Preparation method of flexible heat-conducting material and flexible heat-conducting material

Abstract

The application relates to the technical field of heat-conducting materials, in particular to a preparation method of a flexible heat-conducting material and the flexible heat-conducting material, which comprises the following steps: S10, growing a diamond film on a substrate by a microwave plasma chemical vapor deposition method, wherein the thickness of the diamond film is 3-100 mu m; S20, performing punching treatment on the diamond film, wherein the pore diameter is 0.01-2 mm, and the pore spacing is 0.1-5 mm; S30, depositing metal nickel on the surface of the diamond film by a magnetron sputtering method to form a nickel layer, wherein the thickness of the nickel layer is 0.01-3 mu m; S40, performing oxidation treatment on the nickel layer in an oxygen environment to form a nickel oxide transition layer; S50, coating a polymer material on the surface of the nickel oxide transition layer, wherein the coating thickness is 2-100 mu m; and S60, heating to 150-180 DEG C to solidify the polymer material and couple the polymer material with the nickel oxide transition layer, so that the flexible heat-conducting material is formed. The flexible heat-conducting material prepared by combining the polymer material with the diamond material has high heat conduction, high insulation and excellent flexibility.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat-conducting materials, in particular to a preparation method of a flexible heat-conducting material and the flexible heat-conducting material. BACKGROUND

[0002] With the development of electronic devices towards miniaturization, thinness and multifunction, traditional heat dissipation materials such as metal heat dissipation sheets and heat-conducting silicone grease gradually expose their limitations when facing electronic devices that are gradually becoming small and complex. The development of flexible heat dissipation materials with foldable and bendable functions has become the key to solving the heat dissipation problems of such electronic devices. Compared with traditional heat dissipation materials, flexible heat dissipation materials can adapt to various complex spatial structures, perfectly fit the internal components of electronic devices, and timely and rapidly transfer heat in limited space, thereby providing strong support for the stable operation and miniaturization development of flexible electronic devices such as wearable devices and foldable screen mobile phones. Flexible heat-conducting materials refer to solid-state materials with foldable functions. The earliest flexible materials mainly focused on improved metal heat-conducting materials, followed by graphite sheet materials, heat-conducting filler and high polymer composite materials, and new graphene assembly heat-conducting materials. Flexible heat-conducting materials have both heat-conducting and flexible properties, and in addition to high heat-conducting capacity, they can also adapt to complex spatial structures.

[0003] In related technologies, commonly used heat-conducting materials mainly include metal-based heat-conducting materials, ceramic-based heat-conducting materials and high polymer-based composite heat-conducting materials. Although metal-based heat-conducting materials have excellent heat-conducting performance, they have the defects of strong electrical conductivity and poor flexibility, and cannot meet the insulation requirements and the close fitting requirements of complex surfaces of electronic devices; ceramic-based heat-conducting materials have good insulation and high heat-conducting coefficients, but are brittle and have poor flexibility, and are easy to break due to vibration or impact; traditional high polymer-based composite heat-conducting materials improve the heat-conducting performance by filling heat-conducting fillers (such as aluminum oxide and boron nitride), but the heat-conducting coefficients of such fillers are limited, and a large amount of filling is required to achieve high heat-conducting effect, which leads to a significant decrease in the flexibility of the material, and the insulation performance is also difficult to balance. SUMMARY

[0004] In order to overcome the deficiencies of the prior art, one of the purposes of the present application is to provide a preparation method of a flexible heat-conducting material, which combines high polymer materials with diamond materials to prepare a flexible heat-conducting material with high heat-conducting, high insulation and excellent flexibility.

[0005] The second purpose of the present application is to provide a flexible heat-conducting material prepared by the method.

[0006] The first aspect of the present application provides a preparation method of a flexible heat-conducting material, comprising:

[0007] S10, growing a diamond film on a substrate by a microwave plasma chemical vapor deposition method, the thickness of the diamond film being 3-100 μm;

[0008] S20, performing a punching treatment on the diamond film, the aperture being 0.01-2 mm, and the hole spacing being 0.1-5 mm;

[0009] S30, depositing a metal nickel on the surface of the diamond film by a magnetron sputtering to form a nickel layer, the thickness of the nickel layer being 0.01-3 μm;

[0010] S40, performing an oxidation treatment on the nickel layer in an oxygen environment to form a nickel oxide transition layer;

[0011] S50, coating a polymer material on the surface of the nickel oxide transition layer, the coating thickness being 2-100 μm;

[0012] S60, heating to 150-180 ℃ to solidify the polymer material and couple the polymer material with the nickel oxide transition layer to form a flexible heat-conducting material.

[0013] In the first aspect of the present application, as a preferred embodiment, in step S10, the substrate is a silicon substrate; the deposition conditions include: a microwave frequency of 2.45 GHz, a gas pressure of 5×10 -4 -2×10 -2 Pa, and a gas source of 90%-99.9% hydrogen and 0.1%-10% carbon-containing gas.

[0014] The carbon-containing gas can be methane, ethylene, acetylene, etc.

[0015] In the first aspect of the present application, as a preferred embodiment, in step S20, the punching treatment is implemented by laser punching to form a plurality of through holes, the aperture of each through hole being 0.05-1 mm, and the hole spacing between any two adjacent through holes being 0.5-3 mm.

[0016] In the first aspect of the present application, as a preferred embodiment, in step S30, the sputtering is performed in an argon atmosphere, and the sputtering gas pressure is 0.1-10 Pa.

[0017] In the first aspect of the present application, as a preferred embodiment, in step S40, the oxidation treatment conditions include: a temperature of 270-350 ℃, and an oxygen pressure of 1-2 kPa.

[0018] In the first aspect of the present application, as a preferred embodiment, in step S50, the polymer material includes silicone oil, styrene-butadiene block copolymer (SBS), or polyurethane, and the elongation of the polymer material after solidification is ≥80%.

[0019] In the first aspect of the present application, as a preferred embodiment, the curing in step S60 is performed in a vacuum heat treatment furnace, and the holding time is 10-60 minutes.

[0020] In the first aspect of the present application, as a preferred embodiment, the method further comprises step S70 of covering the surface of the flexible heat-conductive material with a PET protective film.

[0021] The second aspect of the present application provides a flexible heat-conductive material prepared by the method of the first aspect of the present application; the flexible heat-conductive material has a thermal conductivity greater than 700 W / m·K, an electrical resistivity greater than 10 15 Ω·cm, and an elongation greater than 80%.

[0022] In the second aspect of the present application, as a preferred embodiment, the thickness of the diamond film is 3-100 μm; the thickness of the nickel oxide transition layer is 0.01-0.3 μm; and the thickness of the polymer material is 2-100 μm.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] 1. The present application uses the microwave plasma chemical vapor deposition method to grow a diamond film on a substrate. The diamond film is punched to enhance the bonding force between the diamond film and the polymer layer. The magnetic control sputtering makes nickel atoms deposit on the surface of the punched diamond film to form a nickel layer, which is subsequently oxidized into a nickel oxide transition layer. The nickel oxide on the surface of the nickel oxide transition layer can be chemically bonded with the polymer material, thereby enhancing the bonding force with the polymer material. After the polymer material is coated, heating and curing coupling are performed to tightly bond the layers of materials to form a flexible heat-conductive material. In this way, the flexible heat-conductive material prepared by the present application has high thermal conductivity of diamond, enhanced bonding force of the metal transition layer, and flexibility of the polymer material, effectively solving the problem that traditional heat-conductive materials cannot simultaneously have high thermal conductivity, high insulation, and flexibility.

[0025] 2. The flexible heat-conductive material of the present application has comprehensive performance of high thermal conductivity, high insulation, and excellent flexibility, and can be widely applied in the fields of heat dissipation of electronic equipment, electrical insulation, etc., meeting the demand of modern industry for high-performance materials and providing strong support for the technical development in related fields. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall process of the preparation method of the present application.

[0027] Figure 2 It is a physical photograph of the flexible heat-conductive material of the present application in a horizontal state.

[0028] Figure 3 It is a physical photograph of the flexible heat-conductive material of the present application in a bent state. DETAILED DESCRIPTION

[0029] The invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Unless otherwise specified, the materials and equipment used in this embodiment are commercially available. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0030] In the description of this application, it should be understood that the terms "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and 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 the description of this application, "a plurality of" means two or more, unless otherwise precisely specified.

[0031] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "connected," "linked," and "connected" should be interpreted broadly. For example, they can refer to a connection, a link between two elements through an intermediary, the internal connection of two elements, or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0032] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or apparatus.

[0033] Reference Figure 1 The first aspect of this embodiment is to provide a method for preparing a flexible thermally conductive material, comprising:

[0034] S10. A diamond film is grown on a substrate by microwave plasma chemical vapor deposition, and the thickness of the diamond film is 3-100 μm.

[0035] S20. Drill holes in the diamond film with a hole diameter of 0.01-2 mm and a hole spacing of 0.1-5 mm.

[0036] S30. Metallic nickel is deposited on the surface of a diamond thin film by magnetron sputtering to form a nickel layer; the thickness of the nickel layer is 0.01-3 μm.

[0037] S40. Oxidize the nickel layer in an oxygen environment to form a nickel oxide transition layer;

[0038] S50. Coat the surface of the nickel oxide transition layer with a polymer material, with a coating thickness of 2-100μm.

[0039] S60, heating to 150-180℃ to solidify the polymer material and couple it with the nickel oxide transition layer to form a flexible thermally conductive material.

[0040] Based on the above scheme, this invention utilizes microwave plasma chemical vapor deposition to grow a diamond film on a substrate. Holes are drilled in the diamond film to enhance the bonding force between the diamond film and the polymer layer through a pinning effect. Magnetron sputtering deposits nickel atoms onto the surface of the drilled diamond film to form a nickel layer. This nickel layer is subsequently oxidized to form a nickel oxide transition layer. The nickel oxide on its surface can chemically bond with the polymer material, thereby enhancing the bonding force. After coating with the polymer material, heating and curing coupling are performed, allowing the layers to bond tightly together to form a flexible thermally conductive material. Thus, the flexible thermally conductive material prepared by this invention combines the high thermal conductivity of diamond, the enhanced bonding force of the metal transition layer, and the flexibility of the polymer material, effectively solving the problem that traditional thermally conductive materials cannot simultaneously achieve high thermal conductivity, high insulation, and flexibility.

[0041] In a first aspect of the present invention, as a preferred embodiment, in step S10, the substrate is a silicon substrate; the deposition conditions include: microwave frequency 2.45 GHz, air pressure 5 × 10⁻⁶. -4 -2×10 -2 Pa, the gas source is 90%-99.9% hydrogen and 0.1%-10% carbon-containing gas.

[0042] In a first aspect of the present invention, as a preferred embodiment, in step S20, the drilling process is achieved by laser drilling to form a plurality of through holes, each through hole having a diameter of 0.05-1 mm and a hole spacing of 0.5-3 mm between any two adjacent through holes.

[0043] In a first aspect of the present invention, as a preferred embodiment, in step S30, sputtering is performed under an argon atmosphere with a sputtering pressure of 0.1-10 Pa.

[0044] In a first aspect of the present invention, as a preferred embodiment, the oxidation treatment conditions in step S40 include: a temperature of 270-350°C and an oxygen pressure of 1-2 kPa. When the temperature is below 270°C, the metal activation is insufficient, the oxidation efficiency is low, and the effect is poor; when the temperature is above 350°C, the metal is too reactive, leading to excessive oxidation, and the amount of oxidation is difficult to control.

[0045] In a first aspect of the present invention, as a preferred embodiment, in step S50, the polymer material comprises silicone oil, styrene-butadiene block copolymer (SBS) or polyurethane, and the elongation of the polymer material after curing is ≥80%.

[0046] In a first aspect of the present invention, as a preferred embodiment, in step S60, curing is carried out in a vacuum heat treatment furnace for a holding time of 10-60 minutes.

[0047] In a preferred embodiment of the first aspect of the invention, step S70 is further included, where a PET protective film is coated onto the surface of the flexible thermally conductive material. Thus, the PET protective film possesses good flexibility, abrasion resistance, and chemical stability. Its working principle is to form a physical barrier on the surface of the flexible thermally conductive material, protecting the material from external mechanical damage, chemical corrosion, and contamination from dust and other impurities, thereby extending the material's service life.

[0048] A second aspect of the present invention provides a flexible thermally conductive material prepared by the method of the first aspect of the present invention; the flexible thermally conductive material has a thermal conductivity greater than 700 W / m·K and a resistivity greater than 10 Ω·m. 15 Its elongation is greater than 80% (Ω·cm).

[0049] In a second aspect of the present invention, as a preferred embodiment, the thickness of the diamond film is 3-100 μm; the thickness of the nickel oxide transition layer is 0.01-0.3 μm; and the thickness of the polymer material is 2-100 μm.

[0050] The following are some embodiments listed in this application, which further illustrate this application.

[0051] Example 1:

[0052] This embodiment provides a method for preparing a flexible thermally conductive material, including the following steps:

[0053] S10. Using a silicon substrate as the base, a diamond thin film is grown by microwave plasma chemical vapor deposition. The deposition conditions are: microwave frequency 2.45 GHz, gas pressure 1 × 10⁻⁶. -3 Pa, the gas source is 95% hydrogen and 5% methane by volume, and the thickness of the grown diamond film is 20 μm.

[0054] S20. Laser drilling is used to drill holes in the diamond film, with a hole diameter of 0.5 mm and a hole spacing of 2 mm.

[0055] S30. Under an argon atmosphere of 0.5 Pa, metallic nickel is deposited on the surface of a diamond film by magnetron sputtering to form a nickel layer with a thickness of 0.15 μm.

[0056] S40. Under an oxygen pressure of 1 kPa, the nickel layer is oxidized at 300°C to form a nickel oxide transition layer.

[0057] S50. Apply silicone oil to the surface of the nickel oxide transition layer with a coating thickness of 10 μm.

[0058] S60. Place the above sample in a vacuum heat treatment furnace, heat it to 160°C, and keep it at that temperature for 30 minutes to allow the silicone oil to solidify and couple with the nickel oxide transition layer, forming a flexible thermally conductive material.

[0059] S70. A PET protective film is applied to the surface of the flexible thermally conductive material.

[0060] The flexible thermally conductive material prepared by the above method has a silicon substrate thickness of 100 μm, a diamond film thickness of 20 μm, a nickel oxide transition layer thickness of 0.15 μm, and a polymer film thickness of 10 μm.

[0061] Reference Figure 2 , reference Figure 3 This demonstrates that flexible thermal conductive materials possess excellent flexibility.

[0062] The performance of the flexible thermally conductive material in Example 1 is shown in Table 1.

[0063] Table 1

[0064]

[0065] Based on Example 1 above, the influence of different diamond film thicknesses on the performance of flexible thermal conductive materials was further investigated. In this process, the diamond film thickness was different, but other conditions remained consistent with Example 1. The specific performance of the flexible thermal conductive materials is shown in Table 2.

[0066] Table 2

[0067]

[0068] As shown in Table 2, with the increase of diamond film thickness, the thermal conductivity and hardness of the material increase, while the elongation decreases. When the diamond film thickness increases to a certain size, the thermal conductivity of the material basically stabilizes within a certain range.

[0069] Based on Example 1 above, the effect of coating with silicone oil of different thicknesses on the performance of the flexible thermal conductive material was further investigated. In this process, silicone oil of different thicknesses was coated, but other conditions remained consistent with Example 1. The specific performance of the flexible thermal conductive material is shown in Table 3.

[0070] Table 3

[0071]

[0072] As can be seen from Table 3, as the thickness of the silicone oil increases, the thermal conductivity of the material decreases, the hardness decreases, and the elongation increases.

[0073] Example 2:

[0074] The only difference between this embodiment and Embodiment 1 is that SBS is used instead of silicone oil. Everything else is the same as in Embodiment 1.

[0075] The performance of the flexible thermally conductive material in Example 2 is shown in Table 4.

[0076] Table 4

[0077]

[0078] Example 3:

[0079] The only difference between this embodiment and Embodiment 1 is that Si is used instead of Ni. Everything else is the same as Embodiment 1.

[0080] The performance of the flexible thermally conductive material in Example 3 is shown in Table 5.

[0081] Table 5

[0082]

[0083] Example 4:

[0084] The only difference between this embodiment and Embodiment 1 is that Cr is used instead of Ni. Everything else is the same as Embodiment 1.

[0085] The performance of the flexible thermally conductive material in Example 4 is shown in Table 6.

[0086] Table 6

[0087]

[0088] Comparative Example 1:

[0089] The difference between this comparative example and Example 1 is that silicon carbide is used instead of diamond. Everything else is the same as in Example 1.

[0090] The performance of the flexible thermally conductive material in Comparative Example 1 is shown in Table 7.

[0091] Table 7

[0092]

[0093] As can be seen from Tables 7 and 1, the thermal conductivity of silicon carbide is much lower than that of diamond, so the thermal conductivity is significantly reduced after replacement.

[0094] Comparative Example 2:

[0095] The difference between this comparative example and Example 1 is that polyimide is used instead of silicone oil. Everything else is the same as in Example 1.

[0096] The performance of the flexible thermal conductive material in Comparative Example 2 is shown in Table 8.

[0097] Table 8

[0098]

[0099] As can be seen from Tables 8 and 1, since diamond film is the main thermal conductive material, the thermal conductivity remains basically unchanged after replacing silicone oil with polyimide. However, after polyimide forms a three-dimensional network crosslink, the hardness increases and the elongation decreases.

[0100] Although certain components and embodiments of this application have been illustrated and described, many modifications and alterations will be apparent to those skilled in the art without actually departing from the scope and spirit of the claims, such as variations in the size, dimensions, structure, shape and proportion of the various elements, installation arrangement, material use, color, orientation, etc.

[0101] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a flexible thermally conductive material, characterized in that, include: S10. A diamond film is grown on a substrate by microwave plasma chemical vapor deposition, and the thickness of the diamond film is 3-100 μm. S20. Drill holes in the diamond film with a hole diameter of 0.01-2 mm and a hole spacing of 0.1-5 mm. S30. Metallic nickel is deposited on the surface of a diamond thin film by magnetron sputtering to form a nickel layer; the thickness of the nickel layer is 0.01-3 μm. S40. Oxidize the nickel layer in an oxygen environment to form a nickel oxide transition layer; S50. A polymer material is coated on the surface of the nickel oxide transition layer, with a coating thickness of 2-100 μm; the polymer material includes silicone oil or SBS. S60, heating to 150-180℃ to solidify the polymer material and couple it with the nickel oxide transition layer to form a flexible thermally conductive material.

2. The preparation method according to claim 1, characterized in that, In step S10, the substrate is a silicon substrate; the deposition conditions include: microwave frequency 2.45 GHz, air pressure 5 × 10⁻⁶. -4 -2×10 -2 Pa, the gas source is 90%-99.9% hydrogen and 0.1%-10% carbon-containing gas.

3. The preparation method according to claim 1, characterized in that, In step S20, the drilling process is achieved by laser drilling to form several through holes. The diameter of each through hole is 0.05-1mm, and the hole spacing between any two adjacent through holes is 0.5-3mm.

4. The preparation method according to claim 1, characterized in that, In step S30, sputtering is performed under an argon atmosphere with a sputtering pressure of 0.1-10 Pa.

5. The preparation method according to claim 1, characterized in that, In step S40, the oxidation treatment conditions include: temperature 270-350℃ and oxygen pressure 1-2kPa.

6. The preparation method according to claim 1, characterized in that, In step S50, the elongation of the polymer material after curing is ≥80%.

7. The preparation method according to claim 1, characterized in that, In step S60, curing is carried out in a vacuum heat treatment furnace for 10-60 minutes.

8. The preparation method according to claim 1, characterized in that, It also includes step S70, which involves coating the surface of the flexible thermally conductive material with a PET protective film.

9. A flexible thermally conductive material, characterized in that, The flexible thermally conductive material is prepared by the preparation method according to any one of claims 1-8; the thermal conductivity of the material is greater than 700 W / m·K, and its resistivity is greater than 10. 15 Its elongation is greater than 80% (Ω·cm).

10. The flexible thermally conductive material as described in claim 9, characterized in that, The thickness of diamond films is 3-100 μm; the thickness of nickel oxide transition layers is 0.01-0.3 μm; and the thickness of polymer materials is 2-100 μm.

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