Laser non-traditional processing ultrathin vapor chamber and manufacturing method thereof

Abstract

The invention discloses a laser non-traditional machining ultrathin vapor chamber and a manufacturing method thereof. The laser non-traditional machining ultrathin vapor chamber comprises a first shell plate, a second shell plate and a liquid absorption core layer. The first shell plate and the second shell plate are welded through laser to form a closed accommodating cavity; the liquid absorption core layer is arranged in the containing cavity, a micro-nano structure is formed on the surface of the liquid absorption core layer through laser ablation, the capillary performance of a liquid absorption core is improved, and then the heat transfer performance of the vapor chamber is improved; meanwhile, the inner surfaces of the two shell plates can be subjected to laser ablation treatment to form a micro-channel structure. The manufacturing method comprises the steps of laser ablation of the wick layer and laser welding of the two shell plates. Based on the laser ablation technology, design and treatment of the microstructure morphology of the surface of the wick can be met; the influence on the mechanical property of a shell material in the manufacturing process can be reduced to the maximum extent through laser welding, the manufacturing yield of the vapor chamber is improved, and compared with traditional brazing, non-contact welding can avoid pollution to an internal wick.

Description

Technical Field

[0001] The invention relates to the technical field of heat dissipation of microelectronic devices, and in particular to a laser special processing ultra-thin heat spreader and a manufacturing method thereof. Background Art

[0002] With the rapid development of technologies such as the fifth generation of mobile communication technology (5G technology) and artificial intelligence (AI), electronic devices such as smartphones, tablets, laptops, servers, and graphics processing units (GPUs) are constantly developing towards high performance, high integration, and miniaturization. These devices generate a lot of heat during operation. If the heat cannot be dissipated in time, the device temperature will be too high, which will affect the performance and stability of the device and may even cause damage to the device. Therefore, how to achieve rapid heat dissipation in the high-temperature area of ​​the chip is of great significance to ensure the stable operation of high-performance computing and smart devices.

[0003] As a highly efficient heat conduction element, the ultra-thin vapor chamber has the advantages of excellent thermal conductivity, large heat transfer area, good temperature uniformity and high reliability. It uses the gas-liquid phase change of the internal working fluid to achieve efficient heat transfer and dissipation, and can effectively solve the heat dissipation problem of high heat flux density in a small space. Compared with traditional heat dissipation methods, the ultra-thin vapor chamber not only has higher thermal conductivity, but also has a thinner thickness, which is more suitable for the development trend of modern electronic equipment to be thinner and lighter.

[0004] Traditional ultra-thin vapor chamber wick surface treatment processes (such as heat treatment, chemical deposition and electrochemical deposition) have very limited effects on improving the capillary and hydrophilic properties of the wick, and are unable to accurately control the morphology and size of the formed microstructure, resulting in inconsistent surface performance of the wick, affecting the heat transfer performance of the ultra-thin vapor chamber. At the same time, these methods are also easily restricted by material type and shape and are not universal.

[0005] In addition, the peripheral seals of traditional ultra-thin heat spreader shell plates are mostly based on brazing processing, which will produce a large thermal impact during the welding process, and are prone to material deformation, performance degradation and other problems. It is not only difficult to form high-quality welds, but there is also the problem of brazing agent contaminating the liquid wick, resulting in low manufacturing yield and efficiency, and high cost. The ultra-thin heat spreader processed based on this process usually has heat transfer performance and stability that are difficult to meet the heat dissipation requirements of higher-performance equipment in the future. In view of this, in order to overcome the above technical problems, the present invention designs a laser special processing ultra-thin heat spreader and its manufacturing method to solve the above problems. Summary of the invention

[0006] The present invention aims to at least improve one of the technical problems existing in the prior art. To this end, the present invention provides a laser special processing ultra-thin heat sink and a manufacturing method thereof.

[0007] A laser special processing ultra-thin heat sink, comprising: First shell plate; The second shell plate is laser welded with the first shell plate to form a closed cavity; A liquid absorbing core layer, wherein the liquid absorbing core layer is arranged in the cavity, and a micro-nano structure is formed on the surface of the liquid absorbing core layer by laser ablation; In a possible implementation manner of the first aspect, the liquid absorbent core layer includes: A braided mesh absorbent core, the braided mesh absorbent core comprising a plurality of braided and interlaced metal wires; A wire mesh absorbent core, wherein the wire mesh absorbent core comprises a plurality of metal wires arranged at a certain angle, and the woven mesh absorbent core and the wire mesh absorbent core are stacked between the first shell plate and the second shell plate; Wherein, at least one of the woven mesh liquid absorbent core and the wire mesh liquid absorbent core has the micro-nano structure.

[0008] Preferably, the number of woven meshes of the woven mesh wick is at least one, the number of layers of the wire mesh wick is at least one, and the woven mesh wick and the wire mesh wick are vertically distributed in the cavity. Under the premise of ensuring good capillary properties and hydrophilicity of the wick, the ultra-thin heat spreader is both light and thin, which is more conducive to application in the field of microelectronics technology.

[0009] Preferably, the overall thickness of the ultra-thin vapor chamber is in the range of 0.03 mm to 0.4 mm, wherein: The thickness of the liquid-absorbing core layer ranges from 0.01 mm to 0.1 mm; The thickness of the first shell plate ranges from 0.01 mm to 0.15 mm; The thickness of the second shell plate ranges from 0.01 mm to 0.15 mm.

[0010] Controlling the overall thickness of the heat spreader to below 0.4mm is more conducive to broadening the application fields and application scenarios of the ultra-thin heat spreader in this application. Compared with the conventional 2mm ultra-thin heat spreader, this application can maintain stable heat dissipation performance in narrower or harsh working environments.

[0011] Preferably, the second shell plate has an inner curved surface, the inner curved surface protrudes in a direction away from the first shell plate, and is used to form the cavity, and the liquid wick layer is located on the inner curved surface, and is used to provide a working channel for the cooling medium; Preferably, the first shell plate forms a microchannel structure on the inner plane by laser ablation; the second shell plate forms a microchannel structure on the inner curved surface by laser ablation, so as to improve the overall heat transfer performance of the ultra-thin heat spreader.

[0012] Preferably, in the wire mesh wick, a plurality of metal wires are arranged orthogonally.

[0013] Preferably, the material of the first shell plate is any one of metal foil, polymer film or composite film; The material of the second shell plate is any one of metal foil, polymer film or composite film.

[0014] The laser special processing ultra-thin heat spreader according to the present invention can not only improve the capillary performance and hydrophilicity of the liquid wick in the ultra-thin heat spreader, optimize the penetration, diffusion and transmission process of the liquid in the liquid wick, but also complete the packaging of the ultra-thin heat spreader with high quality, making the ultra-thin heat spreader more stable while obtaining high-quality welds.

[0015] A method for preparing a laser special processing ultra-thin heat sink, wherein the method is used to prepare the laser special processing ultra-thin heat sink as described above, and comprises the following contents: Step S1, preparing the main material of the shell plate and the liquid absorbent core layer: taking two shell plates and the main material of the liquid absorbent core layer, cutting out the target outline, and etching a cavity on one of the shell plates, and obtaining the main material of the first shell plate, the second shell plate and the liquid absorbent core layer after pretreatment; Step S2, microstructure processing: laser ablation is performed on the first shell plate and the second shell plate to form a microchannel structure, and ablation is performed on the surface of the main material of the liquid absorbent core layer to form a micro-nano structure to obtain the liquid absorbent core layer; Step S3, sintering the liquid-absorbing core layer: sintering the liquid-absorbing core layer to the inner wall of the shell plate containing the cavity; Step S4, sealing the periphery of the vapor chamber: assembling the first shell plate and the second shell plate to form a butt joint at the contact point, performing a periphery sealing treatment on the butt joint by laser welding, and reserving a hole position for a liquid injection pipe; Step S5, liquid injection, vacuuming, and sealing: insert the liquid injection tube into the liquid injection tube hole and fix it, inject the cooling medium, perform vacuuming, seal, and cut off the liquid injection tube; Step S6, finished product finishing: perform thickness shaping on the vapor chamber, select the vapor chambers with thickness errors within the expected range, and obtain finished products.

[0016] Preferably, when sintering the liquid absorbent core, if there are multiple sheets of liquid absorbent core main body material, the ablated multiple sheets of liquid absorbent core main body material need to be sintered and formed in a mold first and then sintered to the inner wall of the shell plate containing the cavity.

[0017] The manufacturing method according to the present invention includes laser ablation of the liquid absorbent core layer and laser welding of the two shell plates of the heat spreader: the laser ablation technology used in the present application can be applicable to various types of products, the processing accuracy can reach the micron level, and the operation has a high degree of flexibility and controllability, which can meet the design and processing of the microstructure morphology of the surface of the liquid absorbent core layer; the laser welding laser beam can obtain a very small light spot after focusing, which can minimize the impact on the mechanical properties of the outer shell plate material during the manufacturing process and improve the manufacturing yield of the heat spreader, and the laser welding in the present application is contactless welding, which can avoid contaminating the internal liquid absorbent core compared to traditional brazing.

[0018] The surface treatment process of the liquid-absorbing core of the ultra-thin heat spreader and the peripheral sealing process of the two shell plates both use laser technology, forming an integrated molding path for ultra-thin heat spreaders based on laser special processing, realizing the deep integration of laser special processing in the field of ultra-thin heat spreaders.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic diagram of the decomposed structure of an ultra-thin heat sink processed by laser special processing in one embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of laser ablation treatment of the surface of the liquid wick in one embodiment of the present invention; Figure 3 Schematic diagram of the microstructure of the ablated wick in one embodiment of the present invention; Figure 4 It is a schematic diagram of the laser welding processing structure of the periphery of the first shell plate and the second shell plate of the ultra-thin heat sink specially processed by laser in one embodiment of the present invention; Figure 5 This is a schematic diagram of the fish scale structure of the first shell plate and the second shell plate of the ultra-thin heat spreader processed by laser special processing in one embodiment of the present invention after laser welding.

[0022] Reference numerals: The first shell plate 1 , the second shell plate 2 , the liquid absorbent core layer 3 , the woven mesh liquid absorbent core 301 , the wire mesh liquid absorbent core 302 , the liquid injection tube 4 , the laser ablation laser head 5 , and the laser welding laser head 6 . DETAILED DESCRIPTION

[0023] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0024] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0026] Example 1 See also Figures 1 to 3 , is a schematic diagram of the structure of the ultra-thin heat spreader processed by laser special processing proposed in this application, and the proposed ultra-thin heat spreader processed by laser special processing includes: First shell plate 1; The second shell plate 2 is laser welded with the first shell plate 1 to form a closed cavity; The liquid absorbent core layer 3 is arranged in the cavity, and the surface of the liquid absorbent core layer 3 is formed into a micro-nano structure by laser ablation.

[0027] It should be noted that the liquid absorbent core layer 3 can be directly sintered on the surface of the first shell plate 1 or the second shell plate 2, and the connection method of the liquid absorbent core layer 3 is not limited in the present application.

[0028] In this embodiment, the absorbent core layer 3 includes a woven mesh absorbent core 301 and a wire mesh absorbent core 302, wherein the woven mesh absorbent core 301 and the wire mesh absorbent core 302 are sintered and fixed and laser ablated to form a rough micro-nano structure, such as Figure 3 As shown, Figure 3 a in the figure is a schematic diagram of the microstructure of the ablated braided mesh wick, wherein the braided mesh wick 301 comprises a plurality of braided and interlaced metal wires. Figure 3 b is a schematic diagram of the microstructure of the ablated wire mesh wick, wherein the wire mesh wick 302 includes a plurality of metal wires arranged at a certain angle, and the woven mesh wick 301 and the wire mesh wick 302 are stacked between the first shell plate 1 and the second shell plate 2; the capillary properties of the wick layer 3 are improved and its heat conduction path is optimized.

[0029] It should be noted that the cooling medium of the ultra-thin heat spreader is stored in the liquid absorbent core layer. In the liquid absorbent core layer, the middle cavity of the woven mesh liquid absorbent core structure serves as a steam channel.

[0030] It should be noted that the steam channel of this embodiment refers to: a specific path or space for steam circulation between the first shell plate 1, the second shell plate 2 and the liquid absorbent core layer 3 of the ultra-thin heat spreader.

[0031] In this embodiment, preferably, a steam channel is formed between the combination of the first shell plate 1, the woven mesh wick 301, the wire mesh wick 302 and the second shell plate 2, allowing steam to flow efficiently between the evaporation zone and the condensation zone of the ultra-thin heat spreader, thereby achieving rapid heat transfer.

[0032] It should be noted that the roughness of the micro-nano structure in this embodiment can be controlled by the parameters of laser ablation, thereby affecting the hydrophilicity of the liquid wick layer, so as to change the heat transfer performance of the ultra-thin vapor chamber.

[0033] It should be noted that the braided mesh liquid absorbent core 301 has at least one braided mesh; The number of layers of the wire mesh absorbent core 302 is at least one, wherein the woven mesh absorbent core 301 and the wire mesh absorbent core 302 are vertically distributed in the cavity.

[0034] In this embodiment, the wick layer 3 composed of the woven mesh wick 301 and the wire mesh wick 302 is not limited to one layer. The present application provides a layer to ensure that the wick has good capillary properties and hydrophilicity, so that the ultra-thin heat spreader has both light and thin characteristics, which is more conducive to application in the field of microelectronics technology. In this embodiment, the multi-layer composite wick is also within the protection scope of this application.

[0035] It should be noted that the overall thickness of the ultra-thin vapor chamber is in the range of 0.03 mm to 0.4 mm, wherein: The thickness of the liquid-absorbing core layer 3 is in the range of 0.01 mm to 0.1 mm; The thickness of the first shell plate 1 and the second shell plate 2 are both in the range of 0.01 mm to 0.15 mm.

[0036] In this embodiment, the overall thickness of the heat spreader is controlled below 0.4 mm, which is more conducive to broadening the application fields and application scenarios of the ultra-thin heat spreader in this application. Compared with the conventional 2mm ultra-thin heat spreader, this application can maintain stable heat dissipation performance in narrower or harsh working environments.

[0037] It should be noted that the second shell plate 2 has an inner curved surface, which protrudes in a direction away from the first shell plate 1 and is used to form the cavity. The liquid wick layer 3 is located on the inner curved surface and is used to provide a working channel for the cooling medium. It should be noted that if the structure of the absorbent core layer in other heat spreaders is not the composite structure of the woven mesh absorbent core 301 and the wire mesh absorbent core 302 mentioned in this application, then the upper shell plate of the heat spreader needs to be reinforced with support columns to enhance the stability of the heat spreader and prevent it from collapsing and deforming.

[0038] Specifically, the laser special processing ultra-thin heat sink also includes: The support column is arranged on the inner plane of the first shell plate 1 facing the second shell plate 2, and is used to support the first shell plate 1 to prevent the heat sink from collapsing.

[0039] Furthermore, the support column is a portion protruding from the inner plane of the shell plate for support, including but not limited to a cylindrical or hemispherical structure (not shown in the figure). Specifically, the support column is arranged in a rectangular array on the inner plane of the first shell plate 1. In this embodiment, the woven mesh wick 301 in the wick layer 3 also plays a supporting role, and acts on the ultra-thin heat spreader to enhance the stability of its structure and prevent it from collapsing and deforming. The main reason for setting the woven mesh wick 301 in the ultra-thin heat spreader is that the heat spreader of this embodiment is thinner than the heat spreader of the prior art, and is more prone to collapse and deformation.

[0040] It should be noted that, as mentioned above, the present application does not set a support column, and adopts a woven mesh liquid absorbent core 301 as a support column, which can reduce the thickness of the original support column and effectively reduce the overall thickness of the ultra-thin heat spreader.

[0041] It should be noted that the material of the liquid absorbent core layer 3 is preferably a copper mesh liquid absorbent core or a stainless steel wire mesh liquid absorbent core or a mixed spiral woven mesh liquid absorbent core. The above-mentioned mesh liquid absorbent core is fixed together by laser sintering, which strengthens the strength structure of the ultra-thin heat spreader and avoids the bulging and damage caused by the high temperature generated when the ultra-thin heat spreader is working.

[0042] In this embodiment, after laser ablation, the surface of the absorbent core layer 3 forms an irregular rough micro-nano structure, which increases the thermal contact area of ​​the working fluid and greatly promotes the heat exchange of the working fluid; while increasing the roughness of the surface of the absorbent core layer 3, it can also greatly enhance the effect of the capillary force of the absorbent core, promote the phase change cycle of the liquid working fluid, and greatly improve the heat transfer performance of the ultra-thin heat spreader.

[0043] It should be noted that the first shell plate 1 and the second shell plate 2 form microchannel structures on the inner surfaces through laser ablation, so as to improve the overall heat transfer performance of the ultra-thin heat spreader.

[0044] It should be noted that the material of the first shell plate 1 is any one of metal foil, polymer film or composite film; The material of the second shell plate 2 is any one of metal foil, polymer film or composite film.

[0045] It should be noted that laser welding technology is used between the first shell plate 1 and the second shell plate 2 to complete the packaging of the upper and lower shell plates of the ultra-thin heat spreader, which not only achieves high-precision welding, ensures the accuracy of the internal structure of the ultra-thin heat spreader and the stability of the weld, but also reduces the impact on the mechanical properties of the outer shell material during the manufacturing process, ensures the accuracy of the internal structure of the ultra-thin heat spreader while improving manufacturing efficiency and yield.

[0046] It should be noted that the liquid-absorbing core layer 3 is made of porous material, which includes but is not limited to plastic, polymer, foam metal or multi-layer woven wire mesh.

[0047] Example 2 This embodiment provides another installation method of the liquid absorbent core layer based on the embodiment 1, wherein the liquid absorbent core layer 3 may not be directly connected to the surface of the first shell plate 1 or the second shell plate 2.

[0048] In this embodiment, the liquid-absorbing core layer 3 contacts the surface of the first shell plate 1 or the second shell plate 2 and also falls within the protection scope of the present application.

[0049] Example 3 See also Figures 4 to 5 , is the laser special processing ultra-thin heat sink preparation method proposed in this application, and the proposed preparation method includes the following contents: Step S1, preparing the main material of the shell plate and the liquid absorbent core layer: taking two shell plates and the main material of the liquid absorbent core layer, cutting out the target outline, and etching a cavity on one of the shell plates, and obtaining the main material of the first shell plate 1, the second shell plate 2 and the liquid absorbent core layer 3 after pretreatment, specifically including the following contents: a. Take two shell plates and use laser etching technology to etch the required structure on the inner surface of the first shell plate 1 and the second shell plate 2, wherein the first shell plate 1 is a planar structure with a support column, serving as the upper shell plate, and the second shell plate 2 is a planar structure with a cavity, serving as the lower shell plate. Use high-precision methods such as laser cutting, plasma cutting or water jet cutting to cut the shell plates into the outer contour of the target structure shape. The pre-processing includes chamfering and deburring the edges of the shell plates to improve safety and ensure edge quality; b. preparing the main material of the liquid absorbent core layer 3, taking the main material of the liquid absorbent core layer 3 and cutting out the target shape outer contour of the liquid absorbent core layer 3, and obtaining the main material of the liquid absorbent core layer 3 after pretreatment; Step S2, microstructure processing: laser ablation is performed on the first shell plate 1 and the second shell plate 2 to form a microchannel structure, and ablation is performed on the main material surface of the liquid absorbent core layer 3 to form a micro-nano structure to obtain the liquid absorbent core layer 3; Specifically, Figure 2 As shown, the surface of the liquid-absorbing core layer 3 and the sintered inner surface of the shell plate containing the cavity are laser ablated by laser. The following is a detailed description of the process and its advantages: Select a suitable laser ablation laser head 5, and adjust the parameters such as the wavelength, power and focusing depth of the laser beam. Place the woven mesh absorbent core 301 and the silk screen absorbent core 302 to be processed by laser ablation on the laser processing platform, and scan the surface of the absorbent core layer main material with the laser beam of the laser ablation laser head 5 controlled by a computer. The processing result is that the scanned area of ​​the material is etched with a micro-nano structure. The laser ablation laser head 5 includes but is not limited to a carbon dioxide laser head, which is for reference only and is not intended to limit the present invention.

[0050] It should be noted that before laser ablation of the main material surface of the absorbent core layer, the surface of the material must be clean and flat to facilitate laser ablation and reduce ablation deviation. The absorbent core layer adopts laser ablation technology with the advantage of controllable parameters.

[0051] Furthermore, different processing parameters can be selected according to the different materials of the first shell plate 1 and the second shell plate 2 to achieve active design of the microchannel structure morphology on the inner surfaces of the first shell plate 1 and the second shell plate 2 .

[0052] Step S3, sintering the liquid-absorbing core layer: sintering the liquid-absorbing core layer to the inner wall of the shell plate containing the cavity; In this embodiment, the shell plate containing the cavity is the second shell plate 2. Specifically, the liquid-absorbing core layer 3 after laser ablation is fixed in the cavity of the second shell plate 2 by a sintering process, so that the two are closely fitted. In this embodiment, a sintering process of a composite liquid-absorbing core layer is disclosed, which specifically includes the following contents: Place the ablated single-layer liquid-absorbing core into a special graphite mold and clamp it with bolts; The assembled graphite mold of the composite liquid-absorbing core layer 3 is placed in an atmosphere furnace and sintered for 1 hour; Take out the sintered composite liquid absorbent core 3 and spot weld it to the second shell plate 2 of the ultra-thin heat spreader by a spot welding machine. The spot-welded sample was placed in a graphite mold, clamped by bolts, and then placed in an atmosphere furnace for sintering for 1 hour to obtain a finished composite liquid-absorbing core layer.

[0053] It should be noted that the laser used in preparing the absorbent core layer 3 is a femtosecond laser or a nanosecond laser, wherein the pulse frequency of the laser ablation laser head is 20Hz-80Hz, the power is 1W-30W, the scanning speed is 10mm / s-7000mm / s, the ablation depth is ≤3mm, and the scanning times are single or multiple.

[0054] Step S4, sealing the periphery of the vapor chamber: assemble the first shell plate 1 and the second shell plate 2 to form a butt joint at the contact point, perform periphery sealing on the butt joint by laser welding technology, and reserve a hole for the injection pipe; like Figure 4 As shown, the ultra-thin heat spreader performs peripheral sealing treatment on the first shell plate 1 and the second shell plate 2 through laser welding technology. The laser welding technology can adopt butt welding or lap welding, and the welding quality and the performance of the heat spreader are ensured by controlling the selected parameters of the laser.

[0055] In this embodiment, two laser welding technologies, butt welding and lap welding, are disclosed to obtain a detailed analysis of the ultra-thin heat sink of the present application: A Butt welding process: The first shell plate 1 and the second shell plate 2 with the sintered liquid absorbent core layer 3 are tightly fitted together, so that the end faces of the two outer peripheries are aligned, and a butt joint is formed at the contact point. The laser passes through the butt joint to melt the materials of the first shell plate 1 and the second shell plate 2 to form a weld, thereby achieving the purpose of welding. The ultra-thin heat spreader obtained by this welding method has the advantages of high air tightness, uniform weld quality, and can be flexibly used.

[0056] B Stitch welding process: The first shell plate 1 and the second shell plate 2 with the sintered liquid absorbent core layer 3 are tightly fitted together, so that the end faces of the two outer peripheries are aligned, and a butt joint is formed at the contact point. The laser passes through the surface of one of the shell plates, penetrates the first shell plate and melts the second shell plate to form a weld, thereby achieving the purpose of welding. This method has a fast welding speed and can withstand a certain positioning error. The ultra-thin heat spreader welded by this welding method has the advantages of high processing efficiency, small positioning deviation, and high yield rate.

[0057] In this embodiment, in order to ensure the long-term reliability and sealing of the ultra-thin vapor chamber, laser butt welding technology is used for final sealing while applying pressure for welding, forming a weld on the surface of the ultra-thin vapor chamber that is flush with the edge of the shell plate to ensure the sealing effect of the ultra-thin vapor chamber. Figure 5 This is a schematic diagram of the fish scale structure of the first shell plate and the second shell plate of the ultra-thin heat spreader after laser welding. The use of this welding appearance can ensure that the ultra-thin heat spreader of this embodiment has good sealing performance.

[0058] Specifically, in this embodiment, a pulsed laser welding machine is selected to perform peripheral sealing processing, and the pulse frequency of the laser welding laser head 6 thereof is ≤100 Hz, and the maximum power is 16 kW.

[0059] In this embodiment, a hole for the injection tube 4 needs to be reserved during the peripheral sealing process of the ultra-thin heat spreader, so that a cooling medium can be injected into the ultra-thin heat spreader cavity through the injection tube 4 in subsequent processes.

[0060] Step S5, liquid injection, vacuuming, and sealing: insert the liquid injection tube into the liquid injection tube hole and fix it, inject the cooling medium, perform vacuuming, seal, and cut off the liquid injection tube, specifically: c. inserting the injection tube into the injection tube hole and fixing the injection tube; d. Inject the cooling medium into the injection pipe, and perform vacuum treatment after the injection is completed; e. After sealing the injection tube, cut off the injection tube.

[0061] Specifically, the process includes the following: The required filling liquid working medium is obtained according to the size of the ultra-thin heat spreader and the structure of the composite liquid absorbing core layer 3. This is the prior art and will not be elaborated in detail here.

[0062] A high-precision automatic liquid injection machine or other suitable equipment is used to inject liquid working medium into the cavity of the ultra-thin heat spreader through the liquid injection pipe 4 .

[0063] After the filling is completed, the ultra-thin heat spreader is left to stand for about 1 minute to ensure that the working fluid is completely absorbed by the composite liquid absorbent core.

[0064] A vacuum extraction system is connected to the liquid injection pipe 4, and a vacuum pump in the vacuum extraction system is used to evacuate the cavity of the ultra-thin heat spreader to remove most of the air and other gases.

[0065] It should be noted that during the vacuuming process, it is necessary to monitor the pressure change in the cavity through a pressure sensor to determine whether the next step is required.

[0066] After confirming that the filling is correct and the ultra-thin heat spreader has good performance, the liquid filling pipe 4 is sealed to prevent leakage of the liquid working medium.

[0067] Finally, the ultra-thin heat spreader is tested and debugged after filling to ensure that its performance meets the design requirements.

[0068] In this embodiment, the flow rate and filling amount of the working fluid need to be strictly controlled during the filling process to ensure that the performance of the ultra-thin vapor chamber meets the design requirements.

[0069] In this embodiment, the vacuum extraction system generally includes components such as a vacuum pump, a pressure sensor, and a valve, which can accurately control the vacuum degree in the cavity.

[0070] In this embodiment, the test contents include heat transfer performance, pressure resistance performance, sealing performance and other aspects.

[0071] Step S6, finished product finishing: the thickness of the vapor chamber is shaped after the liquid injection tube is cut off, and the vapor chambers with thickness errors within the expected range are selected to obtain ultra-thin vapor chamber finished products.

[0072] It should be noted that when sintering the liquid absorbent core, if there are multiple pieces of liquid absorbent core main body material, the ablated multiple pieces of liquid absorbent core main body material need to be sintered and formed in a mold first and then sintered to the inner wall of the shell plate containing the cavity.

[0073] The laser special processing ultra-thin heat sink and the preparation method thereof of the present invention have the following advantages: The surface of the wick is micro-processed by high-energy laser beams, and the processing accuracy can reach the micron level. The operation is highly flexible and controllable. It can not only form a specific microstructure to meet the design and treatment of the microstructure morphology of the surface of the wick of the heat spreader, thereby significantly improving its capillary properties and hydrophilicity, but also accurately control the roughness, porosity and wettability of the wick surface, thereby optimizing the penetration, diffusion and transmission process of the liquid in the wick. Using a high-energy-density laser beam as a heat source, the local area of ​​the material to be welded is heated to a molten state accurately and quickly, achieving deep fusion of the materials while ensuring the narrowness and high quality of the weld. It can also minimize the impact on the mechanical properties of the shell material during the manufacturing process and improve the manufacturing yield of the heat spreader. At the same time, these two processes also have the advantages of precise processing, high production efficiency, and mass production.

[0074] The surface treatment process of the liquid wick of the ultra-thin heat spreader and the peripheral sealing process of the upper and lower shell plates both use laser technology, forming an integrated molding path for the ultra-thin heat spreader based on laser special processing, realizing the deep integration of laser special processing in the field of ultra-thin heat spreaders. Compared with traditional brazing, the laser welding in this application is contactless welding, which can avoid contaminating the internal liquid wick.

[0075] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the invention.

[0076] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0077] Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Mentioning "embodiment" in this article means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present embodiment application. The appearance of this phrase in various positions in the specification is not necessarily the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It can be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0078] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A laser special processing ultra-thin heat sink, characterized in that: include: A first shell plate (1); The second shell plate (2) is laser welded to the first shell plate (1) to form a closed cavity; A liquid absorbent core layer (3), the liquid absorbent core layer (3) being arranged in the containing cavity, and a surface of the liquid absorbent core layer (3) being formed into a micro-nano structure by laser ablation.

2. The laser special processing ultra-thin heat sink according to claim 1, characterized in that: The liquid-absorbing core layer (3) comprises: A braided mesh liquid absorbent core (301), wherein the braided mesh liquid absorbent core (301) comprises a plurality of braided and interlaced metal wires; A wire mesh wick (302), the wire mesh wick (302) comprising a plurality of metal wires arranged at a certain angle, the woven mesh wick (301) and the wire mesh wick (302) being stacked between the first shell plate (1) and the second shell plate (2); Wherein, at least one of the woven mesh liquid absorbent core (301) and the wire mesh liquid absorbent core (302) has the micro-nano structure.

3. The laser special processing ultra-thin heat sink according to claim 2, characterized in that: The number of woven meshes of the woven mesh liquid absorbent core (301) is at least one; The number of layers of the wire mesh liquid absorbent core (302) is at least one layer, wherein the woven mesh liquid absorbent core (301) and the wire mesh liquid absorbent core (302) are vertically distributed in the cavity.

4. The laser special processing ultra-thin heat sink according to claim 1, characterized in that: The overall thickness of the ultra-thin vapor chamber is in the range of 0.03 mm to 0.4 mm, wherein: The thickness of the liquid-absorbing core layer (3) is in the range of 0.01 mm to 0.1 mm; The thickness of the first shell plate (1) ranges from 0.01 mm to 0.15 mm; The thickness of the second shell plate (2) ranges from 0.01 mm to 0.15 mm.

5. The laser special processing ultra-thin heat sink according to claim 1, characterized in that: The second shell plate (2) has an inner curved surface, the inner curved surface protruding in a direction away from the first shell plate (1) and used to form the containing cavity, and the liquid absorbent core layer (3) is located on the inner curved surface.

6. The laser special processing ultra-thin heat sink according to claim 5, characterized in that: The first shell plate (1) forms a microchannel structure on the inner plane by laser ablation.

7. The laser special processing ultra-thin heat sink according to claim 5, characterized in that: The second shell plate (2) forms a microchannel structure on the inner curved surface by laser ablation.

8. The laser special processing ultra-thin heat sink according to claim 2, characterized in that: In the wire mesh liquid-absorbing core (302), a plurality of metal wires are arranged orthogonally.

9. A method for preparing a laser special processing ultra-thin heat sink, characterized in that: The method for preparing the laser special processing ultra-thin heat sink as claimed in any one of claims 1 to 8 comprises the following steps: Step S1, preparing the main material of the shell plate and the liquid absorbent core layer: taking two shell plates and the main material of the liquid absorbent core layer, cutting out the target outline, and etching a cavity on one of the shell plates, and obtaining the main material of the first shell plate, the second shell plate and the liquid absorbent core layer after pretreatment; Step S2, microstructure processing: laser ablation is performed on the first shell plate and the second shell plate to form a microchannel structure, and ablation is performed on the surface of the main material of the liquid absorbent core layer to form a micro-nano structure to obtain the liquid absorbent core layer; Step S3, sintering the liquid-absorbing core layer: sintering the liquid-absorbing core layer to the inner wall of the shell plate containing the cavity; Step S4, sealing the periphery of the vapor chamber: assembling the first shell plate and the second shell plate to form a butt joint at the contact point, performing a periphery sealing treatment on the butt joint by laser welding, and reserving a hole position for a liquid injection pipe; Step S5, liquid injection, vacuuming, and sealing: insert the liquid injection tube into the liquid injection tube hole and fix it, inject the cooling medium, perform vacuuming, seal, and cut off the liquid injection tube; Step S6, finished product finishing: perform thickness shaping on the vapor chamber, select the vapor chambers with thickness errors within the expected range, and obtain finished products.

10. The method for preparing a laser special processing ultra-thin heat sink according to claim 9, characterized in that: When sintering the liquid absorbent core, if there are multiple pieces of liquid absorbent core main body material, the ablated multiple pieces of liquid absorbent core main body material need to be sintered and formed in a prefabricated mold first and then sintered to the inner wall of the shell plate containing the cavity.

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