WO2022206509A1 - 一种导热材料及其制作方法、半固化片、层压板、电路板 - Google Patents

一种导热材料及其制作方法、半固化片、层压板、电路板 Download PDF

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WO2022206509A1
WO2022206509A1 PCT/CN2022/082479 CN2022082479W WO2022206509A1 WO 2022206509 A1 WO2022206509 A1 WO 2022206509A1 CN 2022082479 W CN2022082479 W CN 2022082479W WO 2022206509 A1 WO2022206509 A1 WO 2022206509A1
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thermally conductive
liquid crystal
conductive material
conductive filler
crystal polymer
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PCT/CN2022/082479
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English (en)
French (fr)
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张齐艳
蔡黎
高峰
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华为技术有限公司
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    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B32B15/092—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin comprising epoxy resins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/14—Layered products comprising a layer of metal next to a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/20—Layered products comprising a layer of metal comprising aluminium or copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/02—Layered products essentially comprising sheet glass, or glass, slag, or like fibres in the form of fibres or filaments
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    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/04—Layered products comprising a layer of synthetic resin as impregnant, bonding, or embedding substance
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
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    • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
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    • C08K3/34—Silicon-containing compounds
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    • C08K3/38—Boron-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K9/00—Use of pretreated ingredients
    • C08K9/04—Ingredients treated with organic substances
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    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
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    • C08K9/04—Ingredients treated with organic substances
    • C08K9/06—Ingredients treated with organic substances with silicon-containing compounds
    • C—CHEMISTRY; METALLURGY
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    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L71/00—Compositions of polyethers obtained by reactions forming an ether link in the main chain; Compositions of derivatives of such polymers
    • C08L71/08—Polyethers derived from hydroxy compounds or from their metallic derivatives
    • C08L71/10—Polyethers derived from hydroxy compounds or from their metallic derivatives from phenols
    • C08L71/12—Polyphenylene oxides
    • C—CHEMISTRY; METALLURGY
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    • C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
    • C08L79/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08L79/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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    • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/03—Use of materials for the substrate
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/03—Use of materials for the substrate
    • H05K1/0313—Organic insulating material
    • H05K1/0353—Organic insulating material consisting of two or more materials, e.g. two or more polymers, polymer + filler, + reinforcement
    • H05K1/036—Multilayers with layers of different types
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/46—Manufacturing multilayer circuits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2250/00—Layers arrangement
    • B32B2250/40—Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/02—Coating on the layer surface on fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
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    • B32B2255/26—Polymeric coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
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    • B32B2457/00—Electrical equipment
    • B32B2457/08—PCBs, i.e. printed circuit boards
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
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    • C08K3/00—Use of inorganic substances as compounding ingredients
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    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
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Definitions

  • the present application relates to the technical field of nanomaterials, and in particular, to a thermally conductive material and a method for making the same, a prepreg, a laminate, and a circuit board.
  • thermally conductive materials with high thermal conductivity can be added to polymers to form thermally conductive materials.
  • the above thermally conductive materials are applied to electronic devices for the purpose of reducing their internal heat.
  • electronic devices are becoming more and more integrated and miniaturized, and the power density has been greatly improved, and the heat generated by electronic devices during operation has increased dramatically.
  • the thermal conductivity of the current thermally conductive material is difficult to meet the use requirements, resulting in the inability of heat to be dissipated in time and accumulated continuously, which seriously affects the safe working conditions and performance of the equipment.
  • Embodiments of the present application provide a thermally conductive material and a method for making the same, a prepreg, a laminate, and a circuit board, which are used to provide a thermally conductive material with high thermal conductivity.
  • a thermally conductive material in some embodiments of the present application, includes a matrix polymer, a curing agent, and a modified thermally conductive filler.
  • the modified thermally conductive filler includes a thermally conductive filler and a liquid crystal polymer grafted and coated on the surface of the thermally conductive filler. In the modified thermally conductive filler, a chemical bond is formed between the liquid crystal polymer and the matrix polymer through a curing agent.
  • the thermally conductive filler and the liquid crystal polymer can be connected by a strong covalent bond, so that the thermal conductive filler and the liquid crystal polymer are bonded together. It is more compact, improves the interface bonding force between the thermally conductive filler and the polymer matrix, can eliminate the air thermal resistance between the thermally conductive filler and the polymer matrix, and is more conducive to reducing the interface thermal resistance between the thermally conductive filler and the polymer matrix.
  • the liquid crystal polymer is a macromolecular liquid crystal with regular liquid crystal cells inside, so the liquid crystal polymer can form a regular stacking structure in a specific crystal plane direction along the thermally conductive filler particles.
  • the regular structure is conducive to phonon transmission, thereby effectively reducing the phonon dispersion at the interface between the thermally conductive filler and the polymer matrix, and is conducive to reducing the interface thermal resistance between the thermally conductive filler and the polymer matrix.
  • thermosetting liquid crystal polymer itself has a high thermal conductivity, for example, the thermal conductivity can be greater than or equal to 0.25W/mk, and its thermal conductivity is higher than that of the amorphous polymer, which is beneficial to improve the thermal conductivity of the final thermally conductive material. .
  • the liquid crystal polymer includes a liquid crystal epoxy.
  • liquid crystal epoxy resin includes biphenyl type liquid crystal epoxy resin, arylate type liquid crystal epoxy resin, ⁇ -methylstyrene type liquid crystal epoxy resin, azo type liquid crystal epoxy resin, methyleneamine type liquid crystal epoxy resin At least one of resin, naphthalene type liquid crystal epoxy resin, and triphenylene type liquid crystal epoxy resin.
  • the above liquid crystal polymer has high thermal conductivity, and the thermal conductivity can be greater than or equal to 0.25W/mk.
  • the liquid crystal polymer includes a functional group that can undergo a cross-linking reaction, and the functional group includes at least one of an epoxy group, an alkenyl group, an alkynyl group, a cyanate group, an isocyanate group, and a benzocyclobutenyl group. kind.
  • the liquid crystal polymer includes a regular liquid crystal cell, and the liquid crystal cell includes at least one of a biphenyl structure, an aryl ester structure, an ⁇ -methylstyrene structure, an azo structure, a methyleneamine structure, a binaphthyl structure, and a triphenylene structure. .
  • the functional groups of the liquid crystal polymer can undergo a cross-linking reaction with the functional groups on the surface of the thermally conductive filler to form chemical bonds, such as covalent bonds.
  • the interface bonding strength between the thermally conductive filler and the liquid crystal polymer is further improved, which is beneficial to eliminate the air thermal resistance caused by the interface gap, thereby improving the thermal conductivity of the thermally conductive material.
  • the thermally conductive filler includes nanoscale or microscale inorganic thermally conductive materials.
  • the inorganic thermally conductive material includes at least one of silicon dioxide, aluminum oxide, aluminum nitride, boron nitride, silicon carbide, and diamond.
  • silica and alumina have relatively low thermal conductivity, but are readily available and inexpensive.
  • Aluminum nitride, boron nitride, and silicon carbide have relatively high thermal conductivity.
  • a plurality of modified thermally conductive fillers are stacked to form a thermally conductive network structure, and the liquid crystal polymers of the plurality of modified thermally conductive fillers in contact are connected by forming chemical bonds with a curing agent.
  • the filling amount of the thermally conductive filler in the matrix polymer is relatively high, multiple modified thermally conductive fillers can be stacked to form a dense thermally conductive network structure, and the liquid crystal polymers of the multiple modified thermally conductive fillers in contact are connected by chemical bonds. In this way, heat can be transmitted in the form of phonons in the thermal conduction network structure through the vibration of the crystal lattice, thereby further improving the thermal conduction efficiency of the final thermal conduction material.
  • the particle sizes of at least two thermally conductive fillers in the thermally conductive material are different.
  • thermally conductive fillers with smaller particle sizes can be embedded in the voids formed between the thermally conductive fillers with larger particle sizes, thereby further improving the compactness of the thermally conductive network structure formed by the accumulation of multiple modified thermally conductive fillers. It is beneficial to further improve the thermal conductivity of the obtained thermally conductive material.
  • the above method includes: first, dispersing the thermally conductive filler in a solution having a liquid crystal polymer to obtain a thermally conductive filler dispersion. Then, after heating and refluxing reaction, filtration, washing and drying of the thermally conductive filler dispersion liquid, grinding treatment is performed to obtain a modified thermally conductive filler. The surfaces of the thermally conductive fillers in the modified thermally conductive fillers are all grafted and coated with liquid crystal polymers. Then, the modified thermally conductive filler is dispersed in the solution with the matrix polymer to obtain the thermally conductive material precursor.
  • the thermal conductive material precursor is poured into the mold, and subjected to vacuum defoaming and curing or semi-curing treatment to obtain the thermal conductive material, or, the thermal conductive material precursor is mixed with an organic solvent, and the prepreg is obtained by adjusting the solid content of the solution, The prepreg is coated on the substrate and baked to form a thermally conductive material covering the substrate.
  • the manufacturing method of the thermally conductive material has the same technical effect as the thermally conductive material provided in the foregoing embodiments, and details are not described herein again.
  • the method before dispersing the thermally conductive filler in the solution with the liquid crystal polymer, the method further includes: first, adding the thermally conductive filler into the solution with a coupling agent to perform coupling agent treatment. Then, the solution treated with the coupling agent is filtered, washed and dried. The surface of the thermally conductive filler is treated with a coupling agent, and different functional groups can be introduced into the surface of the thermally conductive filler according to different silane coupling agents.
  • the introduced functional group can chemically react with the liquid crystal polymer to form a covalent bond, thereby further improving the interface bonding strength between the thermally conductive filler and the liquid crystal polymer, which is beneficial to eliminate the air thermal resistance caused by the interface gap, thereby improving the thermal conductivity of the material. thermal conductivity.
  • dispersing the thermally conductive filler in a solution with a liquid crystal polymer to obtain a thermally conductive filler dispersion includes: first, adding the thermally conductive filler into an organic solvent and dispersing. Then, the dispersed solution is stirred and passed in an inert gas, a catalyst and a liquid crystal polymer are added, and a heating and refluxing reaction is carried out to obtain a thermally conductive filler dispersion.
  • the thermally conductive filler can be dispersed more uniformly.
  • dispersing the thermally conductive filler in the solution with the liquid crystal polymer to obtain the thermally conductive filler dispersion includes: first, adding the thermally conductive filler and the liquid crystal polymer to an organic solvent and dispersing. Then, the dispersed solution is stirred and passed in an inert gas, a catalyst is added, and a heating and reflux reaction is carried out to obtain a thermally conductive filler dispersion. In this way, the thermally conductive filler can be dispersed in the organic solvent together with the liquid crystal polymer.
  • a thermally conductive material in other embodiments of the present application, includes a matrix polymer, a liquid crystal polymer, a curing agent and a thermally conductive filler.
  • the thermally conductive filler is filled in the matrix polymer. At least a portion of the surface of the thermally conductive filler is coated with a liquid crystal polymer. A chemical bond is formed between the liquid crystal polymer and the matrix polymer through a curing agent. The affinity of the liquid crystal polymer with the thermally conductive filler is greater than that of the matrix polymer with the thermally conductive filler.
  • the thermally conductive filler when the thermally conductive filler is dispersed in the blend composed of the liquid crystal polymer and the matrix polymer, the thermally conductive filler will be selectively distributed in the liquid crystal polymer with stronger affinity.
  • the thermally conductive network structure formed by the accumulation of a plurality of thermally conductive fillers the molecular chains of the in-situ coated liquid crystal polymer are regularly stacked along a certain crystal plane direction of the filler particles.
  • the thermally conductive filler and the liquid crystal polymer are connected by intermolecular forces and partial chemical bonds, ie covalent bonds.
  • a covalent bond is formed between the liquid crystal polymer and the matrix polymer through a curing agent.
  • the liquid crystal polymer is coated on the surface of the thermally conductive network structure to form a network chain structure.
  • the liquid crystal polymers in the network chain structure are connected by forming chemical bonds with the curing agent. Therefore, it is beneficial to effectively reduce the interface thermal resistance between the filler and the polymer matrix, so that heat can be transmitted in the form of phonons in the thermal conduction network structure through the vibration of the crystal lattice.
  • the thermally conductive material precursor is cured, the above-mentioned network chain structure can form a dense thermal conduction path, which is beneficial to efficient heat transfer.
  • the liquid crystal polymer includes a liquid crystal epoxy.
  • liquid crystal epoxy resin includes biphenyl type liquid crystal epoxy resin, arylate type liquid crystal epoxy resin, ⁇ -methylstyrene type liquid crystal epoxy resin, azo type liquid crystal epoxy resin, methyleneamine type liquid crystal epoxy resin At least one of resin, naphthalene type liquid crystal epoxy resin, and triphenylene type liquid crystal epoxy resin.
  • the above liquid crystal polymer has high thermal conductivity, and the thermal conductivity can be greater than or equal to 0.25W/mk.
  • the liquid crystal polymer includes a functional group that can undergo a cross-linking reaction, and the functional group includes at least one of an epoxy group, an alkenyl group, an alkynyl group, a cyanate group, an isocyanate group, and a benzocyclobutenyl group. kind.
  • the liquid crystal polymer includes a regular liquid crystal cell, and the liquid crystal cell includes at least one of a biphenyl structure, an aryl ester structure, an ⁇ -methylstyrene structure, an azo structure, a methyleneamine structure, a binaphthyl structure, and a triphenylene structure. .
  • the functional groups of the liquid crystal polymer can undergo a cross-linking reaction with the functional groups on the surface of the thermally conductive filler to form chemical bonds, such as covalent bonds.
  • the interface bonding strength between the thermally conductive filler and the liquid crystal polymer is further improved, which is beneficial to eliminate the air thermal resistance caused by the interface gap, thereby improving the thermal conductivity of the thermally conductive material.
  • the base polymer includes at least one of polyphenylene ether, hydrocarbon resin, epoxy resin, cyanate ester, bismaleimide resin, silicone resin, and polyimide.
  • polyphenylene ether hydrocarbon resin
  • epoxy resin epoxy resin
  • cyanate ester bismaleimide resin
  • silicone resin silicone resin
  • polyimide polyimide
  • the weight ratio of the liquid crystal polymer accounts for 3-30 wt % of the total amount of polymers in the thermally conductive material, which is beneficial to improve the thermal conductivity of the thermally conductive material.
  • the thermally conductive filler includes nanoscale or microscale inorganic thermally conductive materials.
  • the inorganic thermally conductive material includes at least one of silicon dioxide, aluminum oxide, aluminum nitride, boron nitride, silicon carbide, and diamond.
  • silica and alumina have relatively low thermal conductivity, but are readily available and inexpensive.
  • Aluminum nitride, boron nitride, and silicon carbide have relatively high thermal conductivity.
  • the particle sizes of at least two thermally conductive fillers in the thermally conductive material are different.
  • thermally conductive fillers with smaller particle sizes can be embedded in the voids formed between the thermally conductive fillers with larger particle sizes, thereby further improving the compactness of the thermally conductive network structure formed by the accumulation of multiple modified thermally conductive fillers. It is beneficial to further improve the thermal conductivity of the obtained thermally conductive material.
  • Another aspect of the embodiments of the present application provides a method for manufacturing any of the above thermally conductive materials.
  • the above method includes: first, adding the thermally conductive filler and the liquid crystal polymer into the organic solvent, and stirring, dissolving and dispersing. Then, after stirring, the matrix polymer, the curing agent and the curing accelerator are added, and the stirring is continued to obtain the thermally conductive material precursor.
  • the affinity of the liquid crystal polymer and the thermally conductive filler is greater than that of the matrix polymer and the thermally conductive filler.
  • the thermal conductive material precursor is poured into the mold, and subjected to vacuum defoaming and curing or semi-curing treatment to obtain the thermal conductive material, or, the thermal conductive material precursor is mixed with an organic solvent, and the prepreg is obtained by adjusting the solid content of the solution, The prepreg is coated on the substrate and baked to form a thermally conductive material covering the substrate.
  • the technical effect of the above-mentioned method for preparing a thermally conductive material is the same as that of the above-mentioned thermally conductive material, which will not be repeated here.
  • the prepreg includes a substrate and any one of the above-mentioned thermally conductive materials, and the thermally conductive material coats the substrate.
  • the prepreg has the same technical effect as the thermally conductive material provided in the foregoing embodiments, and details are not repeated here.
  • the laminate includes copper foil and the prepreg described above. Copper foil covers the surface of the prepreg.
  • the laminate has the same technical effect as the thermally conductive material provided in the foregoing embodiments, which will not be repeated here.
  • the circuit board includes the above-mentioned prepreg and the above-mentioned laminate, and the laminate and the prepreg are laminated.
  • the circuit board has the same technical effects as the prepreg and laminate provided in the foregoing embodiments, and details are not described herein again.
  • FIG. 1 is an application scenario of a thermally conductive material provided by an embodiment of the present application
  • FIG. 2 is an application scenario of another thermally conductive material provided by an embodiment of the present application.
  • FIG. 3 is a manufacturing method of a thermally conductive material provided by an embodiment of the present application.
  • FIG. 4 is another manufacturing method of a thermally conductive material provided by an embodiment of the present application.
  • FIG. 5 is a schematic structural diagram of a modified thermally conductive material prepared by the manufacturing method shown in FIG. 4;
  • FIG. 6 is a schematic diagram of the formation principle of the modified thermally conductive material prepared by the manufacturing method shown in FIG. 4;
  • FIG. 7A is a schematic structural diagram of a thermally conductive material prepared by the manufacturing method shown in FIG. 4;
  • FIG. 7B is another schematic structural diagram of the thermally conductive material prepared by the manufacturing method shown in FIG. 4;
  • 7C is another schematic structural diagram of the thermally conductive material prepared by the manufacturing method shown in FIG. 4;
  • FIG. 8 is a schematic structural diagram of a thermally conductive material provided by the related art.
  • FIG. 9 is a schematic diagram of the generation of interface thermal resistance provided by an embodiment of the present application.
  • FIG. 10 is another schematic structural diagram of the thermally conductive material provided by the embodiment of the present application.
  • 10-thermal interface material 11-chip; 12-carrying substrate; 13-underfill; 14-plastic compound; 15-plastic cover plate; 16-thermally conductive adhesive; 17-thermally conductive potting compound; 18-prepreg; 19- CCL; 22-liquid crystal polymer; 30-thermally conductive filler; 200-modified thermally conductive filler; 20-liquid crystal cell; 21-functional group of liquid crystal polymer; 31-functional group of thermally conductive filler; 41-thermal conductive material precursor ; 201 - thermally conductive network structure; 40 - matrix polymer; 22 - liquid crystal polymer; 301 - network chain structure.
  • first”, second, etc. are only used for descriptive purposes, and should not be understood as indicating or implying relative importance or implying the number of indicated technical features.
  • a feature defined as “first”, “second”, etc. may expressly or implicitly include one or more of that feature.
  • orientation terms such as “upper”, “lower”, “left” and “right” are defined relative to the orientation in which the components in the drawings are schematically placed, and it should be understood that these directional terms are Relative notions, they are used for relative description and clarification, which may vary accordingly depending on the orientation in which components are placed in the figures.
  • connection should be understood in a broad sense.
  • connection may be a fixed connection, a detachable connection, or an integrated body; it may be directly connected, or Can be indirectly connected through an intermediary.
  • the electronic device may include a mobile phone (mobile phone), a tablet computer (pad), a TV, a smart wearable product (for example, a smart watch, a smart bracelet), a virtual reality (virtual reality, VR) equipment, augmented reality (augmented reality AR) equipment, etc.
  • the above-mentioned electronic device may also be an electronic product such as a rechargeable electric vehicle, a rechargeable household small electrical appliance (such as a soymilk maker, a cleaning robot), and an unmanned aerial vehicle.
  • some structures in the electronic device may be prepared by using the thermally conductive material provided in the embodiments of the present application.
  • the application scenarios of the thermally conductive materials provided in the embodiments of the present application in the above-mentioned electronic products will be exemplified below.
  • the above thermally conductive material can be used to prepare a thermally conductive block in a semi-cured state or a cured state.
  • the thermally conductive block can be used to prepare, for example, a thermal interface material (TIM) 10 disposed on the surface of the chip 11 as shown in (a) of FIG. 1 , as shown in (b) of FIG. 1 .
  • An underfill 13 is placed between the chip 11 and the carrier substrate 12 , such as the molding compound 14 shown in (c) in FIG.
  • the plastic cover 15 prepared as the housing of the above-mentioned electronic device, as shown in (e) in FIG. f)
  • the thermally conductive potting compound 17 and the like applied in the potting process shown.
  • the semi-cured or cured thermally conductive blocks can be directly applied, or they can be heated, or further cured before being applied. Do limit.
  • the above-mentioned thermally conductive material can also be used for the prepared prepreg 18 as shown in (a) of FIG. 2 .
  • the embodiments of the present application also provide a circuit board, such as a printed circuit board (printed circuit board, PCB).
  • the PCB can be made by stacking the multi-layer CCL 19 and the prepreg 18, and performing processes such as hot pressing, processing, etching, drilling and copper plating according to design requirements.
  • thermally conductive material The structure, manufacturing process, and heat conduction principle of the above-mentioned thermally conductive material will be illustrated in detail below according to different manufacturing methods of the thermally conductive material.
  • a graft coating method is adopted, that is, a grafting polymerization (grating to) method is adopted, and the thermal conductive filler is subjected to graft coating modification treatment through a liquid crystal polymer. Thereby, the molecular chains of the liquid crystal polymer are grafted to the surface of the thermally conductive filler. Then, the modified thermally conductive filler is added to the polymer matrix to form the thermally conductive material provided in the first example.
  • the manufacturing method of the thermally conductive material may include S101 and S102 as shown in FIG. 3 .
  • S101 in this example may include S201 and S202 as shown in FIG. 4 , or may include S211 , S201 and S202 .
  • the thermally conductive filler is dispersed in a solution in which a certain amount of liquid crystal polymer is dissolved to obtain a thermally conductive filler dispersion.
  • the catalyst is added, heated and refluxed to react sufficiently, and then the thermally conductive filler is obtained by filtration, and then, the thermally conductive filler is washed with an organic solvent to remove the unreacted liquid crystal polymer in the thermally conductive filler. Then, the thermally conductive filler is dried and ground (or pulverized) to obtain the modified thermally conductive filler 200 as shown in FIG. 5 .
  • the modified thermally conductive filler 200 includes a thermally conductive filler 30 and a liquid crystal polymer 22 grafted and coated on the surface of the thermally conductive filler 30 . Therefore, the surface of the thermally conductive filler 30 can be completely or nearly completely surrounded by the shell structure formed by the liquid crystal polymer 22 , and the thermally conductive filler 30 and the liquid crystal polymer 22 are bonded by covalent bonds.
  • the above-mentioned dispersing the thermally conductive filler in a solution in which a certain amount of liquid crystal polymer is dissolved refers to pouring a filler material composed of a plurality of granular thermally conductive fillers 30 into the above-mentioned solution, and pouring a large amount of the filler material into the solution.
  • a particulate thermally conductive filler 30 is dispersed in the solution.
  • the surface of at least one thermally conductive filler 30 is grafted and coated with the above-mentioned liquid crystal polymer 22 , so that at least one particulate modified thermally conductive filler 200 can be formed.
  • the liquid crystal polymer 22 is grafted and coated on the surface of the thermally conductive filler 30, which means that, in the process of manufacturing the modified thermally conductive filler 200 by the above-mentioned graft polymerization method, the thermally conductive filler 200 can be prepared with acceptable manufacturing accuracy. 30 may be fully or nearly fully encapsulated by liquid crystal polymer 22 .
  • the thermally conductive filler in order to prepare the above-mentioned thermally conductive filler dispersion liquid, may be added to an organic solvent and dispersed.
  • the thermal conductive filler is added to an appropriate amount of organic solvent, and ultrasonically dispersed for 0.5-2h. Then, the dispersed solution is stirred and passed in an inert gas, a catalyst and a liquid crystal polymer are added, and a heating and reflux reaction is carried out to obtain a thermally conductive filler dispersion.
  • liquid crystal polymer such as liquid crystal epoxy resin (LCEP)
  • LCEP liquid crystal epoxy resin
  • the thermally conductive filler is first dispersed in an organic solvent, and then the liquid crystal polymer is added.
  • the thermally conductive filler and the liquid crystal polymer may be added to an organic solvent and dispersed. Then, the dispersed solution is stirred and passed in an inert gas, a catalyst is added, and a heating and reflux reaction is carried out to obtain a thermally conductive filler dispersion.
  • the thermally conductive filler and the liquid crystal polymer are dispersed together in an organic solvent.
  • the method of dispersing the thermally conductive filler in an organic solvent first, and then adding the liquid crystal polymer can make the thermally conductive filler more uniformly dispersed.
  • the surface of each thermally conductive filler can be covered by the shell layer formed by the liquid crystal polymer.
  • the above-mentioned thermally conductive fillers may include nanoscale or microscale inorganic thermally conductive materials.
  • the above-mentioned inorganic thermally conductive material may include at least one of silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), aluminum nitride (AlN), boron nitride (BN), silicon carbide (SiC), and the like .
  • the above-mentioned thermally conductive filler can also be nano-diamond.
  • the thermal conductivity of silicon dioxide (SiO 2 ) and aluminum oxide (Al 2 O 3 ) is relatively low, for example, less than 40 W/mk.
  • Aluminum nitride (AlN), boron nitride (BN), silicon carbide (SiC), and nanodiamond have high thermal conductivity, eg, greater than 80 W/mk. Therefore, the thermal conductivity of the finally prepared thermally conductive material can be effectively improved.
  • thermal conductivity may also be referred to as thermal conductivity, which is a measure of the thermal conductivity of a substance.
  • the thermal conductivity specifically refers to the heat transferred through the unit horizontal cross-sectional area per unit time when the vertical downward gradient of the temperature is 1°C/m.
  • the unit of thermal conductivity is Watt ⁇ meter -1 ⁇ Kel -1 (W ⁇ m -1 ⁇ K -1 ), or, watts per meter Kelvin (W/mk).
  • the liquid crystal polymer used may be a thermosetting liquid crystal polymer, and the liquid crystal polymer has a relatively high thermal conductivity (for example, the thermal conductivity may be greater than or equal to 0.25W/mk).
  • the liquid crystal polymer may include a liquid crystal epoxy.
  • liquid crystal epoxy resin includes biphenyl type liquid crystal epoxy resin, arylate type liquid crystal epoxy resin, ⁇ -methylstyrene type liquid crystal epoxy resin, azo type liquid crystal epoxy resin, methyleneamine type liquid crystal epoxy resin At least one of resin, naphthalene type liquid crystal epoxy resin, triphenylene type liquid crystal epoxy resin, and the like.
  • the above-mentioned liquid crystal polymer is a prepolymer, and the molecular weight of the prepolymer is relatively low.
  • the liquid crystal polymer has a functional group (referred to as the functional group 21 of the polymer) as shown in FIG. 6 that can undergo a crosslinking reaction.
  • the functional group 21 of the polymer may include at least one of epoxy group, alkenyl group (vinyl group, propenyl group, etc.), alkynyl group, cyanate group, isocyanate group, benzocyclobutenyl group, and the like.
  • the liquid crystal polymer may further include a liquid crystal cell 20 as shown in FIG. 6 .
  • the above-mentioned liquid crystal cells 20 are regularly arranged.
  • the liquid crystal cell 20 refers to a group with liquid crystal characteristics.
  • the liquid crystal cell 20 may include a biphenyl structure. aryl ester structure Alpha-methylstyrene structure Azo structure Methyleneamine structure where Y is Binaphthyl structure Triphenylene structure at least one of etc.
  • the functional groups 21 of the liquid crystal polymer such as functional groups
  • the functional groups 31 of the thermally conductive filler can chemically react with the functional groups 31 of the thermally conductive filler to form chemical bonds, such as covalent bonds.
  • the manufacturing method of the thermally conductive material may further include S211 (coupling agent processing on the thermally conductive filler) as shown in FIG. 4 .
  • S211 coupling agent processing on the thermally conductive filler
  • the thermally conductive filler 30 is added to the solution with the coupling agent, the coupling agent is treated, and the solution treated with the coupling agent is filtered, washed and dried.
  • the coupling agent into the mixed solvent mainly composed of ethanol and deionized water, then add the thermal conductive filler, and react at 25-80° C. for 0.5-12 hours.
  • the solvent in the solution obtained by S210 can be removed by filtration, washed with solvents such as ethanol and deionized water to remove the unreacted coupling agent, and then dried at 80-140 °C for 0.5-6 h.
  • the above-mentioned coupling agent may be a silane coupling agent.
  • the surface of the thermally conductive filler 30 is treated with a coupling agent, and different functional groups, such as epoxy group, amino group, vinyl group, etc., can be introduced into the surface of the thermally conductive filler 30 according to different silane coupling agents.
  • the introduced functional group can chemically react with the liquid crystal polymer in S201 to form a covalent bond, thereby further improving the interface bonding strength between the thermally conductive filler and the liquid crystal polymer, which is conducive to eliminating the air thermal resistance caused by the interface gap, thereby enabling Improve the thermal conductivity of thermally conductive materials.
  • the thermally conductive material precursor 41 as shown in FIG. 7A can be obtained.
  • the above-mentioned liquid crystal polymer 22 graft-coated thermally conductive filler 30, base polymer 40, and curing agent are added to an appropriate amount of organic solvent according to a certain proportion, and after mechanical stirring for 0.5-3 hours, an appropriate amount of curing accelerator is added to dissolve and disperse. Stirring is continued for 0.5-2 h to prepare the thermally conductive material precursor 41 .
  • the material of the matrix polymer used in S202 is not limited, for example, it may be epoxy resin.
  • the modified thermally conductive filler 200 in the above-mentioned thermally conductive material precursor 41 one end of the liquid crystal polymer 22 grafted on the surface of the thermally conductive filler 30 is connected with the thermally conductive filler 30 through a covalent bond, and the other end of the liquid crystal polymer 22 is connected by a covalent bond. Covalent cross-linking with the base polymer 40 occurs through the curing agent.
  • the liquid crystal polymer 22 grafted on the surface of the thermally conductive filler 30 can form a regular stacking structure in a specific crystal plane direction along the particles of the thermally conductive filler 30 .
  • the filling amount of the thermally conductive filler 30 in the matrix polymer 40 is relatively high, as shown in FIG.
  • the liquid crystal polymer 22 on the surface of the adjacent thermally conductive fillers 30 also undergoes a crosslinking reaction through the curing agent, so that the gap between the adjacent modified thermally conductive fillers 200 can be eliminated, and in the thermally conductive material precursor 41, A dense heat-conducting network composed of a plurality of modified heat-conducting fillers 200 connected to each other is formed.
  • the thermally conductive filler 30 may be directly added to the base polymer 40 to form a thermally conductive material. At this time, the periphery of each filler is surrounded by the matrix polymer 40 .
  • the molecules in the thermally conductive filler 30 have a regular crystal structure as shown in Figure 9, and the atoms are arranged in an orderly manner. Therefore, in the thermally conductive filler 30, heat (indicated by black arrows in the figure) can be transferred from the left end as shown in FIG. 9 to the right end as shown in FIG. 9 through lattice vibration. Therefore, the thermal conductivity of the thermally conductive filler 30 is relatively high.
  • the matrix polymer 40 has an amorphous structure, and the molecular chains are arranged disorderly. Therefore, as shown in FIG. 9, in the matrix polymer 40, the heat transport is disordered so that the phonon scattering is large and the thermal conductivity is low. Therefore, the thermally conductive filler 30 is directly added to the thermally conductive material prepared from the base polymer 40.
  • the thermally conductive material provided in the embodiment of the present application includes a matrix polymer 40 , a curing agent and a modified thermally conductive filler 200 .
  • the modified thermally conductive filler 200 is filled in the matrix polymer 40 , and the surface of the thermally conductive filler 30 in the modified thermally conductive filler 200 is grafted and coated with the liquid crystal polymer 22 .
  • the thermally conductive filler 30 and the liquid crystal polymer 22 are connected by strong covalent bonds, and the liquid crystal polymer 22 covering the thermally conductive filler 30 can eliminate the gap between the thermally conductive filler 30 and the polymer matrix.
  • the air thermal resistance is more conducive to reducing the interface thermal resistance between the thermally conductive filler and the polymer matrix.
  • the liquid crystal polymer 22 is a macromolecular liquid crystal with regular liquid crystal cells 20 inside, so the liquid crystal polymer 22 can form a regular stacking structure along the particles of the thermal conductive filler 30 in a specific crystal plane direction.
  • the regular structure is conducive to phonon transmission, thereby effectively reducing the phonon dispersion at the interface between the thermally conductive filler 30 and the polymer matrix, and is conducive to reducing the interface thermal resistance between the thermally conductive filler 30 and the polymer matrix.
  • thermosetting liquid crystal polymer itself has a high thermal conductivity, for example, the thermal conductivity can be greater than or equal to 0.25W/mk, and its thermal conductivity is higher than that of the amorphous polymer, which is beneficial to improve the thermal conductivity of the final thermally conductive material. .
  • the method of grafting and coating the surface of the thermally conductive filler 30 with the liquid crystal polymer 22 improves the heat dissipation capability of the thermally conductive material.
  • the preparation method is simpler, the yield is high, the effect is obvious, and it is more suitable for industrial production.
  • a plurality of modified thermally conductive fillers 200 can be stacked to form a dense thermally conductive network structure 201 , and a plurality of modified thermally conductive fillers 200 in contact with each other
  • the liquid crystal polymers 22 of the thermally conductive filler 200 are connected by chemical bonds. In this way, heat can be transmitted in the form of phonons in the thermal conduction network structure 201 through the vibration of the crystal lattice, thereby further improving the thermal conduction efficiency of the final thermal conduction material.
  • the embodiment of the present application does not limit the particle size of the thermally conductive filler 30 in the thermally conductive material.
  • FIG. 7A and FIG. 7B are described by taking an example that the particle size of the thermally conductive filler is the same.
  • the particle sizes of at least two thermally conductive fillers 30 in the thermally conductive material may be different.
  • the thermally conductive fillers 30 with smaller particle size can be embedded, so as to further improve the compactness of the thermally conductive network structure 201 formed by stacking a plurality of modified thermally conductive fillers 200, which is beneficial to further improve the thermal conductivity of the obtained thermally conductive material.
  • the thermal conductive material precursor is mixed with an organic solvent, and the prepreg is obtained by adjusting the solid content of the solution.
  • the thermally conductive material precursor 41 can be mixed with an organic solvent, and the prepreg can be obtained by adjusting the solid content of the solution (for example, 50-80 wt %).
  • the prepreg is coated on the substrate and baked to form a thermally conductive material covering the substrate.
  • the above-mentioned base material and the thermally conductive material covering the base material can be used to constitute the prepreg 18 shown in (a) of FIG. 2 .
  • the prepreg in the process of making the prepreg 18, can be coated on a substrate, such as glass cloth (eg, E-type glass cloth), and baked in an oven at 140-190° C. for 1-30 minutes A prepreg with a resin content of 60-85% was produced. It can be seen from the above that a copper foil is placed on the top and bottom of the prepared prepreg 18, placed in a vacuum hot press at a pressure of 1-50MPa and a temperature of 170-230°C, and pressing can be obtained as shown in Figure 2 ( b) CCL19 as indicated.
  • the above is only an example of the manufacturing process of the prepreg 18 and the CCL 19 .
  • the present application does not limit the manufacturing methods of the prepreg 18 and the CCL 19 , and other manufacturing methods will not be repeated here.
  • FIGS. 7A , 7B and 8 represent a possible transmission path of heat in the form of phonons in the thermally conductive material. This application does not limit the transmission path, and the realization of other transmission paths The methods are not repeated here.
  • the material of the thermally conductive filler 30 is aluminum oxide (Al 2 O 3 )
  • the material of the liquid crystal polymer 22 is tetramethyl biphenyl epoxy resin (thermal conductivity is 0.27W/mk)
  • the matrix polymer 40 is The material is bisphenol A epoxy resin.
  • the manufacturing method of the thermally conductive material precursor 41 may include the above-mentioned S201 and S202. The methods of S201 , S202 , S102 , and the prepreg 18 and CCL19 are illustrated below with reference to the specific materials of the thermally conductive filler 30 , the liquid crystal polymer 22 and the matrix polymer 40 .
  • the above-mentioned S201 is performed to manufacture the modified thermally conductive filler 200 .
  • alumina (Al 2 O 3 ) particles as the thermally conductive filler 30 and tetramethylbiphenyl epoxy resin as the liquid crystal polymer 22 are added to the organic solvent butanone.
  • the mass ratio of alumina (Al 2 O 3 ) particles to butanone may be 1/40.
  • the modified thermally conductive filler 200 is alumina (referred to as Al 2 O 3 -g-EP) graft-coated with tetramethyl biphenyl epoxy resin.
  • S202 is performed to fabricate the thermally conductive material precursor 41 .
  • thermally conductive material precursor 41 For example, an appropriate amount of organic solvent butanone, bisphenol A epoxy resin as matrix polymer 40, phenolic resin curing agent and modified thermally conductive filler 200 (Al 2 O 3 -g-EP), mechanically stirring for 1 hour to dissolve and disperse, then add an appropriate amount of curing accelerator 2 methylimidazole (2MZ) and continue stirring for 1 hour to obtain thermally conductive material precursor 41.
  • organic solvent butanone bisphenol A epoxy resin as matrix polymer 40
  • phenolic resin curing agent and modified thermally conductive filler 200 Al 2 O 3 -g-EP
  • the above-mentioned S102 may be performed to fabricate a thermally conductive material.
  • the above-mentioned thermally conductive material precursor 41 is poured into a film-forming mold, vacuum defoamed and cured and molded to prepare a high thermal conductivity epoxy resin matrix filled with tetramethylbiphenyl epoxy resin grafted and coated with alumina Thermally conductive material.
  • the thermally conductive material can be used as the thermally conductive block for preparing the thermal interface material 10 , the underfill material 13 , the plastic sealing compound 14 , the plastic cover 15 and the thermally conductive adhesive 16 .
  • prepreg 18 and CCL 19 are prepared.
  • epoxy resin epoxy resin, phenolic resin curing agent, the above-mentioned modified thermal conductive filler 200 (Al 2 O 3 -g-EP), curing accelerator 2-methylimidazole (2MZ), additives, etc. are prepared according to the formula in Table 1, and then Mix butanone and xylene according to a volume ratio of 2:1 as a solvent to dissolve, adjust the solid content of the resin composition to 65%, and stir uniformly at room temperature with mechanical stirring to prepare a prepreg.
  • Al 2 O 3 -g-EP modified thermal conductive filler 200
  • 2MZ 2-methylimidazole
  • the prepreg was coated on E-type glass cloth (specification 2116, single weight 104 g/m 2 ), and baked in a 170° C. oven for 10 minutes to prepare a prepreg 18 with a resin content of 80%. Then, a copper foil was placed on the upper and lower surfaces of the prepared prepreg 18 with a resin content of 80%, placed in a vacuum hot press at a pressure of 2MPa and a temperature of 200°C, and pressed to obtain CCL19. In this case, the thermal conductivity of the dielectric layer (formed by curing the prepreg 18 ) in the prepared CCL19 is shown in Table 1.
  • Test Item 1 is a thermally conductive material filled with modified thermally conductive filler 200 (Al 2 O 3 -g-EP) as an example.
  • the resin content in CCL19 prepared by the formula of test item 1 can be 40 parts (32+8).
  • the resin content of CCL19 prepared with the formula of test item 2 can be 50 parts (40+10).
  • the resin content of CCL19 prepared with the formula of test item 3 can be 60 parts (48+12).
  • the resin content of test item 2 and test item 3 is relatively high, and the content of modified thermally conductive filler 200 (Al 2 O 3 -g-EP) is relatively low. Therefore, the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared by the formula of test item 2 and test item 3 is relatively low, which are 0.65W/mk and 0.58W/mk respectively.
  • the resin content of test item 1 is the lowest, so the content of modified thermal conductive filler 200 (Al 2 O 3 -g-EP) is the highest, so the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared with the formula of test item 1 is the highest, for example is 0.83W/mk.
  • both the comparative item 1 and the comparative item 2 are described as an example of preparing CCL19 by using a thermally conductive material filled with an original thermally conductive filler (Al 2 O 3 ) that is not modified with a liquid crystal polymer.
  • the fractions of fillers with different particle sizes are the same, and the fractions of filler particles with particle sizes (D50) of 10um, 6um, 3um and 0.2um are 24 and 18 respectively. , 12 and 6.
  • test item 1 is to prepare CCL19 with a thermally conductive material filled with modified thermal conductive filler 200 (Al 2 O 3 -g-EP), test item 1 is used to prepare the dielectric thermal conductivity of the dielectric layer in CCL19 (0.83W/mk). Higher than that, the dielectric thermal conductivity (0.61W/mk) of the dielectric layer in the CCL19 was prepared using the comparative item 1.
  • test item 3 is to prepare CCL19 with a thermally conductive material filled with modified thermal conductive filler 200 (Al 2 O 3 -g-EP), test item 3 is used to prepare the dielectric thermal conductivity of the dielectric layer in CCL19 (0.58W/mk) Higher than that, the dielectric thermal conductivity (0.42W/mk) of the dielectric layer in the CCL19 was prepared using the comparative item 1.
  • the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared by using the thermally conductive material filled with the modified thermally conductive filler 200 (Al 2 O 3 -g-EP) provided in the examples of this application is higher than that without the liquid crystal polymer modification.
  • the thermal conductivity of the original thermal conductive filler (Al 2 O 3 ) filled thermal conductive material prepared the dielectric thermal conductivity of the dielectric layer in CCL19.
  • the dielectric thermal conductivity of the dielectric layer in the finally obtained CCL19 is beneficial to improve the electronic equipment with the CCL19. heat dissipation capacity.
  • the same part as the first embodiment is that the material of the thermally conductive filler 30 is aluminum oxide (Al 2 O 3 ), and the material of the liquid crystal polymer 22 is tetramethyl biphenyl epoxy resin (the thermal conductivity is 0.27W). /mk), the material of the matrix polymer 40 is bisphenol A epoxy resin.
  • the manufacturing method of the thermally conductive material precursor 41 may include the above-mentioned S211, S201 and S202.
  • the methods of S211 , S201 , S202 , S102 , and the prepreg 18 and CCL19 are illustrated below with reference to the specific materials of the thermally conductive filler 30 , the liquid crystal polymer 22 and the matrix polymer 40 .
  • the above-mentioned S211 is performed, and the thermally conductive filler 30 is treated with a coupling agent.
  • alumina (Al 2 O 3 ) particles as the thermally conductive filler 30 and silane coupling agent (KH550) are added to a mixed solution of ethanol and deionized water (wherein, the mass ratio of ethanol and deionized water is 90/10) , ultrasonic dispersion for 30min.
  • the hydrogen ion concentration index (pH value) of the solution was adjusted to 5-6 with sulfuric acid in advance. Then, under the protection of nitrogen, the reaction was heated under reflux with magnetic stirring for 5 h.
  • the coupling agent-treated alumina (Al 2 O 3 -KH550) obtained after performing the above S211 is added to the organic solvent butanone, so that the mass ratio of Al 2 O 3 particles to butanone is 1/40, and the Mix and ultrasonically disperse in a three-necked flask for 30 min. Then, under magnetic stirring and nitrogen protection, tetramethylbiphenyl epoxy resin as liquid crystal polymer 22 was added, an appropriate amount of 2methylimidazole (2MZ) was added as an initiator, and the reaction was heated and refluxed at 100 °C for 8 h. Next, it is filtered, washed with butanone, dried and pulverized to obtain the above modified thermally conductive filler 200 .
  • the modified thermally conductive filler 200 is alumina (referred to as Al 2 O 3 -g-EP) graft-coated with tetramethyl biphenyl epoxy resin.
  • test item 1, test item 2, and test item 3 in Table 2 are to replace the thermally conductive filler in the first embodiment with the second embodiment.
  • the other components of the modified thermally conductive filler 200 obtained by chemical modification treatment are the same as the formulations (or components) of Test Item 1, Test Item 2, and Test Item 3 in Table 1, so they are not reflected in Table 2.
  • the alumina (Al 2 O 3 ) particles serving as the thermally conductive filler 30 are treated with a coupling agent.
  • the coupling agent can improve the interface bonding strength and graft density between the thermally conductive filler 30 and the liquid crystal polymer 22, thereby improving the thermal conductivity of the thermally conductive material.
  • the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared by the formula of Test Item 1, Test Item 2, and Test Item 3 (respectively 0.97W/mk, 0.79W /mk, 0.68W/mk), respectively higher than the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared by the formula of test item 1, test item 2, and test item 3 in Embodiment 1 (respectively 0.83W/mk, 0.65 W/mk, 0.58W/mk).
  • the difference from the first embodiment is that the material of the liquid crystal polymer 22 is a multi-liquid crystal cell epoxy resin (the thermal conductivity is 0.5W/mk).
  • the above-mentioned multi-liquid crystal cell epoxy resin means that there are two or more liquid crystal cells 20 in an epoxy resin monomer.
  • the liquid crystal cell 20 may have the above-mentioned biphenyl structure, aryl ester structure, ⁇ -methylstyrene structure, azo structure, methyleneamine structure, binaphthyl structure, triphenylene structure, and the like.
  • the plurality of liquid crystal cells 20 in the monomer of the multi-liquid crystal cell epoxy resin may be the same or different, which is not limited in the present application.
  • the epoxy resins with multiple liquid crystal cells in the following embodiments all have two liquid crystal cells 20 in a monomer, and the two liquid crystal cells 20 are both of biphenyl structure.
  • the arrangement of other multi-liquid crystal units 20 will not be repeated here.
  • the material of the thermally conductive filler 30 is aluminum oxide (Al 2 O 3 ), and the material of the matrix polymer 40 is bisphenol A epoxy resin.
  • the manufacturing method of the thermally conductive material precursor 41 may include the above-mentioned S201 and S202. The methods of S201 , S202 , S102 , and the prepreg 18 and CCL19 are illustrated below with reference to the specific materials of the thermally conductive filler 30 , the liquid crystal polymer 22 and the matrix polymer 40 .
  • the above-mentioned S201 is performed to manufacture the modified thermally conductive filler 200 .
  • the material of the thermally conductive filler 30 is Al 2 O 3 particles, and the multi-liquid crystal cell epoxy resin as the liquid crystal polymer 22 is added to the organic solvent butanone.
  • the mass ratio of alumina (Al 2 O 3 ) particles to butanone may be 1/40.
  • Embodiment 1 mix and ultrasonically disperse in a three-necked flask for 1 hour, and then add tetrabutylammonium bromide (relative to tetramethylbiphenyl ring) as a catalyst under magnetic stirring and nitrogen protection.
  • the mass ratio of oxygen resin is 2 wt %), and the reaction is heated and refluxed at 100° C. for 12 h.
  • it is filtered, washed with butanone, dried and pulverized to obtain the modified thermally conductive filler 200 described above.
  • the modified thermally conductive filler 200 is alumina (denoted as Al 2 O 3 -g-EP) grafted and coated with epoxy resin with multiple liquid crystal cells.
  • test item 1, test item 2, and test item 3 are to replace the liquid crystal polymer 22 in the first embodiment from tetramethyl biphenyl epoxy resin with the polycrystalline liquid crystal in the third embodiment.
  • Unit epoxy resin, other components are the same as the formulas (or components) of Test Item 1, Test Item 2, and Test Item 3 in Table 1, so they are not listed in Table 3.
  • thermo conductivity of 0.5W/mk thermo conductivity of 0.5W/mk
  • the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared with the formula of Test Item 1, Test Item 2, and Test Item 3 (respectively 1.23W/mk, 0.97W /mk, 0.83W/mk), which are respectively higher than the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared with the formula of test item 1, test item 2, and test item 3 in Embodiment 1 (respectively 0.83W/mk, 0.65 W/mk, 0.58W/mk).
  • a coupling agent is used to process the thermally conductive filler 30 before the production of the 200
  • the test item 1, the test item 2, and the test item are used.
  • the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared by the formula 3 (respectively 1.23W/mk, 0.97W/mk, 0.83W/mk) is slightly higher than that in the second embodiment, using test item 1, test item 2, test The dielectric thermal conductivity of the dielectric layer in the CCL19 prepared by the formula of item 3 (0.97W/mk, 0.79W/mk, 0.68W/mk, respectively).
  • the difference from the first embodiment is that the material of the liquid crystal polymer 22 is multi-liquid crystal cell epoxy resin (thermal conductivity is 0.5W/mk), and the material of the thermal conductive filler 30 is aluminum nitride (AlN ).
  • the material of the matrix polymer 40 is bisphenol A epoxy resin.
  • the manufacturing method of the thermally conductive material precursor 41 may include the above-mentioned S201 and S202. The methods of S201 , S202 , S102 , and the prepreg 18 and CCL19 are illustrated below with reference to the specific materials of the thermally conductive filler 30 , the liquid crystal polymer 22 and the matrix polymer 40 .
  • the above-mentioned S201 is performed to manufacture the modified thermally conductive filler 200 .
  • the material of the thermally conductive filler 30 is aluminum nitride (AlN) and the multi - liquid crystal cell epoxy resin as the liquid crystal polymer 22 is added to the organic solvent butanone.
  • AlN aluminum nitride
  • the ratio can be 1/40.
  • Embodiment 1 mix and ultrasonically disperse in a three-necked flask for 1 hour, and then add tetrabutylammonium bromide (relative to tetramethylbiphenyl ring) as a catalyst under magnetic stirring and nitrogen protection.
  • the mass ratio of oxygen resin is 2 wt %), and the reaction is heated and refluxed at 100° C. for 12 h.
  • it is filtered, washed with butanone, dried and pulverized to obtain the modified thermally conductive filler 200 described above.
  • the modified thermally conductive filler 200 is aluminum nitride (referred to as AlN-g-EP) grafted and coated with epoxy resin with multiple liquid crystal cells.
  • S202 may be performed to manufacture the thermally conductive material precursor 41, and the above-mentioned S102 may be performed to manufacture the thermally conductive material.
  • the manufacturing process is the same as that of the first embodiment, and will not be repeated here.
  • prepreg 18 and CCL 19 are prepared.
  • bisphenol A epoxy resin, phenolic resin curing agent, the above-mentioned modified thermal conductive filler 200 (AlN-g-EP), curing accelerator 2 methylimidazole (2MZ), additives, etc. are prepared according to the formula in Table 4, Then, methyl ethyl ketone and xylene are mixed in a volume ratio of 2:1 as a solvent to dissolve, and the solid content of the resin composition is adjusted to 75%.
  • the composition prepreg was coated on E-type glass cloth (specification 2116, single weight 104g/m 2 ), and the resin was prepared after baking in an oven at 170°C for 10 minutes Prepreg 18 with 80% content. Then, a copper foil was placed on the upper and lower surfaces of the prepared prepreg 18 with a resin content of 80%, placed in a vacuum hot press at a pressure of 2MPa and a temperature of 200°C, and pressed to obtain CCL19. In this case, the thermal conductivity of the dielectric layer (formed after curing of the prepreg 18 ) in the prepared CCL 19 is shown in Table 4.
  • Test Item 1, Test Item 2, and Test Item 3 are all prepared by using a thermally conductive material filled with modified thermally conductive filler 200 (Al 2 O 3 -g-EP) to prepare CCL19 as an example. illustrate.
  • the resin content in CCL19 prepared with the formula of test item 1, the resin content in CCL19 prepared with the formula of test item 2, and the resin content in CCL19 prepared with the formula of test item 3 are all different.
  • both the comparative item 1 and the comparative item 2 are used to illustrate the preparation of CCL19 by using a thermally conductive material filled with an original thermally conductive filler (AlN-) not modified with a liquid crystal polymer as an example.
  • AlN- original thermally conductive filler
  • Comparative Item 1 and Test Item 1 the fractions of fillers with different particle sizes are the same.
  • comparison item 2 and test item 3 the fractions of fillers with different particle sizes are the same.
  • the dielectric thermal conductivity (1.63W/mk) of the dielectric layer in the CCL19 prepared by the test item 1 is higher than that of the dielectric layer in the CCL19 prepared by the comparative item 1 (1.03W/mk).
  • the dielectric thermal conductivity (1.05W/mk) of the dielectric layer in CCL19 prepared by test item 3 is higher than that of the dielectric layer in CCL19 prepared by comparison item 2 (0.63W/mk).
  • thermo conductivity of the thermally conductive material obtained by filling the polymer matrix with the above-mentioned modified thermally conductive filler 200 is higher.
  • the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared by the formulas of Test Item 1, Test Item 2, Test Item 3, Comparative Item 1 and Comparative Item 2 (respectively are 1.63W/mk, 1.42W/mk, 1.05W/mk, 1.03W/mk, 0.63W/mk), which are respectively higher than those in the first embodiment, using test item 1, test item 2, test item 3, and comparison item
  • the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared by the formulations of Item 1 and Comparative Item 2 (respectively 0.83W/mk, 0.65W/m ⁇ k, 0.58W/mk, 0.61W/mk, 0.42W/mk).
  • thermosetting material with better affinity with the thermally conductive filler 30 Liquid crystal polymer 22. Therefore, the liquid crystal polymer 22 can in-situ coat the surface of the thermally conductive network structure constructed by the plurality of thermally conductive fillers 30 in the base polymer 40 to form the thermally conductive material provided in the embodiment of the present application, which may be referred to as liquid crystal polymer.
  • the manufacturing method of the thermally conductive material may include the above-mentioned S101 and S102.
  • S101 is performed. Specifically, it may include: adding the thermally conductive filler 30 and the liquid crystal polymer 22 into the organic solvent, and stirring to dissolve and disperse, for example, mechanical stirring for 0.5-2 hours. After stirring, the matrix polymer 40, curing agent and curing accelerator are added, and the stirring is continued for dissolution and dispersion, for example, mechanical stirring is continued for 0.5-2 h to obtain the thermally conductive material precursor 41 as shown in FIG. 10 .
  • the inorganic thermally conductive filler 30 is in different polymers and has different interactions with the polymers. If the interaction between the thermally conductive filler 30 and the polymer is strong, the affinity of the thermally conductive filler 30 with the polymer is good, or the wettability is better. In the second example, the affinity between the liquid crystal polymer 22 and the thermally conductive filler 30 is greater than the affinity between the matrix polymer 40 and the thermally conductive filler 30 . In this way, when the thermally conductive filler 30 is dispersed in the blend composed of the liquid crystal polymer 22 and the matrix polymer 40, the thermally conductive filler 30 will be selectively distributed in the polymer component with stronger affinity, such as liquid crystal polymer item 22.
  • the matrix polymer 40 may include: polyphenylene ether, hydrocarbon resin, At least one of epoxy resin, cyanate ester, bismaleimide resin, silicone resin, polyimide and the like.
  • the above-mentioned materials of the thermally conductive filler 30 and the liquid crystal polymer 22 are the same as those of the first example, and will not be repeated here.
  • the weight ratio of the liquid crystal polymer 22 may account for 3-30 wt %, eg, 5-10 wt %, of the total amount of polymers in the thermally conductive material, so as to improve the thermal conductivity of the thermally conductive material.
  • the total amount of polymers in the thermally conductive material includes the sum of the weights of the liquid crystal polymer 22, the matrix polymer 40, and the above-mentioned curing agent and curing accelerator.
  • the thermally conductive filler 30 and the thermosetting liquid crystal polymer 22 have better affinity, the liquid crystal polymer 22 It can be adsorbed on the surface of the thermally conductive filler 30 by thermodynamic action. On this basis, since the liquid crystal polymer 22 tends to aggregate into a phase, it can drive the thermally conductive filler 30 to self-aggregate to form a thermally conductive network structure by stacking. In addition, the surface of the thermally conductive network structure constructed by the thermally conductive filler 30 is coated with a layer of liquid crystal polymer 22 with high thermal conductivity ( ⁇ 0.25W/mk) to form a network chain structure 301 .
  • the second embodiment provides a thermally conductive material including thermally conductive filler 30 , liquid crystal polymer 22 , curing agent and matrix polymer 40 .
  • the thermally conductive filler 30 is filled in the matrix polymer 40 , and at least a part of the surface of the thermally conductive filler 30 is coated with the liquid crystal polymer 22 .
  • a chemical bond is formed between the liquid crystal polymer 22 and the matrix polymer 40 through a curing agent.
  • the thermally conductive filler 30 is covered with the liquid crystal polymer 22 means that the surface of the thermally conductive filler 30 can be completely covered by the liquid crystal polymer 22 .
  • the liquid crystal polymer 22 may cover only a part of the surface of the thermally conductive filler 30 , and the portion of the thermally conductive filler 30 not covered by the liquid crystal polymer 22 may be in contact with another thermally conductive filler 30 , or may also be in contact with the matrix polymer 40 touch.
  • the affinity between the liquid crystal polymer 22 and the thermally conductive filler 30 is greater than the affinity between the matrix polymer 40 and the thermally conductive filler 30 .
  • a thermally conductive network structure is formed by the accumulation of a plurality of thermally conductive fillers 30 in the matrix polymer 40 .
  • the surface of the thermally conductive network structure is covered with liquid crystal polymer 22 to form a network chain structure 301 .
  • the thermally conductive network structure formed by the stacking of a plurality of thermally conductive fillers 30 the molecular chains of the in-situ coated liquid crystal polymer 22 are regularly stacked along a certain crystal plane direction of the filler particles.
  • the thermally conductive filler 30 and the liquid crystal polymer 22 are connected by intermolecular forces and partial chemical bonds, i.e., covalent bonds.
  • a covalent bond is formed between the liquid crystal polymer 22 and the matrix polymer 40 through a curing agent.
  • the thermally conductive material precursor 41 may include a three-dimensional through thermally conductive network chain constructed by the above-mentioned thermally conductive filler 30 and the liquid crystal polymer 22 (eg, liquid crystal epoxy resin) coated in situ on the surface of the filler network. .
  • the liquid crystal polymers 22 in the above-mentioned network chain structure are connected by covalent bonds through a curing agent. In this way, it is beneficial to effectively reduce the interface thermal resistance between the filler and the polymer matrix, so that heat can be transmitted in the form of phonons in the thermal conductive network structure 201 through the vibration of the crystal lattice.
  • the above-mentioned mesh chain structure 301 can form a dense thermal conduction path (the transmission path indicated by the arrow in FIG. 10 ), which is beneficial to the efficient transmission of heat.
  • the liquid crystal polymer 22 has a high thermal conductivity, for example, the thermal conductivity can be greater than or equal to 0.25W/mk, which is higher than that of the amorphous polymer, thereby helping to improve the thermal conductivity of the final thermally conductive material.
  • the method of using the liquid crystal polymer 22 to coat the surface of the thermally conductive filler 30 in situ improves the thermal conductivity of the thermally conductive material.
  • the preparation method is simpler, the yield is high, the effect is obvious, and it is more suitable for industrial production.
  • the particle size of the thermally conductive filler 30 in the thermally conductive material is not limited.
  • FIG. 10 is an example for illustrating that the particle size of the thermally conductive filler is the same.
  • the particle sizes of at least two thermally conductive fillers 30 in the thermally conductive material may be different, and the technical effects are the same as those described above, which will not be repeated here.
  • step S102 is performed, and a thermally conductive material is produced by using the thermally conductive material precursor 41 .
  • the thermally conductive material precursor 41 may be poured into a mold, and subjected to vacuum defoaming and curing or semi-curing treatment to obtain a thermally conductive material.
  • the thermally conductive material can be used as the thermally conductive block for preparing the thermal interface material 10 , the underfill material 13 , the plastic sealing compound 14 , the plastic cover 15 and the thermally conductive adhesive 16 .
  • the thermally conductive material precursor is mixed with an organic solvent, and the thermally conductive material is obtained by adjusting the solid content of the solution.
  • the prepreg for preparing the prepreg 18 is obtained by mixing the thermally conductive material precursor 41 with an organic solvent and adjusting the solid content of the solution.
  • the methods of the prepreg 18 and the CCL 19 are the same as described above, and will not be repeated here.
  • the material of the thermally conductive filler 30 is at least one of alumina (Al 2 O 3 ) and boron nitride (BN), and the material of the liquid crystal polymer 22 is tetramethyl biphenyl epoxy resin (thermally conductive The coefficient is 0.27 W/mk), and the material of the matrix polymer 40 is polyphenylene ether.
  • the manufacturing method of the thermally conductive material precursor 41 may include the above-mentioned S201 and S202.
  • S101 is performed to obtain the thermally conductive material precursor 41 having the mesh chain structure 301 shown in FIG. 10 .
  • organic solvent butanone and xylene
  • thermally conductive filler 30 at least one of Al 2 O 3 and BN
  • tetramethyl biphenyl epoxy as the liquid crystal polymer 22 are sequentially added to the glue bottle.
  • epoxy resin curing agent 4,4'-diaminodiphenylmethane (DDM) and curing accelerator 2MZ mechanically stirring for 1 hour.
  • polyphenylene ether as the base polymer 40 as well as the curing agent triallyl isocyanate (TAIC) and the catalyst dicumyl peroxide (DCP) were added, and the mechanical stirring was continued for 2h to completely dissolve and disperse, and then the resin composition was prepared.
  • the glue is used as the aforementioned thermally conductive material precursor 41 .
  • the ratio of each composition is shown in Table 5.
  • the above-mentioned S102 may be performed to manufacture the thermally conductive material, and the preparation process of the thermally conductive material is the same as that of the first embodiment in Example 1, and details are not repeated here.
  • prepreg 18 and CCL 19 are prepared.
  • the thermally conductive material precursor 41 obtained by performing S101 is formulated into a uniform prepreg with a solid content of 75%.
  • the prepreg was coated on E-type glass cloth (specification 2116, single weight 104 g/m 2 ), and baked in a 170° C. oven for 10 minutes to prepare a prepreg 18 with a resin content of 80%.
  • a copper foil was placed on the upper and lower surfaces of the prepared prepreg 18 with a resin content of 80%, placed in a vacuum hot press at a pressure of 2MPa and a temperature of 200°C, and pressed to obtain CCL19.
  • the thermal conductivity of the dielectric layer (formed after curing of the prepreg 18 ) in the prepared CCL19 is shown in Table 5.
  • Test Item 1, Test Item 2, and Test Item 3 are all described as an example of preparing CCL19 using a thermally conductive material added with liquid crystal polymer 22 (tetramethyl biphenyl epoxy resin). It can be seen from Table 5 that the difference between Test Item 1, Test Item 2, and Test Item 3 is that the material of the thermally conductive filler 30 added is different.
  • the thermal conductive filler 30 of test item 1 is alumina (Al 2 O 3 ), and the dielectric thermal conductivity of the dielectric layer in the prepared CCL19 is the lowest, which is 1.42 W/mk.
  • the thermal conductive filler 30 of test item 2 is boron nitride (BN) with high thermal conductivity, and the dielectric thermal conductivity of the dielectric layer in the prepared CCL19 is the highest, which is 1.97W/mk.
  • the thermal conductive filler 30 of test item 3 is aluminum oxide (Al 2 O 3 ) and boron nitride (BN).
  • the value of the dielectric thermal conductivity of the dielectric layer in the prepared CCL19 is located in the middle of the above two test items, for example, 1.73W/ mk.
  • the comparative item 1, the comparative item 2 and the comparative item 3 are all descriptions of preparing CCL19 by using the thermally conductive material without adding the liquid crystal polymer 22 as an example.
  • the fractions of fillers with different particle sizes are the same.
  • test item 1 is to prepare CCL19 with a thermally conductive material added with liquid crystal polymer 22, the dielectric thermal conductivity (1.42W/mk) of the dielectric layer in CCL19 prepared with test item 1 is higher than that in CCL19 prepared with comparison item 1.
  • the dielectric thermal conductivity of the dielectric layer (0.93W/mk).
  • the fractions of fillers with different particle sizes are the same.
  • the dielectric thermal conductivity (1.97W/mk) of the dielectric layer in the CCL19 prepared by the test item 2 is higher than that of the dielectric layer in the CCL19 prepared by the comparative item 2 (1.35W/mk).
  • the fractions of fillers with different particle sizes are the same.
  • the dielectric thermal conductivity (1.73W/mk) of the dielectric layer in the CCL19 prepared by the test item 3 is higher than that of the dielectric layer in the CCL19 prepared by the comparative item 3 (1.13W/mk).
  • the dielectric thermal conductivity of the dielectric layer in CCL19 prepared with the thermally conductive material added with liquid crystal polymer 22 is higher than that of the dielectric layer in CCL19 prepared with the thermal conductive material without liquid crystal polymer 22 added.
  • the difference from Embodiment 5 is that the material of the liquid crystal polymer 22 is a multi-liquid crystal cell epoxy resin (the thermal conductivity is 0.5 W/mk).
  • the material of the thermally conductive filler 30 may be at least one of alumina (Al 2 O 3 ) and boron nitride (BN), and the material of the matrix polymer 40 is polyphenylene ether.
  • the manufacturing method of the thermally conductive material precursor 41 may include the above-mentioned S201 and S202.
  • the above-mentioned methods of S101 , S102 , and the prepreg 18 and CCL19 will be illustrated by way of example.
  • S101 is performed to obtain the thermally conductive material precursor 41 having the mesh chain structure 301 shown in FIG. 10 .
  • organic solvent butanone and xylene
  • thermally conductive filler 30 at least one of Al 2 O 3 and BN
  • multi-liquid crystal cell epoxy resin as liquid crystal polymer 22
  • Epoxy resin curing agent 4,4'-diaminodiphenylmethane (DDM) and curing accelerator 2MZ mechanically stirred for 1 hour.
  • polyphenylene ether as the base polymer 40 as well as the curing agent triallyl isocyanate (TAIC) and the catalyst dicumyl peroxide (DCP) were added, and the mechanical stirring was continued for 2h to completely dissolve and disperse, and then the resin composition was prepared.
  • the glue is used as the aforementioned thermally conductive material precursor 41 .
  • the ratio of each composition is shown in Table 6.
  • the above-mentioned S102 is performed to manufacture the thermally conductive material, or the manufacturing process of the prepreg 18 and the CCL19 by using the thermally conductive material precursor 41 prepared in S101 is the same as that of the fifth embodiment, and will not be repeated here.
  • the thermal conductivity of the dielectric layer in the prepared CCL19 is shown in Table 6.
  • test item 1, test item 2, and test item 3 are the liquid crystal polymer 22 in the fifth embodiment replaced by tetramethyl biphenyl epoxy resin with the polycrystalline liquid crystal in the sixth embodiment.
  • Unit epoxy resin, other components are the same as the formulas (or components) of Test Item 1, Test Item 2, and Test Item 3 in Table 5, so they are not reflected in Table 6.
  • the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared by the formula of Test Item 1, Test Item 2, and Test Item 3 (respectively 1.67W/mk, 2.32W /mk, 1.85W/mk), which are respectively higher than those of the fifth embodiment, the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared by the formula of test item 1, test item 2, and test item 3 (respectively 1.42W/mk, 1.97 W/mk, 1.73W/mk).
  • the difference from Embodiment 5 is that the material of the matrix polymer 40 is polybutadiene (hydrocarbon resin).
  • the material of the liquid crystal polymer 22 is tetramethyl biphenyl epoxy resin (the thermal conductivity is 0.27 W/mk).
  • the material of the thermally conductive filler 30 may be at least one of alumina (Al 2 O 3 ) and boron nitride (BN).
  • the manufacturing method of the thermally conductive material precursor 41 may include the above-mentioned S201 and S202.
  • S101 is performed to obtain the thermally conductive material precursor 41 having the mesh chain structure 301 shown in FIG. 10 .
  • organic solvent butanone and xylene
  • thermally conductive filler 30 at least one of Al 2 O 3 and BN
  • tetramethyl biphenyl epoxy as the liquid crystal polymer 22 are sequentially added to the glue bottle.
  • DDM epoxy resin curing agent 4,4'-diaminodiphenylmethane
  • 2MZ curing accelerator
  • polybutadiene (hydrocarbon resin) as matrix polymer 40 as well as curing agent triallyl isocyanate (TAIC) and catalyst dicumyl peroxide (DCP) were added, and mechanical stirring was continued for 2h to completely dissolve and disperse , and configured into a resin composition glue solution as the above-mentioned thermally conductive material precursor 41 .
  • TAIC curing agent triallyl isocyanate
  • DCP catalyst dicumyl peroxide
  • the above-mentioned S102 is performed to manufacture the thermally conductive material, or the manufacturing process of the prepreg 18 and the CCL19 by using the thermally conductive material precursor 41 prepared in S101 is the same as that of the fifth embodiment, and will not be repeated here.
  • the thermal conductivity of the dielectric layer in the prepared CCL19 is shown in Table 7.
  • the medium of the dielectric layer in the CCL19 prepared by the formula of test item 1, test item 2, and test item 3 is used.
  • Thermal conductivity (1.53W/mk, 2.12W/mk, 1.84W/mk respectively).
  • the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared using the formulations of comparative item 1, comparative item 2 and comparative item 3 (respectively 1.01W/mk, 1.41W/mk, 1.25W/mk).
  • thermo conductivity of 0.5W/mk thermo conductivity of 0.5W/mk
  • the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared by the formula of Test Item 1, Test Item 2, and Test Item 3 (respectively 1.53W/mk, 2.12W /mk, 1.84W/mk), respectively slightly lower than the dielectric thermal conductivity of the dielectric layer in the CCL19 prepared with the formula of test item 1, test item 2, and test item 3 in the sixth embodiment (respectively 1.67W/mk, 2.32W/mk, 1.85W/mk).

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Abstract

本申请实施例提供一种导热材料及其制作方法、半固化片、层压板、电路板，涉及纳米材料技术领域，用于提供具有较高导热性能的导热材料。导热材料包括基体聚合物、固化剂以及改性导热填料。改性导热填料包括导热填料以及接枝包覆于导热填料表面的液晶聚合物。液晶聚合物用于对导热填料进行改性。改性导热填料中，液晶聚合物与基体聚合物之间通过固化剂形成化学键连接。或者，导热材料包括基体聚合物、液晶聚合物、固化剂以及导热填料。导热填料填充于基体聚合物内，导热填料表面的至少一部分包覆有液晶聚合物。液晶聚合物与基体聚合物之间通过固化剂形成化学键连接，该液晶聚合物与导热填料的亲和性，大于基体聚合物与导热填料的亲和性。

Description

一种导热材料及其制作方法、半固化片、层压板、电路板
本申请要求于2021年03月31日提交国家知识产权局、申请号为202110352474.2、申请名称为“一种导热材料及其制作方法、半固化片、层压板、电路板”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及纳米材料技术领域，尤其涉及一种导热材料及其制作方法、半固化片、层压板、电路板。
背景技术
随着电子技术的发展，为了降低电子器件内部的热量，可以将一些导热系数较高的无机导热材料添加到聚合物中，形成导热材料。将上述导热材料应用至电子器件中以达到降低其内部热量的目的。然而，随着微电子与组装技术的飞速发展，电子器件越来越集成化、小型化，而且功率密度大幅提升，电子器件在运行过程中产生的热量急剧增加。这样一来，目前的导热材料的导热性能难以满足使用需求，导致热量无法及时耗散并持续堆积，严重影响了设备的安全工作条件和使用性能。
发明内容
本申请实施例提供一种导热材料及其制作方法、半固化片、层压板、电路板，用于提供具有较高导热性能的导热材料。
为达到上述目的，本申请采用如下技术方案：
在本申请的一些实施例中，提供一种导热材料。该导热材料包括基体聚合物、固化剂以及改性导热填料。该改性导热填料包括导热填料以及接枝包覆于该导热填料表面的液晶聚合物。该改性导热填料中，液晶聚合物与基体聚合物之间通过固化剂形成化学键连接。这样一来，通过在导热填料的表面均接枝包覆有液晶聚合物，可以使得导热填料与液晶聚合物之间通过较强的共价键连接，使得导热填料与液晶聚合物之间结合得更加紧密，提高了导热填料与聚合物基体间的界面结合力，可以消除导热填料与聚合物基体间的空气热阻，更有利于降低导热填料与聚合物基体之间的界面热阻。另一方面，该液晶聚合物为大分子液晶，内部有规整的液晶单元，因此液晶聚合物能够沿着导热填料粒子在特定的晶面方向上形成规整的堆积结构。该规整结构有利于声子传输，从而有效减小导热填料与聚合物基体界面处的声子色散，有利于降低导热填料与聚合物基体之间的界面热阻。又一方面，热固性液晶聚合物自身具有较高的导热系数，例如导热系数可以大于或等于0.25W/mk，其导热系数高于无定型聚合物，从而有利于提高最终得到的导热材料的导热效率。
可选的，液晶聚合物包括液晶环氧树脂。其中，液晶环氧树脂包括联苯型液晶环氧树脂、芳酯型液晶环氧树脂、α-甲基苯乙烯型液晶环氧树脂、偶氮型液晶环氧树脂、亚甲胺型液晶环氧树脂、萘型液晶环氧树脂、苯并菲型液晶环氧树脂中的至少一种。上述液晶聚合物具有较高的导热系数，导热系数可以大于或等于0.25W/mk。
可选的，液晶聚合物包括可发生交联反应的功能基团，功能基团包括环氧基、烯基、炔基、氰酸酯基、异氰酸酯基、苯并环丁烯基中的至少一种。液晶聚合物包括规整的液晶单元，液晶单元包括联苯结构、芳酯结构、α-甲基苯乙烯结构、偶氮结构、亚甲胺结构、联萘结构、苯并菲结构中的至少一种。液晶聚合物的功能基团可以与导热填料表面的功能基团发生交联反应，形成化学键，例如共价键。从而进一步提高导热填料与液晶聚合物间的界面结合强度，有利于消除界面缝隙带来的空气热阻，从而能够提高导热材料的导热系数。
可选的，导热填料包括纳米级或微米级无机导热材料。构成无机导热材料包括二氧化硅、氧化铝、氮化铝、氮化硼、碳化硅、金刚石中的至少一种。其中，二氧化硅和氧化铝的导热系数相对较低，但是容易获得且成本较低。氮化铝、氮化硼、碳化硅的导热系数相对较高。
可选的，多个改性导热填料堆积形成导热网络结构，且相接触的多个改性导热填料的液晶聚合物通过与固化剂形成化学键连接。当基体聚合物中导热填料填充量较高时，多个改性导热填料可以堆积形成致密的导热网络结构，且相接触的多个改性导热填料的液晶聚合物通过化学键连接。这样一来，可以使得热量以声子的形式在导热网络结构中，通过晶格的振动进行传输，从而进一步提高最终得到的导热材料的导热效率。
可选的，导热材料中至少两个导热填料的粒径不同。这样一来，具有较大粒径的导热填料之间形成的空隙中，可以嵌入粒径较小的导热填料，从而能够进一步提高多个改性导热填料堆积形成的导热网络结构的致密性，有利于进一步提高得到的导热材料的导热效率。
本申请实施例的另一方面，提供一种用于制作如上所述的任意一种导热材料的方法。上述方法包括：首先，将导热填料分散于具有液晶聚合物的溶液中，得到导热填料分散液。然后，对导热填料分散液进行加热回流反应、过滤、洗涤、干燥后，进行研磨处理得到改性导热填料。改性导热填料中的导热填料表面均接枝包覆有液晶聚合物。然后，将改性导热填料分散于具有基体聚合物的溶液中，得到导热材料前体。然后，将导热材料前体倒入模具中，进行真空脱泡以及固化或半固化处理，得到导热材料，或者，将导热材料前体与有机溶剂混合，并通过调节溶液固含量得到预浸渍料，将预浸渍料涂布于基材上，并烘烤后形成包覆基材的导热材料。该导热材料的制作方法具有与前述实施例提供的导热材料相同的技术效果，此处不再赘述。
可选的，将导热填料分散于具有液晶聚合物的溶液中之前，方法还包括：首先，将导热填料加入具有偶联剂的溶液中，进行偶联剂处理。然后，将经过偶联剂处理后的溶液进行过滤、洗涤并干燥。通过偶联剂对导热填料的表面进行处理，可以根据不同的硅烷偶联剂，在导热填料的表面引入不同的功能基团。引入的功能基团可以与液晶聚合物发生化学反应形成共价键，从而进一步提高导热填料与液晶聚合物间的界面结合强度，有利于消除界面缝隙带来的空气热阻，从而能够提高导热材料的导热系数。
可选的，将导热填料分散于具有液晶聚合物的溶液中，得到导热填料分散液包括：首先，将导热填料加入有机溶剂中，并进行分散。然后，对分散后的溶液进行搅拌和通入惰性气体，加入催化剂和液晶聚合物，并进行加热回流反应，得到导热填料分散 液。通过先将导热填料在有机溶剂中进行分散，再加入液晶聚合物，能够使导热填料分散得更加均匀。
可选的，将导热填料分散于具有液晶聚合物的溶液中，得到导热填料分散液包括：首先，将导热填料以及液晶聚合物加入有机溶剂中，并进行分散。然后，对分散后的溶液进行搅拌和通入惰性气体，加入催化剂，并进行加热回流反应，得到导热填料分散液。这样一来，可以将导热填料和液晶聚合物一起在有机溶剂中进行分散。
在本申请的另一些实施例中，提供一种导热材料。该导热材料包括基体聚合物、液晶聚合物、固化剂以及导热填料。该导热填料填充于基体聚合物内。导热填料表面的至少一部分包覆有液晶聚合物。液晶聚合物与基体聚合物之间通过固化剂形成化学键连接。液晶聚合物与导热填料的亲和性，大于基体聚合物与导热填料的亲和性。这样一来，当将导热填料分散在液晶聚合物和基体聚合物构成的共混物中时，导热填料会选择性分布于亲和性更强的液晶聚合物中。从而使得多个导热填料堆积形成的导热网络结构表面，原位包覆的液晶聚合物的分子链沿着填料粒子一定的晶面方向上规整堆叠。此外，导热填料和液晶聚合物之间通过分子间作用力以及部分化学键，即共价键连接。液晶聚合物与基体聚合物之间通过固化剂形成共价键连接。
可选的，多个导热填料堆积形成的导热网络结构，液晶聚合物包覆于导热网络结构的表面形成网链结构。网链结构中的液晶聚合物通过与固化剂形成化学键连接。从而有利于有效降低填料与聚合物基体间的界面热阻，可以使得热量以声子的形式在导热网络结构中，通过晶格的振动进行传输。当导热材料前体固化后，上述网链结构可以形成致密的导热通路，有利于热量的高效传输。
可选的，液晶聚合物包括液晶环氧树脂。其中，液晶环氧树脂包括联苯型液晶环氧树脂、芳酯型液晶环氧树脂、α-甲基苯乙烯型液晶环氧树脂、偶氮型液晶环氧树脂、亚甲胺型液晶环氧树脂、萘型液晶环氧树脂、苯并菲型液晶环氧树脂中的至少一种。上述液晶聚合物具有较高的导热系数，导热系数可以大于或等于0.25W/mk。
可选的，液晶聚合物包括可发生交联反应的功能基团，功能基团包括环氧基、烯基、炔基、氰酸酯基、异氰酸酯基、苯并环丁烯基中的至少一种。液晶聚合物包括规整的液晶单元，液晶单元包括联苯结构、芳酯结构、α-甲基苯乙烯结构、偶氮结构、亚甲胺结构、联萘结构、苯并菲结构中的至少一种。液晶聚合物的功能基团可以与导热填料表面的功能基团发生交联反应，形成化学键，例如共价键。从而进一步提高导热填料与液晶聚合物间的界面结合强度，有利于消除界面缝隙带来的空气热阻，从而能够提高导热材料的导热系数。
可选的，基体聚合物包括：聚苯醚、碳氢树脂、环氧树脂、氰酸酯、双马来酰亚胺树脂、有机硅树脂、聚酰亚胺中的至少一种。液晶聚合物和基体聚合物的选择搭配中，需保证导热填料与液晶聚合物的亲和性，相对于导热填料与基体聚合物的亲和性更强。
可选的，液晶聚合物的重量比占导热材料中聚合物总量的3～30wt％，从而有利于提高导热材料的导热系数。
可选的，导热填料包括纳米级或微米级无机导热材料。构成无机导热材料包括二氧化硅、氧化铝、氮化铝、氮化硼、碳化硅、金刚石中的至少一种。其中，二氧化硅 和氧化铝的导热系数相对较低，但是容易获得且成本较低。氮化铝、氮化硼、碳化硅的导热系数相对较高。
可选的，导热材料中至少两个导热填料的粒径不同。这样一来，具有较大粒径的导热填料之间形成的空隙中，可以嵌入粒径较小的导热填料，从而能够进一步提高多个改性导热填料堆积形成的导热网络结构的致密性，有利于进一步提高得到的导热材料的导热效率。
本申请实施例的另一方面，提供一种用于制作如上所述的任意一种导热材料的方法。上述方法包括：首先，将导热填料、液晶聚合物加入有机溶剂中，并进行搅拌溶解和分散。然后，在搅拌后，加入基体聚合物、固化剂和固化促进剂，继续搅拌得到导热材料前体。其中，液晶聚合物与导热填料的亲和性，大于基体聚合物与导热填料的亲和性。然后，将导热材料前体倒入模具中，进行真空脱泡以及固化或半固化处理，得到导热材料，或者，将导热材料前体与有机溶剂混合，并通过调节溶液固含量得到预浸渍料，将预浸渍料涂布于基材上，并烘烤后形成包覆基材的导热材料。采用上述制备导热材料的方法的技术效果与上述导热材料的技术效果相同，此处不再赘述。
本申请实施例的另一方面，提供一种半固化片。该半固化片包括基材以及如上所述的任意一种导热材料，导热材料包覆基材。该半固化片具有与前述实施例提供的导热材料相同的技术效果，此处不再赘述。
本申请实施例的另一方面，提供一种层压板。层压板包括铜箔以及上所述的半固化片。铜箔覆盖半固化片的表面。该层压板具有与前述实施例提供的导热材料相同的技术效果，此处不再赘述。
本申请实施例的另一方面，提供一种电路板。该电路板包括上述半固化片和上述层压板，层压板和半固化片层叠设置。该电路板具有与前述实施例提供的半固化片和层压板相同的技术效果，此处不再赘述。
附图说明
图1为本申请实施例提供的一种导热材料的应用场景；
图2为本申请实施例提供的另一种导热材料的应用场景；
图3为本申请实施例提供的一种导热材料的制作方法；
图4为本申请实施例提供的另一种导热材料的制作方法；
图5为采用图4所示的制作方法制备的改性导热材料的一种结构示意图；
图6为采用图4所示的制作方法制备的改性导热材料的形成原理示意图；
图7A为采用图4所示的制作方法制备的导热材料的一种结构示意图；
图7B为采用图4所示的制作方法制备的导热材料的另一种结构示意图；
图7C为采用图4所示的制作方法制备的导热材料的另一种结构示意图；
图8为相关技术提供的导热材料的一种结构示意图；
图9为本申请实施例提供的界面热阻的产生原理图；
图10为本申请实施例提供的导热材料的另一种结构示意图。
附图标记：
10-热界面材料；11-芯片；12-承载基板；13-底部填充料；14-塑封料；15-塑料盖板；16-导热胶；17-导热灌封料；18-半固化片；19-CCL；22-液晶聚合物；30-导热填 料；200-改性导热填料；20-液晶单元；21-液晶聚合物的功能基团；31-导热填料的功能基团；41-导热材料前体；201-导热网络结构；40-基体聚合物；22-液晶聚合物；301-网链结构。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。
以下，术语“第一”、“第二”等仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”等的特征可以明示或者隐含地包括一个或者更多个该特征。
此外，本申请中，“上”、“下”、“左”、“右”等方位术语是相对于附图中的部件示意置放的方位来定义的，应当理解到，这些方向性术语是相对的概念，它们用于相对于的描述和澄清，其可以根据附图中部件所放置的方位的变化而相应地发生变化。
在本申请中，除非另有明确的规定和限定，术语“连接”应做广义理解，例如，“连接”可以是固定连接，也可以是可拆卸连接，或成一体；可以是直接相连，也可以通过中间媒介间接相连。
随着电子器件集成化、小型化，且功率密度大的设计要求，电子器件在运行过程中产生的热量急剧增加。本申请对上述电子器件的具体形式不做限定，例如，该电子器件可以包括手机(mobile phone)、平板电脑(pad)、电视、智能穿戴产品(例如，智能手表、智能手环)、虚拟现实(virtual reality，VR)设备、增强现实(augmented reality AR)设备等。上述电子器件还可以是充电电动汽车、充电家用小型电器(例如豆浆机、扫地机器人)、无人机等电子产品。
基于此，为了降低电子器件在运行过程中产生的热量，该电子器件中的部分结构可以采用本申请实施例提供的导热材料制备。以下对本申请实施例提供的导热材料在上述电子产品中的应用场景进行举例说明。
在本申请的一些实施例中，采用上述导热材料可以用于制备呈半固化状态或者固化状态的导热块体。该导热块体可以用于制备例如，图1中的(a)所示的设置于芯片11表面的热界面材料(thermal interface material，TIM)10，如图1中的(b)所示的设置于芯片11与承载基板12之间底部填充料13，如图1中的(c)所示的用于塑封芯片11的塑封料(molding)14，如图1中的(d)所示的用于制备成上述电子器件的壳体的塑料盖板15，如图1中的(e)所示的用于涂覆于发热器件，例如芯片11表面的导热胶16，以及如图1中的(f)所示的应用于灌封工艺中的导热灌封料17等。
需要说明的是，在上述导热块体的应用领域中，可以将半固化状态或者固化状态的导热块体直接进行应用，或者还可以进行加热，或者进一步固化处理之后再应用，本申请对此不做限定。
或者，在本申请的另一些实施例中，采用上述导热材料还可以用于制备的如图2中的(a)所示的半固化片18。基于此，如图2中的(b)所示，在制备好的半固化片18的上、下表面中的至少一个表面覆以铜箔181，压制得到覆铜箔层压板(copper clad laminate，CCL)19，也可以简称为层压板或者覆铜板。在此情况下，本申请实施例还提供一种电路板，例如印制电路板(printed circuit board，PCB)。该PCB可以通过将 多层CCL19与半固化片18层叠设置，并根据设计需要进行热压、加工、蚀刻、钻孔及镀铜等工序制成。
以下根据导热材料不同的制作方法，对上述导热材料的结构以及制作过程、导热原理等进行详细的举例说明。
示例一
本示例采用采用接枝包覆法，即采用接枝聚合(grating to)法，通过液晶聚合物对导热填料进行接枝包覆改性处理。从而将液晶聚合物的分子链接枝到导热填料的表面。然后，将改性后的导热填料添加到聚合物基体中，形成本示例一提供的导热材料。该导热材料的制作方法，可以包括如图3所示的S101和S102。
S101、制备导热材料前体(也称为胶液)。
本示例中的S101可以包括如图4所示的S201和S202，或者，可以包括S211、S201以及S202。
S201、制作改性导热填料200。
具体的，将导热填料分散于溶解有一定量液晶聚合物的溶液中，得到导热填料分散液。加入催化剂，加热回流充分反应后，过滤得到导热填料，然后，采用有机溶剂对导热填料进行洗涤，以去除导热填料中未反应的液晶聚合物。然后，对导热填料进行干燥和研磨(或粉碎)处理得到如图5所示的改性导热填料200。改性导热填料200包括导热填料30以及接枝包覆于该导热填料30表面的液晶聚合物22。从而使得导热填料30的表面可以被液晶聚合物22形成的壳层结构完全或近似完全包围，且导热填料30与液晶聚合物22之间通过共价键相结合。
需要说明的是，上述将导热填料分散于溶解有一定量液晶聚合物的溶液中是指，将由多个颗粒状的导热填料30构成的填料材料倒入上述溶液中，并将该填料材料中的多个颗粒状的导热填料30分散于该溶液中。在此情况下，至少一颗导热填料30的表面会接枝包覆有上述液晶聚合物22，从而可以形成至少一个颗粒状的改性导热填料200。
此外，本示例一中，液晶聚合物22接枝包覆于该导热填料30表面是指，采用上述接枝聚合法制作改性导热填料200的过程中，在制作精度允许的情况下，导热填料30可以被液晶聚合物22完全或近似完全包覆。
在本申请的一些实施例中，为了制作上述导热填料分散液，可以先将导热填料加入有机溶剂中，并进行分散。例如，将导热填料加入适量有机溶剂中，超声分散0.5-2h。然后，对分散后的溶液进行搅拌和通入惰性气体，加入催化剂和液晶聚合物，并进行加热回流反应，得到导热填料分散液。示例的，在磁力搅拌和氮气保护下加入液晶聚合物，例如，液晶环氧树脂(liquid crystal epoxy resin，LCEP)，在80-120℃下加热回流反应4-12h。本实施方案中，是先将导热填料在有机溶剂中进行分散，再加入液晶聚合物。
或者，在本申请的另一些实施例中，为了制作上述导热填料分散液可以先将导热填料以及液晶聚物加入有机溶剂中，并进行分散。然后，对分散后的溶液进行搅拌和通入惰性气体，加入催化剂，并进行加热回流反应，得到导热填料分散液。本实施方案中，是将导热填料和液晶聚合物一起在有机溶剂中进行分散。
上述制作上述导热填料分散液的两种实施方式相比较而言，先将导热填料在有机溶剂中进行分散，再加入液晶聚合物的方式，能够使得导热填料分散的更加均匀。这样一来，通过液晶聚合物对导热填料进行接枝包覆的过程中，可以使得每个导热填料的表面均被液晶聚合物形成的壳层包覆。
示例的，上述导热填料可以包括纳米级或微米级无机导热材料。例如，上述无机导热材料可以包括二氧化硅(SiO 2)、氧化铝(Al 2O 3)、氮化铝(AlN)、氮化硼(BN)、碳化硅(SiC)等中的至少一种。此外，上述导热填料还可以为纳米金刚石。其中，上述导热填料中，二氧化硅(SiO 2)和氧化铝(Al 2O 3)的导热系数相对较低，例如小于40W/mk。但是容易获得且成本较低。氮化铝(AlN)、氮化硼(BN)、碳化硅(SiC)以及纳米金刚石具有较高的导热系数，例如大于80W/mk。因此能够有效提升最终制得的导热材料的导热系数。
需要说明的是，上述导热系数也可以称为热导率(thermal conductivity)，是物质导热能力的量度。导热系数具体是指当温度垂直向下梯度为1℃/m时，单位时间内通过单位水平截面积所传递的热量。导热系数的单位为瓦特·米 -1·开 -1(W·m -1·K -1)，或者，瓦特/米开(W/mk)。
此外，本申请实施例中，采用的液晶聚合物可以为热固性液晶聚合物，该液晶聚合物具有较高的导热系数(例如，导热系数可以大于或等于0.25W/mk)。示例的，液晶聚合物可以包括液晶环氧树脂。其中，液晶环氧树脂包括联苯型液晶环氧树脂、芳酯型液晶环氧树脂、α-甲基苯乙烯型液晶环氧树脂、偶氮型液晶环氧树脂、亚甲胺型液晶环氧树脂、萘型液晶环氧树脂、苯并菲型液晶环氧树脂等中的至少一种。
上述液晶聚合物为预聚体，该预聚体的分子量较低。液晶聚合物具有可发生交联反应的如图6所示的功能基团(称为聚合物的功能基团21)。该聚合物的功能基团21可以包括环氧基、烯基(乙烯基、丙烯基等)、炔基、氰酸酯基、异氰酸酯基、苯并环丁烯基等中的至少一种。此外，液晶聚合物还可以包括如图6所示的液晶单元20。上述液晶单元20规整排布。
其中，液晶单元20是指具有液晶特征的基团，示例的，上述液晶单元20可以包括联苯结构
Figure PCTCN2022082479-appb-000001
芳酯结构
Figure PCTCN2022082479-appb-000002
Figure PCTCN2022082479-appb-000003
α-甲基苯乙烯结构
Figure PCTCN2022082479-appb-000004
偶氮结构
Figure PCTCN2022082479-appb-000005
亚甲胺结构
Figure PCTCN2022082479-appb-000006
其中Y为
Figure PCTCN2022082479-appb-000007
联 萘结构
Figure PCTCN2022082479-appb-000008
苯并菲结构
Figure PCTCN2022082479-appb-000009
等中的至少一种。
在此情况下，执行上述S201得到的导热填料分散液中，液晶聚合物的功能基团21，如功能基团可以与导热填料的功能基团31发生化学反应，形成化学键，例如共价键。
在本申请的一些实施例中，在执行S201之前，导热材料的制作方法还可以包括如图4所示的S211(对导热填料进行偶联剂处理)。例如，将导热填料30加入具有偶联剂的溶液中，进行偶联剂处理，并将经过偶联剂处理后的溶液进行过滤、洗涤并干燥。
例如，将偶联剂滴加主要由乙醇、去离子水组成的混合溶剂中，再加入导热填料，在25-80℃下反应0.5-12h。此外，通过过滤可以去除S210得到的溶液中的溶剂，并采用溶剂，例如乙醇和去离子水进行洗涤去除未发生反应的偶联剂，然后在80-140℃下干燥0.5-6h。
上述偶联剂可以为硅烷偶联剂。通过偶联剂对导热填料30的表面进行处理，可以根据不同的硅烷偶联剂，在导热填料30的表面引入不同的功能基团，例如环氧基、氨基、乙烯基等。引入的功能基团可以与S201中的液晶聚合物发生化学反应形成共价键，从而进一步提高导热填料与液晶聚合物间的界面结合强度，有利于消除界面缝隙带来的空气热阻，从而能够提高导热材料的导热系数。
S202、将改性导热填料200分散于具有基体聚合物40的溶液中。
执行上述S202后可以得到如图7A所示的导热材料前体41。示例的，将上述液晶聚合物22接枝包覆的导热填料30、基体聚合物40、固化剂按照一定配比加入适量有机溶剂中，机械搅拌0.5-3h溶解分散后，再加入适量固化促进剂继续搅拌0.5-2h，制备得到导热材料前体41。
本示例对S202中采用的基体聚合物的材料不做限定，例如可以为环氧树脂。在此情况下，上述导热材料前体41中的改性导热填料200中，导热填料30表面接枝的液晶聚合物22的一端与导热填料30通过共价键连接，液晶聚合物22的另一端与基体聚合物40通过固化剂发生共价交联。导热填料30表面接枝的液晶聚合物22，能够沿着导热填料30粒子在特定的晶面方向上形成规整的堆积结构。
在此基础上，当基体聚合物40中导热填料30填充量较高时，如图7B所示，导热填料30表面接枝包覆的液晶聚合物22的分子链除了与基体聚合物40发生交联反应以外，相邻的导热填料30表面的液晶聚合物22也通过固化剂发生交联反应，从而可以消除相邻的改性导热填料200之间的间隙，并在导热材料前体41中，形成由多个改性导热填料200彼此相连构成的致密的导热网络。
相关技术中，如图8所示，可以直接将导热填料30添加至基体聚合物40中以形成导热材料。此时，各个填料的周边均被基体聚合物40包围。其中，导热填料30中 的分子如图9所示具有规整的晶体结构，原子有序排布。因此在导热填料30中，热量(图中的黑色箭头所示)可以通过晶格振动由如图9所示的左端传递至如图9所示的右端。所以导热填料30的导热系数较高。
然而，基体聚合物40是非晶结构，分子链无序排列。因此如图9所示，在基体聚合物40中，热量传输无序从而使得声子色散(phonon scattering)较大，导热系数低。所以直接将导热填料30添加至基体聚合物40制备的导热材料中，导热填料30与基体聚合物40之间由于声子谱不匹配，因此存在较大的导热系数差异(声子谱不匹配)，从而使得导热填料30和基体聚合物40的界面上存在的声子散射带来巨大界面热阻(卡皮查热阻)，不利于提高导热材料的导热系数。
需要说明的是，在绝缘材料中，热量以声子的形成进行传输。声子(phonon)是一种非真实的准粒子，是用来描述晶体原子热振动，即晶格振动规律的一种能量量子，它的能量等于
Figure PCTCN2022082479-appb-000010
综上所述，相对于图8所示的方案而言，本申请实施例提供导热材料包括基体聚合物40、固化剂以及改性导热填料200。其中，如图7A所示，改性导热填料200填充于基体聚合物40中，且改性导热填料200中的导热填料30的表面接枝包覆有液晶聚合物22。
由上述可知，一方面，导热填料30与液晶聚合物22之间通过较强的共价键连接，且包覆该导热填料30的液晶聚合物22，可以消除导热填料30与聚合物基体之间的空气热阻，更有利于降低导热填料与聚合物基体之间的界面热阻。
另一方面，该液晶聚合物22为大分子液晶，内部有规整的液晶单元20，因此液晶聚合物22能够沿着导热填料30粒子在特定的晶面方向上形成规整的堆积结构。该规则结构有利于声子传输，从而有效减小导热填料30与聚合物基体界面处的声子色散，有利于降低导热填料30与聚合物基体之间的界面热阻。
又一方面，热固性液晶聚合物自身具有较高的导热系数，例如导热系数可以大于或等于0.25W/mk，其导热系数高于无定型聚合物，从而有利于提高最终得到的导热材料的导热效率。
又一方面，在制备导热材料的过程中，采用液晶聚合物22对导热填料30的表面进行接枝包覆的方法提高导热材料的散热能力，相对于利用磁场、电场等诱导一维或二维导热填料取向分布，形成有序结构的方式而言，制备方法更加简单，产率高、效果明显，更适合工业化生产。
在此基础上，当基体聚合物40中导热填料30填充量较高时，如图7B所示，多个改性导热填料200可以堆积形成致密的导热网络结构201，且相接触的多个改性导热填料200的液晶聚合物22通过化学键连接。这样一来，可以使得热量以声子的形式在导热网络结构201中，通过晶格的振动进行传输，从而进一步提高最终得到的导热材料的导热效率。
其中，本申请实施例对导热材料中，导热填料30粒径大小不做限定，图7A和图7B是以导热填料的粒径大小均相同为例进行的说明。在本申请的另一些实施例中，如图7C所示，导热材料中至少两个导热填料30粒径可以不同，这样一来，具有较大粒径的导热填料30之间形成的空隙中，可以嵌入粒径较小的导热填料30，从而能够进 一步提高多个改性导热填料200堆积形成的导热网络结构201的致密性，有利于进一步提高得到的导热材料的导热效率。
S102、采用导热材料前体41制作导热材料。
例如，在本申请的一些实施例中，可以将导热材料前体41倒入模具中，进行真空脱泡以及固化或半固化处理，得到导热材料。具体的，将导热材料前体41倒入模具中，进行真空脱泡以及固化或半固化处理，得到导热材料可以作为上述导热块体。该导热块体可以用于制备图1中的(a)所示的热界面材料10、如图1中的(b)所示的底部填充料13、如图1中的(c)所示的塑封料14、如图1中的(d)所示的塑料盖板15以及如图1中的(e)所示的导热胶16。
或者，在本申请的另一些实施例中，将导热材料前体与有机溶剂混合，并通过调节溶液固含量得到预浸渍料。具体的，可以将导热材料前体41与有机溶剂混合，并通过调节溶液固含量(例如，50-80wt％)得到预浸渍料。将预浸渍料涂布于基材上，并烘烤后可以形成包覆该基材的导热材料。上述基材以及包覆该基材的导热材料可以用于构成如图2中的(a)所示的半固化片18。
示例的，在制作半固化片18的过程中，可以将该预浸渍料涂布在基材，例如玻璃布(例如E型玻璃布)上，并在140-190℃烘箱中烘烤1-30分钟后制得树脂含量为60-85％的半固化片。由上述可知，将制得的半固化片18的上、下各放一张铜箔，置于真空热压机中于1-50MPa压力和170-230℃温度下，压制可以得到如图2中的(b)所示的CCL19。上述仅仅是对半固化片18和CCL19制作过程的举例说明，本申请对半固化片18和CCL19的制作方法不进行限定，其他制作方法在此不再一一赘述。
需要说明的是，图7A、图7B以及图8中的箭头代表热量以声子的形式在导热材料中的一种可能的传输路径，本申请对该传输路径不做限定，其余传输路径的实现方式在此不再一一赘述。
以下结合不同材料的导热填料30、液晶聚合物22以及基体聚合物40，对上述S101(S201和S202)、S102以及利用导热材料制备半固化片18和CCL19的方式进行详细的举例说明。
实施方式一
本实施例方式中，导热填料30的材料为氧化铝(Al 2O 3)，液晶聚合物22的材料为四甲基联苯环氧树脂(导热系数为0.27W/mk)，基体聚合物40的材料为双酚A型环氧树脂。在此情况下，导热材料前体41的制作方法可以包括上述S201和S202。以下结合上述导热填料30、液晶聚合物22以及基体聚合物40的具体材料，对上述S201、S202、S102以及半固化片18和CCL19的方式进行举例说明。
首先，执行上述S201，以制作改性导热填料200。
例如，将作为导热填料30的氧化铝(Al 2O 3)颗粒和作为液晶聚合物22的四甲基联苯环氧树脂加入有机溶剂丁酮中。其中，氧化铝(Al 2O 3)颗粒与丁酮的质量比可以为1/40。接下来，在三颈烧瓶中混合并超声分散1小时。然后，在磁力搅拌和氮气保护下加入作为催化剂的四丁基溴化铵(相对于四甲基联苯环氧树脂的质量比为2wt％)，并在100℃下加热回流反应12h。接下来过滤，用丁酮洗涤，干燥并粉碎，得到上述改性导热填料200。该改性导热填料200为四甲基联苯环氧树脂接枝包覆的氧化铝(记 为Al 2O 3-g-EP)。
接下来，执行S202以制作导热材料前体41。
例如，依次在反应瓶中加入适量的有机溶剂丁酮、作为基体聚合物40的双酚A型环氧树脂、酚醛树脂固化剂和表1中不同粒径的改性导热填料200(Al 2O 3-g-EP)，机械搅拌1h溶解分散后，再加入适量固化促进剂2甲基咪唑(2MZ)继续搅拌1h，得到导热材料前体41。
接下来，在一些实施例中，可以执行上述S102以制作导热材料。
具体的，将上述导热材料前体41倒入成膜模具中，进行真空脱泡和固化成型，制备得到四甲基联苯环氧树脂接枝包覆的氧化铝填充的高导热环氧树脂基导热材料。该导热材料可以作为上述导热块体，用于制备上述热界面材料10、底部填充料13、塑封料14、塑料盖板15以及导热胶16。
或者，接下来，在另一些实施例中，制备半固化片18和CCL19。
例如，将环氧树脂、酚醛树脂固化剂以及上述改性导热填料200(Al 2O 3-g-EP)、固化促进剂2甲基咪唑(2MZ)、添加剂等按表1的配方配料，然后用丁酮和二甲苯按照体积比2:1混合作为溶剂溶解，调节树脂组合物的固含量为65％，用机械搅拌在室温下搅拌均匀调制成预浸渍料。
接下来，将该预浸料涂布在E型玻璃布(规格2116，单重104g/m 2)上，并在170℃烘箱中烘烤10分钟后制得树脂含量为80％的半固化片18。然后，将制得的树脂含量为80％的半固化片18的上、下表面各放一张铜箔，置于真空热压机中于2MPa压力和200℃温度下，压制得到CCL19。在此情况下，制得的CCL19中介质层(由半固化片18固化后形成)的导热系数如表1所示。
表1
Figure PCTCN2022082479-appb-000011
Figure PCTCN2022082479-appb-000012
表1中，测试项1、测试项2、以及测试项3均是采用改性导热填料200(Al 2O 3-g-EP)填充的导热材料制备CCL19为例进行的说明。其中，采用测试项1的配方制备的CCL19中树脂含量可以为40份(32+8)。采用测试项2的配方制备的CCL19中树脂含量可以为50份(40+10)。采用测试项3的配方制备的CCL19中树脂含量可以为60份(48+12)。
由表1可以看出，测试项2和测试项3的树脂含量较高，改性导热填料200(Al 2O 3-g-EP)的含量较低。所以，采用测试项2和测试项3的配方制备的CCL19中介质层的介质导热系数较低，依次分别为0.65W/mk、0.58W/mk。反之，测试项1的树脂含量最低，所以改性导热填料200(Al 2O 3-g-EP)的含量最高，因此采用测试项1的配方制备的CCL19中介质层的介质导热系数最高，例如为0.83W/mk。
此外，对比项1和对比项2均是采用未用液晶聚合物改性的原始导热填料(Al 2O 3)填充的导热材料制备CCL19为例进行的说明。其中，对比项1与测试项1中，不同粒径的填料的份数相同，均是粒径(D50)为10um、6um、3um以及0.2um的填料颗粒的份数分别为24份、18份、12份以及6份。但是由于测试项1是采用改性导热填料200(Al 2O 3-g-EP)填充的导热材料制备CCL19，因此采用测试项1制备CCL19中介质层的介质导热系数(为0.83W/mk)高于，采用对比项1制备CCL19中介质层的介质导热系数(0.61W/mk)。
同理，对比项2与测试项3中，不同粒径的填料的份数相同，均是粒径(D50)为10um、6um、3um以及0.2um的填料颗粒的份数分别为20份、12份、6份以及2份。但是由于测试项3是采用改性导热填料200(Al 2O 3-g-EP)填充的导热材料制备CCL19，因此采用测试项3制备CCL19中介质层的介质导热系数(为0.58W/mk)高于，采用对比项1制备CCL19中介质层的介质导热系数(0.42W/mk)。
综上所述，采用本申请实施例提供的改性导热填料200(Al 2O 3-g-EP)填充的导热材料制备CCL19中介质层的介质导热系数，高于未采用液晶聚合物改性的原始导热填料(Al 2O 3)填充的导热材料制备CCL19中介质层的介质导热系数。并且，当导热材料中改性导热填料200(Al 2O 3-g-EP)的填充量越高，最终得到的CCL19中介质层的介质导热系数，从而有利于提高具有该CCL19的电子设备的散热能力。
实施方式二
本实施例方式中，与实施方式一相同的部分在于导热填料30的材料为氧化铝(Al 2O 3)、液晶聚合物22的材料为四甲基联苯环氧树脂(导热系数为0.27W/mk)，基体聚合物40的材料为双酚A型环氧树脂。
与实施方式一不同之处在于，在执行S201之前执行上述S211。在此情况下，导热材料前体41的制作方法可以包括上述S211、S201以及S202。以下结合上述导热填料30、液晶聚合物22以及基体聚合物40的具体材料，对上述S211、S201、S202、S102以及半固化片18和CCL19的方式进行举例说明。
首先，执行上述S211，对导热填料30进行偶联剂处理。
例如，将作为导热填料30的氧化铝(Al 2O 3)颗粒、硅烷偶联剂(KH550)加入 乙醇和去离子水混合溶液(其中，乙醇和去离子水的质量比为90/10)中，超声分散30min。将溶液的氢离子浓度指数(pH值)预先用硫酸调节至5-6。然后，在氮气保护下磁力搅拌加热回流反应5h。然后，对溶液进行过滤，用无水乙醇洗涤，干燥并粉碎，从而在作为导热填料30的氧化铝(Al 2O 3)颗粒表面引入氨基，获得偶联剂处理后的氧化铝(记为Al 2O 3-KH550)。
接下来，执行上述S201，以制作改性导热填料200。
例如，将执行上述S211后得到的偶联剂处理后的氧化铝(Al 2O 3-KH550)加入有机溶剂丁酮中，使得Al 2O 3颗粒与丁酮的质量比1/40，并在三颈烧瓶中混合并超声分散30min。然后，在磁力搅拌和氮气保护下加入作为液晶聚合物22的四甲基联苯环氧树脂，加入适量2甲基咪唑(2MZ)作为引发剂，在100℃下加热回流反应8h。接下来过滤，并用丁酮洗涤，干燥并粉碎，得到上述改性导热填料200。该改性导热填料200为四甲基联苯环氧树脂接枝包覆的氧化铝(记为Al 2O 3-g-EP)。
接下来，执行S202制作导热材料前体41、执行上述S102以制作导热材料，或者采用S201制备的改性导热填料200制作半固化片18和CCL19的制作过程与实施方式一相同，此处不再赘述。制得的CCL19中介质层的导热系数如表2所示。
表2
Figure PCTCN2022082479-appb-000013
需要说明的是，表2中测试项1、测试项2、以及测试项3是将实施方式一中的导热填料替换为实施方式二中，先将导热填料经过偶联剂处理，再经过液晶聚合物改性处理得到的改性导热填料200，其他组分与表1中测试项1、测试项2、以及测试项3的配方(或组分)相同，因此表2中不再一一体现。
由上述可知，本实施方式二中，制作改性导热填料200之前，对作为导热填料30的氧化铝(Al 2O 3)颗粒进行了偶联剂处理。偶联剂可以提高导热填料30与液晶聚合物22间的界面结合强度和接枝密度，从而能够提高导热材料的导热系数。
因此，由表2和表1可知，本实施方式二中，采用测试项1、测试项2、测试项3的配方制备的CCL19中介质层的介质导热系数(分别为0.97W/mk、0.79W/mk、0.68W/mk)，分别高于实施方式一中，采用测试项1、测试项2、测试项3的配方制备的CCL19中介质层的介质导热系数(分别为0.83W/mk、0.65W/mk、0.58W/mk)。
实施方式三
本实施例方式中，与实施方式一的不同之处在于，液晶聚合物22的材料为多液晶单元环氧树脂(导热系数为0.5W/mk)。
需要说明的是，上述多液晶单元环氧树脂是指，环氧树脂单体中具有两个或两个以上的液晶单元20。该液晶单元20可以是上述联苯结构、芳酯结构、α-甲基苯乙烯结构、偶氮结构、亚甲胺结构、联萘结构、苯并菲结构等。并且，多液晶单元环氧树脂的单体中的多个液晶单元20可以相同，也可以不同，本申请对此不作限定。
为了方便说明，以下实施方式中的多液晶单元环氧树脂，均是单体中具有两个液晶单元20，且该两个液晶单元20均为联苯结构为例进行的说明。其他多液晶单元20 的设置方式在此不再一一赘述。
与实施方式一的相同之处在于，导热填料30的材料为氧化铝(Al 2O 3)，基体聚合物40的材料为双酚A型环氧树脂。在此情况下，导热材料前体41的制作方法可以包括上述S201和S202。以下结合上述导热填料30、液晶聚合物22以及基体聚合物40的具体材料，对上述S201、S202、S102以及半固化片18和CCL19的方式进行举例说明。
首先，执行上述S201，以制作改性导热填料200。
例如，将导热填料30的材料为Al 2O 3颗粒、作为液晶聚合物22的多液晶单元环氧树脂加入有机溶剂丁酮中。其中，氧化铝(Al 2O 3)颗粒与丁酮的质量比可以为1/40。
接来下，与实施方式一相同，在三颈烧瓶中混合并超声分散1小时，然后，在磁力搅拌和氮气保护下加入作为催化剂的四丁基溴化铵(相对于四甲基联苯环氧树脂的质量比为2wt％)，并在100℃下加热回流反应12h。接下来过滤，用丁酮洗涤，干燥并粉碎，得到上述改性导热填料200。该改性导热填料200为多液晶单元环氧树脂接枝包覆的氧化铝(记为Al 2O 3-g-EP)。
接下来，执行S202制作导热材料前体41、执行上述S102以制作导热材料，或者采用S201制备的改性导热填料200制作半固化片18和CCL19的制作过程与实施方式一相同，此处不再赘述。制得的CCL19中介质层的导热系数如表3所示。
表3
Figure PCTCN2022082479-appb-000014
需要说明的是，表3中测试项1、测试项2、以及测试项3是将实施方式一中的液晶聚合物22由四甲基联苯环氧树脂，替换为实施方式三中的多液晶单元环氧树脂，其他组分与表1中测试项1、测试项2、以及测试项3的配方(或组分)相同，因此表3中不再一一体现。
由上述可知，本实施方式三中，在制作改性导热填料200的过程中，采用了导热系数更高的多液晶单元环氧树脂(导热系数为0.5W/mk)作为液晶聚合物22的材料，从而使得采用上述改性导热填料200填充聚合物基体获得的导热材料的导热系数更高。
因此，由表3和表1可知，本实施方式三中，采用测试项1、测试项2、测试项3的配方制备的CCL19中介质层的介质导热系数(分别为1.23W/mk、0.97W/mk、0.83W/mk)，分别高于实施方式一中，采用测试项1、测试项2、测试项3的配方制备的CCL19中介质层的介质导热系数(分别为0.83W/mk、0.65W/mk、0.58W/mk)。
此外，虽然实施方式二中，在制作200之前采用了偶联剂对导热填料30进行处理，但是由表3和表2可知，本实施方式三中，采用测试项1、测试项2、测试项3的配方制备的CCL19中介质层的介质导热系数(分别为1.23W/mk、0.97W/mk、0.83W/mk)，略高于实施方式二中，采用测试项1、测试项2、测试项3的配方制备的CCL19中介质层的介质导热系数(分别为0.97W/mk、0.79W/mk、0.68W/mk)。
实施方式四
本实施例方式中，与实施方式一的不同之处在于，液晶聚合物22的材料为多液晶单元环氧树脂(导热系数为0.5W/mk)，导热填料30的材料为氮化铝(AlN)。
与实施方式一的相同之处在于，基体聚合物40的材料为双酚A型环氧树脂。在此情况下，导热材料前体41的制作方法可以包括上述S201和S202。以下结合上述导热填料30、液晶聚合物22以及基体聚合物40的具体材料，对上述S201、S202、S102以及半固化片18和CCL19的方式进行举例说明。
首先，执行上述S201，以制作改性导热填料200。
例如，将导热填料30的材料为氮化铝(AlN)和作为液晶聚合物22的多液晶单元环氧树脂加入有机溶剂丁酮中其中，氧化铝(Al 2O 3)颗粒与丁酮的质量比可以为1/40。
接来下，与实施方式一相同，在三颈烧瓶中混合并超声分散1小时，然后，在磁力搅拌和氮气保护下加入作为催化剂的四丁基溴化铵(相对于四甲基联苯环氧树脂的质量比为2wt％)，并在100℃下加热回流反应12h。接下来过滤，用丁酮洗涤，干燥并粉碎，得到上述改性导热填料200。该改性导热填料200为多液晶单元环氧树脂接枝包覆的氮化铝(记为AlN-g-EP)。
接下来，在一些实施例中，可以执行S202制作导热材料前体41、执行上述S102以制作导热材料，制作过程与实施方式一相同，此处不再赘述。
或者，接下来，在另一些实施例中，制备半固化片18和CCL19。
例如，将双酚A型环氧树脂、酚醛树脂固化剂以及上述改性导热填料200(AlN-g-EP)、固化促进剂2甲基咪唑(2MZ)、添加剂等按表4的配方配料，然后用丁酮和二甲苯按照体积比2:1混合作为溶剂溶解，调节树脂组合物的固含量为75％，用机械搅拌在室温下搅拌均匀调制成预浸渍料。
接下来，与实施方式一相同，将该组合物预浸料涂布在E型玻璃布(规格2116，单重104g/m 2)上，并在170℃烘箱中烘烤10分钟后制得树脂含量为80％的半固化片18。然后，将制得的树脂含量为80％的半固化片18的上、下表面各放一张铜箔，置于真空热压机中于2MPa压力和200℃温度下，压制得到CCL19。在此情况下，制得的CCL19中介质层(由半固化片18固化后形成)的导热系数如表4所示。
表4
Figure PCTCN2022082479-appb-000015
Figure PCTCN2022082479-appb-000016
与实施方式一相同，表4中，测试项1、测试项2、以及测试项3均是采用改性导热填料200(Al 2O 3-g-EP)填充的导热材料制备CCL19为例进行的说明。其中，采用测试项1的配方制备的CCL19中树脂含量、采用测试项2的配方制备的CCL19中树脂含量以及采用测试项3的配方制备的CCL19中树脂含量均不同。
因此，与实施方式一同理可得，由表4可以看出，测试项2和测试项3的树脂含量较高，所以改性导热填料200(AlN-g-EP)的含量较低。所以，采用测试项2和测试项3的配方制备的CCL19中介质层的介质导热系数较低，依次分别为1.42W/mk、1.05W/mk。反之，测试项1的树脂含量最低，所以改性导热填料200(AlN-g-EP)的含量最高，因此采用测试项1的配方制备的CCL19中介质层的介质导热系数最高，例如为1.63W/mk。
此外，对比项1和对比项2均是采用未用液晶聚合物改性的原始导热填料(AlN-)填充的导热材料制备CCL19为例进行的说明。其中，对比项1与测试项1中，不同粒径的填料的份数相同。对比项2与测试项3中，不同粒径的填料的份数相同。
因此，采用测试项1制备CCL19中介质层的介质导热系数(为1.63W/mk)高于，采用对比项1制备CCL19中介质层的介质导热系数(1.03W/mk)。同理，采用测试项3制备CCL19中介质层的介质导热系数(1.05W/mk)高于，采用对比项2制备CCL19中介质层的介质导热系数(0.63W/mk)。
在此基础上，由上述可知，本实施方式四中，在制作改性导热填料200的过程中，采用了导热系数更高的多液晶单元环氧树脂(导热系数为0.5W/mk)作为液晶聚合物22的材料，从而使得采用上述改性导热填料200填充聚合物基体获得的导热材料的导热系数更高。
因此，由表4和表1可知，本实施方式四中，采用测试项1、测试项2、测试项3、对比项1和对比项2的配方制备的CCL19中介质层的介质导热系数(分别为1.63W/mk、1.42W/mk、1.05W/mk、1.03W/mk、0.63W/mk)，分别高于实施方式一中，采用测试项1、测试项2、测试项3、对比项1和对比项2的配方制备的CCL19中介质层的介质导热系数(分别为0.83W/mk、0.65W/m·k、0.58W/mk、0.61W/mk、0.42W/mk)。
示例二
本示例与示例一不同之处在于，本示例中，在聚合物基导热材料的制备过程中，可以采用溶液共混或熔融共混的方法，添加少量与导热填料30亲和性更好的热固性液晶聚合物22。从而可以使得液晶聚合物22能够对基体聚合物40中，由多个导热填料30构筑的导热网络结构的表面进行原位包覆，形成本申请实施例提供的导热材料，可以称为液晶聚合物原位包覆导热填料网络构筑的导热材料。该导热材料的制作方法， 可以包括上述S101和S102。
首先执行S101，具体的，可以包括：将导热填料30、液晶聚合物22加入有机溶剂中，并搅拌进行溶解和分散，例如机械搅拌0.5-2h。在搅拌后，加入基体聚合物40、固化剂和固化促进剂，继续搅拌进行溶解和分散，例如继续机械搅拌0.5-2h，得到如图10所示的导热材料前体41。
其中，无机的导热填料30在不同的聚合物中，与聚合物的相互作用不同。若导热填料30与聚合物的相互作用强，则导热填料30与该聚合物的亲和性好，或润湿性更好。本示例二中，液晶聚合物22与导热填料30的亲和性，大于基体聚合物40与导热填料30的亲和性。这样一来，当将导热填料30分散在液晶聚合物22和基体聚合物40构成的共混物中时，导热填料30会选择性分布于亲和性更强的聚合物组分，例如液晶聚合物22中。
基于此，为了使得导热填料30与液晶聚合物22的亲和性，相对于导热填料30与基体聚合物40的亲和性更强，基体聚合物40可以包括：聚苯醚、碳氢树脂、环氧树脂、氰酸酯、双马来酰亚胺树脂、有机硅树脂、聚酰亚胺等中的至少一种。此外，上述导热填料30和液晶聚合物22的材料与示例一相同，此处不再赘述。
在本申请的一些实施例中，液晶聚合物22的重量比可以占导热材料中聚合物总量的3-30wt％，例如，5-10wt％，从而有利于提高导热材料的导热系数。其中，导热材料中的聚合物总量包括液晶聚合物22、基体聚合物40以及上述固化剂和固化促化剂的重量之和。
在此情况下，采用溶液共混或熔融共混等方法执行上述S101制备导热材料前体41的过程中，由于导热填料30和热固性液晶聚合物22的亲和性更好，因此液晶聚合物22可以通过热力学作用吸附在导热填料30表面。在此基础上，由于液晶聚合物22倾向于聚集成相，因此能够驱动导热填料30自凝聚以堆积形成导热网络结构。此外，在导热填料30构筑的导热网络结构表面包覆有一层具有高导热系数(≥0.25W/mk)的液晶聚合物22，形成网链结构301。
综上所述，相对于图8所示的方案而言，本实例二提供导热材料包括导热填料30、液晶聚合物22、固化剂以及基体聚合物40。导热填料30填充于基体聚合物40内，且该导热填料30表面的至少一部分包覆有液晶聚合物22。该液晶聚合物22与基体聚合物40之间通过固化剂形成化学键连接。
需要说明的是，本示例二中，导热填料30表面的至少一部分包覆有液晶聚合物22是指，导热填料30表面可以被液晶聚合物22完全包覆。或者，液晶聚合物22可以只包覆导热填料30表面的一部分，该导热填料30未被液晶聚合物22包覆的部分可以与另一个导热填料30相接触，或者还可以与基体聚合物40相接触。
此外，由上述可知，液晶聚合物22与导热填料30的亲和性，大于基体聚合物40与导热填料30的亲和性。其中，如图10所示，当基体聚合物40中导热填料30填充量较高时，基体聚合物40中的多个导热填料30堆积形成的导热网络结构。导热网络结构表面包覆有液晶聚合物22，形成网链结构301。
这样一来，一方面，多个导热填料30堆积形成的导热网络结构表面，原位包覆的液晶聚合物22的分子链沿着填料粒子一定的晶面方向上规整堆叠。此外，导热填料 30和液晶聚合物22之间通过分子间作用力以及部分化学键，即共价键连接。液晶聚合物22与基体聚合物40之间通过固化剂形成共价键连接。
此外，如图10所示，导热材料前体41可以包括由上述导热填料30和填料网络表面原位包覆的液晶聚合物22(例如，液晶环氧树脂)共同构筑的三维贯通的导热网链。上述网链结构中的液晶聚合物22之间通过固化剂进行共价键连接。这样一来，有利于有效降低填料与聚合物基体间的界面热阻，可以使得热量以声子的形式在导热网络结构201中，通过晶格的振动进行传输。当导热材料前体41固化后，上述网链结构301可以形成致密的导热通路(图10中箭头表示的传输路径)，有利于热量的高效传输。
又一方面，液晶聚合物22具有较高的导热系数，例如导热系数可以大于或等于0.25W/mk，其导热系数高于无定型聚合物，从而有利于提高最终得到的导热材料的导热效率。
又一方面，在制备导热材料的过程中，采用液晶聚合物22对导热填料30表面进行原位包覆的方法提高导热材料的导热能力，相对于利用磁场、电场等诱导一维或二维导热填料取向分布，形成有序结构的方法而言，制备方法更加简单，产率高、效果明显，更适合工业化生产。
此外，与示例一相同，本示例二对导热材料中导热填料30粒径大小不做限定，图10是以导热填料的粒径大小均相同为例进行的说明。在本申请的另一些实施例中，导热材料中至少两个导热填料30粒径可以不同，技术效果同上所述，此处不再赘述。
接下来执行S102、采用导热材料前体41制作导热材料。
与示例一相同，本示例二中，在一些实施例中，可以将导热材料前体41倒入模具中，进行真空脱泡以及固化或半固化处理，得到导热材料。该导热材料可以作为上述导热块体，用于制备上述热界面材料10、底部填充料13、塑封料14、塑料盖板15以及导热胶16。
或者，本示例二中，在另一些实施例中，将导热材料前体与有机溶剂混合，并通过调节溶液固含量得到导热材料。在将导热材料前体41与有机溶剂混合，并通过调节溶液固含量得到用于制备半固化片18的预浸渍料。该半固化片18以及CCL19的方法同上所述，此处不再赘述。
以下结合不同材料的导热填料30、液晶聚合物22以及基体聚合物40，对上述S101、S102以及利用导热材料制备半固化片18和CCL19的方式进行详细的举例说明。
实施方式五
本实施例方式中，导热填料30的材料为氧化铝(Al 2O 3)和氮化硼(BN)中的至少一种，液晶聚合物22的材料为四甲基联苯环氧树脂(导热系数为0.27W/mk)，基体聚合物40的材料为聚苯醚。在此情况下，导热材料前体41的制作方法可以包括上述S201和S202。以下结合上述导热填料30、液晶聚合物22以及基体聚合物40的具体材料，对上述S101、S102以及半固化片18和CCL19的方式进行举例说明。
具体的，执行S101以得到具有如图10所示的网链结构301的导热材料前体41。例如，依次在调胶瓶中加入适量的有机溶剂(丁酮和二甲苯)、导热填料30(Al 2O 3和BN的至少一种)、作为液晶聚合物22的四甲基联苯环氧、环氧树脂固化剂4,4’-二氨基二苯甲烷(DDM)和固化促进剂2MZ，机械搅拌1小时。
然后，加入作为基体聚合物40的聚苯醚，以及固化剂三烯丙基异氰酸酯(TAIC)和催化剂过氧化二异丙苯(DCP)，继续机械搅拌2h完全溶解分散后，配置成树脂组合物胶液作为上述导热材料前体41。各组成的配比如表5所示。
接下来，在一些实施例中，可以执行上述S102以制作导热材料，该导热材料的制备过程与示例一中的实施方式一相同，此处不再赘述。
或者，接下来，在另一些实施例中，制备半固化片18和CCL19。例如，将执行S101得到的导热材料前体41调配成固含量为75％的均匀预浸渍料。接下来，将该预浸料涂布在E型玻璃布(规格2116，单重104g/m 2)上，并在170℃烘箱中烘烤10分钟后制得树脂含量为80％的半固化片18。
然后，将制得的树脂含量为80％的半固化片18的上、下表面各放一张铜箔，置于真空热压机中于2MPa压力和200℃温度下，压制得到CCL19。在此情况下，制得的CCL19中介质层(由半固化片18固化后形成)的导热系数如表5所示。
表5
Figure PCTCN2022082479-appb-000017
表5中，测试项1、测试项2、以及测试项3均是采用添加有液晶聚合物22(四甲基联苯环氧树脂)的导热材料，制备CCL19为例进行的说明。由表5可知，测试项1、测试项2、以及测试项3的不同之处在于，加入的导热填料30的材料不同。测试项1的导热填料30为氧化铝(Al 2O 3)，制备的CCL19中介质层的介质导热系数最低，为1.42W/mk。测试项2的导热填料30为导热系数较高的氮化硼(BN)，制备的CCL19中介质层的介质导热系数最高，为1.97W/mk。测试项3的导热填料30为氧化铝(Al 2O 3)和氮化硼(BN)，制备的CCL19中介质层的介质导热系数的数值位于上述两个测试 项的中间，例如为1.73W/mk。
此外，对比项1、对比项2以及对比项3均是采用未添加有液晶聚合物22的导热材料，制备CCL19为例进行的说明。其中，对比项1与测试项1中，不同粒径的填料的份数相同。但是由于测试项1是采用添加有液晶聚合物22的导热材料制备CCL19，因此采用测试项1制备CCL19中介质层的介质导热系数(为1.42W/mk)高于，采用对比项1制备CCL19中介质层的介质导热系数(0.93W/mk)。
同理，对比项2与测试项2中，不同粒径的填料的份数相同。采用测试项2制备CCL19中介质层的介质导热系数(为1.97W/mk)高于，采用对比项2制备CCL19中介质层的介质导热系数(1.35W/mk)。对比项3与测试项3中，不同粒径的填料的份数相同。采用测试项3制备CCL19中介质层的介质导热系数(为1.73W/mk)高于，采用对比项3制备CCL19中介质层的介质导热系数(1.13W/mk)。
综上所述，采用添加有液晶聚合物22的导热材料制备CCL19中介质层的介质导热系数，高于采用未添加液晶聚合物22的导热材料制备CCL19中介质层的介质导热系数。
实施方式六
本实施方式中，与实施方式五不同之处在于，液晶聚合物22的材料为多液晶单元环氧树脂(导热系数为0.5W/mk)。
与实施方式五的相同之处在于，导热填料30的材料可以为氧化铝(Al 2O 3)和氮化硼(BN)中的至少一种，基体聚合物40的材料为聚苯醚。在此情况下，导热材料前体41的制作方法可以包括上述S201和S202。以下结合上述导热填料30、液晶聚合物22以及基体聚合物40的具体材料，对上述S101、S102以及半固化片18和CCL19的方式进行举例说明。
具体的，执行S101以得到具有如图10所示的网链结构301的导热材料前体41。例如，依次在调胶瓶中加入适量的有机溶剂(丁酮和二甲苯)、导热填料30(Al 2O 3和BN的至少一种)、作为液晶聚合物22的多液晶单元环氧树脂、环氧树脂固化剂4,4’-二氨基二苯甲烷(DDM)和固化促进剂2MZ，机械搅拌1小时。然后，加入作为基体聚合物40的聚苯醚，以及固化剂三烯丙基异氰酸酯(TAIC)和催化剂过氧化二异丙苯(DCP)，继续机械搅拌2h完全溶解分散后，配置成树脂组合物胶液作为上述导热材料前体41。各组成的配比如表6所示。
接下来，执行上述S102以制作导热材料，或者采用S101制备的导热材料前体41制作半固化片18和CCL19的制作过程与实施方式五相同，此处不再赘述。制得的CCL19中介质层的导热系数如表6所示。
表6
Figure PCTCN2022082479-appb-000018
需要说明的是，表6中测试项1、测试项2、以及测试项3是将实施方式五中的液晶聚合物22由四甲基联苯环氧树脂，替换为实施方式六中的多液晶单元环氧树脂，其他组分与表5中测试项1、测试项2、以及测试项3的配方(或组分)相同，因此表6 中不再一一体现。
由上述可知，本实施方式六中，在制作具有如图10所示的网链结构301的导热材料前体41的过程中，采用了导热系数更高的多液晶单元环氧树脂(导热系数为0.5W/mk)作为液晶聚合物22的材料，从而使得获得的液晶聚合物原位包覆导热填料网络所构筑的导热材料的导热系数更高。
因此，由表6和表5可知，本实施方式六中，采用测试项1、测试项2、测试项3的配方制备的CCL19中介质层的介质导热系数(分别为1.67W/mk、2.32W/mk、1.85W/mk)，分别高于实施方式五中，采用测试项1、测试项2、测试项3的配方制备的CCL19中介质层的介质导热系数(分别为1.42W/mk、1.97W/mk、1.73W/mk)。
实施方式七
本实施方式中，与实施方式五不同之处在于，基体聚合物40的材料为聚丁二烯(碳氢树脂)。与实施方式五的相同之处在于，液晶聚合物22的材料为四甲基联苯环氧树脂(导热系数为0.27W/mk)。导热填料30的材料可以为氧化铝(Al 2O 3)和氮化硼(BN)中的至少一种。在此情况下，导热材料前体41的制作方法可以包括上述S201和S202。以下结合上述导热填料30、液晶聚合物22以及基体聚合物40的具体材料，对上述S101、S102以及半固化片18和CCL19的方式进行举例说明。
具体的，执行S101以得到具有如图10所示的网链结构301的导热材料前体41。例如，依次在调胶瓶中加入适量的有机溶剂(丁酮和二甲苯)、导热填料30(Al 2O 3和BN的至少一种)、作为液晶聚合物22的四甲基联苯环氧树脂、环氧树脂固化剂4,4’-二氨基二苯甲烷(DDM)和固化促进剂2MZ，机械搅拌1小时。
然后，加入作为基体聚合物40的聚丁二烯(碳氢树脂)，以及固化剂三烯丙基异氰酸酯(TAIC)和催化剂过氧化二异丙苯(DCP)，继续机械搅拌2h完全溶解分散后，配置成树脂组合物胶液作为上述导热材料前体41。各组成的配比如表7所示。
接下来，执行上述S102以制作导热材料，或者采用S101制备的导热材料前体41制作半固化片18和CCL19的制作过程与实施方式五相同，此处不再赘述。制得的CCL19中介质层的导热系数如表7所示。
表7
Figure PCTCN2022082479-appb-000019
需要说明的是，表7中测试项1、测试项2、以及测试项3是将实施方式五中的基体聚合物40由聚苯醚，替换为实施方式七中的聚丁二烯(碳氢树脂)，其他组分与表5中测试项1、测试项2、以及测试项3的配方(或组分)相同。并且，表7中对比项1、对比项2以及对比项3是将实施方式五中的基体聚合物40由聚苯醚，替换为实施方式七中的聚丁二烯(碳氢树脂)，其他组分与表5中对比项1、对比项2以及对比项3的配方(或组分)相同。因此表7中不再一一体现。
由表7，本实施方式七中通过将基体聚合物40由聚苯醚换成了聚丁二烯后，采用测试项1、测试项2、测试项3的配方制备的CCL19中介质层的介质导热系数(分别为1.53W/mk、2.12W/mk、1.84W/mk)。采用对比项1、对比项2以及对比项3的配 方制备的CCL19中介质层的介质导热系数(分别为1.01W/mk、1.41W/mk、1.25W/mk)。
此外，由上述可知，本实施方式六中，在制作具有网链结构301的导热材料前体41的过程中，采用了导热系数更高的多液晶单元环氧树脂(导热系数为0.5W/mk)作为液晶聚合物22的材料，从而使得获得的液晶聚合物原位包覆导热填料网络构筑的导热材料的导热系数更高。
因此，由表7和表6可知，本实施方式七中，采用测试项1、测试项2、测试项3的配方制备的CCL19中介质层的介质导热系数(分别为1.53W/mk、2.12W/mk、1.84W/mk)，分别略低于实施方式六中，采用测试项1、测试项2、测试项3的配方制备的CCL19中介质层的介质导热系数(分别为1.67W/mk、2.32W/mk、1.85W/mk)。
综上所述，在制作具有网链结构301的导热材料前体41的过程中，选取的导热填料30、液晶聚合物22的导热系数越高，制备的CCL19中介质层的介质导热系数越高。
以上所述，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。

Claims (22)

  1. 一种导热材料，其特征在于，包括：基体聚合物、固化剂以及改性导热填料，
    所述改性导热填料包括导热填料以及接枝包覆于所述导热填料表面的液晶聚合物；所述液晶聚合物用于对所述导热填料进行改性；
    所述液晶聚合物与所述基体聚合物之间通过所述固化剂形成化学键连接。
  2. 根据权利要求1所述的导热材料，其特征在于，
    所述液晶聚合物包括液晶环氧树脂；其中，所述液晶环氧树脂包括联苯型液晶环氧树脂、芳酯型液晶环氧树脂、α-甲基苯乙烯型液晶环氧树脂、偶氮型液晶环氧树脂、亚甲胺型液晶环氧树脂、萘型液晶环氧树脂、苯并菲型液晶环氧树脂中的至少一种。
  3. 根据权利要求2所述的导热材料，其特征在于，
    所述液晶聚合物还包括功能基团，所述功能基团包括环氧基、烯基、炔基、氰酸酯基、异氰酸酯基、苯并环丁烯基中的至少一种；
    所述液晶聚合物包括液晶单元，所述液晶单元包括联苯结构、芳酯结构、α-甲基苯乙烯结构、偶氮结构、亚甲胺结构、联萘结构、苯并菲结构中的至少一种。
  4. 根据权利要求1-3任一项所述的导热材料，其特征在于，
    所述导热填料包括纳米级或微米级无机导热材料；构成所述无机导热材料包括二氧化硅、氧化铝、氮化铝、氮化硼、碳化硅、金刚石中的至少一种。
  5. 根据权利要求4所述的导热材料，其特征在于，
    多个所述改性导热填料堆积形成导热网络结构，且相接触的多个所述改性导热填料的液晶聚合物通过所述固化剂形成化学键连接。
  6. 根据权利要求5所述的导热材料，其特征在于，所述导热材料中至少两个所述导热填料的粒径不同。
  7. 一种用于制作如权利要求1-6任一项所述的导热材料的方法，其特征在于，
    将所述导热填料分散于具有液晶聚合物的溶液中，得到导热填料分散液；
    对所述导热填料分散液进行加热回流反应、过滤、洗涤、干燥后，进行研磨处理得到所述改性导热填料；
    将所述改性导热填料分散于具有基体聚合物的溶液中，得到导热材料前体；
    将所述导热材料前体倒入模具中，进行真空脱泡以及固化或半固化处理，得到所述导热材料，或者，将所述导热材料前体与有机溶剂混合，并通过调节溶液固含量得到预浸渍料，将所述预浸渍料涂布于基材上，并烘烤后形成包覆所述基材的所述导热材料。
  8. 根据权利要求7所述的方法，其特征在于，所述将所述导热填料分散于具有液晶聚合物的溶液中之前，所述方法还包括：
    将所述导热填料加入具有偶联剂的溶液中，进行偶联剂处理；
    将经过所述偶联剂处理后的溶液进行过滤、洗涤并干燥。
  9. 根据权利要求7或8所述的方法，其特征在于，所述将所述导热填料分散于具有液晶聚合物的溶液中，得到导热填料分散液包括：
    将所述导热填料加入有机溶剂中，并进行分散；
    对分散后的溶液进行搅拌和通入惰性气体，加入催化剂和所述液晶聚合物，并进 行加热回流反应，得到所述导热填料分散液。
  10. 根据权利要求7或8所述的方法，其特征在于，所述将所述导热填料分散于具有液晶聚合物的溶液中，得到导热填料分散液包括：
    将导热填料以及液晶聚合物加入有机溶剂中，并进行分散；
    对分散后的溶液进行搅拌和通入惰性气体，加入催化剂，并进行加热回流反应，得到所述导热填料分散液。
  11. 一种导热材料，其特征在于，包括：
    基体聚合物；
    液晶聚合物；
    固化剂；
    导热填料，填充于所述基体聚合物内；所述导热填料表面的至少一部分包覆有所述液晶聚合物，所述液晶聚合物与所述基体聚合物之间通过所述固化剂形成化学键连接；
    其中，所述液晶聚合物与所述导热填料的亲和性，大于所述基体聚合物与所述导热填料的亲和性。
  12. 根据权利要求11所述的导热材料，其特征在于，
    多个所述导热填料堆积形成的导热网络结构，所述液晶聚合物包覆于所述导热网络结构的表面形成网链结构；相接触的多个所述网链结构的液晶聚合物通过所述固化剂形成化学键连接。
  13. 根据权利要求11或12所述的导热材料，其特征在于，
    所述液晶聚合物包括液晶环氧树脂；其中，所述液晶环氧树脂包括联苯型液晶环氧树脂、芳酯型液晶环氧树脂、α-甲基苯乙烯型液晶环氧树脂、偶氮型液晶环氧树脂、亚甲胺型液晶环氧树脂、萘型液晶环氧树脂、苯并菲型液晶环氧树脂中的至少一种。
  14. 根据权利要求13所述的导热材料，其特征在于，
    所述液晶聚合物包括功能基团，所述功能基团包括环氧基、烯基、炔基、氰酸酯基、异氰酸酯基、苯并环丁烯基中的至少一种；
    所述液晶聚合物包括液晶单元，所述液晶单元包括联苯结构、芳酯结构、α-甲基苯乙烯结构、偶氮结构、亚甲胺结构、联萘结构、苯并菲结构中的至少一种。
  15. 根据权利要求11所述的导热材料，其特征在于，
    所述基体聚合物包括：聚苯醚、碳氢树脂、环氧树脂、氰酸酯、双马来酰亚胺树脂、有机硅树脂、聚酰亚胺中的至少一种。
  16. 根据权利要求11所述的导热材料，其特征在于，所述液晶聚合物的重量比占所述导热材料中聚合物总量的3～30wt％。
  17. 根据权利要求11所述的导热材料，其特征在于，
    所述导热填料包括纳米级或微米级无机导热材料；构成所述无机导热材料包括二氧化硅、氧化铝、氮化铝、氮化硼、碳化硅、金刚石中的至少一种。
  18. 根据权利要求12所述的导热材料，其特征在于，所述导热材料中至少两个所述导热填料的粒径不同。
  19. 一种用于制作如权利要求11-18任一项所述的导热材料的方法，其特征在于，
    将所述导热填料、所述液晶聚合物加入有机溶剂中，并进行搅拌；
    在搅拌后，加入基体聚合物、固化剂和固化促进剂，继续搅拌得到导热材料前体；其中，所述液晶聚合物与所述导热填料的亲和性，大于所述基体聚合物与所述导热填料的亲和性；
    将所述导热材料前体倒入模具中，进行真空脱泡以及固化或半固化处理，得到所述导热材料，或者，将所述导热材料前体与有机溶剂混合，并通过调节溶液固含量得到预浸渍料，将所述预浸渍料涂布于基材上，并烘烤后形成包覆所述基材的所述导热材料。
  20. 一种半固化片，其特征在于，包括基材，以及如权利要求1-6任一项所述的导热材料，或者如权利要求11-18任一项所述的导热材料，所述导热材料包覆所述基材。
  21. 一种层压板，其特征在于，包括铜箔以及如权利要求20所述的半固化片；所述铜箔覆盖所述半固化片的表面。
  22. 一种电路板，其特征在于，包括层叠设置的半固化片和层压板；
    所半固化片为如权利要求20所述的半固化片，或者，所述层压板为如权利要求21所述的层压板。
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