A copper surface micro-etching and roughening solution for fine lines, and a preparation method and application thereof

Abstract

The application discloses a fine line copper surface micro-etching and roughening solution and a preparation method and application thereof, and relates to the technical field of printed circuit board manufacturing. The fine line copper surface micro-etching and roughening solution comprises the following components in mass concentration: sulfuric acid 60-100 g / L, hydrogen peroxide 40-60 g / L, zinc sulfate 0.5-2 g / L, copper ions 10-30 g / L, pyridine heterocyclic Schiff base 0.5-1 g / L, ethanol 10-100 g / L, 2-mercaptobenzothiazole 1-3 g / L, methionine 1-5 g / L, and polyacrylamide 1-5 g / L. The 2-mercaptobenzothiazole and methionine in the copper surface micro-etching and roughening solution can form a honeycomb structure on the copper surface under a lower etching amount, and the zinc sulfate and the pyridine heterocyclic Schiff base can form a composite film layer with the copper ions on the surface of the honeycomb structure, so that the interlayer adhesion is improved.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board manufacturing technology, and in particular to a copper surface micro-etching roughening solution for fine circuits, its preparation method and application. Background Technology

[0002] In the manufacturing process of printed circuit boards (PCBs), to ensure stable adhesion between the copper surface and the subsequently applied resist or photoresist film, pretreatment of the copper surface is necessary before the film application process. Currently, the industry employs differentiated copper surface treatment processes for PCBs of different grades: low-end PCBs typically use mechanical brushing or traditional chemical micro-etching processes. While these processes are less expensive, their roughening effect is limited, and the increase in copper surface area is not significant, making it difficult to meet the requirements for high adhesion. Mid- to high-end PCBs generally use copper surface micro-etching roughening processes. This process creates a honeycomb-like rough structure on the copper surface, significantly increasing the copper surface area and greatly improving the adhesion between the film layer and the copper surface. It is a key process for ensuring the quality of mid- to high-end PCB products.

[0003] As consumer electronics products rapidly evolve towards miniaturization, portability, and multifunctionality, PCB products continue to evolve towards high-density wiring, high speed, and high frequency. Among these, the line width / spacing (L / S) of fine printed circuit boards such as HDI / BUM boards has evolved from the traditional 50μm / 50μm to specifications below 30μm / 30μm or even finer. During the manufacturing process of fine printed circuit boards, the significant reduction in line width / spacing (L / S) results in a substantial decrease in the actual contact area between the film layer and the copper surface, placing higher demands on the adhesion between the copper surface and the film layer.

[0004] Traditional copper surface etching and roughening solutions typically follow the logic that "the greater the etching amount, the better the roughening effect and the stronger the adhesion." To achieve optimal roughening, the etching amount is generally controlled at 1-2 μm. However, a large etching amount can easily lead to problems such as thinner lines, open circuits, or increased impedance due to changes in the cross-sectional shape of the lines during subsequent fine circuit processing. These problems become more pronounced as the line width and spacing narrower: for PCBs with a line width / spacing greater than 50 μm / 50 μm, the impact of a large etching amount from traditional etching and roughening solutions can be partially offset by adjusting subsequent process parameters, still meeting the needs of mass production; however, for fine circuits with a line width / spacing less than 30 μm / 30 μm, the excessive etching amount of traditional etching and roughening solutions directly affects the integrity of the circuit pattern, leading to decreased product yield, unstable characteristic impedance, and failure to meet the production requirements of fine circuit PCBs. Therefore, developing a copper surface etching and roughening solution with low etching amount and high adhesion for fine circuits has become crucial to solving the current industry pain points. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a copper surface micro-etching roughening solution for fine circuits, its preparation method, and its application. Specifically, it is a copper surface micro-etching roughening solution suitable for high-density interconnect (HDI) boards, multilayer boards (BUM), and other fine-line printed circuit boards (PCBs), along with its preparation method and application. This solution can achieve low etching volume while ensuring high adhesion between the copper surface and the film layer, effectively solving problems such as line thinning, open circuits, and impedance abnormalities in the production of fine circuits with line widths / spacings below 30μm / 30μm. This meets the demand for high-density PCB wiring in the miniaturization and portability development of consumer electronics products.

[0006] Specifically, the following technical solutions are included:

[0007] In one aspect, a copper surface micro-etching roughening solution for fine circuits is provided, comprising the following components by mass concentration: sulfuric acid 60-100 g / L, hydrogen peroxide 40-60 g / L, zinc sulfate 0.5-2 g / L, copper ions 10-30 g / L, pyridine heterocyclic Schiff base 0.5-1 g / L, ethanol 10-100 g / L, 2-mercaptobenzothiazole 1-3 g / L, methionine 1-5 g / L, and polyacrylamide 1-5 g / L.

[0008] Furthermore, the mass ratio of zinc sulfate to pyridine heterocyclic Schiff base is 1:(0.5-1).

[0009] Furthermore, the copper surface micro-etching roughening solution for fine circuits is composed of the following components by mass concentration: sulfuric acid 60-100 g / L, hydrogen peroxide 40-60 g / L, copper ions 10-30 g / L, zinc sulfate 0.5-2 g / L, pyridine heterocyclic Schiff base 0.5-1 g / L, ethanol 10-100 g / L, 2-mercaptobenzothiazole 1-3 g / L, methionine 1-5 g / L, polyacrylamide 1-5 g / L, with the balance being deionized water.

[0010] Furthermore, the copper surface micro-etching roughening solution for fine circuits is composed of the following components by mass concentration: sulfuric acid 60-100 g / L, hydrogen peroxide 40-60 g / L, copper ions 10-30 g / L, zinc sulfate 0.5-1 g / L, pyridine heterocyclic Schiff base 0.5-0.7 g / L, ethanol 10-100 g / L, 2-mercaptobenzothiazole 2-3 g / L, methionine 3-5 g / L, polyacrylamide 1-3 g / L, with the balance being deionized water.

[0011] Furthermore, the copper ions are derived from copper sulfate pentahydrate or copper oxide; the pyridine-containing heterocyclic Schiff base is selected from one of o-formylphenoxyacetic acid isoniazid and cinnamaldehyde isoniazid.

[0012] Preferably, the o-formylphenoxyacetic acid condensed isoniazid is a condensation product of o-formylphenoxyacetic acid and isoniazid, and the cinnamaldehyde condensed isoniazid is a condensation product of cinnamaldehyde and isoniazid.

[0013] Secondly, a method for preparing a copper surface micro-etching roughening solution for fine circuits as described in the first aspect is provided, comprising the following steps:

[0014] S1. Take deionized water, add sulfuric acid under stirring, and wait for the sulfuric acid to completely dissolve and the solution temperature to drop to room temperature to obtain an aqueous sulfuric acid solution;

[0015] S2. Add copper ions, zinc sulfate, a pyridine heterocyclic Schiff base solution, 2-mercaptobenzothiazole, methionine, and polyacrylamide sequentially to the sulfuric acid aqueous solution obtained in step S1. After each component is added, stir continuously for 15-20 minutes until the component is completely dissolved to obtain a mixed solution. The pyridine heterocyclic Schiff base solution is prepared by dissolving a pyridine heterocyclic Schiff base in ethanol.

[0016] S3. Under stirring conditions, hydrogen peroxide is added to the mixed solution obtained in step S2, and stirring is continued for 30 minutes to make the solution uniformly mixed, thus obtaining the copper surface micro-etching roughening solution for fine circuits.

[0017] Furthermore, in step S1, the stirring rate of the stirring conditions is 300-500 r / min, and the room temperature is 25±2℃.

[0018] Thirdly, a method for roughening copper surface micro-etching is provided, in which the fine lines described in the first aspect are sprayed onto the copper surface of the PCB board using a copper surface micro-etching roughening solution.

[0019] Furthermore, the spraying method is horizontal spraying, and the spraying pressure is 2-4 kg / cm². 2 .

[0020] Furthermore, the temperature of the copper surface micro-etching roughening solution for fine circuits is 25-35℃, and the spraying time is 30-60s.

[0021] Preferably, the copper surface micro-etching roughening treatment method further includes the following steps: after spraying, rinse with deionized water for 2-3 minutes, and then dry at 80-90℃ for 2-3 minutes to complete the copper surface micro-etching roughening treatment.

[0022] The beneficial effects of this invention are as follows: 2-Mercaptobenzothiazole and methionine in the copper surface micro-etching and roughening solution for fine circuits can reduce the micro-etching rate of copper, allowing the copper surface to form a honeycomb structure at a lower micro-etching amount. Zinc sulfate and pyridine-containing heterocyclic Schiff bases can form a composite film layer with copper ions on the surface of the honeycomb structure, which can improve interlayer adhesion. Furthermore, the synergistic effect of the components in the copper surface micro-etching and roughening solution for fine circuits overcomes the problem of defects and low yield in fine circuits caused by excessive micro-etching amounts in traditional copper surface micro-etching and roughening solutions. It achieves a roughening effect with micro-etching amount controlled at 0.3-0.8 μm, while ensuring high adhesion between the copper surface and the film layer, meeting the production requirements of fine circuit PCBs with line width / spacing below 30 μm / 30 μm. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 SEM images from Embodiment 1 of the present invention;

[0025] Figure 2 SEM image of Comparative Example 2 using the present invention. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0028] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0029] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0030] To better understand the technical content of the present invention, the technical solution of the present invention will be further introduced and explained below with reference to specific embodiments.

[0031] In the embodiments / comparative examples of the present invention, the pyridine-containing heterocyclic Schiff base is selected from one of o-formylphenoxyacetic acid isoniazid and cinnamaldehyde isoniazid.

[0032] The preparation method of o-formylphenoxyacetic acid isoniazid includes the following steps: dissolving 6 mmol of o-formylphenoxyacetic acid and 7 mmol of isoniazid in 100 mL of anhydrous ethanol, stirring and refluxing magnetically at 35 °C for 1 hour, and obtaining the product after the solvent has evaporated.

[0033] The preparation method of the cinnamaldehyde isoniazid includes the following steps: dissolving 6 mmol of cinnamaldehyde and 7 mmol of isoniazid in 100 mL of anhydrous ethanol, stirring and refluxing magnetically at 35°C for 1 hour, and obtaining the product after the solvent has evaporated.

[0034] Example 1:

[0035] A copper surface micro-etching and roughening solution for fine circuits comprises the following components by mass concentration: 80 g / L sulfuric acid, 50 g / L hydrogen peroxide, 1 g / L zinc sulfate, 20 g / L copper ions, 0.7 g / L pyridine heterocyclic Schiff base, 50 g / L ethanol, 2 g / L 2-mercaptobenzothiazole, 3 g / L methionine, 3 g / L polyacrylamide, and the balance being deionized water. The copper ions are derived from copper sulfate pentahydrate, and the pyridine heterocyclic Schiff base is o-formylphenoxyacetic acid isoniazid.

[0036] The preparation method of o-formylphenoxyacetic acid isoniazid includes the following steps: 6 mmol of o-formylphenoxyacetic acid and 7 mmol of isoniazid are dissolved in 100 mL of anhydrous ethanol, and the mixture is magnetically stirred and refluxed at 35 °C for 1 hour. After the solvent has evaporated, the product is obtained.

[0037] The preparation method of the copper surface micro-etching roughening solution for fine circuits includes the following steps:

[0038] S1. Take deionized water and add sulfuric acid under stirring conditions. The stirring rate is 400 r / min. Wait until the sulfuric acid is completely dissolved and the solution temperature drops to room temperature (25℃) to obtain an aqueous sulfuric acid solution.

[0039] S2. Add copper ions, zinc sulfate, a pyridine heterocyclic Schiff base solution, 2-mercaptobenzothiazole, methionine, and polyacrylamide sequentially to the sulfuric acid aqueous solution obtained in step S1. Stir continuously for 18 minutes after each addition until the component is completely dissolved to obtain a mixed solution. The pyridine heterocyclic Schiff base solution is prepared by dissolving a pyridine heterocyclic Schiff base in ethanol.

[0040] S3. Under stirring conditions, hydrogen peroxide is added to the mixed solution obtained in step S2, and stirring is continued for 30 minutes to make the solution uniformly mixed, thus obtaining the copper surface micro-etching roughening solution for fine circuits.

[0041] The copper surface micro-etching and roughening solutions for fine circuits in Examples 2-7 were prepared according to the formulations in Table 1 below. The preparation methods for the copper surface micro-etching and roughening solutions for fine circuits in Examples 2-7 were the same as those in Example 1.

[0042] Table 1. Formulations (mass concentration, g / L) of copper surface micro-etching roughening solutions for fine circuits in Examples 2-7

[0043]

[0044] In Table 1, the copper ions in Example 4 were provided by copper oxide, and the rest were provided by copper sulfate pentahydrate. The pyridine heterocyclic Schiff bases in Examples 2-4 of Table 1 were all o-formylphenoxyacetic acid isoniazid, and their preparation method was the same as in Example 1. The pyridine heterocyclic Schiff bases in Examples 5-7 of Table 1 were all cinnamaldehyde isoniazid. The preparation method of cinnamaldehyde isoniazid includes the following steps: dissolving 6 mmol of cinnamaldehyde and 7 mmol of isoniazid in 100 mL of anhydrous ethanol, stirring and refluxing magnetically at 35°C for 1 hour, and obtaining the solution after the solvent has evaporated. Comparative Examples 1-7 were prepared according to the formulation of the copper surface micro-etching roughening solution for fine circuits in Table 2 below. The preparation method of the copper surface micro-etching roughening solution for fine circuits in Comparative Examples 1-7 was the same as in Example 1.

[0045] Table 2 Formulations (mass concentration, g / L) of copper surface micro-etching roughening solutions for fine circuits in Comparative Examples 1-7

[0046]

[0047] In Table 2, the copper ions in Comparative Example 4 were provided by copper oxide, and the rest were provided by copper sulfate pentahydrate. All pyridine heterocyclic Schiff bases in Table 2 were o-formylphenoxyacetic acid isoniazid, and their preparation method was the same as in Example 1.

[0048] Comparative Examples 8-14 were prepared according to the formulations of the copper surface micro-etching and roughening solutions for fine circuits in Table 3 below. The preparation methods of the copper surface micro-etching and roughening solutions for fine circuits in Comparative Examples 8-14 were the same as those in Example 1.

[0049] Table 3 Formulations (mass concentration, g / L) of copper surface micro-etching roughening solutions for fine circuits in Comparative Examples 8-14

[0050]

[0051] In Table 3, the copper ions in Comparative Examples 8-14 were provided by copper sulfate pentahydrate. All pyridine heterocyclic Schiff bases in Table 3 are o-formylphenoxyacetic acid isoniazid, prepared using the same method as in Example 1.

[0052] The fine-line copper surface micro-etching roughening solution of the examples / comparative examples was used to perform copper surface micro-etching roughening treatment. The copper surface micro-etching roughening treatment method includes the following steps: the PCB board to be treated is processed through a horizontal spray pretreatment device according to the factory standard processing procedure. The ultra-roughening tank contains the fine-line copper surface micro-etching roughening solution prepared above. The fine-line copper surface micro-etching roughening solution is sprayed onto the copper surface of the PCB board. The spraying method is horizontal spraying, and the spraying pressure is 3 kg / cm². 2 The temperature of the copper surface micro-etching roughening solution for fine circuits is 30℃, and the spraying time is 40s. After spraying, rinse with deionized water for 2.5min, and then dry at 85℃ for 2.5min to complete the copper surface micro-etching roughening treatment. The test samples are tested according to the following performance test methods.

[0053] Performance testing:

[0054] 1. Surface morphology: The PCB boards of each embodiment and comparative example were observed with scanning electron microscope. A uniform honeycomb structure was considered acceptable, while a non-uniform or non-honeycomb structure was considered unacceptable.

[0055] 2. Micro-etching amount test:

[0056] The weighing method was used: Before micro-etching, the mass of the copper surface area of ​​the PCB board was weighed using an electronic balance (accuracy 0.1 mg) (recorded as m1). After micro-etching, the area was dried to constant weight and weighed again (recorded as m2). Based on the density of copper (8.96 g / cm³) and the area of ​​the copper surface test area (recorded as S), the micro-etching amount was calculated using the formula "micro-etching amount = (m1 - m2) / (ρ × S)". A micro-etching amount of 0.3-0.8 μm is considered acceptable.

[0057] 3. Bonding strength test:

[0058] The processed PCB board is laminated with film, and exposed and developed according to L / S=25μm / 25μm to create patterns. 3M tape (model 610) is applied to the dry film of the circuit and quickly peeled off. The film peeling is observed and rated as "0 level (no peeling) - 5 level (complete peeling)", with 0 level being the best.

[0059] 4. Line Defect Statistics:

[0060] For each embodiment and comparative example, 5 PCB boards were processed. After the circuit was completed, an optical inspection (AOI) instrument was used to perform a full inspection to count the number of open circuits and thin spots, requiring the number of defect points to be 0.

[0061] The fine circuits from Examples 1-7 were subjected to copper surface micro-etching roughening treatment using the copper surface micro-etching roughening solution, followed by performance testing. The test results are shown in Table 4 below.

[0062] Table 4 Performance test results of copper surface micro-etching roughening solutions for fine circuits in Examples 1-7

[0063]

[0064] in, Figure 1 The SEM image used in Embodiment 1 of the present invention. From Figure 1 As shown in Table 4, the copper surface micro-etching roughening solution for fine circuits in this embodiment of the invention performs well, with surface morphology, micro-etching amount, adhesion test, and circuit defect points all within the qualified range.

[0065] The fine lines in Comparative Examples 1-7 were roughened using a copper surface micro-etching roughening solution, and then their performance was tested. The test results are shown in Table 5 below.

[0066] Table 5 Performance test results of copper surface micro-etching roughening solutions for fine circuits in Comparative Examples 1-7

[0067]

[0068] in, Figure 2 SEM images of Comparative Example 2 using the present invention. (By...) Figure 2As shown in Table 5, the copper surface etching and roughening solution for fine circuits prepared without zinc sulfate and a pyridine heterocyclic Schiff base (Comparative Example 1) showed poor adhesion and circuit defect statistics in performance testing. The copper surface etching and roughening solutions for fine circuits prepared with sulfuric acid and hydrogen peroxide at concentrations outside the limits of this invention (Comparative Examples 2 and 3) showed poor surface morphology and circuit defect statistics in performance testing. Furthermore, the copper surface etching and roughening solution for fine circuits prepared using copper ions outside the concentration limits of this invention (Comparative Example 4) showed poor surface morphology in performance testing. The copper surface etching and roughening solution for fine circuits prepared using zinc sulfate and a pyridine heterocyclic Schiff base outside the concentration limits of this invention (Comparative Example 5) showed poor adhesion in performance testing. Furthermore, if 2-mercaptobenzothiazole and methionine, which are not within the mass concentration range specified in this invention, are used, the resulting copper surface micro-etching roughening solution for fine circuits (Comparative Example 6) exhibits poor surface morphology and circuit defect statistics in performance testing. If polyacrylamide, which is not within the mass concentration range specified in this invention, is used, the resulting copper surface micro-etching roughening solution for fine circuits (Comparative Example 7) exhibits poor surface morphology and circuit defect statistics in performance testing.

[0069] The fine lines of Comparative Examples 8-14 were roughened using a copper surface micro-etching solution, and then their performance was tested. The test results are shown in Table 6 below.

[0070] Table 6 Performance test results of the copper surface micro-etching roughening solution for fine circuits in Comparative Examples 8-14

[0071]

[0072] As shown in Table 6, the performance test results of the fine-line copper surface etching roughening solution (Comparative Example 8) prepared without 2-mercaptobenzothiazole were all poor. The surface morphology, adhesion, and circuit defect statistics of the fine-line copper surface etching roughening solution prepared without methionine (Comparative Example 9) were also poor. The adhesion and circuit defect statistics of the fine-line copper surface etching roughening solution prepared without zinc sulfate (Comparative Example 10) were also poor. The adhesion test results of the fine-line copper surface etching roughening solution prepared without pyridine heterocyclic Schiff bases (Comparative Example 11) were also poor. Furthermore, the circuit defect statistics of the fine-line copper surface etching roughening solution prepared using a pyridine heterocyclic Schiff base outside the mass concentration range specified in this invention (Comparative Example 12) were also poor. If 2-mercaptobenzothiazole, which is outside the mass concentration range specified in this invention, is used, the resulting copper surface micro-etching roughening solution for fine circuits (Comparative Example 13) exhibits poor surface morphology and circuit defect statistics in performance testing. If the mass ratio of zinc sulfate to a pyridine heterocyclic Schiff base is outside the range specified in this invention, the resulting copper surface micro-etching roughening solution for fine circuits (Comparative Example 14) exhibits poor circuit defect statistics in performance testing.

[0073] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A copper surface micro-etching roughening solution for fine circuits, characterized in that, The following components are included in the following mass concentrations: sulfuric acid 60-100 g / L, hydrogen peroxide 40-60 g / L, zinc sulfate 0.5-2 g / L, copper ions 10-30 g / L, pyridine-containing heterocyclic Schiff base 0.5-1 g / L, ethanol 10-100 g / L, 2-mercaptobenzothiazole 1-3 g / L, methionine 1-5 g / L, and polyacrylamide 1-5 g / L. The mass ratio of zinc sulfate to a pyridine heterocyclic Schiff base is 1:(0.5-1). The pyridine-containing heterocyclic Schiff base is selected from one of o-formylphenoxyacetic acid acetonitrile and cinnamaldehyde acetonitrile.

2. The copper surface micro-etching and roughening solution for fine circuits as described in claim 1, characterized in that, It consists of the following components in mass concentration: sulfuric acid 60-100 g / L, hydrogen peroxide 40-60 g / L, copper ions 10-30 g / L, zinc sulfate 0.5-2 g / L, pyridine heterocyclic Schiff base 0.5-1 g / L, ethanol 10-100 g / L, 2-mercaptobenzothiazole 1-3 g / L, methionine 1-5 g / L, polyacrylamide 1-5 g / L, with the balance being deionized water.

3. The copper surface micro-etching and roughening solution for fine circuits as described in claim 2, characterized in that, It consists of the following components in mass concentration: sulfuric acid 60-100 g / L, hydrogen peroxide 40-60 g / L, copper ions 10-30 g / L, zinc sulfate 0.5-1 g / L, pyridine heterocyclic Schiff base 0.5-0.7 g / L, ethanol 10-100 g / L, 2-mercaptobenzothiazole 2-3 g / L, methionine 3-5 g / L, polyacrylamide 1-3 g / L, with the balance being deionized water.

4. The copper surface micro-etching and roughening solution for fine circuits as described in claim 1, characterized in that, The copper ions mentioned are derived from copper sulfate pentahydrate or copper oxide.

5. The method for preparing the copper surface micro-etching roughening solution for fine circuits as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Take deionized water, add sulfuric acid under stirring, and wait for the sulfuric acid to completely dissolve and the solution temperature to drop to room temperature to obtain an aqueous sulfuric acid solution; S2. Add copper ions, zinc sulfate, a pyridine heterocyclic Schiff base solution, 2-mercaptobenzothiazole, methionine, and polyacrylamide sequentially to the sulfuric acid aqueous solution obtained in step S1. After each component is added, stir continuously for 15-20 minutes until the component is completely dissolved to obtain a mixed solution. The pyridine heterocyclic Schiff base solution is prepared by dissolving a pyridine heterocyclic Schiff base in ethanol. S3. Under stirring conditions, hydrogen peroxide is added to the mixed solution obtained in step S2, and stirring is continued for 30 minutes to make the solution uniformly mixed, thus obtaining the copper surface micro-etching roughening solution for fine circuits.

6. The method for preparing the copper surface micro-etching roughening solution for fine circuits as described in claim 5, characterized in that, In step S1, the stirring rate of the stirring conditions is 300-500 r / min, and the room temperature is 25±2℃.

7. A method for roughening copper surface through micro-etching, characterized in that, The fine-line copper surface roughening solution described in any one of claims 1-4 is sprayed onto the copper surface of the PCB board.

8. The copper surface micro-etching roughening treatment method as described in claim 7, characterized in that, The spraying method is horizontal spraying, and the spraying pressure is 2-4 kg / cm². 2 .

9. The copper surface micro-etching roughening treatment method as described in claim 7, characterized in that, The temperature of the copper surface micro-etching roughening solution for fine circuits is 25-35℃, and the spraying time is 30-60s.

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