An alkaline micro-etching solution, its preparation method and micro-etching method

Abstract

The present invention discloses an alkaline micro-etching solution, its preparation method and a micro-etching method, which relate to the technical field of printed circuit board production. The alkaline micro-etching solution is composed of the following components by mass concentration: 0.01 - 2 g / L of a polylactic acid block copolymer, 20 - 100 g / L of an inorganic base, 1 - 10 g / L of an organic base, 1 - 10 g / L of an organic carboxylic acid, 5 - 30 g / L of copper ions, 0.1 - 5 g / L of a corrosion inhibitor, and the balance is deionized water; the polylactic acid block copolymer is a block copolymer containing polylactic acid structural units. The alkaline micro-etching solution of the present invention regulates the dissolution rate of different copper crystal planes through the synergistic effect of the corrosion inhibitor, the organic carboxylic acid, the organic base and the polylactic acid block copolymer, optimizes the dissolution-etching process of copper in the microscopic region, reduces problems such as pinholes and pockmarks, effectively improves the etching uniformity of the copper surface of the circuit, and improves the quality yield of the printed circuit board.

Description

Technical Field

[0001] The present invention relates to the technical field of printed circuit board production, and particularly to an alkaline micro-etching solution, a preparation method thereof, and a micro-etching method. Background Art

[0002] With the development of electronic devices towards being light, thin, small, and high-performance, the lead pitch and line width of printed circuit boards (PCBs) are becoming increasingly fine, and the control requirements for line width and line pitch are becoming increasingly strict. In the major processes of PCB production and manufacturing, chemical micro-etching is required for the pretreatment of many processes, such as lamination, pattern transfer, electroplating, OSP (organic solderability protective layer), solder mask, ENIG (electroless nickel immersion gold), etc. The role of micro-etching is to form a microscopically uneven surface shape on the copper layer surface to enhance the bonding force with the copper plating layer and improve the thermal shock resistance and delamination resistance of the laminate. If the micro-etching depth is too shallow, the bonding force of the copper plating layer will be insufficient, resulting in delamination or peeling off in subsequent processes; if the micro-etching is too deep, it will not only increase the consumption of chemicals, but more seriously, it will cause excessive copper etching and even holes in the hole walls.

[0003] The basic principle of chemical micro-etching is to use sodium persulfate, hydrogen peroxide, copper chloride, etc. with strong oxidizing properties to chemically react with copper, playing a role in cleaning and roughening the copper surface. Currently, the commonly used micro-etching systems are the formic acid-copper chloride, sulfuric acid-sodium persulfate, and sulfuric acid-hydrogen peroxide systems. Using different micro-etching systems, the roughening effect on the copper surface is different, which in turn affects the bonding force between the copper surface and dry film, substrate, wet film, solder mask ink, etc. The etching rate of alkaline etching solution is usually faster than that of acidic etching solution, and more printed circuit boards can be processed in the same time, thereby improving production efficiency. The edge side etching of alkaline etching solution is smaller, which is particularly important for high-precision circuit manufacturing. Alkaline etching has a milder effect on materials and less damage to materials. The etching solution can be recycled, reducing production costs. Abnormal processing of acidic micro-etching solution will lead to excessive etching of copper pads on the copper surface, resulting in a reduction in the effective area of the pads, affecting the SMT (surface mounting technology) mounting reliability, and non-uniform thinning of the copper thickness, causing microvia open circuits, and thus severely reducing the batch yield of the product. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides an alkaline micro-etching solution, a preparation method thereof, and a micro-etching method. This alkaline micro-etching solution can effectively etch the copper surface, and the etched copper surface has a uniform color and high flatness. At the same time, it has no corrosive effect on other metals such as nickel, silver, and gold, meeting the requirements of circuit board enterprises for high-quality micro-etching solutions.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In the first aspect, an alkaline micro-etching solution is provided, which is composed of the following components in mass concentration:

[0007] 0.01 - 2 g / L of polylactic acid block copolymer, 20 - 100 g / L of inorganic base, 1 - 10 g / L of organic base, 1 - 10 g / L of organic carboxylic acid, 5 - 30 g / L of copper ions, 0.1 - 5 g / L of corrosion inhibitor, and the balance is deionized water; the polylactic acid block copolymer is a block copolymer containing polylactic acid structural units.

[0008] Further, the block copolymer containing polylactic acid structural units is selected from one or more of polylactic acid - polyethylene glycol - polylactic acid copolymer (PLA - PEG - PLA), polylactic acid - polyethylene glycol - polylysine copolymer (PLA - PEG - PLL), polylactic acid - polycaprolactone - polyethylene glycol - polycaprolactone - polylactic acid copolymer (PLA - PCL - PEG - PCL - PLA), polyethyleneimine - polyethylene glycol - polylactic acid copolymer (PEI - PEG - PLA), and polylactic acid - polyethylene glycol - maleimide copolymer (PLA - PEG - MAL).

[0009] Further, the average molecular weight of the polylactic acid block copolymer is 500 - 10000.

[0010] Further, the inorganic base is selected from one or more of ammonia water, sodium hydroxide, potassium hydroxide, and calcium hydroxide; the organic base is selected from one or more of dopamine, diethylenetriamine, tetraethylenepentamine, hexamethylenetetramine, triethanolamine, and hydroxyethyl ethylenediamine.

[0011] Further, the organic carboxylic acid is selected from one or more of citric acid, malic acid, succinic acid, and benzoic acid; the copper ions are selected from at least one of copper sulfate, copper nitrate, and copper acetate.

[0012] Further, the corrosion inhibitor is a mixture of benzimidazole derivatives and benzotriazole derivatives, and the mass ratio of benzimidazole derivatives to benzotriazole derivatives is 1:(1 - 10).

[0013] Further, the benzimidazole derivatives are selected from at least one of 2 - amino - 5 - nitro - 1H - benzimidazole, 5 - amino - 2 - mercaptobenzimidazole, benzimidazole - 5,6 - dicarboxylic acid, and 5 - ethoxy - 2 - mercaptobenzimidazole.

[0014] Further, the benzotriazole derivatives are selected from at least one of 2 - (1 - benzotriazolyl)acetic acid, 1 - aminobenzotriazole, 4 - hydroxybenzotriazole, 5 - aminobenzotriazole, 5 - benzotriazolecarboxylic acid, and 4 - carboxybenzotriazole.

[0015] Second aspect: Provided is a method for preparing the alkaline micro-etching solution as described in the first aspect, including the following steps: After weighing an inorganic base, an organic base, an organic carboxylic acid, copper ions, a corrosion inhibitor, and a polylactic acid block copolymer, dissolve them in deionized water, mix, stir, and make up the volume to obtain the described alkaline micro-etching solution.

[0016] Third aspect: Provided is a micro-etching method, including the following steps: Use the alkaline micro-etching solution described in the first aspect to etch a circuit board. The etching method is horizontal line spraying, and the spraying pressure is 0.8 - 2 kg / cm 2 , the temperature is 25 - 40 °C, and the etching time is 30 - 120 s.

[0017] The beneficial effects of the present invention are as follows:

[0018] (1) The alkaline micro-etching solution of the present invention uses a polylactic acid block copolymer, an organic carboxylic acid, an inorganic base, and an organic base to form a buffer system, thereby ensuring the stable and controllable etching rate;

[0019] (2) The alkaline micro-etching solution of the present invention uses a heterocyclic compound containing nitrogen, oxygen, and sulfur in the molecular chain, an organic base, and a polylactic acid block copolymer, which can form π bonds or covalent bonds with copper atoms, regulate the dissolution rate of different copper crystal planes, optimize the dissolution-etching process of copper in the microscopic region, greatly improve the etching uniformity of the copper surface, and significantly optimize the micro-etching roughening effect. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 It is a scanning electron microscope photograph of the copper surface after being treated by the micro-etching method using the alkaline micro-etching solution of Example 1 of the present invention. Detailed Embodiments

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are some, rather than all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0023] 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, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or their combinations.

[0024] It should also be understood that the terminology used in this specification of the present invention is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used in this specification of the present invention and the appended claims, unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0025] It should be further understood that the term " / and" used in this specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0026] To more fully understand the technical content of the present invention, the technical solutions of the present invention will be further introduced and described below in conjunction with specific embodiments.

[0027] Example 1

[0028] An alkaline micro-etching solution is composed of the following components by mass concentration:

[0029] Polylactic acid block copolymer 0.05 g / L, inorganic base (ammonia water) 30 g / L, organic base (dopamine) 2 g / L, organic carboxylic acid (benzoic acid) 5 g / L, copper ions (copper sulfate) 10 g / L, corrosion inhibitor 0.6 g / L, and the balance is deionized water; the polylactic acid block copolymer is a polylactic acid-polyethylene glycol-polylactic acid copolymer (PLA-PEG-PLA); the corrosion inhibitor is composed of 2-amino-5-nitro-1H-benzimidazole with a mass concentration of 0.1 g / L and 5-aminobenzotriazole with a mass concentration of 0.5 g / L.

[0030] The preparation method of the alkaline micro-etching solution of Example 1 includes the following steps: After weighing the inorganic base, organic base, organic carboxylic acid, copper ions, corrosion inhibitor and polylactic acid block copolymer, dissolve them in deionized water, mix, stir, and make up the volume to obtain the alkaline micro-etching solution.

[0031] A micro-etching method includes the following steps: Using the alkaline micro-etching solution described in Example 1 to etch a circuit board, the etching method is horizontal line spraying, the spraying pressure is 1.2 kg / cm 2 , the temperature is 30 °C, and the etching time is 60 s.

[0032] Example 2

[0033] An alkaline micro-etching solution is composed of the following components by mass concentration:

[0034] 0.1 g / L of polylactic acid block copolymer, 25 g / L of inorganic base (potassium hydroxide), 5 g / L of organic base (tetraethylenepentamine), 4 g / L of organic carboxylic acid (succinic acid), 8 g / L of copper ions (copper sulfate), 0.7 g / L of corrosion inhibitor, and the balance is deionized water; the polylactic acid block copolymer is polylactic acid-polyethylene glycol-polylysine copolymer (PLA-PEG-PLL); the corrosion inhibitor is composed of 5-ethoxy-2-mercaptobenzimidazole with a mass concentration of 0.2 g / L and 4-carboxybenzotriazole with a mass concentration of 0.5 g / L.

[0035] Example 3

[0036] An alkaline micro-etching solution is composed of the following components by mass concentration:

[0037] 0.08 g / L of polylactic acid block copolymer, 35 g / L of inorganic base (sodium hydroxide), 8 g / L of organic base (dopamine), 6 g / L of organic carboxylic acid (benzoic acid), 5 g / L of copper ions (copper acetate), 0.8 g / L of corrosion inhibitor, and the balance is deionized water; the polylactic acid block copolymer is polylactic acid-polycaprolactone-polyethylene glycol-polycaprolactone-poly lactic acid copolymer (PLA-PCL-PEG-PCL-PLA); the corrosion inhibitor is composed of 2-amino-5-nitro-1H-benzimidazole with a mass concentration of 0.1 g / L and 2-(1-benzotriazolyl)acetic acid with a mass concentration of 0.7 g / L.

[0038] Example 4

[0039] An alkaline micro-etching solution is composed of the following components by mass concentration:

[0040] 0.1 g / L of polylactic acid block copolymer, 40 g / L of inorganic base (ammonia water), 4 g / L of organic base (diethylenetriamine), 8 g / L of organic carboxylic acid (citric acid), 15 g / L of copper ions (copper nitrate), 0.9 g / L of corrosion inhibitor, and the balance is deionized water; the polylactic acid block copolymer is polyethyleneimine-polyethylene glycol-poly lactic acid copolymer (PEI-PEG-PLA); the corrosion inhibitor is composed of 2-amino-5-nitro-1H-benzimidazole with a mass concentration of 0.3 g / L and 4-hydroxybenzotriazole with a mass concentration of 0.6 g / L.

[0041] Example 5

[0042] An alkaline micro-etching solution is composed of the following components by mass concentration:

[0043] 0.2 g / L of polylactic acid block copolymer, 30 g / L of inorganic base (potassium hydroxide), 6 g / L of organic base (triethanolamine), 5 g / L of organic carboxylic acid (succinic acid), 20 g / L of copper ions (copper sulfate), 0.75 g / L of corrosion inhibitor, and the balance is deionized water; the polylactic acid block copolymer is a polylactic acid-polyethylene glycol-maleimide copolymer (PLA-PEG-MAL); the corrosion inhibitor is composed of 5-amino-2-mercaptobenzimidazole with a mass concentration of 0.25 g / L and 4-carboxybenzotriazole with a mass concentration of 0.5 g / L.

[0044] Example 6

[0045] An alkaline micro-etching solution is composed of the following components in mass concentration:

[0046] 0.1 g / L of polylactic acid block copolymer, 50 g / L of inorganic base (sodium hydroxide), 5 g / L of organic base (hydroxyethyl ethylenediamine), 7 g / L of organic carboxylic acid (malic acid), 25 g / L of copper ions (copper acetate), 0.9 g / L of corrosion inhibitor, and the balance is deionized water; the polylactic acid block copolymer is a polyethyleneimine-polyethylene glycol-polylactic acid copolymer (PEI-PEG-PLA); the corrosion inhibitor is composed of benzimidazole-5,6-dicarboxylic acid with a mass concentration of 0.1 g / L and 5-benzotriazolecarboxylic acid with a mass concentration of 0.8 g / L.

[0047] The preparation method of the alkaline micro-etching solutions of Examples 2-6 is the same as that of Example 1, and the micro-etching method of Examples 2-6 is the same as that of Example 1.

[0048] Performance test:

[0049] I. Copper micro-etching amount, and the calculation formula is as follows:

[0050] ;

[0051] Where: X is the etching amount of the sample (μm); W0 is the weight of the sample before etching (g); W1 is the weight of the sample after etching (g); A is the length of the sample (cm); B is the width of the sample (cm).

[0052] II. Roughness Ra, Rz analysis: Measured using a HORIBA laser particle size analyzer (model LA-960V2).

[0053] The performance test was carried out on the copper surface treated by the micro-etching method using the alkaline micro-etching solutions of Examples 1-6, and the test results are shown in Table 1:

[0054] Table 1 Performance test results of the alkaline micro-etching solutions of Examples 1-6

[0055]

[0056] Among them, Figure 1 is a scanning electron microscope photograph of the copper surface after being treated by the micro-etching method using the alkaline micro-etching solution of Example 1 of the present invention.

[0057] From Figure 1 and the test results in Table 1, it can be seen that the alkaline micro-etching solution of the embodiments of the present invention regulates the dissolution rates of different copper crystal planes through the synergistic effects of corrosion inhibitors, organic carboxylic acids, organic bases, and polylactic acid block copolymers, optimizes the dissolution-etching process of copper in the microscopic region, reduces problems such as pinholes and pitting, effectively improves the etching uniformity of the circuit copper surface, and increases the quality yield of the circuit board.

[0058] I. Influence based on polylactic acid block copolymer

[0059] The difference between Comparative Example 1 and Example 1 is that there is no polylactic acid block copolymer in the alkaline micro-etching solution, and the other conditions are the same. The difference between Comparative Example 2 and Example 1 is that the mass concentration of the polylactic acid block copolymer in the alkaline micro-etching solution is 5 g / L, and the other conditions are the same. Performance tests were carried out on the copper surfaces treated by the micro-etching method using the alkaline micro-etching solutions of Example 1 and Comparative Examples 1-2, and the test results are shown in Table 2:

[0060] Table 2 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Examples 1-2

[0061]

[0062] From the test results in Table 2, it can be seen that if there is no polylactic acid block copolymer in the alkaline micro-etching solution (Comparative Example 1) or the alkaline micro-etching solution prepared with the mass concentration of the polylactic acid block copolymer not within the range defined in the present invention (Comparative Example 2), the performance test results are poor. Therefore, the mass concentration of the polylactic acid block copolymer is preferably 0.01-2 g / L.

[0063] II. Influence based on inorganic base

[0064] The difference between Comparative Example 3 and Example 1 is that there is no inorganic base in the alkaline micro-etching solution, and the other conditions are the same. Performance tests were carried out on the copper surfaces treated by the micro-etching method using the alkaline micro-etching solutions of Example 1 and Comparative Example 3, and the test results are shown in Table 3:

[0065] Table 3 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Example 3

[0066]

[0067] From the test results in Table 3, it can be seen that if there is no inorganic base in the alkaline micro-etching solution (Comparative Example 3), the performance test results are poor.

[0068] III. Influence of Organic Bases

[0069] The difference between Comparative Example 4 and Example 1 is that the alkaline etching solution does not contain organic bases, and the other conditions are the same. Performance tests were conducted on the copper surfaces treated by the etching method using the alkaline etching solutions of Example 1 and Comparative Example 4, and the test results are shown in Table 4:

[0070] Table 4 Performance Test Results of the Alkaline Etching Solutions of Example 1 and Comparative Example 4

[0071]

[0072] It can be seen from the test results in Table 4 that if the alkaline etching solution does not contain organic bases (Comparative Example 4), the performance test results are poor.

[0073] IV. Influence of Organic Carboxylic Acids

[0074] The difference between Comparative Example 5 and Example 1 is that the alkaline etching solution does not contain organic carboxylic acids, and the other conditions are the same. Performance tests were conducted on the copper surfaces treated by the etching method using the alkaline etching solutions of Example 1 and Comparative Example 5, and the test results are shown in Table 5:

[0075] Table 5 Performance Test Results of the Alkaline Etching Solutions of Example 1 and Comparative Example 5

[0076]

[0077] It can be seen from the test results in Table 5 that if the alkaline etching solution does not contain organic carboxylic acids (Comparative Example 5), the performance test results are poor.

[0078] V. Influence of Corrosion Inhibitors

[0079] The difference between Comparative Example 6 and Example 1 is that there is no corrosion inhibitor in the alkaline etching solution, and the other conditions are the same. The difference between Comparative Example 7 and Example 1 is that the mass concentration of the corrosion inhibitor in the alkaline etching solution is 0.05 g / L (composed of 2-amino-5-nitro-1H-benzimidazole with a mass concentration of 0.025 g / L and 5-aminobenzotriazole with a mass concentration of 0.025 g / L), and the other conditions are the same. The difference between Comparative Example 8 and Example 1 is that the mass concentration of the corrosion inhibitor in the alkaline etching solution is 6 g / L (composed of 2-amino-5-nitro-1H-benzimidazole with a mass concentration of 3 g / L and 5-aminobenzotriazole with a mass concentration of 3 g / L), and the other conditions are the same.

[0080] Performance tests were conducted on the copper surfaces treated by the etching method using the alkaline etching solutions of Example 1 and Comparative Examples 6 - 8, and the test results are shown in Table 6:

[0081] Table 6 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Examples 6-8

[0082]

[0083] As can be seen from the test results in Table 6, if the alkaline micro-etching solution does not contain a corrosion inhibitor (Comparative Example 6) or the alkaline micro-etching solution prepared with the mass concentration of the corrosion inhibitor not within the scope defined in the present invention (Comparative Examples 7 and 8), the performance test results are poor. Therefore, the mass concentration of the corrosion inhibitor is preferably 0.1 - 5 g / L.

[0084] VI. Influence based on the mass ratio of components in the corrosion inhibitor

[0085] The difference between Comparative Example 9 and Example 1 lies in that the mass concentration of the corrosion inhibitor in the alkaline micro-etching solution is 0.6 g / L (composed of 2-amino-5-nitro-1H-benzimidazole with a mass concentration of 0.05 g / L and 5-aminobenzotriazole with a mass concentration of 0.55 g / L), that is, the mass ratio of 2-amino-5-nitro-1H-benzimidazole to 5-aminobenzotriazole is 1:11, and the other conditions are the same. The difference between Comparative Example 10 and Example 1 lies in that the mass concentration of the corrosion inhibitor in the alkaline micro-etching solution is 0.6 g / L (composed of 2-amino-5-nitro-1H-benzimidazole with a mass concentration of 0.4 g / L and 5-aminobenzotriazole with a mass concentration of 0.2 g / L), that is, the mass ratio of 2-amino-5-nitro-1H-benzimidazole to 5-aminobenzotriazole is 1:0.5, and the other conditions are the same.

[0086] The copper surfaces treated by the micro-etching method using the alkaline micro-etching solutions of Example 1 and Comparative Examples 9-10 were subjected to performance tests, and the test results are shown in Table 7:

[0087] Table 7 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Examples 9-10

[0088]

[0089] As can be seen from the test results in Table 7, if the alkaline micro-etching solution uses a corrosion inhibitor with the mass ratio of benzimidazole derivative and benzotriazole derivative not within the scope defined in the present invention (Comparative Examples 9 and 10), the performance test results are poor. Therefore, the mass ratio of benzimidazole derivative and benzotriazole derivative is preferably 1:(1 - 10).

[0090] VII. Synergistic influence based on the corrosion inhibitor, organic carboxylic acid, organic base, and polylactic acid block copolymer

[0091] The difference between Comparative Example 11 and Example 1 is that there is no organic carboxylic acid and organic base in the alkaline micro-etching solution, and the remaining conditions are the same. The difference between Comparative Example 12 and Example 1 is that there is no corrosion inhibitor and polylactic acid block copolymer in the alkaline micro-etching solution, and the remaining conditions are the same. The difference between Comparative Example 13 and Example 1 is that there is no corrosion inhibitor and organic base in the alkaline micro-etching solution, and the remaining conditions are the same. The difference between Comparative Example 14 and Example 1 is that there is no corrosion inhibitor, organic base and polylactic acid block copolymer in the alkaline micro-etching solution, and the remaining conditions are the same. Performance tests were carried out on the copper surfaces treated by the micro-etching method using the alkaline micro-etching solutions of Example 1 and Comparative Examples 11-14, and the test results are shown in Table 8:

[0092] Table 8 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Examples 11-14

[0093]

[0094] It can be seen from the test results in Table 8 that if the alkaline micro-etching solution prepared by lacking multiple components (Comparative Examples 11-14), the performance test results show that the roughness of the micro-etched copper sheets is relatively low. Thus, it can be seen that the present invention regulates the dissolution rate of different copper crystal planes, optimizes the dissolution-etching process of copper in the microscopic region, improves the etching uniformity of the circuit copper surface, and increases the quality yield of the circuit board through the synergistic effect of the corrosion inhibitor, organic base, organic carboxylic acid, and polylactic acid block copolymer.

[0095] As described above, the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An alkaline micro-etching solution, characterized in that, It consists of the following components by mass concentration: Polylactic acid block copolymer: 0.01 - 2 g / L, inorganic base: 20 - 100 g / L, organic base: 1 - 10 g / L, organic carboxylic acid: 1 - 10 g / L, copper ions: 5 - 30 g / L, corrosion inhibitor: 0.1 - 5 g / L, and the balance is deionized water; the polylactic acid block copolymer is a block copolymer containing polylactic acid structural units; The block copolymer containing polylactic acid structural units is selected from one or more of polylactic acid - polyethylene glycol - polylactic acid copolymer, polylactic acid - polyethylene glycol - polylysine copolymer, polylactic acid - polycaprolactone - polyethylene glycol - polycaprolactone - polylactic acid copolymer, polyethyleneimine - polyethylene glycol - polylactic acid copolymer, and polylactic acid - polyethylene glycol - maleimide copolymer; The inorganic base is selected from one or more of ammonia water, sodium hydroxide, potassium hydroxide, and calcium hydroxide; the organic base is selected from one or more of dopamine, diethylenetriamine, tetraethylenepentamine, hexamethylenetetramine, triethanolamine, and hydroxyethyl ethylenediamine; The organic carboxylic acid is selected from one or more of citric acid, malic acid, succinic acid, and benzoic acid; the copper ions are selected from at least one of copper sulfate, copper nitrate, and copper acetate; The corrosion inhibitor is a mixture of benzimidazole derivatives and benzotriazole derivatives, and the mass ratio of benzimidazole derivatives to benzotriazole derivatives is 1:(1 - 10); The benzimidazole derivatives are selected from at least one of 2 - amino - 5 - nitro - 1h - benzimidazole, 5 - amino - 2 - mercaptobenzimidazole, benzimidazole - 5,6 - dicarboxylic acid, and 5 - ethoxy - 2 - mercaptobenzimidazole; The benzotriazole derivatives are selected from at least one of 2 - (1 - benzotriazole) acetic acid, 1 - aminobenzotriazole, 4 - hydroxybenzotriazole, 5 - aminobenzotriazole, 5 - benzotriazole formic acid, and 4 - carboxybenzotriazole; 2. The alkaline micro-etching solution according to claim 1, characterized in that, The average molecular weight of the polylactic acid block copolymer is 500 - 10000.

3. The preparation method of the alkaline micro-etching solution according to any one of claims 1-2, characterized in that, It includes the following steps: After weighing the inorganic base, organic base, organic carboxylic acid, copper ions, corrosion inhibitor, and polylactic acid block copolymer, dissolve them in deionized water, mix, stir, and make up the volume to obtain the alkaline micro - etching solution.

4. A micro-etching method, characterized in that, It includes the following steps: etching the circuit board with the alkaline micro-etching solution described in any one of claims 1-2, the etching method is horizontal line spraying, and the spraying pressure is 0.8-2 kg / cm 2 , the temperature is 25-40 °C, and the etching time is 30-120 s.

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