Circuit board thin tin etching solution and preparation method thereof

Abstract

The application relates to the field of etching liquid, in particular to a circuit board thin tin etching liquid and a preparation method thereof. The circuit board thin tin etching liquid comprises a main agent and an auxiliary agent; the main agent raw material is as follows: 4-6% of inorganic acid, 15-20% of organic acid, 5-8% of oxidant, 1-3% of complexing agent, 2-3.5% of auxiliary agent, 2.5-4% of protective agent, 0.5-1% of copper protective agent, 0.5-1.5% of stabilizer, 3-5% of carboxyl compound and deionized water to make up the rest. The auxiliary agent raw material is as follows: 6-8% of inorganic acid, 10-14% of organic acid, 2-4% of oxidant, 1-3% of carboxyl compound and deionized water to make up the rest. The circuit board thin tin etching liquid prepared by the application not only has excellent etching precision and good etching effect, but also avoids the emergence of chamfering, tailing, tin dissolving and tin surface oxidation, and has very high load and self stability, thereby meeting the performance requirements of the existing thin tin etching liquid in the existing circuit board manufacturing field.

Description

Technical Field

[0001] This application relates to the field of etching solutions, and more particularly to a thin tin etching solution for circuit boards and its preparation method. Background Technology

[0002] In the electronics manufacturing industry, circuit boards are the fundamental platform for assembling electronic components, and the etching process for thin tin layers is an indispensable part of manufacturing high-quality multilayer circuit boards. Etching solutions are widely used in the manufacturing process of printed circuit boards (PCBs) to precisely remove unwanted metal layers, thereby forming the desired conductive line patterns. As electronic products develop towards miniaturization, lightweighting, and high performance, higher demands are placed on the fine line fabrication of circuit boards. This requires not only that the etching solution possess good selectivity, uniformity, and stability, but also that it ensures good surface quality and no residue after etching.

[0003] Traditional thin tin etching solutions are primarily based on chemical components such as ferric chloride (FeCl3) solution or sulfuric acid-hydrogen peroxide mixture. While these traditional etching solutions can meet basic etching requirements, they have some limitations and challenges. For example, ferric chloride solution, due to its highly corrosive and difficult-to-control properties, is prone to over-etching or lateral etching, affecting the precision and reliability of the final product. Furthermore, it can pollute the environment and has high treatment costs. On the other hand, while the sulfuric acid-hydrogen peroxide system provides better etching results, it releases harmful gases during use, and due to its strong oxidizing properties, it may damage non-target materials, such as polymer coatings on the substrate.

[0004] However, existing thin tin etching solutions for circuit boards still suffer from insufficient etching precision, significant defects in etching effect such as chamfering and tailing, low loading capacity, and poor stability. Therefore, to address these issues, this application provides a thin tin etching solution for circuit boards and its preparation method. The resulting etching solution not only possesses excellent etching precision and good etching effect, avoiding chamfering, tailing, tin dissolution, and tin surface oxidation, but also exhibits extremely high loading capacity and stability, meeting the performance requirements of existing thin tin etching solutions in the current circuit board manufacturing industry. Summary of the Invention

[0005] To address the aforementioned problems, the first aspect of this application provides a thin tin etching solution for circuit boards, comprising a main agent and auxiliary agents; the main agent, by mass percentage, comprises: 4-6% inorganic acid, 15-20% organic acid, 5-8% oxidant, 1-3% complexing agent, 2-3.5% auxiliary agent, 2.5-4% protective agent, 0.5-1% copper protectant, 0.5-1.5% stabilizer, 3-5% carboxyl compound, with deionized water to make up the balance.

[0006] As a preferred embodiment, the excipients, by mass percentage, consist of: 6-8% inorganic acid, 10-14% organic acid, 2-4% oxidant, 1-3% carboxyl compound, and the remainder is deionized water.

[0007] As a preferred embodiment, the dosage relationship between the main agent and the auxiliary agent is as follows: during etching, the main agent is used for etching, and as the etching progresses, for every 200 ppm increase in the concentration of loaded tin ions, an auxiliary agent of 0.2 to 0.25% of the main agent mass percentage is added.

[0008] As a preferred embodiment, the inorganic acid is at least one selected from nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, and hydrofluoric acid.

[0009] As a preferred embodiment, the inorganic acid is nitric acid or hydrochloric acid.

[0010] As a preferred embodiment, the organic acid is oxalic acid.

[0011] As a preferred embodiment, the oxidant is at least one selected from ferric nitrate, ammonium persulfate, hydrogen peroxide, potassium iodate, and potassium persulfate.

[0012] As a preferred embodiment, the oxidant is ferric nitrate.

[0013] As a preferred embodiment, the complexing agent is at least one of EDTA, DTPA, EGTA, NTA, CDTA, and TTHA.

[0014] As a preferred embodiment, the complexing agent is a combination of EDTA, DTPA, and TTHA.

[0015] As a preferred embodiment, the mass ratio of EDTA, DTPA, and TTHA is (4-5):(1-1.5):(0.2-0.4).

[0016] As a preferred embodiment, the mass ratio of EDTA, DTPA, and TTHA is (4-4.5):(1-1.2):(0.2-0.3).

[0017] As a preferred embodiment, the additive is a composition of isomeric C12-C13 fatty alcohol polyoxyethylene ether, phenethylphenol polyoxyethylene ether, and block polyether.

[0018] As a preferred embodiment, the mass ratio of the isomeric C12-C13 fatty alcohol polyoxyethylene ether, phenethylphenol polyoxyethylene ether, and block polyether is (3-4):(1.2-1.6):(0.2-0.3).

[0019] As a preferred embodiment, the mass ratio of the isomeric C12-C13 fatty alcohol polyoxyethylene ether, phenethylphenol polyoxyethylene ether, and block polyether is (3.4-3.8):(1.4-1.5):(0.2-0.25).

[0020] As a preferred embodiment, the hydroxyl value of the isomeric C12-C13 fatty alcohol polyoxyethylene ether is 150-200 mg KOH / g.

[0021] As a preferred embodiment, the hydroxyl value of the isomeric C12-C13 fatty alcohol polyoxyethylene ether is 180-195 mgKOH / g.

[0022] As a preferred embodiment, the phenethylphenol polyoxyethylene ether has an HLB value of 12 to 18.

[0023] As a preferred embodiment, the phenethylphenol polyoxyethylene ether has an HLB value of 16 to 18.

[0024] As a preferred embodiment, the block polyether has a weight-average molecular weight of 8000–12000 Da.

[0025] As a preferred embodiment, the block polyether has a weight-average molecular weight of 10,000 to 11,000 Da.

[0026] This application utilizes a combination of the aforementioned additives to effectively improve the etching efficiency of thin tin etching solution while effectively preventing phenomena such as chamfering, tailing, tin dissolution, and tin surface oxidation. This increases the solution's loading capacity and maintains good stability. The combined effect of these additives forms a film system in the etching solution, composed of overlapping phases of different additives. This system effectively encapsulates and blocks excessive free collisions of active molecules within the system during storage, reducing the probability of mutual contact, preventing the aggregation of insoluble particles, and avoiding particle deposition, thereby achieving excellent stability. On the other hand, the combination of the above-mentioned specific conditional additives can fully utilize their film-layer effect to form a good film layer effect on the etched surface, and can more easily penetrate into the fine structure of the metal surface and improve the rheological properties of the system, making the system and the etching process more stable. Finally, through the film layer effect, it provides a good ordered transport effect on the etched surface, avoiding excessive contact of active molecules per unit area with the etched surface. Thus, during the etching process, it can effectively avoid the occurrence of chamfering, tailing, tin dissolution and tin surface oxidation phenomena of the etching solution. Moreover, its higher film layer retention can greatly improve the system's preservation effect on loaded ions, and significantly increase its loading limit in the process of reducing free state.

[0027] As a preferred embodiment, the protective agent is at least one selected from benzotriazole, methylbenzotriazole, mercaptobenzothiazole, sodium stearate, and imidazoline.

[0028] As a preferred option, the protective agent is benzotriazole.

[0029] As a preferred embodiment, the copper protectant is at least one of zinc diethyl dithiocarbamate, 8-hydroxyquinoline, thiourea, and 2-mercaptobenzimidazole.

[0030] As a preferred embodiment, the copper protectant is 8-hydroxyquinoline.

[0031] As a preferred embodiment, the stabilizer is at least one selected from polyvinylpyrrolidone, polyacrylic acid, and polyethylene oxide.

[0032] As a preferred embodiment, the stabilizer is a combination of polyvinylpyrrolidone and polyethylene oxide.

[0033] As a preferred embodiment, the mass ratio of polyvinylpyrrolidone to polyethylene oxide is (3-3.5):(0.6-1).

[0034] As a preferred embodiment, the carboxyl compound is a combination of malonic acid, adipic acid, and citric acid.

[0035] As a preferred embodiment, the mass ratio of malonic acid, adipic acid and citric acid is (5-6):(2-3):(4-4.5).

[0036] As a preferred embodiment, the mass ratio of malonic acid, adipic acid and citric acid is 5.5:2.5:4.2.

[0037] As a preferred embodiment, the mass ratio of inorganic acid, organic acid, oxidant, auxiliary agent and carboxyl compound in the main agent is (4.5-5.5):(16-18):(6-7):(2.5-3):(3.5-4).

[0038] As a preferred embodiment, the mass ratio of inorganic acid, organic acid, oxidant and carboxyl compound in the excipient is (7-7.5):(11-12.5):(2.2-3):(1.1-1.5).

[0039] The second aspect of this application provides a method for preparing the above-mentioned thin tin etching solution for circuit boards, specifically including the following steps: S1: Add the raw materials required for the main agent and the auxiliary agent to different mixing containers, and stir at 35-45°C and 60-100 rpm for 40-60 minutes to obtain the main agent and the auxiliary agent; S2: When using, add the auxiliary agent to the main agent according to the concentration of tin ions loaded, and the solution is obtained.

[0040] The beneficial effects of this application are:

[0041] 1. The thin tin etching solution for circuit boards provided in this application not only has excellent etching precision and good etching effect, avoiding the occurrence of chamfering, tailing, tin dissolution and tin surface oxidation, but also has extremely high loading capacity and self-stability, meeting the performance requirements of the existing circuit board manufacturing field for existing thin tin etching solutions.

[0042] 2. The thin tin etching solution for circuit boards provided in this application employs a combination of composite additives, which effectively improves the etching efficiency of the thin tin etching solution while effectively avoiding phenomena such as chamfering, tailing, tin dissolution, and tin surface oxidation. This increases its loading capacity while maintaining good stability. The combined effect of the aforementioned additives forms a film system in the etching solution system, composed of overlapping different additive phases. This system effectively encapsulates and blocks excessive free collisions of active molecules within the system during storage, reducing the probability of mutual contact, preventing the aggregation of insoluble particles, and avoiding particle deposition, thereby achieving excellent stability.

[0043] 3. The thin tin etching solution for circuit boards provided in this application uses a combination of composite additives, which can fully utilize their film layer effect to form a good film layer effect on the etching surface. It can also more easily penetrate into the fine structure of the metal surface and improve the rheological properties of the system, making the system and etching process more stable. Finally, through the film layer effect, it provides a good ordered transport effect on the etching surface, avoiding excessive contact of active molecules per unit area with the etching surface. Thus, during the etching process, it can effectively avoid the occurrence of chamfering, tailing, tin dissolution and tin surface oxidation phenomena of the etching solution. Moreover, its higher film layer retention can greatly improve the system's preservation effect on loaded ions, and significantly increase its upper limit of loading while reducing free state. Detailed Implementation

[0044] The following will further illustrate and demonstrate the technical solutions described above in this application through specific implementation schemes. Furthermore, the following embodiments are merely practical examples used to illustrate and explain the content of the technical solutions in the specification, and should not limit the scope of the claims to be protected by this application. All technical products based on the technical solutions described in this application should be covered within the scope of protection of this application.

[0045] In the following embodiments, unless otherwise specified, the raw materials are all commercially available products or can be prepared by methods known to those skilled in the art.

[0046] Example 1

[0047] Example 1 provides a thin tin etching solution for circuit boards, comprising a main agent and an auxiliary agent.

[0048] The main component, by mass percentage, consists of: 4.8% inorganic acid, 17.2% organic acid, 6.6% oxidant, 2.1% complexing agent, 2.8% auxiliary agent, 2.9% protective agent, 0.8% copper protectant, 0.7% stabilizer, 3.8% carboxyl compound, and deionized water to make up the balance.

[0049] The excipients, by mass percentage, are: 7.4% inorganic acid, 12.1% organic acid, 2.6% oxidant, 1.2% carboxyl compound, and deionized water to make up the balance.

[0050] The dosage relationship between the main agent and the auxiliary agent is as follows: during etching, the main agent is used for etching, and as the etching progresses, for every 200ppm increase in the concentration of loaded tin ions, an auxiliary agent of 0.22% of the main agent mass percentage is added.

[0051] The inorganic acid is nitric acid; the organic acid is oxalic acid; and the oxidizing agent is ferric nitrate.

[0052] The complexing agent is a composition of EDTA, DTPA and TTHA, with a mass ratio of 4.2:1.1:0.2.

[0053] The additive is a composition of isomeric C12-C13 fatty alcohol polyoxyethylene ether, phenylethylphenol polyoxyethylene ether and block polyether, with a mass ratio of 3.5:1.4:0.22.

[0054] The hydroxyl value of the isomeric C12-C13 fatty alcohol polyoxyethylene ether is 190 mg KOH / g, and it is E-1302 product purchased from Haian Guoyun Chemical Co., Ltd. in China.

[0055] The HLB value of phenethylphenol polyoxyethylene ether is 17, and the corresponding HLB value product was purchased from Haian Guoyun Chemical Co., Ltd. in China.

[0056] The block polyether has a weight-average molecular weight of 11,000 Da and was purchased from BASF Germany as a product of the corresponding weight-average molecular weight L series of epoxy block polyethers.

[0057] The protective agent is benzotriazole; the copper protective agent is 8-hydroxyquinoline.

[0058] The stabilizer is a composition of polyvinylpyrrolidone K90 and polyethylene oxide in a mass ratio of 3.4:0.8. The polyethylene oxide was purchased as a standard industrial-grade product from Hubei Huada Fine Chemical Co., Ltd., China.

[0059] The carboxyl compound is a combination of malonic acid, adipic acid and citric acid in a mass ratio of 5.5:2.5:4.2.

[0060] The second aspect of this embodiment provides a method for preparing the above-mentioned thin tin etching solution for circuit boards, specifically including the following steps: S1: Add the raw materials required for the main agent and the auxiliary agent to different mixing containers, and stir at 80 rpm for 55 minutes at 40°C to obtain the main agent and the auxiliary agent; S2: When using, add the auxiliary agent to the main agent according to the concentration of tin ions loaded, and the solution is obtained.

[0061] Example 2

[0062] The specific implementation method of this embodiment is basically the same as that of embodiment 1, except that the thin tin etching solution for the circuit board includes a main agent and an auxiliary agent.

[0063] The main component, by mass percentage, consists of the following raw materials: 5.4% inorganic acid, 16.2% organic acid, 6% oxidant, 2.1% complexing agent, 2.5% auxiliary agent, 2.9% protective agent, 0.8% copper protectant, 0.7% stabilizer, 3.5% carboxyl compound, and deionized water to make up the balance.

[0064] The excipients, by mass percentage, are: 7% inorganic acid, 11% organic acid, 2.2% oxidant, 1.5% carboxyl compound, and deionized water to make up the balance.

[0065] The complexing agent is a composition of EDTA, DTPA and TTHA in a mass ratio of 5:1:0.4.

[0066] The additive is a composition of isomeric C12-C13 fatty alcohol polyoxyethylene ether, phenylethylphenol polyoxyethylene ether and block polyether, with a mass ratio of 3:1.6:0.3.

[0067] The stabilizer is a combination of polyvinylpyrrolidone K90 and polyethylene oxide in a mass ratio of 3:1.

[0068] The carboxyl compound is a combination of malonic acid, adipic acid and citric acid in a mass ratio of 6:2:4.5.

[0069] Example 3

[0070] The specific implementation method of this embodiment is basically the same as that of embodiment 1, except that the thin tin etching solution for the circuit board includes a main agent and an auxiliary agent.

[0071] The main component, by mass percentage, consists of: 4.5% inorganic acid, 17.8% organic acid, 7% oxidant, 2.1% complexing agent, 3% auxiliary agent, 2.9% protective agent, 0.8% copper protectant, 0.7% stabilizer, 4% carboxyl compound, and deionized water to make up the balance.

[0072] The excipients, by mass percentage, are: 7.5% inorganic acid, 12.5% ​​organic acid, 3% oxidant, 1.1% carboxyl compound, and deionized water to make up the balance.

[0073] The complexing agent is a composition of EDTA, DTPA and TTHA in a mass ratio of 4:1.5:0.2.

[0074] The additive is a composition of isomeric C12-C13 fatty alcohol polyoxyethylene ether, phenylethylphenol polyoxyethylene ether and block polyether, with a mass ratio of 4:1.2:0.2.

[0075] The stabilizer is a composition of polyvinylpyrrolidone K90 and polyethylene oxide in a mass ratio of 3.5:0.6.

[0076] The carboxyl compound is a combination of malonic acid, adipic acid and citric acid in a mass ratio of 5:3:4.

[0077] Comparative Example 1

[0078] The specific implementation method of this comparative example is basically the same as that of Example 1, except that: the main agent, by mass percentage, consists of: 5.5% inorganic acid, 18.5% organic acid, 6.6% oxidant, 2.1% complexing agent, 1.1% auxiliary agent, 2.9% protective agent, 0.8% copper protectant, 0.7% stabilizer, 1.6% carboxyl compound, and deionized water to make up the balance.

[0079] The excipients, by mass percentage, are: 7.4% inorganic acid, 12.1% organic acid, 2.6% oxidant, 0.4% carboxyl compound, and deionized water to make up the balance.

[0080] Comparative Example 2

[0081] The specific implementation method of this comparative example is basically the same as that of Example 1, except that: the main agent, by mass percentage, consists of: 4.8% inorganic acid, 17.2% organic acid, 6.6% oxidant, 2.1% complexing agent, 4.5% auxiliary agent, 2.9% protective agent, 0.8% copper protectant, 0.7% stabilizer, 1.2% carboxyl compound, and deionized water to make up the balance.

[0082] The excipients, by mass percentage, consist of: 7.4% inorganic acid, 12.1% organic acid, 2.6% oxidant, and the remainder is deionized water.

[0083] Comparative Example 3

[0084] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the carboxyl compound is a combination of malonic acid, adipic acid and citric acid, and the mass ratio of the three is 1:1:0.5.

[0085] Comparative Example 4

[0086] The specific implementation method of this comparative example is basically the same as that of Example 1, except that: the complexing agent is EDTA; the stabilizer is a composition of polyvinylpyrrolidone K90 and polyethylene oxide, with a mass ratio of 8:0.6.

[0087] Comparative Example 5

[0088] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the auxiliary agent is a composition of isomeric C12-C13 fatty alcohol polyoxyethylene ether, phenylethylphenol polyoxyethylene ether and block polyether, and the mass ratio of the three is 8:1:0.1.

[0089] Comparative Example 6

[0090] The specific implementation method of this comparative example is basically the same as that of Example 1, except that the auxiliary agent is a composition of isomeric C12-C13 fatty alcohol polyoxyethylene ether, phenylethylphenol polyoxyethylene ether and block polyether, and the mass ratio of the three is 1:1.5:1.

[0091] Performance Evaluation

[0092] The etching solutions prepared using the examples and comparative examples were used for performance testing. The test target was a copper-based thin tin film circuit board with a copper thickness of 5000 Å, a tin thickness of 300 Å, an etching temperature of 35°C, and an etching time of 160–190 sec.

[0093] After etching is completed, check for chamfering and tailing phenomena. If they are present, they are marked as unqualified; otherwise, they are qualified. 50 samples are tested in each group, and the pass rate is recorded in Table 1.

[0094] After etching, check for signs of molten tin and oxidation on the tin surface. If any are found, the test is considered unqualified; otherwise, it is considered qualified. Each group tests 50 samples, and the pass rate is recorded in Table 1.

[0095] Record the highest tin load during the etching process, in whole numbers of 1000, and record the results in Table 1.

[0096] Record the CD-loss (single-sided, μm) results in the etching results, and take the average of 10 tests and record it in Table 1.

[0097] The etching solutions prepared in the examples and comparative examples were subjected to stability tests. The test environment temperature was 60±2℃ and the relative humidity was 75±2%. The etching solutions were kept at constant temperature and humidity for 72 hours. After completion, the solutions were taken out and observed for stratification, segregation and suspended impurities. If they were present, they were recorded as unqualified, otherwise they were qualified. 50 samples were tested in each group, and the pass rate was recorded in Table 1.

[0098] Table 1 Performance Test Results

[0099]

[0100]

[0101] From the embodiments and comparative examples of this application, as well as the data results in Table 1, it can be seen that Embodiments 1 and 2 of this application have significant advantages over Comparative Examples 1 to 6 in terms of etching effect, anti-beveling and tailing effect, anti-solder melting and tin surface oxidation effect, etching precision, and self-stability. This is mainly due to the combined effect of the functional additives and other cooperating technical solutions specified in this application. Comparative Examples 1 to 6, on the other hand, did not fully adopt the technical solutions specified in this application, resulting in significant disadvantages in the above performance tests. This further proves the necessity of the technical solutions specified in this application for the technical effect of this application and for solving technical problems.

Claims

1. A thin tin etching solution for circuit boards, characterized in that: It includes a main agent and excipients; the main agent, by mass percentage, consists of the following raw materials: 4-6% inorganic acid, 15-20% organic acid, 5-8% oxidant, 1-3% complexing agent, 2-3.5% auxiliary agent, 2.5-4% protective agent, 0.5-1% copper protectant, 0.5-1.5% stabilizer, 3-5% carboxyl compound, and deionized water to make up the balance; The excipients, by mass percentage, consist of: 6-8% inorganic acid, 10-14% organic acid, 2-4% oxidant, 1-3% carboxyl compound, and deionized water to make up the balance. The dosage relationship between the main agent and the auxiliary agent is as follows: during etching, the main agent is used for etching, and as the etching progresses, for every 200 ppm increase in the concentration of loaded tin ions, an auxiliary agent of 0.2 to 0.25% of the main agent mass percentage is added. The inorganic acid is at least one of nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, and hydrofluoric acid; The organic acid is oxalic acid; The additive is a composition of isomeric C12-C13 fatty alcohol polyoxyethylene ether, phenethylphenol polyoxyethylene ether and block polyether; The mass ratio of the isomeric C12-C13 fatty alcohol polyoxyethylene ether, phenethylphenol polyoxyethylene ether, and block polyether is (3-4):(1.2-1.6):(0.2-0.3). The stabilizer is a combination of polyvinylpyrrolidone and polyethylene oxide; The mass ratio of polyvinylpyrrolidone to polyethylene oxide is (3-3.5):(0.6-1); The carboxyl compound is a combination of malonic acid, adipic acid, and citric acid; The mass ratio of malonic acid, adipic acid and citric acid is (5-6):(2-3):(4-4.5).

2. The circuit board thin tin etching solution according to claim 1, characterized in that: In the main agent, the mass ratio of inorganic acid, organic acid, oxidant, auxiliary agent and carboxyl compound is (4.5-5.5): (16-18): (6-7): (2.5-3): (3.5-4).

3. The circuit board thin tin etching solution according to claim 2, characterized in that: The complexing agent is at least one of EDTA, DTPA, EGTA, NTA, CDTA, and TTHA.

4. The circuit board thin tin etching solution according to claim 3, characterized in that: The complexing agent is a composition of EDTA, DTPA and TTHA; the mass ratio of EDTA, DTPA and TTHA is (4-5):(1-1.5):(0.2-0.4).

5. The circuit board thin tin etching solution according to claim 4, characterized in that: The hydroxyl value of the isomeric C12-C13 fatty alcohol polyoxyethylene ether is 150-200 mgKOH / g.

6. The circuit board thin tin etching solution according to claim 5, characterized in that: The HLB value of the phenethylphenol polyoxyethylene ether is 12 to 18.

7. The circuit board thin tin etching solution according to claim 6, characterized in that: The block polyether has a weight-average molecular weight of 8000–12000 Da.

8. The circuit board thin tin etching solution according to claim 7, characterized in that: The protective agent is at least one of benzotriazole, methylbenzotriazole, mercaptobenzothiazole, sodium stearate, and imidazoline.

9. The circuit board thin tin etching solution according to claim 8, characterized in that: The copper protectant is at least one of zinc diethyl dithiocarbamate, 8-hydroxyquinoline, thiourea, and 2-mercaptobenzimidazole.

10. A method for preparing a thin tin etching solution for circuit boards according to any one of claims 1 to 9, characterized in that: Specifically, the following steps are included: S1: Add the raw materials required for the main agent and the excipient to different mixing containers, and stir at 35-45℃ and 60-100 rpm for 40-60 minutes to obtain the main agent and the excipient; S2: When using, add the excipient to the main agent according to the concentration of tin ions loaded, and the product is obtained.

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