Additive for 1-micron electrolytic copper foil and method for producing 1-micron electrolytic copper foil

Abstract

The application discloses an additive for 1-micron electrolytic copper foil and a preparation method of the 1-micron electrolytic copper foil, which comprises the following components: 10-85 mg / L of polyethylene glycol 6000, 0.5-9 mg / L of hydroxyethyl cellulose, 3-26 mg / L of fatty alcohol polyoxyethylene ether sulfosuccinic acid monoester disodium, 20-185 mg / L of sodium hydroxymethyl sulfonate, 15-80 mg / L of polydithiopropane sulfonate sodium, 2-27 mg / L of tetrahydrothiazole thione, 0.3-9.5 mg / L of 2-mercaptobenzimidazole and 0.3-9.5 mg / L of ethylene thiourea. The application has the beneficial effect of improving the strength of the 1-micron copper foil, reducing the internal stress of the 1-micron copper foil, improving the compactness and uniformity of the 1-micron copper foil and facilitating the complete stripping of the 1-micron copper foil from the cathode surface by optimizing the additive process.

Description

Technical Field

[0001] This invention relates to the field of electrolytic copper foil technology, and more particularly to additives for 1-micron electrolytic copper foil and a method for preparing 1-micron electrolytic copper foil. Background Technology

[0002] Copper foil is a thin material made of copper. Due to its excellent electrical and thermal conductivity, ductility, corrosion resistance, and shielding properties, it is widely used in industrial fields. Copper foil plays a crucial role in lithium batteries and printed circuit boards (PCBs).

[0003] Copper foil serves as the negative electrode current collector in lithium-ion batteries and is an important component of these batteries. With the increasing penetration rate of new energy vehicles, the demand for lithium-ion batteries from new energy companies has grown. The increasing demands from lithium battery companies for high energy density, dimensional stability, efficient production, and safe use have also raised the performance requirements for copper foil materials.

[0004] Composite copper foil, as an emerging negative electrode current collector for lithium batteries, exhibits significant advantages in the lithium battery field: Its sandwich structure, with a lightweight PET or PP film in the middle layer and ultra-thin copper layers on both sides, results in a lower unit weight compared to traditional copper foil of the same thickness, significantly improving battery energy density. With the increasing demand for copper in the new energy industry, copper raw materials are expensive, while PET or PP are relatively inexpensive. Replacing traditional copper foil with composite copper foil can significantly reduce raw material costs. Furthermore, composite copper foil is less prone to puncturing the separator when the battery is impacted, effectively reducing the risk of short circuits and improving battery safety.

[0005] Currently, the mainstream process for composite copper foil is the 1+4+1 process, which consists of 1μm copper layers on both sides and a 4μm PET or PP film in the middle. Copper is deposited onto an organic substrate using magnetron sputtering to a thickness of approximately 50 nm, and then the copper layer is thickened to 1μm through electroplating. However, this process has a high initial investment cost, and the electroplating process uses a low current density, resulting in a slow production speed, which is not conducive to industrialization.

[0006] If a 1μm thick copper layer can be produced directly through electrolysis, and then the composite layer is laminated with the copper layer, the investment in magnetron sputtering equipment can be eliminated, which will help promote the industrialization of composite copper foil.

[0007] In the PCB industry, driven by technologies such as 5G communication and artificial intelligence, PCBs are developing towards higher density and thinner designs, placing higher demands on the thickness precision and conductivity of copper foil. The line width / spacing of fine-line PCBs has been reduced to below 20μm. Thin copper foil can effectively reduce signal interference between lines, improve signal transmission rates, and at the same time reduce the overall thickness and weight of the PCB, meeting the miniaturization requirements of high-end electronic devices such as smartphones and servers.

[0008] In the PCB industry, ultra-thin copper foil is usually prepared using carrier copper foil. However, as the thickness of the copper foil decreases further, the strength of the copper foil will decrease and its internal stress will increase. Therefore, it is much more difficult to peel it off from the carrier stably and completely. At the same time, a large number of pinholes are easily generated on the surface of ultra-thin copper foil. At present, there are certain difficulties in the industrialization of carrier copper foil with a thickness of less than 2μm.

[0009] Therefore, developing a method for preparing 1μm copper foil is of great practical significance for promoting the development of the PCB industry.

[0010] For example, Chinese invention patent authorization announcement number CN112226790B discloses a method for producing ultra-thin high-strength electronic copper foil, which uses 18-35 micrometer copper foil as a cathode carrier, and performs electrochemical deposition on the carrier surface in a mixture of electrolyte and additives to form an ultra-thin copper foil layer with a thickness of 2.5-5 micrometers. The ultra-thin copper foil layer of this patent also has a thickness of 2.5 micrometers, which does not reach the target value of 1 micrometer.

[0011] For example, Chinese invention patent authorization announcement number CN116043283B discloses an electrolyte for ultra-thin electrolytic copper foil, as well as the ultra-thin electrolytic copper foil and its preparation method. By controlling the components and concentrations of the electrolyte and the electrodeposition process parameters, the thickness and roughness of the copper foil are significantly reduced. The thickness of the ultra-thin electrolytic copper foil is 2.7 to 3.8 μm, which does not reach the target value of 1 micrometer.

[0012] For example, Chinese invention patent publication number CN119890322A discloses a method for preparing foil. By adhering a release film to the raw foil, the stability of the raw foil can be improved, effectively reducing the tearing problem when peeling the raw foil from the roller. Although this patent can process raw foil with a thickness of 1-2 μm, it does not mention how the 1-2 μm raw foil is prepared. Moreover, this patent uses a release film to peel the raw foil, and by adhering a release film to the raw foil, the stability of the raw foil is improved, effectively reducing the tearing problem when peeling the raw foil from the roller. Summary of the Invention

[0013] The problem this invention aims to solve is that existing 1-micron copper foil cannot be directly prepared by electrolysis, and even if 1-micron copper foil is prepared, it cannot be completely peeled off from the carrier. To address this, this invention provides an additive for 1-micron electrolytic copper foil and a method for preparing 1-micron electrolytic copper foil.

[0014] The technical solution of this invention is: an additive for 1-micron electrolytic copper foil, comprising: polyethylene glycol 6000# 10mg / L to 85mg / L, hydroxyethyl cellulose 0.5mg / L to 9mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 3mg / L to 26mg / L, sodium hydroxymethanesulfonate 20mg / L to 185mg / L, sodium polydisulfide dipropane sulfonate 15mg / L to 80mg / L, tetrahydrothiazothione 2mg / L to 27mg / L, 2-mercaptobenzimidazole 0.3mg / L to 9.5mg / L, and ethylene thiourea 0.3mg / L to 9.5mg / L.

[0015] A method for preparing 1-micron electrolytic copper foil includes the following steps: S1, preparing an additive with the following components: polyethylene glycol 6000# 10 mg / L to 85 mg / L, hydroxyethyl cellulose 0.5 mg / L to 9 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 3 mg / L to 26 mg / L, sodium hydroxymethyl sulfonate 20 mg / L to 185 mg / L, and sodium polydisulfide dipropane sulfonate 15 mg / L. ~80mg / L, tetrahydrothiazolyl 2mg / L~27mg / L, 2-mercaptobenzimidazole 0.3mg / L~9.5mg / L and ethylene thiourea 0.3mg / L~9.5mg / L; S2, titanium plate polishing: use a polishing wheel to polish the surface of the titanium plate, and then use a polishing wheel to polish and finely polish the surface of the titanium plate; S3, electrolytic foil production: prepare copper sulfate electrolyte, and mix the additives prepared in S1 into the electrolyte. Pour the mixture into a Haring tank, place the polished titanium plate and carbon plate from S2 into the Haring tank for fixation, and perform electrolytic foil production to obtain 1-micron copper foil; S4, copper foil peeling: attach cellulose acetate tape to the 1-micron copper foil on the surface of the titanium plate, use a rubber roller to flatten the cellulose acetate tape, stick the end of the cellulose acetate tape to the rubber roller, and roll the rubber roller at a uniform speed of 0.1. S5. Tape dissolution: Place the cellulose acetate tape with the 1-micron copper foil attached in an organic solvent. After the tape dissolves, take out the 1-micron copper foil and dry it.

[0016] In the above scheme, polyethylene glycol 6000#, hydroxyethyl cellulose, disodium fatty alcohol polyoxyethylene ether sulfonated succinate monoester, sodium hydroxymethyl sulfonate, sodium polydithiopropane sulfonate, tetrahydrothiazolyl thionone, 2-mercaptobenzimidazole and ethylene thiourea in S1 are dissolved in deionized water and diluted to 250 mL in a volumetric flask to obtain the corresponding additives.

[0017] In the above scheme, the polishing wheel in S2 is made of polyvinyl alcohol, with a mesh size of 180-1000 and a polishing frequency of 25Hz-50Hz; the polishing wheel is made of non-woven fabric, with a mesh size of 640-1500 and a polishing frequency of 25Hz-50Hz; and the fine polishing wheel is made of non-woven fabric, with a mesh size of 1000-2500 and a polishing frequency of 25Hz-50Hz.

[0018] In the above scheme, the titanium plate in S2 has a thickness of 5mm, a width of 6cm, and a length of 15cm. After polishing, the surface roughness of the titanium plate is Ra≤0.20μm and Rz≤2.0μm.

[0019] The copper sulfate electrolyte prepared in S3 of the above scheme has a copper ion concentration of 65 g / L to 95 g / L, a sulfuric acid concentration of 80 g / L to 170 g / L, a chloride ion concentration of 15 ppm to 30 ppm, and an electrolyte temperature of 50℃ to 60℃.

[0020] In the above scheme, the additive in S1 is added to the electrolyte prepared in S3 and stirred at a temperature of 50℃~60℃ for 30 minutes to obtain a mixture.

[0021] In the above scheme, the electrode distance between the titanium plate and the carbon plate in S3 is 10mm.

[0022] In the above scheme, the current during the electrolysis of the foil in S3 is 2A to 30A, and the electroplating time is 6s to 90s. The electroplating time is inversely proportional to the current.

[0023] The tape thickness in the above scheme is 30μm to 50μm, the tape width is 6cm, and the tape width matches the width of the titanium plate in S2.

[0024] The organic solvent used in S5 of the above scheme is a mixture of ethyl acetate and acetone, wherein the mass fraction of ethyl acetate is 20% to 45% and the mass fraction of acetone is 55% to 80%.

[0025] In the above scheme, the drying temperature of the 1-micron copper foil in S5 is 90℃, and the drying time is not less than 10 minutes.

[0026] The beneficial effects of this invention are: by optimizing the additive process, the strength of the 1-micron copper foil is improved, its internal stress is reduced, and the density and uniformity of the 1-micron copper foil are improved, which is conducive to its complete peeling from the cathode surface; by optimizing the cathode polishing process, the surface roughness of the titanium cathode plate is reduced, and the pinholes and surface defects of the 1-micron copper foil are reduced; and by providing a foil peeling process for ultra-thin copper foil, the 1-micron copper foil can be completely peeled from the cathode surface. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of applying tape to the surface of a 1-micron copper foil as described in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of peeling off a tape with 1-micron copper foil attached using a rubber roller, as described in Embodiment 1 of the present invention. Figure 3 This is a SEM image of the smooth surface of a 1-micron copper foil prepared in Example 1 of the present invention; Figure 4 This is an SEM image of a 1-micrometer copper foil cross-section prepared in Example 1 of the present invention; In the diagram: 1. Titanium plate; 2. 1μm copper foil; 3. Cellulose acetate tape; 4. Glue roller. Detailed Implementation

[0028] To facilitate understanding of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0029] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0030] Unless otherwise specified, all raw materials used in this invention are purchased commercially.

[0031] Example 1: As Figures 1-4 As shown, the method for preparing 1-micron copper foil according to the present invention includes the following steps: Step S1: Prepare the additive solution with the following concentrations: polyethylene glycol 6000# 50 mg / L, hydroxyethyl cellulose 2 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 15 mg / L, sodium hydroxymethanesulfonate 120 mg / L, sodium polydisulfide dipropane sulfonate 50 mg / L, tetrahydrothiazolyl thionone 10 mg / L, 2-mercaptobenzimidazole 4 mg / L, and ethylene thiourea 4 mg / L. The polyethylene glycol 6000# mentioned above refers to polyethylene glycol 6000 with CAS number 25322-68-3.

[0032] Step S2: Select a titanium plate with a thickness of 5mm, a width of 6cm, and a length of 15cm. Grind the titanium plate with a 600-grit PVA polishing wheel at a frequency of 35Hz. After grinding, polish the titanium plate with a 1200-grit non-woven polishing wheel at a frequency of 35Hz, and then polish it again with a 2000-grit non-woven polishing wheel at a frequency of 35Hz. After polishing, the surface roughness of the titanium plate is Ra=0.116μm and Rz=1.232μm.

[0033] Step S3: Prepare copper sulfate electrolyte, wherein Cu 2+ Concentration of 80 g / L, SO4 2- The concentration is 140 g / L, Cl - The concentration was 20 ppm, and the electrolyte temperature was 55℃. The prepared additive solution was mixed into the electrolyte and stirred at 55℃ for 30 minutes to obtain a mixture, which was then poured into a Haring tank. A carbon plate and a polished titanium plate (from step S2) were placed in the Haring tank and fixed, with a 10 mm electrode distance between them. The titanium plate was used as the cathode, and the carbon plate as the anode for electrolytic plating of the green foil at a current of 5 A for 36 seconds. After plating, the titanium plate was removed, yielding a titanium plate coated with 1 μm copper foil. A photograph of the 1 μm copper foil showed good surface uniformity and a rough surface gloss of 325 GU.

[0034] Step S4: Select a 40μm thick and 6cm wide adhesive tape. Attach one end of the tape to the edge of the wide side of the titanium plate. Slowly spread the tape along the long side using a roller, ensuring it adheres to the copper foil on the titanium plate. When spreading the tape, ensure there are no air gaps between the tape and the copper foil, achieving complete adhesion. Once the tape is fully adhered to the copper foil, attach the end of the tape to the roller and slowly roll the roller at a speed of 0.4mm / s. The roller will then peel off the 1μm copper foil from the tape.

[0035] Step S5: Prepare a mixed organic solvent of ethyl acetate and acetone, wherein the mass fraction of ethyl acetate is 30% and the mass fraction of acetone is 70%. Place the tape with 1μm copper foil attached in the mixed organic solvent and let it stand for 110 minutes. After the tape is completely dissolved, place the 1μm copper foil in an oven and dry it at 90°C for 10 minutes to obtain a complete 1μm copper foil.

[0036] The smooth surface (the surface in contact with the titanium plate) and cross-sectional images of the 1μm copper foil prepared in this embodiment were taken using SEM. The surface of the 1μm copper foil prepared in this embodiment is free of pinholes and obvious defects, and the polishing marks of the polishing wheel can be observed.

[0037] Example 2: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: polyethylene glycol 6000# 45 mg / L, hydroxyethyl cellulose 3 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 18 mg / L, sodium hydroxymethyl sulfonate 125 mg / L, sodium polydisulfide dipropane sulfonate 50 mg / L, tetrahydrothiazolyl thionone 12 mg / L, 2-mercaptobenzimidazole 4 mg / L, and ethylene thiourea 4 mg / L.

[0038] The titanium plate used in this embodiment has a surface roughness Ra=0.120μm and Rz=1.304μm. After electroplating, the copper foil has a matte finish gloss of 314GU.

[0039] Example 3: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: polyethylene glycol 6000# 55 mg / L, hydroxyethyl cellulose 2 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 12 mg / L, sodium hydroxymethyl sulfonate 115 mg / L, sodium polydisulfide dipropane sulfonate 55 mg / L, tetrahydrothiazolyl thionone 10 mg / L, 2-mercaptobenzimidazole 3 mg / L, and ethylene thiourea 3 mg / L.

[0040] The titanium plate used in this embodiment has a surface roughness Ra=0.109μm and Rz=1.201μm. After electroplating, the copper foil has a matte finish gloss of 303GU.

[0041] Example 4: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: polyethylene glycol 6000# 10 mg / L, hydroxyethyl cellulose 0.5 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate monoester 3 mg / L, sodium hydroxymethyl sulfonate 20 mg / L, sodium polydisulfide dipropane sulfonate 15 mg / L, tetrahydrothiazolyl thionone 2 mg / L, 2-mercaptobenzimidazole 0.3 mg / L, and ethylene thiourea 0.3 mg / L.

[0042] The titanium plate used in this embodiment has a surface roughness Ra=0.114μm and Rz=1.218μm. After electroplating, the copper foil has a matte finish gloss of 252GU.

[0043] Example 5: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: polyethylene glycol 6000# 85 mg / L, hydroxyethyl cellulose 9 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate monoester 26 mg / L, sodium hydroxymethyl sulfonate 185 mg / L, sodium polydisulfide dipropane sulfonate 80 mg / L, tetrahydrothiazolyl thione 27 mg / L, 2-mercaptobenzimidazole 9.5 mg / L, and ethylene thiourea 9.5 mg / L.

[0044] The titanium plate used in this embodiment has a surface roughness Ra=0.119μm and Rz=1.233μm. After electroplating, the copper foil has a matte finish gloss of 243GU.

[0045] Example 6: The preparation process is basically the same as in Example 1, except for step S2: The titanium plate was polished using a 180-grit PVA polishing wheel at a frequency of 50 Hz. After polishing, it was polished using a 640-grit non-woven polishing wheel at a frequency of 50 Hz, and then polished again using a 1000-grit non-woven polishing wheel at a frequency of 50 Hz. After polishing, the surface roughness of the titanium plate was Ra = 0.143 μm and Rz = 1.445 μm.

[0046] In this embodiment, the surface gloss of the copper foil after electroplating is 289 GU.

[0047] Example 7: The preparation process is basically the same as in Example 1, except for step S2: The titanium plate was polished using a 1000-grit PVA polishing wheel at a frequency of 25 Hz. After polishing, it was polished using a 1500-grit non-woven polishing wheel at a frequency of 25 Hz, and then polished again using a 2500-grit non-woven polishing wheel at a frequency of 25 Hz. After polishing, the surface roughness of the titanium plate was Ra = 0.100 μm and Rz = 1.017 μm.

[0048] In this embodiment, the surface gloss of the copper foil after electroplating is 320 GU.

[0049] Example 8: The preparation process is basically the same as in Example 1, except for step S3: Cu for preparing copper sulfate electrolyte 2+ The concentration is 65 g / L, SO4 2- The concentration is 80 g / L, Cl - The concentration was 15 ppm, and the electrolyte temperature was 50°C. The prepared additive solution was mixed into the electrolyte and stirred at 50°C for 30 minutes to obtain a mixture. The electrolytic current for the green foil was 25 A, and the electroplating time was 7.2 s.

[0050] The titanium plate used in this embodiment has a surface roughness Ra=0.116μm and Rz=1.297μm. After electroplating, the copper foil has a matte finish gloss of 244GU.

[0051] Example 9: The preparation process is basically the same as in Example 1, except for step S3: Cu for preparing copper sulfate electrolyte 2+ The concentration is 95 g / L, SO42- The concentration is 170 g / L, Cl - The concentration was 30 ppm, and the electrolyte temperature was 60°C. The prepared additive solution was mixed into the electrolyte and stirred at 60°C for 30 minutes to obtain a mixture. The electrolytic current for the green foil was 2 A, and the electroplating time was 90 seconds.

[0052] The titanium plate used in this embodiment has a surface roughness Ra=0.108μm and Rz=1.195μm. After electroplating, the copper foil has a matte finish gloss of 287GU.

[0053] Example 10: The preparation process is basically the same as in Example 1, except for steps S4 and S5: The titanium plate used in this embodiment has a surface roughness Ra=0.114μm and Rz=1.244μm. After electroplating, the copper foil has a matte finish gloss of 332GU.

[0054] In this embodiment, CA tape with a thickness of 30 μm and a width of 6 cm is selected. When peeling off the foil, the tape roller is slowly rolled at a speed of 0.1 mm / s, and the tape is driven by the tape roller to peel off the 1 μm copper foil. Step S5: Prepare a mixed organic solvent of ethyl acetate and acetone, wherein the mass fraction of ethyl acetate is 20% and the mass fraction of acetone is 80%. Place the tape with the 1 μm copper foil attached in the mixed organic solvent and let it stand for 80 min.

[0055] Example 11: The preparation process is basically the same as in Example 1, except for steps S4 and S5: The titanium plate used in this embodiment has a surface roughness Ra=0.118μm and Rz=1.289μm. After electroplating, the copper foil has a matte finish gloss of 316GU.

[0056] In this embodiment, CA tape with a thickness of 50 μm and a width of 6 cm is selected. When peeling off the foil, the tape roller is slowly rolled at a speed of 0.9 mm / s, and the tape is driven by the tape roller to peel off the 1 μm copper foil. Step S5: Prepare a mixed organic solvent of ethyl acetate and acetone, wherein the mass fraction of ethyl acetate is 45% and the mass fraction of acetone is 55%. Place the tape with the 1 μm copper foil attached in the mixed organic solvent and let it stand for 180 min.

[0057] The process parameters for Examples 1-11 are shown in Table 1. For ease of representation, polyethylene glycol 6000#, hydroxyethyl cellulose, disodium sulfonated succinate monoester of fatty alcohol polyoxyethylene ether, sodium hydroxymethyl sulfonate, sodium polydithiopropane sulfonate, tetrahydrothiazolium thione, 2-mercaptobenzimidazole, and ethylene thiourea are referred to as additives A-H, respectively.

[0058]

[0059] As can be seen from the table above, the additive process, titanium plate polishing process, and ultra-thin copper foil peeling process of the present invention have certain process windows. Within the process window, a 1μm copper foil with a uniform surface and no pinholes can be obtained.

[0060] Comparative Example 1: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: hydroxyethyl cellulose 2 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 15 mg / L, sodium hydroxymethyl sulfonate 120 mg / L, sodium polydisulfide dipropane sulfonate 50 mg / L, tetrahydrothiazolyl thionone 10 mg / L, 2-mercaptobenzimidazole 4 mg / L, and ethylene thiourea 4 mg / L.

[0061] The titanium plate used in this comparative example has a surface roughness Ra = 0.134 μm and Rz = 1.317 μm. After electroplating, the copper foil surface appears whitish with a matte finish gloss of 46 GU. In this comparative example, the copper foil could not be peeled off the titanium plate during the foil removal process, therefore the pinhole situation could not be determined.

[0062] Comparative Example 2: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: polyethylene glycol 6000# 50 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 15 mg / L, sodium hydroxymethyl sulfonate 120 mg / L, sodium polydisulfide dipropane sulfonate 50 mg / L, tetrahydrothiazolyl thionone 10 mg / L, 2-mercaptobenzimidazole 4 mg / L, and ethylene thiourea 4 mg / L.

[0063] The titanium plate used in this comparative example has a surface roughness Ra = 0.130 μm and Rz = 1.346 μm. After electroplating, the copper foil surface exhibits a mottled appearance with a matte finish of 104 GU. This comparative example successfully peels the copper foil off the titanium plate, but a small number of pinholes are present on the copper foil surface.

[0064] Comparative Example 3: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: polyethylene glycol 6000# 50 mg / L, hydroxyethyl cellulose 2 mg / L, sodium hydroxymethanesulfonate 120 mg / L, sodium polydithiopropanesulfonate 50 mg / L, tetrahydrothiazothione 10 mg / L, 2-mercaptobenzimidazole 4 mg / L, and ethylene thiourea 4 mg / L.

[0065] The titanium plate used in this comparative example has a surface roughness Ra = 0.119 μm and Rz = 1.115 μm. After electroplating, the copper foil surface appears whitish with a matte finish of 58 GU. In this comparative example, the copper foil could not be peeled off the titanium plate during the foil removal process, therefore the pinhole situation could not be determined.

[0066] Comparative Example 4: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: polyethylene glycol 6000# 50 mg / L, hydroxyethyl cellulose 2 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate monoester 15 mg / L, sodium polydisulfide dipropane sulfonate 50 mg / L, tetrahydrothiazolyl thionone 10 mg / L, 2-mercaptobenzimidazole 4 mg / L, and ethylene thiourea 4 mg / L.

[0067] The titanium plate used in this comparative example has a surface roughness Ra = 0.128 μm and Rz = 1.327 μm. After electroplating, the copper foil surface appears whitish with a matte finish of 24 GU. In this comparative example, the copper foil could not be peeled off the titanium plate during the foil removal process, therefore the pinhole situation could not be determined.

[0068] Comparative Example 5: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: polyethylene glycol 6000# 50 mg / L, hydroxyethyl cellulose 2 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate monoester 15 mg / L, sodium hydroxymethyl sulfonate 120 mg / L, tetrahydrothiazolyl thionone 10 mg / L, 2-mercaptobenzimidazole 4 mg / L, and ethylene thiourea 4 mg / L.

[0069] The titanium plate used in this comparative example has a surface roughness Ra = 0.112 μm and Rz = 1.226 μm. After electroplating, the copper foil surface appears whitish with a matte finish of 30 GU. In this comparative example, the copper foil could not be peeled off the titanium plate during the foil removal process, therefore the pinhole situation could not be determined.

[0070] Comparative Example 6: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: polyethylene glycol 6000# 50 mg / L, hydroxyethyl cellulose 2 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 15 mg / L, sodium hydroxymethyl sulfonate 120 mg / L, sodium polydisulfide dipropane sulfonate 50 mg / L, 2-mercaptobenzimidazole 4 mg / L, and ethylene thiourea 4 mg / L.

[0071] The titanium plate used in this comparative example has a surface roughness Ra = 0.110 μm and Rz = 1.187 μm. After electroplating, the copper foil surface is uniform with a matte finish of 204 GU. This comparative example can successfully peel the foil off from the titanium plate, but the copper foil surface has many pinholes.

[0072] Comparative Example 7: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: polyethylene glycol 6000# 50 mg / L, hydroxyethyl cellulose 2 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 15 mg / L, sodium hydroxymethyl sulfonate 120 mg / L, sodium polydisulfide dipropane sulfonate 50 mg / L, tetrahydrothiazolyl thionone 10 mg / L, and ethylene thiourea 4 mg / L.

[0073] The titanium plate used in this comparative example has a surface roughness Ra = 0.128 μm and Rz = 1.307 μm. After electroplating, the copper foil surface is uniform with a matte gloss of 220 GU. This comparative example can successfully peel the foil off from the titanium plate, but the copper foil surface has many pinholes.

[0074] Comparative Example 8: The preparation process is basically the same as in Example 1, except for step S1: The concentrations of the additive solutions were as follows: polyethylene glycol 6000# 50 mg / L, hydroxyethyl cellulose 2 mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 15 mg / L, sodium hydroxymethyl sulfonate 120 mg / L, sodium polydisulfide dipropane sulfonate 50 mg / L, tetrahydrothiazolyl thionone 10 mg / L, and 2-mercaptobenzimidazole 4 mg / L.

[0075] The titanium plate used in this comparative example has a surface roughness Ra = 0.120 μm and Rz = 1.170 μm. After electroplating, the copper foil surface is uniform with a matte gloss of 209 GU. This comparative example can successfully peel the foil off from the titanium plate, but the copper foil surface has many pinholes.

[0076] The process parameters for Examples 1 and Comparative Examples 1-8 are shown in Table 2. For ease of representation, polyethylene glycol 6000#, hydroxyethyl cellulose, disodium sulfonated succinate of fatty alcohol polyoxyethylene ether, sodium hydroxymethyl sulfonate, sodium polydithiopropane sulfonate, tetrahydrothiazolium thione, 2-mercaptobenzimidazole, and ethylene thiourea are referred to as additives A-H, respectively.

[0077] As can be seen from the data in Example 1 and Comparative Examples 1-8, the additive process of the present invention enables the additive components to work synergistically. Under the combined effect of these components, the density and uniformity of the 1μm copper foil are improved, the gloss of the copper foil surface is enhanced, and the pinholes on the copper foil surface are reduced, facilitating its complete removal from the cathode surface. Each component of the additives in this application is essential; the absence of any one component will result in various appearance defects in the prepared 1μm green foil, or the inability to peel it off, or an excessive number of pinholes.

[0078] Comparative Example 9: The preparation process is basically the same as in Example 1, except for step S2: The titanium plate was polished using a 600-grit PVA polishing wheel at a frequency of 20 Hz. After polishing, it was polished using a 1200-grit non-woven polishing wheel at a frequency of 20 Hz, and then polished again using a 2000-grit non-woven polishing wheel at a frequency of 20 Hz. After polishing, the surface roughness of the titanium plate was Ra = 0.285 μm and Rz = 2.599 μm.

[0079] After electroplating, the copper foil in this comparative example has a rough surface gloss of 156 GU. This comparative example can be successfully peeled off from a titanium plate, but the copper foil surface has numerous pinholes.

[0080] Comparative Example 10: The preparation process is basically the same as in Example 1, except for step S2: The titanium plate was polished using a 600-grit PVA polishing wheel at a frequency of 70 Hz. After polishing, it was polished using a 1200-grit non-woven polishing wheel at a frequency of 70 Hz, and then polished again using a 2000-grit non-woven polishing wheel at a frequency of 70 Hz. After polishing, the surface roughness of the titanium plate was Ra = 0.058 μm and Rz = 0.652 μm.

[0081] After electroplating, the copper foil surface in this comparative example showed powdering, with a matte gloss level of 29 GU. During the foil peeling process, the copper foil could not be completely removed from the titanium plate in this comparative example, therefore the pinhole situation could not be determined.

[0082] Comparative Example 11: The preparation process is basically the same as in Example 1, except for step S2: The titanium plate was polished using 600-grit sandpaper at a frequency of 35 Hz. After polishing, it was polished using 1000-grit sandpaper at a frequency of 35 Hz, and then polished again using 1200-grit sandpaper at a frequency of 35 Hz. After polishing, the surface roughness of the titanium plate was Ra = 0.312 μm and Rz = 3.007 μm.

[0083] After electroplating, the copper foil in this comparative example has a rough surface and a gloss level of 138 GU. This comparative example can be successfully peeled off from a titanium plate, but the copper foil surface has numerous pinholes.

[0084] Comparative Example 12: The preparation process is basically the same as in Example 1, except for step S2: The titanium plate was polished using a 600-mesh nonwoven fabric wing wheel at a frequency of 35 Hz. After polishing, it was polished using an 800-mesh nonwoven fabric wing wheel at a frequency of 35 Hz, and then polished again using a 1000-mesh nonwoven fabric wing wheel at a frequency of 35 Hz. After polishing, the surface roughness of the titanium plate was Ra = 0.359 μm and Rz = 3.431 μm.

[0085] After electroplating, the copper foil in this comparative example has a rough surface gloss of 122 GU. This comparative example can be successfully peeled off from a titanium plate, but the copper foil surface has numerous pinholes.

[0086] Comparative Example 13: The preparation process is basically the same as in Example 1, except for step S2: The titanium plate was polished using a 600-grit sisal fiber wheel at a frequency of 35 Hz. After polishing, it was then polished using an 800-grit sisal fiber wheel at a frequency of 35 Hz, followed by a 1000-grit sisal fiber wheel at a frequency of 35 Hz. After polishing, the surface roughness of the titanium plate was Ra = 0.370 μm and Rz = 3.866 μm.

[0087] After electroplating, the copper foil in this comparative example has a rough surface and a gloss level of 120 GU. This comparative example can be successfully peeled off from a titanium plate, but the copper foil surface has numerous pinholes.

[0088] The process parameters for Examples 1 and Comparative Examples 9-13 are shown in Table 3. For ease of representation, polyethylene glycol 6000#, hydroxyethyl cellulose, disodium sulfonated succinate of fatty alcohol polyoxyethylene ether, sodium hydroxymethyl sulfonate, sodium polydithiopropane sulfonate, tetrahydrothiazolium thione, 2-mercaptobenzimidazole, and ethylene thiourea are referred to as additives A-H, respectively.

[0089] As shown in Table 3, the titanium plate polishing process of the present invention can make the roughness of the titanium plate within a suitable range for copper foil electroplating. Too high a roughness of the titanium plate will lead to an increase in pinholes on the surface of the copper foil, while too low a roughness of the titanium plate will lead to poor bonding between the copper foil and the titanium plate, and the electroplated copper foil will become powdery.

[0090] Comparative Example 14: The preparation process is basically the same as in Example 1, except for step S4: The titanium plate used in this comparative example has a surface roughness Ra=0.102μm and Rz=1.054μm. After electroplating, the copper foil surface is uniform, with a matte gloss of 315GU.

[0091] This comparative example uses CA tape with a thickness of 40μm and a width of 6cm. When peeling the foil, the tape roller was slowly rolled at a speed of 3mm / s, using the roller to drive the tape and peel off the 1μm copper foil, but the peeling failed.

[0092] Comparative Example 15: The preparation process is basically the same as in Example 1, except for step S4: The titanium plate used in this comparative example has a surface roughness Ra=0.119μm and Rz=1.207μm. After electroplating, the copper foil surface is uniform, with a matte gloss of 313GU.

[0093] This comparative example uses CA tape with a thickness of 10μm and a width of 6cm. When peeling the foil, the tape roller was slowly rolled at a speed of 0.4mm / s, using the roller to drive the tape and peel off the 1μm copper foil, but the peeling failed.

[0094] Comparative Example 16: The preparation process is basically the same as in Example 1, except for step S4: The titanium plate used in this comparative example has a surface roughness Ra=0.140μm and Rz=1.310μm. After electroplating, the copper foil surface is uniform, with a matte gloss of 305GU.

[0095] This comparative example uses silicone rubber tape with a thickness of 40μm and a width of 6cm. When peeling the foil, the tape roller was slowly rolled at a speed of 0.4mm / s, using the roller to pull the tape and peel off the 1μm copper foil, but the peeling failed.

[0096] Comparative Example 17: The preparation process is basically the same as in Example 1, except for step S4: The titanium plate used in this comparative example has a surface roughness Ra=0.111μm and Rz=1.247μm. After electroplating, the copper foil surface is uniform, with a matte gloss of 306GU.

[0097] This comparative example uses PVC tape with a thickness of 40μm and a width of 6cm. When peeling off the foil, the tape roller is slowly rolled at a speed of 0.4mm / s. The tape is then driven by the tape roller to peel off the 1μm copper foil. The foil can be peeled off, but some copper residue remains on the titanium plate.

[0098] The process parameters for Examples 1 and Comparative Examples 14-17 are shown in Table 4. For ease of representation, polyethylene glycol 6000#, hydroxyethyl cellulose, disodium sulfonated succinate of fatty alcohol polyoxyethylene ether, sodium hydroxymethyl sulfonate, sodium polydithiopropane sulfonate, tetrahydrothiazolium thione, 2-mercaptobenzimidazole, and ethylene thiourea are referred to as additives A-H, respectively.

[0099] Table 4

[0100] Table 4 shows that the adhesive tape used in the ultra-thin copper foil peeling process has suitable adhesion, the tape thickness is suitable for peeling copper foil, and the peeling speed is matched with the tape's adhesion force, thus successfully peeling off 1μm copper foil. Changing the tape material, peeling speed, or tape thickness will result in the failure to successfully prepare and peel off 1μm copper foil.

[0101] In summary, by utilizing the above-mentioned technical solutions of the present invention and optimizing the additive process, titanium plate polishing process, and ultra-thin copper foil peeling process, 1μm copper foil can be prepared.

[0102] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit and principles of the invention. The embodiments disclosed above are merely preferred embodiments of the present invention and are not intended to limit the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

An additive for 1.1-micron electrolytic copper foil, characterized by comprising: Polyethylene glycol 6000# 10mg / L~85mg / L, hydroxyethyl cellulose 0.5mg / L~9mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 3mg / L~26mg / L, sodium hydroxymethanesulfonate 20mg / L~185mg / L, sodium polydisulfide dipropane sulfonate 15mg / L~80mg / L, tetrahydrothiazothione 2mg / L~27mg / L, 2-mercaptobenzimidazole 0.3mg / L~9.5mg / L, and ethylene thiourea 0.3mg / L~9.5mg / L. A method for preparing 2.1-micron electrolytic copper foil, characterized by: Includes the following steps: S1. Additives containing the following components: polyethylene glycol 6000# 10mg / L~85mg / L, hydroxyethyl cellulose 0.5mg / L~9mg / L, disodium fatty alcohol polyoxyethylene ether sulfonated succinate 3mg / L~26mg / L, sodium hydroxymethanesulfonate 20mg / L~185mg / L, sodium polydisulfide dipropane sulfonate 15mg / L~80mg / L, tetrahydrothiazolyl thionone 1mg / L~27mg / L, 2-mercaptobenzimidazole 0.3mg / L~9.5mg / L, and ethylene thiourea 0.3mg / L~9.5mg / L; S2. Polishing of titanium plates: Use a polishing wheel to grind the surface of the titanium plate, and then use a polishing wheel to polish and finely polish the surface of the titanium plate. S3. Electrolytic foil production: Prepare copper sulfate electrolyte and mix the additives prepared in S1 into the electrolyte. Pour the mixture into a Haring tank. Place the polished titanium plate and carbon plate from S2 into the Haring tank for fixation and electrolytic foil production to obtain 1-micron copper foil. S4. Copper foil peeling: Apply cellulose acetate tape to the 1-micron copper foil on the surface of the titanium plate. Flatten the cellulose acetate tape with a roller, attach the end of the tape to the roller, and roll the roller at a uniform speed of 0.1 mm / s to 0.9 mm / s. The roller will peel the 1-micron copper foil from the surface of the titanium plate. S5. Tape dissolution: Place the cellulose acetate tape with the 1-micron copper foil in an organic solvent. After the tape dissolves, remove the 1-micron copper foil and dry it. In S2, the polishing wheel is made of polyvinyl alcohol, with a mesh size of 180-1000 mesh and a polishing frequency of 25 Hz. ~50Hz; the polishing wheel is made of non-woven fabric, with a grit size of 640-1500 and a polishing frequency of 25Hz-50Hz; the fine polishing wheel is made of non-woven fabric, with a grit size of 1000-2500 and a polishing frequency of 25Hz-50Hz.

3. The method for preparing 1-micron electrolytic copper foil as described in claim 2, characterized in that: In S1, polyethylene glycol 6000#, hydroxyethyl cellulose, disodium fatty alcohol polyoxyethylene ether sulfonated succinate, sodium hydroxymethyl sulfonate, sodium polydithiopropane sulfonate, tetrahydrothiazolyl thionone, 2-mercaptobenzimidazole and ethylene thiourea were dissolved in deionized water and diluted to 250 mL in a volumetric flask to obtain the corresponding additives.

4. The method for preparing 1-micron electrolytic copper foil as described in claim 2, characterized in that: The titanium plate in S2 has a thickness of 5mm, a width of 6cm, and a length of 15cm. After polishing, the surface roughness of the titanium plate is Ra≤0.20μm and Rz≤2.0μm.

5. The method for preparing 1-micron electrolytic copper foil as described in claim 2, characterized in that: The copper sulfate electrolyte prepared in S3 has a copper ion concentration of 65 g / L to 95 g / L, a sulfuric acid concentration of 80 g / L to 170 g / L, a chloride ion concentration of 15 ppm to 30 ppm, and an electrolyte temperature of 50°C to 60°C.

6. The method for preparing 1-micron electrolytic copper foil as described in claim 2, characterized in that: The additive in S1 is added to the electrolyte prepared in S3 and stirred at 50℃~60℃ for 30 minutes to obtain a mixture.

7. The method for preparing 1-micron electrolytic copper foil as described in claim 2, characterized in that: The electrode spacing between the titanium plate and the carbon plate in S3 is 10 mm.

8. The method for preparing 1-micron electrolytic copper foil as described in claim 2, characterized in that: In S3, the current during the electrolysis of the foil is 2A to 25A, and the electroplating time is 7.2s to 90s. The electroplating time is inversely proportional to the current.

9. The method for preparing 1-micron electrolytic copper foil as described in claim 2, characterized in that: The cellulose acetate tape has a thickness of 30μm to 50μm and a width of 6cm, which matches the width of the titanium plate in S2.

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