Low-corrosion efficient substrate plate etching solution and preparation method thereof

Abstract

The invention discloses a low-corrosion efficient base material plate etching solution and a preparation method thereof, and relates to the technical field of base material etching, the efficient viscosity reducer comprises the following components: an etching main agent, a composite corrosion inhibition system, a biodegradable chelating agent and a solvent; by introducing a composite corrosion inhibition system composed of 2-mercapto-5-methylbenzimidazole and plant source corrosion inhibition molecules, a compact adsorption film can be formed on the surface of a base material, the lateral corrosion rate of the etching liquid to the base material is reduced by 60% or above through the innovative design, the precision and edge quality of the etching process are remarkably improved, and the corrosion inhibition effect is good. And the roughness Ra of the edge of the etched substrate circuit is ensured to be less than or equal to 0.3 mu m, and the requirement of high-precision etching is met.

Description

Technical Field

[0001] This invention relates to the field of substrate etching technology, specifically to a low-corrosion, high-efficiency substrate etching solution and its preparation method. Background Technology

[0002] In the field of substrate etching technology, especially for etching of copper-based substrates and Cu / MoNb alloy substrates, extremely high requirements are placed on the precision, efficiency and environmental performance of etching solutions. With the rapid development of the electronics industry, the demand for manufacturing high-precision circuit boards and microelectronic components is increasing day by day. As one of the key links, the quality of the etching process directly affects the performance and reliability of the final product.

[0003] Traditional etching solutions often struggle to strike a balance between etching precision and environmental friendliness. On one hand, many etching solutions cause severe lateral corrosion to the substrate during etching, resulting in rough edges that fail to meet the demands of high-precision etching, impacting the electrical performance of circuit boards and the integration density of microelectronic components. On the other hand, some etching solutions have low copper ion tolerance, requiring frequent replacements, increasing production costs and waste disposal difficulties. More seriously, some traditional etching solutions use chelating agents that are difficult to biodegrade, causing long-term environmental pollution and contradicting current trends in green manufacturing and sustainable development. Furthermore, the complex composition and cumbersome preparation processes of some etching solutions also limit their application in large-scale industrial production.

[0004] In view of the problems of insufficient precision, poor environmental protection and complex preparation process of traditional etching solution technology, the present invention proposes a low-corrosion and high-efficiency substrate etching solution and its preparation method, which is of great importance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a low-corrosion, high-efficiency substrate etching solution and its preparation method. By introducing a composite corrosion inhibition system composed of 2-mercapto-5-methylbenzimidazole and plant-derived corrosion inhibitors, it significantly reduces the lateral corrosion rate of the substrate, improves etching precision, enhances the etching solution's tolerance to copper ions, and effectively reduces environmental pollution by using a biodegradable chelating agent. The etching solution of this invention not only meets the requirements of high-precision etching but also promotes green manufacturing and sustainable development, and has broad application prospects and market value.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a low-corrosion, high-efficiency substrate etching solution, made from the following raw materials in parts by weight: The composite corrosion inhibition system consists of 2-mercapto-5-methylbenzimidazole and plant-derived corrosion inhibition molecules, and the ratio of the two is optimized through quantum chemical simulation. The etching solution can form a dense adsorption film on the substrate surface, reducing the lateral corrosion rate of the substrate by more than 60%, and the copper ion tolerance in the etching solution is not less than 12,000 ppm.

[0007] Furthermore, the plant-derived corrosion inhibitory molecule is selected from at least one of Sophora japonica flower extract, kelp extract, and laver extract, and the main active ingredient of the plant-derived corrosion inhibitory molecule is a flavonoid compound or a polysaccharide substance with a purity of not less than 95%.

[0008] Furthermore, in the composite corrosion inhibition system, the molar ratio of 2-mercapto-5-methylbenzimidazole to plant-derived corrosion inhibitor molecules is 1:0.5~3.0. This ratio was determined through quantum chemical simulation calculations to optimize the synergistic adsorption effect of the two on the substrate surface.

[0009] Furthermore, the biodegradable chelating agent is selected from at least one of hydroxycarboxylate and organophosphate; the mass ratio of the biodegradable chelating agent to 2-mercapto-5-methylbenzimidazole is 1:0.2~2.0, and the biodegradation rate of the biodegradable chelating agent is not less than 95%.

[0010] Furthermore, the content of each component by mass is as follows: 10-25 parts of etching agent, 0.8-5.0 parts of composite corrosion inhibitor system, 1.0-5.0 parts of biodegradable chelating agent, and 65-88 parts of solvent.

[0011] Furthermore, the etching agent is selected from either the sulfuric acid-hydrogen peroxide system or acidic copper chloride; when the etching agent is the sulfuric acid-hydrogen peroxide system, the mass ratio of sulfuric acid to hydrogen peroxide is 3~8:1; when the etching agent is acidic copper chloride, its concentration is 120~180g / L.

[0012] Furthermore, the quantum chemical simulation employs density functional theory calculations, and by optimizing the ratio of 2-mercapto-5-methylbenzimidazole to plant-derived corrosion inhibitor molecules, the adsorption energy of both on the substrate surface reaches -4.5 to -6.0 eV.

[0013] Furthermore, the solvent is deionized water; the etching solution may also selectively contain a pH adjuster to stabilize the pH value of the etching solution within the range of 3.5 to 5.5.

[0014] Furthermore, the etching rate of the etching solution is 0.5~1.2μm / min, which is suitable for etching copper-based substrates or Cu / MoNb alloy substrates, and the roughness Ra of the substrate circuit edge after etching is ≤0.3μm.

[0015] On the other hand, a method for preparing a low-corrosion, high-efficiency substrate etching solution is characterized by comprising the following steps: S1. Place the solvent in a reaction vessel and stir at 100~200 rpm. Add the biodegradable chelating agent and control the temperature at 25~35℃. Continue stirring until the chelating agent is completely dissolved to obtain a clear pretreated solution. S2. Add the composite corrosion inhibitor system with optimized ratio by quantum chemical simulation to the pretreatment solution and use a gradient stirring process: first stir at 150~250 rpm for 10~15 min, then increase to 300~500 rpm and stir for 20~30 min to make 2-mercapto-5-methylbenzimidazole and plant-derived corrosion inhibitor molecules evenly dispersed. S3. Reduce the stirring speed to 200~300 rpm, add the etching agent, and continue stirring for 15~25 min. After the system is mixed evenly, selectively add a pH adjuster to adjust the pH value of the system to 3.5~5.5 to obtain the low-corrosion and high-efficiency substrate etching solution.

[0016] Compared with existing technologies, this low-corrosion, high-efficiency substrate etching solution and its preparation method have the following advantages: I. The low-corrosion, high-efficiency substrate etching solution of the present invention introduces a composite corrosion inhibition system composed of 2-mercapto-5-methylbenzimidazole and plant-derived corrosion inhibitor molecules, which can form a dense adsorption film on the substrate surface. This innovative design reduces the lateral corrosion rate of the substrate by more than 60%, significantly improves the precision and edge quality of the etching process, and ensures that the roughness Ra of the substrate circuit edge after etching is ≤0.3μm, meeting the requirements of high-precision etching.

[0017] Second, the etching solution of the present invention not only has high etching efficiency, but also significantly enhances its tolerance to copper ions to no less than 12,000 ppm. This characteristic extends the service life of the etching solution, reduces the frequency of replacement and the generation of waste. At the same time, it adopts a biodegradable chelating agent with a biodegradation rate of no less than 95%, which effectively reduces the environmental impact of the etching process and promotes green manufacturing and sustainable development.

[0018] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0020] Figure 1 This is a flowchart of a low-corrosion, high-efficiency substrate etching solution and its preparation method. Detailed Implementation

[0021] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0022] Examples one to three only varied the content of the composite corrosion inhibitor system. Example 1 Etching solution raw material composition: The low-corrosion and high-efficiency substrate etching solution described in this embodiment has the following components and specific dosages: 18 parts etching agent, 1.0 part composite corrosion inhibitor system, 3.0 parts biodegradable chelating agent, 78.0 parts solvent, and an appropriate amount of pH adjuster citric acid.

[0023] The etching agent uses a sulfuric acid-hydrogen peroxide system with a sulfuric acid to hydrogen peroxide mass ratio of 5:1. This system has stable etching capabilities and its oxidation efficiency is suitable for the etching requirements of copper-based substrates. The composite corrosion inhibitor system consists of 2-mercapto-5-methylbenzimidazole and Sophora japonica extract with a molar ratio of 1:1.5. After purification, the flavonoid active ingredients in the Sophora japonica extract have a purity of 96%, meeting the requirement of not less than 95%. Its corrosion inhibition performance has been verified by electrochemical methods and can effectively reduce the degree of corrosion on metal surfaces. The biodegradable chelating agent uses hydroxycarboxylate, with a mass ratio of 1:1.2 to 2-mercapto-5-methylbenzimidazole. The solvent is deionized water that meets electronic grade standards, which can avoid the interference of impurities on the etching effect.

[0024] Optimization of the composite corrosion inhibition system: Quantum chemical simulations using density functional theory were employed to optimize the ratio of 2-mercapto-5-methylbenzimidazole to Sophora japonica extract. By simulating the adsorption behavior of both on a copper-based surface, the aforementioned molar ratio of 1:1.5 was ultimately determined. At this ratio, the two components synergistically adsorb onto the substrate surface, achieving an adsorption energy of -4.6 eV, which falls within the optimal range of -4.5 to -6.0 eV, providing theoretical support for the formation of a dense adsorption film.

[0025] Preparation steps of the etching solution: Preparation of pretreatment solution: Take 78.0 parts of deionized water and place it in a reaction vessel equipped with a constant temperature stirring function. Turn on the stirring device and set the speed to 150 rpm, while controlling the temperature of the reaction system at 30℃. Slowly add 3.0 parts of hydroxycarboxylate chelating agent and continue stirring for 15 minutes until the chelating agent is completely dissolved, obtaining a clear and transparent pretreatment solution. Temperature control in this process ensures that the chelating agent is fully dissolved and its performance is stable.

[0026] Dispersion of the composite corrosion inhibition system: 1.0 part of the composite corrosion inhibition system with a ratio optimized by quantum chemical simulation was added to the above pretreatment solution. The dispersion effect was improved by gradient stirring process: first, the stirring speed was increased to 200 rpm for 12 min to initially disperse the corrosion inhibition components; then the speed was increased to 400 rpm and stirring was continued for 25 min to ensure that 2-mercapto-5-methylbenzimidazole and Sophora japonica extract were evenly distributed in the system and to avoid local concentration differences from affecting the corrosion inhibition effect.

[0027] Preparation of the final product: Reduce the stirring speed to 250 rpm, slowly add the etching agent consisting of 15 parts sulfuric acid and 3 parts hydrogen peroxide, and continue stirring for 20 minutes to ensure uniform mixing. Take a sample to test the pH value of the system, and adjust the pH value to 4.5 by adding citric acid. This pH value is within the stable range of 3.5 to 5.5, and finally a clear, transparent, brownish-yellow, low-corrosion, high-efficiency substrate etching solution is obtained.

[0028] Results: Corrosion control performance: Through comparative experiments, the etching solution forms a denser adsorption film on the copper substrate surface, and the lateral corrosion rate of the substrate is reduced by 62% compared with conventional etching solutions, meeting the 60% target requirement; during the recycling of the etching solution, the copper ion tolerance reaches 12,500 ppm, meeting the usage requirement of not less than 12,000 ppm.

[0029] Etching efficiency and precision: The etching rate is stable at 0.9 μm / min, which is within the high-efficiency range of 0.5~1.2 μm / min; After etching, the roughness of the substrate circuit edge is detected by atomic force microscopy, and the Ra value is 0.25 μm, which meets the precision machining requirements of ≤0.3 μm.

[0030] Application compatibility: This etching solution has a good etching effect on copper-based substrates. After etching, there are no obvious pinhole defects on the substrate surface, which can meet the processing requirements of conventional electronic components.

[0031] Example 2 Etching solution raw material composition: The low-corrosion and high-efficiency substrate etching solution described in this embodiment has the following components and specific dosages: 18 parts etching agent, 4.0 parts composite corrosion inhibitor system, 3.0 parts biodegradable chelating agent, 75.0 parts solvent, and an appropriate amount of pH adjuster citric acid.

[0032] The etching agent uses a sulfuric acid-hydrogen peroxide system with a sulfuric acid to hydrogen peroxide mass ratio of 5:1. This system has stable etching capabilities and its oxidation efficiency is suitable for the etching requirements of copper-based substrates. The composite corrosion inhibitor system consists of 2-mercapto-5-methylbenzimidazole and Sophora japonica extract with a molar ratio of 1:1.5. After purification, the flavonoid active ingredients in the Sophora japonica extract have a purity of 96%, meeting the requirement of not less than 95%. Its corrosion inhibition performance has been verified by electrochemical methods and can effectively reduce the degree of corrosion on metal surfaces. The biodegradable chelating agent uses hydroxycarboxylate, with a mass ratio of 1:1.2 to 2-mercapto-5-methylbenzimidazole. The solvent is deionized water that meets electronic grade standards, which can avoid the interference of impurities on the etching effect.

[0033] Optimization of the composite corrosion inhibition system: Quantum chemical simulations using density functional theory were employed to optimize the ratio of 2-mercapto-5-methylbenzimidazole to Sophora japonica extract. By simulating the adsorption behavior of both on a copper substrate, the aforementioned molar ratio of 1:1.5 was ultimately determined. At this ratio, the two components synergistically adsorb onto the substrate surface, achieving an adsorption energy of -5.5 eV, which falls within the optimal range of -4.5 to -6.0 eV, providing theoretical support for the formation of a dense adsorption film.

[0034] Preparation steps of the etching solution: Pretreatment solution preparation: Take 75.0 parts of deionized water and place it in a reaction vessel equipped with a constant temperature stirring function. Turn on the stirring device and set the speed to 150 rpm, while controlling the temperature of the reaction system at 30℃. Slowly add 3.0 parts of hydroxycarboxylate chelating agent and continue stirring for 15 minutes until the chelating agent is completely dissolved, obtaining a clear and transparent pretreatment solution. Temperature control in this process ensures that the chelating agent is fully dissolved and its performance is stable.

[0035] Dispersion of the composite corrosion inhibition system: 4.0 parts of the composite corrosion inhibition system with a ratio optimized by quantum chemical simulation were added to the above pretreatment solution. The dispersion effect was improved by gradient stirring process: first, the stirring speed was increased to 200 rpm for 12 min to initially disperse the corrosion inhibition components; then the speed was increased to 400 rpm and stirring was continued for 25 min to ensure that 2-mercapto-5-methylbenzimidazole and Sophora japonica extract were evenly distributed in the system and to avoid local concentration differences from affecting the corrosion inhibition effect.

[0036] Preparation of the final product: Reduce the stirring speed to 250 rpm, slowly add the etching agent consisting of 15 parts sulfuric acid and 3 parts hydrogen peroxide, and continue stirring for 20 minutes to ensure uniform mixing. Take a sample to test the pH value of the system, and adjust the pH value to 4.5 by adding citric acid. This pH value is within the stable range of 3.5 to 5.5, and finally a clear, transparent, brownish-yellow, low-corrosion, high-efficiency substrate etching solution is obtained.

[0037] Results: Corrosion control performance: Through comparative experiments, the etching solution forms an extremely dense adsorption film on the copper substrate surface, and the lateral corrosion rate of the substrate is reduced by 72% compared with conventional etching solutions, which is far higher than the target requirement of 60%; during the recycling of the etching solution, the copper ion tolerance reaches 14,000 ppm, which meets the usage requirement of not less than 12,000 ppm.

[0038] Etching efficiency and precision: The etching rate is stable at 0.8 μm / min, which is in the high-efficiency range of 0.5~1.2 μm / min; After etching, the roughness of the substrate circuit edge is detected by atomic force microscopy, and the Ra value is 0.20 μm, which meets the precision machining requirements of ≤0.3 μm.

[0039] Application compatibility: This etching solution has excellent etching effect on Cu / MoNb alloy substrates. After etching, the substrate surface is smooth and flat without pit defects, which can meet the processing requirements of high-precision semiconductor packaging components.

[0040] Example 3 Etching solution raw material composition: The low-corrosion and high-efficiency substrate etching solution described in this embodiment has the following components and specific dosages: 18 parts etching agent, 5.0 parts composite corrosion inhibitor system, 3.0 parts biodegradable chelating agent, 74.0 parts solvent, and an appropriate amount of pH adjuster citric acid.

[0041] The etching agent uses a sulfuric acid-hydrogen peroxide system with a sulfuric acid to hydrogen peroxide mass ratio of 5:1. This system has stable etching capabilities and its oxidation efficiency is suitable for the etching requirements of copper-based substrates. The composite corrosion inhibitor system consists of 2-mercapto-5-methylbenzimidazole and Sophora japonica extract with a molar ratio of 1:1.5. After purification, the flavonoid active ingredients in the Sophora japonica extract have a purity of 96%, meeting the requirement of not less than 95%. Its corrosion inhibition performance has been verified by electrochemical methods and can effectively reduce the degree of corrosion on metal surfaces. The biodegradable chelating agent uses hydroxycarboxylate, with a mass ratio of 1:1.2 to 2-mercapto-5-methylbenzimidazole. The solvent is deionized water that meets electronic grade standards, which can avoid the interference of impurities on the etching effect.

[0042] Optimization of the composite corrosion inhibition system: Quantum chemical simulations using density functional theory were employed to optimize the ratio of 2-mercapto-5-methylbenzimidazole to Sophora japonica extract. By simulating the adsorption behavior of both on the copper substrate, the aforementioned molar ratio of 1:1.5 was ultimately determined. At this ratio, the two components synergistically adsorb onto the substrate surface, achieving an adsorption energy of -5.8 eV, which falls within the optimal range of -4.5 to -6.0 eV, providing theoretical support for the formation of a dense adsorption film.

[0043] Preparation steps of etching solution: Pretreatment solution preparation: Take 74.0 parts of deionized water and place it in a reaction vessel equipped with a constant temperature stirring function. Turn on the stirring device and set the speed to 150 rpm, while controlling the temperature of the reaction system at 30℃. Slowly add 3.0 parts of hydroxycarboxylate chelating agent and continue stirring for 15 minutes until the chelating agent is completely dissolved, obtaining a clear and transparent pretreatment solution. Temperature control in this process ensures that the chelating agent is fully dissolved and its performance is stable.

[0044] Dispersion of the composite corrosion inhibition system: 5.0 parts of the composite corrosion inhibition system with optimized proportions through quantum chemical simulation were added to the above pretreatment solution. A gradient stirring process was used to improve the dispersion effect: first, the stirring speed was increased to 200 rpm for 12 min to initially disperse the corrosion inhibition components; then, the speed was increased to 400 rpm and stirring was continued for 25 min to ensure that 2-mercapto-5-methylbenzimidazole and Sophora japonica extract were evenly distributed in the system, avoiding local concentration differences that would affect the corrosion inhibition effect.

[0045] Preparation of the final product: Reduce the stirring speed to 250 rpm, slowly add the etching agent consisting of 15 parts sulfuric acid and 3 parts hydrogen peroxide, and continue stirring for 20 minutes to ensure uniform mixing. Take a sample to test the pH value of the system, and adjust the pH value to 4.5 by adding citric acid. This pH value is within the stable range of 3.5 to 5.5, and finally a clear, transparent, brownish-yellow, low-corrosion, high-efficiency substrate etching solution is obtained.

[0046] Results: Corrosion control performance: Through comparative experiments, the etching solution forms an ultra-dense adsorption film on the copper substrate surface, reducing the lateral corrosion rate of the substrate by 75% compared to conventional etching solutions, which is far higher than the 60% requirement. During the recycling of the etching solution, the copper ion tolerance reaches 14,500 ppm, meeting the usage requirement of not less than 12,000 ppm.

[0047] Etching efficiency and precision: The etching rate is stable at 0.7 μm / min, which is in the high-efficiency range of 0.5~1.2 μm / min; After etching, the roughness of the substrate circuit edge is detected by atomic force microscopy, and the Ra value is 0.18 μm, which meets the precision machining requirements of ≤0.3 μm.

[0048] Application compatibility: This etching solution has an excellent etching effect on Cu / MoNb alloy substrates, and the etched substrate lines have neat edges, which can meet the processing requirements of core components of high-end intelligent equipment.

[0049] Examples 4 to 6 only varied the content of the biodegradable chelating agent. Example 4 Etching solution raw material composition: The low-corrosion and high-efficiency substrate etching solution described in this embodiment has the following components and specific dosages: 18 parts etching agent, 2.5 parts composite corrosion inhibitor system, 1.5 parts biodegradable chelating agent, 78.0 parts solvent, and an appropriate amount of pH adjuster citric acid.

[0050] The etching agent uses a sulfuric acid-hydrogen peroxide system with a sulfuric acid to hydrogen peroxide mass ratio of 5:1 (15 parts sulfuric acid to 3 parts hydrogen peroxide). This system has stable etching capabilities, and its oxidation efficiency is highly compatible with the etching requirements of copper-based substrates, enabling efficient dissolution of copper ions. The composite corrosion inhibition system consists of 2-mercapto-5-methylbenzimidazole and Sophora japonica extract in a molar ratio of 1:1.5. After alcohol extraction and chromatography purification, the Sophora japonica extract has a flavonoid active ingredient purity of 96%, meeting the application standard of no less than 95%. Its corrosion inhibition performance is verified by potentiodynamic polarization curve testing, and its corrosion inhibition efficiency on copper-based surfaces can reach over 85%. The biodegradable chelating agent is a hydroxycarboxylate salt with a mass ratio of 1:2.0 to 2-mercapto-5-methylbenzimidazole. It has excellent copper ion chelating ability and is biodegradable with no environmental residue risk. The solvent is electronic-grade deionized water that meets the GB / T11446.1 standard and has a resistivity ≥18.2 MΩ·cm, which can effectively avoid the interference of impurity ions on the stability of the etching system.

[0051] Optimization of the composite corrosion inhibition system: Quantum chemical simulations were performed at the B3LYP / 6-31G(d,p) basis set level using density functional theory, focusing on optimizing the ratio of 2-mercapto-5-methylbenzimidazole to Sophora japonica extract. By simulating the adsorption configuration, bond length, and charge distribution of these two molecules on the copper substrate, the adsorption energy and coverage under different ratios were analyzed. When the molar ratio was 1:1.5, the thiol group of 2-mercapto-5-methylbenzimidazole and the hydroxyl group of flavonoids in Sophora japonica extract could synergistically adsorb onto the active sites on the copper substrate, forming a two-site adsorption structure. At this point, the adsorption energy reached -5.1 eV, falling within the optimal stability range of -4.5 to -6.0 eV, providing a solid theoretical foundation for the subsequent formation of a dense and uniform adsorption film.

[0052] Preparation steps of etching solution: Select a 500mL three-necked reaction vessel equipped with a thermostatic jacket and a digital display stirrer, add 78.0 parts of electronic grade deionized water, turn on the stirrer and set the speed precisely to 150rpm, and simultaneously stabilize the temperature of the reaction system at 30℃±0.5℃ through the thermostatic jacket. Under continuous stirring, slowly add 1.5 parts of hydroxycarboxylate chelating agent using an intermittent feeding method to avoid excessively high local concentrations leading to incomplete dissolution. After continuous stirring for 15min, visually observe to confirm that the solution is clear, transparent and free of flocculent matter, thus obtaining the pretreatment solution. This temperature control can ensure the stability of the chelating agent molecular conformation and improve its subsequent chelating activity.

[0053] Dispersion of the composite corrosion inhibitor system: 2.5 parts of the precisely proportioned composite corrosion inhibitor system were added to the pretreatment solution at once, and a gradient stirring process was used to improve the dispersion uniformity. In the first stage, the mixture was stirred at 200 rpm for 12 minutes to allow the corrosion inhibitor components to initially diffuse in the solution and form a homogeneous suspension system. In the second stage, the stirring speed was increased to 400 rpm and stirring was continued for 25 minutes. The high shear force broke down any possible agglomerates, ensuring that 2-mercapto-5-methylbenzimidazole and Sophora japonica extract were uniformly distributed at the molecular level in the system, avoiding uneven corrosion inhibition effects caused by local concentration differences.

[0054] Preparation of the final product: The stirring speed was reduced to 250 rpm. The etching agent, composed of 15 parts sulfuric acid and 3 parts hydrogen peroxide, was slowly added dropwise along the inner wall of the reaction vessel at a rate of 1 mL / min to prevent localized overheating and decomposition of the hydrogen peroxide. After the addition was complete, stirring was continued for 20 minutes to ensure thorough mixing and reaction of all components. The pH value of the system was measured using a precision pH meter. The pH was adjusted to 4.5 by adding a 5% citric acid solution. This pH value balances etching efficiency and corrosion inhibition, remaining within a stable range of 3.5–5.5. The final product was a clear, transparent, brownish-yellow, low-corrosion, high-efficiency substrate etching solution. After standing for 24 hours, no stratification or precipitation was observed.

[0055] Results: Corrosion control and system stability: The lateral corrosion rate of the substrate was 0.18 μm / h, which was reduced by 63% compared with conventional sulfuric acid-hydrogen peroxide etching solution, as determined by the weight loss method. The copper ion tolerance of the etching solution reached 12200 ppm, and after 6 hours of continuous cycling, a trace amount of light blue copper salt precipitate appeared in the solution, and the pH fluctuation of the system was ≤0.1.

[0056] Etching efficiency and precision: The change in substrate thickness before and after etching was measured using a micrometer screw gauge. The calculated etching rate was stable at 0.9 μm / min, which is within the industrial high-efficiency range of 0.5~1.2 μm / min. The roughness Ra value of the etched circuit edge was observed by atomic force microscopy and was 0.26 μm, which meets the precision machining requirements of ≤0.3 μm for electronic circuit boards.

[0057] Application compatibility: The etched substrate surface has no obvious pinholes or pits, and the gloss reaches 85GU, making it suitable for processing copper-based substrates in automotive electronics, consumer electronics, and other applications where etching precision requirements are generally low.

[0058] Example 5 Etching solution raw material composition: The low-corrosion and high-efficiency substrate etching solution described in this embodiment has the following components and specific dosages: 18 parts etching agent, 2.5 parts composite corrosion inhibitor system, 4.0 parts biodegradable chelating agent, 75.5 parts solvent, and an appropriate amount of pH adjuster citric acid.

[0059] The etching agent is a sulfuric acid-hydrogen peroxide composite system, with a sulfuric acid to hydrogen peroxide mass ratio of 5:1 (15 parts sulfuric acid to 3 parts hydrogen peroxide). This system exhibits high selectivity in oxidation reaction at pH 4.5, etching only the copper substrate and having no corrosive effect on other metal layers on the substrate surface. The composite corrosion inhibitor system consists of 2-mercapto-5-methylbenzimidazole and Sophora japonica extract in a 1:1.5 molar ratio. The Sophora japonica extract, after column chromatography purification, has a flavonoid purity of 96%, and its corrosion inhibition efficiency reaches 88% according to polarization curve testing. The biodegradable chelating agent is a hydroxycarboxylate salt, with a mass ratio of 1:0.75 to 2-mercapto-5-methylbenzimidazole. This chelating agent can react with Cu... 2 ⁺ It forms a stable five-membered ring chelate, which can be degraded into harmless substances by microorganisms in the natural environment. The solvent is electronic-grade deionized water with a resistivity ≥18.2MΩ·cm and a heavy metal ion content ≤1ppb, ensuring the purity of the etching solution.

[0060] Optimization of the composite corrosion inhibition system: Quantum chemical calculations were performed using density functional theory, with Cu(111) surface as the adsorption substrate, to optimize the ratio of 2-mercapto-5-methylbenzimidazole to Sophora japonica extract. The calculation results showed that when the molar ratio of the two was 1:1.5, the intermolecular hydrogen bonding and π-π stacking effects were strongest. After synergistic adsorption on the copper substrate surface, the resulting adsorption film had the lowest surface energy, reaching -5.3 eV, which is within the optimal range of -4.5 to -6.0 eV, effectively inhibiting lateral corrosion of the substrate.

[0061] Preparation steps of etching solution: Pretreatment solution preparation: Add 75.5 parts of electronic-grade deionized water to a three-necked reaction vessel, turn on the constant temperature stirrer, set the speed to 150 rpm and the temperature to 30℃±0.5℃. Slowly add 4.0 parts of hydroxycarboxylate chelating agent, and continue stirring for 15 min. During this period, use a laser particle size analyzer to monitor the particle size in the solution to ensure that the chelating agent is completely dissolved and the particle size is ≤10nm, thus obtaining a clear and transparent pretreatment solution.

[0062] Dispersion of the composite corrosion inhibitor system: Add 2.5 parts of the composite corrosion inhibitor system to the pretreatment solution, stir at 200 rpm for 12 min to allow the corrosion inhibitor components to initially diffuse; then increase the speed to 400 rpm and continue stirring for 25 min. After stirring, check the uniformity of the solution to ensure that the concentration deviation of the corrosion inhibitor in different areas is ≤5%.

[0063] Preparation of finished product: Reduce the stirring speed to 250 rpm and slowly add the etching agent dropwise at a rate of 1 mL / min to prevent local overheating. After the addition is complete, stir for 20 min, adjust the pH value to 4.5 using a precision pH meter, and observe after standing for 24 h. If the solution is clear and transparent with no visible impurities, it is a qualified etching solution product.

[0064] Results: Corrosion control and system stability: The lateral corrosion rate of the substrate was 0.14 μm / h, which was 70% lower than that of conventional etching solutions; the copper ion tolerance of the etching solution reached 14200 ppm. After 10 hours of continuous cycling, the system remained clear, the pH value fluctuated ≤0.08, and no copper salt precipitate was formed.

[0065] Etching efficiency and precision: The etching rate is stable at 0.7μm / min, which is in the high-efficiency range; AFM testing shows that the edge roughness Ra value of the etched circuit is 0.20μm, the verticality of the circuit sidewall reaches 90°, and the etching precision is excellent.

[0066] Application adaptability: The substrate surface is free of any defects after etching, and it can be used for processing Cu / MoNb alloy substrate boards in fields such as semiconductor packaging and precision sensors, meeting the manufacturing needs of mid-to-high-end electronic components.

[0067] Example 6 Etching solution raw material composition: The low-corrosion and high-efficiency substrate etching solution described in this embodiment has the following components and specific dosages: 18 parts etching agent, 2.5 parts composite corrosion inhibitor system, 5.0 parts biodegradable chelating agent, 74.5 parts solvent, and an appropriate amount of pH adjuster citric acid.

[0068] The etching agent uses a sulfuric acid-hydrogen peroxide system with a sulfuric acid to hydrogen peroxide mass ratio of 5:1. It consists of 15 parts of high-purity sulfuric acid and 3 parts of food-grade hydrogen peroxide. This system has a controllable reaction rate and produces no toxic gases during etching, meeting environmental protection requirements. The composite corrosion inhibitor system is prepared by mixing 2-mercapto-5-methylbenzimidazole and Sophora japonica extract in a 1:1.5 molar ratio. The Sophora japonica extract, after purification, has a 96% purity of flavonoid active ingredients. Its adsorption kinetics on the copper-based surface conform to the Langmuir isotherm adsorption model, with a saturated adsorption capacity of 2.5 × 10⁻⁻⁻⁻⁶. 5 mol / cm 2 The biodegradable chelating agent is a hydroxycarboxylate salt with a mass ratio of 1:0.6 to 2-mercapto-5-methylbenzimidazole. The biodegradability of this chelating agent can reach 92% in the natural environment within 60 days, combining environmental friendliness with chelating performance. The solvent is electronic-grade deionized water, which complies with GB / T11446.1-2013 standard, and all impurity indicators meet the requirements for electronic chemicals.

[0069] Optimization of the composite corrosion inhibition system: Density functional theory combined with adsorption kinetics simulation was used to optimize the ratio of 2-mercapto-5-methylbenzimidazole to Sophora japonica extract. In the Cu(111) crystal plane model, when the molar ratio of the two is 1:1.5, the adsorption active sites of the two molecules are fully exposed, the coordination bond energy formed with Cu atoms reaches 280 kJ / mol, and the adsorption energy reaches -5.4 eV, which is in the optimal stable range of -4.5~-6.0 eV. The resulting adsorption film has the best density and can minimize the penetration of corrosive media.

[0070] Preparation steps of etching solution: Preparation of pretreatment solution: Add 74.5 parts of electronic grade deionized water to a three-necked reaction vessel equipped with a constant temperature stirring and temperature measuring device. Set the stirring speed to 150 rpm and control the system temperature at 30℃±0.5℃ by a constant temperature water bath. Add 5.0 parts of hydroxycarboxylate chelating agent in batches, 1.0 part per batch, with an interval of 3 min. Stir continuously for 15 min until the chelating agent is completely dissolved, the solution is clear and transparent, and there are no suspended particles.

[0071] Dispersion of the composite corrosion inhibitor system: Add 2.5 parts of the composite corrosion inhibitor system to the pretreatment solution and perform a gradient stirring program: stir at 200 rpm for 12 min for initial dispersion, and stir at 400 rpm for 25 min for deep dispersion. After stirring, use a UV-Vis spectrophotometer to detect the absorbance of the solution to ensure that the absorbance deviation of different parts is ≤2%, which proves that the corrosion inhibitor component is uniformly dispersed.

[0072] Preparation of finished product: Reduce the stirring speed to 250 rpm, slowly add the etching agent, and use a cold water bath to control the temperature during the dropwise addition to ensure that the system temperature does not exceed 35℃. After the dropwise addition is complete, continue stirring for 20 minutes to ensure that the components are fully mixed. Adjust the pH value to 4.5 with citric acid. After standing for 48 hours, observe the solution. If the solution remains brownish-yellow and clear, without layering, precipitation, or discoloration, it is a qualified finished product.

[0073] Results: Corrosion control and system stability: The lateral corrosion rate of the substrate was 0.12 μm / h, which was 73% lower than that of conventional etching solutions; the copper ion tolerance of the etching solution reached 14,800 ppm. After 12 hours of continuous cycling, the system remained stable, with the pH value maintained at around 4.5 and no copper salt precipitation.

[0074] Etching efficiency and precision: The etching rate is stable at 0.6μm / min, which is within the high-efficiency range of 0.5~1.2μm / min; AFM testing shows that the edge roughness Ra value of the etched circuit is as low as 0.19μm, the circuit size deviation is ≤±2μm, and the etching precision meets the processing standards of high-end electronic components.

[0075] Application compatibility: The etched substrate surface is smooth and flat with a gloss of 95GU, which can meet the etching requirements of Cu / MoNb alloy substrate boards in harsh scenarios such as semiconductor chip packaging and core components of intelligent equipment.

[0076] The specific content is shown in the table below: Content of composite corrosion inhibitor system (parts by weight) Content of biodegradable chelating agent (parts by weight) Example 1 1.0 3.0 Example 2 4.0 3.0 Example 3 5.0 3.0 Example 4 2.5 1.5 Example 5 2.5 4.0 Example 6 2.5 5.0 As shown in the table above, Examples 1 to 3 only changed the content of the composite corrosion inhibitor system. Under the same basic formula and preparation process, the performance change pattern was obvious only by adjusting the content of the composite corrosion inhibitor system: First, the corrosion control capability steadily improved with the increase of the corrosion inhibitor system content, the lateral corrosion rate reduction rate increased from 62% to 75%, and the copper ion tolerance increased from 12500ppm to 14500ppm. This is because more corrosion inhibitor molecules form a denser adsorption film on the substrate surface, which matches the characteristic that the corrosion inhibitor concentration is positively correlated with the corrosion inhibition efficiency. Second, the etching accuracy was continuously optimized, and the line edge roughness Ra value increased from 0. The reduction from 25μm to 0.18μm demonstrates the precise control of the etching process by the corrosion inhibition system. Thirdly, the etching rate shows a slight decreasing trend, from 0.9μm / min to 0.7μm / min, but remains within the high-efficiency range of 0.5~1.2μm / min, without affecting practical efficiency. Overall, the composite corrosion inhibition system content of 2.5~4.0 parts can achieve the optimal balance between corrosion inhibition performance and etching efficiency, 1.0 part can meet basic processing requirements, and 5.0 parts is suitable for high-end scenarios with extremely high requirements for precision and corrosion resistance, providing a flexible basis for formula adjustment for different application needs.

[0077] Examples four through six illustrate the effects of varying the content of the biodegradable chelating agent on corrosion control and system stability: The chelating agent inhibits the activity of copper ions generated during etching by chelating them. The content is positively correlated with copper ion tolerance and lateral corrosion inhibition. When the content increases from 1.5 parts to 5.0 parts, the copper ion tolerance increases from 12200 ppm to 14800 ppm, the lateral corrosion rate reduction rate increases from 63% to 73%, and the system stability time extends from 6 hours to 12 hours, confirming the core role of the chelating agent in system stability. Regarding the impact on etching efficiency and precision: The chelating agent moderately inhibits the activity of the etching agent. The content is weakly negatively correlated with the etching rate and positively correlated with etching precision. The etching rate decreased from 0.9 μm / min to 0.6 μm / min, while the Ra value decreased from 0.26 μm to 0.19 μm. This indicates that increasing the chelating agent can improve etching accuracy through a stable reaction process without sacrificing practical efficiency. The suitability varies depending on the application scenario: 1.5 parts of chelating agent are suitable for low-cost, basic precision copper-based processing; 3.0 parts represent the optimal cost-performance ratio, suitable for most conventional precision machining; 4.0~5.0 parts are suitable for Cu / MoNb alloys and high-end precision components, with 5.0 parts meeting the stringent requirements of semiconductor packaging and other demanding scenarios. In summary, adjusting the content of biodegradable chelating agent within the range of 1.0~5.0 parts allows for precise matching of etching solution performance with application scenarios, providing flexible solutions for different processing needs.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A low-corrosion, high-efficiency substrate etching solution, characterized in that, Made from the following raw materials in parts by weight: The composite corrosion inhibition system is composed of 2-mercapto-5-methylbenzimidazole and plant-derived corrosion inhibition molecules; The etching solution can form a dense adsorption film on the substrate surface, reducing the lateral corrosion rate of the substrate by more than 60%, and the copper ion tolerance in the etching solution is not less than 12,000 ppm.

2. The low-corrosion, high-efficiency substrate etching solution according to claim 1, characterized in that, The plant-derived corrosion inhibitory molecule is selected from at least one of Sophora japonica flower extract, kelp extract, and laver extract, and the main active ingredient of the plant-derived corrosion inhibitory molecule is a flavonoid or a polysaccharide.

3. The low-corrosion, high-efficiency substrate etching solution according to claim 1, characterized in that, In the composite corrosion inhibition system, the molar ratio of 2-mercapto-5-methylbenzimidazole to plant-derived corrosion inhibitor molecules is 1:0.5~3.

0.

4. The low-corrosion, high-efficiency substrate etching solution according to claim 1, characterized in that, The biodegradable chelating agent is selected from at least one of hydroxycarboxylic acid salts and organophosphates; the mass ratio of the biodegradable chelating agent to 2-mercapto-5-methylbenzimidazole is 1:0.2~2.

0.

5. The low-corrosion, high-efficiency substrate etching solution according to claim 1, characterized in that, The components, by weight, are: 10-25 parts etching agent, 0.8-5.0 parts composite corrosion inhibitor, 1.0-5.0 parts biodegradable chelating agent, and 65-88 parts solvent.

6. The low-corrosion, high-efficiency substrate etching solution according to claim 1, characterized in that, The etching agent is selected from sulfuric acid-hydrogen peroxide system and acidic copper chloride; when the etching agent is sulfuric acid-hydrogen peroxide system, the mass ratio of sulfuric acid to hydrogen peroxide is 3~8:1; when the etching agent is acidic copper chloride, its concentration is 120~180g / L.

7. The low-corrosion, high-efficiency substrate etching solution according to claim 1, characterized in that, The quantum chemical simulation was performed using density functional theory calculations. By optimizing the ratio of 2-mercapto-5-methylbenzimidazole to plant-derived corrosion inhibitors, the adsorption energy of the two on the substrate surface reached -4.5 to -6.0 eV.

8. The low-corrosion, high-efficiency substrate etching solution according to claim 1, characterized in that, The solvent is deionized water; the etching solution may also selectively contain a pH adjuster to stabilize the pH value of the etching solution within the range of 3.5 to 5.

5.

9. The low-corrosion, high-efficiency substrate etching solution according to claim 1, characterized in that, The etching rate of the etching solution is 0.5~1.2μm / min, which is suitable for etching copper-based substrates or Cu / MoNb alloy substrates. After etching, the edge roughness Ra of the substrate circuit is ≤0.3μm.

10. A method for preparing a low-corrosion, high-efficiency substrate etching solution, used to prepare the low-corrosion, high-efficiency substrate etching solution according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Place the solvent in a reaction vessel and stir at 100~200 rpm. Add the biodegradable chelating agent and control the temperature at 25~35℃. Continue stirring until the chelating agent is completely dissolved to obtain a clear pretreated solution. S2. Add the composite corrosion inhibitor system with optimized ratio by quantum chemical simulation to the pretreatment solution and use a gradient stirring process: first stir at 150~250 rpm for 10~15 min, then increase to 300~500 rpm and stir for 20~30 min to make 2-mercapto-5-methylbenzimidazole and plant-derived corrosion inhibitor molecules evenly dispersed. S3. Reduce the stirring speed to 200~300 rpm, add the etching agent, and continue stirring for 15~25 min. After the system is mixed evenly, selectively add a pH adjuster to adjust the pH value of the system to 3.5~5.5 to obtain the low-corrosion and high-efficiency substrate etching solution.

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