Anti-corrosion and anti-leakage copper skeleton / liquid metal composite thermal interface material and preparation method thereof

Abstract

This invention discloses a corrosion-resistant and leak-proof copper skeleton / liquid metal composite thermal interface material and its preparation method. The composite thermal interface material comprises: a copper skeleton; and a liquid metal alloy filling the pores of the skeleton; wherein the surface of the copper skeleton is provided with a chemically modified layer to prevent direct contact between the liquid metal and the metal substrate of the copper skeleton. This invention, by introducing a dense and stable chemically modified layer on the surface of the copper skeleton, effectively blocks direct physical contact and atomic diffusion paths between the liquid metal and the metal substrate, thereby significantly inhibiting corrosion reactions and ensuring the structural integrity and thermal performance stability of the material under long-term thermal cycling or high-temperature aging conditions.

Description

Technical Field

[0001] This invention belongs to the field of thermal management materials technology, specifically relating to a composite thermal interface material for heat dissipation of electronic devices and its preparation method, and more particularly to a corrosion-resistant and leak-proof copper skeleton / liquid metal composite thermal interface material and its preparation method. Background Technology

[0002] With the rapid development of high-power-density electronic devices such as 5G base station chips, GPUs, and electric vehicle control modules, efficient thermal management has become crucial for ensuring their reliable operation. Thermal interface materials, as functional materials that fill the micron-level gaps between chips and heat sinks, play a decisive role in reducing contact thermal resistance and improving overall heat dissipation efficiency.

[0003] Liquid metals, especially gallium-based alloys, are considered ideal candidates for next-generation high-performance thermal interface materials due to their extremely high intrinsic thermal conductivity, low melting point, and good fluidity. However, their practical engineering applications have long faced two key challenges:

[0004] First, liquid metals are prone to leakage. Because they are liquid at room temperature, they may overflow from the interface when the device is tilted, vibrated, or thermally cycled, which may not only cause thermal interface failure but also lead to safety hazards such as short circuits.

[0005] Secondly, liquid metals exhibit severe interfacial reactions with commonly used metal heat dissipation structures such as copper and aluminum. Elements such as gallium readily undergo alloying reactions with copper, forming brittle intermetallic compounds such as CuGa2. This leads to corrosion of the copper substrate, structural deterioration, and the formation of a high thermal resistance reaction layer at the interface, significantly reducing thermal conductivity and long-term reliability.

[0006] To address these issues, existing technologies have explored various strategies. For example, high-melting-point indium-bismuth alloys are used to reduce fluidity, but this sacrifices low-temperature start-up capability; or the flow of liquid metal is restricted through polymer encapsulation or microencapsulation, but this often introduces additional interfacial thermal resistance, weakening its high thermal conductivity advantage; some studies have also attempted to deposit inert coatings on copper surfaces, but the process is complex, costly, and it is difficult to balance flexibility and interfacial bonding strength.

[0007] Therefore, there is an urgent need to develop a new type of composite thermal interface material that combines high thermal conductivity, corrosion resistance, leak prevention, and good flexibility, especially suitable for advanced electronic heat dissipation scenarios with stringent requirements for low-temperature start-up performance, long-term stability, and safety and reliability. Summary of the Invention

[0008] To overcome the above problems, this invention proposes a corrosion-resistant and leak-proof copper skeleton / liquid metal composite thermal interface material and its preparation method.

[0009] Specifically, the object of the present invention is to provide the following aspects:

[0010] In a first aspect, a composite thermal interface material of a copper skeleton and liquid metal is provided, wherein the liquid metal fills the pores of the copper skeleton, and the surface of the copper skeleton is provided with a chemically modified layer for preventing the liquid metal from directly contacting the copper skeleton.

[0011] Optionally, the porous copper skeleton has a three-dimensional interconnected pore structure.

[0012] Optionally, the liquid metal alloy is a gallium-based alloy.

[0013] Optionally, the gallium-based alloy is a gallium-indium alloy or a gallium-indium-tin alloy.

[0014] Optionally, the chemically modified layer is a hydroxylated layer.

[0015] Optionally, the chemically modified layer is a carboxylated layer.

[0016] Optionally, the chemically modified layer is a self-assembled monolayer.

[0017] In a second aspect, a method for preparing the composite thermal interface material described in the first aspect is provided, the method comprising:

[0018] S1, Clean the surface of the copper skeleton;

[0019] S2 forms a chemically modified layer on the cleaned copper skeleton surface;

[0020] S3, liquid metal is filled into the pores of a copper skeleton with a chemically modified layer to obtain the composite thermal interface material.

[0021] Optionally, in S1, the surface cleaning includes sequential organic solvent cleaning, acid washing, and deionized water rinsing.

[0022] Thirdly, the application of the composite thermal interface material according to the first aspect of the present invention in the thermal management of electronic devices is provided.

[0023] The beneficial effects of this invention include: the composite thermal interface material provided by this invention solves the long-standing corrosion and leakage problems of liquid metal thermal interface materials by constructing a chemically modified layer on the surface of a copper skeleton and combining it with the high thermal conductivity of liquid metal. It also fully leverages the advantages of high thermal conductivity and flexibility of liquid metal, making it particularly suitable for heat dissipation scenarios of electronic devices with high requirements for low-temperature start-up and reliability. Attached Figure Description

[0024] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0025] In the attached diagram:

[0026] Figure 1 Comparative images of the composite thermal interface materials prepared in Examples 1-3 and Comparative Example 1 are shown.

[0027] Figure 2 The image shows the composite thermal interface material prepared in Example 3, and a physical image of the liquid metal leakage test.

[0028] Figure 3 The results of effective thermal resistance tests of the composite thermal interface materials prepared in Examples 1-3 and Comparative Example 1 are shown.

[0029] Figure 4 The images show a comparison of the corrosion resistance morphology of the composite thermal interface materials prepared in Examples 1-3 and Comparative Example 1 after high-temperature aging. Detailed Implementation

[0030] The following will refer to the appendix. Figures 1 to 4 Specific embodiments of the invention will be described in more detail below. While specific embodiments of the invention are shown in the accompanying drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0031] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0032] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this invention, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0034] On the one hand, according to the present invention, a copper skeleton / liquid metal composite thermal interface material is provided, wherein the liquid metal fills the pores of the copper skeleton, and the surface of the copper skeleton is provided with a chemically modified layer for preventing the liquid metal from directly contacting the copper skeleton.

[0035] In this invention, although gallium-based liquid metal alloys possess excellent intrinsic thermal conductivity, their high chemical reactivity makes them prone to interfacial alloying or electrochemical corrosion with metallic copper, leading to deterioration of the copper framework structure, increased interfacial thermal resistance, and even device failure. This invention addresses this by introducing a dense, stable chemically modified layer onto the surface of the copper framework, effectively blocking direct physical contact and atomic diffusion paths between the liquid metal and the metal substrate. This significantly inhibits corrosion reactions and ensures the structural integrity and thermal stability of the material under long-term thermal cycling or high-temperature aging conditions.

[0036] Meanwhile, the copper framework itself possesses a three-dimensional interconnected micro-nano pore structure, utilizing its capillary forces to physically confine the liquid metal. Furthermore, because the framework itself retains the high thermal conductivity network of copper, and the liquid metal fully fills the pores to form a continuous heat conduction pathway, the material exhibits excellent interfacial thermal conductivity overall.

[0037] In this invention, the copper skeleton has a three-dimensionally interconnected porous structure with a mesh size of 200-350 mesh, a pore diameter of 0.045-0.08 mm, and a thickness of 0.05-0.1 mm. With these structural parameters, the skeleton can effectively confine liquid metal through capillary action and, together with the filled liquid metal, construct a continuous heat-conducting network with low thermal resistance. For example, the copper skeleton may have a mesh size of 350 mesh, a pore diameter of 0.045 mm, and a thickness of 0.08 mm.

[0038] Furthermore, the copper skeleton is a woven copper mesh or perforated copper foil, which has high thermal conductivity and good machinability, and is widely used as a heat dissipation substrate material.

[0039] In this invention, the liquid metal alloy is a gallium-based alloy, which remains liquid at room temperature and low temperatures, possessing both high thermal conductivity and good fluidity, making it suitable for electronic heat dissipation scenarios with high requirements for low-temperature start-up performance. Preferably, the gallium-based alloy is selected from any of the following: containing 75 wt% gallium and 25 wt% indium (melting point 16°C); containing 62.5 wt% gallium, 21.5 wt% indium, and 16 wt% tin (melting point 10.7°C); containing 68.5 wt% gallium, 21.5 wt% indium, and 10 wt% tin (melting point -19°C).

[0040] In this invention, the chemically modified layer is a hydroxylated layer, a carboxylated layer, or a self-assembled monolayer. These modified layers can form a dense and stable interfacial barrier on the surface of the copper framework, effectively suppressing atomic diffusion and electrochemical reactions between the liquid metal and the metal substrate, while also ensuring confinement stability and thermal conductivity.

[0041] The hydroxylation layer is formed in situ on the surface of the copper framework under the action of alkaline hydrogen peroxide, creating a hydroxyl layer rich in -OH functional groups. This layer serves to block the penetration and corrosion of liquid metal. The reaction that occurs is initial oxidation under alkaline conditions: 2Cu + H₂O₂ + 2OH⁻ - → Cu2O + 2H2O + O2↑, further hydroxylation: Cu2O + H2O2 + 2OH - → 2Cu(OH)2.

[0042] The carboxylation layer utilizes mercaptocarboxylic acid molecules. The thiol group (-SH) has a strong affinity for copper, while the terminal carboxyl group (-COOH) provides a polar interface, preventing excessive penetration of liquid metal and maintaining wettability to ensure thermal contact. Taking 11-mercaptoundecanoic acid as an example, the reaction is: Cu + HS-(CH2) 10 -COOH → Cu-S-(CH2) 10 -COOH + ½H2↑.

[0043] The self-assembled monolayer is formed by first hydrolyzing a silane coupling agent to generate silanol, which then undergoes dehydration condensation with the copper surface to form a stable Si-O-Cu covalent interface. Taking (3-aminopropyl)triethoxysilane as an example, the reactions are as follows: the hydrolysis reaction is (C2H5O)3-Si-(CH2)3-NH2 + 3H2O → (HO)3-Si-(CH2)3-NH2 + 3C2H5OH, and the condensation reaction is Cu-OH + (HO)3-Si-(CH2)3-NH2 → Cu-O-Si-(CH2)3-NH2 + H2O.

[0044] In this invention, the thickness of the chemically modified layer is 5-20 nm, preferably 10 nm. The reason for choosing this parameter is that when the thickness of the modified layer is less than 5 nm, it is difficult to form a continuous interface layer, which makes it easy for liquid metal to penetrate and alloy with copper, reducing the stability of the material; while when the thickness exceeds 20 nm, although the interfacial bonding force is enhanced, the low thermal conductivity of the organic layer significantly increases the interfacial thermal resistance, affecting the overall thermal conductivity.

[0045] In this invention, the material has excellent thermal stability, and after 1000 cycles of thermal shock at 0°C-100°C, the effective thermal resistance change is less than 20%.

[0046] On the other hand, according to the method for preparing the material according to the first aspect of the present invention, the method includes:

[0047] S1, Clean the surface of the copper skeleton;

[0048] S2 forms a chemically modified layer on the cleaned copper skeleton surface;

[0049] S3, liquid metal is filled into the pores of a copper skeleton with a chemically modified layer to obtain the composite thermal interface material.

[0050] The above methods will be described in detail below.

[0051] In S1, the copper skeleton is surface cleaned to remove grease, oxides, dust and other organic or inorganic contaminants adhering to its surface, thereby obtaining a clean and active metal surface, which provides a basis for the uniform film formation of the subsequent chemically modified layer.

[0052] Specifically, the surface cleaning includes sequential organic solvent cleaning, acid washing, and deionized water rinsing.

[0053] The organic solvent cleaning process includes: ultrasonically cleaning the copper skeleton sequentially in acetone and then in ethanol, with each ultrasonic cleaning session lasting 5-10 minutes. This can be understood as: ultrasonically cleaning the copper skeleton in acetone for 5-10 minutes, followed by ultrasonic cleaning in ethanol for 5-10 minutes.

[0054] The pickling process removes the oxide layer (such as CuO / Cu2O) that naturally forms on the copper framework surface in the air, exposing the reactive metallic copper and ensuring that the subsequent chemical modification layer can form a uniform and robust film. A 0.1 mol / L H2O solution is preferred. ＋ The hydrochloric acid or sulfuric acid, preferably 0.1 mol / L H₂O, is preferred. ＋Hydrochloric acid. This concentration effectively dissolves metal oxides while avoiding excessive corrosion of copper or collapse of the pore structure due to excessive acidity; for example, 0.1 mol / L HCl can remove the oxide layer within 3-5 minutes without corroding the copper substrate, balancing cleaning efficiency and structural integrity.

[0055] After pickling, the metal is repeatedly rinsed with a large amount of deionized water until the rinsing solution is neutral to completely remove residual acid. Then, high-purity nitrogen is used to dry the metal to prevent secondary oxidation of the metal surface in the air after cleaning. Finally, a clean, activated and structurally complete copper skeleton is obtained for subsequent chemical modification treatment.

[0056] In S2, a chemically modified layer is formed on the cleaned copper skeleton surface by any one of hydroxylation, carboxylation, or self-assembly treatment.

[0057] In one embodiment, a hydroxylation treatment is employed to form a chemically modified layer on the surface of a cleaned copper skeleton. This includes immersing the copper skeleton in an alkaline hydrogen peroxide solution and reacting it at room temperature for 1-4 hours to generate an oxide layer rich in -OH functional groups in situ on its surface; after the reaction, rinsing with deionized water and drying with nitrogen gas for later use.

[0058] Preferably, the alkaline hydrogen peroxide solution is prepared by adjusting the pH of a 3%-30% (w / w) H₂O₂ solution to 8-10 using a strong alkali. Under these conditions, H₂O₂ decomposes in the alkaline environment to generate reactive oxygen species, promoting controlled oxidation on the copper surface and forming a uniform hydroxylation layer. This hydroxylation layer has high polarity and chemical inertness, effectively preventing the diffusion of liquid metal atoms, such as gallium atoms, into the copper. Simultaneously, it enhances the interfacial bonding with the liquid metal through hydrogen bonding, reducing contact thermal resistance.

[0059] For example, the alkaline hydrogen peroxide solution is prepared by adjusting the pH to 9 with a 25-30% H2O2 solution and sodium hydroxide or potassium hydroxide. The copper skeleton is immersed in the prepared alkaline hydrogen peroxide solution and reacted at room temperature for 2-3 hours. After the reaction is completed, it is rinsed with deionized water, dried with nitrogen, and then used for later use.

[0060] In one embodiment, a carboxylation treatment is employed to form a chemically modified layer on the cleaned copper framework surface. This includes immersing the copper framework in an organic solution containing mercaptocarboxylic acid, and reacting it at 800-1200 rpm for 12-48 hours under light-protected, room-temperature conditions with stirring, thereby causing strong coordination adsorption of mercapto groups (-SH) onto the copper surface, forming a self-assembled carboxylated monolayer or multilayer structure; the terminal carboxyl groups (-COOH) provide a polar interface.

[0061] Preferably, the thiocarboxylic acid is 11-mercaptoundecanoic acid (11-MUA), the organic solvent is toluene, and the concentration of the thiocarboxylic acid is 1-20 mM. After the reaction is complete, the mixture is ultrasonically cleaned sequentially with toluene and deionized water to remove physically adsorbed molecules, and then dried with nitrogen gas for later use, resulting in a modified framework with a surface rich in -COOH functional groups. This carboxylated layer utilizes the steric hindrance effect of the long alkyl chain to restrict the penetration of liquid metal, while the terminal carboxyl groups provide a moderately polar interface, preventing leakage while maintaining good thermal contact.

[0062] Furthermore, toluene, being an aprotic, low-polarity organic solvent, exhibits excellent solubility for 11-MUA and does not undergo side reactions with thiol groups (-SH) or metal surfaces. More importantly, toluene's low surface tension facilitates solution penetration into the micron-scale channels of the porous framework, ensuring uniform film formation throughout the entire three-dimensional network, rather than merely covering the surface. When the concentration of 11-MUA is below 1 mM, it is difficult to form a continuous barrier; while above 20 mM, it easily leads to multilayer physical adsorption or molecular aggregation, which in turn reduces the stability and density of the film.

[0063] For example, the copper skeleton is immersed in a toluene solution of 10-11 mM 11-mercaptoundecanoic acid and stirred at 1200-1300 rpm for 24-36 h under light-protected, room temperature conditions; then, the copper skeleton is ultrasonically cleaned with toluene and deionized water in sequence; finally, it is dried with nitrogen gas for later use.

[0064] In one embodiment, a self-assembly process is employed to form a chemically modified layer on the cleaned copper framework surface. This includes: immersing the copper framework in an organic solution containing a silane coupling agent, stirring at 1200-1500 rpm for 12-48 hours at room temperature and in the dark, allowing it to spontaneously form an ordered monolayer on the copper surface; after the reaction is complete, ultrasonically cleaning with toluene and deionized water sequentially to remove physically adsorbed molecules, and drying with nitrogen gas for later use.

[0065] Preferably, the silane coupling agent is selected from at least one of 3-mercaptopropyltriethoxysilane (MPTES), (3-aminopropyl)triethoxysilane (APTES), 3-chloropropyltriethoxysilane (CPTES), and n-butyltriethoxysilane; the organic solution is toluene. That is, the silane coupling agent is prepared into a 1-20 mM toluene solution.

[0066] Furthermore, silane molecules hydrolyze to generate silanol (Si-OH), which then condenses with hydroxyl groups on the metal surface to form Si-O-Cu bonds, constructing a stable covalently linked monolayer. This layer is typically 5-20 nm thick, has a dense structure, and efficiently blocks atomic-level diffusion channels; its terminal functional groups (-SH, -NH2, -Cl, -CH3, etc.) can also flexibly adjust the surface energy, enabling precise control over the spreadability of liquid metals.

[0067] For example, the copper skeleton is immersed in a toluene solution with a silane coupling agent concentration of 10-11 mM and stirred at 1200-1300 rpm for 12-24 h at room temperature and in the dark; then, the copper skeleton is ultrasonically cleaned with toluene and deionized water in sequence; finally, it is dried with nitrogen gas for later use.

[0068] In S3, the capillary force and surface wetting properties of the skeleton are utilized to allow liquid metal to spontaneously or with the assistance of an external field fill its three-dimensional interconnected pores, forming a composite thermal interface material with stable structure and continuous thermal conduction.

[0069] Furthermore, the filling is preferably achieved through a wetting method or a scraping method. The wetting method utilizes the capillary force of the copper skeleton's pores, allowing the liquid metal to be automatically drawn in and fill the pores under surface tension. The scraping method involves directly applying the liquid metal to the copper skeleton, using pressure from a scraper or brush to embed it into the pores. In this invention, by constructing a chemically modified layer on the surface of the copper skeleton and combining the high thermal conductivity of the liquid metal with the capillary structure of the skeleton, the long-standing corrosion and leakage problems of liquid metal thermal interface materials are solved. It also fully leverages the advantages of high thermal conductivity and flexibility, providing a highly reliable and high-performance thermal management solution for high-power-density electronic devices.

[0070] Gallium-based liquid metals possess strong metal-dissolving capabilities and readily alloy with copper, forming a brittle Cu-Ga phase that leads to structural damage and increased interfacial thermal resistance. This invention addresses this by introducing hydroxylated layers, carboxylated layers, or silane self-assembled monolayers to form a dense and stable chemical barrier on the metal surface. This effectively blocks the diffusion path of gallium atoms into the matrix, significantly inhibiting corrosion. Experiments demonstrate that the modified composite material retains its structural integrity after aging at 400°C for 4 hours, showing no significant oxidation or breakage. Furthermore, it can withstand repeated bending without cracking, achieving low-stress, high-fit interfacial coupling, making it suitable for curved packaging or flexible electronics applications.

[0071] Furthermore, despite the high fluidity of liquid metal, this invention utilizes the capillary force generated by the three-dimensional interconnected microporous structure of the copper framework to physically confine the liquid metal. Simultaneously, the chemically modified layer prevents excessive spreading or leakage of the liquid metal by regulating surface energy (such as the steric hindrance of long alkyl chains or the wetting balance of polar functional groups). The resulting material showed no leakage after being vertically suspended for 1 hour or under thermal shock conditions, meeting the stringent safety requirements of electronic devices.

[0072] Finally, the selected gallium-based alloy has a melting point of -19°C and remains liquid at room temperature and low temperatures (-19°C), ensuring rapid thermal response of the equipment in cold environments; simultaneously, the chemically modified layer withstands 1000 thermal cycles (0°C) The thermal resistance change is less than 20% after 100°C, making it suitable for extreme conditions such as 5G base stations, electric vehicle electronic control, and aerospace.

[0073] Thirdly, the application of the composite thermal interface material described in the first aspect of the present invention or the composite thermal interface material prepared according to the method described in the second aspect in the thermal management of electronic devices.

[0074] Example

[0075] The present invention is further described below through specific examples; however, these examples are merely exemplary and do not constitute any limitation on the scope of protection of the present invention.

[0076] Example 1

[0077] Preparation of hydroxylated modified copper mesh / gallium indium alloy composite thermal interface material

[0078] (1) Take a copper mesh with a mesh size of 350, an aperture of 0.045 mm and a thickness of 0.08 mm, and place it in acetone, anhydrous ethanol and 0.1 mol / L dilute hydrochloric acid in sequence, and ultrasonically clean it for 5 minutes each; then rinse it with a large amount of deionized water until neutral, and blow it dry with high-purity nitrogen to obtain a clean copper mesh.

[0079] (2) Prepare a 30% hydrogen peroxide solution and add 2 mol / L sodium hydroxide solution to adjust the pH to 9 to obtain an alkaline hydrogen peroxide solution. Immerse the clean copper mesh completely in the solution and let it stand at room temperature for 2 hours. After the reaction is complete, take it out, rinse it thoroughly with deionized water, and blow it dry with nitrogen to obtain a copper mesh with surface hydroxylation modification.

[0080] (3) Fix the dried copper mesh from step (2) flat, and use a soft brush to apply gallium-indium alloy liquid metal (containing 75 wt% Ga, 25 wt% In, melting point about 16°C) gently and from multiple angles to the surface of the copper mesh. At the same time, apply 10 psi pressure to assist filling until the copper mesh shows a uniform silvery-white metallic luster, indicating that the liquid metal has been fully filled into the pores under capillary action and mechanical assistance, and finally forms a composite thermal interface material.

[0081] Example 2

[0082] Composite thermal interface materials were prepared in a manner similar to that in Example 1, except that: copper mesh / gallium indium alloy composite thermal interface materials were prepared by carboxylation modification.

[0083] (1) Take a copper mesh with a mesh size of 350, an aperture of 0.045 mm and a thickness of 0.08 mm, and place it in acetone, anhydrous ethanol and 0.1 mol / L dilute hydrochloric acid in sequence, and ultrasonically clean it for 5 minutes each; then rinse it with a large amount of deionized water until neutral, and blow it dry with high-purity nitrogen to obtain a clean copper mesh.

[0084] (2) Prepare a 10 mM toluene solution of 11-mercaptoundecanoic acid (11-MUA); immerse a clean copper mesh in the solution and stir at 1200 rpm for 24 hours at room temperature and in the dark; after the reaction is completed, clean it with toluene and deionized water by ultrasonication in sequence, and finally dry it with high-purity nitrogen to obtain a copper mesh with carboxylation modification on the surface.

[0085] (3) Fix the dried copper mesh from step (2) flat, and use a soft brush to apply gallium-indium alloy liquid metal (containing 75 wt% Ga, 25 wt% In, melting point about 16°C) gently and from multiple angles to the surface of the copper mesh. At the same time, apply 10 psi pressure to assist filling until the copper mesh shows a uniform silvery-white metallic luster, indicating that the liquid metal has been fully filled into the pores under capillary action and mechanical assistance, and finally forms a composite thermal interface material.

[0086] Example 3

[0087] Composite thermal interface materials were prepared in a manner similar to that in Example 1, except that copper mesh / gallium indium alloy composite thermal interface materials were prepared by self-assembly modification.

[0088] (1) Take a copper mesh with a mesh size of 350, an aperture of 0.045 mm and a thickness of 0.08 mm, and place it in acetone, anhydrous ethanol and 0.1 mol / L dilute hydrochloric acid in sequence, and ultrasonically clean it for 5 minutes each; then rinse it with a large amount of deionized water until neutral, and blow it dry with high-purity nitrogen to obtain a clean copper mesh.

[0089] (2) Prepare a 10 mM solution of 3-mercaptopropyltriethoxysilane (MPTES) in toluene; immerse a clean copper mesh in the solution and stir at 1200 rpm for 24 hours at room temperature and in the dark; after the reaction, clean the copper mesh with toluene and deionized water for 10 minutes each, and dry it with nitrogen to obtain a copper mesh with a surface silane self-assembled monolayer modified.

[0090] (3) Fix the dried copper mesh from step (2) flat, and use a soft brush to apply gallium-indium alloy liquid metal (containing 75 wt% Ga, 25 wt% In, melting point about 16°C) gently and from multiple angles to the surface of the copper mesh. At the same time, apply 10 psi pressure to assist filling until the copper mesh shows a uniform silvery-white metallic luster, indicating that the liquid metal has been fully filled into the pores under capillary action and mechanical assistance, and finally forms a composite thermal interface material.

[0091] Example 4

[0092] The composite thermal interface material was prepared in a manner similar to that in Example 3, except that the self-assembly modification was performed using a toluene solution of (3-aminopropyl)triethoxysilane (APTES).

[0093] (1) Take a copper mesh with a mesh size of 350, an aperture of 0.045 mm and a thickness of 0.08 mm, and place it in acetone, anhydrous ethanol and 0.1 mol / L dilute hydrochloric acid in sequence, and ultrasonically clean it for 5 minutes each; then rinse it with a large amount of deionized water until neutral, and blow it dry with high-purity nitrogen to obtain a clean copper mesh.

[0094] (2) Prepare a 10 mM solution of (3-aminopropyl)triethoxysilane (APTES) in toluene; immerse a clean copper mesh in the solution and stir at 1200 rpm for 24 hours at room temperature and in the dark; after the reaction, clean the copper mesh with toluene and deionized water for 10 minutes each, and dry it with nitrogen to obtain a copper mesh with a surface silane self-assembled monolayer modified.

[0095] (3) Fix the dried copper mesh from step (2) flat, and use a soft brush to apply gallium-indium alloy liquid metal (containing 75 wt% Ga, 25 wt% In, melting point about 16°C) gently and from multiple angles to the surface of the copper mesh. At the same time, apply 10 psi pressure to assist filling until the copper mesh shows a uniform silvery-white metallic luster, indicating that the liquid metal has been fully filled into the pores under capillary action and mechanical assistance, and finally forms a composite thermal interface material.

[0096] Example 5

[0097] The composite thermal interface material was prepared in a manner similar to that in Example 3, except that the self-assembly modification was performed using a toluene solution of 3-chloropropyltriethoxysilane (CPTES).

[0098] (1) Take a copper mesh with a mesh size of 350, an aperture of 0.045 mm and a thickness of 0.08 mm, and place it in acetone, anhydrous ethanol and 0.1 mol / L dilute hydrochloric acid in sequence, and ultrasonically clean it for 5 minutes each; then rinse it with a large amount of deionized water until neutral, and blow it dry with high-purity nitrogen to obtain a clean copper mesh.

[0099] (2) Prepare a 10 mM solution of 3-chloropropyltriethoxysilane (CPTES) in toluene; immerse a clean copper mesh in the solution and stir at 1200 rpm for 24 hours at room temperature and in the dark; after the reaction, clean the copper mesh with toluene and deionized water for 10 minutes each, and dry it with nitrogen to obtain a copper mesh with a surface silane self-assembled monolayer modified.

[0100] (3) Fix the dried copper mesh from step (2) flat, and use a soft brush to apply gallium-indium alloy liquid metal (containing 75 wt% Ga, 25 wt% In, melting point about 16°C) gently and from multiple angles to the surface of the copper mesh. At the same time, apply 10 psi pressure to assist filling until the copper mesh shows a uniform silvery-white metallic luster, indicating that the liquid metal has been fully filled into the pores under capillary action and mechanical assistance, and finally forms a composite thermal interface material.

[0101] Example 6

[0102] The composite thermal interface material was prepared in a manner similar to that in Example 5, except that the gallium-based alloy used contained 62.5 wt% gallium, 21.5 wt% indium and 16 wt% tin (melting point 10.7°C).

[0103] (1) Take a copper mesh with a mesh size of 350, an aperture of 0.045 mm and a thickness of 0.08 mm, and place it in acetone, anhydrous ethanol and 0.1 mol / L dilute hydrochloric acid in sequence, and ultrasonically clean it for 5 minutes each; then rinse it with a large amount of deionized water until neutral, and blow it dry with high-purity nitrogen to obtain a clean copper mesh.

[0104] (2) Prepare a 10 mM solution of 3-chloropropyltriethoxysilane (CPTES) in toluene; immerse a clean copper mesh in the solution and stir at 1200 rpm for 24 hours at room temperature and in the dark; after the reaction, clean the copper mesh with toluene and deionized water for 10 minutes each, and dry it with nitrogen to obtain a copper mesh with a surface silane self-assembled monolayer modified.

[0105] (3) Fix the dried copper mesh from step (2) flat, and use a soft brush to apply gallium indium tin alloy liquid metal (containing 62.5wt% gallium, 21.5wt% indium and 16wt% tin (melting point 10.7℃) gently and at multiple angles to the surface of the copper mesh. At the same time, apply 10psi pressure to assist filling until the copper mesh shows a uniform silvery-white metallic luster, indicating that the liquid metal has been fully filled into the pores under capillary action and mechanical assistance, and finally forms a composite thermal interface material.

[0106] Example 7

[0107] The composite thermal interface material was prepared in a manner similar to that in Example 5, except that the gallium-based alloy used contained 68.5 wt% gallium, 21.5 wt% indium and 10 wt% tin (melting point -19°C).

[0108] (1) Take a copper mesh with a mesh size of 350, an aperture of 0.045 mm and a thickness of 0.08 mm, and place it in acetone, anhydrous ethanol and 0.1 mol / L dilute hydrochloric acid in sequence, and ultrasonically clean it for 5 minutes each; then rinse it with a large amount of deionized water until neutral, and blow it dry with high-purity nitrogen to obtain a clean copper mesh.

[0109] (2) Prepare a 10 mM solution of 3-chloropropyltriethoxysilane (CPTES) in toluene; immerse a clean copper mesh in the solution and stir at 1200 rpm for 24 hours at room temperature and in the dark; after the reaction, clean the copper mesh with toluene and deionized water for 10 minutes each, and dry it with nitrogen to obtain a copper mesh with a surface silane self-assembled monolayer modified.

[0110] (3) Fix the dried copper mesh from step (2) flat, and use a soft brush to apply gallium indium tin alloy liquid metal (containing 68.5 wt% gallium, 21.5 wt% indium and 10 wt% tin (melting point -19℃)) gently and at multiple angles to the surface of the copper mesh. At the same time, apply 10 psi pressure to assist filling until the copper mesh shows a uniform silvery-white metallic luster, indicating that the liquid metal has been fully filled into the pores under capillary action and mechanical assistance, and finally forms a composite thermal interface material.

[0111] Comparative Example 1

[0112] The composite thermal interface material was prepared in a manner similar to that in Example 1, except that no hydroxylation modification was performed.

[0113] (1) Take a copper mesh with a mesh size of 350, an aperture of 0.045 mm and a thickness of 0.08 mm, and place it in acetone, anhydrous ethanol and 0.1 mol / L dilute hydrochloric acid in sequence, and ultrasonically clean it for 5 minutes each; then rinse it with a large amount of deionized water until neutral, and blow it dry with high-purity nitrogen to obtain a clean copper mesh.

[0114] (2) Fix the cleaned copper mesh from step (1) flat, and use a soft brush to apply gallium-indium alloy liquid metal (containing 75 wt% Ga, 25 wt% In, melting point about 16°C) gently and from multiple angles to the surface of the copper mesh. At the same time, apply 10 psi pressure to assist filling until the copper mesh shows a uniform silvery-white metallic luster, indicating that the liquid metal has been fully filled into the pores under capillary action and mechanical assistance, and finally forms a composite thermal interface material.

[0115] Figure 1 The composite thermal interface materials prepared in Examples 1-3 and Comparative Example 1 are shown. Figure 1The images, from left to right, show a comparison of the composite thermal interface materials prepared in Example 1, Example 1, Example 2, and Example 3. The images reveal a uniform, continuous silvery-white metallic luster and a smooth surface. All modified samples remained dry and intact, without any droplets or obvious signs of wetting or diffusion.

[0116] The composite thermal interface material prepared in Example 3 was subjected to a liquid metal leakage test as follows: First, at room temperature (approximately 25°C), one end of the sample was held with clean tweezers, ensuring it was completely vertical. Then, the sample was left to stand in this state for 60 minutes to fully assess its ability to bind liquid metal under continuous gravity. Subsequently, immediately after the standing period, front and side photographs were taken of the sample to check for any liquid metal seepage or dripping from its surface and edges. The resulting physical image of the liquid metal leakage test sample is shown below. Figure 2 As shown, the presence of its chemically modified layer ensures that the liquid metal alloy does not leak when the composite thermal interface material is placed vertically.

[0117] The composite thermal interface materials prepared in Examples 1-3 and Comparative Example 1 were subjected to effective thermal resistance testing according to the following steps, using the steady-state method based on standard ASTM D5470. The samples were cut to a specified size (40 mm × 40 mm) and placed between two parallel copper pillars with known thermal conductivity and surface flatness. A one-dimensional steady-state heat flow was established at 40°C under a fixed clamping pressure of 0.1 MPa. The effective thermal resistance was calculated by measuring the heat flux density flowing through the sample and the temperature difference across the sample. The comparative results of the effective thermal resistance tests are shown below. Figure 3 As shown, it can be seen that the presence of the chemically modified layer in Examples 1-3 ensures that the effective thermal resistance change is less than 20% after 1000 cycles of thermal shock at 0℃-100℃. Among them, Example 3 has the smallest effective thermal resistance change at 8.6%, indicating that Example 3 is the best example.

[0118] The composite thermal interface materials prepared in Examples 1-3 and Comparative Example 1 were subjected to high-temperature aging at 400°C for 4 hours. The final corrosion resistance morphology was compared with that of the composite thermal interface materials prepared in Examples 1-3 and Comparative Example 1. Figure 4As shown, the presence of the chemically modified layers in Examples 1-3 ensures that the material remains intact after aging at 400°C for 4 hours, without significant corrosion or structural breakage. The material also exhibits flexibility and does not break when folded. Example 3 shows the most pronounced metallic luster because its surface coating (liquid metal) did not peel off, and the structure remained continuous. Furthermore, the creases in Example 3 are deeper and wider, indicating that under extreme bending, the material absorbs and releases stress through significant plastic deformation (crease formation), thus avoiding catastrophic brittle fracture or breakage. This demonstrates the material's excellent flexibility and ductility, making Example 3 the best example.

[0119] The present invention has been described in detail above with reference to preferred embodiments and exemplary examples. However, it should be noted that these specific embodiments are merely illustrative explanations of the invention and do not constitute any limitation on the scope of protection of the invention. Various improvements, equivalent substitutions, or modifications can be made to the technical content and embodiments of the present invention without departing from the spirit and scope of protection of the invention, and all such modifications fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A metallic copper skeleton / liquid metal composite thermal interface material, characterized in that, The liquid metal fills the pores of the copper skeleton, and the surface of the copper skeleton is provided with a chemically modified layer to prevent the liquid metal from directly contacting the copper skeleton.

2. The composite thermal interface material according to claim 1, characterized in that, Preferably, the porous copper skeleton has a three-dimensional interconnected pore structure.

3. The composite thermal interface material according to claim 1, characterized in that, The liquid metal alloy is a gallium-based alloy.

4. The composite thermal interface material according to claim 3, characterized in that, The gallium-based alloy is a gallium-indium alloy or a gallium-indium-tin alloy.

5. The composite thermal interface material according to claim 2, characterized in that, The chemically modified layer is a hydroxylated layer.

6. The composite thermal interface material according to claim 2, characterized in that, The chemically modified layer is a carboxylated layer.

7. The composite thermal interface material according to claim 2, characterized in that, The chemically modified layer is a self-assembled monolayer.

8. A method for preparing the composite thermal interface material according to any one of claims 1-7, characterized in that, The method includes: S1, Clean the surface of the copper skeleton; S2 forms a chemically modified layer on the cleaned copper skeleton surface; S3, liquid metal is filled into the pores of a copper skeleton with a chemically modified layer to obtain the composite thermal interface material.

9. The method according to claim 8, characterized in that, In S1, the surface cleaning includes sequential organic solvent cleaning, acid washing, and deionized water rinsing.

10. The application of the composite thermal interface material according to any one of claims 1-7 of the present invention in the thermal management of electronic devices.

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