Heat-conducting interface material as well as preparation method and application thereof

Abstract

The invention discloses a heat-conducting interface material and a preparation method and application thereof.The heat-conducting interface material comprises graphene, carbon nanotubes and a high-molecular polymer matrix, by means of the method, filler can be evenly dispersed and bridged in the matrix, a three-dimensional network chain structure in oriented arrangement is formed, and the heat-conducting interface material is prepared. Therefore, the phase interface thermal resistance in the composite system is reduced, the spatial orientation of the anisotropic carbon-based nano material filler in the matrix is accurate and controllable, and the design requirements of high-efficiency heat-conducting interface materials with different orientations are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal conductive materials, and in particular relates to a thermal conductive interface material and a preparation method and application thereof. Background Art

[0002] With the rapid development of artificial intelligence and autonomous driving technologies, deep data learning and precise image processing require hardware support from high-performance integrated circuits. Electronic components (CPUs, GPUs, and GaN field-effect transistors) are moving towards higher performance, integration, and miniaturization. This leads to increased energy and power density in devices, and increased system power consumption. This places new demands on efficient heat removal and thermal management technologies. Inadequate heat dissipation in electronic devices can reduce performance (throttling, stagnation), shorten service life, affect device stability, increase failure rates, and pose a safety hazard to personnel due to thermal runaway. Thermal failure is the primary mode of electronic device failure, with 55% of electronic device failures caused by excessive temperatures.

[0003] Heat removal from electronic components primarily utilizes passive thermal management techniques, relying on non-dynamic materials and devices for heat transfer. This involves transferring heat generated by the components to a heat sink via thermal conduction. Due to machining precision limitations, the rigid contact surface between the heat source and heat sink contains tiny pores and uneven grooves invisible to the naked eye, significantly reducing the contact area and thermal path between the two components. Air fills these pores, creating interfacial thermal resistance due to its low thermal conductivity (0.026 W / (m•K)). This slows heat flow across the contact surface and reduces thermal conductivity.

[0004] To improve the passive thermal management performance of electronic components, thermal interface materials (TIMs) are often used to facilitate heat transfer between the heat source and the heat sink, reducing internal heat transfer resistance and ensuring rapid and uniform heat flow across the interface. Due to their excellent compressible deformation properties, TIMs can fill tiny gaps and pores between the heat source and heat sink, removing air trapped in these pores, reducing interfacial thermal resistance, and improving thermal conductivity.

[0005] In addition to high thermal conductivity, thermal interface materials must also possess excellent mechanical properties, electrical insulation, and a high breakdown voltage to meet the demands of their intended use. Polymers, with their excellent insulation, fatigue resistance, chemical resistance, ease of molding, and low cost, have been widely used in thermal management of electronic components. Common polymers include epoxy resins, acrylates, polyurethanes, polyimides, and polytetrafluoroethylene. Pure polymers are saturated systems, lacking free electron flow. Phonons act as thermal energy carriers, and heat conduction relies on the vibrations of atoms, groups, or chain links. Due to the low crystallinity of polymers and the phonon scattering caused by anharmonic lattice vibrations, the microstructural regularity of polymers is far lower than that of metals and inorganic amorphous materials. Consequently, polymers have very low thermal conductivity, with a coefficient of thermal conductivity below 0.5 W / (m·K). This performance is 500–1000 times lower than that of metals and inorganic materials, making them inadequate for industrial applications in electronic component heat dissipation.

[0006] Therefore, existing thermal interface materials need to be improved. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. The present invention provides a thermal interface material and a preparation method and application thereof, wherein the thermal interface material has excellent thermal conductivity.

[0008] In a first aspect of the present invention, a method for preparing a thermally conductive interface material is provided. According to an embodiment of the present invention, the method comprises: (1) Weighing carbon nanotubes and graphene separately to obtain a mixed thermal conductive filler; (2) performing a first mixing of the mixed thermal conductive filler and the solvent to obtain a first slurry; (3) grafting the first slurry with a first coupling agent, and then performing a second mixing with magnetite powder to obtain a second slurry; (4) performing a third mixing of the second slurry, the surfactant, the second coupling agent, and the auxiliary agent, and then performing a first drying to obtain a third slurry; (5) performing a fourth mixing of the third slurry, the high molecular weight polymer, and the curing agent, and then performing a defoaming treatment to obtain an injection molding slurry; (6) The molding slurry is injected into a mold, and then an external magnetic field is applied to perform magnetic field orientation and solidification, and then a second drying is performed to obtain a thermal conductive interface material.

[0009] In some embodiments, in step (1), the mass ratio of the carbon nanotubes to the graphene is 1:(1-3), for example, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc.

[0010] In some embodiments, the graphene includes one or more of two-dimensional single-layer graphene, double-layer graphene, few-layer graphene, and multi-layer graphene.

[0011] In some embodiments, the carbon nanotubes are one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0012] In some embodiments, in step (2), the solid-liquid ratio of the mixed thermal conductive filler and the solvent is 1 g: (20-40) mL, for example, 1 g: 25 mL, 1 g: 30 mL, etc.

[0013] In some embodiments, the solvent includes one or more of ethanol, ethyl acetate, and acetone.

[0014] In some embodiments, the first mixing comprises: stirring at 500-1000 rpm for 12-24 hours, followed by ultrasonication at 20-50 kHz for 8-16 hours.

[0015] In some embodiments, in step (3), the first coupling agent includes one or more of KH-570, A-171, and Z-6030. By adding the first coupling agent, the thermal conductive filler and the magnetite powder can be coupled.

[0016] In some embodiments, the mixing ratio of the mixed thermally conductive filler and the first coupling agent is 1 g: (10-30) mL, for example, 1 g: 15 mL, 1 g: 20 mL, 1 g: 25 mL, etc.

[0017] In some embodiments, the mixing ratio of the mixed thermal conductive filler and the magnetite powder is 1:(5-10), preferably 1:6, 1:7, 1:8, 1:9, etc.

[0018] In some embodiments, the magnetite powder has a particle size of 100 nm to 1 μm.

[0019] In some embodiments, the pH value of the grafting treatment is 4-6.

[0020] In some embodiments, the second mixing comprises: stirring at 400-800 rpm for 3-6 hours, followed by ultrasonication at 20-50 kHz for 8-12 hours.

[0021] In some embodiments, in step (4), based on 1g of the mixed thermally conductive filler, the added amount of the surfactant is 1-5g, for example, 1.5g, 2g, 2.5g, 3g, 3.5g, 4g, 4.5g, etc., the added amount of the second coupling agent is 1-3g, for example, 1.5g, 2g, 2.5g, etc., and the added amount of the auxiliary agent is 0.5-2g, for example, 1g, 1.5g, etc.

[0022] The inventors found that by using a surfactant to modify the surface of the thermally conductive filler, the second coupling agent couples the modified thermally conductive filler and the high molecular polymer matrix, and at the same time, under the action of the auxiliary agent, the compatibility of the thermally conductive filler and the polymer matrix is enhanced.

[0023] In some embodiments, the surfactant includes one or more of polypropylene, polyethylene wax, and polyethylene glycol.

[0024] In some embodiments, the second coupling agent includes one or more of silane, titanate, and aluminate.

[0025] In some embodiments, the auxiliary agent includes one or more of acrylic acid and maleic acid.

[0026] In some embodiments, the third mixing comprises: stirring at 500-1000 rpm for 6-12 hours.

[0027] In some embodiments, the first drying comprises: drying at 40-60° C. for 3-8 hours.

[0028] In some embodiments, in step (5), the mass ratio of the mixed thermal conductive filler to the high molecular polymer is 1:(10-15), for example, 1:11, 1:12, 1:13, 1:14, etc.

[0029] In some embodiments, the mass ratio of the mixed thermal conductive filler to the curing agent is 1:(3-5), for example, 1:3.5, 1:4, 1:4.5, etc.

[0030] In some embodiments, the high molecular weight polymer includes one or more of epoxy resin and acrylate.

[0031] In some embodiments, the curing agent includes one or more of diethylenetriamine, m-phenylenediamine, and phthalic anhydride.

[0032] In some embodiments, the fourth mixing comprises: stirring at 800-2000 rpm for 6-12 hours, and then ultrasonicating at 40-80 kHz for 3-6 hours.

[0033] In some embodiments, in step (6), the magnetic field strength of the external magnetic field is 0.2-0.8 T, and the action time is 12-24 hours.

[0034] In some embodiments, the second drying comprises: drying at 50-60° C. for 24-48 hours.

[0035] In a second aspect of the present invention, the present invention provides a thermally conductive interface material, which is prepared by the above method.

[0036] In some embodiments, the distribution of the thermal interface material is anisotropic.

[0037] In some embodiments, the vertical thermal conductivity of the thermal interface material is 1.0-1.8 W / (m·K), for example, 1.2 W / (m·K), 1.3 W / (m·K), 1.4 W / (m·K), 1.5 W / (m·K), 1.6 W / (m·K), 1.7 W / (m·K), etc.

[0038] In some embodiments, the horizontal thermal conductivity of the thermal interface material is 2.0-3.5 W / (m·K), for example, 2.1 W / (m·K), 2.2 W / (m·K), 2.3 W / (m·K), 2.4 W / (m·K), 2.5 W / (m·K), 2.6 W / (m·K), 2.7 W / (m·K), 2.8 W / (m·K), 2.9 W / (m·K), 3.0 W / (m·K), 3.1 W / (m·K), 3.2 W / (m·K), 3.3 W / (m·K), 3.4 W / (m·K), etc. Thus, the thermal interface material can have excellent both horizontal and vertical thermal conductivity.

[0039] In some embodiments, the room temperature resistivity of the thermal interface material is 600-1200 ohm·cm, for example, 650 ohm·cm, 700 ohm·cm, 750 ohm·cm, 800 ohm·cm, 850 ohm·cm, 900 ohm·cm, 950 ohm·cm, 1000 ohm·cm, 1050 ohm·cm, 1100 ohm·cm, 1150 ohm·cm, etc.

[0040] In a third aspect of the present invention, the present invention provides a use of the above-mentioned thermal interface material in electronic components.

[0041] The present invention has the following beneficial effects: (1) Nano-sized magnetite powder (Fe3O4) was loaded on the surface of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) through grafting to obtain carbon-based composite magnetic materials Fe3O4@CNTs and Fe3O4@GNPs. This allows the fillers to have paramagnetic / antimagnetic response characteristics and can be oriented in the magnetic field under the action of a conventional external magnetic field strength, thus solving the problem that carbon-based non-magnetic materials (CNTs and GNPs) cannot be directly oriented in the magnetic field.

[0042] (2) Using magnetically treated hybrid carbon-based nanomaterials (Fe3O4@CNTs and Fe3O4@GNPs) to replace single carbon-based nanomaterials (CNTs, GNPs) and polymer matrices to prepare high thermal conductivity composite polymers, the interfacial thermal resistance caused by the bending and entanglement of CNTs and the agglomeration of GNPs microsheets is reduced, and a three-dimensional network structure of carbon chain-carbon network bridges is formed. Through innovative composite material design processes, the filling mass ratio of CNTs and GNPs fillers is optimized to explore new thermal conductivity structures of composite polymers. The preparation of composite thermal conductive polymers with hybrid carbon-based nanomaterials (CNTs+GNPs) can better exert their coordination effect. CNTs can form a bridge structure with GNPs through van der Waals forces and π-π bonds, which is beneficial to phonon transmission. At the same time, the introduction of one-dimensional high aspect ratio CNTs into GNPs can effectively inhibit the stacking and aggregation between two-dimensional graphene sheets.

[0043] (3) By using surface modifiers, second coupling agents and additives to modify the surface of carbon-based nanomaterials (CNTs, GNPs), chemical reactions occur on the surface lattice particles of the carbon-based nanomaterials, electron transfer or electron sharing occurs between the particles participating in the reaction, and strong bonds such as ionic bonds, covalent bonds or coordination bonds are formed on the surface of the powder, thereby achieving chemical adsorption. After post-treatment, surface-active carbon-based nanofillers are obtained. The modified carbon-based nanofillers are mixed with a polymer matrix to prepare a composite thermal conductive polymer. The compatibility between the filler and the matrix is enhanced, the uniform dispersion and bonding performance of the inorganic-organic composite system is improved, and the agglomeration effect between the fillers is reduced, solving the problem that high thermal conductivity carbon-based nanofillers are difficult to form a stable and complete three-dimensional thermal conductive network structure in the composite system.

[0044] (4) By applying a conventional magnetic field to induce orientation, the orientation arrangement of magnetic hybrid carbon-based nanofillers (Fe3O4@CNTs and Fe3O4@GNPs) in the polymer matrix is precisely controlled. Since the magnetic orientation of magnetic hybrid carbon-based nanofillers depends on the synergistic effect of van der Waals force, electrostatic force and magnetic field force in the composite system, the effects of iron powder addition, magnetic field magnetization intensity and magnetic field magnetization direction on thermal conductivity and micromorphology are optimized. According to the thermal conductivity orientation requirements of thermal conductive interface materials, paramagnetic magnetization, reverse magnetic magnetization and paramagnetic-reverse magnetic coupling magnetization induced orientation methods are used respectively to prepare hybrid carbon-based oriented thermal conductive polymers with excellent horizontal average thermal conductivity, vertical thermal conductivity and horizontal-vertical synergistic thermal conductivity, thereby meeting the design requirements of high-efficiency thermal conductive interface materials with different orientations.

[0045] In summary, the thermally conductive interface material of the present invention includes a mixed thermally conductive filler (graphene and carbon nanotubes) and a high molecular polymer matrix. The method of the present invention can achieve uniform dispersion and bridging of the filler in the matrix, and form an oriented three-dimensional network chain structure, thereby reducing the phase interface thermal resistance in the composite system and achieving precise and controllable spatial orientation of the anisotropic carbon-based nanomaterial filler in the matrix, meeting the design requirements of high-efficiency thermally conductive interface materials with different orientations.

[0046] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 These are physical pictures of the blank sample, Example 1, Example 3, Comparative Example 1, and Comparative Example 3 of the present invention.

[0048] Figure 2 These are SEM images of the materials prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 4 of the present invention.

[0049] Figure 3 Schematic diagram of the preparation method of the interface thermal conductive material of Example 1 of the present invention. DETAILED DESCRIPTION

[0050] The present invention is described below with reference to specific examples. It should be noted that these examples are merely illustrative and do not limit the present invention in any way. In the following examples and comparative examples, unless otherwise specified, the raw materials used are common commercial products that can be directly purchased in the art or prepared according to conventional methods available in the art. Unless otherwise specified, the mixing or reaction temperature is room temperature.

[0051] Multi-walled carbon nanotube powder was purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., with an average diameter of 50 nm and a length of 0.5-2 μm; few-layer graphene microsheets were purchased from Shenzhen Hongdachang Technology Evolution Co., Ltd., with a particle size (D 50 ) 7~10μm, 1~3 layers; high-purity quartz sand powder (SiO2 purity 99.93%, particle size (D 50 ) 45μm) was taken from the quartz concentrate product provided by Chongqing Geology and Mineral Resources Testing Center.

[0052] Example 1 (1) Weigh 0.4 g of multi-walled carbon nanotube powder and few-layer graphene microsheets (mass ratio 1:1) as a mixed thermal conductive filler; (2) Add 0.4 g of mixed thermal conductive filler and 8 mL of ethyl acetate to a beaker, stir at 800 rpm for 12 h, and then ultrasonically disperse at 30 kHz for 8 h to pre-wet and obtain a first slurry; (3) 4 mL of KH-570 was added to the first slurry at a ratio of 1:10 for grafting, and the pH value was adjusted to 6. Subsequently, 100 nm magnetite powder was added to the mixed solution at a mass ratio of 1:5 (mixed thermal conductive filler: magnetite powder), stirred at 500 rpm for 3 h, and then ultrasonically dispersed at 20 kHz for 8 h to obtain the second slurry; (4) 1.5 g of polyethylene glycol, 2.5 g of titanate, and 1.5 g of acrylic acid were added to the second slurry for surface modification. The mixture was stirred at 500 rpm for 12 h at room temperature, and then heated and dried in a blast drying oven to eliminate the remaining organic solvent. The heating temperature was set to 60 ° C and the drying time was 5 h to obtain a third slurry. (5) Add 6 g of epoxy resin and 2 g of phthalic anhydride to the third slurry, stir at 1000 rpm for 6 h at room temperature, then ultrasonically disperse at 30 kHz for 3 h, and then place in a vacuum drying oven and defoam at -0.1 MPa for 1 h at room temperature to obtain an injection molding slurry; (6) Pour the injection molding slurry into the cylindrical silicone mold to 1 / 2 of the height, shake the silicone mold slowly to make the internal slurry raw material fill evenly and the upper liquid surface flat, place the silicone mold on the stage of the magnetic field induced orientation experimental device, the stage is located in the middle area of the top-bottom magnet holder, install a cylindrical neodymium iron boron magnet with a magnetic field strength of 0.6T on the magnet holder, rotate the fine-tuning screw to adjust the distance between the top and bottom magnets, install the top magnet holder in the positive direction to obtain the NS paramagnetic magnetic field, and orient the injection molding slurry under the induction of the magnetic field for 12 hours; remove it from the stage Remove the silicone mold, continue to pour the injection molding slurry raw material into the silicone mold, fill the remaining 1 / 2 height of the mold, slowly shake the silicone mold to make the internal slurry raw material evenly filled and the upper liquid surface flat, place the silicone mold on the stage, install the top magnet holder in reverse to obtain the NN reverse magnetic field, and orient the injection molding slurry under the induction of the magnetic field and solidify it for 12 hours; finally, place the silicone mold containing the injection molding slurry in a blast drying oven, dry and harden it at 60°C for 24 hours to obtain a horizontal-vertical synergistic thermal conductive mixed carbon-based orientation thermal interface material.

[0053] The schematic diagram of the preparation method of the interface thermal conductive material of Example 1 is as follows Figure 3 shown.

[0054] Example 2 Step (6) is changed to: pour the injection molding slurry raw material into the cylindrical silicone mold, slowly shake the silicone mold so that the internal slurry raw material is evenly filled and the upper liquid surface is flat, place the silicone mold on the stage of the magnetic field induced orientation experimental device, the stage is located in the middle area of the top-bottom magnet holder, install a cylindrical neodymium iron boron magnet with a magnetic field strength of 0.6T on the magnet holder, rotate the fine-tuning screw to adjust the spacing between the top and bottom magnets, adjust the positive and negative installation direction of the top magnet holder according to the vertical heat conduction requirements of the thermal conductive composite polymer product, obtain NS paramagnetism, orient the injection molding slurry under the action of magnetic field induction and solidify for 12 hours, finally place the silicone mold containing the injection molding slurry in a blast drying oven, dry and harden at 60°C for 24 hours, and obtain a vertically conductive mixed carbon-based orientation thermal conductive polymer.

[0055] Other details are the same as in Example 1.

[0056] Example 3 Step (1) was changed to: weigh 0.4 g of multi-walled carbon nanotube powder and few-layer graphene microsheets (mass ratio 1:3) and put them into a beaker, pour ethyl acetate into the beaker at a solid-liquid ratio of 1:20, stir at 800 rpm for 12 h, and then ultrasonically disperse at 30 kHz for 8 h to pre-wet and obtain a first slurry; Other details are the same as in Example 2.

[0057] Comparative Example 1 Step (1) was changed to: weigh 0.4 g of multi-walled carbon nanotube powder and put it into a beaker, pour ethyl acetate into the beaker at a solid-liquid ratio of 1:20, stir at 800 rpm for 12 h, and then ultrasonically disperse at 30 kHz for 8 h to pre-wet and obtain a first slurry; Other details are the same as in Example 2.

[0058] Comparative Example 2 Step (1) was changed to: weigh 0.4 g of few-layer graphene microsheets and put them into a beaker, pour ethyl acetate into the beaker at a solid-liquid ratio of 1:20, stir at 800 rpm for 12 h, and then ultrasonically disperse at 30 kHz for 8 h to pre-wet and obtain a first slurry; Other details are the same as in Example 2.

[0059] Comparative Example 3 Step (1) was changed to: weigh 0.4 g of high-purity quartz sand powder and put it into a beaker, pour ethyl acetate into the beaker at a solid-liquid ratio of 1:20, stir at 800 rpm for 12 h, and then ultrasonically disperse at 30 kHz for 8 h to pre-wet and obtain a first slurry; Other details are the same as in Example 2.

[0060] Comparative Example 4 Step (1) was changed to: weigh 0.4 g of multi-walled carbon nanotube powder and few-layer graphene microsheets (mass ratio 1:7) and put them into a beaker, pour ethyl acetate into the beaker at a solid-liquid ratio of 1:20, stir at 800 rpm for 12 h, and then ultrasonically disperse at 30 kHz for 8 h to pre-wet and obtain a first slurry; Other details are the same as in Example 2.

[0061] The addition amounts of carbon nanotube powder, graphene microsheets, high-purity quartz sand powder, magnetite powder, and epoxy resin in each embodiment and comparative example are shown in Table 1, and other conditions are the same as in Example 1.

[0062] Comparative Example 5 Step (3) was changed to: adjust the pH value of the first slurry to 6, add 100 nm magnetite powder to the first slurry at a mass ratio of 1:5 (mixed thermal conductive filler: magnetite powder), stir at 500 rpm for 3 h, and then ultrasonically disperse at 20 kHz for 8 h to obtain a second slurry. The rest was the same as in Example 2.

[0063] Comparative Example 6 Step (4) was changed to: add 1.5 g of polyethylene glycol and 1.5 g of acrylic acid to the second slurry, stir at 500 rpm for 12 h at room temperature, and then heat and dry in a forced air drying oven to eliminate the remaining organic solvent. The heating temperature was set to 60°C and the drying time was 5 h to obtain a third slurry. The rest was the same as in Example 2.

[0064] Table 1

[0065] The actual pictures of blank sample, Example 1, Example 3, Comparative Example 1 and Comparative Example 3 are as follows Figure 1 As shown, the blank sample is a pure epoxy resin sample obtained by reference to steps (5) to (6) of Example 2, and the SEM images of the materials prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 4 are shown in FIG. Figure 2 As shown, it can be seen that as the proportion of carbon nanotubes in the mixed thermal conductive filler increases, the proportion of graphene microsheets agglomerated in the matrix decreases.

[0066] The thermal conductivity of the thermal interface materials prepared in the above examples and comparative examples was tested, and the horizontal / vertical thermal diffusivity of the materials was detected using a laser thermal conductivity meter. α , Differential Scanning Calorimetry to Determine the Specific Heat Capacity of Materials c p , weighing method to determine density ρ , based on the formula λ=α·c p ·ρ The horizontal / vertical thermal conductivity λ of the thermal interface material is calculated, and the results are shown in Table 2: Table 2

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that it is still possible to modify the technical solutions described in the aforementioned embodiments, or to make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a thermally conductive interface material, characterized in that: The method comprises: (1) Weighing carbon nanotubes and graphene separately to obtain a mixed thermal conductive filler; (2) performing a first mixing of the mixed thermal conductive filler and the solvent to obtain a first slurry; (3) grafting the first slurry with a first coupling agent, and then performing a second mixing with magnetite powder to obtain a second slurry; (4) performing a third mixing of the second slurry, the surfactant, the second coupling agent, and the auxiliary agent, and then performing a first drying to obtain a third slurry; (5) performing a fourth mixing of the third slurry, the high molecular weight polymer, and the curing agent, and then performing a defoaming treatment to obtain an injection molding slurry; (6) The molding slurry is injected into a mold, and then an external magnetic field is applied to perform magnetic field orientation and solidification, and then a second drying is performed to obtain a thermal conductive interface material.

2. The method according to claim 1, characterized in that In step (1), the mass ratio of the carbon nanotubes to the graphene is 1:(1-3); and / or, The graphene includes one or more of two-dimensional single-layer graphene, double-layer graphene, few-layer graphene and multi-layer graphene; and / or, The carbon nanotubes are one or more of single-walled carbon nanotubes, double-walled carbon nanotubes and multi-walled carbon nanotubes.

3. The method according to claim 1, characterized in that In step (2), the first mixing comprises: stirring at 500-1000 rpm for 12-24 hours, followed by ultrasonication at 20-50 kHz for 8-16 hours; and / or, The solid-liquid ratio of the mixed thermal conductive filler and the solvent is 1g:(20-40)mL; and / or, The solvent includes one or more of ethanol, ethyl acetate and acetone.

4. The method according to claim 1, wherein In step (3), the first coupling agent includes one or more of KH-570, A-171 and Z-6030; and / or, The mixing ratio of the mixed thermally conductive filler and the first coupling agent is 1g: (10-30)mL; and / or, The mass ratio of the mixed thermal conductive filler to the magnetite powder is 1:(5-10); and / or, The particle size of the magnetite powder is 100 nm~1 μm; and / or, The second mixing includes: stirring at 400-800 rpm for 3-6 hours, and then ultrasonicating at 20-50 kHz for 8-12 hours.

5. The method according to claim 1, wherein In step (4), based on 1g of the mixed thermal conductive filler, the added amount of the surfactant is 1-5g, the added amount of the second coupling agent is 1-3g, and the added amount of the auxiliary agent is 0.5-2g; and / or, The surfactant comprises one or more of polypropylene, polyethylene wax and polyethylene glycol; and / or, The second coupling agent includes one or more of silane, titanate, and aluminate; and / or, The auxiliary agent includes one or more of acrylic acid and maleic acid; and / or, The third mixing comprises: stirring at 500-1000 rpm for 6-12 hours; and / or, The first drying comprises: drying at 40-60° C. for 3-8 hours.

6. The method according to claim 1, characterized in that In step (5), the mass ratio of the mixed thermal conductive filler to the high molecular polymer is 1:(10-15); and / or, The mass ratio of the mixed thermal conductive filler to the curing agent is 1:(3-5); and / or, The high molecular polymer includes one or more of epoxy resin and acrylate; and / or, The curing agent includes one or more of diethylenetriamine, m-phenylenediamine and phthalic anhydride; and / or, The fourth mixing includes: stirring at 800-2000 rpm for 6-12 hours, and then ultrasonicating at 40-80 kHz for 3-6 hours.

7. The method according to claim 1, characterized in that In step (6), the magnetic field strength of the external magnetic field is 0.2-0.8 T, and the action time is 12-24 hours; and / or, The second drying comprises: drying at 50-60° C. for 24-48 hours.

8. A thermally conductive interface material prepared by the method according to any one of claims 1 to 7, characterized in that: The distribution of the thermal conductive interface material is anisotropic.

9. The thermal interface material according to claim 8, wherein: The vertical thermal conductivity of the thermal interface material is 1.0-1.8 W / (m·K); and / or, The horizontal thermal conductivity of the thermal interface material is 2.0-3.5 W / (m·K); and / or, The room temperature resistivity of the thermal interface material is 600-1200 ohm·cm.

10. Use of the thermal interface material according to claim 8 or 9 in electronic components.

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