Copper foil, preparation method thereof and circuit substrate

Abstract

The embodiment of the invention provides a copper foil, a preparation method thereof and a circuit substrate. The preparation method comprises the following steps: placing a raw foil in an electrolyte for copper deposition electrolysis to obtain a copper foil intermediate; performing surface treatment on the copper foil intermediate to obtain a copper foil; the electrolyte comprises H2SO4, Cu < 2 + >, Cl <-> and an additive; the additive comprises at least two of cellulose ether, a polyether derivative, a collagen compound and a polysaccharide compound. The method is used for achieving the effects of controlling the roughness of the non-treated surface of the copper foil and improving the peeling strength of the copper foil.

Description

Technical Field

[0001] This application relates to the field of copper foil preparation, and more particularly to a copper foil and its preparation method, and a circuit board. Background Technology

[0002] Copper foil, a key basic material in the electronics industry, is widely used in 5G communications, artificial intelligence chip packaging, new energy vehicle power batteries, high-density printed circuit boards (HPCBs), and semiconductor packaging. In 5G / AI high-frequency and high-speed communication scenarios, the surface roughness of copper foil directly affects the transmission loss and signal integrity of electromagnetic waves. In the automotive field, the low roughness of copper foil is closely related to thermal management performance, requiring high thermal conductivity and low thermal resistance. In advanced packaging processes (such as Flip-Chip and PoP), the double-sided roughness control of copper foil must balance adhesive strength and mechanical stability. With technological iteration, the industry has put forward higher requirements for copper foil, namely "double low roughness" (low roughness on both the processed and unprocessed sides), to achieve finer line etching, lower dielectric loss, and more stable peel strength.

[0003] Current copper foil manufacturing processes primarily involve producing raw foil via electrolytic deposition (ED), followed by surface treatments such as roughening and curing to form the final product. In existing technologies, the roughness of the treated surface of the copper foil is typically achieved by adjusting the electrolyte composition (e.g., sulfuric acid, chloride ion concentration) and current density, while the roughness control of the untreated surface (i.e., the roughened surface) depends on the type of additives and the stability of process parameters. However, traditional methods have the following limitations: the additive system is singular, making it difficult to simultaneously achieve a balance between untreated surface roughness control and conductivity and peel strength; process parameters fluctuate greatly, with electrolyte temperature, current density, and other parameters easily affected by the environment, resulting in a large range of untreated surface roughness fluctuations (typically Rz values ​​higher than 3.5 μm), making it difficult to meet the demands of high-end applications.

[0004] Therefore, there is an urgent need to develop a method for preparing copper foil to control the roughness of the untreated surface of the copper foil and improve the peel strength between the copper foil and the substrate. Summary of the Invention

[0005] This application provides a copper foil and its preparation method, as well as a circuit board, to achieve stable control of the roughness of the untreated surface of the copper foil, while also taking into account conductivity and peel strength.

[0006] In a first aspect, embodiments of this application provide a method for preparing copper foil, comprising: placing raw foil in an electrolyte for copper deposition electrolysis to obtain a copper foil intermediate;

[0007] The copper foil intermediate is surface treated to obtain copper foil;

[0008] The electrolyte includes H2SO4 and Cu.2+ Cl - and additives;

[0009] The additives include at least two of the following: cellulose ethers, polyether derivatives, collagen compounds, and polysaccharide compounds.

[0010] In one possible implementation, the additives include hydroxyethyl cellulose and bone glue.

[0011] In one possible implementation, the concentration of H2SO4 in the electrolyte is 80 g / L to 160 g / L;

[0012] And / or, the concentration of Cu²⁺ is 60 g / L to 105 g / L;

[0013] And / or, the Cl - The concentration is 10ppm~75ppm;

[0014] And / or, the concentration of any one of the additives in the electrolyte is 2 ppm to 80 ppm.

[0015] In one possible implementation, the electrolysis temperature of the copper deposition electrolysis is 20°C-80°C, preferably 40°C-70°C;

[0016] And / or, the electrolytic current of the copper deposition electrolysis is 20kA-50kA.

[0017] In one possible implementation, the surface treatment includes roughening and curing;

[0018] The coarsened current density is 2A / dm. 2 ~25A / dm 2 The roughening temperature is 15℃~35℃;

[0019] The current density during curing is 2 A / dm³. 2 ~23A / dm 2 The curing temperature is 25℃~45℃.

[0020] In one possible implementation, the roughening solution used for roughening includes H2SO4 and Cu. 2+ ;

[0021] The concentration of H2SO4 in the roughening solution is 70 g / L to 190 g / L;

[0022] The Cu 2+ The concentration in the roughening solution is 5 g / L to 28 g / L;

[0023] And / or, the curing solution used for curing includes H2SO4 and Cu.2+ ;

[0024] The concentration of H2SO4 in the curing solution is 50 g / L to 130 g / L;

[0025] The Cu 2+ The concentration in the roughening solution is 15 g / L to 70 g / L.

[0026] In one possible implementation, the number of curing processes is greater than or equal to the number of roughening processes;

[0027] And / or, the surface treatment includes at least two roughening processes and at least two curing processes.

[0028] In one possible implementation, the surface treatment includes anti-oxidation treatment and / or anti-corrosion treatment;

[0029] The current density for the anti-oxidation treatment is 0.3 A / dm³. 2 ~6A / dm 2 The temperature for the anti-oxidation treatment is 20℃~45℃;

[0030] The current density for the corrosion protection treatment is 0.25 A / dm. 2 ~6A / dm 2 The temperature for the anti-oxidation treatment is 20℃~45℃.

[0031] In one possible implementation, the antioxidant electrolyte used in the antioxidant treatment includes Cr. 6+ ;

[0032] The Cr 6+ The concentration in the antioxidant electrolyte is 0.5 g / L-6 g / L;

[0033] The pH of the antioxidant electrolyte is 8.0~12.0;

[0034] And / or, the anti-corrosion electrolyte used in the anti-corrosion treatment includes Zn. 2+ and K4P2O7;

[0035] The Zn 2+ The concentration in the anti-corrosion electrolyte is 1g / L-25g / L;

[0036] The concentration of K4P2O7 in the anti-corrosion electrolyte is 50g / L-300g / L;

[0037] The pH of the anti-corrosion electrolyte is 8.0~12.0.

[0038] In one possible implementation, the surface treatment includes silane coupling agent spraying and drying;

[0039] The silane coupling agent includes at least one of sulfur-containing silane coupling agents, amino-based silane coupling agents, and epoxy-based silane coupling agents;

[0040] Secondly, embodiments of this application provide a copper foil prepared by the above-described preparation method.

[0041] In one possible implementation, the copper foil includes a non-processed side and a processed side;

[0042] When the thickness of the copper foil is 35 μm, the roughness of the untreated surface is 2.0 μm-3.0 μm, and the roughness of the treated surface is 2.0 μm-3.0 μm;

[0043] When the thickness of the copper foil is 70 μm, the roughness of the untreated surface is 3.0 μm-5.0 μm, and the roughness of the treated surface is 2.0 μm-3 μm.

[0044] In one possible implementation, the roughness standard deviation of the untreated surface is less than or equal to 0.099.

[0045] Thirdly, embodiments of this application provide a circuit board comprising copper foil prepared by the above-described preparation method or the copper foil described above.

[0046] The embodiments of this application provide a copper foil and its preparation method, as well as a circuit board. By synergistically controlling the mixed additives and electrolytic process parameters, the roughness of the untreated surface of the copper foil is reduced and the roughness of the untreated surface of the copper foil is stably controlled, thereby reducing signal loss while taking into account its conductivity and peel strength. Attached Figure Description

[0047] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0048] Figure 1 A schematic diagram of the structure of the copper foil provided in this application.

[0049] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0050] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0051] First, let me explain the terms used in this application:

[0052] RTF (Reverse Treated Foil) copper foil: copper foil with different roughness on both sides obtained through step-by-step processing;

[0053] Processed surface: refers to the contact surface of the copper foil that has been roughened (such as by acidic electrolytic roughening) to form an uneven structure, which enhances the bonding force with the resin;

[0054] Unprocessed surface: refers to the contact surface in the copper foil that maintains low roughness (Rz<3μm) to reduce signal loss.

[0055] Figure 1 A schematic diagram of the structure of the copper foil provided in this application.

[0056] In existing technologies, it is difficult to stably control the roughness (Rz value) of the untreated surface of copper foil during continuous production, which leads to fluctuations in product performance and fails to meet the stringent requirements of 5G / AI high-frequency communication for low dielectric loss.

[0057] The copper foil preparation method provided in this application solves the technical problem of unstable control of the roughness of the untreated surface of copper foil by means of synergistic regulation of the mixed additive system (at least two of polyether derivatives, collagen, and high molecular weight polysaccharide compounds) and electrolyte process parameters.

[0058] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0059] This application provides a method for preparing copper foil, the method comprising: placing raw foil in an electrolyte for copper deposition electrolysis to obtain a copper foil intermediate; and performing surface treatment on the copper foil intermediate to obtain copper foil; the electrolyte comprising H2SO4 and Cu. 2+ Cl - Additives; additives include at least two of the following: cellulose ethers, polyether derivatives, collagen compounds, and polysaccharide compounds.

[0060] In this embodiment, the long-chain polymer of cellulose ether adsorbs onto the active growth sites on the cathode surface, forming a microscopic, dynamic "barrier film." This film increases the difficulty for copper ions to reach the cathode surface and discharge, transforming copper deposition from "selective rapid growth" to "uniform, slow nucleation and growth," thereby generating finer, denser copper grains. Furthermore, as a water-soluble polymer, it slightly increases the viscosity of the electrolyte, helping to reduce the impact of electrolyte turbulence on the cathode diffusion layer, making the ion concentration and current distribution near the cathode more stable, thus forming a more stable diffusion layer. This facilitates more controllable and consistent supply of copper ions and distribution of inhibitors. Polyether derivatives (such as PEG) can react with Cl... - Formation of PEG-Cu + -Cl - Ternary complexes lower surface energy, increasing the texture coefficient of the untreated surface and thus reducing roughness. Collagen-like compounds, with their functional groups strongly adsorbed onto the active sites of copper crystal growth, specifically inhibit longitudinal grain growth and promote lateral growth and new nucleation, resulting in extremely fine and uniform grain structure to ensure stable roughness. Polysaccharide compounds not only fill grain boundary micropores and reduce oxidation channels, giving the copper foil good thermal oxidation stability, but also, as polymers, preferentially inhibit deposition at microscopic protrusions by forming a viscous diffusion layer on the cathode surface, achieving macroscopic leveling. Simultaneously, their long-chain structure acts as a "skeleton," enhancing the stability of the entire adsorption layer. By adding at least two of the above additives, intermolecular hydrogen bonding and steric hindrance effects are achieved, regulating the deposition rate and crystal orientation of copper ions on the untreated surface, ultimately reducing the surface roughness of the untreated surface and improving the stability of roughness control. Surface treatment, through chemical adsorption and redox reactions, forms a dense protective film on the copper foil surface, reducing the surface defect rate.

[0061] In some specific implementations, the additives include hydroxyethyl cellulose and bone glue.

[0062] HEC molecules have relatively long chains, enabling them to form a viscous, dynamic adsorption film on the cathode surface (especially in microscopic protrusions or high current density areas). This film hinders the diffusion of copper ions to the cathode surface. At microscopic protrusions, the diffusion path is shorter, the current density is higher, and the inhibitory effect of HEC is more pronounced; while at depressions, the inhibitory effect is relatively weaker. This "preferred inhibition" effect causes copper deposition to preferentially occur in depressions, effectively smoothing the microscopic contour and inhibiting the formation of nodules and dendrites. By hindering the free deposition of copper ions, HEC increases the overpotential for copper nucleation, increasing the number of nucleation sites and inhibiting grain growth. This results in a finer, more uniform copper foil crystal structure and reduced surface roughness. Meanwhile, bone glue molecules contain various amino acids and peptide chains, whose functional groups (such as -COOH, -NH2) can be strongly adsorbed onto specific crystal faces of copper crystals. This adsorption alters the growth rate of different crystal faces, inhibiting the excessively rapid growth of certain dominant orientation crystal faces, thus allowing copper to grow in the form of more and smaller nuclei. In this embodiment, hydroxyethyl cellulose (HEC) and bone glue are added to the electrolyte as additives. The bone glue molecules can interact with the "skeleton" formed by HEC on the cathode surface, making the entire additive adsorption layer more robust and stable. This stable adsorption layer can resist interference from electrolyte flow, temperature fluctuations, and small changes in current density, ensuring that each roll of copper foil produced has a consistent low roughness, thereby achieving control over the roughness stability of the untreated surface.

[0063] In some specific embodiments, the concentration of any additive in the electrolyte is 2 ppm to 80 ppm.

[0064] For polyether derivatives, their main function is to provide basic inhibition and polarization, providing an adsorption platform for other additives (such as collagen). If the concentration is insufficient, the basic inhibition layer is weak, and collagen and HEC cannot effectively "attach"; if the concentration is too high, it may cause deposition to stop or generate stress, making the copper foil brittle. For collagen compounds, insufficient concentration results in poor grain refinement and high roughness; excessive concentration leads to "over-inhibition," causing uneven deposition, increased internal stress, copper foil embrittlement, and even surface streaks or spots. For polysaccharide compounds, insufficient concentration results in poor leveling and large surface micro-undulations; excessive concentration leads to excessive solution viscosity, affecting copper ion transport and potentially causing uneven deposition or new defects. Therefore, in this embodiment, by controlling the concentration of any of the above additives in the electrolyte to 2ppm-80ppm, precise and independent replenishment can be made according to their respective consumption rates, and more diverse "sites" can be generated, making the copper foil surface structure more stable, more resistant to competitive adsorption of impurity ions, and maintaining the stability of the deposition process.

[0065] For example, the concentration of any additive in the electrolyte can be a range of 2 ppm, 5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm, 50 ppm, 55 ppm, 60 ppm, 65 ppm, 70 ppm, 75 ppm, 80 ppm, or any combination thereof.

[0066] In some specific embodiments, when electrolyzing the raw foil, the electrolyte used includes copper ions, chloride ions and hydrochloric acid, wherein the concentration of copper ions can be 60 g / L to 105 g / L, the concentration of chloride ions can be 10 ppm to 75 ppm, and the concentration of sulfuric acid (H2SO4) can be 80 g / L to 160 g / L.

[0067] In this embodiment, the concentration of copper ions in the electrolyte is controlled at 60 g / L to 105 g / L to ensure the deposition rate and thickness uniformity of copper on the green foil surface. Furthermore, a suitable copper ion concentration matches the current density, providing a suitable cathode overpotential, which is beneficial for the formation of fine equiaxed crystals. The concentration of chloride ions is controlled at 10 ppm to 75 ppm to activate and stabilize the additives. This is because chloride ions preferentially adsorb onto the cathode copper surface, altering the interfacial properties and providing adsorption sites for organic additives such as polyether derivatives and bone glue. It forms a "Cl" with these additives. - The "organic additive" co-adsorption layer provides a powerful inhibitory effect. In addition, by promoting uniform deposition, chloride ions can effectively inhibit the formation of rough, dull "pockmarked" surfaces and dendritic crystals, contributing to a glossy, smooth surface.

[0068] For example, the concentration of copper ions can be a range of 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, or any combination thereof; the concentration of chloride ions can be a range of 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm, 50 ppm, 55 ppm, 60 ppm, 65 ppm, 70 ppm, 75 ppm, or any combination thereof.

[0069] By controlling the concentration of sulfuric acid in the electrolyte, the conductivity of the electrolyte can be improved, energy consumption can be reduced, and the hydrolysis of copper sulfate can be prevented from producing copper hydroxide precipitate or basic copper sulfate crystals, thus avoiding these impurities from contaminating the electrolyte or adhering to the copper foil and forming defects.

[0070] For example, the concentration of sulfuric acid in the electrolyte can be a range of 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, 160 g / L, or any combination thereof.

[0071] In some specific embodiments, the electrolysis temperature for copper deposition electrolysis is 20℃-80℃, preferably 40℃-70℃.

[0072] When the electrolysis temperature is between 20℃ and 80℃, the migration and diffusion rates of copper ions are slower, and the polarization effect on the cathode surface is enhanced, which is conducive to increasing the driving force for copper crystal nucleus formation and significantly increasing the nucleation rate. At this time, a large number of fine crystal nuclei grow simultaneously, eventually forming a fine and dense grain structure, thereby directly and significantly reducing the surface roughness of the copper foil, especially the untreated surface. Moreover, this temperature range is also within the optimal activity window of the aforementioned additives, which is key to maintaining their stable performance and ensuring batch-to-batch consistency of copper foil roughness. It is understandable that the deposition temperature also affects the internal stress of the copper foil. By controlling the electrolysis temperature, copper foil with moderate internal stress and good toughness can be obtained.

[0073] For example, the electrolysis temperature of copper deposition electrolysis can be a range of 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, or any combination thereof.

[0074] In some specific implementations, the electrolytic current for copper deposition electrolysis is 20kA-50kA.

[0075] At lower current densities, the electrochemical polarization on the cathode surface is stronger, and the driving force for copper ion deposition is relatively mild. This is conducive to the formation of numerous small crystal nuclei. These tiny nuclei grow slowly, eventually forming a dense, uniform, and smooth surface, thereby significantly reducing the roughness of the untreated surface. By precisely controlling the current between 20kA and 50kA, the untreated surface can have a lower roughness within a certain range to reduce signal loss, while the treated surface can have a relatively higher roughness to enhance adhesion to the resist.

[0076] For example, the electrolytic current for copper deposition electrolysis can be a range of 20kA, 25kA, 30kA, 35kA, 40kA, 45kA, 50kA, or any combination thereof.

[0077] In some specific embodiments, the surface treatment includes roughening and curing; preferably, the roughening current density is 2 A / dm. 2 ~25A / dm 2 The roughening temperature is 15℃~35℃; preferably, the curing current density is 2A / dm³. 2 ~23A / dm2 The curing temperature is 25℃~45℃.

[0078] The essence of roughening treatment is to deposit a layer of microscopic "nodular" or "dendritic" copper particles on the smooth surface of copper foil using electrochemical methods, thus roughening it. Its core function is to enhance the mechanical bonding force with the substrate (anchoring effect) and provide a "foundation" for the cured layer formed during subsequent curing treatment. Curing treatment, also known as a "barrier layer" or "thermal stabilization layer" treatment, typically involves electrodepositing an alloy or compound rich in elements such as zinc, nickel, and cobalt onto the roughened layer. Its core function is to improve the heat resistance and chemical corrosion resistance of the copper foil. The resulting cured layer can encapsulate and fix the roughened nodular particles, preventing them from being flattened or collapsing under the high temperature and pressure of subsequent processing (such as lamination), thereby maintaining their anchoring effect.

[0079] In this embodiment, the current density during coarsening is controlled to be 2A / dm. 2 ~25A / dm 2 The temperature is maintained between 15℃ and 35℃ to control the porosity and density of the roughened layer and ensure its uniformity, thereby maintaining high-temperature peel strength. The current density during curing is controlled at 2A / dm³. 2 ~23A / dm 2 At a temperature of 25℃~45℃, a solidified layer with the target alloy ratio can be obtained, forming a thin, dense, and completely covering alloy layer, thereby achieving better barrier performance.

[0080] For example, the current density during coarsening can be 2 A / dm. 2 5A / dm 2 8A / dm 2 10A / dm 2 12A / dm 2 14A / dm 2 16A / dm 2 18A / dm 2 20A / dm 2 22A / dm 2 25A / dm 2 Or a range of any two of them; the temperature during roughening can be 15℃, 20℃, 25℃, 30℃, 35℃ or a range of any two of them.

[0081] For example, the current density during curing can be 2 A / dm. 2 5A / dm 2 8A / dm 2 10A / dm 2 12A / dm 2 14A / dm2 16A / dm 2 18A / dm 2 20A / dm 2 23A / dm 2 Or a range of any two of them; the curing temperature can be 25℃, 30℃, 35℃, 40℃, 45℃ or a range of any two of them.

[0082] In some specific embodiments, the roughening solution used for roughening includes H2SO4 and Cu. 2+ Preferably, the concentration of H2SO4 in the roughening solution is 70 g / L to 190 g / L; preferably, Cu 2+ The concentration in the roughening solution is 5 g / L to 28 g / L.

[0083] In the roughening solution, sulfuric acid provides a highly acidic etching environment. During electrodeposition, two competing processes occur: the deposition of copper ions and the chemical / electrochemical dissolution of the deposited copper. A high sulfuric acid concentration enhances the etching effect on the deposited copper nodules and dendrites, preserving a stronger and more stable "skeleton." By controlling the sulfuric acid concentration in the roughening solution to 70 g / L~190 g / L, the roughened structure can be etched, avoiding the formation of overly loose, sponge-like inferior nodules, thus obtaining a more robust and denser roughened layer that better maintains high-temperature peel strength.

[0084] Furthermore, in the roughening solution, the concentrations of copper ions and sulfuric acid determine the "deposition-dissolution" balance. By controlling the copper ion concentration to be between 5 g / L and 28 g / L, it can be combined with the current density to obtain a roughened structure with an ideal morphology. This produces an ideal roughened layer that provides both high adhesion and can withstand the test of subsequent high-temperature processing, thus meeting the different requirements for peel strength and signal loss in different application scenarios (such as ordinary FR-4 boards and high-frequency, high-speed materials).

[0085] For example, the sulfuric acid concentration in the roughening solution can be a range of 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, 160 g / L, 170 g / L, 180 g / L, 190 g / L, or any combination thereof; the copper ion concentration in the roughening solution can be a range of 5 g / L, 10 g / L, 12 g / L, 14 g / L, 16 g / L, 18 g / L, 20 g / L, 22 g / L, 24 g / L, 26 g / L, 28 g / L, or any combination thereof.

[0086] In some specific embodiments, the curing solution used for curing includes H2SO4 and Cu. 2+Preferably, the concentration of H2SO4 in the curing solution is 50 g / L to 130 g / L; preferably, Cu 2+ The concentration in the roughening solution is 15 g / L to 70 g / L.

[0087] By controlling the concentration of H2SO4 in the curing solution to 50 g / L~130 g / L, excellent conductivity is provided, allowing the current to be evenly distributed across the entire cathode (copper foil) surface. Simultaneously, a stable low pH environment is maintained, effectively preventing the hydrolysis of zinc ions and the formation of flocculent zinc hydroxide precipitates. Furthermore, through the common ion effect and altered electrochemical polarization, the high acidity environment increases the overpotential for copper deposition, making it more difficult for copper ions to be reduced. This provides a preferential deposition window for more reactive metals such as zinc, achieving the formation of a high-quality alloy layer.

[0088] I understand that the ideal composition of the cured layer is zinc or a zinc-nickel alloy. If the copper ion concentration is too high, it will compete with zinc / nickel for deposition, resulting in an excessive amount of copper in the cured layer. The incorporation of copper will significantly reduce the heat resistance of the cured layer. Therefore, controlling the concentration of copper ions in the curing solution to 15 g / L~70 g / L is beneficial for obtaining a chemically pure and high-performance cured layer.

[0089] For example, the sulfuric acid concentration in the curing solution can be in the range of 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, or any combination thereof; the copper ion concentration in the roughening solution can be in the range of 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L, or any combination thereof.

[0090] In some specific implementations, the number of curing processes is greater than or equal to the number of roughening processes; preferably, the surface treatment includes at least two roughening processes and at least two curing processes.

[0091] It should be understood that after roughening, the surface of the copper foil is no longer flat, but covered with microscopic, irregular "nodular" or "dendritic" nodules. These nodules undulate, forming a complex three-dimensional structure. After curing, the resulting cured layer acts as a barrier, and it must completely and continuously cover the surface of each roughened nodule. Any exposed copper will become a point of failure for performance degradation or chemical corrosion at high temperatures. Therefore, by ensuring that the number of curing treatments is greater than or equal to the number of roughening treatments, the peel strength of the copper foil after lamination is maximized, preventing blistering and delamination. Furthermore, achieving complete coverage of the copper foil ensures that the etching solution cannot contact the pure copper inside during acid etching processes, thus preventing "brown contamination."

[0092] For example, the surface treatment includes roughening I, curing I, roughening II, curing II, or roughening I, curing I, roughening II, curing II, roughening III, curing III, or roughening I, curing I, roughening II, curing II, curing III, etc., performed sequentially.

[0093] In some specific embodiments, the surface treatment further includes anti-oxidation treatment and / or anti-corrosion treatment; the current density of the anti-oxidation treatment is 0.3 A / dm³. 2 ~6A / dm 2 The temperature for anti-oxidation treatment is 20℃~45℃; the current density for anti-corrosion treatment is 0.25A / dm³. 2 ~6A / dm 2 The temperature for corrosion protection treatment is 20℃~45℃.

[0094] When performing anti-oxidation treatment on copper foil, the current density for the anti-oxidation treatment is controlled at 0.3 A / dm³. 2 ~6A / dm 2 To control the thickness and uniformity of the protective film and achieve a consistent protective effect, the temperature of the anti-oxidation treatment is controlled between 20℃ and 45℃ to stabilize the reaction kinetics during the anti-oxidation treatment, maintain the stability of the treatment solution, and ensure the quality of the film formation.

[0095] For example, the current density for the anti-oxidation treatment can be 0.3 A / dm³. 2 0.5A / dm 2 1.0A / dm 2 1.5A / dm 2 2.0A / dm 2 2.5A / dm 2 3.0A / dm 2 3.5A / dm 2 4.0A / dm 2 4.5A / dm 2 5.0A / dm 2 5.5A / dm 2 6.0A / dm 2 Or a range of any two of these; the temperature for the anti-oxidation treatment can be 20℃, 25℃, 30℃, 35℃, 40℃, 45℃ or a range of any two of these.

[0096] Corrosion protection treatment (or passivation treatment) typically involves forming a denser and more stable inert barrier layer on top of the anti-oxidation layer using chemical or electrochemical methods. Commonly used passivation methods include organic nitrogen heterocyclic compounds (such as BTA) or trivalent chromium. The current density for corrosion protection treatment is controlled at 0.25 A / dm³.2 ~6A / dm 2 This process promotes the formation of a dense passivation film and facilitates faster and more uniform coordination and binding with BTA molecules, resulting in a strong, dense, and seamless polymer protective film. Simultaneously, it ensures uniform adsorption of passivating agent molecules across all microscopic surfaces, including coarsened nodules, achieving comprehensive coverage. Controlling the corrosion protection treatment temperature to 20℃~45℃ optimizes the passivating agent adsorption behavior, resulting in stronger protection.

[0097] For example, the current density for corrosion protection treatment can be 0.25 A / dm. 2 0.3A / dm 2 0.5A / dm 2 1.0A / dm 2 1.5A / dm 2 2.0A / dm 2 2.5A / dm 2 3.0A / dm 2 3.5A / dm 2 4.0A / dm 2 4.5A / dm 2 5.0A / dm 2 5.5A / dm 2 6.0A / dm 2 Or a range of any two of these; the temperature for corrosion protection treatment can be 20℃, 25℃, 30℃, 35℃, 40℃, 45℃ or a range of any two of these.

[0098] In some specific embodiments, the anti-oxidation electrolyte used in the anti-oxidation treatment includes Cr 6+ Preferably, Cr 6 + The concentration in the anti-oxidation electrolyte is 0.5 g / L-6 g / L; preferably, the pH of the anti-oxidation electrolyte is 8.0-12.0.

[0099] In this embodiment, by controlling the Cr content in the anti-oxidation electrolyte... 6+ The concentration of the electrolyte, ranging from 0.5 g / L to 6 g / L, ensures rapid and uniform adsorption of chromate molecules on the copper foil surface, forming a complete and dense passivation film that effectively isolates air and moisture. Simultaneously, it allows for control over the passivation film thickness, providing sufficient protection without being too thick and affecting subsequent processing (such as lamination) or increasing costs. Furthermore, the pH of the anti-oxidation electrolyte is controlled at alkalinity, ensuring that chromate molecules are effectively absorbed. 6+ It tends to form a more stable oxide film dominated by trivalent chromium.

[0100] For example, Cr in the anti-oxidation electrolyte 6+The concentration can be 0.5 g / L, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, 5.5 g / L, 6 g / L, or any combination thereof; the pH of the anti-oxidation electrolyte can be 8.0, 9.0, 10.0, 11.0, 12.0, or any combination thereof.

[0101] In some specific implementations, the anti-corrosion electrolyte used in the anti-corrosion treatment includes Zn. 2+ and K4P2O7; preferably, Zn 2+ The concentration of K4P2O7 in the anti-corrosion electrolyte is 1 g / L-25 g / L; preferably, the concentration of K4P2O7 in the anti-corrosion electrolyte is 50 g / L-300 g / L; preferably, the pH of the anti-corrosion electrolyte is 8.0-12.0.

[0102] It should be understood that Zn 2+ It is the "core raw material" for forming the anti-corrosion coating, controlling Zn 2+ The concentration of potassium pyrophosphate (K4P2O7) in the anti-corrosion electrolyte is 1 g / L-25 g / L, which can control the deposition rate and coating thickness of the anti-corrosion protective layer. Matching this concentration with the current density helps to improve cathodic polarization, resulting in a crystal nucleation rate greater than the growth rate, thus obtaining a fine-grained, smooth coating with better barrier protection. 2+ This not only improves coating quality but also acts as a pH buffer, helping to maintain the stability of the electrolyte's pH value. By controlling the concentration of K4P2O7 in the anti-corrosion electrolyte to 50g / L-300g / L, the concentration of Zn can be ensured. 2+ It exists in a complex morphology conducive to electrodeposition, directly ensuring the excellent quality of the coating from a fundamental perspective. At this concentration, K4P2O7 also promotes normal anode dissolution and prevents Zn from damaging the anode surface. 2+ Accumulation and passivation ensure uniform dissolution of the anode and maintain Zn 2+ Concentration stability.

[0103] For example, Zn 2+The concentration of K4P2O7 in the anti-corrosion electrolyte can be 1 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, or any combination thereof; the concentration of K4P2O7 in the anti-corrosion electrolyte can be 50 g / L, 75 g / L, 100 g / L, 125 g / L, 150 g / L, 175 g / L, 200 g / L, 225 g / L, 250 g / L, 275 g / L, 300 g / L, or any combination thereof; the pH of the anti-corrosion electrolyte can be 8.0, 9.0, 10.0, 11.0, 12.0, or any combination thereof.

[0104] In some specific embodiments, the surface treatment also includes silane coupling agent spraying and drying. Preferably, the silane coupling agent includes at least one of sulfur silane coupling agents, amino silane coupling agents, and epoxy silane coupling agents.

[0105] In this embodiment, a silane coupling agent is uniformly sprayed onto the surface of the copper foil after anti-corrosion treatment, and then dried and wound up at 190°C. The silane coupling agent bonds with the copper foil surface through -Si-OC- bonds to form a silane self-assembled film, the thickness of which is generally 1nm-3nm, in order to improve the interfacial adhesion strength and reduce the surface energy.

[0106] Specifically, the copper foil surface is treated with a silane coupling agent spraying process, which includes the following steps:

[0107] 1. Copper foil surface cleaning and activation: Soak or wipe the copper foil surface with organic solvents (such as acetone, ethanol, isopropanol) to thoroughly remove oil and organic contaminants; then use dilute acid to remove the oxide layer (Cu2O, CuO) on the surface, forming a fresh, active micro-rough surface, increasing the specific surface area and reactive sites; then rinse the copper foil surface with plenty of deionized water to thoroughly remove residual acid and impurity ions;

[0108] 2. Preparation of silane solution: First, select the appropriate silane based on the type of material to be laminated with the copper foil. For example, when bonding with epoxy resin, KH-550 (γ-aminopropyltriethoxysilane) can be used for spraying; when bonding with polyurethane, KH-560 (γ-glycidoxypropyltrimethoxysilane) can be used; and when bonding with polyethylene, vinyltriethoxysilane can be selected. Since the silane coupling agent needs to be hydrolyzed to generate active silanols before it can bond with the hydroxyl groups on the copper foil surface, the silane coupling agent must first be dissolved in a mixture of deionized water and ethanol or methanol (e.g., volume ratio of ethanol:water = 9:1 or 8:2), with a volume percentage of 1%-5%; and a small amount of acetic acid should be added to adjust the pH to 4-5.5. This acidic environment is beneficial for the hydrolysis and stability of the silane.

[0109] 3. Spraying: When using silane coupling agent for spraying, the silane solution is evenly sprayed onto the rough surface of the copper foil through the spray pipe, and the water pressure is usually between 0.2MPa and 0.5MPa.

[0110] 4. After spraying, the copper foil is conveyed to the oven through guide rollers, so that the silane solution can be fully spread on the surface and complete the chemical bonding with the copper foil surface. The drying is completed at the oven temperature of 100℃-250℃.

[0111] The copper foil preparation method provided in this application achieves the reduction and stable control of the roughness of the untreated surface of the copper foil by means of synergistic regulation of the mixed additive system (at least two of polyether derivatives, collagen compounds, and polysaccharide compounds) and electrolyte process parameters, while taking into account the requirements of conductivity, peel strength and environmental protection.

[0112] Figure 1 This is a schematic diagram of the structure of the copper foil provided in this application, which is prepared by the above-described preparation method.

[0113] In some specific embodiments, the copper foil includes an untreated surface and a treated surface; when the thickness of the copper foil is 35 μm, the roughness of the untreated surface is 2.0 μm-3.0 μm, and the roughness of the treated surface is 2.0 μm-3 μm; when the thickness of the copper foil is 70 μm, the roughness of the untreated surface is 3.0 μm-5.0 μm, and the roughness of the treated surface is 2.0 μm-3 μm.

[0114] In some embodiments, this application achieves stable control of the untreated surface roughness (Rz) of 35μm copper foil within the range of 2.0μm-3.0μm and the untreated surface roughness (Rz) of 70μm copper foil within the range of 3.0μm-5.0μm through the synergistic effect of mixed additives and electrolysis parameters, with a fluctuation range of less than or equal to 0.2μm. By employing a roughening-curing combined process, a gradient match is achieved between the treated surface Rz value (2.45μm~2.73μm) and the untreated surface, meeting the differentiated requirements of high-frequency communication for double-sided roughness.

[0115] In some specific implementations, the roughness standard deviation of the untreated surface is less than or equal to 0.099.

[0116] This application also provides a circuit board comprising copper foil prepared by the above-described preparation method or the copper foil described above.

[0117] The circuit board provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0118] The technical solution of this application will be further described below using specific embodiments.

[0119] Example 1

[0120] A copper foil, the preparation method of which is as follows:

[0121] Copper deposition electrolysis: The electrolyte is electrolyzed at 40℃ using a current of 20kA to obtain a copper foil intermediate; wherein the electrolyte includes 80g / L H2SO4 and 60g / L Cu. 2+ 10ppm Cl - 40 ppm hydroxyethyl cellulose and 40 ppm bone glue;

[0122] Surface treatment: The obtained copper foil intermediate is subjected to the following surface treatments in sequence:

[0123] 1. Two coarse and two solid treatments:

[0124] Roughening I: Current density 8 A / dm², temperature 25℃; in roughening solution I, H₂SO₄ concentration 110 g / L, Cu 2+ Concentration 7 g / L;

[0125] Curing I: Current density 15 A / dm², temperature 35℃; in curing solution I, H₂SO₄ concentration 95 g / L, Cu 2+ Concentration 25 g / L;

[0126] Roughening II: Current density 8 A / dm², temperature 25℃; in roughening solution II, H₂SO₄ concentration 110 g / L, Cu 2+ Concentration 7 g / L;

[0127] Curing II: Current density 15 A / dm², temperature 35℃; In curing solution I, H₂SO₄ concentration 95 g / L, Cu 2+ Concentration 25 g / L;

[0128] Corrosion protection treatment: current density 1A / dm², temperature 35℃; Zn in the corrosion-resistant electrolyte. 2+ Concentration 15 g / L, potassium pyrophosphate (K4P2O7) concentration 190 g / L, pH=11;

[0129] Anti-oxidation treatment: current density 1.2 A / dm², temperature 35℃, in the anti-oxidation electrolyte, Cr 6+ Concentration 1.5 g / L, pH=10;

[0130] Silane spraying: The surface after anti-oxidation treatment was cleaned with ethanol and 5% dilute hydrochloric acid, and then rinsed with deionized water; a silane solution containing 1% KH-550 by volume was sprayed at a pressure of 0.2 MPa; after spraying, it was dried in an oven at 190℃ to obtain a copper foil with a thickness of 35 μm.

[0131] Example 2

[0132] A copper foil is prepared in a manner that is basically the same as in Example 1, except that the concentration of hydroxyethyl cellulose used is 2 ppm.

[0133] Example 3

[0134] A copper foil is prepared in a manner that is basically the same as in Example 1, except that the concentration of hydroxyethyl cellulose used is 1 ppm.

[0135] Example 4

[0136] A copper foil is prepared in a manner that is basically the same as in Example 1, except that the concentration of hydroxyethyl cellulose used is 80 ppm.

[0137] Example 5

[0138] A copper foil is prepared in a manner that is basically the same as in Example 4, except that the concentration of hydroxyethyl cellulose used is 81 ppm.

[0139] Example 6

[0140] A copper foil is prepared in a manner that is basically the same as in Example 3, except that the concentrations of hydroxyethyl cellulose and bone glue used are both 1 ppm.

[0141] Example 7

[0142] A copper foil is prepared in a manner that is basically the same as in Example 5, except that the concentrations of hydroxyethyl cellulose and bone glue used are both 81 ppm.

[0143] Example 8

[0144] A copper foil is prepared in a manner that is basically the same as that in Example 1, except that the additives used are hydroxyethyl cellulose and PEG-400.

[0145] Example 9

[0146] A copper foil is prepared in a manner that is basically the same as in Example 1, except that the additives used are hydroxyethyl cellulose and hyaluronic acid.

[0147] Example 10

[0148] A copper foil, the preparation method of which is basically the same as that of Example 1, except that the additives used are PEG-400 and bone glue.

[0149] Example 11

[0150] A copper foil is prepared in a manner that is basically the same as in Example 1, except that the additives used are PEG-400 and hyaluronic acid.

[0151] Example 12

[0152] A copper foil is prepared in a manner that is basically the same as in Example 1, except that the additives used are bone glue and hyaluronic acid, and the thickness of the prepared copper foil is 70 μm.

[0153] Example 13

[0154] A copper foil, prepared in a manner essentially the same as in Example 1, differs in that, during copper deposition electrolysis, the concentration of H2SO4 in the electrolyte is 160 g / L, and the Cu... 2+ The concentration is 105 g / L, Cl - The concentration is 75 ppm.

[0155] Example 14

[0156] A copper foil, prepared in a manner essentially the same as in Example 1, differs in that, during copper deposition electrolysis, the concentration of H2SO4 in the electrolyte is 70 g / L, and the Cu... 2+ The concentration is 50 g / L, Cl - The concentration is 5 ppm.

[0157] Example 15

[0158] A copper foil, prepared in a manner essentially the same as in Example 13, except that during copper deposition electrolysis, the concentration of H2SO4 in the electrolyte is 170 g / L, and the Cu... 2+ The concentration is 110 g / L, Cl - The concentration is 80 ppm.

[0159] Example 16

[0160] A copper foil is prepared in a manner that is basically the same as in Example 1, except that the electrolysis temperature during copper deposition is 20°C.

[0161] Example 17

[0162] A copper foil is prepared in a manner that is basically the same as that in Example 16, except that the electrolysis temperature during copper deposition is 15°C.

[0163] Example 18

[0164] A copper foil is prepared in a manner that is basically the same as in Example 1, except that the electrolysis temperature during copper deposition is 70°C.

[0165] Example 19

[0166] A copper foil is prepared in a manner that is basically the same as in Example 1, except that the electrolysis temperature during copper deposition is 80°C.

[0167] Example 20

[0168] A copper foil is prepared in a manner that is basically the same as that in Example 19, except that the electrolysis temperature during copper deposition is 85°C.

[0169] Example 21

[0170] A copper foil is prepared using a method essentially the same as in Example 1, except that the current density for both roughening I and roughening II is 2 A / dm². 2 The temperature was 35℃.

[0171] Example 22

[0172] A copper foil is prepared using a method essentially the same as in Example 1, except that the current density for both roughening I and roughening II is 25 A / dm². 2 The temperature was 15℃.

[0173] Example 23

[0174] A copper foil is prepared using a method essentially the same as in Example 1, except that the current density for both curing I and curing II is 2 A / dm². 2 The temperature was 35℃.

[0175] Example 24

[0176] A copper foil is prepared using a method essentially the same as in Example 1, except that the current density for both curing I and curing II is 23 A / dm². 2 The temperature was 45℃.

[0177] Example 25

[0178] A copper foil, prepared in a manner essentially the same as in Example 1, except that in roughening solutions I and II, the concentration of H2SO4 is 70 g / L, and the Cu... 2+ Concentration 5g / l.

[0179] Example 26

[0180] A copper foil, prepared in a manner essentially the same as in Example 1, except that the concentration of H2SO4 in roughening solution I and roughening solution II is 190 g / L, and the Cu... 2+ Concentration 28g / l.

[0181] Example 27

[0182] A copper foil, prepared in a manner essentially the same as in Example 1, except that the concentration of H2SO4 in curing solution I and curing solution II is 50 g / L, and the Cu... 2+ Concentration 15g / l.

[0183] Example 28

[0184] A copper foil, prepared in a manner essentially the same as in Example 1, except that the concentration of H2SO4 in curing solution I and curing solution II is 130 g / L, and the Cu... 2+ Concentration 70g / l.

[0185] Example 29

[0186] A copper foil, prepared in a manner essentially the same as in Example 1, except that the surface treatment further includes roughening III: current density 8 A / dm², temperature 25°C; in roughening solution III, the concentration of H₂SO₄ is 110 g / L, and Cu... 2+ Concentration 7 g / L; and Curing III: current density 15 A / dm², temperature 35℃; in curing solution III, H₂SO₄ concentration 95 g / L, Cu 2+ Concentration 25g / l.

[0187] Example 30

[0188] A copper foil is prepared in a manner that is basically the same as in Example 1, except that roughening II and curing II are not performed.

[0189] Comparative Example 1

[0190] A copper foil is prepared in a manner that is basically the same as in Example 1, except that hydroxyethyl cellulose is not added.

[0191] Comparative Example 2

[0192] A copper foil, the preparation method of which is basically the same as that of Example 1, except that no bone glue is added.

[0193] Comparative Example 3

[0194] A copper foil is prepared in a manner that is basically the same as in Example 1, except that hydroxyethyl cellulose and bone glue are not added.

[0195] The copper foils obtained in the above embodiments and comparative examples were subjected to the following performance tests:

[0196] Roughness: Use a contact roughness tester (such as FORMTRACER Avant S3000) to measure the Rz value (average of 10 points) and standard deviation of the untreated and treated surfaces;

[0197] Resistivity: The resistivity of the copper foil surface was measured using the four-probe method, referring to ASTM B193-20, "Standard Test Method for Resistivity of Electrical Conductor Materials".

[0198] Peel strength: The peel force at 180° was tested using a peel testing machine (PST-R5).

[0199] The test results are shown in Table 1.

[0200] Table 1

[0201]

[0202]

[0203] As shown in Table 1, the copper foil prepared by the method provided in this application has the following properties: when the thickness of the copper foil is 35 μm, the roughness of the non-roughened surface can be controlled within the range of 2.0 μm-3.0 μm, and the roughness of the processed surface can be controlled within the range of 2.0 μm-3.0 μm; when the thickness of the copper foil is 70 μm, the roughness of the non-roughened surface can be controlled within the range of 3.0 μm-5.0 μm, and the roughness of the processed surface can be controlled within the range of 2.0 μm-3.0 μm. Importantly, the standard deviation of the roughness is less than 0.2, and can reach as low as 0.075. Moreover, the resistivity of the copper foil is basically maintained at around 0.160 μΩ·cm, and the peel strength reaches a level greater than 1 MPa. It can be seen that the copper foil prepared by the method provided in this application has lower roughness and roughness standard deviation, while ensuring certain conductivity and peel strength, and has good practical application value.

[0204] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for producing a copper foil, characterized by, The application relates to a method for preparing a copper foil. The method comprises the following steps: The copper foil is obtained by surface treatment of a copper foil intermediate obtained by copper deposition electrolysis of a green foil in an electrolyte. The electrolyte comprises H2SO4, Cu 2+ , Cl - and additives; The additive comprises at least two of cellulose ether, polyether derivative, collagen compound and polysaccharide compound.

2. The method of producing a copper foil according to claim 1, characterized by, The additive comprises hydroxyethyl cellulose and bone glue.

3. The production method of the copper foil according to claim 1 or 2, characterized by, The concentration of H2SO4 in the electrolyte is 80 g / l-160 g / l. and / or the Cu 2+ concentration is 60 g / l to 105 g / l; and / or the concentration of Cl - is 10 ppm to 75 ppm; The concentration of any additive in the electrolyte is 2 ppm-80 ppm.

4. The method of producing a copper foil according to any one of claims 1 to 3, characterized in that, The electrolysis temperature of the copper deposition electrolysis is 20 DEG C-80 DEG C, preferably 40 DEG C-70 DEG C. The electrolysis current of the copper deposition electrolysis is 20 kA-50 kA.

5. The method of producing a copper foil according to any one of claims 1 to 4, characterized in that, The surface treatment comprises roughening and solidification. The roughening current density is 2 A / dm 2 25 A / dm 2 The roughening temperature is 15°C to 35°C. The solidification current density is 2 A / dm 2 23 A / dm 2 The solidification temperature is 25°C to 45°C.

6. The method for preparing a copper foil according to claim 5, wherein The roughening liquid used for the roughening includes H2SO4 and Cu 2+ ; The concentration of H2SO4 in the roughening solution is 70 g / L-190 g / L. The Cu 2+ The concentration in the roughening solution is 5-28 g / L. and / or the solidification uses a solidification liquid including H2SO4 and Cu 2+ ; The concentration of H2SO4 in the solidification solution is 50 g / L-130 g / L. The Cu 2+ The concentration in the roughening solution is 15 g / L to 70 g / L.

7. The method of producing a copper foil according to any one of claims 5 to 6, characterized in that, The number of times of the solidification treatment is greater than or equal to the number of times of the roughening treatment. The surface treatment comprises at least two times of roughening and at least two times of solidification.

8. The method of producing a copper foil according to any one of claims 1 to 7, characterized in that, The surface treatment further comprises an anti-oxidation treatment and / or an anti-corrosion treatment. The current density of the anti-oxidation treatment is 0.3 A / dm 2 6 A / dm 2 The temperature of the anti-oxidation treatment is 20℃~45℃; The current density of the anticorrosion treatment is 0.25 A / dm 2 6 A / dm 2 The temperature of the anticorrosion treatment is 20℃~45℃.

9. The method of producing a copper foil according to claim 8, characterized in that, The anti-oxidation treatment uses an anti-oxidation electrolyte including Cr 6+ ; The Cr 6+ in the anti-oxidation electrolyte is 0.5 g / L-6 g / L; The pH of the anti-oxidation electrolyte is 8.0-12.

0. And / or, the anticorrosion treatment uses an anticorrosion electrolyte including Zn 2+ and K4P2O7; The Zn 2+ The concentration in the anticorrosion electrolyte is 1-25 g / L. The concentration of K4P2O7 in the anti-corrosion electrolyte is 50 g / L-300 g / L. The pH of the anti-corrosion electrolyte is 8.0-12.

0.

10. The method of producing a copper foil according to any one of claims 1 to 9, characterized in that, The surface treatment further comprises silane coupling agent spraying and drying. The silane coupling agent comprises at least one of sulfur-containing silane coupling agent, amino silane coupling agent and epoxy silane coupling agent.

11. A copper foil, characterized by, The copper foil is prepared by the method according to any one of claims 1-11.

12. The copper foil according to claim 11, characterized by, The copper foil comprises a non-treated surface and a treated surface. When the thickness of the copper foil is 35 mu m, the roughness of the non-treated surface is 2.0 mu m-3.0 mu m, and the roughness of the treated surface is 2.0 mu m-3.0 mu m. When the thickness of the copper foil is 70 mu m, the roughness of the non-treated surface is 3.0 mu m-5.0 mu m, and the roughness of the treated surface is 2.0 mu m-3.0 mu m.

13. The copper foil according to claim 12, characterized by, The standard deviation of the roughness of the non-treated surface is less than or equal to 0.

099.

14. A circuit substrate, characterized by comprising: The copper foil is prepared by the method according to any one of claims 1-10 or the copper foil according to any one of claims 11-13.

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