Liquid absorption core with separated steam channel and liquid channel, preparation method of liquid absorption core and vapor chamber

Abstract

The invention belongs to the technical field of hot plate design and manufacturing, and particularly relates to a liquid absorption core with a steam channel and a liquid channel separated, a preparation method of the liquid absorption core and a vapor chamber. The liquid absorption core with the steam channel and the liquid channel separated comprises a liquid absorption core body, a protruding part is arranged at one end of the liquid absorption core body, the position where the protruding part is located corresponds to a chip, and a plurality of tooth-shaped liquid backflow channels arranged in parallel are arranged at the other end of the liquid absorption core body. Each tooth-shaped liquid backflow channel is provided with a root portion fixed to the wick body and a free end portion opposite to the root portion, and a steam channel is formed by a gap between every two adjacent tooth-shaped liquid backflow channels. The steam channel and the liquid backflow channel of the liquid absorption core are located on the same plane, the height of the steam channel can be maximized, the height of the steam channel is equal to that of the inner cavity of the vapor chamber, resistance in the steam conveying process can be obviously reduced, the steam conveying rate can be increased, and the temperature uniformity of the whole vapor chamber can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hot plate design and manufacturing, and in particular relates to a liquid wick with separated steam channels and liquid channels, a preparation method thereof, and a heat spreader. Background Art

[0002] With the advancement of 5G network construction, the functions of 5G terminal equipment have become more diversified. Chips need to cope with complex environmental conditions, and their high-speed operation will cause high heat problems. When meeting the requirements of high integration, thinness and maximum space utilization of terminal equipment at the same time, it is necessary to consider the use of ultra-thin heat spreaders. Due to the fine and varied internal structure of the heat spreader and the very complex phase change heat transfer mechanism, there are many factors that affect the heat transfer performance. As the heat spreader develops towards ultra-thinness, it is necessary to comprehensively consider various design problems.

[0003] For existing technologies, on the one hand, the heat transfer performance of the vapor chamber must be met, and on the other hand, it must be made ultra-thin. Studies have shown that when the thickness is below the critical thickness of 0.3mm, as the thickness further decreases, the thermal resistance of the steam chamber heat transfer will rise rapidly, causing the overall heat transfer performance of the vapor chamber to decrease. For ultra-thin vapor chambers below 0.3mm, the steam transmission space is extremely limited. Therefore, the traditional vapor chamber with an upper and lower unequal surface structure (the liquid absorbent core and the steam channel are not in the same plane) has the problem of insufficient steam chamber thickness and conflict between the gas channel and the liquid return channel of the liquid absorbent core, resulting in poor heat transfer performance of such vapor chambers with a thickness of less than 0.3mm, and they have not been used in large quantities. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a wick with separated steam channels and liquid channels, a preparation method thereof, and a vapor chamber. The steam channel and liquid reflux channel of the wick of the present invention are in the same plane, which can maximize the height of the steam channel and make it equal to the inner cavity of the vapor chamber. This can significantly reduce the resistance during steam transmission, increase the steam transmission rate, and help improve the temperature uniformity of the overall vapor chamber. The above-mentioned wick is used in an ultra-thin vapor chamber with a thickness of less than 0.35 mm, which can meet the temperature uniformity of a heat source power of 5-8W. The temperature difference between the upper surface of the heat source of the vapor chamber and the cold end of the upper surface can be controlled within 5°C, which can effectively solve the problem of local high heat flow heat dissipation of microelectronic devices in confined spaces.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the embodiment of the present invention is: In the first aspect, an embodiment of the present invention provides a liquid absorbent core with separated steam channels and liquid channels, comprising a liquid absorbent core body, one end of the liquid absorbent core body is provided with a protrusion, the position of the protrusion corresponds to the chip setting, and the other end of the liquid absorbent core body is provided with a plurality of parallel serrated liquid reflux channels, each of the serrated liquid reflux channels has a root fixed to the liquid absorbent core body, and a free end opposite to the root, and the gap between adjacent serrated liquid reflux channels forms a steam channel.

[0006] Furthermore, the liquid absorbent core body is integrally formed, and the width of the protrusion is smaller than the width of the liquid absorbent core body.

[0007] Furthermore, the absorbent core is made of multi-layer metal mesh, foam metal, composite of foam metal and metal mesh, composite of metal mesh and metal powder, the thickness of the absorbent core is 40-200 μm, the porosity of the absorbent core is 60%-80%, and the pore size is 10-25 μm.

[0008] Preferably, the wick is made of metal copper or stainless steel.

[0009] Furthermore, the area S1 of the steam channel / the area S2 of the toothed liquid reflux channel=5:1-1:1.

[0010] Furthermore, the size of the protrusion is 10mm×10mm-20mm×20mm, and the protrusion and the root of the wick body are continuous, and are used for storing and evaporating working fluid.

[0011] In a second aspect, an embodiment of the present invention provides a method for preparing a wick with separated steam channels and liquid channels as described in the first aspect, wherein the wick body is formed by a material removal processing method, or formed by a slurry in-situ forming process and then sintered, or processed by 3D printing; When the material removal processing method is used for forming, the steam channel is formed by removing material from the liquid absorbent core body through a die cutting process or an etching process.

[0012] Furthermore, when the absorbent core body is formed by a material removal processing method, the following steps are included: a. First, a porous copper wet film is prepared by screen printing, the thickness of the wet film is 50-300 μm, and cold isostatically pressed graphite is used as a substrate for forming a porous copper wet film with a copper slurry; b. The wet film formed by the copper slurry and the graphite substrate are sent into a sintering furnace to sinter the porous copper foam at a sintering temperature of 900-1000°C for 1-3 hours in an atmosphere of a hydrogen-nitrogen mixed gas containing 10%-20% hydrogen; c. The obtained porous copper foam metal sheet is die-cut to form a serrated liquid reflux channel, a steam channel and a protrusion, thereby obtaining a liquid absorbent core with a separated steam channel and a separated liquid channel.

[0013] Furthermore, the preparation method of the copper slurry comprises the following steps: The copper powder and the solvent are mixed evenly in a dispersing mixer at a stirring speed of 1000-5000 rpm for 30-60 min, and the temperature is controlled below 35°C. A pore-forming agent is added and dispersed at a speed of 6000-10000 rpm for 5-10 min until the mixture is evenly dispersed. The copper slurry comprises the following components by mass fraction: 60-80% copper powder, 20-35% solvent, and 0-5% pore-forming agent; The mass percentage of the binder PVA in the solvent is 0.5-5%, the mass percentage of the wetting agent PEG wet material is 2-6%, the mass percentage of the thixotropic agent is 3-9%, and the rest is a mixture of one or more of the solvent water, ethanol, glycerol and isopropanol; The thixotropic agent is one or more of polyamide wax, ethyl cellulose and bentonite; The pore-forming agent is one or both of PMMA microspheres and PS microspheres.

[0014] In a third aspect, an embodiment of the present invention provides a vapor chamber, comprising an upper shell plate and a lower shell plate, wherein the upper shell plate and the lower shell plate are sealed and connected at their peripheries to form a sealed working medium chamber, wherein the sealed working medium chamber is in a vacuum state and is filled with a liquid working medium, and a liquid wick is further provided in the sealed working medium chamber; The liquid absorbent core adopts the liquid absorbent core with separated steam channels and liquid channels as described in the first aspect.

[0015] Furthermore, the inner surfaces of the upper shell plate and the lower shell plate are both concave, the inner surface of the upper shell plate is provided with a first support column, the inner surface of the lower shell plate is provided with a second support column, and each of the first support column and the second support column is arranged opposite to each other; The upper surface of the absorbent core is tightly fitted with the lower surface of the upper shell plate, the lower surface of the absorbent core is tightly fitted with the upper surface of the lower shell plate, and the first support column and the second support column are arranged at the steam channel of the absorbent core, and the serrated liquid reflux channel of the absorbent core is located in the gap between adjacent first support columns and second support columns.

[0016] The technical solution provided by the embodiment of the present invention has the following beneficial effects: (1) The steam channel and liquid return channel of the liquid absorbent core of the present invention are designed as coplanar structures, that is, the steam channel and the liquid return channel are in the same plane, which can maximize the height of the steam channel and make it equal to the inner cavity of the heat spreader. This can significantly reduce the resistance during steam transmission and increase the steam transmission rate, which is beneficial to improving the temperature uniformity of the entire heat spreader.

[0017] (2) The steam channel and liquid return channel of the absorbent core of the present invention are designed as coplanar structures. Steam and liquid are transmitted in their respective independent channels, which reduces the problem of conflict between steam gas and the liquid return channel of the absorbent core, and can increase the circulation rate of steam and liquid in the entire heat spreader, thereby improving the overall temperature uniformity of the heat spreader.

[0018] (3) By using a wick with separated steam channels and liquid reflux channels in an ultra-thin heat spreader, it is possible to meet the needs of large-area ultra-thin heat spreaders. For example, the temperature difference between the upper surface of the heat source and the cold end of the upper surface of an ultra-thin heat spreader with a width of 60 mm × a length of 100 mm × a height of 0.3 mm can be controlled within 5°C.

[0019] (4) The wick with separated steam channels and liquid channels of the present invention can be designed with a single hot spot as the evaporation center or with multiple hot spots. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the liquid absorbent core with separated steam channel and liquid channel in an embodiment of the present invention.

[0021] Figure 2 yes Figure 1 Schematic diagram of the application structure of a wick with separated steam channel and liquid channel on a heat spreader.

[0022] Figure 3 1 is a schematic diagram of the structure of a heat spreader with the foam copper liquid absorbing core in Example 1.

[0023] Figure 4 yes Figure 3 Schematic diagram of the structural breakdown of the heat sink.

[0024] Figure 5 1 is a schematic diagram of the structure of a heat spreader with the foam copper liquid absorbing core in Example 2.

[0025] Figure 6 yes Figure 5 Schematic diagram of the structural breakdown of the heat sink.

[0026] Figure 7 Schematic diagram of the structure of a heat spreader with the foam copper liquid wick in Example 3.

[0027] Figure 8 yes Figure 7Schematic diagram of the structural breakdown of the heat sink.

[0028] Fig. 9 It is a schematic diagram of the structure of the heat spreader in the comparative example.

[0029] Explanation of the reference numerals: 1-protrusion; 2-toothed liquid reflux channel; 3-root; 4-free end; 5-steam channel; 6-upper shell plate; 7-lower shell plate; 8-liquid absorption core; 9-solder paste; 61-first support column; 71-second support column. DETAILED DESCRIPTION

[0030] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "inside, outside", "up, down", "left, right", etc. are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention.

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Example 1 A liquid absorbent core with separated steam channels and liquid channels comprises a liquid absorbent core body, one end of the liquid absorbent core body is provided with a protrusion 1, the position of the protrusion 1 corresponds to the chip setting, the other end of the liquid absorbent core body is provided with a plurality of parallel toothed liquid reflux channels 2, each toothed liquid reflux channel 2 has a root 3 fixed to the liquid absorbent core body, and a free end 4 opposite to the root 3, and the gap between adjacent toothed liquid reflux channels 2 forms a steam channel 5.

[0033] The liquid absorbent core body is integrally formed, and the width of the raised portion 1 is smaller than that of the liquid absorbent core body. The raised portion 1 is arranged at the heat source, and functions to store and evaporate the working fluid. The size is the same as the heat source size 18mm×18mm. The non-heat source portion is a coplanar structure of the steam channel 5 and the serrated liquid reflux channel 2 (that is, the steam channel and the liquid reflux channel are in the same plane). The steam channel 5 is a hollow structure, which serves as a steam transmission channel for evaporation at the heat source. The serrated liquid reflux channel 2 contains a liquid absorbent core, which plays a role in transmitting and refluxing the working fluid to the heat source.

[0034] The liquid wick is made of foamed metal copper, the thickness of the liquid wick is 200 μm, the porosity of the liquid wick is 70%, and the pore size is 15 μm.

[0035] The area S1 of the steam channel 5 / the area S2 of the toothed liquid reflux channel 2 = 3:1.

[0036] The size of the protrusion 1 is 18 mm×18 mm. The protrusion 1 and the root 3 of the liquid absorbent core body are continuous and are used for storing and evaporating working fluid.

[0037] The method for preparing the above-mentioned liquid-absorbing core with separated steam channels and liquid channels comprises the following steps: a. A porous copper wet film was prepared by screen printing, with a size of 100 mm × 200 mm and a thickness of 220 μm. Cold isostatically pressed graphite was used as a substrate for the copper slurry to form the wet film; The preparation process of the copper slurry is as follows: copper powder and solvent are mixed uniformly in a dispersing mixer at a stirring speed of 1000 rpm for 30 minutes and the temperature is controlled at 25°C to obtain a copper slurry; a pore-forming agent is added to the copper slurry, and the slurry is dispersed at a high speed of 6000 rpm for 5 minutes and stirred until uniform; According to the mass fraction, the copper slurry includes the following components: 70% copper powder, 28% solvent, and 2% pore-forming agent, wherein the solvent ratio is: 1.5% by mass of binder PVA, 4% by mass of wetting agent PEG wet material, 6% by mass of thixotropic agent, polyamide wax is used, and the rest is isopropyl alcohol, and the pore-forming agent is PMMA microspheres.

[0038] b. The porous copper wet film formed by the copper slurry and the graphite substrate are sent into a sintering furnace to sinter the porous copper foam. The sintering temperature is 950°C, the sintering time is 2h, and the atmosphere is a hydrogen-nitrogen mixed gas, in which the volume fraction of hydrogen is 10%; c. The obtained porous foam copper metal sheet is die-cut to form a serrated liquid reflux channel 2, a steam channel 5 and a protrusion 1, thereby obtaining a liquid absorbent core with a multi-steam channel and multi-liquid channel separation structure.

[0039] like Figure 3 and 4 As shown, a heat spreader has the dimensions of: width 60 mm×length 100 mm×height 0.3 mm, including an upper shell plate 6 and a lower shell plate 7, and both the upper shell plate 6 and the lower shell plate 7 are made of a copper plate with a thickness of 50 μm; The upper shell plate 6 and the lower shell plate 7 are sealed and connected by solder paste 9 to form a sealed working medium cavity. The sealed working medium cavity is in a vacuum state and is filled with liquid working medium. A liquid wick 8 is also provided in the sealed working medium cavity. The liquid absorbent core 8 adopts the above-mentioned liquid absorbent core with separated steam channel and liquid channel; The inner surfaces of the upper shell plate 6 and the lower shell plate 7 are both concave surfaces. The inner surface of the upper shell plate 6 is provided with a first support column 61, and the inner surface of the lower shell plate 7 is provided with a second support column 71. The first support column 61 and the second support column 71 are arranged opposite to each other. The upper surface of the absorbent core 8 is tightly fitted with the lower surface of the upper shell plate 6, the lower surface of the absorbent core 8 is tightly fitted with the upper surface of the lower shell plate 32, and the first support column 61 and the second support column 71 are arranged at the steam channel 5 of the absorbent core 8, and the serrated liquid reflux channel 2 of the absorbent core 8 is located in the gap between the adjacent first support columns 61 and the second support columns 71.

[0040] The above-mentioned heat spreader can meet the temperature equalization requirement of the heat source power of 5-8W, and the temperature difference between the upper surface of the heat source of the heat spreader and the cold end of the upper surface can be controlled within 5°C.

[0041] Example 2 A liquid absorbent core with separated steam channels and liquid channels comprises a liquid absorbent core body, one end of the liquid absorbent core body is provided with a protrusion 1, the position of the protrusion 1 corresponds to the chip setting, the other end of the liquid absorbent core body is provided with a plurality of parallel toothed liquid reflux channels 2, each toothed liquid reflux channel 2 has a root 3 fixed to the liquid absorbent core body, and a free end 4 opposite to the root 3, and the gap between adjacent toothed liquid reflux channels 2 forms a steam channel 5.

[0042] The liquid absorbent core body is integrally formed, and the width of the raised portion 1 is smaller than that of the liquid absorbent core body. The raised portion 1 is arranged at the heat source, and functions to store and evaporate the working fluid. The size is the same as the heat source size 18mm×18mm. The non-heat source portion is a coplanar structure of the steam channel 5 and the serrated liquid reflux channel 2 (that is, the steam channel and the liquid reflux channel are in the same plane). The steam channel 5 is a hollow structure, which serves as a steam transmission channel for evaporation at the heat source. The serrated liquid reflux channel 2 contains a liquid absorbent core, which plays a role in transmitting and refluxing the working fluid to the heat source.

[0043] The absorbent core is made of foamed metal copper, the thickness of the absorbent core is 160 μm, the porosity of the absorbent core is 75%, and the pore size is 10 μm.

[0044] The area S1 of the steam channel 5 / the area S2 of the toothed liquid reflux channel 2 = 4:1.

[0045] The size of the protrusion 1 is 18 mm×18 mm. The protrusion 1 and the root 3 of the liquid absorbent core body are continuous and are used for storing and evaporating working fluid.

[0046] The method for preparing the above-mentioned liquid-absorbing core with separated steam channels and liquid channels comprises the following steps: a. A porous copper wet film was prepared by screen printing, with a size of 100 mm × 200 mm and a thickness of 180 μm. Cold isostatically pressed graphite was used as a substrate for the copper slurry to form the wet film; The preparation process of the copper slurry is as follows: copper powder and solvent are mixed uniformly in a dispersing mixer at a stirring speed of 1500 rpm for 30 minutes and the temperature is controlled at 25° C. to obtain a copper slurry; a pore-forming agent is added to the copper slurry, and the mixture is dispersed at a high speed of 10000 rpm for 5 minutes and stirred until uniform; The copper slurry comprises the following components by mass fraction: 75% copper powder, 24.5% solvent, and 0.5% pore-forming agent, wherein the solvent ratio is: 0.5% by mass percentage of binder PVA, 3% by mass percentage of wetting agent PEG wet material, 4% by mass percentage of thixotropic agent, polyamide wax is used, and the rest is solvent water, and the pore-forming agent is PMMA microspheres; b. The wet film formed by the copper slurry and the graphite substrate are sent into a sintering furnace to sinter the porous copper foam. The sintering temperature is 930°C, the sintering time is 2h, and the atmosphere is a hydrogen-nitrogen mixed gas, in which the volume fraction of hydrogen is 10%; c. The obtained porous foam copper metal sheet is die-cut to form a serrated liquid reflux channel 2, a steam channel 5 and a protrusion 1, so as to obtain a liquid absorbent core with a separation structure of multiple steam channels and multiple liquid channels.

[0047] like Figure 5 and 6 As shown, a heat spreader has the dimensions of: width 60 mm×length 100 mm×height 0.3 mm, including an upper shell plate 6 and a lower shell plate 7, and both the upper shell plate 6 and the lower shell plate 7 are made of a copper plate with a thickness of 70 μm; The upper shell plate 6 and the lower shell plate 7 are sealed and connected by solder paste 9 to form a sealed working medium cavity. The sealed working medium cavity is in a vacuum state and is filled with liquid working medium. A liquid wick 8 is also provided in the sealed working medium cavity. The liquid absorbent core 8 adopts the above-mentioned liquid absorbent core with separated steam channel and liquid channel; The inner surfaces of the upper shell plate 6 and the lower shell plate 7 are both concave surfaces. The inner surface of the upper shell plate 6 is provided with a first support column 61, and the inner surface of the lower shell plate 7 is provided with a second support column 71. The first support column 61 and the second support column 71 are arranged opposite to each other. The upper surface of the absorbent core 8 is tightly fitted with the lower surface of the upper shell plate 6, the lower surface of the absorbent core 8 is tightly fitted with the upper surface of the lower shell plate 32, and the first support column 61 and the second support column 71 are arranged at the steam channel 5 of the absorbent core 8, and the serrated liquid reflux channel 2 of the absorbent core 8 is located in the gap between the adjacent first support columns 61 and the second support columns 71.

[0048] The above-mentioned heat spreader can meet the temperature equalization requirement of the heat source power of 5-8W, and the temperature difference between the upper surface of the heat source of the heat spreader and the cold end of the upper surface can be controlled within 3°C.

[0049] Example 3 A liquid absorbent core with separated steam channels and liquid channels comprises a liquid absorbent core body, one end of the liquid absorbent core body is provided with a protrusion 1, the position of the protrusion 1 corresponds to the chip setting, the other end of the liquid absorbent core body is provided with a plurality of parallel toothed liquid reflux channels 2, each toothed liquid reflux channel 2 has a root 3 fixed to the liquid absorbent core body, and a free end 4 opposite to the root 3, and the gap between adjacent toothed liquid reflux channels 2 forms a steam channel 5.

[0050] The liquid absorbent core body is integrally formed, and the width of the raised portion 1 is smaller than that of the liquid absorbent core body. The raised portion 1 is arranged at the heat source, and functions to store and evaporate the working fluid. The size is the same as the heat source size 18mm×18mm. The non-heat source portion is a coplanar structure of the steam channel 5 and the serrated liquid reflux channel 2 (that is, the steam channel and the liquid reflux channel are in the same plane). The steam channel 5 is a hollow structure, which serves as a steam transmission channel for evaporation at the heat source. The serrated liquid reflux channel 2 contains a liquid absorbent core, which plays a role in transmitting and refluxing the working fluid to the heat source.

[0051] The liquid wick is made of foamed metal copper, the thickness of the liquid wick is 200 μm, the porosity of the liquid wick is 65%, and the pore size is 20 μm.

[0052] The area S1 of the steam channel 5 / the area S2 of the toothed liquid reflux channel 2 = 3:1.

[0053] The size of the protrusion 1 is 18 mm×18 mm. The protrusion 1 and the root 3 of the liquid absorbent core body are continuous and are used for storing and evaporating working fluid.

[0054] The method for preparing the above-mentioned liquid-absorbing core with separated steam channels and liquid channels comprises the following steps: a. First, a porous copper wet film is prepared by screen printing, with a size of 100 mm × 200 mm and a thickness of 220 μm, and cold isostatically pressed graphite is used as a substrate for the copper slurry to form the wet film; The preparation process of the copper slurry is as follows: the copper powder and the solvent are mixed evenly in a disperser at a stirring speed of 2000 rpm for 30 minutes and the temperature is controlled at 25°C to obtain the copper slurry; a pore-forming agent is added to the copper slurry, and the slurry is dispersed at a high speed of 8000 rpm for 5 minutes and stirred until it is uniform.

[0055] The copper slurry comprises the following components by mass fraction: 77% copper powder, 22.5% solvent, and 0.5% pore former, wherein the solvent ratio is: 0.5% by mass of binder PVA, 3% by mass of wetting agent PEG wet material, 6% by mass of thixotropic agent, polyamide wax is used, and the rest is solvent water, and the pore former is PMMA microspheres; b. The wet film formed by the copper slurry and the graphite substrate are sent into a sintering furnace to sinter the porous copper foam. The sintering temperature is 1000°C, the sintering time is 1 hour, and the atmosphere is a hydrogen-nitrogen mixed gas with 10% hydrogen.

[0056] c. The obtained porous copper foam metal sheet is die-cut to form a toothed liquid reflux channel 2, a steam channel 5 and a protrusion 1, so as to obtain a liquid absorbent core with a multi-steam channel and multi-liquid channel separation structure.

[0057] like Figure 7 and 8 As shown, a heat spreader has the dimensions of: width 60 mm×length 100 mm×height 0.3 mm, including an upper shell plate 6 and a lower shell plate 7, and both the upper shell plate 6 and the lower shell plate 7 are made of a copper plate with a thickness of 50 μm; The upper shell plate 6 and the lower shell plate 7 are sealed and connected by solder paste 9 to form a sealed working medium cavity. The sealed working medium cavity is in a vacuum state and is filled with liquid working medium. A liquid wick 8 is also provided in the sealed working medium cavity. The liquid absorbent core 8 adopts the above-mentioned liquid absorbent core with separated steam channel and liquid channel; The inner surfaces of the upper shell plate 6 and the lower shell plate 7 are both concave surfaces. The inner surface of the upper shell plate 6 is provided with a first support column 61, and the inner surface of the lower shell plate 7 is provided with a second support column 71. The first support column 61 and the second support column 71 are arranged opposite to each other. The upper surface of the absorbent core 8 is tightly fitted with the lower surface of the upper shell plate 6, the lower surface of the absorbent core 8 is tightly fitted with the upper surface of the lower shell plate 32, and the first support column 61 and the second support column 71 are arranged at the steam channel 5 of the absorbent core 8, and the serrated liquid reflux channel 2 of the absorbent core 8 is located in the gap between the adjacent first support columns 61 and the second support columns 71.

[0058] The above-mentioned heat spreader can meet the temperature equalization requirement of the heat source power of 5-8W, and the temperature difference between the upper surface of the heat source of the heat spreader and the cold end of the upper surface can be controlled within 5°C.

[0059] Comparative Example like Fig. 9 As shown, a heat spreader has the dimensions of: width 60 mm×length 100 mm×height 0.3 mm, including an upper shell plate 6 and a lower shell plate 7, both of which are made of a copper plate with a thickness of 50 μm, and the height of the steam channel is 130 μm; The upper shell plate 6 and the lower shell plate 7 are sealed and connected by solder paste 9 to form a sealed working medium cavity. The sealed working medium cavity is in a vacuum state and is filled with liquid working medium. A liquid wick 8 is also provided in the sealed working medium cavity. The inner surfaces of the upper shell plate 6 and the lower shell plate 7 are both concave. The inner surface of the upper shell plate 6 is provided with a first support column 61. The upper surface of the absorbent core 8 is tightly fitted with the free end of the first support column 61, and the lower surface of the absorbent core 8 is tightly fitted with the upper surface of the lower shell plate 7.

[0060] The liquid wick 8 uses a 250-mesh two-dimensional metal copper mesh with a wire diameter of 0.04 mm and a copper mesh thickness of 70 μm. The porosity of the liquid wick is 52% and the pore size is 60 μm.

[0061] When the heat source power is 5W, the temperature difference between the upper surface of the heat source of the above-mentioned vapor chamber and the cold end of the upper surface is more than 10°C, and the requirement of 5°C temperature difference on the upper surface cannot be achieved.

[0062] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A liquid absorbent core with separated steam channels and liquid channels, characterized in that: The invention comprises a liquid absorbent core body, wherein a protrusion (1) is arranged at one end of the liquid absorbent core body, and the position of the protrusion (1) corresponds to the chip arrangement; a plurality of parallel toothed liquid reflux channels (2) are arranged at the other end of the liquid absorbent core body, and each of the toothed liquid reflux channels (2) has a root (3) fixed to the liquid absorbent core body, and a free end (4) opposite to the root (3); and the gaps between adjacent toothed liquid reflux channels (2) form a steam channel (5).

2. The absorbent core with separated vapor channel and liquid channel according to claim 1, characterized in that: The liquid absorbent core body is integrally formed, and the width of the protrusion (1) is smaller than the width of the liquid absorbent core body.

3. The absorbent core with separated vapor channel and liquid channel according to claim 1, characterized in that: The liquid wick is made of multi-layer metal mesh, foam metal, composite of foam metal and metal mesh, and composite of metal mesh and metal powder. The liquid wick has a thickness of 40-200 μm, a porosity of 60%-80%, and a pore size of 10-25 μm.

4. The absorbent core with separated vapor channel and liquid channel according to claim 1, characterized in that: The area S1 of the steam channel (5) / the area S2 of the toothed liquid reflux channel (2)=5:1-1:

1.

5. The absorbent core with separated vapor channel and liquid channel according to claim 1, characterized in that: The size of the protrusion (1) is 10 mm×10 mm-20 mm×20 mm, and the protrusion (1) and the root (3) of the liquid absorbent core body are continuous, and are used for storing and evaporating working fluid.

6. The method for preparing the absorbent core with separated vapor channel and liquid channel according to any one of claims 1 to 5, characterized in that: The wick body is formed by a material removal process, or formed by a slurry in-situ forming process and then sintered, or formed by 3D printing; During the molding process of the material removal processing method, material is removed from the liquid absorbent core body through a die cutting process or an etching process to form the steam channel (5).

7. The method for preparing the absorbent core with separated vapor channel and liquid channel according to claim 6, characterized in that: When the absorbent core body is formed by a material removal processing method, the following steps are included: a. First, a porous copper wet film is prepared by screen printing, the thickness of the wet film is 50-300 μm, and cold isostatically pressed graphite is used as a substrate for forming a porous copper wet film with a copper slurry; b. The wet film formed by the copper slurry and the graphite substrate are sent into a sintering furnace to sinter the porous copper foam at a sintering temperature of 900-1000°C for 1-3 hours in an atmosphere of a hydrogen-nitrogen mixed gas containing 10%-20% hydrogen; c. The obtained porous copper foam metal sheet is die-cut to form a toothed liquid reflux channel (2), a steam channel (5) and a protrusion (1), thereby obtaining a liquid absorbent core with a separated steam channel and a separated liquid channel.

8. The method for preparing the absorbent core with separated vapor channel and liquid channel according to claim 7, characterized in that: The preparation method of the copper slurry comprises the following steps: The copper powder and the solvent are mixed evenly in a dispersing mixer at a stirring speed of 1000-5000 rpm for 30-60 min, and the temperature is controlled below 35°C. A pore-forming agent is added and dispersed at a speed of 6000-10000 rpm for 5-10 min until the mixture is evenly dispersed. The copper slurry comprises the following components by mass fraction: 60-80% copper powder, 20-35% solvent, and 0-5% pore-forming agent; The mass percentage of the binder PVA in the solvent is 0.5-5%, the mass percentage of the wetting agent PEG wet material is 2-6%, the mass percentage of the thixotropic agent is 3-9%, and the rest is a mixture of one or more of the solvent water, ethanol, glycerol and isopropanol; The thixotropic agent is one or more of polyamide wax, ethyl cellulose and bentonite; The pore-forming agent is one or both of PMMA microspheres and PS microspheres.

9. A heat spreader, characterized in that: It comprises an upper shell plate (6) and a lower shell plate (7), wherein the upper shell plate (6) and the lower shell plate (7) are connected in a sealed manner at their peripheries to form a sealed working medium cavity, wherein the sealed working medium cavity is in a vacuum state and is filled with a liquid working medium, and a liquid wick (8) is also provided in the sealed working medium cavity; The liquid absorbent core (8) adopts the liquid absorbent core with separated steam channels and liquid channels as described in any one of claims 1 to 5.

10. The vapor chamber according to claim 9, characterized in that: The inner surfaces of the upper shell plate (6) and the lower shell plate (7) are both concave surfaces, the inner surface of the upper shell plate (6) is provided with a first support column (61), and the inner surface of the lower shell plate (7) is provided with a second support column (71), and each of the first support column (61) and the second support column (71) is arranged opposite to each other; The upper surface of the absorbent core (8) is tightly fitted with the lower surface of the upper shell plate (6), and the lower surface of the absorbent core (8) is tightly fitted with the upper surface of the lower shell plate (32). The first support column (61) and the second support column (71) are arranged at the steam channel (5) of the absorbent core (8), and the toothed liquid reflux channel (2) of the absorbent core (8) is located in the gap between the adjacent first support column (61) and the second support column (71).

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