A vapor chamber liquid-absorbing core structure and its preparation method

Abstract

This invention provides a vapor chamber wick structure and its fabrication method, relating to the technical field of heat dissipation structures. The vapor chamber wick structure includes a substrate, on which a primary micropillar array structure composed of multiple equally spaced micropillar structures is disposed; the upper surface of the micropillar structure is provided with a secondary micropit array structure composed of multiple equally spaced micropit structures; and the substrate is covered with a cluster of nanoneedles. This invention solves the problems of poor boiling heat transfer performance, poor liquid transport and gas-liquid separation, and difficulty in fabricating micro / nano structures in traditional vapor chamber wicks.

Description

Technical Field

[0001] This invention relates to the technical field of heat dissipation structures, and more specifically, to a vapor chamber liquid-absorbing core structure and its preparation method. Background Technology

[0002] A vapor chamber is a highly efficient passive heat transfer device that achieves heat exchange through latent heat of phase change. Its evaporation end undergoes boiling at high heat flux, generating a large amount of latent heat that can carry away significant amounts of heat. This makes it one of the ideal heat dissipation methods for high power density electronic devices. The efficient heat dissipation capability of boiling can meet the thermal management requirements of high heat flux devices, such as photovoltaic cells, fast-charging batteries, data centers, and integrated electronic devices.

[0003] The continued growth in energy demand has led to increasing emphasis on achieving higher boiling performance enhancements. Existing methods for enhancing boiling heat transfer at the evaporator end of steam chambers focus on increasing the critical heat flux (CHF) and heat transfer coefficient (HTC). When the CHF is reached, the device surface is covered by a gas film (film boiling). Due to the high thermal resistance of the gas film, the surface temperature rises sharply, causing the device to burn out.

[0004] Existing evaporator end capillary structure designs are relatively simple, and most can only improve CHF or HTC in one aspect. Structures with high nucleation site density may increase HTC, but will reduce CHF. Structures that enhance capillary force can effectively delay the occurrence of CHF, but it is difficult to balance the efficiency of HTC.

[0005] In terms of improving boiling performance, high critical heat flux (CHF) requires the surface structure to have high wettability to delay the formation of vapor film, while high heat transfer coefficient (HTC) requires the surface to have a large number of vaporization nuclei to promote bubble generation. However, there is an inherent contradiction between improving surface wettability and increasing the number of vaporization nuclei - traditional structural designs often cannot achieve both. Summary of the Invention

[0006] The problem addressed by this invention is how to resolve the inherent contradiction between improving the surface wettability of the liquid suction core in a traditional steam chamber and increasing the number of vaporization cores.

[0007] In a first aspect, the present invention provides a vapor chamber liquid-absorbing core structure, comprising a substrate, wherein a primary micropillar array structure composed of multiple equally spaced micropillar structures is provided on the substrate, and a secondary micropit array structure composed of multiple equally spaced micropit structures is provided on the upper surface of the micropillar structure; the substrate is covered with a nanoneedle cluster structure.

[0008] Optionally, the cross-section of the micropillar structure is an isosceles trapezoid, with both the upper and lower bases being squares; the width of the lower base of the micropillar structure is 350 to 550 μm.

[0009] Optionally, the primary array micropillar structures are V-shaped grooves; the width of the V-shaped groove is 50 to 100 μm, and the ratio of the height to the width of the V-shaped groove is 1.5 to 2.

[0010] Optionally, the depth of the micropit structure is 30 to 50 μm, and the diameter of the top surface of the micropit structure is 10 to 30 μm.

[0011] Optionally, the average length of the needle-like structure of the nanoneedle cluster is 260 to 300 nm, the average width is 30 to 60 nm, and the thickness is 0.4 to 1.2 μm.

[0012] Secondly, the present invention provides a method for preparing the above-mentioned vapor chamber liquid-absorbing core structure, comprising the following steps:

[0013] S1: The optical path of the femtosecond laser is adjusted to an infrared femtosecond laser, and a line-by-line scanning path with vertical intersecting lines is used to etch micropillar structures of the same size and spacing on the surface of the substrate; then, the optical path of the femtosecond laser is adjusted to an ultraviolet femtosecond laser, and a regular micro-pit structure is etched on the top surface of the micropillar structure with a circular scanning path.

[0014] S2: A nanoneedle cluster structure was modified on the substrate by boiling water treatment.

[0015] Optionally, in step S1, the wavelength of the infrared femtosecond laser is 1020 to 1040 nm, the average laser power is 32 to 38 W, the scanning speed is 950 to 1050 mm / s, and the repetition frequency is 380 to 430 kHz.

[0016] Optionally, in step S1, the wavelength of the ultraviolet femtosecond laser is 340 to 360 nm, the average laser power is 2.8 to 3.2 W, the scanning speed is 380 to 420 mm / s, and the repetition frequency is 180 to 220 kHz.

[0017] Optionally, in step S2, the boiling water treatment time is 160 to 200 minutes, and the boiling water temperature is 140 to 160°C.

[0018] Optionally, in step S1, the cross-section of the etched micropillar structure is an isosceles trapezoid, with both the upper and lower bases being squares; the width of the lower base of the micropillar structure is 350 to 550 μm; the depth of the etched micropit structure is 30 to 50 μm, and the diameter of the top surface of the micropit structure is 10 to 30 μm; in step S1, an infrared femtosecond laser etches V-grooves between adjacent micropillar structures; wherein the width of the V-groove is 50 to 100 μm, and the ratio of the height to the width of the V-groove is 1.5 to 2; the average length of the needle-like structure of the nanoneedle cluster is 260 to 300 nm, the average width is 30 to 60 nm, and the thickness ranges from 0.4 to 1.2 μm.

[0019] The beneficial effects of the vapor chamber liquid-absorbing core structure and its preparation method of the present invention are as follows: A hierarchical integrated design is achieved by combining a primary micropillar array structure, a secondary micropit array structure, and a nanoneedle cluster structure. The primary micropillar array structure forms a spatial skeleton and creates V-shaped groove channels between the pillars, serving as the main capillary liquid replenishment path and supporting continuous liquid supply. The regularly arranged secondary micropit array structure on the top surface of the primary micropillar array structure provides a high-density vaporization core, promoting bubble initiation at lower superheat. The nanoneedle cluster structure covering the secondary micropit array structure and the V-shaped grooves further expands the channel area of ​​the capillary-driven liquid, while increasing the thin liquid film evaporation area and improving latent heat transfer efficiency. During boiling, larger bubbles generated at the bottom of the V-shaped grooves detach first, possessing higher buoyancy and inertia, and can engulf smaller bubbles that have not yet grown or remain in the micropits, thus forming a bubble collaborative detachment mechanism, significantly improving the bubble discharge rate and avoiding surface dry spots and vapor film coverage. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a vapor chamber liquid suction core structure according to the present invention.

[0021] Figure 2 A schematic diagram illustrating how the liquid-absorbing core structure at the middle evaporation end regulates the dynamic process of boiling bubbles.

[0022] Figure 3 for Figure 1 A partial side view of region A in the middle.

[0023] Figure 4 This is a flowchart illustrating a method for preparing a vapor chamber liquid-absorbing core structure according to the present invention.

[0024] Figure 5 A schematic diagram of the preset scanning path for laser texture.

[0025] Figure 6 This is a surface morphology diagram of the liquid-absorbing core structure and a schematic diagram of the underwater gas contact angle.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Substrate; 2. Primary array micropillar structure; 3. V-groove; 4. Secondary array structure of micropits; 5. Tertiary structure of nanoneedle clusters; 6. Detached bubbles generated by the V-groove; 7. Bubbles generated by the secondary array structure of micropits; 8. Secondary liquid supply path; 9. Primary liquid supply path. Detailed Implementation

[0028] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0029] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this invention's description is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0030] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0031] In related technologies, a Chinese invention patent discloses a microscale synergistic surface structure for enhancing boiling heat transfer (application number 201910241520.4). In this structure, the substrate surface is divided into large grooves, small grooves, and connecting grooves by ribs. The small grooves are modified with a low surface energy superhydrophobic coating of fluoropolymer to achieve the purpose of generating vaporization nuclei at a lower superheat. However, the structure of this groove is of uniform cross-section in the vertical direction, which is not conducive to the vertical rise and detachment of bubbles. Furthermore, this non-covalent bond adsorption bonding method results in poor coating adhesion, making it susceptible to water erosion or mechanical friction damage, and prone to failure in harsh environments such as aerospace.

[0032] A Chinese invention patent discloses a non-uniform fractal micro-pit structure and a superhydrophilic composite surface for enhancing boiling heat transfer (application number 202411528872.5). The micro-pit structure is etched by nanosecond laser to provide a large number of vaporization nuclei, and the etching is performed by chemical solutions of NaClO2, NaOH, and Na3PO4. However, the method is dangerous and environmentally polluting, and the resulting nanostructure has weak capillary force, which cannot significantly improve CHF.

[0033] Chinese invention patent discloses a micro / nano multi-scale structure for surface-enhanced boiling heat transfer and its manufacturing method (application number 202210582471.2). It achieves efficient cooling liquid replenishment by combining micro-protrusion units with nanostructures. Although this design is beneficial to delay the occurrence of critical heat flux density, it cannot guarantee the formation of a large number of vaporization nuclei in the early stage of boiling, thus failing to achieve a high heat transfer coefficient in the boiling stage.

[0034] Therefore, designing surface micro / nano structures capable of controlling the dynamic behavior of boiling bubbles to form dense vaporization nuclei at low heat flux densities while effectively delaying bubble film formation to improve heat transfer flux (CHF) at high heat flux densities has become a key challenge in the design and manufacturing of boiling surface structures. Meanwhile, in terms of structure fabrication, existing processing methods for improving boiling heat transfer performance have significant shortcomings: for example, template-based methods involve cumbersome steps (such as photolithography and electroforming), making large-scale commercial production difficult; while chemical methods, due to the use of highly corrosive reagents, pose environmental pollution and safety risks.

[0035] To address the problems existing in the aforementioned related technologies, embodiments of the present invention provide a vapor chamber liquid suction core structure and its preparation method.

[0036] like Figures 1 to 3 As shown, an embodiment of the present invention provides a vapor chamber liquid absorption core structure, comprising: a substrate 1, on which a primary micropillar array structure composed of multiple equally spaced micropillar structures 2 is provided, and a secondary micropit array structure composed of multiple equally spaced micropit structures 4 is provided on the upper surface of the micropillar structures 2; and a nanoneedle cluster structure 5 is covered on the substrate 1.

[0037] The substrate 1 is made of pure aluminum or aluminum alloy, with a maximum substrate size range of 150mm*150mm.

[0038] In this embodiment, a combination of a primary micropillar array structure, a secondary micropit array structure, and a nanoneedle cluster structure is employed. This multi-level structural design provides rich surface morphology and functional properties. The primary micropillar array structure increases the surface area, improving the liquid's adsorption and transport capabilities. The secondary micropit array structure provides numerous vaporization nuclei, which facilitates bubble generation at low heat flux densities, thereby increasing the heat transfer coefficient (HTC). The abundant nanoneedle cluster structure forms secondary liquid replenishment channels 8, while simultaneously expanding the thin liquid film evaporation area, thus increasing the critical heat flux density (CHF) and effectively balancing the improvement of HTC and CHF. The substrate 1 is made of pure aluminum or aluminum alloy, which has excellent thermal conductivity, enabling rapid heat transfer from the heat source to the wick structure and improving heat dissipation efficiency. Furthermore, aluminum and aluminum alloys offer advantages such as light weight, high strength, and corrosion resistance, making them suitable for various applications, especially in fields with high requirements for weight and reliability, such as aerospace.

[0039] Optionally, such as Figure 3 As shown, the cross-section (perpendicular to the substrate direction) of the micropillar structure 2 is an isosceles trapezoid, with both the upper and lower bases (i.e., the two opposite faces of the micropillar structure 2 parallel to the substrate) being squares. The width W3 of the lower base of the micropillar structure 2 is 350 to 550 μm. A V-groove 3 is formed between adjacent micropillar structures 2; the width W1 of the V-groove 3 is 50 to 100 μm, and the ratio H1 of the height H1 to the width W1 of the V-groove 3, H1 / W1, is 1.5 to 2.

[0040] In this embodiment, the width of the micropillar structure 2 can ensure structural strength and increase specific surface area, thereby enhancing liquid absorption and heat transfer capabilities. The V-shaped groove 5 formed between the micropillar structures 2 can form the main liquid replenishment channel 9. The width of the V-shaped groove 5 is conducive to rapid liquid transport and gas-liquid exchange, while the ratio of height to width can reasonably store liquid and optimize the bubble detachment path.

[0041] Optionally, the depth H2 of the micropit structure 4 is 30 to 50 μm, and the top diameter W2 of the micropit structure 4 is 10 to 30 μm.

[0042] Optionally, the needle-like structure 5 has an average length of 260 to 300 nm, an average width of 30 to 60 nm, and a thickness of 0.4 to 1.2 μm.

[0043] In this embodiment, the depth of the micro-pit structure 4 can stabilize the gas-liquid interface and promote the formation of vaporization nuclei under low heat flux density. The size of the top surface diameter can increase the micro-pit density and bubble generation frequency. The dimensions of each part cooperate with each other to achieve efficient heat transfer and heat dissipation performance.

[0044] Since the heat flow first reaches the bottom of the V-groove 3, when the bubbles 7 generated by the micro-pit structure 4 begin to grow, the detached bubbles 6 generated by the V-groove 3 are much larger than the bubbles 7 generated by the micro-pit structure 4. Due to the coordinated detachment mechanism of the bubbles, the detached bubbles 6 have higher buoyancy and inertia. During the upward process, they will swallow up the small bubbles 7 that have not yet grown or are stuck in the micro-pit, thereby driving the small bubbles 7 to detach from the surface more quickly. This helps to quickly remove the bubbles on the heated surface and avoid local dry spots.

[0045] In the vapor chamber liquid wick structure, the nanoneedle cluster structure forms a secondary liquid replenishment channel 8, and the V-groove 5 can form a main liquid replenishment channel 9. The liquid can flow in the above channels. The secondary liquid supply path 8 and the main liquid supply path 9 cooperate to rewet the surface, forming gas channels and liquid channels that do not affect each other during the boiling heat transfer process. This effectively solves the liquid replenishment obstacle caused by bubble blockage in the traditional structure, improves the structure's resistance to dry spots and film state, significantly delays the triggering of CHF, and can greatly improve the overall boiling phase change heat transfer performance.

[0046] like Figure 4 and 5 As shown, an embodiment of the present invention provides a method for preparing a vapor chamber liquid-absorbing core structure, comprising the following steps:

[0047] S1: The optical path of the femtosecond laser is adjusted to an infrared femtosecond laser, and a line-by-line scanning path with vertical intersecting lines is used to etch micropillar structures 2 of the same size and spacing on the surface of the substrate 1; then, the optical path of the femtosecond laser is adjusted to an ultraviolet femtosecond laser, and a regular micro-pit structure 4 is etched on the top surface of the micropillar structure 2 with a circular scanning path.

[0048] S2: Nanoneedle clusters were modified on substrate 1 by boiling water treatment.

[0049] In this embodiment, the femtosecond laser includes dual paths of infrared and ultraviolet femtosecond lasers, with a pulse width of 218 fs-5 ps. It enables one-click switching between the infrared and ultraviolet femtosecond dual-path systems, eliminating the need for secondary dimming and replacement of the sample to be processed, thus improving processing efficiency. Infrared femtosecond lasers offer advantages such as high power and high efficiency, making them suitable for rapid etching of large-area micropillar structures, such as... Figure 5As shown, infrared femtosecond lasers etch micropillar structures by scanning the substrate line by line along horizontal and vertical straight lines with perpendicular intersections. Ultraviolet femtosecond lasers can achieve sub-micron level precision morphology control, and can further fabricate finer micro-pit structures on the top surface of the micropillar structures, such as... Figure 5 As shown, a femtosecond ultraviolet laser etches micropits along a circular path on the top surface of the micropillar structure. The femtosecond laser's narrow pulse width and high peak power allow for precise control of structural parameters, and the etching path is clear and easy to operate. Subsequent environmentally friendly boiling water treatment induces the formation of needle-like boehmite crystals on the microstructure surface due to the adsorption of Al-O atoms by the dense Al atoms on the aluminum surface, resulting in a highly capillary nanoneedle cluster structure. This nanoneedle cluster structure can be modified simply through boiling water treatment, without the need for corrosive chemicals. The process is simple and efficient, significantly improving production efficiency, reducing costs, and possessing industrial scalability.

[0050] Optionally, in step S1, the wavelength of the infrared femtosecond laser is 1000 to 1060 nm, the average laser power is 32 to 38 W, the scanning speed is 950 to 1050 mm / s, and the repetition frequency is 380 to 430 kHz.

[0051] Preferably, the infrared femtosecond laser has a wavelength of 1030nm, an average laser power of 35W, a scanning speed of 1000mm / s, and a repetition frequency of 400kHz.

[0052] Optionally, in step S1, the wavelength of the ultraviolet femtosecond laser is 340 to 360 nm, the average laser power is 2.8 to 3.2 W, the scanning speed is 380 to 420 mm / s, and the repetition frequency is 180 to 220 kHz.

[0053] Preferably, the wavelength of the ultraviolet femtosecond laser is 355nm, the average laser power is 3W, the scanning speed is 400mm / s, and the repetition frequency is 200kHz.

[0054] Optionally, in step S2, the boiling water treatment time is 160 to 200 minutes, and the boiling water temperature is 140 to 160°C.

[0055] Preferably, the boiling water treatment time is 180 min and the boiling water temperature is 150℃.

[0056] In this embodiment, the aforementioned parameters are carefully designed and play a crucial role in the quality and efficiency of the vapor chamber wick structure fabrication. Within this parameter range, infrared femtosecond lasers can efficiently etch micropillar structures onto the substrate, and optimized parameters can further improve the dimensional accuracy and surface quality of the micropillar structures. Within this parameter range, ultraviolet femtosecond lasers can finely process micro-pit structures on the top surface of the micropillar structures, and optimized values ​​can make the micro-pit structures more uniformly distributed and more regularly shaped. Within this parameter range, boiling water treatment can create suitable conditions for the modification of nanoneedle cluster structures, ensuring their full growth. Optimized parameters can further optimize the nanoneedle cluster structure and enhance the boiling heat transfer performance of the wick.

[0057] Optionally, in step S1, the cross-section (the cross-section perpendicular to the substrate direction) of the etched micropillar structure 2 is an isosceles trapezoid, and the upper and lower base surfaces (i.e., the two opposite surfaces of the micropillar structure 2 that are parallel to the substrate) are both squares. The width of the lower base surface of the micropillar structure 2 is 350 to 550 μm; the depth of the etched micropit structure is 30 to 50 μm, and the diameter of the top surface of the micropit structure is 10 to 30 μm.

[0058] Optionally, in step S1, an infrared femtosecond laser etches a V-groove between adjacent micropillar structures 2; wherein the width of the V-groove is 50 to 100 μm, and the ratio of the height to the width of the V-groove is 1.5 to 2.

[0059] In this embodiment, the above parameters achieve a balance between the density of the vaporization core and the liquid replenishment capacity in boiling heat transfer, while also taking into account processing efficiency and structural reliability, providing an ideal solution for high-performance vapor chamber liquid suction cores.

[0060] The present invention will be further described below with reference to specific embodiments.

[0061] Example 1

[0062] like Figure 6 As shown, in a contact angle test of the vapor chamber liquid-absorbing core structure of the present invention, the sample is placed in deionized water with the structured side facing vertically downwards. 5 μL of air is injected into the water below the sample using a syringe. The contact angle obtained by the contact between the air bubble generated by the syringe and the surface structure is the underwater gas contact angle.

[0063] The test results show that the underwater gas contact angle (CA = 153°) is relatively large, indicating that the surface of the wick structure has good gas-repellency. During boiling heat transfer, this gas-repellency facilitates the rapid detachment of gas (vapor bubbles) from the surface, reduces the adhesion time of bubbles on the surface, and prevents gas from accumulating on the surface to form a gas film, thereby preventing heat transfer deterioration and increasing the critical heat flux (CHF).

[0064] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A vapor chamber liquid-absorbing core structure, characterized in that, The substrate (1) is provided with a primary micropillar array structure composed of multiple equally spaced micropillar structures (2), and the upper surface of the micropillar structure (2) is provided with a secondary micropit array structure composed of multiple equally spaced micropit structures (4); the substrate (1) is covered with a nanoneedle cluster structure (5). The micropillar structures (2) are connected by V-grooves (3); the width of the V-grooves (3) is 50 to 100 μm, and the ratio of the height to the width of the V-grooves (3) is 1.5 to 2. The depth of the micro-pit structure (4) is 30 to 50 μm, and the diameter of the top surface of the micro-pit structure (4) is 10 to 30 μm; During the boiling process, the bubbles generated at the bottom of the V-shaped groove (3) detach first, possessing buoyancy and inertia, and can engulf bubbles that have not yet grown or remain in the micro-pit structure (4), thereby forming a bubble detachment mechanism, improving the bubble discharge rate, and avoiding surface dry spots and vapor film coverage.

2. The vapor chamber liquid suction core structure according to claim 1, characterized in that, The cross-section of the micro-pillar structure (2) is an isosceles trapezoid, with both the upper and lower bases being squares; the width of the lower base of the micro-pillar structure (2) is 350 to 550 μm.

3. The vapor chamber liquid suction core structure according to claim 1, characterized in that, The average length of the needle-like structure of the nanoneedle cluster (5) is 260 to 300 nm, the average width is 30 to 60 nm, and the thickness is 0.4 to 1.2 μm.

4. A method for preparing a vapor chamber liquid-absorbing core structure according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1: The optical path of the femtosecond laser is adjusted to an infrared femtosecond laser, and a line-by-line scanning path with vertical intersecting lines is used to etch micropillar structures of the same size and spacing on the surface of the substrate; then, the optical path of the femtosecond laser is adjusted to an ultraviolet femtosecond laser, and a regular micro-pit structure is etched on the top surface of the micropillar structure with a circular scanning path. S2: A nanoneedle cluster structure was modified on the substrate by boiling water treatment.

5. The method for preparing the vapor chamber liquid-absorbing core structure according to claim 4, characterized in that, In step S1, the wavelength of the infrared femtosecond laser is 1020 to 1040 nm, the average laser power is 32 to 38 W, the scanning speed is 950 to 1050 mm / s, and the repetition frequency is 380 to 430 kHz.

6. The method for preparing the vapor chamber liquid-absorbing core structure according to claim 4, characterized in that, In step S1, the wavelength of the ultraviolet femtosecond laser is 340 to 360 nm, the average laser power is 2.8 to 3.2 W, the scanning speed is 380 to 420 mm / s, and the repetition frequency is 180 to 220 kHz.

7. The method for preparing the vapor chamber liquid-absorbing core structure according to claim 4, characterized in that, In step S2, the boiling water treatment time is 160 to 200 minutes, and the boiling water temperature is 140 to 160°C.

8. The method for preparing the vapor chamber liquid-absorbing core structure according to claim 4, characterized in that, In step S1, the cross-section of the etched micropillar structure is an isosceles trapezoid, with both the upper and lower bases being squares; the width of the lower base of the micropillar structure is 350 to 550 μm. The depth of the etched micropit structure is 30 to 50 μm, and the diameter of the top surface of the micropit structure is 10 to 30 μm. Infrared femtosecond lasers are used to etch V-shaped grooves between adjacent micropillar structures. The width of the V-shaped groove is 50 to 100 μm, and the ratio of the height to the width of the V-shaped groove is 1.5 to 2. The needle-like structures of the nanoneedle cluster have an average length of 260 to 300 nm, an average width of 30 to 60 nm, and a thickness ranging from 0.4 to 1.2 μm.

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