An ultra-low profile hvlp copper foil and a method for manufacturing the same

Abstract

This invention relates to the field of copper foil preparation technology, specifically disclosing an ultra-low profile (HVLP) copper foil and its preparation method. The preparation method of the HVLP copper foil includes: adding functionalized gelatin to a raw foil electrolyte for electrodeposition to obtain a raw foil; sequentially subjecting the raw foil to activation treatment, roughening treatment, surface protection treatment, anti-oxidation treatment, and coupling treatment to obtain the ultra-low profile HVLP copper foil. The coupling treatment uses a coupling treatment solution containing a non-silicone coupling agent. The functionalized gelatin in the raw foil electrolyte can regulate the copper ion deposition behavior, improve the surface morphology of the copper foil, and reduce surface roughness; the non-silicone coupling agent can improve the surface anchoring ability of the copper foil and the interfacial bonding stability with the resin substrate. The copper foil obtained by this invention has the characteristics of low surface roughness and good interfacial bonding performance, and is suitable for high-frequency and high-speed copper-clad laminates, low-dissipation printed circuit boards, and high-speed transmission circuit boards.

Description

Technical Field

[0001] This invention relates to the field of copper foil preparation technology, and more specifically, to an ultra-low profile HVLP copper foil and its preparation method. Background Technology

[0002] With the development of high-frequency and high-speed signal transmission, fine circuit processing, and the trend towards thinner and lighter electronic products, higher requirements are being placed on the surface profile, heat resistance, oxidation resistance, and bonding performance with resin substrates of copper foil. Ultra-low profile (HVLP) copper foil, due to its lower surface roughness, lower high-frequency signal transmission loss, and better processing adaptability, has become an important development direction for copper foil used in high-frequency and high-speed copper-clad laminates.

[0003] Existing HVLP copper foils typically achieve performance control through optimization of the green foil electrodeposition process and subsequent surface treatment processes. However, existing preparation techniques still have the following problems: On the one hand, during the green foil preparation process, the additives have limited effect on controlling the copper deposition morphology, which can easily lead to uneven crystallization, high profile, or increased surface defects on the copper foil surface, making it difficult to obtain ultra-low profile copper foils; on the other hand, the lack of matching between subsequent roughening, surface protection, anti-oxidation, and coupling treatments can easily cause unstable bonding of the copper foil surface treatment layer, thereby affecting the heat resistance, oxidation resistance, and peel strength between the copper foil and the resin substrate.

[0004] Therefore, there is an urgent need to develop an ultra-low profile HVLP copper foil and its preparation method that can take into account ultra-low surface profile, surface treatment stability and comprehensive performance. Summary of the Invention

[0005] To address the problems in existing technologies such as insufficient surface profile control during the forming process of HVLP copper foil, poor stability of subsequent surface treatment layers, and difficulty in achieving comprehensive performance of copper foil, this invention provides an ultra-low profile HVLP copper foil and its preparation method.

[0006] In a first aspect, the present invention provides a method for preparing ultra-low profile (HVLP) copper foil, employing the following technical solution: A method for preparing ultra-low profile (HVLP) copper foil includes the following steps: S1. Inject the raw foil electrolyte into the electrolytic cell, use a titanium cathode roller as the cathode and DSA as the anode to perform electrodeposition. After electrodeposition, peel off and wash with water to obtain the original foil. S2. The original foil is subjected to activation treatment, roughening treatment, surface protection treatment, anti-oxidation treatment and coupling treatment in sequence to obtain the treated original foil; S3. Wash the treated original foil with water, dry it, cool it and roll it up to obtain ultra-low profile HVLP copper foil. The electrolyte for the raw foil includes copper sulfate pentahydrate, sulfuric acid, hydrochloric acid, benzotriazole, and functionalized gelatin; the functionalized gelatin is prepared by grafting gelatin with histamine and taurine.

[0007] Preferably, the concentrations of each component in the foil electrolyte in step S1 are: copper sulfate pentahydrate 260-280 g / L, sulfuric acid 100-120 g / L, hydrochloric acid 25-35 mg / L, benzotriazole 0.3-0.5 mg / L, and functionalized gelatin 80-100 mg / L.

[0008] Preferably, the method for preparing the functionalized gelatin includes the following steps: A1. Add gelatin to MES buffer, stir until completely dissolved, cool to room temperature, add N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, stir to react, and obtain the activation solution; A2. Add histamine to deionized water, adjust the pH of the system to 5.8-6.2, stir evenly, and then add it dropwise to the activation solution. After the addition is complete, continue stirring the reaction to obtain the imidazole functional gelatin reaction solution. A3. Add taurine to deionized water, adjust the pH of the system to 6-6.5, stir evenly, and then add it dropwise to the imidazole functionalized gelatin reaction solution. After the addition is complete, continue stirring the reaction. After the reaction is complete, cool, dialyze, and dry to obtain functionalized gelatin.

[0009] Preferably, in step A1, the mass ratio of gelatin, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and MES buffer is 1:0.06-0.10:0.10-0.18:20-30.

[0010] Preferably, in step A1, stirring until completely dissolved means stirring for 1-2 hours at a temperature of 45-55℃ and a rotation speed of 300-500 r / min until completely dissolved.

[0011] Preferably, the stirring reaction in step A1 refers to stirring the reaction for 50-60 minutes at room temperature and a rotation speed of 400-600 r / min.

[0012] Preferably, the mass ratio of histamine, deionized water and activation solution in step A2 is 1:10-15:180-220.

[0013] Preferably, the term "stirring evenly" in step A2 refers to stirring for 20-30 minutes at room temperature and a rotation speed of 300-500 r / min.

[0014] Preferably, in step A2, the continued stirring reaction means continuing the stirring reaction for 3-4 hours at a temperature of 30-35℃ and a rotation speed of 400-600 r / min.

[0015] Preferably, the mass ratio of taurine, deionized water and imidazole functional gelatin reaction solution in step A3 is 1:10-15:200-300.

[0016] Preferably, the term "stirring evenly" in step A3 refers to stirring for 20-30 minutes at a temperature of 25-35℃ and a rotation speed of 300-500 r / min.

[0017] Preferably, in step A3, the continued stirring reaction means continuing the stirring reaction for 3-5 hours at a temperature of 35-40℃ and a rotation speed of 400-600 r / min.

[0018] Preferably, in step A3, the dialysis and drying process refers to: placing the reaction solution into a dialysis bag with a molecular weight cutoff of 8000-10000 Da, using deionized water as the dialysis medium, and dialyzing at a temperature of 4-10℃ for 48-72 hours, replacing the deionized water every 6-12 hours during this period. After dialysis, the dialyzed reaction solution is pre-frozen at a temperature of -40℃ to -50℃ for 8-10 hours to solidify, and then placed in a freeze dryer for freeze drying at a vacuum degree of 20-30 Pa and a cold trap temperature of -50℃ to -60℃ for 24-48 hours.

[0019] Preferably, electrodeposition in step S1 refers to electrodeposition at a current density of 60-66 A / dm³. 2 Electrodeposition was performed for 50-60 seconds under the conditions of a cell voltage of 6.2-7.0V and a cathode roller linear speed of 2.2-2.6m / min.

[0020] Preferably, in step S1, the peeling and washing process refers to: continuously peeling the copper foil deposited on the surface of the titanium cathode roller at room temperature and a peeling tension of 12-16N, followed by a two-stage spray washing with deionized water at a temperature of 26-30℃, a spraying pressure of 0.18-0.22MPa, a washing time of 6-8s per stage, and a total washing time of 12-16s.

[0021] Preferably, in step S2, a primary water wash is performed between adjacent processing steps. The primary water wash refers to: using deionized water to perform a primary spray water wash on the original foil, with a water washing temperature of 26-30℃, a spray pressure of 0.10-0.18MPa, and a water washing time of 6-8s.

[0022] Preferably, the activation treatment in step S2 refers to: placing the original foil in an activation treatment solution and activating it for 12-20 seconds at a temperature of 26-30℃ and a rotation speed of 220-280r / min; the concentration of sulfuric acid in the activation treatment solution is 48-55g / L and the concentration of hydrogen peroxide is 3-4g / L.

[0023] Preferably, the roughening treatment in step S2 refers to: placing the activated foil in a roughening treatment solution at a temperature of 31-34℃ and a current density of 10-14 A / dm³. 2 The roughening treatment was carried out under the following conditions for 6-10 seconds; the concentrations of each component in the roughening treatment solution were: copper sulfate pentahydrate 28-32 g / L, sulfuric acid 95-105 g / L, and hydrochloric acid 22-28 mg / L.

[0024] Preferably, the surface protection treatment in step S2 refers to: placing the roughened original foil in a surface protection solution, and applying it at a temperature of 29-32℃ and a current density of 1.0-1.4 A / dm³. 2 The surface is treated for 6-8 seconds under the following conditions; the concentrations of each component in the surface protection solution are: zinc sulfate 8-10 g / L, nickel sulfate 11-14 g / L, sodium citrate 20-24 g / L; the pH of the surface protection solution is 4.3-4.8.

[0025] Preferably, the anti-oxidation treatment in step S2 refers to: placing the original foil after surface protection treatment in an anti-oxidation treatment solution and treating it at a temperature of 30-34℃ for 20-25 seconds; the concentrations of each component in the anti-oxidation treatment solution are: benzotriazole 0.8-1.2 g / L, sodium molybdate 1.0-1.5 g / L, and sodium dihydrogen phosphate 0.5-1.0 g / L; the pH of the anti-oxidation treatment solution is 5.2-5.8.

[0026] Preferably, the coupling treatment in step S2 refers to: placing the original foil after anti-oxidation treatment in a coupling treatment solution and coupling treatment at a temperature of 35-40℃ for 20-30s; the concentration of the non-silicone coupling agent in the coupling treatment solution is 0.6-1.0g / L, the volume fraction of anhydrous ethanol is 6-10%; and the pH of the coupling treatment solution is 4.8-5.4.

[0027] Preferably, the preparation method of the non-silicon coupling agent includes the following steps: 4-Aminophenylphosphonic acid was added to a mixed solvent, the pH of the system was adjusted to 7.5-8.2, and the mixture was stirred until homogeneous. Then, 2-naphthol and formaldehyde aqueous solution were added, and the mixture was stirred to react. After the reaction was completed, the mixture was cooled and post-treated to obtain a non-silicon coupling agent.

[0028] Preferably, the mass ratio of the 4-aminophenylphosphonic acid, 2-naphthol, formaldehyde aqueous solution and mixed solvent is 1:0.8-0.9:0.9-1:9-10.

[0029] Preferably, the formaldehyde aqueous solution has a mass fraction of 37%.

[0030] Preferably, the mixed solvent is composed of anhydrous ethanol and deionized water in a volume ratio of 3-4:1.

[0031] Preferably, the term "uniform stirring" refers to stirring for 30-40 minutes at a temperature of 30-40℃ and a rotation speed of 400-600 r / min.

[0032] Preferably, the stirring reaction refers to: first stirring the reaction at a temperature of 35-45℃ and a speed of 400-600r / min for 50-60 minutes, then raising the temperature to 75-82℃ and continuing the stirring reaction at a speed of 400-600r / min for 6-8 hours.

[0033] Preferably, the post-treatment refers to: cooling the reaction solution to 45-50°C, concentrating it under reduced pressure to 1 / 3 of the reaction solution volume at a temperature of 45-50°C and a vacuum degree of -0.06MPa to -0.09MPa; then cooling the residue to room temperature, adjusting the pH to 5.0-5.6 using a 10% acetic acid aqueous solution, stirring for 30-50 minutes at a temperature of 5-10°C and a rotation speed of 300-500 r / min to precipitate the precipitate, filtering it using a polypropylene filter cloth with a pore size of 3-5μm under a vacuum degree of 0.04-0.08MPa, washing the filter cake 2-3 times each with anhydrous ethanol and deionized water, and drying it at a temperature of 40-50°C for 12-24 hours.

[0034] Preferably, the drying after washing in step S3 refers to: the treated original foil being subjected to a two-stage spray washing with deionized water, with a spray pressure of 0.10-0.18 MPa, a washing temperature of 26-30℃, a washing time of 5-8 seconds for each stage, and a total washing time of 10-16 seconds. After washing, it is dried with hot air at a temperature of 68-75℃ for 80-90 seconds.

[0035] Preferably, in step S3, cooling and winding refers to: cooling the dried original foil to 25-30°C using a cooling roller, wherein the surface temperature of the cooling roller is 18-22°C and the cooling time is 10-20s; and then winding is performed under the conditions of winding tension of 12-18N and winding speed of 2.2-2.8m / min.

[0036] Secondly, the present invention provides an ultra-low profile HVLP copper foil, which adopts the following technical solution: An ultra-low profile HVLP copper foil prepared by the above-mentioned method.

[0037] In summary, the present invention has the following beneficial effects: 1. This invention introduces functionalized gelatin into the electrolyte of raw copper foil, utilizing the imidazole and sulfonic acid groups in its molecules to regulate the copper electrodeposition process. The imidazole groups enhance the adsorption of additive molecules on the cathode surface, regulating the reductive deposition behavior of copper ions; the sulfonic acid groups improve its dispersibility and stability in acidic electrolytes. The synergistic effect of these two groups inhibits abnormal growth of copper grains and localized protrusions, thereby reducing the surface roughness of the deposited layer and improving the density and uniformity of the copper foil surface.

[0038] 2. This invention achieves synergistic regulation of the surface structure and chemical state of the original foil by sequentially performing activation, roughening, surface protection, anti-oxidation, and coupling treatments. Specifically, the activation treatment removes oxides and residual electrolytes from the original foil surface, ensuring the bonding stability between the subsequent treatment layers and the copper substrate; the roughening treatment increases the effective bonding area of ​​the surface by forming a fine, uniform, and controllable micro-nodular structure without excessively increasing the surface profile; and the surface protection and anti-oxidation treatments further stabilize the surface structure of the original foil. Therefore, this invention improves the interfacial bonding strength between the copper foil and the resin substrate while maintaining ultra-low surface roughness of the copper foil.

[0039] 3. This invention uses a coupling treatment solution containing a non-silicone coupling agent to modify the surface of copper foil. The non-silicone coupling agent contains phosphonic acid groups, which can stably bind to the surface of the copper foil or the surface protective layer. Simultaneously, its aromatic structure and polar functional groups enhance the interaction between it and the resin substrate, thereby forming a stable interfacial transition layer between the copper foil and the resin. Compared with conventional silane coupling systems, this non-silicone coupling agent is less prone to problems such as uncontrolled condensation polymerization or insufficient hydrolytic stability, which helps to further improve the consistency, heat resistance, and long-term bonding reliability of the interfacial treatment, and enhance the interfacial bonding strength between the copper foil and the resin substrate. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 Figure 1 shows the SEM images of the ultra-low profile HVLP copper foil prepared in Example 1 of this invention; Figure (a) is the overall surface morphology at 2000× magnification; Figure (b) is the local surface micromorphology at 5000× magnification. Detailed Implementation

[0042] The following will combine Figure 1 The technical solutions of the present invention have been clearly and completely described in the accompanying embodiments. 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.

[0043] The specific parameters of the raw materials used in this invention are as follows: MES buffer: Catalog number: T16975, purchased from Shanghai Shangbao Biotechnology Co., Ltd.; 4-Aminophenylphosphonic acid: CAS No.: 5337-17-7, purchased from Hubei Chengfeng Chemical Co., Ltd.; Modified polyphenylene ether resin: Model: XH6121INBMPH, purchased from Dongguan Shenghao Plastic Raw Materials Co., Ltd.

[0044] Examples 1-3 provide an ultra-low profile HVLP copper foil and its preparation method.

[0045] Example 1

[0046] The preparation method of functionalized gelatin includes the following steps: A1. The mass ratio of gelatin, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and MES buffer was controlled at 1:0.06:0.10:20. Gelatin was added to MES buffer (0.5M; pH 6.0) and stirred for 2 hours at 45℃ and 300 rpm until completely dissolved. After cooling to room temperature, N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were added and stirred for 60 minutes at room temperature and 400 rpm to obtain the activated solution. A2. Control the mass ratio of histamine, deionized water and activation solution to 1:10:180. Add histamine to deionized water and adjust the pH of the system to 5.8 using a 10% acetic acid aqueous solution. Stir for 30 min at room temperature and 300 r / min, then add it dropwise to the activation solution over a time of 20 min. After the addition is complete, continue stirring the reaction at 30℃ and 400 r / min for 4 h to obtain the imidazole functional gelatin reaction solution. A3. Control the mass ratio of taurine, deionized water, and imidazole functional gelatin reaction solution to 1:10:200. Add taurine to deionized water and adjust the pH of the system to 6 using 10% ammonia. Stir for 30 minutes at 25℃ and 300 r / min, then add it dropwise to the imidazole functional gelatin reaction solution over a time of 40 minutes. After the addition is complete, continue stirring for 5 hours at 35℃ and 400 r / min. After the reaction is complete, cool to room temperature and place the reaction solution into a dialysis bag with a molecular weight cutoff of 8000 Da. Dialyze at 4℃ for 72 hours using deionized water as the dialysis medium, changing the deionized water every 12 hours. After dialysis, pre-freeze the dialyzed reaction solution at -40℃ for 10 hours to solidify it, then place it in a freeze dryer and freeze-dry for 48 hours under a vacuum of 20 Pa and a cold trap temperature of -50℃ to obtain functionalized gelatin. The preparation method of the non-silicon coupling agent includes the following steps: The mass ratio of 4-aminophenylphosphonic acid, 2-naphthol, formaldehyde aqueous solution, and mixed solvent was controlled at 1:0.8:0.9:9. 4-Aminophenylphosphonic acid was added to the mixed solvent (composed of anhydrous ethanol and deionized water in a volume ratio of 3:1). The pH of the system was adjusted to 7.5 using 10% ammonia solution. The mixture was stirred for 40 min at 30℃ and 400 rpm. Then, 2-naphthol and 37% formaldehyde aqueous solution were added. The mixture was first stirred for 60 min at 35℃ and 400 rpm, then the temperature was increased to 75℃ and the reaction was carried out at 400 rpm. The reaction was stirred for another 8 hours. After the reaction was completed, the reaction solution was cooled to 45°C and concentrated under reduced pressure to 1 / 3 of the reaction solution volume at 45°C and a vacuum of -0.06 MPa. The residue was then cooled to room temperature and the pH was adjusted to 5.0 using a 10% acetic acid aqueous solution. The mixture was stirred at 5°C and 300 r / min for 50 min to precipitate the precipitate. The precipitate was filtered under a vacuum of 0.04 MPa using a polypropylene filter cloth with a pore size of 3 μm. The filter cake was washed twice each with anhydrous ethanol and deionized water and then dried at 40°C for 24 hours to obtain the non-silicon coupling agent. A method for preparing ultra-low profile (HVLP) copper foil includes the following steps: S1. The electrolyte for the raw foil (concentrations of each component are: copper sulfate pentahydrate 260 g / L, sulfuric acid 100 g / L, hydrochloric acid 25 mg / L, benzotriazole 0.3 mg / L, functionalized gelatin 80 mg / L) is injected into the electrolytic cell, with a titanium cathode roller as the cathode and DSA as the anode, at a current density of 60 A / dm³. 2Electrodeposition was performed for 60 seconds under the conditions of a tank voltage of 6.2V and a cathode roller linear speed of 2.2m / min. After electrodeposition, the copper foil deposited on the surface of the titanium cathode roller was continuously peeled off at room temperature and a peel tension of 12N. Then, it was washed with deionized water in two stages at a temperature of 26℃ and a spray pressure of 0.18MPa. Each stage of washing lasted for 8 seconds, and the total washing time was 16 seconds, to obtain the original foil. S2. Place the original foil in an activation treatment solution (the concentration of sulfuric acid in the activation treatment solution is 48 g / L, and the concentration of hydrogen peroxide is 3 g / L), and activate it for 20 s at a temperature of 26℃ and a rotation speed of 220 r / min. Then place the activated original foil in a roughening treatment solution (the concentrations of each component are: copper sulfate pentahydrate 28 g / L, sulfuric acid 95 g / L, and hydrochloric acid 22 mg / L), and activate it at a temperature of 31℃ and a current density of 10 A / dm³. 2 The raw foil was roughened for 10 seconds under the following conditions: The roughened foil was then placed in a surface protection solution (concentrations of components: zinc sulfate 8 g / L, nickel sulfate 11 g / L, sodium citrate 20 g / L; pH of the surface protection solution was 4.3), and subjected to a temperature of 29℃ and a current density of 1.0 A / dm³. 2 The original foil was surface-treated for 8 seconds under the following conditions: After surface protection treatment, the original foil was placed in an anti-oxidation treatment solution (the concentrations of each component were: benzotriazole 0.8 g / L, sodium molybdate 1.0 g / L, sodium dihydrogen phosphate 0.5 g / L; the pH of the anti-oxidation treatment solution was 5.2) and treated at 30℃ for 25 seconds; After anti-oxidation treatment, the original foil was placed in a coupling treatment solution (the concentration of non-silicone coupling agent in the coupling treatment solution was 0.6 g / L, the volume fraction of anhydrous ethanol was 6%; the pH of the coupling treatment solution was 4.8) and coupled at 35℃ for 30 seconds; A primary water wash was performed between adjacent treatment steps, using deionized water for a primary spray wash at a temperature of 26℃, a spray pressure of 0.10 MPa, and a washing time of 8 seconds; after the treatment, the treated original foil was obtained. S3. The treated foil is subjected to a two-stage spray washing with deionized water at a spray pressure of 0.10 MPa and a washing temperature of 26°C. Each stage of washing lasts for 8 seconds, and the total washing time is 16 seconds. After washing, the foil is dried with hot air at 68°C for 90 seconds. The dried foil is then cooled to 25°C by a cooling roller with a surface temperature of 18°C ​​for 10 seconds. Subsequently, the foil is wound up at a winding tension of 12 N and a winding speed of 2.2 m / min to obtain ultra-low profile HVLP copper foil.

[0047] Example 2

[0048] The preparation method of functionalized gelatin includes the following steps: A1. The mass ratio of gelatin, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and MES buffer was controlled at 1:0.08:0.14:25. Gelatin was added to MES buffer (0.5M; pH 6.0) and stirred at 50℃ and 400 r / min for 1.5 h until completely dissolved. After cooling to room temperature, N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were added and stirred at room temperature and 500 r / min for 55 min to obtain the activated solution. A2. Control the mass ratio of histamine, deionized water and activation solution to 1:13:200. Add histamine to deionized water and adjust the pH of the system to 6 using a 10% acetic acid aqueous solution. Stir for 25 minutes at room temperature and 400 r / min. Then add it dropwise to the activation solution, controlling the dropwise addition time to 25 minutes. After the dropwise addition is completed, continue stirring the reaction at 32℃ and 500 r / min for 3.5 hours to obtain the imidazole functional gelatin reaction solution. A3. Control the mass ratio of taurine, deionized water, and imidazole functional gelatin reaction solution to 1:13:250. Add taurine to deionized water and adjust the pH of the system to 6.2 using 10% ammonia. Stir for 25 minutes at 30℃ and 400 r / min, then add it dropwise to the imidazole functional gelatin reaction solution over a time of 45 minutes. After the addition is complete, continue stirring for 4 hours at 38℃ and 500 r / min. After the reaction is complete, cool to room temperature and place the reaction solution into a dialysis bag with a molecular weight cutoff of 9000 Da. Dialyze at 7℃ for 60 hours using deionized water as the dialysis medium, changing the deionized water every 9 hours. After dialysis, pre-freeze the dialyzed reaction solution at -45℃ for 9 hours to solidify it, then place it in a freeze dryer and freeze-dry for 36 hours under a vacuum of 25 Pa and a cold trap temperature of -55℃ to obtain functionalized gelatin. The preparation method of the non-silicon coupling agent includes the following steps: The mass ratio of 4-aminophenylphosphonic acid, 2-naphthol, formaldehyde aqueous solution, and mixed solvent was controlled at 1:0.85:0.95:9.5. 4-Aminophenylphosphonic acid was added to the mixed solvent (composed of anhydrous ethanol and deionized water in a volume ratio of 3.5:1). The pH of the system was adjusted to 8 using 10% ammonia solution. The mixture was stirred for 35 min at 35°C and 500 rpm. Then, 2-naphthol and 37% formaldehyde aqueous solution were added. The mixture was first stirred for 55 min at 40°C and 500 rpm, and then the temperature was increased to 78°C and the mixture was stirred at 500 rpm. The reaction was continued under stirring for 7 hours. After the reaction was completed, the reaction solution was cooled to 48°C and concentrated under reduced pressure to 1 / 3 of the reaction solution volume at 48°C and a vacuum of -0.08 MPa. The residue was then cooled to room temperature and the pH was adjusted to 5.3 using a 10% acetic acid aqueous solution. The mixture was stirred at 8°C and 400 r / min for 40 min to precipitate the precipitate. The precipitate was filtered under a vacuum of 0.06 MPa using a polypropylene filter cloth with a pore size of 4 μm. The filter cake was washed three times each with anhydrous ethanol and deionized water and then dried at 45°C for 18 hours to obtain the non-silicon coupling agent. A method for preparing ultra-low profile (HVLP) copper foil includes the following steps: S1. The electrolyte for the raw foil (concentrations of each component are: copper sulfate pentahydrate 270 g / L, sulfuric acid 110 g / L, hydrochloric acid 30 mg / L, benzotriazole 0.4 mg / L, functionalized gelatin 90 mg / L) is injected into the electrolytic cell, with a titanium cathode roller as the cathode and DSA as the anode, at a current density of 63 A / dm³. 2 Electrodeposition was performed for 55 seconds under the conditions of a tank voltage of 6.6V and a cathode roller linear speed of 2.4m / min. After electrodeposition, the copper foil deposited on the surface of the titanium cathode roller was continuously peeled off at room temperature and a peel tension of 14N. Then, it was washed with deionized water in two stages at a temperature of 28℃ and a spray pressure of 0.2MPa. Each stage of washing lasted for 7 seconds, and the total washing time was 14 seconds to obtain the original foil. S2. The original foil was placed in an activation treatment solution (the concentration of sulfuric acid in the activation treatment solution was 51 g / L, and the concentration of hydrogen peroxide was 3.5 g / L), and activated for 16 s at a temperature of 28℃ and a rotation speed of 250 r / min. The activated original foil was then placed in a roughening treatment solution (the concentrations of each component were: copper sulfate pentahydrate 30 g / L, sulfuric acid 100 g / L, and hydrochloric acid 25 mg / L), and activated at a temperature of 33℃ and a current density of 12 A / dm³. 2The raw foil was roughened for 8 seconds under the following conditions: The roughened foil was then placed in a surface protection solution (concentrations of components: zinc sulfate 9 g / L, nickel sulfate 12.5 g / L, sodium citrate 22 g / L; pH of the surface protection solution was 4.5), and subjected to a temperature of 30℃ and a current density of 1.2 A / dm³. 2 The original foil was surface-treated for 7 seconds under the following conditions: The surface-protected foil was then placed in an anti-oxidation treatment solution (the concentrations of each component were: benzotriazole 1 g / L, sodium molybdate 1.3 g / L, sodium dihydrogen phosphate 0.8 g / L; the pH of the anti-oxidation treatment solution was 5.5) and treated at 32℃ for 23 seconds; The anti-oxidation treated foil was then placed in a coupling treatment solution (the concentration of the non-silicone coupling agent in the coupling treatment solution was 0.8 g / L, the volume fraction of anhydrous ethanol was 8%; the pH of the coupling treatment solution was 5) and coupled at 38℃ for 25 seconds; A primary water wash was performed between adjacent treatment steps, using deionized water for a primary spray wash at a temperature of 28℃, a spray pressure of 0.14 MPa, and a washing time of 7 seconds; After the treatment, the treated original foil was obtained. S3. The treated foil is subjected to a two-stage spray washing with deionized water at a spray pressure of 0.14 MPa and a washing temperature of 28°C. Each stage of washing lasts for 7 seconds, and the total washing time is 14 seconds. After washing, the foil is dried with hot air at 71°C for 85 seconds. The dried foil is then cooled to 28°C by a cooling roller with a surface temperature of 20°C for 15 seconds. Subsequently, the foil is wound up at a winding tension of 15 N and a winding speed of 2.5 m / min to obtain ultra-low profile HVLP copper foil.

[0049] Example 3

[0050] The preparation method of functionalized gelatin includes the following steps: A1. The mass ratio of gelatin, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and MES buffer was controlled at 1:0.10:0.18:30. Gelatin was added to MES buffer (molar concentration of 0.1 mol / L; pH 6.0) and stirred at 55℃ and 500 r / min for 1 h until completely dissolved. After cooling to room temperature, N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were added and stirred at room temperature and 600 r / min for 50 min to obtain the activated solution. A2. Control the mass ratio of histamine, deionized water and activation solution to 1:15:220. Add histamine to deionized water and adjust the pH of the system to 6.2 using a 10% acetic acid aqueous solution. Stir for 20 minutes at room temperature and 500 r / min. Then add it dropwise to the activation solution, controlling the dropwise addition time to 30 minutes. After the dropwise addition is completed, continue stirring the reaction for 3 hours at 35℃ and 600 r / min to obtain the imidazole functional gelatin reaction solution. A3. Control the mass ratio of taurine, deionized water, and imidazole functional gelatin reaction solution to 1:15:300. Add taurine to deionized water and adjust the pH of the system to 6.5 using 10% ammonia. Stir for 20 minutes at 35℃ and 500 r / min, then add it dropwise to the imidazole functional gelatin reaction solution over a time of 50 minutes. After the addition is complete, continue stirring for 3 hours at 40℃ and 600 r / min. After the reaction is complete, cool to room temperature and place the reaction solution into a dialysis bag with a molecular weight cutoff of 10000 Da. Dialyze at 10℃ for 48 hours using deionized water as the dialysis medium, changing the deionized water every 6 hours. After dialysis, pre-freeze the dialyzed reaction solution at -50℃ for 8 hours to solidify it, then place it in a freeze dryer and freeze-dry for 24 hours under a vacuum of 30 Pa and a cold trap temperature of -60℃ to obtain functionalized gelatin. The preparation method of the non-silicon coupling agent includes the following steps: The mass ratio of 4-aminophenylphosphonic acid, 2-naphthol, formaldehyde aqueous solution, and mixed solvent was controlled at 1:0.9:1:10. 4-Aminophenylphosphonic acid was added to the mixed solvent (composed of anhydrous ethanol and deionized water in a volume ratio of 4:1). The pH of the system was adjusted to 8.2 using 10% ammonia solution. The mixture was stirred for 30 min at 40℃ and 600 r / min. Then, 2-naphthol and 37% formaldehyde aqueous solution were added. The mixture was first stirred for 50 min at 45℃ and 600 r / min, then the temperature was increased to 82℃ and the reaction continued at 600 r / min. The reaction was stirred for another 6 hours. After the reaction was completed, the reaction solution was cooled to 50°C and concentrated under reduced pressure at 50°C and a vacuum of -0.09 MPa to 1 / 3 of the reaction solution volume. The residue was then cooled to room temperature and the pH was adjusted to 5.6 using a 10% acetic acid aqueous solution. The mixture was stirred at 10°C and 500 r / min for 30 minutes to precipitate the precipitate. The precipitate was filtered under a vacuum of 0.08 MPa using a 5 μm pore size polypropylene filter cloth. The filter cake was washed three times each with anhydrous ethanol and deionized water and then dried at 50°C for 12 hours to obtain the non-silicone coupling agent. A method for preparing ultra-low profile (HVLP) copper foil includes the following steps: S1. The electrolyte for the raw foil (the concentrations of each component are: copper sulfate pentahydrate 280 g / L, sulfuric acid 120 g / L, hydrochloric acid 35 mg / L, benzotriazole 0.5 mg / L, functionalized gelatin 100 mg / L) is injected into the electrolytic cell, with a titanium cathode roller as the cathode and DSA as the anode, at a current density of 66 A / dm³. 2 Electrodeposition was performed for 50 seconds under the conditions of a tank voltage of 7.0V and a cathode roller linear speed of 2.6m / min. After electrodeposition, the copper foil deposited on the surface of the titanium cathode roller was continuously peeled off at room temperature and a peel tension of 16N. Then, it was washed with deionized water in two stages at a temperature of 30℃ and a spray pressure of 0.22MPa. Each stage of washing lasted for 6 seconds, and the total washing time was 12 seconds, to obtain the original foil. S2. Place the original foil in an activation treatment solution (the concentration of sulfuric acid in the activation treatment solution is 55 g / L, and the concentration of hydrogen peroxide is 4 g / L), and activate it for 12 s at a temperature of 30℃ and a rotation speed of 280 r / min. Then place the activated original foil in a roughening treatment solution (the concentrations of each component are: copper sulfate pentahydrate 32 g / L, sulfuric acid 105 g / L, and hydrochloric acid 28 mg / L), and activate it at a temperature of 31℃ and a current density of 14 A / dm³. 2 The foil was roughened for 6 seconds under the following conditions: The roughened foil was then placed in a surface protection solution (concentrations of components: zinc sulfate 10 g / L, nickel sulfate 14 g / L, sodium citrate 24 g / L; pH of the surface protection solution was 4.8), and subjected to a temperature of 32℃ and a current density of 1.4 A / dm³. 2 The original foil was surface-treated for 6 seconds under the following conditions: The surface-protected foil was then placed in an anti-oxidation treatment solution (the concentrations of each component were: benzotriazole 1.2 g / L, sodium molybdate 1.5 g / L, sodium dihydrogen phosphate 1.0 g / L; the pH of the anti-oxidation treatment solution was 5.8) and treated at 34℃ for 20 seconds; The anti-oxidation treated foil was then placed in a coupling treatment solution (the concentration of the non-silicone coupling agent in the coupling treatment solution was 1.0 g / L, the volume fraction of anhydrous ethanol was 10%; the pH of the coupling treatment solution was 5.4) and coupled at 40℃ for 20 seconds; A primary water wash was performed between adjacent treatment steps, using deionized water for a primary spray wash at 30℃, a spray pressure of 0.18 MPa, and a washing time of 6 seconds; After the treatment, the treated original foil was obtained. S3. The treated foil is subjected to a two-stage spray washing with deionized water at a spray pressure of 0.18 MPa and a washing temperature of 30°C. Each stage of washing lasts for 5 seconds, and the total washing time is 10 seconds. After washing, the foil is dried with hot air at 75°C for 80 seconds. The dried foil is then cooled to 30°C by a cooling roller with a surface temperature of 22°C for 20 seconds. Subsequently, the foil is wound up at a winding tension of 18 N and a winding speed of 2.8 m / min to obtain ultra-low profile HVLP copper foil.

[0051] To verify the comprehensive performance of the ultra-low profile HVLP copper foils prepared in Examples 1-3 of this invention, the inventors set up Comparative Examples 1-5, as follows: Comparative Example 1 The difference between this comparative example and Example 1 is that in the original step S1, the functionalized gelatin in the raw foil electrolyte is replaced with gelatin, while the remaining steps and raw materials are the same as in Example 1. Specifically; S1. The electrolyte for the raw foil (concentrations of each component are: copper sulfate pentahydrate 260 g / L, sulfuric acid 100 g / L, hydrochloric acid 25 mg / L, benzotriazole 0.3 mg / L, gelatin 80 mg / L) is injected into the electrolytic cell, with a titanium cathode roller as the cathode and DSA as the anode, at a current density of 60 A / dm³. 2 Electrodeposition was performed for 60 s under the conditions of a tank voltage of 6.2 V and a cathode roller linear speed of 2.2 m / min. After electrodeposition, the copper foil deposited on the surface of the titanium cathode roller was continuously peeled off at room temperature and a peel tension of 12 N. Then, a two-stage spray washing was performed using deionized water at a temperature of 26 °C and a spray pressure of 0.18 MPa. Each stage of washing lasted for 8 s, and the total washing time was 16 s, to obtain the original foil.

[0052] Comparative Example 2 The difference between this comparative example and Example 1 is that in the original step S1, the functionalized gelatin in the raw foil electrolyte is replaced with imidazole functionalized gelatin. The imidazole functionalized gelatin is obtained by dialysis and drying of the imidazole functionalized gelatin reaction solution in the original step A2. The remaining steps and raw materials are the same as in Example 1. Specifically: A2. Control the mass ratio of histamine, deionized water, and activation solution to 1:10:180. Add histamine to deionized water and adjust the pH of the system to 5.8 using a 10% acetic acid aqueous solution. Stir for 30 minutes at room temperature and 300 r / min, then add it dropwise to the activation solution over a time of 20 minutes. After the addition is complete, continue stirring for 4 hours at 30℃ and 400 r / min to obtain an imidazole functionalized gelatin reaction solution. Place the imidazole functionalized gelatin reaction solution into a dialysis bag with a molecular weight cutoff of 8000 Da and dialyze at 4℃ for 72 hours using deionized water as the dialysis medium, changing the deionized water every 12 hours. After dialysis, pre-freeze the dialyzed reaction solution at -40℃ for 10 hours to solidify it, then place it in a freeze dryer and freeze-dry it at a vacuum of 20 Pa and a cold trap temperature of -50℃ for 48 hours to obtain imidazole functionalized gelatin. S1. The electrolyte for the raw foil (the concentrations of each component are: copper sulfate pentahydrate 260 g / L, sulfuric acid 100 g / L, hydrochloric acid 25 mg / L, benzotriazole 0.3 mg / L, imidazole functionalized gelatin 80 mg / L) is injected into the electrolytic cell. A titanium cathode roller is used as the cathode and DSA is used as the anode, at a current density of 60 A / dm³. 2 Electrodeposition was performed for 60 s under the conditions of a tank voltage of 6.2 V and a cathode roller linear speed of 2.2 m / min. After electrodeposition, the copper foil deposited on the surface of the titanium cathode roller was continuously peeled off at room temperature and a peel tension of 12 N. Then, a two-stage spray washing was performed using deionized water at a temperature of 26 °C and a spray pressure of 0.18 MPa. Each stage of washing lasted for 8 s, and the total washing time was 16 s, to obtain the original foil.

[0053] Comparative Example 3 The difference between this comparative example and Example 1 is that in the original step S1, the functionalized gelatin in the raw foil electrolyte is replaced with taurine functionalized gelatin, while the remaining steps and raw materials are the same as in Example 1. Specifically: A2. Control the mass ratio of taurine, deionized water, and activation solution to 1:10:200. Add taurine to deionized water and adjust the pH of the system to 6 using 10% ammonia. Stir for 30 minutes at 25℃ and 300 r / min, then add it dropwise to the activation solution over 40 minutes. After the addition is complete, continue stirring for 5 hours at 35℃ and 400 r / min. After the reaction is complete, cool to room temperature and put the reaction solution into a dialysis bag with a molecular weight cutoff of 8000 Da. Dialyze at 4℃ for 72 hours using deionized water as the dialysis medium, changing the deionized water every 12 hours. After dialysis, pre-freeze the dialyzed reaction solution at -40℃ for 10 hours to solidify it, then place it in a freeze dryer and freeze-dry for 48 hours under a vacuum of 20 Pa and a cold trap temperature of -50℃ to obtain taurine functionalized gelatin. S1. The electrolyte for the raw foil (concentrations of each component: copper sulfate pentahydrate 260 g / L, sulfuric acid 100 g / L, hydrochloric acid 25 mg / L, benzotriazole 0.3 mg / L, taurine-functionalized gelatin 80 mg / L) is injected into the electrolytic cell. A titanium cathode roller is used as the cathode and DSA as the anode, at a current density of 60 A / dm³. 2 Electrodeposition was performed for 60 s under the conditions of a tank voltage of 6.2 V and a cathode roller linear speed of 2.2 m / min. After electrodeposition, the copper foil deposited on the surface of the titanium cathode roller was continuously peeled off at room temperature and a peel tension of 12 N. Then, a two-stage spray washing was performed using deionized water at a temperature of 26 °C and a spray pressure of 0.18 MPa. Each stage of washing lasted for 8 s, and the total washing time was 16 s, to obtain the original foil.

[0054] Comparative Example 4 The difference between this comparative example and Example 1 is that in the original step S2, the non-silicone coupling agent is replaced by an equal mass of silane coupling agent KH-550, while the remaining steps and raw materials are the same as in Example 1. Specifically: S2. Place the original foil in an activation treatment solution (the concentration of sulfuric acid in the activation treatment solution is 48 g / L, and the concentration of hydrogen peroxide is 3 g / L), and activate it for 20 s at a temperature of 26℃ and a rotation speed of 220 r / min. Then place the activated original foil in a roughening treatment solution (the concentrations of each component are: copper sulfate pentahydrate 28 g / L, sulfuric acid 95 g / L, and hydrochloric acid 22 mg / L), and activate it at a temperature of 31℃ and a current density of 10 A / dm³. 2 The raw foil was roughened for 10 seconds under the following conditions: The roughened foil was then placed in a surface protection solution (concentrations of components: zinc sulfate 8 g / L, nickel sulfate 11 g / L, sodium citrate 20 g / L; pH of the surface protection solution was 4.3), and subjected to a temperature of 29℃ and a current density of 1.0 A / dm³. 2The surface was treated for 8 seconds under the following conditions: the original foil after surface protection treatment was placed in an anti-oxidation treatment solution (the concentrations of each component were: benzotriazole 0.8 g / L, sodium molybdate 1.0 g / L, sodium dihydrogen phosphate 0.5 g / L; the pH of the anti-oxidation treatment solution was 5.2) and treated at 30℃ for 25 seconds; the original foil after anti-oxidation treatment was placed in a coupling treatment solution (the concentration of KH-550 in the coupling treatment solution was 0.6 g / L, the volume fraction of anhydrous ethanol was 6%; the pH of the coupling treatment solution was 4.8) and coupled at 35℃ for 30 seconds; between adjacent treatment steps, a primary water wash was performed, using deionized water to perform a primary spray water wash on the original foil, the water wash temperature was 26℃, the spray pressure was 0.10 MPa, and the water wash time was 8 seconds; after the treatment, the treated original foil was obtained.

[0055] Comparative Example 5 The difference between this comparative example and Example 1 is that, in the preparation of the non-silicon coupling agent, 4-aminophenylphosphonic acid was replaced with aniline by mass, while the remaining steps and raw materials were the same as in Example 1. The preparation method of the non-silicon coupling agent includes the following steps: The mass ratio of aniline, 2-naphthol, formaldehyde aqueous solution, and mixed solvent was controlled at 1:0.8:0.9:9. Aniline was added to the mixed solvent (composed of anhydrous ethanol and deionized water in a volume ratio of 3:1). The pH of the system was adjusted to 7.5 using ammonia. The mixture was stirred for 40 min at 30℃ and 400 rpm. Then, 2-naphthol and a 37% (w / w) formaldehyde aqueous solution were added. The mixture was first stirred at 35℃ and 400 rpm for 60 min, then the temperature was increased to 75℃, and the reaction was continued at 400 rpm for 8 h. After the reaction was completed, the reaction solution was cooled to 45°C and concentrated under reduced pressure to 1 / 3 of the reaction solution volume at 45°C and a vacuum of -0.06 MPa. The residue was then cooled to room temperature, and the pH was adjusted to 5.0 using a 10% acetic acid aqueous solution. The mixture was stirred at 5°C and 300 r / min for 50 min to precipitate the precipitate. The precipitate was then filtered under a vacuum of 0.04 MPa using a 3 μm pore size polypropylene filter cloth. The filter cake was washed twice each with anhydrous ethanol and deionized water, and then dried at 40°C for 24 h to obtain the non-silicon coupling agent.

[0056] Performance testing The comprehensive performance of the ultra-low profile HVLP copper foils prepared in Examples 1-3 and Comparative Examples 1-5 of this invention was tested respectively.

[0057] ① Surface roughness The tests were conducted in accordance with the following standards: GB / T 3505-2009 "Geometric Specifications for Products (GPS) - Terminology, Definitions and Surface Structure Parameters for Surface Structure Profilometry", GB / T 10610-2009 "Geometric Specifications for Products (GPS) - Rules and Methods for Evaluating Surface Structure using Surface Structure Profilometry", and GB / T 6062-2009 "Geometric Specifications for Products (GPS) - Nominal Characteristics of Contact (Stylus) Instruments for Surface Structure Profilometry". A contact surface roughness meter was used. The ultra-low profile HVLP copper foil samples prepared in Examples 1-3 and Comparative Examples 1-5 were cut into flat copper foil pieces. Before testing, the surfaces were cleaned with anhydrous ethanol and dried. Tests were performed on both sides of the copper foil, with five different locations selected on each side for measurement. The average value was taken as the surface roughness result for that side. The reported parameters are Ra and Rz, in μm.

[0058] ② Peel strength The peel strength of copper-clad laminates was tested according to IPC-TM-650 2.4.8.1-1986, "Peel Strength of Metal Foil (Keyhole Method Thin Laminate)". The ultra-low profile HVLP copper foils prepared in Examples 1-3 and Comparative Examples 1-5 were laminated with modified polyphenylene ether resin substrates and hot-pressed at 200°C and 4 MPa for 100 min to obtain copper-clad laminate samples. Subsequently, a 3 mm wide copper foil peel strip was etched. Peel strength testing was performed using a peel strength testing fixture at a speed of 5 cm / min. The results are expressed in N / mm, and the average value of 5 parallel samples was taken as the final result.

[0059] ③Volume resistivity The tests were conducted according to standard GB / T 3048.2-2007, "Test Methods for Electrical Properties of Wires and Cables - Part 2: Test for Resistivity of Metallic Materials". Ultra-low profile (HVLP) copper foils prepared in Examples 1-3 and Comparative Examples 1-5 were cut into strip-shaped specimens with a test length of 300 mm. Oil and oxides were removed from the specimen surface before testing. The four-terminal method was used to test the specimen resistance, and the volume resistivity was calculated using the formula ρ = RA / L based on the specimen length L, cross-sectional area A, and resistance value R, in μΩ·cm. Five parallel samples were used in each group, and the average value was taken as the final test result.

[0060] ④ Tensile strength The tests were conducted according to the standard GB / T 29847-2025 "Test Methods for Copper Foil for Printed Circuit Boards". The ultra-low profile (HVLP) copper foils prepared in Examples 1-3 and Comparative Examples 1-5 were cut into strips along the winding direction, with a sample size of 13mm × 150mm. The samples should be flat, without wrinkles, burrs, scratches, or obvious defects. Before testing, the sample surface was cleaned with anhydrous ethanol and dried, and then placed at a temperature of 23±2℃ and a relative humidity of 50±10% for at least 2 hours.

[0061] Tensile tests were performed using an electronic universal testing machine. When clamping the specimen, the specimen axis should be aligned with the center line of the clamp. The gauge length was 50 mm, and the tensile speed was 50 mm / min. The maximum tensile load Fmax during the specimen's fracture was recorded, and the tensile strength was calculated based on the specimen width b and thickness t using the formula: Tensile strength = Fmax / (b×t). Five parallel specimens were tested in each group, and the average value was taken as the final test result.

[0062] ⑤ Heat resistance The tests were conducted according to standard GB / T 29847-2025, "Test Methods for Copper Foil for Printed Circuit Boards". Ultra-low profile (HVLP) copper foils prepared in Examples 1-3 and Comparative Examples 1-5 were laminated with modified polyphenylene ether resin substrates and hot-pressed at 200℃ and 4MPa for 100 min to obtain copper-clad laminate samples. Samples with dimensions of 50mm × 50mm were then cut. The samples were immersed in a solder bath at 288±5℃ for 10s, removed, and cooled to room temperature, constituting one thermal shock cycle. This process was repeated until blistering, delamination, or interfacial peeling occurred. The number of thermal shock cycles the sample could withstand before delamination was recorded; if no delamination occurred after 24 cycles, it was recorded as "24 cycles without delamination". Five parallel samples were set up for each group, and the average value was taken as the final test result.

[0063] The specific test results are shown in Table 1.

[0064] Table 1: Performance parameters of ultra-low profile HVLP copper foil

[0065] As shown in Table 1, the ultra-low profile HVLP copper foils prepared in Examples 1-3 of this invention are significantly superior to Comparative Examples 1-5 in terms of surface roughness, peel strength, volume resistivity, tensile strength and heat resistance.

[0066] As shown by the data in Example 1 and Comparative Example 1, in Comparative Example 1, gelatin was used instead of functionalized gelatin. Due to the lack of imidazole and sulfonic acid groups in the gelatin molecule, the coordination adsorption capacity for copper ions, the directional adsorption capacity on the cathode surface, and the ability to control the deposited grains were weak. This resulted in uneven grain growth during the copper deposition process, an increased copper foil surface profile, and a significant increase in Ra and Rz. At the same time, the rough and uneven deposition structure reduced the surface density and interfacial bonding stability of the copper foil, leading to a decrease in the peel strength, tensile strength, and heat resistance of the copper foil.

[0067] Data from Example 1 and Comparative Example 2 show that: Comparative Example 2 uses imidazole functionalized gelatin instead of functionalized gelatin. Due to the lack of sulfonic acid groups, the gelatin molecules have insufficient dispersion stability, hydrophilicity, and uniform adsorption capacity on the cathode surface. The local concentration control effect during the copper ion deposition process is weakened, and the grain refinement and leveling effects are insufficient, resulting in increased surface roughness of the copper foil and decreased peel strength, tensile strength, and heat resistance.

[0068] As shown by the data from Example 1 and Comparative Example 3, when using taurine-functionalized gelatin instead of functionalized gelatin in Comparative Example 3, the lack of imidazole groups for the coordination adsorption of copper ions resulted in insufficient control over copper ion migration, selective crystal growth, and grain refinement. This led to a decrease in the density and uniformity of the copper deposition layer and an increase in surface roughness. At the same time, the uneven microstructure of the copper foil surface reduced the adhesion stability of subsequent surface treatment layers and coupling layers, thereby causing a decrease in the peel strength, tensile strength, and heat resistance of the copper foil.

[0069] As shown by the data from Example 1 and Comparative Example 4, in Comparative Example 4, silane coupling agent KH-550 was used instead of non-silicone coupling agent. Since KH-550 mainly relies on silanol condensation or amino action to form a bond with the interface, the synergistic interface bonding effect between the coupling treatment layer and the copper foil surface, as well as between the coupling treatment layer and the resin substrate, is weakened, resulting in a decrease in the stability of the interface bonding layer. This leads to a decrease in the peel strength between the copper foil and the resin substrate. At the same time, during thermal shock, this interface bonding layer is more prone to damage, which in turn leads to a decrease in the heat resistance of the copper foil.

[0070] As shown by the data from Example 1 and Comparative Example 5, when aniline was used to replace 4-aminophenylphosphonic acid in Comparative Example 5, the resulting coupling agent molecule lacked phosphonic acid anchoring groups, which significantly reduced its adsorption strength and film stability on the copper foil surface. The interfacial bonding layer was easily damaged under thermal shock, resulting in a significant decrease in the peel strength and heat resistance of the copper foil.

[0071] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for preparing ultra-low profile (HVLP) copper foil, characterized in that, The preparation steps include the following: S1. Inject the raw foil electrolyte into the electrolytic cell, use a titanium cathode roller as the cathode and DSA as the anode to perform electrodeposition. After electrodeposition, peel off and wash with water to obtain the original foil. S2. The original foil is subjected to activation treatment, roughening treatment, surface protection treatment, anti-oxidation treatment and coupling treatment in sequence to obtain the treated original foil; S3. Wash the treated original foil with water, dry it, cool it and roll it up to obtain ultra-low profile HVLP copper foil. The electrolyte for the raw foil includes copper sulfate pentahydrate, sulfuric acid, hydrochloric acid, benzotriazole, and functionalized gelatin; the functionalized gelatin is prepared by grafting gelatin with histamine and taurine.

2. The method for preparing ultra-low profile HVLP copper foil according to claim 1, characterized in that, The concentrations of each component in the foil electrolyte in step S1 are as follows: copper sulfate pentahydrate 260-280 g / L, sulfuric acid 100-120 g / L, hydrochloric acid 25-35 mg / L, benzotriazole 0.3-0.5 mg / L, and functionalized gelatin 80-100 mg / L.

3. The method for preparing ultra-low profile HVLP copper foil according to claim 2, characterized in that, The preparation method of the functionalized gelatin includes the following steps: A1. Add gelatin to MES buffer, stir until completely dissolved, cool to room temperature, add N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, stir to react, and obtain the activation solution; A2. Add histamine to deionized water, adjust the pH of the system to 5.8-6.2, stir evenly, and then add it dropwise to the activation solution. After the addition is complete, continue stirring the reaction to obtain the imidazole functional gelatin reaction solution. A3. Add taurine to deionized water, adjust the pH of the system to 6-6.5, stir evenly, and then add it dropwise to the imidazole functionalized gelatin reaction solution. After the addition is complete, continue stirring the reaction. After the reaction is complete, cool, dialyze, and dry to obtain functionalized gelatin.

4. The method for preparing ultra-low profile HVLP copper foil according to claim 3, characterized in that, In step A1, the mass ratio of gelatin, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and MES buffer is 1:0.06-0.10:0.10-0.18:20-30. In step A2, the mass ratio of histamine, deionized water and activation solution is 1:10-15:180-220. In step A3, the mass ratio of taurine, deionized water, and imidazole functional gelatin reaction solution is 1:10-15:200-300.

5. The method for preparing ultra-low profile HVLP copper foil according to claim 1, characterized in that, In step S1, electrodeposition refers to the process of electrodeposition at a current density of 60-66 A / dm². 2 Electrodeposition was performed for 50-60 seconds under the conditions of a cell voltage of 6.2-7.0V and a cathode roller linear speed of 2.2-2.6m / min.

6. The method for preparing ultra-low profile HVLP copper foil according to claim 1, characterized in that, The roughening treatment in step S2 refers to: placing the activated foil in a roughening treatment solution, and applying it at a temperature of 31-34℃ and a current density of 10-14A / dm². 2 The roughening treatment was carried out under the following conditions for 6-10 seconds; the concentrations of each component in the roughening treatment solution were: copper sulfate pentahydrate 28-32 g / L, sulfuric acid 95-105 g / L, and hydrochloric acid 22-28 mg / L.

7. The method for preparing ultra-low profile HVLP copper foil according to claim 1, characterized in that, The surface protection treatment in step S2 refers to: placing the roughened original foil in a surface protection solution, and applying it at a temperature of 29-32℃ and a current density of 1.0-1.4 A / dm³. 2 The surface is treated for 6-8 seconds under the following conditions; the concentrations of each component in the surface protection solution are: zinc sulfate 8-10 g / L, nickel sulfate 11-14 g / L, sodium citrate 20-24 g / L; the pH of the surface protection solution is 4.3-4.

8.

8. The method for preparing ultra-low profile HVLP copper foil according to claim 1, characterized in that, The coupling treatment in step S2 refers to: placing the original foil after anti-oxidation treatment in a coupling treatment solution and coupling treatment at a temperature of 35-40℃ for 20-30 seconds. The concentration of the non-silicone coupling agent in the coupling treatment solution is 0.6-1.0 g / L, and the volume fraction of anhydrous ethanol is 6-10%; the pH of the coupling treatment solution is 4.8-5.

4.

9. The method for preparing ultra-low profile HVLP copper foil according to claim 8, characterized in that, The preparation method of the non-silicon coupling agent includes the following steps: 4-Aminophenylphosphonic acid was added to a mixed solvent, the pH of the system was adjusted to 7.5-8.2, and the mixture was stirred until homogeneous. Then, 2-naphthol and formaldehyde aqueous solution were added, and the mixture was stirred to react. After the reaction was completed, the mixture was cooled and post-treated to obtain a non-silicon coupling agent.

10. An ultra-low profile HVLP copper foil prepared by the method of any one of claims 1-9.

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