Environment-friendly copper etching liquid based on bio-based material and preparation method thereof

Abstract

This invention discloses an environmentally friendly copper etching solution based on bio-based materials and its preparation method. The etching solution, by weight percentage, comprises 5-20% bio-based chelating agent, 3-15% bio-based oxidant, 0.5-5% pH adjuster, 0.1-2% corrosion inhibitor, 0.05-1% surfactant, with the balance being deionized water. The bio-based chelating agent is selected from citric acid, glutamic acid, and their salts; the bio-based oxidant is selected from dehydroascorbic acid, phytic acid, and other similar substances. During preparation, the chelating agent is dissolved sequentially, the pH is adjusted to 3.0-7.0, the oxidant, corrosion inhibitor, and surfactant are added, and the solution is brought to a final volume and filtered. This invention uses renewable bio-based materials as its core, resulting in a weakly acidic to neutral etching solution with low corrosiveness to equipment. The waste liquid is easily biodegradable after use, making it environmentally friendly. Furthermore, this etching solution exhibits a suitable etching rate and a high etching factor, enabling the production of smooth etched surfaces, which meets the requirements of copper etching processes in fields such as printed circuit boards.

Description

Technical Field

[0001] This invention belongs to the field of metal surface treatment technology, specifically relating to an environmentally friendly copper etching solution based on bio-based materials and its preparation method. Background Technology

[0002] In the microelectronics manufacturing industry, copper etching is a key step in pattern transfer and is widely used in printed circuit boards (PCBs), integrated circuit (IC) packaging, and semiconductor manufacturing. The performance of the etching solution directly affects circuit accuracy, product quality, and production costs.

[0003] Currently, various copper etching solution systems are used in industry, but most rely on traditional chemical composition formulations. For example, Chinese invention patent application CN118814166A discloses a copper etching solution whose components include inorganic acids (such as hydrochloric acid), peroxides (such as hydrogen peroxide), organic acids, and conventional chelating agents, etching control agents, and surfactants. This technology aims to improve etching efficiency and extend service life, and proposes waste liquid regeneration methods such as electrolysis and membrane technology. However, its core formulation is still based on highly corrosive inorganic acids and highly oxidizing peroxides, and environmental pollution and equipment corrosion risks still exist during production, use, and waste liquid treatment.

[0004] In precision fields such as semiconductor packaging, the requirements for etching selectivity and morphology control are even higher. For example, Chinese invention patent application CN115786915A provides a copper etching solution for semiconductor packaging, using phosphoric acid as the main inorganic acid, hydrogen peroxide as the oxidant, and compounding specific mono- / dicarboxylic acids and tri- or higher carboxylic acids (such as lactic acid and citric acid) to reduce the etching rate and minimize lateral erosion of structures such as redistribution layers. However, this formulation is still based on a phosphoric acid-hydrogen peroxide system, which is highly acidic, and uses petroleum-based chelating agents such as organophosphonic acids, which have poor biodegradability, and the environmental burden has not been fundamentally solved.

[0005] Another Chinese invention patent application, CN113737183A, focuses on selective etching of copper / tungsten. Its etching solution includes hydrogen peroxide, specific fluorine / nitrogen heterocyclic chelating agents (such as 3-(2,2,2-trifluoroethoxy)pyridine-2-amine), and complexes of noble metals (such as palladium and platinum) and organic carboxylic acids as etching accelerators. While this technology achieves high etching selectivity, the formulation uses structurally complex and potentially non-biodegradable synthetic chelating agents, and introduces expensive noble metals that may pose environmental accumulation risks. Furthermore, the highly oxidizing hydrogen peroxide system presents stability and safety challenges.

[0006] Therefore, developing a novel copper etching solution that combines excellent etching performance, high environmental friendliness, low corrosivity, and renewable raw materials has become an urgent research and development direction in this field. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention discloses an environmentally friendly copper etching solution based on bio-based materials and its preparation method.

[0008] The objective of this invention is achieved through the following technical solution.

[0009] An environmentally friendly copper etching solution based on bio-based materials, comprising the following components by weight percentage: Bio-based chelating agents 5-20%; Bio-based oxidants 3-15%; pH adjuster 0.5-5%; Corrosion inhibitor 0.1-2%; Surfactant 0.05-1%; The remainder is deionized water.

[0010] The bio-based chelating agent is selected from at least one of citric acid, tartaric acid, malic acid, gluconic acid, glutamic acid, aspartic acid, and their soluble salts (such as sodium, potassium, and ammonium salts). Preferably, the bio-based chelating agent is a complex of citric acid and glutamic acid in a weight ratio of (1-3):1. This complex system can synergistically enhance the complexing ability of copper ions and the stability of the etching solution.

[0011] The bio-based oxidant is selected from at least one of dehydroascorbic acid, phytic acid, a product of glucose oxidation catalyzed by glucose oxidase, or a product of lactate oxidation catalyzed by lactate oxidase. Preferably, the bio-based oxidant is dehydroascorbic acid, which has a moderate oxidation potential and can effectively control the etching process and avoid over-etching.

[0012] The pH adjuster is used to adjust the pH of the etching solution to a weakly acidic to neutral range of 3.0-7.0, preferably 4.0-6.0, to reduce corrosiveness and maintain the activity of each component. The pH adjuster is selected from at least one of sodium hydroxide, potassium hydroxide, ammonia, sodium bicarbonate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate, preferably biologically derived ammonia or sodium bicarbonate.

[0013] The corrosion inhibitor is selected from at least one of phytic acid, tannic acid, gallic acid, and lignin sulfonate. Phytic acid is preferred, as its molecules contain multiple phosphate groups, which can form a dense protective film on the copper surface to inhibit lateral corrosion and corrosion in non-patterned areas.

[0014] The surfactant is selected from at least one of sucrose fatty acid esters, polyglycerol fatty acid esters, and alkyl glycosides. Alkyl glycosides (APG) are preferred, as they have good biodegradability and excellent wetting properties, which helps improve etching uniformity.

[0015] In a preferred embodiment, the etching solution comprises, by weight percentage: 5-15% citric acid, 2-8% glutamic acid, 3-10% dehydroascorbic acid, 0.5-3% pH adjuster (for adjusting pH to 4.5-5.5), 0.1-1% phytic acid, 0.05-0.5% alkyl glycoside, and the balance being deionized water. More preferably, the weight ratio of citric acid to glutamic acid is 2:1, and the pH of the etching solution is 5.0.

[0016] This invention also provides a method for preparing the above-mentioned environmentally friendly copper etching solution, comprising the following steps: (1) Under stirring conditions, the bio-based chelating agent is added to a portion of deionized water and stirred until completely dissolved to obtain a first solution; (2) Add the pH adjuster to the first solution, stir evenly, and adjust the pH value of the solution to 3.0-7.0 (preferably 4.0-6.0) to obtain the second solution; (3) Under stirring conditions, the bio-based oxidant is added to the second solution and stirred until completely dissolved to obtain the third solution; (4) The corrosion inhibitor and the surfactant are added to the third solution in sequence, and each component is stirred until completely dissolved and mixed evenly after addition; (5) Use deionized water to adjust the volume of the mixture obtained in step 4 to the target volume, stir evenly, and then filter (preferably using a 0.1-0.45μm filter membrane) to obtain the environmentally friendly copper etching solution.

[0017] Furthermore, this invention also claims protection for the application of the bio-based copper etching solution in copper or copper alloy etching processes during the manufacturing of printed circuit boards or integrated circuit chips. The etching process is preferably performed at 40-70°C, and the etching method can be spray etching or immersion etching.

[0018] Compared with existing technologies, the present invention has the following advantages and beneficial effects: The etching solution of this invention uses renewable bio-based materials as its core, which has good biodegradability, significantly reducing environmental impact and the difficulty of wastewater treatment; its mild system, which is weakly acidic to neutral, has low corrosiveness to production equipment, extending the equipment's lifespan; at the same time, through the synergistic effect of each component, it achieves excellent etching rate, high etching factor, and smooth etching surface, which can meet the requirements of precision pattern processing. Attached Figure Description

[0019] Figure 1 The preparation process of the environmentally friendly copper etching solution described in this invention is as follows. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention. All raw materials used in the embodiments of this invention are commercially available.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0022] Example 1 An environmentally friendly copper etching solution based on bio-based materials, comprising the following components by weight percentage: Citric acid 8.0% Glutamic acid 4.0% Dehydroascorbic acid 5.0% Sodium bicarbonate 1.2% (used to adjust the final pH of the etching solution to 5.0) Phytic acid 0.5% Alkyl glycoside (APG0810) 0.2% Deionized water balance.

[0023] Preparation methods, such as Figure 1 As shown, it includes the following steps: (1) Dissolving chelating agent: Under stirring conditions, add the prescribed amount of citric acid and glutamic acid to deionized water accounting for 60% of the total water volume, and stir at 25°C for 40 minutes until completely dissolved.

[0024] (2) Adjust the pH value: Add the prescribed amount of sodium bicarbonate to the solution obtained in step (1), stir for 20 minutes until it is evenly dissolved, and then finely adjust it with 10% citric acid solution or 10% sodium bicarbonate solution to stabilize the pH value of the solution at 5.0±0.1.

[0025] (3) Add oxidant: Under continuous stirring, slowly add the amount of dehydroascorbic acid in the formula and continue stirring for 30 minutes until it is completely dissolved.

[0026] (4) Add auxiliary agents: Add the prescribed amounts of phytic acid and alkyl glycosides to the solution in sequence, stirring for 15 minutes after each addition until completely dissolved and mixed evenly.

[0027] (5) Volume adjustment and filtration: The above solution is adjusted to the target total weight with the remaining deionized water, stirred evenly, and then filtered through 1μm and 0.22μm filter cartridges in sequence to obtain the etching solution.

[0028] Example 2 An environmentally friendly copper etching solution based on bio-based materials, comprising the following components by weight percentage: Gluconic acid 15.0% Dehydroascorbic acid 4.0% Ammonia solution (25% concentration) 0.6%: Adjust the final pH of the etching solution to 6.0. Tannic acid 1.0% Sucrose fatty acid esters (SE-15) 0.1% Deionized water balance.

[0029] The preparation method includes the following steps: (1) Dissolving the chelating agent: Under stirring conditions, add the amount of gluconic acid in the formula to deionized water accounting for 65% of the total water volume, and stir at 30°C for 30 minutes until completely dissolved.

[0030] (2) Adjust pH value: Add the prescribed amount of ammonia water to the solution obtained in step (1), stir for 15 minutes, measure and adjust the pH value of the solution to 6.0±0.1.

[0031] (3) Add oxidant: Under continuous stirring, slowly add the amount of dehydroascorbic acid in the formula and continue stirring for 25 minutes until it is completely dissolved.

[0032] (4) Add auxiliary agents: Add the prescribed amounts of tannic acid and sucrose fatty acid ester to the solution in sequence, stirring for 10 minutes after each addition until completely dissolved and mixed evenly.

[0033] (5) Volume adjustment and filtration: The above solution is adjusted to volume with the remaining deionized water, stirred evenly, and then filtered through a 0.45μm filter membrane to obtain the etching solution.

[0034] Example 3 An environmentally friendly copper etching solution based on bio-based materials, comprising the following components by weight percentage: Malic acid 10.0% Tartaric acid 5.0% Phytic acid 8.0%: In this embodiment, phytic acid also acts as an oxidant. Potassium dihydrogen phosphate 1.0%: Adjusts the final pH of the etching solution to 4.0. Gallic acid 0.8% Polyglycerol fatty acid ester (PGFE) 0.05% Deionized water balance.

[0035] The preparation method includes the following steps: (1) Dissolving chelating agent: Under stirring conditions, add the formula amount of malic acid and tartaric acid to deionized water accounting for 70% of the total water volume, and stir at room temperature for 35 minutes until completely dissolved.

[0036] (2) Adjust the pH value: Add the prescribed amount of potassium dihydrogen phosphate to the solution obtained in step (1), stir for 20 minutes until it is evenly dissolved, and then finely adjust it with dilute phosphoric acid or potassium hydroxide solution to stabilize the pH value of the solution at 4.0±0.1.

[0037] (3) Add oxidant: Under continuous stirring, slowly add the amount of phytic acid in the formula and continue stirring for 40 minutes until it is completely dissolved and mixed evenly.

[0038] (4) Add auxiliary agents: Add the prescribed amounts of gallic acid and polyglycerol fatty acid ester to the solution in sequence, stirring for 15 minutes after each addition until completely dissolved and mixed evenly.

[0039] (5) Volume adjustment and filtration: Use the remaining deionized water to adjust the volume of the above solution to the target total weight, stir evenly, and then filter through a 0.22μm filter membrane to obtain the etching solution.

[0040] Example 4 An environmentally friendly copper etching solution based on bio-based materials, comprising the following components by weight percentage: Citric acid 5.0% Aspartic acid 3.0% Gluconic acid 2.0% The product of lactate oxidase-catalyzed lactate oxidation (based on effective oxidizing component) is 3.0%. Potassium hydroxide 0.8%: Used to adjust the final pH of the etching solution to 7.0. Sodium lignosulfonate 1.5% Alkyl glycoside (APG1214) 0.5% Deionized water balance.

[0041] The preparation method includes the following steps: (1) Dissolving chelating agent: Under stirring conditions, add the formula amount of citric acid, aspartic acid and gluconic acid to deionized water accounting for 55% of the total water volume, and stir at 28°C for 45 minutes until completely dissolved.

[0042] (2) Adjust pH value: Add the prescribed amount of potassium hydroxide to the solution obtained in step (1), stir for 25 minutes until it is evenly dissolved, and measure and adjust the pH value of the solution to 7.0±0.1.

[0043] (3) Add oxidant: Under continuous stirring, slowly add the product of lactic acid oxidation catalyzed by lactic acid oxidase in the formula amount, and continue stirring for 30 minutes until it is completely dissolved and mixed evenly.

[0044] (4) Add auxiliary agents: Add sodium lignosulfonate and alkyl glycosides in the formula amount to the solution in sequence. Stir for 20 minutes after each addition until completely dissolved and mixed evenly.

[0045] (5) Volume adjustment and filtration: The above solution is adjusted to volume with the remaining deionized water, stirred evenly, and then filtered through 5μm and 0.45μm filter bags in sequence to obtain the etching solution.

[0046] Comparative Example 1 An etching solution, the composition of which, compared to Example 1, does not contain a bio-based oxidant (dehydroascorbic acid). The composition, by weight percentage, is as follows: Citric acid 8.0% Glutamic acid 4.0% Sodium bicarbonate 1.2% Phytic acid 0.5% Alkyl glycoside (APG0810) 0.2% Deionized water balance.

[0047] The preparation method is the same as in Example 1, but step (3) of adding oxidant is omitted, and the rest of the steps are the same.

[0048] Comparative Example 2 An etching solution, the composition of which, compared with Example 1, does not contain the corrosion inhibitor phytic acid. The composition, by weight percentage, is as follows: Citric acid 8.0% Glutamic acid 4.0% Dehydroascorbic acid 5.0% Sodium bicarbonate 1.2% Alkyl glycoside (APG0810) 0.2% Deionized water balance.

[0049] The preparation method is the same as in Example 1, but only alkyl glycosides are added in step (4), and phytic acid is not added.

[0050] Comparative Example 3 An etching solution using conventional chemical components. Its composition, by weight percentage, is as follows: Hydrogen peroxide (30%) 10.0% Phosphoric acid 5.0% Hydroxyethylenediaminetriacetic acid (HEDTA) 4.0% Benzotriazole (BTA) 0.3% Fatty alcohol polyoxyethylene ether (AEO-9) 0.1% Deionized water balance The pH value of this formula is approximately 1.5.

[0051] Preparation method: Following the steps in Example 1, HEDTA was dissolved in water, phosphoric acid and hydrogen peroxide were added to adjust the system, and finally BTA and AEO-9 were added, followed by volume adjustment and filtration.

[0052] Comparative Example 4 An etching solution with the same composition as in Example 1, but with the pH value adjusted to 2.0 (outside the scope of this invention).

[0053] Citric acid 8.0% Glutamic acid 4.0% Dehydroascorbic acid 5.0% Concentrated hydrochloric acid (approximately 0.9%): Used to adjust the final pH of the etching solution to 2.0. Phytic acid 0.5% Alkyl glycoside (APG0810) 0.2% Deionized water balance.

[0054] The preparation method is the same as in Example 1, but in step (2), concentrated hydrochloric acid is used to adjust the pH of the solution to 2.0 ± 0.1.

[0055] Comparative Example 5 An etching solution, compared to Example 1, uses a surfactant that is not preferred and exceeds the content range of the present invention. The composition, by weight percentage, is as follows: Citric acid 8.0% Glutamic acid 4.0% Dehydroascorbic acid 5.0% Sodium bicarbonate 1.2% Phytic acid 0.5% Sodium dodecylbenzenesulfonate 0.05% Deionized water balance.

[0056] The preparation method is the same as in Example 1, except that sodium dodecylbenzenesulfonate is used instead of alkyl glycoside in step (4).

[0057] Test Example 1: Comprehensive comparison test of etching performance Objective: To verify the comprehensive performance of the etching solution in the embodiments of the present invention in terms of etching rate, etching factor and surface morphology, and to investigate the effects of different component deficiencies or pH deviations on performance.

[0058] method: Samples: Etching solutions prepared in Examples 1, 2, 3 and Comparative Examples 1-5.

[0059] Substrate: A standard FR-4 copper clad laminate (copper layer thickness 35±1μm) is selected, with test patterns pre-etched with a line width / spacing of 50 / 50 μm.

[0060] Etching conditions: A constant temperature spray etching machine was used, with the etching temperature set at 60.0±0.5℃, the spray pressure at 1.5 bar, and the conveying speed at 1.2 m / min.

[0061] Testing indicators: Etching rate: Calculated by measuring the mass loss per unit area of ​​the copper-clad laminate before and after etching, based on the density of copper. Each group was tested in parallel for 5 times, and the average value was taken.

[0062] Etching Factor: After etching, the top linewidth (A) and bottom linewidth (B), as well as the copper layer thickness (T), are measured using a laser confocal microscope. The etching factor (EF) is calculated using the formula EF = 2T / (A - B). Three points are measured for each line, and five lines are measured for each sample. The average value is then taken.

[0063] The results are shown in Table 1.

[0064]

[0065] Conclusions: Examples 1-3 of this invention achieved good etching rates and high etching factors (≥3.0) under weakly acidic to near-neutral conditions, indicating excellent vertical etching capability and surface quality. Comparative Example 1, lacking a bio-based oxidant, failed to effectively carry out the etching reaction, demonstrating its necessity. Comparative Example 2, lacking a bio-based corrosion inhibitor, resulted in uncontrolled lateral etching and a significant decrease in the etching factor, highlighting its crucial role in protecting the circuit sidewalls. Comparative Example 3 (conventional acidic etching solution) showed a high etching rate but a low etching factor and poor surface quality. Comparative Example 4 shows that excessively low pH values ​​(strong acidity) degrade the etching morphology. Comparative Example 5 demonstrates that non-bio-based or non-preferred types of surfactants cannot achieve the synergistic effect of the bio-based surfactants (such as alkyl glycosides) of this invention in improving wettability and uniformity. The synergistic effect of multiple components is crucial for achieving high-precision, high-quality etching.

[0066] Test Example 2 Environmental friendliness assessment test Objective: To evaluate the biodegradability of the etching solution and its simulated waste liquid of the present invention, and to compare its environmental impact with that of traditional etching solutions.

[0067] method: Sample preparation: Stock solution: Take the etching solution stock solution from Example 1, Example 3 and Comparative Example 3.

[0068] Simulated waste liquid: The above etching solution was reacted with copper powder at 60°C until the copper ion concentration reached 10 g / L, and then filtered to obtain simulated waste liquid.

[0069] Testing indicators: Chemical oxygen demand (COD): Determined using rapid digestion spectrophotometry.

[0070] Five-day biochemical oxygen demand (BOD5): The dilution inoculation method was used to determine the inoculation solution, which was a mixture of activated sludge.

[0071] Biodegradability assessment: Calculate the BOD5 / COD ratio. A ratio >0.3 indicates good biodegradability, and a ratio >0.45 indicates easy biodegradability.

[0072] Heavy metal ions (Cu) 2+ Content: The total copper concentration in the simulated waste liquid was determined by inductively coupled plasma atomic emission spectrometry.

[0073] The results are shown in Table 2.

[0074]

[0075] Conclusion: The BOD5 / COD ratios of both the raw etching solution and the simulated waste liquid in the embodiments of this invention are greater than 0.4, indicating that their organic components are mainly biodegradable substances. In contrast, the BOD5 / COD ratio of the traditional etching solution (Comparative Example 3) is extremely low (<0.10), classifying it as recalcitrant wastewater. This demonstrates that the bio-based raw material system used in this invention significantly improves the overall biodegradability of the etching solution, making its waste liquid more suitable for purification using conventional biological treatment methods (such as activated sludge processes). This effectively reduces the difficulty and cost of subsequent wastewater treatment, reflecting outstanding environmental friendliness.

[0076] Test Example 3 Corrosion testing of equipment materials Objective: To evaluate the corrosivity of the etching solution of this invention to commonly used metal materials in microelectronics manufacturing and to verify its low corrosion characteristics.

[0077] method: Test pieces and samples: 304 stainless steel, 6061 aluminum alloy and copper test pieces (size: 50 mm × 25 mm × 2 mm) were selected. The etching solution samples were Example 1 (pH=5.0), Example 2 (pH=6.0) and Comparative Example 3 (pH≈1.5) and Comparative Example 4 (pH=2.0).

[0078] Test conditions: The test pieces were completely immersed in the etching solutions and placed in a constant temperature water bath at 50.0±2.0℃ for 72 hours. Three replicates were set up for each group.

[0079] Testing indicators: Corrosion rate: After immersion, remove the test piece, remove corrosion products according to national standard GB / T 16545-2015, dry it, and weigh it accurately. Calculate the annual corrosion rate (unit: mm / a) based on the weight loss.

[0080] The results are shown in Table 3.

[0081]

[0082] *Note: In Comparative Example 3, the aluminum and copper specimens showed severe overall corrosion, with some areas exhibiting perforation.

[0083] Conclusion: The etching solutions (pH 5.0-6.0) of Examples 1 and 2 of this invention exhibit extremely low corrosion rates (<0.01 mm / a) on 304 stainless steel and 6061 aluminum alloy, indicating that they cause almost no corrosion to stainless steel or aluminum alloy components such as etching tanks, pipes, and pump bodies. Even after prolonged immersion at relatively high temperatures (50°C), the corrosion rate remains far below the industry-standard safe tolerance range for equipment (typically <0.1 mm / a).

[0084] Test Example 4 Actual PCB circuit board application testing Objective: To verify the pattern transfer accuracy and reliability of the etching solution of this invention in actual PCB manufacturing processes.

[0085] method: Substrate and process: A 4-layer FR-4 PCB inner core board with a copper thickness of 18μm was selected. Dry film was applied and exposed and developed to form dense circuit patterns (minimum line width / spacing: 75 / 75 μm).

[0086] Etching Process: On a mass-production horizontal conveyor etching line, etching was performed using the etching solution from Example 1 and a commercially available acidic copper chloride etching solution (conventional process, used as a control group). Process parameters were optimized based on the characteristics of the etching solutions. For example, in Example 1: solution temperature 55°C, conveyor speed 1.5 m / min; in the control group: solution temperature 50°C, conveyor speed 2.0 m / min. The etching endpoint was controlled to ensure complete removal of copper.

[0087] Testing and Evaluation: Dimensional accuracy: The etched board surface is scanned using an automated optical inspection (AOI) device to statistically analyze the linewidth deviation (the difference between the actual linewidth and the design value).

[0088] Yield assessment: Count the number of defects such as open circuits, short circuits, gaps, and burrs, and calculate the first pass yield.

[0089] Lateral etching measurement: Under a metallographic microscope, a cross-section of the circuit is fabricated, and the lateral etching is measured.

[0090] Surface cleanliness: Observe whether there are obvious residues or discoloration on the etched board surface.

[0091] The results are shown in Table 4.

[0092]

[0093] Conclusion: In a real-world PCB manufacturing environment, the etching solution of Example 1 of this invention exhibits excellent overall performance. It offers higher linewidth control precision and reduces lateral etching by approximately 44%, significantly improving dimensional consistency and electrical reliability, ultimately resulting in a higher first-pass yield. Furthermore, its mild pH environment and bio-based components make the working environment more environmentally friendly (with less irritating odor), and the resulting board surface cleanliness may reduce subsequent cleaning requirements. This test confirms that the etching solution of this invention not only meets environmental protection requirements but also possesses the feasibility and performance advantages of replacing traditional etching solutions in the actual production of high-precision PCBs.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any changes and modifications made to the embodiments described herein based on the innovative concept of the present invention, or equivalent structural or procedural transformations made using the content of the present invention specification, directly or indirectly applying the above technical solutions to other related technical fields, are all included within the scope of protection of the present invention patent.

Claims

1. An environmentally friendly copper etching solution based on bio-based materials, characterized in that, By weight percentage, it consists of the following components: Bio-based chelating agents 5-20%; Bio-based oxidants 3-15%; pH adjuster 0.5-5%; Corrosion inhibitor 0.1-2%; Surfactant 0.05-1%; The remainder is deionized water; The bio-based chelating agent is a compound of citric acid and glutamic acid, wherein the weight ratio of citric acid to glutamic acid is (1-3):1; The bio-based oxidant is dehydroascorbic acid; The etching solution has a pH value of 4.0-6.0, an etching rate of 1-5 μm / min, and an etching factor of not less than 3.

0. The surfactant is selected from at least one of sucrose fatty acid esters, polyglycerol fatty acid esters, and alkyl glycosides.

2. The environmentally friendly copper etching solution according to claim 1, characterized in that, The pH adjuster is selected from at least one of ammonia, sodium bicarbonate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate.

3. The environmentally friendly copper etching solution according to claim 1, characterized in that, The corrosion inhibitor is selected from at least one of phytic acid, tannic acid, gallic acid, and lignin sulfonate.

4. The environmentally friendly copper etching solution according to claim 1, characterized in that, By weight percentage, it consists of the following components: Citric acid 5-15%; Glutamic acid 2-8%; Dehydroascorbic acid 3-10%; pH adjuster 0.5-3%, the pH adjuster being used to adjust the pH value of the etching solution to 4.5-5.5; Phytic acid 0.1-1%; Alkyl glycosides 0.05-0.5%; The remainder is deionized water.

5. The method for preparing the environmentally friendly copper etching solution based on bio-based materials as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Under stirring conditions, the bio-based chelating agent is added to a portion of deionized water and stirred until completely dissolved to obtain a first solution; (2) Add the pH adjuster to the first solution, stir evenly, and adjust the pH value of the solution to 4.0-6.0 to obtain the second solution; (3) Under stirring conditions, the bio-based oxidant is added to the second solution and stirred until completely dissolved to obtain the third solution; (4) The corrosion inhibitor and the surfactant are added to the third solution in sequence, and each component is stirred until completely dissolved and mixed evenly after addition; (5) Use deionized water to adjust the volume of the mixture obtained in step (4) to the target volume, stir evenly, and then filter to obtain the environmentally friendly copper etching solution.

6. The preparation method according to claim 5, characterized in that, In step (5), the filtration is performed using a filter membrane with a pore size of 0.1-0.45 μm.

7. The application of the environmentally friendly copper etching solution based on bio-based materials as described in any one of claims 1-4 in the copper or copper alloy etching process during the manufacturing of printed circuit boards or integrated circuit chips.

8. The application according to claim 7, characterized in that, The etching process is carried out at 40-70℃, and the etching method is spray etching or immersion etching.

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