CN114703515B - Copper foil, preparation method thereof, circuit board and current collector - Google Patents

Copper foil, preparation method thereof, circuit board and current collector Download PDF

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CN114703515B
CN114703515B CN202210391059.2A CN202210391059A CN114703515B CN 114703515 B CN114703515 B CN 114703515B CN 202210391059 A CN202210391059 A CN 202210391059A CN 114703515 B CN114703515 B CN 114703515B
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copper foil
interface
concentration
thickness
foil according
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CN114703515A (en
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卢磊
程钊
陈祥成
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Institute of Metal Research of CAS
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Institute of Metal Research of CAS
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D1/00—Electroforming
    • C25D1/04—Wires; Strips; Foils
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/38—Electroplating: Baths therefor from solutions of copper
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/11—Printed elements for providing electric connections to or between printed circuits
    • H05K1/111—Pads for surface mounting, e.g. lay-out
    • H05K1/112—Pads for surface mounting, e.g. lay-out directly combined with via connections
    • H05K1/113—Via provided in pad; Pad over filled via
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Composite Materials (AREA)
  • Manufacturing & Machinery (AREA)
  • Cell Electrode Carriers And Collectors (AREA)

Abstract

The invention relates to a copper foil, a preparation method thereof, a circuit board and a current collector, which mainly adopts the following technical scheme: the microstructure of the copper foil is a layered structure; wherein an interface exists between any adjacent two layers in the layered structure; wherein, in a direction parallel to the interface: each layer in the layered structure includes a plurality of grains. Depositing the copper foil by using a direct current electrolytic deposition technology; wherein, in the direct current electrolytic deposition process: the electrolyte contains additives; wherein the additive comprises gelatin, collagen, hydroxyethyl cellulose, glucose, and 2-mercaptobenzimidazole. The invention is mainly used for providing or preparing the copper foil with high strength and high elongation at the same time, and in addition, the copper foil also has lower surface roughness and higher stability. The copper foil of the invention has great application potential in the fields of lithium ion batteries and electronic circuits thanks to remarkable performance advantages.

Description

Copper foil, preparation method thereof, circuit board and current collector
Technical Field
The invention relates to the technical field of copper foil preparation, in particular to a copper foil, a preparation method thereof, a circuit board and a current collector.
Background
The copper foil material is one of the basic materials in the modern industry and is widely applied to the fields of electronic circuits, lithium ion batteries and the like. With the rapid development of 5G communication technology, intelligent electronics and high quality of new energy automobiles, the performance requirements on copper foil are higher and higher. The research on the copper foil in China is started later, the technical accumulation is less, the copper foil is mainly conventional copper foil, and the high-end copper foil with high performance is monopoly of enterprises such as Japan, korea and the like for a long time. Therefore, the development of high-end copper foil has important strategic significance for national economy and national security.
Currently, the development of high-end copper foil is along the traditional principle of "fine-grain strengthening", i.e. by reducing the grain size of the copper foil, the strength thereof is improved. Most advanced copper foil enterprises accumulate through long-term technology, and greatly explore additives capable of refining grains to realize the preparation of high-end electrolytic copper foil.
However, as the grain size is reduced, the elongation and conductivity of the copper foil are significantly reduced, which makes it difficult to apply the high strength copper foil to a wide range of applications. Analysis from the strengthening mechanism shows that when the grain size is refined, the resistance of dislocation movement to grain boundary is increased, and the strength is improved; the dislocation movement capability is reduced, the plastic deformation capability of the material is reduced, and the elongation is reduced; at the same time, the atomic arrangement at the grain boundary is in a disordered state, scattering of electrons is strong, and thus conductivity is lowered. In addition, when the size of the crystal grains is too small (for example, reaching the nanometer level), the copper foil becomes unstable, the crystal grains grow up at room temperature, and the strength is reduced, which is also an important reason that the current copper foil material is difficult to break through the strength bottleneck.
Disclosure of Invention
In view of the above, the present invention provides a copper foil, a method for preparing the same, a circuit board and a current collector, and is mainly aimed at providing or preparing a copper foil with high strength and high elongation.
In order to achieve the above purpose, the present invention mainly provides the following technical solutions:
In one aspect, embodiments of the present invention provide a copper foil, wherein the microstructure of the copper foil is a layered structure; wherein an interface exists between any adjacent two layers in the layered structure; wherein, in a direction parallel to the interface: each layer in the layered structure includes a plurality of grains.
Preferably, in a direction perpendicular to the interface, a distribution state of grains of each layer in the layered structure is one or several of the following states: a single die spans one interface, a single die spans multiple interfaces, and a single die is distributed only within the layers of the copper foil.
Preferably, the thickness of the interface is 1nm to 1. Mu.m, preferably 5nm to 200nm, more preferably 10nm to 100nm.
Preferably, the average minor axis size of the grains is in the range of 1nm to 5 μm;
Preferably, the spacing of the interfaces is 1nm to 100. Mu.m, preferably 10nm to 1. Mu.m, more preferably 10nm to 500nm.
Preferably, the interface has a density of 10 4-109m2/m3, preferably 10 6-108m2/m3.
Preferably, the interface comprises one or both of a continuous interface and a discontinuous interface.
Preferably, the interface comprises one or both of a flat interface portion, a wavy interface portion; preferably, the straight interface portion is parallel to the copper foil surface; the equilibrium position of the wave interface portion exhibits a wave-like variation parallel to the surface of the copper foil, and the non-equilibrium position (it is to be noted here that the definition of the equilibrium position refers to the equilibrium position of the wave).
Preferably, the crystal grain comprises a twin structure.
Preferably, the thickness of the copper foil is 1 to 500. Mu.m, preferably 2 to 50. Mu.m, or 40 to 300. Mu.m, further preferably 3 to 30. Mu.m, or 50 to 200. Mu.m; preferably, when the thickness of the copper foil is 1 to 4 μm, the copper foil is used for being combined with a carrier to form a carrier copper foil (preferably, a conventional copper foil is used as a carrier).
Preferably, the tensile strength of the copper foil is 300-900MPa and the elongation is higher than 3% under the condition of room temperature.
Preferably, the copper foil has a surface roughness Rz of 0.1 to 3.0 μm.
Preferably, the copper foil comprises copper elements; or the copper foil comprises copper elements with the mass fraction not less than 90%; further comprises one or more elements of silver, zinc, tin, iron, cobalt, nickel, bismuth, carbon, nitrogen, oxygen, sulfur and chlorine.
Preferably, the copper foil is deposited using a direct current electrolytic deposition technique; wherein, in the direct current electrolytic deposition process: the electrolyte contains additives; wherein the additive comprises gelatin, collagen, hydroxyethyl cellulose, glucose, and 2-mercaptobenzimidazole.
Preferably, in the electrolyte: the concentration of gelatin is 1-40mg/L, the concentration of collagen is 2-30mg/L, the concentration of hydroxyethyl cellulose is 1-10mg/L, the concentration of glucose is 10-300mg/L, and the concentration of 2-mercaptobenzimidazole is 0.5-5mg/L; preferably, the concentration of gelatin is 5-20mg/L, the concentration of collagen is 10-30mg/L, the concentration of hydroxyethyl cellulose is 1-5mg/L, the concentration of glucose is 50-200mg/L, and the concentration of 2-mercaptobenzimidazole is 2-5mg/L; preferably, the concentration of gelatin is 10-40mg/L, the concentration of collagen is 5-15mg/L, the concentration of hydroxyethyl cellulose is 4-10mg/L, the concentration of glucose is 150-300mg/L, and the concentration of 2-mercaptobenzimidazole is 1-3mg/L; preferably, the electrolyte further comprises the following components: 250-350g/L of copper sulfate pentahydrate, 20-110g/L of H 2SO4, 10-50mg/L of HCl and the balance of water.
Preferably, during the direct current electrolytic deposition process: the current density is controlled to be 10-110A/dm 2, preferably 30-80A/dm 2, more preferably 40-70A/dm 2 or 50-75A/dm 2; the temperature is controlled to 10-60 ℃, preferably 40-55 ℃.
Preferably, the spacing of the interfaces, the average minor axis size of the grains and the thickness of the interfaces in the copper foil are regulated and controlled by regulating the temperature of the electrolyte, the concentration of one or more components in the additive and the current density in the direct current electrolytic deposition process; preferably, the strength of the copper foil is regulated by adjusting one or more of the spacing of interfaces in the copper foil, the average minor axis dimension of crystal grains, the twinning structure ratio (the twinning structure ratio refers to the ratio of the volume of all twinning structures in the copper foil sample to the total volume of the copper foil sample) and the thickness of a twinning sheet layer; preferably, the surface roughness of the copper foil is adjusted by adjusting one or more of the pitch of the interface, the average minor axis size of the crystal grains, and the thickness of the interface in the copper foil.
Preferably, the strength of the copper foil is 300-900MPa when the interface thickness is 10nm-1 μm and the interface spacing is 10nm-5 μm;
preferably, the strength of the copper foil is 300-900MPa when the average minor axis size of the crystal grains is 10nm-5 μm;
preferably, in the direct current electrolytic deposition process, any one or more of temperature, current density and additive concentration are regulated and controlled simultaneously, so that the prepared copper foil can meet the following conditions: the thickness of the interface is 10nm-1 mu m, the interval of the interface is 10nm-5 mu m, the average minor axis size of the crystal grain is 10nm-5 mu m, and the strength of the copper foil is 300-900MPa; further preferred is: regulating the temperature to 20-55deg.C; the current density is regulated at 40-100A/dm 2; the concentration of the additive was controlled as follows: the concentration of gelatin is 10-40mg/L, the concentration of collagen is 5-30mg/L, the concentration of hydroxyethyl cellulose is 1-8mg/L, the concentration of glucose is 10-300mg/L, and the concentration of 2-mercaptobenzimidazole is 0.5-5mg/L.
It should be noted that: the spacing of the interfaces, the average minor axis dimension of the grains, or the thickness of the interfaces can be reduced by temperature, current density, additive adjustment alone or by simultaneous adjustment of two or three parameters.
In another aspect, an embodiment of the present invention provides a circuit board, where the circuit board includes:
a copper foil, wherein the copper foil is any one of the above-described copper foils;
The copper foil is positioned on the substrate;
Preferably, the copper foil is bonded to the substrate; further preferably, the copper foil is subjected to a surface treatment before being bonded to the substrate.
In yet another aspect, an embodiment of the present invention provides a current collector, wherein the current collector includes the copper foil of any one of the above;
preferably, the current collector further comprises graphite; wherein the graphite is bonded to the copper foil;
Preferably, the current collector is applied in a battery, preferably in a lithium ion battery.
In still another aspect, an embodiment of the present invention provides a method for packaging an electronic circuit, wherein, during packaging an electronic circuit, a copper foil is deposited in a blind hole of a circuit board by using the method for preparing a copper foil as described in any one of the above, so as to implement an electronic circuit packaging operation of wiring and interlayer interconnection of the circuit board.
Compared with the prior art, the copper foil and the preparation method thereof, and the circuit board and the current collector have at least the following beneficial effects:
In one aspect, the embodiment of the invention provides a copper foil, wherein the microstructure of the copper foil is a layered structure; wherein an interface exists between any two adjacent layers in the layered structure; wherein, in a direction parallel to the interface: each layer in the layered structure includes a plurality of grains. The copper foil of the above structure exhibits a unique layer structure on a microscopic scale, which is completely different from the conventional copper foil, and is an entirely new copper foil. On one hand, in the copper foil provided by the embodiment of the invention, the high-density interface between the adjacent layers can effectively block dislocation movement and improve the geometrically necessary dislocation density, so that the strength of the copper foil is improved and the extensibility of the copper foil is contributed; on the other hand, due to the existence of the high-density interface, the grain size of the copper foil can be reduced to the nanometer level, which is 2-3 orders of magnitude lower than that of common copper foil, especially common electrolytic copper foil, and the strength of the copper foil is further improved. For example, taking the copper foil with the average interface spacing of 210nm and the interface density of 7×10 6m2/m3 as an example, the room-temperature tensile property of 749MPa and the elongation of 5.2% are far superior to the requirements of the copper foil standard of the electronic circuit board IPC-4562 for tensile strength (276 MPa) and the copper foil standard of the lithium ion battery SJ/T11483-2014 for tensile strength (300 MPa), and the requirements of the elongation in the standard are completely satisfied.
Furthermore, the interface in the copper foil provided by the embodiment of the invention has higher stability, and the reason is that mismatch defects such as composition, orientation or lattice distortion and the like generally exist at the interface, and the interface has a certain thickness, so that the interface has higher interface migration energy barrier. The introduction of the interface enables the nanoscale tiny crystal grains to exist stably for a long time at room temperature, so that the copper foil has high strength, high elongation and high stability, and the phenomenon of inversion of the strength, elongation and stability of the conventional copper foil is broken through. Taking the copper foil with the average interface spacing of 210nm as an example, the microstructure such as the average interface spacing and grain size, and the mechanical properties such as tensile strength and elongation remain stable after the copper foil is placed for 3 months.
Furthermore, in the copper foil provided by the embodiment of the invention, the interfaces between adjacent layers can enable the growth of crystal grains in the layers to be consistent on one hand, and reduce the rapid growth of local crystal grains; on the other hand, the grain size is reduced, so that the surface roughness of the copper foil is lower. Here, taking the copper foil with the average interface spacing of 210nm as an example of the embodiment of the present invention, the surface roughness is only rz=0.30 μm (ra=0.06 μm), which is far lower than the requirement of the standard surface roughness (Rz less than or equal to 3 μm) of the copper foil of the ion battery SJ/T11483-2014. Based on the basic principle that the interface blocks crack propagation and thus improves the toughness of the metal material, the interface of the copper foil improves the crack propagation resistance of the copper foil in bending deformation, thereby being beneficial to obtaining higher bending resistance and bending resistance.
On the other hand, the embodiment of the invention provides a preparation method of the copper foil, wherein the copper foil is deposited by using a direct current electrolytic deposition technology; specifically, the selected additive not only contains strong surfactant such as gelatin, collagen and hydroxyethyl cellulose, but also contains additive with certain reducibility such as glucose and 2-mercaptobenzimidazole; in this case, under the action of the cathode polarization of the strong surfactant, the additive having the reducing property is consumed by reduction when the cathode surface is accumulated to a certain extent (the cathode potential is lowered to a certain extent), and then the cathode potential is raised to some extent, and the additive is accumulated again. As these additives are continuously accumulated and consumed at the cathode, the electric double layer resistance characteristics of the cathode surface and the cathode potential show periodic variation, thereby realizing the preparation of the copper foil with the microstructure.
Further, the preparation method of the copper foil provided by the embodiment of the invention has strong controllability and easily optimized performance. Here, by changing parameters such as current density, concentration of each component of the additive, temperature, etc., the pitch of the interface, grain size (average minor axis size), thickness of the interface, etc. in the copper foil can be adjusted, thereby achieving further optimization of the copper foil performance. Taking examples 1-3 of the present invention as an example, when the current density was increased from 50A/dm 2 to 75A/dm 2, the average interface spacing was reduced from 960nm to 140nm, so that the tensile strength of the copper foil was increased from 538MPa to 846MPa, the elongation at break was increased from 4.2% to 5.3%, and the surface roughness Rz was reduced from 0.96 μm to 0.4. Mu.m.
In conclusion, the copper foil and the preparation method thereof provided by the embodiment of the invention have the advantages of extremely high strength, higher elongation, higher stability, extremely low surface roughness, higher bending resistance, flex resistance and the like, and greatly meet the development requirements of high safety, high stability, high energy density and low cost of high-performance lithium ion batteries and electronic circuits, so that the copper foil has great application prospects in the fields of new energy batteries and electronic circuits.
The foregoing description is only an overview of the present invention, and is intended to provide a better understanding of the present invention, as it is embodied in the following description, with reference to the preferred embodiments of the present invention and the accompanying drawings.
Drawings
Fig. 1 is a cross-sectional view of the copper foil prepared in example 1 in the thickness direction under a scanning electron microscope.
Fig. 2 is an energy dispersive X-ray spectrometer (EDS) spectrum of the copper foil prepared in example 1 in the thickness direction under a scanning electron microscope.
Fig. 3 is an engineering stress-strain curve of the copper foil prepared in example 1.
Fig. 4 is a cross-sectional view of the copper foil prepared in example 2 in the thickness direction under a scanning electron microscope.
Fig. 5 is an engineering stress-strain curve of the copper foil prepared in example 2.
Fig. 6 is a cross-sectional view of the copper foil prepared in example 3 in the thickness direction under a scanning electron microscope.
Fig. 7 is an engineering stress-strain curve of the copper foil prepared in example 3.
Detailed Description
In order to further describe the technical means and effects adopted for achieving the preset aim of the invention, the following detailed description refers to the specific implementation, structure, characteristics and effects according to the application of the invention with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, the particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.
In recent years, the inventor's team has found that the layered structure can significantly enhance the mechanical properties of the metal material, so that the metal material has both higher strength and good elongation. The metal material with the layered structure is mainly characterized in that one or more interfaces exist in the material, and the strength and the elongation of the metal material are synchronously improved along with the reduction of the interface distance or the increase of the interface density, so that the limitation of inversion of the strength and the elongation is broken through. On one hand, the interface can directly block dislocation movement, so that higher strength is achieved; on the other hand, at the same time, a certain thickness of interface is often formed between two adjacent layers, and the plastic deformation of the interface is different from that of the adjacent layers, so that a plastic strain gradient is formed, the extra storage of geometrically necessary dislocation is realized, and the work hardening performance of the layered structure material is improved, so that the elongation of the metal material can be improved.
Based on the above research, the application innovatively introduces a high-density interface into the copper foil to form a unique microcosmic layered structure, thereby providing and preparing the copper foil with high strength and high elongation.
The scheme of the invention is as follows:
In one aspect, embodiments of the present invention provide a copper foil having a microstructure with a unique layered structure, each layer being disposed parallel to the surface of the copper foil, with interfaces having a thickness between adjacent layers.
The thickness values of the interfaces in the regions of the same copper foil are not exactly the same. The thickness of the interface is adjusted in the range of 1nm to 1. Mu.m, preferably 5nm to 200nm, and more preferably 10nm to 100nm.
The spacing of the interfaces is defined as: and on the copper foil, the distance between the centers of two adjacent interfaces. The spacing of the interfaces of the areas in the same copper foil is not completely the same; the spacing of the interfaces in the copper foil can be adjusted to a range of 1nm to 100. Mu.m, preferably 10nm to 1. Mu.m, and more preferably 10nm to 500nm. In the copper foil, the variation trend of the spacing of the interface along the thickness direction of the copper foil includes constant, gradual increase, gradual decrease, periodic increase or decrease, or random variation.
The density of the interface is defined as: the sum of the areas of the interfaces per unit volume of the copper foil. The density of the interface is in the range of 10 4-109m2/m3, preferably 10 6-108m2/m3, and more preferably 2×10 6-108m2/m3.
The interface of the copper foil is parallel to the copper foil surface. From a shape perspective, the interface includes one or both of a straight interface portion and a wavy interface portion. Wherein the straight interface portion refers to an interface portion parallel to the surface of the copper foil; the wave interface refers to an interface portion that is a curved surface with its equilibrium position parallel to the copper foil surface but with a local position offset from the equilibrium position exhibiting a wave-like variation.
The interface of the copper foil includes one or two of a continuous interface and a discontinuous interface in terms of continuity. The continuous interface means that the interface is continuous along the horizontal direction and is not interrupted by grains; discontinuous interfaces refer to interfaces that are discontinuous in the horizontal direction, interrupted by grains.
In a direction parallel to the interface, each layer is composed of a plurality of crystal grains (specifically, each layer is composed of a plurality of crystal grains). In the direction perpendicular to the interface, the positional relationship between the crystal grain and the interface includes: a single die may span one or more interfaces, and a die may not span an interface but may be distributed within a single layer. In the case where a single grain can span one or more interfaces, the number of interfaces that the grain can span is in the range of 1 to 100, preferably 1 to 20 or 15 to 50, more preferably 1 to 10 or 20 to 40.
Each layer of the copper foil comprises (preferably consists of) a plurality of grains, which may be columnar or equiaxed in shape; preferably, a twin structure may be included within the grains; more preferably, the mean twin sheet layer thickness of the twin structure is up to 100nm or less. The copper foil has a short axis size of average crystal grains ranging from 1nm to 5. Mu.m, preferably from 50nm to 600nm or from 500nm to 3. Mu.m, more preferably from 80nm to 300nm or from 800nm to 2. Mu.m. The trend of variation of the grain short axis dimension of the copper foil along the thickness direction includes constant, gradual increase, gradual decrease, periodic increase or decrease, or random variation.
The thickness of the copper foil according to the embodiment of the present invention is in the range of 1 to 500. Mu.m, preferably 2 to 50. Mu.m, or 40 to 300. Mu.m, more preferably 3 to 30. Mu.m, or 50 to 200. Mu.m. Wherein, when the thickness of the copper foil is 1-4 μm, the carrier copper foil can be formed by compounding with a conventional copper foil to facilitate transportation, processing and use. There are various ways of compounding the copper foil with the conventional copper foil, such as adhesion, mechanical press-fitting, etc. Alternative supports include conventional copper foil, aluminum foil, organic film, and the like, with the support thickness preferably being set between 6-30 microns.
The copper foil of the embodiment of the invention is bonded with the substrate to prepare a conductive circuit, and the conductive circuit is used for preparing various Copper Clad Laminates (CCLs), printed Circuit Boards (PCBs) and the like. Wherein, the base plate contains hard board and soft board. The copper foil is required to be subjected to surface treatments including roughening, curing, oxidation preventing, galvanization, silane coupling agent treatment, etc. before being bonded to the substrate, in order to improve its peel strength and oxidation resistance. The copper foil of the present invention can be widely used in conventional printed circuit boards and special high performance printed circuit boards such as high frequency high speed circuits, integrated circuit packaging carrier boards, fine circuits (HDI), high power high current circuits, flexible circuits, etc. The application has the advantages that the surface roughness of the copper foil is low, the loss of the copper foil in the circuit board in the process of conducting electricity or transmitting signals is reduced, and the enhancement effect plays an important role in improving the signal transmission quality of the high-frequency high-speed circuit board. In addition, the barrier effect of the interface of the copper foil on crack propagation contributes to the improvement of bending and flexing resistance of the circuit board, which has a significant positive effect on improving the service environment margin and service life of the flexible circuit board.
The copper foil provided by the embodiment of the invention has a great prospect in a lithium ion battery. The copper foil can replace the conventional copper foil in the prior art and is used for manufacturing a current collector of the lithium ion battery by being bonded with graphite. The copper foil has the advantages that the tensile strength of the copper foil is extremely high, the extension rate and the stability are also high, on one hand, the thickness of the copper foil used in the lithium ion battery can be effectively reduced under the condition of meeting the bearing capacity, and the capacity of the lithium ion battery is improved; on the other hand, the bearing capacity and the service life of the current collector in the lithium ion battery can be improved, so that the safety of the battery can be remarkably improved and the service life of the battery can be prolonged.
On the other hand, the embodiment of the invention provides a preparation method of the copper foil, and specifically, the copper foil can be obtained by using a direct current electrolytic deposition technology, or can be obtained by using a rolling technology and the like. The preparation method is exemplified by a direct current electrolytic deposition technique, and is specifically as follows:
In the direct current electrolytic deposition process: the current density is controlled to be 10-110A/dm 2, preferably 30-80A/dm 2, more preferably 40-70A/dm 2 or 50-75A/dm 2; the temperature is controlled to be 10-60 ℃, preferably 40-55 ℃.
The anode and the cathode respectively use a titanium plate and a pure titanium plate with iridium tantalum coating, and the distance between the titanium plate and the pure titanium plate is 5-40mm, preferably 5-15mm; the circulation speed of the solution is 1-25m 3/h, preferably 2-20m 3/h, more preferably 3-10m 3/h or 5-15m 3/h; the deposition mode is electrolytic bath flat plate deposition or electrolytic copper foil raw foil machine roller deposition. What should be stated here is: electrodeposited copper foil is generally classified into plate electrodeposition and roller deposition, the length of plate electrodeposition time generally determines the thickness of the copper foil, and the speed of roller electrodeposition speed generally determines the thickness of the copper foil.
In the preparation method of the copper foil, the electrolyte comprises 250-350g/L of copper sulfate pentahydrate, 20-110g/L of H 2SO4, 10-50mg/L of HCl and purified water. The electrolyte used also contains additives, which include not only surfactants but also reducing agents. Wherein, the concentration of the surfactant gelatin is 1-40mg/L, the concentration of the collagen is 2-30mg/L, and the concentration of the hydroxyethyl cellulose is 1-10mg/L; the concentration of the reducing agent glucose is 10-300mg/L, and the concentration of the 2-mercaptobenzimidazole is 0.5-5mg/L. In a preferred mode, the concentration of gelatin is 5-20mg/L, the concentration of collagen is 10-30mg/L, the concentration of hydroxyethyl cellulose is 1-5mg/L, the concentration of glucose is 50-200mg/L, and the concentration of 2-mercaptobenzimidazole is 2-5mg/L; in another preferred mode, the concentration of gelatin is 10-40mg/L, the concentration of collagen is 5-15mg/L, the concentration of hydroxyethyl cellulose is 4-10mg/L, the concentration of glucose is 150-300mg/L, and the concentration of 2-mercaptobenzimidazole is 1-3mg/L.
The copper foil of the embodiment of the invention can be composed of copper elements, and can also comprise one or more elements of silver, zinc, tin, iron, cobalt, nickel, bismuth, carbon, nitrogen, oxygen, sulfur, chlorine and the like besides copper elements. Among the elements of the copper foil with the layered structure, besides the elements which are actively added, the elements are also influenced by the purity of the solution and additives. Still further, when composed of a plurality of elements, the trend of the variation of the copper element content along the thickness direction of the copper foil (see arrow in fig. 1, 4 or 6) includes constant, gradual increase, gradual decrease, periodic increase or decrease, or random variation.
The invention can also adjust the spacing of the interfaces, the grain size and the thickness of the interfaces in the copper foil by adjusting parameters in the preparation process. The specific method comprises the following steps:
Among other methods of reducing the spacing of the interfaces include, but are not limited to: increasing the current density; reducing the temperature of the electrolyte; and increasing the concentration of one or more additives of gelatin, collagen, hydroxyethyl cellulose, glucose and 2-mercaptobenzimidazole. The above methods may be used alone or in combination of two or three methods. Methods of increasing the spacing of the interfaces include, but are not limited to, decreasing the current density; raising the temperature of the electrolyte, reducing the concentration of one or more additives of gelatin, collagen, hydroxyethyl cellulose, glucose and 2-mercaptobenzimidazole, etc. The above methods may be used alone or in combination of two or three methods.
Methods of reducing the grain size of copper foil include, but are not limited to: increasing the current density; reducing the temperature of the electrolyte; and increasing the concentration of one or more additives of gelatin, collagen, hydroxyethyl cellulose, glucose and 2-mercaptobenzimidazole. The above methods may be used alone or in combination of two or three methods. Methods of increasing the grain size of copper foil include, but are not limited to: reducing the current density; raising the temperature of the electrolyte; reducing the concentration of one or more additives of gelatin, collagen, hydroxyethyl cellulose, glucose and 2-mercaptobenzimidazole, etc. The above methods may be used alone or in combination of two or three methods.
Methods of reducing the thickness of the interface include, but are not limited to: increasing the current density; reducing the temperature of the electrolyte; increasing the concentration of one or more additives of gelatin, collagen, hydroxyethyl cellulose, glucose and 2-mercaptobenzimidazole, etc. The above methods may be used alone or in combination of two or three methods. Methods of increasing the thickness of the interface include, but are not limited to: reducing the current density; raising the temperature of the electrolyte; reducing the concentration of one or more additives of gelatin, collagen, hydroxyethyl cellulose, glucose and 2-mercaptobenzimidazole, etc. The above methods may be used alone or in combination of two or three methods.
Methods for improving the strength of copper foil include, but are not limited to: reducing the spacing of the interfaces; reducing the size of the grains (average minor axis size of the grains); reducing the thickness of the interface; increasing the duty ratio of the twin crystal structure; the thickness of the twin layer is reduced. The above methods may be used alone or in combination of two or more methods. Methods of reducing the strength of copper foil include, but are not limited to: increasing the spacing of the interfaces; increasing the grain size; increasing the thickness of the interface; the twinning structure duty ratio is reduced; the twin wafer layer thickness is increased. The above methods may be used alone or in combination of two or more methods.
Methods of reducing surface roughness of copper foil include, but are not limited to: reducing the spacing of the interfaces; reducing the grain size (average minor axis size of the grains); the thickness of the interface is reduced. The above methods may be used alone or in combination of two or more methods. Methods of increasing the surface roughness of copper foil include, but are not limited to: increasing the spacing of the interfaces; increasing the grain size; increasing the thickness of the interface. The above methods may be used alone or in combination of two or more methods.
In addition, the preparation method of the copper foil can be directly applied to the packaging process of the circuit board, and the operations such as blind hole filling and the like are carried out according to design requirements, so that the electronic circuit packaging operations such as circuit board wiring and interlayer interconnection and the like are realized. Therefore, the copper foil preparation method can be widely applied to the fields of integrated circuit packaging, very large scale integrated circuit chips and the like. The interface has strong defect (vacancy, interstitial atom and the like) absorption capacity and has a large barrier effect on the diffusion of atoms, so that the weldability and electromigration resistance of the electronic device can be remarkably improved, and the stability and the service life of an electronic circuit are improved.
For a further understanding of the present invention, reference should be made to the following description of the invention taken in conjunction with the accompanying drawings, which are included to provide a further understanding of the nature and advantages of the invention, and not to the limit of the claims.
Example 1
The copper foil is prepared mainly by a direct current electrolytic deposition method in the embodiment, and specifically comprises the following steps:
1. Electrolytic deposition apparatus: DC voltage-stabilizing and current-stabilizing power supply;
Electrolyte requirements for electrolytic deposition: preparing a copper sulfate solution by using analytically pure copper sulfate pentahydrate and purified water, wherein the concentration of the solution is about 300g/L, then adding analytically pure concentrated sulfuric acid into the solution to ensure that the concentration of H 2SO4 is 100g/L, and adding HCL to ensure that the concentration of HCl is 15mg/L to form an electrodeposited base solution. Then adding additives, specifically, gelatin with concentration of 8mg/L, collagen with concentration of 10mg/L, hydroxyethyl cellulose with concentration of 6mg/L, glucose with concentration of 100mg/L and 2-mercaptobenzimidazole with concentration of 2mg/L.
The anode and the cathode are respectively an iridium tantalum titanium plate and a pure titanium plate.
2. Electrolytic deposition process parameters: electroplating copper foil by adopting a direct current electrolysis mode, wherein the current density is 50A/dm 2; the cathodes and the anodes are arranged in parallel, the interval is 10mm, and the area-to-size ratio of the cathodes to the anodes is 1:1; the electrolysis temperature is 53 ℃; electrolyte circulation is carried out by adopting a water pump, and the power of the water pump is 2m 3/h; the preparation time (deposition time) was 1.5 minutes.
The copper foil prepared in this example had an area of 120X 100mm 2 and a thickness of 10.6. Mu.m, as measured by a weighing method.
The copper foil prepared in this example was tested by scanning electron microscopy, as shown in fig. 1, and shows that the microstructure of the copper foil has a remarkable layered structure, and a remarkable interface exists between each layer. The spacing of the interfaces is shown as t 1 in figure 1. The spacing of the interfaces along the thickness direction of the copper foil is not a constant value, and shows a random variation trend, the variation range is 500nm to 2.5 mu m, and the average spacing of the interfaces is 960nm. The density of the interface ranged from 4 x10 5m2/m3 to 2 x10 6m2/m3, with an average interface density of 1 x10 6m2/m3. The thickness of the interface is shown as t 2 in FIG. 1, and is in the range of 80nm-230nm, and the average thickness of the interface is about 150nm.
In the horizontal direction parallel to the interface, each layer is composed of a plurality of crystal grains. In the vertical direction (copper foil thickness direction) perpendicular to the interface, most of the area is shown as 1-1 area in fig. 1, each layer is composed of 1-3 grains, each grain does not cross the interface, and only each layer is distributed; at the same time, there is also a partial region (as shown in region 1-2), one grain crossing the interface, and being present in both layers.
In the interface of the copper foil prepared in this example, a part of the interface is a flat interface, as shown in the area 1-3 in fig. 1; the other part of the interface is a wave interface, as shown in the area 1-4 in fig. 1. And the interfaces at regions 1-3 and 1-4 in FIG. 1 are continuous interfaces, representing the majority of the interface types of the copper foil sample; in addition, there are discontinuous interfaces, as shown by the areas 1-5 in FIG. 1, which are interrupted by a grain from left to right.
In each layer of the copper foil prepared in this example, some of the grains are equiaxed, as shown in the 1-6 regions of fig. 1; some of the grains are columnar with the long axis direction perpendicular to the interface, as shown by the area 1-2 in fig. 1. Along the thickness direction of the copper foil, the grain size is not a constant value, and shows a random variation trend, and the average minor axis size of all grains in the copper foil is 340nm. Wherein a portion of the grains can observe a distinct nano-twin structure, as shown in regions 1-7 of fig. 1. The copper foil has good toughness, can be completely taken down from the titanium plate, and has no pinholes.
The energy dispersive X-ray spectrometer (EDS) spectrum of the copper foil prepared in this example, as shown in fig. 2, can be seen: in addition to having a significant copper peak, there is a weak carbon peak, which indicates the presence of carbon elements in addition to copper elements. However, the quantitative analysis result shows that the copper foil contains 100% copper element (see upper right corner of fig. 2), because the content of carbon element is extremely low, and it is difficult to quantitatively detect.
The roughness of the roughened surface of the copper foil prepared in this example was rz=0.96 μm and ra=0.19 μm.
The room temperature stretching results of the copper foil prepared in this example are shown in fig. 3. The test conditions were: the tensile test pattern is cut by a JDC-0.5-10 precision cutter, the length and the width are 70mm multiplied by 12mm, and the tensile property is tested by an Instron5848 tensile testing machine, and the tensile rate is 50mm/min. The test results were as follows: the copper foil prepared in this example had a tensile strength of 538MPa and an elongation at break of 4.2%.
Example 2
This example mainly prepared copper foil by a direct current electrolytic deposition method, wherein this example is different from example 1 in that:
In the present example, the current density was adjusted to increase the current density to 65A/dm 2 during the DC electrodeposition. Meanwhile, the concentration of each additive in the electrolyte adopted in this example was adjusted as follows: the concentration of gelatin is 10mg/L, the concentration of collagen is 15mg/L, the concentration of hydroxyethyl cellulose is 3mg/L, the concentration of glucose is 150mg/L, and the concentration of 2-mercaptobenzimidazole is 2.5mg/L. In addition, the time of electrodeposition was 1 minute.
The copper foil prepared in this example had a thickness of 10.8. Mu.m, as measured by a weighing method.
The copper foil prepared in this example was tested by scanning electron microscopy, as shown in fig. 4, and the microstructure of the copper foil was shown to have a distinct layered structure, with most of the grains being elongated columnar crystals, and the columnar crystals spanning 1-15 interfaces. As shown in region 4-1 of FIG. 4, one columnar crystal spans 8 interfaces.
Compared with example 1, the present example reduces the average interface spacing (see t 1 in fig. 4) to 210nm, increases the average interface density to 5×10 6m2/m3, and reduces the average interface thickness (see t 2 in fig. 4) to 70nm by adjusting the current density and concentration parameters of each additive. The pitch of the interface has a weak tendency to increase in the thickness direction, and the average interface pitch is 193nm when the interface is close to the lower surface (light surface) and 216nm when the interface is close to the upper surface (rough surface).
In the copper foil prepared in this example, most of the interfaces were continuous interfaces, but a small portion of the discontinuous interfaces were also present, as shown in the region 4-2 of fig. 4. Further, the copper foil prepared in this example had both a flat interface and a wavy interface, wherein the wavy interface had a smaller volatility (the extent of deviation from the equilibrium position) than that of the copper foil of example 1.
The average minor axis size of the crystal grains of the copper foil prepared in this example was reduced to 160nm, and the crystal grain size also had a weak tendency to increase in the thickness direction, and when it was close to the lower surface (smooth surface), the average minor axis size of the crystal grains was 140nm; near the upper surface (rough surface), the average minor axis size of the grains was 180nm. In the copper foil prepared in this example, a part of the crystal grains have a high-density twin boundary as shown by the approximately vertical grain boundary in the region 4-3 of fig. 4.
Compared with example 1, this example achieves reduction of the spacing of the interfaces, the grain size (average minor axis size of the grains) and the thickness of the interfaces by actively controlling the current density and the concentration of each additive, and reduction of the roughness of the roughened surface of the copper foil to rz=0.3 μm, ra=0.06 μm.
The results of the room temperature tensile test of the copper foil prepared in this example are shown in fig. 5. Compared with the embodiment 1, the method reduces the spacing, grain size and interface thickness of the interface by actively controlling the current density and the concentration of each additive, so that the tensile strength of the copper foil is improved to 749MPa, and the elongation is 5.2%. And, after the copper foil of this example is kept at room temperature for 2 months, the tensile strength and elongation remain substantially unchanged (the change rate is less than 5%), which means that the copper foil prepared in this example has higher stability.
Example 3
This example mainly prepared copper foil by a direct current electrolytic deposition method, wherein this example is different from example 1 in that:
This example further increases the current density to 75A/dm 2. The concentration of each additive in the electrolyte was adjusted to 16mg/L of gelatin, 12mg/L of collagen, 2mg/L of hydroxyethyl cellulose, 250mg/L of glucose and 3mg/L of 2-mercaptobenzimidazole. And, the electrodeposition time was 1 minute.
The copper foil prepared in this example had a thickness of 12 μm as measured by a weighing method.
The copper foil prepared in this example was tested by scanning electron microscopy, as shown in fig. 6, and the microstructure of the copper foil prepared in this example was shown to have a distinct layered structure, with most of the grains being elongated columnar crystals, and the columnar crystals spanning 1-35 interfaces. As shown in region 6-1 of FIG. 6, one columnar crystal spans 21 interfaces.
Compared with example 1, the method further reduces the interval of the average interface in the copper foil (see t 1 in fig. 6) to 140nm by controlling the process parameters, further increases the density of the average interface to 7×10 6m2/m3, and further reduces the thickness of the average interface (see t 2 in fig. 6) to 60nm. The pitch of the interface has a weak tendency to increase in the thickness direction, and the average interface pitch is 120nm when approaching the lower surface (light surface) and 183nm when approaching the upper surface (rough surface).
The interface of the copper foil prepared in this example was mostly a continuous interface, and there was some discontinuous interface near the lower surface of the copper foil (see lower side of fig. 6). In addition, in the copper foil prepared in this example, a flat interface and a wavy interface exist at the same time, and the interface below in FIG. 6 is mostly a wavy interface, the volatility of which is higher than that of other regions,
In the copper foil prepared in this example, the average minor axis size of the crystal grains was 300nm, which is slightly lower than that of example 1. The grain size in this example also had a weak tendency to increase in the thickness direction, and the average minor axis size of the grains was 210nm when approaching the lower surface (smooth surface) and 350nm when approaching the upper surface (rough surface).
Compared with example 1, the present example greatly reduces the spacing of the interfaces and the thickness of the interfaces by actively controlling the current density and the concentration of each additive in the electrolyte, and the roughness of the roughened surface of the copper foil is reduced to rz=0.4 μm, ra=0.08 μm.
The results of room temperature tensile test of the copper foil prepared in this example are shown in fig. 7. Compared with the embodiment 1, the embodiment greatly reduces the interval of the interface and the thickness of the interface by actively controlling the current density and the concentration of each additive, so that the tensile strength of the copper foil of the embodiment is further improved to 846MPa, and the breaking elongation is improved to 5.3%.
Comparative example 1
The mechanical property requirements of the standard IPC-4562 of the printed board metal foil on the standard electrolytic copper foil with the thickness of 17 mu m include: the tensile strength is more than or equal to 207MPa, and the elongation is more than or equal to 2%; the elongation percentage of the rolled and forged copper foil with the thickness of 17 mu m is more than or equal to 0.5 percent when the tensile strength is more than or equal to 345 MPa.
Comparative example 2
The electrolytic copper foil industry standard SJ/T11483-2014 for the lithium ion battery comprises the following requirements: LBEC-01 model, when the thickness is 8-20 μm, the tensile strength is more than or equal to 294MPa, the elongation is more than or equal to 3%, and the roughness Rz of the rough surface is less than or equal to 3.0 μm; LBEC-02, the tensile strength is not less than 300MPa, the elongation is not less than 2.5%, and the roughness Rz of the rough surface is not more than 3.0 μm, 4.0 μm, 4.5 μm and 5.0 μm when the thicknesses are 8 μm, 9 μm, 10 μm and 12 μm, measured at room temperature (23 ℃); LBEC-03 model, when the thickness is 9 μm, 10 μm, 12 μm, the tensile strength is more than or equal to 300MPa, the elongation is more than or equal to 2.5%, the roughness Rz of the rough surface is less than or equal to 4.0 μm, 4.5 μm and 5.0 μm measured at room temperature (23 ℃); LBEC-04 model, when the thickness is 10 μm and 12 μm, the tensile strength is more than or equal to 300MPa, the elongation is more than or equal to 2.5%, and the roughness Rz of the rough surface is less than or equal to 5.0 μm and 6.0 μm measured at room temperature (23 ℃).
Comparative example 3
He Tian et al (university of south Chang, university of Shuoshi paper, 2011) showed that the process parameters were: the temperature is 60 ℃, the current density is 65A/dm 2, the copper ion concentration is 80-90g/L (the equivalent weight of the copper sulfate pentahydrate is 312-350 g/L), and when the concentration of H 2SO4 is 120-130g/L and the concentration of HCl is 30-40mg/L, no additive is used. The prepared copper foil has a thickness of 18 mu m, a common polycrystalline structure inside, a grain size of micron order, a tensile strength of about 380MPa, an elongation of about 5.5% and a surface roughness rz=5.2 mu m.
The tensile strength of the copper foil prepared by the embodiment of the invention is far higher than the requirements of electrolytic copper foil standards IPC-4562 and SJ/T11483-2014. Meanwhile, the copper foil prepared by the embodiment of the invention has higher elongation and lower surface roughness, which are closely related to the microstructure and high-density interface of the copper foil. The copper foil prepared by the embodiment of the invention is suitable for the current collector of the battery, and the remarkable performance advantages of tensile strength, elongation, surface roughness and the like accord with the development trend of high capacity, high safety, high stability and low cost of the high-performance lithium ion battery. Meanwhile, due to the enhancement effect of the high-density interface on deflection resistance and bending resistance, the stabilization effect on microstructure and mechanical property and the reduction effect on surface roughness, the copper foil prepared by the embodiment of the invention and the preparation method thereof are also respectively suitable for circuit board manufacture and electronic circuit packaging, and have larger application potential particularly in flexible circuit boards and high-frequency high-speed circuit boards. In addition, the copper foil prepared by the embodiment of the invention has wide variation range of mechanical property and surface roughness, so that the copper foil has wide application range. In addition, the technical scheme of the invention can control the microstructure parameters such as the interval of the interface, the density of the interface, the grain size and the like of the copper foil by actively regulating and controlling the technological parameters such as the current density, the additive concentration, the temperature and the like, thereby further optimizing the mechanical property and the surface roughness of the copper foil and providing technical support for preparing the laminated structure copper foil aiming at different use performance requirements. Therefore, the copper foil with the microstructure in the layered structure prepared by the embodiment of the invention has great commercial application value as a brand new copper foil material.
The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement the same according to the content of the present invention, and are not intended to limit the scope of the present invention. Effective changes or modifications made in accordance with the spirit of the present invention should be included in the scope of the present invention.

Claims (30)

1. A copper foil, characterized in that the microstructure of the copper foil is a layered structure; wherein an interface exists between any adjacent two layers in the layered structure; wherein, in a direction parallel to the interface: each layer in the layered structure comprises a plurality of grains;
Wherein, in the direction perpendicular to the interface, the distribution state of the crystal grains of each layer in the layered structure is one or more of the following states: single grains span one interface, single grains span multiple interfaces, and single grains are only distributed in the layer of the copper foil;
The thickness of the interface is 1nm-1 mu m, and the interval of the interface is 1nm-100 mu m;
the grain comprises a twin structure;
The interface comprises one or two of a flat interface part and a wave interface part; wherein the straight interface portion is parallel to the copper foil surface; the equilibrium position of the fluctuation interface part is parallel to the surface of the copper foil, and the unbalanced position shows wave-like change;
Wherein the density of the interface is 10 4-109m2/m3; the interface comprises one or two of a continuous interface and a discontinuous interface; the average minor axis size of the grains is in the range of 1nm to 5 μm.
2. The copper foil according to claim 1, wherein the interface has a thickness of 5nm to 200nm.
3. The copper foil according to claim 2, wherein the interface has a thickness of 10nm to 100nm.
4. The copper foil according to claim 1, wherein the interface has a pitch of 10nm to 1 μm.
5. The copper foil according to claim 4, wherein the interface has a pitch of 10nm to 500nm.
6. The copper foil of claim 1, wherein the interface has a density of 10 6-108m2/m3.
7. The copper foil according to claim 1, wherein the copper foil has a thickness of 1 to 500 μm.
8. The copper foil according to claim 7, wherein the copper foil has a thickness of 2-50 μm or 40-300 μm.
9. The copper foil according to claim 8, wherein the copper foil has a thickness of 3-30 μm or 50-200 μm.
10. The copper foil according to claim 1, wherein the copper foil has a tensile strength of 538-900MPa and an elongation of more than 3% at room temperature.
11. The copper foil according to claim 1, wherein the copper foil has a surface roughness Rz of 0.1 to 3.0 μm.
12. The copper foil of claim 1, wherein,
The copper foil comprises copper elements; or (b)
The copper foil comprises copper elements with the mass fraction of not less than 90% and one or more elements of silver, zinc, tin, iron, cobalt, nickel, bismuth, carbon, nitrogen, oxygen, sulfur and chlorine.
13. The method of producing a copper foil according to any one of claims 1 to 12, wherein the copper foil is deposited using a direct current electrolytic deposition technique; wherein,
In the direct current electrolytic deposition process: the electrolyte contains additives; wherein the additive comprises gelatin, collagen, hydroxyethyl cellulose, glucose, and 2-mercaptobenzimidazole;
Wherein, in the electrolyte: the concentration of gelatin is 1-40mg/L, the concentration of collagen is 2-30mg/L, the concentration of hydroxyethyl cellulose is 1-10mg/L, the concentration of glucose is 10-300mg/L, and the concentration of 2-mercaptobenzimidazole is 0.5-5mg/L;
Wherein, in the direct current electrolytic deposition process: the current density is controlled to be 10-110A/dm 2, and the temperature is controlled to be 10-60 ℃.
14. The method for producing a copper foil according to claim 13, wherein,
The concentration of gelatin is 5-20mg/L, the concentration of collagen is 10-30mg/L, the concentration of hydroxyethyl cellulose is 1-5mg/L, the concentration of glucose is 50-200mg/L, and the concentration of 2-mercaptobenzimidazole is 2-5mg/L.
15. The method for preparing copper foil according to claim 14, wherein the concentration of gelatin is 10-40mg/L, the concentration of collagen is 5-15mg/L, the concentration of hydroxyethyl cellulose is 4-10mg/L, the concentration of glucose is 150-300mg/L, and the concentration of 2-mercaptobenzimidazole is 1-3mg/L.
16. The method of producing a copper foil according to claim 13, wherein the electrolytic solution further comprises the following components: 250-350g/L of copper sulfate pentahydrate, 20-110g/L of H 2SO4, 10-50mg/L of HCl and the balance of water.
17. The method for producing a copper foil according to any one of claims 13 to 16, wherein, in the direct current electrolytic deposition process: the current density is controlled to be 30-80A/dm 2.
18. The method of producing copper foil according to claim 17, wherein, in the direct current electrolytic deposition process: the current density is controlled to be 40-70A/dm 2 or 50-75A/dm 2.
19. The method for producing a copper foil according to any one of claims 13 to 16, wherein, in the direct current electrolytic deposition process: the temperature is controlled to be 40-55 ℃.
20. The method for preparing a copper foil according to any one of claims 13 to 16, wherein the interval of the interface, the average minor axis size of the crystal grains, and the thickness of the interface in the copper foil are controlled by adjusting the temperature of the electrolyte, the concentration of one or more components in the additive, and the current density during the direct current electrolytic deposition.
21. The method of producing a copper foil according to claim 20, wherein the strength of the copper foil is controlled by adjusting one or more of a pitch of an interface in the copper foil, an average minor axis size of crystal grains, a twinning structure ratio, and a twinning sheet thickness.
22. The method of producing a copper foil according to claim 20, wherein the surface roughness of the copper foil is adjusted by adjusting one or more of a pitch of an interface, an average minor axis size of crystal grains, and a thickness of an interface in the copper foil.
23. A circuit board, the circuit board comprising:
a copper foil, which is the copper foil according to any one of claims 1 to 12;
And the copper foil is positioned on the substrate.
24. The circuit board of claim 23, wherein the copper foil is bonded to the substrate.
25. The circuit board of claim 24, wherein the copper foil is subjected to a surface treatment prior to bonding the copper foil to the substrate.
26. A current collector comprising the copper foil of any one of claims 1-12.
27. The current collector of claim 26, wherein the current collector comprises,
The current collector also includes graphite; wherein the graphite is bonded to the copper foil.
28. The current collector of claim 26, wherein the current collector is used in a battery.
29. The current collector of claim 28, wherein the current collector is applied to
In lithium ion batteries.
30. A method of electronic circuit packaging, characterized in that, in the electronic circuit packaging, copper foil is deposited in blind holes of a circuit board by the method of manufacturing copper foil according to any one of claims 13 to 22, so as to realize electronic circuit packaging operation of wiring and interlayer interconnection of the circuit board.
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