Surface treatment method of rolled copper foil

Abstract

The invention relates to a surface treatment method of rolled copper foil. The surface treatment method comprises the steps of degreasing, electrochemical corrosion and roughening. In the electrochemical step, the rolled copper foil serves as an anode, electrochemical corrosion treatment is conducted on the copper foil in an acid pretreatment solution, the defects of surface rolling lines, peeling and the like are removed, and the copper foil surface which is flat macroscopically and rough microcosmically is obtained. In the coarsening step, an additive is added into a coarsening solution, and fine copper particles are electroplated on the surface of the copper foil, so that the performance requirements of low roughness and high stripping resistance of the copper foil are met, and the use requirements of the high-frequency circuit board are met.

Description

Technical Field

[0001] The invention relates to the technical field of rolled copper foil, and in particular to a surface treatment method of rolled copper foil. Background Art

[0002] Rolled copper foil is a key raw material for PCB laminates. With the continuous development of the fifth generation of mobile communication technology (5G) around the world, rolled copper foil also faces the problem of high-frequency signal transmission. Usually, when the signal transmission frequency is above 1GHz, the electrical signal is no longer transmitted through the inside of the conductor, but through the surface of the conductor, which is called the "skin effect". At this time, slight changes in the surface roughness of the copper foil will affect the signal loss. This requires that the copper foil has a low roughness. In addition, the production of PCB boards requires the copper foil to be combined with a resin film, which requires that the copper foil has a high peel strength to ensure the bonding between the copper foil and the resin.

[0003] When the surface of the rolled copper foil of the existing PCB board is treated, it is usually degreased, pickled and roughened before the oxide layer is electroplated. However, after the degreasing and pickling treatments, the rolling texture on the surface of the copper foil substrate cannot be effectively removed, resulting in poor surface flatness of the copper foil substrate, which leads to poor bonding between the coating and the copper foil substrate, reduces the peeling strength of the copper foil, and even causes the coating to fall off or powder to fall off. Through the roughening treatment, a layer of copper particles is electroplated on the surface of the copper foil. Although the peeling strength of the copper foil can be improved, the roughness of the copper foil will be significantly increased due to the large size of the particles in the roughening layer, which will affect the roughness of the final rolled copper foil product.

[0004] Therefore, the rolled copper foil product prepared by the existing surface treatment method cannot meet the performance requirements of low roughness and high peel strength, and thus cannot meet the use requirements of high-frequency circuit boards. Summary of the invention

[0005] In view of the above problems, the present invention is proposed to provide a surface treatment method for rolled copper foil that overcomes the above problems or at least partially solves the above problems, so as to eliminate defects such as rolling marks before roughening treatment and reduce the size of roughening layer particles, so that the rolled copper foil has low roughness and high peeling strength, which can meet the use requirements of high-frequency circuit boards.

[0006] Specifically, the present invention provides a surface treatment method for a rolled copper foil, which comprises the following steps in sequence:

[0007] Degreasing: Degreasing liquid is used to degrease the rolled copper foil after rolling;

[0008] Electrochemical corrosion: using the rolled copper foil as an anode and performing electrochemical corrosion in an acidic pretreatment solution; wherein the acidic pretreatment solution comprises sulfuric acid, cupric chloride, a complexing agent and water, and the complexing agent comprises one or more of disodium ethylenediaminetetraacetate, citric acid, oxalic acid, tartaric acid, sodium gluconate and lactic acid;

[0009] Roughening: The rolled copper foil is roughened with a roughening liquid; the roughening liquid includes copper sulfate, sulfuric acid and additives, and the additives include one or more of sodium polydipropylene sulfonate, polyethylene glycol, polyvinyl alcohol, guar gum and carrageenan.

[0010] Optionally, the concentration of sulfuric acid in the acidic pretreatment solution is 100-150 g / L, the concentration of cupric chloride is 20-30 g / L, and the concentration of the complexing agent is 5-20 g / L.

[0011] Optionally, in the electrochemical corrosion step:

[0012] The temperature of the acidic pretreatment solution is 30-40°C;

[0013] The electrochemical corrosion time is 0.5 to 2 minutes;

[0014] The electrochemical corrosion voltage is 0.3~0.6V.

[0015] Optionally, the concentration of the additive in the roughening solution is 0.01 to 3 g / L.

[0016] Optionally, the Cu in the roughening solution 2+ The concentration is 20-30 g / L, and the concentration of sulfuric acid is 80-100 g / L.

[0017] Optionally, in the roughening step:

[0018] Current density is 15~30A / dm 2 ;

[0019] The coarsening time is 2 to 4 seconds.

[0020] Optionally, before the electrochemical corrosion step, the following steps are also included:

[0021] Prepare an acidic pretreatment solution: dissolve sulfuric acid, cupric chloride and a complexing agent in water to prepare an acidic pretreatment solution.

[0022] Optionally, before the roughening treatment of the rolled copper foil with the roughening solution, the method further includes: washing the electrochemically corroded rolled copper foil with water to wash away the acidic pretreatment solution on the surface of the rolled copper foil.

[0023] Optionally, in the degreasing step: the degreasing is chemical degreasing, the concentration of sodium hydroxide in the degreasing liquid is 30-40 g / L, the concentration of the surfactant is 1-2 g / L, the temperature of the degreasing liquid is 50-60° C., and the degreasing time is 6-10 s.

[0024] Optionally, the rolled copper foil has a thickness of 9 to 70 μm after rolling.

[0025] The beneficial effects of the present invention are:

[0026] The present invention replaces the pickling step in the prior art with an electrochemical etching step, using the copper foil as the anode and electrochemically etching the degreased copper foil using an acidic pretreatment solution. Since the acidic pretreatment solution includes sulfuric acid, copper chloride and a complexing agent, the surface of the copper foil can be etched flat, and the oxide layer, rolling lines and processing defects on the surface of the copper foil can be etched away.

[0027] Specifically, on the one hand, since copper is a relatively active metal and can be dissolved in acidic solutions such as sulfuric acid, the stronger the acidity, the stronger the corrosion of the solution on the copper material; the sulfuric acid in the acidic pretreatment solution has a strong corrosive effect on the copper material. On the other hand, due to the small radius and strong penetration ability of chloride ions, they can be preferentially adsorbed on the surface of copper foil, destroying the passivation film and causing local corrosion. Chloride ions accelerate the corrosion of copper through two mechanisms: phase film theory and adsorption theory. The phase film theory believes that chloride ions will react with oxides on the copper surface to form soluble chlorides, thereby destroying the passivation film; the adsorption theory believes that chloride ions will adsorb on the passivation film, squeeze out oxygen atoms, form small pits, and then cause corrosion. Therefore, the present invention utilizes the acidity of the solution and the corrosion effect of chloride ions to accelerate the electrochemical corrosion process, thereby removing defects such as rolling marks, peeling, scratches, etc. on the surface of the rolled copper foil, and obtaining a surface that is flat on a macroscopic level and slightly rough on a microscopic level, which is beneficial to improving the subsequent mechanical adhesion between the copper foil substrate and the coating, thereby facilitating improving the bonding strength between the copper foil finished product and the resin when in use, and can also improve the surface quality of the copper foil.

[0028] On the other hand, the acidic pretreatment liquid contains a complexing agent, and the complexing agent is a copper complexing agent, which can accelerate the dissolution of copper powder such as copper oxide produced after electrochemical corrosion, prevent the formation of a passivation film on the surface of the copper foil substrate, and affect the subsequent roughening and electroplating anti-oxidation layer steps.

[0029] Furthermore, in the roughening step after electrochemical corrosion, the present invention adds an additive to the roughening solution, and the additive can affect the nucleation density and distribution of copper particles by changing the reaction potential of copper deposition, thereby affecting the microstructure and morphology of the coating. In other words, the additive can regulate the nucleation growth process of copper particles, thereby regulating the size and shape of the roughening layer particles, increasing the roughening specific surface area, and avoiding excessively large particles in the roughening layer, which is not only conducive to improving the anti-peel strength of the copper foil, but also does not significantly increase the surface roughness of the copper foil.

[0030] The surface treatment method of the present invention is advantageous for making the surface of the rolled copper foil uniform and dense after surface treatment, and having low roughness and high peeling strength, thereby being able to meet the performance requirements of high-frequency circuit boards.

[0031] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0033] Figure 1 is a SEM image of the rolled copper foil after roughening treatment in Example 1;

[0034] Figure 2 is a SEM image of the rolled copper foil after roughening treatment in Example 2;

[0035] Figure 3 is a SEM image of the rolled copper foil after roughening treatment in Example 3;

[0036] Figure 4 is a SEM image of the rolled copper foil after roughening treatment in Example 4;

[0037] Figure 5 This is a SEM image of the rolled copper foil after roughening treatment in Comparative Example 1;

[0038] Figure 6 It is a schematic flow chart of a surface treatment method of a rolled copper foil according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] To make the purpose, technical scheme and advantages of the embodiment of the present invention clearer, the technical scheme in the embodiment of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiment, it is carried out according to the normal conditions or the conditions recommended by the manufacturer. If the reagents or instruments used do not specify the manufacturer, they are all conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes, taking "A and / or B" as an example, including scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that the combination of such technical solutions does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present invention.

[0040] The embodiment of the present invention provides a surface treatment method for a rolled copper foil, which comprises the following steps: using the rolled copper foil as a substrate, and sequentially performing degreasing, electrochemical etching, and roughening on the rolled copper foil substrate.

[0041] The degreasing step specifically includes: using a degreasing liquid to degrease the rolled copper foil substrate after rolling to remove grease and dirt on the surface of the rolled copper foil.

[0042] The electrochemical corrosion step is specifically as follows: the rolled copper foil after degreasing treatment is used as an anode, and the rolled copper foil is electrochemically corroded in an acidic pretreatment solution to remove the rolling lines, peeling, scratches and other defects on the surface of the rolled copper foil, so as to obtain a surface that is flat in the macroscopic view and rough in the microscopic view. The acidic pretreatment solution includes sulfuric acid, copper chloride, a complexing agent and water, and the complexing agent is a copper complexing agent. Specifically, the complexing agent includes one or more of disodium ethylenediaminetetraacetic acid, citric acid, oxalic acid, tartaric acid, sodium gluconate and lactic acid. In the electrochemical corrosion process, the copper foil is used as an anode, and the copper thin surface will be oxidized to form copper oxide powder, etc.; the copper complexing agent can quickly dissolve the copper oxide and other copper powders to avoid the formation of a copper oxide passivation film on the surface of the copper foil.

[0043] Roughening: Roughening the rolled copper foil after electrochemical corrosion treatment with a roughening solution to electroplate a roughening layer on the surface of the rolled copper foil, the roughening layer consisting of fine copper particles. The roughening solution includes copper sulfate, sulfuric acid and additives, and the additives include one or more of sodium polydisulfide dipropane sulfonate, polyethylene glycol, polyvinyl alcohol, guar gum, and carrageenan.

[0044] Compared with the prior art, this embodiment mainly makes the following two improvements:

[0045] 1. Replace ordinary pickling with electrochemical corrosion, and use the acidity of the solution and the corrosion effect of chloride ions to accelerate the electrochemical corrosion process. The complexing agent can accelerate the dissolution of copper powder such as copper oxide after electrochemical corrosion, prevent the formation of a passivation film on the surface, and affect subsequent electroplating.

[0046] 2. In the roughening step, additives are added to the roughening solution to regulate the size and formation of copper particles in the roughening copper plating process and increase the roughening specific surface area to form uniform, dense, micro-nano copper particles.

[0047] Therefore, the electrochemical corrosion pretreatment process can solve the problem of poor flatness caused by defects such as rolling marks on the surface of the rolled copper foil, as well as the problem of poor bonding between the substrate and the coating caused by the low roughness of the rolled copper foil substrate. By then adjusting the coarsening particles through additives, the requirements of low roughness and high peel strength of the rolled copper foil can be achieved together, thereby meeting the performance requirements of high-frequency circuit boards.

[0048] In some optional embodiments of the present invention, the concentration of sulfuric acid in the acidic pretreatment solution is 100-150 g / L, the concentration of cupric chloride is 20-30 g / L, and the concentration of the complexing agent is 5-20 g / L.

[0049] For example, the sulfuric acid concentration may be any one of 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, and 150 g / L.

[0050] The copper chloride concentration may be any one of 20 g / L, 22 g / L, 24 g / L, 25 g / L, 26 g / L, 28 g / L, and 30 g / L.

[0051] The concentration of the complexing agent may be any one of 5 g / L, 8 g / L, 10 g / L, 12 g / L, 15 g / L, 18 g / L, and 20 g / L.

[0052] By setting reasonable sulfuric acid concentration, cupric chloride concentration and complexing agent concentration, this embodiment can not only control the speed of electrochemical corrosion and prevent over-corrosion; it can also enable the complexing agent to promptly and effectively dissolve copper powder such as copper oxide after corrosion, so as to effectively prevent the formation of a passivation film on the surface of the copper foil.

[0053] In some optional embodiments of the present invention, in the electrochemical corrosion step: the temperature of the acidic pretreatment solution is 30-40° C.; the electrochemical corrosion time is 0.5-2 min; and the electrochemical corrosion voltage is 0.3-0.6V.

[0054] For example, the temperature of the acidic pretreatment solution can be any one of 30°C, 32°C, 35°C, 36°C, 37°C, 38°C, and 40°C; the electrochemical corrosion time can be any one of 0.5min, 0.7min, 0.9min, 1min, 1.2min, 1.5min, 1.8min, and 2min; the electrochemical corrosion voltage can be any one of 0.3V, 0.4V, 0.5V, and 0.6V.

[0055] This embodiment sets reasonable electrochemical corrosion process parameters, which can not only remove rolling marks, peeling, scratches and other defects on the surface of the rolled copper foil, but also avoid over-corrosion and significantly reduce the thickness of the copper foil substrate.

[0056] In some optional embodiments of the present invention, the concentration of the additive in the roughening liquid is 0.01-3 g / L. By setting a reasonable concentration of the additive, not only the size and shape of the roughened particles can be effectively regulated, but also the cost of the roughening liquid can be reasonably controlled.

[0057] In some optional embodiments of the present invention, the Cu in the roughening solution 2+ The concentration is 20-30 g / L, and the sulfuric acid concentration is 80-100 g / L. 2+ The concentration can be any one of 20g / L, 22g / L, 24g / L, 26g / L, 28g / L, and 30g / L; the sulfuric acid concentration can be any one of 80g / L, 85g / L, 90g / L, 95g / L, and 100 / L.

[0058] In some optional embodiments of the present invention, in the roughening step: the current density is 15-30A / dm 2 ; The roughening time is 2 to 4 seconds. For example: the current density can be 15A / dm 2 、18A / dm 2 、20A / dm 2 、25A / dm 2 、30A / dm 2 The coarsening duration can be any value among 2s, 3s, and 4s.

[0059] By setting reasonable roughening liquid composition and roughening process parameters, it is helpful to improve the roughening efficiency and effect.

[0060] In some optional embodiments of the present invention, before the electrochemical corrosion step, a step of preparing an acidic pretreatment solution is further included. The step of preparing the acidic pretreatment solution is specifically: dissolving sulfuric acid, cupric chloride, and a complexing agent in water to prepare the acidic pretreatment solution.

[0061] In some optional embodiments of the present invention, before the roughening treatment of the rolled copper foil with the roughening liquid, the method further includes: washing the electrochemically corroded rolled copper foil with water to wash off the acidic pretreatment solution on the surface of the rolled copper foil.

[0062] This embodiment can avoid bringing the acidic pretreatment solution into the roughening solution, thereby not only avoiding the acidic pretreatment solution from affecting the roughening effect, but also extending the effective use time of the roughening solution. In addition, it should be noted that, in order to avoid pollution, water washing is provided between electroplating tanks with different functions. The process of copper foil being transferred between tank solutions is relatively short, and the surface of the copper foil is covered by liquid and cannot be exposed to air, so the surface of the copper foil will not be rapidly oxidized.

[0063] In some optional embodiments of the present invention, in the degreasing step: the degreasing is chemical degreasing, the sodium hydroxide concentration in the degreasing solution is 30-40 g / L, the concentration of the surfactant is 1-2 g / L, the temperature of the degreasing solution is 50-60° C., and the degreasing time is 6-10 seconds. In other optional embodiments, other alkaline degreasing agents can also be used, and other alkaline washing parameters can be used.

[0064] In some optional embodiments of the present invention, the rolled copper foil has a thickness of 9-70 μm after rolling, a grade of C1100 / T2, and is made of pure copper. Preferably, the rolled copper foil has a thickness of 35 μm after rolling.

[0065] In some optional embodiments of the present invention, after the roughening step, the surface treatment method further comprises the following steps:

[0066] Electroplating anti-oxidation layer: The rolled copper foil is electroplated to form an anti-oxidation layer on the surface of the rolled copper foil.

[0067] Specifically, Figure 6 As shown, the surface treatment method of rolled copper foil includes the following steps: chemical degreasing, electrochemical corrosion, water washing, roughening, and anti-oxidation. Among them, anti-oxidation refers to electroplating anti-oxidation layer.

[0068] In some optional embodiments of the present invention, the step of electroplating the anti-oxidation layer may include zinc plating and chrome plating.

[0069] Among them, in the galvanizing step: Zn in the galvanizing solution 2+ The concentration is 1.2g / L, the potassium pyrophosphate concentration is 20g / L, the pH of the zinc plating solution is 11, and the current density is 1A / dm 2 , electroplating time is 3s.

[0070] In the chromium plating step: the CrO3 concentration in the chromium plating solution is 1g / L, the pH of the chromium plating solution is 12, and the current density is 1A / dm 2 , electroplating time is 3s.

[0071] In some alternative embodiments, the anti-oxidation layer electroplating process may also be a copper-nickel alloy, zinc-nickel alloy or other electroplating process.

[0072] In some optional embodiments of the present invention, after the step of electroplating the anti-oxidation layer, the surface treatment method further comprises spraying silane treatment. By spraying silane treatment, the peeling resistance of the surface of the rolled copper foil can be further improved.

[0073] The present invention is described in more detail below through specific examples and comparative examples.

[0074] Example 1

[0075] A surface treatment method for rolled copper foil comprises the following steps:

[0076] Degreasing (alkaline washing): Soak the rolled copper foil (brand C1100 / T2, made of pure copper, 35 μm thick) in a 50°C sodium hydroxide solution with a sodium hydroxide concentration of 30 g / L and a surfactant sodium dodecyl sulfate concentration of 1 g / L for 8 seconds.

[0077] Prepare an acidic pretreatment solution: dissolve sulfuric acid, cupric chloride, and disodium ethylenediaminetetraacetate in water to prepare an acidic pretreatment solution, so that the concentration of sulfuric acid in the acidic pretreatment solution is 100 g / L, the concentration of cupric chloride is 20 g / L, the concentration of disodium ethylenediaminetetraacetate is 5 g / L, and the solution temperature is 30°C.

[0078] Electrochemical corrosion: The copper foil was used as the anode and the 2 mm thick copper plate was used as the cathode. The copper foil was electrochemically corroded in an acidic pretreatment solution. The corrosion time was 30 s and the corrosion voltage was 0.3 V.

[0079] Roughening: The copper foil after electrochemical corrosion was rinsed with distilled water and then roughened. The copper ion concentration in the roughening solution was 20 g / L, the sulfuric acid concentration was 80 g / L, the additives included sodium polydisulfide dipropane sulfonate and guar gum, the concentration of sodium polydisulfide dipropane sulfonate in the roughening solution was 0.01 g / L, and the concentration of guar gum was 0.1 g / L; the roughening current density was 20 A / dm 2 , the coarsening time is 3s.

[0080] Example 2

[0081] A surface treatment method for rolled copper foil comprises the following steps:

[0082] Degreasing (alkaline washing): The degreasing step is the same as that of Example 1, and the copper foil substrate used is also the same.

[0083] Prepare an acidic pretreatment solution: dissolve sulfuric acid, cupric chloride and citric acid in water to prepare an acidic pretreatment solution, so that the concentration of sulfuric acid in the acidic pretreatment solution is 150 g / L, the concentration of cupric chloride is 30 g / L, the concentration of citric acid is 10 g / L, and the solution temperature is 35°C.

[0084] Electrochemical corrosion: A 2 mm thick copper plate was used as the cathode and a copper foil was used as the anode for electrochemical corrosion in an acidic pretreatment solution. The corrosion time was 2 min and the corrosion voltage was 0.6 V.

[0085] Roughening: The copper foil after electrochemical corrosion was rinsed with distilled water and then roughened; the copper ion concentration in the roughening solution was 30 g / L, the sulfuric acid concentration was 150 g / L, the additives included sodium polydisulfide propane sulfonate and polyethylene glycol, the concentration of sodium polydisulfide propane sulfonate in the roughening solution was 0.01 g / L, and the concentration of polyethylene glycol was 0.1 g / L; the roughening current density was 30 A / dm 2 , the coarsening time is 3s.

[0086] Example 3

[0087] A surface treatment method for rolled copper foil comprises the following steps:

[0088] Degreasing (alkaline washing): The degreasing step is the same as that of Example 1, and the copper foil substrate used is also the same.

[0089] Prepare an acidic pretreatment solution: dissolve sulfuric acid, cupric chloride and lactic acid in water to prepare an acidic pretreatment solution, so that the concentration of sulfuric acid in the acidic pretreatment solution is 120 g / L, the concentration of cupric chloride is 25 g / L, the concentration of lactic acid is 20 g / L, and the solution temperature is 35°C.

[0090] Electrochemical corrosion: A 2 mm thick copper plate was used as the cathode and a copper foil was used as the anode for electrochemical corrosion in an acidic pretreatment solution. The corrosion time was 1 min and the corrosion voltage was 0.4 V.

[0091] Roughening: The copper foil after electrochemical corrosion was rinsed with distilled water and then roughened; the copper ion concentration in the roughening solution was 25g / L, the sulfuric acid concentration was 100g / L, the roughening additives included guar gum and polyvinyl alcohol, the guar gum concentration in the roughening solution was 0.01g / L, and the polyvinyl alcohol concentration was 0.1g / L; the roughening current density was 25A / dm 2 , the coarsening time is 3s.

[0092] Example 4

[0093] A surface treatment method for rolled copper foil comprises the following steps:

[0094] Degreasing (alkaline washing): The degreasing step is the same as that of Example 1, and the copper foil substrate used is also the same.

[0095] Prepare an acidic pretreatment solution: dissolve sulfuric acid, cupric chloride and tartaric acid in water to prepare an acidic pretreatment solution, so that the concentration of sulfuric acid in the acidic pretreatment solution is 150 g / L, the concentration of cupric chloride is 30 g / L, the concentration of tartaric acid is 20 g / L, and the solution temperature is 35°C.

[0096] Electrochemical corrosion: A 2 mm thick copper plate was used as the cathode and a copper foil was used as the anode for electrochemical corrosion in an acidic pretreatment solution. The corrosion time was 1.5 min and the corrosion voltage was 0.6 V.

[0097] Roughening: The copper foil after electrochemical corrosion is rinsed with distilled water and then roughened; the copper ion concentration in the roughening solution is 20g / L, the sulfuric acid concentration is 100g / L, the roughening additives include carrageenan and sodium polydisulfide dipropane sulfonate, the concentration of carrageenan in the roughening solution is 0.1g / L, the concentration of sodium polydisulfide dipropane sulfonate is 0.01g / L, and the roughening current density is 30A / dm 2 , the coarsening time is 3s.

[0098] Comparative Example 1

[0099] A surface treatment method for rolled copper foil comprises the following steps:

[0100] Degreasing (alkaline washing): The degreasing step is the same as that of Example 1, and the copper foil substrate used is also the same.

[0101] Pickling: Soak the copper foil in 100g / L sulfuric acid solution for 4s;

[0102] Roughening: Rinse the copper foil with distilled water and then roughen it. The copper ion concentration in the roughening solution is 25g / L, the sulfuric acid concentration is 100g / L, there is no additive, and the roughening current density is 15A / dm 2 , the coarsening time is 3s.

[0103] In order to better illustrate the effect of electrochemical corrosion and roughening on the performance of copper foil in the surface treatment method of the present application, the copper foils after roughening treatment in Examples 1 to 4 and Comparative Example 1 were characterized and tested for performance, and the results are as follows:

[0104] Example 1: Figure 1 As shown, the surface texture of the copper foil has basically disappeared, and the surface flatness is relatively high; the roughness Rz of the copper foil is 0.84μm, and the peel strength is 0.82N / mm.

[0105] Example 2: Figure 2As shown, the surface texture of the copper foil disappears, the surface flatness is high, and the copper particles are dense; the roughness Rz of the copper foil is 0.93μm, and the peel strength is 0.91N / mm.

[0106] Example 3: Figure 3 As shown, the surface texture of the copper foil disappears, the surface flatness is high, the coating particle size and morphology are uniform, and the coating is dense; the roughness Rz of the tested copper foil is 0.77μm, and the peel strength is 0.97N / mm.

[0107] Example 4: Figure 4 As shown, the surface texture of the copper foil disappears, the surface flatness is high, the coating particle size and morphology are uniform, and the coating is dense; the roughness Rz of the copper foil is 0.89μm, and the peel strength is 0.90N / mm.

[0108] Comparative Example 1: Figure 5 As shown, the copper foil surface has obvious rolling lines, particles grow along the lines, and the flatness is poor; the roughness of the copper foil is 1.03μm, and the peel strength is 0.73N / mm.

[0109] The specific method of the peel strength test is as follows: the roughened copper foil and FR-4 epoxy resin are pressed into a copper clad laminate at a pressing temperature of 180°C, a pressure of 20 MPa, and a time of 60 minutes; and then the peel resistance test is performed using a Japanese Shimadzu AGS-X electronic universal testing machine.

[0110] In summary, by comparing the characterization test results of the copper foil after roughening treatment of Examples 1 to 4 and Comparative Example 1, it can be found that by replacing pickling with electrochemical corrosion and adding additives to the roughening solution, the rolling marks on the surface of the copper foil can be eliminated, the surface flatness can be improved, the surface roughness can be reduced, and the peel strength of the copper foil can be improved.

[0111] Furthermore, compared with the prior art, the present application is conducive to improving the peeling strength of the final copper foil product and reducing the surface roughness of the copper foil product.

[0112] Multiple exemplary embodiments of the present invention, however, without departing from the spirit and scope of the present invention, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention. Therefore, the scope of the present invention should be understood and identified as covering all these other variations or modifications.

Claims

1. A surface treatment method for rolled copper foil, characterized in that: The following steps are included in sequence: Degreasing: Degreasing liquid is used to degrease the rolled copper foil after rolling; Electrochemical corrosion: using the rolled copper foil as an anode and performing electrochemical corrosion in an acidic pretreatment solution; wherein the acidic pretreatment solution comprises sulfuric acid, cupric chloride, a complexing agent and water, and the complexing agent comprises one or more of disodium ethylenediaminetetraacetate, citric acid, oxalic acid, tartaric acid, sodium gluconate and lactic acid; Roughening: The rolled copper foil is roughened with a roughening liquid; the roughening liquid includes sulfuric acid, copper sulfate and additives, and the additives include one or more of sodium polydisulfide dipropane sulfonate, polyethylene glycol, polyvinyl alcohol, guar gum and carrageenan.

2. The surface treatment method according to claim 1, characterized in that: The concentration of sulfuric acid in the acidic pretreatment solution is 100-150 g / L, the concentration of cupric chloride is 20-30 g / L, and the concentration of the complexing agent is 5-20 g / L.

3. The surface treatment method according to claim 1, characterized in that: In the electrochemical corrosion step: The temperature of the acidic pretreatment solution is 30-40°C; The electrochemical corrosion time is 0.5 to 2 minutes; The electrochemical corrosion voltage is 0.3~0.6V.

4. The surface treatment method according to claim 1, characterized in that: The concentration of the additive in the roughening solution is 0.01-3 g / L.

5. The surface treatment method according to claim 4, characterized in that: The Cu 2+ The concentration is 20-30 g / L, and the concentration of sulfuric acid is 80-100 g / L.

6. The surface treatment method according to claim 5, characterized in that: In the roughening step: Current density is 15~30A / dm 2 ; The coarsening time is 2 to 4 seconds.

7. The surface treatment method according to claim 1, characterized in that: Before the electrochemical corrosion step, the method further comprises the following steps: Preparation of acidic pretreatment solution: dissolving sulfuric acid, cupric chloride and a complexing agent in water to obtain the acidic pretreatment solution.

8. The surface treatment method according to claim 1, characterized in that: Before the roughening treatment of the rolled copper foil with the roughening solution, the method further includes: washing the electrochemically corroded rolled copper foil with water to wash away the acidic pretreatment solution on the surface of the rolled copper foil.

9. The surface treatment method according to claim 1, characterized in that: In the degreasing step: the degreasing is chemical degreasing, the sodium hydroxide concentration in the degreasing solution is 30-40 g / L, the concentration of the surfactant is 1-2 g / L, the temperature of the degreasing solution is 50-60° C., and the degreasing time is 6-10 seconds.

10. The surface treatment method according to claim 1, characterized in that: The rolled copper foil has a thickness of 9 to 70 μm after rolling.

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