Air core coplanar ultrathin vapor chamber with hydrophilic and hydrophobic inner wall and preparation method of vapor chamber

Abstract

The invention discloses a gas core coplanar ultrathin vapor chamber with a hydrophilic and hydrophobic inner wall and a preparation method of the vapor chamber. The vapor chamber comprises an upper shell plate, a lower shell plate and a three-dimensional structure liquid absorption core. The upper shell plate and the lower shell plate are provided with inner cavities, the wall face of the inner cavity of the upper shell plate is connected with the top face of the three-dimensional structure wick, and the wall face of the inner cavity of the lower shell plate is connected with the bottom face of the three-dimensional structure wick. The upper shell plate and the lower shell plate are attached and packaged to form a sealing structure, and the three-dimensional structure liquid absorption core is wrapped in the sealing structure. Hydrophilic and hydrophobic wedge-shaped patterns are etched on the inner cavity wall faces, connected with the three-dimensional structure wick, of the upper shell plate and the lower shell plate. The upper wall surface and the lower wall surface of the steam channel are etched with the hydrophilic and hydrophobic interphase wedge-shaped patterns to form the hydrophilic and hydrophobic interphase wall surfaces, so that condensed working medium liquid drops can be quickly spread and quickly adsorbed by the liquid absorption core arranged on the side edge, and the steam channel cannot be blocked by the working medium liquid drops; and the problem of poor heat transfer performance of the ultrathin vapor chamber caused by increase of steam flow resistance is prevented.

Description

Technical Field

[0001] The invention belongs to the technical field of vapor chambers, and in particular relates to an ultra-thin vapor chamber with an air core on the same surface and a hydrophilic and hydrophobic inner wall and a preparation method thereof. Background Art

[0002] At present, in order to meet the development demand of lightweight and thin portable electronic products, it is necessary to reduce the thickness of the vapor chamber as much as possible to adapt to the compact internal space of electronic products. However, the maximum heat transfer power and thermal conductivity of the vapor chamber decrease rapidly as its thickness decreases, making it difficult to meet the heat dissipation needs of lightweight and thin electronic products. Therefore, how to solve the contradiction between the heat transfer performance requirements of the vapor chamber and the ultra-thin thickness requirements has become an urgent problem to be solved in the thermal management industry of high-performance lightweight electronic products. Summary of the invention

[0003] The main purpose of the present invention is to improve and break through the existing ultra-thin heat transfer limit power of the heat spreader, overcome the shortcomings and deficiencies of the existing technology that the thickness of the heat spreader is too low, which easily causes the steam channel to be blocked, thereby causing the heat transfer performance of the heat spreader to decrease, and propose an ultra-thin heat spreader with an air core on the same surface of the hydrophilic and hydrophobic inner wall and a preparation method thereof.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] An ultra-thin heat spreader with a hydrophilic and hydrophobic inner wall and an air core on the same surface, comprising an upper shell plate, a lower shell plate and a three-dimensional structure liquid wick;

[0006] The upper shell plate and the lower shell plate are provided with inner cavities, the inner cavity wall of the upper shell plate is connected to the top surface of the three-dimensional structure liquid absorbent core, and the inner cavity wall of the lower shell plate is connected to the bottom surface of the three-dimensional structure liquid absorbent core; the upper shell plate and the lower shell plate are fitted and packaged to form a sealing structure, and the three-dimensional structure liquid absorbent core is wrapped inside the sealing structure;

[0007] The left and right sides of the upper shell plate and the lower shell plate are spaced from the left and right sides of the three-dimensional structure liquid absorbent core to serve as a steam channel;

[0008] The three-dimensional structure liquid absorbent core specifically includes a flat wire mesh liquid absorbent core and a plurality of woven mesh liquid absorbent cores;

[0009] A plurality of woven mesh liquid absorbent cores are arranged side by side, disposed on the top surface of the flat wire mesh liquid absorbent core, and connected to the flat wire mesh liquid absorbent core;

[0010] The multiple braided mesh liquid absorbent cores are evenly divided into a number of groups, grooves are provided between the multiple braided mesh liquid absorbent cores in the group, and intervals are provided between the groups as steam channels;

[0011] The flat screen liquid absorbent core is provided with a plurality of strip through holes, the number, position and size of which correspond to the steam channel; the two ends of the flat screen liquid absorbent core are preset within a certain length range as the evaporation end and the condensation end respectively, and the flat screen liquid absorbent core within the range of the evaporation end and the condensation end is not provided with strip through holes;

[0012] The upper shell plate and the lower shell plate are made of stainless steel, and the inner cavity wall is electroplated with a copper layer, which has a micro-nano structure and is hydrophobic.

[0013] The copper layer of the inner cavity wall of the upper shell plate and the lower shell plate facing the multiple steam channels is etched with a wedge-shaped pattern with alternating hydrophilicity and hydrophobicity, so as to form the inner cavity wall of the shell plate with alternating hydrophilicity and hydrophobicity;

[0014] The wall surface of the inner cavity of the lower shell plate corresponding to the evaporation end and the condensation end of the flat screen liquid wick is not etched with a wedge-shaped pattern of alternating hydrophilic and hydrophobic water;

[0015] Furthermore, a semicircular injection channel is opened at one end of the upper shell plate and the lower shell plate. After the upper shell plate and the lower shell plate are fitted and packaged, the two semicircular injection channels are combined into an injection hole.

[0016] The present invention also includes a method for preparing an ultra-thin vapor chamber, which is used to prepare the ultra-thin vapor chamber with a hydrophilic and hydrophobic inner wall provided by the present invention, and comprises the following steps:

[0017] S1, preparing the upper shell and the lower shell and performing copper plating treatment;

[0018] S2, processing the inner cavity wall surfaces of the upper shell and the lower shell by photolithography, etching wedge-shaped patterns with alternating hydrophilic and hydrophobic properties, and forming the inner cavity wall surfaces of the shell plates with alternating hydrophilic and hydrophobic properties;

[0019] S3, using a woven mesh absorbent core and a flat wire mesh absorbent core to sinter in a mold to prepare a three-dimensional structure absorbent core;

[0020] S4. Assemble and package the various components of the heat spreader and complete the preparation of the ultra-thin heat spreader.

[0021] Furthermore, step S1 specifically includes:

[0022] Stainless steel plate is used as the basic material, and the thickness of the plate is 0.03-0.3mm;

[0023] The upper and lower shell plates with injection channels and inner cavities are processed by, including but not limited to, stamping, chemical etching, milling and cutting;

[0024] Electroplating is performed on the inner cavity wall surfaces of the upper and lower shell plates that have been preliminarily processed, including:

[0025] S11, putting the preliminarily processed upper and lower shell plates into a degreasing solution for degreasing treatment; the degreasing solution is composed of Na3PO4, NaOH, Na3CO4 and OP-10, the solution temperature is 50 to 60°C, the soaking time is 10 minutes, and then treated with clean water to ensure that there are no other impurities in the later stage;

[0026] S12, encapsulating the surrounding walls of the upper and lower shell plates with plastic sheets, leaving only the inner cavity wall exposed;

[0027] S13, electroplating copper, the anode is connected to the copper plate, the cathode is connected to the upper shell plate or lower shell plate packaged with the rubber plate, the plating solution composition is CuSO4·5H2O, H2SO4, CL - and additives;

[0028] S14, after the electroplating is completed, soak it in Na3CO4 solution for 2 minutes, and use ultrasonic treatment to remove impurities remaining on the surface;

[0029] S15, immerse the upper and lower shell plates in the copper sealant for 5 minutes;

[0030] S16. Grind the copper-plated surface, then polish it with short-neck velvet and polishing paste to obtain a mirror-finished surface, and finally dry and let it stand.

[0031] Furthermore, step S2 specifically includes:

[0032] S21, placing the upper and lower shell plates in a mixed solution of acetone and ethanol for ultrasonic cleaning for 10 minutes to remove oil stains; soaking the cleaned upper and lower shell plates in HCl for 15 minutes to remove the oxide layer on the copper-plated wall surface;

[0033] S22, using deionized water to clean the copper-plated shell plate, vacuum drying, and keeping the copper-plated wall clean during the process; soaking the cleaned upper and lower shell plates in a solution of K2S2O8, NaOH and deionized water for 60 minutes, controlling the temperature to 60°C, and then cleaning with deionized water and drying at 60°C in a vacuum environment for 1 hour. After the treatment is completed, a flower cluster-like micro-nano structure is generated on the copper-plated wall surface;

[0034] S23, soaking the upper and lower shell plates in an ethanol solution of perfluorodecyltrimethoxysilane for 12 hours, then rinsing with anhydrous ethanol for 3 times, and drying in a vacuum drying oven at 100° C. for 1 hour to obtain a fully hydrophobic copper-plated wall surface;

[0035] S24, selectively etching the fully hydrophobic copper-plated wall position corresponding to the steam channel through laser processing to etch a plurality of wedge-shaped patterns with alternating hydrophilic and hydrophobic patterns.

[0036] Furthermore, step S3 specifically includes:

[0037] S31, using a flattening process to make a flat screen liquid absorbent core and cutting it into a suitable size; weaving to make a woven screen liquid absorbent core and cutting it into a suitable size;

[0038] S32, arranging a plurality of woven mesh wicks and a flat wire mesh wick according to a designed three-dimensional wick structure, using a graphite mold with grooves to clamp and fix the relative positions of the woven mesh wick and the flat wire mesh wick, and then placing them in a sintering furnace and heating them to 870° C. for 2 hours to make the contact position of the woven mesh wick and the flat wire mesh wick melt slightly and then combine; before heating, first evacuate the furnace and then fill it with a mixture of nitrogen and hydrogen to prevent oxidation of the copper wire surface from affecting the combination;

[0039] S33, placing the sintered three-dimensional structure liquid absorbent core in a heating furnace, opening the air valve of the heating furnace connected to the outside air, heating to 500° C., keeping the temperature constant for 150 minutes, then stopping the heating and naturally cooling to room temperature to complete thermal oxidation;

[0040] S34, placing the thermally oxidized three-dimensional structure liquid absorbent core in a heating furnace, heating it to 380° C. at a rate of 5° C. / min, and then keeping the temperature constant for 60 minutes, then stopping the heating and naturally cooling it to room temperature, and during the process from the start of heating to the natural cooling to 40° C., the inner cavity of the heating furnace continuously introduces reducing gas to reduce the three-dimensional structure liquid absorbent core;

[0041] S35, using a punching process to cut off part of the flat screen wick and excess woven screen wick from the restored three-dimensional structure wick, the position of the removed part of the flat screen wick corresponds to the steam channel of the heat spreader to obtain the desired three-dimensional structure wick.

[0042] Furthermore, step S4 specifically includes:

[0043] S41, placing the upper and lower shell plates in a laser welding fixture, applying ultraviolet sealant on the outside of one end of the injection tube and inserting it into the injection hole formed in the upper and lower shell plates, and then applying ultraviolet sealant around the injection hole, and then placing the upper and lower shell plates under ultraviolet light for irradiation, setting parameters, and waiting for solidification; using a screw wrench to pre-tighten the welding area around the upper and lower shell plates, using argon protection to laser weld the upper and lower shell plates around, and taking out the plates after welding is completed and letting them stand to cool to room temperature;

[0044] S42, filling a certain amount of deionized water into the inner cavity of the heat spreader through the liquid injection pipe, connecting a vacuum pump to extract the air in the inner cavity to below 10Pa, and then cold-pressing weld the end of the liquid injection pipe with a mold to achieve temporary sealing;

[0045] S43. Place the heat spreader vertically, heat the bottom of the heat spreader to 100°C and keep the temperature constant for 90 seconds, so that the non-condensable gas dissolved in the deionized water can be gathered inside the injection tube after sufficient phase change cycle; use a sealing mold to extrude the bottom of the cold-welded injection tube and cut off the injection tube, and then use laser welding to melt and seal the evaporation end of the heat spreader after the injection tube is cut off, so as to complete the production of the ultra-thin heat spreader.

[0046] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0047] 1. The present invention etches alternating hydrophilic and hydrophobic wedge patterns on the upper and lower walls of the vapor chamber steam channel to form alternating hydrophilic and hydrophobic walls, so that the working fluid droplets condensed on the surface of the steam channel can be quickly spread out and quickly adsorbed by the liquid wicks on both sides, so that the steam channel will not be blocked by the working fluid droplets, preventing the increase in steam flow resistance and the problem of poor temperature uniformity of the vapor chamber. At the same time, the liquid can quickly flow back to the evaporation end of the vapor chamber to avoid the evaporation end from drying out, thereby improving the maximum heat transfer power of the vapor chamber.

[0048] 2. The heat spreader of the present invention adopts a structure in which a liquid wick and three steam channels are spaced apart from each other. There is no flat wire mesh structure at the non-evaporation end and the condensation end of the steam channel, which increases the thickness of the steam channel to the greatest extent. As a result, while ensuring the ultra-thin thickness of the heat spreader, the steam flow resistance is small, the gas-liquid interaction is faster, and thus the heat transfer performance is higher.

[0049] 3. The three-dimensional structure liquid absorbent core of the present invention has a high comprehensive permeability and capillary capacity, simple raw materials, and a manufacturing process suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is an exploded view of the structure of the vapor chamber of the present invention;

[0051] Figure 2 is a schematic diagram of the interior of the vapor chamber of the present invention;

[0052] Figure 3 yes Figure 2 The cross-sectional view at A in the middle;

[0053] Figure 4 yes Figure 2 The cross-sectional view at B in the middle;

[0054] Figure 5 is a top view of the upper housing in the embodiment;

[0055] Figure 6 is a top view of the lower housing in the embodiment;

[0056] Figure 7Schematic diagram of a hydrophilic-hydrophobic wedge-shaped pattern in an embodiment;

[0057] Figure 8 is a schematic diagram of the change of water droplets in the steam channel in the embodiment;

[0058] Fig. 9 is a schematic diagram of an electroplated copper layer in an embodiment;

[0059] Fig.10 Schematic diagram of the preparation of the three-dimensional structure liquid absorbent core in the embodiment;

[0060] Explanation of the accompanying figures: 1-upper shell plate; 2-three-dimensional structure liquid absorbent core; 201-woven mesh liquid absorbent core; 202-flat screen liquid absorbent core; 3-lower shell plate; 4-inner cavity; 5-liquid injection channel; 6-wedge pattern; 7-groove; 8-strip through hole; 9-liquid injection tube; 10-droplet; 11-graphite mold; 12-sheet liquid absorbent core. DETAILED DESCRIPTION

[0061] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0062] Example

[0063] like Figure 1 and Figure 2 As shown, the present invention is an ultra-thin heat spreader with a hydrophilic and hydrophobic inner wall, comprising an upper shell plate 1, a lower shell plate 3 and a three-dimensional structure liquid wick 2;

[0064] The upper shell plate and the lower shell plate are provided with an inner cavity 4, the inner cavity wall of the upper shell plate is connected to the top surface of the three-dimensional structure liquid absorbent core, and the inner cavity wall of the lower shell plate is connected to the bottom surface of the three-dimensional structure liquid absorbent core; the upper shell plate and the lower shell plate are fitted and packaged to form a sealed structure, and the three-dimensional structure liquid absorbent core is wrapped inside the sealed structure; the three-dimensional structure liquid absorbent core plays a supporting role.

[0065] The upper shell plate and the lower shell plate are made of stainless steel, and the inner cavity wall is electroplated with a copper layer; a semicircular injection channel 5 is opened at one end of the upper shell plate and the lower shell plate. After the upper shell plate and the lower shell plate are fitted and packaged, the two semicircular injection channels are combined into an injection hole.

[0066] A wedge-shaped pattern 6 with alternating hydrophilic and hydrophobic characteristics is etched on the inner cavity wall surface where the upper shell plate and the lower shell plate are connected to the three-dimensional structure liquid wick.

[0067] In this embodiment, the left and right sides of the upper shell plate and the lower shell plate are spaced from the left and right sides of the three-dimensional structure liquid absorbent core to serve as steam channels.

[0068] like Figure 2 , Figure 3 as well as Figure 4As shown, the three-dimensional structure wick specifically includes a plane screen wick 202 and a plurality of woven screen wicks 201; the plurality of woven screen wicks are arranged side by side, disposed on the top surface of the plane screen wick, and connected to the plane screen wick.

[0069] The plurality of braided mesh absorbent cores are evenly divided into a plurality of groups, and grooves 7 are provided between the plurality of braided mesh absorbent cores in the group (the groove width is set to 0.05 mm in this embodiment), and intervals are provided between the groups as steam channels; Figure 2 , Figure 3 as well as Figure 4 As shown, in this embodiment, there are 6 woven mesh wicks, which are evenly divided into two groups, and there are 3 steam channels.

[0070] The plane screen liquid absorbent core is provided with a plurality of strip-shaped through holes 8 (3 in this embodiment), the number, position and size of the strip-shaped through holes correspond to the steam channel; the two ends of the plane screen liquid absorbent core are preset within a certain length range as the evaporation end and the condensation end respectively, and the plane screen liquid absorbent core within the range of the evaporation end and the condensation end is not provided with strip-shaped through holes. The position of the strip-shaped through holes, that is, the position of the steam channel, is not provided with a plane screen, which increases the thickness of the steam channel to a certain extent;

[0071] In this embodiment, if Figure 5 , Figure 6 and Figure 7 As shown, the copper layer of the inner cavity wall of the upper shell plate and the lower shell plate facing the multiple steam channels is etched with a wedge-shaped pattern of alternating hydrophilicity and hydrophobicity to form the inner cavity wall of the shell plate with alternating hydrophilicity and hydrophobicity; and, as shown Figure 6 As shown, the inner cavity wall of the lower shell plate corresponding to the evaporation end and the condensation end of the plane wire mesh wick is not etched with a wedge-shaped pattern of alternating hydrophilic and hydrophobic elements. Figure 7 In the figure, the black frame is the hydrophobic area; Figure 7 and Figure 8 As shown, the hydrophilic and hydrophobic wedge-shaped pattern can regulate the flow of the droplet 10, so that the droplet can quickly Figure 7 The liquid flows in the direction of the middle arrow into the three-dimensional structured liquid absorbent core on both sides of the steam channel.

[0072] The ultra-thin heat spreader of this embodiment is provided with a hydrophilic-hydrophobic wedge pattern on the inner wall of the upper and lower shell plates, so that the upper and lower walls of the steam channel of the assembled heat spreader are fully and evenly covered with the hydrophilic-hydrophobic wedge pattern, so that the working fluid droplets condensed on the surface of the steam channel can be quickly spread out and quickly adsorbed by the wicks on both sides, so that the steam channel will not be blocked by the working fluid droplets, preventing the increase of steam flow resistance and the problem of poor temperature uniformity of the heat spreader. On the other hand, the ultra-thin heat spreader adopts a structure in which the wick and three steam channels are spaced apart from each other, and there is no flat wire mesh structure at the non-evaporation end and condensation end of the steam channel, which maximizes the thickness of the steam channel, so that the steam flow resistance is small and the gas-liquid interaction is faster while ensuring the ultra-thin thickness of the heat spreader, so that it has a higher heat transfer performance. On the other hand, the three-dimensional structure wick has a higher comprehensive permeability and capillary capacity, simple raw materials, and the manufacturing process is suitable for mass production.

[0073] In another embodiment, a method for preparing an ultra-thin vapor chamber is provided, which is used to prepare the ultra-thin vapor chamber with an air core on the same surface and a hydrophilic and hydrophobic inner wall as described in the embodiment, comprising the following steps:

[0074] S1. Prepare the upper shell and the lower shell and perform copper plating treatment; specifically including:

[0075] Stainless steel plate is used as the basic material, and the thickness of the plate is 0.03-0.3mm;

[0076] The upper and lower shell plates with injection channels and inner cavities are processed by, including but not limited to, stamping, chemical etching, milling and cutting;

[0077] Electroplating is performed on the inner wall surfaces of the upper and lower shell plates that have been preliminarily processed, such as Fig. 9 As shown, including:

[0078] S11, putting the preliminarily processed upper and lower shell plates into a degreasing solution for degreasing treatment; the degreasing solution is composed of Na3PO4, NaOH, Na3CO4 and OP-10, the solution temperature is 50 to 60°C, the soaking time is 10 minutes, and then treated with clean water to ensure that there are no other impurities in the later stage;

[0079] S12, encapsulating the surrounding walls of the upper and lower shell plates with a rubber sheet, exposing only the inner cavity wall portion, the rubber sheet does not undergo any physical or chemical reaction with the stainless steel and the solution, ensuring that the subsequent encapsulation process of the vapor chamber is not affected;

[0080] S13, electroplating copper, the anode is connected to the copper plate, the cathode is connected to the upper shell plate or lower shell plate packaged with the rubber plate, the plating solution composition is CuSO4·5H2O, H2SO4, CL - and additives, and powered on for 20 min at room temperature;

[0081] S14, after the electroplating is completed, soak it in Na3CO4 for 2 minutes, and use ultrasonic treatment to remove impurities remaining on the surface;

[0082] S15, immersing the upper and lower shell plates in a copper sealant for 5 minutes, thereby protecting the copper-plated wall surface;

[0083] S16. Grind the copper-plated surface, then polish it with short-neck velvet and polishing paste to obtain a mirror-finished surface, and finally dry and let it stand.

[0084] The copper layer obtained by the copper plating method adopted in this embodiment has a thickness of micron level and is firm, reliable and not easy to fall off; a stainless steel shell plate is selected as the substrate and a copper layer is plated inside, so that a hydrophilic and hydrophobic pattern can be easily processed. Moreover, after the heat spreader is evacuated, stainless steel will react with water for a long time to generate non-condensable gas, resulting in poor UTVC performance. Copper can remain stable with water for a long time under vacuum conditions (anaerobic conditions), and at the same time ensure that the properties of the hydrophilic wedge pattern will not be destroyed due to the high temperature of the later processing during the later packaging.

[0085] S2. Processing the inner cavity wall surfaces of the upper shell and the lower shell by photolithography, etching a wedge-shaped pattern with alternating hydrophilic and hydrophobic properties, and forming an inner cavity wall surface of the shell plate with alternating hydrophilic and hydrophobic properties, specifically comprising:

[0086] S21, placing the upper and lower shell plates in a copper plate and ultrasonically cleaning them in a mixed solution of acetone and ethanol for 10 minutes to remove oil stains; soaking the cleaned upper and lower shell plates in HCl for 15 minutes to remove the oxide layer on the copper-plated wall surface;

[0087] S22, using deionized water to clean the copper-plated shell plate, vacuum drying, and keeping the copper-plated wall clean during the whole process; soaking the cleaned upper and lower shell plates in a solution of K2S2O8, NaOH and deionized water for 60 minutes, controlling the temperature to 60°C, then cleaning the sample with deionized water and drying it in a vacuum environment at 60°C for 1 hour. After the above method, the copper-plated wall surface will produce a flower cluster-like micro-nano structure;

[0088] S23, soaking the upper and lower shell plates in an ethanol solution of perfluorodecyltrimethoxysilane for 12 hours, then rinsing with anhydrous ethanol for 3 times, and drying in a vacuum drying oven at 100° C. for 1 hour to obtain a fully hydrophobic copper-plated wall surface;

[0089] S24. Selectively etch the fully hydrophobic copper-plated wall corresponding to the steam channel by laser processing; generate high-energy laser by laser and focus it on the surface of the processed object. Since the laser energy is highly concentrated, the surface of the processed object will be locally heated, resulting in melting or vaporization. Therefore, the fluorine on the surface of the hydrophobic copper layer can be removed by laser. The laser power is 100%, the scanning rate is 500 mm / s, and the number of scans is 3, so that three wedge-shaped patterns with alternating hydrophilic and hydrophobic properties can be obtained.

[0090] S3, using a woven mesh absorbent core and a flat wire mesh absorbent core to sinter in a mold to prepare a three-dimensional structure absorbent core; Fig.10 As shown, specifically including:

[0091] S31, using a flattening process to make a flat screen type liquid absorbent core and cutting it into a suitable size; weaving to make a woven screen liquid absorbent core and cutting it into a suitable size;

[0092] S32, arranging a plurality of woven mesh wicks and a flat screen wick according to the designed three-dimensional wick structure, using a graphite mold 11 with grooves to clamp and fix the relative positions of the woven mesh wick and the flat screen wick, and then placing them in a sintering furnace and heating them to 870° C. for 2 hours to make the contact position of the woven mesh wick and the flat screen wick melt and then combine; before heating, first evacuate the furnace and fill it with a mixture of nitrogen and hydrogen to prevent oxidation of the copper wire surface from affecting the combination;

[0093] S33, arranging the sintered three-dimensional structure liquid absorbent core in a heating furnace, opening the air valve of the heating furnace connected to the outside air, heating to 500° C., keeping the temperature constant for 150 minutes, then stopping the heating and naturally cooling to room temperature to complete thermal oxidation; the three-dimensional structure liquid absorbent core is made hydrophilic by thermal oxidation treatment, and the capillary performance is improved, thereby improving the heat transfer performance of the heat spreader;

[0094] S34, arranging the oxidized three-dimensional structure liquid absorbent core in a heating furnace, heating to 380° C. at a rate of 5° C. / min, and then keeping the temperature constant for 60 minutes, then stopping the heating and naturally cooling to room temperature, and during the process from the start of heating to the natural cooling to 40° C., the inner cavity of the heating furnace continuously introduces reducing gas to reduce the three-dimensional structure liquid absorbent core;

[0095] S35, using a punching process to cut off part of the planar wire mesh wicks and excess woven mesh wicks from the restored sheet wick 12, the position of the removed part of the planar wire mesh wicks corresponds to the steam channel of the heat spreader, so as to obtain the desired three-dimensional structure wick 2.

[0096] The three-dimensional structured liquid absorbent core of the present embodiment has the structural features of the grooved liquid absorbent core and the wire mesh type liquid absorbent core due to its reasonable structural configuration, so that the liquid absorbent core has the same advantages as the conventional composite liquid absorbent core, and has high permeability and strong capillary performance. In addition, the flat wire mesh liquid absorbent core is only provided in places other than the steam channel, which effectively saves space and provides more cavities, ensuring that the internal gas pressure drop of the heat spreader will not increase due to the small steam channel when the heat spreader is working; the preparation process of the three-dimensional structured liquid absorbent core is simple, it can be mass-produced, and the raw materials are relatively convenient to obtain, so it has high economic benefits.

[0097] S4. Assemble and package the various components of the vapor chamber to complete the preparation of the ultra-thin vapor chamber; specifically including:

[0098] S41, placing the upper and lower shell plates in a light welding fixture, applying ultraviolet sealant to the outside of one end of the injection tube 9 and inserting it into the injection hole formed by the upper and lower shell plates, and then applying ultraviolet sealant around the injection hole (the ultraviolet sealant is applied to prevent the injection tube and the injection hole from not fitting tightly, which may cause leakage in the subsequent process flow), and then placing the upper and lower shell plates under ultraviolet light for irradiation, setting parameters (5 minutes for each positive and negative irradiation time), and waiting for solidification; using a screw wrench to pre-tighten the welding area around the upper and lower shell plates, using argon protection to laser weld the upper and lower shell plates around, with a power of 25w and a welding speed of 80mm / min. After welding, take it out and let it stand, and cool it to room temperature;

[0099] S42, filling a certain amount of deionized water into the inner cavity of the heat spreader through the liquid injection pipe, connecting a vacuum pump to extract the air in the inner cavity to below 10Pa, and then cold-pressing weld the end of the liquid injection pipe with a mold to achieve temporary sealing;

[0100] S43. Place the heat spreader vertically, heat the bottom of the heat spreader to 100°C and keep the temperature constant for 90 seconds, so that the non-condensable gas dissolved in the deionized water can be gathered inside the injection tube after sufficient phase change cycle; use a sealing mold to extrude the bottom of the cold-welded injection tube and cut off the injection tube, and then use laser welding to melt and seal the evaporation end of the heat spreader after the injection tube is cut off, so as to complete the production of the ultra-thin heat spreader.

[0101] It should also be noted that in this specification, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0102] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An ultra-thin heat spreader with an air core on the same surface and a hydrophilic and hydrophobic inner wall, characterized in that: It includes an upper shell plate, a lower shell plate and a three-dimensional structure liquid wick; The upper shell plate and the lower shell plate are provided with inner cavities, the inner cavity wall of the upper shell plate is connected to the top surface of the three-dimensional structure liquid absorbent core, and the inner cavity wall of the lower shell plate is connected to the bottom surface of the three-dimensional structure liquid absorbent core; the upper shell plate and the lower shell plate are fitted and packaged to form a sealing structure, and the three-dimensional structure liquid absorbent core is wrapped inside the sealing structure; The left and right sides of the upper shell plate and the lower shell plate are spaced from the left and right sides of the three-dimensional structure liquid absorbent core to serve as a steam channel; The three-dimensional structure liquid absorbent core specifically includes a flat wire mesh liquid absorbent core and a plurality of woven mesh liquid absorbent cores; A plurality of woven mesh liquid absorbent cores are arranged side by side, disposed on the top surface of the flat wire mesh liquid absorbent core, and connected to the flat wire mesh liquid absorbent core; The multiple braided mesh liquid absorbent cores are evenly divided into a number of groups, grooves are provided between the multiple braided mesh liquid absorbent cores in the group, and intervals are provided between the groups as steam channels; The flat screen liquid absorbent core is provided with a plurality of strip through holes, the number, position and size of which correspond to the steam channel; the two ends of the flat screen liquid absorbent core are preset within a certain length range as the evaporation end and the condensation end respectively, and the flat screen liquid absorbent core within the range of the evaporation end and the condensation end is not provided with strip through holes; The upper shell plate and the lower shell plate are made of stainless steel, and the inner cavity wall is electroplated with a copper layer, which has a micro-nano structure and is hydrophobic. The copper layer of the inner cavity wall of the upper shell plate and the lower shell plate facing the multiple steam channels is etched with a wedge-shaped pattern with alternating hydrophilicity and hydrophobicity, so as to form the inner cavity wall of the shell plate with alternating hydrophilicity and hydrophobicity; The inner cavity wall surface of the lower shell plate corresponding to the evaporation end and the condensation end of the plane wire mesh liquid wick is not etched with a wedge-shaped pattern of alternating hydrophilic and hydrophobic water.

2. The ultra-thin vapor chamber with a hydrophilic and hydrophobic inner wall according to claim 1, characterized in that: One end of the upper shell plate and the lower shell plate is provided with a semicircular liquid injection channel. After the upper shell plate and the lower shell plate are fitted and sealed, the two semicircular liquid injection channels are combined into a liquid injection hole.

3. A method for preparing an ultra-thin vapor chamber, for preparing the ultra-thin vapor chamber with an air core on the same surface and a hydrophilic and hydrophobic inner wall as claimed in any one of claims 1 to 2, characterized in that: The following steps are involved: S1, preparing the upper shell and the lower shell and performing copper plating treatment; S2, processing the inner cavity wall surfaces of the upper shell and the lower shell by photolithography, etching wedge-shaped patterns with alternating hydrophilic and hydrophobic properties, and forming the inner cavity wall surfaces of the shell plates with alternating hydrophilic and hydrophobic properties; S3, using a woven mesh absorbent core and a flat wire mesh absorbent core to sinter in a mold to prepare a three-dimensional structure absorbent core; S4. Assemble and package the various components of the heat spreader and complete the preparation of the ultra-thin heat spreader.

4. The method for preparing an ultra-thin vapor chamber according to claim 3, characterized in that: Step S1 specifically includes: Stainless steel plate is used as the basic material, and the thickness of the plate is 0.03-0.3mm; The upper and lower shell plates with injection channels and inner cavities are processed by, including but not limited to, stamping, chemical etching, milling and cutting; Electroplating is performed on the inner cavity wall surfaces of the upper and lower shell plates that have been preliminarily processed, including: S11, putting the preliminarily processed upper and lower shell plates into a degreasing solution for degreasing treatment; the degreasing solution is composed of Na3PO4, NaOH, Na3CO4 and OP-10, the solution temperature is 50 to 60°C, the soaking time is 10 minutes, and then treated with clean water to ensure that there are no other impurities in the later stage; S12, encapsulating the surrounding walls of the upper and lower shell plates with plastic sheets, leaving only the inner cavity wall exposed; S13, electroplating copper, the anode is connected to the copper plate, the cathode is connected to the upper shell plate or lower shell plate packaged with the rubber plate, the plating solution composition is CuSO4·5H2O, H2SO4, CL - and additives; S14, after the electroplating is completed, soak it in Na3CO4 solution for 2 minutes, and use ultrasonic treatment to remove impurities remaining on the surface; S15, immerse the upper and lower shell plates in the copper sealant for 5 minutes; S16, grinding the copper-plated surface, and then polishing it with short-neck velvet and polishing paste to obtain a mirror-finished surface, and finally drying and letting it stand.

5. The method for preparing an ultra-thin vapor chamber according to claim 3, characterized in that: Step S2 specifically includes: S21, placing the upper and lower shell plates in a mixed solution of acetone and ethanol for ultrasonic cleaning for 10 minutes to remove oil stains; soaking the cleaned upper and lower shell plates in HCl for 15 minutes to remove the oxide layer on the copper-plated wall surface; S22, using deionized water to clean the copper-plated shell plate, vacuum drying, and keeping the copper-plated wall clean during the process; soaking the cleaned upper and lower shell plates in a solution of K2S2O8, NaOH and deionized water for 60 minutes, controlling the temperature to 60°C, and then cleaning with deionized water and drying at 60°C in a vacuum environment for 1 hour. After the treatment is completed, a flower cluster-like micro-nano structure is generated on the copper-plated wall surface; S23, soaking the upper and lower shell plates in an ethanol solution of perfluorodecyltrimethoxysilane for 12 hours, then rinsing with anhydrous ethanol for 3 times, and drying in a vacuum drying oven at 100° C. for 1 hour to obtain a fully hydrophobic copper-plated wall surface; S24, selectively etching the fully hydrophobic copper-plated wall position corresponding to the steam channel by laser processing, etching a plurality of wedge-shaped patterns with alternating hydrophilic and hydrophobic characteristics.

6. The method for preparing an ultra-thin vapor chamber according to claim 3, characterized in that: Step S3 specifically includes: S31, using a flattening process to make a flat screen liquid absorbent core and cutting it into a suitable size; weaving to make a woven screen liquid absorbent core and cutting it into a suitable size; S32, arranging a plurality of woven mesh wicks and a flat wire mesh wick according to a designed three-dimensional wick structure, using a graphite mold with grooves to clamp and fix the relative positions of the woven mesh wick and the flat wire mesh wick, and then placing them in a sintering furnace and heating them to 870° C. for 2 hours to make the contact position of the woven mesh wick and the flat wire mesh wick melt slightly and then combine; before heating, first evacuate the furnace and then fill it with a mixture of nitrogen and hydrogen to prevent oxidation of the copper wire surface from affecting the combination; S33, placing the sintered three-dimensional structure liquid absorbent core in a heating furnace, opening the air valve of the heating furnace connected to the outside air, heating to 500° C., keeping the temperature constant for 150 minutes, then stopping the heating and naturally cooling to room temperature to complete thermal oxidation; S34, placing the thermally oxidized three-dimensional structure liquid absorbent core in a heating furnace, heating it to 380° C. at a rate of 5° C. / min, and then keeping the temperature constant for 60 minutes, then stopping the heating and naturally cooling it to room temperature, and during the process from the start of heating to the natural cooling to 40° C., the inner cavity of the heating furnace continuously introduces reducing gas to reduce the three-dimensional structure liquid absorbent core; S35, using a punching process to cut off part of the flat screen wick and excess woven screen wick from the restored three-dimensional structure wick, the position of the removed part of the flat screen wick corresponds to the steam channel of the heat spreader to obtain the desired three-dimensional structure wick.

7. The method for preparing an ultra-thin vapor chamber according to claim 3, characterized in that: Step S4 specifically includes: S41, placing the upper and lower shell plates in a laser welding fixture, applying ultraviolet sealant on the outside of one end of the injection tube and inserting it into the injection hole formed in the upper and lower shell plates, and then applying ultraviolet sealant around the injection hole, and then placing the upper and lower shell plates under ultraviolet light for irradiation, setting parameters, and waiting for solidification; using a screw wrench to pre-tighten the welding area around the upper and lower shell plates, using argon protection to laser weld the upper and lower shell plates around, and taking out the plates after welding is completed and letting them stand to cool to room temperature; S42, filling a certain amount of deionized water into the inner cavity of the heat spreader through the liquid injection pipe, connecting a vacuum pump to extract the air in the inner cavity to below 10Pa, and then cold-pressing weld the end of the liquid injection pipe with a mold to achieve temporary sealing; S43. Place the heat spreader vertically, heat the bottom of the heat spreader to 100°C and keep the temperature constant for 90 seconds, so that the non-condensable gas dissolved in the deionized water can be gathered inside the injection tube after sufficient phase change cycle; use a sealing mold to extrude the bottom of the cold-welded injection tube and cut off the injection tube, and then use laser welding to melt and seal the evaporation end of the heat spreader after the injection tube is cut off, so as to complete the production of the ultra-thin heat spreader.

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