A partition-optimized 0.1-0.4 mm ultra-thin VC and preparation method thereof

Abstract

The invention discloses a partition-optimized 0.1-0.4mm ultra-thin VC and a preparation method thereof, comprising an upper cover plate and a lower cover plate, wherein the upper cover plate is welded to the lower cover plate; the upper cover plate and the lower cover plate both comprise an evaporation section, an insulation section and a condensation section; the surface of the evaporation section of the upper cover plate is set as a super-hydrophilic cavity-shaped micro-nano structure, the surface of the insulation section is set as a super-hydrophilic equal-width groove micro-nano structure, and the surface of the condensation section is set as a super-hydrophobic conical micro-nano structure; the surface of the evaporation section region of the lower cover plate is set as a super-hydrophilic conical micro-nano structure, the surface of the insulation section region is set as a super-hydrophilic cactus-like wedge-shaped groove micro-nano structure, and the surface of the condensation section region is set as a super-hydrophilic conical micro-nano structure; the application also discloses a preparation method of the ultra-thin VC. The invention can not only optimize the vapor cavity structure and liquid cavity structure and volume distribution inside the heat pipe, but also ensure its good capillary water absorption performance and low water resistance and thermal resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of vapor chambers, and in particular to a partition-optimized 0.1-0.4 mm ultra-thin VC and a preparation method thereof. Background Art

[0002] With the rapid development of microelectronics technology, especially 5G technology, various electronic devices and devices, especially ultra-thin mobile devices represented by 5G smartphones and tablets, are constantly developing in the direction of high performance, integration, miniaturization and thinness. The density of components is increased, the battery life is improved, and the system power consumption is increased. However, the thickness of the body is constantly compressed, and the heat generated per unit volume continues to rise. The heat dissipation problem caused by high heat flux density has become a key limiting factor restricting the availability, reliability and service life of electronic equipment. About 55% of the failure problems of electronic equipment are caused by excessive temperature. Taking 5G smartphones as an example, the power consumption of its chip is about 2.5 times that of 4G mobile phones. The integration and working speed are further improved, and the heat dissipation demand is more intense. The original heat dissipation solution is difficult to meet its normal work and urgently needs to be upgraded.

[0003] Vapor Chamber (VC, Vacuum Chamber heat dissipation technology) and heat pipe (for convenience, the vapor chamber VC described below includes heat pipes, and the vapor chamber VC of this patent also includes heat pipes) as a high-efficiency two-phase heat transfer device based on boiling phase change heat transfer, its thermal conductivity has exceeded any known metal at present, and it is widely used in electronic devices such as smart phones and laptops due to its excellent thermal conductivity, good isothermal properties and reliability. With the increasing thinness of electronic devices, ultra-thin vapor chambers have also become an effective means and preferred solution for heat dissipation in narrow spaces. Ultra-thin vapor chambers are generally composed of a cavity, a sealing head, a liquid wick and a working medium, and its main structure includes an evaporation section, an insulation section, a condensation section and a sealed shell. In the evaporation section, liquid water absorbs the heat generated by the chip and evaporates into steam, which is transported through the vapor phase of the vapor channel of the insulation section to the condensation section, and the steam is restored to liquid water through the heat release of the condensation section. Due to the capillary force of the liquid wick inside the vapor chamber, the condensed water flows back to the evaporation section and circulates back and forth continuously, quickly dissipating the heat of the chip. The heat transfer performance, heat transfer efficiency and heat transfer limit of the vapor chamber mainly depend on the capillary pressure provided by the wick and the penetration and reflow rate of the liquid in the wick. Traditional wicks mainly include wire mesh wicks, powder / fiber sintered wicks, groove wicks and composite wicks, etc. Their preparation methods mainly include chemical deposition and sintering, or etching methods such as reactive ion etching, electrical discharge machining, electrolytic machining, surface coating, etc. In recent years, laser processing methods have also been more active in preparing wicks.

[0004] The development of 5G technology requires that the heat dissipation capacity of the vapor chamber be further improved and the thickness be further reduced. Especially when the thickness of the vapor chamber is less than 0.4mm, the thickness of its wick will be thinner, its capillary performance will be significantly reduced, the interface shear force caused by the internal gas-liquid high-speed convection will increase, the water resistance and gas resistance will be significantly increased, and the heat transfer efficiency will drop rapidly. Therefore, it is urgent to develop a vapor chamber with better performance and its wick structure.

[0005] The main development trend of ultra-thin heat spreaders is to prepare the wick directly on the cover plate to reduce the thickness, while optimizing the wick structure and improving the capillary force. For example, patent CN106500533B uses nanosecond lasers to carve small, crisscrossing grooves on the wall of the heat pipe, and performs fish scale laser welding on the periphery to prepare ultra-thin heat pipes with good welding sealing, small volume, good heat transfer performance, and low reflux resistance. Patent CN106541210A adds hydrophilic treatment to the groove surface to improve the evaporation heat absorption and condensation reflux efficiency of the working fluid. Patent CN110081749A uses nanosecond lasers to scan a continuous capillary structure with a fuzzy morphology in the groove surface of the aluminum substrate, and uses heat treatment to obtain a structure in which super-hydrophobic and super-hydrophilic areas are alternately distributed to improve heat dissipation efficiency. Patent CN105841535A and Patent CN105865243A propose to use a multifunctional laser to process pin-fin and groove structures on a copper plate, and combine them with a super-hydrophobic surface to prepare a composite structure groove to enhance capillary force and promote boiling, condensation and uniform flow of the working fluid. Patent CN106066130A proposes to use a laser to prepare a groove capillary structure on a sloped copper cover plate, and accelerate the reflux rate of the working fluid in a horizontally placed heat pipe and improve the heat transfer performance by constructing a slope and a groove capillary structure. Patent CN107283067A proposes to use nanosecond lasers to process micro-grooves of unequal width on the wall of a heat pipe to improve the capillary pressure and heat transfer performance of the working fluid reflux. Patent CN107509357A proposes to use a laser to process convex grooves on the surface of a copper substrate to increase the working fluid evaporation surface area and provide additional steam channels to promote working fluid evaporation and reduce working fluid reflux resistance. Patent CN206095014U proposes to use nanosecond laser to etch high aspect ratio grooves on metal substrates, and use adjacent slag deposits to form secondary grooves to prepare flat heat pipes with high capillary pressure and fast working fluid reflux. Patent CN207300016U combines the capillary grooves obtained by laser processing with the mesh wick formed by 3D printing to enhance the evaporation and condensation efficiency of the working fluid, and improve the heat transfer performance and stability.

[0006] In summary, the existing ultra-thin heat pipe wire mesh, powder spraying, and high-temperature brazing packaging mechanical manufacturing methods are difficult to further reduce the thickness of the heat pipe. The laser method has advantages in preparing hydrophilic, super-hydrophilic, hydrophobic, and super-hydrophobic structures and structural layout, but the existing patents using the laser method are generally aimed at heat pipes with a thickness of 0.5mm and above, and almost do not involve heat pipes with a thickness of 0.1-0.4mm. However, when the thickness of the heat pipe further drops below 0.4mm, how to optimize the vapor cavity structure and liquid cavity structure and volume distribution inside the heat pipe, and how to ensure its good capillary water absorption performance and low water resistance and thermal resistance are still a big challenge.

[0007] Therefore, how to provide a 0.1-0.4mm ultra-thin VC and preparation method that can not only optimize the vapor cavity structure, liquid cavity structure and volume distribution inside the heat pipe, but also ensure its good capillary water absorption performance and low water resistance and thermal resistance partition optimization is one of the technical problems that need to be urgently solved in this field. Summary of the invention

[0008] In view of this, the present invention provides a partition-optimized 0.1-0.4mm ultra-thin VC and a preparation method. The ultrafast laser patterning micro-nano preparation method is used to optimize the structure and function of the evaporation section, insulation section, and condensation section of the upper and lower cover plates of the heat spreader. The upper and lower cover plates are welded and packaged using a laser welding method to achieve ultra-thinness and optimized heat transfer performance of the 0.1-0.4mm thick heat spreader.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] A partition-optimized 0.1-0.4 mm ultra-thin VC, comprising an upper cover plate and a lower cover plate, wherein the upper cover plate and the lower cover plate are connected by laser welding;

[0011] The upper cover plate includes a first evaporation section, a first insulation section and a first condensation section; the surface of the first evaporation section is set as a super-hydrophilic cavity-shaped micro-nano structure; the surface of the first insulation section is set as a super-hydrophilic equal-width groove micro-nano structure; the surface of the first condensation section is set as a super-hydrophobic cone-shaped micro-nano structure;

[0012] The lower cover plate includes a second evaporation section, a second insulation section and a second condensation section; the surface of the second evaporation section is set as a super-hydrophilic conical micro-nano structure; the surface of the second insulation section is set as a super-hydrophilic cactus-like wedge-shaped groove micro-nano structure; the surface of the second condensation section is set as a super-hydrophilic conical micro-nano structure.

[0013] The beneficial effects of the above technical solution are: 1) by setting the surface of the second evaporation section area of ​​the lower cover plate to the super-hydrophilic conical micro-nano structure, the evaporation and capillary absorption functions are optimized, and the high-temperature bubble nucleation evaporation heat dissipation mechanism of the super-hydrophilic surface is utilized to significantly improve the heat dissipation efficiency; the strong capillary water absorption capacity of the super-hydrophilic surface is utilized to reduce the liquid flow resistance, improve the water supply efficiency, and significantly improve the water absorption efficiency; the surface of the first evaporation section area of ​​the upper cover plate is set to the super-hydrophilic cavity-shaped micro-nano structure, which optimizes the steam reception and transportation effect and reduces the steam resistance; 2) by setting the surface of the second insulation section area of ​​the lower cover plate to the super-hydrophilic cactus-like wedge-shaped groove micro-nano structure , using the Laplace pressure difference at both ends of the wedge structure to provide a powerful self-driving function, in addition to the super-hydrophilic capillary suction force, an additional self-driving function is added to improve the reflux transport capacity of condensed water and minimize water resistance; the surface area of ​​the first insulation section of the upper cover plate is set to a super-hydrophilic equal-width groove micro-nano structure to quickly transport steam and reduce vapor resistance; 3) by setting the area surface of the first condensation section of the upper cover plate to a super-hydrophobic conical micro-nano structure, the condensation function is optimized, and the droplet condensation heat dissipation mechanism of the super-hydrophobic surface is used to significantly improve the condensation efficiency; the area surface of the second condensation section of the lower cover plate is set to a super-hydrophilic conical micro-nano structure to optimize the condensation water collection and transportation function and reduce water resistance.

[0014] Furthermore, the thickness of the vapor chamber (VC) is 0.1 mm-0.4 mm, and the thickness of the lower cover plate is 50%-80% of the thickness of the vapor chamber (VC).

[0015] Furthermore, the super-hydrophilic conical micro-nano structure is a square periodically distributed micro-cone array, and a high surface energy coating is provided on its surface; the super-hydrophobic conical micro-nano structure is a square periodically distributed micro-cone array, and a low surface energy coating is provided on its surface; and the spacing between each micro-cone is 10-100μm, the diameter is 1-80μm, and the slope is 10°-35°.

[0016] Furthermore, the super-hydrophilic cavity-shaped micro-nano structure is a rectangular cavity, and a high surface coating is provided on its surface; a certain number of support columns are arranged in the middle of the rectangular cavity.

[0017] Furthermore, the super-hydrophilic cactus-like wedge-shaped groove micro-nanostructure is a wedge-shaped groove array distributed in parallel along the length direction of the lower cover plate, and a high surface energy coating is provided on its surface; the angle of the wedge-shaped groove is 5°-35°, and its cross-section is crescent-shaped; the short side of the wedge-shaped groove is located in the evaporation section, and the long side is located in the condensation section; the width of the wedge-shaped groove is 30-100nm.

[0018] Furthermore, the super-hydrophilic equal-width groove micro-nano structure is a rectangular groove array distributed in parallel along the length direction of the upper cover plate, and a high surface energy coating is provided on its surface; the cross-section of the rectangular groove is crescent-shaped, and its width is 50-100nm.

[0019] Furthermore, the height of the micron cone, the depth of the rectangular cavity, and the depth of the wedge-shaped and equal-width grooves are all 10%-70% of the thickness of the plate, and the surface of the micron cone, the inner surface of the rectangular cavity, and the inner surface of the wedge-shaped and equal-width grooves are all distributed with nano-ripples or particles, and the size of the nano-scale ripples or particles is 100-900nm.

[0020] Furthermore, the high surface energy coating is an oxide coating such as SiO2 or TiO2.

[0021] Furthermore, the low surface energy coating is a fluorinated coating.

[0022] Furthermore, the materials used for the upper cover plate and the lower cover plate are copper, copper alloy, aluminum alloy, or stainless steel.

[0023] Furthermore, the upper cover plate and the lower cover plate are packaged by laser welding to form a heat spreader.

[0024] The present invention also provides a method for preparing a partition-optimized 0.1-0.4 mm ultra-thin VC, comprising the following steps:

[0025] 1) performing pre-processing such as cutting and cleaning on the upper cover plate and the lower cover plate;

[0026] 2) According to the shape requirements of each partition structure of the upper cover plate and the lower cover plate, the scanning area of ​​the ultrafast laser is compiled into corresponding shapes, and the preparation work is performed within the above-mentioned shape areas;

[0027] 3) focusing an ultrafast laser onto the surface of each partitioned structure region, optimizing the process parameters of the ultrafast laser, including average power, single pulse energy, repetition frequency, focal spot size, scanning speed, action time, number of scans, and scanning path, so that the beam energy flux density in the laser action region is higher than the ablation threshold of the heat spreader cover material, vaporizing and evaporating the material based on the ablation mechanism, and forming a corresponding micro-nano structure corresponding to each partitioned structure, and forming a nano-corrugated / nano-granular shape on the surface of each micro-nano structure based on the ablation and induction mechanism of the ultrafast laser;

[0028] 4) performing high surface energy treatment on the surface of each partition structure prepared in step 3) to form a super hydrophilic / super hydrophobic micro-nano structure;

[0029] 5) The prepared super-hydrophilic / super-hydrophobic micro-nano structure is sequentially ultrasonically cleaned, purged, and dried, and then vacuum packaged to obtain the upper cover plate and the lower cover plate with partitioned structure and optimized function;

[0030] 6) The upper cover plate and the lower cover plate with optimized partition structure and function obtained in the above step 5) are packaged by laser welding, so as to obtain a 0.1-0.4 mm ultra-thin VC with optimized partition structure and function.

[0031] Compared with the prior art, the present invention has achieved the following technical effects:

[0032] 1) The present invention is specifically for 0.1-0.4mm ultra-thin heat spreader (VC) and heat pipe. It is well known that when the thickness of the heat spreader and heat pipe is reduced to less than 0.4mm, its capillary performance will be significantly reduced, the water resistance and gas resistance will be significantly improved, and the heat transfer efficiency will decrease rapidly. The present invention also optimizes the evaporation section, insulation section and condensation section of the upper cover plate and the lower cover plate in a partitioned structure and function, that is, the second evaporation section area of ​​the lower cover plate uses the high-temperature bubble nucleation evaporation heat dissipation mechanism of the super-hydrophilic surface to significantly improve the evaporation capacity. Studies have shown that when evaporation is performed at a high temperature exceeding 100 degrees, the super-hydrophilic surface will continuously generate a large number of bubbles and quickly detach from the surface, thereby improving the dissipation of heat, while other surfaces will form a water film covering the high-temperature surface, hindering the dissipation of heat flow. At the same temperature, the heat dissipation heat flux of the super-hydrophilic surface is increased by dozens of times compared with the hydrophobic surface or the super-hydrophobic surface. The super-hydrophilic structure of the lower cover plate simultaneously forms a strong liquid absorption capacity, so that the liquid absorption capacity of the micro-nanostructured liquid absorption core is optimized. The first evaporation section of the upper cover adopts a super-hydrophilic cavity-shaped micro-nano structure, which can greatly reduce the vapor resistance of the steam generated by evaporation and quickly export the steam. The second insulation section of the lower cover adopts a super-hydrophilic cactus-like wedge-shaped groove micro-nano structure, which is a wedge-shaped micro-nano channel structure. Due to the diameter difference at both ends of the wedge, surface tension and Laplace pressure difference will be formed, automatically driving water from the larger diameter part to the smaller diameter part. The superimposed driving force on the basis of the strong capillary force of super-hydrophilicity can greatly improve the transmission capacity and efficiency of the liquid from the condensation section to the evaporation section; the first insulation section of the upper cover adopts a super-hydrophilic equal-width groove micro-nano structure, which further improves the bubble nucleation and heat dissipation capacity, while reducing steam resistance and improving steam transport efficiency. The surface of the first condensation section area of ​​the upper cover plate adopts a super-hydrophobic conical micro-nano structure, and the droplet condensation heat dissipation mechanism of the super-hydrophobic surface is used to significantly improve the condensation efficiency. Studies have shown that when the super-hydrophobic surface condenses, the water droplets will be in droplets, and the phenomenon of jumping drops will occur at the same time. The water droplets will quickly detach from the surface, while a water film will appear on the conventional surface, hindering the condensation. The condensation efficiency of the super-hydrophobic surface is more than 10 times higher than the film condensation efficiency of normal metals. The super-hydrophilic conical micro-nano structure on the surface of the second condensation section area of ​​the lower cover plate will optimize the condensation water collection and output functions and reduce water resistance. Due to the partition structure and function optimization effect of the above-mentioned upper and lower cover plates, especially the micro-nano structure on the surface of each section, the functions of the evaporation section, the insulation section and the condensation section are all optimized, and the heat dissipation capacity of the heat spreader is fully exploited. Even if the thickness of the heat spreader is reduced to the extreme thickness of 0.1-0.4mm, it can still maintain good heat dissipation capacity, and even exceed the performance of conventional heat spreaders with thicker thickness.

[0033] 2) The evaporation section, insulation section and condensation section of the upper cover plate and the lower cover plate of the present invention are optimized in partition function and are prepared by high-power picosecond laser or femtosecond laser. The laser beam can be programmed by a computer to control the scanning galvanometer to prepare different structures in different areas of the upper and lower cover plates in one step. Patterns of almost any shape can be prepared, and the patterns of all channels can be designed and realized, which is a flexible and efficient preparation method; by controlling process parameters such as laser beam energy flux density and scanning speed, the depth of various micro-nano structures can be accurately controlled, and the depth of water flow channels and steam channels can be accurately controlled, so that the vapor cavity structure and liquid cavity structure as well as the volume distribution inside the heat spreader can be regulated and optimized to ensure its good capillary water absorption performance and low water resistance and thermal resistance; the laser preparation process is stable, highly repeatable, and has a high yield, and is a practical and reliable preparation method; by increasing the laser power and adopting a variety of measures to increase the processing speed, the laser one-step preparation of the heat spreader partition function optimized micro-nano structure can be an efficient and cost-controlled preparation method. The laser method for preparing the liquid-absorbing core has fewer process steps, shorter process, higher efficiency, better structural consistency, higher stability, and better overall performance, and can achieve the lowest heat pipe thickness and the best heat dissipation effect.

[0034] 3) The upper cover plate and the lower cover plate of the heat spreader (VC) of the present invention are packaged by laser welding, and the laser welding has good welding quality, the weld is well formed, smooth and neat, without leaking and defects; the laser welding speed is fast, and the welding efficiency is greatly improved compared with the current common high-temperature brazing process; the laser welding process is simple, and the requirements for the front and back processes are low. There is no high-temperature heating requirement of 700-800 degrees for brazing, which can greatly simplify the manufacturing process of the heat spreader, reduce manufacturing costs, improve manufacturing efficiency, and enhance the stability of welding quality; laser welding overcomes the influence of high-temperature heating on the capillary structure and performance of the liquid wick, and can realize a stable and reliable heat spreader; laser welding does not increase the thickness of the brazing brazing material, and the thickness of the heat spreader is completely determined by the thickness of the upper cover plate and the lower cover plate, which can minimize the thickness of the heat spreader. Therefore, laser welding has obvious technical progress compared with traditional high-temperature brazing. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the structure of a 0.1-0.4 mm ultra-thin VC with optimized partitioning according to the present invention;

[0036] Figure 2 This is a schematic structural diagram of a partition-optimized 0.1-0.4 mm ultra-thin VC upper cover plate of the present invention;

[0037] Figure 3 This is a schematic structural diagram of a partition-optimized 0.1-0.4 mm ultra-thin VC lower cover plate of the present invention;

[0038] In the figure: 1, upper cover plate; 11, first evaporation section; 12, first insulation section; 13, first condensation section; 2, lower cover plate; 21, second evaporation section; 22, second insulation section; 23, second condensation section. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example 1

[0041] A partition-optimized 0.1-0.4 mm ultra-thin VC comprises an upper cover plate 1 and a lower cover plate 2, wherein the upper cover plate 1 and the lower cover plate 2 are connected by laser welding; the upper cover plate 1 comprises a first evaporation section 11, a first insulation section 12 and a first condensation section 13; the surface of the first evaporation section 11 is arranged as a super-hydrophilic cavity-shaped micro-nano structure; the surface of the first insulation section 12 is arranged as a super-hydrophilic equal-width groove micro-nano structure; the surface of the first condensation section 13 is arranged as a super-hydrophobic conical micro-nano structure; the lower cover plate 2 comprises a second evaporation section 21, a second insulation section 22 and a second condensation section 23; the surface of the second evaporation section 21 is arranged as a super-hydrophilic conical micro-nano structure; the surface of the second insulation section 22 is arranged as a super-hydrophilic cactus-like wedge-shaped groove micro-nano structure; the surface of the second condensation section 23 is arranged as a super-hydrophilic conical micro-nano structure; the thickness of the ultra-thin VC is 0.1 mm-0.4 mm, and the thickness of the lower cover plate 2 is 50%-80% of the thickness of the ultra-thin VC.

[0042] The super-hydrophilic conical micro-nano structure is a square periodically distributed micro-cone array, and its surface is provided with a high surface energy coating; the super-hydrophobic conical micro-nano structure is a square periodically distributed micro-cone array, and its surface is provided with a low surface energy coating; and the spacing between each micro-cone is 10-100μm, the diameter is 1-80μm, and the slope is 10°-35°.

[0043] The super-hydrophilic cavity-shaped micro-nanostructure is a rectangular cavity with a high surface coating on its surface; a certain number of support columns are arranged in the middle of the rectangular cavity.

[0044] The super-hydrophilic cactus-like wedge-shaped groove micro-nanostructure is a wedge-shaped groove array parallelly distributed along the length direction of the lower cover plate 2, and a high surface energy coating is provided on its surface; the angle of the wedge-shaped groove is 5°-35°, and its cross-section is crescent-shaped; the short side of the wedge-shaped groove is located in the evaporation section, and the long side is located in the condensation section; the width of the wedge-shaped groove is 30-100nm.

[0045] The super-hydrophilic equal-width groove micro-nano structure is a rectangular groove array distributed in parallel along the length direction of the upper cover plate 1, and a high surface energy coating is provided on its surface; the cross section of the rectangular groove is crescent-shaped, and its width is 50-100nm.

[0046] The height of the micron cone, the depth of the rectangular cavity, and the depth of the wedge-shaped and equal-width grooves are all 10%-70% of the thickness of the plate. The surface of the micron cone, the inner surface of the rectangular cavity, and the inner surface of the wedge-shaped and equal-width grooves are all distributed with nano-ripples or particles, and the size of the nano-scale ripples or particles is 100-900nm.

[0047] In this embodiment, the high surface energy coating is an oxide coating such as SiO2 or TiO2.

[0048] In this embodiment, the low surface energy coating is a fluorinated coating.

[0049] In some other embodiments, the materials used for the upper cover plate 1 and the lower cover plate 2 are copper, copper alloy, aluminum alloy, or stainless steel.

[0050] In some other embodiments, the upper cover plate 1 and the lower cover plate 2 are packaged by laser welding to form a heat spreader.

[0051] In some other embodiments, the present invention further provides a method for preparing a partition-optimized 0.1-0.4 mm ultra-thin VC, comprising the following steps:

[0052] 1) performing pre-processing such as cutting and cleaning on the upper cover plate 1 and the lower cover plate 2;

[0053] 2) According to the shape requirements of each partition structure of the upper cover plate 1 and the lower cover plate 2, the scanning area of ​​the ultrafast laser is compiled into corresponding shapes, and the preparation work is performed within the above-mentioned shape areas;

[0054] 3) focusing an ultrafast laser onto the surface of each partitioned structure region, optimizing the process parameters of the ultrafast laser, including average power, single pulse energy, repetition frequency, focal spot size, scanning speed, action time, number of scans, and scanning path, so that the beam energy flux density in the laser action region is higher than the ablation threshold of the heat spreader cover material, vaporizing and evaporating the material based on the ablation mechanism, and forming a corresponding micro-nano structure corresponding to each partitioned structure, and forming a nano-corrugated / nano-granular shape on the surface of each micro-nano structure based on the ablation and induction mechanism of the ultrafast laser;

[0055] 4) performing high surface energy treatment on the surface of each partition structure prepared in step 3) to form a super hydrophilic / super hydrophobic micro-nano structure;

[0056] 5) The prepared super-hydrophilic / super-hydrophobic micro-nano structure is sequentially ultrasonically cleaned, purged, and dried, and then vacuum packaged to obtain the upper cover plate 1 and the lower cover plate 2 with partitioned structure and optimized function;

[0057] 6) The upper cover plate 1 and the lower cover plate 2 with optimized partition structure and function obtained in the above step 5) are packaged by laser welding, so as to obtain a 0.1-0.4 mm ultra-thin VC with optimized partition structure and function.

[0058] Compared with the prior art, the present invention has achieved the following technical effects:

[0059] 1) The present invention is specifically for 0.1-0.4mm ultra-thin VC and heat pipes. It is well known that when the thickness of the heat spreader and heat pipe is reduced to below 0.4mm, its capillary performance will be significantly reduced, the water resistance and gas resistance will be significantly improved, and the heat transfer efficiency will decrease rapidly. The present invention also optimizes the evaporation section, insulation section and condensation section of the upper cover plate and the lower cover plate in a partitioned structure and function, that is, the second evaporation section area of ​​the lower cover plate uses the high-temperature bubble nucleation evaporation heat dissipation mechanism of the super-hydrophilic surface to significantly improve the evaporation capacity. Studies have shown that when evaporation is carried out at a high temperature exceeding 100 degrees, the super-hydrophilic surface will continuously generate a large number of bubbles and quickly detach from the surface, thereby improving the dissipation of heat, while other surfaces will form a water film covering the high-temperature surface, hindering the dissipation of heat flow. At the same temperature, the heat dissipation heat flux of the super-hydrophilic surface is increased by dozens of times compared with the hydrophobic surface or the super-hydrophobic surface. The super-hydrophilic structure of the lower cover plate simultaneously forms a strong liquid absorption capacity, so that the liquid absorption capacity of the micro-nanostructured liquid absorption core is optimized. The first evaporation section of the upper cover adopts a super-hydrophilic cavity-shaped micro-nano structure, which can greatly reduce the vapor resistance of the steam generated by evaporation and quickly export the steam. The second insulation section of the lower cover adopts a super-hydrophilic cactus-like wedge-shaped groove micro-nano structure, which is a wedge-shaped micro-nano channel structure. Due to the diameter difference at both ends of the wedge, surface tension and Laplace pressure difference will be formed, automatically driving water from the larger diameter part to the smaller diameter part. The superimposed driving force on the basis of the strong capillary force of super-hydrophilicity can greatly improve the transmission capacity and efficiency of the liquid from the condensation section to the evaporation section; the first insulation section of the upper cover adopts a super-hydrophilic equal-width groove micro-nano structure, which further improves the bubble nucleation and heat dissipation capacity, while reducing steam resistance and improving steam transport efficiency. The surface of the first condensation section area of ​​the upper cover plate adopts a super-hydrophobic conical micro-nano structure, and the droplet condensation heat dissipation mechanism of the super-hydrophobic surface is used to significantly improve the condensation efficiency. Studies have shown that when the super-hydrophobic surface condenses, the water droplets will be in droplets, and the phenomenon of jumping drops will occur at the same time. The water droplets will quickly detach from the surface, while a water film will appear on the conventional surface, hindering the condensation. The condensation efficiency of the super-hydrophobic surface is more than 10 times higher than the film condensation efficiency of normal metals. The super-hydrophilic conical micro-nano structure on the surface of the second condensation section area of ​​the lower cover plate will optimize the condensation water collection and output functions and reduce water resistance. Due to the partition structure and function optimization effect of the above-mentioned upper and lower cover plates, especially the micro-nano structure on the surface of each section, the functions of the evaporation section, the insulation section and the condensation section are all optimized, and the heat dissipation capacity of the heat spreader is fully exploited. Even if the thickness of the heat spreader is reduced to the extreme thickness of 0.1-0.4mm, it can still maintain good heat dissipation capacity, and even exceed the performance of conventional heat spreaders with thicker thickness.

[0060] 2) The evaporation section, insulation section and condensation section of the upper cover plate and the lower cover plate of the present invention are optimized in partition function and are prepared by high-power picosecond laser or femtosecond laser. The laser beam can be programmed by a computer to control the scanning galvanometer to prepare different structures in different areas of the upper and lower cover plates in one step. Patterns of almost any shape can be prepared, and the patterns of all channels can be designed and realized, which is a flexible and efficient preparation method; by controlling process parameters such as laser beam energy flux density and scanning speed, the depth of various micro-nano structures can be accurately controlled, and the depth of water flow channels and steam channels can be accurately controlled, so that the vapor cavity structure and liquid cavity structure as well as the volume distribution inside the heat spreader can be regulated and optimized to ensure its good capillary water absorption performance and low water resistance and thermal resistance; the laser preparation process is stable, highly repeatable, and has a high yield, and is a practical and reliable preparation method; by increasing the laser power and adopting a variety of measures to increase the processing speed, the laser one-step preparation of the heat spreader partition function optimized micro-nano structure can be an efficient and cost-controlled preparation method. The laser method for preparing the liquid-absorbing core has fewer process steps, shorter process, higher efficiency, better structural consistency, higher stability, and better overall performance, and can achieve the lowest heat pipe thickness and the best heat dissipation effect.

[0061] 3) The upper cover plate and the lower cover plate of the ultra-thin VC of the present invention are packaged by laser welding. The laser welding has good welding quality, the weld is well formed, smooth and neat, without leaking and defects; the laser welding speed is fast, and the welding efficiency is greatly improved compared with the current common high-temperature brazing process; the laser welding process is simple, and the requirements for the front and back processes are low. There is no 700-800 degree high-temperature heating requirement for brazing, which can greatly simplify the manufacturing process of the heat spreader, reduce manufacturing costs, improve manufacturing efficiency, and enhance the stability of welding quality; laser welding overcomes the influence of high-temperature heating on the capillary structure and performance of the liquid wick, and can realize a stable and reliable heat spreader; laser welding does not increase the thickness of the brazing brazing material, and the thickness of the heat spreader is completely determined by the thickness of the upper cover plate and the lower cover plate, which can minimize the thickness of the heat spreader. Therefore, laser welding has obvious technical progress compared with traditional high-temperature brazing.

[0062] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A 0.1-0.4 mm ultra-thin heat spreader with optimized partitions, comprising an upper cover plate (1) and a lower cover plate (2), characterized in that: The upper cover plate (1) and the lower cover plate (2) are connected by laser welding; The upper cover plate (1) comprises a first evaporation section (11), a first insulation section (12) and a first condensation section (13); the surface of the first evaporation section (11) is configured as a super-hydrophilic cavity-shaped micro-nano structure; the surface of the first insulation section (12) is configured as a super-hydrophilic equal-width groove micro-nano structure; and the surface of the first condensation section (13) is configured as a super-hydrophobic conical micro-nano structure; The lower cover plate (2) comprises a second evaporation section (21), a second insulation section (22) and a second condensation section (23); the surface of the second evaporation section (21) is configured as a super-hydrophilic conical micro-nano structure; the surface of the second insulation section (22) is configured as a super-hydrophilic cactus-like wedge-shaped groove micro-nano structure, which is a wedge-shaped micro-nano channel structure. Due to the diameter difference between the two ends of the wedge, surface tension and Laplace pressure difference are formed, which automatically drives water from the part with a larger diameter to the part with a smaller diameter, and a driving force is superimposed on the strong capillary force of the super-hydrophilicity; the surface of the second condensation section (23) is configured as a super-hydrophilic conical micro-nano structure; The super-hydrophilic conical micro-nano structure is a square periodically distributed micro-cone array, and a high surface energy coating is provided on its surface; the super-hydrophobic conical micro-nano structure is a square periodically distributed micro-cone array, and a low surface energy coating is provided on its surface; and each of the micro-cones has a spacing of 10-100 μm, a diameter of 1-80 μm, and a slope of 10°-35°; The super-hydrophilic cavity-shaped micro-nano structure is a rectangular cavity, a high surface energy coating is provided on the surface of the rectangular cavity, and a certain number of support columns are arranged in the middle of the rectangular cavity.

2. The partition-optimized 0.1-0.4 mm ultra-thin vapor chamber according to claim 1, characterized in that: The thickness of the ultra-thin heat spreader is 0.1 mm-0.4 mm, and the thickness of the lower cover plate (2) is 50%-80% of the thickness of the ultra-thin heat spreader.

3. The partition-optimized 0.1-0.4 mm ultra-thin vapor chamber according to claim 1, characterized in that: The super-hydrophilic cactus-like wedge-shaped groove micro-nanostructure is a wedge-shaped groove array distributed in parallel along the length direction of the lower cover plate (2), and a high surface energy coating is provided on its surface; the angle of the wedge-shaped groove is 5°-35°, and its cross-section is crescent-shaped; the short side of the wedge-shaped groove is located in the evaporation section, and the long side is located in the condensation section, and the width of the wedge-shaped groove is 30-100 nm.

4. The partition-optimized 0.1-0.4 mm ultra-thin vapor chamber according to claim 1, characterized in that: The super-hydrophilic equal-width groove micro-nano structure is a rectangular groove array distributed in parallel along the length direction of the upper cover plate (1), and a high surface energy coating is provided on its surface; the cross section of the rectangular groove is crescent-shaped, and its width is 50-100 nm.

5. A 0.1-0.4 mm ultra-thin vapor chamber with optimized partitions according to any one of claims 1, 3 and 4, characterized in that: The height of the micron cone, the depth of the rectangular cavity, and the depth of the wedge-shaped and equal-width grooves are all 10%-70% of the thickness of the plate. The surface of the micron cone, the inner surface of the rectangular cavity, and the inner surface of the wedge-shaped and equal-width grooves are all distributed with nanoscale corrugations or particles, and the size of the nanoscale corrugations or particles is 100-900nm.

6. A zone-optimized 0.1-0.4 mm ultra-thin vapor chamber according to any one of claims 1, 3 and 4, characterized in that: The high surface energy coating is a SiO2 or TiO2 oxide coating; The low surface energy coating is a fluorinated coating.

7. A method for preparing a partition-optimized 0.1-0.4 mm ultra-thin vapor chamber as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: 1) performing a preliminary pretreatment of cutting and cleaning the upper cover plate (1) and the lower cover plate (2); 2) According to the shape requirements of each partition structure of the upper cover plate (1) and the lower cover plate (2), the scanning area of ​​the ultrafast laser is compiled into corresponding shapes, and the preparation work is performed within the above-mentioned shape area; 3) Focusing the ultrafast laser onto the surface of each partitioned structure area, optimizing the process parameters of the ultrafast laser, including average power, single pulse energy, repetition frequency, focal spot size, scanning speed, action time, number of scans and scanning path, so that the beam energy flux density in the laser action area is higher than the ablation threshold of the heat spreader cover material, vaporizing and evaporating the material based on the ablation mechanism, and forming a corresponding micro-nano structure for each partitioned structure, and forming a nano-corrugated / nano-granular shape on the surface of each micro-nano structure based on the ablation and induction mechanism of the ultrafast laser; 4) performing high / low surface energy treatment on the surface of each partition structure prepared in step 3) to form a super-hydrophilic / super-hydrophobic micro-nano structure; 5) The prepared super-hydrophilic / super-hydrophobic micro-nano structure is sequentially subjected to ultrasonic cleaning, blowing, and drying, and then vacuum packaging, thereby obtaining the upper cover plate (1) and the lower cover plate (2) having a partitioned structure and optimized functions; 6) The upper cover plate (1) and the lower cover plate (2) with optimized partition structure and function obtained in the above step 5) are packaged by laser welding, thereby obtaining a 0.1-0.4 mm ultra-thin heat spreader with optimized partition structure and function.

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