Alkaline micro-etching solution and preparation method and micro-etching method thereof

Abstract

The invention discloses an alkaline micro-etching solution as well as a preparation method and a micro-etching method thereof, and relates to the technical field of printed circuit board production. The alkaline micro-etching solution consists of the following components in mass concentration: 0.01-2g / L of polylactic acid segmented copolymer, 20-100g / L of inorganic alkali, 1-10g / L of organic alkali, 1-10g / L of organic carboxylic acid, 5-30g / L of copper ions, 0.1-5g / L of corrosion inhibitor and the balance of deionized water, the polylactic acid block copolymer is a block copolymer containing a polylactic acid structural unit. According to the alkaline micro-etching solution, through the synergistic effect of the corrosion inhibitor, the organic carboxylic acid, the organic base and the polylactic acid block copolymer, the dissolution speed of different copper crystal faces is regulated and controlled, the dissolution-etching process of copper in a microscopic area is optimized, the problems of pinholes, pits and the like are reduced, the etching uniformity of the circuit copper face is effectively improved, and the quality yield of a circuit board is improved.

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 more and more stringent. In the major links of the PCB production and manufacturing process, 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, it will lead to insufficient bonding force of the copper plating layer, 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 or even holes in the hole wall.

[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 to play a role in cleaning and roughening the copper surface. Currently, the commonly used micro-etching systems are formic acid - copper chloride, sulfuric acid - sodium persulfate, and sulfuric acid - hydrogen peroxide. 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, thus 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 relatively mild effect on materials, causes less damage to materials, and the etching solution can be recycled to reduce 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 mount 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. The 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 solution.

[0005] To achieve the above object, the present invention provides the following technical solutions: In the first aspect, an alkaline micro-etching solution is provided, which is composed of the following mass concentration components: 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, with the balance being deionized water; the polylactic acid block copolymer is a block copolymer containing polylactic acid structural units.

[0006] Furthermore, the block copolymer containing polylactic acid structural units is selected from one or more of poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) copolymer (PLA-PEG-PLA), poly(lactic acid)-poly(ethylene glycol)-poly(L-lysine) copolymer (PLA-PEG-PLL), poly(lactic acid)-poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone)-poly(lactic acid) copolymer (PLA-PCL-PEG-PCL-PLA), polyethyleneimine-poly(ethylene glycol)-poly(lactic acid) copolymer (PEI-PEG-PLA), poly(lactic acid)-poly(ethylene glycol)-maleimide copolymer (PLA-PEG-MAL).

[0007] Furthermore, the average molecular weight of the polylactic acid block copolymer is 500 - 10,000.

[0008] Furthermore, the inorganic base is selected from one or more of ammonia water, sodium hydroxide, potassium hydroxide, calcium hydroxide; the organic base is selected from one or more of dopamine, diethylenetriamine, tetraethylenepentamine, hexamethylenetetramine, triethanolamine, hydroxyethyl ethylenediamine.

[0009] Furthermore, the organic carboxylic acid is selected from one or more of citric acid, malic acid, succinic acid, benzoic acid; the copper ions are selected from at least one of copper sulfate, copper nitrate, copper acetate.

[0010] Furthermore, 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).

[0011] Furthermore, 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, 5-ethoxy-2-mercaptobenzimidazole.

[0012] Furthermore, the benzotriazole derivatives are selected from at least one of 2-(1H-benzotriazol-2-yl)acetic acid, 1-aminobenzotriazole, 4-hydroxybenzotriazole, 5-aminobenzotriazole, 5-benzotriazolecarboxylic acid, 4-carboxybenzotriazole.

[0013] In a second aspect, there is provided a method for preparing the alkaline micro-etching solution as described in the first aspect, comprising the following steps: weighing an inorganic base, an organic base, an organic carboxylic acid, copper ions, a corrosion inhibitor and a poly(lactic acid) block copolymer, dissolving them in deionized water, mixing, stirring, and making up the volume to obtain the alkaline micro-etching solution.

[0014] In a third aspect, there is provided a micro-etching method, comprising the following steps: etching a circuit board using the alkaline micro-etching solution described in the first aspect, the etching method being horizontal line spraying, the spraying pressure being 0.8 - 2 kg / cm 2 , the temperature being 25 - 40 °C, and the etching time being 30 - 120 s.

[0015] The beneficial effects of the present invention are as follows: (1) The alkaline micro-etching solution of the present invention uses a poly(lactic 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; (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 poly(lactic acid) block copolymer, which can form π bonds or covalent bonds with copper atoms, regulate the dissolution rates 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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.

[0017] 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 DESCRIPTION OF THE EMBODIMENTS

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0019] It should be understood that when used in this specification and the appended claims, the terms "comprises" and "comprising" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0020] It should also be understood that the terms used in the specification of the present invention are merely for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0021] It should be further understood that the term "and / or" used in the 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.

[0022] 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.

[0023] Example 1 An alkaline micro-etching solution is composed of the following components in mass concentration: 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 ion (copper sulfate) 10 g / L, corrosion inhibitor 0.6 g / L, and the balance is deionized water; the polylactic acid block copolymer is 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.

[0024] 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 ion, 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.

[0025] 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.

[0026] Example 2 An alkaline micro-etching solution is composed of the following components in mass concentration: Polylactic acid block copolymer 0.1 g / L, inorganic base (potassium hydroxide) 25 g / L, organic base (tetraethylenepentamine) 5 g / L, organic carboxylic acid (succinic acid) 4 g / L, copper ions (copper sulfate) 8 g / L, corrosion inhibitor 0.7 g / L, with the balance being deionized water; the polylactic acid block copolymer is a 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.

[0027] Example 3 An alkaline micro - etching solution is composed of the following components by mass concentration: Polylactic acid block copolymer 0.08 g / L, inorganic base 35 (sodium hydroxide) g / L, organic base (dopamine) 8 g / L, organic carboxylic acid (benzoic acid) 6 g / L, copper ions (copper acetate) 5 g / L, corrosion inhibitor 0.8 g / L, with the balance being deionized water; the polylactic acid block copolymer is a polylactic acid - polycaprolactone - polyethylene glycol - polycaprolactone - polylactic 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.

[0028] Example 4 An alkaline micro - etching solution is composed of the following components by mass concentration: Polylactic acid block copolymer 0.1 g / L, inorganic base (ammonia water) 40 g / L, organic base (diethylenetriamine) 4 g / L, organic carboxylic acid (citric acid) 8 g / L, copper ions (copper nitrate) 15 g / L, corrosion inhibitor 0.9 g / L, with the balance being deionized water; the polylactic acid block copolymer is a polyethyleneimine - polyethylene glycol - polylactic 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.

[0029] Example 5 An alkaline micro - etching solution is composed of the following components by mass concentration: Polylactic acid block copolymer: 0.2 g / L, inorganic base (potassium hydroxide): 30 g / L, organic base (triethanolamine): 6 g / L, organic carboxylic acid (succinic acid): 5 g / L, copper ions (copper sulfate): 20 g / L, corrosion inhibitor: 0.75 g / L, the balance being deionized water; the polylactic acid block copolymer is a polylactic acid - polyethylene glycol - maleimide copolymer (PLA - PEG - MAL); the corrosion inhibitor consists 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.

[0030] Example 6 An alkaline micro - etching solution, which consists of the following components by mass concentration: Polylactic acid block copolymer: 0.1 g / L, inorganic base (sodium hydroxide): 50 g / L, organic base (hydroxyethyl ethylenediamine): 5 g / L, organic carboxylic acid (malic acid): 7 g / L, copper ions (copper acetate): 25 g / L, corrosion inhibitor: 0.9 g / L, the balance being deionized water; the polylactic acid block copolymer is a polyethyleneimine - polyethylene glycol - polylactic acid copolymer (PEI - PEG - PLA); the corrosion inhibitor consists 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.

[0031] 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.

[0032] Performance test: I. Copper micro - etching amount, the calculation formula is as follows: ; 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).

[0033] II. Roughness Ra, Rz analysis: Measured using a HORIBA laser particle size analyzer (model LA - 960V2).

[0034] Perform performance tests on the copper surfaces 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: Table 1 Performance test results of the alkaline micro - etching solutions of Examples 1 - 6

[0035] Among them, Figure 1 is a scanning electron microscope photograph of the copper surface treated by the micro - etching method using the alkaline micro - etching solution of Example 1 of the present invention.

[0036] From Figure 1 and the test results in Table 1, it can be seen that the alkaline micro-etching solution of the embodiment of the present invention regulates the dissolution rates of different copper crystal planes through the synergistic effects of the corrosion inhibitor, organic carboxylic acid, organic base, and 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 circuit copper surface, and increases the quality yield of the circuit board.

[0037] I. Influence based on polylactic acid block copolymer 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: Table 2 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Examples 1-2

[0038] 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 scope 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.

[0039] II. Influence based on inorganic base 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: Table 3 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Example 3

[0040] 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.

[0041] III. Influence based on organic base The difference between Comparative Example 4 and Example 1 is that there is no organic 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 4, and the test results are shown in Table 4: Table 4 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Example 4

[0042] As can be seen from the test results in Table 4, if the alkaline micro-etching solution does not contain organic base (Comparative Example 4), the performance test results are poor.

[0043] IV. Influence based on organic carboxylic acid The difference between Comparative Example 5 and Example 1 is that the alkaline micro-etching solution does not contain organic carboxylic acid, and the other conditions are the same. The performance of the copper surface treated by the micro-etching method using the alkaline micro-etching solutions of Example 1 and Comparative Example 5 was tested, and the test results are shown in Table 5: Table 5 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Example 5

[0044] As can be seen from the test results in Table 5, if the alkaline micro-etching solution does not contain organic carboxylic acid (Comparative Example 5), the performance test results are poor.

[0045] V. Influence based on corrosion inhibitor The difference between Comparative Example 6 and Example 1 is that the alkaline micro-etching solution does not contain a corrosion inhibitor, 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 micro-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 micro-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.

[0046] The performance of the copper surface treated by the micro-etching method using the alkaline micro-etching solutions of Example 1 and Comparative Examples 6 - 8 was tested, and the test results are shown in Table 6: Table 6 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Examples 6 - 8

[0047] 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 outside the range 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.

[0048] VI. Influence based on the mass ratio of components in the corrosion inhibitor 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 remaining 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 remaining conditions are the same.

[0049] The performance of the copper surface treated by the micro-etching method using the alkaline micro-etching solutions of Example 1 and Comparative Examples 9-10 was tested, and the test results are shown in Table 7: Table 7 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Examples 9-10

[0050] It can be seen from the test results in Table 7 that if the corrosion inhibitor with a mass ratio of benzimidazole derivative to benzotriazole derivative outside the range defined in the present invention is used in the alkaline micro-etching solution (Comparative Example 9, Comparative Example 10), the performance test results are poor. Therefore, the mass ratio of the benzimidazole derivative to the benzotriazole derivative is preferably 1:(1-10).

[0051] VII. Synergistic effects based on corrosion inhibitors, organic carboxylic acids, organic bases, and polylactic acid block copolymers The difference between Comparative Example 11 and Example 1 lies in 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 lies in 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 lies in 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 lies in 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. The performance of the copper surface treated by the micro-etching method using the alkaline micro-etching solutions of Example 1 and Comparative Examples 11-14 was tested, and the test results are shown in Table 8: Table 8 Performance test results of the alkaline micro-etching solutions of Example 1 and Comparative Examples 11-14

[0052] As can be seen from the test results in Table 8, for the alkaline micro-etching solutions prepared without multiple components (Comparative Examples 11 - 14), the test results of their performance show that the roughness of the copper sheets after micro-etching is relatively low. Thus, it can be seen that the present invention regulates the dissolution rate of different copper crystal planes through the synergistic effect of corrosion inhibitors, organic bases, organic carboxylic acids, and polylactic acid block copolymers, 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.

[0053] As described above, the above are only specific embodiments 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 microetching solution, characterized in that: It is composed of the following components by mass concentration: 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 ion, 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.

2. The alkaline microetching solution according to claim 1, characterized in that: 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.

3. The alkaline microetching solution according to claim 1, characterized in that: The average molecular weight of the polylactic acid block copolymer is 500-10000.

4. The alkaline microetching solution according to claim 1, characterized in that: 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 hydroxyethylethylenediamine.

5. The alkaline microetching solution according to claim 1, characterized in that: The organic carboxylic acid is selected from one or more of citric acid, malic acid, succinic acid and benzoic acid; the copper ion is selected from at least one of copper sulfate, copper nitrate and copper acetate.

6. The alkaline microetching solution according to claim 1, characterized in that: The corrosion inhibitor is a mixture of benzimidazole derivatives and benzotriazole derivatives, and the mass ratio of the benzimidazole derivatives to the benzotriazole derivatives is 1:(1-10).

7. The alkaline microetching solution according to claim 6, characterized in that: The benzimidazole derivative is 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.

8. The alkaline microetching solution according to claim 6, characterized in that: The benzotriazole derivative is at least one selected from 2-(1-benzotriazole)acetic acid, 1-aminobenzotriazole, 4-hydroxybenzotriazole, 5-aminobenzotriazole, 5-benzotriazolecarboxylic acid, and 4-carboxybenzotriazole.

9. The method for preparing the alkaline microetching solution according to any one of claims 1 to 8, characterized in that: The following steps are involved: The inorganic base, organic base, organic carboxylic acid, copper ion, corrosion inhibitor and polylactic acid block copolymer are weighed, dissolved in deionized water, mixed, stirred and fixed to obtain the alkaline micro-etching solution.

10. A micro-etching method, characterized in that: The method comprises the following steps: etching the circuit board using the alkaline micro-etching solution according to any one of claims 1 to 8, wherein the etching method is horizontal line spraying, and the spraying pressure is 0.8-2kg / cm 2 , temperature is 25-40℃, and etching time is 30-120s.

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