A high-rebound and low-thermal-resistance interface material and its preparation method

Abstract

The present application relates to a high-elasticity and low-thermal-resistance interface material and a preparation method thereof, belonging to the field of thermal conductive materials. The high-elasticity and low-thermal-resistance interface material includes a graphene thermal conductive film, and a plurality of thermal conductive holes are formed through the graphene thermal conductive film. The thermal conductive holes are filled with a thermal conductive paste, and the thermal conductive paste includes the following raw materials in parts by weight: 50 to 700 parts of carbon fiber; 500 to 1700 parts of thermal conductive powder; 50 to 120 parts of silicone oil; 0.3 to 2 parts of coupling agent; 1 to 4 parts of curing agent; 0.1 to 1 part of inhibitor; 1 to 4 parts of catalyst; the carbon fibers are arranged in the direction of the opening of the thermal conductive holes. The present application uses the graphene thermal conductive film as a thermal conductive matrix, and by forming thermal conductive holes thereon and filling the thermal conductive paste, the carbon fibers in the thermal conductive paste are arranged in the vertical direction of the graphene thermal conductive film, providing good heat conduction effect in the vertical direction for the graphene thermal conductive film, and improving the overall thermal conductivity and compression and rebound performance of the graphene thermal conductive film.

Description

Technical Field

[0001] The present application relates to the field of thermal conductive materials, and in particular to a high-rebound low-thermal-resistance interface material and a preparation method thereof. Background Art

[0002] With the advent of the 5G era, the working frequency of electronic chips has been continuously increasing, and electronic products are gradually developing towards lightweight and high-integration, resulting in a substantial increase in the heat generation of devices. If the excess heat is not conducted away in time, it will greatly affect the working state of electronic components, and in severe cases, it may even cause failure and reduced lifespan. To solve this problem, thermal interface materials have emerged. However, the thermal conductivity of traditional thermal interface materials is low, mainly concentrated in the range of 1-10 W, making it difficult to meet the high heat conduction requirements.

[0003] Graphene is a new type of carbon material with a single-layer two-dimensional honeycomb lattice structure formed by stacking carbon atoms. It not only has excellent mechanical, optical, electrical and other properties, but also has good thermal properties. The theoretical thermal conductivity can reach 5300 W / (m·K), which is more than ten times that of common metal materials. Currently, the in-plane thermal conductivity of porous graphene membranes developed from graphene as raw materials can reach up to more than 1000 W / (m·K), having good heat transfer effects and good compressibility. However, the through-thickness thermal conductivity of porous graphene membranes is relatively low, usually less than 10 W / (m·K), making it difficult to meet the heat transfer brought by high heat flux density in the thickness direction. Moreover, after being compressed in the thickness direction, its rebound effect is very poor, making it difficult to well fill the gap tolerance between the chip and the heat dissipation device, resulting in the heat generated at the interface being difficult to transfer out well, affecting the heat dissipation performance of electronic products. Summary of the Invention

[0004] In view of the above technical problems, the present application provides a high-rebound low-thermal-resistance interface material and a preparation method thereof, which can provide good rebound effect while having good thermal conductivity, can fully fill the gap between the chip and the heat dissipation device, and improve the thermal conductivity.

[0005] In a first aspect, the present application provides a high-rebound low-thermal-resistance interface material, adopting the following technical solution:

[0006] A high-rebound low-thermal-resistance interface material includes a graphene thermal conductive film, and a plurality of thermal conductive holes are penetrated through the graphene thermal conductive film, and the thermal conductive holes are filled with a thermal conductive paste;

[0007] The thermal conductive paste includes the following raw materials in parts by weight:

[0008] 50-700 parts of carbon fiber;

[0009] 500-1700 parts of thermal conductive powder;

[0010] 50 - 120 parts of silicone oil;

[0011] 0.3 - 2 parts of coupling agent;

[0012] 1 - 4 parts of curing agent;

[0013] 0.1 - 1 part of inhibitor;

[0014] 1 - 4 parts of catalyst;

[0015] The carbon fiber is arranged in the direction of the opening of the heat conduction hole.

[0016] By adopting the above technical solution, graphene has good thermal conductivity. However, the thermal conductivity of graphene is anisotropic. Its thermal conductivity in the horizontal direction is excellent, and the graphene thermal conductive film made of it has a good thermal conduction effect in the horizontal direction. By punching holes in the graphene film and filling it with a thermal conductive paste, the heat conduction holes are perpendicular to the plane direction of the graphene thermal conductive film, which can provide a good thermal conduction effect for the graphene thermal conductive film in the direction perpendicular to its plane, thereby making up for the deficiency of the thermal conductivity of the graphene thermal conductive film in the vertical direction. The thermal conductive paste uses silicone oil as the main dispersion material. By adding carbon fiber to it and arranging the carbon fiber in a directional manner so that it extends and distributes along the opening direction of the heat conduction hole, since carbon fiber itself is also an anisotropic thermal conductive material, after the directional arrangement, the thermal conductive paste filled in the heat conduction hole has a good heat conduction effect in the vertical direction of the graphene thermal conductive film, thereby improving the thermal conductivity of the graphene thermal conductive film in the vertical direction. Further adding a thermal conductive powder to the thermal conductive paste, the thermal conductive powder is in a granular shape as a whole. While enhancing the thermal conductivity of the thermal conductive paste filled in the heat conduction hole, the thermal conductive powder can play a role in connecting adjacent carbon fibers, improving the continuity of the carbon fiber in the heat conduction hole, and further improving the thermal conductivity of the graphene thermal conductive film in the vertical direction.

[0017] After the silicone oil is cured, it has good elasticity itself. After filling it in the heat conduction hole, it can form a support skeleton with good elasticity in the thermal conductive film, significantly improving the resilience performance of the thermal conductive film in the vertical direction. And because there is carbon fiber arranged in the heat conduction hole, it can provide a further elastic effect for the graphene thermal conductive film, further improving the resilience performance of the graphene thermal conductive film.

[0018] Optionally, the graphene thermal conductive film is prepared by the following method:

[0019] S1. Take the graphene oxide slurry and coat it to obtain a graphene oxide coating film;

[0020] S2. Dry the graphene oxide coating film to remove the moisture in it to obtain a graphene oxide film;

[0021] S3. Graphitize the graphene oxide film at 2500 - 3500 °C to obtain a graphene thermal conductive film.

[0022] Optionally, the graphene oxide slurry is a graphene oxide aqueous slurry, and the solid content of graphene oxide is 0.1 - 15 wt%, further preferably 5 - 10 wt%.

[0023] Optionally, in step S2, the drying temperature of the graphene oxide coating film is 80 - 150 °C, further preferably 100 - 120 °C.

[0024] Optionally, in step S3, the duration of graphitization is 4 - 10 h, further preferably 8 - 10 h.

[0025] By adopting the above technical solution, the graphene thermal conductive film is obtained by coating and drying the graphene oxide slurry followed by graphitization. Graphene oxide can be well dispersed in water to form a slurry. When preparing the graphene thermal conductive film by the coating process, the layered graphene oxide is oriented along the horizontal plane direction during the coating process, so that the obtained graphene thermal conductive film has better heat conduction effect in the horizontal direction, improving the thermal conductivity of the graphene thermal conductive film in the plane direction of the film layer. Compared with the traditional preparation process of bonding multi-layer graphene films, the graphene thermal conductive film prepared by the coating process has a smaller thermal resistance between graphene film layers, and the graphene sheets have better orientation in the horizontal direction, showing a better heat conduction effect.

[0026] Limiting the solid content of graphene oxide in the graphene oxide slurry within the range of 0.1 - 15 wt%, and further preferably 5 - 10 wt%, can make the obtained coating film have a better coating effect, the structural strength of the formed film layer is better, and better horizontal thermal conductivity can be obtained.

[0027] During the graphitization process, the originally randomly distributed carbon atoms in graphene oxide are arranged neatly through high temperature, and the carbon material will transform from the two-dimensional structure of the carbon network to a three-dimensional ordered structure through the growth of "microcrystals". The mechanical properties and strength of the graphene thermal conductive film are effectively improved, and the thermal resistance between the graphene oxide film layers is significantly reduced, and the thermal conductivity in both the horizontal and vertical directions is effectively improved.

[0028] Optionally, the thickness of the graphene thermal conductive film is 10 - 1000 μm.

[0029] Further preferably, the thickness of the graphene thermal conductive film is 50 - 300 μm.

[0030] By adopting the above technical solution, within this thickness range, the graphene sheets in the graphene thermal conductive film have better orientation, the heat conduction effect in the horizontal direction of the graphene thermal conductive film is better, and it has better mechanical properties.

[0031] Optionally, the thermal conductive paste is prepared by the following method:

[0032] Mix carbon fiber, thermal conductive powder, silicone oil, coupling agent, curing agent, and inhibitor evenly according to the ratio, and then add a catalyst and mix evenly to obtain the thermal conductive paste.

[0033] Optionally, the carbon fiber has a diameter of 5 - 20 μm and a length of 50 - 300 μm. The thermal conductivity of the carbon fiber is not less than 900 W / (m·k).

[0034] By adopting the above technical solution, the length of the carbon fiber matches the thickness of the graphene thermal conductive film. Without exceeding the thickness range of the graphene thermal conductive film, it penetrates both sides of the graphene thermal conductive film as much as possible, providing a good heat conduction effect for the graphene thermal conductive film in the vertical direction.

[0035] Optionally, the thermal conductive powder is one or a combination of more of alumina, zinc oxide, magnesium oxide, aluminum nitride, graphite, graphene, aluminum powder, copper powder, and silver-coated aluminum powder.

[0036] Optionally, the average particle size of the thermal conductive powder is 1 - 15 μm.

[0037] By adopting the above technical solution, the above thermal conductive powders all have good heat conduction effects and can be evenly dispersed in silicone oil, further improving the thermal conductivity of the thermal conductive paste. Limiting the average particle size of the thermal conductive powder within the above range can avoid the agglomeration phenomenon caused by too small particle size and difficulty in dispersion, and can also avoid too large particle size affecting the filling and thermal conductivity of the thermal conductive paste.

[0038] Optionally, the viscosity of the silicone oil is 100 - 300 mPa·s.

[0039] By adopting the above technical solution, limiting the viscosity of the silicone oil within the above range gives it appropriate fluidity, which can well fill the thermal conductive holes. And part of the thermal conductive paste will penetrate into the pores inside the graphene thermal conductive film during the filling process, thereby reducing the air thermal resistance inside the graphene thermal conductive film and improving the interlayer thermal conductivity. When the viscosity of the silicone oil is too high, its fluidity becomes poor and it cannot completely fill the gaps of the thermal conductive holes, while when the viscosity is too low, it is extremely easy to flow and the processing difficulty becomes greater.

[0040] Optionally, the coupling agent is a silane coupling agent containing vinyl functional groups.

[0041] Optionally, the curing agent is hydrogen-containing silicone oil, and the hydrogen content of the hydrogen-containing silicone oil is 0.05 - 0.25%.

[0042] Optionally, the inhibitor is ethynylcyclohexanol.

[0043] Optionally, the catalyst is a platinum catalyst.

[0044] By adopting the above technical solution, through the optimization of raw materials, the curing effect of the thermal conductive paste can be further improved, so that the thermal conductive paste has good resilience performance after curing in the thermal conduction holes, and the compression resilience rate of the graphene thermal conductive film is improved.

[0045] Optionally, the aperture of the thermal conduction holes is 0.05 - 2 mm.

[0046] More preferably, the aperture of the thermal conduction holes is 0.2 - 0.4 mm.

[0047] Optionally, the distance between adjacent thermal conduction holes is 0.2 - 1 mm.

[0048] More preferably, the distance between adjacent thermal conduction holes is 0.3 - 0.5 mm.

[0049] By adopting the above technical solution, if the aperture of the thermal conduction holes is too small, it will lead to greater difficulty in filling the thermal conductive paste, and it is difficult to orient the carbon fibers in the thermal conduction holes, affecting the thermal conductivity and overall resilience performance of the graphene thermal conductive film in the vertical direction; if the aperture of the thermal conduction holes is too large, it will lead to too much thermal conductive paste filled inside the graphene thermal conductive film, and it will damage the structure of the graphene thermal conductive film, affecting the thermal conductivity of the graphene thermal conductive film in the horizontal direction. Similarly, the distance between the thermal conduction holes also affects the thermal conductivity and compression resilience performance of the graphene thermal conductive film. By limiting the aperture of the thermal conduction holes and the distance between the thermal conduction holes within the above ranges, better thermal conductivity and compression resilience performance can be achieved.

[0050] In a second aspect, the present application provides a method for preparing a low-resilience and low-thermal-resistance interface material, adopting the following technical solution:

[0051] A method for preparing a low-resilience and low-thermal-resistance interface material, comprising the following steps:

[0052] S1. Prepare a graphene thermal conductive film;

[0053] S2. Open thermal conduction holes in the graphene thermal conductive film obtained in step S1;

[0054] S3. Fill the thermal conduction holes with the thermal conductive paste by means of dispensing, and make the carbon fibers arranged in the direction of the opening of the thermal conduction holes, and then obtain a high-resilience and low-thermal-resistance interface material after curing.

[0055] Optionally, in step S2, the thermal conduction holes are opened by mechanical drilling or laser drilling, preferably laser drilling.

[0056] Optionally, in step S3, the thermal conductive paste is filled by a precision dispensing machine, and the diameter of the dispensing nozzle on the dispensing device is 0.01 - 0.03 mm smaller than the aperture of the thermal conductive hole.

[0057] Optionally, in step S3, the curing temperature of the thermal conductive paste is 80 - 150 °C.

[0058] By adopting the above technical solution, the thermal conductive paste is filled into the thermal conductive holes by the method of dispensing with a precision dispensing machine. During the dispensing process, the carbon fibers in the thermal conductive paste will adjust their directions and arrange along the extrusion direction as the thermal conductive paste moves in the dispensing nozzle, realizing the directional arrangement of the carbon fibers. After the thermal conductive paste is dispensed and filled into the thermal conductive holes, the carbon fibers can be arranged along the opening direction of the thermal conductive holes in the thermal conductive holes, effectively improving the thermal conductivity of the thermal conductive paste on the vertical graphene thermal conductive film. The diameter of the dispensing nozzle is slightly smaller than the aperture of the thermal conductive hole, which can ensure that the dispensing nozzle can completely extend into the thermal conductive hole, improving the dispensing efficiency and accuracy.

[0059] Optionally, in step S2, after the thermal conductive holes are formed on the graphene thermal conductive film, surface treatment is carried out in an ozone environment. The ozone treatment time is 1 - 5 h, and the ozone concentration is 30 - 90%.

[0060] Further preferably, the ozone treatment time is 2 - 3 h, and the ozone concentration is 60 - 80%.

[0061] By adopting the above technical solution, surface activation treatment of the graphene thermal conductive film is carried out through ozone treatment, so that more active groups are generated on the pore walls of the thermal conductive holes. After filling the thermal conductive paste, graft bonding can occur with raw materials such as silicone oil, enhancing the bonding force between the thermal conductive paste and the graphene thermal conductive film, and further improving the strength and stability of the overall structure.

[0062] Optionally, in step S3, the thermal conductive paste is subjected to vacuum treatment before being filled into the thermal conductive holes.

[0063] By adopting the above technical solution, the gas generated during the mixing process of the thermal conductive paste can be removed through vacuum treatment, avoiding the occurrence of air bubbles and voids inside after the thermal conductive paste is filled into the thermal conductive holes and cured, which affects its thermal conductivity.

[0064] In summary, the present application includes at least one of the following beneficial technical effects:

[0065] 1. In the technical solution of the present application, with the graphene thermal conductive film as the thermal conductive matrix, by forming thermal conductive holes on it and filling the thermal conductive paste, the carbon fibers in the thermal conductive paste are arranged directionally along the vertical direction of the graphene thermal conductive film in the thermal conductive holes, providing good heat conduction effect for the graphene thermal conductive film in the vertical direction, and thus improving the overall thermal conductivity of the graphene thermal conductive film.

[0066] 2. In the technical solution of this application, the graphene thermal conductive film is prepared by processes such as coating, drying, and graphitization of graphene oxide slurry. The graphene thermal conductive film has high integrity, low interlayer thermal resistance, and high overall strength and stability.

[0067] 3. In the technical solution of this application, the thermal conductive paste is filled into the thermal conductive holes by means of dispensing. During the process of dispensing and filling with a precision dispenser, the carbon fibers in the thermal conductive paste adjust their arrangement directions along with the flow of the thermal conductive paste, so that the carbon fibers are arranged in a direction along the flow direction of the thermal conductive paste. After being filled into the thermal conductive holes, the carbon fibers are arranged in a direction along the opening direction of the thermal conductive holes, providing a good thermal conduction effect for the graphene thermal conductive film in the vertical direction. This method is simple and efficient, and can achieve a good directional arrangement effect of the carbon fibers. Description of the Drawings

[0068] Figure 1 It is a schematic diagram of the overall structure of the high-elasticity and low-thermal-resistance interface material in the embodiment of this application.

[0069] Figure 2 It is a cross-sectional view of the high-elasticity and low-thermal-resistance interface material in the embodiment of this application.

[0070] Description of the reference numerals: 1. Graphene thermal conductive film; 2. Thermal conductive hole. Detailed Description of the Embodiment

[0071] The following further describes this application in detail with reference to the drawings and specific embodiments.

[0072] Preparation Example of Graphene Thermal Conductive Film

[0073] Preparation Example 1

[0074] The preparation method of the graphene thermal conductive film is as follows:

[0075] S1. Take graphene oxide aqueous slurry with a solid content of 0.1 wt%, and coat it into a film using a precision coater, with a coating thickness of 1000 μm;

[0076] S2. Dry the coated graphene oxide coating film in an oven at 100 °C to completely remove moisture, obtaining a graphene oxide film;

[0077] S3. Place the graphene oxide film in a heat treatment furnace and perform graphitization treatment at 2800 °C for 4 hours to obtain the graphene thermal conductive film.

[0078] Preparation Example 2

[0079] The difference between this preparation example and Preparation Example 1 is that the solid content of the graphene aqueous slurry is 15 wt%, and the rest are the same as those in Example 1.

[0080] Preparation Example 3

[0081] The difference between this Preparation Example and Preparation Example 1 is that the solid content of the graphene aqueous slurry is 5 wt%, and the rest is the same as in Example 1.

[0082] Preparation Example 4

[0083] The difference between this Preparation Example and Preparation Example 1 is that the graphene thermal conductive film is not graphitized during the preparation process. The specific preparation method is as follows:

[0084] S1. Take the graphene oxide aqueous slurry and coat it into a film using a precision coater;

[0085] S2. Dry the coated graphene oxide film in an oven at 100 °C to completely remove the moisture and obtain the graphene thermal conductive film.

[0086] The rest is the same as in Preparation Example 1.

[0087] Preparation Example 5

[0088] The difference between this Preparation Example and Preparation Example 1 is that the graphene thermal conductive film is prepared by laminating and bonding multiple graphene films. The specific preparation method is as follows:

[0089] Lay up commercially available graphene films with a thickness of 50 μm, and fix them by gluing with an adhesive between adjacent layers. The adhesive is an organic silicone adhesive, and the total thickness of the lay-up is 1000 μm.

[0090] The rest is the same as in Preparation Example 1.

[0091] Preparation Examples of Thermal Conductive Paste

[0092] Preparation Examples 6 - 9

[0093] In Preparation Examples 6 - 9, the raw material component ratio of the thermal conductive paste refers to Table 1. The specific preparation method is as follows:

[0094] Mix carbon fiber, thermal conductive powder, silicone oil, coupling agent, curing agent, and inhibitor evenly according to the ratio, and then add a catalyst and mix evenly to obtain the thermal conductive paste.

[0095] Among them, the diameter of the carbon fiber is 5 - 6 μm, and the length is 55 ± 5 μm;

[0096] The thermal conductive powder is a mixture of alumina and aluminum nitride with a mass ratio of 1:1, and the average particle size of the thermal conductive powder is 1 μm;

[0097] The viscosity of the silicone oil is 100 mPa·s;

[0098] The coupling agent is vinyltrichlorosilane;

[0099] The curing agent is a hydrogen-containing silicone oil with a hydrogen content of 0.05%;

[0100] The inhibitor is ethynylcyclohexanol;

[0101] The catalyst is a platinum catalyst.

[0102] Table 1: Raw material component ratios of Preparation Examples 6 - 9 (unit: g)

[0103] carbon fiber thermal conductive powder silicone oil coupling agent curing agent inhibitor catalyst Preparation Example 6 50 1700 120 2 4 1 4 Preparation Example 7 700 500 50 0.3 1 0.1 1 Preparation Example 8 450 1250 80 1.5 2 0.5 2 Preparation Example 9 550 1050 100 1.5 2.5 0.5 2

[0104] Preparation Example 10

[0105] The difference between this preparation example and Preparation Example 9 is that the length of the carbon fiber is 300 ± 10 μm and the diameter is 15 - 20 μm, and the rest are the same as Preparation Example 9.

[0106] Preparation Example 11

[0107] The difference between this preparation example and Preparation Example 9 is that the length of the carbon fiber is 200 ± 10 μm and the diameter is 10 - 15 μm, and the rest are the same as Preparation Example 9.

[0108] Preparation Example 12

[0109] The difference between this preparation example and Preparation Example 9 is that no carbon fiber is added, and the rest are the same as Preparation Example 9.

[0110] Preparation Example 13

[0111] The difference between this preparation example and Preparation Example 9 is that the average particle size of the heat-conducting powder is 10 μm, and the rest are the same as Preparation Example 9.

[0112] Preparation Example 14

[0113] The difference between this preparation example and Preparation Example 9 is that the average particle size of the heat-conducting powder is 15 μm, and the rest are the same as Preparation Example 9.

[0114] Preparation Example 15

[0115] The difference between this preparation example and Preparation Example 9 is that no heat-conducting powder is added, and the rest are the same as Preparation Example 9.

[0116] Preparation Example 16

[0117] The difference between this preparation example and Preparation Example 9 is that the viscosity of the silicone oil is 300 mPa·s, and the rest are the same as Preparation Example 9.

[0118] Preparation Example 17

[0119] The difference between this preparation example and Preparation Example 9 is that the viscosity of the silicone oil is 200 mPa·s, and the rest are the same as Preparation Example 9.

[0120] Example 1

[0121] A high-elasticity and low-thermal-resistance interface material, the structure of which refers to Figure 1 , including a graphene thermal conductive film 1, the graphene thermal conductive film 1 is prepared by Preparation Example 1, a plurality of thermal conductive holes 2 are formed through the graphene thermal conductive film 1, the aperture of the thermal conductive holes 2 is 0.2 mm, and the distance between the edges of adjacent thermal conductive holes 2 is 0.3 mm. The thermal conductive holes 2 are filled with a thermal conductive paste, and the thermal conductive paste is prepared by Preparation Example 6. The specific preparation method of the high-elasticity and low-thermal-resistance interface material is as follows:

[0122] S1. Take the graphene thermal conductive film 1 prepared by Preparation Example 1, and form thermal conductive holes 2 on it by laser drilling;

[0123] S2. Load the thermal conductive paste into a precision dispensing machine, and inject the thermal conductive paste into the thermal conductive holes 2 by precision dispensing;

[0124] S3. Place the graphene thermal conductive film filled with the thermal conductive paste in an oven, and heat and cure it at 100 °C to obtain the high-elasticity and low-thermal-resistance interface material.

[0125] Example 2

[0126] The difference between this example and Example 1 is that the graphene thermal conductive film is prepared by Preparation Example 2, and the rest are the same as those in Example 1.

[0127] Example 3

[0128] The difference between this example and Example 1 is that the graphene thermal conductive film is prepared by Preparation Example 3, and the rest are the same as those in Example 1.

[0129] Example 4

[0130] The difference between this example and Example 1 is that the graphene thermal conductive film is prepared by Preparation Example 4, and the rest are the same as those in Example 1.

[0131] Example 5

[0132] The difference between this example and Example 1 is that the graphene thermal conductive film is prepared by Preparation Example 5, and the rest are the same as those in Example 1.

[0133] Example 6

[0134] The difference between this example and Example 3 is that the thickness of the graphene thermal conductive film is 10 μm, and the rest are the same as those in Example 3.

[0135] Example 7

[0136] The difference between this example and Example 3 is that the thickness of the graphene thermal conductive film is 500 μm, and the rest are the same as those in Example 3.

[0137] Example 8

[0138] The difference between this embodiment and Embodiment 3 is that the thickness of the graphene thermal conductive film is 200 μm, and the rest is the same as that of Embodiment 3.

[0139] Comparative Example 1

[0140] The difference between this Comparative Example 1 and Embodiment 1 is that the high resilience and low thermal resistance interface material only includes the graphene thermal conductive film, and no thermal conductive holes are formed in the graphene thermal conductive film, nor is it filled with thermal conductive paste.

[0141] Performance testing

[0142] Performance testing was carried out on the prepared interface material, and the testing items are as follows:

[0143] Thermal conductivity: The thermal resistance of the sample in the thickness direction was tested according to the ASTM-D 5470 standard;

[0144] Compression and resilience performance: The resilience rate was tested according to the ASTM D 575-91 standard;

[0145] Mechanical properties: The tensile strength of the sample was tested according to the ASTM-D 412 standard;

[0146] The performance testing results of Embodiments 1 to 8 and Comparative Example 1 are shown in Table 2 below.

[0147] Table 2: Performance testing results of Embodiments 1 to 8 and Comparative Example 1

[0148] Thermal resistance (℃·cm2 / W) Tensile strength (MPa) Rebound rate (%) Example 1 0.29 0.31 80.1 Example 2 0.30 0.30 81.8 Example 3 0.29 0.32 82.5 Example 4 0.39 0.24 80.9 Example 5 0.42 0.36 56.2 Example 6 0.33 0.27 75.3 Example 7 0.28 0.33 82.4 Example 8 0.29 0.34 82.8 Comparative Example 1 0.45 0.33 15.1

[0149] It can be seen from the data in Table 2 that in the technical solution of the present application, by forming thermal conductive holes in the graphene thermal conductive film and filling them with thermal conductive paste, the thermal conductivity and compression and resilience performance of the interface material can be improved well. And it can be seen from the data in Embodiment 1 and Embodiment 5 that the graphene thermal conductive film made by the coating process has a lower thermal resistance in the thickness direction (i.e., the direction perpendicular to the plane of the graphene thermal conductive film) and better resilience performance. This may be because the graphene thermal conductive film made by the coating process does not contain an adhesive layer, resulting in a lower interlayer thermal resistance of the graphene thermal conductive film, and the elastic support structure formed after the thermal conductive paste filled in the thermal conductive holes is cured also further improves the compression and resilience performance of the interface material.

[0150] Embodiments 9 to 17

[0151] The difference between Embodiments 9 to 17 and Embodiment 8 is that the sources of the thermal conductive paste are different. Specifically, refer to Table 3, and the rest is the same as that of Embodiment 8.

[0152] Table 3: Sources of thermal conductive paste for Embodiments 9 to 17

[0153] Example Preparation Example of Thermal Conductive Paste Example 9 Preparation Example 7 Example 10 Preparation Example 8 Example 11 Preparation Example 9 Example 12 Preparation Example 10 Example 13 Preparation Example 11 Example 14 Preparation Example 13 Example 15 Preparation Example 14 Example 16 Preparation Example 16 Example 17 Preparation Example 17

[0154] Comparative Example 2

[0155] The difference between this comparative example and Example 8 is that the thermal conductive paste is prepared from Preparation Example 12, and the rest are the same as those in Example 8.

[0156] Comparative Example 3

[0157] The difference between this comparative example and Example 8 is that the thermal conductive paste is prepared from Preparation Example 15, and the rest are the same as those in Example 8.

[0158] Perform performance tests on the interface materials prepared in Examples 9 to 17 and Comparative Examples 2 and 3. The test results are shown in Table 4 below.

[0159] Table 4: Performance test results of Examples 9 to 17 and Comparative Examples 2 and 3

[0160]

[0161]

[0162] It can be seen from the data in Table 4 that the carbon fiber and the thermal conductive paste in the thermal conductive paste can provide good heat conduction effect for the graphene thermal conductive film in the thickness direction, improve the overall thermal conductivity of the interface material, and make up for the deficiency of poor thermal conductivity of graphene in the vertical direction. And the addition of carbon fiber and thermal conductive powder can further improve the compression and rebound performance of the interface material.

[0163] Example 18

[0164] The difference between this example and Example 17 is that after the heat conduction holes are opened in the graphene thermal conductive film, it is also treated with ozone. Specifically:

[0165] S1. Take the graphene thermal conductive film and punch holes in it by laser drilling;

[0166] S2. Treat the surface activity of the graphene thermal conductive film in an ozone machine, with an ozone concentration of 60% and a treatment time of 2 h;

[0167] S3. Load the thermal conductive paste into a precision dispensing machine and inject the thermal conductive paste into the ozone-treated heat conduction holes through the precision dispensing machine;

[0168] S4. Place the graphene thermal conductive film filled with the thermal conductive paste in an oven and heat and cure it at 100 °C to obtain a high-rebound and low-thermal-resistance interface material.

[0169] The rest are the same as those in Example 17.

[0170] Example 19

[0171] The difference between this embodiment and Embodiment 18 is that the thermal conductive paste is subjected to vacuum treatment before being filled into the thermal conductive holes. Specifically:

[0172] S1. Take a graphene thermal conductive film and punch holes in it by means of laser drilling;

[0173] S2. Subject the graphene thermal conductive film to surface activation treatment in an ozone machine with an ozone concentration of 60% and a treatment time of 2 h;

[0174] S3. Subject the thermal conductive paste to vacuum treatment. After completion, load the thermal conductive paste into a precision dispensing machine and inject it into the thermal conductive holes by dispensing with the precision dispensing machine;

[0175] S4. Place the graphene thermal conductive film filled with the thermal conductive paste in an oven and heat and cure it at 100 °C to obtain a high-elasticity and low-thermal-resistance interface material.

[0176] The rest are the same as those in Embodiment 18.

[0177] Embodiment 20

[0178] The difference between this embodiment and Embodiment 19 is that the thermal conductive filler is filled into the thermal conductive holes by perfusion instead of dispensing with a precision dispensing machine. The rest are the same as those in Embodiment 19.

[0179] Embodiment 21

[0180] The difference between this embodiment and Embodiment 19 is that the aperture of the thermal conductive holes is 0.4 mm and the distance between adjacent thermal conductive holes is 0.5 mm. The rest are the same as those in Embodiment 19.

[0181] Embodiment 22

[0182] The difference between this embodiment and Embodiment 19 is that the aperture of the thermal conductive holes is 0.3 mm and the distance between adjacent thermal conductive holes is 0.4 mm. The rest are the same as those in Embodiment 19.

[0183] Embodiment 23

[0184] The difference between this embodiment and Embodiment 19 is that the aperture of the thermal conductive holes is 2 mm and the distance between adjacent thermal conductive holes is 2 mm. The rest are the same as those in Embodiment 19.

[0185] Embodiment 24

[0186] The difference between this embodiment and Embodiment 19 is that the aperture of the thermal conductive holes is 3.5 mm and the distance between adjacent thermal conductive holes is 0.5 mm. The rest are the same as those in Embodiment 19.

[0187] Embodiment 25

[0188] The difference between this embodiment and Embodiment 19 is that the aperture of the heat-conducting holes is 0.2 mm, and the distance between adjacent heat-conducting holes is 2 mm, and the rest are the same as those in Embodiment 19.

[0189] The performance test results of Embodiments 18 to 25 are shown in Table 5 below.

[0190] Table 5: Performance Test Results of Embodiments 18 to 25

[0191] Thermal resistance (℃·cm2 / W) Tensile strength (MPa) Rebound rate (%) Example 18 0.21 0.38 83.2 Example 19 0.18 0.39 84.5 Example 20 0.35 0.36 80.1 Example 21 0.16 0.40 84.8 Example 22 0.12 0.41 85.8 Example 23 0.15 0.39 85.1 Example 24 0.22 0.34 84.8 Example 25 0.33 0.32 78.2

[0192] It can be seen from the data in Table 5 that both ozone treatment and vacuum treatment further improve the thermal conductivity and resilience of the prepared interface material. Ozone treatment significantly increases the number of active groups on the surface of the graphene thermal conductive film. After the thermal conductive paste is filled into the heat-conducting holes, it can better wet and bond with the graphene thermal conductive film, thereby reducing the pores at the bonding interface between the two, reducing the thermal resistance, and improving the thermal conductivity. Similarly, through vacuum treatment, the gas mixed during the mixing of the thermal conductive paste is effectively removed, and the number of bubbles and cavities inside the thermal conductive paste after curing decreases, reducing the air thermal resistance in the heat-conducting holes and improving the overall thermal conductivity of the interface material.

[0193] It can be seen from Embodiment 20 that when the thermal conductive paste is filled into the heat-conducting holes by perfusion, the thermal resistance of the interface material after curing increases relatively significantly, indicating that the perfusion method does not arrange the carbon fibers well in a specific direction, resulting in the disordered arrangement of carbon fibers in the heat-conducting holes. Due to the anisotropy of the thermal conductivity of carbon fibers, the overall thermal conductivity of the interface material decreases significantly. However, for the thermal conductive paste filled by dispensing with a precision dispensing machine, during the process of flowing out from the dispensing nozzle, the carbon fibers are readjusted in direction as the thermal conductive paste flows, effectively improving the orderliness of the directional arrangement of carbon fibers, and thus making full use of its excellent axial thermal conductivity, and effectively improving the overall thermal conductivity of the interface material.

[0194] The above are all the preferred embodiments of this application. The protection scope of this application is not limited by this. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A high resilience and low thermal resistance interface material, characterized in that It includes a graphene heat-conducting film (1), and a plurality of heat-conducting holes (2) are perforated through the graphene heat-conducting film (1). The heat-conducting holes (2) are filled with a heat-conducting paste, and the heat-conducting paste includes raw materials in the following parts by weight: Carbon fiber: 50 - 700 parts; Heat-conducting powder: 500 - 1700 parts; Silicone oil: 50 - 120 parts; Coupling agent: 0.3 - 2 parts; Curing agent: 1 - 4 parts; Inhibitor: 0.1 - 1 part; Catalyst: 1 - 4 parts; Among them, the aperture of the heat-conducting hole (2) is 0.2 - 2 mm, and the distance between adjacent heat-conducting holes (2) is 0.2 - 1 mm; the diameter of the carbon fiber is 5 - 20 μm, and the length is 50 - 300 μm. The carbon fiber is arranged directionally along the opening direction of the heat-conducting hole (2).

2. The high-elasticity and low-thermal-resistance interface material according to claim 1, wherein The graphene heat-conducting film (1) is prepared by the following method: S1. Take graphene oxide slurry and obtain a graphene oxide coating film through coating; S2. Dry the graphene oxide coating film to remove the moisture therein to obtain a graphene oxide film; S3. Graphitize the graphene oxide film at 2500 - 3500 °C to obtain a graphene heat-conducting film.

3. The high-resilience and low-thermal-resistance interface material according to claim 2, wherein The graphene oxide slurry is a graphene oxide aqueous slurry, and the solid content of graphene oxide is 0.1 - 15 wt%.

4. The high-resilience and low-thermal-resistance interface material according to claim 1, wherein The thickness of the graphene heat-conducting film (1) is 10 - 1000 μm.

5. The high-elasticity and low-thermal-resistance interface material according to claim 1, characterized in that, The heat-conducting paste is prepared by the following method: According to the ratio, mix carbon fiber, heat-conducting powder, silicone oil, coupling agent, curing agent, and inhibitor evenly, and then add a catalyst and mix evenly to obtain the heat-conducting paste. The aperture of the heat-conducting hole (2) is 0.2 - 0.4 mm, and the distance between adjacent heat-conducting holes (2) is 0.3 - 0.5 mm; fill the heat-conducting paste into the heat-conducting hole (2) through a dispensing process to improve the orderliness of the directional arrangement of carbon fibers.

6. The high-resilience and low-thermal-resistance interface material according to claim 1 or 5, characterized in that The diameter of the carbon fiber is 10 - 15 μm, and the length is 190 - 210 μm.

7. A high resilience and low thermal resistance interface material according to claim 1 or 5, characterized in that, The heat-conducting powder is one or a combination of more of alumina, zinc oxide, magnesium oxide, aluminum nitride, graphite, graphene, aluminum powder, copper powder, silver-coated aluminum powder, etc.

8. The high-resilience and low-thermal-resistance interface material according to claim 1 or 5, characterized in that, The viscosity of the silicone oil is 100 - 300 mPa·s.

9. A method for preparing a high resilience and low thermal resistance interface material as described in any one of claims 1-8, characterized in that, It includes the following steps: S1. Prepare a graphene heat-conducting film (1); S2. Open heat-conducting holes (2) on the graphene heat-conducting film obtained in step S1; S3. Fill the heat-conducting paste into the heat-conducting holes by means of dispensing, and make the carbon fiber arranged directionally along the opening direction of the heat-conducting holes. Then, after curing, a high-elasticity and low-thermal-resistance interface material is obtained. The diameter of the dispensing nozzle on the dispensing equipment for filling the heat-conducting paste is 0.01 - 0.03 mm smaller than the aperture of the heat-conducting hole.

10. The preparation method of a high resilience and low thermal resistance interface material according to claim 9, characterized in that, In step S2, after opening the heat-conducting holes on the graphene heat-conducting film, surface treatment is carried out in an ozone environment. The ozone treatment time is 1 - 5 h, and the ozone concentration is 30 - 90%.

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