Conductive and heat-conductive composite ink, and preparation method and application thereof

Abstract

The application provides a conductive and heat-conductive composite ink as well as a preparation method and application thereof. The conductive and heat-conductive composite ink comprises cluster-state material liquid drops in a pomegranate-like structure; the cluster-state material in the pomegranate-like structure comprises graphene, liquid metal and one-dimensional conductive and heat-conductive material; the graphene is assembled on the surface of the liquid metal to form hybrid microspheres, and the one-dimensional conductive and heat-conductive material is bridged between the hybrid microspheres to form the cluster-state material in the pomegranate-like structure. The composite ink provided by the application can obtain a dense, high-conductive and bidirectional heat-conductive film, which is used for a thermal interface material and simultaneously has electromagnetic shielding performance in a GHz frequency band and high interface thermal conductivity, so that key parts in an electronic device are protected from electromagnetic wave interference and high temperature, and high-speed operation of the electronic device is ensured.

Description

Technical Field

[0001] This invention belongs to the field of thermal interface materials technology, and relates to a conductive and thermally conductive composite ink, its preparation method and application. Background Technology

[0002] With the rapid development of 5G communication, artificial intelligence, and high-performance computing technologies, chips are evolving towards higher frequencies, higher integration, and ultra-high power densities. However, they also face severe challenges: on the one hand, increasingly severe electromagnetic interference within and between chips has become a key bottleneck affecting signal integrity and system reliability; on the other hand, the surge in chip power consumption has made heat dissipation capacity a "ceiling" restricting performance release. Simultaneously, the internal design space of chip packages is extremely limited, making "lightweight, thin, and miniaturized" designs a long-term trend. In recent years, coverless packaging designs have become an emerging trend, but they require both efficient electromagnetic shielding and interface heat dissipation. TIM (thermal interface material) is a key electronic material used to fill the tiny gaps at the chip's heat dissipation interface and efficiently conduct heat. In the chip heat dissipation path, it is typically located between the package metal cover (Lid) and the external heat sink, or directly between the bare chip and the heat sink in some coverless packages. For thermal interface materials (TIM1.5) in coverless packages, not only is efficient electromagnetic shielding performance required, but also bidirectional thermal conductivity is needed to avoid electromagnetic interference and interface conduction of heat, as well as in-plane heat dissipation. Therefore, the demand for thermal interface materials with excellent electromagnetic shielding and thermal conductivity, and which are easy to mass-produce industrially, is constantly expanding.

[0003] However, current mainstream heat dissipation and shielding solutions, such as metal shields or polymer composites with added traditional conductive fillers, are no longer sufficient to meet the above dual challenges, and there are three core pain points that urgently need to be addressed.

[0004] The contradiction between "thickness" and "performance": To achieve effective electromagnetic shielding, a certain material thickness is often required, which runs counter to the macro development trend of electronic products being "light, thin, short, and small" and the extremely demanding space budget inside chip packaging.

[0005] The contradiction between "shielding" and "heat dissipation": Excellent electromagnetic shielding materials usually focus on their electrical conductivity, while high thermal conductivity is not their primary goal. Many highly conductive fillers (such as silver and nickel) themselves have only average thermal conductivity, causing existing shielding materials to "lock in" heat while blocking electromagnetic waves, forming a "thermal short circuit." This cannot meet the urgent need for bidirectional and efficient heat conduction (i.e., simultaneously conducting heat vertically from the chip to the heat sink and achieving uniform in-plane heating) for high-frequency thermal devices such as computing chips.

[0006] The challenge of interface thermal resistance: In ultra-thin form, the contact thermal resistance between the material and the chip and heat sink increases significantly. If the material itself has insufficient thermal conductivity, even if the thickness is very thin, the overall thermal management efficiency will be greatly reduced.

[0007] Therefore, developing a material with both high thermal conductivity and electromagnetic shielding functions, especially a material with high electromagnetic shielding effectiveness and bidirectional high thermal conductivity, is a technical problem that urgently needs to be solved. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a conductive and thermally conductive composite ink, its preparation method, and its applications. The composite ink provided by this invention can produce a dense, highly conductive, and bidirectionally thermally conductive thin film. When used as a thermal interface material, it simultaneously possesses GHz-level electromagnetic shielding performance and high interfacial thermal conductivity, protecting critical components in electronic devices from electromagnetic interference and high temperatures, thus ensuring their high-speed operation.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a conductive and thermally conductive composite ink, the conductive and thermally conductive composite ink comprising clustered material droplets with a garnet-like structure;

[0011] The garnet-like clustered materials include graphene, liquid metal, and one-dimensional conductive and thermally conductive materials;

[0012] The graphene is assembled on the surface of the liquid metal to form hybrid microspheres, and the one-dimensional conductive and thermally conductive material is bridged between the hybrid microspheres to form a clustered material with a garnet-like structure.

[0013] Preferably, the one-dimensional conductive and thermally conductive material includes any one or a combination of at least two of carbon nanotubes, carbon nanofibers, or metal nanowires, with carbon nanotubes being the most preferred.

[0014] Preferably, the solid content of the clustered material droplets is 300 g / L to 1500 g / L.

[0015] In a second aspect, the present invention provides a method for preparing the conductive and thermally conductive composite ink as described in the first aspect, the method comprising the following steps:

[0016] Graphene is assembled onto a liquid metal surface using a liquid-phase electrostatic assembly method to obtain a hybrid microsphere dispersion; the hybrid microsphere dispersion is then mixed with a one-dimensional conductive and thermally conductive material dispersion to obtain the conductive and thermally conductive composite ink.

[0017] Preferably, the graphene comprises graphene microsheets, the number of layers of the graphene microsheets is 2 to 10, and the diameter of the graphene microsheets is 0.2 μm to 1 μm.

[0018] Preferably, the particle size of the liquid metal is in the range of 0.8 μm to 4 μm.

[0019] Preferably, the one-dimensional conductive and thermally conductive material includes any one or a combination of at least two of carbon nanotubes, carbon nanofibers, or metal nanowires, preferably carbon nanotubes, and more preferably the length of the carbon nanotubes is 5μm to 50μm.

[0020] Preferably, the mass ratio of the graphene to the liquid metal is (1~5):100.

[0021] Preferably, the amount of the one-dimensional conductive and thermally conductive material is 10wt% to 50wt% of the graphene, and more preferably 10wt% to 30wt%.

[0022] Preferably, the liquid-phase electrostatic assembly method includes:

[0023] Graphene is initially processed and then protonated to obtain a graphene dispersion.

[0024] Liquid metal is deprotonated and dispersed to obtain a liquid metal dispersion.

[0025] The graphene dispersion and the liquid metal dispersion are electrostatically assembled in the liquid phase to obtain hybrid microspheres of graphene assembled on the surface of liquid metal.

[0026] Preferably, the pretreatment agent includes tannic acid.

[0027] Preferably, the amount of the protonable modifier is 1 wt% to 5 wt% of the graphene.

[0028] Preferably, the amount of the deprotonating modifier is 0.5wt% to 4wt% of the liquid metal.

[0029] Preferably, the feeding method for the liquid phase electrostatic assembly includes dropping the liquid metal dispersion into the graphene dispersion.

[0030] Preferably, the stirring speed of the liquid phase electrostatic assembly is 300 rpm to 1000 rpm.

[0031] Preferably, the dispersant of the one-dimensional conductive and thermally conductive material dispersion includes an organic compound with hydrogen bond adsorption, wherein the organic compound with hydrogen bond adsorption includes sericin macromolecules, and the molecular weight of the sericin macromolecules is 50kDa~200kDa.

[0032] Preferably, the amount of dispersant in the one-dimensional conductive and thermally conductive material dispersion is 1wt% to 5wt% of the one-dimensional conductive and thermally conductive material.

[0033] Preferably, the hybrid microsphere dispersion and the one-dimensional conductive and thermally conductive material dispersion are mixed by stirring, and the stirring speed is 300 rpm to 600 rpm.

[0034] Preferably, the hybrid microsphere dispersion is mixed with a one-dimensional conductive and thermally conductive material dispersion, and then separated and concentrated to obtain the conductive and thermally conductive composite ink.

[0035] Thirdly, the present invention provides a conductive and thermally conductive thin film, wherein the raw materials of the conductive and thermally conductive thin film include the conductive and thermally conductive composite ink as described in the first aspect or the conductive and thermally conductive ink prepared by the preparation method described in the second aspect.

[0036] Fourthly, the present invention provides a method for preparing a conductive and thermally conductive thin film as described in the third aspect, the method comprising the following steps:

[0037] The conductive and thermally conductive composite ink as described in the first aspect or the conductive and thermally conductive ink prepared by the preparation method as described in the second aspect are sequentially subjected to calendering coating, drying and hot rolling to obtain the conductive and thermally conductive film.

[0038] Preferably, the hot rolling process includes a first hot rolling process and a second hot rolling process performed in a gradient.

[0039] Preferably, the temperature of the first hot roller is 40℃~80℃, the compression deformation of the first hot roller is 3%~8%, and the time of the first hot roller is 1h~3h.

[0040] Preferably, the temperature of the second hot roller is 110℃~140℃, the compression deformation of the second hot roller is 9%~16%, and the time of the second hot roller is 1h~3h.

[0041] Fifthly, the present invention also provides an application of a conductive and thermally conductive thin film, the application including using the conductive and thermally conductive thin film as described in the third aspect or the conductive and thermally conductive thin film prepared by the preparation method described in the fourth aspect as a thermal interface material with both electromagnetic shielding and interface heat dissipation functions in a capless packaged semiconductor device.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The electrically conductive and thermally conductive composite ink provided by the present invention contains graphene, liquid metal, and one-dimensional conductive and thermally conductive materials, which have a special garnet-like cluster structure. The graphene assembled on the surface of the liquid metal has excellent electrical and thermal conductivity. Furthermore, the hybrid microspheres are bridged to each other through the hydrogen bonding of the one-dimensional conductive and thermally conductive materials, which enhances the bonding force between the hybrid microspheres and the bonding effect between the components is good. The conductive and thermally conductive composite ink provided by the present invention can obtain a bendable, dense, highly conductive, and bidirectionally thermally conductive film structure, which constructs a dense and efficient conductive and thermally conductive film structure. The thermal network, with its ultra-thin thickness, possesses extremely high electromagnetic shielding effectiveness and can also control the orientation of graphene microsheets, comprehensively adjusting the in-plane and out-of-plane thermal conductivity of the film to achieve uniform in-plane heat distribution and out-of-plane heat conduction, thus amplifying the electromagnetic shielding effectiveness. In addition, due to the low-temperature phase change capability of liquid metal, contact thermal resistance can be greatly eliminated, maximizing the out-of-plane thermal conductivity of the composite film. It also has GHz-level electromagnetic shielding performance and high interface thermal conductivity, which can protect key components in electronic devices from electromagnetic interference and high temperatures, ensuring their high-speed operation.

[0044] (2) In this invention, graphene and liquid metal are electrostatically assembled in the liquid phase to coat the surface of the liquid metal, thereby obtaining a graphene-liquid metal hybrid microsphere (GNPs@LMs) dispersion. Then, a one-dimensional conductive and thermally conductive material dispersion is dropped into the GNPs@LMs dispersion. Hydrogen bonds are used to adsorb the GNPs@LMs hybrid microspheres, so that the one-dimensional conductive and thermally conductive material acts as a bridge between the hybrid microspheres to form a conductive and thermally conductive composite cluster with a garnet-like structure, which is beneficial for constructing a dense and efficient conductive and thermally conductive thin film structure.

[0045] (3) The conductive and thermally conductive film obtained by using the conductive and thermally conductive ink provided by the present invention as raw material has the functions of being bendable, dense, highly conductive and bidirectionally thermally conductive. At the same time, it has electromagnetic shielding performance at the GHz band level and high thermal conductivity at the interface, which can protect key components in electronic devices from electromagnetic interference and high temperature damage, and ensure their high-speed operation. It can be used as electromagnetic shielding and interface heat dissipation in high computing power chips, base stations, aerospace and other fields, which is conducive to the thin and light design of chip packaging.

[0046] (4) The present invention uses the above-mentioned conductive and thermally conductive composite ink as the raw material, and through calendering, coating, drying and hot rolling, a garnet-like cluster structure is formed to form a thin film with excellent bending performance, density, high conductivity and bidirectional thermal conductivity. Attached Figure Description

[0047] Figure 1 This is a schematic diagram illustrating the preparation of a conductive and thermally conductive thin film obtained from a conductive and thermally conductive composite ink in Embodiment 1 of the present invention. Detailed Implementation

[0048] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0049] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0050] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0051] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0052] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0053] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0054] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0055] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0056] In this invention, "optional" means that something is optional, that is, it refers to either "with" or "without". If there are multiple "optional" options in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, then each "optional" option is independent.

[0057] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0058] In one embodiment, the first aspect of the present invention provides a conductive and thermally conductive composite ink, the conductive and thermally conductive composite ink comprising clustered material droplets with a garnet-like structure;

[0059] The garnet-like clustered materials include graphene, liquid metal, and one-dimensional conductive and thermally conductive materials;

[0060] The graphene is assembled on the surface of the liquid metal to form hybrid microspheres, and the one-dimensional conductive and thermally conductive material is bridged between the hybrid microspheres to form a clustered material with a garnet-like structure.

[0061] The electrically conductive and thermally conductive composite ink provided by this invention comprises graphene, liquid metal, and one-dimensional conductive and thermally conductive materials in a unique garnet-like cluster structure. The graphene assembled on the liquid metal surface exhibits excellent electrical and thermal conductivity. Furthermore, the hydrogen bonding of the one-dimensional conductive and thermally conductive materials bridges the hybrid microspheres, enhancing the bonding force between them. The components also exhibit good inter-component bonding. The conductive and thermally conductive composite ink provided by this invention can yield a flexible, dense, highly conductive, and bidirectionally thermally conductive film structure, constructing a dense and efficient conductive and thermally conductive network. The composite film possesses extremely high electromagnetic shielding performance even at ultra-thin thicknesses. Furthermore, it allows for the control of the orientation of graphene microsheets, comprehensively adjusting the in-plane and out-of-plane thermal conductivity of the film to achieve uniform in-plane heat distribution and out-of-plane heat conduction, thereby amplifying the electromagnetic shielding effectiveness. In addition, due to the low-temperature phase change capability of liquid metal, contact thermal resistance can be greatly eliminated, maximizing the out-of-plane thermal conductivity of the composite film. Simultaneously, it combines GHz-level electromagnetic shielding performance with high interfacial thermal conductivity, protecting critical components in electronic devices from electromagnetic interference and high temperatures, ensuring their high-speed operation.

[0062] In some embodiments, the one-dimensional conductive and thermally conductive material includes any one or a combination of at least two of carbon nanotubes, carbon nanofibers, or metal nanowires, preferably carbon nanotubes.

[0063] Furthermore, the metal nanowires include silver nanowires and / or copper nanowires.

[0064] In the embodiments of the present invention, carbon nanotubes are selected as the bridging material, which has excellent flexibility at the micron level and has advantages in thermal conductivity and mechanical properties compared to other carbon nanofibers or metal nanowires.

[0065] In some embodiments, the solid content of the clustered material droplets is 300 g / L to 1500 g / L, such as 300 g / L, 400 g / L, 500 g / L, 600 g / L, 700 g / L, 800 g / L, 900 g / L, 1000 g / L, 1100 g / L, 1200 g / L, 1300 g / L, 1400 g / L, or 1500 g / L.

[0066] The solid content of the clustered material droplets provided by this invention directly affects the finished product of the subsequent conductive and thermally conductive film. Regulating the solid content of the clustered material droplets to 300g / L~1500g / L is beneficial for subsequent processing and will not lead to excessive dispersion of clustered particles, thus affecting the effect.

[0067] In one embodiment, a second aspect of the present invention provides a method for preparing a conductive and thermally conductive composite ink as described in the first aspect above, the method comprising the following steps:

[0068] Graphene is assembled onto a liquid metal surface using a liquid-phase electrostatic assembly method to obtain a hybrid microsphere dispersion; the hybrid microsphere dispersion is then mixed with a one-dimensional conductive and thermally conductive material dispersion to obtain the conductive and thermally conductive composite ink.

[0069] In this invention, graphene and liquid metal are electrostatically assembled in a liquid phase to coat the surface of the liquid metal, resulting in a graphene-liquid metal hybrid microsphere (GNPs@LMs) dispersion. Then, a one-dimensional conductive and thermally conductive material dispersion is dropped into the GNPs@LMs dispersion, and hydrogen bonds are used to adsorb the GNPs@LMs hybrid microspheres. This allows the one-dimensional conductive and thermally conductive material to act as a bridge between the hybrid microspheres, forming a conductive and thermally conductive composite cluster with a garnet-like structure. This facilitates the construction of a dense and efficient conductive and thermally conductive thin film structure.

[0070] Compared to the conventional method of directly ultrasonically bonding graphene, liquid metal and one-dimensional conductive and thermally conductive materials, ultrasonic bonding only exhibits high thermal conductivity in the in-plane direction, and has very limited vertical heat conduction at the interface.

[0071] In some embodiments, the graphene comprises graphene microsheets having 2 to 10 layers, such as 2, 3, 4, 5, 6, 7, 8, 9, or 10 layers; and / or, the graphene microsheets have a diameter of 0.2 μm to 1 μm, such as 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or 1 μm.

[0072] The graphene microsheets provided by this invention are ultrafine, highly crystalline microsheets obtained through high-temperature graphitization treatment.

[0073] In some embodiments, the particle size range of the liquid metal is 0.8 μm to 4 μm. For example, the endpoints of the particle size range can be 0.8 μm, 1 μm, 1.3 μm, 1.5 μm, 1.8 μm, 2 μm, 2.3 μm, 2.5 μm, 2.8 μm, 3 μm, 3.3 μm, 3.5 μm, 3.8 μm, or 4 μm, etc.

[0074] In some embodiments, the one-dimensional conductive and thermally conductive material includes any one or a combination of at least two of carbon nanotubes, carbon nanofibers, or metal nanowires.

[0075] In some embodiments, the one-dimensional conductive and thermally conductive material is selected from carbon nanotubes, and more preferably the length of the carbon nanotubes is 5μm to 50μm, such as 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm or 50μm.

[0076] It is understood that, apart from the length of the carbon nanotubes, the present invention does not specifically limit the diameter, type, etc. In principle, the present invention applies to commercially available carbon nanotube materials that meet the requirements or to carbon nanotubes prepared by conventional preparation methods.

[0077] In the preparation process of this invention, graphene materials with a suitable number of layers and sheet diameter (2 to 10 layers, 0.2 μm to 1 μm) are selected and combined with liquid metal with a particle size range of 0.8 μm to 4 μm. This allows for better electrostatic self-assembly of the two materials, with the graphene sheets better covering the surface of the liquid metal. Furthermore, when combined with carbon nanotubes with a length of 5 μm to 50 μm, the bridging effect is significant, and the cluster density is high.

[0078] In some embodiments, the mass ratio of the graphene to the liquid metal is (1~5):100, for example 1:100, 1.5:100, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100 or 5:100, etc.

[0079] In some embodiments, the amount of the one-dimensional conductive and thermally conductive material is 10wt% to 50wt% of the graphene, such as 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt% or 50wt%, etc., preferably 10wt% to 30wt%.

[0080] In the embodiments of the present invention, the use of a one-dimensional conductive and thermally conductive material is beneficial to improving the conductive and thermally conductive effects, and to better exert the synergistic effect with graphene and liquid metal under a specific cluster structure; and adjusting the amount of the one-dimensional conductive and thermally conductive material to 10wt%~30wt% of the graphene is more beneficial to improving the electromagnetic shielding performance and bidirectional (in-plane and out-of-plane) thermal conductivity.

[0081] In some embodiments, the liquid-phase electrostatic assembly method includes:

[0082] Graphene is initially processed and then protonated to obtain a graphene dispersion.

[0083] Liquid metal is deprotonated and dispersed to obtain a liquid metal dispersion.

[0084] The graphene dispersion and the liquid metal dispersion are electrostatically assembled in the liquid phase to obtain hybrid microspheres of graphene assembled on the surface of liquid metal.

[0085] This invention enhances the bonding effect between graphene and liquid metal by reversing the modification of graphene and liquid metal, thereby enabling spontaneous electrostatic self-assembly.

[0086] In some embodiments, the pretreatment agent includes tannic acid.

[0087] In some embodiments, the amount of the protonable modifier is 1 wt% to 5 wt% of the graphene, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt% or 5 wt%.

[0088] In some embodiments, the amount of the deprotonating modifier is 0.5wt% to 4wt% of the liquid metal, for example, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, or 4wt%.

[0089] It is understood that this invention does not specifically limit the types of protonable and deprotonable modifiers. Without departing from the technical concept of this invention, conventional materials that can have corresponding opposite substances are applicable to this invention.

[0090] For example, but not limitingly, the protonable modifier includes at least one of 3-aminopropyltriethoxysilane, ethylenediamine hydrochloride, chitosan, or polydimethyldiallylammonium chloride.

[0091] For example, but not limitingly, the deprotonating modifier includes at least one of polydopamine, sodium alginate, or cellulose nanocrystals.

[0092] In some embodiments, the liquid metal includes, but is not limited to, at least one of gallium, gallium-indium alloy, or gallium-indium-tin alloy.

[0093] In some embodiments, the feeding method for the liquid-phase electrostatic assembly includes dropping the liquid metal dispersion into the graphene dispersion.

[0094] In some embodiments, the stirring speed of the liquid phase electrostatic assembly is 300 rpm to 1000 rpm, such as 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm or 1000 rpm.

[0095] In some embodiments, the dispersant of the one-dimensional conductive and thermally conductive material dispersion includes an organic compound with hydrogen bonding adsorption properties. The organic compound with hydrogen bonding adsorption properties includes sericin macromolecules with a molecular weight of 50kDa to 200kDa, such as 50kDa, 60kDa, 70kDa, 80kDa, 90kDa, 100kDa, 110kDa, 120kDa, 130kDa, 140kDa, 150kDa, 160kDa, 170kDa, 180kDa, 190kDa, or 200kDa.

[0096] This invention selects sericin macromolecules as a modifier and dispersant for one-dimensional conductive and thermally conductive materials. These macromolecules can form hydrogen bond adsorption with the hybrid microsphere dispersion, thereby better realizing the bridging effect of one-dimensional conductive and thermally conductive materials.

[0097] In some embodiments, the amount of dispersant in the one-dimensional conductive and thermally conductive material dispersion is 1wt% to 5wt% of the one-dimensional conductive and thermally conductive material, for example, 1wt%, 2wt%, 3wt%, 4wt% or 5wt%.

[0098] In some embodiments, the hybrid microsphere dispersion is mixed with the one-dimensional conductive and thermally conductive material dispersion by stirring, wherein the stirring speed is 300 rpm to 600 rpm, for example, 300 rpm, 400 rpm, 500 rpm or 600 rpm.

[0099] In some embodiments, the hybrid microsphere dispersion is mixed with a one-dimensional conductive and thermally conductive material dispersion and then separated and concentrated to obtain the conductive and thermally conductive composite ink.

[0100] In one embodiment, the third aspect of the present invention provides a conductive and thermally conductive thin film, wherein the raw material of the conductive and thermally conductive thin film includes the conductive and thermally conductive composite ink provided by the embodiment of the first aspect above or the conductive and thermally conductive ink prepared by the preparation method provided by the embodiment of the second aspect above.

[0101] The conductive and thermally conductive film obtained by using the conductive and thermally conductive ink provided by this invention as raw material has the functions of being flexible, dense, highly conductive and bidirectionally thermally conductive. At the same time, it also has electromagnetic shielding performance at the GHz band level and high interface thermal conductivity, which can protect key components in electronic devices from electromagnetic interference and high temperature damage, ensuring their high-speed operation. It can be used as electromagnetic shielding and interface heat dissipation in high-performance chips, base stations, aerospace and other fields, which is conducive to the thinner and lighter design of chip packaging.

[0102] In some embodiments, the thickness of the conductive and thermally conductive film is 0.05 mm to 0.2 mm, such as 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, or 0.2 mm.

[0103] In one embodiment, the present invention provides a method for preparing a conductive and thermally conductive thin film as described in the third aspect, the method comprising the following steps:

[0104] The conductive and thermally conductive composite ink provided by the embodiment of the first aspect above, or the conductive and thermally conductive ink prepared by the preparation method provided by the embodiment of the second aspect above, is sequentially subjected to calendering coating, drying, and hot rolling to obtain the conductive and thermally conductive film.

[0105] This invention uses the above-mentioned conductive and thermally conductive composite ink as the raw material, and through calendering coating, drying and hot rolling, it ensures that the pomegranate-like cluster structure is formed, resulting in a thin film with excellent bending performance, density, high conductivity and bidirectional thermal conductivity.

[0106] In some embodiments, the spacing of the calendered coating is 0.08 mm to 0.5 mm, such as 0.08 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm or 0.5 mm.

[0107] In some embodiments, the hot rolling process includes a first hot rolling process and a second hot rolling process performed in a gradient.

[0108] In some embodiments, the temperature of the first hot roller pressing is 40°C to 80°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C; and / or, the compression deformation of the first hot roller pressing is 3% to 8%, for example, 3%, 4%, 5%, 6%, 7%, or 8%; and / or, the time of the first hot roller pressing is 1 hour to 3 hours, for example, 1 hour, 2 hours, or 3 hours.

[0109] In some embodiments, the temperature of the second hot rolling is 110°C to 140°C, for example, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, or 140°C; and / or, the compressibility deformation of the second hot rolling is 9% to 16%, for example, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or 16%; and / or, the time of the second hot rolling is 1 hour to 3 hours, for example, 1 hour, 2 hours, or 3 hours.

[0110] In the preparation process of conductive and thermally conductive thin films, this invention achieves the control of electromagnetic shielding performance and bidirectional thermal conductivity through gradient first hot rolling and second hot rolling, which better enhances the bonding effect between components, makes the film more compact, and has better thermal and electrical conductivity continuity, which is conducive to a significant improvement in bendability, thermal conductivity and thermal conductivity.

[0111] In one embodiment, the present invention also provides an application of a conductive and thermally conductive thin film, the application including using the conductive and thermally conductive thin film provided by the embodiment of the third aspect or the conductive and thermally conductive thin film prepared by the preparation method provided by the embodiment of the fourth aspect as a thermal interface material with both electromagnetic shielding and interface heat dissipation functions in a capless packaged semiconductor device.

[0112] Implementation examples and comparative layouts

[0113] Example 1

[0114] This embodiment provides a conductive and thermally conductive composite ink, which comprises clustered material droplets with a pomegranate-like structure;

[0115] The garnet-like clustered materials include graphene, liquid metal, and carbon nanotubes;

[0116] The graphene is assembled on the surface of the liquid metal to form hybrid microspheres, and the carbon nanotubes bridge the hybrid microspheres to form a clustered material with a garnet-like structure.

[0117] The preparation method of the conductive and thermally conductive composite ink includes:

[0118] (a) Dissolve 0.02 g of tannic acid in 1 L of deionized water, add 1 g of graphene microsheets (2 to 5 layers, 0.2 μm to 0.1 μm in diameter), disperse initially by ultrasonication, then add 0.04 g of chitosan into the above dispersion, stir at room temperature for 24 h to obtain a graphene dispersion with positive surface modification.

[0119] (b) 100g of liquid metal (Ga with a purity of 99.99%) 67 In 20.5 Sn 12.5 Alloy (particle size range 0.8μm~4μm) and 1g sodium alginate were added to 0.5L of deionized water, dispersed with an ultrasonic probe for 1 minute, and stirred for 2h to obtain a liquid metal droplet dispersion with negative surface charge modification.

[0120] (c) 0.003 g of sericin macromolecules (molecular weight of 100 kDa) and 0.1 g of multi-walled carbon nanotubes (diameter of 10 nm to 20 nm and length of 10 μm to 30 μm) were added to 1 L of deionized water, initially ultrasonically dispersed, and stirred at room temperature for 24 h to obtain a carbon nanotube dispersion modified with sericin on the surface.

[0121] A peristaltic pump was used to drop a liquid metal dispersion into a graphene dispersion and stir it thoroughly for electrostatic assembly to obtain graphene-liquid metal hybrid microspheres (GNPs@LMs). Then, a carbon nanotube dispersion was dropped into the GNPs@LMs dispersion, with the carbon nanotubes weighing 10 wt% of the graphene. After stirring thoroughly, the mixture was separated and concentrated to obtain a composite ink with a solid content of 800 g / L, in which liquid metal, graphene, and carbon nanotubes form garnet-like clusters (CNTs@GNPs@LMs).

[0122] This embodiment also provides a conductive and thermally conductive thin film, such as Figure 1 As shown, the method for preparing the conductive and thermally conductive thin film includes:

[0123] The composite ink prepared in the above embodiments was formed by calendering and coating, followed by infrared radiation drying to initially obtain a liquid metal / graphene / carbon nanotube composite film. Then, it was placed in a heated twin-roll calender at 60°C and subjected to 3% compression deformation once (first hot roll pressing) for 1 hour. The temperature was then raised to 120°C and the compression deformation was increased to 9% of the original thickness before being subjected to the roll again (second hot roll pressing) for 1 hour, finally obtaining the conductive and thermally conductive film.

[0124] Example 2

[0125] This embodiment provides a conductive and thermally conductive composite ink, which comprises clustered material droplets with a pomegranate-like structure;

[0126] The garnet-like clustered materials include graphene, liquid metal, and carbon nanotubes;

[0127] The graphene is assembled on the surface of the liquid metal to form hybrid microspheres, and the carbon nanotubes bridge the hybrid microspheres to form a clustered material with a garnet-like structure.

[0128] The preparation method of the conductive and thermally conductive composite ink includes:

[0129] (a) Dissolve 0.02 g of tannic acid in 1 L of deionized water, add 1 g of graphene microsheets (5 to 10 layers, 0.5 μm to 1 μm in diameter), disperse initially by ultrasonication, and then add 0.01 g of 3-aminopropyltriethoxysilane into the above dispersion. Stir at room temperature for 24 h to obtain a positively charged graphene dispersion.

[0130] (b) 100g of liquid metal (gallium Ga, particle size range 0.8μm~4μm) and 4g of cellulose nanocrystals were added to 0.5L of deionized water, dispersed by ultrasonic probe for 1 minute, and stirred for 2h to obtain a liquid metal droplet dispersion with negative surface charge modification.

[0131] (c) 0.001 g of sericin macromolecules and 0.1 g of multi-walled carbon nanotubes (diameter 10 nm ~ 20 nm, length 25 μm ~ 50 μm) were added to 1 L of deionized water, initially ultrasonically dispersed, and stirred at room temperature for 24 h to obtain a carbon nanotube dispersion modified with sericin on the surface.

[0132] A peristaltic pump was used to drop a liquid metal dispersion into a graphene dispersion and stir it thoroughly for electrostatic assembly to obtain graphene-liquid metal hybrid microspheres (GNPs@LMs). Then, a carbon nanotube dispersion was dropped into the GNPs@LMs dispersion, with the carbon nanotubes weighing 10 wt% of the graphene. After stirring thoroughly, the mixture was separated and concentrated to obtain a composite ink with a solid content of 300 g / L, in which liquid metal, graphene, and carbon nanotubes form garnet-like clusters (CNTs@GNPs@LMs).

[0133] This embodiment also provides a conductive and thermally conductive thin film, the preparation method of which includes:

[0134] The composite ink prepared in the above embodiments was formed by calendering and coating, followed by infrared radiation drying to initially obtain a liquid metal / graphene / carbon nanotube composite film. Then, it was placed in a heated twin-roll calender at 40°C and subjected to 3% compression deformation once (first hot roll pressing). The temperature was raised to 110°C and the first hot roll pressing time was 3 hours. The compression deformation was increased to 9% of the original thickness and then subjected to the second hot roll pressing for 3 hours, finally obtaining the conductive and thermally conductive film.

[0135] Example 3

[0136] This embodiment provides a conductive and thermally conductive composite ink, which comprises clustered material droplets with a pomegranate-like structure;

[0137] The garnet-like clustered materials include graphene, liquid metal, and carbon nanotubes;

[0138] The graphene is assembled on the surface of the liquid metal to form hybrid microspheres, and the carbon nanotubes bridge the hybrid microspheres to form a clustered material with a garnet-like structure.

[0139] The preparation method of the conductive and thermally conductive composite ink includes:

[0140] (a) Dissolve 0.05 g of tannic acid in 1 L of deionized water, add 1 g of graphene microsheets (2 to 6 layers, 0.1 μm to 0.4 μm in diameter), disperse initially by ultrasonication, then add 0.01 g of ethylenediamine hydrochloride into the dispersion, stir at room temperature for 24 h to obtain a positively charged graphene dispersion.

[0141] (b) 100g of liquid metal (Ga with a purity of 99.99%) 67 In 20.5 Sn 12.5 Alloy (particle size range 0.8μm~4μm) and 0.5g polydopamine were added to 0.5L of deionized water, dispersed with an ultrasonic probe for 1 minute, and stirred for 2h to obtain a liquid metal droplet dispersion with negative surface charge modification.

[0142] (c) 0.03 g of sericin macromolecules and 0.1 g of multi-walled carbon nanotubes (diameter 30 nm ~ 40 nm, length 10 μm ~ 30 μm) were added to 1 L of deionized water, initially ultrasonically dispersed, and stirred at room temperature for 24 h to obtain a carbon nanotube dispersion modified with sericin on the surface.

[0143] A peristaltic pump was used to drop a liquid metal dispersion into a graphene dispersion, and the mixture was stirred thoroughly for electrostatic assembly to obtain graphene-liquid metal hybrid microspheres (GNPs@LMs). Then, a carbon nanotube dispersion was dropped into the GNPs@LMs dispersion, with the carbon nanotubes weighing 10 wt% of the graphene. After thorough stirring, the mixture was separated and concentrated to obtain a composite ink with a solid content of 1500 g / L, in which liquid metal, graphene, and carbon nanotubes form garnet-like clusters (CNTs@GNPs@LMs).

[0144] This embodiment also provides a conductive and thermally conductive thin film, the preparation method of which includes:

[0145] The composite ink prepared in the above embodiments was formed by calendering and coating, followed by infrared radiation drying to initially obtain a liquid metal / graphene / carbon nanotube composite film. Then, it was placed in a heated twin-roll calender at 80°C and subjected to 3% compression deformation once (first hot roll pressing) for 2 hours. The temperature was then raised to 140°C and the compression deformation was increased to 9% of the original thickness before being subjected to the roll again (second hot roll pressing) for 2 hours, finally obtaining the conductive and thermally conductive film.

[0146] Example 4

[0147] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of graphene to liquid metal is 3:100, while still ensuring that the mass of carbon nanotubes is 10 wt% of graphene.

[0148] All other conditions remain the same as in Example 1.

[0149] Example 5

[0150] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of graphene to liquid metal is 5:100, while still ensuring that the mass of carbon nanotubes is 10 wt% of graphene.

[0151] All other conditions remain the same as in Example 1.

[0152] Example 6

[0153] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of graphene to liquid metal is 3:100, and the mass of carbon nanotubes is adjusted to 30 wt% of graphene.

[0154] All other conditions remain the same as in Example 1.

[0155] Example 7

[0156] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of graphene to liquid metal is 3:100, and the mass of carbon nanotubes is adjusted to 50 wt% of graphene.

[0157] All other conditions remain the same as in Example 1.

[0158] Example 8

[0159] The difference between this embodiment and Embodiment 1 is that the one-dimensional conductive and thermally conductive material in this embodiment is carbon nanofiber.

[0160] All other conditions remain the same as in Example 1.

[0161] Example 9

[0162] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of graphene to liquid metal is 3:100, and the mass of carbon nanotubes is adjusted to 30 wt% of graphene.

[0163] In this embodiment, during the preparation of the conductive and thermally conductive thin film, the compression deformation of the first hot rolling press is 6%, and the compression deformation of the second hot rolling press is 12%.

[0164] All other conditions remain the same as in Example 1.

[0165] Example 10

[0166] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of graphene to liquid metal is 3:100, and the mass of carbon nanotubes is adjusted to 30 wt% of graphene.

[0167] In this embodiment, during the preparation of the conductive and thermally conductive thin film, the compression deformation of the first hot rolling is 8%, and the compression deformation of the second hot rolling is 16%.

[0168] All other conditions remain the same as in Example 1.

[0169] Example 11

[0170] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of graphene to liquid metal is 3:100, and the mass of carbon nanotubes is adjusted to 30 wt% of graphene.

[0171] In this embodiment, during the preparation of the conductive and thermally conductive thin film, the compression deformation of the first hot rolling press is 0%, and the compression deformation of the second hot rolling press is 0%.

[0172] Example 12

[0173] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of graphene to liquid metal is 3:100, and the mass of carbon nanotubes is adjusted to 30 wt% of graphene.

[0174] In this embodiment, during the preparation of the conductive and thermally conductive thin film, the compression deformation of the first hot rolling is 10%.

[0175] All other conditions remain the same as in Example 1.

[0176] Example 13

[0177] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of graphene to liquid metal is 3:100, and the mass of carbon nanotubes is adjusted to 30 wt% of graphene.

[0178] In this embodiment, the compression deformation of the second hot roll is 20% during the preparation of the conductive and thermally conductive thin film.

[0179] All other conditions remain the same as in Example 1.

[0180] Example 14

[0181] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of graphene to liquid metal is 3:100, and the mass of carbon nanotubes is adjusted to 30 wt% of graphene.

[0182] In this embodiment, only the first hot rolling process is performed during the preparation of the conductive and thermally conductive thin film.

[0183] All other conditions remain the same as in Example 1.

[0184] Example 15

[0185] The difference between this embodiment and Embodiment 1 is that in this embodiment, the mass ratio of graphene to liquid metal is 3:100, and the mass of carbon nanotubes is adjusted to 30 wt% of graphene.

[0186] In this embodiment, only the second hot rolling process is performed during the preparation of the conductive and thermally conductive thin film.

[0187] All other conditions remain the same as in Example 1.

[0188] Comparative Example 1

[0189] The difference between this comparative example and Example 1 is that the composite ink in this comparative example does not contain carbon nanotubes.

[0190] In the preparation method, carbon nanotubes are not added. Instead, the dispersion of GNPs@LMs hybrid microspheres is directly separated and concentrated to obtain a liquid metal / graphene composite ink.

[0191] All other conditions remain the same as in Example 1.

[0192] Comparative Example 2

[0193] The difference between this comparative example and Example 1 is that in this example, the mass ratio of graphene to liquid metal is 3:100, and the mass of carbon nanotubes is adjusted to 30 wt% of graphene.

[0194] In this comparative example, neither the chitosan modification in step (a) nor the sodium alginate modification in step (b) are performed; that is, the electrostatic assembly of graphene and liquid metal is not performed, and the assembly is directly carried out by stirring.

[0195] All other conditions remain the same as in Example 1.

[0196] Comparative Example 3

[0197] The difference between this comparative example and Example 1 is that in this example, the mass ratio of graphene to liquid metal is 3:100, and the mass of carbon nanotubes is adjusted to 30 wt% of graphene.

[0198] In this comparative example, graphene dispersion, liquid metal dispersion and carbon nanotube dispersion were directly mixed together.

[0199] All other conditions remain the same as in Example 1.

[0200] Performance testing

[0201] The conductive and thermally conductive films provided in the above embodiments and comparative examples were subjected to the following performance tests:

[0202] (1) Bending performance: The film bending tester is used to observe whether it cracks or breaks; if it cannot withstand bending, it cannot be used in practice, and its thermal and electrical properties do not need to be tested.

[0203] (2) Thermal conductivity and thermal resistance: The in-plane thermal conductivity and out-of-plane thermal conductivity were obtained by using the standard test methods of ASTM E1461 and ASTM-D5470 (10psi@80℃).

[0204] (3) Electromagnetic shielding performance: The electromagnetic shielding performance of the X-band was tested using a vector network analyzer.

[0205] The test results are shown in Table 1.

[0206] Table 1

[0207]

[0208] From Table 1, we can obtain:

[0209] The conductive and thermally conductive film obtained from the conductive and thermally conductive composite ink provided by this invention has the functions of being flexible, dense, highly conductive, and bidirectionally thermally conductive. At the same time, it also has electromagnetic shielding performance at the GHz band level and high interface thermal conductivity, which can protect key components in electronic devices from electromagnetic interference and high temperature damage, ensuring their high-speed operation. It can be used as electromagnetic shielding and interface heat dissipation in high-performance chips, base stations, aerospace and other fields, which is beneficial to the thinner and lighter design of chip packaging.

[0210] Data analysis of Examples 1 and 8 shows that carbon nanotubes are selected as one-dimensional conductive and thermally conductive materials in this invention. Compared with other materials, they have better electrical and thermal conductivity, and the interfacial bonding force of the micro-nano components is also better, resulting in better bending resistance.

[0211] Data analysis of Examples 1, 6, and 9-13 shows that, in the preparation of the conductive and thermally conductive thin film, the present invention controls the compression deformation during the two hot rolling processes, which better improves the material's density and optimizes its bidirectional thermal and electrical conductivity. However, excessive compression forces the graphene microsheets to further align in-plane, improving in-plane conductivity and thermal conductivity, but reducing out-of-plane thermal conductivity and increasing thermal resistance.

[0212] Data analysis of Examples 1, 6, and 14-15 shows that the present invention further regulates the density and in-plane orientation of the material through two gradient hot rolling processes, and further comprehensively regulates the interface heat dissipation and electromagnetic shielding functions.

[0213] Data analysis of Examples 1, 6 and Comparative Example 1 shows that without the addition of carbon nanotubes as bridging channels, it is difficult to achieve bridging and reinforcement of micro-nano components in the composite ink of the present invention, resulting in a thin film that is not resistant to bending and is difficult to apply in practice.

[0214] Data analysis of Examples 1, 6 and Comparative Example 2 shows that without surface modification and electrostatic assembly of graphene and liquid metal, the present invention cannot obtain a uniformly dispersed ink, and the calendered and dried film is prone to powdering and cannot be used as a film.

[0215] Analysis of the data from Examples 1, 6 and 3 shows that if the present invention does not perform electrostatic assembly before hydrogen bond adsorption recombination, the film will not have a garnet-like structure. The prepared film has poor out-of-plane thermal conductivity and high thermal resistance, and does not have the advantages of being a chip-level thermal interface material.

[0216] In summary, by adjusting the content of one-dimensional conductive and thermally conductive nanofibers and the degree of two-step hot rolling of the garnet-like droplet-based conductive and thermally conductive ink, the bidirectional thermal conductivity and electromagnetic shielding effectiveness of the prepared conductive and thermally conductive film can be improved, resulting in an interfacial thermal resistance as low as 0.09℃cm. 2 / W, a TIM1.5 thin film material with a shielding effectiveness of up to 93dB. While maintaining low thermal resistance, it can also increase the degree of roll deformation, raising the shielding effectiveness to over 100dB, meeting the ultra-high precision electromagnetic interference resistance requirements of chips.

[0217] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A conductive and thermally conductive composite ink, characterized in that, The conductive and thermally conductive composite ink comprises clustered material droplets with a pomegranate-like structure; The garnet-like clustered materials include graphene, liquid metal, and one-dimensional conductive and thermally conductive materials; The graphene is assembled on the surface of the liquid metal to form hybrid microspheres, and the one-dimensional conductive and thermally conductive material is bridged between the hybrid microspheres to form a clustered material with a garnet-like structure.

2. The conductive and thermally conductive composite ink according to claim 1, characterized in that, The one-dimensional conductive and thermally conductive material includes any one or a combination of at least two of carbon nanotubes, carbon nanofibers or metal nanowires, preferably carbon nanotubes. Preferably, the solid content of the clustered material droplets is 300 g / L to 1500 g / L.

3. A method for preparing a conductive and thermally conductive composite ink as described in claim 1 or 2, characterized in that, The preparation method includes the following steps: Graphene is assembled onto a liquid metal surface using a liquid-phase electrostatic assembly method to obtain a hybrid microsphere dispersion; the hybrid microsphere dispersion is then mixed with a one-dimensional conductive and thermally conductive material dispersion to obtain the conductive and thermally conductive composite ink.

4. The preparation method according to claim 3, characterized in that, The graphene includes graphene microsheets, the number of layers of the graphene microsheets is 2 to 10, and the diameter of the graphene microsheets is 0.2 μm to 1 μm; Preferably, the particle size of the liquid metal ranges from 0.8 μm to 4 μm; Preferably, the one-dimensional conductive and thermally conductive material includes any one or a combination of at least two of carbon nanotubes, carbon nanofibers or metal nanowires, preferably carbon nanotubes, and more preferably the length of the carbon nanotubes is 5μm to 50μm; Preferably, the mass ratio of the graphene to the liquid metal is (1~5):100; Preferably, the amount of the one-dimensional conductive and thermally conductive material is 10wt% to 50wt% of the graphene, and more preferably 10wt% to 30wt%.

5. The preparation method according to claim 3 or 4, characterized in that, The liquid-phase electrostatic assembly method includes: Graphene is initially processed and then protonated and dispersed to obtain a graphene dispersion. Liquid metal is deprotonated and dispersed to obtain a liquid metal dispersion. The graphene dispersion and the liquid metal dispersion are electrostatically assembled in the liquid phase to obtain hybrid microspheres of graphene assembled on the surface of liquid metal. Preferably, the pretreatment agent includes tannic acid; Preferably, the amount of the protonable modifier is 1 wt% to 5 wt% of the graphene. Preferably, the amount of the deprotonating modifier is 0.5wt% to 4wt% of the liquid metal; Preferably, the feeding method for the liquid phase electrostatic assembly includes dropping the liquid metal dispersion into the graphene dispersion; Preferably, the stirring speed of the liquid phase electrostatic assembly is 300 rpm to 1000 rpm.

6. The preparation method according to claim 3 or 4, characterized in that, The dispersant of the one-dimensional conductive and thermally conductive material dispersion includes an organic compound with hydrogen bond adsorption, and the organic compound with hydrogen bond adsorption includes sericin macromolecules, the molecular weight of which is 50kDa~200kDa. Preferably, the amount of dispersant in the one-dimensional conductive and thermally conductive material dispersion is 1 wt% to 5 wt% of the one-dimensional conductive and thermally conductive material. Preferably, the hybrid microsphere dispersion is mixed with the one-dimensional conductive and thermally conductive material dispersion by stirring, wherein the stirring speed is 300 rpm to 600 rpm; Preferably, the hybrid microsphere dispersion is mixed with a one-dimensional conductive and thermally conductive material dispersion, and then separated and concentrated to obtain the conductive and thermally conductive composite ink.

7. A conductive and thermally conductive thin film, characterized in that, The raw materials for the conductive and thermally conductive film include the conductive and thermally conductive composite ink as described in claim 1 or 2, or the conductive and thermally conductive ink prepared by the preparation method described in any one of claims 3-6.

8. A method for preparing a conductive and thermally conductive thin film as described in claim 7, characterized in that, The preparation method includes the following steps: The conductive and thermally conductive composite ink as described in claim 1 or 2, or the conductive and thermally conductive ink prepared by the preparation method as described in any one of claims 3-6, is sequentially subjected to calendering coating, drying, and hot rolling to obtain the conductive and thermally conductive film.

9. The preparation method according to claim 8, characterized in that, The hot rolling process includes a first hot rolling process and a second hot rolling process performed in a gradient. Preferably, the temperature of the first hot roller is 40℃~80℃, the compression deformation of the first hot roller is 3%~8%, and the time of the first hot roller is 1h~3h; Preferably, the temperature of the second hot roller is 110℃~140℃, the compression deformation of the second hot roller is 9%~16%, and the time of the second hot roller is 1h~3h.

10. An application of a conductive and thermally conductive thin film, characterized in that, The application includes using the conductive and thermally conductive thin film as described in claim 7 or the conductive and thermally conductive thin film prepared by the preparation method as described in claim 8 or 9 as a thermal interface material with both electromagnetic shielding and interface heat dissipation functions in capless packaged semiconductor devices.

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