Preparation method of copper foil

Abstract

The preparation method of the copper foil provided by the invention comprises the following steps: providing a carrier layer; forming an oxidized metal layer on the carrier layer; forming a copper foil on the surface, deviating from the carrier layer, of the carrier layer, wherein the copper foil is connected with the carrier layer through an oxidized metal layer; and reducing the oxidized metal layer to separate the copper foil from the oxidized metal layer. According to the preparation method of the copper foil, the preparation cost of the copper foil can be reduced, and no harm is caused to people and the environment in the preparation process.

Description

Technical Field

[0001] The present application relates to the technical field of copper foil preparation, and in particular to a method for preparing copper foil. Background Art

[0002] As electronic products develop towards higher integration and miniaturization, copper foil plays an increasingly important role in electronic manufacturing.

[0003] Copper foil can be prepared by attaching a carrier. Electrolytic copper foil is used as the carrier foil, a peeling layer is formed on it, and then the target copper foil is deposited, and then the carrier foil and the target copper foil are effectively separated. The peeling layer material includes metal materials, alloys and organic matter to achieve efficient separation of the carrier foil and the target copper foil.

[0004] However, the peeling layer material has high cost or may cause harm to the human body and the environment. For example, the peeling layer material may include a metal material, which contains rare earth elements and has high cost. The peeling layer material may include an organic material, which generally includes organic compounds such as benzotriazole, benzimidazole, thiocyanuric acid and their derivatives. Most of these materials have certain toxicity and may cause certain harm to the human body and the environment. Summary of the invention

[0005] The embodiment of the present application provides a method for preparing copper foil, which can reduce the preparation cost of copper foil, and does not use materials that are harmful to humans and the environment during the preparation process.

[0006] The present invention provides a method for preparing a copper foil, comprising the following steps:

[0007] providing a carrier layer;

[0008] forming an oxide metal layer on the carrier layer;

[0009] forming a copper foil on a surface of the oxidized metal layer facing away from the carrier layer, wherein the copper foil is connected to the carrier layer through the oxidized metal layer;

[0010] The oxidized metal layer is subjected to reduction treatment, and the copper foil is separated from the oxidized metal layer.

[0011] Optionally, the metal oxide layer is configured as a copper oxide layer.

[0012] Optionally, forming a metal oxide layer on the carrier layer comprises:

[0013] providing an oxidizing electrolyte;

[0014] The carrier layer is used as a cathode, and electricity is applied to the carrier layer, so that the carrier layer forms the oxidized metal layer through the oxidizing electrolyte.

[0015] Optionally, the solvent of the oxidation electrolyte is water;

[0016] The solute of the oxidizing electrolyte includes sulfuric acid, copper sulfate pentahydrate, sodium hydroxide and an oxidant.

[0017] Optionally, the oxidant comprises hydrogen peroxide;

[0018] The solute of the oxidation electrolyte includes 50-150 g / L sulfuric acid, 15-25 g / L copper sulfate pentahydrate, 50-100 g / L sodium hydroxide and 5-15 g / L hydrogen peroxide.

[0019] Optionally, forming a copper foil on a surface of the oxidized metal layer facing away from the carrier layer comprises:

[0020] providing electrolyte;

[0021] The carrier layer and the oxidized metal layer are used as cathodes, and electricity is applied to at least one of the carrier layer and the oxidized metal layer, so that the oxidized metal layer forms the copper foil through the electrolyte.

[0022] Optionally, the solvent of the electrolyte is water;

[0023] The solutes of the electrolyte include sulfuric acid and copper sulfate pentahydrate.

[0024] Optionally, reducing the oxidized metal layer comprises:

[0025] placing the oxidized metal layer in a reduction chamber;

[0026] A reducing gas is introduced into the reducing chamber so that the reducing gas reduces the oxidized metal layer.

[0027] Optionally, after the oxidized metal layer is disposed in the reduction chamber, the method further comprises:

[0028] Inert gas is introduced into the reduction chamber to discharge oxygen in the reduction chamber.

[0029] Optionally, the carrier layer is configured as a thick copper layer, a copper-based alloy layer, a nickel layer, an aluminum layer and an iron layer.

[0030] The method for preparing copper foil provided by the present application is to treat the oxidized metal layer by reduction treatment, and to set the oxidized metal layer as a copper oxide layer. The copper oxide layer shrinks during the reduction process, and the oxidized metal layer is separated from the carrier layer. At the same time, the oxidized metal layer is separated from the copper foil to obtain the copper foil. The method for preparing copper foil has a low preparation cost, and the preparation process does not use materials that are harmful to the environment, and has the advantages of being environmentally friendly and green. The method has a simple process flow and high operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 is a flow chart of a method for preparing copper foil;

[0033] Figure 2 This is an electron microscope image of the first copper foil prepared;

[0034] Figure 3 This is an electron microscope image of the second copper foil prepared;

[0035] Figure 4 This is the electron microscope image of the third type of copper foil prepared;

[0036] Figure 5 This is the electron microscope image of the fourth type of copper foil prepared. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0038] The method for preparing the copper foil provided by the present invention comprises the following steps: first, providing a carrier layer, then forming an oxidized metal layer on the carrier layer, then forming a copper foil on the surface of the carrier layer away from the carrier layer, wherein the copper foil is connected to the carrier layer via the oxidized metal layer, and finally, the oxidized metal layer is reduced to separate the copper foil from the oxidized metal layer.

[0039] The method for preparing copper foil provided by the present application is to treat the oxidized metal layer by reduction treatment, and to set the oxidized metal layer as a copper oxide layer. The copper oxide layer shrinks during the reduction process, and the oxidized metal layer is separated from the carrier layer. At the same time, the oxidized metal layer is separated from the copper foil to obtain the copper foil. The method for preparing copper foil has a low preparation cost, and the preparation process does not use materials that are harmful to the environment, and has the advantages of being environmentally friendly and green. The method has a simple process flow and high operability.

[0040] Reference Figure 1 As shown, the preparation method of copper foil is as follows:

[0041] Step S110: providing a carrier layer.

[0042] First, a carrier layer is provided, and the carrier layer is configured as a thick copper layer, a copper-based alloy layer, a nickel layer, an aluminum layer, and an iron layer. The material of the carrier layer is selected according to different application scenarios and requirements.

[0043] In some embodiments, the carrier layer is configured as a copper foil, which needs to have good electrical conductivity to facilitate the formation of an oxidized metal layer.

[0044] In some embodiments, the carrier layer is configured as a copper-based alloy foil. The copper-based alloy foil has specific properties, such as higher hardness or corrosion resistance. By selecting the copper-based alloy foil as the carrier layer, these properties can be improved to meet specific requirements.

[0045] Furthermore, the carrier layer is set to be brass, bronze, nickel silver or phosphor bronze. The selection is made by comprehensively considering the conductivity, adhesion, corrosion resistance and wear resistance of different materials and cost-effectiveness.

[0046] Step S120: forming an oxide metal layer on the carrier layer.

[0047] Then, an oxidized metal layer is formed on the provided carrier layer by an oxidizing electrolyte. The process of forming the oxidized metal layer can be by providing an oxidizing electrolyte, using the carrier layer as a cathode, and applying electricity to the carrier layer to cause a chemical reaction. That is, by injecting an oxidizing electrolyte containing metal ions into an electrolytic cell, and placing the carrier layer as a cathode therein. Subsequently, an electric current passes through the electrolytic cell, and the metal ions obtain electrons on the surface of the cathode (i.e., the carrier layer), and a reduction reaction occurs. The metal ions combine with the oxidant in the electrolyte to form a relatively dense oxidized metal layer on the surface of the carrier layer.

[0048] In some embodiments, the metal oxide layer is configured as a nickel oxide layer. The nickel oxide layer is formed by an oxidizing electrolyte. The bonding force between the nickel oxide layer and the copper foil is moderate, which facilitates the peeling of the copper foil and the carrier layer by chemical or physical methods in subsequent processes.

[0049] In other embodiments, the metal oxide layer is configured as a copper oxide layer, which can prevent other metal ions in the electrolyte from being deposited on the copper foil during the electrolysis process, thereby affecting the purity of the copper foil finally prepared.

[0050] In some embodiments, the solvent of the oxidizing electrolyte is water, and the solute of the oxidizing electrolyte includes sulfuric acid, copper sulfate pentahydrate, sodium hydroxide and an oxidant. In other words, water is the solvent of the electrolyte, responsible for dissolving the solute to form a solution that can conduct electricity. During the electrolysis process, the solute of the oxidizing electrolyte participates in the electrolysis reaction. For example, sulfuric acid and sodium hydroxide can adjust the pH value of the oxidizing electrolyte, thereby affecting the conditions and efficiency of the electrolysis reaction. Copper sulfate pentahydrate provides copper ions for generating copper or copper oxide. The oxidant can participate in the oxidation reaction to generate a copper oxide layer.

[0051] In some embodiments, the oxidant may be hydrogen peroxide. The oxidant may be sodium hypochlorite. The oxidant may be potassium persulfate. Different oxidants may affect the speed, uniformity and adhesion of the oxidation reaction of the copper oxide layer.

[0052] In some embodiments, the solute of the oxidizing electrolyte includes 50-150 g / L sulfuric acid, 15-25 g / L copper sulfate pentahydrate, 50-100 g / L sodium hydroxide and 5-15 g / L hydrogen peroxide. This is set to obtain an oxidized metal layer with different physical properties such as thickness and uniformity. For example, 1 L of water is used as a solvent, 50 g of sulfuric acid, 15 g of copper sulfate pentahydrate, 50 g of sodium hydroxide and 5 g of hydrogen peroxide are added, and stirred evenly to prepare an oxidizing electrolyte.

[0053] In some embodiments, the solute of the oxidation electrolyte includes 10-100 g / L sulfuric acid, 1-5 mg / L hydrochloric acid, 2-15 g / L copper sulfate pentahydrate, 20-70 g / L sodium hydroxide and 1-5 g / L hydrogen peroxide. This arrangement is used to obtain an oxide metal layer with different physical properties such as thickness and uniformity.

[0054] In some embodiments, the temperature of the oxidation electrolyte is 15° C. to 30° C. For example, the temperature of the oxidation electrolyte is 15° C., 20° C., 25° C., 30° C., or a range consisting of any two thereof. The temperature of the oxidation electrolyte may affect the chemical reaction rate, electrolysis efficiency, the quality of the oxidized metal layer, and the temperature of the oxidation electrolyte is set based on a variety of factors.

[0055] In other embodiments, the temperature of the oxidation electrolyte is 25° C. to 55° C. For example, the temperature of the oxidation electrolyte is 25° C., 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., or a range consisting of any two of them. The temperature of the oxidation electrolyte may affect the chemical reaction rate, electrolysis efficiency, the quality of the oxidized metal layer, and the temperature of the oxidation electrolyte is set based on a variety of factors.

[0056] In some embodiments, the electroplating reaction adopts a two-electrode system, the cathode voltage is 2-5V, and the current density is 0.5-5A / dm 2The electroplating time is 30-50 seconds. This setting is used to form an oxide metal layer that meets actual needs.

[0057] In other embodiments, the electroplating reaction adopts a two-electrode system, the cathode voltage is 2-5V, and the current density is 0.5-5A / dm 2 , the electroplating time is 30s~60min. Similarly, in this way, an oxide metal layer that meets actual needs is formed.

[0058] In some embodiments, the oxidized metal layer formed after electroplating needs to be cleaned and dried. The cleaning process can remove the plating solution, impurities and other contaminants remaining on the surface of the oxidized metal layer after electroplating, avoiding adverse effects on subsequent processes or product performance. The oxidized metal layer after cleaning needs to be dried. The surface of the oxidized metal layer after drying is relatively clean, which helps to improve the adhesion of the subsequent plating layer.

[0059] Furthermore, the oxidized metal layer formed after electroplating needs to be cleaned with anhydrous ethanol and deionized water in sequence and then dried, which can improve the cleaning effect, avoid secondary pollution, and promote the drying process.

[0060] Exemplarily, anhydrous ethanol has good solubility and volatility, and can dissolve and take away organic matter and other impurities on the surface of the oxidized metal layer. Anhydrous ethanol can evaporate quickly during the cleaning process, can take away the moisture on the surface, and accelerate the drying process, which can save time and reduce energy consumption. After cleaning with anhydrous ethanol, deionized water is used for cleaning to ensure the cleanliness of the surface of the oxidized metal layer. In addition, deionized water removes various dissolved ions to avoid the risk of these ions being re-deposited on the surface of the oxidized metal layer during the cleaning process, thereby causing the risk of secondary pollution.

[0061] Step S130: forming a copper foil on the surface of the oxidized metal layer facing away from the carrier layer, and the copper foil is connected to the carrier layer through the oxidized metal layer.

[0062] As mentioned above, the oxidized metal layer is formed on the carrier layer by electroplating, and then the copper foil to be prepared needs to be electroplated on the oxidized metal layer. An electrolyte is provided for the process of copper foil formation, and the carrier layer and the oxidized metal layer are used as cathodes, and at least one of the carrier layer and the oxidized metal layer is energized. That is, an electrolyte containing copper ions is first prepared, and the carrier layer and the oxidized metal layer are used as cathodes. Subsequently, an external power source is used to energize this cathode (the carrier layer or the oxidized metal layer thereon), so that the copper ions in the electrolyte obtain electrons on the cathode surface and undergo a reduction reaction. The copper ions are continuously reduced and deposited on the oxidized metal layer, and finally a dense layer of copper foil is formed. This copper foil is the copper foil to be prepared.

[0063] In some embodiments, the solvent of the electrolyte is water. The solute of the electrolyte includes sulfuric acid and copper sulfate pentahydrate. In other words, water is the solvent of the electrolyte and is responsible for dissolving the solute to form a solution that can conduct electricity. During the electrolysis process, the solute of the electrolyte participates in the electrolysis reaction.

[0064] For example, sulfuric acid makes the electrolyte acidic, and copper ions are more easily dissociated from copper sulfate pentahydrate, which promotes the electrolysis process. Copper sulfate pentahydrate is the main source of copper ions in the electrolyte. During the electrolysis process, copper sulfate pentahydrate will dissociate copper ions, which migrate to the cathode under the action of the electric field and are reduced to copper atoms on the cathode surface, and gradually deposit to form copper foil.

[0065] In some embodiments, the solute of the electrolyte includes 50-150 g / L sulfuric acid and 15-25 g / L copper sulfate pentahydrate. This arrangement is used to obtain copper foils with different thicknesses, uniformity, and other characteristics on the oxidized metal layer through electroplating reactions. For example, 1 L of water is used as a solvent, 50 g of sulfuric acid and 15 g of copper sulfate pentahydrate are added, and the mixture is stirred evenly to prepare an electrolyte.

[0066] In other embodiments, the solute of the electrolyte includes 5-20 g / L sulfuric acid and 3-15 g / L copper sulfate pentahydrate. In this way, copper foils with different physical properties such as thickness and uniformity can be obtained on the oxidized metal layer through electroplating reaction.

[0067] In some embodiments, the cathode voltage of the electroplating process for forming the copper foil on the surface of the oxidized metal layer is 0.1-10V, and the current density is 20-40A / dm 2 , the electroplating time is 1~20s. This setting can form a copper foil that meets actual needs.

[0068] In other embodiments, the cathode voltage of the electroplating process for forming the copper foil on the surface of the oxidized metal layer is 0.1-10V, and the current density is 20-40A / dm 2 , the electroplating time is 30~3600s. Similarly, in this way, a copper foil that meets actual needs is formed.

[0069] In some embodiments, the temperature of the electrolyte is 25° C. to 55° C. For example, the temperature of the electrolyte is 25° C., 30° C., 35° C., 40° C., 45° C., 50° C., 55° C., or a range consisting of any two of them. The temperature of the electrolyte may affect the chemical reaction rate, electrolysis efficiency, quality of the copper foil, and other aspects, and the temperature of the electrolyte is set based on a variety of factors.

[0070] Step S140 , reducing the oxidized metal layer, and separating the copper foil from the oxidized metal layer.

[0071] Before the reduction treatment, the oxidized metal layer (with copper foil) formed by the carrier layer needs to be placed in the reduction chamber to achieve the reduction reaction. Therefore, an inert gas needs to be introduced into the reduction chamber to exhaust the oxygen in the reduction chamber. By introducing an inert gas into the reduction chamber, the oxygen concentration in the reduction chamber can be reduced, thereby preventing the oxidized metal layer from generating impurities or inconsistent with the expected reaction during the subsequent treatment process.

[0072] Furthermore, the inert gas is set to argon. It is easy to understand that argon is a colorless, odorless, non-toxic inert gas with relatively stable chemical properties and is not easy to react with other substances. Therefore, using argon to pass into the reduction chamber and exhausting the oxygen in the reduction chamber can prevent the subsequent treatment process of the oxidized metal layer from reacting with argon. In addition, the cost of argon is relatively low and it is easy to obtain and store. In this way, using argon as an inert gas can reduce the preparation cost.

[0073] In some embodiments, an oxidized metal layer (attached to a carrier layer) with copper foil attached thereto is placed in a reduction chamber. In this way, a reducing gas is introduced into the reduction chamber so that the reducing gas reduces the oxidized metal layer. In other words, a reducing gas, such as hydrogen or carbon monoxide, is introduced into the reduction chamber, and these reducing gases react chemically with the oxidized metal layer. During the reduction process of the oxidized metal layer, the volume of the oxidized metal layer shrinks, the oxidized metal layer separates from the carrier layer, and at the same time, the oxidized metal layer separates from the copper foil. In this way, the carrier layer and the copper foil are separated spontaneously, thereby obtaining a copper foil.

[0074] With such a configuration, the volume shrinkage characteristics of the oxidized metal layer during reduction can be utilized to achieve efficient and spontaneous separation between the carrier layer and the copper foil. The preparation method of the embodiment of the present application uses an oxidized metal layer to replace the stripping layer of the traditional method to prepare the copper foil. This avoids the use of stripping layer materials that are expensive or may cause harm to the human body and the environment. This method simplifies the preparation operation steps, reduces the production cost of the preparation, avoids the use of harmful chemicals in the preparation process, and meets environmental protection requirements.

[0075] It is easy to understand that by controlling the flow rate, speed, pressure and other parameters of the reducing gas, the shrinking speed can be adjusted, thereby achieving the adjustment of the reduction rate of the oxidized metal layer. This affects the rate and degree of volume shrinkage of the oxidized metal layer, thereby being able to control the stress distribution and separation process between the carrier layer and the copper foil. This helps to ensure the integrity and surface quality of the copper foil, while reducing uncertainty and potential damage during the separation process.

[0076] In some embodiments, the reducing gas is hydrogen. Hydrogen is a strong reducing agent that can reduce a variety of metal oxides. The cost of hydrogen is relatively low and it is easy to obtain. During the reduction process, water is generated at the same time, and the generated product is environmentally friendly.

[0077] Exemplarily, the oxidized metal layer is placed in a reduction chamber and the chamber is sealed. Then, hydrogen is introduced into the reduction chamber and adjusted to the set temperature and pressure conditions. Under the action of hydrogen, the oxidized metal layer begins to be reduced and gradually converted into metal. At the same time, it is necessary to regularly monitor parameters such as gas composition and temperature during the reduction process to ensure the stability and consistency of the reduction process.

[0078] In some embodiments, the reducing gas is set to carbon monoxide. Carbon monoxide can be prepared in a variety of ways, including extraction from raw materials such as natural gas, coal or biomass. In addition, the storage and transportation of carbon monoxide are relatively simple, reducing the overall processing cost. For example, in the reduction chamber, carbon monoxide reacts chemically with the oxidized metal layer to reduce the metal oxide to pure metal and generate carbon dioxide. This reduction process usually has a high reaction rate and selectivity.

[0079] In some embodiments, the reducing gas is heated and the temperature after heating is set to 300°C to 400°C. Heating the reducing gas can increase the reduction reaction rate, optimize the reduction efficiency and enhance the process stability. For example, the temperature of the reducing gas is 300°C, 325°C, 350°C, 375°C, 400°C or a range consisting of any two of them. The temperature of the reducing gas may affect the reduction reaction rate, reduction efficiency, quality of the copper foil and other aspects. The temperature of the reducing gas is set based on a variety of factors.

[0080] In other embodiments, the temperature of the reducing gas after heating is set to 400°C to 500°C. Heating the reducing gas can increase the reduction reaction rate, optimize the reduction efficiency and enhance the process stability. For example, the temperature of the reducing gas is 400°C, 425°C, 450°C, 475°C, 500°C or a range consisting of any two of them. The temperature of the reducing gas may affect the reduction reaction rate, reduction efficiency, quality of the copper foil and other aspects, and the temperature of the reducing gas is set by combining multiple factors.

[0081] In some embodiments, the time for reducing the oxidized metal layer by the reducing gas is set to 5 to 30 minutes. The reduction time setting can shorten the cycle of the reduction process, thereby improving the efficiency of copper foil preparation. This helps to reduce the cost of copper foil preparation and meet the market demand for copper foil. For example, the time of the reduction reaction is 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, or a range consisting of any two of them.

[0082] In other embodiments, the time for reducing the oxidized metal layer by the reducing gas is set to 30 to 120 minutes. The reduction time setting can shorten the cycle of the reduction process, thereby improving the efficiency of copper foil preparation. This helps to reduce the cost of copper foil preparation and meet the market demand for copper foil. For example, the time of the reduction reaction is 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes, or a range consisting of any two of them.

[0083] Finally, after the above reduction reaction, the carrier with the copper foil and the oxidized metal layer is cooled to room temperature to finally obtain an ultra-thin copper foil. During the reduction process, the volume of the oxidized metal layer shrinks, and stress is generated between the copper foil and the carrier layer. The cooling process helps to release these stresses, reduce the warping or deformation of the copper foil, and thus improve the flatness of the copper foil. The copper foil at room temperature is convenient for subsequent processing.

[0084] In some embodiments, the final cooling time is 30 min to 180 min. The cooling time can shorten the cooling process cycle, thereby improving the efficiency of copper foil preparation. For example, the reduction reaction time is 30 min, 60 min, 90 min, 120 min, 150 min, 180 min, or any two thereof.

[0085] In some embodiments, the prepared copper foil is set as an ultra-thin copper foil. The ultra-thin copper foil can be used for highly integrated and miniaturized electronic products.

[0086] In some embodiments, the copper foil may be 2 to 6 micrometers. For example, the copper foil may be 2 micrometers, 3 micrometers, 4 micrometers, 5 micrometers, 6 micrometers, or any two thereof.

[0087] In other embodiments, the prepared copper foil may be an ultra-thin copper foil with a thickness of 250 nanometers.

[0088] The preparation method of the copper foil of the present invention is described in more detail below through specific examples.

[0089] The raw materials used in the embodiments and comparative examples can be purchased from common commercial sources, and no additional processing was performed unless otherwise specified.

[0090] Example 1

[0091] This embodiment provides a method for preparing a copper foil, comprising the following steps:

[0092] First, the carrier layer is provided as a copper foil.

[0093] Then, water was used as solvent, and the solutes included 50 g / L sulfuric acid, 5 mg / L hydrochloric acid, 5 g / L copper sulfate pentahydrate, 50 g / L sodium hydroxide, and 5 g / L hydrogen peroxide to prepare an oxidizing electrolyte. The temperature of the oxidizing electrolyte was set to 25°C. The copper foil was used as the cathode, and power was applied to the copper foil. The electroplating reaction adopted a two-electrode system, the cathode voltage was 2V, and the current density was 5A / dm 2 The electroplating time is 40s. A copper oxide layer is formed on the copper foil by electroplating.

[0094] Subsequently, the surface of the copper oxide layer is cleaned and dried.

[0095] Next, an electrolyte solution was prepared using water as a solvent and 80 g / L sulfuric acid and 20 g / L copper sulfate pentahydrate as the solute. In this step, the cathode voltage of the electroplating was 5 V and the current density was 20 A / dm 2 The electroplating time is 10s. With the copper foil and the copper oxide layer as cathodes, electricity is applied to the copper foil and the copper oxide layer, and the final copper foil required is formed on the copper oxide layer by electroplating.

[0096] Finally, argon gas is introduced into the reduction chamber to exhaust the oxygen in the reduction chamber. The copper oxide layer (including the copper foil on both surfaces of the copper oxide layer) is placed in the reduction chamber. Hydrogen gas is introduced into the reduction chamber and heated to 300°C. The time for hydrogen to reduce the copper oxide layer is set to 5 minutes, so that the volume of the copper oxide layer will shrink during the reduction process, so that the interface between the carrier layer and the prepared copper foil will spontaneously separate. After the above reduction reaction, it is taken out and cooled to room temperature to finally obtain copper foil.

[0097] Combination Figure 2 This indicates that when hydrogen is introduced into the reduction chamber, the hydrogen reacts with the copper oxide layer to undergo a reduction reaction. During this process, the copper oxide layer shrinks in volume during the reduction process, causing the interface between the carrier layer and the prepared copper foil to spontaneously separate, thereby obtaining a copper foil with a thickness of about 2 μm.

[0098] Example 2 This example is basically the same as Example 1, except that the carrier layer is set as a nickel layer; other conditions remain unchanged.

[0099] Example 3 This example is basically the same as Example 1, except that: the oxidizing electrolyte uses water as solvent, the solute includes 100 g / L sulfuric acid, 20 g / L copper sulfate pentahydrate, 75 g / L sodium hydroxide and 10 g / L hydrogen peroxide to prepare; other conditions remain unchanged.

[0100] Example 4 This example is basically the same as Example 1, except that the electroplating time for forming the copper oxide layer is 30s~10min; other conditions remain unchanged.

[0101] Referring to the process of Example 1, the copper foil of the above example was prepared, and the thickness of the prepared copper foil was tested. Figure 3 , Figure 4 and Figure 5 As shown, the measured data of the thickness of the copper foil show that the thickness of the copper foil prepared in Example 2 is about 400 nm, the thickness of the copper foil prepared in Example 3 is about 250 nm, and the thickness of the copper foil prepared in Example 4 is about 9 μm. The thickness of the prepared copper foil is affected by the plating time of the carrier layer, the oxidizing electrolyte, and the copper oxide layer.

[0102] It should be noted that the phrases "one embodiment", "an embodiment", "an exemplary embodiment", "some embodiments", etc. mentioned in the specification indicate that the described embodiments may include certain features, structures or characteristics, but not every embodiment may include the certain features, structures or characteristics. In addition, such phrases do not necessarily refer to the same embodiment. In addition, when describing certain features, structures or characteristics in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such features, structures or characteristics in conjunction with other embodiments, whether explicitly or not explicitly described.

[0103] In general, terms should be understood, at least in part, by the context in which they are used. For example, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in a singular sense, or may be used to describe a combination of features, structures, or characteristics in a plural sense, depending, at least in part, on the context. Similarly, terms such as "a," "an," or "the" may also be understood to convey singular usage or to convey plural usage, depending, at least in part, on the context.

[0104] It should be easily understood that the terms “on,” “above,” and “over” in this application should be interpreted in the broadest manner, so that “on” means not only “directly on something,” but also includes the meaning of “on something” with intervening features or layers therebetween, and “above” or “over” includes not only the meaning of “above something” or “over,” but also may include the meaning of “above something” or “over” with no intervening features or layers therebetween (i.e., directly on something).

[0105] In addition, spatially relative terms, such as "below," "below," "beneath," "above," "above," etc., may be used herein for ease of description to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. The device may have other orientations (rotated 90° or at other orientations), and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a copper foil, characterized in that: include: providing a carrier layer; forming an oxide metal layer on the carrier layer; forming a copper foil on a surface of the oxidized metal layer facing away from the carrier layer, wherein the copper foil is connected to the carrier layer through the oxidized metal layer; The oxidized metal layer is subjected to reduction treatment, and the copper foil is separated from the oxidized metal layer.

2. The method for preparing copper foil according to claim 1, characterized in that: The metal oxide layer is configured as a copper oxide layer.

3. The method for preparing copper foil according to claim 2, characterized in that: The step of forming an oxidized metal layer on the carrier layer comprises: providing an oxidizing electrolyte; The carrier layer is used as a cathode, and electricity is applied to the carrier layer, so that the carrier layer forms the oxidized metal layer through the oxidizing electrolyte.

4. The method for preparing copper foil according to claim 3, characterized in that: The solvent of the oxidation electrolyte is water; The solute of the oxidizing electrolyte includes sulfuric acid, copper sulfate pentahydrate, sodium hydroxide and an oxidant.

5. The method for preparing copper foil according to claim 4, characterized in that: The oxidant includes hydrogen peroxide; The solute of the oxidizing electrolyte includes 50-150 g / L of sulfuric acid, 15-25 g / L of copper sulfate pentahydrate, 50-100 g / L of sodium hydroxide and 5-15 g / L of hydrogen peroxide.

6. The method for preparing copper foil according to claim 1, characterized in that: Forming a copper foil on a surface of the oxidized metal layer facing away from the carrier layer comprises: providing electrolyte; The carrier layer and the oxidized metal layer are used as cathodes, and electricity is applied to at least one of the carrier layer and the oxidized metal layer, so that the oxidized metal layer forms the copper foil through the electrolyte.

7. The method for preparing copper foil according to claim 6, characterized in that: The solvent of the electrolyte is water; The solutes of the electrolyte include sulfuric acid and copper sulfate pentahydrate.

8. The method for preparing the copper foil according to any one of claims 1 to 7, characterized in that: The reduction treatment of the oxidized metal layer comprises: placing the oxidized metal layer in a reduction chamber; A reducing gas is introduced into the reducing chamber so that the reducing gas reduces the oxidized metal layer.

9. The method for preparing copper foil according to claim 8, characterized in that: After the oxidized metal layer is disposed in the reduction chamber, the method further comprises: Inert gas is introduced into the reduction chamber to discharge oxygen in the reduction chamber.

10. The method for preparing the copper foil according to any one of claims 1 to 7, characterized in that: The carrier layer is configured as a thick copper layer, a copper-based alloy layer, a nickel layer, an aluminum layer and an iron layer.

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