A method for selective etching of thin tin on a circuit board with anti-etch protection

Abstract

The present application relates to the technical field of circuit board production, in particular to a circuit board thin tin selective etching method with etch resist protection; after cleaning and drying the circuit board to be etched, the circuit board is subjected to micro-etching treatment with a micro-etching solution, then a thin tin layer is formed on the surface of the circuit board through electroplating process, then the etch resist is evenly coated on the thin tin layer, the copper-clad circuit board coated with the etch resist is subjected to exposure, the exposed thin tin layer is subjected to selective etching with an etching solution, after the etching is completed, the circuit board is subjected to film removal with sodium hydroxide solution, then the circuit board is washed with deionized water and dried, and the selective etching of the circuit board thin tin is completed. The circuit board thin tin selective etching method with etch resist protection provided by the present application can not only ensure that the copper surface and the solidified etch resist have strong bonding force, thereby reducing the loss amount of copper, but also shorten the film removal time and enable selective etching of the etching area.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, specifically to a method for selective etching of thin tin on circuit boards with corrosion protection. Background Technology

[0002] Tin etching is a crucial process step in circuit board manufacturing. This is especially true for etching thin tin layers, which presents numerous challenges. Firstly, the extremely thin tin layer, typically only a few micrometers or even thinner, significantly increases the difficulty of controlling the etching process. Traditional etching methods struggle to precisely control the depth and extent of etching when dealing with thin tin layers, easily leading to over-etching or incomplete etching. Over-etching results in narrower circuit widths, affecting circuit performance and potentially causing open circuits; while incomplete etching leaves excess tin residue, impacting the electrical performance and appearance of the circuit board.

[0003] Circuit boards often contain various metal layers and circuit structures, requiring selective etching—that is, etching away only the target thin tin layer without damaging other metal layers and circuits. However, existing etching techniques have limitations in terms of selectivity. Etching the thin tin layer can easily corrode adjacent areas, thus reducing the yield and reliability of the circuit board.

[0004] Based on this, the present invention provides a method for selective etching of thin tin on circuit boards with corrosion resistance to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for selective etching of thin tin on circuit boards with anti-corrosion protection, which not only ensures a strong bond between the copper surface and the cured resist, reducing the loss of copper, but also has a short demolding time and can selectively etch the etched area.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for selective etching of thin tin on a circuit board with corrosion resistance, comprising the following steps:

[0008] After cleaning and drying, the circuit board to be etched is placed in a micro-etching tank containing micro-etching solution and micro-etched at 30-34°C. After the micro-etching is completed, it is washed with water for 2-4 minutes and then dried to obtain the micro-etched circuit board.

[0009] The micro-etched circuit board is used as the cathode and placed in a tin plating solution. A thin tin layer is formed on the surface of the circuit board through the electroplating process. After washing with water for 3 to 5 minutes and drying, a circuit board containing a thin tin layer is obtained.

[0010] The resist is evenly coated onto a thin tin layer, and then dried at 80–100°C for 10–15 minutes.

[0011] Expose the copper-clad laminate circuit board coated with resist;

[0012] The circuit board is placed in an etching apparatus, and the exposed thin tin layer is selectively etched using an etching solution.

[0013] After etching, the circuit board is stripped with sodium hydroxide solution, then washed with deionized water and dried to complete the selective etching of the thin tin on the circuit board.

[0014] The present invention is further configured such that the micro-etching solution is composed of the following raw materials in parts by weight: 10-12 parts of hydrogen peroxide aqueous solution, 10-20 parts of sulfuric acid aqueous solution, 0.1-0.3 parts of hydrogen chloride aqueous solution, 1-5 parts of compound stabilizer and 30-40 parts of deionized water;

[0015] The hydrogen peroxide aqueous solution has a mass fraction of 0.3-0.6%.

[0016] The sulfuric acid aqueous solution has a mass fraction of 0.5% to 2%;

[0017] The mass fraction of the hydrogen chloride aqueous solution is 0.005–0.01%;

[0018] The preparation process of the micro-etching solution is as follows:

[0019] Accurately weigh out the aqueous solutions of hydrogen peroxide, sulfuric acid, and hydrogen chloride, the compound stabilizer, and deionized water, and set aside for later use;

[0020] Under conditions of 200–300 r / min, sulfuric acid aqueous solution, hydrogen chloride aqueous solution, hydrogen peroxide aqueous solution and compound stabilizer were sequentially placed in deionized water and mixed to prepare a micro-etching solution.

[0021] A further embodiment of the present invention is that the compound stabilizer is composed of diethylenetriaminepentaacetic acid, trisodium citrate and auxiliary materials mixed in a mass ratio of 4.2-4.5:3.2-3.5:1.

[0022] A further feature of this invention is that the auxiliary material is selected from either triethanolamine or triisopropanolamine.

[0023] A further feature of this invention is that the current density during electroplating is 1–3 A / dm². 2 The electroplating time is 5 to 10 minutes, and the electroplating temperature is 20 to 30°C.

[0024] The present invention is further configured such that the resist is composed of the following raw materials in parts by weight: 20-30 parts copolymer base material, 4-8 parts N,N-dimethylethanolamine, 2-4 parts p-nitrobenzene diazonium tetrafluoroborate, 2-4 parts 1-hydroxycyclohexylphenyl ketone and 40-50 parts water;

[0025] The preparation process of the resist is as follows:

[0026] Accurately weigh the copolymer base material, N,N-dimethylethanolamine, p-nitrobenzenediazotetrafluoroborate, 1-hydroxycyclohexylphenyl ketone and water, and set aside.

[0027] The copolymer base material and water are placed in a mixing device and treated at 200-300 r / min for 10-15 min. Then, N,N-dimethylethanolamine, p-nitrobenzene diazonium tetrafluoroborate and 1-hydroxycyclohexylphenyl ketone are added and the mixture is stirred for another 20-30 min to prepare the corrosion resist.

[0028] A further provision of the present invention is that the preparation process of the copolymer base material is as follows:

[0029] The acetoxyphenylbromoethylene, allyl methacrylate, and N,N-dimethylformamide were mixed in a mass ratio of 0.12–0.18:0.22–0.32:1 to obtain a mixture.

[0030] Under a nitrogen atmosphere, 3.5–4% of the mass of the mixture of nitrogen diisobutyronitrile was added to the mixture, the temperature was raised to 65–70°C and kept at that temperature for 22–24 hours. After cooling to room temperature, 100–200% of the mass of the mixture of deionized water was added to the mixture, the mixture was allowed to stand for 8–10 minutes, filtered, and washed 2–4 times with deionized water. After drying, the copolymer base material was obtained.

[0031] A further feature of this invention is that the mass fraction of the sodium hydroxide solution is 1-4%.

[0032] A further feature of the present invention is that the temperature for demolding is 50–60°C.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] This invention involves cleaning and drying the circuit board to be etched, then micro-etching it with a micro-etching solution, followed by electroplating to form a thin tin layer on the circuit board surface. A resist is then uniformly coated onto the tin layer, and the copper-clad laminate circuit board with the resist coating is exposed. An etching solution is used to selectively etch the exposed tin layer. After etching, the circuit board is stripped using a sodium hydroxide solution, washed with deionized water, and dried, completing the selective etching of the thin tin layer on the circuit board. This invention provides a method for selectively etching thin tin layers on circuit boards with corrosion protection. This method not only ensures strong adhesion between the copper surface and the cured resist, reducing copper loss, but also has a short stripping time and allows for selective etching of the etched areas. Therefore, this method for selectively etching thin tin layers on circuit boards with corrosion protection has a broader market prospect and is more suitable for widespread application. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] A method for selective etching of thin tin on a circuit board with corrosion resistance includes the following steps:

[0038] S1. After cleaning and drying the circuit board to be etched, place it in a micro-etching tank containing micro-etching solution and micro-etch at 30°C. After the micro-etching is completed, wash with water for 2 minutes and dry to obtain the micro-etched circuit board.

[0039] The micro-etching solution is composed of the following raw materials in parts by weight: 10 parts hydrogen peroxide aqueous solution, 10 parts sulfuric acid aqueous solution, 0.1 parts hydrogen chloride aqueous solution, 1 part compound stabilizer and 30 parts deionized water;

[0040] The mass fraction of the hydrogen peroxide aqueous solution is 0.3%.

[0041] The mass fraction of the sulfuric acid aqueous solution is 0.5%;

[0042] The mass fraction of the hydrogen chloride aqueous solution is 0.005%;

[0043] The preparation process of the micro-etching solution is as follows:

[0044] Accurately weigh out the aqueous solutions of hydrogen peroxide, sulfuric acid, and hydrogen chloride, the compound stabilizer, and deionized water, and set aside for later use;

[0045] At a speed of 200 r / min, sulfuric acid aqueous solution, hydrogen chloride aqueous solution, hydrogen peroxide aqueous solution and compound stabilizer were sequentially mixed in deionized water to prepare a micro-etching solution.

[0046] Furthermore, the compound stabilizer is composed of diethylenetriaminepentaacetic acid, trisodium citrate, and auxiliary materials mixed in a mass ratio of 4.2:3.2:1.

[0047] Furthermore, triethanolamine is selected as the auxiliary material.

[0048] S2. The micro-etched circuit board is used as the cathode and placed in a tin plating solution. A thin tin layer is formed on the surface of the circuit board through the electroplating process. After washing with water for 3 minutes and drying, a circuit board containing a thin tin layer is obtained.

[0049] The current density for electroplating is 1 A / dm³. 2 The electroplating time is 5 minutes and the electroplating temperature is 20℃.

[0050] S3. Apply the resist evenly to the thin tin layer, and then dry it at 80°C for 10 minutes.

[0051] The corrosion inhibitor is composed of the following raw materials in parts by weight: 20 parts copolymer base material, 4 parts N,N-dimethylethanolamine, 2 parts p-nitrobenzene diazonium tetrafluoroborate, 2 parts 1-hydroxycyclohexylphenyl ketone and 40 parts water.

[0052] The preparation process of the photoresist is as follows:

[0053] Accurately weigh the copolymer base material, N,N-dimethylethanolamine, p-nitrobenzenediazotetrafluoroborate, 1-hydroxycyclohexylphenyl ketone and water, and set aside.

[0054] The copolymer base material and water were placed in a mixing device and treated at 200 r / min for 10 min. Then, N,N-dimethylethanolamine, p-nitrobenzene diazonium tetrafluoroborate and 1-hydroxycyclohexylphenyl ketone were added and the mixture was stirred for another 20 min to prepare the corrosion resist.

[0055] Furthermore, the preparation process of the copolymer base material is as follows:

[0056] The acetoxyphenyl bromide, allyl methacrylate, and N,N-dimethylformamide were mixed in a mass ratio of 0.12:0.22:1 to obtain a mixture.

[0057] Under a nitrogen atmosphere, 3.5% of the mass of the mixture of nitrogen diisobutyronitrile was added to it, the temperature was raised to 65°C and kept at that temperature for 22 hours. After cooling to room temperature, 100% of the mass of the mixture of deionized water was added to it, the mixture was allowed to stand for 8 minutes, filtered, washed twice with deionized water, and dried to obtain the copolymer base material.

[0058] S4. Expose the copper-clad laminate circuit board coated with resist.

[0059] S5. Place the circuit board into the etching equipment and use the etching solution to selectively etch the exposed thin tin layer.

[0060] S6. After etching, the circuit board is stripped with sodium hydroxide solution, then washed and dried with deionized water to complete the selective etching of the thin tin on the circuit board.

[0061] The sodium hydroxide solution has a mass fraction of 1%.

[0062] The demolding temperature is 50℃.

[0063] Example 2

[0064] A method for selective etching of thin tin on a circuit board with corrosion resistance includes the following steps:

[0065] S1. After cleaning and drying the circuit board to be etched, place it in a micro-etching tank containing micro-etching solution and micro-etch at 32°C. After the micro-etching is completed, wash with water for 3 minutes and dry to obtain the micro-etched circuit board.

[0066] The micro-etching solution is composed of the following raw materials in parts by weight: 11 parts hydrogen peroxide aqueous solution, 15 parts sulfuric acid aqueous solution, 0.2 parts hydrogen chloride aqueous solution, 3 parts compound stabilizer and 35 parts deionized water;

[0067] The mass fraction of the hydrogen peroxide aqueous solution is 0.4%.

[0068] The mass fraction of the sulfuric acid aqueous solution is 1.2%;

[0069] The mass fraction of the hydrogen chloride aqueous solution is 0.007%;

[0070] The preparation process of the micro-etching solution is as follows:

[0071] Accurately weigh out the aqueous solutions of hydrogen peroxide, sulfuric acid, and hydrogen chloride, the compound stabilizer, and deionized water, and set aside for later use;

[0072] At a speed of 250 r / min, sulfuric acid aqueous solution, hydrogen chloride aqueous solution, hydrogen peroxide aqueous solution and compound stabilizer were sequentially mixed in deionized water to prepare a micro-etching solution.

[0073] Furthermore, the compound stabilizer is composed of diethylenetriaminepentaacetic acid, trisodium citrate, and auxiliary materials mixed in a mass ratio of 4.3:3.3:1.

[0074] Furthermore, triisopropanolamine is selected as the auxiliary material.

[0075] S2. The micro-etched circuit board is used as the cathode and placed in a tin plating solution. A thin tin layer is formed on the surface of the circuit board through the electroplating process. After washing with water for 4 minutes and drying, a circuit board containing a thin tin layer is obtained.

[0076] The current density for electroplating is 2 A / dm². 2 The electroplating time is 7 minutes and the electroplating temperature is 25℃.

[0077] S3. Apply the resist evenly to the thin tin layer, and then dry it at 90°C for 12 minutes.

[0078] The corrosion inhibitor is composed of the following raw materials in parts by weight: 25 parts copolymer base material, 6 parts N,N-dimethylethanolamine, 3 parts p-nitrobenzene diazonium tetrafluoroborate, 3 parts 1-hydroxycyclohexylphenyl ketone and 45 parts water.

[0079] The preparation process of the photoresist is as follows:

[0080] Accurately weigh the copolymer base material, N,N-dimethylethanolamine, p-nitrobenzenediazotetrafluoroborate, 1-hydroxycyclohexylphenyl ketone and water, and set aside.

[0081] The copolymer base material and water were placed in a mixing device and treated at 250 r / min for 12 min. Then, N,N-dimethylethanolamine, p-nitrobenzene diazonium tetrafluoroborate and 1-hydroxycyclohexylphenyl ketone were added and the mixture was stirred for another 25 min to prepare the corrosion resist.

[0082] Furthermore, the preparation process of the copolymer base material is as follows:

[0083] The acetoxyphenyl bromide, allyl methacrylate, and N,N-dimethylformamide were mixed in a mass ratio of 0.14:0.27:1 to obtain a mixture.

[0084] Under a nitrogen atmosphere, 3.7% (by mass) of N-bisisobutyronitrile was added to the mixture, the temperature was raised to 68°C and kept at that temperature for 23 hours. After cooling to room temperature, 105% (by mass) of deionized water was added to the mixture, the mixture was allowed to stand for 9 minutes, filtered, and washed three times with deionized water. After drying, the copolymer base material was obtained.

[0085] S4. Expose the copper-clad laminate circuit board coated with resist.

[0086] S5. Place the circuit board into the etching equipment and use the etching solution to selectively etch the exposed thin tin layer.

[0087] S6. After etching, the circuit board is stripped with sodium hydroxide solution, then washed and dried with deionized water to complete the selective etching of the thin tin on the circuit board.

[0088] The sodium hydroxide solution has a mass fraction of 2%.

[0089] The demolding temperature is 55℃.

[0090] Example 3

[0091] A method for selective etching of thin tin on a circuit board with corrosion resistance includes the following steps:

[0092] S1. After cleaning and drying the circuit board to be etched, place it in a micro-etching tank containing micro-etching solution and micro-etch it at 34°C. After the micro-etching is completed, wash it with water for 4 minutes and dry it to obtain the micro-etched circuit board.

[0093] The micro-etching solution is composed of the following raw materials in parts by weight: 12 parts hydrogen peroxide aqueous solution, 20 parts sulfuric acid aqueous solution, 0.3 parts hydrogen chloride aqueous solution, 5 parts compound stabilizer and 40 parts deionized water;

[0094] The mass fraction of the hydrogen peroxide aqueous solution is 0.6%.

[0095] The mass fraction of the sulfuric acid aqueous solution is 2%.

[0096] The mass fraction of the hydrogen chloride aqueous solution is 0.01%;

[0097] The preparation process of the micro-etching solution is as follows:

[0098] Accurately weigh out the aqueous solutions of hydrogen peroxide, sulfuric acid, and hydrogen chloride, the compound stabilizer, and deionized water, and set aside for later use;

[0099] At a speed of 300 r / min, sulfuric acid aqueous solution, hydrogen chloride aqueous solution, hydrogen peroxide aqueous solution and compound stabilizer were sequentially mixed in deionized water to prepare a micro-etching solution.

[0100] Furthermore, the compound stabilizer is composed of diethylenetriaminepentaacetic acid, trisodium citrate, and auxiliary materials mixed in a mass ratio of 4.5:3.5:1.

[0101] Furthermore, triethanolamine is selected as the auxiliary material.

[0102] S2. The micro-etched circuit board is used as the cathode and placed in a tin plating solution. A thin tin layer is formed on the surface of the circuit board through the electroplating process. After washing with water for 5 minutes and drying, a circuit board containing a thin tin layer is obtained.

[0103] The current density for electroplating is 3 A / dm³. 2 The electroplating time is 10 minutes and the electroplating temperature is 30℃.

[0104] S3. Apply the resist evenly to the thin tin layer, and then dry it at 100°C for 15 minutes.

[0105] The corrosion inhibitor is composed of the following raw materials in parts by weight: 30 parts copolymer base material, 8 parts N,N-dimethylethanolamine, 4 parts p-nitrobenzene diazonium tetrafluoroborate, 4 parts 1-hydroxycyclohexylphenyl ketone and 50 parts water.

[0106] The preparation process of the photoresist is as follows:

[0107] Accurately weigh the copolymer base material, N,N-dimethylethanolamine, p-nitrobenzenediazotetrafluoroborate, 1-hydroxycyclohexylphenyl ketone and water, and set aside.

[0108] The copolymer base material and water were placed in a mixing device and treated at 300 r / min for 15 min. Then, N,N-dimethylethanolamine, p-nitrobenzene diazonium tetrafluoroborate and 1-hydroxycyclohexylphenyl ketone were added and the mixture was stirred for another 30 min to prepare the corrosion resist.

[0109] Furthermore, the preparation process of the copolymer base material is as follows:

[0110] The acetoxyphenyl bromide, allyl methacrylate, and N,N-dimethylformamide were mixed in a mass ratio of 0.18:0.32:1 to obtain a mixture.

[0111] Under a nitrogen atmosphere, 4% (by mass) of N-bisisobutyronitrile was added to the mixture, the temperature was raised to 70°C and kept at that temperature for 24 hours. After cooling to room temperature, 200% (by mass) of deionized water was added to the mixture, the mixture was allowed to stand for 10 minutes, filtered, and washed four times with deionized water. After drying, the copolymer base material was obtained.

[0112] S4. Expose the copper-clad laminate circuit board coated with resist.

[0113] S5. Place the circuit board into the etching equipment and use the etching solution to selectively etch the exposed thin tin layer.

[0114] S6. After etching, the circuit board is stripped with sodium hydroxide solution, then washed and dried with deionized water to complete the selective etching of the thin tin on the circuit board.

[0115] The sodium hydroxide solution has a mass fraction of 4%.

[0116] The demolding temperature is 60℃.

[0117] Comparative Example 1: The difference from Example 1 is that the micro-etching solution used in this example does not contain a compound stabilizer.

[0118] Comparative Example 2: The difference from Example 1 is that an equal amount of allyl methacrylate is used instead of copolymer base material in this example.

[0119] Performance testing:

[0120] (1) Test method: A 49μm thick copper foil with an area of ​​7cm×7cm was used as the test sample (circuit substrate); after cleaning and drying, the circuit substrate to be etched was placed in a micro-etching tank containing micro-etching solution and micro-etched at 30℃ for 1min. After micro-etching, it was washed with water for 2min and dried to obtain the micro-etched circuit substrate. The micro-etching amount was calculated as follows: micro-etching amount = (AB)×10 4 / (C×S×2), where A is the weight of the test sample before micro-etching, B is the weight of the test sample after micro-etching, C is the density of copper, and S is the area of ​​the test sample.

[0121] (2) Test method: The peel strength between the copper foil and the cured resist was tested according to the test standard method IPC-TM-6502.4.8.

[0122] (3) Test method: Start timing from the moment the circuit board enters the 4% sodium hydroxide solution and continue until the resist on the circuit board is completely peeled off. Record this time as the stripping time.

[0123] The obtained test data are recorded in Tables 1 and 2 below:

[0124] Table 1. Test Data Recording Table for Each Group

[0125] Group Micro-etching amount (μm) Peel strength (N / mm) Example 1 group 0.12 0.95 Example 2 group 0.14 0.97 Example 3 0.11 0.96 Comparison Group 1 0.22 0.88 Comparison of 2 groups - 0.75

[0126] Table 2. Test Data Recording Table for Each Group

[0127]

[0128]

[0129] By comparing and analyzing the relevant data in Tables 1 and 2, it can be seen that the selective etching method for thin tin circuit boards with corrosion protection provided by this invention not only ensures a strong bond between the copper surface and the cured resist, reducing copper loss, but also shortens the demolding time and enables selective etching of the etched area. This indicates that the selective etching method for thin tin circuit boards with corrosion protection provided by this invention has a broader market prospect and is more suitable for widespread application.

[0130] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0131] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for selective etching of thin tin on a circuit board with corrosion resistance, characterized in that, Includes the following steps: After cleaning and drying, the circuit board to be etched is placed in a micro-etching tank containing micro-etching solution and micro-etched at 30-34°C. After micro-etching is completed, it is washed with water for 2-4 minutes and dried to obtain the micro-etched circuit board. The micro-etched circuit board is used as the cathode and placed in a tin plating solution. A thin tin layer is formed on the surface of the circuit board through the electroplating process. After washing with water for 3 to 5 minutes and drying, a circuit board containing a thin tin layer is obtained. The resist is evenly coated onto a thin tin layer, and then dried at 80–100°C for 10–15 minutes. Expose the copper-clad laminate circuit board coated with resist; The circuit board is placed in an etching apparatus, and the exposed thin tin layer is selectively etched using an etching solution. After etching, the circuit board is stripped with sodium hydroxide solution, then washed and dried with deionized water to complete the selective etching of the thin tin on the circuit board. The micro-etching solution is composed of the following raw materials in parts by weight: 10-12 parts of hydrogen peroxide aqueous solution, 10-20 parts of sulfuric acid aqueous solution, 0.1-0.3 parts of hydrogen chloride aqueous solution, 1-5 parts of compound stabilizer and 30-40 parts of deionized water; The compound stabilizer is composed of diethylenetriaminepentaacetic acid, trisodium citrate, and auxiliary materials mixed in a mass ratio of 4.2–4.5:3.2–3.5:

1. The auxiliary material is selected from either triethanolamine or triisopropanolamine. The corrosion inhibitor is composed of the following raw materials in parts by weight: 20-30 parts copolymer base material, 4-8 parts N,N-dimethylethanolamine, 2-4 parts p-nitrobenzene diazonium tetrafluoroborate, 2-4 parts 1-hydroxycyclohexylphenyl ketone and 40-50 parts water. The preparation process of the copolymer base material is as follows: The acetoxyphenyl bromide, allyl methacrylate, and N,N-dimethylformamide were mixed in a mass ratio of 0.12–0.18:0.22–0.32:1 to obtain a mixture. Under a nitrogen atmosphere, 3.5–4% (by mass) of N-bisisobutyronitrile (DIBN) was added to the mixture, the temperature was raised to 65–70°C and kept at that temperature for 22–24 hours. After cooling to room temperature, 100–200% (by mass) of deionized water was added to the mixture, the mixture was allowed to stand for 8–10 minutes, filtered, and washed 2–4 times with deionized water. After drying, the copolymer base material was obtained.

2. The method for selective etching of thin tin on a circuit board with corrosion resistance according to claim 1, characterized in that, The mass fraction of the hydrogen peroxide aqueous solution is 0.3% to 0.6%; The mass fraction of the sulfuric acid aqueous solution is 0.5% to 2%; The mass fraction of the hydrogen chloride aqueous solution is 0.005–0.01%; The preparation process of the micro-etching solution is as follows: Accurately weigh out the aqueous solutions of hydrogen peroxide, sulfuric acid, and hydrogen chloride, the compound stabilizer, and deionized water, and set aside for later use; Under conditions of 200–300 r / min, sulfuric acid aqueous solution, hydrogen chloride aqueous solution, hydrogen peroxide aqueous solution and compound stabilizer were sequentially placed in deionized water and mixed to prepare a micro-etching solution.

3. The selective etching method for thin tin on a circuit board with corrosion resistance as described in claim 1, characterized in that, The electroplating current density is 1-3 A / dm², the electroplating time is 5-10 min, and the electroplating temperature is 20-30℃.

4. The method for selective etching of thin tin on a circuit board with corrosion resistance according to claim 1, characterized in that, The preparation process of the resist is as follows: Accurately weigh the copolymer base material, N,N-dimethylethanolamine, p-nitrobenzenediazotetrafluoroborate, 1-hydroxycyclohexylphenyl ketone and water, and set aside. The copolymer base material and water are placed in a mixing device and treated at 200-300 r / min for 10-15 min. Then, N,N-dimethylethanolamine, p-nitrobenzene diazonium tetrafluoroborate and 1-hydroxycyclohexylphenyl ketone are added and the mixture is stirred for another 20-30 min to prepare the corrosion resist.

5. The method for selective etching of thin tin on a circuit board with corrosion resistance according to claim 1, characterized in that, The sodium hydroxide solution has a mass fraction of 1-4%.

6. The method for selective etching of thin tin on a circuit board with corrosion resistance according to claim 1, characterized in that, The temperature for demolding is 50–60°C.

Images