Heat-conducting gasket

Abstract

The utility model provides a heat-conducting gasket, and relates to the technical field of heat conduction. The heat-conducting gasket comprises a first heat-conducting film, a second heat-conducting film and a carbon nanotube group, the first heat-conducting film and the second heat-conducting film are distributed at intervals, and the carbon nanotube group is arranged between the first heat-conducting film and the second heat-conducting film. According to the heat-conducting gasket, the carbon nanotube group comprising the plurality of carbon nanotubes is arranged between the first heat-conducting film and the second heat-conducting film which are distributed at intervals, the plurality of first carbon nanotubes in the carbon nanotube group are connected to the first heat-conducting film, and at least one second carbon nanotube is connected to the second heat-conducting film; the plurality of first carbon nanotubes connected to the first heat-conducting film and the at least one second carbon nanotube connected to the second heat-conducting film are mutually matched and connected, so that the first heat-conducting film and the second heat-conducting film do not need to be bonded by an adhesive any more; the heat-conducting gasket has better transverse heat-conducting property and longitudinal heat-conducting property, excellent high-temperature stability, higher strength and better compressibility, so that the application scene of the heat-conducting gasket is expanded.

Description

Technical Field

[0001] This application relates to the field of thermal conductivity technology, and more specifically, to a thermally conductive pad. Background Technology

[0002] With the continuous advancement of technology, the integration and power consumption of electronic devices are constantly increasing, resulting in a significant amount of heat being generated during operation. If this heat cannot be dissipated effectively and promptly, it will lead to a decline in the performance of electronic devices and may even cause safety accidents. Therefore, effective heat dissipation has become a critical issue in the design and manufacturing of electronic devices.

[0003] In the field of nanotechnology, graphene has become a hot material for solving this problem due to its excellent thermal conductivity. Graphene is a two-dimensional carbon material with extremely high thermal conductivity, reaching over 5300 W / (m·K).

[0004] Existing graphene thermal pads mainly employ a multi-layer graphene film stacking method, using adhesives between the graphene films to improve their mechanical strength and thermal conductivity. However, the thermal conductivity of this structure is limited by the number of graphene film layers and the properties of the adhesive, and its lateral thermal conductivity is poor, with temperature resistance generally below 300℃, making it difficult to meet the requirements for high-temperature applications. Utility Model Content

[0005] The purpose of this application is to provide a thermally conductive pad that has both good lateral and longitudinal thermal conductivity, and excellent high-temperature stability.

[0006] In a first aspect, embodiments of this application provide a thermally conductive pad, which includes a first thermally conductive film, a second thermally conductive film, and a carbon nanotube assembly. The first and second thermally conductive films are spaced apart, and the carbon nanotube assembly is disposed between the first and second thermally conductive films. The carbon nanotube assembly includes a plurality of first carbon nanotubes and at least one second carbon nanotube. One end of the plurality of first carbon nanotubes is connected to the first thermally conductive film, and the other end abuts against the second thermally conductive film. One end of the at least one second carbon nanotube is connected to the second thermally conductive film, and the other end abuts against the first thermally conductive film. There is a gap between the plurality of first carbon nanotubes, and at least one second carbon nanotube is inserted into the gap to connect the first and second thermally conductive films.

[0007] In the above implementation process, the thermally conductive pad of this application forms a sandwich composite structure of graphene film-carbon nanotube-graphene film by setting a carbon nanotube group including multiple carbon nanotubes between the spaced first thermally conductive film and the second thermally conductive film. In the carbon nanotube group, multiple first carbon nanotubes are connected to the first thermally conductive film, and at least one second carbon nanotube is connected to the second thermally conductive film. The multiple first carbon nanotubes connected to the first thermally conductive film and the at least one second carbon nanotube connected to the second thermally conductive film cooperate with each other, so that the first thermally conductive film and the second thermally conductive film no longer need to be bonded with adhesive. The thermally conductive pad has both good lateral thermal conductivity and longitudinal thermal conductivity, and has excellent high temperature stability, high strength and good compressibility, thereby expanding the application scenarios of the thermally conductive pad.

[0008] In one possible implementation, the carbon nanotube assembly includes a plurality of second carbon nanotubes, a plurality of first carbon nanotubes, and a plurality of second carbon nanotubes interleaved.

[0009] In the above implementation process, when the carbon nanotube group includes multiple second carbon nanotubes and multiple first carbon nanotubes and multiple second carbon nanotubes are distributed in an alternating manner, there are multiple gaps between the multiple first carbon nanotubes, and multiple second carbon nanotubes are inserted into multiple gaps respectively, thereby improving the bonding between the multiple first carbon nanotubes and multiple second carbon nanotubes, making the structure of the entire thermal pad more stable.

[0010] In one possible implementation, the carbon nanotube arrays are distributed in an array.

[0011] In the above process, the arrayed carbon nanotubes are not only structurally stable, but also improve the strength and compressibility of the thermal pad.

[0012] In one possible implementation, the angle between the axis of the first carbon nanotube and the first thermally conductive film is 45° to 90°, and / or; the angle between the axis of the second carbon nanotube and the second thermally conductive film is 45° to 90°.

[0013] In the above implementation process, by keeping the angle between the axis of the first carbon nanotube and the first thermally conductive film and / or the angle between the axis of the second carbon nanotube and the second thermally conductive film within the above range, it is beneficial to make the thermally conductive pad take into account both thermal conductivity and compressibility.

[0014] In one possible implementation, the first thermally conductive film and the second thermally conductive film are parallel to each other.

[0015] In the above implementation process, making the first thermal conductive film and the second thermal conductive film parallel to each other helps to improve the uniformity of the entire thermal conductive pad.

[0016] In one possible implementation, the spacing between the first thermally conductive film and the second thermally conductive film is 50 μm to 1000 μm.

[0017] In the above implementation process, by keeping the spacing between the first thermally conductive film and the second thermally conductive film within the above range, it is beneficial to precisely control the height of the carbon nanotube assembly.

[0018] In one possible implementation, the thickness of the first thermally conductive film and / or the second thermally conductive film is 10 μm to 1000 μm.

[0019] In the above implementation process, by keeping the thickness of the first thermally conductive film and / or the second thermally conductive film within the above range, it is beneficial to improve the strength and compressibility of the thermally conductive pad.

[0020] In one possible implementation, the thickness of the first thermally conductive film and / or the second thermally conductive film is 30 μm to 100 μm.

[0021] In one possible implementation, the diameter of the carbon nanotubes is 1 nm to 1000 nm.

[0022] In one possible implementation, the first thermally conductive film and / or the second thermally conductive film are graphene films or boron nitride films.

[0023] In the above process, graphene film has good thermal conductivity, and boron nitride film has good insulation properties. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of the thermal pad according to an embodiment of this application;

[0026] Figure 2 This is a distribution diagram of the first carbon nanotubes on the first thermally conductive film of the first embodiment of this application;

[0027] Figure 3 This is a distribution diagram of the second carbon nanotubes on the second thermally conductive film of the first embodiment of this application;

[0028] Figure 4 This is a distribution diagram of the first carbon nanotubes on the first thermally conductive film of the second embodiment of this application;

[0029] Figure 5 This is a distribution diagram of the second carbon nanotubes on the second thermally conductive film of the second embodiment of this application.

[0030] Icons: 10 - Thermal pad; 100 - First thermal conductive film; 200 - Second thermal conductive film; 300 - Carbon nanotube assembly; 301 - Gap; 310 - First carbon nanotube; 320 - Second carbon nanotube. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0034] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0035] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0036] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0037] Graphene thermal pads have drawbacks such as poor lateral thermal conductivity and difficulty in meeting the requirements of high-temperature applications. In addition, due to their structure, graphene thermal pads often suffer from insufficient strength and compressibility, which limits their use in large-scale industrial applications.

[0038] Carbon nanotubes (CNTs) are nanomaterials composed of carbon atoms, possessing excellent mechanical, electrical, and thermal properties. Carbon nanotubes can be classified into single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). SWCNTs are more commonly used in practical applications due to their superior structural stability, high thermal conductivity, ease of fabrication, and functionalization.

[0039] This application proposes that combining graphene films and carbon nanotubes could improve the poor lateral thermal conductivity, insufficient strength, and inadequate compressibility of existing graphene thermal pads. However, the key lies in precisely designing the structures of the graphene films and carbon nanotubes.

[0040] Based on this, please refer to Figure 1 This application provides a thermally conductive pad 10, which includes a first thermally conductive film 100, a second thermally conductive film 200 and a carbon nanotube assembly 300. The first thermally conductive film 100 and the second thermally conductive film 200 are distributed at intervals, and the carbon nanotube assembly 300 is disposed between the first thermally conductive film 100 and the second thermally conductive film 200.

[0041] The first thermally conductive film 100 and / or the second thermally conductive film 200 are graphene films or boron nitride films. Graphene films have good thermal conductivity, while boron nitride films have good insulation properties.

[0042] Optionally, both the first thermal conductive film 100 and the second thermal conductive film 200 are graphene films.

[0043] The thickness of the first thermally conductive film 100 and / or the second thermally conductive film 200 is 10 μm to 1000 μm.

[0044] As an example, the thickness of the first thermally conductive film 100 and / or the second thermally conductive film 200 can be 10μm, 20μm, 50μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 600μm, 700μm, 800μm, 900μm or 1000μm.

[0045] Optionally, the thickness of the first thermal conductive film 100 and / or the second thermal conductive film 200 is 30 μm to 100 μm.

[0046] By ensuring that the thickness of the first thermally conductive film 100 and / or the second thermally conductive film 200 is within the aforementioned range, it is beneficial to improve the strength and compressibility of the thermally conductive pad 10.

[0047] Optionally, the first thermal conductive film 100 and the second thermal conductive film 200 are parallel to each other, which helps to improve the uniformity of the entire thermal conductive pad 10.

[0048] Optionally, the spacing between the first thermal conductive film 100 and the second thermal conductive film 200 is 50 μm to 1000 μm.

[0049] As an example, the spacing between the first thermal conductive film 100 and the second thermal conductive film 200 can be 50μm, 80μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 600μm, 700μm, 800μm, 900μm or 1000μm.

[0050] Optionally, the spacing between the first thermal conductive film 100 and the second thermal conductive film 200 is 50 μm to 500 μm.

[0051] By ensuring that the spacing between the first thermally conductive film 100 and the second thermally conductive film 200 is within the aforementioned range, it is beneficial to precisely control the height of the carbon nanotube assembly 300.

[0052] The carbon nanotube assembly 300 includes a plurality of first carbon nanotubes 310 and at least one second carbon nanotube 320. One end of the plurality of first carbon nanotubes 310 is connected to a first thermally conductive film 100 and the other end abuts against a second thermally conductive film 200. One end of at least one second carbon nanotube 320 is connected to the second thermally conductive film 200 and the other end abuts against the first thermally conductive film 100. A gap 301 is provided between the plurality of first carbon nanotubes 310. At least one second carbon nanotube 320 is inserted into the gap 301 so that the first thermally conductive film 100 and the second thermally conductive film 200 are connected.

[0053] Please see Figures 2-3Multiple first carbon nanotubes 310 are connected to the first thermal conductive film 100, and a gap 301 is formed between the multiple first carbon nanotubes 310. A second carbon nanotube 320 is connected to the second thermal conductive film 200. The second carbon nanotube 320 is used to insert into the gap 301 formed between the multiple first carbon nanotubes 310 so that the first thermal conductive film 100 and the second thermal conductive film 200 are connected.

[0054] Please see Figures 4-5 Multiple first carbon nanotubes 310 are connected to the first thermal conductive film 100, and multiple gaps 301 are formed between the multiple first carbon nanotubes 310. Multiple second carbon nanotubes 320 are connected to the second thermal conductive film 200. The multiple second carbon nanotubes 320 are used to be inserted into the multiple gaps 301 formed between the multiple first carbon nanotubes 310 in a one-to-one correspondence, so that the first thermal conductive film 100 and the second thermal conductive film 200 are connected.

[0055] Optionally, the multiple first carbon nanotubes 310 and multiple second carbon nanotubes 320 are staggered, which helps to improve the bonding between the multiple first carbon nanotubes 310 and multiple second carbon nanotubes 320, making the structure of the entire thermal pad 10 more stable.

[0056] Optionally, the carbon nanotube array 300 is distributed in an array. The arrayed carbon nanotube array 300 not only has a stable structure, but also improves the strength and compressibility of the thermal pad 10.

[0057] Optionally, the angle between the axis of the first carbon nanotube 310 and the first thermally conductive film 100 is 45° to 90°, and / or; the angle between the axis of the second carbon nanotube 320 and the second thermally conductive film 200 is 45° to 90°.

[0058] As an example, the angle between the axis of the first carbon nanotube 310 and the first thermally conductive film 100 and / or the angle between the axis of the second carbon nanotube 320 and the second thermally conductive film 200 can be 45°, 50°, 60°, 70°, 80° or 90°.

[0059] By ensuring that the angle between the axis of the first carbon nanotube 310 and the first thermally conductive film 100 and / or the angle between the axis of the second carbon nanotube 320 and the second thermally conductive film 200 are within the aforementioned range, it is advantageous to make the thermally conductive pad 10 balance thermal conductivity and compressibility.

[0060] Optionally, the diameter of the carbon nanotubes is 1 nm to 1000 nm.

[0061] As an example, the diameter of carbon nanotubes can be 1nm, 2nm, 5nm, 10nm, 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, or 1000nm.

[0062] The thermally conductive pad 10 of this application forms a sandwich composite structure of graphene film-carbon nanotube-graphene film by setting a carbon nanotube group 300 including multiple carbon nanotubes between a first thermally conductive film 100 and a second thermally conductive film 200 with spaced distribution. In the carbon nanotube group 300, multiple first carbon nanotubes 310 are connected to the first thermally conductive film 100, and at least one second carbon nanotube 320 is connected to the second thermally conductive film 200. The multiple first carbon nanotubes 310 connected to the first thermally conductive film 100 and the at least one second carbon nanotube 320 connected to the second thermally conductive film 200 cooperate with each other, so that the first thermally conductive film 100 and the second thermally conductive film 200 no longer need to be bonded with adhesive. The thermally conductive pad 10 has both good lateral thermal conductivity and longitudinal thermal conductivity, and has excellent high temperature stability, high strength and good compressibility, thereby expanding the application scenarios of the thermally conductive pad 10.

[0063] It should be noted that longitudinal thermal conductivity refers to the thermal conductivity of the heating pad 10 along its thickness direction, while transverse thermal conductivity refers to the thermal conductivity of the heating pad 10 along its direction perpendicular to its thickness direction.

[0064] The thermal pads of this application can be obtained by the following methods:

[0065] S1. Preparations

[0066] First, prepare a first thermally conductive film and a second thermally conductive film. The first thermally conductive film has a first surface, and the second thermally conductive film has a second surface. Multiple first regions that are separated from each other are set on the first surface, and multiple second regions that are separated from each other are set on the second surface. Then, catalysts for growing carbon nanotubes are set in the multiple first regions and multiple second regions respectively. Next, the first thermally conductive film and the second thermally conductive film are fixed on a special fixture at a certain distance apart, so that the first thermally conductive film and the second thermally conductive film are arranged opposite each other. At this time, the first surface is directly facing the second surface, and the projection of the first region of the first surface onto the second surface has no overlapping area with the second region and is staggered. Then, the special fixture containing the first thermally conductive film and the second thermally conductive film is placed in a container for chemical vapor deposition.

[0067] Optionally, before setting the catalyst in the first and second regions, the roughness of the first and second surfaces can be increased by surface treatment. This is beneficial to improving the adhesion and distribution uniformity of the catalyst on the first and second surfaces, thereby making it easier to precisely control the growth and arrangement of carbon nanotubes.

[0068] Optionally, the method of setting the catalyst in the first region and / or in multiple second regions includes: covering the first surface and / or the second surface with a mask, which facilitates the division of multiple first regions and / or second regions that are separated from each other; setting the catalyst on the first surface and / or the second surface, which enables the catalyst to be set in the first region and / or the second region; and finally removing the mask from the first surface and / or the second surface to enable the growth of carbon nanotubes.

[0069] Catalysts include solutions containing iron ions;

[0070] Optionally, the catalyst includes a ferric nitrate solution;

[0071] Optionally, the concentration of iron ions in the catalyst is 1 mol / L to 2 mol / L.

[0072] Optionally, the projections of multiple first regions on the first surface onto the second surface are arranged in an array with multiple second regions.

[0073] Since the chemical vapor deposition method is used to grow carbon nanotubes with the region containing the catalyst as the growth point, by making the orthogonal projection of multiple first regions on the first surface onto the second surface and multiple second regions in an array, it is possible to make the multiple carbon nanotubes grown from the first surface of the first thermally conductive film and the carbon nanotubes grown from the second surface of the second thermally conductive film in an array.

[0074] S2, Growth of carbon nanotubes

[0075] Multiple carbon nanotubes were grown between the first and second thermally conductive films using chemical vapor deposition.

[0076] Chemical vapor deposition involves first introducing a reducing gas to reduce iron ions in the catalyst to form iron nanoparticles, and then introducing a mixed gas including a carbon source gas and an inert gas, and holding at 600℃~800℃ for 30min~300min.

[0077] The reducing gas includes hydrogen, and the reduction time is 0.5h to 2h; the carbon source gas includes C2H2.

[0078] This preparation method involves first setting catalysts for growing carbon nanotubes in multiple separated first regions on the first surface of a first thermally conductive film and multiple separated second regions on the second surface of a second thermally conductive film. Then, multiple carbon nanotubes are grown between the first and second thermally conductive films using chemical vapor deposition. These carbon nanotubes are precisely arranged and distributed according to the catalyst positions, with some growing from the first surface of the first thermally conductive film and others from the second surface of the second thermally conductive film. The carbon nanotubes grown from the first and second surfaces are interleaved and interconnected, eliminating the need for adhesives to bond the first and second thermally conductive films. This preparation method is simple, reduces production costs, and improves production efficiency. The resulting thermally conductive pad has a sandwich composite structure of graphene film-carbon nanotube-graphene film, exhibiting good lateral and longitudinal thermal conductivity, excellent high-temperature stability, high strength, and good compressibility, thus expanding the application scenarios of thermally conductive pads.

[0079] The following describes a thermally conductive pad of this application in further detail with reference to embodiments.

[0080] Example 1

[0081] This application provides a thermally conductive pad and its preparation method, which includes the following steps:

[0082] S1. Preparations

[0083] First, prepare a first graphene film and a second graphene film, both with a thickness of 50 μm. The first graphene film has a first surface, and the second graphene film has a second surface. Perform plasma surface treatment on the first and second surfaces to improve their roughness. Cover the first and second surfaces with a mask. Divide the first surface into multiple separate first regions and the second surface into multiple separate second regions. Then, spray a 1 mol / L ferric nitrate solution onto the first and second surfaces respectively, so that the ferric nitrate solution is sprayed onto multiple first regions and multiple second regions. Remove the mask from the first and second surfaces. Next, fix the first and second graphene films 50 μm apart on a special fixture, so that the first and second graphene films are arranged opposite each other. At this time, the first surface is directly opposite the second surface, and the projection of the first region on the first surface onto the second surface has no overlap with the second region and is distributed in an array. Then, place the special fixture containing the first and second graphene films in a tube furnace.

[0084] S2, Growth of carbon nanotubes

[0085] The tube furnace was heated to 680℃, and H2 was passed through at a flow rate of 30 mL / min for 1 hour. Then, a mixture of C2H2 and Ar was introduced to start the reaction. The flow rate of C2H2 was 20 mL / min and the flow rate of Ar was 300 mL / min. After 30 minutes of reaction, multiple carbon nanotubes were grown between the first and second graphene films. The mixture was then cooled to room temperature to obtain a thermally conductive pad.

[0086] Example 2

[0087] This application provides a thermally conductive pad and its preparation method, which includes the following steps:

[0088] S1. Preparations

[0089] First, prepare a first graphene film and a second graphene film, both with a thickness of 50 μm. The first graphene film has a first surface, and the second graphene film has a second surface. Perform plasma surface treatment on the first and second surfaces to improve their roughness. Cover the first and second surfaces with a mask. Divide the first surface into multiple separate first regions and the second surface into multiple separate second regions. Then, spray a 1 mol / L ferric nitrate solution onto the first and second surfaces respectively, so that the ferric nitrate solution is sprayed onto multiple first regions and multiple second regions. Remove the mask from the first and second surfaces. Next, fix the first and second graphene films 300 μm apart on a special fixture, so that the first and second graphene films are arranged opposite each other. At this time, the first surface is directly opposite the second surface, and the projection of the first region on the first surface onto the second surface has no overlap with the second region and is distributed in an array. Then, place the special fixture containing the first and second graphene films in a tube furnace.

[0090] S2, Growth of carbon nanotubes

[0091] The tube furnace was heated to 680℃, and H2 was introduced at a flow rate of 30 mL / min for 1 h. Then, a mixture of C2H2 and Ar was introduced to start the reaction, with the flow rate of C2H2 being 20 mL / min and the flow rate of Ar being 300 mL / min. After 200 min of reaction, multiple carbon nanotubes were grown between the first and second graphene films. The mixture was then cooled to room temperature to obtain a thermally conductive pad.

[0092] Example 3

[0093] This application provides a comparative example of a thermally conductive pad and its preparation method, which includes the following steps:

[0094] S1. Preparations

[0095] First, prepare a first graphene film and a second graphene film, both with a thickness of 100 μm. The first graphene film has a first surface, and the second graphene film has a second surface. Perform plasma surface treatment on the first and second surfaces to improve their roughness. Cover the first surface with a mask and divide it into multiple separate first regions. Then, spray a 1 mol / L ferric nitrate solution onto the first surface, so that the ferric nitrate solution is sprayed onto multiple first regions and multiple second regions. Remove the mask from the first and second surfaces. Next, fix the first and second graphene films 50 μm apart on a special fixture, so that the first and second graphene films are arranged opposite each other, with the first surface facing the second surface. The projection of the first region on the first surface onto the second surface has no overlap with the second region and is distributed in an array. Then, place the special fixture containing the first and second graphene films in a tube furnace.

[0096] S2, Growth of carbon nanotubes

[0097] The tube furnace was heated to 680℃, and H2 was passed through at a flow rate of 30 mL / min for 1 hour. Then, a mixture of C2H2 and Ar was introduced to start the reaction. The flow rate of C2H2 was 20 mL / min and the flow rate of Ar was 300 mL / min. After reacting for 30 minutes, multiple carbon nanotubes were grown between the first and second graphene films. The mixture was then cooled to room temperature to obtain a thermally conductive pad.

[0098] Comparative Example 1

[0099] This application provides a comparative example of a thermally conductive pad and its preparation method, which includes the following steps:

[0100] S1. Preparations

[0101] First, prepare a first graphene film and a second graphene film, both with a thickness of 100 μm. The first graphene film has a first surface, and the second graphene film has a second surface. Perform plasma surface treatment on the first and second surfaces to improve their roughness. Cover the first and second surfaces with a mask. Divide the first surface into multiple separate first regions, which are arranged in an array. Then, spray a 1 mol / L ferric nitrate solution onto the first surface, ensuring that the ferric nitrate solution is sprayed onto the multiple first regions. Remove the mask from the first surface. Next, fix the first and second graphene films 50 μm apart on a special fixture, so that the first and second graphene films are arranged opposite each other. At this time, the first surface is directly opposite the second surface, and the projection of the first region on the first surface onto the second surface has no overlap with the second region and is arranged in an array. Then, place the special fixture containing the first and second graphene films in a tube furnace.

[0102] S2, Growth of carbon nanotubes

[0103] The tube furnace was heated to 680℃, and H2 was passed through at a flow rate of 30 mL / min for 1 hour. Then, a mixture of C2H2 and Ar was introduced to start the reaction. The flow rate of C2H2 was 20 mL / min and the flow rate of Ar was 300 mL / min. After 30 minutes of reaction, multiple carbon nanotubes were grown between the first and second graphene films. The mixture was then cooled to room temperature to obtain a thermally conductive pad.

[0104] Comparative Example 2

[0105] This application provides a thermally conductive pad and its preparation method in a comparative example. The method includes, based on Comparative Example 1, using an adhesive to bond the top end of a carbon nanotube to the second surface of a second graphene film to form a thermally conductive pad.

[0106] Experimental Example 1

[0107] The thermally conductive pads prepared in Examples 1-3 and Comparative Examples 1-2 were used to observe their structural stability and measure their transverse thermal conductivity, longitudinal thermal conductivity, compressibility, strength and high-temperature stability. The results are shown in Table 1.

[0108] The testing method is as follows:

[0109] 1. Transverse thermal conductivity and longitudinal thermal conductivity

[0110] Lateral thermal conductivity testing: The thermal diffusivity was tested using a Netzsch LFA467 instrument. The gasket was cut to a diameter of 25.4 mm, and the test mode was set to In-plane to measure the thermal diffusivity. Then, the specific heat capacity of the gasket was tested using DSC differential scanning calorimetry, and the density of the gasket was measured using the water displacement method. Finally, the thermal conductivity was calculated using the formula: thermal diffusivity * specific heat capacity * density.

[0111] Longitudinal thermal conductivity testing: The thermal diffusivity was tested using a Netzsch LFA467 instrument. The gasket was cut to a diameter of 12.7 mm, and the test mode was set to normal to obtain the thermal diffusivity. Then, the specific heat capacity of the gasket was tested using DSC differential scanning calorimetry, and the density of the gasket was tested using the water displacement method. Finally, the thermal conductivity was calculated using the formula: thermal diffusivity * specific heat capacity * density.

[0112] 2. Compression ratio

[0113] The compressibility test was performed using an INSTRON 6800 universal testing machine at a pressure of 20 psi. The compression ratio was calculated as (initial thickness - compressed thickness) * 100 / initial thickness.

[0114] 3. Strength

[0115] The material was cut into standard dumbbell shapes using a mechanical tensile testing machine for strength testing.

[0116] 4. High temperature stability

[0117] Place the thermal pad in a 300°C oven and bake for 1 hour, then observe its damage.

[0118] Table 1. Performance of thermal pads in Examples 1-3 and Comparative Examples 1-2

[0119]

[0120] As can be seen from Examples 1 to 3, the thermal pad structure of the embodiments of this application is stable, with no separation, and the transverse thermal conductivity is 1900W / mK to 1950W / mK, the longitudinal thermal conductivity is 1320W / mK to 1450W / mK, the compression ratio is 62.5% to 75.8%, the strength is 0.24MPa to 0.43MPa, and the high temperature stability is good.

[0121] As can be seen from the comparison between Comparative Example 1 and Example 1, Comparative Example 1 only sets a catalyst on the first graphene film and grows carbon nanotubes by chemical vapor deposition. The carbon nanotubes grown on the first graphene film in the thermal pad cannot be combined with the second graphene film, that is, they are in a separated state.

[0122] As can be seen from the comparison between Comparative Example 2 and Example 1, all carbon nanotubes in Comparative Example 2 are grown on the first graphene film, and the top ends of the carbon nanotubes are bonded to the second graphene film by an adhesive to make the first graphene film and the second graphene film stably linked. The thermal conductivity of the thermal pad of Comparative Example 2 is only 1350 W / mK in the lateral direction and only 950 W / mK in the longitudinal direction, which is far lower than the thermal conductivity of the thermal pad of Example 1 in the lateral direction and the longitudinal direction.

[0123] The above description is merely a specific embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A thermally conductive pad, characterized in that, The thermally conductive pad includes a first thermally conductive film, a second thermally conductive film, and a carbon nanotube assembly. The first and second thermally conductive films are spaced apart, and the carbon nanotube assembly is disposed between the first and second thermally conductive films. The carbon nanotube assembly includes a plurality of first carbon nanotubes and at least one second carbon nanotube. One end of the plurality of first carbon nanotubes is connected to the first thermally conductive film, and the other end abuts against the second thermally conductive film. One end of the at least one second carbon nanotube is connected to the second thermally conductive film, and the other end abuts against the first thermally conductive film. There are gaps between the plurality of first carbon nanotubes, and the at least one second carbon nanotube is inserted into the gaps to connect the first and second thermally conductive films.

2. The thermally conductive pad according to claim 1, characterized in that, The carbon nanotube assembly includes a plurality of second carbon nanotubes, wherein the plurality of first carbon nanotubes and the plurality of second carbon nanotubes are distributed alternately.

3. The thermally conductive pad according to claim 1, characterized in that, The carbon nanotube arrays are distributed in an array.

4. The thermally conductive pad according to claim 1, characterized in that, The angle between the axis of the first carbon nanotube and the first thermally conductive film is 45° to 90°, and / or; the angle between the axis of the second carbon nanotube and the second thermally conductive film is 45° to 90°.

5. The thermally conductive pad according to claim 1, characterized in that, The first thermally conductive film and the second thermally conductive film are parallel to each other.

6. The thermally conductive pad according to claim 5, characterized in that, The distance between the first thermal conductive film and the second thermal conductive film is 50μm to 1000μm.

7. The thermally conductive pad according to claim 1, characterized in that, The thickness of the first thermal conductive film and / or the second thermal conductive film is 10 μm to 1000 μm.

8. The thermally conductive pad according to claim 7, characterized in that, The thickness of the first thermal conductive film and / or the second thermal conductive film is 30 μm to 100 μm.

9. The thermally conductive pad according to claim 1, characterized in that, The diameter of the carbon nanotubes ranges from 1 nm to 1000 nm.

10. The thermally conductive pad according to claim 1, characterized in that, The first thermally conductive film and / or the second thermally conductive film are graphene films or boron nitride films.

Images