Hydrophilic-hydrophobic composite wetting microstructure vapor chamber and method of manufacturing the same

Abstract

The application provides a hydrophilic-hydrophobic composite wetting microstructure steam cavity and a manufacturing method thereof, and relates to the technical field of heat dissipation devices. The hydrophilic-hydrophobic composite wetting microstructure steam cavity comprises an evaporation end and a condensation end, the surface of the evaporation end comprises a microchannel hydrophilic area and a microarray hydrophilic area, the microchannel hydrophilic area surrounds the microarray hydrophilic area; the surface of the condensation end comprises spaced condensation hydrophilic areas and condensation hydrophobic areas, and the evaporation end and the condensation end are assembled to form a flat plate structure with a cavity in the middle. The different wetting surfaces of the condensation hydrophilic areas and the condensation hydrophobic areas are combined, nucleation and condensation can be quickly realized, dropwise condensation heat transfer of the condensation hydrophobic areas is combined with rapid liquid drop-off, capillary suction of the evaporation end microchannel hydrophilic area is combined with rapid liquid discharge, the working medium condensation heat transfer is strengthened, the liquid backflow circulation is accelerated, the temperature uniformity of the hydrophilic-hydrophobic composite wetting microstructure steam cavity is greatly improved, and the microimprinting technology of in-situ heating and pressure forming is adopted to realize batch forming of a large-area microstructure functional surface.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation devices, and in particular to a hydrophilic-hydrophobic composite wetting microstructure steam chamber and a manufacturing method thereof. Background Art

[0002] Currently, capillary wicks within vapor chambers are key to achieving phase change heat transfer. These include sintered, wire mesh, and grooved microstructures. The grooved microstructure is more stable and reliable, and its microstructured functional surface with adjustable wettability can enhance the condensation / boiling heat transfer of working fluids in heat dissipation devices such as vapor chambers. However, current vapor chamber microstructured functional surfaces are still primarily based on either a single hydrophilic or hydrophobic structure. Both these microstructured surfaces have different drawbacks. On fully hydrophobic surfaces, droplets easily shed, forming droplet-like condensation, resulting in higher heat transfer efficiency but a low nucleation rate, hindering rapid nucleation and condensation cycles. On fully hydrophilic surfaces, the nucleation energy barrier is low, increasing the droplet nucleation rate. However, untimely removal of condensate can easily flood the condensation surface, leading to large-area film-like condensation and deteriorating heat transfer performance. Furthermore, currently, microstructured surfaces are mostly fabricated using micromachining, laser micro-nanoprocessing, and other processing methods. These methods are extremely costly and inefficient for fabricating microstructures on material surfaces. Summary of the Invention

[0003] The present invention aims to solve the problem that droplets on a fully hydrophobic surface easily fall off, which is not conducive to a rapid nucleation and condensation cycle, and that the nucleation energy barrier on a fully hydrophilic surface is small, which deteriorates the heat transfer effect.

[0004] To this end, the present invention provides a hydrophilic-hydrophobic composite wetting microstructure steam chamber, comprising an evaporation end and a condensation end, the evaporation end and the condensation end being arranged opposite to each other, wherein:

[0005] The surface of the evaporation end facing the condensation end includes a microchannel hydrophilic area and a microarray hydrophilic area, the microchannel hydrophilic area surrounds the microarray hydrophilic area, the microchannel hydrophilic area has microchannels, and the directions of the microchannels all lead to the microarray hydrophilic area; and

[0006] The surface of the condensation end facing the evaporation end includes a plurality of trapezoidal ridges arranged at intervals, and a V-shaped groove is formed between adjacent trapezoidal ridges. The upper bottom surface of the trapezoidal ridges is a condensation hydrophobic area, and the surface of the V-shaped groove is a condensation hydrophilic area.

[0007] The evaporation end and the condensation end are assembled to form a flat plate structure with a cavity in the middle.

[0008] Optionally, a support column is further included, with the two ends of the support respectively abutting against the evaporation end and the condensation end.

[0009] Optionally, it also includes a shell, which is a flat structure, the evaporation end is located at the inner bottom of the shell, and the condensation end is located at the inner top of the shell. The surfaces of the evaporation end and the condensation end are provided with grooved liquid absorption cores, and the grooved liquid absorption cores at least partially absorb the liquid working medium.

[0010] Optionally, the cross section of the trapezoidal edge perpendicular to the V-shaped groove is an isosceles trapezoidal structure, wherein the upper base length of the isosceles trapezoidal structure is 100-500 μm, the lower base length of the isosceles trapezoidal structure is 500-1000 μm, and the base angle of the isosceles trapezoidal structure is 70-85 degrees.

[0011] Optionally, the contact angle of the surface of the condensation hydrophobic area is ≥140°, and the contact angle of the surface of the V-shaped groove of the condensation hydrophilic area is ≤10°.

[0012] Optionally, the hydrophilic region of the microarray has a tapered microarray structure.

[0013] Optionally, the width of the microchannel is 100-500 μm, and the aspect ratio of the microchannel is 2-3.

[0014] Optionally, the contact angle of the surface of the hydrophilic region of the microchannel is ≤10°, and the contact angle of the surface of the hydrophilic region of the microarray is ≤10°.

[0015] The present invention also provides a method for preparing a hydrophilic-hydrophobic composite wetting microstructure steam cavity. The method comprises the following steps:

[0016] S1. Preparation of blanks for the condensation end and the evaporation end: Select metal materials and process them into sheet blanks;

[0017] S2. Microstructure embossing of the condensing end and the evaporating end: Using micro-embossing technology, trapezoidal edges and V-shaped grooves are prepared on the plate blank to produce the condensing end; using micro-embossing technology, micro-channels and micro-arrays are prepared on the plate blank to produce the evaporating end;

[0018] S3, overall hydrophobic modification of the condensation end: using a hydrophobic silica-methanol-ethanol mixed solution for surface hydrophobic modification;

[0019] S4. Hydrophilic modification of the condensation hydrophilic area: A striped photomask is attached to the condensation hydrophobic area to shield the condensation hydrophobic area from light. Laser scanning of the condensation hydrophilic area induces surface hydrophilic modification of the condensation hydrophilic area to obtain a hydrophilic-hydrophobic composite wetting microchannel condensation end.

[0020] S5. Overall hydrophilic modification of the evaporation end: Laser scanning the evaporation end surface induces hydrophilic modification of the evaporation end surface;

[0021] S6. Assembly: The evaporation end and the condensation end are assembled to form a hydrophilic-hydrophobic composite wetting microstructure steam cavity with a cavity in the middle.

[0022] Optionally, in step S4 and step S5, the energy density of the laser scanning is 12.0-18.0 J / cm 2 , the scanning speed is 1000-2000mm / s.

[0023] Compared with the prior art, the beneficial effects of the hydrophilic-hydrophobic composite wetting microstructure steam chamber and its manufacturing method of the present invention are as follows: the condensation end surface includes condensation hydrophilic areas and condensation hydrophobic areas distributed at intervals, the V-shaped groove is the condensation hydrophilic area, and the upper bottom edge of the trapezoidal structure is the condensation hydrophobic area. The steam first condenses and nucleates in the condensation hydrophilic area, and the liquid increases and spreads, and is sucked back under the action of capillary force. At the same time, the condensation hydrophobic area also condenses to form droplets, and the small droplets will fall off directly to form droplet-shaped condensation heat transfer. The droplet-shaped condensation heat transfer efficiency is much greater than the film-shaped condensation heat transfer efficiency. Droplets with too large diameters that do not fall off in time contact the condensation hydrophilic area. Because the condensation hydrophobic area is located at the upper bottom edge of the trapezoidal structure, the junction of the condensation hydrophobic area and the condensation hydrophilic area is a trapezoidal obtuse angle, which causes the droplets contacting the condensation hydrophilic area to be easily discharged by capillary force, reducing The small droplets detach from the diameter, thereby improving the droplet condensation heat transfer performance. The regional combination of the condensation hydrophilic area and the condensation hydrophobic area with alternating distribution optimizes the condensation mode of the condensation end. At the same time, it has the ability of droplet condensation heat transfer and rapid suction and drainage, which enhances the condensation heat transfer and accelerates the reflux of the working fluid. The surface of the evaporation end includes a microchannel hydrophilic area and a microarray hydrophilic area. The microchannel hydrophilic area surrounds the microarray hydrophilic area. The microarray hydrophilic area in the central area stores the liquid working fluid. When the steam liquefies at the condensation end and returns to the evaporation end, it is rapidly sucked by the capillary action of the microchannel. The direction of the microchannel all leads to the microarray hydrophilic area, and the microchannel is radial. The radial microchannel hydrophilic area shortens the suction path, and can quickly suck the liquid to the central microarray hydrophilic area for storage, participate in boiling heat transfer, accelerate the phase change cycle, and improve the heat transfer efficiency. The surfaces with different wettabilities of the condensation hydrophilic area and the condensation hydrophobic area are composited to enable rapid nucleation and condensation. The droplet-like condensation heat transfer with rapid droplet shedding in the condensation hydrophobic area and the rapid liquid drainage by capillary suction in the hydrophilic area of ​​the evaporation end microchannel are combined to enhance the condensation heat transfer of the working fluid, accelerate the liquid reflux circulation, and greatly improve the temperature uniformity of the steam cavity of the hydrophilic-hydrophobic composite wetting microstructure. In addition, the micro-embossing technology of in-situ heating and imprinting is used to realize the batch forming of large-area microstructure functional surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structure of the hydrophilic-hydrophobic composite wetting microstructure steam chamber of the present invention;

[0025] Figure 2 Schematic cross-sectional view of the trapezoidal edge of the condensation end of the present invention;

[0026] Figure 3 Schematic diagram of the surface structure of the condensation end of the hydrophilic-hydrophobic composite wetting microstructure steam cavity of the present invention;

[0027] Figure 4 for Figure 3 A partial enlarged view of part A;

[0028] Figure 5 for Figure 4 A top view of

[0029] Figure 6 This is a schematic diagram of the structure of the present invention in which a mask is attached to the condensation end for laser scanning;

[0030] Figure 7 Schematic diagram of working medium reflux in the microchannel of the evaporation end of the present invention;

[0031] Figure 8 Schematic diagram of the structure of the evaporation end of the hydrophilic-hydrophobic composite wetting microstructure steam chamber of the present invention;

[0032] Figure 9 for Figure 8 A partial enlarged view of part B;

[0033] Figure 10 for Figure 9 Bottom view of

[0034] Figure 11 for Figure 8 A partial enlarged view of part C in the middle;

[0035] Figure 12 for Figure 8 A partial enlarged view of part D in the middle;

[0036] Figure 13 for Figure 8 A partial enlarged view of part E in the middle;

[0037] Figure 14 This is a flow chart of the method for manufacturing the hydrophilic-hydrophobic composite wetting microstructure steam chamber of the present invention;

[0038] Figure 15 It is a structural schematic diagram of the micro-embossing forming device 8 of the present invention.

[0039] In the figure: 1. Evaporation end; 11. Microchannel hydrophilic area; 111. Microchannel; 12. Microarray hydrophilic area; 121. Microarray; 13. Second connection area; 2. Condensation end; 21. Condensation hydrophilic area; 22. Condensation hydrophobic area; 221. Mask; 23. First connection area; 3. Cavity; 4. Support column; 5. Shell; 6. Grooved wick; 7. Working medium; 8. Micro-embossing forming device; 81. Punch; 82. Die; 83. Heating element 84. Power component; 85. Heat insulation board; 861. Upper frame; 862. Lower frame; 87. Guide column; 88. Plate. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0041] It should be noted that in the description of the present invention, the directions or positional relationships indicated by “up”, “down”, “left”, “right”, “top”, “bottom”, “front”, “back”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, it cannot be understood as limiting the scope of protection of the present invention.

[0042] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0043] Moreover, although the present invention is described with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Many modifications can be made to the exemplary embodiments, and other embodiments can be designed. As long as they do not deviate from the core concept and scope of the present invention as defined by the appended claims, they fall within the scope of protection of the present invention.

[0044] To address these issues, the present invention provides a hydrophilic-hydrophobic composite wetting microstructured steam chamber and its manufacturing method, suitable for use in heat dissipation devices and other applications. This steam chamber utilizes phase change heat transfer within the internal liquid medium (7), vapor diffusion, and condensation reflux to dissipate heat from electronic components. This chamber offers excellent thermal conductivity, a large heat transfer area, good temperature uniformity, and high reliability, making it a leading approach to addressing heat dissipation issues in electronic devices.

[0045] like Figures 1 to 7 As shown, the present invention provides a hydrophilic-hydrophobic composite wetting microstructure steam chamber, comprising an evaporation end 1 and a condensation end 2, the evaporation end 1 and the condensation end 2 being arranged opposite to each other, wherein:

[0046] like Figure 7 As shown, the surface of the evaporation end 1 facing the condensation end 2 includes a microchannel hydrophilic area 11 and a microarray hydrophilic area 12. The microchannel hydrophilic area 11 surrounds the microarray hydrophilic area 12. The microchannel hydrophilic area 11 has microchannels 111. The directions of the microchannels 111 all lead to the microarray hydrophilic area 12.

[0047] like Figures 2 to 6As shown, the surface of the condensation end 2 facing the evaporation end 1 includes a plurality of trapezoidal edges arranged at intervals, and a V-shaped groove is formed between adjacent trapezoidal edges. The upper bottom surface of the trapezoidal edge is a condensation hydrophobic area 22, and the surface of the V-shaped groove formed between two adjacent trapezoidal edges is a condensation hydrophilic area 21; wherein, Figure 3 This is a schematic diagram of the partial structure of the surface of the condensation end 2 facing the evaporation end 1. The width of the bottom surface of the trapezoidal ridge and the width of the V-shaped groove on the surface of the condensation end 2 facing the evaporation end 1 are both small, resulting in a dense microchannel structure on the surface of the condensation end 2. Figure 3 The surface diagram of the condensation end 2 is not clear, so the following is attached Figure 3 A partial enlarged view is provided to clearly illustrate the surface of the condensation end 2.

[0048] like Figure 1 As shown, the evaporation end 1 and the condensation end 2 are assembled to form a flat plate structure with a cavity 3 in the middle. Specifically, the evaporation end 1 and the condensation end 2 can be welded up and down to obtain a flat plate structure with a cavity 3 in the middle.

[0049] A "trapezoidal ridge" is an ridge structure with a trapezoidal cross-section. Multiple ridge structures extend in parallel, with V-shaped grooves formed between adjacent ridges. The "upper base surface of a trapezoidal ridge" refers to the plane where the upper base of the trapezoid lies. If a trapezoidal ridge is considered a raised structure, the "upper base surface of a trapezoidal ridge" can also be referred to as the top surface of the ridge structure.

[0050] like Figure 1 As shown, the function of the heat dissipation device is achieved through condensation / boiling heat transfer of the working medium 7 in the steam chamber of the hydrophilic-hydrophobic composite wetting microstructure. The condensation end 2 is composed of alternating condensation hydrophilic areas 21 and condensation hydrophobic areas 22 with different wettability strengths. The V-shaped grooves of the condensation hydrophilic areas 21 form a microchannel structure. The evaporation end 1 is composed of partitioned microchannels 111 and microarrays 121. The surface of the condensation end 2 includes condensation hydrophilic areas 21 and condensation hydrophobic areas 22 distributed at intervals. The V-shaped grooves are the condensation hydrophilic areas 21, and the upper bottom surface of the trapezoidal edges is the condensation hydrophobic area 22. Figure 2As shown, the steam first condenses and nucleates in the condensation hydrophilic area 21, and the liquid increases and spreads, and is sucked back under the capillary force of the V-shaped groove. At the same time, the condensation hydrophobic area 22 also condenses to form droplets, and the small droplets will fall off directly to form droplet condensation heat transfer. The droplet condensation heat transfer efficiency is much greater than the film condensation heat transfer efficiency. Droplets with too large diameters that do not fall off in time contact the condensation hydrophilic area 21. Because the condensation hydrophobic area 22 is located on the upper bottom surface of the trapezoidal edge, the junction of the condensation hydrophobic area 22 and the condensation hydrophilic area 21 is a trapezoidal obtuse angle, which causes the droplets contacting the condensation hydrophilic area 21 to be easily discharged by the capillary force, reducing the droplet detachment diameter, thereby improving the droplet condensation heat transfer performance. The combination of the condensation hydrophilic area 21 and the condensation hydrophobic area 22 with intervals optimizes the condensation mode of the condensation end 2, and has both droplet condensation heat transfer and rapid suction and drainage. The evaporation end 1 surface includes a microchannel hydrophilic area 11 and a microarray hydrophilic area 12. The microchannel hydrophilic area 11 surrounds the microarray hydrophilic area 12. The microarray hydrophilic area 12 in the central area includes an array microstructure for storing the liquid working medium 7. The microchannel hydrophilic area 111 includes a plurality of microchannels radially extending from the microarray hydrophilic area 12 as the center. When the steam liquefies at the condensation end 2 and returns to the evaporation end 1, it is rapidly sucked by the capillary action of the microchannel hydrophilic area 111. The channel extension directions of the microchannel hydrophilic area 111 all lead to the microarray hydrophilic area 12. The microchannel hydrophilic areas 11 radiating to the surrounding areas shorten the suction path, and can quickly suck the liquid to the central microarray hydrophilic area 12 for storage, participate in boiling heat transfer, accelerate the phase change cycle, and improve the heat transfer efficiency.

[0051] Alternatively, as Figure 1 As shown, it also includes a support column 4, both ends of which are respectively in contact with the evaporation end 1 and the condensation end 2.

[0052] like Figure 3 As shown, the surface of the condensation end 2 is provided with a plurality of first connection areas 23 for connecting the support columns 4, such as Figure 8 As shown, the surface of the evaporation end 1 is provided with multiple second connection areas 13 for connecting to support columns 4. The positions of the first connection areas 23 and the second connection areas 13 correspond to each other. When the ends of the support columns 4 are connected to the first connection areas 23 and the second connection areas 13, respectively, the support columns 4 are perpendicular to the surfaces of the condensation end 2 and the evaporation end 1. The number of support columns 4 is selected based on the dimensions of the condensation end 2 and the evaporation end 1 to ensure a stable flat plate structure of the evaporation end 1 and the condensation end 2.

[0053] Alternatively, as Figure 1 As shown, it also includes a shell 5, which is a flat structure. The evaporation end 1 is located at the inner bottom of the shell 5, and the condensation end 2 is located at the inner top of the shell 5. The surfaces of the evaporation end 1 and the condensation end 2 are both provided with a grooved liquid absorption core 6, and the grooved liquid absorption core 6 at least partially absorbs the liquid working medium 7.

[0054] The shell 5 encloses the flat plate structure of the evaporation end 1 and the condensation end 2 to form a closed steam chamber, so that the working medium 7 in the steam chamber evaporates or liquefies inside the steam chamber to achieve heat dissipation. Among them, the grooved liquid wick 6 can be directly formed on the plate of the evaporation end 1 and the condensation end 2 by plastic micro-forming, i.e., micro-structure imprinting. It does not require the welding and sintering process of the wire mesh and sintered liquid wicks, which reduces the contact thermal resistance. Compared with the traditional wire mesh liquid wick, it has higher strength, is more stable and reliable. The working cycle process of the hydrophilic and hydrophobic composite wetting microstructure steam chamber is as follows: Figure 1 As shown, the working medium 7 absorbs heat from the heat source at the evaporation end 1 and evaporates into the steam chamber. The vapor working medium 7 in the steam chamber is pushed by the vapor pressure difference in the vacuum steam chamber. After encountering the condensation end 2, it is cooled and condensed to change into liquid working medium 7, and flows back to the evaporation end 1 under the capillary force of the groove wick 6 to circulate heat.

[0055] Alternatively, as Figure 2 As shown, the cross section of the trapezoidal edge perpendicular to the V-shaped groove direction is an isosceles trapezoidal structure, wherein the upper base length of the isosceles trapezoidal structure is 100-500 μm, the lower base length of the isosceles trapezoidal structure is 500-1000 μm, and the base angle of the isosceles trapezoidal structure is 70-85 degrees.

[0056] Specifically, the two parallel sides of the trapezoidal structure are called bases, where the shorter base is called the upper base and the longer base is called the lower base; the two non-parallel sides of the trapezoidal structure are called waists, and the lengths of the two waists can be the same or different. When the lengths of the two waists are the same, the trapezoidal structure is an isosceles trapezoidal structure. The angle between the upper base and the waist of the trapezoidal structure is called the vertex angle, and the angle between the lower base and the waist of the trapezoidal structure is called the base angle. The two vertex angles of the isosceles trapezoidal structure have the same angle, and the two base angles of the isosceles trapezoidal structure have the same angle. The upper base length of the isosceles trapezoidal structure formed by the arrangement of the condensation hydrophilic area 21 and the condensation hydrophobic area 22 is 100-500μm, the lower base length of the isosceles trapezoidal structure is 500-1000μm, and when the base angle of the isosceles trapezoidal structure is 70-85 degrees, the isosceles trapezoidal microstructure of this size is very suitable for microstructure embossing molding, has good structural stability, and has excellent capillary suction performance, which is very conducive to efficient condensation and evaporation / boiling. If the scale of the upper base is too small (for example, less than 100μm) or the bottom angle is too large (for example, greater than 85 degrees), the use of microstructure embossing will result in poor filling effect, difficulty in demolding, and easy damage to the punch.

[0057] Optionally, the contact angle of the surface of the condensation hydrophobic region 22 is ≥140°, and the contact angle of the surface of the V-shaped groove of the condensation hydrophilic region 21 is ≤10°.

[0058] At the intersection of solid, liquid and gas, the angle between the solid-liquid interface and the gas-liquid interface is called the contact angle, also known as the wetting angle. When the contact angle is 180 degrees, the liquid droplet on the surface is spherical, which is complete non-wetting. When the contact angle is 0 degrees, the liquid droplet on the surface spreads along the plane and extends infinitely, which is complete wetting. Therefore, the greater the contact angle, the stronger the hydrophobicity of the surface, and the smaller the contact angle, the stronger the hydrophilicity of the surface. The contact angle of the surface of the condensation hydrophobic region 22 is greater than or equal to 140 degrees, achieving strong hydrophobicity, and the contact angle of the surface of the V-shaped groove is less than or equal to 10 degrees, achieving strong hydrophilicity.

[0059] Optionally, as shown in Figure 8 、 Figure 9 and Figure 10 , the microarray hydrophilic region 12 has a tapered microarray 121 structure. Among them, Figure 8 is a schematic diagram of the surface of the evaporation end 1 facing the condensation end 2, and the microchannels 111 and the microarray 121 structure on the surface of the evaporation end 1 facing the condensation end 2 are relatively small, resulting in a dense surface structure of the evaporation end 1, Figure 8 the surface of the evaporation end 1 is not clearly shown, so the partial enlarged view of Figures 9 to 13 is attached for clear illustration of the surface of the evaporation end 1.

[0060] Therefore, the tapered microarray 121 structure can store liquid working medium 7, and the liquefied working medium 7 can be quickly sucked by the capillary action of the tapered microarray 121 structure when returning to the evaporation end, participating in boiling heat transfer, accelerating the phase change cycle, and improving the heat transfer efficiency.

[0061] Optionally, as shown in Figures 11 to 13 , the width of the microchannel 111 is 100-500 μm, and the aspect ratio of the microchannel 111 is 2-3.

[0062] Therefore, the microchannel 111 is very suitable for microstructure imprinting forming, has good structural stability, and has excellent capillary suction performance, which is very beneficial to evaporation / boiling. If the width is too small (e.g. less than 100 μm) or the aspect ratio is too large (greater than 4-5), microstructure imprinting will result in poor filling effect, difficulty in demolding, and easy damage to the punch.

[0063] Optionally, as shown in Figures 7 to 13As shown, the microarray hydrophilic area 12 of the evaporation end 1 is square, having four corners and four sides. The microchannels 111 of the microchannel hydrophilic area 11 in the diagonal area of ​​the microarray hydrophilic area 12 extend diagonally and form a 45-degree angle with the horizontal direction. The microchannels 111 of the microchannel hydrophilic area 11 in the horizontal and vertical areas of the microarray hydrophilic area 12 also extend horizontally and vertically, respectively, to the microarray hydrophilic area 12 in the central area. When the vapor liquefies and returns to the evaporation end 1, it is rapidly drawn in by the capillary action of the microchannel 111 of the microchannel hydrophilic area 11. The radial microchannels 111 shorten the drawing path, enabling the liquid to be quickly drawn into the microarray hydrophilic area 12 in the central area for storage, thereby participating in boiling heat transfer, accelerating the phase change cycle, and improving heat transfer efficiency.

[0064] Optionally, the contact angle of the surface of the microchannel hydrophilic region 11 is ≤10°, and the contact angle of the surface of the microarray hydrophilic region 12 is ≤10°. In this way, the surface of the microchannel hydrophilic region 11 has strong hydrophilicity.

[0065] The present invention also provides a method for preparing a hydrophilic-hydrophobic composite wetting microstructure steam cavity, wherein the hydrophilic-hydrophobic composite wetting microstructure steam cavity is prepared as follows: Figure 14 As shown, the specific steps include:

[0066] S1. Preparation of the blanks for the condensing end 2 and the evaporating end 1: Select metal materials and process them into sheet blanks; specifically, the blanks for the condensing end 2 and the evaporating end 1 can be metal materials such as aluminum, copper, magnesium and their alloys. Select metal materials and process them into sheet blanks of 12×12×3 cm. Use acetone or alcohol to ultrasonically clean the surface of the sheet blank to remove surface impurities.

[0067] S2, microstructure embossing of the condensation end 2 and the evaporation end 1: take the plate blank and use the micro-embossing technology to prepare trapezoidal edges and V-shaped grooves to obtain the condensation end 2; take the plate blank and use the micro-embossing technology to prepare microchannels 111 and microarrays 121 to obtain the evaporation end 1; specifically, the parameters of the micro-embossing technology are: temperature of 350-380℃, forming pressure of 70-75t, and loading speed of 0.1-0.5mm / s.

[0068] Micro-embossing technology is used to form trapezoidal edges and V-shaped grooves on a sheet material to form the condenser end 2. Micro-embossing technology is also used to form microchannels 111 and microarrays 121 on the sheet material to form the evaporator end 1. As a low-cost, mass-producible technology, micro-embossing technology is highly adaptable to the batch processing of large-area microstructures. The condenser end 2 and the evaporator end 1 can be formed in one step using micro-embossing technology. This technology features a simple process, high material utilization, and low cost, making it suitable for the batch production of large-area devices. It also offers high production efficiency, high forming precision, and excellent mechanical properties for the formed microstructures. Micro-embossing technology can be used through molding or roller pressing.

[0069] S3. Overall hydrophobic modification of the condensation end 2: A hydrophobic silica-methanol-ethanol mixed solution is used for surface hydrophobic modification; a fully hydrophobic microchannel condensation end 2 surface with a contact angle ≥ 140° is obtained.

[0070] S4, hydrophilic modification of condensation hydrophilic region 21: Figure 5 As shown, the condensation hydrophobic area 22 is attached with a striped photomask 221 to achieve light shielding of the condensation hydrophobic area 22, and the laser scans the condensation hydrophilic area 21 to induce hydrophilic modification of the surface of the condensation hydrophilic area 21, thereby obtaining a hydrophilic-hydrophobic composite wetting microchannel condensation end 2; specifically, a striped photomask 221 matching the microchannel of the condensation end 2 is prepared, and the striped photomask 221 is covered on the surface of the condensation hydrophobic area 22 to achieve light shielding of the condensation hydrophobic area 22, and then the laser is used at an energy density of 12.0-18.0 J / cm 2 , ultrafast laser scanning at a scanning speed of 1000-2000 mm / s was performed twice to obtain a hydrophilic-hydrophobic composite wetting microchannel condensation end 2 with a contact angle of the condensation hydrophobic area 22 ≥140° and a contact angle of the V-shaped groove of the condensation hydrophilic area 21 ≤10°.

[0071] S5. Hydrophilic modification of the entire evaporation end 1: Laser scanning the surface of the evaporation end 1 induces hydrophilic modification of the surface of the evaporation end 1; specifically, the laser is scanned at an energy density of 12.0-18.0 J / cm 2 , ultrafast laser scanning at a scanning speed of 1000-2000 mm / s was performed twice to obtain a hydrophilic microstructure evaporation end 1 with a contact angle of ≤10°.

[0072] S6. Assembly: The evaporation end 1 and the condensation end 2 are assembled to form a hydrophilic-hydrophobic composite wetting microstructure steam chamber with a central cavity 3. Specifically, the evaporation end 1 and the condensation end 2 are welded together at the top and bottom to form a hydrophilic-hydrophobic composite wetting microstructure steam chamber with a central cavity 3.

[0073] Optionally, the surfaces of both the evaporation end 1 and the condensation end 2 are provided with a grooved wick 6, which at least partially absorbs the liquid working medium 7. The wick also includes a shell 5, which encloses the flat plate structure formed by the evaporation end 1 and the condensation end 2 to form a closed steam chamber. The evaporation end 1 is located at the bottom of the steam chamber, and the condensation end 2 is located at the top of the steam chamber. This allows the working medium 7 in the steam chamber to evaporate or liquefy inside the steam chamber, achieving heat dissipation. The grooved wick 6 can be directly formed in one step on the plate materials of the evaporation end 1 and the condensation end 2 by plastic microforming, i.e., microstructure embossing.

[0074] Optionally, in step S4 and step S5, the energy density of the laser scanning is 12.0-18.0 J / cm 2 , the scanning speed is 1000-2000mm / s.

[0075] like Figure 15 As shown, the micro-embossing forming device 8 is used to realize in-situ heating and molding of the surface of the evaporation end 1, the surface of the condensation end 2 and the groove wick 6 through micro-embossing technology, so that a microarray 121 structure and a microchannel 111 structure are formed on the surface of the evaporation end 1, and a trapezoidal structure microchannel is formed on the surface of the condensation end 2, so that the groove wick 6 can be directly formed on the plate 88 of the evaporation end 1 and the condensation end 2 at one time, without the need for welding and sintering processes of screen-type and sintered wicks, thereby reducing contact thermal resistance. The micro-embossing forming device 8 includes a power component 84, a forming component, a heating element 83 and a guide mechanism. The forming component includes a punch 81 and a die 82. The punch 81 and the die 82 emboss a plate 88. According to the finished product structure to be embossed on the surface of the plate 88, a suitable punch 81 or die 82 mold is selected. The punch 81 and the die 82 are filled with a heating element 83. The heating element 83 can choose to use an electric heating rod to enable the punch 81 and the die 82 to hot-press the plate 88. The power component 84 is connected to the punch 81 and / or the die 82 to enable the power component 84 to drive the punch 81 and / or the die 82 to move so as to hot-press the plate 88. In order to avoid the situation where the temperature of the punch 81 and the die 82 is too high and damages the power component 84 connected thereto, An insulation plate 85 is arranged between the power component 84 and the punch 81 and / or the die 82. The guide mechanism may include a frame and a guide column 87. The frame includes an upper frame 861 and a lower frame 862. The guide column 87 can be fixedly connected to the lower frame 862. A hole is left on the upper frame 861 to pass through the guide column 87, so that the upper frame 861 can move up and down relative to the guide column 87. The upper frame 861 can be used to support the power component 84, and the lower frame 862 can support the forming component. The upper frame 861 has a storage space for the power component 84, so that the power component 84 can drive the upper frame 861 to move up and down relative to the guide column 87. When the power component 84 pushes the forming component, it pushes the forming component up and down along the direction of the guide column 87 to hot press the plate 88.

[0076] Example 1: Preparation of hydrophilic-hydrophobic composite wetting microstructure steam chamber

[0077] S1. Preparation of the blanks for the condensing end and the evaporating end: 7075 aluminum alloy was selected to process a 12×12×3 cm sheet blank. The surface of the sheet blank was ultrasonically cleaned with acetone or alcohol to remove surface impurities.

[0078] S2. Microstructure Imprinting of the Condenser and Evaporator Ends: Micro-embossing was used to create trapezoidal edges and V-shaped grooves on the sheet material to create the condenser end. Micro-embossing was also used to create microchannels and microarrays on the sheet material to create the evaporator end. Specifically, the micro-embossing parameters were: temperature of 350°C, forming pressure of 70t, and loading speed of 0.1mm / s. The trapezoidal edges had an isosceles trapezoidal cross-section, with an upper base length of 100μm, a lower base length of 500μm, and a base angle of 70 degrees. The microarray 121 at the evaporation end is square, with four corners and four sides. The microchannels 111 in the diagonal area of ​​the microarray 121 extend diagonally and at a 45-degree angle to the horizontal direction. The microchannels in the horizontal and vertical areas of the microarray 121 also extend horizontally and vertically, respectively, to the microarray 121 in the central area. The width of the microchannels is 100 μm, and the aspect ratio of the microchannels is 2.

[0079] S3. Overall hydrophobic modification of the condensation end: A hydrophobic silica-methanol-ethanol mixed solution is used for surface hydrophobic modification; a fully hydrophobic microchannel condensation end surface with a contact angle ≥140° is obtained.

[0080] S4. Hydrophilic modification of the condensation hydrophilic area 21: a striped photomask is attached to the condensation hydrophobic area to achieve light shielding of the condensation hydrophobic area, and a laser is scanned on the condensation hydrophilic area to induce hydrophilic modification of the surface of the condensation hydrophilic area, thereby obtaining a hydrophilic-hydrophobic composite wetting microchannel condensation end; specifically, a striped photomask matching the microchannel of the condensation end is prepared, and the striped photomask is covered on the surface of the condensation hydrophobic area to achieve light shielding of the condensation hydrophobic area, and then the energy density is 12.0 J / cm 2 , ultrafast laser scanning at a scanning speed of 1000 mm / s was performed twice to obtain a hydrophilic-hydrophobic composite wetting microchannel condensation end with a contact angle of ≥140° in the condensation hydrophobic area and a contact angle of ≤10° in the V-shaped groove in the condensation hydrophilic area.

[0081] S5. Overall hydrophilic modification of the evaporation end: Laser scanning the evaporation end surface induces hydrophilic modification of the evaporation end surface; specifically, the laser is scanned at an energy density of 12.0 J / cm 2 , ultrafast laser scanning at a scanning speed of 1000 mm / s was performed twice to obtain a hydrophilic microstructure evaporation end with a contact angle of ≤10°.

[0082] S6. Assembly: The evaporation end and the condensation end are welded together to form a hydrophilic-hydrophobic composite wetting microstructure steam cavity with a cavity in the middle.

[0083] Example 2: Preparation of hydrophilic-hydrophobic composite wetting microstructure steam chamber

[0084] S1, blank preparation of condensing end and evaporating end: select 7075 aluminum alloy to process 12x12x3cm plate blank, and clean the surface of the plate blank by ultrasonic cleaning with acetone or alcohol to remove surface impurities.

[0085] S2, microstructure imprinting of condensing end and evaporating end: take the plate blank to prepare trapezoidal ridges and V-shaped grooves by micro-imprinting technology to obtain the condensing end; take the plate blank to prepare microchannels and microarrays by micro-imprinting technology to obtain the evaporating end; specifically, the parameters of micro-imprinting technology: temperature is 380℃, forming pressure is 75t, loading speed is 0.5mm / s. Among them, the trapezoidal ridge is an isosceles trapezoidal structure, the upper base length of the isosceles trapezoidal structure is 500μm, the lower base length of the isosceles trapezoidal structure is 1000μm, and the bottom angle of the isosceles trapezoidal structure is 85 degrees. The microarray of the evaporating end is square, has four corners and four sides, the microchannels in the diagonal line area of the microarray extend along the diagonal line and are at an angle of 45 degrees with the horizontal direction, and the microchannels in the horizontal and vertical direction areas of the microarray also extend along the horizontal and vertical directions respectively to the microarray in the central area. The width of the microchannel is 500μm, and the aspect ratio of the microchannel is 3.

[0086] S3, overall hydrophobic modification of condensing end: surface hydrophobic modification is carried out by using hydrophobic silicon dioxide-methanol-ethanol mixed solution; a full hydrophobic microchannel condensing end surface with a contact angle ≥140° is obtained.

[0087] S4, hydrophilic modification of condensing hydrophilic area: affixing a striped photomask to the condensing hydrophobic area to achieve light shielding of the condensing hydrophobic area, and laser scanning the condensing hydrophilic area to induce surface hydrophilic modification, obtaining a hydrophobic and hydrophilic composite wetting microchannel condensing end; specifically, a striped photomask matching the microchannels of the condensing end is prepared, the striped photomask is covered on the surface of the condensing hydrophobic area to achieve light shielding of the condensing hydrophobic area, and then an ultrashort laser is scanned twice with an energy density of 18.0J / cm 2 , and a scanning speed of 2000mm / s, obtaining a hydrophobic and hydrophilic composite wetting microchannel condensing end with a condensing hydrophobic area contact angle ≥140° and a condensing hydrophilic area V-shaped groove contact angle ≤10°.

[0088] S5, overall hydrophilic modification of evaporating end: laser scanning the surface of the evaporating end to induce surface hydrophilic modification; specifically, an ultrashort laser is scanned twice with an energy density of 18.0J / cm 2 , and a scanning speed of 2000mm / s, obtaining a hydrophilic microstructure evaporating end with a contact angle ≤10°.

[0089] S6, assembly: the evaporating end and the condensing end are welded together in an up-down manner to form a hydrophobic and hydrophilic composite wetting microstructure steam cavity with a cavity in the middle.

[0090] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A hydrophilic-hydrophobic composite wetting microstructure steam chamber, characterized in that: It includes an evaporation end and a condensation end, the evaporation end and the condensation end are arranged opposite to each other, wherein: The surface of the evaporation end facing the condensation end includes a microchannel hydrophilic area and a microarray hydrophilic area, the microchannel hydrophilic area surrounds the microarray hydrophilic area, the microchannel hydrophilic area has microchannels, and the directions of the microchannels all lead to the microarray hydrophilic area; and The surface of the condensation end facing the evaporation end includes a plurality of trapezoidal ridges arranged at intervals, and adjacent trapezoidal ridges form V-shaped grooves, the upper bottom surface of the trapezoidal ridges is a condensation hydrophobic area, and the surface of the V-shaped groove is a condensation hydrophilic area; The evaporation end and the condensation end are assembled to form a flat plate structure with a cavity in the middle.

2. The hydrophilic-hydrophobic composite wetting microstructure steam chamber according to claim 1, characterized in that: It also includes a supporting column, and the two ends of the support are respectively abutted against the evaporation end and the condensation end.

3. The hydrophilic-hydrophobic composite wetting microstructure steam chamber according to claim 1, characterized in that: It also includes a shell, which is a flat structure. The evaporation end is located at the inner bottom of the shell, and the condensation end is located at the inner top of the shell. The surfaces of the evaporation end and the condensation end are both provided with grooved liquid absorption cores, and the grooved liquid absorption cores at least partially absorb the liquid working medium.

4. The hydrophilic-hydrophobic composite wetting microstructure steam chamber according to claim 1, characterized in that: The cross section of the trapezoidal edge perpendicular to the V-shaped groove is an isosceles trapezoidal structure, the upper base length of the isosceles trapezoidal structure is 100-500 μm, the lower base length of the isosceles trapezoidal structure is 500-1000 μm, and the base angle of the isosceles trapezoidal structure is 70-85 degrees.

5. The hydrophilic-hydrophobic composite wetting microstructure steam chamber according to claim 1, characterized in that: The contact angle of the surface of the condensation hydrophobic area is ≥140°, and the contact angle of the surface of the V-shaped groove of the condensation hydrophilic area is ≤10°.

6. The hydrophilic-hydrophobic composite wetting microstructure steam chamber according to claim 1, characterized in that: The microarray hydrophilic region has a cone-shaped microarray structure.

7. The hydrophilic-hydrophobic composite wetting microstructure steam chamber according to claim 1, characterized in that: The width of the microchannel is 100-500 μm, and the aspect ratio of the microchannel is 2-3.

8. The hydrophilic-hydrophobic composite wetting microstructure steam chamber according to claim 1, characterized in that: The contact angle of the surface of the hydrophilic area of ​​the microchannel is ≤10°, and the contact angle of the surface of the hydrophilic area of ​​the microarray is ≤10°.

9. A method for preparing a hydrophilic-hydrophobic composite wetting microstructure steam chamber, characterized in that: The preparation of the hydrophilic-hydrophobic composite wettable microstructure steam chamber according to any one of claims 1 to 8 comprises the following steps: S1. Preparing the blanks for the condensing end and the evaporating end: selecting metal materials and processing them into sheet blanks; S2. Imprinting the microstructures of the condensing end and the evaporating end: using the plate blank to prepare the trapezoidal edges and the V-shaped grooves using micro-imprinting technology to obtain the condensing end; using the plate blank to prepare micro-channels and micro-arrays using micro-imprinting technology to obtain the evaporating end; S3, hydrophobic modification of the entire condensation end: using a hydrophobic silica-methanol-ethanol mixed solution to perform surface hydrophobic modification; S4, hydrophilic modification of the condensation hydrophilic area: attaching a striped photomask to the condensation hydrophobic area to shield the condensation hydrophobic area from light, and laser scanning the condensation hydrophilic area to induce surface hydrophilic modification of the condensation hydrophilic area, thereby obtaining a hydrophilic-hydrophobic composite wetting microchannel condensation end; S5, hydrophilic modification of the entire evaporation end: laser scanning the surface of the evaporation end to induce hydrophilic modification of the surface of the evaporation end; S6. Assembling: The evaporation end and the condensation end are assembled to form a hydrophilic-hydrophobic composite wetting microstructure steam cavity with a cavity in the middle.

10. The method for preparing a hydrophilic-hydrophobic composite wetting microstructure steam chamber according to claim 9, characterized in that: In step S4 and step S5, the energy density of the laser scanning is 12.0-18.0 J / cm 2 , the scanning speed is 1000-2000mm / s.

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