Asymmetric bionic texture pyramid microcolumn array device for enhancing thin film evaporation

Abstract

The invention relates to an asymmetric bionic texture pyramid micro-column array device for enhancing film evaporation, the device can stably transport a coolant and expand the effective evaporation area, and the device specifically comprises: a micro-column unit, the top of which is made of a hydrophobic material and the side wall of which is subjected to hydrophilic treatment and has a textured structure; the micro-column array is composed of micro-column units which are asymmetrically arranged, and the wetting perimeter, period and gradient of the micro-column array are subjected to accurate optimization design; in addition, according to the micro-column array, the capillary transport efficiency of the liquid is further enhanced by adjusting the distance and the height gradient between the micro-columns, and therefore the evaporation area of the thin liquid film is effectively expanded. The top of the micro-column unit is made of a hydrophobic material, the side wall is subjected to hydrophilic treatment and is combined with a micro-texture structure, the distribution and capillary action of liquid are optimized, and the stable transportation capacity of the liquid on the surface of the micro-column is remarkably improved. The device has excellent heat dissipation performance while improving the liquid transportation efficiency and the thin film evaporation performance, and is widely applied to the high-heat-flux fields such as efficient heat dissipation and microelectronic cooling.

Description

Technical Field

[0001] The present invention relates to the field of phase change heat dissipation cooling for systems on a chip, and particularly to an asymmetric bionic texture pyramid micro-column array device for enhancing thin-film evaporation. Background Art

[0002] As an efficient thermal management technology, thin-film evaporation is widely used in on-chip cooling systems, especially suitable for phase change heat exchangers such as heat pipes and heat spreaders. Compared with the traditional boiling process, thin-film evaporation has better controllability and can provide more stable thermal management in complex systems. In on-chip cooling, the efficiency of thin-film evaporation is closely related to the wick design and optimization of the evaporator. By designing the thin-film evaporation area on the microstructure surface, high capillary pressure can be generated at the liquid-gas interface, thereby promoting the transport of liquid and improving the heat dissipation efficiency. The effective evaporation zone is located at the liquid meniscus and within the gas-liquid-solid three-phase contact zone, usually a thin-film area with a thickness of a few micrometers, having low thermal resistance and high heat transfer efficiency, significantly improving the thermal management performance, especially suitable for on-chip cooling systems with high power density.

[0003] Most traditional thin-film evaporation microstructures are two-dimensional and symmetric structures. Although these structures can promote the adsorption and transport of liquid to a certain extent, due to the lack of sufficient complexity and diversity, they cannot fully optimize the liquid transport process at the microscale. The existing microstructure surfaces are usually too smooth, lacking sufficient roughness and structural complexity, which limits the wettability and capillary action of the liquid on the surface. Especially in the case of high power density and high heat flux density, the flow and thin-film formation of the liquid are inhibited, thereby affecting the efficiency of the evaporation process. In addition, the existing microstructure design makes the effective evaporation area relatively limited, unable to fully expand the evaporation area, resulting in the restriction of the improvement of the heat dissipation efficiency. Therefore, it is necessary to design a device for enhancing thin-film heat dissipation that can enhance capillary action and expand the area of the effective thin-film evaporation region while maintaining stable liquid transport, so as to improve the evaporation heat dissipation efficiency. Summary of the Invention

[0004] To solve at least some problems such as low coolant backflow efficiency, limited evaporation area, and unstable liquid film in the prior art, the present invention provides a micro-column array thin-film evaporation heat dissipation device and its preparation method that can stably transport coolant and expand the area of the effective evaporation zone, including:

[0005] Micro-column units, which include various geometric structures such as cylinders, cones, frustums of cones, pyramids, prisms, rectangular ribs, spheres, catenoid surfaces, and gradient cubes;

[0006] A micro-column array, in which the micro-column units are arranged in an asymmetric pyramid structure, that is, the micro-column units are regularly arranged in rows and columns, and the height increases linearly in a gradient manner from the edge of the array to the center, and the diameter and spacing of the micro-columns remain unchanged;

[0007] A working medium, which is filled in the capillary channels between the micro-column arrays;

[0008] The top of the micro-column unit is made of a hydrophobic material, and the side walls are treated hydrophilically and have a micro-nano texture structure, forming a wetting difference with a hydrophobic top and hydrophilic side walls to strengthen capillary action and improve the stable transport ability of the coolant on the micro-column surface;

[0009] The micro-column array improves the capillary transport efficiency of the coolant through structural parameter optimization (such as height gradient, arrangement density, spacing, etc.), thereby significantly expanding the effective evaporation area of the thin liquid film.

[0010] Furthermore, the diameter of the micro-column unit is 20 - 500 μm, the height is 10 - 500 μm, and the micro-column spacing is 0.1 - 4 times its diameter.

[0011] Furthermore, in the asymmetric pyramid structure, the height of the micro-columns increases linearly from the edge of the array to the center and forms a height peak in the middle, and the array is arranged in a circular symmetry or matrix pattern.

[0012] Furthermore, the arrangement period and structural density of the micro-column array are optimized to achieve a uniformly distributed liquid coverage in different heat flux density regions.

[0013] Furthermore, the contact angle of the top of the micro-column is greater than the contact angle of the side wall by °, the contact angle of the side wall ranges from 20 - 60°, the hydrophobic layer is a metal, silane compound or fluoride coating, and the hydrophilic layer is an oxide layer formed by plasma treatment or acid-base treatment.

[0014] Furthermore, a periodic concave-convex texture structure can be constructed on the surface of the micro-column unit, the texture patterns include striped, honeycomb, dot array, etc., the roughness Ra is 0.1 - 5 μm, and the characteristic size is 500 nm - 20 μm.

[0015] Furthermore, the surface texture structure of the micro-column is formed by 3D printing, laser etching, plasma etching, gray-scale lithography, etc.

[0016] Furthermore, the capillary channels formed by the micro-column array are a continuous open network structure, which has the ability of liquid redistribution and can effectively maintain the stable liquid supply of the evaporation liquid film.

[0017] Further, the working medium is deionized water, alcohol, fluorinated liquid or other low-boiling-point phase change liquids, and the filling amount accounts for 10%-90% of the volume of the microcolumn array cavity.

[0018] Further, the microcolumn material is silicon, metal, photosensitive polymer, photoresist, resin or 3D printing compatible material, and the processing technology selects a compatible method according to the material properties.

[0019] Further, the hydrophilic treatment is oxygen plasma treatment for 5-20 min or etching with dilute acid or base for 10-15 min; the hydrophobic treatment uses a silane or fluorinated treatment agent with a concentration of 3-6 mmol / L and reacts at room temperature for 10-20 min.

[0020] Further, the array can be designed with a regionalized structural isomerism according to the heat flux density distribution of the heat source. The microcolumn height and density are enhanced in the high heat flux region, and relatively sparse in the low heat flux region, so as to achieve heat matching optimization and enhance the regionalized heat dissipation performance.

[0021] Further, the top and side walls of the microcolumn unit further include nanoscale rough structures, which together with the microscale geometric morphology form a dual-scale structure for enhancing the capillary transport capacity and evaporation efficiency.

[0022] Further, the nanostructure is a nanoscale protrusion, nanopore or nanogroove, and the characteristic size is 10 nm to 500 nm. The structure is formed by plasma etching, self-assembly, two-photon lithography or chemical etching.

[0023] Further, to enhance the liquid distribution ability in the capillary channel, a liquid guiding groove structure is arranged on the microcolumn array substrate for quickly back-feeding the coolant to realize the redistribution of the liquid film, thereby preventing the generation of dry spots and maintaining the continuity of the evaporation film.

[0024] Further, the surface contact angle of the liquid guiding groove is lower than the average surface contact angle of the microcolumn array to form a surface energy gradient, thereby enhancing the spontaneous directional flow ability of the coolant.

[0025] The present invention has at least the following beneficial effects:

[0026] (1) Through the design of the microcolumn array arranged in an asymmetric pyramid structure, the capillary transport capacity of the coolant is significantly enhanced, realizing long-distance, fast and stable liquid directional transport, and expanding the effective evaporation area;

[0027] (2) The wetting gradient design with a hydrophobic top and a hydrophilic side wall of the microcolumn, and the micro-nano scale cooperative structure enhance the pinning effect of the three-phase contact line, effectively improving the liquid film stability and liquid supply efficiency;

[0028] (3) Compared with the traditional uniform micro - structure array, the array of the present invention can be heterogeneously designed according to the change of heat flux, forming a dense high - pillar array in the local high - heat area to meet the heat - matching requirements and improve the overall heat - transfer uniformity.

[0029] (4) Through the design of liquid - guiding grooves or capillary network structures, the rapid redistribution ability of the coolant in the array area is realized, reducing the risk of dry spots and adapting to complex heat - load scenarios.

[0030] (5) The structure manufacturing process is flexible, compatible with a variety of micro - nano processing technologies and materials, suitable for batch manufacturing requirements in multiple scenarios. The preparation method of the surface functional layer is simple and highly controllable, with good process adaptability and industrial feasibility.

[0031] In summary, the present invention proposes a micro - pillar array thin - film evaporation heat - dissipation device with highly integrated structure and surface function, stable liquid transport, and significant evaporation - enhancement effect. It is particularly suitable for heat - management fields such as high - heat - flux - density electronic components, chips, lasers, etc., and has broad application prospects and engineering practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To further clarify the above and other advantages and features of the embodiments of the present invention, a more specific description of the embodiments of the present invention will be presented with reference to the accompanying drawings. It can be understood that these drawings only depict typical embodiments of the present invention and will not be considered as limiting its scope. In the drawings, for clarity, the same or corresponding components will be denoted by the same or similar reference numerals.

[0033] Figure 1 The top - view structure diagram of a micro - pillar array thin - film evaporation heat - dissipation device according to an embodiment of the present invention is shown, with the regular row - and - column arrangement of micro - pillar units and the illustration of the micro - pillar diameter and spacing.

[0034] Figure 2 The three - dimensional structure schematic diagram of a micro - pillar array thin - film evaporation heat - dissipation device according to an embodiment of the present invention is shown, where the height of the micro - pillars changes in a gradient from the outside to the inside.

[0035] Figure 3 The three - dimensional structure schematic diagram of another micro - pillar array thin - film evaporation heat - dissipation device according to an embodiment of the present invention is shown, where the micro - pillars are arranged in a wave - like pattern with alternating high and low.

[0036] Figure 4 The three - dimensional schematic diagram of a micro - pillar unit according to an embodiment of the present invention is shown, demonstrating the surface - function distribution of hydrophobic top and hydrophilic side walls.

[0037] Figure 5 The schematic diagram of the periodic concave - convex texture structure that can be constructed on the side - wall surface of a micro - pillar unit according to an embodiment of the present invention is shown.

[0038] Figure 6 Shows a process flow sectional view of a microcolumn array according to an embodiment of the present invention, which forms microjunctions by using a pixelated gray mask and a gray lithography exposed negative resist technology;

[0039] Figure 7 Shows a schematic plan view of a pixelated gray mask according to an embodiment of the present invention;

[0040] Figure 8 Shows a functional structure diagram of regional heterogeneous design (layout differences under different heat flux densities) in a microcolumn array according to an embodiment of the present invention, which includes a liquid guiding groove and a capillary transport fine core structure. Specific embodiments

[0041] It should be noted that the components in each drawing may be exaggerated for illustration purposes and are not necessarily to scale.

[0042] In the present invention, each embodiment is only intended to illustrate the solution of the present invention and should not be construed as restrictive.

[0043] In the present invention, unless otherwise specified, the quantifiers "a" and "one" do not exclude the scenario of multiple elements.

[0044] It should also be noted here that in the embodiments of the present invention, for clarity and simplicity, only a part of the components or assemblies may be shown. However, those of ordinary skill in the art can understand that, under the teaching of the present invention, the required components or assemblies can be added according to the specific scenario needs.

[0045] It should also be noted here that within the scope of the present invention, the terms "same", "equal", "equivalent", etc. do not mean that the two values are absolutely equal, but allow a certain reasonable error. That is to say, these terms also cover "substantially the same", "substantially equal", "substantially equivalent".

[0046] It should also be noted here that in the description of the present invention, the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than explicitly or implicitly indicating that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as explicitly or implicitly indicating relative importance.

[0047] In addition, the embodiments of the present invention describe the process steps in a specific order. However, this is only for the convenience of distinguishing each step and does not limit the sequence of the steps. In different embodiments of the present invention, the sequence of each step can be adjusted according to the process requirements.

[0048] As Figure 1 shown, this embodiment provides a micro-column array thin-film evaporation heat dissipation device manufactured based on 3D printing resin. The structural design and manufacturing process of the device are as follows:

[0049] Use photosensitive resin, which has good mechanical strength, thermal stability, and can be accurately formed by photocuring 3D printing technology. The manufacturing material can also be other 3D printing compatible materials.

[0050] Through photocuring 3D printing technology, the resin material is printed layer by layer into a micro-column array 1 structure. The diameter 3 of the micro-column unit 2 is 20 - 500 μm, the height is 10 - 500 μm, and the micro-column spacing 4 is 0.1 - 4 times its diameter. The arrangement of the micro-column array adopts a regular row and column arrangement (as Figure 1 shown), and the arrangement mode of each micro-column unit is adjusted according to requirements to form a continuous and regular capillary channel network (as Figure 2 , 3 shown).

[0051] The top 5 of the micro-column forms a relatively hydrophobic surface by electron beam evaporation of the Ti / Au metal layer, and the contact angle range is 60 - 70° (as Figure 4 shown).

[0052] The side wall 6 of the micro-column forms a hydrophilic surface by plasma treatment, and the contact angle is 20 - 30° (as Figure 4 shown).

[0053] To enhance the capillary force and improve the liquid distribution uniformity, a micro-texture structure 7 needs to be processed on the side wall of the micro-column, as Figure 5 shown. The side wall of the 3D printed unit micro-column structure forms a regular periodic striation structure, and the texture feature size on the surface of the micro-column can be adjusted arbitrarily according to the processing resolution.

[0054] The working medium of this embodiment is deionized water.

[0055] In the above and other embodiments of the present invention, the capillary transport efficiency of the liquid in the micro-column array can be further enhanced by adjusting the micro-column spacing, diameter, height gradient difference, etc.

[0056] As Figure 6 shown, this embodiment provides a micro-column array thin-film evaporation heat dissipation device manufactured by gray-scale lithography technology. The device manufactures precise micro-column structures through high-precision lithography technology.

[0057] Select a silicon-based substrate 8, first clean the surface and remove the oxide layer.

[0058] Use a negative photoresist 9, model AZ5214E. This photoresist has strong photosensitivity and is suitable for the fabrication of fine structures.

[0059] Coat a uniform layer of photoresist on the silicon-based substrate and expose it using a pixelated grayscale mask 10, as Figure 7 shown.

[0060] By controlling the exposure intensity of the DWL66+ multifunctional laser direct writer, a microcolumn array with different heights is formed. The diameter of the microcolumns can be adjusted, the height changes linearly, and the spacing can be 0.5 - 3 times the diameter of the microcolumns.

[0061] After exposure, the unexposed photoresist is removed by a developer AZ400K with a 1:4 ratio, forming an accurate microcolumn structure.

[0062] Lateral etching is used to process the sidewalls of the microcolumns, forming small pits or striped textures, thus providing more interfaces when the liquid contacts the surface, improving the wettability and capillary transport ability of the liquid. These rough structures help improve the liquid flow efficiency, reduce bubble retention, and enhance the evaporation performance.

[0063] As Figure 8 shown, this embodiment provides a thin-film evaporation heat dissipation device that optimizes the microcolumn array through regional heterogeneous design. The device adjusts the arrangement and structure of the microcolumn array according to the change of heat flux density in different regions.

[0064] In the high heat flux density region, a high-density and high-height microcolumn array is used. The diameter of the microcolumns is 50 μm, the height is 500 μm, and the spacing is 1.5 times the diameter of the microcolumns.

[0065] In the low heat flux density region (such as the edge region), a low-density and lower-height microcolumn array is used. The diameter of the microcolumns is 50 μm, the height is 200 μm, and the spacing is 2 times the diameter of the microcolumns.

[0066] A liquid guiding groove ( Figure 8 shown in 11) is set on the microcolumn array substrate for optimizing liquid distribution.

[0067] The liquid absorption core channel ( Figure 8 shown in 12) improves the liquid transport efficiency by designing a capillary transport fine core structure.

[0068] Although some embodiments of the present invention have been described in this application document, those skilled in the art can understand that these embodiments are merely shown as examples. Those skilled in the art can conceive of numerous variations, alternatives, and improvements without departing from the scope of the present invention under the teaching of the present invention. The appended claims are intended to define the scope of the present invention and thereby cover the methods and structures within the scope of these claims themselves and their equivalent transformations.

Claims

1. An asymmetric bionic texture pyramid microcolumn array device for enhancing thin film evaporation, characterized in that Comprising: Micro-column units and a micro-column array, where the micro-column array is arranged on a substrate in an asymmetric pyramid structure by the micro-column units. Among them, the micro-column units are regularly arranged in rows and columns, with the height changing linearly in a gradient from the outside to the inside, and the micro-column diameter and spacing remaining unchanged; A working medium filled in the capillary channels between the micro-column units; The side walls of the micro-column units are hydrophilic and have a micro-texture structure, and the top is relatively hydrophobic compared to the side walls, strengthening the capillary action.

2. The asymmetric bionic texture pyramid micro-column array device for enhanced thin-film evaporation according to claim 1, wherein The diameter of the micro-column units is 20 - 500 μm, the height is 10 - 500 μm, and the micro-column spacing is 0.1 - 4 times its diameter; the micro-column height increases linearly along the direction from the edge to the center of the array and forms a height peak in the middle, and the array is arranged in a circular symmetry or matrix pattern; the arrangement period and structural density of the micro-column array are optimized to evenly distribute the liquid in different heat flux density regions.

3. The asymmetric bionic texture pyramid microcolumn array device for enhanced thin film evaporation according to claim 1, wherein The contact angle at the top of the micro-column is greater than the contact angle of the side wall, and the contact angle of the side wall ranges from 20° to 60°; the hydrophobic layer is a metal, silane compound or fluoride coating, and the hydrophilic layer is an oxide layer formed by plasma treatment or acid-base treatment.

4. The asymmetric bionic texture pyramid micro-column array device for enhanced thin-film evaporation according to claim 1, characterized in that, The micro-texture structure on the side walls of the micro-column units is a periodic concave-convex structure, and the structural forms include striped, dot-shaped or honeycomb-shaped distributions; the characteristic size of the surface texture of the micro-column is 500 nm to 20 μm, and the surface roughness Ra is between 0.1 - 5 μm; the micro-column surface texture structure is formed by 3D printing, laser etching, plasma etching, grayscale lithography, etc.

5. The asymmetric bionic texture pyramid micro-column array device for enhanced thin-film evaporation according to claim 1, characterized in that, The capillary channels formed by the micro-column array are a continuous open network structure; the working medium is deionized water, alcohols, fluorinated liquids or other low-boiling-point phase-change liquids, and the filling amount accounts for 10% - 90% of the cavity volume of the micro-column array.

6. A method for preparing the asymmetric bionic texture pyramid micro-column array device for enhanced thin film evaporation according to claim 1, characterized in that, Comprising: Using grayscale lithography, deep silicon etching, two-photon lithography, 3D printing or electroplating technology to prepare a micro-column array structure on a substrate; performing hydrophobic treatment on the top surface of the micro-column, hydrophilic modification on the side walls, and introducing a micro-nano texture structure.

7. The method according to claim 6, wherein The micro-column material is silicon, metal, photosensitive polymer, photoresist, resin or 3D printing compatible material, and the processing technology selects a compatible method according to the material properties; The hydrophilic treatment is oxygen plasma treatment for 5 - 20 min or etching with dilute acid and alkali for 10 - 15 min; the hydrophobic treatment uses a silane or fluorination treatment agent with a concentration of 3 - 6 mmol / L and reacts at room temperature for 10 - 20 min.

8. The asymmetric bionic texture pyramid micro-column array device for enhanced thin film evaporation according to claim 1, characterized in that The micro-column array is provided with micro-columns of different heights, arrangement densities or diameters along different regions according to the heat flux density distribution characteristics of the target heat source; the top and side walls of the micro-column units further include nano-scale rough structures, which cooperate with the micro-scale geometric morphology to form a dual-scale structure for enhancing the capillary transport capacity and evaporation efficiency; the array substrate is provided with a liquid guiding groove or a guiding channel network communicating with the capillary channels between the micro-columns.

9. The asymmetric bionic texture pyramid micro-column array device for enhanced thin-film evaporation according to claim 8, characterized in that, The nano-structure is nano-protrusions, nano-pores or nano-grooves, and the characteristic size is 10 nm to 500 nm, and the structure is prepared and formed by plasma etching, self-assembly, two-photon lithography or chemical etching methods.

10. The asymmetric bionic texture pyramid microcolumn array device for enhancing thin film evaporation according to claim 8, wherein The surface contact angle of the liquid guide groove is lower than the average surface contact angle of the micro-column array, forming a surface energy gradient.

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