Single-component high-thermal-conductivity silica gel thermal interface material and preparation method thereof

Abstract

The invention discloses a single-component silica gel thermal interface material with high thermal conductivity. The single-component silica gel thermal interface material is prepared from the following raw materials in parts by weight: 2-30 parts of graphene oxide, 1-10 parts of deionized water, 0.01-0.5 part of a reducing agent, 0.01-1 part of a foaming agent, 0.01-0.5 part of liquid metal, 1-10 parts of polydimethylsiloxane, 0.1-2 parts of a curing agent, 0.1-2 parts of a diluent and 0.001-0.5 part of tannic acid. According to the single-component high-thermal-conductivity silica gel thermal interface material and the preparation method provided by the invention, the thermal interface material (TIM) with excellent thermal conductivity is successfully prepared by mixing the polydimethylsiloxane (PDMS) solution with the pre-prepared GA / LM and carrying out dipping treatment and high-temperature curing; the material can be widely applied to efficient heat dissipation in the fields of electronic devices, power batteries and the like, and can remarkably improve the operation efficiency and prolong the service life of electronic equipment.

Description

Technical Field

[0001] This invention relates to the field of thermal interface materials technology, and in particular to a single-component high thermal conductivity silicone thermal interface material and its preparation method. Background Technology

[0002] With the rapid development of electronic devices towards high power density and miniaturization, the heat generated per unit volume has increased dramatically. Heat dissipation has become a key bottleneck restricting performance improvement, reliability assurance, and lifespan extension. Therefore, efficient and reliable thermal management technology has become an indispensable core component of the electronics and information industry. Thermal interface materials (TIMs), as the key medium filling the space between heat-generating components and heat sinks, play a crucial role in effectively filling the tiny gaps and unevenness formed by surface roughness at the solid contact interface, significantly reducing contact thermal resistance, and thus constructing a highly efficient heat conduction channel. Therefore, the thermal conductivity, interface wettability, and long-term stability of the TIM material itself directly determine the heat dissipation efficiency of the entire heat dissipation system and the operating performance of the electronic device.

[0003] Currently, widely used traditional thermal interface materials, such as thermal grease, various solid thermal pads, and phase change materials, are gradually revealing many insurmountable limitations when facing increasingly stringent heat dissipation requirements:

[0004] (1) In terms of processing and application technology, thermal grease is usually in the form of paste. Its coating thickness is difficult to control precisely. It is easy to cause local excessive thickness or thinness due to uneven application, which affects the consistency of thermal conductivity. In the process of molding or curing, thermal pads are affected by factors such as mold precision, material flowability difference and curing shrinkage rate. The thickness tolerance of the final product is often large and the surface flatness is difficult to guarantee. This not only increases the process difficulty in assembly, but may also introduce additional contact thermal resistance due to poor interface contact, and cannot give full play to its thermal conductivity potential.

[0005] (2) In terms of material formulation and performance balance, in order to improve the thermal conductivity of traditional thermal interface materials, the method of filling with high thermal conductivity inorganic fillers (such as boron nitride, alumina, silicon carbide, zinc oxide and other ceramic particles or fibers) is generally adopted. However, the addition of a large amount of high thermal conductivity fillers can easily lead to a decrease in the flexibility and elastic modulus of the composite material, making the material brittle and hard, and difficult to adapt to the dynamic deformation caused by the difference in thermal expansion coefficients at the interface, which in turn leads to interface cracking or peeling. More importantly, there is often a large difference in interfacial energy between inorganic fillers and organic matrix, which can easily lead to uneven dispersion and agglomeration of fillers, making it impossible to effectively build a thermally conductive network. As a result, the overall thermal conductivity of the composite material is only slightly improved, the interfacial contact thermal resistance increases, and the composite material is difficult to meet the performance requirements of high-end electronic devices for thermal interface materials.

[0006] (3) In terms of preparation process and large-scale production, the preparation process of some traditional composite materials with high thermal conductivity often involves complex multi-step processes. These complex preparation processes not only significantly increase the production cycle and process control difficulty, resulting in high preparation costs, but also make it difficult to guarantee the consistency and stability of material properties during scale-up production, resulting in low production efficiency and difficulty in meeting the needs of large-scale industrial production, thus limiting their widespread application in practical engineering.

[0007] In recent years, graphene (GA) and liquid metals (LM), with their ultra-high thermal conductivity, have become research hotspots in the field of thermal interface composite materials due to their unique thermal properties. Among them, graphene, as a two-dimensional crystalline material composed of a single layer of carbon atoms, has a theoretical thermal conductivity of up to 5300 W / (m·K). Liquid metals, such as gallium-based alloys, are liquid at room temperature and have excellent fluidity and interfacial wettability, with a thermal conductivity typically around 30 W / (m·K), far exceeding that of traditional organic thermally conductive matrix materials.

[0008] However, directly applying these high-performance materials to thermal interface materials still faces significant challenges:

[0009] (1) When graphene or liquid metal is introduced into the polymer matrix by a simple physical blending method, the strong van der Waals forces between graphene sheets make it easy for them to stack and agglomerate, making it difficult to form an effective three-dimensional thermally conductive network in the matrix.

[0010] (2) The chemical inertness of graphene makes it less compatible with the organic matrix, which can easily lead to an increase in interfacial thermal resistance.

[0011] (3) For liquid metals, their high surface tension and easy oxidation characteristics make them very easy to form an oxide film in the air, affecting their fluidity and wettability. More importantly, liquid metals may leak during long-term use, which not only contaminates electronic components, but also leads to irreversible degradation of the performance of thermal interface materials, seriously affecting the long-term stability and reliability of composite materials.

[0012] Therefore, effectively solving the problems of graphene dispersion and interfacial compatibility, as well as the oxidation and leakage control of liquid metals, has become the core research direction for developing next-generation high-performance thermal interface composite materials based on graphene and liquid metals. Summary of the Invention

[0013] In view of the above-mentioned defects in the prior art, the technical problem to be solved by the present invention is that when high-performance materials are directly applied to thermal interface materials, the graphene sheets tend to stack and agglomerate, making it difficult to form an effective three-dimensional thermally conductive network in the matrix, or increasing the interfacial thermal resistance, and causing irreversible degradation of the performance of the thermal interface material, affecting the long-term stability and reliability of the composite material. Therefore, the present invention provides a single-component high thermal conductivity silicone thermal interface material and its preparation method. By mixing polydimethylsiloxane (PDMS) solution with pre-prepared GA / LM, performing impregnation treatment and high-temperature curing, a thermal interface material (TIM) with excellent thermal conductivity is successfully prepared. It can be widely used in the fields of electronic devices, power batteries and other fields for efficient heat dissipation, and can significantly improve the operating efficiency and service life of electronic devices.

[0014] To achieve the above objectives, the present invention provides a single-component high thermal conductivity silicone thermal interface material, comprising the following raw materials in parts by weight: 2-30 parts graphene oxide, 1-10 parts deionized water, 0.01-0.5 parts reducing agent, 0.01-1 parts foaming agent, 0.01-0.5 parts liquid metal, 1-10 parts polydimethylsiloxane, 0.1-2 parts curing agent, 0.1-2 parts diluent, and 0.001-0.5 parts tannic acid.

[0015] Furthermore, the graphene oxide was prepared using the Hummer method.

[0016] Furthermore, the concentration of graphene oxide is one or more of the following: 2 mg / ml, 3 mg / ml, 5 mg / ml, 8 mg / ml, 10 mg / ml, 15 mg / ml, 18 mg / ml, 20 mg / ml, and 25 mg / ml.

[0017] Furthermore, the reducing agent includes one or more of the following: hydrazine hydrate, vitamin C, ascorbic acid, hydroiodic acid, sodium borohydride, lithium aluminum hydride, sodium sulfide, sodium bisulfite, isopropanol, diisobutylaluminum hydride, sodium thiosulfate solution, and triethyllithium borohydride.

[0018] Furthermore, the foaming agent includes one of sodium bicarbonate, ammonium carbonate, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, citric acid and carbonate, azodicarbonamide, chitosan, cellulose, p-toluenesulfonyl hydrazine, and azobisisobutyronitrile.

[0019] Furthermore, the liquid metal includes one or more of the following: 8-degree gallium indium tin alloy, 11-degree gallium indium tin alloy, 16-degree gallium indium alloy, 29.8-degree gallium indium alloy, 8-degree indium tin alloy, 11-degree indium tin alloy, 16-degree indium tin alloy, and 21-degree indium tin alloy.

[0020] In a preferred embodiment of the present invention, a method for preparing a single-component high thermal conductivity silicone thermal interface material is provided, comprising the following steps:

[0021] (1) Mix graphene oxide, deionized water, reducing agent, foaming agent, liquid metal and tannic acid evenly and place them in an oven at 50-160℃ for 0.5-3h. After cooling to room temperature, place them in a refrigerator and freeze for 6-24h.

[0022] (2) After the hydrogel in the refrigerator is placed at room temperature, it is placed in an oven at 60-150℃ for 3-10 hours, cooled to 20-50℃, and the obtained hydrogel is washed and placed in an oven at 40-150℃ until completely dry to obtain GA / LM aerogel.

[0023] (3) Stir PDMS, diluent and curing agent for 10-60 minutes until completely mixed according to the set fraction ratio to ensure that the curing agent and PDMS react completely before mixing.

[0024] (4) Using the GA / LM from step (2) as a thermally conductive reinforcing material, the PDMS prepared above is added dropwise to the GA / LM and mixed for impregnation treatment to prepare the GA / LM-PDMS composite material;

[0025] (5) Place the mold containing the composite material into a vacuum drying oven to ensure that PDMS can fully penetrate into the interior of the composite material;

[0026] (6) Remove the mold from the vacuum drying oven and cure it in the oven to finally obtain the GA / LM-PDMS composite.

[0027] Furthermore, the mixing and stirring in step (1) includes mechanical stirring and ultrasonic treatment until the liquid metal is uniformly dispersed in the graphene oxide solution and there is no accumulation of liquid metal at the bottom, while the ultrasonic treatment temperature does not exceed 30°C.

[0028] Furthermore, the impregnation treatment is maintained in a vacuum oven at a vacuum pressure of -0.7 MPa for 30-90 minutes to ensure that PDMS can completely penetrate into the GA / LM composite material.

[0029] Furthermore, the curing in the oven in step (6) is high-temperature curing, with a curing temperature of 40-100℃ and a curing time of 2-10h.

[0030] Technical effect

[0031] This invention provides a single-component high thermal conductivity silicone thermal interface material and its preparation method. By loading LM (silicone ether) onto the three-dimensional porous structure of GA (glucose-containing silica), a GA / LM hybrid filler is formed. This retains the high thermal conductivity network of GA while utilizing the fluidity of LM to fill interfacial voids, significantly reducing contact thermal resistance. The GA / LM hybrid filler is impregnated with PDMS solution, combined with a high-temperature curing process, ensuring uniform dispersion and tight bonding with the matrix, thus improving the material's mechanical strength and thermal stability. The composite material achieves a thermal conductivity of 11.1-1.317 W / (m·K). This material can significantly improve the heat dissipation efficiency of electronic devices, extend device lifespan, and enhance reliability.

[0032] The following will further explain the concept, specific structure, and technical effects of the present invention in order to fully understand the purpose, features, and effects of the present invention. Detailed Implementation

[0033] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] In the following description, specific details, such as particular internal procedures and techniques, are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will appreciate that the invention may be practiced in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of the invention with unnecessary detail.

[0035] This invention proposes a single-component high thermal conductivity silicone thermal interface material and its preparation method. The material comprises a three-dimensional framework constructed from graphene oxide (GA) and includes the following raw materials in parts by weight: 3.125 parts graphene oxide solution, 1.75 parts deionized water, 0.03 parts reducing agent, 0.25 parts foaming agent, 0.01-0.5 parts liquid metal, and 0.01-0.05 parts tannic acid. The graphene oxide solution serves as the basic framework material for the three-dimensional structure. The concentration of the graphene oxide solution diluted with deionized water ensures good dispersion of the graphene oxide. The foaming agent forms three-dimensional interconnected channels through gas foaming, increasing the specific surface area and creating a porous structure. Minor changes in the proportions of these components have little impact on the final technical effect. Tannic acid is added to modify the liquid metal, ensuring uniform dispersion of the liquid metal in the aerogel. Different liquid metal contents lead to different tannic acid contents, which in turn affect the final thermal conductivity value.

[0036] In this invention, compared with the freeze-drying method for preparing three-dimensional porous GA framework, a liquid metal modified graphene aerogel is prepared at room temperature and pressure. During the synthesis process, the liquid metal is loaded into the GA framework to make the graphene oxide and liquid metal uniformly distributed, thus preparing the composite material GA / LM.

[0037] In this invention, the liquid metal includes one of the following: 8-degree gallium indium tin alloy, 11-degree gallium indium tin alloy, 16-degree gallium indium alloy, 29.8-degree gallium indium alloy, 8-degree indium tin alloy, 11-degree indium tin alloy, 16-degree indium tin alloy, and 21-degree indium tin alloy. Gallium indium tin alloy is preferred. Excessive addition of gallium indium tin alloy will prevent the GA from completely coating the liquid metal, causing the liquid metal to aggregate and sink during the reduction process, thus failing to obtain a uniformly loaded GA composite material with LM.

[0038] In this invention, since LM is relatively heavy and not easy to disperse, it needs to be ultrasonically dispersed and mechanically stirred after all raw materials are added so that LM can be completely dispersed and evenly distributed in GA.

[0039] In this invention, when preparing the silicone, PDMS is mixed with curing agent and diluent in a certain proportion. During the preparation process, attention should be paid to the stirring time to ensure uniform mixing and reduce the generation of bubbles. The prepared PDMS should be mixed with GA / LM as soon as possible to avoid curing due to prolonged storage.

[0040] The technical solutions of this invention will be clearly and completely described below with reference to specific embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0041] Example 1

[0042] This embodiment provides a method for preparing a single-component high thermal conductivity silicone thermal interface material, the specific steps of which are as follows:

[0043] (1) Place the 8 mg / ml graphene oxide dispersion in a glass bottle, add deionized water to make the concentration 5 mg / ml, add 0.25 g foaming agent, 0.03 g reducing agent, 0.15 g liquid metal and 0.015 g tannic acid, stir and sonicate until completely mixed and there is no more LM deposit at the bottom of the bottle, seal with plastic wrap and put in a 90℃ oven for 2 hours, then place at room temperature and freeze in a refrigerator overnight;

[0044] (2) After freezing the sample, place it in a 90°C oven for 8 hours. Take out the sample and place it in a 90°C oven for 8 hours. Then, wash the sample with anhydrous ethanol until there is no yellow residue in the cleaning agent. Place the washed sample in a 150°C oven for 2 hours to dry.

[0045] (3) Mix PDMS, curing agent and diluent in a ratio of 9:0.5:0.5, stir for 30 minutes to ensure uniform mixing;

[0046] (4) After compressing GA / LM to 0.1 mm, drop the prepared PDMS into it;

[0047] (5) Place the composite material in a vacuum drying oven and keep it under a vacuum pressure of -0.7MPa for 30 minutes to allow PDMS to fully penetrate into the interior of GA / LM;

[0048] (6) The composite material was placed in an 80℃ oven for 6 hours to cure, thus preparing the composite material GA / LM-PDMS.

[0049] During ultrasonic stirring in step (1), attention should be paid to the temperature. The solution temperature should not be too high. Stir until it is full of air bubbles, then seal it with plastic wrap and put it into the oven.

[0050] The thermal conductivity of the prepared single-component high thermal conductivity silicone composite material is 11.317 W / (m·K).

[0051] Example 2

[0052] Referring to Example 1, the difference is that the liquid metal-modified graphene aerogel obtained in step (2) of Example 1 was ground into powder and added to the PDMS solution prepared in step (3) at the same mass ratio, and stirred until uniform. The sample was placed in an 80°C oven for curing for 8 hours and then the composite material XGA / LM-PDMS was taken out. The thermal conductivity of the composite material was measured to be 2.49 W / (m·K).

[0053] Example 3

[0054] Referring to Example 1, the PDMS prepared in step (3) was directly placed in an 80°C oven for high-temperature curing. The thermal conductivity of pure PDMS was measured to be 0.19 W / (m·K).

[0055] Example 4

[0056] Referring to Example 1, the difference is that the ratio in step (3) is changed to 8:0.5:1.5. The prepared composite material is not easy to cure, and the curing time and curing temperature need to be extended. In addition, the prepared PDMS solution is prone to generating bubbles and cannot be completely immersed in GA / LM, resulting in poor mechanical properties of the material.

[0057] Example 5

[0058] Referring to Example 1, the difference is that the drying temperature in step (2) is changed to 60℃ for 12 hours. Due to the excessively long drying time, the capillary force in the aerogel exerts enormous pressure on the aerogel skeleton, causing the skeleton to easily deform, aggregate, and collapse, making it difficult to form an aerogel.

[0059] Example 6

[0060] Referring to Example 1, the difference is that the concentration of graphene oxide in step (1) is replaced with 10 mg / ml. The high solubility of graphene oxide leads to excessive viscosity and uneven distribution, resulting in local density differences. During drying, the shrinkage rate of different areas is different, causing internal stress concentration, which makes it easy to crack during the synthesis of GA / LM.

[0061] Comparative Example 1

[0062] Referring to Example 1, the difference is that the weight of the added liquid metal is changed to 0.1g, and the thermal conductivity of the prepared composite material is 8.2544W / (m·K).

[0063] Comparative Example 2

[0064] Referring to Example 1, the difference is that the weight of the added liquid metal is changed to 0.2g. The prepared GA / LM aerogel has LM precipitated at the bottom, and the aerogel cannot be fully loaded with LM.

[0065] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A single-component high thermal conductivity silicone thermal interface material, characterized in that, The raw materials include the following parts by weight: 2-30 parts graphene oxide, 1-10 parts deionized water, 0.01-0.5 parts reducing agent, 0.01-1 part foaming agent, 0.01-0.5 parts liquid metal, 1-10 parts polydimethylsiloxane, 0.1-2 parts curing agent, 0.1-2 parts diluent, and 0.001-0.5 parts tannic acid.

2. The single-component high thermal conductivity silicone thermal interface material as described in claim 1, characterized in that, The graphene oxide was prepared using the Hummer method.

3. The single-component high thermal conductivity silicone thermal interface material as described in claim 1, characterized in that, The concentration of the graphene oxide is one or more of the following: 2 mg / ml, 3 mg / ml, 5 mg / ml, 8 mg / ml, 10 mg / ml, 15 mg / ml, 18 mg / ml, 20 mg / ml, and 25 mg / ml.

4. The single-component high thermal conductivity silicone thermal interface material as described in claim 1, characterized in that, The reducing agent includes one or more of the following: hydrazine hydrate, vitamin C, ascorbic acid, hydroiodic acid, sodium borohydride, lithium aluminum hydride, sodium sulfide, sodium bisulfite, isopropanol, diisobutylaluminum hydride, sodium thiosulfate solution, and triethyllithium borohydride.

5. The single-component high thermal conductivity silicone thermal interface material as described in claim 1, characterized in that, The foaming agent includes one of sodium bicarbonate, ammonium carbonate, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, citric acid and carbonate, azodicarbonamide, chitosan, cellulose, p-toluenesulfonyl hydrazine, and azobisisobutyronitrile.

6. The single-component high thermal conductivity silicone thermal interface material as described in claim 1, characterized in that, The liquid metal includes one or more of the following: 8-degree gallium-indium-tin alloy, 11-degree gallium-indium-tin alloy, 16-degree gallium-indium alloy, 29.8-degree gallium-indium alloy, 8-degree indium-tin alloy, 11-degree indium-tin alloy, 16-degree indium-tin alloy, and 21-degree indium-tin alloy.

7. A method for preparing a single-component high thermal conductivity silicone thermal interface material as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) Mix graphene oxide, deionized water, reducing agent, foaming agent, liquid metal and tannic acid evenly and place them in an oven at 50-160℃ for 0.5-3h. After cooling to room temperature, place them in a refrigerator and freeze for 6-24h. (2) After the hydrogel in the refrigerator is placed at room temperature, it is placed in an oven at 60-150℃ for 3-10 hours, cooled to 20-50℃, and the obtained hydrogel is washed and placed in an oven at 40-150℃ until completely dry to obtain GA / LM aerogel. (3) Stir PDMS, diluent and curing agent for 10-60 minutes until completely mixed according to the set fraction ratio to ensure that the curing agent and PDMS react completely before mixing. (4) Using the GA / LM from step (2) as a thermally conductive reinforcing material, the PDMS prepared above is added dropwise to the GA / LM and mixed for impregnation treatment to prepare the GA / LM-PDMS composite material; (5) Place the mold containing the composite material into a vacuum drying oven to ensure that PDMS can fully penetrate into the interior of the composite material; (6) Remove the mold from the vacuum drying oven and cure it in the oven to finally obtain the GA / LM-PDMS composite.

8. The method for preparing a single-component high thermal conductivity silicone thermal interface material as described in claim 7, characterized in that, The mixing in step (1) includes mechanical stirring and ultrasonic treatment until the liquid metal is uniformly dispersed in the graphene oxide solution and there is no accumulation of liquid metal at the bottom. At the same time, the ultrasonic treatment temperature does not exceed 30°C.

9. The method for preparing a single-component high thermal conductivity silicone thermal interface material as described in claim 7, characterized in that, The impregnation process is carried out in a vacuum oven at a vacuum pressure of -0.7 MPa for 30-90 minutes to ensure that PDMS can completely penetrate into the GA / LM composite material.

10. The method for preparing a single-component high thermal conductivity silicone thermal interface material as described in claim 7, characterized in that, In step (6), the curing in the oven is high-temperature curing, with a curing temperature of 40-100℃ and a curing time of 2-10h.