Preparation method of nano-domain reinforced ultrathin copper foil

Abstract

The invention relates to the technical field of electro-deposition nano materials, in particular to a preparation method of nano-domain reinforced ultrathin copper foil, which comprises the following steps: 1) adding copper salt into a solvent, adding sulfuric acid after copper salt particles are fully dissolved, supplementing the solvent to prepare a basic plating solution, adding an additive into the basic plating solution, and uniformly mixing to obtain an electrolyte; 2) selecting a copper plate as an anode and a titanium plate as a cathode, and performing ultrasonic treatment; (3) pulse electrodeposition is started, in the half cycle of high current density and high surfactant concentration, nanodomains widely appear on the titanium plate, in the other half cycle of low current density, other crystal grains continuously become larger and surround the nanodomains, and copper foil with the ultra-thin thickness is formed on the titanium plate; and 4) after the pulse electrodeposition is completed, removing the copper foil with ultra-thin thickness from the titanium plate by using a mechanical method to obtain the nano-domain copper foil. The method is convenient to operate, instruments and equipment are simple, and the prepared nano-domain copper foil has excellent yield strength and ductility.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrodeposited nanomaterials, and particularly relates to a method for preparing a nanocrystalline domain-strengthened ultra-thin copper foil. Background Art

[0002] Pure metal copper foil is widely used in fields such as electronic devices, microelectronics packaging, battery manufacturing, and thermal management systems due to its excellent electrical conductivity, thermal conductivity, and good processability. As electronic devices develop towards thinner, lighter, and higher-performance directions, the performance requirements for copper foil are gradually increasing. On the premise of maintaining high electrical conductivity, higher strength and elongation are also required. Ultra-thin metal copper foil (usually with a thickness between several micrometers and more than ten micrometers) has become an important direction for current research and development due to its special requirements in emerging fields such as high-density integrated circuits and flexible electronic devices. How to prepare an ultra-thin copper foil with high strength, high elongation, and high electrical conductivity has become a key challenge in technological development.

[0003] Traditionally, alloying can significantly improve the strength of copper materials, but this method often significantly reduces the electrical conductivity of copper due to the introduction of a second phase or the change of crystal structure, thus unable to meet the performance requirements of conductive materials. Therefore, for copper foil, its strengthening means can only start from the design of grain tissue structure, and improve the strength and elongation by optimizing the microstructure while trying to maintain its electrical conductivity.

[0004] Currently, there are mainly two ways for strengthening means based on the design of grain tissue structure for pure copper materials: one is the post-processing means, that is, through plastic deformation processes such as spinning, forging, pre-stretching, or high-pressure torsion, introducing a large area of dislocation structure or constructing an ultra-fine grain layer on the surface, thereby significantly improving the strength of the material. However, this method is not applicable to the processing of copper foil with a micron thickness. Ultra-thin copper foil is prone to warping, fracture, or uneven performance during the processing, and the control accuracy of mechanical processing on the microstructure is relatively low, unable to meet the high-performance requirements of ultra-thin copper foil. The other is to conduct grain structure design during the electrodeposition process of ultra-thin copper foil, that is, through the introduction of microstructures such as nano-twins during the electrodeposition process, attempting to improve the strength of copper foil while maintaining the electrical conductivity. For example, the strength is increased by introducing a high density of twin boundaries, but due to the limited thickness of the twin layer, it is difficult to effectively control, resulting in plastic limitation of ultra-thin copper foil under large strain conditions and insufficient elongation. In addition, it is extremely difficult to achieve the arrangement of an ordered nano-twin structure in industrially produced copper foil, resulting in difficult realization of twin boundary strengthening. In summary, the current strengthening strategies have significant limitations when applied to ultra-thin copper foil and are difficult to meet the requirements of high strength, high elongation, and high electrical conductivity simultaneously.

[0005] To solve this problem, the present invention proposes a design scheme for ultra-thin copper foil based on nanocrystalline domain strengthening. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing a nanocrystalline domain-strengthened ultra-thin copper foil. In this method, nanocrystalline domains of copper elements are introduced into the grains of the copper foil. By controlling the density and distribution of the domains in the copper foil, the movement of dislocations is effectively hindered, and their interaction and accumulation are promoted during subsequent dislocation activities, thereby achieving an improvement in the yield strength and elongation rate of the nanocrystalline domain copper foil and avoiding the sacrifice of both strength and ductility.

[0007] This method is easy to operate, and the equipment is simple. The prepared nanocrystalline domain copper foil has excellent yield strength and elongation rate. By optimizing the additives and controlling the current density, the preparation of the nanocrystalline domain copper foil is realized to solve the problems raised in the above-mentioned background technology.

[0008] To achieve the above object, the technical solution of the present invention is realized as follows. A method for preparing a nanocrystalline domain-strengthened ultra-thin copper foil comprises the following steps:

[0009] 1) Add copper salt to a solvent. After the copper salt particles are fully dissolved, add sulfuric acid, and then supplement the solvent to prepare a basic plating solution. Add an additive to the basic plating solution and mix well to obtain an electrolyte;

[0010] 2) Select a copper plate as the anode and a titanium plate as the cathode, and perform ultrasonic treatment to remove impurities on the surface of the substrate;

[0011] 3) Perform pulse electroplating:

[0012] 31) Insert the treated cathode and anode into the prepared electrolyte, and then perform electroplating using a pulsed current with alternating high and low current densities; the pulsed current adopts a repetitive square wave;

[0013] 32) During the electroplating process, simultaneously compound one or several of 2-mercaptobenzothiazoline, 3,5-dinitrobenzoic acid, 4,6-dimethyl-2-mercaptopyrimidine, polyethylenepolyamine, and 1,4-butenediol into a mixture, and inject it into the electrolyte at a certain concentration as a grain refiner to help induce nanoscale domains in the copper foil;

[0014] 33) Under the combined action of the high-current-density half-cycle period and the high-concentration surfactant in the electrolyte, nanocrystalline domains will widely appear in the deposited copper foil;

[0015] 34) In the other half-cycle period of the low current density, the remaining grains in the copper foil continue to grow and enclose the nanocrystalline domains inside; when the thickness of the copper foil reaches the set target value, stop the pulse electroplating. At this time, an ultra-thin copper foil has been formed on the titanium plate;

[0016] 4) After the pulse electro - deposition is completed, the copper foil is removed from the titanium plate, and an ultra - thin copper foil with a nanocrystalline domain structure can be obtained.

[0017] Furthermore, the copper salt in step 1) is copper sulfate; the solvent is deionized water or ultrapure water; the additive is one or a mixture of hydrochloric acid, boric acid, soluble saccharin, sodium lauryl sulfate, sodium poly - dithiopropanesulfonate, polyethylene glycol, 2 - mercapto - thiazoline, 3,5 - dinitrobenzoic acid, 4,6 - dimethyl - 2 - mercaptopyrimidine, polyethylenepolyamine, and 1,4 - butanediol; the surfactant in step 3) includes sodium lauryl sulfate, sodium poly - dithiopropanesulfonate, and sodium dodecyl sulfate.

[0018] Furthermore, the concentration of copper ions in the electrolyte is 60 - 80 g / L, the concentration of chloride ions is 30 - 50 mg / L, the concentration of boric acid is 40 - 60 g / L, the concentration of soluble saccharin is 2 - 3 g / L, the concentration of sodium lauryl sulfate is 0.2 - 0.5 g / L, the concentration of 1,4 - butanediol is 1 - 2 g / L, the concentration of PEG is 30 - 60 ppm, the concentration of SPS is 25 - 80 ppm, the concentration of 2 - mercapto - thiazoline is 20 - 80 mg / L, the concentration of 3,5 - dinitrobenzoic acid is 10 - 90 mg / L, the concentration of 4,6 - dimethyl - 2 - mercaptopyrimidine is 100 - 450 mg / L, and the concentration of polyethylenepolyamine is 20 - 80 mg / L.

[0019] Furthermore, the pH value of the electrolyte in step 1) is 3.4 - 4; the temperature is 45 - 55 °C.

[0020] Furthermore, both the copper plate and the titanium plate in step 2) are annealed and polished, and are respectively polished with sandpapers of 400#, 800#, 1000#, and 2000#.

[0021] Furthermore, in step 3), the pulse electro - deposition uses a repetitive square wave with a width of 5 - 10 ms, a high current density of 20 - 30 A / dm², and a low current density of 1 - 5 A / dm².

[0022] Furthermore, the component of the grain refiner in step 3) is a mixture prepared by compounding one or several of 2 - mercapto - thiazoline with a concentration of 20 - 80 mg / L, 3,5 - dinitrobenzoic acid with a concentration of 10 - 90 mg / L, 4,6 - dimethyl - 2 - mercaptopyrimidine with a concentration of 100 - 450 mg / L, polyethylenepolyamine with a concentration of 20 - 80 mg / L, and 1,4 - butanediol with a concentration of 0.5 - 1.2 g / L, and is injected into the electrolyte at a concentration of 0.2 - 1 g / L.

[0023] Further, the nanodomains in step 3) are only formed inside the copper grains, and the average diameter of the nanodomains is about 7 nm, accounting for only 2-3% of the total volume of the copper grains; in step 4), the ultra-thin copper foil is peeled off after the thickness reaches about 5-30 μm.

[0024] Further, the nanocrystalline domains are also elemental Cu, rather than second-phase particles.

[0025] Further, the thickness of the ultra-thin nanocrystalline domain copper foil obtained in step 4) is 6 μm, its yield strength is about 580.3 MPa, the tensile strength is 607.9 MPa, and the uniform elongation is 7.12%.

[0026] The beneficial effects of the present invention are embodied in:

[0027] The method provided by the present invention introduces nanocrystalline domains of copper elements inside the copper grains. By controlling the density and distribution of the domains in copper, the movement of dislocations is effectively hindered, and their interaction and accumulation are promoted during subsequent dislocation activities, thereby achieving the effect of improving the yield strength and elongation of the nanodomain copper and avoiding the sacrifice of both strength and elongation. Description of the Drawings

[0028] Figure 1 is a transmission electron microscope photograph of a conventional copper foil;

[0029] Figure 2 is a transmission electron microscope photograph of a nanocrystalline domain copper foil;

[0030] Figure 3 is a high-magnification transmission electron microscope photograph of a nanocrystalline domain copper foil;

[0031] Figure 4 is a transmission electron microscope photograph of a copper foil by pulse electrodeposition + conventional electroplating solution;

[0032] Figure 5 is a transmission electron microscope photograph of a copper foil by special electroplating solution + direct current electrodeposition;

[0033] Figure 6 is a tensile stress-strain curve graph of four ultra-thin copper foils. Detailed Embodiments

[0034] Hereinafter, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings of the specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] Example 1

[0036] A preparation method of a nanocrystalline domain strengthened ultra-thin copper foil

[0037] 1. Preparation and pretreatment of the electrolyte

[0038] Take deionized water and add it to a beaker. While stirring continuously, add copper sulfate pentahydrate. After the particles are fully dissolved, add sulfuric acid to obtain a mixed solution of sulfuric acid and copper sulfate. Add an appropriate amount of activated carbon, mix well, remove organic impurities in the plating solution, filter the impurities thoroughly, add deionized water to make the solution reach the required volume to obtain the basic plating solution. Then add one or several of hydrochloric acid, 2-mercaptobenzothiazoline, 3,5-dinitrobenzoic acid, 4,6-dimethyl-2-mercaptopyrimidine, polyethylenepolyamine, 1,4-butenediol, PEG, and SPS to the basic plating solution, mix the ratios evenly to obtain the electrolyte, and keep the pH value of the electrolyte at 3.4 - 4 and the temperature at 45 - 55 °C.

[0039] The electrolyte of the present invention introduces an additive combination (such as 2-mercaptobenzothiazoline, 3,5-dinitrobenzoic acid, 4,6-dimethyl-2-mercaptopyrimidine, polyethylenepolyamine, PEG, and SPS, etc.). Among them, SPS provides a stronger grain refinement effect; PEG acts as a surfactant, improving the surface flatness and coating quality; polyethylenepolyamine and 1,4-butenediol perform excellently in controlling grain nucleation and growth, ensuring the uniform distribution of copper domains in the matrix; 3,5-dinitrobenzoic acid and 4,6-dimethyl-2-mercaptopyrimidine optimize the inhibitory effect on the electrode reaction, further promoting grain uniformity and domain formation.

[0040] These optimizations enable the nanocrystalline domains to have a higher density and a more stable distribution during the electro-deposition process.

[0041] 2. Treatment of the anode and cathode plates

[0042] Select a polished copper plate as the anode, and use a titanium plate polished with 400#, 800#, 1000#, and 2000# sandpapers as the cathode, and perform ultrasonic treatment;

[0043] 3. Pulse electro-deposition

[0044] High current density stage: Set the current density to 40 - 50 A / dm 2 , with a duration of 5 - 10 ms, used to generate nanocrystalline domains in the matrix.

[0045] Low current density stage: Set the current density to 1 - 5 A / dm 2 , with a duration of 10 - 20 ms, used to promote the uniform growth of matrix grains and the encapsulation of nanocrystalline domains.

[0046] During the entire pulse electro - deposition process, the degree of grain refinement was improved by rapidly generating a high - density of nanocrystalline domains during the high - current - density stage; during the low - current - density stage, the slow growth of existing grains and the encapsulation of nanocrystalline domains were promoted, making the overall structure more uniform. Compared with traditional direct - current electro - deposition or a single - current mode, the pulse mode formed more crystal nuclei during the high - current stage and avoided the rapid growth of grains at the same time. The low - current stage enhanced the mutual fusion and connection of grains, improving the mechanical properties (such as elongation and strength) of the copper foil. The combination of the two greatly improved the grain structure distribution and uniformity, endowing the copper foil with excellent strength and ductility.

[0047] The deposition thickness of the copper foil: It is controlled between 5 - 30 μm.

[0048] In addition, during the high - current - density half - cycle, by adjusting the surfactant concentration, the interfacial tension of the electrolyte can be adjusted, optimizing the growth environment of copper grains during electro - deposition, ensuring the refinement and uniformity of copper - grain size, promoting the nucleation and widespread appearance of nanocrystalline domains, and forming normal - sized nanometer - scale copper grains around them. During the other low - current - density half - cycle, the normal nanometer - scale copper grains grow normally and surround the nanodomains.

[0049] 4. Post - treatment

[0050] The electro - deposited copper foil is peeled off from the cathode substrate, and the copper foil is placed in the air for natural aging for 24 - 72 h to remove internal stress and improve grain uniformity.

[0051] According to the above method, in specific implementation, the thickness of the prepared nanocrystalline - domain copper foil can be controlled between 5 - 30 μm. The nanocrystalline domains are mainly formed inside the copper grains, with an average diameter of about 7 nm, accounting for only 2.4% of the total volume. These nanocrystalline domains are also elemental Cu, rather than second - phase particles. Among them, the yield strength of the 6 - μm nanocrystalline - domain copper foil is 580.3 MPa, the tensile strength is 607.9 MPa, and the uniform elongation is 7.12%.

[0052] Example 2

[0053] The yield strength, tensile strength, and elongation of the nanocrystalline - domain copper foil prepared in Example 1 were compared with those of a conventional electro - deposited copper foil, a copper foil prepared by a specific formula + direct - current electro - deposition, and a copper foil prepared by a conventional formula + pulse electro - deposition, obtaining Table 1.

[0054] Table 1 Yield strength, tensile strength, and elongation of four types of copper foils

[0055]

[0056] As can be seen from Table 1 above:

[0057] The first group of data (nanocrystalline domain copper foil): Obtained by using the electrolyte and pulse electro-deposition process of the present invention (i.e., the combination of high and low currents).

[0058] The second group of data (conventional electro-deposited copper foil): Obtained by using a conventional electrolyte and direct current deposition method.

[0059] The third group of data (specific formula + direct current electro-deposited copper foil): Using the electrolyte of the present invention, but obtained by direct current deposition method.

[0060] The fourth group of data (conventional formula + pulse electro-deposited copper foil): Using a conventional electrolyte and obtained by pulse deposition method.

[0061] As Figures 1-5 shown,

[0062] The purpose of setting the five groups of photos is to compare the microscopic structural characteristics of copper foils under different processes in Example 2 through transmission electron microscope images. The result analysis is as follows:

[0063] Figure 1 (Conventional copper foil): The grains are coarse and unevenly distributed.

[0064] Figure 2 (Nanocrystalline domain copper foil): Shows uniformly distributed nanocrystalline domains, and the grain size is significantly refined.

[0065] Figure 3 (High magnification transmission): Further shows the internal structure of the nanocrystalline domains. The average diameter of the domains is about 7 nm, and the distribution density is high.

[0066] Figure 4 (Pulse + conventional electrolyte): Partially refined, but no obvious nanocrystalline domains are formed, and the structure is uneven.

[0067] Figure 5 (Special electrolyte + direct current): The grain refinement is insufficient, and the formation of nanocrystalline domains is insufficient.

[0068] From Figures 1-5 the comparison, it can be seen that: Compared with other processes, the present invention forms uniformly distributed nanocrystalline domains through the combination of pulse electro-deposition and optimized electrolyte, significantly improving the performance of the copper foil.

[0069] As Figure 6 shown: The comparison results of the stress-strain curves of the above four copper foils show that:

[0070] 1 Nanocrystalline domain copper foil: Exhibits the highest yield strength (580.3 MPa) and tensile strength (607.9 MPa), and a relatively high elongation (7.12%), indicating that it still maintains good plasticity while having high strength.

[0071] 2 Conventional electroplated copper foil: It has the lowest strength but the highest elongation rate (10.42%), indicating that the grains are relatively coarse and cannot effectively hinder the movement of dislocations.

[0072] 3 Copper foil with specific formula + direct current electroplating: The strength has increased, but the elongation rate has decreased, indicating that the grain refinement is limited.

[0073] 4 Copper foil with conventional formula + pulse electroplating: The strength and elongation rate are between those of conventional electroplated copper foil and nanocrystalline domain copper foil.

[0074] From Figure 6 it can be seen that the nanocrystalline domain copper foil prepared by the present invention achieves the best balance in strength and ductility, and is superior to the copper foils prepared by other processes.

[0075] Through the above embodiments, it can be seen that the method provided by the present invention realizes the synergistic optimization of strength and elongation rate by introducing a uniformly distributed nanocrystalline domain structure into the matrix of the ultra-thin copper foil:

[0076] 1. The strengthening effect of nanocrystalline domains. Nanocrystalline domains play a strengthening role by hindering the movement of dislocations. Due to the small size of the nanodomains (average diameter is about 7 nm), the dislocations in motion will be effectively blocked when passing through the nanocrystalline domains, similar to the Orowan effect in precipitation strengthening. At the same time, the boundaries of the nanocrystalline domains also further limit the penetration and slip of dislocations.

[0077] 2. The enhancing effect of nanocrystalline domains on the elongation rate. Nanocrystalline domains not only hinder the movement of dislocations but also act as dislocation sources and dislocation traps. The boundaries of the nanocrystalline domains provide more space and conditions for the multiplication and entanglement of dislocations, thus significantly improving the dislocation storage capacity and enhancing the strain hardening ability. This enables the copper foil to continuously undergo uniform plastic deformation under high stress.

[0078] The method provided by the present invention uses the pulse electroplating process and combines fine parameter regulation to realize the distribution design of nanocrystalline domains in the ultra-thin copper foil, achieving both high strength and avoiding the decrease in ductility caused by the rapid annihilation of dislocations, breaking through the technical bottleneck in traditional copper foil processing, and providing a new solution for the preparation of high-performance ultra-thin copper foils.

[0079] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing nanocrystalline domain reinforced ultra-thin copper foil, characterized in that: Here are the steps: 1) adding copper salt to a solvent, adding sulfuric acid after the copper salt particles are fully dissolved, and then adding the solvent to prepare a basic plating solution, and adding additives to the basic plating solution and mixing to obtain an electrolyte; 2) Select a copper plate as the anode and a titanium plate as the cathode, and perform ultrasonic treatment; 3) Pulse electrodeposition: 31) inserting the treated cathode and anode into the prepared electrolyte, and then using pulse current with high current density and low current density alternately for electrodeposition; 32) Injecting a grain refiner into the electrolyte simultaneously during the electrodeposition process; 33) Under the combined effect of high current density half-cycle and surfactant in the electrolyte, nanocrystalline domains appear extensively in the deposited copper foil; 34) In another half cycle of low current density, the remaining grains in the copper foil continue to grow and surround the nanocrystalline domains inside; when the thickness of the copper foil reaches the set target value, the pulse electrodeposition is stopped to form a copper foil with ultra-thin thickness on the titanium plate; 4) After the pulse electrodeposition is completed, the copper foil is removed from the titanium plate to obtain an ultra-thin copper foil with a nanocrystalline domain structure.

2. The method for preparing a nano-domain reinforced ultra-thin copper foil according to claim 1, characterized in that: The copper salt in step 1) is copper sulfate; the solvent is deionized water or ultrapure water; the additive is one or a mixture of hydrochloric acid, boric acid, soluble saccharin, sodium lauryl sulfate, sodium polydisulfide propane sulfonate and polyethylene glycol, 2-mercaptothiazoline, 3,5-dinitrobenzoic acid, 4,6-dimethyl-2-mercaptopyrimidine, polyethylene polyamine and 1,4-butene diol; the surfactant in step 3) includes sodium lauryl sulfate, sodium polydisulfide propane sulfonate and sodium dodecyl sulfate.

3. The method for preparing a nano-domain reinforced ultra-thin copper foil according to claim 2, characterized in that: The electrolyte has a copper ion concentration of 60-80 g / L, a chloride ion concentration of 30-50 mg / L, a boric acid concentration of 40-60 g / L, a soluble saccharin concentration of 2-3 g / L, a sodium lauryl sulfate concentration of 0.2-0.5 g / L, a 1,4-butene diol concentration of 1-2 g / L, a PEG concentration of 30-60 ppm, an SPS concentration of 25-80 ppm, a 2-mercaptothiazoline concentration of 20-80 mg / L, a 3,5-dinitrobenzoic acid concentration of 10-90 mg / L, a 4,6-dimethyl-2-mercaptopyrimidine concentration of 100-450 mg / L, and a polyethylene polyamine concentration of 20-80 mg / L.

4. The method for preparing a nano-domain reinforced ultra-thin copper foil according to claim 1, characterized in that: The pH value of the electrolyte in step 1) is 3.4-4; the temperature is 45-55°C.

5. The method for preparing a nano-domain reinforced ultra-thin copper foil according to claim 1, characterized in that: The copper plate and titanium plate in step 2) are annealed and polished, and are polished with 400#, 800#, 1000# and 2000# sandpapers respectively.

6. The method for preparing a nano-domain reinforced ultra-thin copper foil according to claim 1, characterized in that: The pulse electrodeposition in step 3) uses a repetitive square wave with a width of 5 to 10 ms and a high current density of 20 to 30 A / dm 2 , low current density is 1~5A / dm 2 .

7. The method for preparing a nano-domain reinforced ultra-thin copper foil according to claim 1, characterized in that: The grain refiner in step 3) is composed of one or more of 2-mercaptothiazoline at a concentration of 20 to 80 mg / L, 3,5-dinitrobenzoic acid at a concentration of 10 to 90 mg / L, 4,6-dimethyl-2-mercaptopyrimidine at a concentration of 100 to 450 mg / L, polyethylene polyamine at a concentration of 20 to 80 mg / L, and 1,4-butene diol at a concentration of 0.5 to 1.2 g / L, which are compounded into a mixture and injected into the electrolyte at a concentration of 0.2 to 1 g / L.

8. The method for preparing a nano-domain reinforced ultra-thin copper foil according to claim 1, characterized in that: The nanodomains in step 3) are formed only inside the copper grains, and the average diameter of the nanodomains is about 7nm, accounting for only 2-3% of the total volume of the copper grains; in step 4), the ultra-thin copper foil is peeled off after the thickness reaches about 5-30μm.

9. The method for preparing a nano-domain reinforced ultra-thin copper foil according to claim 8, characterized in that: The nanocrystalline domains are also elemental Cu, rather than second phase particles.

10. The method for preparing a nano-crystal domain reinforced ultra-thin copper foil according to claim 8, characterized in that: The ultra-thin nanocrystalline copper foil obtained in step 4) has a thickness of 6 μm, a yield strength of about 580.3 MPa, a tensile strength of 607.9 MPa, and a uniform elongation of 7.12%.

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