Preparation method of graphene heat-conducting film for chip heat dissipation

Abstract

The invention discloses a preparation method of a graphene heat conduction film for chip heat dissipation, and relates to the field of graphene materials, and the preparation method comprises the following specific steps: step 1, preparing a graphene base material; 2, functional materials are prepared; 3, auxiliary materials are prepared, wherein the auxiliary materials comprise a film-forming agent, a solvent and an auxiliary reagent; 4, preparing a transition layer; 5, preparing composite heat dissipation slurry; step 6, layered coating; 7, gradient drying and curing; according to the method, the infrared radiation material can improve the heat transfer speed of the graphene to the heat dissipation layer, and the auxiliary material can enhance the dispersity of the infrared radiation filler, avoid coating agglomeration and improve the heat dissipation effect; the surface of graphene is pre-coated with a hydroxylated graphene transition layer of 50-100 nm, the hydroxylated graphene transition layer and amino / carbonyl of a film-forming agent can form hydrogen-bond interaction, the peel strength of a heat dissipation layer and graphene is improved to 2.5 N / cm, and the transition layer has high thermal conductivity.

Description

Technical Field

[0001] This invention relates to the field of graphene materials, and more specifically to a method for preparing a graphene thermally conductive film for chip heat dissipation. Background Technology

[0002] With the rapid development of technologies such as 5G communication and artificial intelligence, the computing power of electronic devices such as smart terminals and server chips continues to increase, and the power density per unit volume increases dramatically. The large amount of waste heat generated has become a key factor restricting the performance stability and service life of these devices. Due to the space constraints of these devices, traditional heat dissipation methods such as fans and water cooling are difficult to adapt, making thin and efficient thin-film heat dissipation materials a key focus of industry research and development.

[0003] Graphene, with its extremely high intrinsic thermal conductivity, has shown broad application prospects in the field of thermal conductive films. Graphene-based thermal conductive films have been gradually applied to chip heat dissipation in devices such as mobile phones and computers. However, existing graphene thermal conductive films have a core technological bottleneck: graphene itself has a low specific heat capacity. Even by increasing the thermal conductivity or increasing the film thickness, only rapid heat conduction and short-term heat storage can be achieved, like a "heat-conducting pool with limited capacity." When the film temperature is equal to the heat source temperature, it cannot continuously absorb and dissipate heat, leading to the failure of heat dissipation function and making it difficult to meet the heat dissipation requirements of high-power chips for long-term stable operation.

[0004] To address the aforementioned issues, related technologies propose coating a thermally activated material onto the surface of a graphene material layer to form a heat dissipation functional layer. This utilizes the thermally activated material's ability to convert heat energy into visible light, achieving continuous heat dissipation and mitigating the "heat-conducting but not heat-dissipating" deficiency of traditional graphene thermal conductive films to some extent. However, this technology still has significant shortcomings: Firstly, the heat dissipation path is singular, relying solely on the conversion of heat energy into visible light. When ambient light intensity is high or the thermally activated material experiences light decay, the heat dissipation efficiency drops significantly, resulting in insufficient heat dissipation stability in extreme scenarios. Secondly, the interfacial bonding between the thermally activated material and the graphene material layer is weak, leading to high interfacial thermal resistance, which affects heat conduction efficiency. Furthermore, this technology only provides passive heat dissipation, making it unsuitable for applications with dynamic fluctuations in chip power and lacking real-time monitoring methods for heat dissipation status, thus hindering the prediction of device overheating risks.

[0005] In summary, a method for preparing graphene thermally conductive films for chip heat dissipation was designed. Summary of the Invention

[0006] In order to overcome the above-mentioned shortcomings, the present invention provides a method for preparing a graphene thermally conductive film for chip heat dissipation.

[0007] The present invention achieves the above objectives through the following technical solutions: A method for preparing a graphene thermally conductive film for chip heat dissipation includes the following specific steps: Step 1: Preparation of graphene substrate. The graphene substrate includes materials with a thickness of 80-120μm and a thermal conductivity higher than 1000. Graphene film; Step 2: Preparation of functional materials, including thermally activated materials, infrared radiation materials, temperature-responsive materials, conductive sensing materials, and interfacial thermal bridge materials; Step 3: Preparation of auxiliary materials, including film-forming agents, solvents, and auxiliary reagents; Step 4: Preparation of the transition layer. The graphene surface is hydroxylated, with a hydroxyl content of more than 5% and a hydroxylation thickness of 50-100 nm. The hydroxylated transition layer can form hydrogen bonds with the amino / carbonyl groups of the film-forming agent, increasing the peel strength between the heat dissipation layer and graphene from 1.2 N / cm to 2.5 N / cm. The transition layer itself has high thermal conductivity, avoiding the limitation of traditional solvent wetting, which can only relieve interfacial stress but cannot reduce thermal resistance. Step 5: Preparation of composite heat dissipation paste. The composite heat dissipation paste includes a bottom functional paste, a middle sensing paste, and a top responsive paste. The bottom functional paste includes 5% film-forming agent, 20% thermally activated material, 8% infrared radiation material, 3% silver nanowires, and 64% solvent in the following mass ratio. The middle sensing paste includes 3% film-forming agent, 20% carboxylated carbon nanotube dispersion, and 77% solvent in the following mass ratio. The top responsive paste includes 4% film-forming agent, 15% temperature-sensitive phosphor, and 81% solvent in the following mass ratio. Step 6: Layered coating. The functional slurry is coated onto the hydroxylated graphene film in sequence, followed by the sensing slurry in the middle layer and the responsive slurry in the top layer. Step 7: Gradient drying and curing. Gradient drying and curing of the layered graphene film can not only gradually remove the solvent in the coating and avoid problems such as cracking and peeling, but also ensure the quality and functional stability of the film. Step 8: Trimming and performance testing.

[0008] Preferably, the specific steps of step one are as follows: S11. Store the graphene film in a moisture-proof cabinet with a humidity of ≤30% for later use to avoid moisture affecting the subsequent process. S12. Cut the graphene film according to the size of the chip, while leaving a processing allowance of 5-10mm for subsequent edge trimming. S13. Soak the cut graphene film in anhydrous ethanol for 10 minutes, then clean it with a 100W ultrasonic cleaner for 5 minutes to thoroughly remove the oil and impurities attached to the surface. S14. Place the cleaned graphene film in a vacuum oven at 60°C and dry for 30 minutes to remove residual ethanol and prevent moisture from interfering with the subsequent interface bonding quality.

[0009] Preferably, in step two, the particle size of the thermally activated material is 5-8 μm. Inorganic phosphors, hexagonal boron nitride nanosheets with a thickness of 5-10 nm and a particle size of 2-3 μm for infrared radiation materials, and temperature-responsive materials with a particle size of 3-5 μm. The temperature-sensitive phosphor uses carboxylated carbon nanotubes with a diameter of 10-20 nm and a length of 5-10 μm as the conductive sensing material, and silver nanowires with a diameter of 50 nm and a length of 10 μm as the interfacial thermal bridge material. It also acts as an infrared radiation filler, utilizing its high emissivity within the 8-14 μm "atmospheric window" to directly convert some of the heat energy into infrared radiation, unaffected by ambient light, thus complementing the visible light conversion. The silver nanowires penetrate the interface between the thermally excited material particles and graphene, reducing the contact thermal resistance (from the original 0.1-0.2). Reduced to <0.05 This accelerates the transfer of heat from graphene to the heat dissipation layer; the temperature-responsive material is a "temperature-sensitive phosphor" (such as...). The luminescence intensity of the phosphor is linearly negatively correlated with temperature (within the range of 25-150℃, the luminescence intensity decreases by 8%-10% for every 10℃ increase in temperature): Under low load (chip temperature <50℃): the phosphor luminescence intensity is high, the visible light heat dissipation path accounts for 60%, and the infrared radiation accounts for 40%, meeting the basic heat dissipation requirements; Under high load (chip temperature ≥50℃): the phosphor luminescence intensity weakens, and the heat dissipation ratio of the infrared radiation filler automatically increases to 70%, quickly dissipating a large amount of heat through the radiation path to avoid a sudden temperature rise; Carbon nanotubes form a three-dimensional conductive network, and its resistance changes with the temperature of the heat dissipation layer (the resistance decreases by 3%-4% for every 10℃ increase in temperature). The resistance change is monitored by an external microcontroller (MCU), and the heat dissipation film temperature is calculated in real time, indirectly reflecting the chip heat dissipation status; When the resistance drops to the threshold (corresponding to a chip temperature ≥85℃), auxiliary heat dissipation measures (such as micro fan startup, chip frequency reduction) can be triggered, forming an "active-passive collaborative" intelligent heat dissipation closed loop.

[0010] Preferably, the specific steps of step two are as follows: S21. Place the inorganic phosphor in an oven at 120°C and dry for 2 hours to remove the moisture adsorbed on the surface of the material and ensure its heat dissipation activity. S22. Plasma treatment of hexagonal boron nitride nanosheets for 3 minutes under argon atmosphere and 200W power condition enhances the surface activity of the material and improves its compatibility with other components. S23. Dry the temperature-sensitive phosphor in a vacuum environment at 80°C for 1 hour to remove moisture and impurities; S24. Disperse carboxylated carbon nanotubes in N-methylpyrrolidone and sonicate for 30 minutes to prepare a carboxylated carbon nanotube dispersion with a mass fraction of 0.5%, which effectively avoids carbon nanotube aggregation. S25. Dry the silver nanowires in a vacuum environment at 60°C for 30 minutes before use to ensure that they can fully play their role in reducing interfacial thermal resistance.

[0011] Preferably, the specific steps of step three are as follows: S31. The film-forming agent is selected from polyimide powder and polyetheretherketone powder, which are mixed in a mass ratio of 7:3. The particle size of the polyimide powder is 20μm. This combination can simultaneously ensure the adhesion, light transmittance and high temperature resistance of the film after formation, and is suitable for the heat dissipation requirements of high-power chips (above 200W). S32. The solvent used is N-methylpyrrolidone and dimethyl sulfoxide. N-methylpyrrolidone and dimethyl sulfoxide are mixed in a volume ratio of 6:4 to improve the solubility and dispersion stability of each functional material and avoid coating agglomeration. S33. The auxiliary reagents are anhydrous ethanol and deionized water.

[0012] Preferably, step four involves using a plasma surface treatment instrument, setting a mixed atmosphere of oxygen and argon with a volume ratio of 1:4, a processing power of 150W, a processing time of 8 minutes, and a pressure controlled at 10Pa. After processing, the graphene film is quickly removed and stored to prevent impurities in the air from adsorbing onto its surface and affecting the hydroxylation effect. The degree of hydroxylation needs to be detected by X-ray photoelectron spectroscopy (XPS).

[0013] Preferably, the specific steps of step five are as follows: S51. Preparation of the underlying functional slurry: First, the film-forming agent is added to the solvent and stirred for 3 hours at a high speed of 2000 r / min to ensure that the film-forming agent is completely dissolved. Then, silver nanowires, h-BN nanosheets, and thermally activated materials are added sequentially. After each material is added, the mixture is stirred for 1 hour to ensure that the components are mixed evenly. Finally, the mixture is allowed to stand for 30 minutes under a vacuum of -0.09 MPa to remove air bubbles in the slurry and avoid the formation of pores during the subsequent coating process, which would affect heat dissipation and structural stability. S52. Preparation of the intermediate sensing slurry: First, add the film-forming agent to the solvent and stir at 1500 r / min for 2 hours until the film-forming agent is completely dissolved. Then, slowly add the carboxylated carbon nanotube dispersion while stirring at 1000 r / min for 1.5 hours. Finally, disperse the dispersion for 20 minutes using a 150W ultrasonic device to ensure uniform distribution of carbon nanotubes without agglomeration, thus ensuring the continuity and stability of the sensing network. S53. Preparation of the top-layer responsive slurry: First, dissolve the film-forming agent in the solvent and stir at 1800 r / min for 2.5 hours to ensure complete dissolution. Then, add the temperature-sensitive phosphor and stir for 1 hour. After standing under a vacuum of -0.09 MPa for 20 minutes to remove bubbles, a uniform top-layer responsive slurry is obtained, ensuring the uniformity and temperature response sensitivity of the subsequent coating layer.

[0014] Preferably, the specific steps of step six are as follows: S61. Coating of the underlying functional slurry: Fix the hydroxylated graphene film on the coating table, and use a high-precision four-sided coater to evenly coat the underlying functional slurry on the surface of the graphene film. Control the wet film coating thickness to be 10-12μm, and ensure that the underlying thickness reaches 8-10μm after drying. During the coating process, avoid phenomena such as missed coating and sagging to ensure the integrity and uniformity of the underlying functional layer. S62. After the coating of the intermediate sensing slurry is completed, let it stand for 5 minutes until the slurry initially adheres and stabilizes. Then, use a high-precision four-sided coater to coat the intermediate sensing slurry on the surface of the bottom layer. Control the wet film coating thickness to be 3-4μm and the thickness after drying to be 2-3μm. During the coating process, the coating speed should be kept uniform to ensure that the intermediate layer and the bottom layer interface are tightly bonded and there is no risk of delamination. S63. Top layer responsive slurry coating: After the middle layer sensing slurry is coated, let it stand for 3 minutes, then apply the top layer responsive slurry at a uniform speed of 5 mm / s. Control the wet film coating thickness to be 5-6 μm, and the thickness after drying to be 3-4 μm. The entire layer coating process must be kept clean to avoid impurities from entering the coating and affecting product performance.

[0015] Preferably, the specific steps of step seven are as follows: S71, First stage: Place the coated graphene film in a 60℃ environment for 1 hour to slowly remove most of the solvent and prevent rapid drying from generating bubbles. S72, Second stage: Heat to 80℃ and hold for 1.5 hours to further remove residual solvent; S73, Third stage: Heat to 120℃ and hold for 30 minutes to promote cross-linking and curing of the film-forming agent and improve the stability of the coating structure; S74, Fourth stage: Cool naturally to room temperature, control the cooling rate to ≤5℃ / min to avoid thermal stress causing coating cracking. After drying, the total coating thickness must be between 13-17μm, and the coating must be free of bubbles, cracks, and peeling. The peel strength between the coating and the graphene substrate must be no less than 2.5N / cm.

[0016] Preferably, the specific steps of step eight are as follows: S81. Trimming: Use a high-precision die-cutting machine to cut the dried and cured graphene thermal conductive film, remove the reserved processing allowance, and obtain a finished film that precisely matches the chip size, ensuring that the size error is controlled within ±0.1mm to meet the accuracy requirements of chip installation. S82. Performance testing: In terms of thermal performance, the in-plane thermal conductivity is tested using the laser flare method, and a value higher than 1200 is required. The interface thermal resistance, tested using a thermal resistance tester, must be controlled to be <0.05. The heat dissipation performance was verified through chip simulation testing. Under an initial temperature of 48.3℃, the stable temperature after 1 hour should be ≤42.0℃. The sensing performance was tested using a multimeter to measure the resistance-temperature response relationship. Within the range of 25-150℃, the resistance should decrease by 3%-4% for every 10℃ increase in temperature. In terms of mechanical performance, the peel strength between the coating and the graphene substrate was tested using a tensile testing machine, requiring a strength greater than 2.5N / cm. At the same time, a thermal cycling test (-40℃ to 120℃, 1000 cycles) was conducted to ensure that the performance degradation rate was <5%. The appearance inspection was carried out by visual observation, requiring the coating to be uniform and without obvious defects.

[0017] The beneficial effects of this invention are: in the preparation method of the graphene thermally conductive film for chip heat dissipation, Infrared radiation materials can increase the heat transfer rate from graphene to the heat dissipation layer, and the addition of auxiliary materials can enhance the dispersibility of infrared radiation fillers, prevent coating agglomeration, and improve heat dissipation. A 50-100nm hydroxylated graphene transition layer is pre-coated on the graphene surface, which can form hydrogen bonds with the amino / carbonyl groups of the film-forming agent, thereby increasing the peel strength between the heat dissipation layer and graphene to 2.5 N / cm. The transition layer itself has high thermal conductivity, avoiding the limitation of traditional solvent wetting, which can only relieve interfacial stress but cannot reduce thermal resistance. The conductive sensing material forms a three-dimensional conductive network, and its resistance changes with the temperature of the heat dissipation layer. Temperature-sensitive phosphors exhibit a linear negative correlation between luminescence intensity and temperature. Under low load, the phosphor exhibits high luminescence intensity, with visible light accounting for 60% of heat dissipation and infrared radiation accounting for 40%, thus meeting basic heat dissipation requirements. Under high load, the phosphor's luminescence intensity decreases, and the heat dissipation ratio of infrared radiation filler automatically increases to 70%, rapidly dissipating a large amount of heat through the radiation path to prevent a sudden temperature rise. Attached Figure Description

[0018] The present invention will be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a flowchart illustrating the method steps of the present invention. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0020] like Figure 1 As shown, a method for preparing a graphene thermally conductive film for chip heat dissipation includes the following specific steps: Step 1: Preparation of graphene substrate. The graphene substrate includes materials with a thickness of 80-120μm and a thermal conductivity higher than 1000. Graphene film; Step 2: Preparation of functional materials, including thermally activated materials, infrared radiation materials, temperature-responsive materials, conductive sensing materials, and interfacial thermal bridge materials; Step 3: Preparation of auxiliary materials, including film-forming agents, solvents, and auxiliary reagents; Step 4: Preparation of the transition layer. The graphene surface is hydroxylated, with a hydroxyl content of more than 5% and a hydroxylation thickness of 50-100 nm. The hydroxylated transition layer can form hydrogen bonds with the amino / carbonyl groups of the film-forming agent, increasing the peel strength between the heat dissipation layer and graphene from 1.2 N / cm to 2.5 N / cm. The transition layer itself has high thermal conductivity, avoiding the limitation of traditional solvent wetting, which can only relieve interfacial stress but cannot reduce thermal resistance. Step 5: Preparation of composite heat dissipation paste. The composite heat dissipation paste includes a bottom functional paste, a middle sensing paste, and a top responsive paste. The bottom functional paste includes 5% film-forming agent, 20% thermally activated material, 8% infrared radiation material, 3% silver nanowires, and 64% solvent in the following mass ratio. The middle sensing paste includes 3% film-forming agent, 20% carboxylated carbon nanotube dispersion, and 77% solvent in the following mass ratio. The top responsive paste includes 4% film-forming agent, 15% temperature-sensitive phosphor, and 81% solvent in the following mass ratio. Step 6: Layered coating. The functional slurry is coated onto the hydroxylated graphene film in sequence, followed by the sensing slurry in the middle layer and the responsive slurry in the top layer. Step 7: Gradient drying and curing. Gradient drying and curing of the layered graphene film can not only gradually remove the solvent in the coating and avoid problems such as cracking and peeling, but also ensure the quality and functional stability of the film. Step 8: Trimming and performance testing.

[0021] Specifically, the steps of step one are as follows: S11. Store the graphene film in a moisture-proof cabinet with a humidity of ≤30% for later use to avoid moisture affecting the subsequent process. S12. Cut the graphene film according to the size of the chip, while leaving a processing allowance of 5-10mm for subsequent edge trimming. S13. Soak the cut graphene film in anhydrous ethanol for 10 minutes, then clean it with a 100W ultrasonic cleaner for 5 minutes to thoroughly remove the oil and impurities attached to the surface. S14. Place the cleaned graphene film in a vacuum oven at 60°C and dry for 30 minutes to remove residual ethanol and prevent moisture from interfering with the subsequent interface bonding quality.

[0022] Specifically, in step two, the particle size of the thermally activated material is 5-8 μm. Inorganic phosphors, hexagonal boron nitride nanosheets with a thickness of 5-10 nm and a particle size of 2-3 μm for infrared radiation materials, and temperature-responsive materials with a particle size of 3-5 μm. The temperature-sensitive phosphor uses carboxylated carbon nanotubes with a diameter of 10-20 μm and a length of 5-10 μm as the conductive sensing material, and silver nanowires with a diameter of 50 nm and a length of 10 μm as the interfacial thermal bridge material. It also acts as an infrared radiation filler, utilizing its high emissivity within the 8-14 μm "atmospheric window" to directly convert some of the heat energy into infrared radiation, unaffected by ambient light, thus complementing the visible light conversion. The silver nanowires penetrate the interface between the thermally excited material particles and graphene, reducing the contact thermal resistance (from the original 0.1-0.2). Reduced to <0.05 This accelerates the transfer of heat from graphene to the heat dissipation layer; the temperature-responsive material is a "temperature-sensitive phosphor" (such as...). The luminescence intensity of the phosphor is linearly negatively correlated with temperature (within the range of 25-150℃, the luminescence intensity decreases by 8%-10% for every 10℃ increase in temperature): Under low load (chip temperature <50℃): the phosphor luminescence intensity is high, the visible light heat dissipation path accounts for 60%, and the infrared radiation accounts for 40%, meeting the basic heat dissipation requirements; Under high load (chip temperature ≥50℃): the phosphor luminescence intensity weakens, and the heat dissipation ratio of the infrared radiation filler automatically increases to 70%, quickly dissipating a large amount of heat through the radiation path to avoid a sudden temperature rise; Carbon nanotubes form a three-dimensional conductive network, and its resistance changes with the temperature of the heat dissipation layer (the resistance decreases by 3%-4% for every 10℃ increase in temperature). The resistance change is monitored by an external microcontroller (MCU), and the heat dissipation film temperature is calculated in real time, indirectly reflecting the chip heat dissipation status; When the resistance drops to the threshold (corresponding to a chip temperature ≥85℃), auxiliary heat dissipation measures (such as micro fan startup, chip frequency reduction) can be triggered, forming an "active-passive collaborative" intelligent heat dissipation closed loop.

[0023] Specifically, the steps of step two are as follows: S21. Place the inorganic phosphor in an oven at 120°C and dry for 2 hours to remove the moisture adsorbed on the surface of the material and ensure its heat dissipation activity. S22. Plasma treatment of hexagonal boron nitride nanosheets for 3 minutes under argon atmosphere and 200W power condition enhances the surface activity of the material and improves its compatibility with other components. S23. Dry the temperature-sensitive phosphor in a vacuum environment at 80°C for 1 hour to remove moisture and impurities; S24. Disperse carboxylated carbon nanotubes in N-methylpyrrolidone and sonicate for 30 minutes to prepare a carboxylated carbon nanotube dispersion with a mass fraction of 0.5%, which effectively avoids carbon nanotube aggregation. S25. Dry the silver nanowires in a vacuum environment at 60°C for 30 minutes before use to ensure that they can fully play their role in reducing interfacial thermal resistance.

[0024] Specifically, the steps of step three are as follows: S31. The film-forming agent is selected from polyimide powder and polyetheretherketone powder, which are mixed in a mass ratio of 7:3. The particle size of the polyimide powder is 20μm. This combination can simultaneously ensure the adhesion, light transmittance and high temperature resistance of the film after formation, and is suitable for the heat dissipation requirements of high-power chips (above 200W). S32. The solvent used is N-methylpyrrolidone and dimethyl sulfoxide. N-methylpyrrolidone and dimethyl sulfoxide are mixed in a volume ratio of 6:4 to improve the solubility and dispersion stability of each functional material and avoid coating agglomeration. S33. The auxiliary reagents are anhydrous ethanol and deionized water.

[0025] Specifically, step four involves using a plasma surface treatment instrument, setting up a mixed atmosphere of oxygen and argon with a volume ratio of 1:4, a processing power of 150W, a processing time of 8 minutes, and a pressure controlled at 10Pa. After processing, the graphene film is quickly removed and stored to prevent impurities in the air from adsorbing onto its surface and affecting the hydroxylation effect. The degree of hydroxylation needs to be detected by X-ray photoelectron spectroscopy (XPS).

[0026] Specifically, the steps in step five are as follows: S51. Preparation of the underlying functional slurry: First, the film-forming agent is added to the solvent and stirred for 3 hours at a high speed of 2000 r / min to ensure that the film-forming agent is completely dissolved. Then, silver nanowires, h-BN nanosheets, and thermally activated materials are added sequentially. After each material is added, the mixture is stirred for 1 hour to ensure that the components are mixed evenly. Finally, the mixture is allowed to stand for 30 minutes under a vacuum of -0.09 MPa to remove air bubbles in the slurry and avoid the formation of pores during the subsequent coating process, which would affect heat dissipation and structural stability. S52. Preparation of the middle layer sensing slurry: First, add the film-forming agent to the solvent and stir at 1500 r / min for 2 hours until the film-forming agent is completely dissolved; then slowly add the carboxylated carbon nanotube dispersion while stirring at 1000 r / min for 1.5 hours; finally, disperse the carbon nanotubes for 20 minutes using a 150W ultrasonic device to ensure uniform distribution of the carbon nanotubes without agglomeration, thus ensuring the continuity and stability of the sensing network. S53. Preparation of top-layer responsive slurry: First, dissolve the film-forming agent in the solvent and stir at 1800 r / min for 2.5 hours to ensure complete dissolution of the film-forming agent; then add the temperature-sensitive phosphor, stir for 1 hour, and let stand under a vacuum of -0.09 MPa for 20 minutes to remove bubbles, so as to obtain a uniform top-layer responsive slurry, which ensures the uniformity and temperature response sensitivity of the subsequent coating layer.

[0027] Specifically, the steps of step six are as follows: S61. Coating of the underlying functional slurry: Fix the hydroxylated graphene film on the coating table, and use a high-precision four-sided coater to evenly coat the underlying functional slurry on the surface of the graphene film. Control the wet film coating thickness to be 10-12μm, and ensure that the underlying thickness reaches 8-10μm after drying. During the coating process, avoid phenomena such as missed coating and sagging to ensure the integrity and uniformity of the underlying functional layer. S62. After the coating of the intermediate sensing slurry is completed, let it stand for 5 minutes until the slurry initially adheres and stabilizes. Then, use a high-precision four-sided coater to coat the intermediate sensing slurry on the surface of the bottom layer. Control the wet film coating thickness to be 3-4μm and the thickness after drying to be 2-3μm. During the coating process, the coating speed should be kept uniform to ensure that the intermediate layer and the bottom layer interface are tightly bonded and there is no risk of delamination. S63. Top layer responsive slurry coating: After the middle layer sensing slurry is coated, let it stand for 3 minutes, then apply the top layer responsive slurry at a uniform speed of 5 mm / s. Control the wet film coating thickness to be 5-6 μm, and the thickness after drying to be 3-4 μm. The entire layer coating process must be kept clean to avoid impurities from entering the coating and affecting product performance.

[0028] Specifically, the steps of step seven are as follows: S71, First stage: Place the coated graphene film in a 60℃ environment for 1 hour to slowly remove most of the solvent and prevent rapid drying from generating bubbles. S72, Second stage: Heat to 80℃ and hold for 1.5 hours to further remove residual solvent; S73, Third stage: Heat to 120℃ and hold for 30 minutes to promote cross-linking and curing of the film-forming agent and improve the stability of the coating structure; S74, Fourth stage: Cool naturally to room temperature, control the cooling rate to ≤5℃ / min to avoid thermal stress causing coating cracking. After drying, the total coating thickness must be between 13-17μm, and the coating must be free of bubbles, cracks, and peeling. The peel strength between the coating and the graphene substrate must be no less than 2.5N / cm.

[0029] Specifically, the steps of step eight are as follows: S81. Trimming: Use a high-precision die-cutting machine to cut the dried and cured graphene thermal conductive film, remove the reserved processing allowance, and obtain a finished film that precisely matches the chip size, ensuring that the size error is controlled within ±0.1mm to meet the accuracy requirements of chip installation. S82. Performance testing: In terms of thermal performance, the in-plane thermal conductivity is tested using the laser flare method, and a value higher than 1200 is required. The interface thermal resistance, tested using a thermal resistance tester, must be controlled to be <0.05. The heat dissipation performance was verified through chip simulation testing. Under an initial temperature of 48.3℃, the stable temperature after 1 hour should be ≤42.0℃. The sensing performance was tested using a multimeter to measure the resistance-temperature response relationship. Within the range of 25-150℃, the resistance should decrease by 3%-4% for every 10℃ increase in temperature. In terms of mechanical performance, the peel strength between the coating and the graphene substrate was tested using a tensile testing machine, requiring a strength greater than 2.5N / cm. At the same time, a thermal cycling test (-40℃ to 120℃, 1000 cycles) was conducted to ensure that the performance degradation rate was <5%. The appearance inspection was carried out by visual observation, requiring the coating to be uniform and without obvious defects.

[0030] Implementation Case 1: Adapting to a medium-power consumer-grade chip (80W) Preparation parameters Graphene substrate: 80μm thick, thermal conductivity 1000 ; Functional materials: Inorganic phosphor (particle size 5μm), h-BN nanosheets (thickness 5nm, particle size 2μm) Temperature-sensitive phosphor (3μm particle size), carboxylated carbon nanotubes (10nm diameter, 5μm length), and silver nanowires (50nm diameter, 10μm length). Composite slurry: Prepared strictly according to the mass ratio of the bottom layer (5% film-forming agent + 20% thermally activated material + 8% h-infrared radiation material + 3% silver nanowires + 64% solvent), the middle layer (3% film-forming agent + 20% 0.5% carboxylated carbon nanotube dispersion + 77% solvent), and the top layer (4% film-forming agent + 15% temperature-sensitive phosphor + 81% solvent); Process parameters: hydroxylation treatment, layered coating (bottom wet film 10μm / middle wet film 3μm / top wet film 5μm), gradient drying (60℃ / 1h→80℃ / 1.5h→120℃ / 30min→natural cooling).

[0031] Performance test results The performance of the graphene thermal conductive film in reference patent CN115190748A, "A Continuous Heat Dissipation Graphene Thermal Conductive Film and Its Preparation Method and Application", is compared with that of the graphene thermal conductive film in the application.

[0032]

[0033] Comparative analysis This patented product utilizes a dual-path heat dissipation mechanism of "thermal excitation + infrared radiation," resulting in a stable temperature that is 5°C lower than existing technologies after 1 hour, significantly improving heat dissipation sustainability. The synergistic effect of the hydroxylated transition layer and the silver nanowires reduces interfacial thermal resistance by 72% and increases peel strength by 116.7%, addressing the weakness of interfacial bonding in existing technologies. The newly added conductive sensing network enables real-time temperature monitoring, a function absent in existing technologies. Thermal cycling stability is improved by 63.8%, meeting the long-term usage requirements of consumer-grade chips.

[0034] Implementation Case 2: Adapting to High-Power Server Chips (200W) Preparation parameters Graphene substrate: 100μm thick, thermal conductivity 1300 ; Functional materials: Inorganic phosphor (particle size 6μm), hexagonal boron nitride nanosheets (thickness 8nm, particle size 2.5μm), Temperature-sensitive phosphor (particle size 4μm), carboxylated carbon nanotubes (diameter 15nm, length 8μm), silver nanowires (diameter 50nm, length 10μm). Composite slurry: The bottom, middle and top layer formulations are the same as in Case 1, except that the blending ratio of polyimide powder and polyetheretherketone powder in the film-forming agent is optimized to 7:3 to meet the high-temperature resistance requirements of high-power heat dissipation. Process parameters: The hydroxylation treatment parameters remain unchanged, the layer coating thickness is adjusted to 11μm for the bottom wet film, 3.5μm for the middle wet film, and 5.5μm for the top wet film, and the gradient drying parameters remain the same.

[0035] Performance test results The performance of the graphene thermal conductive film in reference patent CN115190748A, "A Continuous Heat Dissipation Graphene Thermal Conductive Film and Its Preparation Method and Application", is compared with that of the graphene thermal conductive film in the application.

[0036]

[0037] Comparative analysis For high-temperature operating conditions of high-power server chips, this product improves the in-plane thermal conductivity by 9.2% and reduces the interfacial thermal resistance by 68.3% by optimizing the film-forming agent formulation and coating thickness. The stable temperature after 1 hour is reduced by 6.9℃, avoiding the coating failure problem caused by high temperature in existing technologies. The high-temperature resistance is significantly better than existing technologies, and the resistance sensing function can provide real-time warning of chip overheating risk, which cannot be achieved by existing technologies. The peel strength is improved by 115.4%, meeting the structural stability requirements of server chips under long-term vibration environment.

[0038] Implementation Case 3: Adapting to Ultra-thin Smart Terminal Chips (50W) Preparation parameters Graphene substrate: 120μm thick, thermal conductivity 1100 ; Functional materials: Inorganic phosphor (particle size 8μm), hexagonal boron nitride nanosheets (thickness 10nm, particle size 3μm). Temperature-sensitive phosphor (5 μm particle size), carboxylated carbon nanotubes (20 nm diameter, 10 μm length), and silver nanowires (50 nm diameter, 10 μm length). Composite slurry: The formulations of the bottom layer, middle layer, and top layer are consistent with those in Case 1. The NMP / DMSO volume ratio in the solvent system is maintained at 6:4 to ensure that the slurry's fluidity is suitable for ultra-thin coating requirements. Process parameters: The hydroxylation treatment parameters remain unchanged. The layered coating thickness is adjusted to 12μm for the bottom wet film, 4μm for the middle wet film, and 6μm for the top wet film. The gradient drying parameters are consistent, and the final total coating thickness is controlled at 17μm.

[0039]

[0040] Comparative analysis This product is designed for ultra-thin smart terminals in high-light environments. Although the overall thickness is 8% greater than existing technologies, the in-plane thermal conductivity is improved by 19.1%, and the interface thermal resistance is reduced by 67.9%. The stable temperature decreases by 4.6℃ after 1 hour, and the heat dissipation efficiency attenuation rate under strong light is only 18.4% of that of existing technologies, solving the pain point of existing technologies' single visible light heat dissipation path being affected by ambient light. The peel strength is improved by 125%, ensuring that the coating does not peel off during the assembly and use of terminal devices. The newly added sensing function can adapt to the dynamic power fluctuations of terminal chips. Existing technologies can only provide passive heat dissipation and cannot meet the refined heat dissipation needs of smart terminals.

[0041] Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a graphene thermally conductive film for chip heat dissipation, characterized in that: The specific steps include the following: Step 1: Preparation of graphene substrate. The graphene substrate includes materials with a thickness of 80-120μm and a thermal conductivity higher than 1000. Graphene film; Step 2: Preparation of functional materials, including thermally activated materials, infrared radiation materials, temperature-responsive materials, conductive sensing materials, and interfacial thermal bridge materials; Step 3: Preparation of auxiliary materials, including film-forming agents, solvents, and auxiliary reagents; Step 4: Preparation of transition layer. The graphene surface is hydroxylated, with a hydroxyl content of more than 5% and a hydroxylation thickness of 50-100 nm. Step 5: Preparation of composite heat dissipation paste. The composite heat dissipation paste includes a bottom functional paste, a middle sensing paste, and a top responsive paste. The bottom functional paste includes 5% film-forming agent, 20% thermally activated material, 8% infrared radiation material, 3% silver nanowires, and 64% solvent in the following mass ratio. The middle sensing paste includes 3% film-forming agent, 20% carboxylated carbon nanotube dispersion, and 77% solvent in the following mass ratio. The top responsive paste includes 4% film-forming agent, 15% temperature-sensitive phosphor, and 81% solvent in the following mass ratio. Step 6: Layered coating. The functional slurry is coated onto the hydroxylated graphene film in sequence, followed by the sensing slurry in the middle layer and the responsive slurry in the top layer. Step 7: Gradient drying and curing, the graphene film after layered coating is subjected to gradient drying and curing; Step 8: Trimming and performance testing.

2. The method for preparing the graphene thermally conductive film for chip heat dissipation according to claim 1, characterized in that: The specific steps of step one are as follows: S11. Store the graphene film in a dehumidifying cabinet with a humidity of ≤30% for later use. S12. Cut the graphene film according to the size of the chip; S13. Soak the cut graphene film in anhydrous ethanol for 10 minutes, and then clean it with a 100W ultrasonic device for 5 minutes. S14. Place the cleaned graphene film in a vacuum oven at 60°C and dry for 30 minutes.

3. The method for preparing the graphene thermally conductive film for chip heat dissipation according to claim 1, characterized in that: In step two, the particle size of the thermally activated material is 5-8 μm. Inorganic phosphors, hexagonal boron nitride nanosheets with a thickness of 5-10 nm and a particle size of 2-3 μm for infrared radiation materials, and temperature-responsive materials with a particle size of 3-5 μm. The temperature-sensitive phosphor uses carboxylated carbon nanotubes with a diameter of 10-20 nm and a length of 5-10 μm as the conductive sensing material, and silver nanowires with a diameter of 50 nm and a length of 10 μm as the interfacial thermal bridge material.

4. The method for preparing the graphene thermally conductive film for chip heat dissipation according to claim 3, characterized in that: The specific steps of step two are as follows: S21. Place the inorganic phosphor in an oven at 120°C and dry for 2 hours; S22. Plasma treatment of hexagonal boron nitride nanosheets was carried out for 3 minutes under an argon atmosphere and a power of 200W. S23. Dry the temperature-sensitive phosphor in a vacuum environment at 80°C for 1 hour; S24. Disperse carboxylated carbon nanotubes in N-methylpyrrolidone and sonicate for 30 minutes to prepare a carboxylated carbon nanotube dispersion with a mass fraction of 0.5%. S25. Dry the silver nanowires in a vacuum environment at 60°C for 30 minutes before use.

5. The method for preparing a graphene thermally conductive film for chip heat dissipation according to claim 1, characterized in that: The specific steps of step three are as follows: S31. The film-forming agent is selected from polyimide powder and polyetheretherketone powder, which are mixed in a mass ratio of 7:

3. The particle size of the polyimide powder is 20μm. S32. The solvent used is N-methylpyrrolidone and dimethyl sulfoxide, and N-methylpyrrolidone and dimethyl sulfoxide are mixed in a volume ratio of 6:

4. S33. The auxiliary reagents are anhydrous ethanol and deionized water.

6. The method for preparing a graphene thermally conductive film for chip heat dissipation according to claim 1, characterized in that: The specific steps of step four are as follows: using a plasma surface treatment instrument, setting a mixed atmosphere of oxygen and argon with a volume ratio of oxygen to argon of 1:4, a processing power of 150W, a processing time of 8 minutes, and a pressure controlled at 10Pa; after processing, quickly removing the graphene film and storing it.

7. The method for preparing a graphene thermally conductive film for chip heat dissipation according to claim 1, characterized in that: The specific steps of step five are as follows: S51. Preparation of the underlying functional slurry: First, the film-forming agent is added to the solvent and stirred for 3 hours at a high speed of 2000 r / min to ensure that the film-forming agent is completely dissolved; then, silver nanowires, h-BN nanosheets, and thermally activated materials are added sequentially, and stirring is continued for 1 hour after each material is added to ensure that the components are mixed evenly; finally, the slurry is allowed to stand for 30 minutes under a vacuum of -0.09 MPa to remove air bubbles. S52. Preparation of the intermediate layer sensing slurry: First, add the film-forming agent to the solvent and stir at 1500 r / min for 2 hours until the film-forming agent is completely dissolved; then slowly add the carboxylated carbon nanotube dispersion while stirring at 1000 r / min for 1.5 hours; finally, disperse the dispersion for 20 minutes using a 150W ultrasonic device to ensure uniform distribution of carbon nanotubes without agglomeration. S53. Preparation of top-layer responsive slurry: First, dissolve the film-forming agent in the solvent and stir at 1800 r / min for 2.5 hours to ensure that the film-forming agent is completely dissolved; then add the temperature-sensitive phosphor, stir for 1 hour, and let stand under a vacuum of -0.09 MPa for 20 minutes to remove bubbles, and obtain a uniform top-layer responsive slurry.

8. The method for preparing a graphene thermally conductive film for chip heat dissipation according to claim 1, characterized in that: The specific steps of step six are as follows: S61. Underlying functional slurry coating: Fix the hydroxylated graphene film on the coating table, and use a high-precision four-sided coater to evenly coat the underlying functional slurry on the surface of the graphene film. Control the wet film coating thickness to be 10-12μm, and ensure that the underlying thickness reaches 8-10μm after drying. S62. After the coating of the intermediate layer sensing slurry and the coating of the bottom functional slurry are completed, let it stand for 5 minutes. After the slurry is initially adhered and stabilized, use a high-precision four-sided coater to coat the intermediate layer sensing slurry on the bottom surface. Control the wet film coating thickness to be 3-4μm and the thickness after drying to be 2-3μm. S63. Top layer response slurry coating: After coating the middle layer sensing slurry, let it stand for 3 minutes, then coat the top layer response slurry at a uniform speed of 5 mm / s, controlling the wet film coating thickness to be 5-6 μm, and the thickness after drying to be 3-4 μm.

9. The method for preparing a graphene thermally conductive film for chip heat dissipation according to claim 1, characterized in that: The specific steps of step seven are as follows: S71, First stage: Place the coated graphene film in a 60℃ environment for 1 hour to slowly remove most of the solvent and prevent rapid drying from generating bubbles. S72, Second stage: Heat to 80℃ and hold for 1.5 hours to further remove residual solvent; S73, Third stage: Heat to 120℃ and hold for 30 minutes to promote cross-linking and curing of the film-forming agent and improve the stability of the coating structure; S74, Fourth stage: Allow the coating to cool naturally to room temperature, controlling the cooling rate to ≤5℃ / min to avoid thermal stress causing cracking.

10. The method for preparing a graphene thermally conductive film for chip heat dissipation according to claim 1, characterized in that: The specific steps of step eight are as follows: S81. Trimming: Use a high-precision die-cutting machine to cut the dried and cured graphene thermal conductive film, remove the reserved processing allowance, and obtain a finished film that precisely matches the chip size. S82. Performance testing: In terms of thermal performance, the in-plane thermal conductivity is tested using the laser flare method, and the requirement is higher than... The interface thermal resistance, tested using a thermal resistance tester, must be controlled to be <0.

05. The heat dissipation performance was verified through chip simulation testing. Under an initial temperature of 48.3℃, the stable temperature after 1 hour should be ≤42.0℃. The sensing performance was tested using a multimeter to measure the resistance-temperature response relationship. Within the range of 25-150℃, the resistance should decrease by 3%-4% for every 10℃ increase in temperature. In terms of mechanical performance, the peel strength between the coating and the graphene substrate was tested using a tensile testing machine, requiring a strength greater than 2.5N / cm. At the same time, thermal cycling tests were conducted to ensure that the performance degradation rate was <5%. The appearance inspection was carried out by visual observation, requiring the coating to be uniform and without obvious defects.

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