Stainless steel vapor chamber and manufacturing method

Abstract

The invention discloses a stainless steel vapor chamber and a manufacturing method. The stainless steel vapor chamber comprises stainless steel cover plates, a wick is arranged on the inner surface of at least one stainless steel cover plate, a micron structure with a preset geometrical morphology is etched on the surface of the wick, and nano anchor points are formed on the surface of the micron structure through acid solution activation reaction pitting corrosion. A metal compound nanowire structure is separated out in situ on the surface nano anchor point of the wick through a hydrothermal reaction. The manufacturing method of the stainless steel vapor chamber comprises a modification step, an activation step and a growth step. According to the micro-nano composite structure formed in the etching-activation-hydrothermal mode, the stability of the heat transfer effect is guaranteed, the liquid phase supplementing speed is increased, the wettability is improved, the phase change heat resistance is reduced, and the heat exchange efficiency of the stainless steel vapor chamber is also improved.

Description

Technical Field

[0001] This application relates to thermal management technology, and more specifically to a stainless steel heat spreader and its manufacturing method. Background Technology

[0002] With the rapid development of electronic devices towards higher integration and higher heat flux density, heat dissipation performance has become a core factor restricting equipment reliability. As a key component of thermal management, heat spreaders play an irreplaceable role in high-power electronic devices. Compared to mainstream copper-based heat spreaders, stainless steel substrates offer advantages in high strength, lightweight, and low cost, making them a highly promising alternative. However, stainless steel heat spreaders face the following key bottlenecks in practical applications:

[0003] Firstly, stainless steel has low surface energy and is chemically inert, resulting in poor liquid wettability. This poor wettability leads to a low capillary limit, making it difficult to generate sufficient capillary pressure difference to drive the working fluid backflow. Consequently, it is prone to drying out under high power heat load conditions, causing heat dissipation failure.

[0004] Secondly, the thermal conductivity of stainless steel is much lower than that of copper, resulting in high nucleation thermal resistance. If there are no efficient phase transformation nucleation sites, the boiling initiation superheat will be too high, causing the device to experience a sharp temperature rise, significantly reducing thermal management efficiency and affecting the performance.

[0005] Thirdly, the contradiction between interface stability and thermal resistance is prominent. Some heat spreaders have tried to add a hydrophilic layer to improve wettability, but due to the dense passivation layer on the stainless steel surface, the artificially constructed hydrophilic layer is only weakly physically attached to the substrate rather than chemically bonded. Under frequent thermal cycling, the hydrophilic layer is prone to peeling off, leading to heat transfer failure, and the interface contact thermal resistance is significant.

[0006] In summary, achieving synergistic optimization of efficient capillary reflux channels, high-density vaporization cores, and strong interfacial bonding capabilities on stainless steel, an inert substrate, has become a critical technical bottleneck that urgently needs to be overcome in the development of high-performance stainless steel heat exchangers. Summary of the Invention

[0007] This application aims to overcome the shortcomings of existing stainless steel heat exchange plates, such as poor surface wettability, high nucleation thermal resistance, and poor thermal cycling stability caused by weak bonding between micro-nano structures and inert substrates. It provides a stainless steel heat exchange plate and manufacturing method to improve the stability of heat transfer, reduce thermal resistance, and enhance wettability and heat exchange efficiency.

[0008] To achieve the above objectives, in a first aspect, this application provides a stainless steel heat spreader, which includes a stainless steel cover plate. At least one stainless steel cover plate has a liquid-absorbing core on its inner surface. The surface of the liquid-absorbing core is etched with a micron structure of a predetermined geometric shape. The surface of the micron structure is activated by an acidic solution to form nano-anchor points. The liquid-absorbing core precipitates metal compound nanowire structures in situ at the surface nano-anchor points through a hydrothermal reaction.

[0009] In at least one embodiment, the micron structure is a micron-scale recessed array constructed on the surface of the liquid wick by laser etching. The surface of the recessed array has a remelted layer formed by a laser heat-affected zone. The surface of the remelted layer is distributed with non-equilibrium defects that serve as nano-anchors for in-situ growth of nanowire structures and exposed metal substrate.

[0010] In at least one embodiment, a metal oxide nanowire structure is chemically bonded in situ to the concave array surface via nano-anchors, and the nanowire structure and the concave array surface form a seamless mechanical-chemical interlocking structure at the contact point.

[0011] In at least one embodiment, a macroscopic replenishment channel composed of a concave array of micrometer structures and a microscopic superhydrophilic nucleation surface composed of nanowire structures are spatially combined to form a coupled cyclic interface.

[0012] In at least one embodiment, the ratio of the cross-sectional depth to the cross-sectional width of the recessed array of micron-structures is 0.5-2.0.

[0013] In at least one embodiment, the nanowire structure is a CuO nanowire structure.

[0014] Secondly, this application provides a method for manufacturing a stainless steel heat exchange plate, which includes the following steps: The modification step involves laser etching a micron-sized structure with a predetermined geometric shape onto the surface of the liquid-absorbing core of the stainless steel cover plate. In the activation step, the absorbent core is immersed in an acidic solution to carry out an activation reaction, forming nano-anchors on the surface of the absorbent core; In the growth step, the liquid absorbent core is immersed in the precursor solution for hydrothermal reaction, and the nanowire structure of metal oxide is precipitated in situ at the nanoanchor points on the surface of the micron structure.

[0015] In at least one embodiment, the acidic solution is a compound acid solution composed of 5%-10% sulfuric acid and 1%-3% hydrochloric acid by mass; the compound acid solution uses the strong penetrating power of chloride ions to target and etch micron-structured surfaces to construct nano-anchors.

[0016] In at least one embodiment, in the activation step, the activation reaction temperature is 20-40°C and the processing time is 2-8 min.

[0017] In at least one embodiment, the precursor solution is a mixed solution of copper acetate and hexamethylenetetramine, both with a concentration of 0.02-0.1 mol / L; the hydrothermal reaction temperature is 80-100℃, and the reaction time is 3-8 h; the nanowire structure is a CuO nanowire structure.

[0018] This application etches micron-sized structures onto the surface of a liquid absorber core. These micron-sized structures, after activation, form nano-anchors. The nano-anchors then undergo a hydrothermal reaction to generate nanowire structures. This etching-activation-hydrothermal method creates a micro / nano composite structure. On one hand, it achieves lattice-level coupling (chemical bonding) between the nanowire structure and the liquid absorber core surface, resulting in high interfacial stability and minimizing nanowire detachment under frequent thermal cycling, thus ensuring stable heat transfer. On the other hand, it achieves cross-scale phase change enhancement synergy, with the micron-sized structures on the liquid absorber core surface acting as the primary capillary reflux channels, utilizing La... The pressure difference guides the condensate backflow, increasing the liquid phase replenishment rate. The nanowire structure grown in situ by nano-anchors not only transforms the surface of the wick into a superhydrophilic state (contact angle <5°), improving wettability, but its microcracks also provide a massive number of vaporization nuclei, greatly increasing the vaporization nuclei density and reducing the bubble detachment diameter, thereby significantly reducing the initial superheat of nucleation boiling and lowering the phase change thermal resistance. Furthermore, this application compensates for the low thermal conductivity of the stainless steel body through extremely high interfacial heat transfer efficiency, improving the heat transfer efficiency of the stainless steel heat exchange plate.

[0019] The manufacturing method of this application overcomes the bottleneck of poor adhesion on the stainless steel surface by combining etching-activation-hydrothermal methods. It utilizes the synergistic effect of micron-structured concave array reflow and nanowire structure superhydrophilic nucleation to significantly reduce boiling initiation superheat and increase critical heat flux density. It compensates for the thermal conductivity disadvantage of stainless steel substrate by strengthening the interfacial phase change, and achieves isothermal optimization under high power load.

[0020] 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, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of this application more obvious and understandable, some embodiments are listed below for detailed description. Attached Figure Description

[0021] Figure 1 This is an exploded view of a stainless steel heat spreader according to at least one embodiment.

[0022] Figure 2 This is a cross-sectional structural schematic diagram of a stainless steel heat spreader according to at least one embodiment.

[0023] Figure 3 This is an enlarged schematic diagram of a partial structure of the suction core in at least one embodiment.

[0024] Figure 4 A flowchart illustrating a method for manufacturing a stainless steel heat spreader according to at least one embodiment.

[0025] The structures shown in the above views have been appropriately scaled down / enlarged to fit the drawing size and ensure clarity, and there is no limitation on the size of the structures shown in the views. Detailed Implementation

[0026] 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, and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the scope of protection of this application.

[0027] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0028] A stainless steel heat exchanger is a device that uses stainless steel as a base material and efficiently transfers heat through the phase change cycle of the internal working fluid. Its design aims to overcome the limitations of traditional heat exchangers in terms of strength, weight, and cost.

[0029] One or more embodiments of a stainless steel heat spreader includes a stainless steel cover plate 10, such as Figure 1 As shown. The stainless steel cover plate 10 is one of the main structural components of the heat exchanger, used to form a sealed cavity to contain the working fluid and allow it to undergo phase change circulation. The stainless steel cover plate 10 is made of stainless steel, ensuring the overall strength and corrosion resistance of the heat exchanger. The stainless steel cover plate 10 can be formed from a single piece of stainless steel through processes such as stamping, deep drawing, or welding to ensure its structural strength and sealing performance.

[0030] like Figure 1 As shown, there are two stainless steel cover plates 10, one upper and one lower. The two stainless steel cover plates 10 are sealed by laser welding. A vacuum is drawn and a working medium (usually pure water) is injected. Finally, the injection port 11 is sealed to obtain a stainless steel heat exchange plate.

[0031] like Figure 1As shown, at least one stainless steel cover plate 10 has a liquid-absorbing core 20 on its inner surface. The liquid-absorbing core 20 is a stainless steel wire mesh / fiber felt fixed to the inner surface of the stainless steel cover plate 10 by resistance spot welding / roll welding or other methods. The main function of the liquid-absorbing core 20 is to adsorb and guide the working fluid (working medium) to circulate inside the heat spreader through capillary force. The liquid-absorbing core 20 has the functions of driving the liquid working medium backflow, providing a flow channel for the liquid working medium, promoting the gas-liquid phase change of the working medium, and transferring heat from the stainless steel cover plate 10 to the liquid working medium. It is a key component for the heat spreader to achieve efficient phase change heat transfer.

[0032] In addition, such as Figure 1 As shown, support columns 30 are evenly distributed between the upper and lower stainless steel cover plates 10. The support columns 30 are used to support the upper and lower stainless steel cover plates 10, reducing the probability of deformation. In some embodiments, through holes may be provided inside the support columns to allow the condensed liquid above to flow downward to the liquid-absorbing core of the lower stainless steel cover plate.

[0033] like Figure 2 As shown, a micron-sized structure 40 with a predetermined geometric morphology is etched onto the surface of the absorbent core 20. The micron-sized structure 40 serves as a capillary reflux channel for the liquid working fluid, utilizing the Laplace pressure difference to guide the reflux of the liquid working fluid and improve the replenishment rate. A dense network of nano-anchors is formed on the surface of the micron-sized structure 40 through an acidic solution activation reaction. These nano-anchors are nanoscale attachment sites formed on the surface of the micron-sized structure 40 after the reaction, serving as the basis for subsequent nanowire structure growth and ensuring a stable bond between the nanowire structure and the surface of the absorbent core 20. The absorbent core 20 then precipitates metal compound nanowire structures in situ at the surface nano-anchors via a hydrothermal reaction. Nanowire structures refer to linear structures with nanometer diameters and large aspect ratios formed in situ on nano-anchors. These nanowire structures can significantly increase surface area, improve surface wettability, and provide high-density phase transformation nucleation sites. In-situ precipitation means that the target material (metal compound nanowires) grows or forms directly on the predetermined substrate surface without additional transfer or assembly steps. In-situ precipitation can usually ensure a tight interfacial bond between the material and the substrate.

[0034] Thus, a micron-sized structure 40 is etched onto the surface of the wick 20 on the stainless steel heat spreader. After activation, the micron-sized structure 40 forms nano-anchors. The nano-anchors undergo a hydrothermal reaction to generate nanowire structures. This micro-nano composite structure formed by etching-activation-hydrothermal methods achieves lattice-level coupling (chemical bonding) between the nanowire structure and the surface of the wick 20, resulting in high interfacial stability. It is also less prone to nanowire structure detachment under frequent thermal cycling, ensuring stable heat transfer. Furthermore, it achieves cross-scale phase change enhancement synergy. The micron-sized structure on the surface of the wick 20 acts as the main capillary reflux channel, guiding the condensate reflux using the Laplace pressure difference and increasing the liquid phase replenishment rate. The nanowire structure grown in situ by the nano-anchors transforms the surface of the wick 20 into a superhydrophilic state (contact angle <5°), improving wettability. Its microcracks also provide a massive number of vaporization nuclei, greatly increasing the vaporization nucleus density and reducing the bubble detachment diameter. This significantly reduces the initial superheat of nucleation boiling and lowers the phase change thermal resistance. On the other hand, the extremely high interfacial heat transfer efficiency of the nanowire structure compensates for the low thermal conductivity of the stainless steel body, thereby improving the heat transfer efficiency of the stainless steel heat exchange plate.

[0035] In some embodiments, such as Figure 2 As shown, the micron structure 40 is a micron-scale recessed array 400 constructed on the surface of the liquid-absorbing core 20 through laser etching. It includes recessed arrays extending in the length direction and recessed arrays extending in the width direction, combined to form a mesh-like micron structure 40. Laser etching utilizes a high-energy-density laser beam to irradiate the material surface, causing localized areas to melt and be removed. Its advantages include high processing precision, non-contact processing, small heat-affected zone, and ease of automation control. Figure 3 As shown, the ratio of the cross-sectional depth D to the cross-sectional width H of the micron-structured concave array 400 is 0.5-2.0, which enables the concave array 400 to provide sufficient capillary driving force to promote the rapid reflux of the working fluid when used as a liquid working fluid flow channel, while controlling the fluid resistance within a reasonable range.

[0036] like Figure 3As shown, the surface of the recessed array 400 has a remelted layer 401 formed by the laser heat-affected zone. During laser etching of the liquid wick surface, the instantaneous high temperature and rapid cooling effect during laser ablation induce a non-equilibrium remelted layer 401 with a thickness of 0.5μm-2μm on its inner wall. The remelted layer 401 is rich in lattice distortion and dislocations, destroying the inherent dense passivation layer structure of the stainless steel material, and has a different microstructure and properties from the original material. After activation, the surface of the remelted layer 401 is distributed with high-density non-equilibrium defects and exposed metal matrix, which serve as nano-anchors for the in-situ growth of nanowire structures 402. Non-equilibrium defects refer to various crystal defects formed during the rapid solidification process of the material after laser irradiation, such as dislocations, vacancies, grain boundaries, and subgrain boundaries, due to the excessively rapid cooling rate. Non-equilibrium defects usually have high surface energy and chemical activity, and can serve as active sites for subsequent chemical reactions. Exposed metal substrates refer to the fresh, unoxidized, and uncontaminated metal surfaces exposed during laser ablation, where part of the oxide or passivation layer is removed. These exposed metal surfaces possess high chemical reactivity, readily reacting with other substances and serving as active sites for subsequent chemical reactions. These non-equilibrium defects and the exposed metal substrate together constitute a high density of active sites, i.e., nanoanchors. These nanoanchors provide ideal nucleation sites and chemical bonding points for the subsequent in-situ precipitation of metal compound nanowire structures via hydrothermal reactions.

[0037] The stainless steel heat spreader, through precise control of laser ablation and utilization of thermal effects, ensures the uniform distribution and high density of nano-anchor points, thereby greatly promoting the stable and efficient growth of the nanowire structure 402 and enhancing the interfacial bonding strength between the nanowire structure 402 and the surface of the wick 20. This optimized micron structure 40 not only provides a macroscopic channel for fluid reflux but also, through its unique remelted layer 401 and nano-anchor points, lays a solid foundation for the fine construction of the nanowire structure 402, enabling the entire wick 20 to exhibit superior performance in terms of capillary properties and phase transformation nucleation.

[0038] In some embodiments, such as Figure 3As shown, metal oxide nanowire structures 402 are in-situ chemically bonded to the surface of the recessed array 400 via nano-anchors. The nanowire structures 402 and the surface of the recessed array 400 form a seamless mechano-chemical interlocking structure at the contact point. In-situ chemical bonding refers to the direct growth of the nanowire structures 402 on the nano-anchors through chemical reactions, rather than through simple physical adsorption or mechanical attachment. This chemical bonding method ensures molecular-level connections between the nanowire structures 402 and the surface of the recessed array 400, such as covalent bonds, ionic bonds, or metallic bonds, thereby significantly enhancing the bonding strength and stability of the interface. Mechanical interlocking refers to the physical anchoring effect formed by the nanowire structures embedding into the microstructures (such as nano-anchors) of the recessed array 400 surface during growth; while chemical interlocking refers to the connection achieved at the molecular level through in-situ chemical bonding. The synergistic effect of both not only eliminates microscopic gaps at the interface, reduces contact thermal resistance, and improves heat transfer efficiency, but also provides strong anti-peeling capabilities, ensuring the stability of the nanowire structures 402 under long-term thermal cycling.

[0039] The nanowire structure 402 is generated in situ on the nano-anchor points on the surface of the wick 20 via a hydrothermal reaction. Chemical bonding allows the roots of the nanowire structure 402 to embed into the substrate lattice at the nano-anchor points, forming an integrated composite structure that makes the nanowire structure more robust and less prone to detachment. Specifically, the nanowire structure 402 is a needle-like cluster of CuO nanowires. CuO has a certain degree of hydrophilicity, which is enhanced after the formation of the needle-like cluster CuO nanowire structure. Furthermore, the CuO nanowire structure can better form a chemical bond with the nano-anchor points on the surface of the stainless steel wick 20, resulting in better stability. The needle-like cluster CuO nanowire structure can serve as an efficient capillary reflux channel and a high-density vaporization nucleation site, providing fundamental support for the transport and phase transition of the working fluid.

[0040] In the liquid-absorbing core 20, a macroscopic liquid replenishment channel composed of a concave array 400 of micron-sized structures 40 and a microscopic superhydrophilic nucleation surface composed of nanowire structures 402 spatially combine to form a coupled circulation interface. The macroscopic liquid replenishment channel is a channel structure with a large geometric size formed on the surface of the liquid-absorbing core 20, mainly used to guide and transport the liquid working fluid. The microscopic superhydrophilic nucleation surface composed of nanowire structures 402 is located inside the macroscopic liquid replenishment channel, and has extremely high hydrophilicity and a large number of micro- and nano-scale structures, which can improve hydrophilicity and promote the vaporization nucleation of the liquid working fluid. The macroscopic liquid replenishment channel and the microscopic superhydrophilic nucleation surface are spatially combined, nested, or closely arranged to form a highly efficient fluid coupling circulation interface, ensuring a tight physical and functional connection between macroscopic liquid reflux and microscopic vaporization nucleation, realizing seamless fluid connection and efficient circulation, thereby significantly improving the overall heat transfer performance and anti-drying ability of the heat spreader.

[0041] One or more embodiments are methods for manufacturing stainless steel heat spreaders, which can be used to manufacture the stainless steel heat spreaders of the above embodiments. The manufacturing method includes the following steps: material preparation step, modification step, activation step, growth step, and encapsulation step, such as... Figure 4 As shown.

[0042] Before the modification step, a material preparation step is performed, namely, preparing the stainless steel cover plate 10 and the stainless steel wire mesh / stainless steel fiber felt. Generally, two stainless steel cover plates 10 are provided, such as... Figure 1 As shown, these serve as the upper and lower cover plates, respectively. Stainless steel wire mesh / stainless steel fiber felt is welded to the lower stainless steel cover plate 10 using resistance spot welding / roll welding, forming the stainless steel liquid-absorbing core 20. Some heat spreaders have liquid-absorbing cores installed on both the upper and lower cover plates. Figure 1 Only the suction core 20 arranged on the lower stainless steel cover plate 10 is shown; the suction core fixed on the upper stainless steel cover plate is not shown.

[0043] The modification step involves laser etching of the wick. Specifically, a nanosecond fiber laser with a power of 10-30W and a frequency of 20-50kHz is used to etch a micron-sized structure with a predetermined geometry onto the surface of the wick on the stainless steel cover plate. The laser energy density is controlled within 2-10 J / cm². 2 A micron-scale recessed array is etched onto the surface of the liquid-absorbing core. Utilizing the instantaneous high temperature and rapid cooling effect during laser ablation, a non-equilibrium remelted layer with a thickness of 0.5 μm-2 μm is induced on the inner wall of the recessed array. This remelted layer, rich in lattice distortion and dislocations, disrupts the inherent dense passivation layer structure of the stainless steel substrate, providing an active precursor interface for subsequent activation steps. The micron-structured recessed array, acting as a macroscopic liquid replenishment channel, significantly enhances capillary forces to promote liquid flow, thereby effectively solving the problem of low capillary limit caused by poor wettability.

[0044] The activation step is achieved by using Cl-containing compounds. -A complex acid solution containing ions activates the chromium oxide passivation film on the surface of the remelted layer. Utilizing the chemical potential gradient between the defect sites in the remelted layer and the wick substrate, the acid solution selectively peels off and pits the remelted layer. The activation step precisely constructs a high density of nanoscale pitting anchors on the inner wall of the micron-structured concave array. These nanoanchors serve as attachment sites for the subsequent hydrothermal growth of nanowires. Specifically, the wick is immersed in an acidic solution for activation at a temperature of 20-40°C for 2-8 minutes, forming nanoanchors on the surface of the remelted layer. The activation temperature is a key parameter affecting the reaction rate between the acidic solution and the wick surface. Within the temperature range of 20-40°C, the pitting process can be effectively controlled, promoting the formation of nanoanchors while avoiding excessive corrosion or insufficient reaction. The processing time determines the duration of contact and reaction between the acidic solution and the wick surface. Within this timeframe, sufficient reaction time can be ensured to form the required density of nano-anchors, while avoiding unnecessary matrix damage or uneven anchor distribution caused by excessively long reaction times.

[0045] The acidic solution is a compound acid solution composed of 5%-10% sulfuric acid and 1%-3% hydrochloric acid by mass. Sulfuric acid primarily provides a stable acidic environment to ensure the continuous activation reaction and to initially dissolve oxides on the stainless steel surface. Hydrochloric acid introduces the crucial chloride ions, whose strong penetrating power allows for targeted pitting corrosion on the concave array surface of the micron-structure to construct nano-anchors. Targeted pitting corrosion refers to the selective attack of the active component (chloride ions) in the acid solution on specific areas or defects on the remelted layer surface, forming micro-pits or pores, rather than uniform corrosion. The strong penetrating power of chloride ions allows them to penetrate the dense passivation layer (mainly chromium oxide) on the stainless steel surface, reaching the metal substrate and initiating localized pitting corrosion, thereby precisely constructing nano-anchors on the micron-structure surface for subsequent in-situ growth of nanowire structures. This compound acid solution design ensures a balanced acid ratio, avoiding insufficient or excessive corrosion that may be caused by a single acid solution. At the same time, by using pitting etching based on the characteristics of chloride ions, it directly targets the weaknesses of the passivation layer, ensuring that nano-anchors can be uniformly and densely constructed on the surface of the remelted layer. This significantly improves the efficiency of subsequent in-situ growth of nanowire structures and the stability of interfacial bonding.

[0046] The growth step involves the in-situ generation of metal oxide nanowires on the nanoanchor sites formed in the preceding steps. Specifically, the absorbent core is immersed in a precursor solution for a mild hydrothermal reaction. The precursor solution is a mixture of copper acetate and hexamethylenetetramine, both at concentrations of 0.02-0.1 mol / L. By precisely controlling the concentrations of both within the 0.02-0.1 mol / L range, the supply of reactants and the nucleation and growth rate of the nanowires can be balanced, avoiding agglomeration or inhomogeneity caused by excessively rapid growth, while ensuring sufficient growth driving force. The hydrothermal reaction temperature is controlled at 80-100℃, providing suitable reaction kinetics, allowing the CuO nanowire structure to precipitate and crystallize efficiently and orderly on the nanoanchor sites in situ, forming nanowires with good crystallinity and adhesion. The hydrothermal reaction time is controlled at 3-8 hours, ensuring that the nanowires have sufficient time to grow fully, reaching the required length and density, thereby forming a complete and robust CuO nanowire structure.

[0047] In the hydrothermal reaction, copper acetate serves as the copper source, and hexamethylenetetramine acts as a pH adjuster and complexing agent. At a reaction temperature of 80-100℃, copper ions undergo a redox reaction at the nano-anchor points and combine with hydroxide ions generated from hydrolysis, resulting in the in-situ precipitation of CuO nanowire structures. Utilizing the slow-release hydrolysis characteristics of acetate at 80-100℃, the release rate of Cu2+ is controlled, allowing for in-situ epitaxial growth of CuO nanowires at the nano-anchor points. Following the hydrothermal reaction, metal oxide nanowire structures are precipitated in-situ at the nano-anchor points on the surface of the micron-structured concave array, resulting in CuO nanowire structures. Through chemical bonding, the roots of the CuO nanowire structures are embedded in the lattice of the wicking substrate, forming an integrated composite structure. This makes the CuO nanowire structures less prone to detachment due to frequent thermal cycling.

[0048] The reactant concentration in the precursor solution is a crucial parameter affecting the growth rate, morphology, size, and density of nanowire structures. An appropriate concentration range ensures a sufficient supply of reactants while avoiding oversaturation that could lead to non-uniform nucleation or precipitation, thus impacting the quality and adhesion of the nanowires. The concentration can be fine-tuned according to the specific morphology and performance requirements of the target nanowires. For example, a lower concentration may result in slow growth but with a regular morphology, while a higher concentration may accelerate growth but is more prone to aggregation.

[0049] Hydrothermal reaction temperature is one of the key factors controlling the growth kinetics and crystallinity of nanowire structures. Within this temperature range, reactant molecules have sufficient energy for chemical reactions and crystal growth, while avoiding side reactions or excessively demanding equipment requirements that may result from excessively high temperatures. The selection of the reaction temperature also needs to consider the pressure resistance of the reaction vessel and the thermal stability of the target product.

[0050] The hydrothermal reaction time determines the extent and integrity of the nanowire structure growth. A sufficiently long reaction time ensures that the nanowires grow fully, reaching the desired length, density, and crystallinity, thus forming a stable and functionalized structure. The reaction time can be adjusted according to the desired nanowire length and density. For example, a shorter time may result in shorter or sparser nanowires, while a longer time may lead to overgrowth or aggregation of the nanowires.

[0051] After the growth step, the encapsulation step is carried out, which involves welding and encapsulating the two stainless steel cover plates, one above the other, using methods such as vacuum diffusion welding / laser welding. The inside is then evacuated, and a liquid working medium (such as pure water) is injected. Finally, the injection port is sealed to obtain the heat spreader.

[0052] The following example illustrates the manufacturing process of a vapor chamber.

[0053] First, prepare two stainless steel cover plates of the corresponding size and shape, and a SUS316L stainless steel wire mesh of the corresponding size. Use a resistance roller welder with a power of 280 W to weld the stainless steel wire mesh to the stainless steel cover plates to form a stainless steel liquid suction core.

[0054] A nanosecond fiber laser was then selected with a wavelength of 1064 nm, an average power of 25 W, a frequency of 35 kHz, a pulse width of 100 ns, and a scanning speed of 500 mm / s. A grid with a depth of 100 μm (i.e., forming a recessed array) was etched on the surface of the stainless steel wick using a pulsed laser. The laser scanning overlap rate was controlled to be 75% to ensure that a continuous non-equilibrium remelting layer was generated on the inner wall of the recessed array.

[0055] The stainless steel cover plate with the welded stainless steel liquid-absorbing core is then placed in a compound acid solution (8% sulfuric acid H2SO4 + 2% hydrochloric acid HCl by mass) and immersed for 5 minutes at a reaction temperature of 25°C. This causes differential pitting corrosion on the surface of the remelted layer on the inner wall of the concave array, forming nano-anchors. The stainless steel cover plate is then removed and the surface liquid is drained.

[0056] Then, a mixed solution of 0.05 mol / L copper acetate and 0.05 mol / L hexamethylenetetramine (HMTA) was prepared. A stainless steel cover plate with a welded stainless steel wick was placed into the reactor, and the mixed solution was poured into the reactor. The hydrothermal reaction was carried out at a reaction temperature of 90°C for 4 hours. Afterward, the stainless steel cover plate was removed and the surface liquid was drained.

[0057] Finally, the upper and lower stainless steel cover plates are laser welded and sealed, vacuumed and injected with liquid working medium (pure water), and the injection port is sealed to obtain a heat spreader.

[0058] The above examples are merely illustrative of the technical content of this application to facilitate reader understanding, but do not imply that the implementation methods of this application are limited to these. Any technical extensions or re-creations made based on this application are protected by this application. The scope of protection of this application is defined by the claims.

Claims

1. A stainless steel heat spreader, characterized in that, It includes a stainless steel cover plate, and at least one stainless steel cover plate has a liquid-absorbing core on its inner surface. The surface of the liquid-absorbing core is etched with a micron structure of a predetermined geometric shape. The surface of the micron structure is activated by an acidic solution to form nano-anchor points. The liquid-absorbing core precipitates metal compound nanowire structures in situ at the surface nano-anchor points through a hydrothermal reaction.

2. The stainless steel heat spreader as described in claim 1, characterized in that, The micron structure is a micron-scale recessed array constructed on the surface of the liquid-absorbing core by laser etching. The surface of the recessed array has a remelted layer formed by the laser heat-affected zone. The surface of the remelted layer is distributed with non-equilibrium defects that serve as nano-anchors for in-situ growth of nanowire structures and exposed metal substrate.

3. The stainless steel heat spreader as described in claim 2, characterized in that, The concave array surface is in situ chemically bonded with metal oxide nanowire structures through the nano-anchor points, and the nanowire structures and the concave array surface form a seamless mechanical-chemical interlocking structure at the contact point.

4. The stainless steel heat spreader as described in claim 2, characterized in that, The macroscopic liquid replenishment channel, composed of the concave array of the micron structure, and the microscopic superhydrophilic nucleation surface, composed of the nanowire structure, form a coupled cyclic interface.

5. The stainless steel heat spreader as described in claim 2, characterized in that, The ratio of the depth to the width of the recessed array of the microstructure is 0.5-2.

0.

6. The stainless steel heat spreader as described in any one of claims 1-5, characterized in that, The nanowire structure is a CuO nanowire structure.

7. A method for manufacturing a stainless steel heat spreader, characterized in that, It includes the following steps: The modification step involves laser etching a micron-sized structure with a predetermined geometric shape onto the surface of the liquid-absorbing core of the stainless steel cover plate. In the activation step, the absorbent core is immersed in an acidic solution to carry out an activation reaction, forming nano-anchors on the surface of the absorbent core; In the growth step, the liquid absorbent core is immersed in the precursor solution for hydrothermal reaction, and the nanowire structure of metal oxide is precipitated in situ at the nanoanchor points on the surface of the micron structure.

8. The method for manufacturing a stainless steel heat spreader as described in claim 7, characterized in that, The acidic solution is a compound acid solution composed of 5%-10% sulfuric acid and 1%-3% hydrochloric acid by mass; the compound acid solution uses the strong penetrating power of chloride ions to target and etch the micron-structured surface to construct the nano-anchor points.

9. The method for manufacturing a stainless steel heat spreader as described in claim 7, characterized in that, In the activation step, the activation reaction temperature is 20-40℃ and the processing time is 2-8 minutes.

10. The method for manufacturing a stainless steel heat spreader as described in claim 7, characterized in that, The precursor solution is a mixed solution of copper acetate and hexamethylenetetramine, both with a concentration of 0.02-0.1 mol / L; the hydrothermal reaction temperature is 80-100℃, and the reaction time is 3-8h; the nanowire structure is a CuO nanowire structure.

Images