High-heat-flux graphite-based heat conduction core material, preparation method thereof and solid-state vapor chamber

Abstract

The invention belongs to the technical field of graphite metal composite materials, and provides a high-heat-flux graphite-based heat conduction core material, a preparation method thereof and a solid temperature uniformizing plate, and the preparation method comprises the following steps: forming a plurality of micron-sized blind holes in the surface of a graphite film, and processing a plurality of through holes in the graphite film; sequentially depositing an active metal film and a heat-conducting metal film on the surface of the graphite film to obtain a coated graphite film; stacking and aligning a plurality of layers of coated graphite films, enabling the through holes in each layer to be communicated to form a plurality of channels, and filling metal powder in the channels to form a graphite-metal composite green body; and performing vacuum hot pressing to melt the metal powder to form a metal column penetrating through multiple layers, so as to obtain the graphite-based heat-conducting core material. The graphite-based composite material for the vapor chamber prepared by the method has the advantages of high thermal conductivity, high thermal conductivity, high mechanical strength and excellent weldability.

Description

Technical Field

[0001] This invention belongs to the field of graphite metal composite material technology, and relates to a high heat flux graphite-based thermally conductive core material, its preparation method, and a solid-state heat spreader. Background Technology

[0002] With the development of electronic information technology, electronic devices are evolving towards miniaturization, integration, and high power, making heat dissipation an increasingly prominent issue and placing ever higher demands on material performance. Traditional metallic materials have low thermal conductivity and high density, making it difficult to meet the requirements of high heat flux density. Graphite materials, due to their sp... 2 Hybrid structures can efficiently transport phonons and possess excellent in-plane thermal conductivity, making them among the materials with the highest known thermal conductivity. Graphite / metal composites combine high thermal conductivity and high strength and have been widely used in the aerospace field. These materials are mostly prepared using powder metallurgy processes. The process results in a lack of a complete graphite crystal structure and the presence of numerous graphite-metal interfaces, significantly increasing interfacial thermal resistance. Consequently, their in-plane thermal conductivity generally does not exceed 800 W / (m·K).

[0003] In recent years, high thermal conductivity graphite films have been industrialized. However, their extremely low longitudinal thermal conductivity and the difficulty in fabricating thick films limit overall heat flux, failing to meet practical heat dissipation requirements. Therefore, it is urgent to leverage their high in-plane thermal conductivity while addressing issues such as poor longitudinal thermal conductivity and difficulties in assembly along the thickness direction. Traditional liquid vapor chambers, relying on sintered core structures, are prone to structural collapse under repeated impacts and vibrations, leading to reduced heat dissipation performance. Furthermore, their heat transfer performance fails in anti-gravity environments, making them unsuitable for complex operating conditions. In contrast, solid-state heat transfer technology has no internal flow channels, eliminating issues such as medium degradation, corrosion, or changes in flow resistance. It boasts advantages such as high thermal conductivity, lightweight design, and good stability, and is widely used in thermal management of avionics, spaceborne equipment, optoelectronic systems, and radar systems.

[0004] To improve the performance of graphite-based materials in solid-state heat exchangers, existing technologies have been explored. For example, Chinese patent CN116507080B discloses a solid-state heat exchanger in which through holes are set on a heat-conducting plate and filled with metal pillars to connect to the shell. The metal pillars in the through holes connect the shell to enhance structural stability. However, the heat-conducting plate is a single-layer structure, and the metal pillars are only used for mechanical connection. No internal longitudinal heat conduction path is constructed, and multi-layer efficient heat conduction cannot be achieved.

[0005] Chinese patent CN116873909A discloses a method for preparing graphene plates, which involves rolling, high-temperature expansion, needle punching, and scratching of a graphene oxide film followed by multi-layer calendering. The needle punching and scratching are applied to the graphene oxide film, not the finished graphite film, primarily to provide air escape channels during the calendering process and to enhance interlayer friction. However, the material still relies mainly on in-plane heat conduction, lacking an effective longitudinal heat conduction mechanism; furthermore, the needle punches are small (typically <1 mm) and randomly distributed, mainly used for venting and anchoring, making it difficult to form continuous heat conduction pathways.

[0006] In summary, existing technologies still suffer from problems such as low longitudinal thermal conductivity, lack of a three-dimensional thermal conductive network, weak interlayer bonding, high interfacial thermal resistance, and limited functionality of through-holes. Therefore, there is an urgent need for a novel graphite-based thermally conductive core material and its preparation method that combines high in-plane thermal conductivity, strong longitudinal thermal conductivity, and high bonding strength to meet the application requirements of high heat flux solid-state vapor chambers. Summary of the Invention

[0007] To address the technical problems of low longitudinal thermal conductivity, weak interlayer bonding, and difficulty in achieving efficient three-dimensional heat conduction in existing graphite materials, this invention provides a method for preparing a high heat flux graphite-based thermally conductive core material. Specifically, the method includes the following steps: S1. Multiple micron-sized blind holes are formed on the surface of a graphite film, and multiple through holes are processed on the graphite film. The total projected area of ​​the through holes on the graphite film is 20% to 60% of the total area of ​​the graphite film, wherein the diameter of the micron-sized blind holes is smaller than the diameter of the through holes. S2. An active metal film and a thermally conductive metal film are sequentially deposited on the surface of the graphite film to obtain a coated graphite film. S3. Stack and align the multiple layers of the coated graphite film so that the through holes on each layer are connected to form multiple channels, and fill the channels with metal powder to form a graphite-metal composite green body. S4. Vacuum hot pressing is performed on the graphite-metal composite green blank to melt the metal powder and form a metal column that penetrates multiple layers, thereby obtaining a graphite-based thermally conductive core material.

[0008] The present invention also provides a high heat flux graphite-based thermally conductive core material, which is prepared by the above method. The high heat flux graphite-based thermally conductive core material includes a graphite film structure, a metal bonding interface and multiple metal pillars.

[0009] The graphite film structure is formed by stacking and hot-pressing multiple layers of graphite films, wherein each layer of graphite film has micron-sized blind holes on its surface; The metal bonding interface includes an active metal film and a thermally conductive metal film deposited sequentially between adjacent graphite films. The active metal film reacts with the surface of the graphite film to form a carbide interface layer to enhance interface anchoring. Each of the metal pillars is formed by hot-pressing molten metal powder within a channel of the graphite film structure, and each of the channels is perpendicular to the surface of the graphite film.

[0010] The present invention also provides a solid heat spreader, comprising a metal shell and a high heat flux graphite-based thermally conductive core material encapsulated therein. The two ends of the metal column are respectively connected to the top shell and the bottom shell of the metal shell to form a longitudinal heat conduction path. The metal shell and the thermally conductive core material are connected by a welding layer to enhance the welding connection strength.

[0011] This invention constructs a three-dimensional thermal conductivity network for a high-heat-flux graphite-based thermally conductive core material through the synergistic effect of "multi-scale structural design" and "functionally graded interface engineering." The core mechanism is as follows: 1. A multi-scale pore synergistic mechanism was constructed: Micron-level blind pores create an uneven film surface, increasing specific surface area. During hot pressing, the coating elements soften, forming a rivet structure between film layers, thus enhancing the mechanical strength of the composite material and creating mechanical interlocking, improving coating adhesion and interlayer bonding strength. Furthermore, large-projection-area through-holes serve as metal-filled areas, forming multi-layered metal pillars through hot pressing, constructing longitudinal heat conduction channels.

[0012] A multi-scale pore synergy mechanism is formed by micron-level blind holes and through holes. The functions of micron-level blind holes and through holes are clearly defined: the former is used for interface bonding, and the latter is used for heat conduction, thereby achieving the integration of structure and function.

[0013] 2. A double-layer coating interface strengthening mechanism was constructed: the active metal film (Ti film) reacts with graphite carbon during hot pressing to generate carbides such as TiC, forming a covalent bond interface, which significantly reduces the contact thermal resistance and improves the bonding strength; the thermally conductive metal film (such as Cu film) provides a high thermal conductivity path and forms a continuous metal connection with the subsequent filler metal and shell to ensure continuous heat flow.

[0014] 3. A three-dimensional heat conduction network formation mechanism was constructed: After stacking and aligning multiple layers of graphite films, the through holes of adjacent layers are connected to form multiple vertical channels. Metal powder is filled in the channels and densified by hot pressing and melting to form through metal pillars. At the same time, through diffusion and reaction between the coating, graphite and metal pillars, a metallurgical bond is formed, constructing transverse heat conduction paths, longitudinal heat conduction paths and low-resistance interface paths. The three work together to form an efficient three-dimensional heat conduction network.

[0015] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least: 1. By constructing a longitudinal heat conduction path through multiple metal pillars perpendicular to the graphite film surface, the equivalent thermal conductivity is significantly improved. The measured equivalent thermal conductivity of the product made by the method of this invention reaches 850~950 W / (m·K), which is more than 50% higher than that of the traditional method. 2. The interlayer bonding strength is enhanced by the synergistic effect of micron-sized blind pores and active metal film layers, resulting in an interlayer peel strength ≥75 gf / mm, effectively preventing delamination of multilayer structures; 3. Reduce interfacial thermal resistance: The covalent bonded interface (such as the TiC interface) and the thermally conductive metal interface (such as the Cu interface) are designed to reduce the interfacial contact thermal resistance by more than 40%. 4. High process feasibility: Positioning holes are set at the edge of the coated graphite film to achieve high-precision alignment of the through holes, and the axial deviation is controlled to be less than 0.1 mm, which ensures the continuity of the metal column and is suitable for mass production. In summary, the method of this invention is a liquid-free working fluid design, which expands high reliability and the resulting product is suitable for anti-gravity and high-vibration environments such as aerospace and spaceborne equipment. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the preparation method of the high heat flux graphite-based thermally conductive core material of the present invention. Detailed Implementation

[0018] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0019] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features of the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The drawings only show components related to this disclosure and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0021] This invention provides a method for preparing a high heat flux graphite-based thermally conductive core material, see [link to relevant documentation]. Figure 1 As shown, the method includes the following steps: S1. Multiple micron-sized blind holes are formed on the surface of a graphite film, and multiple through holes are processed on the graphite film. The total projected area of ​​the through holes on the graphite film is 20% to 60% of the total area of ​​the graphite film, wherein the diameter of the micron-sized blind holes is smaller than the diameter of the through holes. S2. An active metal film and a thermally conductive metal film are sequentially deposited on the surface of the graphite film to obtain a coated graphite film. S3. Stack and align the multiple layers of the coated graphite film so that the through holes on each layer are connected to form multiple channels, and fill the channels with metal powder to form a graphite-metal composite green body. S4. Vacuum hot pressing is performed on the graphite-metal composite green blank to melt the metal powder and form a metal column that penetrates multiple layers, thereby obtaining a graphite-based thermally conductive core material.

[0022] In one embodiment, the graphite film can be either a graphene thermal conductive film or an artificial graphite film. The graphene thermal conductive film is obtained by coating, carbonizing, graphitizing, and densifying graphene oxide slurry as raw material. The artificial graphite film is prepared based on polyimide film through carbonization, pressure graphitization, and calendering densification. The thickness of the graphite film is between 0.050 and 0.100 mm.

[0023] In one embodiment, the diameter of the micron-sized blind hole is much smaller than the diameter of the through hole.

[0024] In one embodiment, micron-sized blind holes with a diameter of 0.05~1.0 mm and a depth of 0.002~0.020 mm can be formed on the surface of the graphite film by means of needle punching, laser drilling, or chemical oxidation. When using chemical oxidation to form micron-sized blind holes, the chemical oxidation treatment parameters can be selected as follows: holding at a temperature within the range of 200~600℃ in air for 10~60 minutes. When using needle punching or laser drilling, the hole diameter and depth can be controlled by adjusting the needle tip thickness, the number of needle punches, and the laser strike frequency and number of strikes to ensure the hole size and depth.

[0025] In one embodiment, a graphite film of the required specifications can be cut using methods such as laser cutting, die cutting, and mold pressing, according to user needs. Then, multiple through holes are formed on the graphite film. The diameter of the through holes is 1 to 3 mm, and the total projected area of ​​the through holes in the graphite film is controlled to be 20% to 60% of the total area of ​​the graphite film.

[0026] In one embodiment, an active metal film and a thermally conductive metal film can be deposited on the surface of a graphite film using magnetron sputtering or chemical deposition. The active metal film is used to activate the carbon layer on the graphite film surface and improve the interlayer bonding force of the graphite. The thermally conductive metal film is used to effectively reduce the difference in the expansion coefficients between the carbon material and the shell metal material, optimizing the cycling stability of the solid-state heat spreader. The active metal film is relatively thin and mainly forms carbides, playing a role in activating the carbon layer; the thermally conductive metal film is relatively thick and mainly plays a role in bonding and fusion.

[0027] The active metal film is made of titanium, chromium, zirconium, molybdenum, or vanadium, either as an element or an alloy, with a thickness of 30-200 nm; the thermally conductive metal film is made of copper, aluminum, silver, or gold, either as an element or an alloy, with a thickness of 300-1000 nm. The total coating thickness is controlled between 500-1200 nm.

[0028] In one embodiment, the parameters for forming the metal column by vacuum hot pressing include: a vacuum hot pressing temperature of 500~900℃, a pressure of 5~20 MPa, a holding time of 20~90 minutes, and a vacuum degree greater than 10. -3 Pa·m / s. By forming metal pillars that can serve as longitudinal structural supports and longitudinal thermal conduction pathways in the product, the longitudinal thermal conductivity and longitudinal structural strength of the composite material can be greatly improved.

[0029] This invention constructs a three-dimensional thermal conductivity network for a high-heat-flux graphite-based thermally conductive core material through the synergistic effect of "multi-scale structural design" and "functionally graded interface engineering." The core mechanism is as follows: 1. A multi-scale pore synergistic mechanism was constructed: Micron-level blind pores create an uneven film surface, increasing specific surface area. During hot pressing, the coating elements soften, forming a rivet structure between film layers, thus enhancing the mechanical strength of the composite material and creating mechanical interlocking, improving coating adhesion and interlayer bonding strength. Furthermore, large-projection-area through-holes serve as metal-filled areas, forming multi-layered metal pillars through hot pressing, constructing longitudinal heat conduction channels.

[0030] A multi-scale pore synergy mechanism is formed by micron-level blind holes and through holes. The functions of micron-level blind holes and through holes are clearly defined: the former is used for interface bonding, and the latter is used for heat conduction, thereby achieving the integration of structure and function.

[0031] 2. A double-layer coating interface strengthening mechanism was constructed: the active metal film (Ti film) reacts with graphite carbon during hot pressing to generate carbides such as TiC, forming a covalent bond interface, which significantly reduces the contact thermal resistance and improves the bonding strength; the thermally conductive metal film (such as Cu film) provides a high thermal conductivity path and forms a continuous metal connection with the subsequent filler metal and shell to ensure continuous heat flow.

[0032] 3. A three-dimensional heat conduction network formation mechanism was constructed: After stacking and aligning multiple layers of graphite films, the through holes of adjacent layers are connected to form multiple vertical channels. Metal powder is filled in the channels and densified by hot pressing and melting to form through metal pillars. At the same time, through diffusion and reaction between the coating, graphite and metal pillars, a metallurgical bond is formed, constructing transverse heat conduction paths, longitudinal heat conduction paths and low-resistance interface paths. The three work together to form an efficient three-dimensional heat conduction network.

[0033] Tests showed that the high heat flux graphite-based thermally conductive core material prepared by the method of this invention has a density of 2.1~2.6 g / cm³. 3 The transverse thermal conductivity reaches 1300 W / (m·K), and the equivalent thermal conductivity can reach 900 W / (m·K). In addition, the fabricated high heat flux graphite-based thermally conductive core material includes a graphite film structure, a metal bonding interface, and multiple metal pillars.

[0034] The graphite film structure is formed by stacking and hot-pressing multiple layers of graphite films, wherein each layer of graphite film has micron-sized blind holes on its surface; The metal bonding interface includes an active metal film and a thermally conductive metal film deposited sequentially between adjacent graphite films. The active metal film reacts with the surface of the graphite film to form a carbide interface layer to enhance interface anchoring. Each of the metal pillars is formed by hot-pressing molten metal powder within a channel of the graphite film structure, and each of the channels is perpendicular to the surface of the graphite film.

[0035] In one embodiment, the high heat flux graphite-based thermally conductive core material is encapsulated within a metal casing made of aluminum or copper by diffusion welding or brazing.

[0036] The present invention also provides a solid heat spreader, comprising a metal shell and a high heat flux graphite-based thermally conductive core material encapsulated therein. The two ends of the metal column are respectively connected to the top shell and the bottom shell of the metal shell to form a longitudinal heat conduction path. The metal shell and the thermally conductive core material are connected by a welding layer to enhance the welding connection strength.

[0037] This specific embodiment uses Examples 1 to 5 and Comparative Examples 1 to 3 to illustrate the advantages of the solid-state heat spreader prepared in this invention: Example 1: Step 1: Clean the surface of a graphite film with a thickness of 0.080 mm with alcohol or acetone. After cleaning, roughen the surface in an air atmosphere to form multiple micron-sized blind holes. The temperature is 200℃ and the treatment time is 40 min.

[0038] Step 2: Use laser cutting to form multiple through holes on the graphite film, with a total projected area of ​​28% of the total area of ​​the graphite film and a diameter of 1.5mm.

[0039] Step 3: The surface-active titanium film and the thermally conductive copper film are formed by magnetron sputtering, with the thicknesses of the titanium film and the copper film being 50 nm and 500 nm, respectively.

[0040] Step 4: Stack multiple layers of graphite film, ensuring that the through holes between adjacent layers are aligned and connected to form a vertical channel extending from the first layer to the last layer, the channel being perpendicular to the surface of the graphite film; then fill each channel with pure aluminum metal powder and compact it to obtain a graphite-metal composite green body.

[0041] Step 5: Hot-press the graphite-metal composite green body to obtain a high heat flux graphite-based thermally conductive core material. The vacuum hot-pressing temperature is 800℃, the pressure is 10MPa, the holding time is 30min, and the vacuum degree is better than 10. -3 Pa·m / s; Step 6: The high heat flux graphite-based thermally conductive core material is encapsulated in a metal shell using brazing and diffusion welding processes to obtain a solid-state heat spreader.

[0042] Example 2: The difference between Example 2 and Example 1 is as follows: the thickness of the graphite film is 0.040 mm; the roughening treatment temperature in air atmosphere is 400℃ and the time is 15 min; the total projected area of ​​the through holes is 35% of the total area of ​​the graphite film, and the diameter of the through holes is 2 mm; the surface-active metal film is a chromium film with a thickness of 40 nm; the thermally conductive metal film is a copper film with a thickness of 700 nm; the vacuum hot pressing temperature is 750℃, the pressure is 5 MPa, and the holding time is 40 min.

[0043] Example 3: The difference between Example 3 and Example 1 is as follows: the thickness of the graphite film is 0.100 mm; the surface roughening treatment is performed by laser ablation, the diameter of the blind holes is 0.100 mm, and the depth is 0.010 mm; the total projected area of ​​the through holes is 30% of the total area of ​​the graphite film, and the diameter of the through holes is 2 mm; the surface active metal film is a titanium film with a thickness of 80 nm; the thermally conductive metal film is a silver film with a thickness of 650 nm; the vacuum pressure temperature is 800℃, the pressure is 10 MPa, and the holding time is 40 min.

[0044] Example 4: The difference between Example 4 and Example 1 is as follows: the thickness of the graphite film is 0.050 mm; the roughening treatment temperature in air atmosphere is 400℃ and the time is 15 min; the total projected area of ​​the through holes is 60% of the total area of ​​the graphite film, and the diameter of the through holes is 1.5 mm; the surface active metal film is a chromium film with a thickness of 100 nm; the surface active metal film is a silver film with a thickness of 700 nm; the vacuum hot pressing temperature is 600℃, the pressure is 20 MPa, and the holding time is 600 min.

[0045] Example 5: The difference between Example 5 and Example 1 is as follows: the thickness of the graphite film is 0.080 mm; the surface roughening treatment is performed by laser ablation, the diameter of the blind holes is 0.300 mm, and the depth is 0.010 mm; the total projected area of ​​the through holes is 50% of the total area of ​​the graphite film, and the diameter of the through holes is 2 mm; the surface active metal film is a vanadium film with a thickness of 150 nm; the surface active metal film is a gold film with a thickness of 600 nm; the vacuum hot pressing temperature is 800℃, the pressure is 10 MPa, and the holding time is 600 min.

[0046] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that no surface coating treatment was performed.

[0047] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that no through-holes were formed on the graphite film, that is, there were no metal pillars in the prepared solid temperature plate.

[0048] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that no micron-sized blind holes were prepared on the graphite film.

[0049] For the solid-state vapor chambers prepared by Examples 1 to 5 and Comparative Examples 1 to 3 above, the material density, thermal conductivity, and mechanical strength were tested, and the test results are shown in Table 1 below: Table 1: Performance Test Table of Solid Temperature Coefficient Plate

[0050] The in-plane thermal conductivity was tested using a Netzsch LFA467 laser scintillation method, and the test sample was a hot-pressed graphite composite material. The equivalent thermal conductivity was obtained by directly testing the temperature difference, and a copper block of the same size was used as a standard sample for conversion. The peel strength was the force required to peel a sample with a peel width of 20 mm, and the test method referred to GB / T 2792-2014.

[0051] It is particularly important to note that the laser scintillation method is inaccurate for testing macroscopic metal columns with a longitudinal distribution. Therefore, this invention utilizes the Fourier transform principle to calculate the equivalent thermal conductivity of the sample by comparing it with the uniform temperature performance of copper blocks of the same size. The equivalent thermal conductivity reflects the overall heat dissipation performance of the sample and is a data point combining in-plane thermal conductivity and longitudinal thermal conductivity. This invention uses similar graphite films with the same in-plane thermal conductivity; therefore, the equivalent thermal conductivity can also simultaneously reflect the level of the sample's longitudinal thermal conductivity.

[0052] As shown in Table 1, the in-plane thermal conductivity of the examples and the comparative examples is similar. This is mainly because the in-plane thermal conductivity is primarily provided by the high thermal conductivity graphite film. Secondly, comparing the equivalent thermal conductivity and peel strength of the examples and the comparative examples, it is evident that the adhesion between graphite layers is mainly affected by the coating metal and the surface roughening treatment. The equivalent thermal conductivity is related to the coating metal, the internal metal pillars, and the surface roughening treatment process, and is highly correlated with the internal structural design. Furthermore, comparing the examples shows that the internal structural design, coating elements, and thickness all have a significant impact on the performance of the solid-state vapor chamber.

[0053] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least: 1. By constructing a longitudinal heat conduction path through multiple metal pillars perpendicular to the graphite film surface, the equivalent thermal conductivity is significantly improved. The measured equivalent thermal conductivity of the product made by the method of this invention reaches 850~950 W / (m·K), which is more than 50% higher than that of the traditional method. 2. The interlayer bonding strength is enhanced by the synergistic effect of micron-sized blind pores and active metal film layers, resulting in an interlayer peel strength ≥75 gf / mm, effectively preventing delamination of multilayer structures; 3. Reduce interfacial thermal resistance: The covalent bonded interface (such as the TiC interface) and the thermally conductive metal interface (such as the Cu interface) are designed to reduce the interfacial contact thermal resistance by more than 40%. 4. High process feasibility: Positioning holes are set at the edge of the coated graphite film to achieve high-precision alignment of the through holes, and the axial deviation is controlled to be less than 0.1 mm, which ensures the continuity of the metal column and is suitable for mass production. In summary, the method of this invention is a liquid-free working fluid design, which expands high reliability and the resulting product is suitable for anti-gravity and high-vibration environments such as aerospace and spaceborne equipment.

[0054] Obviously, those skilled in the art should understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Various modifications and variations of the embodiments of the present invention are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0055] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for producing a high heat flux graphite-based thermally conductive core material, characterized by, The application relates to a high-heat-flux graphite-based heat-conducting core material. A plurality of micrometer-level blind holes are formed on the surface of a graphite film, and a plurality of through holes are processed on the graphite film, the total projection area of the through holes on the graphite film being 20-60% of the total area of the graphite film, wherein the diameter of the micrometer-level blind holes is smaller than the diameter of the through holes; An active metal film and a heat-conductive metal film are sequentially deposited on the surface of the graphite film to obtain a plated graphite film; The plurality of layers of the plated graphite film are stacked and aligned, the through holes on the layers are connected to form a plurality of channels, and the channels are filled with metal powder to form a graphite-metal composite green body; The graphite-metal composite green body is subjected to vacuum hot pressing, the metal powder is melted to form metal columns penetrating through the plurality of layers, and a graphite-based heat-conducting core material is obtained.

2. The method of producing a high heat flux graphite-based thermally conductive core material according to claim 1, characterized by, Micrometer-level blind holes with a diameter of 0.05-1.00 mm and a depth of 0.002-0.020 mm are formed on the surface of the graphite film by needling, laser drilling or chemical oxidation.

3. The production method of a high heat flux graphite-based thermally conductive core material according to claim 1 or 2, characterized by, The diameter of the through holes is 1-3 mm.

4. The method of claim 1, wherein the high heat flux graphite-based thermally conductive core material is prepared by the steps of: The active metal film is an element or an alloy of titanium, chromium, zirconium, molybdenum or vanadium, and the thickness is 30-200 nm; the heat-conductive metal film is an element or an alloy of copper, aluminum, silver or gold, and the thickness is 300-1000 nm. ​ 5. The method for preparing the high heat flux graphite-based thermally conductive core material according to claim 1, characterized in that, Positioning holes are arranged at the edges of each layer of the plated graphite film, the through holes of the plurality of layers of the plated graphite film are aligned based on the positioning holes, and the through holes are connected to form a plurality of channels perpendicular to the surface of the graphite film.

6. The method for preparing the high heat flux graphite-based thermally conductive core material according to claim 1, characterized in that, The metal powder is selected from copper powder or aluminum powder, and the particle size of the metal powder is 10-50 microns.

7. The method for preparing the high heat flux graphite-based thermally conductive core material according to claim 1, characterized in that, The parameters of vacuum hot pressing include: vacuum hot pressing temperature of 500-900℃, pressure of 5-20 MPa, holding time of 20-90 minutes, and vacuum degree greater than 10 -3 Pa·m / s.

8. A high heat flux graphite-based thermally conductive core material produced by the method of any one of claims 1 to 7, characterized by, The high-heat-flux graphite-based heat-conducting core material comprises: A graphite film structure formed by stacking and hot pressing a plurality of layers of graphite films, wherein each layer of the graphite film is provided with micrometer-level blind holes on the surface; A metal bonding interface comprising an active metal film and a heat-conductive metal film sequentially deposited between adjacent graphite films, the active metal film reacts with the surface of the graphite film to form a carbide interface layer to enhance the interface anchoring; A plurality of metal columns, each of which is formed by hot pressing and melting metal powder in a channel of the graphite film structure, and each of the channels is perpendicular to the surface of the graphite film.

9. A solid state heat spreader, characterized by, The high-heat-flux graphite-based heat-conducting core material is packaged in a metal shell made of aluminum or copper by diffusion welding or brazing.

10. The solid-state heat spreader of claim 9, wherein, The high-heat-flux graphite-based heat-conducting core material is packaged in a metal shell made of aluminum or copper by diffusion welding or brazing.

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