A high-coefficient thermal interface material and a preparation method thereof
By setting a sinusoidal array of strip graphite structures in a flexible matrix and distributing them longitudinally, the problem of high compressive modulus of graphene thermal interface materials at high density was solved, achieving a combination of high thermal conductivity and excellent compressibility.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NINGBO INST OF MATERIALS TECH & ENG CHINESE ACAD OF SCI
- Filing Date
- 2024-12-20
- Publication Date
- 2026-06-23
AI Technical Summary
Existing graphene thermal interface materials have high compressive modulus at high packing density, making it difficult to combine excellent thermal conductivity and compressibility, which limits their effective application in the field of thermal interface materials.
A sinusoidal array of strip graphite structures is adopted in a flexible matrix. The structure is longitudinally aligned and discretely distributed in the horizontal direction. The compressive modulus and thermal conductivity can be controlled by adjusting the included angle, amplitude and number of periodic units.
It achieves both excellent thermal conductivity and compressibility at high packing density, with reduced compressive modulus and increased thermal conductivity, making it suitable for thermal interface materials.
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Figure CN122255657A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of thermal interface materials. Specifically, this invention relates to a highly oriented thermal interface material and its preparation method. Background Technology
[0002] Thermal interface materials are primarily used to connect heat sinks and heat sources, effectively filling the micro-nano scale gaps between them, squeezing out internal air, reducing interfacial thermal resistance, and achieving efficient heat transfer from the heat source to the heat sink. Traditional thermal interface materials are mostly based on flexible polymer matrices, which have very low intrinsic thermal conductivity. Even with the addition of large amounts of ceramic thermally conductive fillers (alumina, magnesium oxide, etc.), the thermal conductivity is difficult to exceed 10 W / mK, and is also accompanied by the problem of deteriorated mechanical properties. In recent years, with the development of electronic information and intelligence, and the use of high-frequency / high-power devices, traditional thermal interface materials have become insufficient to meet heat dissipation requirements.
[0003] Low-dimensional materials such as carbon nanotubes and graphene have attracted widespread attention due to their extremely high thermal conductivity. Graphene, as one of these materials, has an in-plane thermal conductivity of approximately 5300 W / mK for a single layer of suspended graphene, far exceeding that of other metals and ceramics. To fully utilize the anisotropy of graphene's thermal conductivity and effectively leverage its in-plane thermal conductivity, current research tends to focus on fabricating vertical structures.
[0004] Patent application CN113817327A discloses a method for preparing a graphene-based composite thermal pad. The method involves processing ordered layered graphene sheets into a porous mesh structure, stacking these porous mesh sheets to form a block of a certain thickness, filling the pores and gaps of the graphene block with liquid organic matter and other additives, and then solidifying it to form a laminated composite block. The composite block is then slit along a direction perpendicular to the graphene layers to obtain the graphene-based composite thermal pad. The thermal pad prepared by this method has graphene layers perpendicular to the plane of the pad, resulting in a pad with high vertical thermal conductivity while maintaining the stability and flexibility of the pad's mechanical structure. It can be used as a thermal interface material in the fields of heat conduction and dissipation. However, the graphene-based composite thermal pad prepared by the method disclosed in this patent application has a very high compressive modulus.
[0005] Existing research initially focused on microscopic manipulation, employing the self-assembly of graphene nanosheets in a liquid environment to construct graphene-based thermal interface materials, such as ice crystal-guided assembly and graphene oxide liquid crystal self-assembly. However, these methods resulted in 3D cross-linked vertical graphene structures (aerogels) with low density, low graphene content, and partially non-directional arrangement, leading to low thermal conductivity in the final composite material. To significantly improve the thermal conductivity of graphene-based thermal interface materials, some researchers shifted from microscopic design to macroscopic fabrication. For example, they used graphite / PU paper roll-cutting to prepare graphene-based thermal interface materials with a thermal conductivity of 276 W / m K. However, the high density and dense packing resulted in a very high compressive modulus (>30 MPa), increasing the interfacial thermal resistance.
[0006] In summary, graphene thermal interface materials do possess excellent thermal conductivity, but their compressibility still needs further improvement; otherwise, they will be difficult to apply effectively in the field of thermal interface materials. Summary of the Invention
[0007] This invention provides a high compliant structure thermal interface material that maintains a high compliant sinusoidal structure and intermittent horizontal arrangement, which can effectively solve the problem of high compressive modulus caused by high packing density, and has both excellent thermal conductivity and compressibility.
[0008] This invention provides a highly oriented thermal interface material, the highly oriented thermal interface material comprising a flexible matrix and sinusoidal array of strip graphite located inside the flexible matrix;
[0009] The sinusoidal array of strip graphite has a longitudinally aligned structure and a discrete distribution in the horizontal direction.
[0010] Preferably, the angle between the tangent on any side of the slope peak of the sinusoidal array of strip graphite and the horizontal line is 0°-90°, and the amplitude is 0-2cm;
[0011] The sinusoidal arrayed strip graphite comprises multiple arrayed sinusoidal strip structures, the width of which is 0.01-2 cm;
[0012] The sinusoidal ribbon graphite comprises 1-50 periodic units.
[0013] This invention achieves the transformation of the sinusoidal array strip graphite structure by controlling the angle between the tangent on one side of any slope peak and the horizontal line, the amplitude, the width of the sinusoidal strip graphite, and the number of periodic units, thereby enabling reasonable control of the compressive modulus.
[0014] More preferably, the angle between the tangent on any slope peak side of the sinusoidal array of strip graphite and the horizontal line is 57-78°, and the amplitude is 0.37-0.46. The sinusoidal strip graphite includes 1-12 periodic units.
[0015] By further controlling the angle between the tangent on one side of any slope peak and the horizontal line, the amplitude, and the number of periodic units, this invention achieves a high oriented structural thermal interface material with better compressive modulus while ensuring good thermal conductivity.
[0016] More preferably, the compressive modulus of the high oriented thermal interface material is 1.3-2.1 MPa, and the longitudinal thermal conductivity is 163.8-198.1 W / m. -1 K -1 .
[0017] More preferably, the periodic unit is the region between two consecutive troughs or peaks in the sinusoidal strip graphite.
[0018] Preferably, the mass ratio of the sinusoidal array bands to the matrix within the highly oriented thermal interface material is 1-9:1-9. This invention controls the mass ratio of the highly oriented thermal interface material to achieve a density of 0.3-1.4 g / cm³. 3 It can achieve good compressibility at higher bulk density.
[0019] Preferably, the longitudinal thermal conductivity of the high oriented thermal interface material is 20-300 W / mK, and the compressibility of the high oriented thermal interface material is 20-80%.
[0020] Preferably, the flexible matrix is, but not limited to, polydimethylsiloxane, styrene-butadiene rubber, silicone rubber, cis-butadiene rubber, polyurethane, epoxy resin, polybutylene terephthalate, polyimide, natural latex, ethylene propylene rubber, natural rubber, etc.
[0021] On the other hand, the present invention also provides a method for preparing the aforementioned highly oriented thermal interface material, comprising:
[0022] (1) Machining carbon-based thermal interface materials into sinusoidal array strip structures;
[0023] (2) The sinusoidal array strip structure obtained in step (1) is intermittently stacked in the horizontal direction and impregnated in a flexible substrate. Then, it is filtered, cured, and the edges are removed by rotation under vacuum to obtain a high-orientation thermal interface material.
[0024] Preferably, the carbon-based thermal interface material is any one of artificial graphene paper, natural graphite film, and artificial graphite film.
[0025] Preferably, the machining process is one or more of laser beam machining, ultrasonic machining, and ICP etching.
[0026] Preferably, the sinusoidal array strip structure is a spring-like structure with compression and tension properties.
[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0028] This invention utilizes sinusoidal array strip graphite with a longitudinally aligned structure and a discrete distribution in the horizontal direction to achieve high-density, dense packing of the sinusoidal array strip graphite. Because the graphite provided by this invention is sinusoidal array strip in shape and has a longitudinally aligned structure, the material provided by this invention has good thermal conductivity and good compressibility in the longitudinal direction. Attached Figure Description
[0029] Figure 1 This is a cross-sectional schematic diagram of a highly oriented structural thermal interface material provided in a specific embodiment of the present invention, wherein 1 is a sinusoidal band structure, 2 is a flexible matrix, 3 is a slope peak tangent, 4 is a horizontal line, 5 is a periodic unit, a is an included angle, b is the array band width, and c is the amplitude height.
[0030] Figure 2 and Figure 3 The image shows the high-orientation thermal interface material of the sinusoidal array strip structure after laser beam processing provided in Embodiment 1 of the present invention under special conditions (amplitude is 0), when the angle between the tangent on one side of any slope peak and the horizontal line is 90° and 60° respectively.
[0031] Figure 4 This is a confocal image of the sinusoidal array strip structure after laser beam processing, provided in Embodiment 2 of the present invention.
[0032] Figure 5 and Figure 6 The confocal image of the sinusoidal array strip structure after laser processing and the partial electron microscope image of the thermal interface material of the highly oriented structure provided in Embodiment 3 of the present invention are shown.
[0033] Specific implementation methods
[0034] The technical solutions in specific embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.
[0035] A specific embodiment of the present invention provides a highly oriented thermal interface material, such as... Figure 1 As shown, it includes a flexible substrate 2 and sinusoidal array strip graphite located within the flexible substrate 2. The sinusoidal array strip graphite provided in the specific embodiment of the present invention has a longitudinally oriented structure and a discretely distributed structure in the horizontal direction.
[0036] The sinusoidal arrayed strip graphite provided in this specific embodiment includes an array of sinusoidal strip structures 1. The sinusoidal arrayed strip graphite provided in this specific embodiment achieves longitudinal controllability by adjusting the angle α between the tangent 3 on one side of any slope peak and the horizontal line 4, the amplitude c, the width b of the sinusoidal strip structure, and the number of periodic units 5, thereby obtaining a thermal interface material with both high thermal conductivity and excellent compressibility.
[0037] To further understand the present invention, the advantages of the embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the claims of the present invention.
[0038] Example 1
[0039] (1) Take a graphite paper with a thickness of 40 micrometers and use a laser beam to process it to obtain a sinusoidal array strip structure with a bandwidth of 100 micrometers.
[0040] (2) The sinusoidal array strip structure obtained in step (1) is intermittently stacked and impregnated in a flexible modified epoxy matrix, vacuum filtered, cured, and the edges are rotated and cut to obtain the high compliant structure thermal interface material.
[0041] In step (1), the parameters of the sinusoidal array strip structure obtained by laser beam processing are: amplitude of 0 mm, and the sinusoidal array strip satisfies that the angle between the tangent on one side of any slope peak and the horizontal line is 90° or 60° respectively. Figure 2 and Figure 3 As shown, the sinusoidal array strip structures represent special cases where a completely vertical or tilted structure appears.
[0042] The carbon-based thermal interface materials with a high 90° fully vertical structure and a high 60° inclined structure provided in this embodiment have compressive moduli of 2.6 MPa and 2.4 MPa, respectively, and thermal conductivity of 203.4 W / m², respectively. -1 K -1 and 123.7W m -1 K -1 .
[0043] Example 2
[0044] The difference compared to Example 1 is that, as Figure 4 As shown, when the amplitude is 0.46mm (≠0), the sinusoidal array band satisfies the condition that the angle between the tangent on one side of any slope peak and the horizontal line is 78° and the repeating unit is 1.
[0045] The high cis-orientation carbon-based thermal interface material provided in this embodiment has a compressive modulus of 2.1 MPa and a thermal conductivity of 198.1 W / m². -1 K -1 .
[0046] Example 3
[0047] The difference compared to Example 1 is that, as Figure 5 and Figure 6 As shown, in order to further optimize the compression modulus, under the conditions that the amplitude is 0.37mm (≠0), the sinusoidal array band satisfies the angle between the tangent on one side of any slope peak and the horizontal line is 57°, and the repeating unit is 12 times.
[0048] The high cis-orientation carbon-based thermal interface material provided in this example has a compressive modulus of 1.3 MPa and a thermal conductivity of 163.8 W / m². -1 K -1 The compression modulus is much lower than that in Cases 1 and 2.
[0049] The above three examples further illustrate the present invention, but the implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions. Non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention are all within the protection scope of the present invention. The specific time, feeding amount, etc. in the following examples are only examples within a suitable range, that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not intended to be limited to the specific values in the examples below. Therefore, any equivalent or modified implementations made without departing from the spirit disclosed in the present invention fall within the protection scope of the present invention.
[0050] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by the appended claims.
Claims
1. A highly oriented thermal interface material, characterized in that, The highly oriented thermal interface material includes a flexible matrix and sinusoidal arrayed ribbon graphite located inside the flexible matrix. The sinusoidal array of strip graphite has a longitudinally aligned structure and a discrete distribution in the horizontal direction.
2. The highly oriented thermal interface material according to claim 1, characterized in that, The angle between the tangent on any slope peak of the sinusoidal array of strip graphite and the horizontal line is 0°-90°, and the amplitude is 0-2cm. The sinusoidal arrayed strip graphite comprises multiple arrayed sinusoidal strip structures, the width of which is 0.01-2 cm; The sinusoidal ribbon graphite comprises 1-50 periodic units.
3. The highly oriented thermal interface material according to claim 2, characterized in that, The angle between the tangent on any side of the slope peak of the sinusoidal array of the ribbon graphite and the horizontal line is 57-78°, and the amplitude is 0.37-0.
46. The sinusoidal ribbon graphite includes 1-12 periodic units.
4. The highly oriented thermal interface material according to claim 3, characterized in that, The compressive modulus of the high oriented thermal interface material is 1.3-2.1 MPa, and the longitudinal thermal conductivity is 163.8-198.1 W / m². -1 K -1 .
5. The highly oriented thermal interface material according to claim 2, characterized in that, The periodic unit is the region between two consecutive troughs or peaks in the sinusoidal ribbon graphite.
6. The highly oriented thermal interface material according to claim 1, characterized in that, The mass ratio of the sinusoidal array strip inside the high oriented thermal interface material to the matrix is 1-9:1-9.
7. The highly oriented thermal interface material according to claim 1, characterized in that, The longitudinal thermal conductivity of the high oriented structural thermal interface material is 20-300 W / mK, and the compressibility of the high oriented structural thermal interface material is 20-80%.
8. The highly oriented thermal interface material according to claim 1, characterized in that, The flexible matrix includes, but is not limited to, polydimethylsiloxane, styrene-butadiene rubber, silicone rubber, cis-butadiene rubber, polyurethane, epoxy resin, polybutylene terephthalate, polyimide, natural latex, ethylene propylene rubber, or natural rubber.
9. A method for preparing a highly oriented thermal interface material according to any one of claims 1-8, characterized in that, include: (1) Machining carbon-based thermal interface materials into sinusoidal array strip structures; (2) The sinusoidal array strip structure obtained in step (1) is intermittently stacked in the horizontal direction and impregnated in a flexible substrate. Then, it is filtered, cured, and the edges are removed by rotation under vacuum to obtain a high-orientation thermal interface material.
10. The method for preparing a highly oriented thermal interface material according to claim 9, characterized in that, The carbon-based thermal interface material is any one of artificial graphene paper, natural graphite film, and artificial graphite film.