Self-assembled graphene thermal interface material and preparation method and application thereof

Abstract

This invention relates to the field of thermal interface materials technology, and discloses a self-assembled graphene thermally conductive interface material, its preparation method, and its applications. The self-assembled graphene thermally conductive interface material is obtained by stacking dried graphene oxide coatings and then sequentially subjecting them to high-temperature carbonization heat treatment and graphitization treatment, while controlling the molding pressure during the heat treatment process. This invention also provides the self-assembled graphene thermally conductive interface material obtained by the aforementioned preparation method and its applications. The self-assembled graphene thermally conductive interface material prepared by this invention does not use adhesive as a binder, and its thermal conductivity and mechanical properties do not degrade in high and low temperature, high temperature and high humidity, and high temperature liquid working fluid environments.

Description

Technical Field

[0001] This invention relates to the field of thermal interface materials technology, specifically to a self-assembled graphene thermally conductive interface material, its preparation method, and its application. Background Technology

[0002] With the rapid development of technologies such as 5G communication, new energy vehicles, artificial intelligence, optical modules, servers, and the Internet of Things, the power density of electronic devices is constantly increasing, and heat dissipation problems are becoming increasingly prominent. Traditional thermal conductive materials exhibit high contact thermal resistance, low thermal conductivity, and pumping problems when dealing with such high heat flux densities. Unlike traditional thermal interface materials, graphene thermal conductive interface materials possess excellent characteristics such as high longitudinal thermal conductivity, ultra-low thermal resistance, high resilience, high compressibility, and high reliability, and can be widely used in thermal management systems for high-power chips, mobile communications, semiconductor lighting, electric vehicles, and aerospace. Traditional graphene thermal conductive interface material preparation processes include graphene oxide slurry coating, slurry drying, carbonization, calendering, graphitization, adhesive spraying, stacking, curing, slicing, and surface cleaning. However, the complexity of traditional graphene thermal conductive interface material preparation processes, low yield rates, and weak interlayer bonding limit their large-scale application. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems existing in the prior art and provide a self-assembled graphene thermally conductive interface material, its preparation method, and its application.

[0004] This invention uses a coated and dried graphene oxide coating as raw material. During the subsequent high-temperature heat treatment, the density of the graphene bulk is controlled by applying different heat treatment conditions and molding pressures. Because graphene oxide contains a large number of hydroxyl, carboxyl, carbonyl, amino, and thiol functional groups, it undergoes condensation polymerization and cross-linking self-assembly during the subsequent high-temperature heat treatment to form graphene bulks with strong interlayer bonding. Since there is no adhesive present, the sliced ​​graphene bulk is a pure graphite thermal interface material. Under high and low temperature cycling tests and application environments, there is no problem of adhesive aging leading to thermal interface material failure, further improving the reliability of the thermal interface material.

[0005] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a self-assembled graphene thermally conductive interface material, wherein the preparation method includes: stacking graphene oxide coatings and then subjecting them to high-temperature carbonization heat treatment and graphitization treatment in sequence to obtain the self-assembled graphene thermally conductive interface material.

[0006] A second aspect of the present invention provides a self-assembled graphene thermally conductive interface material obtained by the preparation method described in the first aspect.

[0007] A third aspect of the present invention provides the application of the self-assembled graphene thermally conductive interface material according to the second aspect in large-scale integrated circuits, high-power chips / devices and advanced packaging.

[0008] The beneficial technical effects achieved by the present invention through the above technical solution are as follows: (1) The present invention uses coated and dried graphene oxide coating as raw material, stacks graphene oxide coating sequentially along the thickness direction to form a preform, fixes the preform material with graphite tooling, and applies a certain pressure during high-temperature carbonization and graphitization to obtain graphene bulk material. After slicing and cleaning the graphene bulk material, a low-density graphene thermal pad with excellent performance and no binder can be prepared.

[0009] (2) The present invention relies on the excellent chemical reactivity of the graphene oxide coating. During the high-temperature carbonization and graphitization heat treatment, the coating undergoes a polycondensation and cross-linking reaction, which can greatly improve the bonding performance of the graphene thermally conductive interface material.

[0010] (3) The self-assembled graphene thermal interface material prepared in this invention does not use glue as a binder, and its thermal conductivity and mechanical properties will not be reduced in high and low temperature, high temperature and high humidity and high temperature liquid working fluid environments. Detailed Implementation

[0011] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0012] The first aspect of the present invention provides a method for preparing a self-assembled graphene thermally conductive interface material, wherein the preparation method includes: stacking graphene oxide coatings and then subjecting them to high-temperature carbonization heat treatment and graphitization treatment in sequence to obtain the self-assembled graphene thermally conductive interface material.

[0013] This invention uses a coated and dried graphene oxide coating as raw material. Utilizing the rich oxygen-containing active functional groups in graphene oxide, condensation cross-linking occurs between the graphene oxide coatings during subsequent high-temperature carbonization and graphitization heat treatment, leading to self-assembly into a bulk graphene material. Finally, the bulk graphene material is sliced ​​to prepare a binder-free, high-performance, low-density graphene thermally conductive interface material. The method provided by this invention reduces the processes of calendering, coating, and curing of existing graphene thermally conductive films, significantly lowering the production cost of graphene thermally conductive interface materials and promoting their application in high heat flux density scenarios such as large-scale integrated circuits, high-power chips / devices, and advanced packaging. Furthermore, because the graphene thermally conductive pads prepared by this method have a pure graphite structure, they are particularly suitable for operating temperatures exceeding 125°C and immersion liquid cooling environments.

[0014] In some embodiments of the present invention, the temperature of the high-temperature carbonization heat treatment is 900-1600℃, preferably 1000℃.

[0015] In some embodiments of the present invention, the heating rate within the temperature range of 300-700℃ is 0.005-0.1℃ / min, for example, 0.005℃ / min, 0.01℃ / min, 0.02℃ / min, 0.03℃ / min, 0.05℃ / min, 0.1℃ / min, etc., and any value within any range of any two of the above values, preferably 0.01-0.03℃ / min, and more preferably 0.02℃ / min. Slow heating can ensure uniform and slow thermal decomposition of the material during carbonization, while rapid thermal decomposition due to violent heating will lead to more pores and defects in the material.

[0016] In some embodiments of the present invention, the high-temperature carbonization heat treatment time is 350-400 hours. This treatment time is related to the heating rate.

[0017] In some embodiments of the present invention, the molding pressure of the high-temperature carbonization heat treatment is 0-0.5 MPa, such as 0 MPa, 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, etc., and any value within the range of any two of the above values, preferably 0.2-0.4 MPa, and more preferably 0.3 MPa.

[0018] In some embodiments of the present invention, the density of the graphene bulk obtained after the high-temperature carbonization heat treatment is 0.01-0.8 g / cm³. 3 The preferred value is 0.04-0.68 g / cm³. 3 Further preferably, it is 0.35-0.45 g / cm³. 3 .

[0019] In some embodiments of the present invention, the temperature of the graphitization treatment is 2600-3200℃, such as 2600℃, 2800℃, 2900℃, 3000℃, 3050℃, 3150℃, 3200℃, etc., and any value within the range of any two of the above values, preferably 2900-3150℃, and more preferably 3050℃.

[0020] In some embodiments of the present invention, the graphitization treatment is carried out at the temperature for 1-3 hours, more preferably 2 hours.

[0021] In some embodiments of the present invention, the molding pressure of the graphitization treatment is 0-0.9 MPa, for example 0 MPa, 0.1 MPa, 0.3 MPa, 0.5 MPa, 0.7 MPa, 0.9 MPa, and any value within the range of any two of the above values, preferably 0.3-0.5 MPa, and more preferably 0.3 MPa.

[0022] In some embodiments of the present invention, the density of the graphene bulk obtained after the graphitization treatment is 0.05-0.72 g / cm³. 3 The preferred value is 0.40-0.50 g / cm³. 3 .

[0023] In some embodiments of the present invention, the graphitized material is sliced ​​and cleaned to obtain the self-assembled graphene thermal interface material.

[0024] In some embodiments of the present invention, the cleaning method is selected from at least one of grinding, polishing and ultrasonic cleaning.

[0025] This invention uses graphene oxide slurry as raw material, coating a substrate with a certain thickness of graphene oxide coating. After drying, the graphene oxide coating is cut into specific sizes and stacked sequentially in a graphite mold. The molding pressure is controlled by the height limit of graphite bolts and the elastic force of graphite springs under the bolts to control the density of the graphene bulk. The graphite mold is placed in a high-temperature furnace for high-temperature carbonization and graphitization treatment to obtain self-assembled graphene bulk material. The bulk material is then cut into sheets and surface-treated to obtain graphene thermally conductive interface material.

[0026] According to a particularly preferred embodiment of the present invention, a method for preparing a self-assembled graphene thermally conductive interface material includes the following steps: (1) A graphene oxide coating of a certain thickness is applied to the substrate, and the graphene oxide coating is dried. (2) Cut the above-mentioned dried graphene oxide coating into specific sizes and stack them in a graphite mold in sequence; (3) The above graphite mold is fixed with graphite bolts, and a graphite spring is fitted on each graphite bolt. The tension of the graphite spring is adjusted to control the molding pressure during the high-temperature carbonization heat treatment process. (4) The graphite mold is carbonized in a high-temperature furnace. After the carbonization process is completed, the graphite spring tension is further adjusted to control the molding pressure during the graphitization process. (5) Cut the graphene block into thin slices and clean the surface of the sliced ​​material to obtain the graphene thermal interface material.

[0027] A second aspect of the present invention provides a self-assembled graphene thermally conductive interface material obtained by the preparation method described in the first aspect.

[0028] In some embodiments of the present invention, the density of the self-assembled graphene thermally conductive interface material is 0.05-0.72 g / cm³. 3 The preferred value is 0.40-0.50 g / cm³. 3 Its density is consistent with that of the graphene bulk obtained after graphitization.

[0029] In some embodiments of the present invention, the thermal resistance of the self-assembled graphene thermally conductive interface material is 0.05-0.15℃•cm. 2 / W@40psi.

[0030] In some embodiments of the present invention, the interlayer tensile strength of the self-assembled graphene thermally conductive interface material is 0.02-0.1 MPa.

[0031] A third aspect of the present invention provides the application of the self-assembled graphene thermally conductive interface material according to the second aspect in large-scale integrated circuits, high-power chips / devices and advanced packaging.

[0032] In some embodiments of the present invention, the application scenario is a high heat flux density scenario.

[0033] In some embodiments of the present invention, the application environment is an operating temperature exceeding 125°C and an immersion liquid cooling environment, preferably with mineral oil as the cooling medium.

[0034] The present invention will be described in detail below through embodiments.

[0035] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0036] In the following embodiments and comparative examples, the test methods for the relevant performance indicators are as follows: Density: ASTM D 792-20(2020) Standard test method for the density and specific gravity (relative density) of plastics by displacement; Thermal resistance: ASTM D 5470-17(2024) Standard test method for thermal conductivity of thermally conductive insulating materials; Interlaminar tensile strength: ASTM D 412-16(2021) Method for testing the tensile strength of vulcanized rubber and thermoplastic elastomers; High-temperature aging test: GB / T 2423.3(2016) Environmental testing - Part 2: Test methods; Compatibility test with fluorinated liquid: According to T / CI 208-2023 Test method for high temperature stability and substrate compatibility of liquid-cooled thermal management materials, the compatibility life (h) of the thermally conductive interface material with the fluorinated liquid was tested at 80℃.

[0037] Yield rate test: Calculated based on the ratio of the number of qualified products to the number of products manufactured.

[0038] Example 1 This embodiment illustrates the preparation of self-assembled graphene thermally conductive interface materials.

[0039] (1) Coat a 1 mm thick graphene oxide coating on the substrate, cut the dried graphene oxide coating into 100×100 mm size, and stack them in a graphite fixture. (2) The graphite tooling is fixed with graphite bolts and graphite springs. The tension of the graphite springs is adjusted to control the molding pressure during the high-temperature carbonization heat treatment process. The high-temperature carbonization heat treatment temperature is 1000℃ and the time is 350h. The heating rate in the temperature range of 300-700℃ is 0.02℃ / min. (3) After the high-temperature carbonization heat treatment is completed, the graphite spring tension is adjusted to control the molding pressure of the graphitization process to 0.3MPa, the graphitization temperature to 3050℃, and the time to 2h. (4) Cut the graphitized low-density graphene block into 0.3 mm thick sheets and ultrasonically treat the sheets until no graphite particles adhere to the surface to obtain a self-assembled graphene thermal interface material.

[0040] The molding pressure of the high-temperature carbonization heat treatment process in step (2) was adjusted, and the properties of the resulting material are shown in Table 1: Table 1

[0041] As can be seen from the results in Table 1, the density of the graphene bulk obtained by graphitization increases with the increasing molding pressure applied during high-temperature carbonization. The thermal resistance of the final material first decreases and then increases. The optimal high-temperature carbonization molding pressure is 0.2-0.4 MPa.

[0042] Example 2 This embodiment illustrates the preparation of self-assembled graphene thermally conductive interface materials.

[0043] (1) Coat a 1 mm thick graphene oxide coating on the substrate, cut the dried graphene oxide coating into 100×100 mm size, and stack them in a graphite fixture. (2) The graphite tooling is fixed with graphite bolts and graphite springs. The tension of the graphite springs is adjusted to control the molding pressure of the high-temperature carbonization heat treatment process to 0.3MPa and the high-temperature carbonization temperature to 1000℃. (3) After the high-temperature carbonization heat treatment is completed, the graphite spring tension is adjusted to control the molding pressure of the graphitization process to 0.3MPa, the graphitization temperature to 3050℃, and the time to 2h. (4) Cut the graphitized low-density graphene block into 0.3 mm thick sheets, and subject the sheets to ultrasonic treatment until no graphite particles adhere to the surface, thus obtaining a self-assembled graphene thermal interface material.

[0044] The heating rate within the 300-700℃ temperature range during the high-temperature carbonization process in step (2) was adjusted, and the properties of the resulting material are shown in Table 2. Table 2

[0045] As can be seen from the results in Table 2, as the high-temperature carbonization heating rate increases, the density of the graphene bulk obtained by graphitization remains unchanged at first and then gradually decreases, and the thermal resistance of the material gradually increases. Considering both thermal resistance and interlayer tensile strength, the optimal high-temperature carbonization heating rate is 0.02℃ / min.

[0046] Example 3 This embodiment illustrates the preparation of self-assembled graphene thermally conductive interface materials.

[0047] (1) Coat a 1 mm thick graphene oxide coating on the substrate, cut the dried graphene oxide coating into 100×100 mm size, and stack them in a graphite fixture. (2) The graphite tooling is fixed with graphite bolts and graphite springs. The molding pressure of the high-temperature carbonization heat treatment process is controlled by adjusting the graphite spring tension to 0.3MPa, the high-temperature carbonization temperature is 1000℃, and the time is 350h; the heating rate in the temperature range of 300-700℃ is 0.02℃ / min. (3) After the high-temperature carbonization heat treatment is completed, the graphite spring tension is adjusted to control the molding pressure of the graphitization process. The graphitization temperature is 3050℃ and the time is 2h. (4) Cut the graphitized low-density graphene block into 0.3 mm thick sheets, and subject the sheets to ultrasonic treatment until no graphite particles adhere to the surface, thus obtaining a self-assembled graphene thermal interface material.

[0048] The molding pressure during the graphitization process in step (3) was adjusted, and the properties of the resulting material are shown in Table 3. Table 3

[0049] As can be seen from the results in Table 3, as the molding pressure increases during the graphitization process, the density of the graphene bulk obtained by graphitization gradually increases, and the thermal resistance first decreases and then increases. The preferred graphitization molding pressure is 0.3 MPa.

[0050] Example 4 This embodiment illustrates the preparation of self-assembled graphene thermally conductive interface materials.

[0051] (1) Coat a 1 mm thick graphene oxide coating on the substrate, cut the dried graphene oxide coating into 100×100 mm size, and stack them in a graphite fixture. (2) The graphite tooling is fixed with graphite bolts and graphite springs. The molding pressure of the high-temperature carbonization heat treatment process is controlled by adjusting the graphite spring tension to 0.3MPa, the high-temperature carbonization temperature is 1000℃, and the time is 350h; the heating rate in the temperature range of 300-700℃ is 0.02℃ / min. (3) After the high-temperature carbonization heat treatment is completed, the graphite spring tension is adjusted to control the molding pressure of the graphitization process to 0.3MPa, the graphitization temperature is adjusted, and the graphitization time is 2h. (4) Cut the graphitized low-density graphene block into 0.3 mm thick sheets, and subject the sheets to ultrasonic treatment until no graphite particles adhere to the surface, thus obtaining a self-assembled graphene thermal interface material.

[0052] The temperature during the graphitization process in step (3) was adjusted, and the properties of the resulting material are shown in Table 4. Table 4

[0053] As shown in Table 4, with increasing graphitization temperature, the density of the graphene bulk obtained by graphitization continuously increases, and the thermal resistance of the material continuously decreases. When the graphitization heat treatment temperature reaches 3050℃, the overall performance is even better.

[0054] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a self-assembled graphene thermally conductive interface material, characterized in that, The preparation method includes: stacking graphene oxide coatings and then subjecting them to high-temperature carbonization heat treatment and graphitization treatment in sequence to obtain the self-assembled graphene thermally conductive interface material.

2. The preparation method according to claim 1, wherein, The temperature of the high-temperature carbonization heat treatment is 900-1600℃, preferably 1000℃; Preferably, the heating rate within the temperature range of 300-700℃ is 0.005-0.1℃ / min, more preferably 0.01-0.03℃ / min, and even more preferably 0.02℃ / min; Preferably, the high-temperature carbonization heat treatment time is 350-400 hours.

3. The preparation method according to claim 1 or 2, wherein, The molding pressure of the high-temperature carbonization heat treatment is 0-0.5 MPa, preferably 0.2-0.4 MPa, and more preferably 0.3 MPa; Preferably, the density of the graphene bulk obtained after the high-temperature carbonization heat treatment is 0.01-0.8 g / cm³. 3 The preferred value is 0.04-0.68 g / cm³. 3 Further preferably, it is 0.35-0.45 g / cm³. 3 .

4. The preparation method according to any one of claims 1-3, wherein, The temperature for the graphitization treatment is 2600-3200℃, preferably 2900-3150℃, and more preferably 3050℃; Preferably, the graphitization treatment is carried out at the temperature for 1-3 hours, more preferably 2 hours.

5. The preparation method according to any one of claims 1-4, wherein, The molding pressure of the graphitization treatment is 0-0.9 MPa, preferably 0.3-0.5 MPa, and more preferably 0.3 MPa.

6. The preparation method according to any one of claims 1-5, wherein, The density of the graphene bulk obtained after graphitization treatment is 0.05-0.72 g / cm³. 3 The preferred value is 0.40-0.50 g / cm³. 3 .

7. The preparation method according to any one of claims 1-6, wherein, The graphene bulk material after graphitization was sliced ​​and cleaned to obtain the self-assembled graphene thermally conductive interface material. Preferably, the cleaning method is selected from at least one of grinding, polishing, and ultrasonic cleaning.

8. A self-assembled graphene thermally conductive interface material obtained by the preparation method according to any one of claims 1-7.

9. The self-assembled graphene thermally conductive interface material according to claim 8, wherein, The density of the self-assembled graphene thermally conductive interface material is 0.05-0.72 g / cm³. 3 The preferred value is 0.40-0.50 g / cm³. 3 ; Preferably, the thermal resistance of the self-assembled graphene thermally conductive interface material is 0.05-0.15℃·cm. 2 / W@40psi; Preferably, the interlayer tensile strength of the self-assembled graphene thermally conductive interface material is 0.02-0.1 MPa.

10. The application of the self-assembled graphene thermally conductive interface material according to claim 8 or 9 in large-scale integrated circuits, high-power chips / devices and advanced packaging; Preferably, the application scenario is a high heat flux density scenario; Preferably, the application environment is an operating temperature exceeding 125°C and an immersion liquid cooling environment, with mineral oil being the preferred cooling medium.

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