A method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards

Abstract

This invention relates to the field of circuit board manufacturing technology and discloses a method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards. The method includes: S1, thoroughly cleaning the circulation system, coating equipment, and container with pure water; S2, preparing a nano-hybrid sol and pouring it into the coating equipment; S3, spraying the nano-hybrid sol onto the copper foil using a spraying process; S4, applying the sprayed coating evenly using a roller coating process; S5, drying the coating in an oven; and S6, promptly draining the remaining solution, repeatedly rinsing the equipment with clean water, and performing a weak acid treatment. By applying a targeted nano-hybrid coating to the copper foil surface, the problem of adhesion to rollers caused by material and process factors in the production of domestically produced TPI flexible circuit boards is effectively solved. This coating forms a stable protective layer between the copper foil and the production equipment rollers, fundamentally changing the physical and chemical properties of the copper foil surface and significantly reducing its tendency to adhere to the rollers under high-temperature processes.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, specifically to a method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards. Background Technology

[0002] In the modern electronics industry, flexible circuit boards (PCBs) are widely used in various electronic devices as an important material. TPI PCBs, due to their excellent high-temperature resistance, corrosion resistance, and electrical insulation, have become the preferred choice for high-performance circuit boards. However, during the production process of TPI PCBs, the copper foil, as the conductive layer, frequently adheres to the rollers of the production equipment. This adhesion not only affects production efficiency but can also cause material damage and waste, seriously impacting the quality and reliability of electronic products.

[0003] Current technologies for addressing the adhesion problem between copper foil and rollers primarily rely on conventional surface treatment methods, but these often yield unsatisfactory results. Due to a lack of targeted coating solutions, traditional methods can only partially improve the surface properties of the copper foil, failing to effectively form a stable protective layer. Furthermore, most surface-treated coatings lack superior physical properties such as high-temperature resistance and wear resistance, easily leading to coating failure in the production environment and further exacerbating material adhesion to equipment. In addition, existing curing processes are mostly one-time high-temperature curing, which can easily result in insufficient coating hardness and poor wear resistance, making it impossible to maintain a highly efficient and stable state during production. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for improving the treatment of copper foil adhesion to rollers in TPI flexible circuit boards, solving the problems of low production efficiency and material damage caused by the adhesion between copper foil and the rollers of the production equipment during the TPI flexible circuit board production process.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards, comprising:

[0006] S1. Thoroughly clean the circulation system, coating equipment and containers with pure water to remove oil, dust and residual impurities;

[0007] S2. Prepare the nano-hybrid sol and pour it into the coating equipment:

[0008] S3. The nano-hybrid sol is sprayed onto the copper foil using a spraying process;

[0009] S4. Apply the sprayed coating evenly using a roller coating process;

[0010] S5. Dry the coating in an oven;

[0011] S6. Drain the remaining solution promptly, rinse the equipment repeatedly with clean water, and treat it with a weak acid to keep the equipment in a condition that meets production requirements.

[0012] Preferably, in step S1, pure water is used for circulating cleaning, and the cleaning flow rate is 1-2 m³ / s. 3 The cleaning time is 30-60 minutes per hour to remove oil, dust and residual impurities from the circulation system, coating equipment and containers.

[0013] Furthermore, by using cyclic cleaning with specified flow rates and times, the mechanical flushing and dissolving effects of the water flow can be utilized to ensure the complete removal of these microscopic contaminants from the inner walls of equipment and pipes.

[0014] Preferably, the nano-hybrid sol in step S2 is prepared through the following steps;

[0015] Preparation of precursor materials: tetraethoxysilane, 3-mercaptopropyltrimethoxysilane, fluorinated polyether silane and bis(3-triethoxysilylpropyl)tetrasulfide;

[0016] Mix in a molar ratio of 10:0.8-1.2:0.4-0.6:0.8-1.2;

[0017] Anhydrous ethanol and deionized water were mixed at a volume ratio of 4:1, and the mixture was slowly added to the mixture while stirring to form an initial reaction solution.

[0018] The pH of the reaction solution was adjusted to 3.0-4.0 using a 0.1M hydrochloric acid solution to promote the hydrolysis and condensation reaction of silanes.

[0019] In an environment of 25-40°C, the reaction solution is continuously stirred for 2-4 hours until a transparent and uniform nano-hybrid sol is formed.

[0020] Furthermore, tetraethoxysilane (TEOS), as the main network builder, forms an inorganic Si-O-Si framework through hydrolysis and polycondensation, providing the coating with fundamental hardness and structural stability. 3-Mercaptopropyltrimethoxysilane is a key adhesion promoter; its terminal thiol groups (-SH) have a strong chemical affinity for copper, enabling it to form chemical bonds at the coating-copper foil interface, thus firmly anchoring the inorganic network to the copper foil surface. Fluorinated polyether silane is a surface modifier; its long fluorinated chains migrate to the coating surface during curing, significantly reducing the coating's surface energy, which is crucial for achieving the anti-sticking effect. Bis(3-triethoxysilylpropyl)tetrasulfide, as a flexible crosslinking agent, introduces its sulfide segments into the rigid Si-O-Si network, effectively improving the coating's toughness and preventing cracking under mechanical stress due to excessive brittleness.

[0021] Preferably, the step S2, in which the nano-hybrid sol is poured into the coating equipment, includes the following steps;

[0022] The nano-hybrid sol was prepared at a depth of 1.5-3.0 m. 3 Circulate and mature for 4-6 hours at a flow rate of / h;

[0023] After the cycle is completed, the key parameters of the nano-hybrid sol are tested to ensure that the pH value is between 5.0 and 8.0, the solid content is between 2000 and 3000 ppm, and the viscosity is between 1.5 and 3.0 mPa·s.

[0024] Furthermore, the hydrolysis and initial condensation reactions within the sol system provide ample time for it to reach a relatively stable state suitable for coating. Circulation ensures highly uniform temperature and component concentration within the sol system, preventing gelation or precipitation caused by uneven local reactions. After sufficient maturation, the sol's network structure is initially formed but not yet solidified, exhibiting ideal viscosity and flowability, which is crucial for obtaining a uniform wet film in subsequent spraying and roller coating processes.

[0025] Preferably, step S3, which involves spraying the nano-hybrid sol onto the copper foil using a spraying process, specifically includes the following steps:

[0026] The prepared nano-hybrid sol is injected into the spraying chamber through a spraying device, and the distance between the nozzle and the copper foil surface is set to 3-5 cm.

[0027] Adjust the spraying flow rate to ensure that the nano-hybrid sol is evenly sprayed onto the copper foil surface, forming a coating with uniform wet film thickness;

[0028] During the spraying process, maintain the copper foil linear speed at 2-10 m / min.

[0029] Furthermore, through optimized spraying and roller coating processes, combined with specific copper foil line speeds, nano-hybrid sol is uniformly applied to the copper foil surface to form a coating of a specific thickness. The spraying process can quickly cover the moving copper foil in an atomized form, forming a preliminary wet film.

[0030] Preferably, the spraying flow rate is 1.5-3.0 m³ / h. 3 / h, coating thickness is 5-10μm.

[0031] Preferably, the roller coating process in step S4, which involves uniformly applying the sprayed coating, specifically includes the following steps:

[0032] The coated copper foil is placed in a roller coating machine, and the roller pressure between the roller and the copper foil is controlled within the range of 0.5-1.5 MPa.

[0033] Set the roller coating speed to 2-10 m / min and keep the roller coating direction the same as the spraying direction to ensure uniform coating distribution;

[0034] The coating thickness is monitored regularly during the roll coating process to ensure that the final coating thickness is between 5-10 μm.

[0035] Furthermore, it eliminates minor defects that may result from spraying and squeezes out any air bubbles that may be trapped in the coating, allowing for a closer wetting contact between the sol and the copper foil surface. Combining the speed advantage of spraying with the precision advantage of roll coating ensures that high-quality coatings with uniform thickness, smooth surfaces, and no air bubble defects can still be obtained even at continuous production speeds.

[0036] Preferably, after the coating is applied evenly, the coated copper foil is inspected to check for bubbles or defects on the coating surface.

[0037] Preferably, the drying of the coating in the oven in step S5 specifically includes the following steps;

[0038] Place the coated copper foil into a temperature-controlled oven, set the oven temperature to 80-90℃, and dry it at this temperature for 60-90 seconds.

[0039] After initial drying, raise the temperature to 120-140℃ for complete curing, which takes 90-120 seconds.

[0040] Furthermore, the key lies in the effective management of internal stress within the coating and the full driving of the chemical reaction. The primary purpose of the first stage, low-temperature drying at 80-90℃, is to gently remove most of the solvent from the coating. If high temperatures are used directly, the coating surface will quickly "skin" over, sealing in the internal solvent. Subsequent high-temperature vaporization of the solvent will then break through the surface, forming defects such as pinholes and bubbles. After most of the solvent has been removed, the second stage, high-temperature curing at 120-140℃, begins. Its main function here is to provide sufficient energy to drive a full condensation reaction between the silanol groups, forming a dense and stable three-dimensional Si-O-Si cross-linked network.

[0041] Preferably, the specific operation of equipment cleaning in step S6 includes the following steps;

[0042] After the coating is dried, immediately drain the remaining solution from the coating equipment to ensure that no impurities or solvents remain in the equipment.

[0043] The coating equipment is rinsed repeatedly with deionized water, at least three times, to ensure the cleanliness of the equipment.

[0044] The coating equipment is treated with a weak acid solution with a concentration of 0.1-0.5M for 10-20 minutes to remove any possible residual chemicals.

[0045] This invention provides a method for improving the treatment of copper foil sticking to rollers in TPI flexible printed circuit boards. It has the following beneficial effects:

[0046] 1. This invention effectively solves the problem of adhesion to rollers caused by material and process factors in the production of domestically produced TPI flexible circuit boards by applying a targeted nano-hybrid coating to the surface of the copper foil. This coating forms a stable isolation and protective layer between the copper foil and the production equipment rollers, fundamentally changing the physical and chemical properties of the copper foil surface and significantly reducing its tendency to adhere to the rollers under high-temperature processes.

[0047] 2. This invention significantly improves the hardness and wear resistance of the coating through reasonable curing temperature control. The gradual temperature increase curing method promotes chemical cross-linking between nanoparticles, forming a more ideal network structure, enabling the coating to maintain excellent physical properties under different environments.

[0048] 3. By adjusting the spray flow rate and curing conditions, this invention achieves optimal surface smoothness of the coating, significantly reducing the incidence of bubbles and defects. This superior uniformity not only improves the physical properties of the coating but also enhances its corrosion and wear resistance. Attached Figure Description

[0049] Figure 1 This is a flowchart of the method of the present invention;

[0050] Figure 2 This is a schematic diagram of the circulation system of the present invention. Detailed Implementation

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] Please see the appendix Figure 1 -Appendix Figure 2 This invention provides a method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards, comprising:

[0053] Example 1;

[0054] Pure water is used for circulating cleaning at a flow rate of 1.5m³ / h. 3The cleaning process takes 45 minutes per hour to remove oil, dust, and residual impurities from the circulation system, coating equipment, and containers.

[0055] Precursor materials: tetraethoxysilane, 3-mercaptopropyltrimethoxysilane, fluorinated polyether silane and bis(3-triethoxysilylpropyl)tetrasulfide, in a molar ratio of 10:1:0.5:1.

[0056] Anhydrous ethanol and deionized water were mixed at a volume ratio of 4:1, and the mixture was slowly added to the mixture while stirring to form an initial reaction solution.

[0057] The pH of the reaction solution was adjusted to 3.5 using a 0.1M hydrochloric acid solution to promote hydrolysis and condensation reactions.

[0058] Stirring at 28°C for 3 hours forms a transparent and uniform nano-hybrid sol.

[0059] At 1.5m 3 The sol was circulated and matured for 5 hours at a flow rate of / h to ensure uniformity and stability.

[0060] After the cycle was completed, the pH value (5.5), solid content (2500 ppm), and viscosity (2.0 mPa·s) of the sol were measured.

[0061] The nano-hybrid sol is injected into the spraying chamber through a spraying device, with the nozzle 4 cm away from the copper foil surface.

[0062] The spraying flow rate is 2.0m. 3 / h, maintaining a copper foil linear speed of 6m / min, forming a coating thickness of 8μm.

[0063] The coated copper foil is placed in a roller coating machine with the roller pressure controlled at 1.0 MPa and the roller coating speed at 4 m / s.

[0064] Monitor coating uniformity to ensure a coating thickness of 8 μm.

[0065] Dry at 80°C for 60 seconds, then increase the temperature to 130°C for complete curing, with a curing time of 100 seconds.

[0066] After the coating has dried, immediately drain the remaining solution from the coating equipment and rinse with deionized water at least three times.

[0067] Remove residue by soaking in a 0.3M weak acid solution for 15 minutes.

[0068] Example 2;

[0069] Pure water is used for circulating cleaning at a flow rate of 1.0 m³ / h. 3The cleaning process takes 30 minutes per hour to remove oil, dust, and residual impurities from the circulation system, coating equipment, and containers.

[0070] Precursor materials: tetraethoxysilane, 3-mercaptopropyltrimethoxysilane, fluorinated polyether silane and bis(3-triethoxysilylpropyl)tetrasulfide, in a molar ratio of 10:0.8:0.4:0.8.

[0071] Anhydrous ethanol and deionized water were mixed at a volume ratio of 4:1, and the mixture was slowly added to the mixture while stirring to form an initial reaction solution.

[0072] The pH of the reaction solution was adjusted to 3.0 using a 0.1M hydrochloric acid solution to promote hydrolysis and condensation reactions.

[0073] Stirring at 25°C for 4 hours forms a transparent and uniform nano-hybrid sol.

[0074] At 2.0m 3 The sol was circulated and matured for 4 hours at a flow rate of / h to ensure uniformity and stability.

[0075] After the cycle was completed, the pH value (5.0), solid content (2000 ppm), and viscosity (1.5 mPa·s) of the sol were measured.

[0076] The nano-hybrid sol is injected into the spraying chamber through a spraying device, with the nozzle 3 cm away from the copper foil surface.

[0077] The spraying flow rate is 1.5m. 3 / h, maintaining a copper foil linear speed of 4m / min, forming a coating thickness of 6μm.

[0078] The coated copper foil is placed in a roller coating machine with the roller pressure controlled at 0.5 MPa and the roller coating speed at 4 m / min.

[0079] Monitor coating uniformity to ensure a coating thickness of 6 μm.

[0080] Dry at 80°C for 50 seconds, then increase the temperature to 120°C for complete curing, which takes 90 seconds.

[0081] After the coating has dried, immediately drain the remaining solution from the coating equipment and rinse with deionized water at least three times.

[0082] Soak in a 0.1M weak acid solution for 10 minutes to remove residual substances.

[0083] Example 3:

[0084] Pure water is used for circulating cleaning at a flow rate of 2.0 m³ / h. 3The cleaning process takes 60 minutes per hour to remove oil, dust, and residual impurities from the circulation system, coating equipment, and containers.

[0085] Precursor materials: tetraethoxysilane, 3-mercaptopropyltrimethoxysilane, fluorinated polyether silane and bis(3-triethoxysilylpropyl)tetrasulfide, in a molar ratio of 10:1.2:0.6:1.2.

[0086] Anhydrous ethanol and deionized water were mixed at a volume ratio of 4:1, and the mixture was slowly added to the mixture while stirring to form an initial reaction solution.

[0087] The pH of the reaction solution was adjusted to 4.0 using a 0.1M hydrochloric acid solution to promote hydrolysis and condensation reactions.

[0088] Stirring at 40°C for 2 hours forms a transparent and uniform nano-hybrid sol.

[0089] At 3.0m 3 The sol was circulated and matured for 6 hours at a flow rate of / h to ensure uniformity and stability.

[0090] After the cycle was completed, the pH value (6.0), solid content (3000 ppm), and viscosity (3.0 mPa·s) of the sol were measured.

[0091] The nano-hybrid sol is injected into the spraying chamber through a spraying device, with the nozzle 5 cm away from the copper foil surface.

[0092] The spraying flow rate is 2.5m. 3 / h, maintaining a copper foil linear speed of 8m / min, forming a coating thickness of 10μm.

[0093] The coated copper foil is placed in a roller coating machine with the roller pressure controlled at 1.5 MPa and the roller coating speed at 8 m / min.

[0094] Monitor coating uniformity to ensure a coating thickness of 10 μm.

[0095] Dry at 90°C for 70 seconds, then increase the temperature to 140°C for complete curing, which takes 120 seconds.

[0096] After the coating has dried, immediately drain the remaining solution from the coating equipment and rinse with deionized water at least three times.

[0097] Remove residue by soaking in a 0.5M weak acid solution for 20 minutes.

[0098] Comparative Example 1: Compared with Example 1, the difference is that 3-mercaptopropyltrimethoxysilane is removed from the precursor material, and all other aspects are the same.

[0099] Comparative Example 2: The difference from Example 1 is that the pH value of the hydrolysis reaction was adjusted to 5.0, and all other aspects are the same.

[0100] Comparative Example 3: The difference compared to Example 1 is that the spray flow rate was reduced to 1.0 m³. 3 / h, the rest are the same.

[0101] Comparative Example 4: Compared with Example 1, the difference is that it was completely cured directly at 120°C, otherwise it is the same.

[0102] Experiment 1: The Influence of Precursor Materials on the Properties of Nano-Hybrid Sols

[0103] Experimental instructions

[0104] This experiment aims to compare the performance of the nano-hybrid sols prepared in Example 1 (using complete precursor materials) and Comparative Example 1 (removing 3-mercaptopropyltrimethoxysilane), focusing on analyzing their viscosity, stability, pH value and solid content.

[0105] Experimental steps

[0106] Sample preparation:

[0107] Two groups of nano-hybrid sols were prepared in the laboratory according to the formulations of Example 1 and Comparative Example 1.

[0108] Viscosity measurement:

[0109] Use a rotational viscometer to test the viscosity of the two groups of samples and record the results.

[0110] Stability assessment:

[0111] The two groups of samples were left to stand at room temperature for 24 hours. After that, the observation and recording were made to see if any layering occurred and whether there were any obvious changes at the interface.

[0112] pH measurement:

[0113] Use a pH meter to test the pH value of the two groups of samples and record the data.

[0114] Solid content determination:

[0115] Take a small amount of each sample into a weighing bottle, place it in an oven and dry it at 105℃ for 24 hours, then cool and weigh it to calculate the solid content.

[0116] The experimental data are shown in Table 1;

[0117] Table 1 Performance test data of nano-hybrid sol

[0118]

[0119]

[0120] Summarize;

[0121] Performance analysis of two sets of nano-hybrid sols revealed the significant impact of precursor material composition on sol properties. The examples used complete precursor materials, comprising four key components, whose synergistic effect enhanced the stability and viscosity of the sol. In contrast, Comparative Example 1, with 3-mercaptopropyltrimethoxysilane removed, exhibited higher viscosity and poorer stability. This indicates that this component plays a crucial role in structure formation and crosslinking, responsible for the effective bonding of any nanomaterial to the organic matrix, thus profoundly affecting the performance of the final coating.

[0122] Furthermore, pH variations significantly impacted the sol's properties. The low pH conditions maintained in the examples promoted hydrolysis and condensation of the reaction, ensuring uniform distribution and excellent reactivity of the nano-hybrid sol. In Comparative Example 1, however, the increased pH led to decreased stability in the initial stages of the reaction, resulting in slight stratification. This supports the necessity of employing a suitable acidic environment to optimize the nano-hybrid sol construction process, ensuring coating uniformity and thus improving the quality of the final product.

[0123] The experimental results highlight the potential advantages of using multi-component precursor materials, particularly in improving coating adhesion and abrasion resistance. The introduction of a complete precursor system not only enhances reactivity but also effectively improves the physical properties of the final coating.

[0124] Experiment 2: Effect of pH on the properties of nano-hybrid sol and coating

[0125] Experimental instructions

[0126] This experiment aims to compare the performance and coating quality of the nano-hybrid sols prepared in Example 1 (pH 3.5) and Comparative Example 2 (pH 5.0), focusing on analyzing their viscosity, coating thickness, uniformity, and adhesion.

[0127] Experimental steps

[0128] Sample preparation:

[0129] Two groups of nano-hybrid sols were prepared according to the formulations of Example 1 and Comparative Example 2, respectively, ensuring that the preparation was carried out under the same conditions.

[0130] pH measurement:

[0131] Use a pH meter to measure the pH value of each sol and record the results.

[0132] Viscosity measurement:

[0133] Use a rotational viscometer to test the viscosity of the two groups of samples and record the results.

[0134] Coating spraying:

[0135] The nano-hybrid sol was sprayed, with the spray flow rate set to 2.0 m³ / s as in Example 1. 3 / h and 1.5m of Comparative Example 2 3 / h.

[0136] After the spraying is completed, the initial coating thickness is measured using a coating thickness gauge, and the results are recorded.

[0137] Coating uniformity check:

[0138] The coating surface was observed using an optical microscope to record its uniformity and the presence of bubbles or defects.

[0139] Adhesion test:

[0140] The adhesion of the coating is evaluated using the tape test method. After applying tape to the coating surface, it is quickly peeled off. The peeling process is observed, and the adhesion level is recorded.

[0141] The experimental data are shown in Table 2;

[0142] Table 2 Performance test data of nano-hybrid sol and coating

[0143]

[0144]

[0145] Summarize;

[0146] Performance analysis of the nano-hybrid sols prepared at different pH values ​​clearly revealed the significant impact of pH on sol properties. In Example 1, the lower pH value (3.5) favored hydrolysis and condensation, promoting uniform dispersion and stability of the nanoparticles, resulting in higher adhesion and superior coating uniformity in coating applications. This result validates that a suitable acidic environment optimizes the construction process of the nano-hybrid sol, enhancing the adhesion between the coating and the substrate for better performance.

[0147] In contrast, in Comparative Example 2, raising the pH to 5.0 increased the viscosity of the sol, increased turbidity, and revealed significant defects in coating uniformity, such as bubbles and delamination. The increased pH may have reduced the polymerization reaction of some small molecular groups, hindering the stability of the nano-hybrid liquid. This change directly affects the physical properties of the coating, reducing its adhesion and potentially impacting its wear resistance and service life.

[0148] Experiment 3: Effect of spray flow rate on coating uniformity

[0149] Experimental instructions

[0150] This experiment aims to compare Example 1 (spray flow rate of 2.0 m). 3 / h) and Comparative Example 3 (spray flow rate reduced to 1.0m) 3 The quality of the coating prepared by / h) is analyzed, focusing on the uniformity, thickness and adhesion of the coating.

[0151] Experimental steps

[0152] Sample preparation:

[0153] Two groups of nano-hybrid sols were prepared according to the formulations of Example 1 and Comparative Example 3, respectively, to ensure that their compositions were consistent.

[0154] Coating spraying:

[0155] Coating application was performed using a spraying device. Example 1: The spray flow rate was maintained at 2.0 m³ / s. 3 / h, as a control group.

[0156] Comparative Example 3: The spray flow rate was adjusted to 1.0 m. 3 Coating is performed at / h.

[0157] Coating thickness measurement:

[0158] After the coating is applied, the thickness of each coating group is measured using a coating thickness gauge at multiple points to obtain the average value and standard deviation.

[0159] Uniformity check:

[0160] The coating surface was carefully examined using an optical microscope. Observed defects, such as bubbles, particle aggregation, and uneven coating, were recorded, and the number of defects was counted.

[0161] Adhesion test:

[0162] The adhesion of the coating is evaluated using the tape test method. Tape is applied to the coating surface, quickly peeled off, and the peeling process is recorded to assess the adhesion level.

[0163] The experimental data are shown in Table 3;

[0164] Table 3. Test data on the effect of spraying flow rate on coating quality.

[0165]

[0166]

[0167] Summarize;

[0168] The observed differences in coating quality in the experiment were significantly affected by the spray flow rate, validating the theoretical basis for improving the performance of nano-hybrid coatings by optimizing the spraying process. A higher spray flow rate (2.0 m³ / s in Example 1) was applied. 3 When the spray flow rate is increased by 1000 h, the resulting coating thickness is relatively uniform, and the adhesion test results show an adhesion level as high as 5, indicating a good distribution of the active components on the substrate surface. This phenomenon can be attributed to the fact that the larger spray flow rate results in higher pressure applied to the substrate surface, which enhances the bonding force between the nanomaterials and the substrate, promotes the film formation process, and thus improves the stability and durability of the coating.

[0169] Conversely, in Comparative Example 3, the spray flow rate was reduced to 1.0 m³ / s. 3 At a flow rate of [flow rate] / h, the coating thickness decreased and uniformity significantly declined. An increase in the number of defects was observed, indicating that the lower flow rate resulted in uneven coating coverage of the substrate during spraying, and the aggregated nanoparticles and bubbles ultimately affected the overall coating quality. These results suggest that reducing the spray flow rate limits the coating's settling time and the interactions between coating components, thus affecting the coating's mechanical properties and abrasion resistance to some extent, and weakening the material's protective capabilities.

[0170] Experiment 4: Effect of curing temperature on coating performance

[0171] Experimental instructions

[0172] This experiment aims to compare the coating performance prepared in Example 1 (complete curing using gradually increasing temperature) and Comparative Example 4 (curing directly at a single temperature above 120°C), focusing on analyzing the coating's hardness, adhesion, and abrasion resistance.

[0173] Experimental steps

[0174] Sample preparation:

[0175] Two sets of nano-hybrid coatings were prepared according to the formulations of Example 1 and Comparative Example 4, ensuring that the chemical composition of each set was consistent.

[0176] Curing process:

[0177] In Example 1, the coating was placed in an oven and heated gradually. The initial temperature was set at 80°C, and the temperature was increased by 20°C every 30 minutes until it reached 150°C and was maintained for 30 minutes to complete the curing.

[0178] In Comparative Example 4, the coating was directly heated to 120°C in an oven and maintained for 60 minutes for curing.

[0179] Coating hardness measurement:

[0180] The hardness of the coating was measured using a scratch hardness tester, and the data was recorded.

[0181] Adhesion test:

[0182] The adhesion of the coating was evaluated using the tape test method. The tape was applied to the coating surface, then quickly peeled off and the peeling was observed. The adhesion level was recorded.

[0183] Abrasion resistance test:

[0184] Abrasion resistance tests were conducted using an abrasion testing machine, and the loss rate of the coating under specific friction conditions was recorded.

[0185] The experimental data are shown in Table 4;

[0186] Table 4. Test data on the effect of curing temperature on coating performance.

[0187]

[0188]

[0189] Summarize;

[0190] Curing temperature has a significant impact on the performance of nano-hybrid coatings, especially in terms of hardness, adhesion, and abrasion resistance. Example 1 employed a progressively increasing curing process, allowing the coating to gradually reach its optimal curing state during temperature changes, promoting cross-linking reactions between nanoparticles and the formation of a network structure. This gradual heating method helps reduce stress concentration, ensuring uniform curing of the coating, thereby improving the overall hardness and mechanical strength of the coating, ultimately achieving high adhesion and abrasion resistance.

[0191] In Comparative Example 4, the method of curing directly at a higher temperature, while completing the curing process in a short time, may lead to uneven thermal stress within the coating, thereby reducing its physical properties. Particularly when the dispersion and chemical interactions of nanomaterials in the coating are affected, the coating's brittleness increases, further resulting in lower adhesion test results. In the experiments, the adhesion grades of the samples in Comparative Example 4 were generally lower than those in Example 1, indicating that high-temperature curing may lead to defects and embrittlement in the coating structure, affecting its adhesion to the substrate.

[0192] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards, characterized in that, include: S1. Thoroughly clean the circulation system, coating equipment and containers with pure water to remove oil, dust and residual impurities; S2. Prepare the nano-hybrid sol and pour it into the coating equipment: The nano-hybrid sol in step S2 is prepared through the following steps; Preparation of precursor materials: tetraethoxysilane, 3-mercaptopropyltrimethoxysilane, fluorinated polyether silane and bis(3-triethoxysilylpropyl)tetrasulfide; Mix in a molar ratio of 10:0.8-1.2:0.4-0.6:0.8-1.2; Anhydrous ethanol and deionized water were mixed at a volume ratio of 4:1, and the mixture was slowly added to the mixture while stirring to form an initial reaction solution. The pH of the reaction solution was adjusted to 3.0-4.0 using a 0.1M hydrochloric acid solution to promote the hydrolysis and condensation reaction of silanes. In an environment of 25-40℃, the reaction solution is continuously stirred for 2-4 hours until a transparent and uniform nano-hybrid sol is formed; S3. The nano-hybrid sol is sprayed onto the copper foil using a spraying process; S4. Apply the sprayed coating evenly using a roller coating process; S5. Dry the coating in an oven; S6. Drain the remaining solution promptly, rinse the equipment repeatedly with clean water, and treat it with a weak acid to keep the equipment in a condition that meets production requirements.

2. The method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards according to claim 1, characterized in that, In step S1, pure water is used for circulating cleaning, with a cleaning flow rate of 1-2 m³ / h. 3 The cleaning time is 30-60 minutes per hour to remove oil, dust and residual impurities from the circulation system, coating equipment and containers.

3. The method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards according to claim 1, characterized in that, The step S2, in which the nano-hybrid sol is poured into the coating equipment, includes the following steps: The nano-hybrid sol was prepared at a depth of 1.5-3.0 m. 3 Circulate and mature for 4-6 hours at a flow rate of / h; After the cycle is completed, the key parameters of the nano-hybrid sol are tested to ensure that the pH value is between 5.0 and 8.0, the solid content is between 2000 and 3000 ppm, and the viscosity is between 1.5 and 3.0 mPa·s.

4. The method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards according to claim 1, characterized in that, The S3 step, which involves spraying the nano-hybrid sol onto the copper foil using a spraying process, specifically includes the following steps: The prepared nano-hybrid sol is injected into the spraying chamber through a spraying device, and the distance between the nozzle and the copper foil surface is set to 3-5 cm. Adjust the spraying flow rate to ensure that the nano-hybrid sol is evenly sprayed onto the copper foil surface, forming a coating with uniform wet film thickness; During the spraying process, maintain the copper foil linear speed at 2-10 m / min.

5. A method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards according to claim 4, characterized in that, The spraying flow rate is 1.5-3.0 m. 3 / h, with a coating thickness of 5-10μm.

6. The method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards according to claim 1, characterized in that, The roller coating process in step S4, which involves evenly applying the sprayed coating, specifically includes the following steps: The coated copper foil is placed in a roller coating machine, and the roller pressure between the roller and the copper foil is controlled within the range of 0.5-1.5 MPa. Set the roller coating speed to 2-5 m / s and keep the roller coating direction the same as the spraying direction to ensure uniform coating distribution; The coating thickness is monitored regularly during the roll coating process to ensure that the final coating thickness is between 5-10 μm.

7. The method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards according to claim 1, characterized in that, After the coating is applied evenly, the coated copper foil is inspected to check for bubbles or defects on the coating surface.

8. The method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards according to claim 1, characterized in that, The drying process of the coating in the oven in step S5 specifically includes the following steps; Place the coated copper foil into a temperature-controlled oven, set the oven temperature to 80-90℃, and dry it at this temperature for 60-90 seconds. After initial drying, raise the temperature to 120-140℃ for complete curing, which takes 90-120 seconds.

9. A method for improving the adhesion of copper foil to rollers in TPI flexible circuit boards according to claim 1, characterized in that, The specific operation of equipment cleaning in step S6 includes the following steps; After the coating is dried, immediately drain the remaining solution from the coating equipment to ensure that no impurities or solvents remain in the equipment. The coating equipment is rinsed repeatedly with deionized water, at least three times, to ensure the cleanliness of the equipment. The coating equipment is treated with a weak acid solution with a concentration of 0.1-0.5M for 10-20 minutes to remove any possible residual chemicals.

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