Preparation method for constructing copper nodule on copper foil surface

Abstract

The present application provides a preparation method for constructing copper nodules on the surface of copper foil. The method includes the following steps: providing a carrier layer, the carrier layer includes copper foil, and a binder disposed on the surface of the copper foil; providing a copper salt solution and a reducing solution; mixing the copper salt solution and the reducing solution to form a mixed solution, and forming elemental copper; immersing the carrier layer in the mixed solution, and the elemental copper is bonded to the carrier layer through the binder to form a copper nodule layer. The preparation method provided in the present application does not require an electric current-driven electroplating process, which can reduce production costs and energy consumption during the preparation process.

Description

Technical Field

[0001] The present application relates to the field of copper foil preparation methods, and in particular to a preparation method for constructing copper nodules on the surface of copper foil. Background Art

[0002] Copper foil is a conductor material for printed circuit boards, and its surface roughness has a great influence on the transmission loss of high-speed and high-frequency signals.

[0003] The signal transmission frequency of copper foil is relatively high, and the "skin effect" of copper foil will be more obvious. Under the condition of ensuring that the copper foil has a certain degree of peeling, low-profile copper foil (copper foil with lower surface roughness) is used to reduce signal transmission loss. Therefore, copper nodules are usually constructed on the surface of copper foil by electroplating to change its roughness.

[0004] The electroplating method requires a large current to be passed through the electrolytic cell, and the copper nodules are constructed on the surface of the copper foil by consuming electrical energy. However, the electroplating method consumes a lot of energy. Summary of the invention

[0005] The embodiment of the present application provides a method for preparing copper nodules on the surface of copper foil, so as to solve the problem of high energy consumption in the electroplating method.

[0006] The method for preparing copper nodules on the surface of copper foil provided in the embodiment of the present application comprises:

[0007] Providing a carrier layer, the carrier layer comprising a copper foil and an adhesive disposed on a surface of the copper foil;

[0008] providing a copper salt solution and a reducing solution;

[0009] The copper salt solution and the reducing solution are mixed to form a mixed solution, and elemental copper is formed;

[0010] The carrier layer is immersed in the mixed solution, and the single copper is bonded to the carrier layer through a binder to form a copper nodule layer.

[0011] In some embodiments, the molar concentration of copper ions in the copper salt solution is set to 0.01-5 mol / L.

[0012] In some embodiments, the copper salt solution comprises an organic salt solution, and the organic salt solution comprises copper formate or copper acetate;

[0013] Alternatively, the copper salt solution includes an inorganic salt solution, and the inorganic salt solution includes copper sulfate or copper nitrate.

[0014] In some embodiments, the reducing solution is one of hydrazine, hydrazine sulfate, dimethylamine borane, and sodium hydride.

[0015] In some embodiments, the binder includes at least one of epoxy, polyamide, and polyisobutylene.

[0016] In some embodiments, after the copper salt solution and the reducing solution are mixed to form a mixed solution,

[0017] adding a surfactant to the mixed solution;

[0018] Wherein, the surfactant includes at least one of polyvinyl pyrrolidone, polyvinyl alcohol and methyl cellulose.

[0019] In some embodiments, after mixing the copper salt solution and the reducing solution to form a mixed solution, the method further comprises:

[0020] The pH value of the mixed solution is adjusted, and the mixed solution is alkaline.

[0021] In some embodiments, after mixing the copper salt solution and the reducing solution to form a mixed solution, the method includes:

[0022] The mixed solution is ultrasonically treated to suspend and disperse the elemental copper.

[0023] In some embodiments, the time for immersing the carrier layer in the mixed solution is set to 30 min to 20 h;

[0024] And / or, the temperature of the mixed solution is set to 0-20°C.

[0025] In some embodiments, after the copper nodule layer is formed on the surface of the carrier layer,

[0026] Cleaning the copper nodule layer and the carrier layer;

[0027] The copper nodule layer and the carrier layer are dried.

[0028] The preparation method of copper nodules constructed on the surface of copper foil provided in the embodiment of the present application comprises a mixed solution including a copper salt solution and a reducing solution, and the mixed solution undergoes a reduction reaction to form elemental copper. The copper foil is coated with a carrier layer formed by a binder, and the carrier layer is immersed in the mixed solution. The elemental copper in the mixed solution is bonded to the outer surface of the carrier layer by the binder to become a nucleation site, and the elemental copper assembles and agglomerates at the nucleation site to form a copper nodule layer on the outer surface of the carrier layer. This method prepares a copper nodule layer on the outer surface of the carrier layer through chemical reaction and bonding with a binder. This method does not require an electric current-driven electroplating process, which can reduce production costs and energy consumption during the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 A flow chart of a method for preparing copper nodules on the surface of copper foil;

[0031] Figure 2 This is the microstructure picture of smooth copper foil;

[0032] Figure 3 This is the microstructure image of the first low-profile copper foil with copper nodules;

[0033] Figure 4 This is the microstructure picture of the second type of low-profile copper foil with copper nodules;

[0034] Figure 5 This is the microstructure picture of the third type of low-profile copper foil with copper nodules;

[0035] Figure 6 This is the microstructure picture of the fourth type of low-profile copper foil with copper nodules;

[0036] Figure 7 This is the microstructure picture of the fifth type of low-profile copper foil with copper nodules. DETAILED DESCRIPTION

[0037] In the related art, copper foil is adhered to the substrate when manufacturing the circuit board, and the signal is transmitted through the copper foil. The signal transmission frequency of the copper foil is relatively high. For example, the signal transmission frequency can reach 10GHz. When the alternating current is transmitted on the copper foil, the current tends to concentrate on the surface of the copper foil. As the frequency increases, the distribution of the current on the copper foil will be closer to its surface. In other words, the "skin effect" of the copper foil will be more obvious. The copper foil needs to have a certain peel strength to ensure that the copper foil does not fall off the substrate. Copper foil with lower surface roughness helps to reduce the loss during high-frequency signal transmission. Therefore, copper nodules are usually constructed on the surface of the copper foil by electroplating to change its roughness.

[0038] The electroplating method requires a large current to be passed through the electrolytic cell, and the copper nodules are constructed on the surface of the copper foil by consuming electrical energy. However, the energy consumption during the electroplating process is high.

[0039] In view of this, the preparation method of copper nodules constructed on the surface of copper foil provided in the embodiment of the present application is a mixed solution including a copper salt solution and a reducing solution, and the mixed solution undergoes a reduction reaction to form elemental copper. The copper foil is coated with a carrier layer formed by a binder, and the carrier layer is immersed in the mixed solution. The elemental copper in the mixed solution is bonded to the outer surface of the carrier layer through the binder to become a nucleation site, and the elemental copper assembles and agglomerates at the nucleation site to form a copper nodule layer on the outer surface of the carrier layer. This method prepares a copper nodule layer on the outer surface of the carrier layer through chemical reaction and bonding with a binder. This method does not require an electric current-driven electroplating process, can reduce production costs, and can also reduce energy consumption in the preparation process. In addition, this method can simplify the process flow, reduce equipment requirements and operational complexity.

[0040] 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.

[0041] The embodiment of the present application provides a method for preparing copper nodules constructed on the surface of copper foil, which method includes the following steps: first, providing a carrier layer, the carrier layer including copper foil and a binder arranged on the surface of the copper foil; then, providing a copper salt solution and a reducing solution; then, mixing the copper salt solution and the reducing solution to form a mixed solution, and forming elemental copper; finally, immersing the carrier layer in the mixed solution, and the elemental copper is bonded to the carrier layer by the binder to form a copper nodule layer.

[0042] In this method, a mixed solution includes a copper salt solution and a reducing solution, and the mixed solution undergoes a reduction reaction to form elemental copper. A copper foil coated with an adhesive is immersed in the mixed solution. The elemental copper in the mixed solution is bonded to the outer surface of the carrier layer through the adhesive to become a nucleation site, and the elemental copper assembles and agglomerates at the nucleation site to form a copper nodule layer on the outer surface of the carrier layer. This method prepares a copper nodule layer on the outer surface of the carrier layer through chemical reactions and the bonding of an adhesive. This method does not require a current-driven process in electroplating, reduces energy consumption in the preparation process, and reduces production costs. In addition, this method can simplify the process flow, reduce equipment requirements and operational complexity.

[0043] Reference Figure 1 As shown, the preparation method of copper nodule ball constructed on the surface of copper foil is as follows:

[0044] Step S110: providing a carrier layer, wherein the carrier layer includes a copper foil and an adhesive disposed on a surface of the copper foil.

[0045] First, the adhesive is coated on the surface of the copper foil to form a carrier layer. When the copper atoms come into contact with the surface of the metal copper foil, the chemical bonds in the adhesive react with the copper atoms to form stable attachment points. These attachment points will become the nucleation sites of the copper nodules.

[0046] In some embodiments, the binder includes at least one of epoxy resin, polyamide and polyisobutylene. By selecting a suitable binder, the adhesion of copper atoms on the surface of the copper foil can be improved.

[0047] Exemplarily, epoxy resin has excellent adhesion, chemical stability and mechanical strength. On the surface of copper foil, epoxy resin can form a strong chemical bond, react with copper atoms, and enhance adhesion. Polyamide has good heat resistance, wear resistance and chemical stability. The molecular structure of polyamide contains amide bonds, which can form hydrogen bonds or other types of chemical bonds with the copper surface, providing good adhesion properties. Polyisobutylene has excellent flexibility and air tightness. Due to its flexibility, polyisobutylene can form a soft adhesion layer on the surface of copper foil, which helps to absorb stress and improve the durability of the adhesion layer.

[0048] Furthermore, the concentration of the binder or the mixed binder is set to 4%-6%. A higher binder concentration may cause the solution to be more viscous and difficult to apply evenly. A lower binder concentration may result in insufficient adhesion of copper atoms.

[0049] Step S120: providing a copper salt solution and a reducing solution.

[0050] Next, it is necessary to provide a copper salt solution and a reducing solution for forming copper nodules on the carrier layer.

[0051] In some embodiments, the copper salt solution includes an organic salt solution, and the organic salt solution includes copper formate or copper acetate. These compounds can be dissociated in water or other solvents to provide copper ions for forming the copper nodule layer.

[0052] In other embodiments, the copper salt solution includes an inorganic salt solution, and the inorganic salt solution includes copper sulfate or copper nitrate. These compounds can dissociate in a solvent to provide copper ions for forming the copper nodule layer. For example, copper sulfate or copper nitrate has a high solubility in water, is easy to obtain, and can provide a high concentration of copper ions.

[0053] The molar concentration of copper ions in the copper salt solution is set to 0.01-5 mol / L. For example, 0.01 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L or any two of them. The concentration range of the copper salt solution is selected comprehensively according to factors such as the reaction rate, the stability of the solution and the economy.

[0054] Further, the copper salt solution of the mixed solution can be prepared by a solvent and a solute in a certain ratio. The solvent can be selected from ethanol or water. By selecting a suitable solvent and a solute, and controlling their ratio, a stable copper salt solution can be prepared. The solute includes an organic salt or an inorganic salt. For example, about 32g of copper sulfate is dissolved in 1L of ethanol, and stirred to form a copper salt solution having a molar concentration of 0.2mol / L of copper ions.

[0055] In addition, the reducing solution of the mixed solution can be set as a water-soluble compound. That is, the reducing solution is formed by dissolving a water-soluble reducing agent in water. The use of a water-soluble compound can ensure that the reducing agent is evenly distributed in the reducing solution, promote the reduction to form uniform copper atoms, and finally form a uniform copper nodule layer.

[0056] In some embodiments, the reducing solution is set to be one of hydrazine, hydrazine sulfate, dimethylamine borane boron, and sodium hydride. According to specific application requirements and reaction conditions, the most suitable reducing solution can be selected to form a low-profile copper foil.

[0057] Further, the concentration range of the reducing solution is 1-20 g / L, such as 1 g / L, 2 g / L, 4 g / L, 6 g / L, 8 g / L, 10 g / L, 12 g / L, 14 g / L, 16 g / L, 18 g / L, 20 g / L or a range consisting of any two of them. For example, if the concentration of the reducing solution is 1 g / L, 1 g of sodium hydride needs to be dissolved in 1 liter of water and stirred to form a reducing solution with a concentration of 1 g / L.

[0058] Step S130: Mix the copper salt solution and the reducing solution to form a mixed solution, and form elemental copper.

[0059] Next, the copper salt solution provided as described above is mixed with the reducing solution, and after being stirred evenly, a chemical reduction reaction occurs, wherein the copper ions are reduced to elemental copper, thereby forming the copper nodules that need to be prepared on the carrier layer in the end.

[0060] In some embodiments, after the copper salt solution and the reducing solution are mixed to form a mixed solution, a surfactant is added to the mixed solution. Adding a surfactant to the mixed solution can control the morphology and particle size of the formed copper nodules. For example, polyvinyl pyrrolidone can limit the excessive growth of copper nodule particles through its long chain structure, forming relatively uniform copper nodule particles.

[0061] Furthermore, the surfactant includes at least one of polyvinyl pyrrolidone, polyvinyl alcohol, and methyl cellulose. In the actual preparation process, one or more surfactants can be selected and used in combination according to specific needs to optimize the morphology and particle size of the copper nodule ball to meet different needs.

[0062] Specifically, the total molar amount of the surfactant needs to be in a molar ratio of 4:3 to 4:5 to the copper ion in the copper salt. The mass of the added surfactant can be calculated by the molar amount to meet the preparation requirements of the copper nodule layer.

[0063] In some embodiments, after the copper salt solution and the reducing solution are mixed to form a mixed solution, the mixed solution needs to be adjusted to be alkaline. The pH of the mixed solution is adjusted to appropriately control the degree of reduction of copper ions. It is easy to understand that the copper salt solution and the reducing solution are reduced to form elemental copper, and the rate and degree of the reduction reaction are more easily affected by the pH of the solution. The pH of the solution is changed to affect the rate and degree of the reduction reaction, thereby affecting the quality and adhesion of the copper nodule.

[0064] Exemplarily, sodium hydroxide may be added to the mixed solution. Potassium oxide may also be added to the mixed solution. Ammonia water may also be added to the mixed solution. By adding these additives to the mixed solution, the pH of the mixed solution is adjusted, the reduction rate of the reduction reaction is controlled, and the uniform attachment of the copper nodule is promoted.

[0065] Further, the concentration range of sodium hydroxide is 5-20 g / L. For example, 5 g / L, 7 g / L, 9 g / L, 11 g / L, 13 g / L, 15 g / L, 17 g / L, 19 g / L, 20 g / L or a range consisting of any two of them. For example, if the concentration of sodium hydroxide is 1 g / L, 1 g of sodium hydroxide needs to be dissolved in 1 liter of water and stirred to form a sodium hydroxide solution with a concentration of 1 g / L.

[0066] In some embodiments, after forming the final mixed solution, the mixed solution can be treated with ultrasound to suspend and disperse the reduced copper atoms. When ultrasound propagates in the mixed solution, it will cause rapid vibration of the mixed solution. This vibration can form tiny cavitation bubbles in the mixed solution, which will produce local high temperature and high pressure when they collapse, resulting in a microscopic stirring effect. The aggregation between copper atoms can be broken by treating the mixed solution with ultrasound, so that they are evenly dispersed in the mixed solution. This allows the copper atoms to be in more uniform contact with the binder, thereby improving the uniformity of the adhesion of the copper nodules on the carrier layer.

[0067] In addition, the vibration of ultrasound can prevent copper atoms from settling in the mixed solution and improve their suspension stability in the mixed solution.

[0068] Further, the vibration frequency of the ultrasonic wave is set to 20-40kHz, and the time is set to 10s-4h. Within this range, the cavitation effect generated by the ultrasonic wave is more significant. For example, the vibration frequency of the ultrasonic wave can be set to 20kHz, 25kHz, 30kHz, 35kHz, 40kHz, or a range consisting of any two thereof. The vibration time of the ultrasonic wave is set to 10s, 30min, 60min, 90min, 120min, 150min, 180min, 210min, 240min, or a range consisting of any two thereof.

[0069] Step S140, immersing the carrier layer in the mixed solution, and the elemental copper is bonded to the carrier layer by a binder to form a copper nodule layer.

[0070] Finally, the carrier layer formed by coating the binder on the surface of the copper foil is immersed in the mixed solution. The copper atoms in the mixed solution contact the surface of the metal copper foil to form attachment points, which become the nucleation sites of the copper nodules. The copper atoms are evenly dispersed and suspended in the mixed solution through ultrasonic treatment. Through the interaction forces between copper atoms (such as van der Waals force and electrostatic force), the copper atoms will spontaneously assemble at the nucleation sites according to the principle of lowest energy, and form stable copper nodules through agglomeration.

[0071] In some embodiments, the time for the carrier layer to be immersed in the mixed solution is set to 30 min to 20 h, and the time for the carrier layer to be immersed in the mixed solution will affect the adhesion and growth effect of the copper tumor ball. The time for the carrier layer to be immersed in the mixed solution can be set to 30 min, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h or a range consisting of any two of them.

[0072] In some embodiments, the temperature of the mixed solution is set to 0-20°C. The temperature of the mixed solution may affect the growth and morphology of copper atoms. The temperature of the mixed solution can be set to 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C or a range consisting of any two of them.

[0073] In some embodiments, after the copper nodule layer is formed on the surface of the carrier layer, the carrier layer with the copper nodule layer is cleaned and then dried to obtain a copper foil with a low profile. Cleaning can remove residual chemicals, unattached copper atoms and other impurities on the surface of the copper nodule layer. Drying after cleaning can remove residual water or solvent in the cleaning process, ensure the purity of the surface of the copper nodule layer, and facilitate bonding with the substrate of the circuit board to ensure the reliability of the circuit board communication.

[0074] Furthermore, the carrier layer with the copper nodule layer is cleaned with anhydrous ethanol and deionized water in sequence, which can improve the cleaning effect and promote the drying process.

[0075] Exemplarily, anhydrous ethanol has good solubility and volatility, and can dissolve and take away impurities on the surface of the copper nodule layer. Anhydrous ethanol can evaporate rapidly 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 copper nodule layer. In addition, deionized water removes various dissolved ions to avoid the risk of these ions being re-deposited on the surface of the copper nodule layer during the cleaning process, thereby causing the risk of secondary pollution.

[0076] Furthermore, after the carrier layer with the copper nodule layer is cleaned, it needs to be dried. The drying temperature is set to below 85°C and the drying time is set to 5 hours. This ensures that the residual water and solvent on the copper nodule layer are evaporated, but does not cause thermal damage or deformation to the copper nodule layer. The selection of the drying time should ensure that the residual water and solvent on the copper nodule layer are completely removed to prevent problems in subsequent use.

[0077] Exemplarily, the drying temperature can be set to 5°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 85°C or a range consisting of any two of them.

[0078] The drying time can be set to 1h, 2h, 3h, 4h, 5h or a range consisting of any two of them.

[0079] In some embodiments, the surface of the low-profile copper foil prepared by this method has copper nodules with a diameter of about 500 nanometers, a spacing between the copper nodules of about 80 nanometers, and about 6 copper nodules per square micrometer.

[0080] The following is a more detailed introduction to the method for preparing copper nodules on the surface of copper foil of the present invention through specific examples.

[0081] 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.

[0082] Example 1

[0083] The method for preparing copper nodules on the surface of copper foil provided in this embodiment comprises the following steps:

[0084] First, if Figure 2 As shown, copper foil is selected and 5% epoxy resin is applied on the surface of the copper foil to form a carrier layer.

[0085] Then, copper sulfate is added into ethanol to dissolve and prepare a 0.2 mol / L copper salt solution. Dimethylamine borane is selected to prepare a reducing solution with a concentration of 5 g / L.

[0086] Next, the copper salt solution and the reducing solution were mixed to form a mixed solution, and then the surfactant polyvinyl pyrrolidone was added to control the morphology of the copper nodules, and the total molar amount of polyvinyl pyrrolidone added was 1:1 with the molar amount of copper ions in the copper salt. The above solutions were mixed and stirred evenly, and the temperature of the mixed solution was set at 10°C. Ultrasonic assisted treatment was used, and the vibration frequency of the ultrasonic wave was set to 20kHz and the time was set to 4h.

[0087] Finally, the copper foil coated with epoxy resin is immersed in the mixed solution. The immersion time is set to 4 hours. The copper atoms are bonded to the copper foil through the epoxy resin to form a low-profile copper foil with copper nodules. The low-profile copper foil with copper nodules is cleaned and dried. Figure 3 shown.

[0088] Example 2 This example is basically the same as Example 1, except that the copper salt solution can be prepared by copper formate; other conditions remain unchanged.

[0089] Example 3 This example is basically the same as Example 1, except that the copper salt solution can be prepared by copper nitrate; other conditions remain unchanged.

[0090] Example 4 This example is basically the same as Example 1, except that the reducing solution can be prepared by hydrazine sulfate; other conditions remain unchanged.

[0091] Example 5 This example is basically the same as Example 1, except that the time for the carrier layer to be immersed in the mixed solution is set to 20 hours; other conditions remain unchanged.

[0092] Referring to the process of Example 1, the copper nodule ball constructed on the surface of the copper foil of the above example was prepared, and the relevant parameters of the copper nodule ball constructed on the prepared copper foil were tested. The measurement results are summarized in Table 1:

[0093] Table 1

[0094]

[0095] Data Analysis:

[0096] The method for preparing copper nodules on the surface of copper foil according to the embodiment of the present invention can prepare copper foil with low profile, such as Figure 4-Figure 7 As shown;

[0097] Example 2 shows that the copper salt solution prepared with copper formate can reduce the diameter of the copper nodules constructed on the surface of the copper foil, the spacing between the copper nodules is relatively small, and more copper nodules can be distributed on the surface of the copper foil;

[0098] Example 3 shows that the copper salt solution prepared with copper nitrate reduces the diameter of the copper nodules constructed on the copper foil surface, the distance between the copper nodules is smaller, and more copper nodules can be distributed on the copper foil surface;

[0099] Example 4 shows that the reducing solution can be prepared by hydrazine sulfate so that the diameter of the copper nodules constructed on the copper foil surface is appropriately reduced, the distance between the copper nodules is larger, and there can be multiple copper nodules on the copper foil surface;

[0100] Example 5 shows that the time for immersing the carrier layer in the mixed solution is set to 20 hours, so that the shape of the copper nodules constructed on the copper foil surface is slightly different from that in other examples. The spacing between the copper nodules is relatively large, and there can be multiple copper nodules on the copper foil surface.

[0101] 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 a certain feature, structure or characteristic is described in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such feature, structure or characteristic in conjunction with other embodiments, whether explicitly or not explicitly described.

[0102] 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.

[0103] 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).

[0104] 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.

[0105] 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 copper nodules on the surface of copper foil, characterized in that: include: Providing a carrier layer, the carrier layer comprising a copper foil and an adhesive disposed on a surface of the copper foil; providing a copper salt solution and a reducing solution; Mixing the copper salt solution and the reducing solution to form a mixed solution and to form elemental copper; The carrier layer is immersed in the mixed solution, and the elemental copper is bonded to the carrier layer through the binder to form a copper nodule layer; The molar concentration of copper ions in the copper salt solution is set to 0.01 to 5 mol / L; The concentration range of the reducing solution is 1-20 g / L; The reducing solution is set to be one of hydrazine, hydrazine sulfate, dimethylamine borane boron, and sodium hydride; The binder includes at least one of epoxy resin, polyamide and polyisobutylene; the concentration of the binder is set to 4%-6%; The time for immersing the carrier layer in the mixed solution is set to 30 minutes to 20 hours; The temperature of the mixed solution is set to 0-20°C.

2. The method for preparing copper nodules on the surface of copper foil according to claim 1, characterized in that: The copper salt solution includes an organic salt solution, and the organic salt solution includes copper formate or copper acetate; Alternatively, the copper salt solution comprises an inorganic salt solution, and the inorganic salt solution comprises copper sulfate or copper nitrate.

3. The method for preparing copper nodules on the surface of copper foil according to claim 1 or 2, characterized in that: After the copper salt solution and the reducing solution are mixed to form a mixed solution, adding a surfactant to the mixed solution; Wherein, the surfactant includes at least one of polyvinyl pyrrolidone, polyvinyl alcohol and methyl cellulose.

4. The method for preparing copper nodules on the surface of copper foil according to claim 1 or 2, characterized in that: After the copper salt solution and the reducing solution are mixed to form a mixed solution, the method further comprises: The mixed solution is adjusted to be alkaline.

5. The method for preparing copper nodules on the surface of copper foil according to claim 1 or 2, characterized in that: After mixing the copper salt solution and the reducing solution to form a mixed solution, the method comprises: The mixed solution is subjected to ultrasonic treatment to suspend and disperse the elemental copper.

6. The method for preparing copper nodules on the surface of copper foil according to claim 1, characterized in that: After the copper nodule layer is formed on the surface of the carrier layer, Cleaning the copper nodule layer and the carrier layer; The copper nodule layer and the carrier layer are dried.

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