Graphene / carbon nanotube high-temperature thermal interface material and preparation method thereof

Abstract

The application belongs to the field of thermal interface materials, and particularly relates to a graphene / carbon nanotube high-temperature thermal interface material and a preparation method thereof. The application adopts hydrochloric acid to regulate and control graphene oxide / carbon nanotube colloids to form a metastable state, and then combines vacuum-assisted self-assembly, ultralow-temperature freezing and freeze-drying technology to prepare oriented three-dimensional continuous graphene oxide / carbon nanotube porous materials, and then adopts a high-temperature graphitization process to repair defects to obtain graphene / carbon nanotube high-temperature thermal interface materials. The preparation method is simple, low in cost, and the bonding line thickness of the thermal interface material is controllable, and the material is a full-carbon-based thermal interface material prepared by compounding one-dimensional and two-dimensional carbon materials, has the advantages of stable structure and physical properties, can be applied to high-temperature scenes (200-500 DEG C), is expected to solve the aging problem of polymer-based thermal interface materials and the corrosion problem of liquid metal under super-high heat flow density, and has great application potential in the field of high-power chips.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of thermal interface materials, and particularly relates to a graphene / carbon nanotube high-temperature thermal interface material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of low-latency and high-data transmission rate 5G technology, the power consumption and frequency of supporting core electronic components increase sharply, especially the rapid iteration of semiconductor chips drives the chip from the first generation of single-crystal silicon semiconductor material to the second generation of gallium arsenide chip, and continues to climb to the current third generation of gallium nitride and silicon carbide semiconductor material. The third generation of semiconductor chips further presents the trend of high power, miniaturization and high integration. Compared with the second generation, the third generation chip generates more heat during operation, and the local hotspot temperature is higher (more than 300 DEG C), while the limit allowable temperature of the chip is less than 150 DEG C; in order to ensure that the heat of the chip is quickly transmitted to the outside heat sink, reducing the contact thermal resistance between the heat source and the heat sink becomes the key. The thermal interface material can fill the gap between the heat source and the heat sink, and serve as a thermal transport bridge between the two, which can greatly reduce the interface thermal resistance.

[0003] Currently commonly used thermal interface materials mainly include two types: (1) polymer-based thermal interface materials, mainly silicon grease and silica gel; (2) metal-based thermal interface materials, mainly gallium and indium metals. First, the thermal conductivity of the polymer-based thermal interface material is low, and it is easy to age at high temperature, resulting in performance degradation, which is difficult to apply to the heat dissipation field of ultra-high power chips. Second, the metal-based thermal interface material can meet the application demand of high temperature resistance, and can form a continuous heat channel at the contact interface. However, its modulus is high, and it has high requirements for assembly pressure and equipment itself, and gallium-based metals will corrode aluminum alloy substrates, so its application is limited. Therefore, the all-carbon-based thermal interface material has the advantages of high thermal conductivity, excellent interface compatibility, and strong high and low temperature resistance, and can be applied to the high-temperature thermal interface chip heat dissipation field. However, at present, most of the all-carbon-based materials are used in the fields of heat equalization, heat expansion, lubrication and sealing, and few are specially developed for high-temperature thermal interface materials.

[0004] Patent No. CN114214042A discloses the application of a graphene film as a high-temperature thermal interface material or a heat dissipation film material. The preparation method is to use a typical chemical vapor deposition method (CVD) to decompose carbon source gas, reducing gas and carrier gas at 600-1200 DEG C to form a graphene film on the substrate. This method uses carbon pyrolysis to deposit carbon atoms on the substrate, which has low preparation efficiency and is difficult to realize large-scale preparation. Secondly, the graphene film prepared by this method has a two-dimensional dense thin layer structure, and its compression elastic modulus is high, so the interface compatibility of the graphene film as a thermal interface material with the heat source and the heat sink is poor.

[0005] Patent No. CN115650224A discloses a high-thermal-conductivity nitrogen-doped graphene-carbon nanotube composite film and a preparation method thereof. The method uses an amine crosslinking agent to chemically crosslink graphene and carbon nanotubes, and then uses coating, drying and graphitization to prepare a nitrogen-doped graphene film. Due to the use of hot air drying in the composite film, the compression strength of the film structure is high, and it cannot be used as a thermal interface material, but only as a uniform heating material. Existing research work has made many achievements and progress, but there are still problems that need further research and solution. SUMMARY

[0006] To solve the problems existing in the prior art, the present application provides a graphene / carbon nanotube high-temperature thermal interface material and a preparation method thereof. The present application uses hydrochloric acid to regulate the graphene oxide / carbon nanotube colloidal system to form a metastable state, and then uses a vacuum-assisted self-assembly, ultra-low temperature freezing and freeze-drying combined strategy to prepare an oriented three-dimensional continuous graphene oxide / carbon nanotube porous material. Then, a high-temperature graphitization process is used to repair defects to obtain an ultra-high elasticity isotropic graphene / carbon nanotube high-temperature thermal interface material. The preparation method is simple, low in cost, and the bonding line thickness of the thermal interface material is controllable. The material is a full-carbon-based thermal interface material prepared by compounding one-dimensional and two-dimensional carbon materials, has the advantages of stable structure and physical properties, can be applied to high-temperature scenes (200-500℃), and is expected to solve the aging problem and liquid metal corrosion problem of polymer-based thermal interface materials under ultra-high heat flux density, and has great application potential in the field of high-power chips.

[0007] To achieve the above-mentioned purpose, the present application is realized by the following technical solutions:

[0008] The present application provides a preparation method of a graphene / carbon nanotube high-temperature thermal interface material, comprising the following steps:

[0009] Step 1: gel potential regulation

[0010] Mixing graphene oxide, carbon nanotubes and strong acid reagents, ultrasonic dispersion, obtaining metastable graphene oxide / carbon nanotube suspension;

[0011] Step 2: self-assembly, ultra-low temperature freezing and freeze-drying

[0012] The metastable graphene oxide / carbon nanotube suspension is sequentially subjected to vacuum-assisted self-assembly, ultra-low temperature freezing and freeze-drying treatment to obtain graphene oxide / carbon nanotube aerogel;

[0013] Step 3: carbonization

[0014] The graphene oxide / carbon nanotube aerogel is subjected to carbonization treatment to obtain reduced graphene oxide / carbon nanotube aerogel;

[0015] Step 4: graphitization

[0016] The graphene / carbon nanotube high-temperature thermal interface material is obtained by graphitizing the reduced graphene oxide / carbon nanotube aerogel.

[0017] Further, in the step 1, the mass ratio of the graphene oxide and the carbon nanotube is 5:1-1:1, and the volume ratio of the metastable graphene oxide / carbon nanotube suspension and the strong acid reagent is 60:1-10:1.

[0018] Further, in the step 1, the strong acid reagent is selected from one of hydrochloric acid, nitric acid and hydrofluoric acid, and the concentration of the strong acid reagent is 12-0.12 mol / L.

[0019] Further, in the step 1, the PH of the metastable graphene oxide / carbon nanotube suspension is 1-3.

[0020] Further, in the step 2, the ultra-low temperature freezing temperature is (-150)-(-196)℃.

[0021] Further, in the step 2, the freezing drying condition is that the pressure is 20-50 Pa and the temperature is (-20)-(-50)℃.

[0022] Further, in the step 3, the carbonization condition is that the temperature increasing rate is 0.5-5℃ / min, the temperature is 600-1000℃, and the time is 1-2h.

[0023] Further, in the step 4, the graphitization condition is that the temperature is 200-2800℃, and the time is 1-12h.

[0024] Another aspect of the present application provides the graphene / carbon nanotube high-temperature thermal interface material prepared by the preparation method, which has smooth upper and lower surfaces, a graphene-like film surface and in-plane heat spreading capacity, an in-plane thermal conductivity of 100-1000 W / (m·K), a continuous three-dimensional network structure in the vertical direction, a pore size of 50-200 μm, super-high elasticity, an elastic modulus of 0-18 Kpa in the range of 0-80% deformation, and a vertical plane direction thermal conductivity of 1-5 W / (m·K); and can be used stably at 200-500℃ as a full-carbon high-temperature thermal interface material.

[0025] Another aspect of the present application provides the application of the graphene / carbon nanotube high-temperature thermal interface material in the field of gallium nitride and silicon carbide-based third-generation semiconductor chips.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] (1) The application adopts a gel potential regulation method to control the ZETA potential of the original graphene oxide gel, breaks the original graphene oxide colloid system, weakens the bondage of the internal hydrogen bond to the water molecules, and then accelerates the removal of water molecules to realize rapid assembly. Compared with the original graphene oxide membrane vacuum filtration, the method has the advantages of simple operation, short time consumption and batch preparation. At the same time, the thickness of the bonding line of the thermal interface material can be controlled by controlling the content of graphene oxide and carbon nanotubes.

[0028] (2) The graphene / carbon nanotube high-temperature thermal interface material in the application adopts ultra-low temperature freezing and freeze-drying technology to form an oriented three-dimensional continuous network structure, has high compressibility, and can realize high interface fitting behavior with heat sources and heat sinks.

[0029] (3) Compared with the existing polymer-based thermal interface material, the all-carbon-based thermal interface material in the application has a higher applicable temperature range (200-500℃), avoiding performance degradation caused by aging. Compared with the liquid metal-based thermal interface material, it has higher interface compatibility and non-corrosion, and at the same time avoids the pumping effect, can be safely used in the third generation semiconductor chip, and solves the heat transfer problem between the heat source and the heat sink. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The macroscopic photos of the 2mg / mL graphene oxide slurry / carbon nanotube solution (a) and the graphene oxide slurry / carbon nanotube suspension after adding hydrochloric acid of Example 1 of the application.

[0031] Figure 2 The AFM graphs of the graphene oxide slurry / carbon nanotube solution (a) and the graphene oxide slurry / carbon nanotube suspension after adding hydrochloric acid (b) of Example 1 of the application.

[0032] Figure 3 The macroscopic photo of the graphene / carbon nanotube high-temperature thermal interface material in Example 2 of the application.

[0033] Figure 4 The micro-morphology of the aerogel in Example 3 of the application, wherein picture (a) is the planar micro-SEM graph of the aerogel, and picture (b) is the vertical structure micro-SEM graph of the aerogel.

[0034] Figure 5 The relationship between the compressive stress and strain of the thermal interface material of Example 3 of the application.

[0035] Figure 6 The infrared thermal imaging picture of the thermal interface material of Example 2 of the application at 100℃ for 3 seconds.

[0036] Figure 7Thermal conductivity of the thermal interface material of the present application in the vertical direction under different pressures.

[0037] Figure 8 Thermal conductivity of the thermal interface material of the present application in the plane direction under different carbon nanotube contents (GF, G / CF-1, G / CF-3, G / CF-5, G / CF-15: the amount of carbon nanotubes in the thermal interface material is 0, 1%, 3%, 5%, and 15%, respectively).

[0038] Figure 9 High temperature resistance performance of the thermal interface material of the present application. DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present application, the present application will be described more fully below. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0040] Embodiment 1

[0041] First, the graphene oxide water-based slurry and carbon nanotubes are mixed according to a mass ratio of 5:1, and a cell crushing ultrasonic device is used to disperse the mixture into a 2mg / mL mixed slurry under ultrasonic waves at 500W for 30min. Then, 2.5mL of a hydrochloric acid solution with a concentration of 12mol / L is added dropwise to 100mL of the above-mentioned mixed solution until the mixed solution becomes a suspension with a pH of 3. Subsequently, 100mL of the above-mentioned mixed solution is injected into a vacuum filtration system (0.03MPa) to quickly assemble a graphene oxide / carbon nanotube hydrogel, which is immediately placed in liquid nitrogen at -196℃ for ultra-low temperature freezing. The frozen graphene oxide / carbon nanotube hydrogel is freeze-dried at 50Pa and -20℃ to prepare a graphene oxide / carbon nanotube aerogel. Then, it is placed in a tube furnace under argon protection, heated to 100℃ at a rate of 5℃ / min, heated to 500℃ at a rate of 0.5℃ / min, and then carbonized at a rate of 5℃ / min to 700℃, and then kept at this temperature for 1h, and then naturally cooled to room temperature. Finally, the carbonized graphene / carbon nanotube aerogel is heated to 2400℃ at a rate of 5℃ / min for graphitization treatment for 12h, and a high-temperature thermal interface material is obtained.

[0042] Embodiment 2

[0043] First, the graphene oxide aqueous slurry and carbon nanotubes are mixed according to a mass ratio of 1:1, and a cell crushing ultrasonic device is used to disperse the mixture into a mixed slurry of 2 mg / mL under ultrasonic waves of 500 W for 30 min. Then, 2.5 mL of a nitric acid solution with a concentration of 12 mol / L is added dropwise to 100 mL of the above mixed solution until the mixed solution becomes a suspension with a pH of 3. Subsequently, 100 mL of the above mixed solution is injected into a vacuum filtration system (0.03 MPa) to quickly assemble a graphene oxide / carbon nanotube hydrogel, which is immediately placed in liquid nitrogen at -196°C for ultra-low temperature freezing. The frozen graphene oxide / carbon nanotube hydrogel is freeze-dried at 50 Pa and -20°C to prepare a graphene oxide / carbon nanotube aerogel. Then, the graphene oxide / carbon nanotube aerogel is placed in a tube furnace under argon protection, and heated to 700°C at a heating rate of 0.5°C / min, and then naturally cooled to room temperature after heat treatment for 1 h. Finally, the carbonized graphene / carbon nanotube aerogel is heated to 2400°C at a heating rate of 5°C / min for graphitization treatment for 12 h to obtain a high-temperature thermal interface material.

[0044] Example 3

[0045] The graphene oxide aqueous slurry of 2 mg / mL is mixed with hydrochloric acid according to a volume ratio of 50:1 to form a mixed solution until the solution becomes a suspension with a pH of 3. Then, the graphene oxide aqueous slurry and carbon nanotubes are mixed again according to a mass ratio of 5:1, and a cell crushing ultrasonic device is used to disperse the mixture into a mixed solution of 2 mg / mL under ultrasonic waves of 500 W for 30 min. Subsequently, 100 mL of the above mixed solution is injected into a vacuum filtration system (0.03 MPa) to quickly assemble a graphene oxide / carbon nanotube hydrogel, which is immediately placed in liquid nitrogen at -196°C for ultra-low temperature freezing. The frozen graphene oxide / carbon nanotube hydrogel is freeze-dried at 50 Pa and -20°C to prepare a graphene oxide / carbon nanotube aerogel. Then, the graphene oxide / carbon nanotube aerogel is placed in a tube furnace under argon protection, and heated to 700°C at a heating rate of 0.5°C / min, and then naturally cooled to room temperature after heat treatment for 1 h. Finally, the carbonized graphene / carbon nanotube aerogel is heated to 2400°C at a heating rate of 5°C / min for graphitization treatment for 12 h to obtain a high-temperature thermal interface material.

[0046] Example 4

[0047] The 2 mg / mL graphene oxide aqueous slurry is mixed with hydrochloric acid in a volume ratio of 50:1 to form a mixed solution, until the solution becomes a PH = 3 suspension, then mixed again according to the mass ratio of graphene oxide to carbon nanotubes 5:1, and dispersed into a 2 mg / mL mixed solution using a cell crushing ultrasonic device at 500 W for 30 min. Then 100 mL of the above mixed solution is injected into a vacuum filtration system (0.03 MPa) to quickly assemble into a graphene oxide / carbon nanotube hydrogel, which is immediately placed in liquid nitrogen at -196°C for ultra-low temperature freezing. The frozen graphene oxide / carbon nanotube hydrogel is freeze-dried at 50 Pa and -20°C to prepare a graphene oxide / carbon nanotube aerogel. Then, it is placed in a tube furnace under argon protection, heated to 1000°C at a rate of 2°C / min, and held for 2 h, then naturally cooled to room temperature. Finally, the carbonized graphene / carbon nanotube aerogel is heated to 2400°C at a rate of 5°C / min for graphitization for 1 h to obtain a high-temperature thermal interface material.

[0048] Example 5

[0049] First, the graphene oxide aqueous slurry is mixed with carbon nanotubes according to a mass ratio of 1:1, and dispersed into a 2 mg / mL mixed slurry using a cell crushing ultrasonic device at 500 W for 30 min. Then, the mixed solution is mixed with nitric acid in a volume ratio of 20:1 to form a secondary mixed solution, until the solution becomes a PH = 1 suspension. Then, 100 mL of the above mixed solution is injected into a vacuum filtration system (0.03 MPa) to quickly assemble into a graphene oxide / carbon nanotube hydrogel, which is immediately placed in liquid nitrogen at -196°C for ultra-low temperature freezing. The frozen graphene oxide / carbon nanotube hydrogel is freeze-dried at 50 Pa and -20°C to prepare a graphene oxide / carbon nanotube aerogel. Then, it is placed in a tube furnace under argon protection, heated to 700°C at a rate of 0.5°C / min, and held for 1 h, then naturally cooled to room temperature. Finally, the carbonized graphene / carbon nanotube aerogel is heated to 2400°C at a rate of 5°C / min for graphitization for 2 h to obtain a high-temperature thermal interface material.

[0050] Example 6

[0051] First, an aqueous slurry of graphene oxide and carbon nanotubes were mixed at a mass ratio of 1:1 and dispersed using a cell-disrupting sonicator at 500W for 30 minutes to form a mixed slurry of 2 mg / mL. Then, 2.5 mL of a 12 mol / L hydrochloric acid solution was added dropwise to 100 mL of the above mixed solution until the solution became a suspension with pH=3. Subsequently, 100 mL of the above mixed solution was injected into a vacuum filtration system (0.03 MPa) to rapidly assemble a graphene oxide / carbon nanotube hydrogel. The hydrogel was immediately placed in liquid nitrogen at -196℃ for cryogenic freezing. The frozen graphene oxide / carbon nanotube hydrogel was then freeze-dried at 50 Pa and -20℃ to prepare a graphene oxide / carbon nanotube aerogel. Finally, a continuous carbonization combined with graphitization process was adopted. Specifically, the graphene oxide / carbon nanotube aerogel was heated to 1000℃ at a heating rate of 2℃ / min and held at that temperature for 1 hour. Then, without removing the sample, the temperature was increased to 2800℃ at the same heating rate for 2 hours to obtain a high-temperature thermal interface material.

[0052] Depend on Figure 4 It is known that the graphene / carbon nanotube aerogel of the present invention has a continuous three-dimensional network structure in the vertical direction, with a pore size of 50-200 μm.

[0053] Depend on Figure 5 It is known that the graphene / carbon nanotube thermal interface material of the present invention has ultra-high elasticity, with an elastic modulus of 0-18 kPa in the range of 0-80% deformation.

[0054] Depend on Figure 7 It is known that the thermal conductivity of the graphene / carbon nanotube thermal interface material of the present invention in the vertical plane direction is 1-5 W / (m·K).

[0055] Depend on Figure 8 It can be seen that the present invention tested the internal thermal conductivity of graphene / carbon nanotube thermal interface materials with different carbon nanotube contents. The results showed that the graphene / carbon nanotube thermal interface material of the present invention has in-plane heat expansion capability and in-plane thermal conductivity of 100-1000 W / (m·K).

[0056] Depend on Figure 9 It is known that the graphene / carbon nanotube thermal interface material of the present invention, as an all-carbon high-temperature resistant thermal interface material, can exist stably without being destroyed at the lighter flame temperature of 500-600℃. Therefore, this thermal interface material can meet the requirements of electronic devices to be used stably at 200-500℃.

[0057] The above description is only for better explaining the embodiments of the present invention and is not intended to limit them. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims

1. A method for preparing a graphene / carbon nanotube high-temperature thermal interface material, characterized in that: The method comprises the following steps: Step 1: gel potential regulation Mixing graphene oxide and carbon nanotubes with a strong acid reagent, ultrasonic dispersion, obtaining a metastable graphene oxide / carbon nanotube suspension; Step 2: self-assembly, ultra-low temperature freezing and freeze drying The metastable graphene oxide / carbon nanotube suspension is sequentially subjected to vacuum-assisted self-assembly, ultra-low temperature freezing and freeze drying treatment, obtaining a graphene oxide / carbon nanotube aerogel; Step 3: carbonization The graphene oxide / carbon nanotube aerogel is subjected to carbonization treatment, obtaining a reduced graphene oxide / carbon nanotube aerogel; Step 4: graphitization The reduced graphene oxide / carbon nanotube aerogel is subjected to graphitization treatment, obtaining the graphene / carbon nanotube high-temperature thermal interface material; In the step 2, the vacuum-assisted self-assembly is specifically: the metastable graphene oxide / carbon nanotube suspension is injected into a vacuum filtration system to quickly assemble into a graphene oxide / carbon nanotube hydrogel; the ultra-low temperature freezing temperature is (-150) - (-196) DEG C; the freeze drying conditions are: pressure 20-50 Pa, temperature (-20) - (-50) DEG C; In the step 4, the graphitization conditions are: temperature 2400-2800 DEG C, time 1-12 h.

2. The method of claim 1, wherein the graphene / carbon nanotube high-temperature thermal interface material is prepared by the steps of: providing a graphene / carbon nanotube mixture; and applying the graphene / carbon nanotube mixture to a surface of a substrate. In the step 1, the mass ratio of graphene oxide and carbon nanotubes is 5:1-1:1, and the volume ratio of the metastable graphene oxide / carbon nanotube suspension to the strong acid reagent is 60:1-10:

1.

3. The method of claim 1, wherein the graphene / carbon nanotube high-temperature thermal interface material is prepared by the steps of: providing a graphene / carbon nanotube mixture; and applying the graphene / carbon nanotube mixture to a surface of a substrate. In the step 1, the strong acid reagent is selected from one of hydrochloric acid, nitric acid and hydrofluoric acid, and the concentration of the strong acid reagent is 12-0.12 mol / L.

4. The method of claim 1, wherein the graphene / carbon nanotube high-temperature thermal interface material is prepared by the steps of: providing a graphene / carbon nanotube mixture; and applying the graphene / carbon nanotube mixture to a surface of a substrate. In the step 1, the PH of the metastable graphene oxide / carbon nanotube suspension is 1-3.

5. The method of claim 1, wherein the graphene / carbon nanotube high-temperature thermal interface material is prepared by the steps of: providing a graphene / carbon nanotube mixture; and applying the graphene / carbon nanotube mixture to a surface of a substrate. In the step 3, the carbonization conditions are: heating rate 0.5-5 DEG C / min, temperature 600-1000 DEG C, time 1-2 h.

6. The graphene / carbon nanotube high-temperature thermal interface material prepared by the method of any one of claims 1-5, wherein the graphene / carbon nanotube high-temperature thermal interface material has a thermal conductivity of at least 1000 W / mK. The material has flat upper and lower surfaces, a graphene-like film surface and in-plane heat spreading capacity, an in-plane thermal conductivity of 100-1000 W / (m·K), a continuous three-dimensional network structure in the vertical direction, and a pore size of 50-200 μm; has super-high elasticity, an elastic modulus of 0-18 KPa in the range of 0-80% deformation, and a vertical plane direction thermal conductivity of 1-5 W / (m·K); and simultaneously as a full-carbon high-temperature thermal interface material, can be used stably at 200-500 DEG C.

7. Use of the graphene / carbon nanotube high-temperature thermal interface material according to claim 6, characterized in that: Applied to the field of gallium nitride and silicon carbide-based third-generation semiconductor chips.

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