Carbon fiber-carbon nanotube thermal interface material and preparation method thereof

Abstract

The invention discloses a carbon fiber-carbon nanotube thermal interface material and a preparation method thereof. The preparation method comprises the steps of pretreatment of carbon fibers, modification of the carbon fibers, orientation of the carbon fibers, growth of carbon nanotubes, compounding of polymers and the like. According to the preparation method of the carbon fiber-carbon nanotube thermal interface material, carbon fiber orientation and carbon nanotube compounding are realized, and oriented carbon fibers form a first-stage heat conduction network for direct conduction of heat; and moreover, the carbon nanotubes grown on the surface of the carbon fibers in situ form a secondary heat conduction network, are connected with the oriented carbon fibers and carry out auxiliary heat conduction, so that a dual heat conduction network is constructed, and through the synergistic effect of the dual heat conduction network, the in-plane heat conductivity and the through-plane heat conductivity of the composite material are improved. Meanwhile, the polymer matrix is adopted as the matrix, air in a gap between the chip and the packaging body can be fully extruded out, the contact thermal resistance between the chip and the packaging body is effectively reduced, and the thermal conductivity of the thermal interface material is improved.

Description

Technical Field

[0001] The invention relates to a thermally conductive composite material, and in particular to a carbon fiber-carbon nanotube thermal interface material and a preparation method thereof. Background Art

[0002] With the development of miniaturization, integration and functionalization of electronic products, the power density and heat flux density of electronic products have increased dramatically. The huge heat dissipation and temperature pressure in the device have affected the life and reliability of electronic equipment, so more stringent requirements are put forward on how to effectively dissipate heat during the operation of the device. Thermal interface material is a material with good thermal conductivity and high temperature resistance. Its main function is to compensate for the microscopic gap between the heating element and the heat dissipation device, thereby greatly improving the heat conduction efficiency. It has received widespread attention in recent years.

[0003] In the existing technology, carbon fiber has significant advantages in the field of thermal interface materials due to its excellent thermal conductivity, high strength and good mechanical compliance. However, the thermal conductivity of carbon fiber is anisotropic. Its thermal conductivity in the axial direction can be as high as 1000W / m·K, while it does not exceed 10W / m·K in the vertical direction, resulting in the heat conduction of carbon fiber failing to reach the ideal value. Summary of the invention

[0004] The purpose of the present invention is to provide a carbon fiber-carbon nanotube thermal interface material and a preparation method thereof, so as to solve the problem that the thermal conductivity of the above-mentioned carbon fiber has anisotropy, resulting in poor actual thermal conductivity.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for preparing a carbon fiber-carbon nanotube thermal interface material, comprising the following steps:

[0007] Pretreatment of carbon fiber: pickling and drying the carbon fiber;

[0008] Modification of carbon fiber: mixing the acid-washed carbon fiber with tetraethyl silicate in an organic solvent, then filtering out the organic solvent and drying; then heating the carbon fiber mixed with tetraethyl silicate to obtain silicon-modified carbon fiber;

[0009] Carbon fiber orientation: The orientation of silicon-modified carbon fiber is changed by applying an external physical field, so that the silicon-modified carbon fiber forms a 3D thermal conductive skeleton;

[0010] Growth of carbon nanotubes: firstly, a protective gas and a reducing gas are introduced to place the 3D thermally conductive skeleton in an atmosphere of the protective gas and the reducing gas; then, the 3D thermally conductive skeleton is heated, and a mixed liquid of a carbon source and a catalyst is introduced to grow carbon nanotubes on the 3D thermally conductive skeleton, thereby obtaining a carbon fiber-carbon nanotube skeleton;

[0011] Polymer composite: The polymer matrix is ​​vacuum impregnated into the carbon fiber-carbon nanotube skeleton, and the mixture is cured to obtain the carbon fiber-carbon nanotube thermal interface material.

[0012] In the method for preparing the carbon fiber-carbon nanotube thermal interface material, the aspect ratio of the carbon fiber is 100-500.

[0013] In the preparation method of the carbon fiber-carbon nanotube thermal interface material, in the step of growing carbon nanotubes, the carbon source gas and catalyst powder are directly guided to the 3D carbon fiber skeleton through a pipeline, and the introduction direction of the carbon source gas and catalyst powder is the same as the orientation direction of the carbon fiber.

[0014] In the method for preparing the carbon fiber-carbon nanotube thermal interface material, in the step of pre-treating the carbon fiber, the pickling step comprises:

[0015] The carbon fiber is mixed with the pickling liquid, and ultrasonically vibrated to obtain a mixed liquid containing the carbon fiber;

[0016] Adjusting the pH value of the mixed solution containing the carbon fibers to make the mixed solution neutral, and filtering out the carbon fibers in the mixed solution;

[0017] The drying step comprises: placing the filtered carbon fiber in anhydrous ethanol and performing ultrasonic dispersion; after ultrasonic dispersion, drying to completely volatilize the anhydrous ethanol to obtain acid-washed carbon fiber.

[0018] In the preparation method of the carbon fiber-carbon nanotube thermal interface material, in the pickling step, the temperature of the ultrasonic oscillation is 50-100°C, and the time of the ultrasonic oscillation is 0.5-3h; in the drying step, the temperature of the ultrasonic dispersion is 78.5-100°C, and the time of the ultrasonic dispersion is 0.5-3h.

[0019] In the method for preparing the carbon fiber-carbon nanotube thermal interface material, in the step of orienting the carbon fibers, the externally applied physical field includes one of a temperature field, a magnetic field, an electric field and a force field.

[0020] In the preparation method of the carbon fiber-carbon nanotube thermal interface material, in the step of growing carbon nanotubes, the carbon source includes one of methane, acetylene, ethanol, acetone, benzene and xylene, and the catalyst includes one of Fe, Co, Ni, Cu, Mo, Pt, Mn transition metals and compounds of Fe, Co, Ni, Cu, Mo, Pt, Mn transition metals.

[0021] In the preparation method of the carbon fiber-carbon nanotube thermal interface material, in the step of growing carbon nanotubes, the heating temperature of the 3D thermal conductive skeleton is 500-1200° C., and the growth time is 0.5-2 hours.

[0022] In the method for preparing the carbon fiber-carbon nanotube thermal interface material, in the polymer compounding step, the polymer matrix includes one of silicone rubber and silicone resin.

[0023] The present invention also provides a carbon fiber-carbon nanotube thermal interface material, and the carbon fiber-carbon nanotube thermal interface material is prepared by the above-mentioned method for preparing the carbon fiber-carbon nanotube thermal interface material.

[0024] A technical solution in the present invention can have the following beneficial effects:

[0025] The preparation method of the carbon fiber-carbon nanotube thermal interface material realizes carbon fiber orientation and composite carbon nanotubes, and the oriented carbon fiber forms a primary heat conduction network for direct heat conduction; and the carbon nanotubes grown in situ on the surface of the carbon fiber form a secondary heat conduction network, which connects the oriented carbon fiber to assist heat conduction, and constructs a double heat conduction network. Through the synergistic effect of the double heat conduction network, the in-plane thermal conductivity and the through-plane thermal conductivity of the composite material are improved. At the same time, a polymer matrix is ​​used as a matrix, which can fully squeeze out the air in the gap between the chip and the package, effectively reduce the contact thermal resistance between the chip and the package, and improve the thermal conductivity of the thermal interface material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a preparation flow chart of one embodiment of the present invention. DETAILED DESCRIPTION

[0027] The technical scheme of the present invention is further illustrated by specific embodiments below. In order to facilitate understanding of the present invention, the present invention is described more comprehensively below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0028] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] Please refer to Figure 1The present invention provides a method for preparing a carbon fiber-carbon nanotube thermal interface material, comprising the following steps:

[0031] Pretreatment of carbon fiber: pickling and drying the carbon fiber;

[0032] Modification of carbon fiber: mixing the acid-washed carbon fiber with tetraethyl silicate in an organic solvent, then filtering out the organic solvent and drying; then heating the carbon fiber mixed with tetraethyl silicate to obtain silicon-modified carbon fiber;

[0033] Carbon fiber orientation: The orientation of silicon-modified carbon fiber is changed by applying an external physical field, so that the silicon-modified carbon fiber forms a 3D thermal conductive skeleton;

[0034] Growth of carbon nanotubes: firstly, a protective gas and a reducing gas are introduced to place the 3D thermally conductive skeleton in an atmosphere of the protective gas and the reducing gas; then, the 3D thermally conductive skeleton is heated, and a mixed liquid of a carbon source and a catalyst is introduced to grow carbon nanotubes on the 3D thermally conductive skeleton, thereby obtaining a carbon fiber-carbon nanotube skeleton;

[0035] Polymer composite: The polymer matrix is ​​vacuum impregnated into the carbon fiber-carbon nanotube skeleton, and the mixture is cured to obtain the carbon fiber-carbon nanotube thermal interface material.

[0036] The thermal conductive skeleton of the carbon fiber-carbon nanotube thermal interface material is composed of carbon fiber-carbon nanotube fillers to achieve the purpose of thermal conductivity. Through the composite polymer, an elastic polymer is wrapped around the periphery of the thermal conductive skeleton, so that the carbon fiber-carbon nanotube thermal interface material can fill the gap between the chip and the package, avoiding the existence of air between the chip and the package, thereby improving the thermal conductivity.

[0037] Through the modification step of carbon fiber, the carbon fiber can better absorb the catalyst, thereby increasing the number and length of carbon nanotubes grown. In a specific embodiment of the present invention, the carbon fiber is placed in a tube furnace and heated, and the organic solvent is specifically anhydrous ethanol, so that tetraethyl silicate is pyrolyzed to generate silicon dioxide, which is adsorbed on the surface of the carbon fiber.

[0038] Before the carbon fiber forms an ordered thermal conductive network, the thermal conductive skeleton of the thermal interface material is randomly arranged, and the heat is randomly transferred in the material, which cannot effectively transfer heat. After the carbon fiber orientation step, an ordered thermal conductive network is formed, and the heat is transferred along the filler arrangement direction, effectively transferring heat and improving the thermal conductivity of the material.

[0039] The preparation method of the carbon fiber-carbon nanotube thermal interface material realizes carbon fiber orientation and composite carbon nanotubes, and the oriented carbon fiber forms a primary heat conduction network for direct heat conduction; and the carbon nanotubes grown in situ on the surface of the carbon fiber form a secondary heat conduction network, which connects the oriented carbon fiber to assist heat conduction, and constructs a double heat conduction network. Through the synergistic effect of the double heat conduction network, the in-plane thermal conductivity and the through-plane thermal conductivity of the composite material are improved. At the same time, a polymer matrix is ​​used as a matrix, which can fully squeeze out the air in the gap between the chip and the package, effectively reduce the contact thermal resistance between the chip and the package, and improve the thermal conductivity of the thermal interface material.

[0040] The carbon fiber-carbon nanotube thermal interface material obtained by the above-mentioned preparation method of the carbon fiber-carbon nanotube thermal interface material can be applied in the fields of thermal engineering and electronics. As a thermal conductive material for electronic components, it can be used to improve the efficiency of heat energy transfer and effectively reduce thermal resistance to ensure the stability and performance of the equipment in high temperature environments.

[0041] In a specific embodiment of the present invention, the organic solvent in the step of modifying the carbon fiber is specifically anhydrous ethanol, and the heating equipment is a tubular furnace. By heating, tetraethyl silicate is pyrolyzed to generate silicon dioxide, which is adsorbed on the surface of the carbon fiber. In the step of growing carbon nanotubes, argon is used as a protective gas and hydrogen is used as a reducing gas. The 3D thermal conductive skeleton is in an atmosphere of protective gas and reducing gas, which can avoid the problem of oxidation of the 3D thermal conductive skeleton under heating conditions.

[0042] Specifically, the aspect ratio of the carbon fiber is 100 to 500. With the aspect ratio, compared with carbon fibers with a smaller aspect ratio, the contact thermal resistance between the carbon fibers is reduced, and heat can be directly conducted through the carbon fibers.

[0043] Specifically, in the step of growing carbon nanotubes, the carbon source gas and catalyst powder are directly introduced into the 3D carbon fiber skeleton through a pipeline, and the introduction direction of the carbon source gas and catalyst powder is the same as the orientation direction of the carbon fiber.

[0044] The orientation direction of the carbon fiber should be kept parallel to the direction of carbon source gas introduction to ensure that the carbon source gas is in full contact with the carbon fiber, so as to grow higher quality carbon nanotubes and make the carbon nanotubes grow along the orientation direction of the carbon fiber, thereby realizing a secondary heat conduction network.

[0045] Further, in the step of pre-treating the carbon fiber, the pickling step includes:

[0046] The carbon fiber is mixed with the pickling liquid, and ultrasonically vibrated to obtain a mixed liquid containing the carbon fiber;

[0047] Adjusting the pH value of the mixed solution containing the carbon fibers to make the mixed solution neutral, and filtering out the carbon fibers in the mixed solution;

[0048] The drying step comprises: placing the filtered carbon fiber in anhydrous ethanol and performing ultrasonic dispersion; after ultrasonic dispersion, drying to completely volatilize the anhydrous ethanol to obtain acid-washed carbon fiber.

[0049] The above-mentioned pickling step can effectively remove dirt on the surface of the carbon fiber, making the surface of the carbon fiber cleaner. At the same time, the microstructure of the surface of the carbon fiber is adjusted to facilitate the subsequent modification of the carbon fiber. In a specific embodiment of the present invention, the pH adjustment step and the filtration step are specifically as follows: the mixed liquid mixed with the carbon fiber is poured into a suction filtration device, and the water pump filters the mixed liquid into the filter bottle, and then, distilled water is continuously poured in to rinse the carbon fiber and dilute it until the filtrate is neutral, and the carbon fiber remains on the filter membrane. The pickling solution is obtained from dilute sulfuric acid and concentrated nitric acid.

[0050] By adopting the above drying steps, moisture and solvent on the surface of the carbon fiber can be quickly removed, thereby improving the drying efficiency.

[0051] Furthermore, in the pickling step, the temperature of ultrasonic oscillation is 50-100°C, and the time of ultrasonic oscillation is 0.5-3h; in the drying step, the temperature of ultrasonic dispersion is 78.5-100°C, and the time of ultrasonic dispersion is 0.5-3h.

[0052] By using the above-mentioned ultrasonic oscillation and ultrasonic dispersion parameters, the dispersibility of the carbon fiber can be improved, the carbon fiber can be fully contacted with the pickling solution or alcohol, the surface roughness can be improved, and impurities can be effectively removed, which is beneficial to the subsequent growth of carbon nanotubes and the formation of the skeleton.

[0053] Specifically, in the step of orienting the carbon fibers, the externally applied physical field includes one of a temperature field, a magnetic field, an electric field and a force field.

[0054] When the external physical field is a temperature field, carbon fiber orientation is achieved by radial freeze casting, and the specific steps are: use liquid nitrogen to freeze vertically, and then put it into a freeze drying box to sublimate the ice. When the external physical field is a magnetic field, carbon fiber orientation is achieved by magnetic field orientation. When the external physical field is an electric field, carbon fiber orientation is achieved by electrospinning. When the external physical field is a force field, carbon fiber orientation is achieved by shear force flow. The above orientation methods are all existing technologies and will not be described here.

[0055] Specifically, in the step of growing carbon nanotubes, the carbon source includes one of methane, acetylene, ethanol, acetone, benzene and xylene, and the catalyst includes one of transition metals Fe, Co, Ni, Cu, Mo, Pt, Mn and compounds of transition metals Fe, Co, Ni, Cu, Mo, Pt, Mn.

[0056] In a specific embodiment of the present invention, the carbon source can be methane, acetylene, ethanol, acetone, benzene or xylene. The catalyst can be one of Fe, Co, Ni, Cu, Mo, Pt, Mn transition metals and their compounds.

[0057] The use of the above carbon source and catalyst is conducive to the rapid growth of carbon nanotubes.

[0058] Specifically, in the step of growing carbon nanotubes, the heating temperature of the 3D thermally conductive skeleton is 500-1200° C., and the growth time is 0.5-2 hours.

[0059] In a specific embodiment of the present invention, the oriented carbon fibers are placed in a tube furnace for heating at a temperature of 500 to 1200° C. for a growth time of 0.5 to 2 hours. With the above parameters, high-quality carbon nanotubes can be formed on the carbon fibers.

[0060] Specifically, in the polymer compounding step, the polymer matrix includes one of silicone rubber and silicone resin.

[0061] Silicone rubber and silicone resin are both highly elastic. Using silicone rubber or silicone resin as the matrix, the high deformation characteristics of silicone rubber and silicone resin can be used to bring carbon fiber-carbon nanotube thermal interface materials. The air in the gap between the chip and the package can be fully squeezed out, effectively reducing the contact thermal resistance between the chip and the package, and improving the thermal conductivity of the thermal interface material.

[0062] The present invention provides a carbon fiber-carbon nanotube thermal interface material, and the carbon fiber-carbon nanotube thermal interface material is prepared by the above-mentioned method for preparing the carbon fiber-carbon nanotube thermal interface material.

[0063] Example 1

[0064] A method for preparing a carbon fiber-carbon nanotube thermal interface material comprises the following steps:

[0065] Pretreatment of carbon fiber: mix the carbon fiber with the pickling solution and perform ultrasonic oscillation at a temperature of 100°C for 0.5h; obtain a mixed solution mixed with carbon fiber; pour the mixed solution mixed with carbon fiber into a suction filtration device, and use a water pump to filter the mixed solution into a filter bottle, then continuously pour distilled water to rinse and dilute the carbon fiber until the filtrate is neutral and the carbon fiber remains on the filter membrane; place the filtered carbon fiber in anhydrous ethanol and perform ultrasonic dispersion at a temperature of 78.5°C for 3h; after ultrasonic dispersion, dry the anhydrous ethanol to completely volatilize the anhydrous ethanol to obtain the pickled carbon fiber; wherein the pickling solution is obtained by mixing dilute sulfuric acid and concentrated nitric acid;

[0066] Modification of carbon fiber: the acid-washed carbon fiber is mixed with tetraethyl silicate in anhydrous ethanol, the anhydrous ethanol is filtered and dried naturally; the carbon fiber mixed with tetraethyl silicate is then placed in a tube furnace for heating to obtain silicon-modified carbon fiber;

[0067] Carbon fiber orientation: The orientation of silicon-modified carbon fiber is changed by applying an external temperature field; radial freeze casting is adopted, that is, liquid nitrogen is used to vertically freeze the carbon fiber, and then the ice is sublimated in a freeze drying box, so that the silicon-modified carbon fiber forms a 3D thermal conductive skeleton;

[0068] Growth of carbon nanotubes: The 3D thermally conductive skeleton is placed in a tubular furnace, and argon and hydrogen are first introduced to place the 3D thermally conductive skeleton in an atmosphere of protective gas and reducing gas; the 3D thermally conductive skeleton is then placed in a tubular furnace for heating at a temperature of 850°C and a growth time of 0.5h; and a mixture of xylene and ferrocene is injected along the orientation direction of the carbon fiber using an injection pump to grow carbon nanotubes on the 3D thermally conductive skeleton, thereby obtaining a carbon fiber-carbon nanotube skeleton;

[0069] Polymer composite: Silicone rubber is mixed with a carbon fiber-carbon nanotube skeleton under vacuum conditions, and the mixture is cured to obtain a carbon fiber-carbon nanotube thermal interface material.

[0070] The aspect ratio of the carbon fiber is 110, the carbon source is xylene, and the catalyst is ferrocene.

[0071] Example 2

[0072] The steps of Example 2 are the same as those of Example 1, except that: the aspect ratio of the carbon fiber is 110; in the step of pretreatment of the carbon fiber, the temperature of ultrasonic oscillation is 50°C, and the time of ultrasonic oscillation is 3 hours; the temperature of ultrasonic dispersion is 100°C, and the time of ultrasonic dispersion is 0.5 hours; in the step of growing carbon nanotubes, the heating temperature is 1200°C, and the growth time is 0.5 hours.

[0073] Example 3

[0074] The steps of Example 3 are the same as those of Example 1, except that: the aspect ratio of the carbon fiber is 500; in the step of pretreatment of the carbon fiber, the temperature of ultrasonic oscillation is 75°C, and the time of ultrasonic oscillation is 1.5 h; the temperature of ultrasonic dispersion is 85°C, and the time of ultrasonic dispersion is 2 h; in the step of growing carbon nanotubes, the heating temperature is 500°C, and the growth time is 2 h.

[0075] Comparative Example 1

[0076] The steps of Comparative Example 1 are the same as those of Example 1, except that in the step of growing carbon nanotubes, a mixed solution of xylene and ferrocene is injected in a direction perpendicular to the orientation direction of the carbon fibers.

[0077] Comparative Example 2

[0078] The steps of Comparative Example 2 are substantially the same as those of Example 1, except that the step of modifying the carbon fibers is not performed in the preparation steps of Comparative Example 2.

[0079] Comparative Example 3

[0080] The steps of Comparative Example 3 are substantially the same as those of Example 1, except that the step of growing carbon nanotubes is not performed in the preparation steps of Comparative Example 3.

[0081] The thermal interface materials obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were tested for thermal conductivity, including thermal conductivity in the length direction and thermal conductivity in the thickness direction. The test results are shown in Table 1.

[0082] Table 1 - Thermal conductivity test results of various embodiments

[0083]

[0084] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific embodiments of the present invention without creative work, and these equivalent variations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A method for preparing a carbon fiber-carbon nanotube thermal interface material, characterized in that: The following steps are involved: Pretreatment of carbon fiber: pickling and drying the carbon fiber; Modification of carbon fiber: mixing the acid-washed carbon fiber with tetraethyl silicate in an organic solvent, then filtering out the organic solvent and drying; then heating the carbon fiber mixed with tetraethyl silicate to obtain silicon-modified carbon fiber; Carbon fiber orientation: The orientation of silicon-modified carbon fiber is changed by applying an external physical field, so that the silicon-modified carbon fiber forms a 3D thermal conductive skeleton; Growth of carbon nanotubes: firstly, a protective gas and a reducing gas are introduced to place the 3D thermally conductive skeleton in an atmosphere of the protective gas and the reducing gas; then, the 3D thermally conductive skeleton is heated, and a mixed liquid of a carbon source and a catalyst is introduced to grow carbon nanotubes on the 3D thermally conductive skeleton, thereby obtaining a carbon fiber-carbon nanotube skeleton; Polymer composite: The polymer matrix is ​​vacuum impregnated into the carbon fiber-carbon nanotube skeleton, and the mixture is cured to obtain the carbon fiber-carbon nanotube thermal interface material.

2. The method for preparing a carbon fiber-carbon nanotube thermal interface material according to claim 1, characterized in that: The aspect ratio of the carbon fiber is 100-500.

3. The method for preparing a carbon fiber-carbon nanotube thermal interface material according to claim 1, characterized in that: In the step of growing carbon nanotubes, the carbon source gas and catalyst powder are directly introduced into the 3D carbon fiber skeleton through a pipeline, and the introduction direction of the carbon source gas and catalyst powder is the same as the orientation direction of the carbon fiber.

4. The method for preparing a carbon fiber-carbon nanotube thermal interface material according to claim 1, characterized in that: In the step of pre-treating the carbon fiber, the pickling step includes: The carbon fiber is mixed with the pickling liquid, and ultrasonically vibrated to obtain a mixed liquid containing the carbon fiber; Adjusting the pH value of the mixed solution containing the carbon fibers to make the mixed solution neutral, and filtering out the carbon fibers in the mixed solution; The drying step comprises: placing the filtered carbon fiber in anhydrous ethanol and performing ultrasonic dispersion; after ultrasonic dispersion, drying to completely volatilize the anhydrous ethanol to obtain acid-washed carbon fiber.

5. The method for preparing a carbon fiber-carbon nanotube thermal interface material according to claim 4, characterized in that: In the pickling step, the temperature of ultrasonic oscillation is 50-100°C, and the time of ultrasonic oscillation is 0.5-3h; in the drying step, the temperature of ultrasonic dispersion is 78.5-100°C, and the time of ultrasonic dispersion is 0.5-3h.

6. The method for preparing a carbon fiber-carbon nanotube thermal interface material according to claim 1, characterized in that: In the step of orienting the carbon fibers, the externally applied physical field includes one of a temperature field, a magnetic field, an electric field and a force field.

7. The method for preparing a carbon fiber-carbon nanotube thermal interface material according to claim 1, characterized in that: In the step of growing carbon nanotubes, the carbon source includes one of methane, acetylene, ethanol, acetone, benzene and xylene, and the catalyst includes one of transition metals Fe, Co, Ni, Cu, Mo, Pt, Mn and compounds of transition metals Fe, Co, Ni, Cu, Mo, Pt, Mn.

8. The method for preparing a carbon fiber-carbon nanotube thermal interface material according to claim 1, characterized in that: In the step of growing carbon nanotubes, the heating temperature of the 3D thermally conductive skeleton is 500 to 1200° C., and the growth time is 0.5 to 2 hours.

9. The method for preparing a carbon fiber-carbon nanotube thermal interface material according to claim 1, characterized in that: In the polymer compounding step, the polymer matrix includes one of silicone rubber and silicone resin.

10. A carbon fiber-carbon nanotube thermal interface material, characterized in that: The carbon fiber-carbon nanotube thermal interface material is prepared by the method for preparing the carbon fiber-carbon nanotube thermal interface material according to any one of claims 1 to 9.

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