Ultrathin vapor chamber and manufacturing method thereof

Abstract

The invention discloses an ultrathin vapor chamber and a manufacturing method thereof.The vapor chamber comprises an upper cover plate, a lower cover plate and a composite capillary structure arranged between the upper cover plate and the lower cover plate, a boss is arranged in the middle of the lower cover plate, a skirt edge is arranged on the periphery of the boss, and the upper cover plate and the skirt edge are attached to form a cover plate cavity; the composite capillary structure comprises a first capillary structure and a second capillary structure which are horizontally arranged, the first capillary structure is of a net-shaped structure, and the second capillary structure comprises a metal net-shaped structure and a water absorption structure attached to the metal net-shaped structure; the lower surface of the composite capillary structure is attached to the lower cover plate, and the upper surface is attached to the supporting column on the upper cover plate. According to the structure, differential design of high capillary force of an evaporation area and high permeability of a condensation area can be achieved, and the circulation efficiency of a cooling medium is improved; and meanwhile, the punch-formed cover plate is combined with the composite capillary structure, the structural stability is enhanced, and the composite capillary structure is suitable for ultrathin application scenes with the thickness smaller than or equal to 0.2 mm. The invention further provides a corresponding manufacturing method which is simple and convenient in process and suitable for batch production.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, and more specifically to an ultrathin heat exchanger and its manufacturing method. Background Technology

[0002] With the development of 5G communication technology and high-performance mobile devices, the power consumption of electronic components has increased significantly, placing higher demands on heat dissipation systems. As a highly efficient heat dissipation device, vapor chambers are widely used in space-constrained electronic devices such as smartphones due to their excellent heat transfer performance and slim design.

[0003] Currently, the thickness of conventional vapor chambers is typically 0.29mm to 0.35mm, and their main structure includes an upper cover plate, a lower cover plate, and a capillary structure between them. With the increasing trend towards thinner and lighter equipment, vapor chamber thickness is further reduced, especially in ultra-thin vapor chambers with a thickness of ≤0.2mm. Traditional capillary structures struggle to balance high capillary force and high permeability, leading to increased steam channel resistance, reduced cooling medium reflux capacity, and significantly deteriorated heat dissipation performance. Furthermore, ultra-thin structures are prone to deformation and bulging during processing, affecting product structural stability and yield.

[0004] In recent years, some improved technologies have been proposed. For example, Chinese invention patent application CN109891178A (published on June 14, 2019) discloses a thin heat spreader formed by a stamping process. The supporting structure inside the heat spreader consists of multiple spaced-apart first support bosses on the inner surface of a first cover plate. These first support bosses can be formed using a common processing technology such as stamping, which has a lower processing cost than etching. Therefore, this heat spreader reduces the processing cost compared to existing technologies. Moreover, in this heat spreader, the working fluid vapor chamber is automatically formed by the spacer area between adjacent first support bosses during the assembly of the first cover plate, the second cover plate, and the capillary layer, without the need for a special processing technology to form the working fluid vapor chamber.

[0005] For example, Chinese utility model patent application CN 211041903 U (publication date: July 17, 2020) discloses an ultra-thin heat spreader, including a first cover plate and a second cover plate with edge-sealed connection. A cavity is provided between the first cover plate and the second cover plate, and the cavity contains a liquid-absorbing core and working fluid, and is in a vacuum state. The first cover plate is provided with multiple first reinforcing ribs, and the second cover plate is provided with multiple second reinforcing ribs. The first and second reinforcing ribs are symmetrically arranged and interconnected. This utility model can ensure the three-dimensional structure of the heat spreader, enhance the mechanical properties of the heat spreader, and prevent deformation. In addition, the double-sided reinforcing rib design strengthens the bonding of the upper and lower cover plates, thereby avoiding bulging and improving product quality and yield.

[0006] In existing technologies, such as CN211041903U, a heat spreader with a double-sided reinforcing rib structure is proposed. Although it can improve the structural strength, it still does not solve the performance bottleneck caused by the single function of the capillary structure after ultra-thinning. CN109891178A adopts a stamped support structure to reduce costs, but it still uses the traditional capillary structure and fails to optimize the capillary structure for the ultra-thin environment.

[0007] Therefore, developing a heat spreader that can meet the requirements of ultra-thinness while also possessing good heat dissipation performance and structural stability, and its manufacturing method, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides an ultrathin heat spreader, comprising: The lower cover plate has a boss in the middle and a skirt around the boss. The upper cover plate is fitted with the skirt, the boss and the upper cover plate form a cover plate cavity, and a support column is provided on the upper cover plate, the support column being located inside the cover plate cavity; A composite capillary structure is disposed within the cover plate cavity, with the lower surface of the composite capillary structure attached to the lower cover plate and the upper surface attached to the support column. The composite capillary structure includes a first capillary structure and a second capillary structure, which are arranged horizontally. The first capillary structure is a mesh structure, and the second capillary structure includes a metal mesh structure with water-absorbing structures attached to it. This invention enhances the capillary action within the sealed space of the heat spreader through the composite capillary structure. A first capillary structure with strong capillary force is used to drive the evaporation zone, while a second capillary structure with low flow resistance and high permeability is used in the condensation zone. Through its own capillary action, the heat return and retention of water ensure the heat dissipation performance of the heat spreader, enhancing the ability of the liquid cooling medium to flow back to the lower cover. This results in higher heat absorption and release efficiency of the cooling medium circulating within the heat spreader, meeting the heat dissipation requirements of ultra-thin products.

[0009] Furthermore, the thickness of the heat spreader is less than or equal to 0.2 mm.

[0010] Furthermore, the protrusion is L-shaped and is divided into a first protrusion and a second protrusion. The first protrusion and the upper cover plate form a first cover plate cavity, which serves as a condensation area, and the second protrusion and the upper cover plate form a second cover plate cavity, which serves as an evaporation area.

[0011] Furthermore, the first capillary structure is located in the first cover cavity, and the second capillary structure is located in the second cover cavity.

[0012] Furthermore, the metal mesh structure comprises several cells, and the water-absorbing structure is attached to the cells and positioned at the apex and midpoint of the side of the cells.

[0013] Furthermore, the water-absorbing structure is a spherical micron-sized powder with a particle size of 100–200 μm.

[0014] Furthermore, the cell is rectangular in shape.

[0015] Furthermore, both the lower cover plate and the upper cover plate are made of stainless steel.

[0016] Furthermore, the first capillary structure is a stainless steel mesh or a copper mesh. The metal mesh structure is selected from 316L wires with a diameter of 0.015~0.018mm. The metal mesh is woven from metal wires in the warp and weft directions. Rectangular tiny gaps are formed between two adjacent metal wires. These gaps are countless interconnected "capillaries", thereby generating capillary force.

[0017] Furthermore, the water-absorbing structure is made of stainless steel or copper, and the metal mesh structure is made of stainless steel or copper mesh. The metal mesh structure is made of 316L wire with a diameter of 0.015~0.018mm. The metal mesh is woven from metal wires in the warp and weft directions, and rectangular micro-gaps are formed between adjacent metal wires. These gaps are countless interconnected "capillaries", thereby generating capillary force. The water-absorbing structure fills the gaps in the metal mesh structure with micron-sized powder particles (100–200μm), forming a dual-scale channel of "mesh gaps + powder pores". The equivalent radius is significantly reduced, the capillary pressure is greatly increased, the capillary force is strengthened, and a high-permeability capillary structure is formed.

[0018] Furthermore, the ultrathin heat spreader also includes a liquid cooling medium located in the cover plate cavity, and the liquid cooling medium can be pure water.

[0019] The present invention also provides an ultrathin heat spreader and a method for manufacturing the same, comprising the following steps: Step S1: Fabricate the upper and lower cover plates; manufacture the upper and lower cover plates using a stamping process; Step S2: Fabricate a composite capillary structure; obtain the composite capillary structure through coating, debinding and vacuum sintering processes; the water-absorbing structure fills the gaps of the metal mesh structure with micron-sized powder particles (100–200 μm) to form a dual-scale channel of "mesh gaps + powder pores", which significantly reduces the equivalent radius, greatly increases the capillary pressure, and strengthens the capillary force; Step S3: Assemble the heat spreader; assemble the upper cover plate, composite capillary structure, and lower cover plate; Step S4: Sealing treatment; inject liquid, degas, and seal the assembled heat spreader.

[0020] Furthermore, step S2 includes the following steps: Step S21: Prepare a PET film roll by continuously cutting holes 410 of the required shape into the PET film using a rotary cutter and then winding it up to obtain a PET film roll 400 with the shaped holes. Step S22: Use a coating machine to arrange a metal mesh structure, cover the stainless steel mesh with a complete PET film strip, and cover the stainless steel mesh with a PET film roll 400 cut with shaped holes, forming a structure from top to bottom consisting of a perforated PET film, a metal mesh structure, and a complete PET film. Step S23: Prepare a metal paste, the metal paste comprising a film-forming agent and metal powder, wherein the weight of the film-forming agent is 10-50% of the metal paste, and the weight of the metal powder is 50-60% of the metal paste; Step S24: Apply metal paste. Pour the prepared metal paste into the material tank of the coating machine. Set the linear speed to 1-1.5 m / min and the drying tunnel temperature of the coating machine to 100-120℃. After coating and drying, a metal mesh structure with different shapes is obtained. The shaped metal mesh structure is then debonded at 400-600℃ and vacuum sintered at 1000-1200℃ to obtain a composite capillary structure. Step S25: Composite capillary structure, cut into the desired shape.

[0021] Furthermore, the film-forming agent mentioned in step S23 is any one or more of cellulose, waterborne polyurethane, waterborne silicone-acrylic emulsion, and waterborne epoxy resin.

[0022] Furthermore, the metal powder in step S23 has a size of 300-1200 mesh.

[0023] Compared with existing technologies, the advantages and effects of this application are as follows: 1. This application adopts a partitioned composite capillary structure. The evaporation zone is equipped with a second capillary structure with high capillary force, and the condensation zone is equipped with a first capillary structure with high permeability. This effectively improves the reflux rate of the cooling medium and the vapor diffusion efficiency, and solves the technical problem of deterioration of heat dissipation performance of ultra-thin heat exchange plates.

[0024] 2. This application significantly enhances the overall rigidity and compressive strength of the heat spreader by using a stamped and integrally formed upper and lower cover plates and internal support columns, combined with the close support of a composite capillary structure, thus preventing bulging or deformation under vacuum conditions.

[0025] 3. The overall structure of this application is compact, and the thickness can be controlled to below 0.2mm, which meets the urgent need of modern electronic devices for thinner and lighter heat dissipation devices, while maintaining good heat dissipation performance.

[0026] 4. The manufacturing method of this application combines mature processes such as stamping, coating, and sintering, requires no complex equipment, has a simple process flow, and controllable costs, making it suitable for industrial mass production.

[0027] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the preferred embodiments of this application are described in detail below with reference to the accompanying drawings.

[0028] The above and other objects, advantages and features of this application will become more apparent to those skilled in the art from the following detailed description of specific embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0030] in: Figure 1 This is a schematic diagram of an ultrathin heat spreader structure; Figure 2 A schematic diagram of a composite capillary structure for an ultrathin heat exchange plate; Figure 3 This is a flowchart of a manufacturing method for an ultrathin heat spreader. Figure 4 This is a schematic diagram of a manufacturing method for an ultrathin heat spreader.

[0031] Explanation of reference numerals in the attached drawings: 100 - lower cover plate; 110 - boss; 111 - first boss; 112 - second boss; 120 - skirt; 200 - Composite capillary structure; 210 - First capillary structure; 220 - Second capillary structure; 221 - Water-absorbing structure; 222 - Metal mesh structure; 300 - Top cover plate; 310 - Support column; 400 - PET film with visible pores; 410 - pores; 500 - Intact PET film; 600-Metal paste. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. In the following description, specific details such as specific configurations and components are provided merely to help fully understand the embodiments of this application. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. In addition, for clarity and brevity, descriptions of known functions and structures are omitted in the embodiments.

[0033] It should be understood that the phrase "an embodiment" or "this embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this application. Therefore, "an embodiment" or "this embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0034] Furthermore, reference numerals and / or letters may be repeated in different examples within this application. Such repetition is for the purpose of simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or settings discussed.

[0035] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" describes another type of relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the related objects before and after it have an "or" relationship.

[0036] In this article, the term "at least one" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, "at least one of A and B" can mean: A exists alone, A and B exist simultaneously, or B exists alone.

[0037] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion.

[0038] Example 1 This embodiment introduces an ultrathin heat spreader.

[0039] Please refer to Figure 1 As shown, Figure 1 This is a schematic diagram of an ultrathin heat spreader. An ultrathin heat spreader includes: a lower cover plate 100, wherein a boss 110 is provided in the middle of the lower cover plate 100, and a skirt 120 is provided around the boss 110. The upper cover plate 300 is attached to the skirt 120. The boss 110 and the upper cover plate 300 form a cover plate cavity. A support column 410 is provided on the upper cover plate 300 and the support column 410 is located in the cover plate cavity. A composite capillary structure 200 is disposed in the cover plate cavity, the lower surface of the composite capillary structure 200 is attached to the lower cover plate 100, and the upper surface is attached to the support column 410. The composite capillary structure 200 includes a first capillary structure 210 and a second capillary structure 220. The first capillary structure 210 and the second capillary structure 220 are arranged horizontally. The first capillary structure 210 is a mesh structure. The second capillary structure 220 includes a metal mesh structure 222. A water-absorbing structure 221 is attached to the metal mesh structure 222.

[0040] The technical advantages of this embodiment are: by setting up a composite capillary structure, regional differentiation of capillary force is achieved, improving the circulation efficiency of the cooling medium between the evaporation and condensation regions. The structure is simple, easy to assemble, and suitable for ultra-thin devices with strict requirements on thickness and heat dissipation performance.

[0041] Example 2 Based on Example 1, this example discloses a further design of an ultrathin heat spreader.

[0042] Please refer to Figure 2 As shown, Figure 2 A schematic diagram of a composite capillary structure for an ultrathin heat exchange plate; Furthermore, the thickness of the heat spreader is less than or equal to 0.2 mm.

[0043] Furthermore, the boss 110 is L-shaped and is divided into a first boss 111 and a second boss 112. The first boss 111 and the upper cover plate 300 form a first cover plate cavity, which serves as a condensation area, and the second boss 112 and the upper cover plate 300 form a second cover plate cavity, which serves as an evaporation area.

[0044] Furthermore, the first capillary structure 210 is located in the first cover cavity, and the second capillary structure 220 is located in the second cover cavity.

[0045] Furthermore, the metal mesh structure 222 includes several cells, and the water-absorbing structure 221 is attached to the cells and is set at the apex and midpoint of the side of the cells.

[0046] Furthermore, the water-absorbing structure 221 is spherical.

[0047] Furthermore, the cell is rectangular in shape.

[0048] Furthermore, both the lower cover plate 100 and the upper cover plate 300 are made of stainless steel.

[0049] Furthermore, the first capillary structure 210 is a stainless steel mesh or a copper mesh.

[0050] Furthermore, the water-absorbing structure 221 is made of stainless steel or copper, and the metal mesh structure 222 is made of stainless steel mesh or copper mesh.

[0051] The technical advantages of this embodiment are: the boss design is an "L"-shaped partition, clearly distinguishing the evaporation zone and the condensation zone, further optimizing the functional layout of the capillary structure. The water-absorbing structure is set at the vertices and midpoints of the sides of the metal mesh structure cells, forming a stable capillary network and enhancing liquid retention and transport capabilities. Made of stainless steel or copper, it has excellent thermal conductivity and strong corrosion resistance, extending the product's service life.

[0052] Example 3 Based on Example 1, this example discloses a method for manufacturing an ultrathin heat spreader. Please refer to... Figure 3-4 As shown, Figure 3 This is a flowchart of a manufacturing method for an ultrathin heat spreader. Figure 4 This is a schematic diagram of a manufacturing method for an ultrathin heat spreader. The present invention also provides an ultrathin heat spreader and a method for manufacturing the same, comprising the following steps: Step S1: Fabricate the upper and lower cover plates; manufacture the upper cover plate 300 and the lower cover plate 100 using a stamping process; Step S2: Fabrication of the composite capillary structure; the composite capillary structure 200 is obtained through coating, debinding, and vacuum sintering processes; Step S3: Assemble the heat spreader; Assemble the upper cover plate 300, the composite capillary structure 200 and the lower cover plate 100; Step S4: Sealing treatment; inject liquid, degas, and seal the assembled heat spreader.

[0053] Furthermore, step S2 includes the following steps: Step S21: Prepare a PET film roll by continuously cutting holes 410 of the required shape into the PET film using a rotary cutter and then winding it up to obtain a PET film roll 400 with the shaped holes. Step S22: Use a coating machine to arrange a metal mesh structure 222, cover the complete PET film strip under the stainless steel mesh, and cover the stainless steel mesh with a PET film roll 400 cut with shaped holes, forming a structure from top to bottom consisting of a perforated PET film, a metal mesh structure 222, and a complete PET film. Step S23: Prepare metal paste 600, wherein the metal paste 600 comprises a film-forming agent and metal powder, the weight of the film-forming agent is 10-50% of the metal paste 600, and the weight of the metal powder is 50-60% of the metal paste 600; Step S24: Apply metal paste 600. Pour the prepared metal paste 600 into the material tank of the coating machine. Set the linear speed to 1-1.5 m / min and the drying tunnel temperature of the coating machine to 100-120℃. After coating and drying, a metal mesh structure 222 with different shapes is obtained. The shaped metal mesh structure 222 is then debonded at 400-600℃ and vacuum sintered at 1000-1200℃ to obtain a composite capillary structure 200. Step S25: Cut the composite capillary structure 200 into the desired shape.

[0054] Furthermore, the film-forming agent mentioned in step S23 is any one or more of cellulose, waterborne polyurethane, waterborne silicone-acrylic emulsion, and waterborne epoxy resin.

[0055] Furthermore, the metal powder in step S23 has a size of 300-1200 mesh.

[0056] Based on the above manufacturing method, the ultrathin heat spreader was actually prototyped and compared with a conventional capillary structure. The results are shown in the table below: Table 1 Comparison of the performance of different heat sinks The results show that the composite capillary structure effectively improves the temperature uniformity of the heat spreader.

[0057] The technical advantages of this embodiment are as follows: It provides a complete manufacturing process for ultrathin vapor chambers, covering key steps such as capillary structure preparation, cover plate stamping, assembly welding, and liquid injection sealing. The composite capillary structure prepared using a coating-sintering process enables precise molding of complex capillary patterns, adapting to vapor chamber designs with different shapes and performance requirements. Through actual trial production and performance comparison (as shown in Table 1), it is verified that the vapor chamber prepared by this method is superior to traditional structures in terms of saturated water volume, water absorption rate, and temperature uniformity, demonstrating clear industrial application value.

[0058] The above description is merely a preferred embodiment of the present invention and does not limit the scope of protection of the present invention. Various modifications and variations are possible with respect to the present invention. Any changes, modifications, substitutions, integrations, and parameter alterations to these embodiments within the spirit and principles of the present invention fall within the scope of protection of the claims of the present invention.

Claims

1. An ultrathin heat spreader, characterized in that, include: The lower cover plate (100) has a boss (110) in the middle and a skirt (120) around the boss (110). The upper cover plate (300) is fitted with the skirt (120), the boss (110) and the upper cover plate (300) form a cover plate cavity, and a support column (410) is provided on the upper cover plate (300), the support column (410) is located in the cover plate cavity; A composite capillary structure (200) is disposed in the cavity of the cover plate. The lower surface of the composite capillary structure (200) is attached to the lower cover plate (100), and the upper surface is attached to the support column (410). The composite capillary structure (200) includes a first capillary structure (210) and a second capillary structure (220). The first capillary structure (210) and the second capillary structure (220) are arranged horizontally. The first capillary structure (210) is a mesh structure. The second capillary structure (220) includes a metal mesh structure (222). A water-absorbing structure (221) is attached to the metal mesh structure (222).

2. The ultrathin heat spreader according to claim 1, characterized in that, The thickness of the heat spreader is less than or equal to 0.2 mm.

3. An ultrathin heat spreader according to claim 1 or 2, characterized in that, The boss (110) is L-shaped and is divided into a first boss (111) and a second boss (112). The first boss (111) and the upper cover plate (300) form a first cover plate cavity, which serves as a condensation area. The second boss (112) and the upper cover plate (300) form a second cover plate cavity, which serves as an evaporation area.

4. The ultrathin heat spreader according to claim 3, characterized in that, The first capillary structure (210) is located in the first cover cavity, and the second capillary structure (220) is located in the second cover cavity.

5. The ultrathin heat spreader according to claim 3, characterized in that, The metal mesh structure (222) contains several cells, and the water-absorbing structure (221) is attached to the cells and set at the apex and midpoint of the side of the cells.

6. The ultrathin heat spreader according to claim 3, characterized in that, The water-absorbing structure (221) is spherical.

7. The ultrathin heat spreader according to claim 3, characterized in that, The water-absorbing structure (221) is made of stainless steel or copper, and the metal mesh structure (222) is made of stainless steel mesh or copper mesh.

8. The ultrathin heat spreader according to claim 1, characterized in that, Both the lower cover plate (100) and the upper cover plate (300) are made of stainless steel.

9. A method for manufacturing an ultrathin heat spreader according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1: Make the upper and lower cover plates; manufacture the upper cover plate (300) and the lower cover plate (100) by stamping process. Step S2: Fabrication of composite capillary structure; composite capillary structure (200) is obtained through coating, debinding and vacuum sintering processes. Step S3: Assemble the heat spreader; Assemble the upper cover plate (300), the composite capillary structure (200), and the lower cover plate (100); Step S4: Sealing treatment; inject liquid, degas, and seal the assembled heat spreader.

10. The method for manufacturing an ultrathin heat spreader according to claim 9, characterized in that, Step S2 includes the following steps: Step S21: Prepare a PET film roll. Cut the PET film continuously with holes of the required shape using a rotary cutter (410), and then roll it up to obtain a PET film roll with shaped holes (400). Step S22: Use a coating machine to arrange a metal mesh structure (222), cover the stainless steel mesh with a complete PET film strip, and cover the stainless steel mesh with a PET film roll (400) cut with shaped holes, forming a structure from top to bottom consisting of a PET film with shaped holes (400), a metal mesh structure (222), and a complete PET film (500). Step S23: Prepare a metal paste (600), the metal paste (600) comprising a film-forming agent and metal powder, wherein the weight of the film-forming agent is 10-50% of the metal paste (600), and the weight of the metal powder is 50-60% of the metal paste (600); Step S24: Apply metal paste (600). Pour the prepared metal paste (600) into the material tank of the coating machine. Set the linear speed to 1-1.5 m / min and the drying temperature of the coating machine to 100-120℃. After coating and drying, a metal mesh structure (222) with different shapes is obtained. The shaped metal mesh structure (222) is then debonded at 400-600℃ and vacuum sintered at 1000-1200℃ to obtain a composite capillary structure (200). Step S25: The composite capillary structure (200) is cut into the desired shape.

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