Preparation method of integrally-formed graphene micro-channel liquid cooling device

Abstract

The invention provides a preparation method of an integrally-formed graphene micro-channel liquid cooling device. Compared with the prior art, the integrally-formed high-heat-conductivity graphene film is adopted as a micro-channel heat sink material, the compounding process of graphene and traditional metal copper, metal aluminum, silicon and other materials is avoided, and the advantage of high heat conductivity of graphene is fully played; and the graphene micro-channel is integrally formed through laser ablation of the pattern or mold imprinting, accurate machining of the complex micro-channel can be achieved, the process is simple, and the potential of large-scale production is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of chip cooling, and in particular relates to a method for preparing an integrally formed graphene microchannel liquid cooling device. Background Art

[0002] With the rapid upgrade and iteration of electronic devices and the development trend of high integration, the heat dissipation of high-power chips has become a key factor restricting their performance. Microchannel heat sinks are devices that use flowing cooling fluids to exchange heat in microchannels with a size of less than 1mm to achieve heat dissipation. They have attracted much attention due to their small size, high specific surface area, strong heat exchange capacity and easy integration.

[0003] The heat exchange capacity of a microchannel heat sink depends on the thermal conductivity of the main material of the microchannel. The thermal conductivity of traditional metal materials can no longer meet the increasing demand for heat dissipation. Therefore, it is urgent to develop and apply a new generation of high thermal conductivity materials. The in-plane thermal conductivity of a single atomic layer of graphene can reach 5300 W m -1 K -1 The in-plane thermal conductivity of the graphene macro film assembled layer by layer can still reach 1900 W m -1 K -1 , is copper (~400W m -1 K -1 ) is 4 to 5 times that of graphene; in addition, graphene has the characteristics of low density and chemical inertness, making it an ideal choice for the next generation of microchannel heat dissipation materials.

[0004] At present, the common way to introduce graphene into microchannel heat dissipation devices is still to compound graphene with traditional metal materials. The Chinese patent with publication number CN115548517A discloses a graphene-coated liquid cooling plate and its preparation method, wherein the upper and lower substrates are made of graphene / aluminum-based reinforcement materials. With the assistance of a mask, the middle layer is coated, heated, and inflated to obtain a graphene flow channel. The graphene coating on the lower substrate is provided with an array of concave unit microstructures to assist in further heat dissipation. However, in the common composite method: the addition of graphene nanosheets into metal materials is usually affected by the low thermal conductivity caused by the rich structural defects of the graphene sheets; and the composite graphene film or powder on the surface will introduce the problem of graphene / metal interface thermal resistance. In addition, the heat dissipation performance of the microchannel device still depends on the thermal conductivity of the main metal material, and the introduction of a small amount of graphene cannot significantly improve the heat dissipation of the device. Microchannel devices based on pure graphene can potentially achieve a significant improvement in heat exchange efficiency.

[0005] The processing of graphene microchannels is an important challenge in the device construction process. The method of laminating or bonding graphene films layer by layer is prone to channel deformation and even leakage under large microchannel pressure drop. In order to improve the service life of graphene microchannels, the one-piece molding method is a more promising approach to process graphene microchannels. Subtractive processing can obtain microchannels with high precision. For example, Chinese patent with publication number CN108963065A discloses a method for preparing single-layer and multi-layer graphene thermoelectric detectors by laser ablation, which performs laser ablation on multi-layer graphene films with nanometer and sub-nanometer thicknesses to convert local multi-layer graphene films into single-layer graphene films. The patent verifies the laser thinning of graphene films, but the precise processing of graphene macro-assembly films with micrometer or even millimeter thicknesses has not yet been solved; controlling the deformation of graphene films is another effective way to construct microchannels. For example, Chinese patent with publication number CN113820917A discloses a method for preparing nano-imprinted anisotropic graphene films, which uses two PDMS templates to sandwich a thermoplastic polymer film with graphene doped on the surface in the middle to form a "sandwich" structure and uses a nano-imprinter to obtain a nano-imprinted anisotropic graphene film in one step, but the imprint deformation of pure graphene films has not yet been achieved. The graphene macroscopic assembled bubble film contains rich pore structure and compressibility, which can be easily molded into the desired shape and is more suitable for deformation construction of graphene microchannels.

[0006] In summary, in order to give full play to the advantages of graphene's high thermal conductivity, the preparation technology of graphene microchannel liquid cooling devices with graphene as a single material and simple process needs to be studied. Summary of the invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing an integrally formed graphene microchannel liquid cooling device.

[0008] The present invention provides a method for preparing an integrally formed graphene microchannel liquid cooling device, comprising the following steps:

[0009] S1) using an imprinting mold to imprint the graphene foam film to obtain a graphene microchannel;

[0010] S2) stacking the packaging material, the graphene microchannel and the thermal conductive adhesive in order, pressing them together, and obtaining an integrated graphene microchannel liquid cooling device.

[0011] Preferably, the density of the graphene foam film is 0.05 to 1.0 g·cm -3 ; The density of the graphene microchannel after imprinting is 1-2.25 g·cm -3 .

[0012] Preferably, the thickness of the graphene foam film is 20 to 20000 μm.

[0013] Preferably, the stamping pressure is 2-200N.

[0014] Preferably, the embossing reduces the thickness of the graphene foam film to 1 / 2 to 1 / 4 of the original thickness.

[0015] The present invention also provides a method for preparing an integrally formed graphene microchannel liquid cooling device, comprising the following steps:

[0016] A1) performing microchannel etching on one surface of the graphene film using a laser ablation process to obtain a graphene microchannel;

[0017] A2) stacking the packaging material, the graphene microchannel and the thermal conductive adhesive in order, pressing them together, and obtaining an integrated graphene microchannel liquid cooling device.

[0018] Preferably, the density of the graphene film is 1.8 to 2.25 g·cm -3 ; The thickness of the graphene film is 10 to 10000 μm.

[0019] Preferably, the thermal conductivity of the graphene film is 1000-2000 W·m -1 ·K -1 .

[0020] Preferably, the power of the laser ablation process is 2 to 100 W; the processing rate of the laser ablation process is 100 to 10000 mm·s -1 .

[0021] Preferably, the depth of the microchannel etching is 10% to 90% of the thickness of the graphene film.

[0022] Compared with the prior art, the present invention adopts an integrally formed high thermal conductivity graphene film as the microchannel heat sink material, avoiding the composite process of graphene with traditional metal copper, metal aluminum, silicon and other materials, giving full play to the high thermal conductivity advantage of graphene; and by integrally forming the graphene microchannel through laser ablation pattern or embossing mold, precise processing of complex microchannels can be achieved, the process is simple, and it has the potential for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic side view of the structure of the graphene microchannel device prepared in Examples 1 to 3 of the present invention and Comparative Example 1;

[0024] Figure 2 A structural diagram of an in-line microchannel imprinting mold used in Example 1 of the present invention;

[0025] Figure 3 This is an exploded schematic diagram of the graphene microchannel device obtained in Example 1 of the present invention being attached to an electronic component using a thermally conductive adhesive;

[0026] Figure 4 This is a diagram of the channel structure of the Y-shaped graphene microchannel layer ablated by laser in Example 2 of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] The present invention provides a method for preparing an integrally formed graphene microchannel liquid cooling device, comprising the following steps: S1) using an imprinting mold to imprint a graphene foam film to obtain a graphene microchannel; S2) stacking and pressing a packaging material, a graphene microchannel and a thermal conductive adhesive in sequence to obtain an integrally formed graphene microchannel liquid cooling device.

[0029] The present invention has no particular limitation on the sources of all raw materials, and any raw materials available on the market can be used.

[0030] According to the present invention, the imprinting mold is preferably obtained by mechanically and / or laser etching a microchannel pattern for imprinting on a mold material; the mold material includes but is not limited to stainless steel, aluminum, resin or rubber, etc.; the microchannel pattern includes but is not limited to single / double / triple straight channels, wavy microchannels, serpentine microchannels, spiral microchannels, etc.

[0031] The graphene foam film is embossed with an embossing mold to obtain a graphene microchannel; in the present invention, the density of the graphene foam film is preferably 0.05 to 1.0 g·cm -3 , more preferably 0.1 to 1.0 g·cm -3 , and more preferably 0.2 to 0.8 g·cm -3 , and more preferably 0.4 to 0.6 g·cm -3 , and the most preferred value is 0.5 g·cm -3 ; The present invention uses graphene macroscopic bubble membranes with rich pores and compressibility as the main material of the microchannel, which can be easily prepared by mechanical processing. The selection of the imprinting mold material and the size of the applied pressure are key influencing factors. 0.2~1.0g·cm -3 The graphene foam film is pressurized by a hard mold (such as stainless steel, HRC120-150), and the pressure is controlled at 20-200N; and 0.05-0.2g·cm -3The graphene foam film needs to be pressed with a low hardness mold (such as thermosetting plastic, HRC60-80), and the pressure is controlled at 2-20N. Too little pressure will cause the graphene foam film to be unable to be fully densified, affecting the liquid cooling pressure resistance of the graphene microchannel; too much pressure will cause the graphene foam film to be partially pressed through and the film to be damaged. The density of the graphene microchannel after printing is preferably 1-2.25g·cm -3 ; The thickness of the graphene foam film is preferably 20-20000 μm, more preferably 50-10000 μm, more preferably 50-5000 μm, more preferably 100-1000 μm, more preferably 100-800 μm, more preferably 100-500 μm, more preferably 100-300 μm, and most preferably 200 μm; the pressure of the stamping is preferably 2-200 N, more preferably 10-200 N, more preferably 50-150 N, more preferably 80-120 N, and most preferably 100 N; the stamping preferably reduces the thickness of the graphene foam film to 1 / 2-1 / 4 of the original thickness.

[0032] The packaging material, the graphene microchannel and the thermal conductive adhesive are stacked and pressed in sequence to obtain an integrally formed graphene microchannel liquid cooling device; the packaging material is mainly used for sealing the graphene microchannel layer with the top layer and the side edges to prevent leakage of the cooling medium; the packaging material can be a resin material known to those skilled in the art without any special restrictions, and is preferably a resin or metal in the present invention, including but not limited to one or more of stainless steel, aluminum, epoxy resin, polyimide resin, polyurethane resin, silicone resin, polymethyl methacrylate resin and polytetrafluoroethylene; The graphene microchannel is used for cooling medium to pass through; the cooling medium is pure liquid water, air, ethylene glycol, heat transfer oil, liquid metal and the above media with added solid particles; the thermal conductive adhesive is used for connecting the graphene microchannel liquid cooling device and the electronic device, which can be a thermal interface material, preferably including but not limited to thermal grease, thermal silica gel, thermal gel, thermal phase change material and liquid metal; the pressing pressure is preferably 0.5-10MPa, more preferably 1-8MPa, more preferably 1-5MPa, and most preferably 1-2MPa.

[0033] The present invention also provides another method for preparing an integrally formed graphene microchannel liquid cooling device, comprising the following steps: A1) performing microchannel etching on a surface of a graphene film using a laser ablation process to obtain a graphene microchannel; A2) stacking and pressing a packaging material, a graphene microchannel and a thermal conductive adhesive in sequence to obtain an integrally formed graphene microchannel liquid cooling device.

[0034] According to the present invention, the graphene film is preferably a commercially available graphene film that has been subjected to high-temperature graphitization treatment; the density of the graphene film is preferably 1.8 to 2.25 g·cm -3The thickness of the graphene film is preferably 10 to 10000 μm, more preferably 50 to 5000 μm, more preferably 50 to 2000 μm, more preferably 50 to 1000 μm, more preferably 50 to 800 μm, more preferably 80 to 500 μm, more preferably 80 to 300 μm, and most preferably 100 to 200 μm; the thermal conductivity of the graphene film is preferably 1000 to 2000 W·m -1 ·K -1 ; If the laser ablation process uses too high a processing rate, a dot-dashed processing trajectory will be formed, while using too low a processing rate will affect the processing efficiency; using too high a laser power will cause over-ablation, resulting in an increase in etching depth, while too low a laser power will not be able to etch the graphene film. Therefore, appropriate laser processing speed and power are required to achieve uniform, depth-controlled graphene microchannel etching processing; in the present invention, the power of the laser ablation process is preferably 2 to 100 W, more preferably 5 to 100 W, more preferably 10 to 80 W, more preferably 10 to 60 W, more preferably 10 to 50 W, more preferably 20 to 40 W, and most preferably 20 to 30 W; the processing rate of the laser ablation process is preferably 100 to 10,000 mm·s -1 , more preferably 100 to 5000 mm·s -1 , and more preferably 500 to 2000 mm·s -1 , and more preferably 800 to 1500 mm·s -1 , and preferably 800 to 1200 mm·s -1 , the most preferred is 1000 mm·s -1 ; Microchannels are obtained by etching microchannels on one surface of a graphene film through a laser ablation process; the depth of the microchannel etching is preferably 10% to 90% of the thickness of the graphene film, more preferably 20% to 80%, more preferably 30% to 70%, more preferably 40% to 60%, and most preferably 50%.

[0035] The packaging material, the graphene microchannel and the thermal conductive adhesive are stacked and pressed in sequence to obtain an integrally formed graphene microchannel liquid cooling device; the packaging material is mainly used for sealing the graphene microchannel layer with the top layer and the side edges to prevent leakage of the cooling medium; the packaging material can be a resin material known to those skilled in the art without any special restrictions, and is preferably a resin or metal in the present invention, including but not limited to one or more of stainless steel, aluminum, epoxy resin, polyimide resin, polyurethane resin, silicone resin, polymethyl methacrylate resin and polytetrafluoroethylene; The graphene microchannel is used for cooling medium to pass through; the cooling medium is pure liquid water, air, ethylene glycol, heat transfer oil, liquid metal and the above media with added solid particles; the thermal conductive adhesive is used for connecting the graphene microchannel liquid cooling device and the electronic device, which can be a thermal interface material, preferably including but not limited to thermal grease, thermal silica gel, thermal gel, thermal phase change material and liquid metal; the pressing pressure is preferably 0.5-10MPa, more preferably 1-8MPa, more preferably 1-5MPa, and most preferably 1-2MPa.

[0036] The present invention adopts an integrally formed high thermal conductivity graphene film as the microchannel heat sink material, avoiding the composite process of graphene with traditional metal copper, metal aluminum, silicon and other materials, giving full play to the high thermal conductivity advantage of graphene; and by integrally forming the graphene microchannel through laser ablation pattern or embossing mold, precise processing of complex microchannels can be achieved, the process is simple, and it has the potential for large-scale production.

[0037] In order to further illustrate the present invention, the preparation method of the one-piece graphene microchannel liquid cooling device provided by the present invention is described in detail below in combination with the embodiments.

[0038] The reagents used in the following examples are all commercially available.

[0039] Example 1

[0040] preparation Figure 1 The graphene microchannel device with the structure shown in the figure is composed of the electronic device thermal conductive adhesive, graphene microchannel, packaging material, cooling medium outlet and cooling medium inlet from bottom to top. -3 The graphene bubble film is laser cut to form a stainless steel imprinting mold ( Figure 2 ) is close to the shape, the imprinting mold is attached to one side of the graphene bubble film, and a pressure of 100N is applied to press it. The thickness of the mold position is reduced by 150μm by imprinting, and a single-row straight microchannel with a channel height of 50μm is obtained. Then the encapsulation resin, the imprinted graphene bubble film microchannel, and the thermal conductive adhesive are stacked in sequence, and a pressure of 1MPa is applied to press it. The inlet and outlet of the cooling medium are set on the side, and finally the graphene microchannel device is attached to the electronic component with thermal conductive adhesive ( Figure 3 ), and obtain a graphene microchannel liquid cooling device.

[0041] Example 2

[0042] preparation Figure 1 The graphene microchannel device with the structure shown in the figure consists of electronic devices, thermal conductive adhesive, graphene microchannel, packaging material, cooling medium outlet and cooling medium inlet from bottom to top. -3 The graphene bubble film was laser cut into a shape close to the imprinting mold, and the Y-shaped stainless steel imprinting mold was fitted to one side of the graphene bubble film. A 100N pressure was applied to press it together. The thickness of the mold position was reduced by 100μm, and a Y-shaped microchannel ( Figure 4 ), the microchannel width is set to 1mm. Then the encapsulation resin, the laser-ablated graphene bubble film microchannel, and the thermal conductive adhesive are stacked in order, and a pressure of 2MPa is applied to press them together. The inlet and outlet of the cooling medium are set on the side, and finally the graphene microchannel device is attached to the electronic component with thermal conductive adhesive to obtain a graphene microchannel liquid cooling device.

[0043] Example 3

[0044] preparation Figure 1 The graphene microchannel device with the structure shown in the figure includes electronic devices, thermal conductive adhesive, graphene microchannel, packaging material, cooling medium outlet and cooling medium inlet from bottom to top. The graphene film with thermal conductive adhesive is cut by laser, with a density of 2.2g·cm -3 , thickness is 100 μm, thermal conductivity is 1740 W m -1 K -1 The laser ablation technique was used to etch microchannels on the surface of the film, and a Y-shaped microchannel ( Figure 4 ), set the laser power to 20W and the processing speed to 1000mm s -1 The width of the microchannel is set to 2mm, and the height of the obtained microchannel is 50μm. Then the encapsulation resin, the laser-ablated graphene film microchannel, and the thermal conductive adhesive are stacked in order and pressed together with a pressure of 1MPa. The inlet and outlet of the cooling medium are set on the side, and finally the graphene microchannel device is attached to the electronic component with thermal conductive adhesive to obtain a graphene microchannel liquid cooling device.

[0045] The graphene microchannel liquid cooling device obtained in Examples 1 to 3 has high durability and pressure drop resistance. After the cooling liquid circulates, the microchannel structure is stable and will not cause liquid leakage on the back of the microchannel device.

[0046] Comparative Example 1

[0047] preparation Figure 1The graphene microchannel device with the structure shown in the figure is composed of the electronic device thermal conductive adhesive, graphene microchannel, packaging material, cooling medium outlet and cooling medium inlet from bottom to top. -3 The graphene bubble film was laser cut into a shape close to the imprinting mold. The stainless steel imprinting mold was fitted to one side of the graphene bubble film, and a pressure of 250N was applied to press it together. It was found that the graphene bubble film was partially pressed through and holes appeared, and it was stuck to the processed substrate and could not be removed.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an integrally formed graphene microchannel liquid cooling device, characterized in that: The following steps are involved: S1) using an imprinting mold to imprint the graphene foam film to obtain a graphene microchannel; S2) stacking the packaging material, the graphene microchannel and the thermal conductive adhesive in order, pressing them together, and obtaining an integrated graphene microchannel liquid cooling device.

2. The preparation method according to claim 1, characterized in that: The density of the graphene foam film is 0.05-1.0 g·cm -3 ; The density of the graphene microchannel after imprinting is 1-2.25 g·cm -3 .

3. The preparation method according to claim 1, characterized in that: The thickness of the graphene foam film is 20 to 20000 μm.

4. The preparation method according to claim 1, characterized in that: The stamping pressure is 2-200N.

5. The preparation method according to claim 1, characterized in that: The embossing reduces the thickness of the graphene foam film to 1 / 2 to 1 / 4 of the original thickness.

6. A method for preparing an integrally formed graphene microchannel liquid cooling device, characterized in that: The following steps are involved: A1) performing microchannel etching on one surface of the graphene film using a laser ablation process to obtain a graphene microchannel; A2) stacking the packaging material, the graphene microchannel and the thermal conductive adhesive in order, pressing them together, and obtaining an integrated graphene microchannel liquid cooling device.

7. The preparation method according to claim 6, characterized in that: The density of the graphene film is 1.8 to 2.25 g·cm -3 ; The thickness of the graphene film is 10 to 10000 μm.

8. The preparation method according to claim 6, characterized in that: The thermal conductivity of the graphene film is 1000-2000 W·m -1 ·K -1 .

9. The preparation method according to claim 6, characterized in that: The power of the laser ablation process is 2 to 100 W; the processing rate of the laser ablation process is 100 to 10000 mm·s -1 .

10. The preparation method according to claim 6, characterized in that: The depth of the microchannel etching is 10% to 90% of the thickness of the graphene film.

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