Capillary structure for vapor chamber and preparation method therefor, and vapor chamber

Abstract

The present invention relates to the technical field of vapor chambers, and provides a capillary structure for a vapor chamber and a preparation method therefor, and a vapor chamber. The preparation method for the capillary structure comprises: providing copper paste having a preset porosity and a template material having a regular structure; coating a substrate with the template material and the copper paste, and carrying out drying and sintering treatment; and removing the template material in a dissolution or high-temperature decomposition mode to obtain a capillary structure having a regular channel. The preparation method of the present invention is simple, the obtained capillary structure has a regular channel, the thickness is controllable, the structure size is controllable, the capillary effect is excellent, and the capillary structure can be applied to the vapor chamber to obtain an ultrathin vapor chamber.

Description

Capillary structure for temperature averaging plate and preparation method thereof, temperature averaging plate Technical Field

[0001] The present invention belongs to the technical field of temperature averaging plates, and in particular relates to a capillary structure for a temperature averaging plate, a preparation method thereof, and a temperature averaging plate. Background Art

[0002] The high-frequency and high-speed development of electronic components and integrated circuit technology has led to the generation of large amounts of heat during the operation of electronic components. For example, the heat flux density of a computer CPU during operation has reached 60 to 100 W / cm 2 , and even as high as 10 in semiconductor lasers 3 W / cm 2 The reliability of electronic equipment is extremely sensitive to temperature. When the device temperature increases by 1°C above 70-80°C, the reliability will decrease by 5%. High heat flow poses a great threat to the reliability of the normal operation of components, so heat dissipation has become a key issue in the miniaturization of electronic products. In order to ensure the normal operation of electronic components, a heat sink is usually installed on the electronic components to dissipate heat. At the same time, a heat spreader with good thermal conductivity is installed between the heat sink and the electronic components. The function of the heat spreader is to evenly distribute the heat of the heat-generating electronic components and then dissipate it through the heat sink.

[0003] A vapor chamber is a thermally conductive component that achieves rapid heat transfer through phase changes in its internal working fluid. It primarily consists of upper and lower covers or metal tubes, a sealing head, a wick, and a heat transfer medium. The wick's capillary structure directly impacts the vapor chamber's performance, requiring strong capillary forces and minimal flow resistance.

[0004] Secondly, as electronic products continue to develop in the direction of miniaturization, the size of other components is required to become smaller and thinner, which makes the thickness of the heat spreader more stringent. Ultra-thin heat spreaders with a thickness of less than 280 μm (for example, 240 μm) came into being. Ultra-thin heat spreaders require thinner liquid wicks while ensuring heat transfer performance. Liquid wicks with a thickness of 80 μm or even 50 μm are on the agenda.

[0005] Currently, a wide variety of wicks are available for vapor chambers, including copper foam, copper mesh, composite copper mesh, and etched capillary structures. However, these wicks are expensive to produce, involve complex manufacturing processes, and are often marketed at high prices. Furthermore, the inherent thickness of wicks like copper foam, copper mesh, and composite copper mesh limits the development of thinner vapor chambers. Alternatively, capillary structures can be formed using copper paste screen printing, but these capillary structures exhibit high mass transfer resistance, resulting in poor heat transfer performance for vapor chambers. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art, and provides a capillary structure for a temperature equalizing plate, a preparation method thereof, and a temperature equalizing plate.

[0007] In one aspect of the present invention, a method for preparing a capillary structure for a temperature vapor chamber is provided, the method comprising:

[0008] Providing a copper paste with a preset porosity and a template material with a regular structure;

[0009] The template material and the copper paste are coated on a temperature-equalizing plate, and dried and sintered;

[0010] The template material is removed by dissolving or high-temperature decomposition to obtain a capillary structure with regular channels.

[0011] Optionally, the step of coating both the template material having a regular structure and the copper paste on the substrate includes:

[0012] Laying the template material on the substrate to form a template layer;

[0013] The copper paste is coated on the template layer by coating or printing.

[0014] Optionally, the step of coating both the template material having a regular structure and the copper paste on the substrate includes:

[0015] mixing the template material with the copper slurry to form a mixed slurry;

[0016] The mixed slurry is coated on the substrate by coating or printing.

[0017] Optionally, the template material is any one of polymer braid, whisker, and porous foam; and / or,

[0018] The diameter of the template material ranges from 1 μm to 1 mm.

[0019] Optionally, the polymer braid is made of one or more of nylon, polyurethane, polyester, nylon, acrylic, polypropylene, etc.; and / or,

[0020] The whiskers are organic whiskers or inorganic whiskers; and / or,

[0021] The porous foam material is one or more of polyurethane foam, polypropylene foam, polyethylene foam, PVC foam, EVA foam, and melamine foam.

[0022] Optionally, the drying temperature range is 80-150° C., and the drying time range is 5-180 min; and / or,

[0023] The sintering temperature ranges from 300° C. to 850° C., and the sintering time ranges from 10 min to 480 min.

[0024] Optionally, the copper slurry includes copper powder, a pore-forming agent, a binder and a solvent.

[0025] Optionally, the copper powder has a mass fraction of 30-95% and a particle size range of 50 nm-200 μm; and / or,

[0026] The mass fraction of the pore-forming agent is 0-85%, and the particle size range is 500 nm-100 μm; and / or,

[0027] The mass fraction of the binder is 1-20%.

[0028] Another aspect of the present invention provides a capillary structure for a temperature homogenizing plate, which is manufactured using the aforementioned preparation method.

[0029] Another aspect of the present invention provides a temperature averaging plate, comprising an upper cover plate, a lower cover plate, and a capillary structure, wherein:

[0030] The capillary structure is located between the upper cover plate and the lower cover plate, and the capillary structure adopts the capillary structure described above.

[0031] The present invention provides a capillary structure for a temperature homogenizing plate, a preparation method thereof, and a temperature homogenizing plate, which have the following beneficial effects compared to the prior art:

[0032] 1. Compared with other types of wicks, such as copper wire, copper mesh, composite copper mesh, and foam copper, the preparation method of the present invention is simple. The capillary structure obtained by the method of the present invention has regular channels, controllable thickness and structure size, and excellent capillary effect. At the same time, the capillary structure can be applied to a temperature equalizing plate to obtain an ultra-thin temperature equalizing plate.

[0033] 2. Compared with the copper paste screen printing method, the method of the present invention forms a capillary structure with regular channels, has lower mass transfer resistance, and greatly improves the heat transfer performance of the temperature equalizing plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a flow chart of the method for preparing a capillary structure according to the present invention. DETAILED DESCRIPTION

[0035] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It is apparent that the described embodiments are only a portion of the embodiments of the present invention, rather than all of them. Based on the described embodiments of the present invention, all other embodiments derived by those skilled in the art without requiring creative effort are intended to fall within the scope of protection of the present invention.

[0036] As shown in FIG1 , one aspect of the present invention provides a method S100 for preparing a capillary structure for a vapor chamber, comprising steps S110 to S130 :

[0037] S110 , providing a copper paste with a preset porosity and a template material with a regular structure.

[0038] Specifically, a copper paste with a certain preset porosity (for example, a porosity of 30-90%) is first prepared. The copper paste should have the following characteristics: a certain particle size range, copper powder with a certain fixed morphology, a pore-forming agent with a certain particle size range, etc., to meet the porosity requirements of the capillary structure.

[0039] Illustratively, the copper paste includes copper powder, a pore former, a binder, and a solvent.

[0040] In some preferred embodiments, the mass fraction of the copper powder is 30-95%, the copper powder is submicron-grade, the particle size range is 50 nm-200 μm, the purity is ≥90%, and the particle morphology of the copper powder can be spherical, dendritic, or irregular small sintered blocks, etc., without specific limitation.

[0041] In other preferred embodiments, the mass fraction of the pore-forming agent is 0-85%, the particle size of the pore-forming agent ranges from 5 nm to 100 μm, and the pore-forming agent is mainly one or more of organic small molecule particles, polymer powders or inorganic salts, for example, one or more of ammonium chloride, urea, ammonium sulfate, citric acid and benzoic acid, and the particle shape can be spherical or irregular.

[0042] In this embodiment, the pore-forming agent undergoes volatilization or decomposition reactions during the sintering process to form pores in the capillary structure, which can further increase the porosity of the capillary structure, increase its capillary suction force, and further improve the water absorption and heat transfer performance of the capillary structure.

[0043] In other preferred embodiments, the mass fraction of the binder is 1-20%, and the binder is one or more of acrylic resins, epoxy resins, phenolic resins, etc.

[0044] In this embodiment, the binder plays the role of bonding the copper powder, the pore-forming agent and the template material, and makes them strongly adhere to the temperature-homogenizing plate to prevent the powder from falling off after drying.

[0045] In other preferred embodiments, the solvent is one or more of toluene, xylene, terpineol, acetone, ethanol, and the like.

[0046] In this embodiment, the solvent plays the role of dissolving the binder, dispersing the copper powder, and the pore-forming agent, and works together with the binder to disperse and suspend the powder particles uniformly and stably to form a slurry.

[0047] Furthermore, the template material is a material that can be decomposed into small molecules by high temperature, or is more easily soluble in acid, alkali or other solvents to facilitate its removal, and the template material has a regular structure. By decomposing or dissolving the template material, the regular structure of the template material forms a regular channel of the capillary structure.

[0048] It should be understood that since the regular structure of the template material forms a regular channel of the capillary structure, in this embodiment, the template material is preferably a material with a regular structure, such as a polymer braid, whiskers or porous foam. Of course, other template materials with a regular structure can also be selected, and there is no specific limitation on this. The diameter range of the template material is 1 μm to 1 mm; wherein, when whiskers are used as the template material, the aspect ratio of the whiskers is ≥10, so that the formed capillary structure has a good capillary effect.

[0049] In some preferred embodiments, the polymer fabric can be one or more of nylon, polyurethane, polyester, nylon, acrylic, polypropylene, etc., and can be woven from warps and wefts of different thicknesses and different numbers, and the woven warps and wefts give it a unique regular structure.

[0050] In other preferred embodiments, the whisker template material includes organic whiskers and inorganic whiskers, wherein the organic whiskers can be one or more of cellulose whiskers, poly(butyl acrylate-styrene) whiskers, poly(4-hydroxybenzyl ester) whiskers (PHB whiskers), etc.; the inorganic whiskers can be one or more of calcium carbonate whiskers, calcium sulfate whiskers, aluminum oxide whiskers, zinc oxide whiskers, potassium titanate whiskers, etc., which have a certain aspect ratio structure, a specific cross-section, and a stable size to form regular channels of the capillary structure.

[0051] In other preferred embodiments, the porous foam material can be one or more of polyurethane foam, polypropylene foam, polyethylene foam, PVC foam, EVA foam, melamine foam, etc., and is formed by many irregularly arranged and interconnected pores to form regular channels of a capillary structure.

[0052] S120, coating the template material and the copper paste on a temperature-equalizing plate, and performing drying and sintering treatments.

[0053] Specifically, the template material and copper paste are coated on a heat spreader, and the heat spreader coated with the template material and copper paste is placed in an oven with a temperature range of 80~150℃ and dried for 5~180 minutes to allow the solvent to evaporate completely, forming a dry material that is firmly attached to the heat spreader.

[0054] Furthermore, the dried heat absorbing plate is placed in a sintering furnace, and the sintering temperature is set to 300~850℃ and the time is 10~480 minutes to fully debind and sinter it so that the capillary structure is well attached to the heat absorbing plate. The atmosphere used for sintering can be air, N2, H2 and their mixed gases, etc., and there is no specific limitation on this.

[0055] It should be noted that the temperature equalizer includes an upper cover and a lower cover. Generally speaking, the capillary structure is located on the upper cover. Therefore, in the preparation method of this embodiment, the template material with a regular structure and the copper paste can be coated on the upper cover of the temperature equalizer.

[0056] It should be further explained that, in this embodiment, there is no specific limitation on the form in which the template material and the copper paste are coated on the temperature equalizing plate. The template material can be coated on the temperature equalizing plate first, and then the copper paste is coated on the temperature equalizing plate. Alternatively, the copper paste and the template material can be mixed and then coated together on the temperature equalizing plate. In other words, as long as the template material and the copper paste are coated together on the temperature equalizing plate, the regular structure of the template material forms a regular channel after drying and sintering.

[0057] In some preferred embodiments, the template material is laid on a temperature-maintaining plate to form a template layer; then, copper paste is coated on the template layer by coating or printing (for example, screen printing), the temperature-maintaining plate is placed in an oven for drying to evaporate the solvent, and then placed in a sintering furnace for sintering, so that the regular structure of the template material serves as a regular channel.

[0058] In other embodiments, the template material is mixed with copper paste to form a mixed slurry; the mixed slurry is coated on the substrate by coating or printing, and is dried and sintered to make the regular structure of the template material serve as a regular channel.

[0059] S130, removing the template material by dissolving or pyrolysis to obtain a capillary structure with regular channels, wherein the width of the regular channels in the capillary structure is the same as the diameter of the template material.

[0060] It should be noted that when the template material is removed by high-temperature decomposition, the high-temperature decomposition process of the template material can be carried out simultaneously with the sintering in step S120. That is, when the temperature equalizing plate is placed in the sintering furnace for sintering, the template material is completely decomposed by high-temperature volatilization at the sintering temperature to achieve the removal of the template material.

[0061] It should be further explained that when the template material is removed by dissolution, there is no specific limitation on the order of implementation of the dissolution and sintering steps. The sintering process can be carried out first and then the template material can be removed by dissolution, or the template material can be removed by dissolution first and then the sintering process can be carried out. In other words, the dissolution process of the template material can occur before the sintering process or after the sintering process.

[0062] For example, when the template material is organic whiskers or inorganic whiskers, the whisker template material can be dissolved by acid, alkali or other solvents after drying and before sintering, and then a capillary structure with regular channels is prepared by sintering; or the whiskers can be removed during the high-temperature sintering process; or the whiskers can be dissolved by acid, alkali or other solvents after high-temperature sintering.

[0063] In some preferred embodiments, the acid for dissolving the template material may be hydrochloric acid, nitric acid, sulfuric acid, etc. Of course, other acid solutions may also be selected.

[0064] In other preferred embodiments, the alkali for dissolving the template material may be one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. Of course, other alkali solutions may also be selected.

[0065] In other preferred embodiments, other solvents for dissolving the template material may be one or more of water, ethanol, acetone, ethyl acetate, copper butylate, tetrahydrofuran, formic acid, methanol, dichloromethane or chloroform, and are not limited to the solvents described above.

[0066] In the preparation method provided in this embodiment, regular channels are provided by a template material with a regular structure, and the porosity of the capillary structure is increased by a pore-forming agent in the copper slurry. The copper slurry forms the main skeleton of the capillary structure, and its thickness, structural size, and capillary effect are excellent. This structure can not only greatly improve the capillary suction of the capillary structure, but also greatly reduce the flow resistance of the working fluid in the capillary structure, and can greatly improve the water absorption and heat transfer performance of the capillary structure.

[0067] Another aspect of the present invention provides a capillary structure for a temperature homogenizing plate. The capillary structure is manufactured using the method described above. For the specific method, please refer to the above description and will not be repeated here.

[0068] In this embodiment, the capillary structure has a regular channel with a width ranging from 1 μm to 1 mm. The porosity of the capillary structure ranges from 30% to 90%, and it has the characteristics of a three-dimensional interconnected pore structure. It can greatly reduce the flow resistance of the working fluid in the capillary structure, improve the heat transfer performance of the heat spreader, and can be applied to ultra-thin heat spreaders.

[0069] Another aspect of the present invention provides a temperature averaging plate, which includes an upper cover plate, a lower cover plate, and the capillary structure described above. The capillary structure has regular channels, wherein the capillary structure is located between the upper cover plate and the lower cover plate.

[0070] The following is a further explanation of the method for preparing the capillary structure for the temperature equalization plate with reference to several specific examples: Example 1

[0071] The method for preparing the capillary structure in this example includes the following steps:

[0072] S1. Use a 30 μm-wide polyester woven fabric as a template material. Cut the template material into a certain size and fix it to the upper cover of the temperature-isolating plate. Prepare a 30% PMMA ethanol solution, add 50% submicron spherical copper powder and 20% urea powder, and stir thoroughly to form a copper slurry. Apply the copper slurry to the upper cover of the temperature-isolating plate by coating or screen printing. Then place it in an oven at 90-120°C for 5-120 minutes to dry out the solvent.

[0073] S2. The upper cover plate is placed in a solvent, such as formic acid, methanol, dichloromethane or chloroform, to fully dissolve the template material. The upper cover plate is then placed in a sintering furnace for sintering to obtain an upper cover plate with a capillary structure.

[0074] S3. The upper cover plate with the capillary structure is bonded to the lower cover plate by soldering paste to finally obtain a finished temperature homogenizing plate, and the temperature difference between the cold end and the hot end thereof is tested.

[0075] As shown in Table 1, the temperature difference between the cold end and the hot end of the temperature vapor chamber prepared in Example 1 is 1.5° C., which indicates that the temperature vapor chamber of this embodiment has good thermal conductivity. Example 2

[0076] The method for preparing the capillary structure in this example includes the following steps:

[0077] S1. Use a 100 μm-wide polyester woven fabric as a template material. Cut the template material into a certain size and fix it to the temperature-isolating plate. Prepare a 30% PMMA ethanol solution, add 50% submicron spherical copper powder and 20% NH4Cl powder, and stir thoroughly to form a copper slurry. Apply this copper slurry to the upper cover of the temperature-isolating plate by coating or screen printing. Then, place the upper cover in an oven at 90-120°C for 5-120 minutes to dry out the solvent.

[0078] S2. Place the upper cover plate in a solvent, such as formic acid, methanol, dichloromethane, or chloroform, to fully dissolve the template material. Then place the upper cover plate in a sintering furnace for sintering to obtain a cover plate with a capillary structure.

[0079] S3. The upper cover plate with the capillary structure is bonded to the lower cover plate by soldering paste to finally obtain a finished temperature homogenizing plate, and the temperature difference between the cold end and the hot end thereof is tested.

[0080] As shown in Table 1, the temperature difference between the cold end and the hot end of the temperature vapor chamber prepared in Example 2 is 0.8° C., which indicates that the temperature vapor chamber of this example has good thermal conductivity. Example 3

[0081] The method for preparing the capillary structure in this example includes the following steps:

[0082] S1. Use calcium carbonate whiskers with an aspect ratio of 30 as the template material; prepare a 30% PMMA ethanol solution, add 50% submicron spherical copper powder and 20% NH4Cl powder, and stir thoroughly to form a copper slurry. Place the calcium carbonate whiskers into the copper slurry and mix thoroughly. Apply the copper slurry to the upper cover of the above-mentioned temperature-stabilizing plate by coating. Then, bake in an oven at 90-120°C for 5-120 minutes to dry out the solvent.

[0083] S2. Place the upper cover plate in a sintering furnace for sintering; finally place it in an acid solution to fully dissolve the template material, thereby obtaining a cover plate with a capillary structure.

[0084] S3. The upper cover plate with the capillary structure is bonded to the lower cover plate by soldering paste to finally obtain a finished temperature homogenizing plate, and the temperature difference between the cold end and the hot end thereof is tested.

[0085] As shown in Table 1, the temperature difference between the cold end and the hot end of the temperature vapor chamber prepared in Example 3 is 1.1° C., which indicates that the temperature vapor chamber of this embodiment has good thermal conductivity.

[0086] Table 1 Temperature difference test results of Examples 1-3

[0087] Test Example 1 Example 2 Example 3 Average temperature difference 1.5℃ 0.8℃ 1.1℃

[0088] In summary, the temperature difference of the heat spreader prepared in the above embodiments is within 2° C., and the heat spreader has good heat conduction effect and fast startup speed.

[0089] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the essence of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A preparation method for a capillary structure of a heat pipe, characterized in that, The preparation method includes: providing a copper paste with a preset porosity and a template material with a regular structure; coating the template material and the copper paste on a heat pipe, and performing drying and sintering treatments; removing the template material by dissolution or high-temperature decomposition to obtain a capillary structure with regular channels.

2. The preparation method according to claim 1, characterized in that, Coating the template material with a regular structure and the copper paste on a substrate includes: laying the template material on the substrate to form a template layer; coating the copper paste on the template layer by coating or printing.

3. The preparation method according to claim 1, characterized in that, Coating the template material with a regular structure and the copper paste on a substrate includes: mixing the template material and the copper paste to form a mixed slurry; coating the mixed slurry on the substrate by coating or printing.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The template material is any one of a polymer fabric, whiskers, and porous foam; and / or, the diameter range of the template material is 1 μm to 1 mm.

5. The preparation method according to claim 4, characterized in that, The polymer fabric is made of one or more of nylon, polyurethane, polyester, polyamide, acrylic, polypropylene, etc.; and / or, the whiskers are organic whiskers or inorganic whiskers; and / or, the porous foam material is made of one or more of polyurethane foam, polypropylene foam, polyethylene foam, PVC foam, EVA foam, and melamine foam.

6. The preparation method according to any one of claims 1 to 3, characterized in that, The drying temperature range is 80 to 150 °C, and the drying time range is 5 to 180 min; and / or, The sintering temperature range is 300 to 850 °C, and the sintering time range is 10 to 480 min.

7. The preparation method according to any one of claims 1 to 3, characterized in that, The copper paste includes copper powder, a pore-forming agent, a binder, and a solvent.

8. The preparation method according to claim 7, wherein The mass fraction of the copper powder is 30 to 95%, and the particle size range is 50 nm to 200 μm; and / or, The mass fraction of the pore-forming agent is 0 to 85%, and the particle size range is 500 nm to 100 μm; and / or, The mass fraction of the binder is 1 to 20%.

9. A capillary structure for a heat pipe, characterized in that, Prepared by the preparation method according to any one of claims 1 to 8.

10. A heat pipe, characterized in that, The heat pipe includes an upper cover plate, a lower cover plate, and a capillary structure, wherein, the capillary structure is located between the upper cover plate and the lower cover plate, and the capillary structure adopts the capillary structure according to claim 9.

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