Graphene heat-conducting interface material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of thermal interface materials, and discloses a graphene heat-conducting interface material as well as a preparation method and application thereof. The method comprises the following steps: (1) performing low-temperature carbonization treatment and calendaring treatment on a graphene oxide coating to obtain a graphene foam film; (2) coating the surface of the graphene foam film with a carbon-based adhesive and drying; and (3) stacking the graphene foam films to obtain a graphene block material, and then performing high-temperature carbonization treatment and graphitization treatment to obtain the graphene heat-conducting interface material. According to the preparation method, the low-density graphene foam film subjected to low-temperature carbonization treatment and calendering treatment and the carbon-based adhesive are used as raw materials, and the high-orientation graphene block material is formed through dehydrogenation and polycondensation in the later-stage heat treatment process by utilizing the characteristic that the low-density graphene foam film and the carbon-based adhesive are loaded with a large number of active functional groups; finally, the low-density graphene heat-conducting interface material which is high in interlayer bonding strength, high in heat conductivity, small in heat resistance and excellent in compression performance is prepared.

Description

Technical Field

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

[0002] Unlike traditional thermal interface materials, graphene thermal interface materials have the characteristics of high longitudinal thermal conductivity, ultra-low thermal resistance, high resilience, high compressibility, and high reliability. They are widely used in thermal management systems for high-power chips, mobile communications, semiconductor lighting, electric vehicles, and aerospace, especially in high heat flux density scenarios such as large-scale integrated circuits, high-power chips / devices, and advanced packaging.

[0003] Traditional preparation processes for graphene thermally conductive interface materials include graphene oxide slurry coating, slurry drying, carbonization, calendering, graphitization, adhesive spraying, foam film stacking, slicing, and surface cleaning. However, these traditional processes suffer from drawbacks such as complex procedures, low yield, high cost, and weak interlayer bonding, limiting their large-scale application. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems existing in the prior art and provide a graphene thermally conductive interface material, its preparation method, and its application.

[0005] This invention utilizes low-density graphene foam film after low-temperature carbonization and calendering treatment, and carbon-based adhesives (such as graphene slurry or carbon black slurry) as raw materials. Taking advantage of the high number of active functional groups loaded in both materials, a highly oriented graphene bulk material is formed through dehydrogenation and polycondensation during subsequent heat treatment. This ultimately yields a low-density graphene thermally conductive interface material with high interlayer bonding strength, high thermal conductivity, low thermal resistance, and excellent compressibility (low density). This invention can further reduce the production cost of graphene thermally conductive interface materials, promoting their application in high heat flux density scenarios such as large-scale integrated circuits, high-power chips / devices, and advanced packaging. Furthermore, this invention does not use resin-based adhesives, making it particularly suitable for use in liquid cooling scenarios such as fluorinated liquids or mineral oils.

[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a graphene thermally conductive interface material, wherein the method includes the following steps: (1) Graphene foam film is obtained by low-temperature carbonization and calendering of graphene oxide coating; (2) Coat the surface of the graphene foam film with a carbon-based adhesive and dry it; (3) Graphene foam films are stacked to obtain graphene bulk material, and then high-temperature carbonization and graphitization are performed to obtain the graphene thermal interface material.

[0007] A second aspect of the present invention provides a graphene thermally conductive interface material obtained according to the preparation method described in the first aspect.

[0008] A third aspect of the present invention provides the application of the graphene thermally conductive interface material according to the second aspect in large-scale integrated circuits, high-power chips / devices and advanced packaging.

[0009] The beneficial technical effects achieved by the present invention through the above technical solution are as follows: (1) In this invention, the graphene foam film and carbon-based adhesive after low-temperature carbonization and calendering are loaded with a large number of active functional groups. During subsequent high-temperature heat treatment, a dehydrogenation condensation reaction occurs between the foam film and the adhesive layer, which can improve the adhesion between the graphene foam film layers.

[0010] (2) The graphene thermally conductive interface material prepared by the method of the present invention does not contain resin adhesives and has a material density as low as 0.20-0.30 g / cm³. 3 Thermal resistance as low as 0.05℃·cm 2 With a tensile strength of approximately 0.10 MPa at / W@40psi, it is particularly suitable for use in liquid cooling scenarios such as fluorinated liquids or mineral oils.

[0011] (3) This invention does not use glue (acrylic resin, silicone rubber, etc.) as adhesive. Only graphite powder layer remains on the surface of the thermal interface material after slicing, which is easier to clean later. This can improve the yield of graphene thermal pads and promote their application in the field of thermal management. Detailed Implementation

[0012] 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.

[0013] The first aspect of this invention provides a method for preparing a graphene thermally conductive interface material, wherein the method includes the following steps: (1) Graphene foam film is obtained by low-temperature carbonization and calendering of graphene oxide coating; (2) Coat the surface of the graphene foam film with a carbon-based adhesive and dry it; (3) Graphene foam films are stacked to obtain graphene bulk material, and then high-temperature carbonization and graphitization are performed to obtain the graphene thermal interface material.

[0014] This invention uses a coated and dried graphene oxide coating as raw material, which is then subjected to low-temperature carbonization and calendering. A carbon-based adhesive is sprayed onto the surface of the calendered graphene foam film, and the layers are stacked sequentially along the thickness direction to form a bulk material. After high-temperature carbonization and graphitization, a graphene thermally conductive interface material is obtained. In practice, at least two graphene foam films can be stacked.

[0015] In this invention, during the subsequent high-temperature heat treatment process, the foam film and adhesive layer condense to form a graphene block with strong interlayer bonding. Since there is no adhesive present, the surface of the graphene block is smooth after slicing, requiring no surface treatment, which can further improve the yield of graphene thermal pads and reduce pad production costs.

[0016] In some embodiments of the present invention, the temperature of the low-temperature carbonization treatment in step (1) is 350-900℃, such as 350℃, 450℃, 550℃, 650℃, 750℃, 850℃, 900℃, etc., and any value within the range of any two of the above values, preferably 350-850℃, and more preferably 450℃.

[0017] In some embodiments of the present invention, the time for the low-temperature carbonization treatment is 30-400 min, such as 30 min, 100 min, 120 min, 200 min, 250 min, 300 min, 350 min, 400 min, etc., and any value within the range of any two of the above values, preferably 120 min.

[0018] In some embodiments of the present invention, the density of the graphene foam film is 0.01-0.2 g / cm³. 3 The preferred value is 0.15 g / cm³. 3 .

[0019] In some embodiments of the present invention, the carbon-based adhesive in step (2) is selected from at least one of graphene slurry, carbon black slurry, carbon nanotube slurry and graphite slurry.

[0020] In some embodiments of the present invention, the solvent of the carbon-based adhesive is selected from at least one of water, ethanol, acetone and dimethylamide, all of which are volatile solvents.

[0021] In some embodiments of the present invention, the coating thickness of the carbon-based adhesive is 1-75 μm, such as 1 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 75 μm, etc., and any value within the range of any two of the above values, preferably 10-50 μm, and more preferably 20 μm.

[0022] In some embodiments of the present invention, the solid content of carbon material in the carbon-based adhesive is 1-10%, such as 1%, 3%, 4.1%, 5%, 7%, 9%, 10%, etc., and any value within the range of any two of the above values, preferably 4-5%.

[0023] In some embodiments of the present invention, the density of the graphene bulk material in step (3) is 0.1-1 g / cm³. 3 For example, 0.1 g / cm³ 3 0.15g / cm 3 0.2g / cm 3 0.3g / cm 3 0.6g / cm 3 0.8g / cm 3 1g / cm 3 And, any value within the range of any two of the above values, preferably 0.15-1 g / cm³. 3 Further preferred is 0.3 g / cm³ 3 .

[0024] In some embodiments of the present invention, the stacked graphene bulk material is placed in a graphite fixture and the density is adjusted (the height of the graphite bolts is adjusted), and then subjected to high-temperature carbonization and graphitization treatment.

[0025] In some embodiments of the present invention, the temperature of the high-temperature carbonization treatment is 900-1600℃, such as 900℃, 1000℃, 1200℃, 1400℃, 1600℃, etc., and any value within the range of any two of the above values, preferably 1000℃.

[0026] In some embodiments of the present invention, the high-temperature carbonization treatment time is 30-180 min, such as 30 min, 60 min, 100 min, 120 min, 150 min, 180 min, etc., and any value within the range of any two of the above values, preferably 60 min.

[0027] In some embodiments of the present invention, the temperature of the graphitization treatment is 2800-3200℃, such as 2800℃, 2900℃, 3000℃, 3100℃, 3200℃, etc., and any value within the range of any two of the above values, preferably 3100℃.

[0028] In some embodiments of the present invention, the graphitization treatment time is 10-120 min, such as 10 min, 30 min, 60 min, 90 min, 120 min, etc., and any value within the range of any two of the above values, preferably 30 min.

[0029] In some embodiments of the present invention, the graphitized material is sliced ​​and cleaned to obtain the graphene thermal interface material. The graphene thermal interface material can be used as a graphene thermal pad.

[0030] In some embodiments of the present invention, the cleaning method is polishing or ultrasonic cleaning.

[0031] A second aspect of the present invention provides a graphene thermally conductive interface material obtained according to the preparation method described in the first aspect.

[0032] In some embodiments of the present invention, the thermal resistance of the graphene thermally conductive interface material is 0.05-0.11 °C·cm. 2 / W@40psi.

[0033] In some embodiments of the present invention, the interlayer tensile strength of the graphene thermally conductive interface material is 0.03-0.12 MPa.

[0034] In some embodiments of the present invention, the density of the graphene thermally conductive interface material is 0.20-0.60 g / cm³. 3 The preferred value is 0.20-0.30 g / cm³. 3 .

[0035] A third aspect of the present invention provides the application of the graphene thermally conductive interface material according to the second aspect in large-scale integrated circuits, high-power chips / devices and advanced packaging.

[0036] In some embodiments of the present invention, the application scenario is a liquid cooling scenario, preferably a fluorinated liquid or mineral oil scenario.

[0037] The present invention will be described in detail below through embodiments.

[0038] 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.

[0039] In the following embodiments and comparative examples, the test methods for the relevant performance indicators are as follows: 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; Density: ASTM D 792-20(2020) Standard test method for the density and specific gravity (relative density) of plastics by displacement; Yield rate: Calculated as the ratio of qualified products to total output under the same process; the qualified products must meet the following standards: Appearance: Smooth surface, no cracks; Density: ≤0.60g / cm³ 3 ; Thermal resistance: ≤0.08℃·cm 2 / W@40psi; Compression deformation: ≥30%@40psi; Interlaminar tensile strength: ≥0.03MPa; 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℃.

[0040] Example 1 This embodiment illustrates the preparation of graphene thermally conductive interface materials.

[0041] (1) The coated and dried graphene oxide coating was placed in a carbonization furnace for low-temperature carbonization for 120 min; then the material after low-temperature carbonization was calendered, and the density of the graphene foam film obtained after calendering was controlled to be 0.15 g / cm³. 3 ; (2) Spray a layer of graphene slurry (solid content of 4.1% and solvent of water) with a thickness of 20 μm onto the surface of the graphene foam film and dry it; (3) Graphene foam films are stacked sequentially along the thickness direction to obtain graphene bulk material; it is placed in a graphite fixture, and the height of the graphite bolts is adjusted to control the density of the graphene bulk material to 0.3 g / cm³. 3 ; (4) Place the graphite apparatus in a carbonization furnace and perform high-temperature carbonization treatment at 1000℃ for 60 min; then place it in a graphitization furnace and perform graphitization treatment at 3100℃ for 30 min to obtain low-density graphene bulk material. (5) 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 the graphene thermal interface material.

[0042] The temperature of the low-temperature carbonization process in step (1) was adjusted, and the performance indicators of the resulting materials are shown in Table 1.

[0043] Table 1

[0044] The results in Table 1 show that as the low-temperature carbonization temperature increases, the density of the final graphene thermally conductive interface material increases, and the thermal resistance first decreases and then increases. When the low-temperature carbonization temperature is 450℃, its thermal resistance is 0.05℃•cm. 2 / W@40psi, the interlaminar tensile strength reached 0.12MPa.

[0045] Example 2

[0046] This embodiment illustrates the preparation of graphene thermally conductive interface materials.

[0047] (1) The coated and dried graphene oxide coating was placed in a carbonization furnace and carbonized at 450°C for 120 min; then the carbonized material was calendered to control the density of the resulting graphene foam film to be 0.15 g / cm³. 3 ; (2) Spray a layer of graphene slurry (solid content of 4.1%, solvent of water) onto the surface of the graphene foam film and dry it; (3) Graphene foam films are stacked sequentially along the thickness direction to obtain graphene bulk material; it is placed in a graphite fixture, and the height of the graphite bolts is adjusted to control the density of the graphene bulk material to 0.3 g / cm³. 3 ; (4) Place the graphite apparatus in a carbonization furnace and perform high-temperature carbonization treatment at 1000℃ for 60 min; then place it in a graphitization furnace and perform graphitization treatment at 3100℃ for 30 min to obtain low-density graphene bulk material. (5) 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 the graphene thermal interface material.

[0048] The thickness of the graphene slurry in step (2) was adjusted, and the performance indicators of each material are shown in Table 2.

[0049] Table 2

[0050] As can be seen from the results in Table 2, as the coating thickness of graphene slurry increases, the thermal resistance of the graphene thermal interface material continuously increases, while the density does not change significantly.

[0051] Example 3

[0052] This embodiment illustrates the preparation of graphene thermally conductive interface materials.

[0053] (1) The coated and dried graphene oxide coating was placed in a carbonization furnace and carbonized at 450°C for 120 min; then the carbonized material was calendered to control the density of the resulting graphene foam film to be 0.15 g / cm³. 3 ; (2) Spray a layer of graphene slurry (solid content of 4.1% and solvent of water) with a thickness of 20 μm onto the surface of the graphene foam film and dry it; (3) Stack the graphene foam film along the thickness direction to obtain the graphene bulk material; place it in the graphite fixture and adjust the height of the graphite bolts to control the density of the graphene bulk material. (4) Place the graphite apparatus in a carbonization furnace and perform high-temperature carbonization treatment at 1000℃ for 60 min; then place it in a graphitization furnace and perform graphitization treatment at 3100℃ for 30 min to obtain graphene bulk material. (5) 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 the graphene thermal interface material.

[0054] The density of the graphene bulk material in step (2) was adjusted, and the performance indicators of each material are shown in Table 3.

[0055] Table 3

[0056] As can be seen from the results in Table 3, as the density of the graphene bulk material increases, the thermal resistance of the graphene thermal interface material first decreases and then increases, while the interlayer tensile strength continuously increases.

[0057] Example 4

[0058] This embodiment illustrates the preparation of graphene thermally conductive interface materials.

[0059] (1) The coated and dried graphene oxide coating was placed in a carbonization furnace and carbonized at 450°C for 120 min; then the carbonized material was calendered to control the density of the resulting graphene foam film to be 0.15 g / cm³. 3 ; (2) Spray a layer of graphene slurry (solid content of 4.1% and solvent of water) with a thickness of 20 μm onto the surface of the graphene foam film and dry it; (3) Graphene foam films are stacked sequentially along the thickness direction to obtain graphene bulk material; it is placed in a graphite fixture, and the height of the graphite bolts is adjusted to control the density of the graphene bulk to 0.3 g / cm³. 3 ; (4) Place the graphite apparatus in a carbonization furnace and perform high-temperature carbonization treatment at 1000℃ for 60 min; then place it in a graphitization furnace and perform graphitization treatment for 30 min to obtain low-density graphene bulk material. (5) 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 the graphene thermal interface material.

[0060] The temperature of graphitization in step (4) was adjusted, and the performance indicators of the resulting materials are shown in Table 4.

[0061] Table 4

[0062] As shown in Table 4, the thermal resistance of the graphene thermal interface material continuously decreases with increasing graphitization temperature, while the interlayer tensile strength remains around 0.12 MPa. When the heat treatment temperature reaches 3200℃, the interfacial thermal resistance drops to 0.04℃·cm. 2 / W@40psi.

[0063] Comparative Example 1 (1) The coated and dried graphene oxide coating was placed in a carbonization furnace and carbonized at 1000℃ for 60 min; then the carbonized graphene coating was mechanically calendered to control its density to 0.2 g / cm³. 3 The thickness is 150μm; (2) The above materials are then subjected to graphitization treatment at 3000℃ for 30 minutes to obtain graphene foam film; (3) Coat the surface of the graphene foam film with a layer of acrylic adhesive (number average molecular weight of 1200) and dry it; (4) Graphene foam films coated with adhesive are stacked sequentially along the thickness direction to obtain a graphene bulk material; it is placed in a graphite fixture, and the height of the graphite bolts is adjusted to control the density of the graphene bulk material to 0.6 g / cm³. 3 ; (5) Cut the graphene bulk material into thin slices with a thickness of 0.3 mm, and polish the slices until the surface is clean and tidy to obtain the graphene thermal interface material.

[0064] The coating thickness of the acrylic adhesive was adjusted, and the performance indicators of each material are shown in Table 5.

[0065] Table 5

[0066] As can be seen from the results in Table 5, as the adhesive thickness increases, the thermal resistance and interlayer tensile strength of the material remain basically unchanged, but the overall interlayer tensile strength is lower than that of the graphene thermally conductive interface material of the present invention.

[0067] 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 graphene thermally conductive interface material, characterized in that, The method includes the following steps: (1) Graphene foam film is obtained by low-temperature carbonization and calendering of graphene oxide coating; (2) Coat the surface of the graphene foam film with a carbon-based adhesive and dry it; (3) Graphene foam films are stacked to obtain graphene bulk material, and then high-temperature carbonization and graphitization are performed to obtain the graphene thermal interface material.

2. The preparation method according to claim 1, wherein, The temperature of the low-temperature carbonization treatment in step (1) is 350-900℃, preferably 350-850℃, and more preferably 450℃; Preferably, the low-temperature carbonization treatment time is 30-400 min, and more preferably 120 min; Preferably, the density of the graphene foam film is 0.01-0.2 g / cm³. 3 The preferred value is 0.15 g / cm³. 3 .

3. The preparation method according to claim 1 or 2, wherein, The carbon-based adhesive mentioned in step (2) is selected from at least one of graphene slurry, carbon black slurry, carbon nanotube slurry and graphite slurry; Preferably, the solvent of the carbon-based adhesive is selected from at least one of water, ethanol, acetone and dimethylamide; Preferably, the coating thickness of the carbon-based adhesive is 1-75 μm, more preferably 10-50 μm, and even more preferably 20 μm; Preferably, the carbon material in the carbon-based adhesive has a solid content of 1-10%, more preferably 4-5%.

4. The preparation method according to any one of claims 1-3, wherein, The density of the graphene bulk material mentioned in step (3) is 0.1-1 g / cm³. 3 Preferably, it is 0.15-1 g / cm³. 3 Further preferred is 0.3 g / cm³ 3 ; Preferably, the stacked graphene bulk material is placed in a graphite fixture and its density is adjusted before undergoing high-temperature carbonization and graphitization.

5. The preparation method according to any one of claims 1-4, wherein, The high-temperature carbonization treatment is carried out at a temperature of 900-1600℃, preferably 1000℃; Preferably, the high-temperature carbonization treatment time is 30-180 min, and more preferably 60 min.

6. The preparation method according to any one of claims 1-5, wherein, The temperature for graphitization treatment is 2800-3200℃, preferably 3100℃; Preferably, the graphitization treatment time is 10-120 min, and more preferably 30 min.

7. The preparation method according to any one of claims 1-6, wherein, The graphitized material was sliced ​​and cleaned to obtain the graphene thermally conductive interface material. Preferably, the cleaning method is polishing or ultrasonic cleaning.

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

9. The graphene thermally conductive interface material according to claim 8, wherein, The thermal resistance of the graphene thermally conductive interface material is 0.05-0.11℃·cm. 2 / W@40psi; Preferably, the interlayer tensile strength of the graphene thermally conductive interface material is 0.03-0.12 MPa; Preferably, the density of the graphene thermally conductive interface material is 0.20-0.60 g / cm³. 3 The preferred value is 0.20-0.30 g / cm³. 3 .

10. The application of the 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 liquid cooling scenario, and more preferably a fluorinated liquid or mineral oil scenario.

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