An ultrathin vapor chamber based on a biomimetic capillary wick

Abstract

The application belongs to the technical field of heat dissipation devices, and specifically discloses an ultrathin vapor chamber based on a bionic capillary wick, which comprises a lower cover plate, a primary wick, a bionic secondary wick and an upper cover plate. The lower cover plate is provided with a cavity, and the cavity is filled with a liquid working medium; the primary wick is laid on the inner bottom surface of the cavity; the bionic secondary wick is laid on the top surface of the primary wick; and the upper cover plate is connected to the top of the lower cover plate to seal the primary wick and the bionic secondary wick in the cavity of the lower cover plate. The primary wick and the bionic secondary wick are the same or different porous medium structures, and the ultrathin vapor chamber is sequentially divided into an evaporation zone, an adiabatic zone and a condensation zone along the length direction. The application effectively enhances the capillary pressure, improves the liquid return rate and optimizes the condensation heat transfer performance through the synergistic effect of the multi-stage wicks, the zoned design of the superhydrophilic and superhydrophobic structures and the gradient design of the bionic capillary wick, and has the advantages of improving the heat transfer limit and reducing the condensation thermal resistance.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation device technology, and in particular to an ultrathin heat spreader based on a biomimetic capillary core. Background Technology

[0002] With the widespread adoption of 5G portable smart devices, electronic devices are rapidly evolving towards higher power and miniaturization. This trend has resulted in extremely limited internal space for electronic devices, drastically restricting the size of heat dissipation components. Therefore, how to efficiently dissipate high heat flux density within such a confined space has become a critical problem that urgently needs to be solved.

[0003] Among numerous heat dissipation solutions, ultrathin vapor chambers with a total thickness of less than 1 mm have gradually become an important choice for heat dissipation in 5G portable smart devices due to their significant advantages such as high thermal conductivity, good temperature uniformity, small size, and compact structure. However, when the total thickness of the ultrathin vapor chamber is further reduced to less than 0.6 mm, the thickness of the wick becomes extremely limited after deducting the wall thickness of the upper and lower cover plates and the thickness occupied by the vapor channel. This leads to a significant weakening of the capillary force of the wick and a substantial increase in flow resistance. In this situation, the reflux condensate working fluid in the evaporation zone is prone to be insufficient, while condensate tends to accumulate in the condensation zone. These phenomena not only reduce the heat transfer limit of the ultrathin vapor chamber but also increase the condensation heat transfer thermal resistance, seriously affecting its heat dissipation performance and limiting its application in thinner, higher power density devices.

[0004] In view of this, there is an urgent need for an ultrathin heat spreader based on a biomimetic capillary core to solve the above problems. Summary of the Invention

[0005] The present invention aims to provide an ultrathin heat exchange plate based on a biomimetic capillary core to solve the above-mentioned technical problems and achieve the purpose of increasing the heat transfer limit of the ultrathin heat exchange plate and reducing the condensation thermal resistance.

[0006] To achieve the above objectives, the present invention provides the following solution: an ultrathin heat spreader based on a biomimetic capillary wick, comprising:

[0007] The lower cover plate has a cavity filled with a liquid working fluid.

[0008] A primary liquid-absorbing core is laid on the inner bottom surface of the cavity;

[0009] A biomimetic secondary absorbent core is laid on the top surface of the primary absorbent core;

[0010] The upper cover plate is connected to the top of the lower cover plate and seals the primary liquid-absorbing core and the bionic secondary liquid-absorbing core within the cavity of the lower cover plate;

[0011] The primary liquid-absorbing core and the biomimetic secondary liquid-absorbing core may have the same or different porous media structures;

[0012] The ultra-thin heat spreader is divided into an evaporation zone, an insulation zone, and a condensation zone along its length.

[0013] Preferably, the biomimetic secondary liquid-absorbing core comprises 2-15 biomimetic capillary cores arranged at equal intervals along the width direction of the ultrathin heat spreader. The array of biomimetic capillary cores improves liquid transport efficiency, prevents condensate accumulation in localized areas, and avoids drying out of the evaporation zone due to insufficient liquid supply, thereby ensuring stable heat dissipation performance of the heat spreader under extreme thickness conditions.

[0014] Preferably, the biomimetic capillary wick has a smooth, gradually widening width from the condensation zone to the evaporation zone, forming an isosceles trapezoidal structure. The gradual expansion of the isosceles trapezoidal structure allows the capillary pressure distribution in different regions of the capillary wick to better match actual operating conditions, thereby improving the heat transfer efficiency of the heat spreader under high heat flux density conditions.

[0015] Preferably, the porous surface of the primary wick in the evaporation zone has a superhydrophilic micro / nano structure; the porous surface of the primary wick in the adiabatic zone near the evaporation zone has a superhydrophilic micro / nano structure; the lower porous surface of the primary wick in the condensation zone has a superhydrophilic micro / nano structure; the lower porous surface of the primary wick in the adiabatic zone near the condensation zone has a superhydrophilic micro / nano structure; the upper porous surface of the primary wick in the condensation zone has a superhydrophobic micro / nano structure; and the upper porous surface of the primary wick in the adiabatic zone near the condensation zone has a superhydrophobic micro / nano structure. This design optimizes the condensate discharge path while maintaining high capillary force through the partitioned design of superhydrophilic and superhydrophobic structures.

[0016] Preferably, the biomimetic capillary core has alternating triangular serrated structures on both sides of the upper part of the superhydrophobic micro / nano structure of the primary liquid-absorbing core. This design creates a spontaneous droplet migration path by constructing an asymmetric serrated structure on both sides of the superhydrophobic region, thus avoiding the accumulation and blockage of condensate at the edge of the capillary core.

[0017] Preferably, the porous surface of the biomimetic secondary liquid-absorbing core has a superhydrophilic micro / nano structure. This structure can reduce liquid flow resistance and accelerate the permeation and diffusion of the working fluid within the pores.

[0018] Preferably, the primary liquid-absorbing core and / or the biomimetic secondary liquid-absorbing core are made of one or more of sintered copper powder, wire mesh, and copper foam. The above structure significantly improves the liquid working fluid reflux efficiency through the selection and combination of materials, avoiding insufficient liquid supply in the evaporation zone and liquid accumulation in the condensation zone, thereby increasing the heat transfer limit and reducing the condensation thermal resistance, providing reliable capillary dynamic support for a heat spreader with a thickness of less than 0.6 mm.

[0019] Preferably, the upper cover plate and the lower cover plate are made of the same material, namely metal.

[0020] Preferably, the upper cover plate and the lower cover plate are made of copper, aluminum or stainless steel.

[0021] Preferably, the liquid working medium is one of water, acetone, alcohol, or aqueous solution of alcohol.

[0022] Compared with the prior art, the present invention discloses at least the following beneficial effects: The ultrathin heat spreader of the present invention has a porous medium structure with a primary liquid wick and a biomimetic secondary liquid wick. By dividing the evaporation zone, the adiabatic zone and the condensation zone, and combining the gradient design of the superhydrophilic-superhydrophobic micro-nano structure and the biomimetic capillary wick, the capillary pressure is effectively enhanced, the liquid reflux rate is increased and the condensation heat transfer performance is optimized. It has the advantages of improving the heat transfer limit and reducing the condensation thermal resistance. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of the ultrathin heat spreader based on the biomimetic capillary core of the present invention. Figure 1 ;

[0025] Figure 2 This is a schematic diagram of the structure of the ultrathin heat spreader based on the biomimetic capillary core of the present invention. Figure 2 ;

[0026] Figure 3 This is a schematic diagram of the front structure of the ultrathin heat spreader based on biomimetic capillary core of the present invention.

[0027] Figure 4 This is a front assembly view of the ultrathin heat spreader plate based on biomimetic capillary core of the present invention;

[0028] Figure 5 This is a top view of the internal structure of the present invention after the top cover plate has been removed.

[0029] In the diagram: 1. Upper cover plate; 2. Lower cover plate; 3. Primary suction core; 4. Bionic secondary suction core; 41. Bionic capillary core; 42. Triangular serrated structure; 5. Condensation zone; 6. Insulation zone; 7. Evaporation zone. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] In existing technologies, with the increasing power and miniaturization of portable smart devices, heat dissipation components need to achieve efficient heat conduction within a limited space. When the thickness of traditional ultra-thin heat exchange plates is further reduced, the capillary force of the wick decreases significantly, causing the condensed liquid to fail to flow back to the evaporation zone 7 in a timely manner. At the same time, the resistance to vapor flow increases, ultimately leading to a decrease in heat transfer efficiency and an increase in thermal resistance.

[0032] To address the aforementioned issues, this study analyzes the contradictory relationship between capillary force and flow resistance under thin-film conditions, as well as the flow characteristics of the liquid working fluid within an ultrathin cavity. It reveals that a single wicking structure cannot simultaneously meet the requirements of increased capillary force and reduced flow resistance. Therefore, a multi-stage wicking mechanism is proposed to optimize the liquid transport path. Furthermore, considering the driving effect of surface energy gradients on the directional flow of the liquid, a combined design of superhydrophilic and superhydrophobic regions is explored.

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Reference Figures 1 to 5 As shown, this invention provides an ultrathin vapor chamber based on a biomimetic capillary core, comprising a lower cover plate 2, an upper cover plate 1, a primary wicking core 3, and a biomimetic secondary wicking core 4. The lower cover plate 2 forms a sealed cavity filled with a liquid working fluid. The primary wicking core 3 covers the bottom surface of the cavity, and the biomimetic secondary wicking core 4 is superimposed on the surface of the primary wicking core 3. The ultrathin vapor chamber is divided along its length into an evaporation zone 7, an adiabatic zone 6, and a condensation zone 5. The wicking cores employ a porous media structure. The cavity of the lower cover plate 2 is a closed space for containing the liquid working fluid and for phase change heat transfer; it can be formed through stamping or etching processes, and its depth is adapted to the heat dissipation requirements of the equipment. The primary wicking core 3, a basic capillary structure laid on the bottom surface of the cavity, provides basic capillary force and guides liquid distribution. The biomimetic secondary wicking core 4 is an auxiliary capillary structure superimposed on the surface of the primary wicking core 3. Its morphology mimics the hierarchical characteristics of biological capillary tissue, forming supplementary liquid transport channels. The primary liquid-absorbing core 3 and the biomimetic secondary liquid-absorbing core 4 can be made of the same or different porous media structures. The porous media structure is a permeable material with interconnected pores. The porosity can be adjusted according to the properties of the working fluid, which can maintain capillary force and control flow resistance.

[0035] Specifically, the liquid working fluid is heated and evaporated into steam in evaporation zone 7, and the steam diffuses into condensation zone 5 via adiabatic zone 6. The condensed liquid is then accelerated backflow through the directional structure of the biomimetic secondary wicking core 4, while the base structure of the primary wicking core 3 ensures uniform liquid distribution. The layered design of the porous medium forms a composite capillary channel, which increases the liquid contact area and reduces flow resistance through the pore gradient. The functional division between evaporation zone 7 and condensation zone 5 optimizes the phase change heat transfer path, while adiabatic zone 6 provides a low-resistance channel for steam flow.

[0036] Compared to existing technologies, traditional single-layer wick structures face a contradiction between capillary force and thickness limitations when achieving thinner designs, while layered wick designs can achieve capillary force superposition within a limited space. In existing technologies, homogeneous porous structures are prone to forming flow dead zones; biomimetic hierarchical structures improve liquid transport efficiency by optimizing pore distribution. Furthermore, existing solutions do not consider functional differentiation in different regions; this solution achieves directional optimization of the heat transfer path through zoned design.

[0037] Through the above technical solutions, this embodiment maintains effective capillary driving force under ultra-thin conditions, ensuring timely return of condensed liquid to evaporation zone 7 and preventing localized drying or liquid accumulation. The synergistic effect of the multi-stage wicking core reduces the flow resistance of the working fluid and improves phase change heat transfer efficiency. The zoned structural design optimizes the spatial distribution of vapor diffusion and liquid return, enhancing the temperature uniformity of the heat spreader. This structure significantly improves the stability of heat dissipation performance while maintaining an ultra-thin thickness.

[0038] In a further optimized design, the biomimetic secondary liquid-absorbing core 4 includes 2-15 biomimetic capillary cores 41 arranged at equal intervals along the width direction of the ultrathin heat spreader. In one specific embodiment, as... Figure 1 As shown, the biomimetic secondary liquid absorption core 4 of this application includes three biomimetic capillary cores 41 arranged at equal intervals along the width direction of the ultrathin heat spreader.

[0039] Specifically, the biomimetic capillary 41 is a porous media structure that mimics the liquid transport mechanism of a biological organism. It can be achieved by stacking trapezoidal pore structures with sintered copper powder, enhancing liquid transport capacity through biomimetic design. The biomimetic capillary 41 can be manufactured using laser cutting or mold forming processes. Each biomimetic capillary 41 maintains a uniform spacing in the width direction, optimizing the circulation path of the liquid working fluid between the evaporation zone 7 and the condensation zone 5 through regular arrangement.

[0040] In a heat spreader with a total thickness of less than 0.6 mm, when the capillary force is insufficient due to the limited thickness of the liquid wick, multiple parallel-arranged biomimetic capillary wicks 41 can be used to increase the capillary pressure per unit area without increasing the overall thickness. The biomimetic capillary wicks 41 are uniformly distributed along their width, allowing the condensate to synchronously return along the independent paths of each biomimetic capillary wick 41 after the liquid working fluid is heated and vaporized in the evaporation zone 7, avoiding liquid stagnation due to excessive local flow resistance. Simultaneously, the equidistant arrangement creates an alternating distribution of vapor and liquid return channels, effectively separating the gas-liquid two-phase flow paths.

[0041] Compared to existing technologies, traditional vapor chambers often employ a single-layer continuous wick structure, which is prone to insufficient capillary force and delayed liquid reflux under ultra-thin conditions. This solution, however, utilizes a discrete biomimetic capillary wick array (41 units) to form multiple independent capillary pumping units while maintaining structural strength. This allows for the superposition of local capillary pressures, and the edge effect generated by the discrete arrangement accelerates liquid diffusion in the width direction. This solves the problem of insufficient liquid reflux capacity in ultra-thin vapor chambers due to the limited thickness of the wick.

[0042] Further optimization of the design resulted in a biomimetic capillary wick 41 with a smooth, gradual widening from the condensation zone 5 to the evaporation zone 7, forming an isosceles trapezoidal structure. This isosceles trapezoidal structure represents a symmetrical, gradually expanding shape along the width of the capillary wick, which can be achieved through gradient processing of the porous medium using laser cutting or stamping techniques. This structure enhances the capillary transport capacity of the liquid working fluid at the evaporation end by increasing the cross-sectional area of ​​the capillary wick in the evaporation zone 7. The smooth, gradual widening means that there are no abrupt changes or steps in the width transition; this can be achieved by controlling the fluid flow path within the capillary wick through continuously transitioning geometric design parameters, thereby reducing flow resistance.

[0043] Specifically, the biomimetic capillary wick 41 with its isosceles trapezoidal structure maintains a narrow width at the beginning of the condensation zone 5, gradually expanding as it extends into the evaporation zone 7. This design allows the liquid working fluid channels of the capillary wick to form a diffuse distribution at the evaporation end, helping to increase the coverage area of ​​the liquid working fluid in the high-temperature region. During liquid reflux, the gradually widening channel structure generates a capillary pressure gradient, guiding the condensate to flow directionally towards the evaporation zone 7 along the trapezoidal slope. For example, when the heat spreader is operating, the liquid working fluid accumulated in the condensation zone 5 can be uniformly dispersed into the extended area of ​​the evaporation zone 7 through the lateral guidance of the trapezoidal structure.

[0044] Compared to existing technologies, traditional vapor chambers with parallel straight capillary wicks are prone to problems such as a single flow path and uneven liquid distribution during condensate reflux. This solution utilizes an isosceles trapezoidal structure to create an asymmetric capillary force distribution, maintaining the overall structural strength of the capillary wick while providing a larger permeation space for the liquid working fluid in the evaporation zone 7. Compared to conventional capillary wicks of uniform width, this structure effectively avoids localized liquid accumulation at the evaporation end and reduces pressure drop losses during flow. Based on this structure, this application enhances the diffusion capacity of the liquid working fluid in the evaporation zone 7 and improves the uniformity of the condensate reflux path distribution.

[0045] Further optimization of the scheme: the porous surface of the primary liquid-absorbing core 3 in the evaporation zone 7 has a superhydrophilic micro / nano structure; the porous surface of the primary liquid-absorbing core 3 in the adiabatic zone 6 near the evaporation zone 7 has a superhydrophilic micro / nano structure; the lower porous surface of the primary liquid-absorbing core 3 in the condensation zone 5 has a superhydrophilic micro / nano structure; the lower porous surface of the primary liquid-absorbing core 3 in the adiabatic zone 6 near the condensation zone 5 has a superhydrophilic micro / nano structure; the upper porous surface of the primary liquid-absorbing core 3 in the condensation zone 5 has a superhydrophobic micro / nano structure; and the upper porous surface of the primary liquid-absorbing core 3 in the adiabatic zone 6 near the condensation zone 5 has a superhydrophobic micro / nano structure. Specifically, the superhydrophilic micro / nano structure is a micro / nano-level roughened structure with a surface contact angle of less than 10 degrees, which can be achieved using chemical oxidation or nanoparticle coating processes. By enhancing the wettability of the liquid on the capillary core surface, the capillary suction force is improved. Superhydrophobic micro / nano structures are micro / nano-scale composite structures with a surface contact angle greater than 150 degrees. They can be achieved by fluorosilane modification or low surface energy material deposition processes. By inhibiting the spread of liquid on the surface, they promote the formation of bead-like condensation.

[0046] Specifically, in the evaporation zone 7 and the adjacent adiabatic zone 6, the superhydrophilic micro / nano structure enhances the capillary permeability of the liquid working fluid, accelerating the directional transport of liquid from the condensation zone 5 to the evaporation zone 7 and preventing localized drying in the evaporation zone 7 due to insufficient working fluid. In the upper layer of the condensation zone 5 and the adjacent adiabatic zone 6, the superhydrophobic micro / nano structure reduces the liquid film coverage area, causing the condensate to rapidly detach from the surface in the form of discrete droplets, thus reducing the condensation heat transfer thermal resistance. Simultaneously, the superhydrophilic structure in the lower layer of the condensation zone 5 and the superhydrophobic structure in the upper layer form a surface energy gradient, driving the condensate to migrate from low-energy regions to high-energy regions, further improving the working fluid circulation efficiency.

[0047] Compared to existing technologies, traditional vapor chamber wicks typically employ a single wettability structure, failing to simultaneously address the requirements of enhanced capillary force at the evaporation end and rapid droplet detachment at the condensation end. In existing technologies, the condensation zone 5 often suffers from reduced heat transfer efficiency due to continuous liquid film coverage. In contrast, this solution utilizes a partitioned design with both superhydrophilic and superhydrophobic structures to optimize the condensate discharge path while maintaining high capillary force.

[0048] Through the above technical solution, this application effectively solves the problem of reduced working fluid reflux rate and condensate retention caused by insufficient thickness of the liquid wick after the thickness of the ultrathin heat spreader plate is reduced. By driving with surface energy gradient and controlling zoned wettability, efficient circulation of liquid working fluid is achieved, improving the heat transfer limit and reducing condensation thermal resistance.

[0049] Further optimizing the design, the biomimetic capillary wick 41 has alternating triangular serrated structures 42 on both sides of the upper part of the superhydrophobic micro / nano structure of the primary liquid-absorbing wick 3. The triangular serrated structures 42 are periodic concave-convex contours formed along the edges of the capillary wick, which can be achieved through laser cutting or chemical etching. This structure guides the directional migration of droplets through surface tension gradients. The superhydrophobic micro / nano structure is a micro-rough surface with a contact angle greater than 150 degrees, which can be formed by anodic oxidation combined with fluorosilane modification. This structure can reduce droplet adhesion and promote a rolling effect.

[0050] Specifically, in condensation zone 5, after droplets form on the surface of the superhydrophobic micro / nano structure, a local capillary pressure difference is generated at the triangular serrated tips. This pressure difference causes the droplets to move directionally towards evaporation zone 7 along the serration direction, while the recessed areas between adjacent serrations form liquid film transport channels. Through the periodically arranged serrated structure, a continuous surface energy gradient field can be established, effectively overcoming the droplet retention phenomenon present in traditional planar structures.

[0051] Compared to existing technologies, conventional vapor chambers typically employ straight or curved capillary edges, failing to create an effective droplet guiding mechanism. This solution addresses this by constructing an asymmetric serrated structure on both sides of the superhydrophobic region, creating a spontaneous droplet migration path and preventing condensate buildup and blockage at the capillary edge. Based on this structure, this application effectively solves the problem of increased thermal resistance caused by condensate retention in ultrathin vapor chambers under extreme thickness conditions. The structured surface morphology design enhances the reflux driving force of the liquid working fluid, thereby improving phase change heat transfer efficiency. This solution is particularly suitable for micro vapor chamber applications with a thickness of less than 0.6 mm.

[0052] Further optimization of the design involves an ultrathin heat spreader based on a biomimetic capillary core, where the porous surface of the biomimetic secondary wick 4 possesses a superhydrophilic micro / nano structure. The porous surface of the biomimetic secondary wick 4 is a porous medium surface formed through micron- or nano-scale processing, specifically achieved through laser etching, chemical deposition, or electrochemical anodizing. This structure enhances capillary forces and expands the contact area of ​​the liquid working fluid. The superhydrophilic micro / nano structure is a micro-roughened structure with a surface contact angle of less than 10 degrees, specifically achieved through titanium dioxide nanocoating or silane coupling agent modification. This structure reduces liquid flow resistance and accelerates the permeation and diffusion of the working fluid within the pores.

[0053] Specifically, after the porous surface of the biomimetic secondary wicking core 4 is covered with a superhydrophilic micro / nano structure, a high capillary force driving path is formed in the condensation zone 5. When the vapor working fluid condenses into liquid in the condensation zone 5, the superhydrophilic surface rapidly adsorbs the liquid film into the pores through capillary action, while the surface energy gradient promotes the directional migration of the liquid towards the evaporation zone 7. This structure, together with the superhydrophobic region of the primary wicking core 3, forms a surface tension difference, further enhancing the working fluid circulation efficiency, significantly improving capillary pumping capability, and optimizing the liquid film distribution morphology to avoid excessive accumulation of condensate in local areas.

[0054] Further optimization of the scheme involves using one or more of the following materials for the primary liquid-absorbing core 3 and / or the biomimetic secondary liquid-absorbing core 4: sintered copper powder, wire mesh, and copper foam. The sintered copper powder is a porous material with a continuous pore network formed by bonding copper powder particles together using a high-temperature sintering process. In one specific embodiment, copper powder with a particle size of 50-200 micrometers can be sintered in a reducing atmosphere, and its porosity can be controlled within the range of 40%-70%, thereby achieving a balance between high capillary force and liquid permeation rate. The wire mesh is a multi-layered mesh structure woven from metal wires. Specifically, it can be formed by stacking and pressing copper wire mesh with a mesh size of 100-400. By adjusting the weaving density and number of layers, the pore distribution is optimized, thereby reducing liquid flow resistance. The copper foam is a three-dimensional interconnected porous metal material prepared by electrochemical deposition or gas foaming. Specifically, it can use a copper foam matrix with a pore size of 0.05mm-0.2mm. Its high specific surface area and interconnected channels can simultaneously enhance capillary suction capacity and vapor diffusion efficiency.

[0055] Specifically, in the ultrathin vapor chamber, a primary wick 3 is laid on the bottom surface of the cavity, and a biomimetic secondary wick 4 covers it. When sintered copper powder is used as the wick material, its uniformly distributed micron-sized pores can quickly guide the liquid working fluid from the condensation zone 5 to the evaporation zone 7 through capillary action. If a multi-layer copper wire mesh is used, an anisotropic pore structure can be formed by adjusting the stacking direction of the mesh layers, preferentially increasing the liquid transport rate in the evaporation zone 7. When foamed copper is used, its three-dimensional through-holes can reduce vapor flow resistance, while the superhydrophilic surface treatment enhances capillary force. The above materials can be applied individually or in combination to the primary wick 3 and the biomimetic secondary wick 4. By optimizing the porosity, pore size distribution, and permeability matching, the synergistic control of capillary force and flow resistance can be achieved in the ultrathin space. Through the combined application of sintered copper powder, wire mesh, and foamed copper in this solution, a complementary effect can be formed through differentiated pore structures. For example, the high porosity of sintered copper powder can enhance capillary pressure, the layered structure of the wire mesh can directionally guide the liquid, and the foamed copper can reduce the pressure drop of the vapor flow. The synergistic effect of the three can overcome the contradiction between capillary force and flow resistance under ultra-thin conditions.

[0056] Further optimization of the design involves using the same material for both the upper cover plate 1 and the lower cover plate 2: metal, which possesses high thermal conductivity and high mechanical strength. Specifically, copper, aluminum, or stainless steel can be used. These materials effectively transfer heat while ensuring structural strength. The use of the same material and casting process for both the upper cover plate 1 and the lower cover plate 2 ensures consistency in the coefficient of thermal expansion, preventing structural deformation or sealing failure due to temperature changes.

[0057] Further optimization of the design involves using copper, aluminum, or stainless steel for the upper cover plate 1 and lower cover plate 2. Copper is a metallic material composed of pure copper or copper alloys, specifically rolled or stamped copper plates. Its high thermal conductivity facilitates rapid heat transfer within the heat spreader. Aluminum is a metallic material composed of pure aluminum or aluminum alloys, specifically anodized or forged aluminum plates. Its lightweight properties reduce the overall weight of the heat spreader. Stainless steel is an alloy steel containing more than 10.5% chromium, specifically 304 or 316L stainless steel. Its high strength and corrosion resistance enhance the structural stability of the heat spreader.

[0058] In some specific embodiments, the thickness of the copper plate can be controlled within the range of 0.08 mm to 0.15 mm, and the cavity structure is formed by chemical etching; the aluminum plate can be made of 5052 aluminum alloy, and a surface insulating layer is formed by micro-arc oxidation treatment; the stainless steel plate can be encapsulated in a protective gas environment using laser welding technology.

[0059] Further optimization of the design involves using one of the following liquid working fluids: water, acetone, or an alcohol. The liquid working fluid is the medium through which heat transfer occurs within the vapor chamber via a phase change cycle. Specifically, substances with different boiling points, surface tensions, and latent heats of vaporization can be used. For example, water has high thermal conductivity and high latent heat of vaporization, making it suitable for medium- to high-temperature heat dissipation scenarios; its high latent heat of vaporization can improve heat transfer efficiency per unit volume. Acetone has a low boiling point and high volatility, making it suitable for low-temperature or rapid heat dissipation requirements; its low boiling point can accelerate the phase change cycle rate. Alcohols achieve a balance between surface tension and viscosity, helping to reduce flow resistance and maintain stable capillary reflux. The selection of these working fluids is based on their physical properties and their compatibility with the operating temperature range of the vapor chamber. By optimizing the synergistic effect of the working fluid and the wick structure, the capillary pressure gradient can be enhanced, and the liquid reflux dynamics can be improved.

[0060] The working principle of this invention is as follows: The liquid working fluid evaporates into vapor on the side of the biomimetic secondary capillary evaporation zone 7 and at the top of the evaporation zone 7 of the primary wick 3. The vapor diffuses through the cavity between the strip structures of the secondary capillary wick to the adiabatic zone 6 and the condensation zone 5. After condensing into bead-like liquid on the superhydrophobic surface of the condensation zone 5, it flows back to the evaporation zone 7 under the capillary force provided by the superhydrophilic structure of the primary wick 3, the superhydrophilic structure of the secondary capillary wick, and the surface energy gradient between the superhydrophilic structure of the secondary capillary wick and the superhydrophilic structure of the primary wick wick 3, and the cycle continues.

[0061] Compared with existing technologies, traditional vapor chambers mostly use a single working fluid and are not optimized in conjunction with the wick structure, resulting in a limited range of working fluid selection and an inability to adapt to diverse heat dissipation scenarios. This application introduces multiple types of working fluid options and combines them with a superhydrophilic-superhydrophobic composite capillary wick structure, which allows for flexible adjustment of the working fluid type based on the device's heat output, operating temperature, and space constraints, achieving dynamic adaptation of the working fluid properties to the capillary structure.

[0062] Through the above technical solution, this application effectively solves the problem of reduced heat transfer limit caused by insufficient recirculation of the working fluid in ultra-thin heat exchange plates. By matching the surface tension, viscosity, and phase change characteristics of different working fluids, the liquid recirculation efficiency driven by capillary pressure is enhanced, and the droplet shedding speed in the condensation zone 5 is optimized, thereby improving the overall heat dissipation performance while maintaining the ultra-thin structure.

[0063] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0064] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An ultra-thin vapor chamber based on a biomimetic capillary wick, characterized by, include: The lower cover plate (2) is provided with a cavity filled with a liquid working fluid; A primary suction core (3) is laid on the inner bottom surface of the cavity; A biomimetic secondary absorbent core (4) is laid on the top surface of the primary absorbent core (3); The upper cover plate (1) is connected to the top of the lower cover plate (2) and seals the primary liquid-absorbing core (3) and the bionic secondary liquid-absorbing core (4) in the cavity of the lower cover plate (2); The primary liquid-absorbing core (3) and the biomimetic secondary liquid-absorbing core (4) have the same or different porous media structures; The ultrathin heat spreader is divided into an evaporation zone (7), an insulation zone (6), and a condensation zone (5) along its length. The primary liquid absorbent core (3) has a superhydrophilic micro / nano structure on the porous surface of the evaporation zone (7), the primary liquid absorbent core (3) has a superhydrophilic micro / nano structure on the porous surface of the adiabatic zone (6) near the evaporation zone (7), the primary liquid absorbent core (3) has a superhydrophilic micro / nano structure on the lower porous surface of the condensation zone (5), the primary liquid absorbent core (3) has a superhydrophilic micro / nano structure on the lower porous surface of the adiabatic zone (6) near the condensation zone (5), the primary liquid absorbent core (3) has a superhydrophobic micro / nano structure on the upper porous surface of the condensation zone (5), and the primary liquid absorbent core (3) has a superhydrophobic micro / nano structure on the upper porous surface of the adiabatic zone (6) near the condensation zone (5). The biomimetic secondary liquid-absorbing core (4) includes 2-15 biomimetic capillary cores (41) arranged at equal intervals along the width direction of the ultrathin heat spreader; the biomimetic capillary cores (41) have alternating left and right triangular sawtooth structures (42) on both sides of the upper part of the superhydrophobic micro-nano structure of the primary liquid-absorbing core (3).

2. The ultrathin vapor chamber based on a biomimetic capillary wick according to claim 1, characterized in that, The biomimetic capillary core (41) gradually widens from the condensation zone (5) to the evaporation zone (7), forming an isosceles trapezoidal structure.

3. The ultrathin vapor chamber based on the biomimetic capillary wick of claim 1, wherein, The porous surface of the biomimetic secondary liquid-absorbing core (4) has a superhydrophilic micro-nano structure.

4. The ultrathin vapor chamber based on the biomimetic capillary wick of claim 1, wherein, The primary liquid-absorbing core (3) and / or the biomimetic secondary liquid-absorbing core (4) are made of one or more of sintered copper powder, wire mesh, and copper foam.

5. The ultrathin vapor chamber based on the biomimetic capillary wick of claim 1, wherein, The upper cover plate (1) and the lower cover plate (2) are made of the same material, both being metal.

6. The ultrathin vapor chamber based on the biomimetic capillary wick of claim 5, wherein, The upper cover plate (1) and the lower cover plate (2) are made of copper, aluminum or stainless steel.

7. The ultrathin vapor chamber based on a biomimetic capillary wick according to claim 1, characterized in that, The liquid working medium is one of water, acetone, alcohol, or aqueous solution of alcohol.

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