Multi-level capillary structure vapor chamber and preparation method thereof

Abstract

The invention relates to the technical field of thermal management of electronic equipment, in particular to a multi-level capillary structure vapor chamber and a preparation method thereof. The multi-level capillary structure vapor chamber is composed of an asymmetric honeycomb-shaped supporting column array, a multi-level capillary structure and a vacuum sealing cavity in a composite mode. The diameters of the asymmetric honeycomb-shaped supporting columns are changed in a gradient manner along the heat source direction; the multi-level capillary structure is formed by sequentially compounding a nano copper oxide coating, a radial micro groove and a copper powder sintering layer; the vacuum sealing cavity is formed by welding a first cover plate and a second cover plate. According to the multi-level capillary structure vapor chamber provided by the invention, through gradient support column, multi-level capillary structure and heterogeneous material interface optimization, the problem of systematicness insufficiency of structure-material-process collaborative optimization of an existing scheme is solved, and an innovative scheme is provided for thermal management of electronic equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal management of electronic equipment, and in particular to a multi-level capillary structure temperature averaging plate and a preparation method thereof. Background Art

[0002] With the development of technologies such as 5G communications and artificial intelligence chips, the heat flux density of electronic devices continues to increase, and traditional heat dissipation solutions face severe challenges. Existing heat spreaders mostly use a planar structure, which has the following shortcomings: 1. The heat flow path is long; 2. A single capillary structure is difficult to balance capillary force and permeability; 3. The thermal resistance of the heterogeneous material interface is high, and traditional manufacturing processes cannot meet the requirements of ultra-thin precision molding. These defects together lead to the heat spreader being 10W / cm 2 The temperature difference under heat flux density is generally >3°C, and the thermal conductivity is <6000W / (m·K), which makes it difficult to adapt to the heat dissipation needs of the next generation of electronic devices.

[0003] Therefore, there is an urgent need to realize a multi-level capillary structure temperature averaging plate and a preparation method thereof to solve the problems of low heat dissipation efficiency, bloated structure and poor process compatibility of the existing temperature averaging plates. Summary of the Invention

[0004] In order to address the deficiencies in the prior art, the present invention aims to provide a multi-level capillary structure temperature equalizing plate and a preparation method thereof.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A multi-level capillary structure temperature equalizing plate, comprising: a first cover plate and a second cover plate; a receiving groove is provided in the middle portion of the second cover plate; the first cover plate is installed above the notch of the receiving groove, and the first cover plate and the receiving groove form a vacuum cavity; a capillary structure is provided on the inner wall of the vacuum cavity; the capillary structure comprises a copper powder sintered layer, a radial groove layer and a nano copper oxide coating arranged in sequence from the outside to the inside; an asymmetric honeycomb support column array is provided in the vacuum cavity.

[0007] As a further improvement of the above technical solution, the accommodating groove is punched in the middle of the second cover plate, and the outer edge of the notch of the accommodating groove forms a flange plate; the first cover plate is pressed onto the notch of the accommodating groove on the second cover plate by diffusion welding to form a vacuum cavity; the thickness of the vacuum cavity is less than 0.5 mm, and the vacuum degree is 5×10 -4 Pa.

[0008] As a further improvement of the above technical solution, a liquid filling port is provided at the front end of the flange plate of the second cover plate, and the liquid filling port is connected to the receiving tank; the receiving tank is filled with a refrigerant, and the refrigerant is a graphene / acetone mixture containing 0.5wt% nano-diamond particles, and the refrigerant is injected into the receiving tank through the liquid filling port.

[0009] As a further improvement of the above technical solution, the copper powder sintered layer is laid on the inner walls of the vacuum cavity by gradient sintering; the thickness of the copper powder sintered layer is 200-400 μm, the sintering temperature is 650±20°C, hydrogen atmosphere protection is used during the sintering process, and the sintering time is 30-60 minutes.

[0010] As a further improvement of the above technical solution, the radial microgrooves include multiple microgrooves; the multiple microgrooves take the center of the heat source as the starting point and extend radially outward to form a multi-branch flow channel network; the starting points of the multiple microgrooves form a circular area, which is the heat source area; the width of the microgrooves is adjustable within the range of 80 to 150 μm.

[0011] As a further improvement of the above technical solution, the thickness of the nano copper oxide coating is 50-100 nm, and it is prepared by chemical vapor deposition process, the deposition temperature is 450° C., and the reaction gas is a mixture of oxygen and copper acetylacetonate.

[0012] As a further improvement of the above technical solution, the asymmetric honeycomb support column array includes multiple support columns, and the multiple support columns form a honeycomb structure; the diameter of the asymmetric honeycomb support column array shows a gradual gradient change along the heat source direction, and the support columns are integrated with the vacuum cavity through the SLM process; the multiple support columns arranged in the honeycomb structure adopt an asymmetric layout; the support column is frustum-shaped, and its diameter decreases gradually along the heat source direction; the support column is made of titanium alloy material, and the diameter of the support column decreases gradually from 0.8mm to 0.3mm along the heat source direction.

[0013] As a further improvement of the above technical solution, the asymmetric honeycomb support column array is integrated with the vacuum cavity through a selective laser melting process, and the interface bonding strength is greater than 300 MPa.

[0014] The present invention also includes a method for preparing the multi-level capillary structure temperature averaging plate, the method comprising the following steps:

[0015] S1. Prepare a first cover plate and a second cover plate, and punch a receiving groove in the middle portion of the second cover plate. The first cover plate and the receiving groove form a vacuum cavity.

[0016] S2. performing gradient sintering of copper powder on the inner wall of the vacuum chamber to form a copper powder sintered layer of a specific thickness;

[0017] S3. Use laser engraving and mold imprinting technology to process radial micro grooves on the surface of the copper powder sintered layer.

[0018] S4, using chemical vapor deposition technology to generate a nano copper oxide coating on the surface of the copper powder sintered layer;

[0019] S5. Using the selective laser melting process, an asymmetric honeycomb support column array is formed at the bottom of the vacuum cavity.

[0020] S6. Use diffusion welding to weld and press the outer edge joints of the first cover plate and the second cover plate to form a closed vacuum cavity.

[0021] S7. After the diffusion welding of the first cover plate and the second cover plate is completed, a refrigerant is injected into the vacuum chamber, and the first cover plate and the second cover plate are packaged and the welding surface is milled flat to obtain a multi-level capillary structure temperature balancing plate.

[0022] As a further improvement of the above technical solution, in step S2, the thickness of the copper powder sintered layer is 200-400 μm; the sintering temperature of the copper powder gradient sintering is 650±20° C., and the sintering is performed under a hydrogen protection environment.

[0023] As a further improvement of the above technical solution, in step S3, the depth of the micro groove is 50 μm; the width of the micro groove gradually increases from the heat source area to the heat source area, and is adjustable within the range of 80-150 μm.

[0024] As a further improvement of the above technical solution, in the step S4, a nano copper oxide coating is generated on the surface of the copper powder sintered layer by chemical vapor deposition of a mixed gas of oxygen and copper acetylacetonate at high temperature; the chemical vapor deposition technology uses Cu(hfac)2 as a precursor for chemical vapor deposition, uses N2 / H2 mixed gas as a carrier gas, the deposition temperature is greater than 360°C, the deposition time is 30 minutes, and the coating thickness of the nano copper oxide coating (5) is 80nm.

[0025] As a further improvement of the above technical solution, in step S5, the laser power of the selective laser melting process is 180-220 W, the scanning speed is 750@850 mm / s, and the layer thickness is 30 μm.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] (1) The present invention combines three different capillary structures: a copper powder sintered layer, radial microgrooves, and a nano-copper oxide coating, to form a unique multi-level capillary structure. This innovative structural design breaks the limitations of traditional single capillary structures, can better balance capillary force and permeability, and improve the transmission efficiency and heat dissipation performance of the working fluid. Compared with traditional temperature dispersion plates, this multi-level capillary structure can more effectively adapt to different heat flux densities and working environments, and has a wider range of application prospects.

[0028] (2) The multi-level capillary structure heat spreader described in the present invention utilizes an asymmetric honeycomb support column whose diameter varies gradually along the heat source. This design not only optimizes the steam flow path and reduces pressure drop, but also balances local thermal resistance with overall lightweight requirements, avoiding redundant material at the far end. This innovative support column design provides new ideas and methods for optimizing the structure of heat spreaders.

[0029] (3) The multi-level capillary structure heat spreader described in the present invention utilizes a variety of advanced manufacturing processes, including selective laser melting, chemical vapor deposition, and diffusion welding, to manufacture the heat spreader. The combined application of these processes effectively ensures the manufacturing precision and quality of the heat spreader, while also improving production efficiency and reducing production costs. In particular, the application of selective laser melting enables the integrated molding of the asymmetric honeycomb support column array and the cavity, avoiding the potential drawbacks of traditional welding processes and providing strong support for the high performance and reliability of the heat spreader. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the structure of the multi-level capillary structure temperature equalizing plate in the present invention;

[0031] Figure 2 Schematic diagram of the cross-sectional structure of the multi-level capillary structure temperature equalizing plate in the present invention;

[0032] Figure 3 Schematic diagram of the distribution of an asymmetric honeycomb support column array;

[0033] Figure 4 A locally enlarged schematic diagram of the radial microgrooves in the multi-level capillary structure.

[0034] Description of reference numerals:

[0035] 1. First cover plate; 2. Second cover plate; 21. Liquid filling port; 3. Copper powder sintering layer; 4. Radial groove layer; 41. Micro groove; 42. Heat source area; 5. Nano copper oxide coating; 6. Asymmetric honeycomb support column array; 7. Vacuum cavity. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the accompanying drawings:

[0037] like Figures 1 to 4 The multi-level capillary structure heat spreader shown is composed of an asymmetric honeycomb support column array 6, a multi-level capillary structure, and a vacuum cavity 7. The diameter of the asymmetric honeycomb support column array 6 varies in a gradient along the direction of the heat source; the multi-level capillary structure is composed of a nano-copper oxide coating 5, radial micro-grooves 4, and a copper powder sintered layer 3; and the vacuum cavity is formed by welding a first cover plate 1 and a second cover plate 2. The multi-level capillary structure heat spreader provided by the present invention solves the systematic deficiencies in the existing solutions in the "structure-material-process" coordinated optimization through gradient support columns, multi-level capillary structure, and optimization of heterogeneous material interfaces, providing an innovative solution for thermal management of electronic equipment.

[0038] Specifically, if Figure 1 As shown, the multi-level capillary structure temperature equalizing plate includes: a first cover plate 1 and a second cover plate 2; a receiving groove is provided in the middle of the second cover plate 2; the first cover plate 1 is installed above the notch of the receiving groove, and the first cover plate 1 and the receiving groove form a vacuum cavity 7; a capillary structure is provided on the inner wall of the vacuum cavity; the capillary structure includes a copper powder sintered layer 3, a radial groove layer 4 and a nano copper oxide coating 5 arranged in sequence from the outside to the inside; an asymmetric honeycomb support column array 6 is provided in the vacuum cavity 7.

[0039] The multi-level capillary structure heat spreader can be divided into an evaporation zone and a condensation zone. The evaporation zone refers to the area in the heat spreader that is close to the heat source and where the working medium (refrigerant) absorbs heat and quickly evaporates into steam. In this multi-level capillary structure heat spreader, since heat is first transferred from the external heat source to the heat spreader, the heat is concentrated in the area that is in close contact with the heat source, causing the refrigerant in this area to quickly change from liquid to gas after absorbing heat. This is the evaporation zone. The function of the evaporation zone is to convert the heat of the heat source into the internal energy of steam, providing power for the transfer and diffusion of heat. The condensation zone refers to the area in the heat spreader where steam is cooled and condensed into liquid again in an area away from the heat source and with a lower temperature. Steam diffuses and migrates from the evaporation zone to the lower temperature area in the heat spreader, releasing heat in these areas and turning back into liquid. This area is the condensation zone. The condensed liquid can then flow back to the evaporation zone through the capillary structure in the heat spreader (such as a capillary structure composed of a copper powder sintered layer, a nano-copper oxide coating, etc.) and continue to participate in the heat transfer cycle.

[0040] As a further improvement to the above technical solution, the receiving groove is stamped in the middle of the second cover plate 2, and the outer edge of the groove forms a flange plate. The flange plate is the portion extending outward from the edge of the receiving groove, providing a structural foundation for subsequent assembly and connection operations.

[0041] As a further improvement of the above technical solution, the first cover plate 1 is pressed onto the notch of the receiving groove on the second cover plate 2 by diffusion welding to form a vacuum cavity 7. The thickness of the vacuum cavity 7 is less than 0.5 mm, and the vacuum degree is 5×10 - 4 Pa. Preferably, the vacuum sealing cavity has a thickness of 0.45 mm and is formed by diffusion welding and pressing a double-layer cover plate (a first cover plate 1 and a second cover plate 2). Both the first cover plate 1 and the second cover plate 2 are made of copper-clad aluminum nitride. Diffusion welding is a solid-state welding method that achieves connection by causing atoms to diffuse into each other through microscopic plastic deformation of the surface to be welded under a certain temperature and pressure. In the manufacturing process of the multi-level capillary structure temperature equalizer described in the present invention, the first cover plate 1 is pressed onto the notch of the receiving groove of the second cover plate 2 by diffusion welding. The purpose of this is to form a vacuum cavity 7, which is an enclosed space inside the temperature equalizer. This vacuum cavity 7 is very critical to the operation of the temperature equalizer, because the temperature equalizer achieves efficient heat transfer and uniform distribution by the phase change (evaporation and condensation) of the internal refrigerant under a vacuum environment. The vacuum cavity 7 can reduce the interference of gases such as air on heat transfer, improve the efficiency of heat transfer, and also provide a suitable working environment for the internal capillary structure and support structure.

[0042] As a further improvement to the above technical solution, a filling port 21 is provided at the front end of the flange of the second cover plate 2. This filling port 21 is connected to the receiving tank. The receiving tank is filled with a refrigerant, a graphene / acetone mixture containing 0.5 wt% nanodiamond particles (particle size 30 nm). The refrigerant is injected into the receiving tank through the filling port 21. After the receiving tank is completely filled with refrigerant, the filling port is sealed to prevent leakage.

[0043] As a further improvement to the above technical solution, the copper powder sintered layer 3 is fixed to the inner walls of the first and second cover plates 1 and 2 by performing high-temperature gradient sintering of the copper powder. The copper powder sintered layer 3 is laid on the inner walls of the vacuum chamber 7 through gradient sintering. The thickness of the copper powder sintered layer 3 is 200-400 μm, and the sintering temperature is 650±20°C. A hydrogen atmosphere is used during the sintering process, and the sintering time is 30-60 minutes. The evaporation zone of the multi-level capillary structure heat spreader is sintered with high-mesh fine copper powder to form a high-density, small-pore structure; the condensation zone is sintered with low-mesh coarse copper powder to form a large-pore structure. This structure with different pore sizes acts as a capillary force during the liquid transport process. The high-density, small-pore area sintered with fine copper powder utilizes capillary force to better distribute and rise the liquid in the evaporation zone, facilitating liquid evaporation; while the large-pore area sintered with coarse copper powder facilitates the reflux of the condensed liquid under capillary force, promoting the entire refrigerant circulation process.

[0044] Specifically, the characteristic of gradient sintering lies in the different treatment methods used for the evaporation zone and condensation zone of the multi-level capillary structure heat spreader: in the evaporation zone, fine copper powder with a high mesh count is used for sintering, and the resulting structure has the characteristics of high density and small pore size. The dense small-pore structure formed by sintering fine copper powder with a high mesh count is conducive to the rapid evaporation of liquid in the evaporation zone, because the larger specific surface area can accelerate the vaporization rate of the liquid, thereby efficiently absorbing heat. In the condensation zone, coarse copper powder with a low mesh count is used for sintering, forming a large-pore structure. The large-pore structure facilitates the rapid reflow of steam after condensation, allowing the liquid refrigerant to smoothly return to the evaporation zone to continue participating in heat exchange. This design can optimize the refrigerant circulation process within the entire heat spreader and improve the heat dissipation efficiency of the heat spreader.

[0045] As a further improvement of the above technical solution, Figure 4 As shown, the radial micro-grooves 4 include a plurality of micro-grooves 41; the plurality of micro-grooves 41, starting from the center of the heat source, extend radially outward to form a multi-branch flow channel network. The starting points of the plurality of micro-grooves 41 enclose a circular area, which is the heat source area 42. This structure also has a capillary effect and can guide the liquid to flow in the groove. The width of the micro-grooves 41 is adjustable in the range of 80-150μm. The width of the grooves close to the heat source area 42 is narrower, and the width gradually increases away from the heat source area 42. The narrower grooves are close to the heat source and use capillary force to quickly absorb the liquid generated by the heat. As the grooves become wider, the liquid can diffuse and reflux better away from the heat source area, and cooperate with the overall heat flow distribution to promote heat transfer and circulation of liquid in the temperature homogenizing plate.

[0046] In the multi-level capillary structure heat spreader described in the present invention, the radial micro-grooves 4 are an important component. The radial micro-grooves 4 take the center of the heat source as the starting point and extend radially outward, eventually forming a flow channel network with multiple branches. Such a flow channel network structure design can make the working medium (such as refrigerant) in the heat spreader more effectively disperse and transfer heat when flowing in the flow channel. The width of the radial micro-grooves 4 can be adjusted within the range of 80 to 150 microns. In addition, the width of the micro-grooves close to the heat source area is relatively narrow, and as the distance from the heat source area becomes farther and farther, the width of the micro-grooves gradually increases. Close to the heat source area, the heat flux density is relatively large, and the narrower grooves can make the working medium have a higher flow rate and flow rate in this area, thereby absorbing and taking away heat more quickly. Far away from the heat source area, the heat flux density gradually decreases, and the wider grooves can provide a smoother flow channel for the working medium, and can also slow down the flow rate of the working medium to a certain extent, so that it can better release and distribute heat. The structural design of the radial micro-grooves 4 of the present invention helps to optimize the heat transfer process in the temperature evaporating plate, thereby improving the heat dissipation performance and temperature uniformity of the temperature evaporating plate.

[0047] As a further improvement of the above technical solution, the nano copper oxide coating 5 is formed by chemical vapor deposition of a mixture of oxygen and copper acetylacetonate at high temperature. The thickness of the nano copper oxide coating 5 is 50 to 100 nm, and its preparation method is chemical vapor deposition, the deposition temperature is 450°C, and the reaction gas is a mixture of oxygen and copper acetylacetonate. The nano copper oxide coating is used to enhance the wettability of the surface, thereby indirectly improving the capillary effect. When the liquid flows in the copper powder sintered layer 3 and the radial micro grooves 4, the nano copper oxide coating 5 can make the liquid adhere and flow better, further optimize the liquid transmission performance of the entire multi-level capillary structure, and thus improve the heat dissipation efficiency of the heat spreader.

[0048] As a further improvement of the above technical solution, Figure 2 and Figure 3 As shown, the asymmetric honeycomb support column array 6 includes a plurality of support columns, and the plurality of support columns are in a honeycomb structure. The diameter of the asymmetric honeycomb support column array 6 changes in a gradually shrinking gradient along the direction of the heat source, and the support columns are integrated with the vacuum cavity through the SLM process; the honeycomb structure is a geometric arrangement similar to a honeycomb. Honeycomb structure is widely used in the fields of materials science and engineering because it can reduce the amount of material used while ensuring a certain structural strength. In this embodiment, the support column array adopts a honeycomb arrangement, which has efficient space utilization and good mechanical properties. The honeycomb support column array can effectively support the upper and lower cover plates to prevent the cavity from deforming under vacuum environment and thermal stress. Moreover, this structure can also provide a certain channel for the flow of steam and liquid, so that the internal working medium (such as refrigerant) can flow smoothly in the gap between the support columns.

[0049] As a further improvement to the above technical solution, the multiple support columns arranged in a honeycomb structure can be arranged asymmetrically. In areas close to the heat source, the distribution density, shape, or arrangement of the multiple support columns can differ from those in areas further away. To better conduct heat and guide steam flow near the heat source, the support columns can be arranged more closely or in a specific orientation to accommodate the complex heat and steam flow conditions near the heat source.

[0050] As a further improvement of the above technical solution, the support column is truncated cone-shaped, and its diameter decreases gradually along the direction of the heat source. In this embodiment, the diameter of the support column gradually increases from the first cover plate to the second cover plate. The asymmetric design of the support column diameter is to optimize the steam flow path. In the area close to the heat source, the amount of steam generated is relatively large. The use of a support column with a larger diameter can provide sufficient space for the steam to diffuse quickly, reducing the resistance to steam flow (reducing the pressure drop). As the distance from the heat source increases, the amount of steam gradually decreases, and the diameter of the support column also decreases accordingly. This can avoid material redundancy and achieve lightweight overall structure.

[0051] As a further improvement to the above technical solution, the asymmetric honeycomb support column array 6 is integrated with the vacuum cavity 7 through a selective laser melting process, and the interface bonding strength is greater than 300MPa. The selective laser melting process is an advanced additive manufacturing technology that uses a high-energy laser beam to melt metal powder layer by layer along a preset path to construct a three-dimensional solid structure. This process enables the support column array and the vacuum cavity 7 to be tightly combined together, and the interface bonding strength between the two is greater than 300MPa, ensuring the stability of the heat spreader structure, avoiding structural damage or performance degradation due to loose bonding, and effectively preventing defects such as pores and cracks that may occur when welding dissimilar materials.

[0052] As a further improvement of the above technical solution, the support column is made of titanium alloy material, and the diameter is gradually reduced from 0.8mm to 0.3mm along the direction of the heat source. This design can optimize the steam flow path and reduce the pressure drop. The gradient change balances the local thermal resistance and the overall lightweight requirements, and can avoid remote material redundancy.

[0053] Titanium alloys offer advantages such as low density, high strength, high temperature resistance, and corrosion resistance. Using titanium alloy as the support column material in the vapor chamber ensures sufficient strength to support the vacuum chamber and prevent deformation under vacuum conditions. Its low density also reduces the overall weight of the vapor chamber, meeting the demand for lightweight electronic equipment.

[0054] The diameter of the support column decreases gradually from 0.8mm to 0.3mm along the direction of the heat source. This gradient change in diameter plays an important role: on the one hand, it optimizes the flow path of steam in the heat spreader. In the area close to the heat source, the larger diameter support column can provide a wider channel for the steam, so that the steam can quickly diffuse away from the heat source, reducing the resistance to steam flow, thereby reducing the pressure drop and improving the steam transmission efficiency. On the other hand, this gradient change balances the needs of local thermal resistance and overall lightweighting. At the far end away from the heat source, the smaller diameter support column reduces the amount of material used and avoids material redundancy. While ensuring the overall performance of the heat spreader, the weight of the heat spreader is reduced, making it more suitable for electronic devices with strict weight requirements, such as portable electronic devices.

[0055] The present invention also includes a method for preparing the multi-level capillary structure temperature averaging plate, the method comprising the following steps:

[0056] S1. Prepare a first cover plate 1 and a second cover plate 2, and punch a receiving groove in the middle portion of the second cover plate 2. The first cover plate 1 and the receiving groove form a vacuum chamber 7.

[0057] S2. Gradual sintering of copper powder is performed on the inner wall of the vacuum cavity 7 to form a copper powder sintered layer 3 of a specific thickness. This process is completed under specific temperature conditions and a hydrogen protection environment.

[0058] The copper powder gradient sintering process involves sintering copper powders of different specifications according to the functional requirements of different areas. Fine copper powder with a high mesh count is used in the evaporation zone to form a high-density, small-pore structure, which facilitates rapid evaporation of liquid in this area. Coarse copper powder with a low mesh count is used in the condensation zone to form a large-pore structure, which facilitates rapid reflow of the condensed liquid. By performing the copper powder gradient sintering on the inner wall of the vacuum chamber, a copper powder sintered layer 3 with excellent capillary properties is formed on the inner wall of the vacuum chamber to promote refrigerant circulation and heat transfer. Preferably, the thickness of the copper powder sintered layer 3 is 200-400 μm. This appropriate thickness ensures that the copper powder sintered layer has sufficient strength and stability, as well as good capillary properties and thermal conductivity. The copper powder gradient sintering process is performed at a temperature of 650±20°C under a hydrogen-protected atmosphere. This carefully designed sintering temperature range ensures that the copper powder is fully fused during the sintering process to form the desired structure and properties. If the temperature is too high, the copper powder may over-melt and damage the structure; if the temperature is too low, the copper powder may not be fully sintered, affecting the capillary properties and bonding strength. The entire sintering process must be carried out in a hydrogen atmosphere to prevent the copper powder from oxidizing at high temperatures, ensuring the quality and performance of the copper powder sintered layer, and thus improving the heat dissipation effect of the vapor chamber.

[0059] S3. Using laser engraving and mold imprinting technology, radial micro grooves 4 are processed on the surface of the copper powder sintered layer 3.

[0060] Laser engraving has the characteristics of high precision and high energy density, and can accurately etch the required groove shape on the copper powder sintered layer; mold imprinting can use pre-made molds to imprint the copper powder sintered layer, further improving and refining the shape and size of the groove, ensuring the quality and consistency of the micro groove.

[0061] The radial microgrooves 4 include multiple microgrooves 41, which enclose a circular area. Starting from the center of the heat source, the multiple microgrooves 41 extend radially outward at equal intervals to form a multi-branch flow channel network. This innovative radial microgroove structure optimizes the flow path of the working medium within the heat spreader, improving the efficiency and uniformity of heat transfer. Guided by the microgrooves, the working medium can circulate more orderly between the evaporation zone and the condensation zone, thereby quickly dissipating heat from the heat source to the surrounding environment, improving the heat dissipation performance and temperature uniformity of the heat spreader, and ensuring that electronic equipment operates in a stable temperature environment.

[0062] The depth of the micro groove 41 is 50 μm. The appropriate depth can ensure that the working medium has enough flow space in the micro groove, while not increasing the difficulty of processing and affecting the overall structural strength of the temperature equilibrium plate due to being too deep. The width of the micro groove 41 shows the characteristics of changing with the distance from the heat source, and is adjustable within the range of 80-150 μm. The groove width close to the heat source area is relatively narrow, and the groove width away from the heat source area gradually increases. This is because the heat flux density is large near the heat source area, and the narrower grooves can make the working medium have a higher flow rate and flow in this area, thereby absorbing and taking away heat more quickly; while away from the heat source area, the heat flux density gradually decreases, and the wider grooves can provide a smoother flow channel for the working medium, and can also slow down the flow rate of the working medium to a certain extent, so that it can better release and distribute heat.

[0063] S4. Generating a nano-copper oxide coating 5 on the surface of the copper powder sintered layer 3 by using chemical vapor deposition technology.

[0064] Chemical vapor deposition is a technology that uses gaseous substances to undergo chemical reactions on solid surfaces to produce solid deposits.

[0065] In this example, Cu(hfac)2 was used as a precursor for chemical vapor deposition. Under certain conditions, Cu(hfac)2 can decompose and release active substances such as copper ions. These active substances participate in subsequent chemical reactions, providing a copper source for the formation of the nano-copper oxide coating. Its chemical properties are stable, and under appropriate temperature and environment, the reaction process can be precisely controlled to ensure uniform coating growth.

[0066] In this embodiment, an N2 / H2 mixture was selected as the carrier gas. N2 is an inert gas that provides a stable deposition environment and prevents other impurities from interfering with the reaction. H2 has reducing properties, which not only reduces some of the oxides that may be present but also promotes the decomposition of the precursor and the reaction. The combination of the two allows for precise control of the delivery and distribution of the reaction gases, ensuring uniform deposition of the nano-copper oxide coating on the surface of the copper powder sintered layer.

[0067] In this embodiment, the deposition temperature is greater than 360°C. Within this temperature range, the precursor can fully decompose, and chemical reactions between the gaseous reactants and between the reactants and the surface of the copper powder sintered layer can proceed smoothly, promoting the formation of the nano-copper oxide coating. If the temperature is too low, the precursor will not decompose fully, the reaction rate will be slow, and it will be difficult to form a complete coating. If the temperature is too high, the coating structure may be damaged and agglomeration may occur, affecting the coating quality.

[0068] In this embodiment, the deposition time is 30 minutes. This duration ensures that the nano-copper oxide coating grows to the desired thickness at a suitable reaction rate and ensures that the coating has good density and uniformity. If the time is too short, the coating thickness will be insufficient and the performance will not be achieved. If the time is too long, the coating may be too thick, increasing unnecessary costs and even affecting the bonding strength between the coating and the copper powder sintered layer.

[0069] In this embodiment, the coating thickness is 80nm. This nanometer-level thickness fully utilizes the advantages of copper oxide in improving surface wettability and enhancing capillary action without significantly increasing the weight and thermal resistance of the vapor chamber. By optimizing the coating thickness, the efficiency of fluid transmission within the vapor chamber can be effectively improved, thereby enhancing the overall heat dissipation performance of the vapor chamber and meeting the requirements for efficient heat dissipation in electronic equipment.

[0070] S5. Using the selective laser melting (SLM) process, an asymmetric honeycomb support column array 6 is formed at the bottom of the vacuum cavity 7.

[0071] Selective laser melting is an advanced technology in the field of additive manufacturing. It is based on the principle of layer-by-layer accumulation and uses a high-energy laser beam to melt metal powder to build a three-dimensional solid structure.

[0072] In this embodiment, an asymmetric honeycomb support column array is formed by SLM technology, with a laser power of 180-220 W, a scanning speed of 750@850 mm / s, and a layer thickness of 30 μm.

[0073] Among them, the laser power of the SLM process directly affects the melting degree and molding quality of the metal powder. In the power range of 180 to 220W, it can ensure that the titanium alloy powder (support column material) forms a dense support column structure that meets the design requirements during the rapid melting and solidification process, ensuring that it has sufficient strength to support the vacuum cavity and prevent the cavity from deforming in a vacuum environment. The scanning speed of the SLM process is controlled at 750 to 850 mm / s. While ensuring processing efficiency, the laser beam can evenly and effectively melt the titanium alloy powder, ensuring the dimensional accuracy and surface quality of the support column array, so that after it is integrated with the vacuum cavity, it can stably play the role of optimizing the steam flow path and reducing the pressure drop. Layer thickness is one of the key parameters in the SLM process, which affects the accuracy and efficiency of molding. A layer thickness of 30μm strikes a good balance between precision and efficiency. It ensures the precise molding of the complex structure of the asymmetric honeycomb support column array, completes the processing within a reasonable time, and ensures that the layers are tightly bonded, giving the support column array an interfacial bonding strength greater than 300MPa, meeting the mechanical and heat dissipation requirements of the temperature spreader in practical applications.

[0074] S6. Diffusion welding is used to weld and press the outer edge joints of the first cover plate 1 and the second cover plate 2 to form a closed vacuum cavity 7, thereby creating a stable environment for heat dissipation inside the temperature homogenizing plate.

[0075] Diffusion welding, as a solid-state welding technology, plays an important role in the connection process. During welding, the outer edge joints of the first cover plate 1 and the second cover plate 2 are tightly fitted. Under the joint action of a certain temperature and pressure, the atoms on the metal surfaces of the two cover plates obtain enough energy and begin to diffuse with each other. As the diffusion process continues, the two originally separated metal surfaces gradually fuse to form a strong metallurgical bond. This welding method has significant advantages over traditional welding processes. First, diffusion welding can achieve connection without producing an obvious molten pool, avoiding defects such as pores and inclusions caused by fusion welding, and greatly improving the quality and reliability of the welded joint. Secondly, by precisely controlling parameters such as welding temperature, pressure and time, it can be ensured that the welded joint has good mechanical properties and sealing properties. For the temperature equilibrium plate, high-quality welding sealing is crucial. Only by ensuring that the first cover plate and the second cover plate are tightly welded to form a vacuum degree of 5×10 - 4 Pa and a vacuum cavity with a thickness of less than 0.5mm can provide a stable environment for the phase change cycle and heat transfer of the internal refrigerant, prevent outside air from entering and interfering with the heat dissipation process, and ensure the efficient and stable operation of the temperature vapor chamber.

[0076] S7. After the diffusion welding of the first cover plate 1 and the second cover plate is completed, refrigerant is injected into the vacuum chamber 7 from the liquid filling port, and the first cover plate 1 and the second cover plate 2 are packaged and the welding surface is milled flat to obtain a multi-level capillary structure temperature equalizing plate.

[0077] After assembling and soldering the components of a multi-level capillary structure vapor chamber, encapsulation and milling are crucial finishing steps that determine product quality and practicality. Encapsulation further ensures the vapor chamber's internal vacuum chamber remains sealed, preventing the ingress of impurities such as air and moisture. The refrigerant within the vapor chamber undergoes a cycle of evaporation and condensation in a vacuum environment, achieving efficient heat dissipation. Any ingress of foreign matter not only disrupts the vacuum environment but also potentially affects the refrigerant's performance, significantly reducing the vapor chamber's heat dissipation efficiency. Therefore, the encapsulation process requires specialized sealing techniques and materials, and rigorous treatment of areas with potential gaps, such as the liquid filling port, to ensure the vapor chamber's seal and stability during subsequent use. Milling the weld surface is primarily required to ensure proper alignment between the vapor chamber and the heat-generating components of electronic devices. Vapor chambers typically need to fit tightly against heat-generating components such as chips to ensure rapid heat transfer. Uneven or raised weld surfaces can create air gaps between the vapor chamber and the heat-generating component. Air has a much lower thermal conductivity than metal, significantly increasing thermal resistance and severely impacting the vapor chamber's heat dissipation. Through the milling operation, defects such as weld nodules and unevenness generated during the welding process can be removed, so that the surface of the heat spreader reaches an extremely high level of flatness, ensuring that it fits tightly with the heating element and reducing the contact thermal resistance, thereby giving full play to the heat dissipation performance of the heat spreader and providing efficient and stable heat dissipation guarantee for electronic equipment. Ultimately, a finished product with a multi-level capillary structure of the heat spreader with excellent performance and meeting the use standards is obtained.

[0078] In summary, the multi-level capillary structure of the heat spreader described in this invention offers significant advantages. Its multi-level capillary structure, composed of a sintered copper powder layer, radial microgrooves, and a nano-copper oxide coating, combined with an asymmetric honeycomb support column array, enables efficient fluid transmission and optimized steam flow within the heat spreader, significantly improving its heat dissipation efficiency and ensuring temperature uniformity. Furthermore, the integrated molding of the heat spreader, achieved through the use of advanced processes such as diffusion welding and SLM, results in a thin and compact vacuum chamber. This achieves lightweight design while ensuring an interface bonding strength exceeding 300 MPa. This design combines high reliability, stability, and manufacturing precision, making it a perfect fit for electronic devices with demanding heat dissipation and space requirements.

[0079] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A multi-level capillary structure temperature plate, characterized in that: The multi-level capillary structure temperature equalizing plate comprises: a first cover plate (1) and a second cover plate (2); a receiving groove is provided in the middle of the second cover plate (2); the first cover plate (1) is installed above the notch of the receiving groove, and the first cover plate (1) and the receiving groove form a vacuum cavity (7); a capillary structure is provided on the inner wall of the vacuum cavity (7); the capillary structure comprises a copper powder sintered layer (3), a radial groove layer (4) and a nano copper oxide coating (5) arranged in sequence from the outside to the inside; and an asymmetric honeycomb support column array (6) is provided in the vacuum cavity (7).

2. The multi-level capillary structure temperature evaporating plate according to claim 1, characterized in that: The accommodating groove is formed by punching in the middle of the second cover plate (2), and the outer edge of the notch of the accommodating groove forms a flange plate; the first cover plate (1) is pressed onto the notch of the accommodating groove on the second cover plate (2) by diffusion welding to form a vacuum cavity (7); the thickness of the vacuum cavity (7) is less than 0.5 mm, and the vacuum degree is 5×10 -4 Pa.

3. The multi-level capillary structure temperature equalizing plate according to claim 1, characterized in that: A liquid filling port (21) is provided at the front end of the flange plate of the second cover plate (2), and the liquid filling port (21) is connected to the accommodating tank; the accommodating tank is filled with a refrigerant, which is a graphene / acetone mixed liquid containing 0.5wt% nano-diamond particles, and the refrigerant is injected into the accommodating tank through the liquid filling port (21).

4. The multi-level capillary structure temperature equalizing plate according to claim 1, characterized in that: The copper powder sintered layer (3) is laid on the inner walls of the vacuum cavity (7) through gradient sintering; the thickness of the copper powder sintered layer (3) is 200-400 μm, the sintering temperature is 650±20° C., hydrogen atmosphere protection is adopted during the sintering process, and the sintering time is 30-60 minutes.

5. The multi-level capillary structure temperature equalizing plate according to claim 1, characterized in that: The radial micro grooves (4) include a plurality of micro grooves (41); the plurality of micro grooves (41) are radially extended outwards from the heat source center to form a multi-branch flow channel network; The starting points of the plurality of micro grooves (41) form a circular area, which is a heat source area (42); the width of the micro grooves (41) is adjustable within the range of 80 to 150 μm.

6. The multi-level capillary structure temperature equalizing plate according to claim 1, characterized in that: The nano copper oxide coating (5) has a thickness of 50-100 nm and is prepared by a chemical vapor deposition process at a deposition temperature of 450° C. The reaction gas is a mixed gas of oxygen and copper acetylacetonate.

7. The multi-level capillary structure temperature evaporating plate according to claim 1, characterized in that: The asymmetric honeycomb support column array (6) comprises a plurality of support columns, and the plurality of support columns form a honeycomb structure; the diameter of the asymmetric honeycomb support column array (6) changes in a gradually shrinking gradient along the direction of the heat source, and the support columns are integrally formed with the vacuum cavity through the SLM process; The multiple support columns arranged in a honeycomb structure adopt an asymmetric layout; the support columns are truncated cone-shaped, and their diameters decrease gradually along the direction of the heat source; the support columns are made of titanium alloy material, and their diameters decrease gradually from 0.8mm to 0.3mm along the direction of the heat source.

8. The multi-level capillary structure temperature equalizing plate according to claim 1, characterized in that: The asymmetric honeycomb support column array (6) is integrally formed with the vacuum cavity (7) through a selective laser melting process, and the interface bonding strength is greater than 300 MPa.

9. The method for preparing a multi-level capillary structure temperature equalizing plate according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: S1. Prepare a first cover plate (1) and a second cover plate (2), and punch a receiving groove in the middle portion of the second cover plate (2), wherein the first cover plate (1) and the receiving groove enclose a vacuum cavity (7); S2, performing gradient sintering of copper powder on the inner wall of the vacuum cavity (7) to form a copper powder sintered layer (3) of a specific thickness; S3, using laser engraving and mold imprinting technology to process radial micro grooves (4) on the surface of the copper powder sintered layer (3); S4, using chemical vapor deposition technology to generate a nano copper oxide coating (5) on the surface of the copper powder sintered layer (3); S5, using a selective laser melting process to form an asymmetric honeycomb support column array (6) at the bottom of the vacuum cavity (7); S6. Using diffusion welding to weld and press together the outer edge joints of the first cover plate (1) and the second cover plate (2) to form a closed vacuum cavity (7); S7. After the diffusion welding of the first cover plate (1) and the second cover plate (2) is completed, a refrigerant is injected into the vacuum cavity (7), and the first cover plate (1) and the second cover plate (2) are packaged and the welding surface is milled flat to obtain a multi-level capillary structure temperature equalizing plate.

10. The method for preparing a multi-level capillary structure temperature evaporating plate according to claim 9, characterized in that: In the step S2, the thickness of the copper powder sintered layer (3) is 200-400 μm; the sintering temperature of the copper powder gradient sintering is 650±20° C., and the sintering is performed under a hydrogen protection environment; In step S3, the depth of the micro groove (41) is 50 μm; the width of the micro groove (41) gradually increases from the heat source area to the heat source area, and is adjustable within the range of 80-150 μm; In the step S4, a nano copper oxide coating (5) is formed on the surface of the copper powder sintered layer (3) by chemical vapor deposition of a mixed gas of oxygen and copper acetylacetonate at high temperature; the chemical vapor deposition technology uses Cu(hfac)2 as a precursor for chemical vapor deposition, uses N2 / H2 mixed gas as a carrier gas, the deposition temperature is greater than 360°C, the deposition time is 30 minutes, and the coating thickness of the nano copper oxide coating (5) is 80nm; In step S5, the laser power of the selective laser melting process is 180-220 W, the scanning speed is 750@850 mm / s, and the layer thickness is 30 μm.

Images