Graphene composite copper heat-conducting film and preparation method thereof

Abstract

The application provides a graphene composite copper heat-conducting film and a preparation method thereof, and comprises the following steps: adding graphene oxide into water and stirring to obtain graphene oxide slurry; adding copper sulfate solution into the graphene oxide slurry to obtain graphene oxide / copper sulfate composite slurry; coating the graphene oxide / copper sulfate composite slurry on a substrate; sequentially feeding the substrate into a tunnel bin filled with hydrogen iodide vapor and a tunnel furnace to obtain a fluffy graphene composite nanometer copper film; first placing the fluffy graphene composite nanometer copper film in a carbonization furnace, and then placing the fluffy graphene composite nanometer copper film in a graphitization furnace to obtain a heat-treated fluffy graphene composite nanometer copper film; and placing the heat-treated fluffy graphene composite nanometer copper film in a vacuum high-temperature hot-pressing sintering furnace. Through the updating of the formula and the process, the copper is attached to the surface of the graphene and filled and covered in the gap between the graphene layers, so that the thermal conductivity of the graphene heat-conducting film in the thickness direction is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparing heat-conducting films, and particularly relates to a graphene composite copper heat-conducting film and a preparation method thereof. BACKGROUND

[0002] This part provides only background information related to the present disclosure, which is not necessarily prior art.

[0003] With the development of mobile phones towards high performance and miniaturization, the heat generation of chips is getting larger and larger. Due to the limited space, heat is easy to gather to form hot spots, which leads to the failure of the normal work of the chips. Therefore, a material with high lateral thermal conductivity is used for heat dissipation. For 4G mobile phones, the material is usually artificial graphite heat-dissipating film, which is prepared by using polyimide film as raw material through carbonization, graphitization and calendering process. Limited by the polyimide film raw material, the thickness of the artificial graphite heat-dissipating film is limited (<100 μm), which cannot cope with the higher heat generation of 5G mobile phone chips. Due to the difference in process and raw material, the graphene heat-dissipating film breaks through the thickness limitation and can meet the heat dissipation requirements of 5G mobile phone chips, and thus has been widely applied.

[0004] The graphene heat-conducting film is prepared by using graphene oxide as raw material through pulping, coating, carbonization, graphitization and calendering process. Because graphene oxide contains a large number of oxygen-containing functional groups, it is easy to disperse in water to obtain a stable high-solid slurry. During the coating process of the slurry, graphene oxide is self-assembled into an oriented arrangement through hydrogen bonding and van der Waals force between the layers. At a higher temperature, graphene oxide is reduced to graphene, and then the lattice is repaired through graphitization and the density is increased through calendering, so as to finally obtain a graphene heat-conducting film with oriented graphene. Because graphene is a thermally anisotropic material, that is, it has ultra-high thermal conductivity in the two-dimensional plane direction (theoretically 5300 W / (m·K)), but the thermal conductivity in the direction perpendicular to the two-dimensional plane is low, less than 20 W / (m·K). Therefore, the graphene heat-conducting film with oriented graphene has very high in-plane thermal conductivity, but in the thickness direction, the thermal conductivity is very low, generally <10 W / (m·K), which leads to the failure of the excellent horizontal heat conduction capacity of the graphene heat-conducting film. SUMMARY

[0005] In view of the above problems, the first aspect of the present application provides a preparation method of a graphene composite copper heat-conducting film, comprising:

[0006] Pulping: graphene oxide is added to water and stirred to obtain a graphene oxide slurry;

[0007] Compounding: copper sulfate solution is added to the graphene oxide slurry to obtain a graphene oxide / copper sulfate composite slurry;

[0008] Coating: The graphene oxide-copper sulfate composite slurry is coated onto the substrate;

[0009] Reduction: The substrate is sequentially fed into a tunnel chamber and a tunnel furnace filled with hydrogen iodide vapor to obtain a fluffy graphene composite copper nanofilm;

[0010] Heat treatment: First, the fluffy graphene composite copper nanofilm is placed in a carbonization furnace, and then placed in a graphitization furnace to obtain a heat-treated fluffy graphene composite copper nanofilm.

[0011] Vacuum hot pressing: The heat-treated fluffy graphene composite nano copper film is placed in a vacuum high-temperature hot pressing sintering furnace at 1400℃-1800℃, with a pressure of 10-100 tons and a vacuum pressing time of 10-30 minutes.

[0012] Copper sulfate solution and graphene oxide slurry are mixed and coated onto a substrate, followed by reduction, heat treatment, and vacuum hot pressing. Graphene oxide is reduced to graphene in a tunnel chamber filled with hydrogen iodide vapor, while copper sulfate is reduced to nano-copper in the same chamber and adheres to the graphene surface. Moisture is continuously evaporated in the tunnel furnace. The graphene lattice is repaired in a carbonization and graphitization furnace, removing heteroatoms from the porous graphene composite copper nanofilm, resulting in a heat-treated porous graphene composite copper nanofilm. Finally, vacuum hot pressing melts the nano-copper. Under pressure and vacuum, air is expelled from the heat-treated porous graphene composite copper nanofilm, reducing the interlayer spacing of the graphene sheets. The molten nano-copper can then penetrate between the graphene sheets. After cooling, a graphene composite copper thermally conductive film is obtained.

[0013] By updating the formulation and process, copper sulfate solution is converted into nano-copper and introduced. Through composite, reduction, heat treatment and vacuum hot pressing, copper is attached to the surface of graphene and fills the gaps between graphene sheets. Since copper has good thermal conductivity, the thermal conductivity of the graphene thermal conductive film in the thickness direction is improved, while maintaining the in-plane thermal conductivity.

[0014] In some embodiments of the present invention, the solid content of the graphene oxide slurry is 2wt%-6wt%.

[0015] In some embodiments of the present invention, the concentration of the copper sulfate solution is 0.01-0.1 mol / L.

[0016] In some embodiments of the present invention, the mass ratio of copper in the copper sulfate solution to graphene in the graphene oxide is 1:0.2-1.

[0017] In some embodiments of the present invention, the temperature inside the tunnel furnace is 70℃-90℃, the temperature inside the carbonization furnace is 1300℃-1500℃, the time inside the carbonization furnace is 2-6 hours, and the temperature inside the graphitization furnace is 2850℃-3000℃, the time inside the carbonization furnace is 6-10 hours.

[0018] A second aspect of the present invention provides a graphene composite copper thermal conductive film, which is obtained by the preparation method of graphene composite copper thermal conductive film in any of the above technical solutions.

[0019] The graphene composite copper thermal conductive film of this invention has the same beneficial effects as the graphene composite copper thermal conductive film prepared by the preparation method of any of the above-mentioned technical solutions, and will not be repeated here.

[0020] In some embodiments of the present invention, the mass ratio of copper to graphene in the graphene-copper thermal conductive film is 1:0.2-1.

[0021] In some embodiments of the present invention, in the graphene-copper composite thermal conductive film, the copper occupies the surface of the graphene and the gaps between the layers.

[0022] In some embodiments of the present invention, the thickness of the graphene composite copper thermal conductive film is 50-300 μm.

[0023] In some embodiments of the present invention, the thickness-direction thermal conductivity of the graphene composite copper thermal conductive film is 50-100 W / (m·K), and the in-plane thermal conductivity is 1100-1600 W / (m·K). Attached Figure Description

[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0025] Figure 1 This is a flowchart illustrating the preparation method of the graphene composite copper thermal conductive film according to an embodiment of the present invention. Detailed Implementation

[0026] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0027] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also mean including the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof.

[0028] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0029] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0030] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0031] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0032] like Figure 1 As shown, the first aspect of the present invention provides a method for preparing a graphene composite copper thermal conductive film, comprising:

[0033] Pulping: Add graphene oxide to water and stir to obtain graphene oxide slurry;

[0034] Composite: A copper sulfate solution is added to the graphene oxide slurry to obtain a graphene oxide / copper sulfate composite slurry;

[0035] Coating: The graphene oxide-copper sulfate composite slurry is coated onto the substrate;

[0036] Reduction: The substrate is sequentially fed into a tunnel chamber and a tunnel furnace filled with hydrogen iodide vapor to obtain a fluffy graphene composite copper nanofilm;

[0037] Heat treatment: First, the fluffy graphene composite copper nanofilm is placed in a carbonization furnace, and then placed in a graphitization furnace to obtain a heat-treated fluffy graphene composite copper nanofilm.

[0038] Vacuum hot pressing: The heat-treated fluffy graphene composite nano copper film is placed in a vacuum high-temperature hot pressing sintering furnace at 1400℃-1800℃, with a pressure of 10-100 tons and a vacuum pressing time of 10-30 minutes.

[0039] Copper sulfate solution and graphene oxide slurry are mixed and coated onto a substrate, followed by reduction, heat treatment, and vacuum hot pressing. Graphene oxide is reduced to graphene in a tunnel chamber filled with hydrogen iodide vapor, while copper sulfate is reduced to nano-copper in the same chamber and adheres to the graphene surface. Moisture is continuously evaporated in the tunnel furnace. The graphene lattice is repaired in a carbonization and graphitization furnace, removing heteroatoms from the porous graphene composite copper nanofilm, resulting in a heat-treated porous graphene composite copper nanofilm. Finally, vacuum hot pressing melts the nano-copper. Under pressure and vacuum, air is expelled from the heat-treated porous graphene composite copper nanofilm, reducing the interlayer spacing of the graphene sheets. The molten nano-copper can then penetrate between the graphene sheets. After cooling, a graphene composite copper thermally conductive film is obtained.

[0040] By updating the formulation and process, copper sulfate solution is converted into nano-copper and introduced. Through composite, reduction, heat treatment and vacuum hot pressing, copper is attached to the surface of graphene and fills the gaps between graphene sheets. Since copper has good thermal conductivity, the thermal conductivity of the graphene thermal conductive film in the thickness direction is improved, while maintaining the in-plane thermal conductivity.

[0041] In some embodiments of the present invention, the solid content of the graphene oxide slurry is 2wt%-6wt%.

[0042] In some embodiments of the present invention, the concentration of the copper sulfate solution is 0.01-0.1 mol / L.

[0043] In some embodiments of the present invention, the mass ratio of copper in the copper sulfate solution to graphene in the graphene oxide is 1:0.2-1.

[0044] In some embodiments of the present invention, the temperature inside the tunnel furnace is 70℃-90℃, the temperature inside the carbonization furnace is 1300℃-1500℃, the time inside the carbonization furnace is 2-6 hours, and the temperature inside the graphitization furnace is 2850℃-3000℃, the time inside the carbonization furnace is 6-10 hours.

[0045] The following will illustrate the preparation of an electrothermal film composed of graphene / polyurethane composite film by comparison and the preparation of graphene composite copper thermal conductive films by different embodiments:

[0046] Example 1

[0047] Pulping: Add graphene oxide to water and stir in a dual planetary vacuum mixer to obtain a graphene oxide slurry with a solid content of 6 wt%.

[0048] Composite: A copper sulfate solution with a concentration of 0.05 mol / L was added to the graphene oxide slurry according to the mass ratio of copper to graphene of 1:0.2. After thorough stirring, a graphene oxide / copper sulfate composite slurry was obtained.

[0049] Coating: The above-mentioned graphene oxide / copper sulfate composite slurry is coated onto the substrate;

[0050] Reduction: First, the substrate is sent into a tunnel chamber filled with hydrogen iodide vapor, where graphene oxide is reduced to graphene and copper sulfate is reduced to nano-copper that adheres to the graphene surface. Then, the substrate is sent into a tunnel furnace at a temperature of 70°C, where the moisture evaporates to obtain a fluffy graphene composite nano-copper film.

[0051] Heat treatment: First, the above-mentioned fluffy graphene composite copper nanofilm was placed in a carbonization furnace and treated at 1300℃ for 4 hours, and then treated in a graphitization furnace at 3000℃ for 10 hours to repair the graphene lattice and remove heteroatoms, thus obtaining the heat-treated fluffy graphene composite copper nanofilm.

[0052] Vacuum hot pressing: The heat-treated fluffy graphene composite copper nanofilm was placed in a vacuum high-temperature hot pressing furnace at 1400℃ and 100 tons of pressure for 30 minutes. At high temperature, the copper nanoparticles are in a molten state. Under pressure and vacuum, the air inside the heat-treated fluffy graphene composite copper nanofilm is expelled, the spacing between graphene sheets decreases, and the gaps between the sheets are filled and covered by molten copper. After cooling, a graphene composite copper thermally conductive film is obtained.

[0053] The above-mentioned graphene-copper conductive film was tested by thermogravimetric analyzer. The mass ratio of copper to graphene was 1:0.2. The thickness was measured by thickness gauge to be 50 μm. The thermal conductivity in the thickness direction was measured to be 100 W / (m·K) and the in-plane thermal conductivity was measured to be 1600 W / (m·K) by laser thermal conductivity meter.

[0054] Example 2

[0055] Pulping: Add graphene oxide to water and stir in a double planetary vacuum mixer to obtain a graphene oxide slurry with a solid content of 2wt%.

[0056] Composite: A copper sulfate solution with a concentration of 0.1 mol / L was added to the graphene oxide slurry according to the mass ratio of copper to graphene of 1:1. After thorough stirring, a graphene oxide / copper sulfate composite slurry was obtained.

[0057] Coating: The above-mentioned graphene oxide / copper sulfate composite slurry is coated onto the substrate;

[0058] Reduction: First, the substrate is sent into a tunnel chamber filled with hydrogen iodide vapor, where graphene oxide is reduced to graphene and copper sulfate is reduced to nano-copper that adheres to the graphene surface. Then, the substrate is sent into a tunnel furnace at a temperature of 90°C, where the moisture evaporates to obtain a fluffy graphene composite nano-copper film.

[0059] Heat treatment: First, the above-mentioned fluffy graphene composite copper nanofilm was placed in a carbonization furnace and treated at 1500℃ for 4 hours, and then treated in a graphitization furnace at 3000℃ for 6 hours to repair the graphene lattice and remove heteroatoms, thus obtaining the heat-treated fluffy graphene composite copper nanofilm.

[0060] Vacuum hot pressing: The heat-treated fluffy graphene composite copper nanofilm was placed in a vacuum high-temperature hot pressing furnace at 1800℃ and 50 tons of pressure for 10 minutes. At high temperature, the copper nanoparticles are in a molten state. Under pressure and vacuum, the air inside the heat-treated fluffy graphene composite copper nanofilm is expelled, the spacing between graphene sheets decreases, and the gaps between the sheets are filled and covered by molten copper. After cooling, a graphene composite copper thermally conductive film is obtained.

[0061] The above-mentioned graphene-copper conductive film was tested by a thermogravimetric analyzer. The mass ratio of copper to graphene was 1:1. The thickness was measured by a thickness gauge to be 300 μm. The thermal conductivity in the thickness direction was measured to be 50 W / (m·K) and the in-plane thermal conductivity was measured to be 1100 W / (m·K) by a laser thermal conductivity meter.

[0062] Comparative Example 1 (Graphene composite carbon fiber thermal conductive film, compared with Example 1)

[0063] Step 1: Add a certain amount of graphene oxide to deionized water and disperse it to prepare a slurry with a solid content of 6 wt%. Stir the slurry in a double planetary vacuum mixer to obtain a uniformly dispersed graphene oxide slurry.

[0064] Step 2: Add 1 part of high thermal conductivity carbon fiber powder to 20 parts of concentrated sulfuric acid and acidify for 2 hours to activate the carbon fiber surface. Then wash and dry to obtain acidified fiber powder.

[0065] Step 3: Add high thermal conductivity carbon fiber powder, which accounts for 5% of the graphene oxide content, to the slurry. The carbon fiber has a diameter of about 7 μm and a length of 50 μm. Mix thoroughly in a dual planetary vacuum mixer for 2 hours to obtain a composite slurry of graphene oxide / carbon fiber.

[0066] Step 4: The composite slurry obtained in step S3 is coated onto a coating machine to form a film, and after drying, a composite film of graphene oxide / carbon fiber is obtained.

[0067] Step 5: The composite film obtained above is treated at 1300℃ for 4 hours, and then treated at 3000℃ for 10 hours in a graphitization furnace to complete graphitization and obtain a graphene film.

[0068] Step 6: The graphene film obtained above is further vacuum-pressed under a pressure of 100 tons for 30 minutes to obtain a high thermal conductivity graphene / carbon fiber composite thermal conductive film with a thickness of 50 μm. The in-plane thermal conductivity can reach 1200 W / (m·K) and the vertical thermal conductivity can reach 30 W / (m·K).

[0069] Comparative Example 2 (graphene composite thermal conductive film, compared with Example 1)

[0070] Step 1: Add a certain amount of graphene oxide to deionized water and disperse it to prepare a slurry with a solid content of 6 wt%. Stir the slurry in a double planetary vacuum mixer to obtain a uniformly dispersed graphene oxide slurry.

[0071] Step 2: The graphene oxide slurry obtained in step S1 is coated onto a coating machine to form a film, and after drying, a graphene oxide film is obtained.

[0072] Step 3: The graphene oxide film obtained above is treated at 1300℃ for 4 hours, and then treated at 3000℃ for 10 hours in a graphitization furnace to complete the graphitization and obtain a graphene film.

[0073] Step 4: The graphene film obtained above is further vacuum-pressed under a pressure of 100 tons for 30 minutes to obtain a high thermal conductivity graphene thermal conductive film with a thickness of 50 μm. The in-plane thermal conductivity can reach 1550 W / (m·K) and the vertical thermal conductivity can reach 5 W / (m·K).

[0074] Comparing Example 1, Example 2, and Comparative Example 1 and Comparative Example 2, it can be seen that the in-plane thermal conductivity of the samples is similar, but the thermal conductivity in the thickness direction of Example 1 and Example 2 is significantly improved compared to Comparative Example 1 and Comparative Example 2. Analysis of the mass ratio of copper to graphene in the final sample shows that the introduction of copper plays a decisive role in improving the thermal conductivity in the thickness direction.

[0075] A second aspect of the present invention provides a graphene composite copper thermal conductive film, which is obtained by the preparation method of graphene composite copper thermal conductive film in any of the above technical solutions.

[0076] The graphene composite copper thermal conductive film of this invention has the same beneficial effects as the graphene composite copper thermal conductive film prepared by the preparation method of any of the above-mentioned technical solutions, and will not be repeated here.

[0077] In some embodiments of the present invention, the mass ratio of copper to graphene in the graphene-copper thermal conductive film is 1:0.2-1.

[0078] In some embodiments of the present invention, in the graphene-copper composite thermal conductive film, copper occupies the gaps between the graphene sheets. Copper adheres to the surface of the graphene and fills the gaps between the graphene sheets. Due to the good thermal conductivity of copper, the thermal conductivity of the graphene thermal conductive film in the thickness direction is improved, while maintaining the in-plane thermal conductivity.

[0079] In some embodiments of the present invention, the thickness of the graphene composite copper thermal conductive film is 50-300 μm.

[0080] In some embodiments of the present invention, the thermal conductivity in the thickness direction of the graphene composite copper thermal conductive film is 50-100 W / (m·K), and the in-plane thermal conductivity is 1100-1600 W / (m·K).

[0081] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a graphene composite copper thermal conductive film, characterized in that, include: Pulping: Add graphene oxide to water and stir to obtain graphene oxide slurry; Composite: A copper sulfate solution is added to the graphene oxide slurry to obtain a graphene oxide / copper sulfate composite slurry; Coating: The graphene oxide-copper sulfate composite slurry is coated onto the substrate; Reduction: The substrate is sequentially fed into a tunnel chamber and a tunnel furnace filled with hydrogen iodide vapor to obtain a fluffy graphene composite copper nanofilm; Heat treatment: First, the loose graphene composite copper nanofilm is placed in a carbonization furnace to remove heteroatoms from the loose graphene composite copper nanofilm to obtain a heat-treated loose graphene composite copper nanofilm. Then, it is placed in a graphitization furnace to obtain a heat-treated loose graphene composite copper nanofilm. Vacuum hot pressing: The heat-treated fluffy graphene composite copper nanofilm is placed in a vacuum high-temperature hot pressing sintering furnace at 1400℃-1800℃, with a pressure of 10-100 tons and a vacuum pressing time of 10-30 minutes. The air inside the heat-treated fluffy graphene composite copper nanofilm is expelled, the spacing between the graphene sheets is reduced, and the molten copper nanofilm can enter the spaces between the graphene sheets. After cooling, a graphene composite copper thermal conductive film is obtained.

2. The method for preparing the graphene composite copper thermal conductive film according to claim 1, characterized in that, The solid content of the graphene oxide slurry is 2wt%-6wt%.

3. The method for preparing the graphene composite copper thermal conductive film according to claim 1, characterized in that, The concentration of the copper sulfate solution is 0.01-0.1 mol / L.

4. The method for preparing the graphene composite copper thermal conductive film according to claim 1, characterized in that, The mass ratio of copper in the copper sulfate solution to graphene in the graphene oxide is 1:0.2-1.

5. The method for preparing the graphene composite copper thermal conductive film according to claim 1, characterized in that, The temperature inside the tunnel furnace is 70℃-90℃, the temperature inside the carbonization furnace is 1300℃-1500℃, and the time inside the carbonization furnace is 2-6 hours. The temperature inside the graphitization furnace is 2850℃-3000℃, and the time inside the carbonization furnace is 6-10 hours.

6. A graphene composite copper thermal conductive film, obtained by the preparation method of the graphene composite copper thermal conductive film according to any one of claims 1-5.

7. The graphene composite copper thermal conductive film according to claim 6, characterized in that, The mass ratio of copper to graphene in the graphene-copper composite thermal conductive film is 1:0.2-1.

8. The graphene composite copper thermal conductive film according to claim 7, characterized in that, In the graphene-copper composite thermal conductive film, copper occupies the gaps between the graphene sheets.

9. The graphene composite copper thermal conductive film according to claim 6, characterized in that, The thickness of the graphene-copper thermal conductive film is 50-300 μm.

10. The graphene composite copper thermal conductive film according to claim 6, characterized in that, The graphene-copper composite thermal conductive film has a thickness-direction thermal conductivity of 50-100 W / (m·K) and an in-plane thermal conductivity of 1100-1600 W / (m·K).

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