A copper foil graphite sheet and its manufacturing process

Abstract

The present invention belongs to the technical field of heat dissipation foil materials, and particularly relates to a copper foil graphite sheet and a manufacturing process thereof. The heat sink developed by the present invention includes a copper foil and a graphene layer continuously deposited on the surface of the copper foil; it also includes a nickel plating layer distributed in a discontinuous island shape between the copper foil and the graphene layer; the nickel plating layer is electroplated on the surface of the copper foil; at least part of the graphene grows inside the nickel plating layer. At least part of the surface area of the copper foil is provided with through holes, the nickel plating layer covers the through holes and connects the nickel plating layers electroplated on both sides of the copper foil; in addition, the total area of the through holes accounts for 5-10% of the single-sided area of the copper foil; the area of the single-sided nickel plating layer accounts for 15-20% of the single-sided area of the copper foil. The copper foil graphite sheet of the present invention can ensure a stable heat dissipation effect during use and prevent the graphene layer from peeling off the surface of the copper foil.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat dissipation foil materials. More specifically, it relates to a copper foil graphite sheet and its manufacturing process. Background Art

[0002] Intelligent devices such as tablet computers and smart phones have a huge market demand for heat dissipation. However, their heat dissipation solutions are different from those of traditional PCs and laptops. Since they cannot install fans and the available heat dissipation area and thickness are quite limited, currently, only thin heat dissipation materials and components can be used for thermal management.

[0003] Since the internal components of thin and light intelligent devices are installed compactly, when placing heat dissipation components therein, it is often necessary to arrange them adaptively according to the layout of the internal components. Therefore, it is desired that the heat dissipation components have good flexibility.

[0004] For conventional heat dissipation components, there are products with graphene directly coated on the surface of copper foil. If a general resin adhesive with extremely poor thermal conductivity is used as the adhesive for the graphene layer, it will easily cause obstruction in the process of heat transfer or heat dissipation in the plane direction of the surface graphene layer. In particular, the resin adhesive is prone to aging after long-term use; but if graphene is directly deposited on the surface of copper foil by methods such as chemical vapor deposition, when the heat dissipation component is laid inside a compact intelligent device, especially at the bent parts of the heat dissipation component, the graphene layer is likely to be detached from the underlying copper foil, resulting in obstruction of heat transfer between the copper foil and the graphene layer.

[0005] Therefore, how to enable the graphene layer attached to the surface of copper foil to be firmly adsorbed on the copper foil surface for a long time and avoid a significant decrease in the heat dissipation performance of the heat dissipation component during use has become one of the technical problems urgently to be solved by those skilled in the art. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects and deficiencies that in the heat dissipation component with a graphene layer attached to the surface of copper foil, the graphene layer is difficult to be effectively and long-term adsorbed on the copper foil surface, especially it is easy to cause poor heat dissipation performance at the bent parts, and to provide a copper foil graphite sheet and its manufacturing process.

[0007] The object of the present invention is to provide a copper foil graphite sheet.

[0008] Another object of the present invention is to provide a manufacturing process of a copper foil graphite sheet.

[0009] The above objects of the present invention are achieved by the following technical solutions:

[0010] A copper foil graphite sheet, comprising a copper foil and a graphene layer continuously deposited on the surface of the copper foil;

[0011] It also includes a nickel plating layer that is discontinuously distributed in island shapes between the copper foil and the graphene layer;

[0012] The nickel plating layer is electroplated on the surface of the copper foil;

[0013] At least part of the graphene is grown inside the nickel plating layer by chemical vapor deposition.

[0014] The above technical solution locally nickel-plates the surface of the copper foil to form a nickel plating layer with a discontinuous island distribution, and controls at least part of the graphene to grow inside the nickel plating layer; First, the graphene sheets can be anchored to the surface of the copper foil through the nickel plating layer, and due to the intercalation between the graphene sheets and the intermolecular interaction forces, a continuous and stable graphene layer can be formed;

[0015] In addition, when heat contacts the copper foil, the copper foil can quickly transfer the heat in the planar direction and the thickness direction of the copper foil; when the heat is transferred to the graphene layer, the graphene can achieve faster planar direction transfer. Due to the gaps between the layers, the heat dissipation in the thickness direction of the graphene is relatively lagging. And at the distribution of the nickel plating layer, the thickness of the graphene layer is less than that at the non-nickel plating layer distribution. Therefore, to a certain extent, the nickel plating layer can assist in the heat transfer in the thickness direction of the graphene layer at this location, thereby effectively enhancing the overall heat dissipation effect of the product by changing the local heat transfer mode.

[0016] Furthermore, graphene layers are continuously deposited on both side surfaces of the copper foil; and on both side surfaces of the copper foil, there are nickel plating layers that are discontinuously distributed in island shapes between the copper foil and the graphene layer.

[0017] By continuously depositing graphene layers on both side surfaces of the copper foil, in this way, the excellent flexibility of the graphene layer can be utilized to fit well on the surface of the corresponding components, reducing the interfacial thermal resistance of the contact. And since graphene layers are provided on both surfaces, one of the two surfaces plays the role of absorbing heat in the early stage, and the other plays the role of dissipating heat in the later stage. Since the materials are the same, the balance between heat absorption and dissipation can be achieved, reducing the accumulation of heat inside.

[0018] Furthermore, through holes are distributed in at least part of the area on the surface of the copper foil, the nickel plating layer covers the through holes and connects the nickel plating layers electroplated on both sides of the copper foil.

[0019] Holes are punched on the surface of the copper foil, and a nickel plating layer is formed at the position where the through holes are located, and the through holes are effectively filled, so as to realize the connection of the nickel plating layers on both sides of the copper foil. In this way, the nickel plating layers on the two surfaces can be more firmly anchored to the surface of the copper foil. At the same time, the heat here can be directly transferred from the graphene layer on one side to the copper foil and the graphene layer on the other side through the nickel plating layer. By further optimizing the local heat transfer path, the overall heat dissipation effect is improved.

[0020] Further, the aperture of the through hole is 0.8-1.5 times the thickness of the copper foil.

[0021] In particular, by controlling the relationship between the aperture and the thickness of the copper foil, excessive nickel deposition in the over-large aperture is avoided, which may lead to the formation of a harder nickel plating layer at the pores, resulting in the risk of tearing of the copper foil at the punched holes when the heat sink is folded, thus causing cracks on the surface and affecting the heat dissipation in the plane direction.

[0022] Further, the total area of the through holes accounts for 5-10% of the single-sided area of the copper foil; the area of the single-sided nickel plating layer accounts for 15-20% of the single-sided area of the copper foil.

[0023] By further controlling the area of the through holes and the area of the single-sided nickel plating layer, while ensuring the effective anchoring of the nickel plating layers on both sides, the graphene layer obtains sufficient anchoring of the nickel plating layer. Synchronously, the nickel plating layer with sufficient area enables the graphene layer with sufficient area to obtain relatively better heat conduction in the thickness direction. In addition, although the nickel plating layer improves the heat transfer path, the problem of low heat dissipation efficiency at the material level due to its significantly lower thermal conductivity than that of copper needs to be considered. The size of the through hole area controls the filling amount of nickel in the through hole, and the area of the nickel plating layer directly controls the relative content of the nickel plating layer deposited on the surface of the copper foil.

[0024] Further, the thickness of the copper foil is 20-60 μm, and the thickness of the single-sided nickel plating layer is 1 / 3-1 / 2 of the thickness of the copper foil.

[0025] Further, the thickness of a single layer of the graphene layer is 0.8-1.5 times the thickness of the copper foil; the thickness of a single layer of the graphene is the thickness of the graphene layer in the non-nickel-plated area.

[0026] A manufacturing process of a copper foil graphite sheet, and the specific preparation steps include:

[0027] Nickel plating is carried out on the surface of the copper foil to form a nickel plating layer with a discontinuous island-like distribution;

[0028] The copper foil with the nickel plating layer is heated to 850-900 °C in a hydrogen atmosphere, and after heat preservation, annealing treatment is carried out to obtain a pretreated copper foil;

[0029] The pretreated copper foil is subjected to chemical vapor deposition of graphene layers in a mixed atmosphere of hydrogen and methane. After the growth of the graphene layers is completed, the temperature is rapidly reduced to room temperature, and the product is discharged.

[0030] Furthermore, the mixed atmosphere of hydrogen and methane is formed by mixing hydrogen and methane in a volume ratio of 3:1 - 5:1. Specific Embodiments

[0031] The present invention will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0032] Unless otherwise specified, the reagents and materials used in the following embodiments are all commercially available.

[0033] Example 1

[0034] Select a copper foil with a thickness of 20 μm as the substrate. First, clean the surface of the copper foil with sulfuric acid with a mass fraction of 10% to remove the surface oxide layer, and then clean it with clean water to remove the residual sulfuric acid. After the surface is dried, clean it with acetone to remove oil, and obtain a cleaned copper foil;

[0035] Taking the thickness of the copper foil as the base number, use a punch to punch through holes on the surface of the copper foil, control the diameter of the through holes to be 0.8 times the thickness of the copper foil, and the total area of all through holes on the surface of the copper foil accounts for 5% of the single-sided area of the copper foil. After the punching is completed, remove the residues in the through holes to obtain a punched copper foil;

[0036] Adopt the electroplating method, use a nickel nitrate solution with a mass fraction of 10% as the plating solution, and add a brightener accounting for 0.1% of the mass of the nickel nitrate solution and a wetting agent accounting for 2% of the mass of the nickel nitrate solution to the nickel nitrate solution. During the electroplating process, control the temperature of the plating solution at 30 °C by water bath, and the electroplating current density is 3 A / cm 2 , and control the thickness of the nickel plating layer deposited on the surface of the punched copper foil by controlling the electroplating time. Specifically, the thickness of the single-sided nickel plating layer is 1 / 3 of the thickness of the copper foil; by exposing the punched area and covering the unpunched area to control the coverage area of the nickel plating layer. Specifically, make the nickel plating layer fill and cover all the through holes to obtain a nickel-plated copper foil with a discontinuous island-like distributed nickel plating layer, and make the area of the single-sided nickel plating layer account for 15% of the single-sided area of the copper foil;

[0037] Heat the nickel-plated copper foil to 850 °C in a hydrogen atmosphere, and after holding for 30 min, perform annealing treatment to obtain a pretreated copper foil;

[0038] The pretreated copper foil is subjected to chemical vapor deposition of graphene layers in a mixed atmosphere of hydrogen and methane. Specifically, when controlling the chemical vapor deposition, the reaction temperature is 1000 °C, and by changing the deposition time, the thickness of the graphene layer grown on the surface of the pretreated copper foil is controlled. The thickness of a single-layer graphene layer is 0.8 times the thickness of the copper foil; the thickness of a single-layer graphene is the thickness of the graphene layer in the non-nickel-plated area; after the growth of the graphene layer is completed, it is rapidly cooled to room temperature within 5 minutes, and the product is taken out; wherein, the mixed atmosphere of hydrogen and methane is formed by mixing hydrogen and methane in a volume ratio of 3:1.

[0039] Example 2

[0040] Select a copper foil with a thickness of 40 μm as the substrate. First, clean the surface of the copper foil with sulfuric acid with a mass fraction of 10% to remove the surface oxide layer, and then wash it with clean water to remove the residual sulfuric acid. After the surface is dried, wash it with acetone to remove oil to obtain a cleaned copper foil;

[0041] Taking the thickness of the copper foil as the base number, use a punch to punch through holes on the surface of the copper foil, control the diameter of the through holes to be 1.2 times the thickness of the copper foil, and the total area of all through holes on the surface of the copper foil accounts for 8% of the single-sided area of the copper foil. After the punching is completed, remove the residues in the through holes to obtain a punched copper foil;

[0042] Adopt the electroplating method, use a nickel nitrate solution with a mass fraction of 15% as the plating solution, and add a brightener accounting for 0.2% of the mass of the nickel nitrate solution and a wetting agent accounting for 3% of the mass of the nickel nitrate solution to the nickel nitrate solution. During the electroplating process, control the temperature of the plating solution at 32 °C by water bath, and the electroplating current density is 5 A / cm 2 , and by controlling the electroplating time, the thickness of the nickel-plated layer deposited on the surface of the punched copper foil is regulated. Specifically, the thickness of the single-sided nickel-plated layer is 1 / 3 of the thickness of the copper foil; by exposing the punched area and covering the unpunched area to control the coverage area of the nickel-plated layer. Specifically, the nickel-plated layer fills and covers all the through holes to obtain a nickel-plated copper foil with a discontinuous island-like distributed nickel-plated layer, and the area of the single-sided nickel-plated layer accounts for 18% of the single-sided area of the copper foil;

[0043] Heat the nickel-plated copper foil to 880 °C in a hydrogen atmosphere, and after holding for 35 minutes, perform annealing treatment to obtain a pretreated copper foil;

[0044] The pretreated copper foil is subjected to chemical vapor deposition of graphene layers in a mixed atmosphere of hydrogen and methane. Specifically, during chemical vapor deposition, the reaction temperature is controlled at 1010 °C, and by changing the deposition time, the thickness of the graphene layer grown on the surface of the pretreated copper foil is controlled. The thickness of a single-layer graphene layer is 1.2 times the thickness of the copper foil; the thickness of a single-layer graphene is the thickness of the graphene layer in the non-nickel-plated region. After the growth of the graphene layer is completed, it is rapidly cooled to room temperature within 8 minutes, and the product is discharged. Among them, the mixed atmosphere of hydrogen and methane is formed by mixing hydrogen and methane in a volume ratio of 4:1.

[0045] Example 3

[0046] Select a copper foil with a thickness of 60 μm as the substrate. First, clean the surface of the copper foil with sulfuric acid with a mass fraction of 10% to remove the surface oxide layer, and then wash it with clean water to remove the residual sulfuric acid. After the surface is dried, wash it with acetone to remove oil, and obtain the cleaned copper foil.

[0047] Taking the thickness of the copper foil as the base number, use a punch to punch through holes on the surface of the copper foil, control the diameter of the through holes to be 1.5 times the thickness of the copper foil, and the total area of all through holes on the surface of the copper foil accounts for 10% of the single-sided area of the copper foil. After the punching is completed, remove the residues in the through holes to obtain the punched copper foil.

[0048] Adopt the electroplating method, use a nickel nitrate solution with a mass fraction of 20% as the plating solution, add a brightener accounting for 0.3% of the mass of the nickel nitrate solution and a wetting agent accounting for 4% of the mass of the nickel nitrate solution to the nickel nitrate solution. During the electroplating process, control the temperature of the plating solution at 35 °C through a water bath, and the electroplating current density is 6 A / cm 2 , and by controlling the electroplating time, the thickness of the nickel-plated layer deposited on the surface of the punched copper foil is regulated. Specifically, the thickness of the single-sided nickel-plated layer is 1 / 2 of the thickness of the copper foil; by exposing the punched area and covering the unpunched area to control the coverage area of the nickel-plated layer, specifically, the nickel-plated layer fills and covers all the through holes to obtain a nickel-plated copper foil with a discontinuous island-like distributed nickel-plated layer, and the area of the single-sided nickel-plated layer accounts for 20% of the single-sided area of the copper foil.

[0049] Heat the nickel-plated copper foil to 900 °C in a hydrogen atmosphere, and after holding for 40 minutes, perform annealing treatment to obtain the pretreated copper foil.

[0050] The pretreated copper foil is subjected to chemical vapor deposition of graphene layers in a mixed atmosphere of hydrogen and methane. Specifically, when controlling the chemical vapor deposition, the reaction temperature is 1020 °C, and by changing the deposition time, the thickness of the graphene layer grown on the surface of the pretreated copper foil is controlled. The thickness of a single-layer graphene layer is 1.5 times the thickness of the copper foil; the thickness of a single-layer graphene is the thickness of the graphene layer in the non-nickel-plated area; after the growth of the graphene layer is completed, it is rapidly cooled to room temperature within 10 minutes, and the product is taken out, thus obtaining the product; wherein, the mixed atmosphere of hydrogen and methane is formed by mixing hydrogen and methane in a volume ratio of 5:1.

[0051] Example 4

[0052] Compared with Example 1, the difference in this example is that the copper foil is not perforated, and the other conditions remain unchanged.

[0053] Example 5

[0054] Compared with Example 1, the difference in this example is that the through-hole diameter is controlled to be 1.6 times the thickness of the copper foil, and the other conditions remain unchanged.

[0055] Example 6

[0056] Compared with Example 1, the difference in this example is that the thickness of the single-sided nickel-plated layer is 0.6 times the thickness of the copper foil, and the other conditions remain unchanged.

[0057] Comparative Example 1

[0058] Compared with Example 1, the difference in this comparative example is that the copper foil is not nickel-plated, and the other conditions remain unchanged.

[0059] Performance tests are carried out on the products obtained in Examples 1-6 and Comparative Example 1. The specific test methods and test results are as follows:

[0060] The products obtained in each example and comparative example are cut, and the size of the cut samples is controlled to be 50 cm × 30 cm. The thermal conductivity 1 in the horizontal direction and the thermal conductivity 2 in the vertical direction of the cut samples are respectively tested. Subsequently, with the nickel-plated and perforated area as the folding part, a 180° bend is carried out, and after continuously bending 5000 times, the thermal conductivity 3 in the horizontal direction and the thermal conductivity 4 in the vertical direction are respectively tested again. After the thermal conductivity test is completed, it is observed whether the graphene layer on the surface has fallen off or become hollow. The specific test results are shown in Table 1:

[0061] Table 1: Product performance test results

[0062]

[0063]

[0064] As can be seen from the test results in Table 1, the product obtained by the present invention has excellent anti-bending performance and can effectively play a long-term reliable heat conduction and dissipation performance in compact intelligent devices.

[0065] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A copper foil graphite sheet, characterized in that, it includes a copper foil and a graphene layer continuously deposited on the surface of the copper foil; it further includes a nickel plating layer distributed in a discontinuous island shape between the copper foil and the graphene layer; the nickel plating layer is electroplated on the surface of the copper foil; at least part of the graphene is grown inside the nickel plating layer by chemical vapor deposition; graphene layers are continuously deposited on both side surfaces of the copper foil; and, on both side surfaces of the copper foil, there are nickel plating layers distributed in a discontinuous island shape between the copper foil and the graphene layer; through holes are distributed in at least part of the area of the copper foil surface, the nickel plating layer covers the through holes and connects the nickel plating layers electroplated on both sides of the copper foil; the thickness of the copper foil is 20 - 60 μm, and the thickness of the single-sided nickel plating layer is 1 / 3 - 1 / 2 of the thickness of the copper foil; the thickness of a single-layer graphene layer is 0.8 - 1.5 times the thickness of the copper foil; the thickness of a single-layer graphene is the thickness of the graphene layer in the non-nickel plating layer area; the specific preparation steps include: nickel plating is carried out on the surface of the copper foil to form a nickel plating layer distributed in a discontinuous island shape; heating the copper foil with the nickel plating layer to 850 - 900 °C in a hydrogen atmosphere, after heat preservation, annealing treatment is carried out to obtain a pretreated copper foil; carrying out gas-phase chemical deposition of a graphene layer on the pretreated copper foil in a mixed atmosphere of hydrogen and methane, after the growth of the graphene layer is completed, quickly cooling to room temperature and discharging to obtain the product; the mixed atmosphere of hydrogen and methane is formed by mixing hydrogen and methane according to a volume ratio of 3:1 - 5:

1.

2. A copper foil graphite sheet according to claim 1, characterized in that, the aperture of the through hole is 0.8 - 1.5 times the thickness of the copper foil.

3. A copper foil graphite sheet according to claim 1, characterized in that, the total area of the through holes accounts for 5 - 10% of the single-sided area of the copper foil; the area of the single-sided nickel plating layer accounts for 15 - 20% of the single-sided area of the copper foil.

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