AFG-based ultrahigh longitudinal heat-conducting film integrated with micro-cone array

Abstract

The invention discloses an AFG-based ultrahigh longitudinal heat conduction film integrated with a micro-cone array. The AFG-based ultrahigh longitudinal heat conduction film comprises the following components in parts by mass: 60-75 parts of annealed flexible graphite micro powder; 8 to 12 parts of a functionalized boron nitride nanotube; 5 to 9 parts of a silicon carbide nanowire-silver nanoparticle core-shell structure; 3 to 6 parts of a polydopamine-graphene quantum dot interface modifier; 4 to 7 parts of ionic liquid modified polyimide nanofiber; 2 to 4 parts of a polyvinyl butyral binder; 150 to 250 parts of an acetone-isopropanol mixed solvent; heat conduction components are guided to be directionally arranged through the micro-cone array template, meanwhile, a silicon carbide nanowire-silver nanoparticle core-shell structure is introduced, the silver nanoparticles are high in heat conduction coefficient, can serve as a longitudinal heat conduction bridge and cooperate with the micro-cone array to form a continuous three-dimensional heat conduction network, the longitudinal heat conduction coefficient is increased compared with a traditional graphite film, and the heat conduction performance of the graphite film is improved. And the core requirement of vertical heat dissipation of the electronic equipment is met.

Description

Technical Field

[0001] This invention belongs to the field of thermal conductive materials technology, specifically an AFG-based ultra-high longitudinal thermal conductivity film with an integrated microcone array. Background Technology

[0002] As electronic devices continue to evolve towards miniaturization and higher performance, the heat generated by their internal electronic components during operation increases dramatically. If this heat cannot be dissipated effectively and promptly, it will cause the temperature of the electronic device to rise, affecting the performance, stability, and lifespan of the electronic components, and in severe cases, even leading to device malfunction. Therefore, efficient heat dissipation technology has become one of the key factors in the development of electronic devices, and thermal conductive films, as important heat dissipation materials, play a crucial role in this process.

[0003] While existing graphite-based thermally conductive films possess excellent in-plane thermal conductivity, their longitudinal thermal conductivity is generally low, severely limiting their application in convection cooling scenarios. Traditional improvement methods, such as adding boron nitride or carbon nanotubes, have some effect, but suffer from the following drawbacks:

[0004] 1) The random orientation of one-dimensional filler leads to discontinuities in the longitudinal heat conduction path;

[0005] 2) The interface thermal resistance between the inorganic filler and the graphite matrix is ​​large;

[0006] 3) No directional three-dimensional heat conduction channels were constructed.

[0007] Based on this, an AFG-based ultra-high longitudinal thermal conductivity film with an integrated microcone array was designed. Summary of the Invention

[0008] In view of the above situation and to overcome the defects of the prior art, the present invention provides an AFG-based ultra-high longitudinal thermal conductivity film with integrated microcone array and its preparation method, which effectively solves the problems mentioned in the background.

[0009] To achieve the above objectives, the present invention provides the following technical solution: an AFG-based ultra-high longitudinal thermal conductivity film with an integrated microcone array, comprising the following components by mass:

[0010] Annealed flexible graphite powder: 60-75 parts;

[0011] Functionalized boron nitride nanotubes: 8-12 parts;

[0012] Silicon carbide nanowire-silver nanoparticle core-shell structure: 5-9 parts;

[0013] Polydopamine-graphene quantum dot interface modifier: 3-6 parts;

[0014] Ionic liquid modified polyimide nanofibers: 4-7 parts;

[0015] Polyvinyl butyral adhesive: 2-4 parts;

[0016] Acetone-isopropanol mixed solvent: 150-250 parts.

[0017] Preferably, the annealed flexible graphite micropowder has a particle size of 15-25 μm and a carbon content of ≥99.9%;

[0018] In the acetone-isopropanol mixed solvent, the volume ratio of acetone to isopropanol is 3:1;

[0019] In the silicon carbide nanowire-silver nanoparticle core-shell structure, the β-silicon carbide nanowires have a diameter of 50-80 nm, and the surface is covered with silver nanoparticles with a particle size of 5-10 nm, with a shell thickness of 8-15 nm.

[0020] Preferably, the preparation method of the silicon carbide nanowire-silver nanoparticle core-shell structure is as follows:

[0021] S1. Disperse 1.5-2.5g of silicon carbide nanowires in a mixture of 150-200mL of deionized water and 25-35mL of anhydrous ethanol, and treat with ultrasonic power of 450-600W for 25-35 minutes to form a uniform suspension.

[0022] S2. Under the conditions of stirring speed of 350-450 rpm and temperature of 55-65℃, add 0.8-1.2g of silver nitrate and 0.3-0.5g of trisodium citrate in sequence, purge with nitrogen for protection, and add 25-35mL of 0.1-0.2mol / L ascorbic acid solution dropwise, controlling the dropping rate to 1.5-2.5mL / min.

[0023] S3. Add 0.05-0.08g of polyvinylpyrrolidone, heat to 75-85℃, and stir continuously for 90-120 minutes.

[0024] S4. Centrifuge at 7500-8500 rpm for 8-12 minutes, wash three times with deionized water and anhydrous ethanol, and vacuum dry at 65-75℃ and -0.09 to -0.1 MPa for 10-14 hours to obtain silicon carbide nanowire-silver nanoparticle core-shell structure powder.

[0025] Preferably, the preparation method of the polydopamine-graphene quantum dot interface modifier is as follows:

[0026] S1. Disperse 0.15-0.25g of graphene quantum dots in 180-220mL of Tris-HCl buffer solution, pH=8.3-8.7, concentration 8-12mmol / L, and sonicate for 15-25 minutes.

[0027] S2. Add 1.8-2.2g of dopamine hydrochloride, control the water bath temperature at 28-32℃, and stir continuously at 180-220rpm for 8-12 hours to allow dopamine to self-polymerize and graft graphene quantum dots.

[0028] S3. Add 0.03-0.05g of ammonium persulfate as an oxidant, heat to 38-42℃, and continue stirring for 1.5-2.5 hours to promote the formation of cross-linked networks;

[0029] S4. Dialysis purification: the molecular weight cutoff of the dialysis bag is 3500-4500 Da, the dialysis time is 36-48 hours, freeze drying is carried out at a cold trap temperature of -55 to -65℃, a vacuum degree of 10-20 Pa, and a time of 20-28 hours to obtain polydopamine-graphene quantum dot interface modifier solid powder.

[0030] Preferably, the preparation method of the ionic liquid modified polyimide nanofibers is as follows:

[0031] S1. Nanofibers are prepared by electrospinning a 12-16 wt% polyamic acid solution in N,N-dimethylacetamide as the solvent. Parameters: voltage 18-22 kV, receiving distance 15-20 cm, feed rate 0.8-1.2 mL / h, drum speed 150-250 rpm, and ambient humidity 35-45%.

[0032] S2. Gradual imidization of the fiber membrane in a vacuum oven: hold at 150-160℃ for 0.8-1.2 hours, hold at 220-240℃ for 0.8-1.2 hours, and finally raise the temperature to 320-340℃ and hold for 0.8-1.2 hours;

[0033] S3. Dissolve 0.8-1.2g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid in 40-60mL of anhydrous ethanol, add 0.3-0.5g of γ-aminopropyltriethoxysilane, and hydrolyze at 45-55℃ for 40-60 minutes to form an ionic liquid coupling agent solution.

[0034] S4. Immerse the polyimide nanofibers in the above solution, and ultrasonically assisted impregnate for 15-25 minutes. Then vacuum dry at 85-95℃ for 3-5 hours to obtain ionic liquid modified polyimide nanofibers.

[0035] Preferably, the thermally conductive template is prepared as follows:

[0036] S1. Fabrication of microcone array templates

[0037] A copper plate with a thickness of 0.3-0.5 mm is used to process an array of conical pits by laser etching. The pits have a depth of 100-150 μm, a top diameter of 80-120 μm, a bottom diameter of 40-60 μm, and an array spacing of 150-200 μm. The copper plate is then immersed in an 8-12 wt% oxalic acid solution and chemically polished at 45-55℃ for 15-25 minutes. After ultrasonic cleaning, it is used as a molding template.

[0038] S2, Preparation of composite slurry

[0039] S2.1 Mix 60-75 parts of annealed flexible graphite micro powder with 150-250 parts of acetone-isopropanol mixed solvent, with the solid content controlled at 25-35 wt%, and pre-disperse in a planetary mixer at an orbital speed of 35-45 rpm and a rotational speed of 800-1200 rpm for 15-25 minutes.

[0040] S2.2, sequentially add 8-12 parts of functionalized boron nitride nanotubes, 5-9 parts of silicon carbide nanowire-silver nanoparticle core-shell structure, 3-6 parts of polydopamine-graphene quantum dot interface modifier, and 4-7 parts of ionic liquid modified polyimide nanofibers. After each component is added, increase the rotation speed to 1500-2000 rpm and disperse at high speed for 8-12 minutes.

[0041] S2.3 Add 2-4 parts of polyvinyl butyral binder, reduce the rotation speed to 600-800 rpm, vacuum degassing, vacuum degree -0.08 to -0.095 MPa, time 25-35 minutes, to obtain a composite slurry with a viscosity of 3500-5500 mPa·s;

[0042] S3, Coating and Molding

[0043] The slurry obtained from S2 was applied to the surface of the S1 template using a doctor blade coating method. The doctor blade gap was controlled at 200-300 μm, the coating rate was 1.5-2.5 m / min, the ambient temperature was 22-28℃, and the relative humidity was ≤40%. Subsequently, the template was placed in a vacuum oven and pre-cured at 75-85℃ for 30-45 minutes, with the solvent evaporation rate controlled at 70-80%.

[0044] S4, Hot-press curing

[0045] The template with the slurry is placed into the hot press. From bottom to top, the layers are: template, composite coating, release film, and equalizing plate. The hot pressing process parameters are as follows:

[0046] First stage: Temperature 95-105℃, pressure 3-5MPa, pressure holding time 8-12 minutes;

[0047] Second stage: Temperature 155-165℃, pressure 8-12MPa, pressure holding time 15-20 minutes;

[0048] Third stage: Temperature 210-230℃, pressure 12-16MPa, pressure holding time 25-35 minutes;

[0049] The heating rate is 5-8℃ / min throughout the process, the cooling rate is 3-5℃ / min, and the pressure is released and the temperature is naturally cooled to room temperature.

[0050] S5, Demolding and Post-processing

[0051] The cured film is peeled off from the template and annealed in a tube furnace: under an argon atmosphere, the temperature is increased to 850-950℃ at a rate of 8-12℃ / min, held for 45-75 minutes, and then cooled to room temperature at a rate of 5-7℃ / min to obtain a final thermally conductive film with a thickness of 80-120μm.

[0052] Compared with the prior art, the beneficial effects of the present invention are:

[0053] 1. This invention guides the directional arrangement of thermally conductive components through a microcone array template, and introduces a silicon carbide nanowire-silver nanoparticle core-shell structure. The silver nanoparticles have a high thermal conductivity and can serve as a longitudinal "heat conduction bridge". Together with the microcone array, they form a continuous three-dimensional thermally conductive network, which improves the longitudinal thermal conductivity compared with traditional graphite films. This meets the core requirement of "vertical heat dissipation" for electronic devices and effectively solves the problem of low thermal conductivity caused by the random orientation of one-dimensional fillers in existing graphite-based thermally conductive films, which makes the longitudinal heat conduction path easy to break.

[0054] 2. This invention adds a polydopamine-graphene quantum dot interface modifier. In its molecular structure, the amino and hydroxyl groups of polydopamine can form chemical bonds with the surface of graphite powder and inorganic fillers, while graphene quantum dots fill the interface gaps. The two work together to reduce the interface thermal resistance, reduce the heat reflection and scattering loss at the interface, and ensure efficient heat transfer.

[0055] 3. Traditional thermal conductive films are prone to bending and breakage due to the brittleness of the matrix. This invention introduces ionic liquid modified polyimide nanofibers. On the one hand, polyimide nanofibers can serve as a "structural skeleton" to improve the tensile strength of the film material. On the other hand, the introduction of ionic liquids significantly optimizes the high and low temperature resistance of the film material, making it suitable for complex environments such as outdoor electronic devices and automotive electronics.

[0056] 4. Polyvinyl butyral binder is used, whose hydroxyl groups can form hydrogen bonds with the surface groups of annealed flexible graphite powder and functionalized boron nitride nanotubes. At the same time, it works synergistically with ionic liquid modified polyimide fibers to prevent component shedding during hot pressing and use, thus meeting the structural stability requirements for long-term use. Detailed Implementation

[0057] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] This invention provides an AFG-based ultra-high longitudinal thermal conductivity film with an integrated microcone array, comprising the following components in parts by weight:

[0059] Annealed flexible graphite powder: 60-75 parts;

[0060] Functionalized boron nitride nanotubes: 8-12 parts;

[0061] Silicon carbide nanowire-silver nanoparticle core-shell structure: 5-9 parts;

[0062] Polydopamine-graphene quantum dot interface modifier: 3-6 parts;

[0063] Ionic liquid modified polyimide nanofibers: 4-7 parts;

[0064] Polyvinyl butyral adhesive: 2-4 parts;

[0065] Acetone-isopropanol mixed solvent: 150-250 parts.

[0066] The annealed flexible graphite micropowder in this embodiment has a particle size of 15-25 μm and a carbon content of ≥99.9%.

[0067] In the acetone-isopropanol mixed solvent, the volume ratio of acetone to isopropanol is 3:1;

[0068] In the silicon carbide nanowire-silver nanoparticle core-shell structure, the β-silicon carbide nanowires have a diameter of 50-80 nm, and the surface is coated with silver nanoparticles with a particle size of 5-10 nm, with a shell thickness of 8-15 nm.

[0069] The preparation method of the silicon carbide nanowire-silver nanoparticle core-shell structure in this embodiment is as follows:

[0070] S1. Disperse 1.5-2.5g of silicon carbide nanowires in a mixture of 150-200mL of deionized water and 25-35mL of anhydrous ethanol, and treat with ultrasonic power of 450-600W for 25-35 minutes to form a uniform suspension.

[0071] S2. Under the conditions of stirring speed of 350-450 rpm and temperature of 55-65℃, add 0.8-1.2g of silver nitrate and 0.3-0.5g of trisodium citrate in sequence, purge with nitrogen for protection, and add 25-35mL of 0.1-0.2mol / L ascorbic acid solution dropwise, controlling the dropping rate to 1.5-2.5mL / min.

[0072] S3. Add 0.05-0.08g of polyvinylpyrrolidone, heat to 75-85℃, and stir continuously for 90-120 minutes.

[0073] S4. Centrifuge at 7500-8500 rpm for 8-12 minutes, wash three times with deionized water and anhydrous ethanol, and vacuum dry at 65-75℃ and -0.09 to -0.1 MPa for 10-14 hours to obtain silicon carbide nanowire-silver nanoparticle core-shell structure powder.

[0074] The preparation method of the polydopamine-graphene quantum dot interface modifier in this embodiment is as follows:

[0075] S1. Disperse 0.15-0.25g of graphene quantum dots in 180-220mL of Tris-HCl buffer solution, pH=8.3-8.7, concentration 8-12mmol / L, and sonicate for 15-25 minutes.

[0076] S2. Add 1.8-2.2g of dopamine hydrochloride, control the water bath temperature at 28-32℃, and stir continuously at 180-220rpm for 8-12 hours to allow dopamine to self-polymerize and graft graphene quantum dots.

[0077] S3. Add 0.03-0.05g of ammonium persulfate as an oxidant, heat to 38-42℃, and continue stirring for 1.5-2.5 hours to promote the formation of cross-linked networks;

[0078] S4. Dialysis purification: the molecular weight cutoff of the dialysis bag is 3500-4500 Da, the dialysis time is 36-48 hours, freeze drying is carried out at a cold trap temperature of -55 to -65℃, a vacuum degree of 10-20 Pa, and a time of 20-28 hours to obtain polydopamine-graphene quantum dot interface modifier solid powder.

[0079] The preparation method of ionic liquid modified polyimide nanofibers in this embodiment is as follows:

[0080] S1. Nanofibers are prepared by electrospinning a 12-16 wt% polyamic acid solution in N,N-dimethylacetamide as the solvent. Parameters: voltage 18-22 kV, receiving distance 15-20 cm, feed rate 0.8-1.2 mL / h, drum speed 150-250 rpm, and ambient humidity 35-45%.

[0081] S2. Gradual imidization of the fiber membrane in a vacuum oven: hold at 150-160℃ for 0.8-1.2 hours, hold at 220-240℃ for 0.8-1.2 hours, and finally raise the temperature to 320-340℃ and hold for 0.8-1.2 hours;

[0082] S3. Dissolve 0.8-1.2g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid in 40-60mL of anhydrous ethanol, add 0.3-0.5g of γ-aminopropyltriethoxysilane, and hydrolyze at 45-55℃ for 40-60 minutes to form an ionic liquid coupling agent solution.

[0083] S4. Immerse the polyimide nanofibers in the above solution, and ultrasonically assisted impregnate for 15-25 minutes. Then vacuum dry at 85-95℃ for 3-5 hours to obtain ionic liquid modified polyimide nanofibers.

[0084] The method for preparing the thermally conductive template in this embodiment is as follows:

[0085] S1. Fabrication of microcone array templates

[0086] A copper plate with a thickness of 0.3-0.5 mm is used to process an array of conical pits by laser etching. The pits have a depth of 100-150 μm, a top diameter of 80-120 μm, a bottom diameter of 40-60 μm, and an array spacing of 150-200 μm. The copper plate is then immersed in an 8-12 wt% oxalic acid solution and chemically polished at 45-55℃ for 15-25 minutes. After ultrasonic cleaning, it is used as a molding template.

[0087] S2, Preparation of composite slurry

[0088] S2.1 Mix 60-75 parts of annealed flexible graphite micro powder with 150-250 parts of acetone-isopropanol mixed solvent, with the solid content controlled at 25-35 wt%, and pre-disperse in a planetary mixer at an orbital speed of 35-45 rpm and a rotational speed of 800-1200 rpm for 15-25 minutes.

[0089] S2.2, sequentially add 8-12 parts of functionalized boron nitride nanotubes, 5-9 parts of silicon carbide nanowire-silver nanoparticle core-shell structure, 3-6 parts of polydopamine-graphene quantum dot interface modifier, and 4-7 parts of ionic liquid modified polyimide nanofibers. After each component is added, increase the rotation speed to 1500-2000 rpm and disperse at high speed for 8-12 minutes.

[0090] S2.3 Add 2-4 parts of polyvinyl butyral binder, reduce the rotation speed to 600-800 rpm, vacuum degassing, vacuum degree -0.08 to -0.095 MPa, time 25-35 minutes, to obtain a composite slurry with a viscosity of 3500-5500 mPa·s;

[0091] S3, Coating and Molding

[0092] The slurry obtained from S2 was applied to the surface of the S1 template using a doctor blade coating method. The doctor blade gap was controlled at 200-300 μm, the coating rate was 1.5-2.5 m / min, the ambient temperature was 22-28℃, and the relative humidity was ≤40%. Subsequently, the template was placed in a vacuum oven and pre-cured at 75-85℃ for 30-45 minutes, with the solvent evaporation rate controlled at 70-80%.

[0093] S4, Hot-press curing

[0094] The template with the slurry is placed into the hot press. From bottom to top, the layers are: template, composite coating, release film, and equalizing plate. The hot pressing process parameters are as follows:

[0095] First stage: Temperature 95-105℃, pressure 3-5MPa, pressure holding time 8-12 minutes;

[0096] Second stage: Temperature 155-165℃, pressure 8-12MPa, pressure holding time 15-20 minutes;

[0097] Third stage: Temperature 210-230℃, pressure 12-16MPa, pressure holding time 25-35 minutes;

[0098] The heating rate is 5-8℃ / min throughout the process, the cooling rate is 3-5℃ / min, and the pressure is released and the temperature is naturally cooled to room temperature.

[0099] S5, Demolding and Post-processing

[0100] The cured film is peeled off from the template and annealed in a tube furnace: under an argon atmosphere, the temperature is increased to 850-950℃ at a rate of 8-12℃ / min, held for 45-75 minutes, and then cooled to room temperature at a rate of 5-7℃ / min to obtain a final thermally conductive film with a thickness of 80-120μm.

[0101] Example 1:

[0102] An AFG-based ultra-high longitudinal thermal conductivity film with an integrated microcone array comprises the following components in parts by mass:

[0103] Annealed flexible graphite powder: 60 parts;

[0104] Functionalized boron nitride nanotubes: 8 parts;

[0105] Silicon carbide nanowire-silver nanoparticle core-shell structure: 5 parts;

[0106] Polydopamine-graphene quantum dot interface modifier: 3 parts;

[0107] Ionic liquid modified polyimide nanofibers: 4 parts;

[0108] Polyvinyl butyral adhesive: 2 parts;

[0109] Acetone-isopropanol mixed solvent: 150 parts.

[0110] The annealed flexible graphite micropowder in this embodiment has a particle size of 15-25 μm and a carbon content of ≥99.9%.

[0111] In the acetone-isopropanol mixed solvent, the volume ratio of acetone to isopropanol is 3:1;

[0112] In the silicon carbide nanowire-silver nanoparticle core-shell structure, the β-silicon carbide nanowires have a diameter of 50-80 nm, and the surface is coated with silver nanoparticles with a particle size of 5-10 nm, with a shell thickness of 8-15 nm.

[0113] The preparation method of the silicon carbide nanowire-silver nanoparticle core-shell structure in this embodiment is as follows:

[0114] S1. Disperse 1.5g of silicon carbide nanowires in a mixture of 150mL of deionized water and 25mL of anhydrous ethanol, and treat with ultrasonic power of 450W for 25 minutes to form a uniform suspension.

[0115] S2. Under the conditions of stirring speed of 350 rpm and temperature of 55℃, add 0.8 g silver nitrate and 0.3 g trisodium citrate in sequence, purge with nitrogen for protection, and add 25 mL of 0.1 mol / L ascorbic acid solution dropwise, controlling the dropping rate to 1.5 mL / min.

[0116] S3. Add 0.05g of polyvinylpyrrolidone, heat to 75℃, and stir continuously for 90 minutes.

[0117] S4. Centrifuge at 7500 rpm for 8 minutes, wash three times with deionized water and anhydrous ethanol, and vacuum dry at 65℃ and -0.09 MPa for 10 hours to obtain silicon carbide nanowire-silver nanoparticle core-shell structure powder.

[0118] The preparation method of the polydopamine-graphene quantum dot interface modifier in this embodiment is as follows:

[0119] S1. Disperse 0.15g of graphene quantum dots in 180mL of Tris-HCl buffer solution, pH=8.3, concentration 8mmol / L, and sonicate for 15 minutes.

[0120] S2. Add 1.8g of dopamine hydrochloride, control the water bath temperature at 28℃, and stir continuously at 180rpm for 8 hours to allow dopamine to self-polymerize and graft graphene quantum dots.

[0121] S3. Add 0.03g of ammonium persulfate as an oxidant, heat to 38℃, and continue stirring for 1.5 hours to promote the formation of cross-linked networks;

[0122] S4. Dialysis purification: the molecular weight cutoff of the dialysis bag is 3500-4500 Da, the dialysis time is 36 hours, and the product is freeze-dried at a cold trap temperature of -55℃, a vacuum degree of 10 Pa, and a time of 20 hours to obtain a solid powder of polydopamine-graphene quantum dot interface modifier.

[0123] The preparation method of ionic liquid modified polyimide nanofibers in this embodiment is as follows:

[0124] S1. Nanofibers were prepared by electrospinning a 12wt% polyamic acid solution in N,N-dimethylacetamide as the solvent. The parameters were: voltage 18kV, receiving distance 15cm, feed rate 0.8mL / h, drum speed 150rpm, and ambient humidity 35%.

[0125] S2. Gradual imidization of the fiber membrane in a vacuum oven: holding at 150℃ for 0.8 hours, holding at 220℃ for 0.8 hours, and finally raising the temperature to 320℃ and holding for 0.8 hours;

[0126] S3. Dissolve 0.8g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid in 40mL of anhydrous ethanol, add 0.3g of γ-aminopropyltriethoxysilane, and hydrolyze at 45℃ for 40 minutes to form an ionic liquid coupling agent solution.

[0127] S4. Immerse the polyimide nanofibers in the above solution, ultrasonically assisted impregnate for 15 minutes, and then vacuum dry at 85°C for 3 hours to obtain ionic liquid modified polyimide nanofibers.

[0128] The method for preparing the thermally conductive template in this embodiment is as follows:

[0129] S1. Fabrication of microcone array templates

[0130] A 0.3mm thick copper plate was used to process an array of conical pits by laser etching. The pits were 100μm deep, 80μm in diameter at the top, 40μm in diameter at the bottom, and the array spacing was 150μm. The copper plate was then immersed in an 8wt% oxalic acid solution, chemically polished at 45℃ for 15 minutes, and ultrasonically cleaned before being used as a molding template.

[0131] S2, Preparation of composite slurry

[0132] S2.1 Mix 60 parts of annealed flexible graphite micro powder with 150 parts of acetone-isopropanol mixed solvent, control the solid content at 25wt%, and pre-disperse in a planetary mixer at a revolution speed of 35rpm and a rotation speed of 800rpm for 15 minutes.

[0133] S2.2, add 8 parts of functionalized boron nitride nanotubes, 5 parts of silicon carbide nanowire-silver nanoparticle core-shell structure, 3 parts of polydopamine-graphene quantum dot interface modifier, and 4 parts of ionic liquid modified polyimide nanofibers in sequence. After each component is added, increase the rotation speed to 1500 rpm and disperse at high speed for 8 minutes.

[0134] S2.3 Add 2 parts of polyvinyl butyral binder, reduce the rotation speed to 600 rpm, vacuum degassing, vacuum degree -0.08 MPa, time 25 minutes, to obtain a composite slurry with a viscosity of 3500 mPa·s;

[0135] S3, Coating and Molding

[0136] The slurry obtained from S2 was applied to the surface of the S1 template using a doctor blade coating method. The doctor blade gap was controlled at 200 μm, the coating rate was 1.5 m / min, the ambient temperature was 22℃, and the relative humidity was ≤40%. Subsequently, the template was placed in a vacuum oven and pre-cured at 75℃ for 30 minutes, with the solvent evaporation rate controlled at 70%.

[0137] S4, Hot-press curing

[0138] The template with the slurry is placed into the hot press. From bottom to top, the layers are: template, composite coating, release film, and equalizing plate. The hot pressing process parameters are as follows:

[0139] First stage: Temperature 95℃, pressure 3MPa, pressure holding time 8 minutes;

[0140] Second stage: Temperature 155℃, pressure 8MPa, pressure holding time 15 minutes;

[0141] Third stage: Temperature 210℃, pressure 12MPa, pressure holding time 25 minutes;

[0142] The entire heating rate is 5℃ / min, the cooling rate is 3℃ / min, and the pressure is released and the temperature is naturally cooled to room temperature.

[0143] S5, Demolding and Post-processing

[0144] The cured film was peeled off from the template and annealed in a tube furnace: under an argon atmosphere, the temperature was increased to 850°C at a rate of 8°C / min and held for 45 minutes, and then cooled to room temperature at a rate of 5°C / min to obtain a final thermally conductive film with a thickness of 80 μm.

[0145] Example 2:

[0146] An AFG-based ultra-high longitudinal thermal conductivity film with an integrated microcone array comprises the following components in parts by mass:

[0147] Annealed flexible graphite powder: 75 parts;

[0148] Functionalized boron nitride nanotubes: 12 parts;

[0149] Silicon carbide nanowire-silver nanoparticle core-shell structure: 9 parts;

[0150] Polydopamine-graphene quantum dot interface modifier: 6 parts;

[0151] Ionic liquid modified polyimide nanofibers: 7 parts;

[0152] Polyvinyl butyral adhesive: 4 parts;

[0153] Acetone-isopropanol mixed solvent: 250 parts.

[0154] The annealed flexible graphite micropowder in this embodiment has a particle size of 15-25 μm and a carbon content of ≥99.9%.

[0155] In the acetone-isopropanol mixed solvent, the volume ratio of acetone to isopropanol is 3:1;

[0156] In the silicon carbide nanowire-silver nanoparticle core-shell structure, the β-silicon carbide nanowires have a diameter of 50-80 nm, and the surface is coated with silver nanoparticles with a particle size of 5-10 nm, with a shell thickness of 8-15 nm.

[0157] The preparation method of the silicon carbide nanowire-silver nanoparticle core-shell structure in this embodiment is as follows:

[0158] S1. Disperse 2.5g of silicon carbide nanowires in a mixture of 200mL of deionized water and 35mL of anhydrous ethanol, and treat with ultrasonic power of 600W for 35 minutes to form a uniform suspension.

[0159] S2. Under the conditions of stirring speed of 450 rpm and temperature of 65℃, add 1.2 g silver nitrate and 0.5 g trisodium citrate in sequence, purge with nitrogen for protection, and add 35 mL of 0.2 mol / L ascorbic acid solution dropwise, controlling the dropping rate to 2.5 mL / min.

[0160] S3. Add 0.08g of polyvinylpyrrolidone, heat to 85℃, and stir continuously for 120 minutes.

[0161] S4. Centrifuge at 8500 rpm for 12 minutes, wash three times with deionized water and anhydrous ethanol, and vacuum dry at 75℃ and -0.1 MPa for 14 hours to obtain silicon carbide nanowire-silver nanoparticle core-shell structure powder.

[0162] The preparation method of the polydopamine-graphene quantum dot interface modifier in this embodiment is as follows:

[0163] S1. Disperse 0.25g of graphene quantum dots in 220mL of Tris-HCl buffer solution, pH=8.7, concentration 12mmol / L, and sonicate for 25 minutes.

[0164] S2. Add 2.2g of dopamine hydrochloride, control the water bath temperature at 32℃, and stir continuously at 220rpm for 12 hours to allow dopamine to self-polymerize and graft graphene quantum dots.

[0165] S3. Add 0.05g of ammonium persulfate as an oxidant, heat to 42℃, and continue stirring for 2.5 hours to promote the formation of cross-linked networks;

[0166] S4. Dialysis purification: the molecular weight cutoff of the dialysis bag is 3500-4500 Da, the dialysis time is 48 hours, and the product is freeze-dried at a cold trap temperature of -65℃, a vacuum degree of 20Pa, and a time of 28 hours to obtain a solid powder of polydopamine-graphene quantum dot interface modifier.

[0167] The preparation method of ionic liquid modified polyimide nanofibers in this embodiment is as follows:

[0168] S1. Nanofibers were prepared by electrospinning a 16wt% polyamic acid solution in N,N-dimethylacetamide as the solvent. The parameters were: voltage 22kV, receiving distance 20cm, feed rate 1.2mL / h, drum speed 250rpm, and ambient humidity 45%.

[0169] S2. Gradual imidization of the fiber membrane in a vacuum oven: holding at 160℃ for 1.2 hours, holding at 240℃ for 1.2 hours, and finally raising the temperature to 340℃ and holding for 1.2 hours;

[0170] S3. Dissolve 1.2g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid in 60mL of anhydrous ethanol, add 0.5g of γ-aminopropyltriethoxysilane, and hydrolyze at 55℃ for 60 minutes to form an ionic liquid coupling agent solution.

[0171] S4. Immerse the polyimide nanofibers in the above solution, ultrasonically assisted impregnation for 25 minutes, and then vacuum dry at 95°C for 5 hours to obtain ionic liquid modified polyimide nanofibers.

[0172] The method for preparing the thermally conductive template in this embodiment is as follows:

[0173] S1. Fabrication of microcone array templates

[0174] A 0.5mm thick copper plate was used to process an array of conical pits by laser etching. The pits were 150μm deep, 120μm in diameter at the top, 60μm in diameter at the bottom, and the array spacing was 200μm. The copper plate was then immersed in a 12wt% oxalic acid solution, chemically polished at 55℃ for 25 minutes, and ultrasonically cleaned before being used as a molding template.

[0175] S2, Preparation of composite slurry

[0176] S2.1 Mix 75 parts of annealed flexible graphite micro powder with 250 parts of acetone-isopropanol mixed solvent, control the solid content at 35wt%, and pre-disperse in a planetary mixer at an orbital speed of 45rpm and a rotational speed of 1200rpm for 25 minutes.

[0177] S2.2, add 12 parts of functionalized boron nitride nanotubes, 9 parts of silicon carbide nanowire-silver nanoparticle core-shell structure, 6 parts of polydopamine-graphene quantum dot interface modifier, and 7 parts of ionic liquid modified polyimide nanofibers in sequence. After each component is added, increase the rotation speed to 2000 rpm and disperse at high speed for 12 minutes.

[0178] S2.3 Add 4 parts of polyvinyl butyral binder, reduce the rotation speed to 800 rpm, vacuum degas at a vacuum degree of -0.095 MPa for 35 minutes to obtain a composite slurry with a viscosity of 5500 mPa·s;

[0179] S3, Coating and Molding

[0180] The slurry obtained from S2 was applied to the surface of the S1 template using a doctor blade coating method. The doctor blade gap was controlled at 300 μm, the coating rate was 2.5 m / min, the ambient temperature was 28℃, and the relative humidity was ≤40%. Subsequently, the template was placed in a vacuum oven and pre-cured at 85℃ for 45 minutes, with the solvent evaporation rate controlled at 80%.

[0181] S4, Hot-press curing

[0182] The template with the slurry is placed into the hot press. From bottom to top, the layers are: template, composite coating, release film, and equalizing plate. The hot pressing process parameters are as follows:

[0183] First stage: Temperature 105℃, pressure 5MPa, pressure holding time 12 minutes;

[0184] Second stage: Temperature 165℃, pressure 12MPa, pressure holding time 20 minutes;

[0185] Third stage: Temperature 230℃, pressure 16MPa, pressure holding time 35 minutes;

[0186] The entire heating rate is 8℃ / min, the cooling rate is 5℃ / min, and the pressure is released and the temperature is naturally cooled to room temperature.

[0187] S5, Demolding and Post-processing

[0188] The cured film was peeled off from the template and annealed in a tube furnace: under an argon atmosphere, the temperature was increased to 950°C at a rate of 12°C / min and held for 75 minutes, and then cooled to room temperature at a rate of 7°C / min to obtain a final thermally conductive film with a thickness of 120 μm.

[0189] Example 3:

[0190] An AFG-based ultra-high longitudinal thermal conductivity film with an integrated microcone array comprises the following components in parts by mass:

[0191] Annealed flexible graphite powder: 67 parts;

[0192] Functionalized boron nitride nanotubes: 10 parts;

[0193] Silicon carbide nanowire-silver nanoparticle core-shell structure: 7 parts;

[0194] Polydopamine-graphene quantum dot interface modifier: 5 parts;

[0195] Ionic liquid modified polyimide nanofibers: 5 parts;

[0196] Polyvinyl butyral adhesive: 3 parts;

[0197] Acetone-isopropanol mixed solvent: 200 parts.

[0198] The annealed flexible graphite micropowder in this embodiment has a particle size of 15-25 μm and a carbon content of ≥99.9%.

[0199] In the acetone-isopropanol mixed solvent, the volume ratio of acetone to isopropanol is 3:1;

[0200] In the silicon carbide nanowire-silver nanoparticle core-shell structure, the β-silicon carbide nanowires have a diameter of 50-80 nm, and the surface is coated with silver nanoparticles with a particle size of 5-10 nm, with a shell thickness of 8-15 nm.

[0201] The preparation method of the silicon carbide nanowire-silver nanoparticle core-shell structure in this embodiment is as follows:

[0202] S1. Disperse 2g of silicon carbide nanowires in a mixture of 175mL of deionized water and 30mL of anhydrous ethanol, and treat with ultrasonic power of 520W for 30 minutes to form a uniform suspension.

[0203] S2. Under the conditions of stirring speed of 400 rpm and temperature of 60℃, add 1g of silver nitrate and 0.4g of trisodium citrate in sequence, purge with nitrogen for protection, and add 30mL of 0.1mol / L ascorbic acid solution dropwise, controlling the dropping rate to 2mL / min.

[0204] S3. Add 0.06g of polyvinylpyrrolidone, heat to 80℃, and stir continuously for 105 minutes.

[0205] S4. Centrifuge at 8000 rpm for 10 minutes, wash three times with deionized water and anhydrous ethanol, and vacuum dry at 70℃ and -0.09 MPa for 12 hours to obtain silicon carbide nanowire-silver nanoparticle core-shell structure powder.

[0206] The preparation method of the polydopamine-graphene quantum dot interface modifier in this embodiment is as follows:

[0207] S1. Disperse 0.2g of graphene quantum dots in 200mL Tris-HCl buffer solution, pH=8.5, concentration 10mmol / L, and sonicate for 20 minutes.

[0208] S2. Add 2g of dopamine hydrochloride, control the water bath temperature at 30℃, and stir continuously at 200rpm for 10 hours to allow dopamine to self-polymerize and graft graphene quantum dots.

[0209] S3. Add 0.04g of ammonium persulfate as an oxidant, heat to 40℃, and continue stirring for 2 hours to promote the formation of cross-linked networks;

[0210] S4. Dialysis purification: the molecular weight cutoff of the dialysis bag is 3500-4500 Da, the dialysis time is 42 hours, and the product is freeze-dried at a cold trap temperature of -60℃, a vacuum degree of 15Pa, and a time of 24 hours to obtain a solid powder of polydopamine-graphene quantum dot interface modifier.

[0211] The preparation method of ionic liquid modified polyimide nanofibers in this embodiment is as follows:

[0212] S1. Nanofibers were prepared by electrospinning a 12-16 wt% polyamic acid solution in N,N-dimethylacetamide as the solvent. The parameters were: voltage 20 kV, receiving distance 18 cm, feed rate 1 mL / h, drum speed 200 rpm, and ambient humidity 40%.

[0213] S2. Gradual imidization of the fiber membrane in a vacuum oven: hold at 155℃ for 1 hour, hold at 230℃ for 1 hour, and finally raise the temperature to 330℃ and hold for 1 hour.

[0214] S3. Dissolve 1g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid in 50mL of anhydrous ethanol, add 0.4g of γ-aminopropyltriethoxysilane, and hydrolyze at 50℃ for 50 minutes to form an ionic liquid coupling agent solution.

[0215] S4. Immerse the polyimide nanofibers in the above solution, ultrasonically assisted impregnate for 20 minutes, and then vacuum dry at 90°C for 4 hours to obtain ionic liquid modified polyimide nanofibers.

[0216] The method for preparing the thermally conductive template in this embodiment is as follows:

[0217] S1. Fabrication of microcone array templates

[0218] A 0.4mm thick copper plate was used to laser-etch an array of conical pits with a depth of 125μm, a top diameter of 100μm, a bottom diameter of 50μm, and an array spacing of 175μm. The copper plate was then immersed in a 10wt% oxalic acid solution, chemically polished at 50℃ for 20 minutes, and ultrasonically cleaned before being used as a molding template.

[0219] S2, Preparation of composite slurry

[0220] S2.1 Mix 67 parts of annealed flexible graphite micro powder with 200 parts of acetone-isopropanol mixed solvent, control the solid content at 30wt%, and pre-disperse in a planetary mixer at an orbital speed of 40rpm and a rotational speed of 1000rpm for 20 minutes.

[0221] S2.2, add 10 parts of functionalized boron nitride nanotubes, 7 parts of silicon carbide nanowire-silver nanoparticle core-shell structure, 5 parts of polydopamine-graphene quantum dot interface modifier, and 5 parts of ionic liquid modified polyimide nanofibers in sequence. After each component is added, increase the rotation speed to 1800 rpm and disperse at high speed for 10 minutes.

[0222] S2.3 Add 3 parts of polyvinyl butyral binder, reduce the rotation speed to 700 rpm, vacuum degassing, vacuum degree -0.085 MPa, time 30 minutes, to obtain a composite slurry with a viscosity of 4500 mPa·s;

[0223] S3, Coating and Molding

[0224] The slurry obtained from S2 was applied to the surface of the S1 template using a doctor blade coating method. The doctor blade gap was controlled at 250 μm, the coating rate was 2 m / min, the ambient temperature was 25℃, and the relative humidity was ≤40%. Subsequently, the template was placed in a vacuum oven and pre-cured at 80℃ for 37 minutes, with the solvent evaporation rate controlled at 75%.

[0225] S4, Hot-press curing

[0226] The template with the slurry is placed into the hot press. From bottom to top, the layers are: template, composite coating, release film, and equalizing plate. The hot pressing process parameters are as follows:

[0227] First stage: Temperature 100℃, pressure 4MPa, pressure holding time 10 minutes;

[0228] Second stage: Temperature 160℃, pressure 10MPa, pressure holding time 18 minutes;

[0229] Third stage: Temperature 220℃, pressure 14MPa, pressure holding time 30 minutes;

[0230] The entire heating rate is 6℃ / min, the cooling rate is 4℃ / min, and the pressure is released and the temperature is naturally cooled to room temperature.

[0231] S5, Demolding and Post-processing

[0232] The cured film was peeled off from the template and annealed in a tube furnace: under an argon atmosphere, the temperature was increased to 900°C at a rate of 10°C / min and held for 60 minutes, and then cooled to room temperature at a rate of 6°C / min to obtain a final thermally conductive film with a thickness of 100 μm.

[0233] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0234] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An AFG-based ultra-high longitudinal thermal conductive film integrated with a microcone array, characterized in that, Comprise the following mass parts of ingredients: annealed flexible graphite powder: 60-75 parts; functionalized boron nitride nanotubes: 8-12 parts; silicon carbide nanowire-silver nanoparticle core-shell structure: 5-9 parts; polydopamine-graphene quantum dot interface modifier: 3-6 parts; ionic liquid modified polyimide nanofiber: 4-7 parts; polyvinyl butyral binder: 2-4 parts; acetone-isopropyl alcohol mixed solvent: 150-250 parts.

2. The AFG-based super-high longitudinal thermal conductive film integrated with micro-taper arrays according to claim 1, characterized in that, The annealed flexible graphite powder has a particle size of 15-25 μm and a carbon content of ≥99.9%; In the acetone-isopropyl alcohol mixed solvent, the volume ratio of acetone to isopropyl alcohol is 3:1; In the silicon carbide nanowire-silver nanoparticle core-shell structure, the β-silicon carbide nanowire has a diameter of 50-80 nm, the surface is coated with silver nanoparticles with a particle size of 5-10 nm, and the shell layer has a thickness of 8-15 nm.

3. The AFG-based super-high longitudinal thermal conductive film integrated with micro-taper arrays according to claim 1, characterized in that, The preparation method of the silicon carbide nanowire-silver nanoparticle core-shell structure is as follows: S1, disperse 1.5-2.5 g of silicon carbide nanowire in a mixture of 150-200 mL of deionized water and 25-35 mL of anhydrous ethanol, treat for 25-35 minutes under ultrasonic power of 450-600 W, and form a uniform suspension; S2, under the conditions of stirring speed 350-450 rpm and temperature 55-65℃, sequentially add 0.8-1.2 g of silver nitrate, 0.3-0.5 g of trisodium citrate, protect with nitrogen, drop 25-35 mL of 0.1-0.2 mol / L ascorbic acid solution, and control the drop rate to be 1.5-2.5 mL / min; S3, add 0.05-0.08 g of polyvinylpyrrolidone, heat to 75-85℃, and continuously stir for 90-120 minutes; S4, centrifugal separation at a speed of 7500-8500 rpm for 8-12 minutes, wash with deionized water and anhydrous ethanol alternately for 3 times, vacuum drying at a temperature of 65-75℃, a vacuum degree of -0.09 to -0.1 MPa, and a time of 10-14 hours, to obtain a silicon carbide nanowire-silver nanoparticle core-shell structure powder.

4. The AFG-based super-high longitudinal thermal conductive film integrated with micro-taper arrays according to claim 1, characterized in that, The preparation method of the polydopamine-graphene quantum dot interface modifier is as follows: S1, disperse 0.15-0.25 g of graphene quantum dots in 180-220 mL of Tris-HCl buffer solution with pH=8.3-8.7 and a concentration of 8-12 mmol / L, and ultrasonic treat for 15-25 minutes; S2, add 1.8-2.2 g of dopamine hydrochloride, control the water bath temperature at 28-32℃, and continuously stir at a speed of 180-220 rpm for 8-12 hours to make dopamine self-polymerize and graft graphene quantum dots; S3, add 0.03-0.05 g of ammonium persulfate as an oxidizing agent, heat to 38-42℃, and continue to stir for 1.5-2.5 hours to promote the formation of a crosslinked network; S4, dialysis purification, dialysis bag molecular weight cut-off 3500-4500 Da, dialysis time 36-48 hours, freeze-drying, cold trap temperature -55 to -65℃, vacuum degree 10-20 Pa, time 20-28 hours, to obtain a polydopamine-graphene quantum dot interface modifier solid powder.

5. The AFG-based super-high longitudinal thermal conductive film integrated with micro-taper arrays according to claim 1, characterized in that, The preparation method of the ion liquid modified polyimide nanofiber is as follows: S1, 12-16wt% of polyamide acid solution, solvent is N,N-dimethylacetamide, is prepared into nanofiber by electrospinning, parameters: voltage 18-22kV, receiving distance 15-20cm, push rate 0.8-1.2mL / h, drum rotating speed 150-250rpm, environmental humidity 35-45%; S2, the fiber membrane is gradient imidized in a vacuum oven: 150-160℃ for 0.8-1.2 hours, 220-240℃ for 0.8-1.2 hours, finally heated to 320-340℃ for 0.8-1.2 hours; S3, 0.8-1.2g 1-ethyl-3-methyl imidazole bis-trifluoromethanesulfonylimidate ion liquid is dissolved in 40-60mL anhydrous ethanol, 0.3-0.5g γ-aminopropyl triethoxysilane is added, hydrolysis reaction is carried out at 45-55℃ for 40-60 minutes, ion liquid coupling agent solution is formed; S4, the polyimide nanofiber is immersed in the above solution, ultrasonic assisted immersion is carried out for 15-25 minutes, then vacuum drying is carried out at 85-95℃ for 3-5 hours, ion liquid modified polyimide nanofiber is obtained.

6. The AFG-based super-high longitudinal thermal conductive film integrated with micro-taper arrays according to claim 1, wherein, The preparation method of the heat conduction mold is as follows: S1, micro-taper array template preparation A copper plate with a thickness of 0.3-0.5mm is used, array arranged conical pits are processed by laser etching, the pit depth is 100-150μm, the top diameter is 80-120μm, the bottom diameter is 40-60μm, and the array spacing is 150-200μm; Then the copper plate is immersed in an 8-12wt% oxalic acid solution, chemical polishing is carried out at 45-55℃ for 15-25 minutes, and after ultrasonic cleaning, it is used as a forming mold; S2, composite slurry preparation S2.1, 60-75 parts of annealed flexible graphite micro powder and 150-250 parts of acetone-isopropyl alcohol mixed solvent are mixed, the solid content is controlled at 25-35wt%, and pre-dispersion is carried out in a planetary mixer at a revolution speed of 35-45rpm and a rotation speed of 800-1200rpm for 15-25 minutes; S2.2, 8-12 parts of functionalized boron nitride nanotube, 5-9 parts of silicon carbide nanowire-silver nanoparticle core-shell structure, 3-6 parts of polydopamine-graphene quantum dot interface modifier, and 4-7 parts of ion liquid modified polyimide nanofiber are added in sequence, the rotation speed is increased to 1500-2000rpm after each component is added, and high-speed dispersion is carried out for 8-12 minutes; S2.3, 2-4 parts of polyvinyl butyral adhesive is added, the rotation speed is reduced to 600-800rpm, vacuum degassing is carried out, the vacuum degree is-0.08 to-0.095 MPa, and the time is 25-35 minutes, to obtain a composite slurry with a viscosity of 3500-5500mPa·s; S3, coating forming The slurry obtained in S2 was applied to the surface of the template in S1 by doctor blade coating method, with a gap of 200-300 μm, a coating speed of 1.5-2.5 m / min, an ambient temperature of 22-28℃, and a relative humidity of ≤40%; then the template was placed in a vacuum oven and pre-cured at 75-85℃ for 30-45 minutes, with a solvent evaporation rate of 70-80%; S4, hot-pressing and curing The template with the slurry was placed in a hot press, with the template, the composite coating, the release film, and the pressure plate arranged from bottom to top; the hot-pressing process parameters were as follows: First stage: temperature 95-105℃, pressure 3-5 MPa, pressure holding time 8-12 minutes; Second stage: temperature 155-165℃, pressure 8-12 MPa, pressure holding time 15-20 minutes; Third stage: temperature 210-230℃, pressure 12-16 MPa, pressure holding time 25-35 minutes; The temperature was raised at a rate of 5-8℃ / min throughout the process, and the temperature was lowered at a rate of 3-5℃ / min, and the pressure was released and the template was naturally cooled to room temperature; S5, demolding and post-processing The cured film was peeled off from the template and annealed in a tube furnace: the temperature was raised to 850-950℃ at a rate of 8-12℃ / min under an argon atmosphere, and the temperature was maintained for 45-75 minutes, and then the temperature was lowered to room temperature at a rate of 5-7℃ / min, to obtain a final heat-conducting film with a thickness of 80-120 μm.