A thermally conductive interface material and its preparation method and application

Abstract

The application discloses a kind of heat-conducting interface materials and its preparation method and application, the heat-conducting interface material includes graphene, carbon nanotube and polymer polymer matrix, the method of the application can realize filler in matrix uniform dispersion bridge, and three-dimensional net chain structure of orientation arrangement is formed, so as to reduce the interfacial thermal resistance in composite system, realize the orientation precision controllable of each anisotropic carbon-based nanomaterial filler in matrix space, satisfy the design requirement of different orientation high-efficiency heat-conducting interface material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of heat-conducting materials, and particularly relates to a heat-conducting interface material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of artificial intelligence and automobile automatic driving technology, data deep learning and image accurate processing need high-performance integrated circuits for hardware support, and electronic components (CPU, GPU, GaN field effect transistor) are developing towards high performance, integration and miniaturization, resulting in increased energy and power density of equipment and increased system power consumption, which puts forward new requirements for high-efficiency heat removal and heat management technology. Insufficient heat dissipation of electronic equipment will reduce the performance of the equipment (frequency reduction, vibration), shorten the service life, affect the stability of the equipment, increase the failure rate, and thermal runaway will also bring personal safety hazards. Thermal failure is the main failure mode of electronic equipment, and 55% of the failure rate of electronic equipment is caused by high temperature.

[0003] Electronic components and devices mainly use passive thermal management technology to transfer heat through non-powered materials and devices, that is, to conduct the heat generated by the components and devices to the heat sink through heat conduction. The heat source and the heat sink are in contact with each other. Due to the limitation of machining precision, the rigid contact surface will have tiny pores and uneven grooves that cannot be observed with the naked eye, greatly reducing the contact area and heat conduction path of the two element surfaces. Air fills the gap holes. Since the thermal conductivity of air is low (0.026 W / (m•K)), it produces interface thermal resistance, causing slow heat flow conduction and poor thermal conductivity of the contact surface.

[0004] To improve the passive thermal management performance of electronic components, a heat-conducting interface material (TIMs, Thermal Interface Materials) is usually used to conduct heat between the heat-generating module and the heat dissipation device, to reduce the internal heat transfer resistance, and to quickly and uniformly conduct heat flow at the contact surface. Based on the excellent compressible deformation characteristics of TIMs, the tiny gaps and holes on the contact surface of the heat source and the heat sink can be filled, the air in the holes can be removed, the interface thermal resistance can be reduced, and the thermal conductivity can be improved.

[0005] In addition to the need for high thermal conductivity, the thermal interface material also needs to have excellent mechanical properties, electrical insulation and high breakdown voltage to meet the working condition requirements. High molecular polymer has good insulation performance, fatigue resistance, chemical corrosion resistance, easy forming processing and low cost, and has been widely used in the thermal management of electronic components. Common high molecular polymers include epoxy resin, acrylate, polyurethane, polyimide and polytetrafluoroethylene. Pure polymer belongs to a saturated system without free electron flow movement. Phonon is the carrier of thermal energy, and thermal conduction depends on the vibration of atoms, groups or chain segments. Due to the low crystallinity of high molecular polymer and the phonon scattering caused by non-harmonic vibration of crystal lattice, the microstructure regularity is much lower than that of metal and inorganic non-crystal, so the thermal conductivity of polymer is very low, and the thermal conductivity is less than 0.5 W / (m·K). The thermal conductivity of polymer is 500-1000 times lower than that of metal and inorganic materials, which cannot meet the industrial application in the field of electronic component heat dissipation.

[0006] Therefore, the existing thermal interface material needs to be improved. SUMMARY

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

[0008] In the first aspect of the present application, a method for preparing a thermal interface material is provided. According to an embodiment of the present application, the method comprises:

[0009] (1) carbon nanotubes and graphene are weighed respectively to obtain a mixed thermal conductive filler;

[0010] (2) the mixed thermal conductive filler and the solvent are first mixed to obtain a first slurry;

[0011] (3) the first slurry is subjected to grafting treatment with a first coupling agent, and then subjected to second mixing with magnetite powder to obtain a second slurry;

[0012] (4) the second slurry, a surfactant, a second coupling agent and an additive are third mixed, and then first dried to obtain a third slurry;

[0013] (5) the third slurry, a high molecular polymer and a curing agent are fourth mixed, and then subjected to defoaming treatment to obtain an injection molding slurry;

[0014] (6) the injection molding slurry is injected into a mold, and then subjected to magnetic field orientation and curing by applying an external magnetic field, and then subjected to second drying to obtain a thermal interface material.

[0015] In some embodiments, in step (1), the mass ratio of the carbon nanotubes and the graphene is 1: (1-3). For example, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc.

[0016] In some embodiments, the graphene comprises one or more of two-dimensional single-layer graphene, double-layer graphene, few-layer graphene, and multi-layer graphene.

[0017] In some embodiments, the carbon nanotubes are one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0018] In some embodiments, in step (2), the solid-liquid ratio of the mixed thermally conductive filler and the solvent is 1 g: (20-40) mL, for example, 1 g:25 mL, 1 g:30 mL, etc.

[0019] In some embodiments, the solvent comprises one or more of ethanol, ethyl acetate, and acetone.

[0020] In some embodiments, the first mixing comprises stirring at 500-1000 rpm for 12-24 h, followed by 20-50 kHz ultrasonic for 8-16 h.

[0021] In some embodiments, in step (3), the first coupling agent comprises one or more of KH-570, A-171, and Z-6030. By adding the first coupling agent, the thermally conductive filler and the magnetite powder can be coupled.

[0022] 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.

[0023] In some embodiments, the mixing ratio of the mixed thermally conductive filler and the magnetite powder is 1: (5-10), preferably 1:6, 1:7, 1:8, 1:9, etc.

[0024] In some embodiments, the particle size of the magnetite powder is 100 nm-1 μm.

[0025] In some embodiments, the pH value of the grafting treatment is 4-6.

[0026] In some embodiments, the second mixing comprises stirring at 400-800 rpm for 3-6 h, followed by 20-50 kHz ultrasonic for 8-12 h.

[0027] In some embodiments, in step (4), the amount of the surfactant added is 1-5 g, such as 1.5 g, 2 g, 2.5 g, 3 g, 3.5 g, 4 g, 4.5 g, etc., the amount of the second coupling agent added is 1-3 g, such as 1.5 g, 2 g, 2.5 g, etc., and the amount of the auxiliary agent added is 0.5-2 g, such as 1 g, 1.5 g, etc., based on 1 g of the mixed thermally conductive filler.

[0028] The inventors have 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 polymer matrix, and under the action of the auxiliary agent, the compatibility of the thermally conductive filler and the polymer matrix is enhanced.

[0029] In some embodiments, the surfactant includes one or more of polypropylene, polyethylene wax, and polyethylene glycol.

[0030] In some embodiments, the second coupling agent includes one or more of silane, titanate, and aluminate.

[0031] In some embodiments, the auxiliary agent includes one or more of acrylic acid and maleic acid.

[0032] In some embodiments, the third mixing includes stirring at 500-1000 rpm for 6-12 h.

[0033] In some embodiments, the first drying includes drying at 40-60 °C for 3-8 h.

[0034] In some embodiments, in step (5), the mass ratio of the mixed thermally conductive filler to the high polymer is 1:(10-15), such as 1:11, 1:12, 1:13, 1:14, etc.

[0035] In some embodiments, the mass ratio of the mixed thermally conductive filler to the curing agent is 1:(3-5), such as 1:3.5, 1:4, 1:4.5, etc.

[0036] In some embodiments, the high polymer includes one or more of epoxy resin and acrylate.

[0037] In some embodiments, the curing agent includes one or more of diethylenetriamine, m-phenylenediamine, and phthalic anhydride.

[0038] In some embodiments, the fourth mixing includes stirring at 800-2000 rpm for 6-12 h, and then ultrasonicating at 40-80 kHz for 3-6 h.

[0039] In some embodiments, in step (6), the magnetic field strength of the applied magnetic field is 0.2-0.8 T, and the action time is 12-24 h.

[0040] In some embodiments, the second drying comprises drying at 50-60℃ for 24-48 h.

[0041] In a second aspect, the present application provides a thermal interface material prepared by the above method.

[0042] In some embodiments, the thermal interface material has an anisotropic distribution.

[0043] In some embodiments, the thermal interface material has a vertical thermal conductivity of 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.

[0044] In some embodiments, the thermal interface material has a horizontal thermal conductivity of 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 horizontal and vertical thermal conductivity.

[0045] In some embodiments, the thermal interface material has a room temperature resistivity of 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.

[0046] In a third aspect, the present application provides use of the above thermal interface material in electronic components.

[0047] The present application has the following advantages:

[0048] (1) Through the grafting effect on the surface of carbon nanotubes (CNTs) and graphene microsheets (GNPs), nano-sized magnetite powder (Fe3O4) is loaded to obtain carbon-based composite magnetic materials Fe3O4@CNTs and Fe3O4@GNPs, so that the filler has the characteristics of parallel and reverse magnetic response, and can be oriented in the magnetic field under the action of conventional external magnetic field strength, solving the problem that carbon-based non-magnetic materials (CNTs and GNPs) cannot be directly oriented in the magnetic field.

[0049] (2) The hybrid carbon-based nanomaterials (Fe3O4@CNTs and Fe3O4@GNPs) after magnetic treatment are used to replace single carbon-based nanomaterials (CNTs, GNPs) to prepare high-thermal-conductivity composite polymers with polymer matrix, reducing the interfacial thermal resistance caused by the bending and winding of CNTs and the agglomeration of GNPs microsheets, and forming a three-dimensional network structure connected by carbon chains and carbon bridges. Through innovative composite material design process, the filling quality ratio of CNTs and GNPs is optimized, and the new heat conduction architecture of composite polymers is explored. The hybrid carbon-based nanomaterials (CNTs+GNPs) can better play the coordination effect in the preparation of composite heat-conducting polymers. CNTs can form a bridging structure with GNPs through van der Waals force and π-π bond, 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 accumulation and aggregation between two-dimensional graphene sheets.

[0050] (3) Through the surface modification of carbon-based nanomaterials (CNTs, GNPs) by using surface modifiers, second coupling agents and additives, chemical reactions occur on the surface lattice particles of carbon-based nanomaterials, and electron transfer or electron sharing occurs between the participating particles, forming strong bonds such as ionic bonds, covalent bonds or coordination bonds on the surface of the powder, thereby realizing chemical adsorption, and then through post-processing, carbon-based nanofillers with surface activity are obtained. The modified carbon-based nanofillers are mixed with the polymer matrix to prepare composite heat-conducting polymers, the compatibility between the fillers and the matrix is strengthened, the uniform dispersion and bonding performance of the inorganic-organic composite system are 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 heat-conducting network structure in the composite system.

[0051] (4) By the external conventional magnetic field induced orientation effect, the orientation arrangement of the magnetized hybrid carbon-based nanofillers (Fe3O4@CNTs and Fe3O4@GNPs) in the polymer matrix is precisely controlled. Since the magnetization orientation of the magnetized hybrid carbon-based nanofillers depends on the synergistic effect of the van der Waals force, electrostatic force and magnetic force in the composite system, the effects of the iron powder addition amount, magnetic field magnetization strength and magnetic field magnetization direction on the thermal conductivity and micro-morphology are optimized. According to the orientation requirements of the thermal conductive interface material, the paramagnetic magnetization, inverse magnetic magnetization and paramagnetic-inverse magnetic coupling magnetization induced orientation methods can be used to prepare the hybrid carbon-based oriented thermal conductive polymers with excellent horizontal thermal conductivity, vertical thermal conductivity and horizontal-vertical synergistic thermal conductivity, so as to meet the design requirements of the high-efficiency thermal conductive interface materials with different orientations.

[0052] In summary, the thermal conductive interface material of the present application comprises mixed thermal conductive fillers (graphene and carbon nanotubes) and a polymer matrix, and the method of the present application can realize uniform dispersion and bridging of the fillers in the matrix, and form an oriented three-dimensional network chain structure, thereby reducing the interfacial thermal resistance in the composite system, realizing the precise orientation control of the anisotropic carbon-based nanomaterial fillers in the matrix space, and meeting the design requirements of the high-efficiency thermal conductive interface materials with different orientations.

[0053] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 The physical diagrams of the blank sample, example 1, example 3, comparative example 1, comparative example 3 of the present application.

[0055] Figure 2 The SEM diagrams of the materials prepared in example 1, example 2, example 3, comparative example 1, comparative example 2, comparative example 4 of the present application.

[0056] Figure 3 The schematic diagram of the preparation method of the interface thermal conductive material of example 1 of the present application. DETAILED DESCRIPTION

[0057] The present application will be described below with reference to specific examples, and it should be noted that these examples are merely descriptive and do not limit the present application in any way. In the following examples and comparative examples, the raw materials used are ordinary commercially available products or are prepared according to the conventional methods in the art, unless otherwise specified. The mixing or reaction temperature is room temperature, unless otherwise specified.

[0058] Multi-walled carbon nanotube powder was purchased from Jiangsu Xianfeng Nanometer Material Technology Co., Ltd., with an average diameter of 50 nm and a length of 0.5-2 μm; few-layer graphene microflakes were purchased from Shenzhen Hongdachang Science and Technology Co., Ltd., with a particle size (D 50 ) of 7-10 μm and 1-3 layers; high-purity quartz sand powder (SiO2purity 99.93%, particle size (D 50 ) 45 μm) was taken from the quartz concentrate product provided by Chongqing Geological and Mineral Testing Center.

[0059] Example 1

[0060] (1) 0.4 g of multi-walled carbon nanotube powder and few-layer graphene microflakes (mass ratio 1:1) were weighed as a mixed thermal conductive filler;

[0061] (2) 0.4 g of the mixed thermal conductive filler and 8 mL of ethyl acetate were added to a beaker, stirred at 800 rpm for 12 h, and then ultrasonically dispersed at 30 kHz for 8 h to obtain a first slurry by pre-wetting;

[0062] (3) 4 mL of KH-570 was added to the first slurry at a ratio of 1:10 for grafting treatment, the pH value was adjusted to 6, and then 100 nm of 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 a second slurry;

[0063] (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 treatment, first stirred at 500 rpm for 12 h at room temperature, and then heated and dried in a forced air drying oven to eliminate residual organic solvents, with a heating temperature setting of 60°C and a drying time of 5 h to obtain a third slurry;

[0064] (5) 6 g of epoxy resin and 2 g of phthalic anhydride were added to the third slurry, stirred at 1000 rpm for 6 h at room temperature, and then ultrasonically dispersed at 30 kHz for 3 h, followed by placement in a vacuum drying oven for 1 h of defoaming treatment at room temperature and -0.1 MPa to obtain a mold injection slurry;

[0065] (6) Pour the injection molding slurry into the cylindrical silica gel mold to 1 / 2 height, slowly shake the silica gel mold to make the internal slurry material fill evenly, the upper liquid surface is flat, place the silica gel mold on the sample stage of the magnetic field induction orientation experiment device, the sample stage is located in the middle region of the top-bottom end magnet holder, install a cylindrical neodymium-iron-boron magnet with a magnetic field strength of 0.6 T on the magnet holder, adjust the distance between the top and bottom magnets by rotating the fine adjustment screw, and install the top magnet holder in the forward direction to obtain an N-S paramagnetic magnetic field. The injection molding slurry is oriented and arranged under the action of the magnetic field and solidified for 12 h; remove the silica gel mold from the sample stage, continue to pour the injection molding slurry into the silica gel mold, fill the remaining 1 / 2 height of the mold, slowly shake the silica gel mold to make the internal slurry material fill evenly, the upper liquid surface is flat, place the silica gel mold on the sample stage, install the top magnet holder in the reverse direction to obtain an N-N inverse magnetic field, and the injection molding slurry is oriented and arranged under the action of the magnetic field and solidified for 12 h; finally, place the silica gel mold containing the injection molding slurry in a forced air drying oven, dry and harden at a temperature of 60°C for 24 h, and obtain a hybrid carbon-based oriented thermal interface material with horizontal-vertical cooperative thermal conduction.

[0066] The schematic diagram of the preparation method of the interface thermal conductive material of Example 1 is shown in Figure 3 .

[0067] Example 2

[0068] Step (6) is changed to: pour the injection molding slurry into the cylindrical silica gel mold, slowly shake the silica gel mold to make the internal slurry material fill evenly, the upper liquid surface is flat, place the silica gel mold on the sample stage of the magnetic field induction orientation experiment device, the sample stage is located in the middle region of the top-bottom end magnet holder, install a cylindrical neodymium-iron-boron magnet with a magnetic field strength of 0.6 T on the magnet holder, adjust the distance between the top and bottom magnets by rotating the fine adjustment screw, and adjust the installation direction of the top magnet holder according to the vertical thermal conduction requirement of the thermal conductive composite polymer product, to obtain an N-S paramagnetic magnetic field. The injection molding slurry is oriented and arranged under the action of the magnetic field and solidified for 12 h, and finally the silica gel mold containing the injection molding slurry is placed in a forced air drying oven, dried and hardened at a temperature of 60°C for 24 h, to obtain a vertical thermal conductive hybrid carbon-based oriented thermal conductive polymer.

[0069] The others are the same as Example 1.

[0070] Example 3

[0071] Step (1) is changed to: weigh 0.4 g of multi-walled carbon nanotube powder and few-layer graphene microsheet (mass ratio 1:3) into a beaker, pour ethyl acetate into the beaker according to a solid-liquid ratio of 1:20, stir at 800 rpm for 12 h, and then perform 30 kHz ultrasonic dispersion for 8 h to obtain a first slurry;

[0072] The others are the same as Example 2.

[0073] Comparative Example 1

[0074] Step (1) was changed to: 0.4 g of multi-walled carbon nanotube powder was weighed into a beaker, and ethyl acetate was poured into the beaker according to a solid-liquid ratio of 1:20, stirred at 800 rpm for 12 h, and then 30 kHz ultrasonic dispersion for 8 h to obtain a first slurry by pre-wetting;

[0075] The others were the same as in Example 2.

[0076] Comparative Example 2

[0077] Step (1) was changed to: 0.4 g of few-layer graphene microsheet was weighed into a beaker, and ethyl acetate was poured into the beaker according to a solid-liquid ratio of 1:20, stirred at 800 rpm for 12 h, and then 30 kHz ultrasonic dispersion for 8 h to obtain a first slurry by pre-wetting;

[0078] The others were the same as in Example 2.

[0079] Comparative Example 3

[0080] Step (1) was changed to: 0.4 g of high-purity quartz sand powder was weighed into a beaker, and ethyl acetate was poured into the beaker according to a solid-liquid ratio of 1:20, stirred at 800 rpm for 12 h, and then 30 kHz ultrasonic dispersion for 8 h to obtain a first slurry by pre-wetting;

[0081] The others were the same as in Example 2.

[0082] Comparative Example 4

[0083] Step (1) was changed to: 0.4 g of multi-walled carbon nanotube powder and few-layer graphene microsheet (mass ratio 1:7) were weighed into a beaker, and ethyl acetate was poured into the beaker according to a solid-liquid ratio of 1:20, stirred at 800 rpm for 12 h, and then 30 kHz ultrasonic dispersion for 8 h to obtain a first slurry by pre-wetting;

[0084] The others were the same as in Example 2.

[0085] The addition amounts of carbon nanotube powder, graphene microsheet, high-purity quartz sand powder, magnetite powder, and epoxy resin in each example and comparative example were shown in Table 1, and other conditions were the same as in Example 1.

[0086] Comparative Example 5

[0087] Step (3) was changed to: the pH value of the first slurry was adjusted to 6, 100 nm magnetite powder was added to the first slurry according to a mass ratio (mixed thermal conductive filler:magnetite powder) of 1:5, stirred at 500 rpm for 3 h, and then 20 kHz ultrasonic dispersion for 8 h to obtain a second slurry, and the others were the same as in Example 2.

[0088] Comparative Example 6

[0089] Step (4) was changed to: 1.5 g of polyethylene glycol and 1.5 g of acrylic acid were added to the second slurry, and stirring was first carried out at 500 rpm for 12 h at room temperature, and then residual organic solvents were eliminated by heating and drying in a blast drying oven, with the heating temperature set to 60℃ and the drying time set to 5 h, to obtain a third slurry, and the other steps were the same as in Example 2.

[0090] Table 1

[0091]

[0092] The actual photos of the blank sample, Example 1, Example 3, Comparative Example 1 and Comparative Example 3 are shown in Figure 1 , wherein the blank sample is a pure epoxy resin sample prepared according to steps (5) to (6) of Reference 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 Figure 2 , and it can be seen that as the proportion of carbon nanotubes in the mixed thermal conductive filler increases, the proportion of graphene microsheet agglomeration in the matrix decreases.

[0093] The thermal conductivity of the thermal interface material prepared in the above examples and comparative examples was tested, and the horizontal / vertical thermal diffusivity of the material was detected by a laser thermal conductivity instrument α , the specific heat capacity of the material was determined by a differential scanning calorimeter c p , the density was determined by a weighing method p , and the horizontal / vertical thermal conductivity λ of the thermal interface material was calculated based on the formula λ = a - c p - p , and the results are shown in Table 2:

[0094] Table 2

[0095]

[0096] The above examples are only used to illustrate the technical solutions of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

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) injecting the injection molding slurry into a mold, applying an external magnetic field for magnetic field orientation and curing, and then performing a second drying to obtain a thermal conductive interface material; In step (3), the mass ratio of the mixed thermal conductive filler to the magnetite powder is 1:(5-10); In step (1), the mass ratio of the carbon nanotubes to the graphene is 1:(1-3).

2. The method according to claim 1, characterized in that 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 thermal conductive filler and the first coupling agent is 1g: (10-30)mL; 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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