High-thermal-conductivity film for chip heat dissipation and preparation method of high-thermal-conductivity film

Abstract

The invention relates to the technical field of heat conduction films, in particular to a high-heat-conduction film for chip heat dissipation and a preparation method of the high-heat-conduction film. The preparation method comprises the following steps: dispersing graphene oxide in a solvent to prepare a graphene oxide dispersion liquid, introducing and adding a coupling agent, carrying out a mixing reaction to obtain graphene oxide slurry, directly coating two surfaces of an ultrathin porous copper foil with the graphene oxide slurry by taking the ultrathin porous copper foil activated by dilute sulphuric acid as a base material, carrying out heat treatment to reduce the graphene oxide slurry, and carrying out heat treatment to obtain the ultrathin porous copper foil. Copper in the middle layer can be effectively diffused between graphene sheet layers to form a graphene-copper composite structure; and carrying out carbonization, graphitization and vacuum hot pressing treatment to obtain the high-thermal-conductivity film for heat dissipation of the chip. The in-plane heat conductivity of the high-heat-conductivity film for chip heat dissipation is larger than or equal to 2012 W / mK, the out-plane heat conductivity of the high-heat-conductivity film is larger than or equal to 95 W / mK, and the high-heat-conductivity film has excellent heat dissipation performance and mechanical performance. Meanwhile, the preparation method is simple and easy to implement, mild in operation condition, economical, environmentally friendly and suitable for large-scale production.

Description

Technical Field

[0001] This application relates to the field of thermal conductive film technology, and in particular to a high thermal conductivity film for chip heat dissipation and its preparation method. Background Technology

[0002] With the miniaturization and integration of electronic products, the thermal management of chips has become increasingly prominent. Existing heat dissipation materials include metals, ceramics, and polymer-based composite materials. Among them, polymer-based materials have attracted attention due to their lightweight and flexibility, but their thermal conductivity is generally low (usually <5W / m·K), making it difficult to meet the heat dissipation requirements of high-power chips.

[0003] Graphene is a type of carbon atom arranged in sp... 2 Two-dimensional carbon nanomaterials with a hexagonal honeycomb lattice composed of hybrid orbitals have a theoretical thermal conductivity of 5300 W / (m·K), making them one of the best thermally conductive materials known to date. Based on this property, graphene thermal conductive films are widely used in heat conduction and heat dissipation fields such as mobile phones, computers, 5G base stations, and military applications.

[0004] Graphene thermal conductive films are typically prepared using graphene oxide as a precursor through processes such as coating, carbonization, graphitization, and pressing. While retaining the original hexagonal structure of graphene, graphene oxide contains numerous functional groups such as hydroxyl, carboxyl, and epoxy groups on its surface and edges. These functional groups enable graphene oxide to maintain good dispersibility in solvents such as water, ethanol, and DMF, and enhance its self-assembly properties in solvents, thus facilitating film formation.

[0005] The graphene oxide films produced by existing processes are stacked together by self-assembled layers, with the layers attracted by van der Waals forces. During the heat treatment process, the oxygen-containing functional groups are gradually reduced, releasing a large amount of gas, which causes the graphene film to expand violently. This makes it prone to cracking or even bursting during subsequent use, resulting in waste. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this application provides a high thermal conductivity film for chip heat dissipation and its preparation method. First, graphene oxide is dispersed in a solvent to prepare a graphene oxide dispersion. Then, a coupling agent is added and mixed to obtain a graphene oxide slurry. Next, using an ultrathin porous copper foil activated with dilute sulfuric acid as a substrate, the graphene oxide slurry is directly coated onto both sides of the ultrathin porous copper foil. During heat treatment to reduce the graphene oxide slurry, copper in the intermediate layer can be effectively diffused between the graphene sheets, forming a graphene-copper composite structure. Vacuum hot pressing removes all air from the graphene layers, allowing copper to better diffuse into the various cavities within the graphene layers. A three-dimensional thermal conductivity structure is formed between the isolated copper and graphene sheets, resulting in a more compact internal structure and reduced heat loss. In this process, a specific coupling agent is introduced during the slurry preparation. This agent reacts with the oxygen-containing functional groups (hydroxyl, carboxyl, and epoxy groups) on the graphene oxide, connecting the individual layers of graphene oxide and significantly improving the interfacial bonding strength with the surface of the ultrathin porous copper foil. During the drying and film formation process, the heating temperature during drying promotes self-crosslinking, making the graphene oxide more tightly connected. This also acts as a fixation agent during heat treatment, reducing expansion caused by gas release. The high thermal conductivity film for chip heat dissipation prepared in this application has an in-plane thermal conductivity ≥2012 W / mK and an out-of-plane thermal conductivity ≥95 W / mK, exhibiting excellent heat dissipation and mechanical properties. Furthermore, the preparation method of this application is simple and easy to implement, with mild operating conditions, and is economical and environmentally friendly, making it suitable for large-scale production.

[0007] In a first aspect, this application provides a method for preparing a high thermal conductivity film for chip heat dissipation, employing the following technical solution: A method for preparing a high thermal conductivity film for chip heat dissipation includes the following steps: S1. According to the mass fraction, 10-20 parts of graphene oxide are placed into a solution consisting of 50 parts of ethanol and 150 parts of deionized water, and ultrasonically dispersed for 60-80 minutes to obtain a graphene oxide dispersion. S2. According to the mass fraction, mix 300 parts of graphene oxide dispersion with 0.1-0.2 parts of coupling agent, and sonicate for 3-4 hours to obtain graphene oxide slurry; S3. Using pretreated ultrathin porous copper foil as the coating substrate, first coat one side of the pretreated ultrathin porous copper foil with graphene oxide slurry and place it in an oven to dry into a film. Then, perform the same coating and drying process on the other side to obtain a graphene oxide copper composite film. S4. Under a nitrogen atmosphere, the graphene oxide copper composite film is preheated to obtain a preheated graphene oxide copper composite film; the preheating temperature is 200-250℃ and the time is 12-16 hours. S5. Under a nitrogen atmosphere, the preheated graphene oxide copper composite film is carbonized to obtain a carbonized graphene oxide copper composite film. S6. Under a nitrogen atmosphere, the carbonized graphene oxide copper composite film is graphitized to obtain a graphitized graphene oxide copper composite film. S7. The graphitized graphene oxide copper composite film is subjected to vacuum hot pressing to obtain a high thermal conductivity film for chip heat dissipation.

[0008] By employing the above technical solutions, graphene oxide is selected as the primary thermally conductive material due to its unique two-dimensional layered structure and excellent thermal conductivity. After dispersion and reduction treatment, graphene oxide can form a dense layered structure, which facilitates the formation of a high thermal conductivity film. Ethanol and deionized water are used as solvent systems for the dispersion of graphene oxide. The mixed solvent of ethanol and water effectively disperses graphene oxide and provides the necessary conditions for subsequent reactions. Coupling agents are used to enhance the interfacial bonding strength between graphene oxide and the substrate. By reacting with the oxygen-containing functional groups on graphene oxide, coupling agents can improve the connection strength and stability of graphene oxide sheets. Ultrathin porous copper foil serves as the substrate, providing not only physical support but also forming a composite structure with graphene oxide during heat treatment, enhancing thermal conductivity. S1: Graphene oxide is ultrasonically dispersed to ensure uniform distribution in the solvent, providing a basis for subsequent mixing and coating. S2: The graphene oxide dispersion is mixed with a coupling agent and subjected to ultrasonic reaction to further enhance the bonding strength and stability of the graphene oxide. S3: Graphene oxide slurry is coated and dried to form a film, creating a preliminary graphene oxide-copper composite structure. S4: The graphene oxide-copper composite film is preheated to further reduce the graphene oxide and enhance its bonding with the copper foil. S5: Carbonization treatment improves the thermal conductivity of the graphene oxide. S6: Graphitization treatment further optimizes the structure and thermal conductivity of the graphene oxide. S7: Vacuum hot pressing ensures that air inside the graphene layer is expelled, allowing copper to better diffuse into the graphene layer, forming a three-dimensional thermally conductive structure. Through the synergistic effect of these steps, the final high thermal conductivity film exhibits excellent heat dissipation and mechanical properties, while maintaining the simplicity, ease of preparation, and economic and environmental benefits of the method.

[0009] Preferably, in step S1, the method for preparing the graphene oxide includes the following steps: S21. According to the mass fraction, add 3 parts graphite powder and 1 part potassium nitrate into the reaction vessel, place the reaction vessel in an ice-water bath, stir at a stirring speed of 700 rpm, and slowly add 120 parts of sulfuric acid with a mass concentration of 98%, continue stirring, and react for 2 hours to obtain solution A. S22, according to the mass fraction, add 12 parts of potassium permanganate to solution A, stir at 700 rpm, react for 1-1.5 hours to obtain solution B, then transfer solution B to a 30℃ water bath, stir at 700 rpm for 1 hour, add 250 parts of distilled water and continue stirring until the solution turns brown, then raise the water bath temperature to 93℃ and react for 1-2 hours to obtain solution C; S23, add 40 parts of 30% hydrogen peroxide to solution C according to the mass fraction until no more bubbles are produced in solution C. Filter while hot to obtain a brownish-yellow insoluble substance. Wash with dilute hydrochloric acid and distilled water by centrifugation 8 times until complete precipitation. Collect the precipitate and dialyze it with distilled water at 25°C for 8 days to obtain the product. S24. The product is placed in a freeze dryer and freeze-dried at -60°C for 24 hours to obtain graphene oxide.

[0010] By employing the above technical solutions, the pretreatment of graphite powder involves the following steps: Graphite powder is converted into graphene oxide through the reaction of potassium nitrate and sulfuric acid. Potassium nitrate acts as an oxidant, improving reaction efficiency. Sulfuric acid, as a strong acid medium, facilitates the oxidation reaction. The addition of potassium permanganate further oxidizes the carbon atoms in the graphite powder, converting them into graphene oxide. Simultaneously, the addition of potassium permanganate also enhances the oxidation capacity of the solution. Control of reaction conditions is achieved by controlling the reaction temperature and time to ensure the completeness of the oxidation reaction. Simultaneously, controlling the stirring speed ensures uniform mixing of reactants and uniform reaction. The addition of hydrogen peroxide further oxidizes residual carbon atoms in the solution, ensuring the purity of the graphene oxide. Simultaneously, the addition of hydrogen peroxide also enhances the oxidation capacity of the solution. Washing and dialysis are performed: impurities and unreacted reagents are removed from the solution through washing with dilute hydrochloric acid and distilled water. Dialysis is used to remove small molecule impurities from the solution, ensuring the purity of the graphene oxide. Freeze-drying: Freeze-drying removes moisture from graphene oxide, yielding dried graphene oxide powder. This method maintains the structural integrity of graphene oxide and improves its thermal conductivity.

[0011] Preferably, in step S2, the coupling agent is composed of bis(dioctylpyrophosphoryloxy)ethylene titanate and vinyltriethoxysilane in a mass ratio of 1:1.

[0012] By employing the above technical solutions, bis(dioctylpyrophosphate)ethylene titanate is used to improve the adhesion between the material and the metal surface. It can react with oxygen-containing functional groups (such as hydroxyl, carboxyl, and epoxy groups) on graphene oxide to form stable chemical bonds. This helps to connect the individual layers of graphene oxide, enhancing the overall structure of the material. Vinyltriethoxysilane is used to improve the adhesion between the material and the metal surface. It can react with oxygen-containing functional groups on graphene oxide to form silicon-oxygen bonds, thereby enhancing the interfacial bonding strength between graphene oxide and the surface of ultrathin porous copper foil. When these two coupling agents are mixed in a 1:1 mass ratio, they can synergistically act on the oxygen-containing functional groups of graphene oxide to form stable chemical bonds. This synergistic effect not only enhances the connection between graphene oxide layers but also improves the interfacial bonding strength between graphene oxide and the copper foil surface. During the drying and film formation process, this synergistic effect helps to tightly connect the graphene oxide, forming a more stable structure. During the heat treatment process, this synergistic effect acts as a fixation mechanism, reducing expansion caused by gas release and thus ensuring the stability of the preparation process. Through this synergistic effect, the high thermal conductivity film prepared in this application exhibits excellent heat dissipation and mechanical properties.

[0013] Preferably, in step S3, the preparation method of the pretreated ultrathin porous copper foil is as follows: immerse the ultrathin porous copper foil in a sulfuric acid solution with a mass concentration of 2%, the immersion temperature is 20-25℃, the immersion time is 0.5-1 minute, after taking it out, rinse it with deionized water 3 times, and then dry the surface moisture to obtain the pretreated ultrathin porous copper foil.

[0014] By employing the above-mentioned technical solution, sulfuric acid, a strong oxidizing and corrosive agent, can effectively remove oil, oxides, and other impurities from the surface of copper foil. Immersion in a sulfuric acid solution cleans the copper foil surface, improving the efficiency and effectiveness of subsequent coating processes. Sulfuric acid treatment activates the copper foil surface, increasing its surface activity. Surface activation helps improve the adhesion and bonding strength between graphene oxide and the copper foil surface. Immersion time and temperature need to be controlled during sulfuric acid treatment to avoid excessive corrosion that could damage the copper foil structure. Simultaneously, this step also helps maintain the pore structure of the ultrathin porous copper foil, which is crucial for subsequent coating and heat treatment processes. After sulfuric acid treatment, the surface cleaning and activation effects of the ultrathin porous copper foil significantly improve the adhesion and bonding strength of the graphene oxide slurry on the copper foil surface. Maintaining the integrity of the pore structure also contributes to the uniform coating of the graphene oxide slurry and subsequent heat treatment processes. Sulfuric acid treatment not only improves the cleanliness and activity of the copper foil surface but also maintains the pore structure of the copper foil by controlling the immersion conditions. These factors work together to ensure that the graphene oxide slurry can be uniformly coated on the copper foil surface and form a stable graphene-copper composite structure during subsequent heat treatment.

[0015] Preferably, the thickness of the ultrathin porous copper foil is 6-8 μm and the porosity is 1000-1500 mesh.

[0016] Preferably, in step S3, the coating thickness is 0.3-0.5 mm, the drying temperature is 60-70°C, and the drying time is 30-40 minutes.

[0017] Preferably, in step S5, the carbonization process conditions are as follows: heating to 800-1000℃ at a heating rate of 4-5℃ / min, and then holding at that temperature for 3-4 hours.

[0018] Preferably, in step S6, the graphitization process conditions are as follows: first, the temperature is increased to 1000-1200℃ at a heating rate of 20-25℃ / min and held for 30-40 minutes, and then the temperature is increased to 2700-2900℃ at a heating rate of 5-7℃ / min and held for 3-4 hours.

[0019] Preferably, in step S7, the process conditions for the vacuum hot pressing treatment are as follows: the graphitized graphene oxide copper composite film is vacuum pressed at 1210-1250℃ using a vacuum flat press, with a vacuum degree of 0.5-1 Pa, a pressure of 20-50 MPa, and a pressing time of 20-30 minutes.

[0020] Secondly, this application provides a high thermal conductivity film for chip heat dissipation, employing the following technical solution: As a general technical concept, this application also provides the above-mentioned high thermal conductivity film for chip heat dissipation, which is prepared by the above-mentioned method for preparing high thermal conductivity film for chip heat dissipation.

[0021] In summary, the beneficial technical effects of this application are as follows: 1. Improved heat dissipation performance: The high thermal conductivity film prepared in this application exhibits excellent heat dissipation performance. The in-plane thermal conductivity reaches ≥2012 W / mK, and the out-of-plane thermal conductivity reaches ≥95 W / mK. This high thermal conductivity can effectively improve the chip's heat dissipation efficiency, reduce the chip's operating temperature, and extend the chip's lifespan.

[0022] 2. Enhanced Mechanical Properties: The high thermal conductivity film prepared in this application possesses excellent mechanical properties. This means that in practical applications, the film can withstand certain mechanical pressure and impact, and is not easily broken or damaged.

[0023] 3. Simplified preparation process: The preparation method of this application is simple and easy to implement, with mild operating conditions. This makes the technology easy to mass-produce, reduces production costs, and ensures product quality and consistency.

[0024] 4. Economic and Environmentally Friendly: The preparation method of this application is economical and environmentally friendly. It uses environmentally friendly materials and processes, reducing the impact on the environment. Furthermore, due to the simple production process and low energy consumption, it contributes to achieving green manufacturing.

[0025] 5. Improved interfacial bonding strength: By introducing a specific coupling agent during the slurry preparation process, the interfacial bonding strength between graphene oxide and the surface of ultrathin porous copper foil was improved. This not only helps to improve the stability of the film but also reduces performance loss caused by interfacial problems.

[0026] 6. Formation of a three-dimensional thermal conductivity structure: Through vacuum hot pressing, the air inside the graphene layer is expelled, allowing copper to diffuse better into the various cavities within the graphene layer, forming a three-dimensional thermal conductivity structure. This structure helps improve thermal conductivity while reducing heat loss. Detailed Implementation

[0027] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0028] In the following examples and preparation examples, 1 part represents 50g.

[0029] Preparation Example 1: Preparation of Graphene Oxide The method for preparing the graphene oxide includes the following steps: S21. According to the mass fraction, add 3 parts graphite powder and 1 part potassium nitrate into the reaction vessel, place the reaction vessel in an ice-water bath, stir at a stirring speed of 700 rpm, and slowly add 120 parts of sulfuric acid with a mass concentration of 98%, continue stirring, and react for 2 hours to obtain solution A. S22, according to the mass fraction, add 12 parts of potassium permanganate to solution A, stir at 700 rpm and react for 1.3 hours to obtain solution B. Then transfer solution B to a 30°C water bath and stir at 700 rpm for 1 hour. Then add 250 parts of distilled water and continue stirring until the solution turns brown. Then raise the water bath temperature to 93°C and react for 1.2 hours to obtain solution C. S23, add 40 parts of 30% hydrogen peroxide to solution C according to the mass fraction until no more bubbles are produced in solution C. Filter while hot to obtain a brownish-yellow insoluble substance. Wash with dilute hydrochloric acid and distilled water by centrifugation 8 times until complete precipitation. Collect the precipitate and dialyze it with distilled water at 25°C for 8 days to obtain the product. S24. The product is placed in a freeze dryer and freeze-dried at -60°C for 24 hours to obtain graphene oxide.

[0030] Example 1 A method for preparing a high thermal conductivity film for chip heat dissipation includes the following steps: S1. According to the mass fraction, 10 parts of graphene oxide were placed into a solution composed of 50 parts of ethanol and 150 parts of deionized water, and ultrasonically dispersed for 60 minutes to obtain a graphene oxide dispersion; the graphene oxide was prepared in Preparation Example 1. S2. According to the mass fraction, 300 parts of graphene oxide dispersion are mixed with 0.1 parts of coupling agent, and ultrasonic reaction is carried out for 3 hours to obtain graphene oxide slurry; the coupling agent is composed of bis(dioctylpyrophosphoryloxy)ethylene titanate and vinyltriethoxysilane in a mass fraction ratio of 1:1. S3. Preparation of pretreated ultrathin porous copper foil: Immerse an ultrathin porous copper foil with a thickness of 6μm and a porosity of 1000 mesh into a sulfuric acid solution with a mass concentration of 2% at a immersion temperature of 20℃ for 0.5 minutes. After removal, rinse with deionized water 3 times and then air dry the surface moisture to obtain the pretreated ultrathin porous copper foil. S4. Using pretreated ultrathin porous copper foil as the coating substrate, first coat one side of the pretreated ultrathin porous copper foil with graphene oxide slurry and place it in an oven to dry into a film. Then, perform the same coating and drying process on the other side to obtain a graphene oxide copper composite film. The thickness of the coating on one side is 0.3 mm. The drying temperature is 60°C and the time is 40 minutes. S5. Under a nitrogen atmosphere, the graphene oxide copper composite film is preheated at a temperature of 200°C for 16 hours to obtain a preheated graphene oxide copper composite film. S6. Under a nitrogen atmosphere, the preheated graphene oxide copper composite film is carbonized. The carbonization process conditions are: heating to 800°C at a heating rate of 4°C / min, and then holding at the temperature for 4 hours to obtain the carbonized graphene oxide copper composite film. S7. Under a nitrogen atmosphere, the carbonized graphene oxide copper composite film is graphitized. The graphitization process conditions are as follows: first, the temperature is increased to 1200℃ at a heating rate of 20℃ / min and held for 40 minutes, and then the temperature is increased to 2700℃ at a heating rate of 7℃ / min and held for 4 hours to obtain the graphitized graphene oxide copper composite film. S8. The graphitized graphene oxide copper composite film is vacuum pressed at 1210℃ using a vacuum flat press. The vacuum degree is 0.5Pa, the pressure is 20MPa, and the pressing time is 30 minutes to obtain a high thermal conductivity film for chip heat dissipation.

[0031] Example 2 A method for preparing a high thermal conductivity film for chip heat dissipation includes the following steps: S1. According to the mass fraction, 20 parts of graphene oxide were placed into a solution consisting of 50 parts of ethanol and 150 parts of deionized water, and ultrasonically dispersed for 80 minutes to obtain a graphene oxide dispersion; the graphene oxide was prepared in Preparation Example 1. S2. According to the mass fraction, 300 parts of graphene oxide dispersion are mixed with 0.2 parts of coupling agent, and ultrasonic reaction is carried out for 4 hours to obtain graphene oxide slurry; the coupling agent is composed of bis(dioctylpyrophosphoryloxy)ethylene titanate and vinyltriethoxysilane in a mass fraction ratio of 1:1. S3. Preparation of pretreated ultrathin porous copper foil: An ultrathin porous copper foil with a thickness of 8μm and a porosity of 1500 mesh is immersed in a sulfuric acid solution with a mass concentration of 2% at a immersion temperature of 25℃ for 1 minute. After being taken out, it is rinsed three times with deionized water and then dried to obtain the pretreated ultrathin porous copper foil. S4. Using pretreated ultrathin porous copper foil as the coating substrate, first coat one side of the pretreated ultrathin porous copper foil with graphene oxide slurry and place it in an oven to dry into a film. Then, perform the same coating and drying process on the other side to obtain a graphene oxide copper composite film. The thickness of the coating on one side is 0.5 mm. The drying temperature is 70°C and the time is 30 minutes. S5. Under a nitrogen atmosphere, the graphene oxide copper composite film is preheated at a temperature of 250°C for 12 hours to obtain the preheated graphene oxide copper composite film. S6. Under a nitrogen atmosphere, the preheated graphene oxide copper composite film is carbonized. The carbonization process conditions are: heating to 1000°C at a heating rate of 5°C / min, and then holding at the temperature for 3 hours to obtain the carbonized graphene oxide copper composite film. S7. Under a nitrogen atmosphere, the carbonized graphene oxide copper composite film is graphitized. The graphitization process conditions are as follows: first, the temperature is increased to 1000℃ at a heating rate of 25℃ / min and held for 30 minutes, and then the temperature is increased to 2900℃ at a heating rate of 7℃ / min and held for 3 hours to obtain the graphitized graphene oxide copper composite film. S8. The graphitized graphene oxide copper composite film is vacuum pressed at 1250℃ using a vacuum flat press. The vacuum degree is 1Pa, the pressure is 50MPa, and the pressing time is 20 minutes to obtain a high thermal conductivity film for chip heat dissipation.

[0032] Example 3 A method for preparing a high thermal conductivity film for chip heat dissipation includes the following steps: S1. According to the mass fraction, 15 parts of graphene oxide were placed into a solution consisting of 50 parts of ethanol and 150 parts of deionized water, and ultrasonically dispersed for 70 minutes to obtain a graphene oxide dispersion; the graphene oxide was prepared in Preparation Example 1. S2. According to the mass fraction, 300 parts of graphene oxide dispersion are mixed with 0.15 parts of coupling agent, and the mixture is ultrasonically reacted for 3.5 hours to obtain graphene oxide slurry; the coupling agent is composed of bis(dioctylpyrophosphoryloxy)ethylene titanate and vinyltriethoxysilane in a mass fraction ratio of 1:1. S3. Preparation of pretreated ultrathin porous copper foil: An ultrathin porous copper foil with a thickness of 7μm and a porosity of 1200 mesh is immersed in a sulfuric acid solution with a mass concentration of 2% at a immersion temperature of 24℃ for 0.7 minutes. After being taken out, it is rinsed three times with deionized water and then dried to obtain the pretreated ultrathin porous copper foil. S4. Using pretreated ultrathin porous copper foil as the coating substrate, first coat one side of the pretreated ultrathin porous copper foil with graphene oxide slurry and place it in an oven to dry into a film. Then, perform the same coating and drying process on the other side to obtain a graphene oxide copper composite film. The thickness of the coating on one side is 0.4 mm. The drying temperature is 65°C and the time is 35 minutes. S5. Under a nitrogen atmosphere, the graphene oxide copper composite film is preheated at a temperature of 230°C for 14 hours to obtain the preheated graphene oxide copper composite film. S6. Under a nitrogen atmosphere, the preheated graphene oxide copper composite film is subjected to carbonization treatment. The carbonization treatment process conditions are: heating to 900°C at a heating rate of 4.5°C / min, and then holding at the temperature for 3.5 hours to obtain the carbonized graphene oxide copper composite film. S7. Under a nitrogen atmosphere, the carbonized graphene oxide copper composite film is graphitized. The graphitization process conditions are as follows: first, the temperature is increased to 1100℃ at a heating rate of 23℃ / min and held for 36 minutes, and then the temperature is increased to 2800℃ at a heating rate of 6℃ / min and held for 3.4 hours to obtain the graphitized graphene oxide copper composite film. S8. The graphitized graphene oxide copper composite film is vacuum pressed at 1230℃ using a vacuum flat press. The vacuum degree is 0.7Pa, the pressure is 35MPa, and the pressing time is 25 minutes to obtain a high thermal conductivity film for chip heat dissipation.

[0033] Comparative Example 1 Similar to Example 3, except that graphene oxide from Jiangsu Carbon Yuan Technology Co., Ltd. was used in place of the graphene oxide prepared in Preparation Example 1 in equal parts by mass.

[0034] Comparative Example 2 Similar to Example 3, except that in step S2, the coupling agent is bis(dioctylpyrophosphate)ethylene titanate.

[0035] Comparative Example 3 Similar to Example 3, except that in step S2, the coupling agent is vinyltriethoxysilane.

[0036] Comparative Example 4 Similar to Example 3, except that step S2 is omitted, and in step S4, the graphene oxide dispersion obtained in step S1 is directly coated on the surface of the pretreated ultrathin porous copper foil.

[0037] Performance testing Samples of the high thermal conductivity films for chip heat dissipation prepared in Examples 1-3 and Comparative Examples 1-4 were taken and tested as follows. Each group of test samples was tested 3 times, and the average value of the results was taken. The results are shown in Table 1.

[0038] 1. In-plane thermal conductivity measurement test of the thermal conductive film: The in-plane thermal conductivity measurement test steps for the high thermal conductivity films for chip heat dissipation prepared in Examples 1-3 and Comparative Examples 1-4 are as follows: Four sample strips of the same specifications are cut from the high thermal conductivity films for chip heat dissipation prepared in Examples 1-3 and Comparative Examples 1-4 at an angle of 90° between the test direction and the film fiber direction. The sample strips are rotated 90° along the cut surface so that the cut surface of the sample strip is flush with the fiber direction of the high thermal conductivity films for chip heat dissipation prepared in Examples 1-3 and Comparative Examples 1-4. The four sample strips are spliced ​​together to obtain a spliced ​​plate. The thermal diffusivity, density and specific heat capacity of the spliced ​​plates of Examples 1 and 3 and Comparative Examples 1-4 are measured respectively. The in-plane thermal conductivity is calculated according to the formula: In-plane thermal conductivity (W / mK) = thermal diffusivity × density × specific heat capacity.

[0039] 2. Thermal conductivity measurement test of the outer surface of the thermal conductive film The test steps for measuring the out-of-plane (thickness direction) thermal conductivity of the high thermal conductivity films for chip heat dissipation prepared in Examples 1-3 and Comparative Examples 1-4 are as follows: (1) Select the high thermal conductivity films for chip heat dissipation prepared in Examples 1-3 and Comparative Examples 1-4 and measure their thickness; (2) Place the high thermal conductivity film samples for chip heat dissipation prepared in Examples 1-3 and Comparative Examples 1-4 on a thermal flow sensor, and let the heat flow pass through the sample. Then use a heat flow meter to measure the heat flow through the sample; (3) Install temperature sensors on the upper and lower surfaces of the high thermal conductivity film samples for chip heat dissipation prepared in Examples 1-3 and Comparative Examples 1-4 respectively, record the temperature difference between the two temperature sensors, ensure that the sensors are in contact with the sample surface and remain stable, and calculate the out-of-plane thermal conductivity according to the formula: out-of-plane thermal conductivity (W / mK) = heat flow / sample thickness × temperature difference.

[0040] Table 1 Test Results Analyzing the data in Table 1, we can see that: 1) The high thermal conductivity films for chip heat dissipation prepared in Examples 1-3 have an in-plane thermal conductivity ≥2012W / mK and an out-of-plane thermal conductivity ≥95W / mK, exhibiting excellent heat dissipation performance.

[0041] 2) The performance comparison analysis of the high thermal conductivity films for chip heat dissipation prepared in Example 3 and Comparative Example 1 shows that the graphene oxide prepared in this application has higher purity and better structural integrity, and the final high thermal conductivity film for chip heat dissipation has better heat dissipation performance.

[0042] 3) A comparative analysis of the performance of the high thermal conductivity films for chip heat dissipation prepared in Example 3 and Comparative Examples 2-4 shows that introducing a specific coupling agent during the preparation of the graphene oxide slurry allows it to react with the oxygen-containing functional groups (hydroxyl, carboxyl, and epoxy groups) on the graphene oxide. This coupling agent connects the various layers of graphene oxide and significantly improves the interfacial bonding strength with the surface of the ultrathin porous copper foil. During the drying and film formation process, the heating temperature during drying promotes self-crosslinking, making the graphene oxide more tightly connected. It also plays a fixing role during heat treatment, reducing the expansion caused by the release of gas. As a result, the prepared high thermal conductivity film for chip heat dissipation has an in-plane thermal conductivity of over 2012 W / mK and an out-of-plane thermal conductivity of over 95 W / mK, exhibiting excellent heat dissipation performance.

[0043] The above embodiments are only used to explain the technical solutions of this application and are not intended to limit it. Although the above embodiments have provided specific descriptions of this application, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation methods of this application. Any modifications and equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of this application.

Claims

1. A method for preparing a high thermal conductivity film for chip heat dissipation, characterized in that, Includes the following steps: S1. According to the mass fraction, 10-20 parts of graphene oxide are placed into a solution consisting of 50 parts of ethanol and 150 parts of deionized water, and ultrasonically dispersed for 60-80 minutes to obtain a graphene oxide dispersion. S2. According to the mass fraction, mix 300 parts of graphene oxide dispersion with 0.1-0.2 parts of coupling agent, and sonicate for 3-4 hours to obtain graphene oxide slurry; S3. Using pretreated ultrathin porous copper foil as the coating substrate, first coat one side of the pretreated ultrathin porous copper foil with graphene oxide slurry and place it in an oven to dry into a film. Then, perform the same coating and drying process on the other side to obtain a graphene oxide copper composite film. S4. Under a nitrogen atmosphere, the graphene oxide copper composite film is preheated to obtain a preheated graphene oxide copper composite film; the preheating temperature is 200-250℃ and the time is 12-16 hours. S5. Under a nitrogen atmosphere, the preheated graphene oxide copper composite film is carbonized to obtain a carbonized graphene oxide copper composite film. S6. Under a nitrogen atmosphere, the carbonized graphene oxide copper composite film is graphitized to obtain a graphitized graphene oxide copper composite film. S7. The graphitized graphene oxide copper composite film is subjected to vacuum hot pressing to obtain a high thermal conductivity film for chip heat dissipation.

2. The method for preparing a high thermal conductivity film for chip heat dissipation according to claim 1, characterized in that, In step S1, the method for preparing the graphene oxide includes the following steps: S21. According to the mass fraction, add 3 parts graphite powder and 1 part potassium nitrate into the reaction vessel, place the reaction vessel in an ice-water bath, stir at a stirring speed of 700 rpm, and slowly add 120 parts of sulfuric acid with a mass concentration of 98%, continue stirring, and react for 2 hours to obtain solution A. S22, according to the mass fraction, add 12 parts of potassium permanganate to solution A, stir at 700 rpm, react for 1-1.5 hours to obtain solution B, then transfer solution B to a 30℃ water bath, stir at 700 rpm for 1 hour, add 250 parts of distilled water and continue stirring until the solution turns brown, then raise the water bath temperature to 93℃ and react for 1-2 hours to obtain solution C; S23, add 40 parts of 30% hydrogen peroxide to solution C according to the mass fraction until no more bubbles are produced in solution C. Filter while hot to obtain a brownish-yellow insoluble substance. Wash with dilute hydrochloric acid and distilled water 8 times by centrifugation until complete precipitation. Collect the precipitate and dialyze it with distilled water at 25°C for 8 days to obtain the product. S24. The product is placed in a freeze dryer and freeze-dried at -60°C for 24 hours to obtain graphene oxide.

3. The method for preparing a high thermal conductivity film for chip heat dissipation according to claim 1, characterized in that, In step S2, the coupling agent is composed of bis(dioctylpyrophosphoryloxy)ethylene titanate and vinyltriethoxysilane in a mass ratio of 1:

1.

4. The method for preparing a high thermal conductivity film for chip heat dissipation according to claim 1, characterized in that, In step S3, the preparation method of the pretreated ultrathin porous copper foil is as follows: immerse the ultrathin porous copper foil in a sulfuric acid solution with a mass concentration of 2% at a immersion temperature of 20-25℃ for a immersion time of 0.5-1 minute, rinse it three times with deionized water after removal, and then dry the surface moisture to obtain the pretreated ultrathin porous copper foil.

5. The method for preparing a high thermal conductivity film for chip heat dissipation according to claim 4, characterized in that, The ultrathin porous copper foil has a thickness of 6-8 μm and a porosity of 1000-1500 mesh.

6. The method for preparing a high thermal conductivity film for chip heat dissipation according to claim 1, characterized in that, In step S3, the coating thickness is 0.3-0.5 mm, the drying temperature is 60-70°C, and the drying time is 30-40 minutes.

7. The method for preparing a high thermal conductivity film for chip heat dissipation according to claim 1, characterized in that, In step S5, the carbonization process conditions are as follows: the temperature is increased to 800-1000℃ at a heating rate of 4-5℃ / min, and then held at that temperature for 3-4 hours.

8. The method for preparing a high thermal conductivity film for chip heat dissipation according to claim 1, characterized in that, In step S6, the graphitization process conditions are as follows: first, heat the temperature to 1000-1200℃ at a heating rate of 20-25℃ / min and hold for 30-40 minutes, then heat the temperature to 2700-2900℃ at a heating rate of 5-7℃ / min and hold for 3-4 hours.

9. The method for preparing a high thermal conductivity film for chip heat dissipation according to claim 1, characterized in that, In step S7, the process conditions for the vacuum hot pressing treatment are as follows: the graphitized graphene oxide copper composite film is vacuum pressed at 1210-1250℃ using a vacuum flat press, with a vacuum degree of 0.5-1 Pa, a pressure of 20-50 MPa, and a pressing time of 20-30 minutes.

10. A high thermal conductivity film for chip heat dissipation, characterized in that, The high thermal conductivity film for chip heat dissipation is prepared by the method for preparing a high thermal conductivity film for chip heat dissipation according to any one of claims 1-9.

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