CN114703515A - Copper foil and preparation method thereof, and circuit board and current collector - Google Patents

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

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CN114703515A
CN114703515A CN202210391059.2A CN202210391059A CN114703515A CN 114703515 A CN114703515 A CN 114703515A CN 202210391059 A CN202210391059 A CN 202210391059A CN 114703515 A CN114703515 A CN 114703515A
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copper foil
interface
concentration
thickness
crystal grains
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CN114703515B (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)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Microelectronics & Electronic Packaging (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 and a circuit board and a current collector, which mainly adopt the technical scheme that: 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 comprises 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 additive; 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, and in addition, the copper foil also has lower surface roughness and higher stability. The copper foil has great application potential in the fields of lithium ion batteries and electronic circuits due to the remarkable performance advantages.

Description

Copper foil and preparation method thereof, and circuit board and current collector
Technical Field
The invention relates to the technical field of copper foil preparation, in particular to a copper foil and a preparation method thereof, and a circuit board and a current collector.
Background
The copper foil material is one of the basic materials in modern industry, and is widely applied to the fields of electronic circuits, lithium ion batteries and the like. With the rapid development of the 5G communication technology, the high quality of intelligent electronics and new energy automobiles, the performance requirement on the copper foil is higher and higher. The research on the copper foil in China starts late, the technology accumulation is less, the copper foil is mainly the conventional copper foil, and the high-end copper foil with high performance is monopolized by enterprises such as Japan, Korea and the like for a long time. Therefore, the development of high-end copper foil has important strategic significance on national economy and national safety.
At present, the development of high-end copper foil is along the traditional principle of 'fine grain strengthening', namely, the strength of the copper foil is improved by reducing the grain size of the copper foil. Most advanced copper foil enterprises vigorously explore additives capable of refining grains through long-term technology accumulation, and the preparation of high-end electrolytic copper foil is realized.
However, as the grain size decreases, the elongation and conductivity properties of the copper foil are significantly reduced, which makes it difficult to obtain a high-strength copper foil for a wide range of applications. Analysis on a strengthening mechanism shows that when the grain size is refined, the dislocation motion is increased by the resistance of a grain boundary, and the strength is improved; the dislocation motion capability is reduced, and the plastic deformation capability of the material is reduced, so that the elongation rate 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 reduced. In addition, when the grain size is too small (for example, to reach nanometer level), the copper foil becomes unstable, and the grain will grow at room temperature, which reduces the strength, 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, and a circuit board and a current collector, and mainly aims to provide or prepare a high-strength and high-elongation copper foil.
In order to achieve the purpose, the invention mainly provides the following technical scheme:
in one aspect, embodiments of the present invention provide a copper foil, wherein a 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 comprises a plurality of grains.
Preferably, 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: the single crystal grain spans one interface, the single crystal grain spans a plurality of interfaces, and the single crystal grain is only distributed in the layer of the copper foil.
Preferably, the thickness of the interface is 1nm to 1 μm, preferably 5nm to 200nm, and more preferably 10nm to 100 nm.
Preferably, the average minor axis size of the crystal grains ranges from 1nm to 5 μm;
preferably, the distance between the interfaces is 1nm to 100 μm, preferably 10nm to 1 μm, and more preferably 10nm to 500 nm.
Preferably, the interface has a density of 104-109m2/m3Preferably 106-108m2/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 straight interface portion and an undulated interface portion; preferably, the straight interface portion is parallel to the copper foil surface; the equilibrium position of the undulation interface part is parallel to the surface of the copper foil, and the nonequilibrium position shows undulation change (it is to be noted that the definition of the equilibrium position refers to the equilibrium position of the wave).
Preferably, twin structures are included in the grains.
Preferably, the thickness of the copper foil is 1-500 μm, preferably 2-50 μm or 40-300 μm, and more preferably 3-30 μm or 50-200 μm; preferably, when the copper foil has a thickness of 1-4 μm, the copper foil is used for compounding with a carrier to form a carrier copper foil (preferably, the carrier is a conventional copper foil).
Preferably, the tensile strength of the copper foil is 300-900MPa and the elongation is higher than 3% under the room temperature condition.
Preferably, the surface roughness Rz of the copper foil is 0.1 to 3.0 μm.
Preferably, the copper foil is composed entirely of copper element; or the copper foil comprises copper element 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 by using a direct-current electrolytic deposition technology; wherein, in the direct current electrolytic deposition process: the electrolyte used 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 0.5-5 mg/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 2-5 mg/L; preferably, the concentration of the gelatin is 10-40mg/L, the concentration of the collagen is 5-15mg/L, the concentration of the hydroxyethyl cellulose is 4-10mg/L, the concentration of the glucose is 150mg/L, and the concentration of the 2-mercaptobenzimidazole is 1-3 mg/L; preferably, the electrolyte further comprises the following components: 250-350g/L blue vitriol, 20-110g/L H2SO410-50mg/L of HCl and the balance of water.
Preferably, in the direct current electrodeposition process: the current density is controlled to be between 10 and 110A/dm2Preferably 30-80A/dm2More preferably 40 to 70A/dm2Or 50-75A/dm2(ii) a The temperature is controlled to be 10-60 ℃, preferably 40-55 ℃.
Preferably, the distance of the interface in the copper foil, the average minor axis size of crystal grains and the thickness of the interface are regulated and controlled by regulating the temperature of electrolyte, the concentration of one or more components in an additive and the current density in the direct current electrolytic deposition process; preferably, the strength of the copper foil is regulated and controlled by adjusting one or more of the interval of the interface in the copper foil, the average minor axis size of crystal grains, the twin structure occupation ratio (herein, the twin structure occupation ratio refers to the ratio of the volume of all the twin structures in the copper foil sample to the total volume of the copper foil sample), and the thickness of a twin crystal layer; preferably, the surface roughness of the copper foil is adjusted by adjusting one or more of the spacing of the interface, the average minor axis size of the crystal grains, and the thickness of the interface in the copper foil.
Preferably, when the interface thickness is 10nm-1 μm and the interface distance is 10nm-5 μm, the strength of the copper foil is 300-900 MPa;
preferably, when the average minor axis size of the crystal grains is between 10nm and 5 mu m, the strength of the copper foil is 300-900 MPa;
preferably, in the direct current electrolytic deposition process, the prepared copper foil can meet the following requirements by regulating any one or more of the temperature, the current density and the additive concentration: the interface thickness is 10nm-1 μm, the interface distance is 10nm-5 μm, the average minor axis size of the crystal grains is 10nm-5 μm, and the strength of the copper foil is 300-; further preferred is: regulating the temperature to 20-55 ℃; the current density is controlled to be 40-100A/dm2(ii) a The concentration of the additive was adjusted 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 0.5-5 mg/L.
It should be noted that: the distance between the interfaces, the average minor axis size of the crystal grains or the thickness of the interfaces can be reduced by adjusting the temperature, the current density, the additives individually or simultaneously adjusting 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, said copper foil being any of the copper foils described above;
a substrate, the copper foil being located on the substrate;
preferably, the copper foil is bonded to the substrate; further preferably, the copper foil is subjected to a surface treatment before the copper foil is bonded to the substrate.
In yet another aspect, an embodiment of the present invention provides a current collector, wherein the current collector includes any one of the copper foils described 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 a lithium ion battery.
In another aspect, an embodiment of the present invention provides a method for packaging an electronic circuit, wherein, during electronic circuit packaging, a copper foil is deposited in a blind hole of a circuit board by using any one of the above-mentioned methods for preparing a copper foil, so as to implement electronic circuit packaging operations of circuit board wiring and interlayer interconnection.
Compared with the prior art, the copper foil, the preparation method thereof, the circuit board and the current collector have the following beneficial effects:
in one aspect, embodiments of the present invention provide a copper foil, a microstructure of which 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. Here, the copper foil of the above structure exhibits a unique layered structure in a microscopic scale, which is completely different from a conventional copper foil, and is a completely new copper foil. On one hand, in the copper foil provided by the embodiment of the invention, the high-density interface between adjacent layers can effectively block dislocation motion and improve the geometrically necessary dislocation density, so that the strength of the copper foil is improved, and the elongation of the copper foil is also 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 a 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, the average interface pitch of the embodiments of the present invention is 210nm,Interface density of 7X 106m2/m3The copper foil is taken as an example, the room temperature tensile property is 749MPa, the elongation is 5.2%, the strength of the copper foil is far more than the requirements of the IPC-4562 copper foil standard on the tensile strength (276MPa) of an electronic circuit printed board and the lithium ion battery SJ/T11483-.
Further, the interface in the copper foil provided by the embodiment of the invention has higher stability, because mismatch defects such as composition, orientation or lattice distortion generally exist at the interface and the interface has a certain thickness, so that the interface has a higher interface migration energy barrier. Due to the introduction of the interface, nano-scale extremely-small crystal grains can stably exist at room temperature for a long time, 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, the grain size and the like, and the mechanical properties such as tensile strength, elongation and the like are kept stable after the copper foil is placed for 3 months.
Furthermore, in the copper foil provided by the embodiment of the invention, the interface between adjacent layers can enable the growth of crystal grains in the layers to be consistent on one hand, and the rapid growth of local crystal grains is weakened; 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 pitch 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 much lower than the requirement of the ion battery SJ/T11483-. Based on the basic principle that the interface hinders crack propagation so as to improve 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 a copper foil, which is characterized in that the copper foil is deposited by using a direct-current electrolytic deposition technology; specifically, the selected additives not only comprise strong surfactants such as gelatin, collagen and hydroxyethyl cellulose, but also comprise additives with certain reducibility such as glucose and 2-mercaptobenzimidazole; here, under the action of cathodic polarization of a strong surfactant, additives having reducibility are reductively consumed when the surface of the cathode accumulates to some extent (the cathode potential decreases to some extent), and then the cathode potential rises to some extent, and these additives accumulate again. As the additives are accumulated and consumed at the cathode, the electric double layer impedance characteristic of the surface of the cathode and the potential of the cathode show periodic changes, thereby realizing the preparation of the copper foil with the micro-laminated structure.
Further, the preparation method of the copper foil provided by the embodiment of the invention has the advantages of strong controllability and easy performance optimization. Here, the pitch of the interface, the grain size (average minor axis size), the thickness of the interface, and the like in the copper foil can be adjusted by changing parameters such as current density, concentration of each component of the additive, temperature, and the like, thereby achieving further optimization of the copper foil performance. Taking examples 1-3 of the present invention as an example, when the current density is from 50A/dm2Raised to 75A/dm2The average interface distance is reduced from 960nm to 140nm, so that the tensile strength of the copper foil is improved from 538MPa to 846MPa, the elongation at break is improved from 4.2% to 5.3%, and the surface roughness Rz is reduced from 0.96 mu m to 0.4 mu m.
In summary, the copper foil and the preparation method thereof provided by the embodiment of the invention enable the copper foil to have performance advantages of extremely high strength, high elongation, high stability, extremely low surface roughness, high bending 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 and the preparation method thereof have great application prospects in the fields of new energy batteries and electronic circuits.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to make the technical solutions of the present invention practical in accordance with the contents of the specification, the following detailed description is given of preferred embodiments of the present invention with reference to the accompanying drawings.
Drawings
Fig. 1 is a sectional view of the copper foil prepared in example 1 in a thickness direction under a scanning electron microscope.
Fig. 2 is an energy dispersive X-ray spectroscopy (EDS) energy spectrum of the copper foil prepared in example 1 in a 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
To further explain the technical means and effects of the present invention adopted to achieve the predetermined object, the following detailed description of the embodiments, structures, features and effects according to the present invention will be made with reference to the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "an embodiment" refers to not necessarily the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
In recent years, a great deal of research is carried out by the team of the applicant, and the research shows that the mechanical property of the metal material can be obviously enhanced by the layered structure, so that the metal material can have 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 motion, thereby contributing to higher strength; on the other hand, meanwhile, an interface with a certain thickness is often formed between two adjacent layers, and the plastic deformation of the interface is different from that in the adjacent layer, so that a plastic strain gradient is formed, the extra storage of geometrically necessary dislocation is realized, the work hardening performance of the layered structure material is improved, and the elongation of the metal material can be improved.
Based on the research, the high-density interface is innovatively introduced into the copper foil to form a unique microscopic layered structure, and then the copper foil with high strength and high elongation is provided and prepared.
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 distributed parallel to a surface of the copper foil, and an interface having a certain thickness being present between adjacent layers.
The thickness values of the interfaces in the respective 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 μm, preferably 5nm to 200nm, and more preferably 10nm to 100 nm.
The spacing of the interfaces is defined as: distance between centers of two adjacent interfaces on the copper foil. The intervals of the interfaces of all areas in the same copper foil are not completely the same; in the copper foil, the pitch of the interface can be adjusted to a range of 1nm to 100. mu.m, preferably 10nm to 1 μm, and more preferably 10nm to 500 nm. In the copper foil, the variation trend of the distance of the interface along the thickness direction of the copper foil comprises constant, gradually increasing, gradually decreasing, periodic increasing or decreasing 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 104-109m2/m3Preferably 106-108m2/m3More preferably 2X 106-108m2/m3。
The interface of the copper foil is parallel to the surface of the copper foil. From the shape, the interface includes either or both of a flat interface portion, an undulating interface portion. Wherein the straight interface portion refers to an interface portion parallel to the surface of the copper foil; the wavy interface means an interface portion which is a curved surface whose equilibrium position is parallel to the surface of the copper foil but whose local position deviates from the equilibrium position to exhibit wavy variation.
The interface of the copper foil comprises one or two of a continuous interface and a discontinuous interface from the continuity aspect. The continuous interface means that the interface is continuous along the horizontal direction and is not interrupted by crystal grains; a discontinuous interface is one where the interface is discontinuous horizontally, interrupted by grains.
In the 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 grains and the interface includes: a single grain may span one or more interfaces, and a grain may not span an interface and may only be distributed within a single layer. Where a single grain may span one or more interfaces, the number of interfaces that the grain may span may range from 1 to 100, preferably from 1 to 20 or from 15 to 50, more preferably from 1 to 10 or from 20 to 40.
Each layer of the copper foil comprises a plurality of grains (preferably consisting of a plurality of grains), and the shape of the grains can be columnar or isometric; preferably, twin structures may be contained within the grains; more preferably, the average twin lamella thickness of the twin structure is 100nm or less. The average crystal grain of the copper foil has a minor axis size in the range of 1nm to 5 μm, preferably 50nm to 600nm or 500nm to 3 μm, and more preferably 80nm to 300nm or 800nm to 2 μm. The variation tendency of the minor axis dimension of the crystal grains 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 of the embodiment of the present invention is in the range of 1 to 500. mu.m, preferably 2 to 50 μm or 40 to 300. mu.m, and more preferably 3 to 30 μm or 50 to 200. mu.m. Wherein, when the copper foil is 1-4 μm thick, the carrier copper foil can be formed by compounding with a conventional copper foil, so that the carrier copper foil is convenient to transport, process and use. There are various ways of compounding copper foil with conventional copper foil, such as adhesion, mechanical press-fitting, and the like. Alternative carriers include conventional copper foil, aluminum foil, organic films, and the like, with the carrier preferably being set between 6 and 30 microns thick.
The copper foil disclosed by the embodiment of the invention is bonded with a substrate to prepare a conductive circuit for preparing various Copper Clad Laminates (CCLs), Printed Circuit Boards (PCBs) and the like. Wherein, the base plate comprises a hard plate and a soft plate. Before being bonded with a substrate, the copper foil needs to be subjected to surface treatment, including roughening, curing, oxidation resistance, galvanizing treatment, silane coupling agent treatment and the like, so as to improve the performances of peel resistance, oxidation resistance and the like. The copper foil can be widely applied to conventional printed circuit boards and special high-performance printed circuit boards such as high-frequency high-speed circuits, integrated circuit packaging carrier plates, micro circuits (HDIs), high-power large-current circuits, flexible circuits and the like. 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 conducting or signal transmission process 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 resistance effect of the interface of the copper foil on crack propagation contributes to the improvement of the bending resistance and the bending resistance of the circuit board, and the performance advantage has a great positive effect on the improvement of the service environment tolerance and the service life of the flexible circuit board.
The copper foil provided by the embodiment of the invention has a huge prospect in lithium ion batteries. The copper foil can replace the conventional copper foil in the prior art, and is used for manufacturing a current collector of a lithium ion battery in a mode of being bonded with graphite. The copper foil has the advantages that the copper foil is extremely high in tensile strength and high in elongation and stability, so that 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 obviously improved, and the service life of the battery can be prolonged.
In another aspect, embodiments of the present invention provide a method for preparing the copper foil, and specifically, the copper foil may be obtained by using a direct current electrodeposition technique, or may be obtained by using a rolling technique, for example. The preparation method is described by taking a direct-current electrolytic deposition technology as an example, and specifically comprises the following steps:
in the direct current electrolytic deposition process: controlling the current density to be 10-110A/dm2Preferably 30-80A/dm2More preferably 40 to 70A/dm2Or 50-75A/dm2(ii) a The temperature is controlled at 10-60 deg.C, preferably 40-55 deg.C.
The anode and the cathode respectively use a titanium plate with an iridium tantalum coating and a pure titanium plate, and the distance between the anode and the cathode is 5-40mm, preferably 5-15 mm; the solution circulation speed is 1-25m3H, preferably a circulation speed of 2 to 20m3H, more preferably 3 to 10m3H or 5 to 15m3H; the deposition mode is electrolytic bath flat plate deposition or electrolytic copper foil raw foil machine roller deposition. Here, it should be noted that: the electrolytic deposition of the copper foil is generally divided into flat electrolytic deposition and roller deposition, the thickness of the copper foil is generally determined by the length of the flat electrolytic deposition time, and the thickness of the copper foil is generally determined by the speed of the roller electrolytic deposition rotating speed.
In the copper foil preparation method of the embodiment of the invention, the components of the electrolyte comprise 250-350g/L blue vitriod and 20-110g/L H2SO410-50mg/L HCl and purified water. The electrolyte used also contains additives which include not only surfactants but also reducing agents. Wherein, the concentration of the surface active agent gelatin is 1-40mg/L, the concentration of the collagen is 2-30mg/L, and the concentration of the hydroxyethyl cellulose is 1-10 mg/L; the concentration of the reducing agent glucose is 10-300mg/L, and the concentration of the 2-mercaptobenzimidazole is 0.5-5 mg/L. In a preferable 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 2-5 mg/L; in another preferred mode, the concentration of the gelatin is 10-40mg/L, the concentration of the collagen is 5-15mg/L, the concentration of the hydroxyethyl cellulose is 4-10mg/L, the concentration of the glucose is 150-300mg/L, and the concentration of the 2-mercaptobenzimidazole is 1-3 mg/L.
The copper foil of the embodiment of the invention may be composed of all copper elements, or may include one or more elements of silver, zinc, tin, iron, cobalt, nickel, bismuth, carbon, nitrogen, oxygen, sulfur, chlorine, and the like in addition to the copper elements. Among elements composed of the copper foil having a layered structure, the elements added actively are influenced by the purity of the solution and additives. Still further, when composed of a plurality of elements, the variation tendency of the content of copper element along the thickness direction of the copper foil (see arrows 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 distance of the interface, the grain size and the thickness of the interface in the copper foil by adjusting the parameters in the preparation process. The specific method comprises the following steps:
among the methods for reducing the pitch of the interface are, but 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, and the like. The above methods can be used alone or in combination of two or three methods. Methods of increasing the spacing of the interface include, but are not limited to, decreasing the current density; raising the temperature of the electrolyte, and reducing the concentration of one or more additives of gelatin, collagen, hydroxyethyl cellulose, glucose and 2-mercaptobenzimidazole. The above methods can 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, and the like. The above methods can 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; increasing the temperature of the electrolyte; reducing the concentration of one or more additives selected from gelatin, collagen, hydroxyethyl cellulose, glucose and 2-mercaptobenzimidazole, and the like. The above methods can 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 selected from gelatin, collagen, hydroxyethyl cellulose, glucose and 2-mercaptobenzimidazole, and the like. The above methods can 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, and the like. The above methods can be used alone or in combination of two or three methods.
Methods of increasing 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; the occupation ratio of a twin structure is increased; the thickness of the twin lamella 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 interface; increasing the grain size; increasing the thickness of the interface; the twin structure occupation ratio is reduced; the thickness of the twin crystal lamella is increased. The above methods may be used either singly or in combination of two or more.
Methods of reducing the surface roughness of copper foil include, but are not limited to: reducing the spacing of the interfaces; reducing the grain size (average minor axis dimension 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 the copper foil include, but are not limited to: increasing the spacing of the interface; 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 copper foil preparation method can be directly applied to the packaging process of the circuit board, blind hole filling and other operations are carried out according to design requirements, and electronic circuit packaging operations such as circuit board wiring and interlayer interconnection are achieved. Therefore, the copper foil preparation method can be widely applied to the fields of integrated circuit packaging, ultra-large scale integrated circuit chips and the like. The method has the advantages that the interface has stronger defect (vacancy, interstitial atom and the like) absorption capacity and larger barrier effect on the diffusion of atoms, the weldability and the electromigration resistance of an electronic device can be obviously improved, the stability of an electronic circuit is improved, and the service life of the electronic circuit is prolonged.
For further understanding of the present invention, the present invention will be described with reference to the following examples and drawings, but the examples are only for the purpose of further illustrating the features and advantages of the present invention and are not intended to limit the claims of the present invention.
Example 1
In the embodiment, the copper foil is mainly prepared by a direct-current electrolytic deposition method, which comprises the following steps:
1. an electrolytic deposition apparatus: a direct current voltage and current stabilization power supply;
the requirements of the electrolyte used for the electrowinning: preparing copper sulfate solution with concentration of about 300g/L from analytically pure copper sulfate pentahydrate and purified water, and adding analytically pure concentrated sulfuric acid to obtain H2SO4Is 100g/L, and HCl is added to a concentration of 15mg/L to form a base solution for electrodeposition. Then adding additives, specifically, gelatin concentration is 8mg/L, collagen concentration is 10mg/L, hydroxyethyl cellulose concentration is 6mg/L, glucose concentration is 100mg/L, and 2-mercaptobenzimidazole concentration is 2 mg/L.
The anode and the cathode are respectively an iridium tantalum titanium plate and a pure titanium plate.
2. Parameters of the electrolytic deposition process: electroplating copper foil by direct current electrolysis with current density of 50A/dm2(ii) a The cathode and the anode are placed in parallel, the distance is 10mm, and the area ratio of the cathode to the anode is 1: 1; the electrolysis temperature is 53 ℃; electrolyte circulation is carried out by adopting a water pump with the power of 2m3H; the preparation time (deposition time) was 1.5 minutes.
The area of the copper foil prepared by the embodiment is 120X 100mm2The thickness was measured by weighing to be 10.6 μm.
The copper foil prepared in this example was tested by scanning electron microscopy, as shown in fig. 1, indicating that the microstructure of the copper foil had a significant layered structure with distinct interfaces between the layers. The spacing of the interfaces is t in FIG. 11As shown. The interface pitch is not a constant value along the thickness direction of the copper foil, and shows a random variation tendency ranging from 500nm to 2.5 μm, with an average interface pitch of 960 nm. The density of the interface ranged from 4X 105m2/m3To 2X 106m2/m3Density of average interface of 1X 106m2/m3. Wherein the thickness of the interface is t in FIG. 12Shown in the range of 80nm to 230nm, with an average interface thickness of about 150 nm.
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 the area 1-1 in fig. 1, each layer is composed of 1-3 crystal grains, and each crystal grain does not cross the interface and is only distributed in each layer; at the same time, there is a partial region (as shown in region 1-2), and one grain crosses the interface and exists 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 areas 1 to 3 in fig. 1; another portion of the interface is an undulating interface, as shown by regions 1-4 in FIG. 1. And the interfaces at regions 1-3 and 1-4 in fig. 1 are continuous interfaces, representing most of the interface types of the copper foil sample; in addition, there are discontinuous interfaces, which are interrupted by a grain from left to right as shown by the regions 1-5 in fig. 1.
In each layer of the copper foil produced in this example, some of the grains are equiaxed, as shown in regions 1-6 in fig. 1; some grains are columnar with their long axes perpendicular to the interface, as shown in the 1-2 region of fig. 1. The grain size was not constant along the thickness direction of the copper foil, and showed a tendency of random variation, and the average minor axis size of all the grains in the copper foil was 340 nm. In which a significant nano-twin structure is observed in some of the grains, as shown by the regions 1-7 in fig. 1. The copper foil has good toughness, can be completely taken off from the titanium plate, and has no pin hole.
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, indicating the presence of carbon in addition to copper. However, the quantitative analysis results showed that the copper foil contained 100% of copper element (see upper right corner of fig. 2), which is difficult to be quantitatively determined because the content of carbon element is extremely low.
The matte roughness of the copper foil prepared in this example was 0.96 μm in Rz and 0.19 μm in Ra.
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 was cut out with a JDC-0.5-10 precision cutter, the length X width of which was 70mm X12 mm, and the tensile properties were measured with a tensile tester Instron5848 at a tensile rate of 50 mm/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
The copper foil is prepared mainly by a direct current electrolytic deposition method, wherein the difference between the embodiment and the embodiment 1 is as follows:
in this example, the current density was adjusted to increase to 65A/dm2. Meanwhile, the concentration of each additive in the electrolyte adopted in the embodiment is 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 2.5 mg/L. In addition, the time for the electrolytic deposition was 1 minute.
The thickness of the copper foil prepared in this example was measured to be 10.8 μm by a weight method.
The copper foil prepared in this example is tested by a scanning electron microscope, as shown in fig. 4, which shows that the microstructure of the copper foil has an obvious layered structure, most of the crystal grains are elongated columnar crystals, and the columnar crystals span 1-15 interfaces. As shown in the 4-1 region of fig. 4, one columnar crystal spans 8 interfaces.
In comparison with example 1, the present example adjusted the current density and the concentration parameters of each additive, so that the distance of the average interface in the copper foil prepared in the present example (see t in fig. 4)1) Reduced to 210nm and increased average interface density to 5X 106m2/m3Average interface thickness (see t in FIG. 4)2) The reduction was 70 nm. The spacing between the interfaces had a slight tendency to increase in the thickness direction, with an average interface spacing of 193nm near the lower surface (smooth surface) and 216nm near the upper surface (matte surface).
In the copper foil prepared in this example, most of the interfaces are continuous interfaces, but a small portion of non-continuous interfaces also exist, as shown in the region 4-2 in fig. 4. In addition, both a straight interface and a wavy interface exist in the copper foil prepared in this example, wherein the fluctuation (the degree of deviation from the equilibrium position) of the wavy interface is smaller than that of the copper foil of example 1.
The average minor axis size of the crystal grains of the copper foil prepared in the embodiment is reduced to 160nm, the crystal grain size also has a slight increasing trend along the thickness direction, and when the crystal grain is close to the lower surface (smooth surface), the average minor axis size of the crystal grains is 140 nm; near the upper surface (matte), the average minor axis size of the grains was 180 nm. In the copper foil prepared in this example, a part of the crystal grains had a high density of twin boundaries as indicated by approximately vertical boundaries in the region 4-3 of fig. 4.
Compared with example 1, this example achieved reduction in the pitch of the interface, the crystal grain size (average minor axis size of crystal grains), and the thickness of the interface by actively controlling the current density and the concentration of each additive, and the matte roughness of the copper foil was reduced to Rz ═ 0.3 μm and Ra ═ 0.06 μm.
The room temperature tensile test results of the copper foil prepared in this example are shown in fig. 5. Compared with the embodiment 1, the current density and the concentration of each additive are actively regulated and controlled, so that the distance between interfaces, the grain size and the interface thickness are reduced, the tensile strength of the copper foil is improved to 749MPa, and the elongation is 5.2%. In addition, after the copper foil of the embodiment is kept at room temperature for 2 months, the tensile strength and the elongation rate are basically kept unchanged (the change rate is less than 5%), which shows that the copper foil prepared by the embodiment has higher stability.
Example 3
The present example mainly prepares a copper foil by a direct current electrodeposition method, wherein the present example is different from example 1 in that:
this example further increases the current density to 75A/dm2. The concentration of each additive in the electrolyte was adjusted to 16mg/L gelatin concentration, 12mg/L collagen concentration, 2mg/L hydroxyethyl cellulose concentration, and 25 glucose concentration0mg/L, the concentration of 2-mercaptobenzimidazole was 3 mg/L. And, the electrodeposition time was 1 minute.
The thickness of the copper foil prepared in this example was measured to be 12 μm by a weight method.
The copper foil prepared in this example is tested by a scanning electron microscope, as shown in fig. 6, which shows that the microstructure of the copper foil prepared in this example has an obvious layered structure, most of the crystal grains are elongated columnar crystals, and the columnar crystals span 1-35 interfaces. As shown in the 6-1 region in fig. 6, one columnar crystal spans 21 interfaces.
Compared with example 1, the present example enables the pitch of the average interface in the copper foil to be adjusted by controlling the process parameters (see t in fig. 6)1) Further reduction to 140nm and further increase of the average interface density to 7X 106m2/m3Average thickness of the interface (see t in FIG. 6)2) Further down to 60 nm. The distance between the interfaces had a slight tendency to increase in the thickness direction, with the average interface distance being 120nm near the lower surface (smooth surface) and 183nm near the upper surface (matte surface).
The interface of the copper foil prepared in this example is mostly a continuous interface, and there are some discontinuous interfaces near the lower surface of the copper foil (see the lower side of fig. 6). In addition, in the copper foil prepared in this embodiment, a straight interface and a wave interface exist simultaneously, and the interface below fig. 6 is mostly the wave interface, and the wave property is higher than that of other areas,
the average minor axis size of the grains in the copper foil prepared in this example was 300nm, which is slightly lower than the average grain size of example 1. The grain size in this example also has a slight tendency to increase along the thickness direction, and the average minor axis size of the grains is 210nm near the lower surface (smooth surface) and 350nm near the upper surface (matte surface).
Compared with example 1, in this example, by actively controlling the current density and the concentration of each additive in the electrolyte, the interface pitch and the interface thickness were greatly reduced, and the matte roughness of the copper foil was reduced to Rz of 0.4 μm and Ra of 0.08 μm.
The room temperature tensile test results of the copper foil prepared in this example are shown in fig. 7. Compared with the embodiment 1, the embodiment has the advantages that the current density and the concentration of each additive are actively regulated and controlled, so that the distance between the interfaces and the thickness of the interfaces are greatly reduced, the tensile strength of the copper foil is further improved to 846MPa, and the breaking elongation is improved to 5.3%.
Comparative example 1
The mechanical property requirements of the printed board metal foil standard IPC-4562 on the standard electrolytic copper foil with the thickness of 17 mu m comprise: the tensile strength is more than or equal to 207MPa, and the elongation is more than or equal to 2 percent; when the tensile strength of the rolled and forged copper foil with the thickness of 17 mu m is more than or equal to 345MPa, the elongation is more than or equal to 0.5 percent.
Comparative example 2
The requirements of the electrolytic copper foil industry standard SJ/T11483-2014 for the lithium ion battery comprise: LBEC-01 model, when the thickness is 8-20 μm, the tensile strength is not less than 294MPa, the elongation is not less than 3%, and the roughness Rz of the rough surface is not more than 3.0 μm when measured at room temperature (23 ℃); LBEC-02 with a thickness of 8 μm, 9 μm, 10 μm and 12 μm, a tensile strength of not less than 300MPa, an elongation of not less than 2.5%, a matte roughness Rz of not more than 3.0 μm, 4.0 μm, 4.5 μm and 5.0 μm, measured at room temperature (23 ℃); LBEC-03 type, 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%, and the roughness Rz of the rough surface is less than or equal to 4.0 μm, 4.5 μm and 5.0 μm when measured at room temperature (23 ℃); LBEC-04 model, when the thickness is 10 μm and 12 μm, 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 5.0 μm and 6.0 μm when measured at room temperature (23 ℃).
Comparative example 3
Research by Hotan et al (Master academic thesis of Nanchang university, 2011) shows that the process parameters are as follows: the temperature is 60 ℃, and the current density is 65A/dm2The concentration of copper ions is 80-90g/L (the equivalent of blue vitriol is 312-350g/L), H2SO4The concentration of (b) is 120-130g/L, and the concentration of HCl is 30-40mg/L, no additive is used. The prepared copper foil has the thickness of 18 mu m, the interior of the copper foil is of a common polycrystalline structure, the grain size of the copper foil is in a micron order, the tensile strength of the copper foil is about 380MPa, the elongation of the copper foil is about 5.5 percent, and the surface roughness R isz＝5.2μm。
Through comparison, the tensile strength of the copper foil prepared by the embodiment of the invention is far higher than the requirements of the 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 is closely related to the micro-laminated structure 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 meet the development trend of high capacity, high safety, high stability and low cost of a high-performance lithium ion battery. Meanwhile, the copper foil and the preparation method thereof prepared by the embodiment of the invention are also suitable for circuit board manufacture and electronic circuit packaging respectively, and particularly have greater application potential in flexible circuit boards and high-frequency high-speed circuit boards, thanks to the enhancement effect of the high-density interface on the deflection and bending resistance, the stabilization effect on microstructures and mechanical properties, and the effect on reducing surface roughness. In addition, the copper foil prepared by the embodiment of the invention has large 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 distance of the interface of the copper foil, the density of the interface, the grain size and the like by actively regulating and controlling the process parameters such as the current density, the additive concentration, the temperature and the like, thereby further optimizing the method of the mechanical property and the surface roughness of the copper foil and providing technical support for preparing and manufacturing the copper foil with the laminated structure 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 merely illustrative of the technical ideas and features of the present invention, and are intended to enable one skilled in the art to understand the contents of the present invention and implement the present invention, and the protection scope of the present invention is not limited thereby. Effective changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. A copper foil, characterized in that 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 comprises a plurality of grains.
2. The copper foil of claim 1,
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: the single crystal grain spans one interface, the single crystal grain spans a plurality of interfaces, and the single crystal grain is only distributed in the layer of the copper foil; and/or
The thickness of the interface is 1nm-1 μm, preferably 5nm-200nm, and more preferably 10nm-100 nm; and/or
The distance between the interfaces is 1nm-100 μm, preferably 10nm-1 μm, and more preferably 10nm-500 nm; and/or
The interface has a density of 104-109m2/m3Preferably 106-108m2/m3；
The interface comprises one or two of a continuous interface and a discontinuous interface; and/or
The interface comprises one or two of a straight interface part and a wavy interface part; preferably, the straight interface portion is parallel to the copper foil surface; the equilibrium position of the wave interface part is parallel to the surface of the copper foil, and the non-equilibrium position of the wave interface part shows wave-shaped change; and/or
The crystal grains comprise twin crystal structures; and/or
The average minor axis size range of the crystal grains is 1nm-5 mu m; and/or
The thickness of the copper foil is 1-500 μm, preferably 2-50 μm or 40-300 μm, and more preferably 3-30 μm or 50-200 μm; preferably, when the thickness of the copper foil is 1-4 μm, the copper foil is used for compounding with a carrier to form a carrier copper foil; and/or
Under the condition of room temperature, the tensile strength of the copper foil is 300-900MPa, and the elongation is higher than 3%; and/or
The surface roughness Rz of the copper foil is 0.1-3.0 μm.
3. The copper foil of claim 1,
the copper foil is composed of copper elements; or
The copper foil comprises copper elements with the mass fraction of not less than 90%; further comprises one or more elements of silver, zinc, tin, iron, cobalt, nickel, bismuth, carbon, nitrogen, oxygen, sulfur and chlorine.
4. The method of making the copper foil of any of claims 1-3, wherein the copper foil is deposited using a direct current electrodeposition technique; wherein the content of the first and second substances,
in the direct current electrolytic deposition process: the electrolyte used contains additives; wherein the additive comprises gelatin, collagen, hydroxyethyl cellulose, glucose, and 2-mercaptobenzimidazole.
5. The method for producing a copper foil according to claim 4, 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 0.5-5 mg/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 2-5 mg/L;
preferably, the concentration of the gelatin is 10-40mg/L, the concentration of the collagen is 5-15mg/L, the concentration of the hydroxyethyl cellulose is 4-10mg/L, the concentration of the glucose is 150mg/L, and the concentration of the 2-mercaptobenzimidazole is 1-3 mg/L;
preferably, the electrolyte further comprises the following components: 250-350g/L blue vitriol, 20-110g/L H2SO410-50mg/L of HCl and the balance of water.
6. The method for preparing copper foil according to claim 4 or 5, wherein in the DC electrodeposition process:
the current density is controlled to be between 10 and 110A/dm2Preferably 30-80A/dm2More preferably 40 to 70A/dm2Or 50-75A/dm2；
The temperature is controlled to be 10-60 ℃, preferably 40-55 ℃.
7. The method for preparing copper foil according to any one of claims 4 to 6, wherein the distance between the interfaces, the average minor axis size of the crystal grains, and the thickness of the interfaces in the copper foil are controlled by adjusting the temperature of the electrolyte, the concentration of one or more components of the additives, and the current density during the DC electrodeposition;
preferably, the strength of the copper foil is regulated and controlled by adjusting one or more of the distance of an interface in the copper foil, the average minor axis size of crystal grains, the proportion of a twin crystal structure and the thickness of a twin crystal sheet layer;
preferably, the surface roughness of the copper foil is adjusted by adjusting one or more of the interval of the interface in the copper foil, the average minor axis size of crystal grains and the thickness of the interface;
preferably, when the interface thickness is 10nm-1 μm and the interface distance is 10nm-5 μm, the strength of the copper foil is 300-900 MPa;
preferably, when the average minor axis size of the crystal grains is between 10nm and 5 mu m, the strength of the copper foil is 300-900 MPa;
preferably, in the direct current electrolytic deposition process, the prepared copper foil can meet the following requirements by regulating any one or more of the temperature, the current density and the additive concentration: the interface thickness is 10nm-1 μm, the interface spacing is 10nm-5 μm, the average minor axis size of the crystal grains is 10nm-5 μm, and the strength of the copper foil is 300-900 MPa;
further preferably, the temperature is regulated and controlled to be 20-55 ℃;
further preferably, the current density is controlled to be 40-100A/dm2；
Further preferably, the concentration of the additive is regulated 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 0.5-5 mg/L.
8. A circuit board, comprising:
a copper foil according to any one of claims 1 to 3;
a substrate, the copper foil being located on the substrate;
preferably, the copper foil is bonded to the substrate; further preferably, the copper foil is subjected to surface treatment before being bonded to the substrate.
9. A current collector, characterized in that it comprises the copper foil according to any one of claims 1 to 3;
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 a lithium ion battery.
10. A method for packaging an electronic circuit, characterized in that, in the electronic circuit packaging, a copper foil is deposited in blind holes of a circuit board by using the copper foil preparation method of any one of claims 4 to 7, so as to realize the electronic circuit packaging operation of circuit board wiring and interlayer interconnection.
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