An equalizing plate and a preparation method and application thereof

Abstract

This invention discloses a vapor chamber, its preparation method, and its applications, belonging to the field of vapor chamber technology. It includes a base plate, a top plate, a liquid-absorbing core with a micro / nano hierarchical pore structure, and a support column. The base plate and top plate form a vacuum cavity. The liquid-absorbing core with the micro / nano hierarchical pore structure and the support column are located inside the vacuum cavity. The support column connects the base plate and the top plate. The vacuum cavity is filled with a working fluid. The liquid-absorbing core with the micro / nano hierarchical pore structure of this invention has a micron-sized structure and a conformal porous metal foam structure with nanopore characteristics, exhibiting high capillary driving force, high permeability, and low flow resistance. This vapor chamber has low manufacturing cost, a simple method, high heat transfer capacity, high heat transfer efficiency, and high reliability. It can be used to manufacture large-area vapor chambers, meeting the heat dissipation requirements of electronic devices with high heat flux densities. Furthermore, the micro / nano hierarchical structure of this invention can be further used for the inner walls of heat pipes requiring high capillary driving force and other heat sinks to achieve rapid heat dissipation, showing broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of heat spreader technology, specifically to a heat spreader, its preparation method, and its application. Background Technology

[0002] The rapid development of electronic information technology, especially communication and detection technologies, has greatly promoted the widespread application of electronic products and industrial instruments, such as mobile phones and base stations, profoundly changing people's lifestyles and improving their quality of life. Heat spreaders are widely used for heat dissipation in electronic devices, with the wick being the core component.

[0003] Traditional vapor chambers using pure copper mesh absorbers cannot control the pore structure, have heat dissipation limitations, and are only suitable for low- to mid-range heat dissipation, no longer meeting the heat dissipation requirements of 5G base stations. Currently, porous media are commonly used as capillary materials; however, the microstructure of porous media is amorphous, with irregular pore distribution and no clearly defined pore units. Because these porous media lack highly ordered microscale characteristics, accurately predicting fluid transport and precisely adjusting structural features becomes more difficult, and the highly tortuous network between pores exhibits significant hydraulic resistance.

[0004] Therefore, this application is submitted. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a heat spreader, its preparation method and application. The heat spreader contains a liquid wick with a micro-nano multi-level pore structure, which has a large heat transfer capacity, high heat transfer efficiency and high reliability, and can be used to make large-area heat spreaders.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A heat spreader includes a base plate, a top plate, a liquid-absorbing core with a micro-nano hierarchical pore structure, and a support column. The base plate and the top plate form a vacuum cavity. The liquid-absorbing core with a micro-nano hierarchical pore structure and the support column are located inside the vacuum cavity. The support column connects the base plate and the top plate. The vacuum cavity is filled with a working fluid.

[0008] The liquid-absorbing core with a micro-nano hierarchical pore structure described in this invention has a micron-sized structure and a conformal porous metal foam structure with nanopore characteristics, exhibiting high capillary driving force, high permeability, and low flow resistance. This type of vapor chamber is low-cost, simple to manufacture, has high heat transfer capacity, high heat transfer efficiency, and high reliability, and can be used to fabricate large-area vapor chambers to meet the heat dissipation requirements of electronic devices with high heat flux densities. Furthermore, the micro-nano hierarchical structure of this invention can be further used for the inner walls of heat pipes requiring high capillary driving force and other heat sinks to achieve rapid heat dissipation, showing broad application prospects.

[0009] In a preferred embodiment of the present invention, the thickness of the bottom plate and the top plate is 0.01 to 0.1 mm, and the material of the bottom plate and the top plate is copper alloy, aluminum alloy, stainless steel or titanium alloy.

[0010] The present invention also provides a method for preparing a heat spreader, comprising the following steps:

[0011] (1) A base plate is provided, the surface of which has a wire mesh or channels;

[0012] (2) Mix PS microspheres and binder evenly to obtain emulsion. Apply the emulsion to the surface of the substrate and dry it. Deposit electrodeposition solution on the surface of the substrate by electrodeposition method. Soak in organic solvent and anneal to obtain liquid absorbent core with micro-nano hierarchical pore structure.

[0013] (3) The support column and base plate are placed on the stamping die and welded to form the top plate;

[0014] (4) The liquid-absorbing core with micro-nano multi-level pore structure is welded to the top plate and the bottom plate, and the working liquid is injected, degassing and encapsulation are performed to obtain the heat spreader.

[0015] This invention utilizes industrially scalable PS microspheres and adhesives to deposit a sacrificial structural template on a wire mesh / channel microstructure. Metal nanoparticles are deposited in the gaps between the PS sacrificial spheres using electrodeposition. The PS sacrificial template is removed by immersion in an organic solvent and annealing, resulting in a conformal porous metal structure with nanoporous features on the aforementioned wire mesh / channel microstructure. A diffusion welding process is then used to weld support columns to the top plate of a heat spreader. The edges of the bottom and top plates are welded together as a single unit and connected to a working tube. After vacuuming, the working fluid is injected into the heat spreader, and the plate is degassed and encapsulated to create a complete heat spreader, effectively improving heat transfer capacity, efficiency, and reliability.

[0016] The working fluid includes deionized water, acetone, or nanofluid.

[0017] In a preferred embodiment of the present invention, the average particle size of the PS microspheres is 0.5–100 μm;

[0018] The adhesive is an aqueous solution of polyvinyl alcohol, and the mass concentration of the aqueous solution of polyvinyl alcohol is 2-5%.

[0019] The mass ratio of the PS microspheres to the binder is 1:(0.9~1.1).

[0020] Using PS microspheres with an average particle size of 0.5–100 μm, they can effectively enter the pores of the copper mesh to form a connected porous metal structure.

[0021] In this invention, polyvinyl alcohol is used as a binder. Polyvinyl alcohol has good bonding properties and is easily soluble in hot water, making the template easy to remove. However, if polyadipate is used as a binder, the polyadipate template is difficult to remove after molding, and a large amount of residue remains even after high-temperature calcination.

[0022] The mass ratio of PS microspheres to binder has a significant impact on the effect. By controlling the mass of both within this range, a dense and interconnected porous metal foam structure can be formed. If the mass ratio is less than 1:1, the solution is too dilute and it is not easy to form a dense PS sphere template, which will dissolve during the subsequent electrodeposition process. If the mass ratio is greater than 1:1, the solution is viscous and the thickness of the template formed will be uneven, resulting in uneven distribution of the electrodeposited nanostructure and failure to form a complete interconnected porous structure.

[0023] In a preferred embodiment of the present invention, the thickness of the emulsion coating is 1 to 2 mm.

[0024] In a preferred embodiment of the present invention, the electrodeposition current is 0.1 to 1 A, the deposition time is 1 to 4 hours, and the electrodeposition temperature is 30 to 50°C.

[0025] This process involves controlling the electrodeposition parameters to generate uniform and refined nanocrystals within the gaps between PS microspheres, ultimately producing a micro / nano-level liquid-absorbing core. However, excessively low electrodeposition temperatures result in slow deposition rates; excessively high temperatures lead to dendritic structures; excessively high currents result in coarse grains that easily aggregate; excessively low currents fail to form a connected mesh structure; and excessively long electrodeposition times lead to dense grain growth, filling the pores and causing the loss of active sites.

[0026] In a preferred embodiment of the present invention, the electrodeposition solution is prepared from a saturated sulfate solution and a sulfuric acid solution, and the pH of the electrodeposition solution is 0.8 to 1.2; the sulfate solution includes at least one of copper sulfate solution and nickel sulfate solution.

[0027] In a preferred embodiment of the present invention, the organic solvent includes at least one of tetrahydrofuran and acetone, and the soaking temperature is 30-40°C.

[0028] In a preferred embodiment of the present invention, the annealing temperature is 400-600°C and the annealing time is 1-3 hours.

[0029] In a preferred embodiment of the present invention, the wire mesh is a 50-200 mesh copper wire mesh.

[0030] This invention also provides an application of a heat spreader in 5G base stations, electronic chips, and LEDs.

[0031] The beneficial effects of this invention are as follows: The liquid-absorbing core with a micro-nano hierarchical pore structure described in this invention has a micron-sized structure and a conformal porous metal foam structure with nanopore characteristics, exhibiting high capillary driving force, high permeability, and low flow resistance. This type of vapor chamber has low manufacturing cost, a simple manufacturing method, high heat transfer capacity, high heat transfer efficiency, and high reliability. It can be used to fabricate large-area vapor chambers, meeting the heat dissipation requirements of electronic devices with high heat flux densities. Furthermore, the micro-nano hierarchical structure of this invention can be further used for the inner walls of heat pipes requiring high capillary driving force and other heat sinks to achieve rapid heat dissipation, showing broad application prospects. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the heat spreader of the present invention.

[0033] Figure 2 This is a picture of the base plate after drying in Example 1.

[0034] Figure 3 This is a scanning electron microscope image of the substrate after drying in Example 1.

[0035] Figure 4 This is an image of the substrate after electrodeposition for 1 hour in Example 1.

[0036] Figure 5 This is a picture of the substrate after being soaked in tetrahydrofuran in Example 1.

[0037] Figure 6 This is a scanning electron microscope image of the substrate after being soaked in tetrahydrofuran in Example 1.

[0038] Figure 7 This is a scanning electron microscope image of Example 1 after annealing.

[0039] Figure 8 The image shows one end of the support column in Example 1 welded to the base plate using a diffusion welding process.

[0040] Figure 9 The image shows a heat spreader plate from which the edges of the bottom plate and top plate are welded together as a whole, as shown in Example 1.

[0041] Figure 10 The thermogravimetric curve of the PS ball in Example 1 is shown.

[0042] Figure 11 The image shows the result after electrodeposition for 4 hours, immersion in tetrahydrofuran, and annealing in Example 2. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0045] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0046] In this application, there are no particular restrictions on the specific dispersion and mixing methods.

[0047] Unless otherwise specified, all components, raw materials, or instruments used in the embodiments and comparative examples of this invention are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] The following embodiments are provided to facilitate understanding of the invention. These embodiments are not intended to limit the scope of the claims.

[0050] Example 1

[0051] like Figure 1 As shown, this embodiment provides a heat spreader, including a base plate 1, a liquid absorbent core 2 with a micro-nano multi-level pore structure, a support column 3, and a top plate 4. The base plate and the top plate form a vacuum cavity. The liquid absorbent core with a micro-nano multi-level pore structure and the support column are located inside the vacuum cavity. The support column connects the base plate and the top plate. The vacuum cavity is filled with a working liquid.

[0052] The method for preparing the heat spreader includes the following steps:

[0053] (1) A C5191 copper base plate with a thickness of 0.4 mm and a C5191 copper top plate with a thickness of 0.4 mm are provided by stamping, and a 100-mesh copper wire mesh is placed on the surface of the base plate;

[0054] (2) PS microspheres and a 4% polyvinyl alcohol aqueous solution were mixed evenly at a mass ratio of 1:1 to obtain an emulsion. The emulsion was then coated onto the surface of the substrate to a thickness of 1 mm and dried. The image after drying is shown below. Figure 2 As shown; Scanning electron microscope image after drying is shown below. Figure 2 As shown, the PS spheres are evenly covered on the surface of the copper mesh, presenting a regularly arranged microsphere structure.

[0055] (3) Adjust the pH of the saturated copper sulfate solution to 1 with sulfuric acid solution to obtain an electrodeposition solution. The electrodeposition solution is deposited on the surface of the substrate by electrodeposition method. The current of the electrodeposition is 0.5A and the temperature of the electrodeposition is 40℃.

[0056] like Figure 4 As shown in the photograph of the substrate after 1 hour of electrodeposition, it can be seen that the PS ball template on the surface did not fall off, which indicates that the template can still maintain good stability in the strongly acidic electrodeposition solution, without falling off or dissolving.

[0057] (4) Soak in tetrahydrofuran for 24 hours, such as Figure 5 As shown in the photograph of the substrate after being soaked in tetrahydrofuran, the surface template has been almost completely removed, indicating that organic solvents can effectively remove the PS ball template on a macroscopic scale.

[0058] Scanning electron microscope image after immersion in tetrahydrofuran: Figure 6 As shown, a small amount of PS ball template residue can be observed.

[0059] (5) Anneal at 500℃ under an argon atmosphere for 2 hours; Figure 7 As described above, the scanning electron microscope image after annealing is as follows: Figure 7 As shown, the template was completely removed, revealing nanostructured pores. The liquid-absorbing core with micro-nano hierarchical pore structure was thoroughly washed with water, dried, and weighed.

[0060] (6) Figure 8 The support column, the liquid-absorbing core with micro-nano multi-level pore structure, and the top and bottom plates are welded together, and their surface coatings are smooth and uniform.

[0061] (7) Inject working fluid, degas, and weld the edges of the bottom plate and top plate together to form a single heat spreader, such as... Figure 9 The edges of the base plate must be smooth, flat, and clean to facilitate welding.

[0062] Figure 10 The thermogravimetric curve of the PS ball template is given. It can be seen that when the temperature reaches 500℃, the weight of the PS ball is almost 0, and the PS ball can be completely removed above 500℃.

[0063] Example 2

[0064] Example 2 differs from Example 1 in that the electrodeposition time is 4 hours, while all other parameters are identical to Example 1. The image after immersion in tetrahydrofuran and annealing is shown below. Figure 11 As shown, a conformal porous metal foam with nanostructure pores was found after the electrodeposition time was extended, and the PS ball template was completely removed.

[0065] Example 3

[0066] The difference between Example 3 and Example 1 is that the bottom plate and top plate are made of stainless steel.

[0067] Example 4

[0068] Example 4 differs from Example 1 in that nickel sulfate solution is used instead of copper sulfate (resulting in a common porous nickel foam).

[0069] Example 5

[0070] The difference between Example 5 and Example 1 is that the emulsion is applied to the surface of the base plate with a coating thickness of 2 mm.

[0071] Example 6

[0072] The difference between Example 6 and Example 1 is that the annealing temperature is 400°C.

[0073] Example 7

[0074] The difference between Example 7 and Example 1 is that the annealing temperature is 600°C.

[0075] Comparative Example 1

[0076] The difference between Comparative Example 1 and Example 1 is that the emulsion was applied to the surface of the substrate with a coating thickness of 0.5 mm. In this comparative example, due to the low coating thickness, the template dissolved and fell off in the acidic electrodeposition solution, and the filter element could not be prepared.

[0077] Comparative Example 2

[0078] The difference between Comparative Example 2 and Example 1 is that the annealing temperature is 800°C. If the annealing temperature is too high, the nanostructure will be destroyed and the filter element cannot be prepared.

[0079] Comparative Example 3

[0080] The difference between Comparative Example 3 and Example 1 is that the annealing temperature is 300°C.

[0081] Comparative Example 4

[0082] The difference between Comparative Example 4 and Example 1 is that the PS microspheres and the 4% polyvinyl alcohol aqueous solution were in a mass ratio of 1:0.5.

[0083] Comparative Example 5

[0084] The difference between Comparative Example 5 and Example 1 is that the PS microspheres and the 4% polyvinyl alcohol aqueous solution were in a mass ratio of 1:2.

[0085] Test case

[0086] The performance of the heat spreaders obtained in the embodiments and comparative examples is shown in Table 1.

[0087] Double 85 performance test: Place the sample at 85% humidity and 85℃ and test for 168h according to the method of GB / T 2423.50.

[0088] Table 1

[0089]

[0090]

[0091] As can be seen from Table 1, the heat spreader described in this invention has excellent heat transfer efficiency and reliability.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for producing a vapor chamber, characterized by, The preparation method comprises the following steps: (1) providing a bottom plate, a surface of the bottom plate having a wire mesh or a channel; (2) mixing PS microspheres and a binder uniformly to obtain an emulsion, applying the emulsion on the surface of the bottom plate, drying, depositing an electrodeposition liquid on the surface of the bottom plate by using an electrodeposition method, soaking by using an organic solvent, annealing, and obtaining a wick with a micro-nano multi-level porous structure; the thickness of the emulsion application is 1-2 mm; the binder is a polyvinyl alcohol aqueous solution, the mass concentration of the polyvinyl alcohol aqueous solution is 2-5%, and the mass ratio of the PS microspheres to the binder is 1:(0.9-1.1); (3) placing a support column and a base plate on a stamping die to make a top plate by welding; (4) welding the wick with the micro-nano multi-level porous structure with the top plate and the bottom plate, injecting a working liquid, degassing, and packaging to obtain a vapor chamber. The vapor chamber comprises a bottom plate, a top plate, a wick with a micro-nano multi-level porous structure, and a support column, the bottom plate and the top plate form a vacuum cavity, the wick with the micro-nano multi-level porous structure and the support column are located inside the vacuum cavity, the support column connects the bottom plate and the top plate, and the vacuum cavity is filled with a working liquid.

2. The production method of the vapor chamber according to claim 1, characterized by The average particle size of the PS microspheres is 0.5-100 μm.

3. The production method of the vapor chamber according to claim 1, characterized by The current of the electrodeposition is 0.1-1 A, and the deposition time is 1-4 h.

4. The production method of the vapor chamber according to claim 1, characterized by The electrodeposition liquid is prepared from a saturated sulfate solution and a sulfuric acid solution, the pH of the electrodeposition liquid is 0.8-1.2, and the sulfate solution comprises at least one of a copper sulfate solution and a nickel sulfate solution.

5. The production method of the vapor chamber according to claim 1, characterized by The organic solvent comprises at least one of tetrahydrofuran and acetone, and the soaking temperature is 30-40 °C.

6. The production method of the vapor chamber according to claim 1, wherein The annealing temperature is 400-600 °C, and the annealing time is 1-3 h.

7. The production method of the vapor chamber according to claim 1, wherein The materials of the bottom plate and the top plate are copper alloy, aluminum alloy, stainless steel, or titanium alloy.

8. Application of the vapor chamber prepared by the preparation method in a 5G base station or an LED.

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