Flexible carbon nanotube sponge vapor chamber and preparation method thereof

Abstract

The invention discloses a flexible carbon nanotube sponge vapor chamber and a preparation method thereof, and belongs to the technical field of vapor chambers, the flexible carbon nanotube sponge vapor chamber comprises a first flexible shell plate, a flexible liquid absorption core, a flexible support layer and a second flexible shell plate which are arranged in sequence; the first flexible shell plate and the second flexible shell plate are connected in a sealed mode to form a vacuum cavity, and the vacuum cavity is filled with a liquid working medium. The flexible supporting layer is made of carbon nano tube sponge. The carbon nanotube sponge is used as the flexible supporting layer, the carbon nanotube sponge is of a three-dimensional net-shaped structure, the carbon nanotube sponge has high porosity and an extremely large super-hydrophobic surface area, and accurate control of a steam channel can be achieved by regulating and controlling the size and density of holes; therefore, the accumulation of heat in the cavity is reduced, and the recovery speed of the cooling liquid and the overall heat dissipation performance are improved.

Description

Technical Field

[0001] The invention relates to the technical field of vapor chambers, and in particular to a flexible carbon nanotube sponge vapor chamber and a preparation method thereof. Background Art

[0002] With the advent of the 5G era, the development of the global data information industry has accelerated suddenly, bringing people a higher performance experience while also bringing new requirements for the heat dissipation performance of existing network infrastructure. The heat spreader is a heat transfer element with ultra-high thermal conductivity. It is generally composed of a shell plate, a support column, a vacuum cavity, a liquid wick and a liquid working medium. It achieves efficient heat exchange through the huge phase change latent heat generated by the gas-liquid phase change of the internal liquid working medium. It has been widely used in the thermal management technology of electronic products in the 5G era.

[0003] At present, most traditional heat spreaders are made of metal materials such as copper, aluminum, and stainless steel to make rigid shells and support columns. When bent and folded, the shell and internal structure will be irreversibly damaged, affecting its mechanical properties and the effective flow of fluid media, limiting its application in flexible electronic devices (wearable devices, flexible displays, etc.). In addition, since most existing heat spreaders use opaque shells, it is impossible to clearly and intuitively observe the internal structure during the preparation and use process, and thus it is impossible to promptly and effectively solve the failure problem of the heat spreader, and it is difficult to accurately analyze and optimize the structural parameters. Therefore, it is urgent to design a visual flexible heat spreader to improve its heat dissipation and reliability.

[0004] In view of this, this application is filed. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a flexible carbon nanotube sponge heat spreader and a preparation method thereof, which have excellent flexibility and visibility, thereby improving the heat dissipation and reliability of the heat spreader and expanding its application in flexible electronic devices.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A flexible carbon nanotube sponge soaking plate, comprising a first flexible shell plate, a flexible liquid wick, a flexible support layer, and a second flexible shell plate arranged in sequence; the first flexible shell plate and the second flexible shell plate are sealed and connected to form a vacuum cavity, and the vacuum cavity is filled with a liquid working medium;

[0008] The flexible supporting layer is carbon nanotube sponge.

[0009] Preferably, the first flexible shell plate and the second flexible shell plate are both made of polymer film materials; the polymer film material includes at least one of PET, PP, PI, PE, and PVA.

[0010] Preferably, the flexible liquid-absorbing core comprises metal powder, carbon material and binder; the mass ratio of the metal powder, carbon material and binder is (40-50): (15-20): (30-45).

[0011] Preferably, the metal powder includes at least one of copper powder, aluminum powder, aluminum-magnesium alloy powder, aluminum-copper alloy powder and aluminum-zinc alloy powder;

[0012] The carbon material includes at least one of carbon nanotubes, graphene, and graphite;

[0013] The binder includes at least one of sulfate, silicate, phosphate and borate.

[0014] Preferably, the average particle size of the metal powder is 20 to 500 nm;

[0015] The average particle size of the carbon material is 0.5 to 20 μm.

[0016] Preferably, the thickness of the first flexible shell plate is 0.01-0.2 mm;

[0017] The thickness of the second flexible shell plate is 0.01-0.2 mm;

[0018] The thickness of the flexible support layer is 1 to 5 mm;

[0019] The thickness of the flexible liquid-absorbing core is 0.02-0.15 mm.

[0020] The present invention also provides a method for preparing a flexible carbon nanotube sponge soaking plate, comprising the following steps:

[0021] (1) providing a first flexible shell panel and a second flexible shell panel;

[0022] (2) mixing metal powder, carbon material, binder and water uniformly to obtain a paste;

[0023] (3) applying the paste on the surface of the first flexible shell plate, baking and curing to obtain a flexible liquid absorbent core, and performing plasma surface activation treatment on the flexible liquid absorbent core;

[0024] (4) placing the carbon nanotube sponge between the flexible liquid absorbent core and the second flexible shell plate, aligning and compacting them, and sealing the joint between the first flexible shell plate and the second flexible shell plate to obtain a heat spreader cavity with a reserved injection pipe hole;

[0025] (5) Insert the injection tube into the injection tube hole, fix the cavity and the injection tube, inject the liquid working medium and then use a vacuum machine to evacuate the liquid, seal the injection tube, and obtain a flexible carbon nanotube sponge heat spreader.

[0026] Preferably, the solid content of the paste is 60-80%.

[0027] Preferably, the baking temperature is 175-185° C. and the baking time is 30-50 min.

[0028] Preferably, the power of the plasma surface activation treatment is 50 to 300 W, and the time is 5 to 20 minutes.

[0029] The beneficial effects of the present invention are as follows: (1) The present invention adopts carbon nanotube sponge as a flexible support layer. The carbon nanotube sponge is a three-dimensional mesh structure. The carbon nanotube sponge has a high porosity and a large super-hydrophobic surface area, and the precise control of the steam channel can be achieved by adjusting the pore size and density, so it is beneficial to reduce the accumulation of heat inside the chamber, improve the recovery rate of the coolant and the overall heat dissipation performance. (2) The carbon nanotube sponge used in the present invention has high reversible compressibility and flexibility, can withstand a large degree of bending or twisting without breaking, and can still return to its original shape after deformation, so that it can be used as a support structure to fit the liquid absorbent core with various irregular surfaces, and the liquid absorbent core pore structure will not be damaged when it is bent and squeezed, thereby improving the overall structural stability and flexibility of the heat spreader. (3) The present invention adopts a high-temperature resistant, flexible and transparent polymer film or composite film, and adjusts its type and thickness to achieve the purpose of flexibility and visualization, so that the real gas-liquid two-phase flow inside the heat spreader can be observed at any time, and whether the internal structure is damaged can be found in time, so that the structural parameters can be accurately and effectively optimized to improve the overall performance. (4) The present invention adjusts and controls relevant technical parameters so that the preparation process can work synergistically. The obtained visualized flexible carbon nanotube sponge heat spreader has the advantages of simple preparation process, easy operation, low production cost, and easy large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of the heat spreader of the present invention.

[0031] Figure 2 It is a schematic structural diagram of the heat spreader of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0033] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0034] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0035] In the present application, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0036] Unless otherwise specified, the components, raw materials or instruments used in the embodiments and comparative examples of the present invention are all commercially available raw materials or instruments, and the components and raw materials used in each parallel experiment are all of the same kind.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0038] See also Figure 1-2 The present invention provides a flexible carbon nanotube sponge soaking plate, comprising a first flexible shell plate 1, a flexible liquid wick 3, a flexible support layer 4, and a second flexible shell plate 2 arranged in sequence; the first flexible shell plate and the second flexible shell plate are sealed and connected to form a vacuum cavity, and the vacuum cavity is filled with a liquid working medium;

[0039] The flexible supporting layer is carbon nanotube sponge.

[0040] The present invention adopts carbon nanotube sponge as a flexible supporting layer. The carbon nanotube sponge is a three-dimensional network structure. The carbon nanotube sponge has a high porosity and a large super-hydrophobic surface area, and the steam channel can be precisely controlled by adjusting the pore size and density. Therefore, it is beneficial to reduce the accumulation of heat inside the chamber, improve the recovery rate of the coolant and the overall heat dissipation performance.

[0041] The carbon nanotube sponge used in the present invention has high reversible compressibility and flexibility, can withstand a large degree of bending or twisting without breaking, and can still return to its original shape after deformation. Therefore, it can be used as a supporting structure to fit the absorbent cores on various irregular surfaces, and the pore structure of the absorbent core will not be damaged when bent or squeezed, thereby improving the overall structural stability and flexibility of the heat spreader.

[0042] It should be noted that the present invention has no limitation on the shape of the flexible support layer, and the flexible support layer can be adjusted to any shape, such as a cube, a cylinder or a cone.

[0043] In one embodiment, the flexible supporting layer is in the shape of a cube.

[0044] Furthermore, the lower surface of the first flexible shell plate is a concave structure, and the upper surface of the second flexible shell plate is a flat structure, which facilitates the sealing connection between the first flexible shell plate and the second flexible shell plate.

[0045] In one embodiment, the first flexible shell plate and the second flexible shell plate are both made of polymer film materials; the polymer film material includes at least one of PET, PP, PI, PE, and PVA.

[0046] The present invention adopts a high temperature resistant, flexible and transparent polymer film or composite film, and adjusts its type and thickness to achieve the purpose of flexibility and visualization, so as to observe the actual gas-liquid two-phase flow conditions inside the heat spreader at any time, and promptly discover whether the internal structure is damaged, thereby accurately and effectively optimizing the structural parameters to improve the overall performance.

[0047] In one embodiment, the flexible liquid-absorbing core comprises metal powder, carbon material and binder; the mass ratio of the metal powder, carbon material and binder is (40-50): (15-20): (30-45).

[0048] The inventors of the present invention have found that the ratio of the metal powder, carbon material and binder has a significant effect on the heat dissipation effect. By controlling the mass ratio of the metal powder, carbon material and binder to (40-50): (15-20): (30-45), the capillary force, liquid reflux rate and heat dissipation efficiency of the flexible absorbent core can be effectively adjusted, the production efficiency can be accelerated and the energy consumption can be reduced, the mechanical strength and thermal conductivity of the flexible absorbent core can be improved, so as to reduce the diffusion thermal resistance of the absorbent core, improve the overall reliability, and effectively avoid the agglomeration of the metal powder and carbon material.

[0049] In one embodiment, the metal powder includes at least one of copper powder, aluminum powder, aluminum-magnesium alloy powder, aluminum-copper alloy powder and aluminum-zinc alloy powder;

[0050] The carbon material includes at least one of carbon nanotubes, graphene, and graphite;

[0051] The binder includes at least one of sulfate, silicate, phosphate and borate.

[0052] In one embodiment, the average particle size of the metal powder is 20 to 500 nm;

[0053] The average particle size of the carbon material is 0.5 to 20 μm.

[0054] In one embodiment, the thickness of the first flexible shell is 0.01-0.2 mm;

[0055] The thickness of the second flexible shell plate is 0.01-0.2 mm;

[0056] The thickness of the flexible support layer is 1 to 5 mm;

[0057] The thickness of the flexible liquid-absorbing core is 0.02-0.15 mm.

[0058] An embodiment of the present invention further provides a method for preparing a flexible carbon nanotube sponge soaking plate, comprising the following steps:

[0059] (1) providing a first flexible shell panel and a second flexible shell panel;

[0060] (2) mixing metal powder, carbon material, binder and water uniformly to obtain a paste;

[0061] (3) applying the paste on the surface of the first flexible shell plate, baking and curing to obtain a flexible liquid absorbent core, and performing plasma surface activation treatment on the flexible liquid absorbent core;

[0062] (4) placing the carbon nanotube sponge between the flexible liquid absorbent core and the second flexible shell plate, aligning and compacting them, and sealing the joint between the first flexible shell plate and the second flexible shell plate to obtain a heat spreader cavity with a reserved injection pipe hole;

[0063] (5) Insert the injection tube into the injection tube hole, fix the cavity and the injection tube, inject the liquid working medium and then use a vacuum machine to evacuate the liquid, seal the injection tube, and obtain a flexible carbon nanotube sponge heat spreader.

[0064] In one embodiment, the solid content of the paste is 60-80%. By controlling the solid content of the paste to be 60-80%, during the baking process, the water between the capillary particles in the paste evaporates to form a plurality of pores, which is conducive to forming a suitable pore structure to increase the liquid absorption effect of the liquid absorbent core. In addition, it can ensure that the flexible heat spreader has good flexibility, bendability and lightness, and make the bonding strength between the liquid absorbent core and the plate shell higher, so that the contact thermal resistance between the liquid absorbent core and the plate shell is lower, thereby improving the heat transfer efficiency.

[0065] In one embodiment, the baking temperature is 175-185°C and the time is 30-50 minutes. After the paste is baked and cured, the water inside it evaporates and only the capillary particles remain and pores are formed between the capillary particles, thereby obtaining a liquid absorbent core. Most of the existing heat spreaders are baked and cured at high temperature in a baking and curing furnace. The production time of the heat spreader is long, the risk factor is high, and the cost is high. It is not possible to produce a large number of heat spreaders at one time. The drying temperature of the present invention is only 175-185°C. This low-temperature preparation can avoid the cracking of the liquid absorbent core caused by high-temperature thermal stress, and can effectively ensure the physical properties of the high-temperature resistant polymer film or composite film used as a flexible shell plate.

[0066] Preferably, the power of the plasma surface activation treatment is 50 to 300 W, and the time is 5 to 20 min. The plasma surface activation technology is used to introduce a large number of hydrophilic groups (hydroxyl or carboxyl) on the surface of the liquid absorbent core to hydrophilize the liquid absorbent core, thereby greatly reducing the surface energy of the liquid absorbent core and improving its hydrophilicity, thereby increasing the liquid circulation rate.

[0067] In one embodiment, the method of sealing the joint between the first flexible shell plate and the second flexible shell plate includes, but is not limited to, gluing, heat pressing, brazing or ultrasonic welding.

[0068] In one embodiment, the method of fixing the cavity and the injection tube includes but is not limited to high-frequency welding or gluing.

[0069] In one embodiment, the method of sealing the injection tube includes but is not limited to heat pressing.

[0070] In one embodiment, the liquid working medium is water.

[0071] The following examples are provided to facilitate understanding of the present invention. These examples are not provided to limit the scope of the claims.

[0072] Example 1

[0073] like Figure 1 , Figure 2 As shown, this embodiment provides a flexible carbon nanotube sponge heat spreader, comprising a first flexible shell plate 1, a flexible liquid absorbent core 3, a flexible support layer 4 and a second flexible shell plate 2 arranged in sequence; the first flexible shell plate and the second flexible shell plate are connected by edge sealing to form a vacuum cavity, and the vacuum cavity is filled with liquid working fluid (water).

[0074] The flexible porous absorbent core and the supporting structure are arranged inside the cavity between the first flexible shell plate and the second flexible shell plate, and the lower end surface of the flexible porous absorbent core is in contact with the inner surface of the first flexible shell plate, and the flexible porous supporting structure is tightly fitted with the upper end surface of the flexible porous absorbent core and the inner surface of the second flexible shell plate.

[0075] Among them, the first flexible shell plate and the second flexible shell plate are both made of flexible, transparent and high-temperature resistant PET material, with a thickness of 0.05 mm, and are both cut into rectangular blocks with a length and width of 60 mm.

[0076] The thickness of the flexible porous liquid absorbent core is 0.1 mm, and the flexible porous liquid absorbent core is made of nano copper powder, carbon nanotubes and a binder uniformly mixed, and the mass ratio of the nano copper powder, carbon nanotubes and binder is 40:20:40. The average particle size of the nano copper powder is 20 nm, the average particle size of the carbon nanotube is 10 μm, the average tube diameter is 10 nm, and the average tube length is 200 μm. The binder is potassium silicate.

[0077] The flexible support layer is a carbon nanotube sponge with a thickness of 0.2 mm, which is cut into a cuboid with a length and width of 60 mm. It has excellent flexibility, a certain margin in the thickness direction, adjustable thickness, reduced processing requirements, and is simple and convenient to process.

[0078] The method for preparing the flexible carbon nanotube sponge soaking plate comprises the following steps:

[0079] (1) providing a first flexible shell panel and a second flexible shell panel;

[0080] (2) mixing the nano copper powder, carbon nanotubes, potassium silicate and water uniformly to obtain a paste with a solid content of 60%;

[0081] (3) applying the paste on the surface of the first flexible shell plate, baking and curing at 180° C. for 40 min to obtain a flexible liquid absorbent core, and performing plasma surface activation treatment on the flexible liquid absorbent core, the plasma surface activation power is 200 W, the time is 10 min, and the atmosphere is air;

[0082] (4) placing the carbon nanotube sponge between the flexible liquid absorbent core and the second flexible shell plate, positioning and pressing, and then using a hot press to press and seal the edges of the first flexible shell plate and the second flexible shell plate to obtain a cavity with a reserved injection tube hole;

[0083] (5) The injection tube inserted into the injection tube hole is fixed to the cavity by means of glue coating, and an appropriate amount of deionized water is poured into the cavity through the injection tube; the cavity is evacuated by a vacuum machine, and when the vacuum degree reaches 11 Pa, hot pressing and sealing are performed to keep the cavity in a high vacuum state;

[0084] (6) Air tightness test: The prepared flexible heat spreader was tested for air tightness by helium testing (good air tightness), proving that it was completely sealed and the entire preparation process was completed.

[0085] Example 2

[0086] The difference between Example 2 and Example 1 is that in the flexible liquid absorbent core of Example 2, the mass ratio of the nano copper powder, carbon nanotubes and binder is 50:15:30. The nano copper powder has an average particle size of 100 nm, the carbon nanotubes have an average particle size of 10 μm, an average tube diameter of 10 nm, and an average tube length of 200 μm, and the binder is potassium silicate, and the rest are the same.

[0087] Example 3

[0088] The difference between Example 3 and Example 1 is that in the flexible liquid-absorbing core of Example 3, the solid content of the paste is 80%.

[0089] Example 4

[0090] The difference between Example 4 and Example 1 is that in the flexible liquid-absorbing core of Example 4, graphene with equal particle size is used to replace carbon nanotubes.

[0091] Comparative Example 1

[0092] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 is not subjected to plasma surface activation treatment.

[0093] Comparative Example 2

[0094] The difference between Comparative Example 2 and Example 1 is that in the flexible liquid-absorbing core of Comparative Example 2, the mass ratio of the nano copper powder, the carbon nanotubes and the binder is 30:45:25.

[0095] Comparative Example 3

[0096] The difference between Comparative Example 3 and Example 1 is that in the flexible liquid-absorbing core of Comparative Example 3, the mass ratio of the nano copper powder, the carbon nanotubes and the binder is 60:10:30.

[0097] Comparative Example 4

[0098] The difference between Comparative Example 4 and Example 1 is that in the flexible liquid-absorbing core of Comparative Example 3, the solid content of the paste is 90%.

[0099] Comparative Example 5

[0100] The difference between Comparative Example 5 and Example 1 is that in the flexible liquid-absorbing core of Comparative Example 5, the solid content of the paste is 50%.

[0101] Test Case

[0102] Table 1

[0103] Implementation Thermal conductivity (W / (m·K)) Flexural strength(MPa) Example 1 9270 2780 Example 2 8960 2740 Example 3 9130 2690 Example 4 9250 2760 Comparative Example 1 6530 2670 Comparative Example 2 7320 2480 Comparative Example 3 7760 2530 Comparative Example 4 8120 2150 Comparative Example 5 8350 2210

[0104] It can be seen from Table 1 that the vapor chamber of the present invention has excellent heat dissipation and reliability.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, 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 essence and scope of the technical solution of the present invention.

Claims

1. A flexible carbon nanotube sponge soaking plate, characterized in that: It comprises a first flexible shell plate, a flexible liquid-absorbing core, a flexible support layer and a second flexible shell plate which are arranged in sequence; the first flexible shell plate and the second flexible shell plate are sealed and connected to form a vacuum cavity, and the vacuum cavity is filled with a liquid working medium; The flexible supporting layer is carbon nanotube sponge.

2. The flexible carbon nanotube sponge soaking plate according to claim 1, characterized in that: The first flexible shell plate and the second flexible shell plate are both made of polymer film materials; the polymer film material includes at least one of PET, PP, PI, PE, and PVA.

3. The flexible carbon nanotube sponge soaking plate according to claim 1, characterized in that: The flexible liquid-absorbing core comprises metal powder, carbon material and binder; the mass ratio of the metal powder, carbon material and binder is (40-50): (15-20): (30-45).

4. The flexible carbon nanotube sponge soaking plate according to claim 1, characterized in that: The metal powder comprises at least one of copper powder, aluminum powder, aluminum-magnesium alloy powder, aluminum-copper alloy powder and aluminum-zinc alloy powder; The carbon material includes at least one of carbon nanotubes, graphene, and graphite; The binder includes at least one of sulfate, silicate, phosphate and borate.

5. The flexible carbon nanotube sponge soaking plate according to claim 4, characterized in that: The average particle size of the metal powder is 20 to 500 nm; The average particle size of the carbon material is 0.5 to 20 μm.

6. The flexible carbon nanotube sponge soaking plate according to claim 1, characterized in that: The thickness of the first flexible shell plate is 0.01-0.2 mm; The thickness of the second flexible shell plate is 0.01-0.2 mm; The thickness of the flexible support layer is 1 to 5 mm; The thickness of the flexible liquid-absorbing core is 0.02-0.15 mm.

7. The method for preparing the flexible carbon nanotube sponge soaking plate according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) providing a first flexible shell panel and a second flexible shell panel; (2) mixing metal powder, carbon material, binder and water uniformly to obtain a paste; (3) applying the paste on the surface of the first flexible shell plate, baking and curing to obtain a flexible liquid absorbent core, and performing plasma surface activation treatment on the flexible liquid absorbent core; (4) placing the carbon nanotube sponge between the flexible liquid absorbent core and the second flexible shell plate, aligning and compacting them, and sealing the joint between the first flexible shell plate and the second flexible shell plate to obtain a heat spreader cavity with a reserved injection pipe hole; (5) Insert the injection tube into the injection tube hole, fix the cavity and the injection tube, inject the liquid working medium and then use a vacuum machine to evacuate the liquid, seal the injection tube, and obtain a flexible carbon nanotube sponge heat spreader.

8. The method for preparing a flexible carbon nanotube sponge soaking plate according to claim 7, characterized in that: The solid content of the paste is 60-80%.

9. The method for preparing a flexible carbon nanotube sponge soaking plate according to claim 7, characterized in that: The baking temperature is 175-185° C., and the baking time is 30-50 minutes.

10. The method for preparing a flexible carbon nanotube sponge soaking plate according to claim 7, characterized in that: The power of the plasma surface activation treatment is 50 to 300 W, and the time is 5 to 20 minutes.

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