Epoxy-based non-curing locking liquid high-thermal-conductivity insulating liquid metal thermal paste and preparation method thereof

Abstract

The application relates to the technical field of heat-conducting materials, in particular to an epoxy-based non-curing locking liquid high-heat-conducting insulating liquid metal heat-conducting paste and a preparation method. The high-heat-conducting insulating liquid metal heat-conducting paste is composed of the following components in percentage by weight: liquid-state bisphenol F epoxy: 5.0-12.0%; hydrophobic MQ silicon resin: 0.1-1.0%; hydrophobic nano-gaseous silicon dioxide: 0.3-1.2%; nanometer-level flaky hydrophobic modified boron nitride: 0.1-1.5%; liquid-state gallium-indium-tin metal: 30.0-40.0%; micron-level composite heat-conducting filler: 38.0-42.4%; and additives: 1.0-1.9%. Through the synergistic locking liquid structure of a thixotropic network-micro-crosslinking elastic network-flaky barrier network, the heat-conducting insulating filler compounding and the additive regulation, the heat-conducting paste realizes long-acting locking liquid in the whole temperature range and is suitable for the heat dissipation of high-power electronic devices. Therefore, the problems of the locking liquid effect reduction and the heat-conducting coefficient reduction in the prior art are solved.

Description

Technical Field

[0001] This application relates to the field of thermal conductive materials technology, and in particular to epoxy-based non-curing, liquid-locking, high thermal conductivity insulating liquid metal thermal conductive paste and its preparation method. Background Technology

[0002] Thermal paste, as a core material for heat dissipation in electronic devices, plays an irreplaceable role in alleviating thermal stress, ensuring stable operation, and improving power density and lifespan. Especially in high-heat-fluidity electronic devices such as high-power data center servers and AI chips, heat accumulation can easily lead to performance degradation and short-circuit failure, severely restricting the high-end development of the electronics industry. Traditional liquid metal thermal pastes generally suffer from poor liquid-locking effect, difficulty in balancing high thermal conductivity and high insulation, and irreparability after substrate curing. It is difficult to achieve a synergistic adaptation of full-temperature-range liquid-locking, efficient heat dissipation, and device maintenance. There is an urgent need to develop epoxy-based liquid metal thermal pastes that combine long-lasting full-temperature-range liquid-locking, high thermal conductivity, high insulation, non-curing properties, and good maintainability.

[0003] Existing liquid metal thermal pastes and related preparation technologies suffer from the following problems: Traditional thermal pastes often improve flowability by adding polymer thickeners and inorganic thixotropic agents, lacking precise design of the liquid-locking structure and multi-network synergistic construction. They can only achieve limited liquid-locking at room temperature or medium-low temperatures, with a significant decrease in liquid-locking effect at high temperatures or across the entire temperature range. This leads to easy flow and overflow of the liquid metal, and the poor compatibility between liquid metal and organic matrices, resulting in problems such as stratification and sedimentation, severely reducing the long-term reliability of the thermal paste. Furthermore, to impart insulating properties to the thermal paste, a large amount of insulating filler is usually added, but the lack of insulating filler and thermal conductivity... The scientific compounding and structural design of the medium, and the addition of a large amount of insulating filler, can disrupt the heat conduction path and significantly reduce the thermal conductivity of the thermal paste, making it difficult to meet the dual requirements of high thermal conductivity and high insulation. Most liquid metal thermal pastes use a curable organic matrix, which can solve the flow problem to some extent, but lacks the design and control of the non-curing properties of the matrix. After curing, the thermal paste loses its repairability. When electronic devices fail and need repair or replacement, it is difficult to remove the thermal paste from the device surface, which increases the difficulty and cost of repair and further limits the application effect of liquid metal thermal paste in the field of high heat flux density electronic devices. Summary of the Invention

[0004] This application provides an epoxy-based non-curing liquid metal thermal grease with high thermal conductivity and insulation, and its preparation method, to solve the problems of reduced liquid-locking effect, reduced thermal conductivity, and low maintainability of thermal grease in the prior art.

[0005] This application provides an epoxy-based non-curing, liquid-locking, high thermal conductivity, insulating liquid metal thermally conductive paste, such as... Figure 1 As shown, its composition, by weight percentage, is as follows: Bisphenol F liquid epoxy: 5.0~12.0%; Hydrophobic MQ silicone resin: 0.1~1.0%; Hydrophobic nano-fumed silica: 0.3~1.2%; Nanoscale sheet-like hydrophobically modified boron nitride: 0.1~1.5%; Gallium indium tin liquid metal: 30.0~40.0%; Micron-scale composite thermally conductive filler: 38.0~42.4%; Additives: 1.0~1.9%.

[0006] Optionally, the micron-sized composite thermally conductive filler is composed of micron-sized diamond powder, micron-sized aluminum nitride powder, and insulating modified metal powder in a mass ratio of 2:(1.0~2.0):(1.0~2.0), and the particle size of the micron-sized composite thermally conductive filler is 1~50μm.

[0007] Optionally, the insulating modified metal powder consists of metal powder and an insulating layer, wherein the metal powder includes aluminum powder or copper powder, and the insulating layer includes silicon dioxide or boron nitride.

[0008] Optionally, the additive is composed of a polymerization inhibitor, p-benzoquinone, an antioxidant, and a silane coupling agent, KH550; wherein the polymerization inhibitor p-benzoquinone has a weight percentage of 0.10~0.20% in the thermal paste, the antioxidant is an equal mass mixture of antioxidant 1076 and antioxidant 168, wherein the equal mass mixture of antioxidant 1076 and antioxidant 168 has a weight percentage of 0.50~1.00% in the thermal paste, and the silane coupling agent, KH550, has a weight percentage of 0.40~0.70% in the thermal paste.

[0009] Optionally, the gallium indium tin liquid metal is composed of 68-70% gallium, 20-22% indium, and 8-10% tin by weight percentage, and the melting point of the gallium indium tin liquid metal is 10-20°C.

[0010] Optionally, the nanoscale sheet-like hydrophobic modified boron nitride has a sheet diameter of 50~200nm, and the nanoscale sheet-like hydrophobic modified boron nitride is composed of boron nitride and a modifier, wherein the modifier is a silane coupling agent KH550 or KH570.

[0011] Optionally, the specific surface area of ​​the hydrophobic nano-fumed silica is 200~300m² / g, and the molar ratio of the hydrophobic MQ silicone resin to siloxanes is M:Q=1:(1.5~3.0).

[0012] This application also proposes a method for preparing an epoxy-based non-curing, liquid-locking, high thermal conductivity, insulating liquid metal thermally conductive paste, comprising the following steps: (1) Pretreatment of epoxy matrix: Mix the bisphenol F liquid epoxy and hydrophobic MQ silicone resin according to the formula, heat to 80~100℃, keep warm for 1~4h, then cool to 30~45℃, add the polymerization inhibitor p-benzoquinone and antioxidant according to the formula, stir at 500~1000r / min until the system is uniform, and obtain the pretreated epoxy matrix; (2) Dispersion of filler and functional components: GaInT liquid metal, micron-scale composite thermally conductive filler, nano-scale sheet-like hydrophobic modified boron nitride and silane coupling agent KH550 are added sequentially to the pretreated epoxy matrix and stirred at low speed. Then, hydrophobic nano-vaporized silica is added and dispersed at high speed to obtain a mixed slurry. (3) Vacuum degassing: The mixed slurry is placed in a vacuum degassing machine and degassed for 15 to 35 minutes under a vacuum of -0.08 to -0.1 MPa and a temperature of 20 to 30°C. After degassing is completed, the material is discharged to obtain the thermal paste.

[0013] Preferably, in step (2), the low-speed stirring speed is 600~1000r / min and the stirring time is 20~40min, and the high-speed dispersion speed is 2500~3500r / min and the dispersion time is 30~70min; air cooling is used during the high-speed dispersion process to control the system temperature to not exceed 50℃.

[0014] This application also proposes an epoxy-based non-curing liquid-locking high thermal conductivity insulating liquid metal thermal grease. Through the synergistic effect of a thixotropic network formed by hydrophobic nano-vaporized silica, a micro-crosslinked elastic network formed by hydrophobic MQ silicone resin, and a sheet-like barrier network formed by nano-scale sheet-like hydrophobic modified boron nitride, a triple-network liquid-locking structure is formed, which realizes the locking of gallium indium tin liquid metal in the full temperature range of -50℃ to 230℃. Moreover, no liquid metal overflow was found after a long-term reliability test at 150℃ / 1000h, which can be used for heat dissipation of high-power electronic devices.

[0015] Therefore, this application has at least the following beneficial effects: (1) In the embodiments of this application, hydrophobic nano-fumed silica, hydrophobic MQ silicone resin, and nano-scale sheet-like hydrophobically modified boron nitride synergistically construct a triple network liquid-locking structure in the system. The hydrophobic nano-fumed silica forms a three-dimensional continuous thixotropic network through intermolecular hydrogen bonding, giving the thermal paste excellent thixotropic properties. The hydrophobic MQ silicone resin forms a micro-crosslinked elastic network through intermolecular Si-OH self-condensation at 80~100℃, which is nested with the thixotropic network to improve high-temperature stability. The nano-scale sheet-like hydrophobic modified boron nitride... Boron nitride is uniformly dispersed in the network to form a sheet-like barrier network, which assists in liquid locking through physical barrier. The triple network interweaves to form a dense and elastic liquid locking system, achieving long-term locking of gallium indium tin liquid metal in the entire temperature range of -50℃ to 230℃. This allows the thermal paste to flow in a low-viscosity state when applied by external force and quickly return to a paste state after the external force is removed, setting without flowing. After a long-term reliability test at 150℃ / 1000h, there was no liquid metal overflow, which solves the core problem of traditional liquid metal thermal paste being prone to flowing and overflowing in the entire temperature range.

[0016] (2) In the embodiments of this application, the micron-sized composite thermally conductive filler and the nano-sized sheet-like hydrophobic modified boron nitride synergistically construct a highly efficient thermally conductive and highly insulating system. The micron-sized composite thermally conductive filler is composed of micron-sized diamond powder, micron-sized aluminum nitride powder, and insulating modified metal powder in a ratio of 2:(1.0~2.0):(1.0~2.0). The filler with a particle size of 1~50μm can fully fill the gaps between the liquid metal and the epoxy matrix, constructing a continuous thermally conductive path. The nano-sized sheet-like hydrophobic modified boron nitride not only assists in liquid locking but also further improves the thermally conductive network. At the same time, its insulating properties and the insulating layer of the insulating modified metal powder form a double insulation guarantee, so that the thermal conductivity of the thermal paste is ≥13.8W / m・K, the thermal resistance is ≤0.009K・cm² / W, and the volume resistivity is ≥1.2×10¹ according to the GB / T5470 standard. 4 Ω・cm solves the problem of decreased thermal conductivity caused by adding a large amount of insulating filler to traditional thermal paste.

[0017] (3) In the embodiments of this application, the additives are composed of an equal mass mixture of the polymerization inhibitor p-benzoquinone, antioxidants 1076 and 168, and silane coupling agent KH550 in proportion. The polymerization inhibitor p-benzoquinone accounts for 0.10~0.20% in the thermal paste, which effectively inhibits the free radical polymerization reaction that may occur in the system, ensures the non-curing property of the bisphenol F liquid epoxy body, and allows the thermal paste to remain non-curing for a long time. When repairing electronic devices, it can be easily removed from the surface of the device, which has excellent maintainability and reduces the difficulty and cost of repair. The antioxidant accounts for 0.50~1.00%, which significantly improves the antioxidant performance of the thermal paste and extends its service life. The silane coupling agent KH550 accounts for 0.40~0.70%, which effectively improves the interfacial compatibility between inorganic fillers, liquid metal and epoxy body, ensures that each component is uniformly dispersed in the system, and improves the morphology and performance stability of the thermal paste.

[0018] (4) In the embodiments of this application, the gallium indium tin liquid metal is composed of 68-70% gallium, 20-22% indium and 8-10% tin by weight. The melting point is controlled at 10-20℃ and it is used as the core thermal conductive medium in a proportion of 30.0-40.0% to provide a high thermal conductivity basis for the thermal paste. The micron-sized composite thermal conductive filler is composed of micron-sized diamond powder, micron-sized aluminum nitride powder and insulating modified metal powder with a particle size of 1-50μm and a mass ratio of 2:(1.0-2.0):(1.0-2.0). It is filled in the gaps of the triple network in a proportion of 38.0-42.4%. The insulating modified metal powder has aluminum powder or copper powder as the core and silicon dioxide or boron nitride as the insulating layer. It retains the high thermal conductivity of the metal powder and has insulation properties. The composite thermal conductive filler and the gallium indium tin liquid metal work together to build a continuous and dense thermal conductive network, which greatly improves the thermal conductivity of the thermal paste.

[0019] This solves the problems of reduced liquid retention, decreased thermal conductivity, and low maintainability of thermal paste in existing technologies.

[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0021] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of a thermally conductive-insulating system provided according to an embodiment of this application. Detailed Implementation

[0022] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0023] In the embodiments of this application, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0024] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way.

[0025] In the embodiments of this application, the sources of the components include: bisphenol F liquid epoxy purchased from Henan Wokas Biotechnology Co., Ltd.; hydrophobic nano-fumed silica purchased from Hubei Huifu Nanomaterials Co., Ltd.; nano-scale sheet-like hydrophobic modified boron nitride purchased from Jiangxi Liankai Technology Co., Ltd.; gallium indium tin liquid metal purchased from Hunan Zhongcai Shengte New Material Technology Co., Ltd.; micron-sized diamond powder purchased from Yuansu (Zhecheng County) Materials Technology Co., Ltd.; micron-sized aluminum nitride powder purchased from Xuzhou Jiechuang New Material Technology Co., Ltd.; insulating modified metal powder purchased from Hunan Ningxiang Jiweixin Metal Powder Co., Ltd.; hydrophobic MQ silicone resin purchased from Chengdu Chenguang Boda New Material Co., Ltd.; silane coupling agent KH-570 or KH-550 purchased from Shandong Hengyu New Material Co., Ltd.; polymerization inhibitor p-benzoquinone purchased from Weifang Tongrun Chemical Co., Ltd.; antioxidant 1076 purchased from Beijing Jiyi Chemical Co., Ltd.; and antioxidant 168 purchased from Linyi Sanfeng Chemical Co., Ltd.

[0026] Example 1

[0027] This application provides an epoxy-based non-curing, high thermal conductivity, insulating liquid metal thermal grease, the composition of which, by weight percentage, is: Bisphenol F liquid epoxy: 5.0%; Hydrophobic MQ silicone resin: 0.1%; Hydrophobic nano-fumed silica: 0.3%; Nanoscale sheet-like hydrophobic modified boron nitride: 0.1%; Gallium indium tin liquid metal: 30.0%; Micron-scale composite thermally conductive filler: 38.0%; Additives: 1.0%.

[0028] The micron-sized composite thermal conductive filler is composed of micron-sized diamond powder, micron-sized aluminum nitride powder, and insulating modified metal powder in a mass ratio of 2:(1.0):(1.0), and the particle size of the micron-sized composite thermal conductive filler is 1μm.

[0029] The insulating modified metal powder consists of metal powder and an insulating layer. The metal powder includes aluminum powder or copper powder, and the insulating layer includes silicon dioxide or boron nitride.

[0030] The additives consist of the polymerization inhibitor p-benzoquinone, an antioxidant, and the silane coupling agent KH550. The polymerization inhibitor p-benzoquinone accounts for 0.10% of the thermal paste by weight. The antioxidant is a mixture of antioxidants 1076 and 168 by equal mass, which accounts for 0.50% of the thermal paste by weight. The silane coupling agent KH550 accounts for 0.40% of the thermal paste by weight.

[0031] The gallium indium tin liquid metal is composed of 68% gallium, 22% indium, and 10% tin by weight percentage, and its melting point is 10°C.

[0032] Among them, the nanoscale sheet-like hydrophobic modified boron nitride has a sheet diameter of 50 nm. The nanoscale sheet-like hydrophobic modified boron nitride is composed of boron nitride and a modifier, wherein the modifier is a silane coupling agent KH550 or KH570.

[0033] Among them, the specific surface area of ​​the hydrophobic nano-fumed silica is 200 m² / g, and the molar ratio of siloxanes in the hydrophobic MQ silicone resin is M:Q=1:(1.5).

[0034] This application also proposes a method for preparing an epoxy-based non-curing, liquid-locking, high thermal conductivity, insulating liquid metal thermally conductive paste, comprising the following steps: Epoxy pretreatment: Mix the formulated amount of bisphenol F liquid epoxy with hydrophobic MQ silicone resin, heat to 80℃, keep warm for 1 hour, then cool to 30℃, add the formulated amount of polymerization inhibitor p-benzoquinone and antioxidant, stir at 500 r / min until the system is uniform, and obtain the pretreated epoxy. It is understood that in this embodiment, heating and heat preservation are used to induce the hydrophobic MQ silicone resin to form a micro-crosslinked elastic network in the epoxy matrix, laying the foundation for the subsequent construction of the triple liquid-locking structure. After cooling, the polymerization inhibitor and antioxidant are added to avoid the decomposition and failure of the additives caused by the high temperature environment, ensuring the functional effectiveness of the additives. At the same time, stirring allows the additives to be fully mixed with the epoxy matrix, achieving the system uniformity of the pretreated epoxy matrix. This provides a stable and suitable matrix environment for the dispersion of various fillers and functional components, and also ensures the non-curing property and antioxidant performance of the epoxy matrix in advance.

[0035] Dispersion of filler and functional components: GaInTl liquid metal, micron-sized composite thermally conductive filler, nano-sized sheet-like hydrophobic modified boron nitride and silane coupling agent KH550 are added sequentially to the pretreated epoxy matrix and stirred at low speed. Then, hydrophobic nano-vaporized silica is added and dispersed at high speed to obtain a mixed slurry. Understandably, in this embodiment, the filler and functional components are dispersed in steps. First, liquid metal, various thermally conductive fillers, boron nitride, and silane coupling agent are sequentially incorporated into the pretreated epoxy matrix through low-speed stirring. This allows the silane coupling agent to fully function, improving the compatibility of inorganic fillers, liquid metal, and epoxy matrix, while avoiding oxidation of the liquid metal caused by high-speed stirring, thus ensuring its core high thermal conductivity performance. Subsequently, hydrophobic nano-vaporized silica is added for high-speed dispersion, allowing it to be uniformly dispersed in the system and form a thixotropic network, nested with the previously formed micro-crosslinked elastic network. At the same time, various thermally conductive fillers and boron nitride are uniformly distributed in the system, creating conditions for the formation of a sheet-like barrier network and constructing a continuous thermally conductive pathway, resulting in a mixed slurry with uniformly dispersed components.

[0036] (3) Vacuum degassing: Place the mixed slurry in a vacuum degassing machine and degas for 15 minutes under a vacuum of -0.08MPa and a temperature of 20℃. After degassing is completed, the material is discharged to obtain the thermal paste.

[0037] It is understood that the vacuum degassing treatment of the mixed slurry in this embodiment can effectively remove the air bubbles generated during the stirring and dispersion process, prevent the air bubbles from forming thermally conductive voids in the system, ensure the uniformity and stability of the thermal conductivity of the thermal paste, eliminate the appearance defects of the paste caused by air bubbles, make the physical morphology of the thermal paste more regular, and allow it to fit tightly with the heat dissipation interface of electronic devices when applied, improve the contact effect of the heat dissipation interface, ensure the heat dissipation performance in actual applications, and avoid problems such as damage to the liquid-locking structure and liquid metal flow caused by air bubble rupture during subsequent use, further improving the overall reliability of the thermal paste.

[0038] In step (2), the low-speed stirring speed is 600 r / min and the stirring time is 20 min, while the high-speed dispersion speed is 2500 r / min and the dispersion time is 30 min. During the high-speed dispersion process, air cooling is used to control the system temperature to not exceed 50℃.

[0039] This application also proposes an epoxy-based non-curing liquid-locking high thermal conductivity insulating liquid metal thermal grease. Through the synergistic effect of a thixotropic network formed by hydrophobic nano-vaporized silica, a micro-crosslinked elastic network formed by hydrophobic MQ silicone resin, and a sheet-like barrier network formed by nano-scale sheet-like hydrophobic modified boron nitride, a triple-network liquid-locking structure is formed, which realizes the locking of gallium indium tin liquid metal in the full temperature range of -50℃ to 230℃. Moreover, no liquid metal overflow was found after a long-term reliability test at 150℃ / 1000h, which can be used for heat dissipation of high-power electronic devices.

[0040] For example, during the assembly or maintenance of high-power electronic devices such as high-power data center servers, AI chips, and automotive IGBT modules, this epoxy-based non-curing, liquid-locking, high-thermal-conductivity, insulating liquid metal thermal grease is uniformly applied at an appropriate dosage (e.g., 0.05-0.1g per square centimeter of heat dissipation interface) to the interface between the device chip and the heat dissipation module. The gallium indium tin (CITi) liquid metal within the grease serves as the core thermally conductive medium, rapidly conducting the high heat flux generated by the device's operation. Micron-level composite thermally conductive fillers and the liquid metal work together to construct a continuous and dense thermally conductive network, further improving heat transfer efficiency. According to GB / T5470 standards, it achieves a thermal conductivity ≥13.8W / m·K and a thermal resistance ≤0.009K·cm² / W, resulting in highly efficient heat dissipation. In this system, hydrophobic nano-fumed silica, hydrophobic MQ silicone resin, and nano-scale sheet-like hydrophobically modified boron nitride synergistically form a triple-network liquid-locking structure. On the one hand, the thixotropic network endows the thermal paste with excellent thixotropic properties, allowing it to quickly set and prevent indiscriminate flow after application. On the other hand, relying on the dual effects of the micro-crosslinked elastic network and the sheet-like barrier network, it achieves long-term, full-temperature-range locking of the gallium indium tin liquid metal. After 72 hours of storage at -50℃, there is no delamination or flow; after a short-term heating at 230℃ for 30 minutes, there is no liquid metal overflow; and after a long-term reliability test at 150℃ / 1000 hours, there is still no liquid metal overflow, effectively preventing liquid metal from flowing and contaminating the device. The nano-scale sheet-like hydrophobically modified boron nitride also endows the system with excellent insulation properties, making the volume resistivity of the thermal paste ≥10¹. 4 With a strength of Ω·cm, this product effectively addresses the short-circuit hazards in electronic devices caused by the conductivity of liquid metals. The polymerization inhibitor p-benzoquinone in the additives ensures the thermal paste does not harden over a long period. The silane coupling agent KH550 enhances the compatibility of each component with the epoxy matrix, preventing stratification and sedimentation of the paste. During device maintenance, the thermal paste can be easily removed from the heat dissipation interface without the need for additional treatment of cured residues. The synergistic effect of various functional components provides continuous and stable performance with high thermal conductivity, high insulation, and full-temperature liquid-locking properties. This effectively alleviates the heat buildup problem during the operation of high-power electronic devices, preventing performance degradation and ablation failure due to high temperatures. It significantly improves the operational stability and lifespan of the devices. Simultaneously, the non-curing characteristic greatly reduces the difficulty and cost of device repair, perfectly meeting the long-term service and maintenance needs of high-power electronic devices.

[0041] Example 2

[0042] This application provides an epoxy-based non-curing, high thermal conductivity, insulating liquid metal thermal grease, the composition of which, by weight percentage, is: Bisphenol F liquid epoxy: 8.0%; Hydrophobic MQ silicone resin: 0.5%; Hydrophobic nano-fumed silica: 0.8%; Nanoscale sheet-like hydrophobic modified boron nitride: 1.0%; Gallium indium tin liquid metal: 35.0%; Micron-scale composite thermally conductive filler: 40.0%; Additives: 1.6%.

[0043] The micron-sized composite thermal conductive filler is composed of micron-sized diamond powder, micron-sized aluminum nitride powder, and insulating modified metal powder in a mass ratio of 2:(1.5):(1.5), and the particle size of the micron-sized composite thermal conductive filler is 25μm.

[0044] The insulating modified metal powder consists of metal powder and an insulating layer. The metal powder includes aluminum powder or copper powder, and the insulating layer includes silicon dioxide or boron nitride.

[0045] The additives consist of the polymerization inhibitor p-benzoquinone, an antioxidant, and the silane coupling agent KH550. The polymerization inhibitor p-benzoquinone accounts for 0.15% of the thermal paste by weight. The antioxidant is a mixture of antioxidants 1076 and 168 by equal mass, which accounts for 0.80% of the thermal paste by weight. The silane coupling agent KH550 accounts for 0.60% of the thermal paste by weight.

[0046] The gallium indium tin liquid metal is composed of 70% gallium, 21% indium, and 9% tin by weight percentage, and has a melting point of 15°C.

[0047] Among them, the nanoscale sheet-like hydrophobic modified boron nitride has a sheet diameter of 150 nm. The nanoscale sheet-like hydrophobic modified boron nitride is composed of boron nitride and a modifier, wherein the modifier is a silane coupling agent KH550 or KH570.

[0048] Among them, the specific surface area of ​​the hydrophobic nano-fumed silica is 250 m² / g, and the molar ratio of siloxanes in the hydrophobic MQ silicone resin is M:Q=1:(2.0).

[0049] This application also proposes a method for preparing an epoxy-based non-curing, liquid-locking, high thermal conductivity, insulating liquid metal thermally conductive paste, comprising the following steps: Epoxy pretreatment: The formulated amount of bisphenol F liquid epoxy is mixed with hydrophobic MQ silicone resin, heated to 90℃, kept at the temperature for 2.5h, then cooled to 40℃, and the formulated amount of polymerization inhibitor p-benzoquinone and antioxidant are added. The mixture is stirred at 700r / min until the system is homogeneous to obtain the pretreated epoxy. It is understood that in this embodiment, heating and heat preservation are used to induce the hydrophobic MQ silicone resin to form a micro-crosslinked elastic network in the epoxy matrix, laying the foundation for the subsequent construction of the triple liquid-locking structure. After cooling, the polymerization inhibitor and antioxidant are added to avoid the decomposition and failure of the additives caused by the high temperature environment, ensuring the functional effectiveness of the additives. At the same time, stirring allows the additives to be fully mixed with the epoxy matrix, achieving the system uniformity of the pretreated epoxy matrix. This provides a stable and suitable matrix environment for the dispersion of various fillers and functional components, and also ensures the non-curing property and antioxidant performance of the epoxy matrix in advance.

[0050] Dispersion of filler and functional components: GaInTl liquid metal, micron-sized composite thermally conductive filler, nano-sized sheet-like hydrophobic modified boron nitride and silane coupling agent KH550 are added sequentially to the pretreated epoxy matrix and stirred at low speed. Then, hydrophobic nano-vaporized silica is added and dispersed at high speed to obtain a mixed slurry. Understandably, in this embodiment, the filler and functional components are dispersed in steps. First, liquid metal, various thermally conductive fillers, boron nitride, and silane coupling agent are sequentially incorporated into the pretreated epoxy matrix through low-speed stirring. This allows the silane coupling agent to fully function, improving the compatibility of inorganic fillers, liquid metal, and epoxy matrix, while avoiding oxidation of the liquid metal caused by high-speed stirring, thus ensuring its core high thermal conductivity performance. Subsequently, hydrophobic nano-vaporized silica is added for high-speed dispersion, allowing it to be uniformly dispersed in the system and form a thixotropic network, nested with the previously formed micro-crosslinked elastic network. At the same time, various thermally conductive fillers and boron nitride are uniformly distributed in the system, creating conditions for the formation of a sheet-like barrier network and constructing a continuous thermally conductive pathway, resulting in a mixed slurry with uniformly dispersed components.

[0051] (3) Vacuum degassing: Place the mixed slurry in a vacuum degassing machine and degas for 25 minutes at a vacuum degree of -0.09MPa and a temperature of 25℃. After degassing is completed, the material is discharged to obtain the thermal paste.

[0052] It is understood that the vacuum degassing treatment of the mixed slurry in this embodiment can effectively remove the air bubbles generated during the stirring and dispersion process, prevent the air bubbles from forming thermally conductive voids in the system, ensure the uniformity and stability of the thermal conductivity of the thermal paste, eliminate the appearance defects of the paste caused by air bubbles, make the physical morphology of the thermal paste more regular, and allow it to fit tightly with the heat dissipation interface of electronic devices when applied, improve the contact effect of the heat dissipation interface, ensure the heat dissipation performance in actual applications, and avoid problems such as damage to the liquid-locking structure and liquid metal flow caused by air bubble rupture during subsequent use, further improving the overall reliability of the thermal paste.

[0053] In step (2), the low-speed stirring speed is 800 r / min and the stirring time is 30 min, while the high-speed dispersion speed is 3000 r / min and the dispersion time is 50 min. During the high-speed dispersion process, air cooling is used to control the system temperature to not exceed 50℃.

[0054] This application also proposes an epoxy-based non-curing liquid-locking high thermal conductivity insulating liquid metal thermal grease. Through the synergistic effect of a thixotropic network formed by hydrophobic nano-vaporized silica, a micro-crosslinked elastic network formed by hydrophobic MQ silicone resin, and a sheet-like barrier network formed by nano-scale sheet-like hydrophobic modified boron nitride, a triple-network liquid-locking structure is formed, which realizes the locking of gallium indium tin liquid metal in the full temperature range of -50℃ to 230℃. Moreover, no liquid metal overflow was found after a long-term reliability test at 150℃ / 1000h, which can be used for heat dissipation of high-power electronic devices.

[0055] The preparation method of this embodiment is the same as that of Embodiment 1.

[0056] Example 3

[0057] This application provides an epoxy-based non-curing, high thermal conductivity, insulating liquid metal thermal grease, the composition of which, by weight percentage, is: Bisphenol F liquid epoxy: 12.0%; Hydrophobic MQ silicone resin: 1.0%; Hydrophobic nano-fumed silica: 1.2%; Nanoscale sheet-like hydrophobic modified boron nitride: 1.5%; Gallium indium tin liquid metal: 40.0%; Micron-scale composite thermally conductive filler: 42.4%; Additives: 1.9%.

[0058] The micron-sized composite thermal conductive filler is composed of micron-sized diamond powder, micron-sized aluminum nitride powder, and insulating modified metal powder in a mass ratio of 2:(2.0):(2.0), and the particle size of the micron-sized composite thermal conductive filler is 50μm.

[0059] The insulating modified metal powder consists of metal powder and an insulating layer. The metal powder includes aluminum powder or copper powder, and the insulating layer includes silicon dioxide or boron nitride.

[0060] The additives consist of the polymerization inhibitor p-benzoquinone, an antioxidant, and the silane coupling agent KH550. The polymerization inhibitor p-benzoquinone accounts for 0.20% of the thermal paste by weight. The antioxidant is a mixture of antioxidants 1076 and 168 by equal mass, which accounts for 1.00% of the thermal paste by weight. The silane coupling agent KH550 accounts for 0.70% of the thermal paste by weight.

[0061] The gallium indium tin liquid metal is composed of 70% gallium, 22% indium, and 8% tin by weight percentage, and its melting point is 20°C.

[0062] Among them, the nanoscale sheet-like hydrophobic modified boron nitride has a sheet diameter of 200 nm. The nanoscale sheet-like hydrophobic modified boron nitride is composed of boron nitride and a modifier, wherein the modifier is a silane coupling agent KH550 or KH570.

[0063] Among them, the specific surface area of ​​the hydrophobic nano-fumed silica is 300 m² / g, and the molar ratio of siloxanes in the hydrophobic MQ silicone resin is M:Q=1:(3.0).

[0064] This application also proposes a method for preparing an epoxy-based non-curing, liquid-locking, high thermal conductivity, insulating liquid metal thermally conductive paste, comprising the following steps: (1) Pretreatment of epoxy matrix: The amount of bisphenol F liquid epoxy and hydrophobic MQ silicone resin in the formulation are mixed, heated to 100°C, kept at the temperature for 4 hours, and then cooled to 45°C. The amount of polymerization inhibitor p-benzoquinone and antioxidant in the formulation are added, and the mixture is stirred at 1000 r / min until the system is uniform to obtain the pretreated epoxy matrix. It is understood that in this embodiment, heating and heat preservation are used to induce the hydrophobic MQ silicone resin to form a micro-crosslinked elastic network in the epoxy matrix, laying the foundation for the subsequent construction of the triple liquid-locking structure. After cooling, the polymerization inhibitor and antioxidant are added to avoid the decomposition and failure of the additives caused by the high temperature environment, ensuring the functional effectiveness of the additives. At the same time, stirring allows the additives to be fully mixed with the epoxy matrix, achieving the system uniformity of the pretreated epoxy matrix. This provides a stable and suitable matrix environment for the dispersion of various fillers and functional components, and also ensures the non-curing property and antioxidant performance of the epoxy matrix in advance.

[0065] (2) Dispersion of filler and functional components: GaInT liquid metal, micron-sized composite thermally conductive filler, nano-sized sheet-like hydrophobic modified boron nitride and silane coupling agent KH550 are added sequentially to the pretreated epoxy matrix and stirred at low speed. Then, hydrophobic nano-vaporized silica is added and dispersed at high speed to obtain a mixed slurry. Understandably, in this embodiment, the filler and functional components are dispersed in steps. First, liquid metal, various thermally conductive fillers, boron nitride, and silane coupling agent are sequentially incorporated into the pretreated epoxy matrix through low-speed stirring. This allows the silane coupling agent to fully function, improving the compatibility of inorganic fillers, liquid metal, and epoxy matrix, while avoiding oxidation of the liquid metal caused by high-speed stirring, thus ensuring its core high thermal conductivity performance. Subsequently, hydrophobic nano-vaporized silica is added for high-speed dispersion, allowing it to be uniformly dispersed in the system and form a thixotropic network, nested with the previously formed micro-crosslinked elastic network. At the same time, various thermally conductive fillers and boron nitride are uniformly distributed in the system, creating conditions for the formation of a sheet-like barrier network and constructing a continuous thermally conductive pathway, resulting in a mixed slurry with uniformly dispersed components.

[0066] (3) Vacuum degassing: Place the mixed slurry in a vacuum degassing machine and degas for 35 minutes at a vacuum degree of -0.1MPa and a temperature of 30℃. After degassing is completed, the material is discharged to obtain the thermal paste.

[0067] It is understood that the vacuum degassing treatment of the mixed slurry in this embodiment can effectively remove the air bubbles generated during the stirring and dispersion process, prevent the air bubbles from forming thermally conductive voids in the system, ensure the uniformity and stability of the thermal conductivity of the thermal paste, eliminate the appearance defects of the paste caused by air bubbles, make the physical morphology of the thermal paste more regular, and allow it to fit tightly with the heat dissipation interface of electronic devices when applied, improve the contact effect of the heat dissipation interface, ensure the heat dissipation performance in actual applications, and avoid problems such as damage to the liquid-locking structure and liquid metal flow caused by air bubble rupture during subsequent use, further improving the overall reliability of the thermal paste.

[0068] In step (2), the low-speed stirring speed is 1000 r / min and the stirring time is 40 min, while the high-speed dispersion speed is 3500 r / min and the dispersion time is 70 min. During the high-speed dispersion process, air cooling is used to control the system temperature to not exceed 50℃.

[0069] This application also proposes an epoxy-based non-curing liquid-locking high thermal conductivity insulating liquid metal thermal grease. Through the synergistic effect of a thixotropic network formed by hydrophobic nano-vaporized silica, a micro-crosslinked elastic network formed by hydrophobic MQ silicone resin, and a sheet-like barrier network formed by nano-scale sheet-like hydrophobic modified boron nitride, a triple-network liquid-locking structure is formed, which realizes the locking of gallium indium tin liquid metal in the full temperature range of -50℃ to 230℃. Moreover, no liquid metal overflow was found after a long-term reliability test at 150℃ / 1000h, which can be used for heat dissipation of high-power electronic devices.

[0070] Comparative Example 1 This comparative example provides an epoxy-based non-curing, liquid-locking, high thermal conductivity insulating liquid metal thermal grease and its preparation method. The only difference between this and Example 1 is that it does not contain hydrophobic MQ silicone resin and nano-scale sheet-like hydrophobic modified boron nitride. The reduced amount of hydrophobic MQ silicone resin and nano-scale sheet-like hydrophobic modified boron nitride is distributed to the bisphenol F liquid epoxy. The remaining components, component contents, and preparation process are the same as in Example 1.

[0071] Comparative Example 2 This comparative example provides an epoxy-based non-curing, liquid-locking, high thermal conductivity insulating liquid metal thermal grease and its preparation method. The only difference between this and Example 1 is that it does not contain nanoscale sheet-like hydrophobic modified boron nitride. The reduction in the amount of nanoscale sheet-like hydrophobic modified boron nitride is distributed to the micron-scale composite thermally conductive filler. The remaining components, component contents, and preparation process are the same as in Example 1.

[0072] Performance testing

[0073] The epoxy-based non-curing liquid thermally conductive insulating liquid metal thermal pastes prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to full-temperature-range liquid-locking performance analysis using a combination of high and low temperature aging and long-term reliability testing. The samples were uniformly coated on an aluminum alloy heat sink substrate (coating amount 0.1 g / cm²) and subjected to full-temperature-range testing, including -50℃ low-temperature sealed storage for 72 h, 230℃ high-temperature static heating for 30 min, and 150℃ constant-temperature aging for 1000 h. The presence of liquid metal overflow, stratification, or flow was observed. The liquid-locking performance was recorded as follows: no overflow / no stratification / no flow was excellent; slight overflow / minor stratification was medium; and obvious overflow / severe stratification / random flow was poor. The performance test data are shown in Table 1.

[0074] Table 1. Full Temperature Range Liquid Locking Performance Test

[0075] As shown in Table 1, the thermal greases prepared in Examples 1-3 of this invention exhibited excellent liquid-locking performance in the full temperature range test from -50℃ to 230℃. There was no liquid metal overflow, no layering, and no flow throughout the test, and the overall performance was excellent. This result fully confirms the effectiveness of the technical solution of this application: the thixotropic network formed by hydrophobic nano-vaporized silica endows the thermal grease with excellent thixotropic properties, and it quickly sets after the external force is removed; the micro-crosslinked elastic network formed by hydrophobic MQ silicone resin and the thixotropic network are nested with each other, which improves the stability of the liquid-locking structure at high temperature and avoids high-temperature collapse; the sheet-like barrier network formed by nano-scale sheet-like hydrophobic modified boron nitride assists in liquid-locking through physical barrier. The three networks interpenetrate with each other to form a dense and elastic liquid-locking system, which realizes long-term locking of gallium indium tin liquid metal in the full temperature range. Even after long-term high-temperature aging at 150℃ / 1000h, the liquid-locking structure remains intact and there is no liquid metal overflow.

[0076] In contrast, the liquid-locking performance of Comparative Examples 1 and 2 deteriorated significantly with the absence of network structures: Comparative Example 1 consisted of a single thixotropic network, lacking the synergistic effect of the micro-crosslinked elastic network and the sheet-like barrier network. At high temperatures, the thixotropic network was prone to structural relaxation, resulting in significant liquid metal leakage after short-term heating at 230°C and slight leakage even after long-term aging at 150°C, indicating poor liquid-locking performance. Comparative Example 2, with its dual liquid-locking network, lacked the physical barrier assistance of the sheet-like barrier network, still exhibiting trace amounts of liquid metal leakage at 230°C, resulting in only moderate liquid-locking performance. The micro-crosslinked elastic network is crucial for improving high-temperature liquid-locking stability, while the sheet-like barrier network is an important auxiliary for long-term liquid-locking across the entire temperature range. The absence of either or both significantly reduces the protective capability of the liquid-locking structure, further highlighting the necessity of the synergistic construction of the triple network in the embodiments for improving liquid-locking performance across the entire temperature range.

[0077] The core thermal conductivity and insulation properties of the epoxy-based non-curing liquid-locking high thermal conductivity insulating liquid metal thermal grease prepared in Examples 1-3 and Comparative Examples 1-2 were analyzed using national standard and conventional industry standard testing methods. The thermal conductivity and thermal resistance were tested according to GB / T5470 standard, and the volume resistivity was tested according to conventional insulation material testing standards. All samples were tested in three parallel tests and the average value was taken. The performance test data are shown in Table 2.

[0078] Table 2 Thermal conductivity and insulation core performance test

[0079] As shown in Table 2, the thermal greases prepared in Examples 1-3 of this invention exhibit excellent and progressively improving performance in the core thermal conductivity and insulation indicators, fully meeting the requirements for high-power electronic devices. Regarding thermal conductivity, Examples 1-3 show a steady increase from 13.8 W / m·K to 14.6 W / m·K, both far exceeding the threshold of 13.8 W / m·K; thermal resistance decreases from 0.009 K·cm² / W to 0.008 K·cm² / W, both below the threshold of 0.009 K·cm² / W, demonstrating a stepwise improvement in thermal conductivity; and volume resistivity reaches 10¹. 4 With a thermal conductivity of Ω·cm and above, it exhibits excellent insulation properties. The micron-sized composite thermally conductive filler is a blend of diamond powder, aluminum nitride powder, and insulating modified metal powder in a specific ratio. The filler, with a particle size of 1~50μm, fully fills the gaps between the liquid metal and the epoxy matrix, synergistically constructing a continuous and dense thermally conductive pathway with the gallium indium tin liquid metal. The nano-sized sheet-like hydrophobic modified boron nitride further improves the thermally conductive network. At the same time, its insulating properties, together with the insulating layer of the insulating modified metal powder, form a double insulation guarantee, achieving both high thermal conductivity and high insulation, thus solving the problem of traditional thermal pastes that are difficult to balance insulation and thermal conductivity.

[0080] The thermal conductivity and insulation performance of Comparative Examples 1-2 were significantly lower than those of the Example. In terms of thermal conductivity, Comparative Example 1 had a thermal conductivity of only 10.2 W / m·K, which was less than 70% of that of Example 3 (14.6 W / m·K); Comparative Example 2 had a thermal conductivity of 12.8 W / m·K, which still did not reach the threshold of 13.8 W / m·K. The thermal resistance increased to 0.015 K·cm² / W and 0.011 K·cm² / W, respectively, indicating a significant decrease in thermal conductivity. In terms of volume resistivity, Comparative Examples 1-2 were only at the level of 10³ Ω·cm, indicating extremely poor insulation performance, which could not meet the insulation requirements of high-power electronic devices. Comparative Examples 1 and 2 both lacked nanoscale sheet-like hydrophobic modified boron nitride, which not only lacked the core component for a complete thermally conductive network but also lost the key filler that imparts insulation performance to the system. At the same time, without the assistance of the sheet-like barrier network, the dispersibility of the thermally conductive filler was also affected, ultimately leading to a decline in both thermal conductivity and insulation performance. This fully demonstrates that the synergistic effect of nanoscale sheet-like hydrophobic modified boron nitride and composite thermally conductive filler is the key to ensuring the core performance of thermal conductivity and insulation.

[0081] The storage and use stability of the epoxy-based non-curing, high thermal conductivity insulating liquid metal thermal grease prepared in Examples 1-3 and Comparative Examples 1-2 were analyzed using a combination of room temperature storage and high temperature aging. The samples were sealed and stored at 25℃ / 60% humidity for one year, and at the same time, a high temperature aging test of 150℃ / 1000h was conducted on the samples. The curing state and delamination of the samples were observed, and the thermal conductivity retention rate after high temperature aging (thermal conductivity after aging / initial thermal conductivity × 100%) was tested. The performance test data are shown in Table 3.

[0082] Table 3 Storage and Usage Stability Test

[0083] As shown in Table 3, the thermal conductive pastes prepared in Examples 1-3 of this invention exhibit excellent storage and usage stability. After one year of sealed storage at room temperature, they all remained completely uncured and viscous, showing no signs of curing. After high-temperature aging at 150℃ / 1000h, there was no stratification or sedimentation, and the system showed good homogeneity. The thermal conductivity retention rate reached 98% or higher, with Example 3 reaching as high as 99.3%, and the performance degradation was negligible. The polymerization inhibitor p-benzoquinone in the additives effectively inhibited the possible free radical polymerization reaction in the system, ensuring the non-curing property of the bisphenol F liquid epoxy body. The silane coupling agent KH550 significantly improved the interfacial compatibility between the inorganic filler, liquid metal, and epoxy body, ensuring that the components were uniformly dispersed during long-term storage and high-temperature aging, without stratification or sedimentation. The combination of antioxidants 1076 and 168 improved the antioxidant performance of the system and reduced performance degradation at high temperatures. The synergistic effect of the three additives ensured the storage and usage stability of the thermal conductive paste.

[0084] While Comparative Examples 1 and 2 also maintained a completely uncured state, their stability decreased significantly after high-temperature aging. Comparative Example 1 showed slight delamination and a small amount of filler sedimentation, with a thermal conductivity retention rate of only 85.5%, indicating significant performance degradation. Comparative Example 2 showed only slight delamination with no significant sedimentation, and a thermal conductivity retention rate of 90.2%, still far lower than the examples. Both Comparative Examples 1 and 2 lacked the synergistic effect of the silane coupling agent and the nanoscale sheet-like hydrophobic modified boron nitride. The inorganic filler had poor compatibility with the liquid metal and epoxy matrix, resulting in decreased interfacial bonding at high temperatures and easy delamination and sedimentation. Furthermore, the lack of spatial support from the sheet-like barrier network made the filler prone to sedimentation, ultimately leading to damage to the thermal conductivity network and a significant reduction in thermal conductivity retention rate. This further highlights the importance of additive formulation and triple network synergy in improving the storage and use stability of thermal conductive paste.

[0085] The comprehensive performance comparison analysis of Example 3 of this invention and commercially available mainstream thermal pastes for high-power electronic devices (Honeywell 7950, Momentive 7000, and Dow Corning 5888) was conducted using national standard and industry-standard testing methods. Thermal conductivity and thermal resistance were tested according to GB / T5470 standard, and volume resistivity was tested according to conventional insulation material testing standards. After the samples were coated on the heat dissipation substrate, a constant temperature aging test of 125℃ / 1000h was conducted to observe the liquid metal overflow. At the same time, the curing state and actual repairability of the samples were visually evaluated. All tests followed the same standards and operating procedures. The performance test data are shown in Table 4.

[0086] Table 4 Comparison Test of Comprehensive Performance of Thermal Paste

[0087] As shown in Table 4, the thermal paste prepared in Example 3 of this invention exhibits superior overall performance compared to mainstream commercial products. Its core heat dissipation performance is particularly outstanding, with a thermal conductivity of 14.6 W / m·K, significantly higher than products such as Honeywell 7950, Momentive 7000, and Dow Corning 5888. Its thermal resistance is only 0.008 K·cm² / W, significantly lower than commercially available products, and its volume resistivity reaches 5.2 × 10¹⁸. 4With a Ω·cm insulation rating comparable to commercially available products, this thermal paste fully meets the high insulation requirements of high-power electronic devices. Furthermore, it exhibits no liquid metal leakage after aging at 125℃ for 1000 hours and remains non-cured for an extended period, demonstrating excellent maintainability. This superior performance is attributed to the innovative design of this invention. The triple-network synergistic liquid-locking structure—comprising a thixotropic network, a micro-crosslinked elastic network, and a sheet-like barrier network—achieves long-term locking of the liquid metal. The gallium indium tin (GaInT) liquid metal, combined with micron-level composite thermally conductive fillers, constructs a continuous, dense, and highly efficient thermally conductive network. Nanoscale sheet-like hydrophobically modified boron nitride assists in liquid locking while simultaneously enhancing thermal conductivity and imparting insulation properties. The non-curing matrix of bisphenol F liquid epoxy, combined with the polymerization inhibitor regulating benzoquinone, ensures the maintainability of the thermal paste. The synergistic effect of these components achieves a unified performance across the entire temperature range: liquid locking, high thermal conductivity, high insulation, and non-curing.

[0088] In comparison, most commercially available thermal pastes have varying degrees of performance shortcomings, making it difficult to meet the comprehensive heat dissipation needs of high-power electronic devices. Honeywell 7950, while not experiencing high-temperature overflow and meeting insulation standards, has a low thermal conductivity, high thermal resistance, and insufficient heat dissipation efficiency. Furthermore, its semi-cured state makes it difficult to remove during device repair, resulting in poor maintainability. Momentive 7000 is a non-cured system with good maintainability, but its thermal conductivity still shows significant shortcomings. After aging at 125℃ / 1000h, it exhibits trace amounts of liquid metal overflow, indicating a defect in its liquid-locking performance. Dow Corning 5888 has the lowest thermal conductivity and highest thermal resistance among the four samples, resulting in the worst heat dissipation. Its cured state completely renders it unrecoverable, making it impossible to remove after device failure, significantly increasing repair costs and difficulty. Commercially available products cannot simultaneously achieve the multiple performance requirements of high thermal conductivity, full-temperature-range liquid locking, high insulation, and non-curing maintainability because they lack an efficient synergistic liquid-locking structure and have limitations in the compounding of thermally conductive fillers and the selection of matrix. This further highlights the technical advantages and application value of the thermal paste of this invention in the field of heat dissipation of high-power electronic devices.

[0089] In summary, the embodiments of this application utilize a triple-network synergistic liquid-locking structure constructed from thixotropic networks, micro-crosslinked elastic networks, and sheet-like barrier networks; a synergistic compounding of micron-level composite thermally conductive fillers and nano-level sheet-like hydrophobic modified boron nitride for thermal conductivity and insulation; and a special additive compounding of polymerization inhibitors, antioxidants, and silane coupling agent KH550 to regulate the process. This resulted in the preparation of an epoxy-based, non-curing, liquid-locking, highly thermally conductive, insulating liquid metal thermal grease. The synergistic effect of the triple network enabled Examples 1-3 to achieve high thermal conductivity at -50℃ / 72h, 230℃ / 30min, and 150℃. In the full-temperature range liquid-locking test at ℃ / 1000h, there was no stratification, flow, or overflow, indicating excellent overall performance. However, comparative examples 1-2, with missing network components, showed varying degrees of liquid metal overflow, with poor and medium liquid-locking performance, respectively. The synergistic construction of a highly efficient thermally conductive network by micron-level composite thermally conductive filler and nano-level sheet-like hydrophobic modified boron nitride, along with dual insulation protection, resulted in thermal conductivity of 13.8-14.6 W / m・K, thermal resistance ≤0.009 K・cm² / W, and volume resistivity ≥1.2×10¹ for Examples 1-3. 4 The thermal conductivity (Ω·cm) fully meets the requirements of high-power electronic devices. Comparative Examples 1-2, which lack boron nitride, exhibited significantly reduced thermal conductivity, failing to reach the threshold and having a volume resistivity only in the 10³ Ω·cm range. The synergistic regulation of the three additives allowed Examples 1-3 to remain a completely non-curing, viscous paste after one year of storage at room temperature. After 150°C / 1000h high-temperature aging, there was no delamination or sedimentation, and the thermal conductivity retention rate reached 98.2%-99.3%. Comparative Examples 1-2, on the other hand, showed delamination and sedimentation problems, resulting in a significantly reduced thermal conductivity. With a thermal conductivity retention rate of only 85.5%-90.2%, this thermal paste's overall performance far surpasses mainstream commercially available products such as Honeywell 7950, Momentive 7000, and Dow Corning 5888. It boasts a thermal conductivity of 14.5 W / m·K, a thermal resistance of 0.008 K·cm² / W, and exhibits no overflow or long-term non-curing after 125℃ / 1000h aging. It also demonstrates excellent maintainability, addressing the shortcomings of commercially available products such as low heat dissipation efficiency, defects in liquid lock, and poor maintainability. It perfectly meets the heat dissipation needs of high-power electronic devices.

[0090] According to the embodiments of this application, an epoxy-based non-curing liquid-locking high thermal conductivity insulating liquid metal thermal grease and its preparation method are proposed. Hydrophobic nano-fumed silica, hydrophobic MQ silicone resin, and nano-scale sheet-like hydrophobic modified boron nitride synergistically construct a thixotropic-micro-crosslinked elastic-sheet-like barrier triple network liquid-locking structure. Relying on the formation mechanism and interpenetration of each network, a dense elastic liquid-locking system is formed, achieving long-term locking of gallium indium tin (GaInT) liquid metal across the entire temperature range of -50℃ to 230℃. After a long-term reliability test at 150℃ / 1000h, no liquid metal overflow was observed, solving the core problem of easy flow and overflow in traditional liquid metal thermal greases across the entire temperature range. The GaInT liquid metal is prepared at a weight percentage of 68-70% gallium, 20-22% indium, and 8-10% tin. The core thermally conductive medium is prepared using a specific ratio (melting point 10~20℃, percentage 30.0~40.0%). Micron-sized composite thermally conductive fillers are compounded in a mass ratio of 2:(1.0~2.0):(1.0~2.0) with micron-sized diamond powder, aluminum nitride powder, and insulating modified metal powder (aluminum / copper powder as the core, silicon dioxide / boron nitride as the insulating layer, particle size 1~50μm, percentage 38.0~42.4%). These two components synergistically fill the voids in the triple network, constructing a continuous and dense thermally conductive network. This is further enhanced by nano-sized sheet-like hydrophobic modified boron nitride, which, together with the insulating modified metal powder, provides double insulation. This results in a thermal conductivity ≥13.8W / m・K, thermal resistance ≤0.009K・cm² / W, and volume resistivity ≥10¹. 4 Ω・cm, solving the problem of decreased thermal conductivity caused by adding a large amount of insulating filler to traditional thermal pastes; the additive system is compounded in the proportion of polymerization inhibitor p-benzoquinone (0.10~0.20%), antioxidant 1076 and 168 mixed in equal mass (0.50~1.00%), and silane coupling agent KH550 (0.40~0.70%), respectively achieving the following: inhibiting free radical polymerization to ensure the non-curing property of bisphenol F liquid epoxy body, improving the antioxidant performance of thermal paste to extend service life, improving the interfacial compatibility between inorganic filler and liquid metal and epoxy body to ensure uniform dispersion of components, giving thermal paste excellent maintainability and morphological stability.

[0091] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

[0092] The present application and its embodiments have been described above. This description is not restrictive, and the actual application is not limited thereto. In conclusion, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the spirit of this application, such design should fall within the protection scope of this application.

Claims

1. A non-curing, liquid-locking, high thermal conductivity, insulating liquid metal thermal grease, characterized in that, Its composition by weight percentage is as follows: Bisphenol F liquid epoxy: 5.0~12.0%; Hydrophobic MQ silicone resin: 0.1~1.0%; Hydrophobic nano-fumed silica: 0.3~1.2%; Nanoscale sheet-like hydrophobically modified boron nitride: 0.1~1.5%; Gallium indium tin liquid metal: 30.0~40.0%; Micron-scale composite thermally conductive filler: 38.0~42.4%; Additives: 1.0~1.9%.

2. The epoxy-based non-curing, liquid-locking, high thermal conductivity insulating liquid metal thermal grease according to claim 1, characterized in that, The micron-sized composite thermal conductive filler is composed of micron-sized diamond powder, micron-sized aluminum nitride powder, and insulating modified metal powder in a mass ratio of 2:(1.0~2.0):(1.0~2.0), and the particle size of the micron-sized composite thermal conductive filler is 1~50μm.

3. The epoxy-based non-curing, liquid-locking, high thermal conductivity insulating liquid metal thermal grease according to claim 2, characterized in that, The insulating modified metal powder is composed of metal powder and an insulating layer, wherein the metal powder includes aluminum powder or copper powder, and the insulating layer includes silicon dioxide or boron nitride.

4. The epoxy-based non-curing, liquid-locking, high thermal conductivity, insulating liquid metal thermal grease according to claim 1, characterized in that, The additives consist of a polymerization inhibitor, p-benzoquinone, an antioxidant, and a silane coupling agent, KH550. The p-benzoquinone polymerization inhibitor constitutes 0.10-0.20% of the thermal paste by weight. The antioxidant is an equal mass mixture of antioxidant 1076 and antioxidant 168, wherein the equal mass mixture of antioxidant 1076 and antioxidant 168 constitutes 0.50-1.00% of the thermal paste by weight. The silane coupling agent, KH550, constitutes 0.40-0.70% of the thermal paste by weight.

5. The epoxy-based non-curing, liquid-locking, high thermal conductivity, insulating liquid metal thermal grease according to claim 1, characterized in that, The gallium indium tin liquid metal is composed of 68-70% gallium, 20-22% indium, and 8-10% tin by weight percentage, and the melting point of the gallium indium tin liquid metal is 10-20°C.

6. The epoxy-based non-curing, liquid-locking, high thermal conductivity, insulating liquid metal thermal grease according to claim 1, characterized in that, The nanoscale sheet-like hydrophobic modified boron nitride has a sheet diameter of 50~200nm. The nanoscale sheet-like hydrophobic modified boron nitride is composed of boron nitride and a modifier, wherein the modifier is a silane coupling agent KH550 or KH570.

7. The epoxy-based non-curing, liquid-locking, high thermal conductivity, insulating liquid metal thermal grease according to claim 1, characterized in that, The specific surface area of ​​the hydrophobic nano-fumed silica is 200~300m² / g, and the molar ratio of the hydrophobic MQ silicone resin is M:Q=1:(1.5~3.0).

8. A method for preparing an epoxy-based non-curing, liquid-locking, high thermal conductivity, insulating liquid metal thermally conductive paste as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Pretreatment of epoxy matrix: Mix the bisphenol F liquid epoxy and hydrophobic MQ silicone resin according to the formula, heat to 80~100℃, keep warm for 1~4h, then cool to 30~45℃, add the polymerization inhibitor p-benzoquinone and antioxidant according to the formula, stir at 500~1000r / min until the system is uniform, and obtain the pretreated epoxy matrix; (2) Dispersion of filler and functional components: GaInT liquid metal, micron-scale composite thermally conductive filler, nano-scale sheet-like hydrophobic modified boron nitride and silane coupling agent KH550 are added sequentially to the pretreated epoxy matrix and stirred at low speed. Then, hydrophobic nano-vaporized silica is added and dispersed at high speed to obtain a mixed slurry. (3) Vacuum degassing: The mixed slurry is placed in a vacuum degassing machine and degassed for 15 to 35 minutes under a vacuum of -0.08 to -0.1 MPa and a temperature of 20 to 30°C. After degassing is completed, the material is discharged to obtain the thermal paste.

9. The preparation method according to claim 8, characterized in that, In step (2), the speed of low-speed stirring is 600~1000r / min and the stirring time is 20~40min. The speed of high-speed dispersion is 2500~3500r / min and the dispersion time is 30~70min. During the high-speed dispersion process, air cooling is used to control the system temperature to not exceed 50℃.

10. The epoxy-based non-curing liquid-locking high thermal conductivity insulating liquid metal thermal grease as described in any one of claims 1-7, through the synergistic effect of the thixotropic network formed by hydrophobic nano-vaporized silica, the micro-crosslinked elastic network formed by hydrophobic MQ silicone resin, and the sheet-like barrier network formed by nano-scale sheet-like hydrophobic modified boron nitride, constitutes a triple-network liquid-locking structure, realizing the locking of gallium indium tin liquid metal in the full temperature range of -50℃ to 230℃, and after a long-term reliability test of 150℃ / 1000h, there is no liquid metal overflow, which is used for heat dissipation of high-power electronic devices.

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