Capillary wick, heat pipe and VC heat sink

Abstract

This disclosure provides a capillary wick, a heat pipe, and a VC vapor chamber, belonging to the field of heat dissipation devices. The capillary wick includes: a first capillary structure layer, a second capillary structure layer, and a plurality of capillary pillars, with the first and second capillary structure layers disposed opposite to each other; the plurality of capillary pillars are disposed between the first and second capillary structure layers, forming a microchannel extending from one end of the capillary wick to the other. The capillary wick, heat pipe, and VC vapor chamber provided in this disclosure, by setting a plurality of capillary pillars between the first and second capillary structure layers and forming an acute-angle flow channel region between the capillary pillars and the structure layers, structurally constructs a three-dimensional composite liquid guiding system with strong capillary attraction and a smooth return flow path. This significantly enhances capillary pressure difference, improves wetting speed and climbing ability during liquid contact, while reducing flow resistance during liquid return.

Description

Technical Field

[0001] This disclosure belongs to the field of heat dissipation device technology, specifically relating to a capillary wick, a heat pipe, and a VC heat sink. Background Technology

[0002] Phase change thermal management technology is widely used in thermal management devices such as heat pipes and vapor chambers (VCs). Due to its high thermal conductivity and compact structure, it has become an important component of heat dissipation systems for high-performance electronic devices. In these devices, the capillary wick is a key component for realizing the return of condensate to the evaporation end, and its performance directly affects the thermal cycling efficiency and overall heat dissipation capacity of the device.

[0003] Currently, the capillary structure materials commonly used in heat pipes and VCs mainly include copper powder sintered layers and copper mesh laminated sintered structures. Among them, copper powder sintered layers form a porous structure with a certain porosity by controlling the powder particle size and sintering process, while copper mesh laminates are formed by pressing and sintering several layers of fine copper wire mesh to form a spatial network.

[0004] However, in demanding applications requiring high heat flux and rapid thermal response, these traditional capillary structures exhibit significant performance bottlenecks. Specifically, due to their relatively simple capillary channel structure, insufficient surface wettability, or lack of optimized channel orientation, their capillary liquid absorption rate is low, making it difficult for liquid to flow back to the evaporation zone in a timely and efficient manner at the condensation end. Utility Model Content

[0005] The purpose of this disclosure is to provide a capillary wick, a heat pipe, and a VC heat exchanger that can improve the flow rate and climbing height of a liquid working fluid.

[0006] To achieve the above objectives, the technical solution provided in this disclosure is as follows:

[0007] In a first aspect, this disclosure provides a capillary core comprising: a first capillary structure layer, a second capillary structure layer, and a plurality of capillary columns, wherein the first capillary structure layer and the second capillary structure layer are disposed opposite to each other; the plurality of capillary columns are disposed between the first capillary structure layer and the second capillary structure layer, and a microchannel is formed between the plurality of capillary columns extending from one end of the capillary core to the other end; wherein an acute-angle flow channel region is formed between the capillary columns and the first capillary structure layer and / or the second capillary structure layer; and on the cross-section of the capillary core, the angle between the tangent of the capillary column at the acute-angle flow channel region and the first capillary structure layer and / or the second capillary structure layer is an acute angle.

[0008] In one or more embodiments, the first capillary layer and / or the second capillary layer is a porous metal structure, wherein the porous metal structure includes at least one of a metal powder sintered porous structure layer, a metal fiber interwoven porous structure layer, a porous metal sheet, and a metal fiber interwoven composite metal powder sintered porous structure layer; in the metal fiber interwoven composite metal powder sintered porous structure layer, the metal powder is distributed in the gaps between the fibers.

[0009] In one or more embodiments, the pore size in the first capillary layer and the second capillary layer is 5~30μm, and the porosity is greater than 35%.

[0010] In one or more embodiments, the capillary column has a capillary structure, and the surface of the capillary column is distributed with uneven metal powder.

[0011] In one or more embodiments, the capillary column is a porous metal wire formed by sintering metal powder.

[0012] In one or more embodiments, the cross-sectional shape of the capillary column is circular, elliptical, or semi-circular.

[0013] In one or more embodiments, the width of the capillary column is 0.1~0.7mm; the thickness of the first capillary layer and / or the second capillary layer is 0.01~0.5mm.

[0014] In one or more embodiments, the height of the microchannel is 0.08~0.35mm and the width is 0.1~1.5mm, preferably 0.15~0.6mm.

[0015] Secondly, this disclosure provides a heat pipe including a tube body and the aforementioned capillary wick, wherein the capillary wick is nested within the tube body and adheres to the inner wall of the tube body, and the capillary wick is sintered together with the inner wall of the tube body by means of metal powder.

[0016] Thirdly, this disclosure provides a VC heat spreader, which includes a housing and the aforementioned capillary wick, the capillary wick being attached to the inner wall of the housing.

[0017] The capillary wick, heat pipe, and VC heat spreader provided in this disclosure construct a three-dimensional composite liquid guiding system with strong capillary attraction and unobstructed reflux path by setting multiple capillary columns between the first capillary structure layer and the second capillary structure layer, and forming an acute-angle flow channel region between the capillary columns and the structure layer. This significantly enhances the capillary pressure difference, improves the wetting speed and climbing ability when the liquid is in contact, while reducing the flow resistance during the liquid reflux process. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic cross-sectional view of a capillary wick in one embodiment of the present disclosure;

[0020] Figure 2 This is a microscopic image of a porous structure layer sintered from metal powder in one embodiment of this disclosure;

[0021] Figure 3 This is a microscopic image of a metal fiber interwoven porous structure layer in one embodiment of this disclosure;

[0022] Figure 4 A microscopic image of a porous metal plate according to an embodiment of this disclosure;

[0023] Figure 5 This is a microscopic image of a porous structure layer of interwoven metal fiber composite metal powder sintered in one embodiment of this disclosure.

[0024] Explanation of key figure labels:

[0025] 1-First capillary layer, 2-Second capillary layer, 3-Capillary column, 4-Microchannel, 41-Acute-angled channel region. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0027] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0028] It should be noted that when an element is described as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. In the embodiments shown in this disclosure, directional representations such as up, down, left, right, front, and back are relative and are used to explain the relative structure and movement of different components in this disclosure. These representations are appropriate when the components are in the positions shown in the figures. However, if the description of the component positions changes, then these representations are considered to change accordingly.

[0029] In phase change heat dissipation devices such as heat pipes and VCs, the capillary wick serves as the core structure for working fluid reflux, and its performance directly affects the thermal cycling efficiency and heat dissipation capacity of the entire device. Existing capillary wicks typically employ sintered metal powder layers or metal mesh stacked structures. Although these structures have mature processing technologies, under complex operating conditions such as high heat flux density or rapid thermal response, problems such as slow liquid absorption rate, weak capillary driving force, and obstructed liquid reflux path are becoming increasingly prominent. Especially during continuous high-power heat dissipation, the condensate is difficult to return to the evaporation zone in a timely manner, easily causing localized drying, thereby affecting the stability and reliability of phase change heat dissipation.

[0030] After conducting an in-depth analysis of the structural characteristics and performance limitations of the aforementioned prior art, the inventors realized that the traditional capillary wick structure has a bottleneck in terms of capillary reflux efficiency. The core problem lies in the lack of a three-dimensional guiding structure that has both strong capillary suction and low flow resistance, making it impossible to effectively balance the needs of liquid wetting ability and smooth reflux.

[0031] Based on this understanding, this disclosure proposes a novel capillary wick design concept, aiming to construct a multidimensional composite capillary structure that simultaneously possesses high capillary driving capability and low backflow resistance. This concept introduces a three-dimensional support network between multiple interfaces within the capillary wick, forming a spatial configuration within the network structure that enhances capillary attraction and guides the directional backflow of the liquid. This structurally enhances the adsorption, climbing, and backflow capabilities of the working fluid. This composite capillary structure fully utilizes the synergistic effect of its components, strengthening capillary forces and optimizing the liquid flow path. By forming continuous liquid transport channels within the capillary wick, it shortens the backflow time of the liquid working fluid from the condensation zone to the heat source zone.

[0032] Please refer to Figure 1As shown, a capillary core in one embodiment of this disclosure includes: a first capillary structure layer 1, a second capillary structure layer 2, and a plurality of capillary columns 3. The first capillary structure layer 1 and the second capillary structure layer 2 are disposed opposite to each other; the plurality of capillary columns 3 are disposed between the first capillary structure layer 1 and the second capillary structure layer 2, and a microchannel 4 extending from one end of the capillary core to the other end is formed between the plurality of capillary columns 3. An acute-angle flow channel region 41 is formed between the capillary columns 3 and the first capillary structure layer 1 and / or the second capillary structure layer 2; on the cross-section of the capillary core, the angle between the tangent of the capillary column 3 at the acute-angle flow channel region 41 and the first capillary structure layer 1 and / or the second capillary structure layer 2 is an acute angle.

[0033] The first capillary layer 1 and the second capillary layer 2 are arranged opposite to each other, forming the upper and lower interfaces of the capillary core, respectively, and playing a role in stabilizing the overall structure, providing initial wetting, and capillary attraction. These two layers can be made of porous metallic materials, possessing porous characteristics that enable rapid capillary adsorption upon contact with the liquid working fluid, promoting liquid diffusion along the surface. They not only serve as the source of capillary force for liquid absorption but also as the supporting base for the entire array of capillary columns 3.

[0034] Capillary columns 3 are located between the first capillary structure layer 1 and the second capillary structure layer 2. The arrangement of multiple capillary columns 3 forms interconnected microchannels 4, which create a continuous liquid reflux channel extending from one end to the other within the capillary core. These microchannels 4 provide a low-resistance transport path for the liquid working fluid from the condensation zone to the evaporation zone, promoting efficient liquid reflux. The capillary columns 3 themselves have a capillary structure, enabling them to further adsorb the liquid working fluid through capillary action, enhancing the liquid's transport capacity within the capillary core.

[0035] The capillary column 3 forms an acute-angle flow channel region 41 at the contact point with the upper and lower capillary structure layers, that is, from the cross-section of the capillary core (e.g. Figure 1 As shown, the outer contour of the capillary column 3 forms an angle of less than 90° with the surface of the adjacent capillary layer, creating an acute-angled converging flow channel. This acute-angle flow channel structure generates a large capillary pressure difference during liquid contact, enhancing the driving force at the liquid interface and thus significantly increasing the liquid's rise height and flow velocity. Simultaneously, due to the capillary structure of the capillary column 3 itself, its outer surface possesses abundant roughness and capillary pores, further enhancing capillary attraction and liquid wetting effects.

[0036] In one exemplary embodiment, the first capillary layer 1 and / or the second capillary layer 2 are porous metal structures, which include at least one of a metal powder sintered porous structure layer, a metal fiber interwoven porous structure layer, a porous metal sheet, and a metal fiber interwoven composite metal powder sintered porous structure layer; in the metal fiber interwoven composite metal powder sintered porous structure layer, the metal powder is distributed in the gaps between the fibers.

[0037] The first capillary layer 1 and the second capillary layer 2 provide the boundary for the entire capillary core and together constitute the capillary channel interface for liquid reflux and adsorption. Their performance directly affects the wetting ability and reflux efficiency of the working fluid. These two layers preferably employ a metal structure with capillary pores to achieve a good balance between capillary liquid absorption performance and mechanical strength. The so-called porous metal structure includes four forms: sintered porous metal powder layers (such as...) Figure 2 As shown), a porous structure layer interwoven with metal fibers (such as...) Figure 3 As shown), porous metal sheets (such as...) Figure 4 As shown), and a porous structure layer of interwoven metal fiber composite metal powder sintering (such as...). Figure 5 (As shown).

[0038] Among them, the metal powder sintering structure forms a highly interconnected porous network within the material through a directional sintering process of metal powders of different particle sizes. This structure possesses a high specific surface area and stable pore size distribution, providing continuous capillary channels to ensure rapid adsorption and spread of condensate along the channels. The metal fiber interwoven structure uses metal filaments woven into a mesh structure in a specific manner, with uniform gaps and good flexibility and liquid permeability, suitable for high-frequency liquid reciprocating wetting scenarios. Furthermore, porous metal sheets form micropore arrays on metal substrates through machining or laser drilling, exhibiting structural stability and strong pressure resistance, and can serve as a carrier to enhance the overall mechanical strength of the capillary core. The metal fiber interwoven composite metal powder sintered porous structure layer involves covering a layer of metal powder onto a metal wire interwoven mesh structure and sintering it, distributing the metal powder within the gaps between the metal wires to form a composite porous structure. This provides good capillary wetting while enhancing structural integrity and liquid retention capacity, achieving a synergistic effect of dual liquid absorption mechanisms.

[0039] The aforementioned porous metal structures can be combined or replaced according to specific application requirements, providing a stable, continuous, and efficient interfacial liquid absorption environment for the microchannels 4 between the capillary columns 3, ensuring that the liquid working fluid can be rapidly adsorbed and guided into the interior of the capillary wick. The porous metal structures can be made of copper, aluminum, titanium, nickel, or their alloys, or other metallic materials. Generally, metallic materials have good thermal conductivity, strong machinability, and corrosion resistance, which helps improve the long-term reliability of the capillary wick in complex working environments such as high temperature and high humidity.

[0040] Preferably, the capillary pores in the first capillary layer 1 and the second capillary layer 2 have a size of 5~30μm and a porosity greater than 35%. This pore size range of 5~30μm allows for maintaining a large capillary pressure differential while ensuring the unobstructed flow of the liquid. If the pore size is too small, although capillary force may increase, flow resistance will rise significantly, hindering rapid liquid recirculation; conversely, if the pore size is too large, capillary attraction weakens, making it difficult for the liquid to be adsorbed and drawn in a timely manner.

[0041] A porosity greater than 35% not only ensures that the liquid can form continuous seepage channels at the microscale, but also helps to improve the overall liquid storage capacity and response speed of the capillary layer. Higher porosity means an increase in the amount of liquid adsorbed per unit area, so that the condensate can be adsorbed in large quantities and distributed to a wider area when it comes into instantaneous contact with the capillary layer surface, and then quickly enter the internal microchannels 4. This ensures that the liquid working fluid can be continuously supplied to the evaporation zone during the phase change heat dissipation process, preventing the heat source area from failing due to lack of liquid.

[0042] Preferably, the width of the capillary column 3 is 0.1~0.7mm; the thickness of the first capillary layer 1 and / or the second capillary layer 2 is 0.01~0.5mm. The height of the microchannel 4 is 0.08~0.35mm, and the width is 0.1~1.5mm, preferably 0.15~0.6mm.

[0043] The width of the capillary column 3 is in the range of 0.1~0.7mm, balancing the supporting strength of the capillary column 3 with the effective flow area of ​​the microchannel 4. The smaller width of the capillary column 3 helps to form more microchannels 4 between adjacent columns, thereby increasing the density of return channels per unit area and improving the uniformity of liquid distribution and response speed. Without sacrificing the unobstructed flow, moderately increasing the width of the capillary column 3 can enhance the overall rigidity of the structure and improve its stability under high thermal loads or mechanical vibration conditions.

[0044] In conjunction with the capillary column 3, the thicknesses of the first capillary structure layer 1 and the second capillary structure layer 2 are in the range of 0.1~0.5mm. This thickness setting ensures, on the one hand, that the capillary layer has sufficient pore depth to form a stable capillary channel network, which is beneficial for the condensate to quickly penetrate into the interior and be transported to the microchannel 4 after contacting the surface; on the other hand, it also avoids the volume redundancy and heat conduction path extension problems caused by excessively thick capillary layers, thereby improving thermal response efficiency and material utilization while ensuring the liquid absorption function.

[0045] The height of the microchannel 4 is in the range of 0.08~0.35mm, which ensures that there is enough space inside the microchannel 4 to accommodate the liquid volume and maintain continuous flow, while also generating a strong capillary pressure difference to drive liquid backflow. The width of the microchannel 4 is in the range of 0.1~1.5mm, which can provide a certain amount of capillary force while reducing liquid flow resistance.

[0046] In one exemplary embodiment, to further enhance its liquid conduction capacity and interfacial wetting performance during the working fluid reflux process, the capillary column 3 has a capillary pore structure, and the surface of the capillary column 3 is distributed with uneven metal powder.

[0047] The capillary structure inside the capillary column 3 can be fabricated through powder sintering, porous wire drawing, and other methods. The resulting interconnected pore network allows liquid to permeate radially or axially within the column, thereby enhancing the column's capillary storage capacity and multi-path adsorption capacity. This structure helps alleviate the liquid concentration and blockage problems that may occur during condensate reflux, and also makes the capillary column 3 not only an obstacle between flow channels, but also a porous liquid-conducting medium with active adsorption and permeation capabilities.

[0048] Furthermore, the uneven metal powder layer coating the surface of the capillary column 3 further expands its surface contact area and introduces microscopic roughness. This rough surface effectively enhances the contact hysteresis between the liquid and the column surface, thereby promoting a stronger capillary wetting effect at the moment of contact. The uneven powder structure also improves the adhesion stability of the liquid along the column surface, making it less prone to detachment and flow interruption during vertical or inclined flow, which helps maintain a continuous and stable flow of liquid into the downstream flow channel area.

[0049] Specifically, the capillary column 3 is a porous metal wire formed by sintering metal powder. The porous metal wire, formed using metal powder sintering technology, has numerous through or semi-through capillary channels inside, allowing the working fluid to not only wet and spread along the surface of the column but also penetrate into the internal capillary pores when it comes into contact with it. This multi-path distribution enables rapid liquid absorption and directional transport. Compared to a solid column, this structure has a higher specific surface area and stronger capillary driving force.

[0050] In terms of shape design, the capillary column 3 is not limited to a straight configuration; it can be designed as a curved or divergent layout according to application requirements. This degree of freedom in shape design makes the microchannel system 4 inside the capillary core more adaptable and diverse. For example, a curved column can be used to adjust the direction of local channels and alleviate flow dead zones; a divergent structure is beneficial for quickly guiding the liquid to diffuse outward in areas with concentrated heat sources, improving the uniformity of liquid distribution and thermal response speed.

[0051] Furthermore, the cross-sectional shape of the capillary column 3 is circular, elliptical, or semi-circular. A circular cross-section is the most symmetrical form; when its outer contour contacts the surrounding capillary structure layer, multiple acute-angled regions of equal angles are naturally formed on the cross-section. This facilitates the uniform generation of capillary pressure differentials in different directions, enhancing the adsorption capacity of the liquid around the column. Simultaneously, the spacing of the circular columns is easily controlled during manufacturing and arrangement, enabling the formation of a regular and uniform microchannel network 4 within the capillary core, which is beneficial for achieving stable liquid channels and flow control.

[0052] The elliptical cross-section introduces a difference between the major and minor axes, giving the flow channel space a directional quality. By rationally arranging the major axis of the elliptical cylinder, the liquid can be guided to preferentially expand or accelerate its flow in a specific direction, thereby enhancing the directional nature of the liquid's backflow. This is suitable for scenarios with uneven heat flux distribution or concentrated local heat sources.

[0053] Semi-circular cross-sections are typically used in scenarios where there is a closer fit with a capillary layer on one side. The flat side allows for a larger contact area with the upper or lower structure, improving structural stability, while the curved surface still retains some capillary liquid-gathering effect. This structure is suitable for boundary areas or structural designs requiring support on one side and release of flow space on the other.

[0054] This disclosure also provides a heat pipe comprising a tube body and the aforementioned capillary wick, the capillary wick being nested within the tube body and conforming to the inner wall of the tube body. The capillary wick is sintered with the inner wall of the tube body using metal powder. The tube body, as an external sealed container, is typically made of a highly thermally conductive metal (such as copper or aluminum) and is elongated or has a specific geometric shape, creating a vacuum or low-pressure environment inside to contain the liquid working fluid. The capillary wick, nestled within the tube body and tightly conforming to the inner wall of the tube body, is sintered with the inner wall of the tube body using metal powder, forming the core liquid transport system of the heat pipe. The capillary wick consists of a first capillary structure layer, a second capillary structure layer, and capillary columns, wherein the gaps between the capillary columns form microchannels. These microchannels, in conjunction with the porous structure of the first and second capillary structure layers, work together to drive the liquid working fluid back from the condensation zone to the evaporation zone.

[0055] This disclosure also provides a VC vapor chamber, comprising a shell and the aforementioned capillary wick, the capillary wick being attached to the inner wall of the shell. The shell, as an external sealed container, is typically made of a highly thermally conductive metal (such as copper or aluminum), and is flat in shape, forming a vacuum or low-pressure environment inside to contain the liquid working fluid. The capillary wick is attached to the inner wall of the shell, in close contact with the inner wall surface, constituting the core system for liquid transport and heat diffusion of the vapor chamber. The capillary wick consists of a first capillary structure layer, a second capillary structure layer, and capillary columns, wherein the gaps between the capillary columns form microchannels. The microchannels, in conjunction with the porous structure of the first and second capillary structure layers, drive the circulating flow of the liquid working fluid within the shell.

[0056] The capillary core provided in this disclosure will be further described below with reference to specific embodiments.

[0057] Example 1

[0058] The first and second capillary layers are made of copper powder sintered layers (thickness of about 0.25 mm, average pore size of about 16 μm, porosity of about 60%), with circular copper powder sintered metal wires of about 0.3 mm in diameter set in the middle as capillary columns, and the microchannels between the columns are about 0.3 mm high and about 0.6 mm wide.

[0059] Example 2

[0060] The copper powder sintered layer, which is basically the same as in Example 1, is used as the first capillary structure layer and the second capillary structure layer. An elliptical copper powder sintered metal wire with a height (short axis) of about 0.27 mm and a width (long axis) of about 0.36 mm is set in the middle as a capillary column. The microchannel between the columns has a height of about 0.27 mm and a width of about 0.6 mm.

[0061] Example 3

[0062] A copper powder sintered layer, which is basically the same as in Example 1, is used as the first capillary structure layer and the second capillary structure layer. A semi-circular copper powder sintered metal wire with a diameter of about 0.4 mm is set in the middle as a capillary column. The height of the microchannel between the columns is about 0.2 mm and the width is about 0.6 mm.

[0063] Example 4

[0064] The first capillary layer and the second capillary layer adopt Figure 3 The metal fiber interwoven porous structure shown has a thickness of about 0.2 mm. A circular copper powder sintered metal wire with a diameter of about 0.3 mm is set in the middle as a capillary column. The microchannel between the columns has a height of about 0.3 mm and a width of about 0.6 mm.

[0065] Example 5

[0066] The first capillary layer and the second capillary layer adopt Figure 4 The porous metal sheet shown has a diameter of about 0.3 mm and a circular copper powder sintered metal wire as a capillary column in the middle. The microchannel between the columns is about 0.3 mm high and about 0.6 mm wide.

[0067] Example 6

[0068] The first capillary layer and the second capillary layer adopt Figure 5 The metal fiber interwoven composite metal powder sintered porous structure shown has a thickness of about 0.25 mm. A circular copper powder sintered metal wire with a diameter of about 0.3 mm is set in the middle as a capillary column. The microchannel between the columns has a height of about 0.3 mm and a width of about 0.6 mm.

[0069] Comparative Example 1

[0070] The single-layer copper powder sintered capillary structure has a thickness of about 0.6 mm, an average pore size of about 16 μm, a porosity of about 60%, and no internal microchannel guiding structure.

[0071] Comparative Example 2

[0072] A copper powder sintered layer, which is basically the same as in Example 1, is used as the first capillary structure layer and the second capillary structure layer. A square copper powder sintered metal wire with a side length of about 0.3 mm is set in the middle as a capillary column. The microchannel between the columns has a height of about 0.3 mm and a width of about 0.6 mm.

[0073] The capillary wick performance of each embodiment and comparative example was tested. The water absorption time required for the capillary wick to reach a water absorption height of 20 cm and the maximum water absorption height of the capillary wick were measured. The maximum water absorption height was determined to be reached when the water absorption rate was below 1 cm / min. The test results are shown in Table 1.

[0074] Table 1 - Capillary wick performance test results

[0075]

[0076] Note: When the sample is tested for water absorption vertically, the water absorption rate gradually decreases as the height increases. When the water absorption rate drops to 1 cm / min, it is considered to have reached the maximum water absorption height.

[0077] In summary, the capillary wick, heat pipe, and VC heat spreader provided in this disclosure, by setting multiple capillary columns between the first and second capillary structural layers and forming an acute-angle flow channel region between the capillary columns and the structural layers, structurally construct a three-dimensional composite liquid guiding system with strong capillary attraction and unobstructed return path. This system can significantly enhance capillary pressure difference, improve wetting speed and climbing ability when in contact with liquid, while reducing flow resistance during liquid return process.

[0078] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0079] 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 capillary wick, characterized in that, include: A first capillary layer and a second capillary layer are disposed opposite to each other; Multiple capillary columns are disposed between the first capillary structure layer and the second capillary structure layer, and microchannels extending from one end of the capillary core to the other are formed between the multiple capillary columns; Wherein, an acute-angle flow channel region is formed between the capillary column and the first capillary structure layer and / or the second capillary structure layer; on the cross-section of the capillary core, the angle between the tangent of the capillary column at the acute-angle flow channel region and the first capillary structure layer and / or the second capillary structure layer is an acute angle.

2. The capillary wick according to claim 1, characterized in that, The first capillary layer and / or the second capillary layer are porous metal structures, and the porous metal structure includes at least one of the following: a metal powder sintered porous structure layer, a metal fiber interwoven porous structure layer, a porous metal sheet, and a metal fiber interwoven composite metal powder sintered porous structure layer; in the metal fiber interwoven composite metal powder sintered porous structure layer, the metal powder is distributed in the gaps between the fibers.

3. The capillary wick according to claim 2, characterized in that, The pore size in the first capillary layer and the second capillary layer is 5~30μm, and the porosity is greater than 35%.

4. The capillary wick according to claim 1, characterized in that, The capillary column has a capillary structure, and the surface of the capillary column is distributed with uneven metal powder.

5. The capillary wick according to claim 4, characterized in that, The capillary column is a porous metal wire formed by sintering metal powder.

6. The capillary wick according to claim 1, characterized in that, The cross-sectional shape of the capillary column is circular, elliptical, or semi-circular.

7. The capillary wick according to claim 1, characterized in that, The width of the capillary column is 0.1~0.7mm; the thickness of the first capillary structure layer and / or the second capillary structure layer is 0.01~0.5mm.

8. The capillary wick according to claim 1, characterized in that, The height of the microchannel is 0.08~0.35mm and the width is 0.1~1.5mm.

9. A heat pipe, characterized in that, The device includes a tube body and a capillary core as described in any one of claims 1 to 8, wherein the capillary core is nested within the tube body and adheres to the inner wall of the tube body, and the capillary core is sintered together with the inner wall of the tube body by means of metal powder.

10. A VC heat spreader, characterized in that, It includes a housing and a capillary core according to any one of claims 1 to 8, the capillary core being attached to the inner wall of the housing.

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