl ether compound, and the structural formulas of the 2-substituted benzimidazole compound and the diglycidyl ether compound are shown in Formula I and Formula II, respectively: Wherein, _R1 of the 2-substituted benzimidazole compound is one of _C5 - _C10 alkyl, p-halobenzyl, 2,4-dihalobenzyl, and 3,4-dihalobenzyl; R ₂ of the diglycidyl ether compound is a C ₁ -C ₁₀ alkyl group. 2. The leveler containing 2-substituted benzimidazole groups according to claim 1, characterized in that the number average molecular weight of the polymer is 500-25000. 3. The leveler containing 2-substituted benzimidazole groups according to claim 1, characterized in that the number average molecular weight of the polymer is 500-10000. 4. A method for preparing a leveler containing a 2-substituted benzimidazole group, characterized in that the preparation method comprises the following steps: The 2-substituted benzimidazole compound is dissolved in a solvent, a diglycidyl ether compound is added dropwise to carry out a condensation reaction to obtain a polymer, and after distilling and recovering the solvent, appropriate amounts of water and sulfuric acid solution are added to the polymer to adjust the pH to acidic to obtain the leveling agent containing the 2-substituted benzimidazole group. 5. The preparation method according to claim 4, characterized in that the molar ratio of the 2-substituted benzimidazole compound to the diglycidyl ether compound is 0.5-2:1. 6 . The preparation method according to claim 4 , characterized in that the mass ratio of the 2-substituted benzimidazole compound to the solvent is 1:1-10. 7. The preparation method according to claim 3, characterized in that the solvent is one or more of methanol, ethanol, isopropanol, ethyl acetate, chloroform, tetrahydrofuran, toluene, and xylene. 8. An electroplating solution, characterized in that the electroplating solution contains the leveler containing 2-substituted benzimidazole groups according to any one of claims 1 to 7. 9. Use of the electroplating solution according to claim 8 in blind hole copper electroplating.