Surface copper protection treatment process for environment-friendly multilayer board

Abstract

The invention relates to the technical field of circuit board processing, in particular to an environment-friendly multilayer board surface copper protection treatment process. The invention relates to an environment-friendly multilayer board surface copper protection treatment process, which comprises the following steps of circular spraying oil removal, three-stage pressure water washing, suction drying, spraying micro-etching, three-stage pressure water washing, suction drying, copper protection, three-stage pressure water washing, suction drying, drying and blowing cooling, comprising the following components in mass concentration: 8-10g / L of sodium silicate, 1.1-1.4 g / L of a composite surfactant and 0.5-0.7 g / L of sodium polyepoxysuccinate, the circulating spraying oil removal pressure of the circulating spraying oil removal is 1.4 Kg / cm < 2 > to 1.6 Kg / cm < 2 >. The surface copper protection treatment process for the environment-friendly multilayer board is excellent in cleaning efficiency, protection performance, economical efficiency and environment-friendly safety, and is a novel process with a great application prospect.

Description

Technical Field

[0001] This application relates to the technical field of printed circuit board processing, and in particular to an environmentally friendly multi-layer board surface copper protection treatment process. Background Art

[0002] A printed circuit board (FPC) belongs to an electronic component, which is a support for electronic components and a provider of electrical connections. It has the characteristics of light weight, good consistency, small size, high reliability, and easy standardization. Currently, it has been widely used in high-tech electronic product fields such as digital products, aerospace, smart home appliances, communications, and medical treatment. As a basic component of electronic products, the performance of printed circuit boards plays a crucial role in the service life of electronic products. In recent years, with the development of electronic products towards multi-functionalization, miniaturization, high density, and high efficiency, higher requirements have also been put forward for the preparation refinement and application reliability of printed circuit boards.

[0003] OSP is a process that meets the requirements of the RoHS directive for the surface treatment of copper foils on printed circuit boards (PCBs). OSP is the abbreviation of Organic Solderability Preservatives, which is translated into Chinese as organic solder mask, also known as copper protection agent, and is also called Preflux in English. Simply put, OSP is to grow an organic film on the clean bare copper surface by chemical means. This film has anti-oxidation, heat shock resistance, and moisture resistance, and is used to protect the copper surface from rusting (oxidation or sulfidation, etc.) any further in the normal environment; but in the subsequent high-temperature soldering, this protective film must be easily and quickly removed by the soldering flux, so that the exposed clean copper surface can be immediately combined with the molten solder to form a firm solder joint in a very short time.

[0004] Currently, for the environmentally friendly multi-layer board surface copper protection treatment process, due to foreign matters and oil stains remaining on the surface of the product in the previous process and the acidic degreasing not being able to completely remove them, after the OSP film reacts with the foreign matters and oil stains on the board surface, the PI surface shows different colors, and in severe cases, it shows colorful colors, resulting in frequent rework of the product, affecting the output and product quality. At the same time, the current OSP film is also prone to oxidation at high temperatures and cannot form a dense organic solderable protective layer on the copper surface. Summary of the Invention

[0005] The purpose of this application is to provide an environmentally friendly multi-layer board surface copper protection treatment process in view of the deficiencies of the current technology. The environmentally friendly multi-layer board surface copper protection treatment process of this application can not only simply and efficiently remove oil stains and form a dense protective layer, improve the anti-oxidation performance and heat shock resistance of the environmentally friendly multi-layer board, but also has a 100% solderability. The environmentally friendly multi-layer board surface copper protection treatment process of this application is simple, easy to operate, low in cost, and environmentally friendly and safe.

[0006] This application provides an environmental protection multi-layer board surface copper protection treatment process, adopting the following technical solutions: An environmental protection multi-layer board surface copper protection treatment process includes the following steps: circulating spray degreasing → three-stage pressure water washing → drying → spray micro-etching → three-stage pressure water washing → drying → copper protection → three-stage pressure water washing → drying → drying → air cooling. Among them, the circulating spray degreasing includes components with the following mass concentrations: sodium silicate 8-10g / L, composite surfactant 1.1-1.4g / L, and polyepoxysuccinic acid sodium 0.5-0.7g / L.

[0007] By adopting the above technical solutions, this environmental protection multi-layer board surface copper protection treatment process realizes efficient oil stain removal, formation of a copper surface protection layer, and performance improvement through a series of steps and combinations of specific chemical components. Circulating spray degreasing: In this step, a solution containing sodium silicate, composite surfactant, and polyepoxysuccinic acid sodium is used for spraying under a pressure of 1.1-1.4 kg / cm 2 . Sodium silicate mainly plays a saponification role to decompose grease; the composite surfactant reduces the surface tension of water to help penetrate and emulsify oil stains; polyepoxysuccinic acid sodium provides additional chelating effects to further decompose and suspend oil stain particles. These components work together to remove oil stains quickly and efficiently. Three-stage pressure water washing: Through multiple high-pressure water washings, the residual degreasing agent and oil stains on the surface are thoroughly removed to ensure the effective progress of subsequent treatment steps. Drying: Remove the surface moisture to prepare for the next treatment step. Spray micro-etching: Use specific chemical reagents to slightly etch the copper surface to increase its roughness, thereby improving the adhesion between the protection layer and the copper layer. This step can also effectively inhibit the oxidation and discoloration of the copper surface and maintain the purity of the copper. Three-stage pressure water washing and drying again: Repeat the cleaning and drying process to ensure that the copper surface after micro-etching is clean and residue-free. Copper protection: Apply a layer of protective material to form a dense protection layer to improve the antioxidant performance and heat shock resistance of the environmental protection multi-layer board. Drying and air cooling: Through drying and cooling treatments, the protection layer is firmly attached to the copper surface. Synergy between degreasing and micro-etching: The degreasing step creates a clean basis for micro-etching, enabling micro-etching to be carried out more effectively, while micro-etching increases the roughness of the copper surface and enhances the adhesion of the protection layer. Formation of the protection layer: The copper protection step forms a dense protection layer on the clean and pretreated copper surface. This layer not only prevents oxidation but also improves the heat shock resistance. Optimization of the overall process: The entire process flow is designed to be simple and efficient, with each step closely coordinated to ensure the efficient completion of the whole process from cleaning to protection, while maintaining low cost and environmental friendliness. In summary, this environmental protection multi-layer board surface copper protection treatment process realizes efficient oil stain removal, copper surface protection, and performance improvement through a fine chemical formula and a reasonable process flow design, fully reflecting the synergistic effects between each step and component.

[0008] Preferably, the temperature of the circulating spray degreasing is 20 - 30°C, the time is 30 - 60 seconds, and the pressure of the circulating spray degreasing is 1.1 - 1.4 Kg / cm 2 .

[0009] Preferably, the composite surfactant is composed of isooctanol polyoxypropylene polyoxyethylene ether and alkylphenol polyoxyethylene (4) ether in a mass ratio of 4:1 - 2.

[0010] By adopting the above technical solutions, isooctanol polyoxypropylene polyoxyethylene ether: As a non-ionic surfactant, isooctanol polyoxypropylene polyoxyethylene ether has good wettability and permeability, can rapidly reduce the surface tension of water, make water more easily penetrate between the oil stain and the board surface, thus effectively emulsifying and dispersing the oil stain. It can also enhance the stability of the cleaning solution and prevent the oil stain from redepositing on the board surface. Alkylphenol polyoxyethylene (4) ether is also a non-ionic surfactant, which has strong detergency and emulsifying ability, and can further help decompose and remove stubborn oil stains. In addition, it can improve the hard water resistance of the cleaning solution and reduce the influence of calcium, magnesium and other ions in water on the cleaning effect. When these two surfactants are mixed and used in a specific ratio (such as a mass ratio of 4:1 - 2), a synergistic effect will occur between them, enhancing each other's performance. The good wettability and permeability of isooctanol polyoxypropylene polyoxyethylene ether are combined with the strong detergency and emulsifying ability of alkylphenol polyoxyethylene (4) ether, making the circulating spray degreasing process more efficient and able to more thoroughly remove the oil stain on the board surface. At the same time, this synergistic effect also helps to improve the overall stability and hard water resistance of the cleaning solution, ensuring the durability and consistency of the cleaning effect. In summary, isooctanol polyoxypropylene polyoxyethylene ether and alkylphenol polyoxyethylene (4) ether in the composite surfactant jointly enhance the effect of circulating spray degreasing through their respective characteristics and the synergistic effect between them, laying a solid foundation for the successful implementation of the copper protection treatment process on the surface of environmental protection multi-layer boards.

[0011] Preferably, the conductivity of the pure water inlet of the three-stage pressure water washing is ≤20 μs / cm, and the pressure of the three-stage pressure water washing is 1.0 - 1.5 Kg / cm 2 , the process of suction drying is to use a PVA foaming water-absorbing roller to suck dry the water on the surface of the multi-layer board; the process of drying is to use hot air at 60 - 80°C for drying; the process of blowing and cooling is to use a cooling fan to cool to below 30°C.

[0012] Preferably, the micro-etching treatment liquid for spray micro-etching comprises components with the following mass concentrations: sulfuric acid 6 - 10 g / L, hydrogen peroxide 6 - 12 g / L, hydroxyethyl ethylenediaminetriacetic acid 1 - 2 g / L, corrosion inhibitor 2 - 4 g / L, stabilizer 1 - 3 g / L, surfactant 5 - 8 g / L, temperature 20 - 30 °C, time 10 - 30 seconds, spray pressure 1.1 - 1.4 Kg / cm 2 .

[0013] By adopting the above technical solution, sulfuric acid, as a strong acid, plays a major etching role in the micro-etching process, can effectively remove the oxides and other impurities on the copper surface, and expose a fresh metal layer on the copper surface. The concentration and temperature of sulfuric acid need to be precisely controlled to ensure a moderate etching rate and avoid damage to the copper layer caused by over-etching. Hydrogen peroxide has oxidizing properties and can cooperate with sulfuric acid during micro-etching to accelerate the removal process of the oxides on the copper surface. At the same time, hydrogen peroxide can also act as a cleaner to help remove the organic pollutants on the copper surface. As a chelating agent, hydroxyethyl ethylenediaminetriacetic acid can form a stable complex with copper ions, thereby inhibiting the free movement of copper ions in the solution and reducing the further oxidation and discoloration of the copper surface. This helps to maintain the uniformity and stability of the copper surface after micro-etching. The role of the corrosion inhibitor is to slow down or prevent the over-etching of sulfuric acid on the copper layer, ensuring that the micro-etching process only occurs in specific areas of the copper surface without damaging the entire copper layer. By adding a corrosion inhibitor, the micro-etching depth and rate can be more precisely controlled. The stabilizer is used to maintain the stability of the micro-etching treatment liquid and prevent unnecessary changes in the chemical components in the solution during the reaction process. It helps to ensure the consistency and predictability of the micro-etching process. The surfactant can reduce the surface tension of the liquid, making the micro-etching treatment liquid more easily penetrate into the surface and tiny pores of the copper layer. This helps to improve the micro-etching efficiency and uniformity, ensuring that the entire copper surface can be fully treated. In summary, each component in the spray micro-etching treatment liquid, through their respective characteristics and their synergistic effects, jointly realizes an efficient and stable micro-etching process. Sulfuric acid and hydrogen peroxide cooperate to remove the oxides and impurities on the copper surface, hydroxyethyl ethylenediaminetriacetic acid, as a chelating agent, inhibits the free movement of copper ions, the corrosion inhibitor controls the micro-etching depth and rate, the stabilizer maintains the solution stability, and the surfactant promotes the penetration and uniform distribution of the treatment liquid. The synergistic effects of these components enable the spray micro-etching step to effectively enhance the adhesion and overall performance of the copper protection layer on the surface of the environmentally friendly multi-layer board.

[0014] Preferably, the corrosion inhibitor is composed of 1-hydroxybenzotriazole and dibenzotriazole in a mass ratio of 5:3; the stabilizer is ethylenediamine disuccinic acid; the surfactant is composed of isomeric tridecyl alcohol polyoxyethylene ether and isooctyl alcohol polyoxypropylene polyoxyethylene ether in a mass fraction ratio of 1:1.

[0015] Preferably, the copper protection liquid comprises components with the following mass concentrations: composite film-forming agent 12 - 16 g / L, lactic acid 60 - 70 g / L, lauric acid 0.5 - 0.8 g / L, composite surfactant 0.7 - 0.9 g / L, EDTA 0.5 - 0.8 g / L; the preparation method of the protection liquid is to weigh the raw materials according to the formula ratio, mix them, and stir.

[0016] By adopting the above technical solution, the composite film-forming agent is the main component in the protection liquid, and a uniform and dense protective film is formed on the copper surface. This protective film can effectively isolate oxygen and moisture in the air, preventing the oxidation and corrosion of the copper layer. At the same time, the composite film-forming agent can also enhance the mechanical strength of the protective layer, improving the wear resistance and durability of the board. Lactic acid, as an organic acid, can play a role in adjusting the pH value in the protection liquid, ensuring the stability and effectiveness of the protection liquid. At the same time, lactic acid can also undergo a slight chemical reaction with the copper surface, helping to clean the copper surface and providing better conditions for the adhesion of the film-forming agent. Lauric acid is a fatty acid, which is mainly used as a lubricant and dispersant in the protection liquid. Lauric acid can help the protection liquid better wet the copper surface, making the film-forming agent more evenly distributed on the copper layer. At the same time, it can also reduce the bubbles and agglomeration phenomena in the protection liquid, improving the coating effect of the protection liquid. The composite surfactant is composed of a variety of surfactants compounded, with excellent wettability and permeability. In the protection liquid, it can reduce the surface tension of the liquid, making the protection liquid easier to penetrate into the surface and micro-pores of the copper layer, which helps to improve the uniformity and adhesion of the protective layer, ensuring that the entire copper surface can be fully protected. EDTA (ethylenediaminetetraacetic acid) is a chelating agent, which can form stable complexes with the metal ions that may exist in the protection liquid in the protection liquid. This helps to prevent the interference and damage of metal ions to the protection liquid, maintaining the stability and effectiveness of the protection liquid. At the same time, EDTA can also form complexes with copper ions, further inhibiting the oxidation and corrosion of the copper layer. To sum up, each component in the copper protection liquid, through its own characteristics and their synergistic effects, jointly achieves the goal of forming a dense, uniform and stable protective layer on the copper surface. This protective layer can not only improve the antioxidant performance and heat shock resistance of the environmental protection multi-layer board, but also ensure a 100% tinning rate, thus meeting the production requirements of high-quality electronic products.

[0017] Preferably, the composite film-forming agent is composed of benzotriazole and 2-heptyl-5-nitrobenzimidazole in a mass ratio of 3:2 - 3.

[0018] By adopting the above technical scheme, benzotriazole is an efficient copper corrosion inhibitor that can form a stable complex with the copper surface to prevent copper oxidation and corrosion. In the protective solution, benzotriazole can provide long-term protective effects to ensure that the copper layer remains stable under various environmental conditions. 2-heptyl-5-nitrobenzimidazole can enhance the adhesion between the protective layer and the copper layer, making the protective layer more firmly attached to the copper surface. This compound has high thermal stability and can maintain its protective performance under high temperature conditions, thereby improving the heat shock resistance of environmentally friendly multi-room boards. Benzotriazole mainly provides antioxidant properties, while 2-heptyl-5-nitrobenzimidazole enhances the combination of adhesion and heat resistance, forming a protective layer with both excellent antioxidant properties and high adhesion and heat resistance. Due to the interaction of the two compounds, the distribution of the protective layer on the copper surface is more evenly covered, avoiding the appearance of local weak points, thereby improving the overall protective effect. The stability of benzotriazole combined with the adhesion and heat resistance of 2-heptyl-5-nitrobenzimidazole allows the protective layer to maintain its performance during long-term use and is not easy to fall off or fail. In summary, the synergistic effect of benzotriazole and 2-heptyl-5-nitrobenzimidazole in the copper protection solution not only improves the antioxidant and heat shock resistance of the environmentally friendly multi-layer board, but also ensures a 100% tinning rate, making the entire treatment process more efficient, stable and reliable.

[0019] Preferably, the composite surfactant is composed of sodium methylene dinaphthalene sulfonate and alkyl glycoside tartrate in a mass ratio of 4:2-3.

[0020] By adopting the above technical scheme, sodium methylene dinaphthalene sulfonate has good wetting properties, can reduce the surface tension of the protective liquid, and make the protective liquid more easily penetrate into the surface and tiny pores of the copper layer. It can also effectively disperse other components in the protective liquid to ensure the uniformity and consistency of the protective layer. Alkyl glycoside tartrate can enhance the adhesion between the protective layer and the copper layer, so that the protective layer is more firmly attached to the copper surface. This compound helps to improve the stability of the protective liquid and prevent the protective liquid from stratification or precipitation during use. Sodium methylene dinaphthalene sulfonate mainly provides wettability and dispersibility, while alkyl glycoside tartrate enhances adhesion and stability. The combination of the two forms a protective layer with good wettability and dispersibility as well as strong adhesion and stability. Due to the interaction of the two compounds, the distribution of the protective layer on the copper surface is more evenly covered, avoiding the occurrence of local weak points, thereby improving the overall protective effect. Long-term stability The stability of sodium methylene dinaphthalene sulfonate combined with the adhesion and stability of alkyl glycoside tartrate enables the protective layer to maintain its performance during long-term use and is not easy to fall off or fail.

[0021] Preferably, the process conditions for copper protection are as follows: the temperature of the protective liquid is 25-35°C, and the immersion time is 60-90 seconds.

[0022] In summary, the beneficial technical effects of this application are as follows: 1. High cleaning ability: Through the circulating spray degreasing step, this process can quickly and effectively remove the oil stains on the surface of the multilayer board, ensuring the effective progress of subsequent processing steps.

[0023] 2. Excellent oxidation resistance and thermal shock resistance: The protective layer formed by the copper protection treatment not only improves the oxidation resistance of the multilayer board but also enhances its thermal shock resistance, which is crucial for extending the service life of the material.

[0024] 3. High tin plating rate: This process ensures a 100% tin plating rate, which is very important for the soldering and other applications of electronic products, ensuring good electrical connection performance.

[0025] 4. Simple operation and low cost: The entire treatment process is simple and easy to implement, with convenient operation. At the same time, because the chemical reagents and equipment used are relatively common, the cost is relatively low, making it suitable for large-scale production.

[0026] 5. Environmental protection and safety: The chemical reagents used are all environmentally friendly, and the waste liquid generated during the treatment process is easy to handle, with little impact on the environment, meeting the concept of green production.

[0027] 6. Excellent micro-etching performance: The spray micro-etching step can not only efficiently etch the copper surface but also has good stability, effectively inhibiting the oxidation and discoloration of the copper surface, while enhancing the adhesion between the protective layer and the copper layer. Detailed implementation mode

[0028] The following will describe the implementation plan of this application in detail in combination with the embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate this application and should not be regarded as limiting the scope of this application. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0029] In the following embodiments, the environmentally friendly multilayer board to be processed is a PCB board with chemically deposited copper.

[0030] Example 1 An environmentally friendly surface copper protection treatment process for multi-layer boards, comprising the following steps: circulating spray degreasing → three-stage pressure water washing → drying → spray micro-etching → three-stage pressure water washing → drying → copper protection → three-stage pressure water washing → drying → drying → air cooling, wherein, the circulating spray degreasing includes components with the following mass concentrations: sodium silicate 8g / L, composite surfactant 1.1g / L, polyepoxysuccinic acid sodium 0.5g / L; the temperature of the circulating spray degreasing is 20°C, the time is 60 seconds, and the circulating spray degreasing pressure is 1.1 Kg / cm 2 ; the composite surfactant is composed of isooctyl polyoxypropylene polyoxyethylene ether and alkylphenol polyoxyethylene (4) ether in a mass ratio of 4:1; the conductivity of the pure water inlet of the three-stage pressure water washing is 20 μs / cm, and the pressure of the three-stage pressure water washing is 1.0 Kg / cm 2 , the drying process is to use a PVA foaming water-absorbing roller to dry the water on the surface of the multi-layer board; the drying process is to use hot air at 60°C for drying; the air cooling process is to use a cooling fan to cool to 30°C.

[0031] Among them, the micro-etching treatment solution for the spray micro-etching includes components with the following mass concentrations: sulfuric acid 6g / L, hydrogen peroxide 6g / L, hydroxyethyl ethylenediamine triacetic acid 1g / L, corrosion inhibitor 2g / L, stabilizer 1g / L, surfactant 5g / L, the temperature is 20°C, the time is 30 seconds, and the spray pressure is 1.1 Kg / cm 2 , the corrosion inhibitor is composed of 1-hydroxybenzotriazole and dibenzotriazole in a mass ratio of 5:3; the stabilizer is ethylenediamine disuccinic acid; the surfactant is composed of isomeric tridecyl polyoxyethylene ether and isooctyl polyoxypropylene polyoxyethylene ether in a mass ratio of 1:1.

[0032] Among them, the protection solution for the copper protection includes components with the following mass concentrations: composite film-forming agent 12g / L, lactic acid 60g / L, lauric acid 0.5g / L, composite surfactant 0.7g / L, EDTA 0.5g / L; the preparation method of the protection solution is to weigh the raw materials according to the formula ratio, mix, and stir. The composite film-forming agent is composed of benzotriazole and 2-heptyl-5-nitrobenzimidazole in a mass ratio of 3:2, and the composite surfactant is composed of sodium methylene bisnaphthalene sulfonate and alkyl glycoside tartrate in a mass ratio of 4:2. The process conditions for copper protection are: the temperature of the protection solution is 25°C, and the soaking time is 90 seconds.

[0033] Example 2 An environmentally friendly surface copper protection treatment process for multi-layer boards, comprising the following steps: circulating spray degreasing → three-stage pressure water washing → drying by suction → spray micro-etching → three-stage pressure water washing → drying by suction → copper protection → three-stage pressure water washing → drying by suction → drying → air cooling, wherein, the circulating spray degreasing comprises components with the following mass concentrations: sodium silicate 10g / L, composite surfactant 1.4g / L, polyepoxysuccinic acid sodium 0.7g / L; the temperature of the circulating spray degreasing is 30°C, the time is 30 seconds, and the pressure of the circulating spray degreasing is 1.4 Kg / cm 2 ; the composite surfactant is composed of isooctyl polyoxypropylene polyoxyethylene ether and alkylphenol polyoxyethylene (4) ether in a mass ratio of 4:2; the conductivity of the pure water inlet of the three-stage pressure water washing is 15 μs / cm, and the pressure of the three-stage pressure water washing is 1.5 Kg / cm 2 , the process of drying by suction is to use a PVA foaming water-absorbing roller to dry the water on the surface of the multi-layer board; the process of drying is to use hot air at 80°C for drying; the process of air cooling is to use a cooling fan to cool to 25°C.

[0034] Among them, the micro-etching treatment solution for spray micro-etching comprises components with the following mass concentrations: sulfuric acid 10g / L, hydrogen peroxide 12g / L, hydroxyethyl ethylenediamine triacetic acid 2g / L, corrosion inhibitor 4g / L, stabilizer 3g / L, surfactant 8g / L, the temperature is 30°C, the time is 10 seconds, and the spray pressure is 1.4 Kg / cm 2 , the corrosion inhibitor is composed of 1-hydroxybenzotriazole and dibenzotriazole in a mass ratio of 5:3; the stabilizer is ethylenediamine disuccinic acid; the surfactant is composed of isomeric tridecyl polyoxyethylene ether and isooctyl polyoxypropylene polyoxyethylene ether in a mass ratio of 1:1.

[0035] Among them, the protection solution for copper protection comprises components with the following mass concentrations: composite film-forming agent 16g / L, lactic acid 70g / L, lauric acid 0.8g / L, composite surfactant 0.9g / L, EDTA 0.8g / L; the preparation method of the protection solution is to weigh the raw materials according to the formula ratio, mix them, and stir. The composite film-forming agent is composed of benzotriazole and 2-heptyl-5-nitrobenzimidazole in a mass ratio of 3:3, and the composite surfactant is composed of sodium methylene dinaphthalene sulfonate and alkyl glycoside tartrate in a mass ratio of 4:3. The process conditions for copper protection are: the temperature of the protection solution is 35°C, and the soaking time is 60 seconds.

[0036] Example 3 An environmentally friendly surface copper protection treatment process for multi-layer boards, comprising the following steps: circulating spray degreasing → three-stage pressure water washing → drying by suction → spray micro-etching → three-stage pressure water washing → drying by suction → copper protection → three-stage pressure water washing → drying by suction → drying → air cooling, wherein, the circulating spray degreasing includes components with the following mass concentrations: sodium silicate 9g / L, composite surfactant 1.3g / L, polyepoxysuccinic acid sodium 0.6g / L; the temperature of the circulating spray degreasing is 25°C, the time is 50 seconds, and the circulating spray degreasing pressure is 1.2 Kg / cm 2 ; the composite surfactant consists of isooctanol polyoxypropylene polyoxyethylene ether and alkylphenol polyoxyethylene (4) ether in a mass ratio of 4:1.5; the conductivity of the pure water inlet of the three-stage pressure water washing is 10 μs / cm, and the pressure of the three-stage pressure water washing is 1.3 Kg / cm 2 , the process of drying by suction is to use a PVA foaming water-absorbing roller to dry the water on the surface of the multi-layer board; the process of drying is to use hot air at 70°C for drying; the process of air cooling is to use a cooling fan to cool to 30°C.

[0037] Among them, the micro-etching treatment solution for spray micro-etching includes components with the following mass concentrations: sulfuric acid 8g / L, hydrogen peroxide 9g / L, hydroxyethyl ethylenediaminetriacetic acid 1.2g / L, corrosion inhibitor 3g / L, stabilizer 2g / L, surfactant 7g / L, the temperature is 25°C, the time is 20 seconds, and the spray pressure is 1.2 Kg / cm 2 , the corrosion inhibitor consists of 1-hydroxybenzotriazole and dibenzotriazole in a mass ratio of 5:3; the stabilizer is ethylenediamine disuccinic acid; the surfactant consists of isomeric tridecanol polyoxyethylene ether and isooctanol polyoxypropylene polyoxyethylene ether in a mass ratio of 1:1.

[0038] Among them, the protection solution for copper protection includes components with the following mass concentrations: composite film-forming agent 14g / L, lactic acid 65g / L, lauric acid 0.7g / L, composite surfactant 0.8g / L, EDTA 0.6g / L; the preparation method of the protection solution is to weigh the raw materials according to the formula ratio, mix, and stir. The composite film-forming agent consists of benzotriazole and 2-heptyl-5-nitrobenzotriazole in a mass ratio of 3:2.5, and the composite surfactant consists of sodium methylene bisnaphthalene sulfonate and alkyl glycoside tartrate in a mass ratio of 4:2.5. The process conditions for copper protection are: the temperature of the protection solution is 30°C, and the soaking time is 80 seconds.

[0039] Comparative Example 1 Same as Example 3, the difference is that: in the protection solution for copper protection, the composite film-forming agent is benzotriazole.

[0040] Comparative Example 2 Same as Example 3, except that: in the protective solution for protecting copper, the composite film-forming agent is 2-heptyl-5-nitrobenzimidazole.

[0041] Comparative Example 3 Same as Example 3, except that: in the protective solution for protecting copper, the composite surfactant is sodium methylene bisnaphthalene sulfonate.

[0042] Comparative Example 4 Same as Example 3, except that: in the protective solution for protecting copper, the composite surfactant is alkyl glycoside tartrate.

[0043] Performance Test Samples of the environmentally friendly multi-layer boards prepared in Examples 1 - 3 and Comparative Examples 1 - 4 were taken respectively for the following performance tests, and the results are shown in Table 1; Antioxidant test: The treated samples were placed in a constant temperature and humidity chamber at a temperature of 65°C and a humidity of 95% for 10 days, and the copper surface was observed for oxidation and discoloration. Thermal shock resistance: The test samples were processed through the following process: (1) Constant temperature at 120°C, baking the test board for 30 min; (2) Constant temperature at 150°C, baking the test board for 15 min; (3) Constant temperature at 260°C, baking the test board for 5 min; (4) Constant temperature at 288°C, baking the test board for 10 s, standing at room temperature for 10 s, continuously for three times, and then baking the test board for 30 s. After the sample board was cooled, the color change was observed. Tinning rate: Wave soldering experimental conditions: Using a small wave soldering furnace, preheating temperature 120, soldering temperature 265°C, conveying speed of the environmentally friendly multi-layer board 1M / m, tinning time 2 s (single wave), and the soldering flux is RMA type soldering flux. 7 groups of environmentally friendly multi-layer boards (samples of the environmentally friendly multi-layer boards prepared in Examples 1 - 3 and Comparative Examples 1 - 4), 100 pieces in each group, were tested for the tinning rate, and the average value was taken.

[0044] Table 1 Performance Test Table Project Antioxidant property Heat resistance Tinning rate / % Example 1 No No 100 Example 2 No No 100 Example 3 No No 100 Comparative example 1 Slight discoloration Slight discoloration 93 Comparative example 2 Slight discoloration Slight discoloration 92 Comparative example 3 Slight discoloration Slight discoloration 95 Comparative example 4 Slight discoloration Slight discoloration 96 Analyzing the data in Table 1, it can be seen that: 1) Combining Examples 1 - 3, it can be seen that the surface copper protection treatment process of the environmentally friendly multi-layer board of the present application can not only simply and efficiently remove oil stains and form a dense protective layer, improve the antioxidant performance and thermal shock resistance of the environmentally friendly multi-layer board, but also the tinning rate is 100%.

[0045] 2) By combining the performance comparison and analysis of Example 3 and Comparative Examples 1-2, it can be seen that when the composite film-forming agent consists of benzotriazole and 2-heptyl-5-nitrobenzimidazole in a mass ratio of 3:2.5, benzotriazole can provide long-term protection, ensuring that the copper layer remains stable under various environmental conditions. 2-Heptyl-5-nitrobenzimidazole can enhance the adhesion between the protective layer and the copper layer, making the protective layer adhere more firmly to the copper surface. This compound has high thermal stability and can maintain its protective performance in high-temperature environments, thereby improving the thermal shock resistance of the environmentally friendly multi-layer board. Benzotriazole mainly provides antioxidant properties, while 2-heptyl-5-nitrobenzimidazole enhances adhesion and heat resistance. The combination of the two forms a protective layer with excellent antioxidant properties, high adhesion, and heat resistance. Due to the interaction of these two compounds, the protective layer is more evenly distributed and covered on the copper surface, avoiding the appearance of local weak points, thus improving the overall protective effect. Utilizing their synergistic effect not only improves the antioxidant and thermal shock resistance of the environmentally friendly multi-layer board but also ensures a 100% solderability, making the entire treatment process more efficient, stable, and reliable.

[0046] 3) By combining the performance comparison and analysis of Example 3 and Comparative Examples 3-4, it can be seen that when the composite surfactant consists of sodium methylene bisnaphthalene sulfonate and alkyl glycoside tartrate in a mass ratio of 4:2.5, sodium methylene bisnaphthalene sulfonate has good wetting properties, which can reduce the surface tension of the protective liquid and make the protective liquid more easily penetrate into the surface and micro-pores of the copper layer. It can also effectively disperse other components in the protective liquid, ensuring the uniformity and consistency of the protective layer. Alkyl glycoside tartrate can enhance the adhesion between the protective layer and the copper layer, making the protective layer adhere more firmly to the copper surface. This compound helps to improve the stability of the protective liquid and prevent the protective liquid from stratifying or precipitating during use. Utilizing their synergistic effect, a protective layer with good wettability, dispersibility, strong adhesion, and stability is formed. Due to the interaction of these two compounds, the protective layer is more evenly distributed and covered on the copper surface, avoiding the appearance of local weak points, thus improving the overall protective effect. Furthermore, it improves the antioxidant and thermal shock resistance of the environmentally friendly multi-layer board, and at the same time, the solderability is 100%.

[0047] The above embodiments are only used to explain the technical solutions of the present application and are not intended to limit them. Although the above embodiments have specifically described the present application, those skilled in the art should understand that they can still modify the specific implementation manners of the present invention or make equivalent replacements. Any modification and equivalent replacement without departing from the spirit and scope of the present application should be covered within the protection scope of the present application.

Claims

1. An environmentally friendly multi-layer board surface copper protection treatment process, characterized in that: The following steps are involved: Circulating spray degreasing → three-stage pressure water washing → drying → spray micro-etching → three-stage pressure water washing → drying → copper protection → three-stage pressure water washing → drying → drying → blowing cold, wherein the circulating spray degreasing includes the following components in mass concentrations: sodium silicate 8-10g / L, composite surfactant 1.1-1.4g / L, polyepoxy sodium succinate 0.5-0.7g / L.

2. According to claim 1, an environmentally friendly multi-layer board surface copper protection treatment process is characterized in that: The temperature of the circulating spray degreasing is 20-30°C, the time is 30-60 seconds, and the pressure of the circulating spray degreasing is 1.1-1.4Kg / cm 2 .

3. The environmentally friendly copper protection treatment process for multi-layer board surface according to claim 1 is characterized in that: The composite surfactant is composed of isooctyl alcohol polyoxypropylene polyoxyethylene ether and alkylphenol polyoxyethylene (4) ether in a mass ratio of 4:1-2.

4. The environmentally friendly copper protection treatment process for multi-layer board surface according to claim 1 is characterized in that: The conductivity of the pure water inlet of the three-stage pressure water washing is ≤20μs / cm, and the pressure of the three-stage pressure water washing is 1.0-1.5Kg / cm 2 The drying process is to use a PVA foaming water-absorbing roller to absorb water from the surface of the multilayer board; the drying process is to use 60-80°C hot air for drying; and the cooling process is to use a cooling fan to cool to below 30°C.

5. The environmentally friendly copper protection treatment process for multi-layer board surface according to claim 1 is characterized in that: The micro-etching treatment liquid for spray micro-etching includes the following components in mass concentrations: 6-10 g / L sulfuric acid, 6-12 g / L hydrogen peroxide, 1-2 g / L hydroxyethylethylenediaminetriacetic acid, 2-4 g / L corrosion inhibitor, 1-3 g / L stabilizer, 5-8 g / L surfactant, the temperature is 20-30°C, the time is 10-30 seconds, and the spraying pressure is 1.1-1.4 Kg / cm 2 .

6. The environmentally friendly copper protection treatment process for multi-layer board surface according to claim 5 is characterized in that: The corrosion inhibitor is composed of 1-hydroxybenzotriazole and dibenzotriazole in a mass ratio of 5:3; the stabilizer is ethylenediamine disuccinic acid; and the surfactant is composed of isomeric tridecyl alcohol polyoxyethylene ether and isooctyl alcohol polyoxypropylene polyoxyethylene ether in a mass ratio of 1:

1.

7. The environmentally friendly copper protection treatment process for multi-layer board surface according to claim 1, characterized in that: The copper protection solution comprises the following components in mass concentrations: 12-16 g / L of composite film-forming agent, 60-70 g / L of lactic acid, 0.5-0.8 g / L of lauric acid, 0.7-0.9 g / L of composite surfactant, and 0.5-0.8 g / L of EDTA. The preparation method of the protection solution is to weigh the raw materials according to the formula ratio, mix them, and stir them.

8. The environmentally friendly copper protection treatment process for multi-layer boards according to claim 7, characterized in that: The composite film-forming agent is composed of benzotriazole and 2-heptyl-5-nitrobenzimidazole in a mass ratio of 3:2-3.

9. The environmentally friendly copper protection treatment process for multi-layer board surface according to claim 7, characterized in that: The composite surfactant is composed of sodium methylene dinaphthalene sulfonate and alkyl glycoside tartrate in a mass ratio of 4:2-3.

10. The environmentally friendly copper protection treatment process for multi-layer board surface according to claim 7, characterized in that: The process conditions of the copper protection are: the temperature of the protection liquid is 25-35° C., and the immersion time is 60-90 seconds.