Heat dissipating material, composition containing same, and method for producing same

Abstract

A heat dissipation material is provided having a filler including secondary particles formed by agglomeration of primary particles, the filler in a polymer resin matrix forming a thermal interface layer for thermal conduction between a heat generating part and a heat absorbing part.

Description

[Technical Field]

[0001] The present application relates to a heat dissipation material, a composition containing the same, and a manufacturing method thereof, and more particularly to a heat dissipation material containing secondary particles formed by aggregation of a plurality of primary particles, a composition containing the same, and a manufacturing method thereof.

[0002] The present invention has been derived as a result of the following research and development projects.

[0003] -Project unique number: 1711155761 -Project number: 2020M3H4A3106409 - Department name: Ministry of Science, ICT and Communication -Name of the project management (specialized) organization: Korea Research Foundation -Research Project Name: Nano-Materials Technology Development (R&D) -Research title: Development of high thermal conductivity filler material for multifunctional bonding materials for micro LEDs -Contribution rate: 1 / 1 -Project implementation organization: Korea Ceramic Technology Institute -Research period: 2022-01-01~2022-12-31 -Total research period: 2020-08-24~2024-12-31 [Background technology]

[0004] As the size of various electronic elements, including components that consume high power and generate a lot of heat, such as micro LEDs and power devices, becomes smaller, dissipating the generated heat to the outside and maintaining temperature has become an important issue.

[0005] To efficiently dissipate heat, heat dissipation technologies such as high-heat dissipation circuit boards based on metal substrates with excellent thermal conductivity are being applied, but there are limitations to the thermal conductivity of the bonding layer, which is a polymer base that connects heat-generating electronic elements and components with external heat dissipation components.

[0006] In order to achieve high thermal conductivity in polymer composite materials, a large amount of filler must be added, but in this case, processing conditions become strict and problems arise in that the physical properties of the product are impaired.

[0007] Thermal conductivity problems occur in a variety of applications, including polymer-based bonding, thermal interface materials (TIM), sealing, and underfill. To solve these problems, composites containing fillers with high thermal conductivity are used.

[0008] The size and fraction of the filler to be inserted may need to be fine-tuned depending on the application field of the composite. For example, in applications such as 3D NAND memory and bonding of light-emitting elements for displays, composites of 10 μm or less, preferably on the order of 1 to 5 μm, are used to reduce weight and thickness, and the filler present inside must be 10 μm or less, preferably on the order of 1 to 5 μm.

[0009] The main properties of the fillers used in composites include high thermal conductivity, shape (a shape that does not interfere with the dispersibility and flow of the polymer), and dispersion within the polymer resin, and various heat-dissipating materials have been developed to improve these properties.

[0010] For example, Korean Patent Publication No. 10-2021-0073257 discloses a method for producing a thermally conductive polymer composite, in which a mixture of thermally conductive carbon material powder and a mixed solvent consisting of saturated fatty acid and C1 to C4 alcohol is placed in a wet pelletizer to obtain a master arrangement of a granule-type thermally conductive carbon material, 30 to 60% by weight of the master arrangement of the granule-type thermally conductive carbon material and 40 to 70% by weight of a thermoplastic resin are mixed, and the extrusion molding is pelletized using a press.

[0011] Furthermore, for example, Korean Patent No. 10-1797671 discloses a method for manufacturing a silver-carbon nanocomposite, which includes a first step of mixing graphite powder and silver powder in a predetermined ratio to prepare a mixed powder, and a second step of irradiating the mixed powder with microwaves in a predetermined gas atmosphere to form a silver-carbon nanocomposite, and further includes a step of pretreating the graphite powder with one method selected from microwave treatment and plasma treatment before the first step. In the second step, the graphite powder is exfoliated by irradiating microwaves to form graphene, and the graphene reacts with the silver powder to form a silver-carbon nanocomposite with a structure in which silver particles grow into nanoparticles on the surface of the graphene. In the second step, the mixed powder is self-heated at a temperature of 400 to 1700°C by the microwaves irradiated to form the silver-carbon nanocomposite. The silver-carbon nanocomposite has a thermal diffusivity of 140 to 170 mm / s and a Vickers hardness of 140 to 170 mm / s. A method for producing a silver-carbon nanocomposite for heat dissipation material is disclosed, characterized in that the hardness is 70 to 140 HV. Summary of the Invention [Problem to be solved by the invention]

[0012] SUMMARY OF THE INVENTION An object of the present invention is to provide a heat dissipating material, a composition containing the same, and a method for producing the same.

[0013] Another object of the present invention is to provide a heat dissipating material having improved dispersibility and flowability in a polymer resin, and a method for manufacturing the same.

[0014] It is still another object of the present invention to provide a heat dissipating material with improved sphericity and a method for manufacturing the same.

[0015] Another object of the present invention is to provide a heat dissipation material with an increased heat transfer path and a method for manufacturing the same.

[0016] A further object of the present invention is to provide a heat dissipating material and a method for manufacturing the same that are simple in manufacturing process and easy to mass-produce.

[0017] It is still another object of the present invention to provide a heat dissipating material having secondary particles formed by aggregation of primary particles, and a method for manufacturing the same.

[0018] It is yet another object of the present invention to provide a heat dissipating material having agglomerated secondary particles using functionalized primary particles, and a method for manufacturing the same.

[0019] It is still another object of the present invention to provide a heat dissipating material capable of improving the filling rate and a method for manufacturing the same.

[0020] It is yet another object of the present invention to provide a heat dissipation material having improved thermal conductivity and a method for manufacturing the same.

[0021] It is yet another object of the present invention to provide a method for manufacturing a heat dissipating material that reduces the sintering temperature.

[0022] The object of the present invention is not limited to the above. [Means for solving the problem]

[0023] To achieve the above object, the present invention provides a method for manufacturing a heat dissipating material.

[0024] The method for manufacturing the heat dissipating material includes the steps of preparing primary particles, mixing the primary particles, a binder, a dispersant, and a solvent to prepare a dispersion solution, adding and dissolving a boron source and a nitrogen source in the dispersion solution to prepare a base source, spraying the base source to prepare droplets, drying the droplets to prepare preliminary secondary particles including primary agglomerated particles formed by agglomerating a plurality of the primary particles and intermediate particles formed by reacting the boron source and the nitrogen source, sintering the preliminary secondary particles to prepare secondary particles, and mixing the plurality of secondary particles with a polymer resin to prepare the heat dissipating material, and the solvent may be pure water, ultrapure water, chloroform, chlorobenzene, acetic acid, acetone, acetonitrile, aniline, benzene, benzonitrile, benzyl alcohol, or the like. Alcohol, Bromobenzene, Bromoform, 1-butanol, 2-butanol, Carbon disulfide, Carbon tetrachloride, Cyclohexane, Cyclohexanone, Decalin, Dibromomethane, Diethylene glycol, Diethylene glycol ether, Diethyl ether, Dimethoxymethane, N,N-Dimethylformamide, Ethanol, Ethylamine, Ethylbenzene, Ethylene glycol ether, Ethylene glycol, Ethylene oxideoxide, formaldehyde, formic acid, glycerol, heptane, hexane, iodobenzene, mesitylene, methanol, methoxybenzene, methylamine, methylene bromide, methylene chloride, methylpyridine, morpholine, naphthalene, nitrobenzene, nitromethane, octane, pentane, pentyl alcohol alcohol, phenol, 1-propanol, 2-propanol, pyridine, pyrrole, pyrrolidine, quinoline, 1,1,2,2-tetrachloroethane, tetrachloroethylene, tetrahydrofuran, tetralin, tetramethylethylenediamine Tetramethylethylenediamine, thiophene, toluene, 1,2,4-trichlorobenzene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethene, triethylamine, triethylene glycol dimethyl etherThe solvent contains at least one of 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, and methyl pyrrolidone.

[0025] In the step of preparing the base source, the ratio of the boron source to the nitrogen source added to the dispersion solution is controlled to be 7:1 or more and 14:1 or less.

[0026] The secondary particles are produced by sintering the preliminary secondary particles at a temperature of 1100°C or higher and lower than 1500°C.

[0027] In the process of producing the secondary particles, the preliminary secondary particles are sintered, so that the intermediate particles are formed to have the same phase as the primary agglomerated particles.

[0028] Furthermore, after the step of preparing the primary particles and before the step of producing the dispersion solution, the method includes a step of surface-treating the primary particles to replace nitrogen groups present on the surfaces of the primary particles with first functional groups.

[0029] To achieve the above object, the present invention provides a method for manufacturing a thermal interface layer.

[0030] The method for manufacturing the thermal interface layer includes the steps of: preparing the heat dissipation material manufactured as described above; and providing the heat dissipation material to manufacture a thermal interface layer using the heat dissipation material, applying pressure to compress a plurality of the secondary particles with a load that exceeds the compressive strength of the secondary particles.

[0031] At least some of the secondary particles are broken down and divided into pieces, and the secondary particles that do not break down and the pieces coexist by mixing with each other in the thermal interface layer.

[0032] To achieve the above object, the present invention provides a heat dissipation material.

[0033] A heat dissipation material having a filler including secondary particles formed by aggregation of primary particles, the filler forming a thermal interface layer for thermal conduction between a heat generating part and a heat absorbing part, the filler including at least one of boron nitride (BN), carbon (C), silicon carbide (SiC), diamond, beryllium oxide (BeO), boron phosphide (BP), aluminum nitride (AlN), beryllium sulfide (BeS), boron arsenide (BAs), silicon (Si), gallium nitride (GaN), aluminum phosphide (AlP), or gallium phosphide (GaP), and the primary particles are nanoparticles, nanotubes, or the like. The term "nanotube," "nanoflake," "nanoneedle," "nanofiber," "nanodot," "nanosheet," "nanoribbon," "nanoplate," "nanosphere," "nanohorn," "nanocone," or "nanoscroll" includes having at least one shape selected from the group consisting of nanotube, nanoflake, nanoflake, nanoneedle, nanofiber, nanodot, nanosheet, nanoribbon, nanoplate, nanosphere, nanohorn, nanocone, and nanoscroll.

[0034] The secondary particles include primary aggregate particles formed by aggregating a plurality of primary particles, and intermediate particles disposed between the plurality of primary aggregate particles.

[0035] In the ninth item, the primary particles contain boron nitride having a hexagonal crystal structure, and the primary aggregate particles are aggregates of multiple boron nitride particles having a hexagonal crystal structure and have a spherical shape.

[0036] The intermediate particles have the same phase as the primary aggregate particles and are spherical in shape.

[0037] The secondary particles have a reduced BET specific surface area as the content of the intermediate particles increases compared to the primary particles.

[0038] In XRD analysis of the secondary particles, the fraction of secondary phases and heterogeneous phases is 1% or less.

[0039] When the secondary particles are dispersed in water and subjected to ultrasonic treatment at 20 KHz and 200 W, the maximum particle size peak is maintained at more than 80%.

[0040] To achieve the above object, the present invention provides a heat-dissipating composition.

[0041] The heat dissipation composition includes a polymer resin matrix and a first filler mixed with the polymer resin matrix, the first filler including secondary particles formed by agglomeration of a plurality of primary particles, the polymer resin matrix including at least one of a thermoplastic resin and a thermosetting resin, and the first filler is a heat dissipation material selected from the group consisting of boron nitride (BN), carbon (C), silicon carbide (SiC), diamond, beryllium oxide (BeO), boron phosphide (BP), aluminum nitride (AlN), beryllium sulfide (BeS), boron arsenide (BAs), silicon (Si), gallium nitride (GaN), aluminum phosphide (AlP), and gallium phosphide. phosphide, GaP), The primary particles have at least one shape of nanoparticles, nanotubes, nanoflakes, nanoneedles, nanofibers, nanodots, nanosheets, nanoribbons, nanoplates, nanospheres, nanohorns, nanocones, or nanoscrolls, and the polymer resin is selected from the group consisting of epoxy resin, urethane resin, polyimide resin nylon, polyisoprene, polydicyclopentadiene, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, silicon, polyketone, aramid, cellulose, polyimide, rayon, polymethyl methacrylate, polyvinylidene chloride, and polyvinylidene fluoride. fluoride, polyurethane, polyisobutylene, polychloroprene, polybutadiene, polypropylene, polyvinyl chloride, polyvinyl acetate, polystyrene, polyester, polyvinyl pyrrolidone, polycyanoacrylate, polyacrylonitrile, polyamide, polyarylene ethynylene, polyphenylene ethynyleneethynylene, polythiophene, polyaniline, polypyrrole, polybutylene terephthalate, polyethylene terephthalate, aromatic polyamide, polyamide, polycarbonate, polystyrene, polyphenylene sulfide, polysulfone, polyethersulfone, polyetherimide, polyetheretherketone, polyarylate, polymethylmethacrylate, polyvinyl alcohol The material contains at least one of poly(acrylonitrile-butadiene-styrene), polypropylene, polyethylene, poly(acrylonitrile-butadiene-styrene), and poly(styrene-butadiene-styrene).

[0042] The secondary particles include primary agglomerated particles formed by agglomerating a plurality of primary particles, and intermediate particles disposed between the plurality of primary agglomerated particles.

[0043] The size of the secondary particles is 1 to 10 μm, and the BET specific surface area of ​​the secondary particles is 20 m 2 / g.

[0044] The first filler is contained in an amount of 10 to 80 vol %.

[0045] Furthermore, in addition to the first filler, a second filler is included, and the second filler includes at least one of carbon, carbon black, CNT, graphite, aluminum flakes, magnesium oxide, aluminum nitride, copper, boric anhydride, magnesium carbonate, zinc oxide, silicon oxide, aluminum oxide, stainless steel, silicon carbide, yttrium (III) oxide, boron oxide, and zirconium oxide. [Effects of the Invention]

[0046] According to the present invention, a dispersion solution is prepared by mixing primary particles, a binder, a dispersant, and a solvent, a boron source and a nitrogen source are added to the dispersion solution and dissolved to prepare a base source, the base source is sprayed to prepare droplets, the droplets are dried to prepare primary agglomerated particles in which a plurality of the primary particles are agglomerated, and preliminary secondary particles including intermediate particles in which the boron source and the nitrogen source are reacted, and the preliminary secondary particles are sintered to prepare secondary particles.

[0047] Before preparing the base source, first functional groups are attached to the surfaces of the primary particles, and due to the attachment of the first functional groups, the primary particles have a high degree of dispersion in the source solution, which not only improves the sphericity of the secondary particles prepared using droplets of the source solution, but also promotes sintering of the secondary particles.

[0048] In addition, the sphericity of the secondary particles is improved, and the secondary particles have high flowability and dispersion in the polymer resin, thereby improving the filling rate of the secondary particles in the polymer resin matrix.

[0049] Furthermore, the intermediate particles can reduce the sintering temperature for producing the secondary particles.

[0050] In addition, during the process of manufacturing the thermal interface layer using the secondary particles, the secondary particles disintegrate, and thus, the non-disintegrated secondary particles and multiple pieces generated by the disintegration of the secondary particles coexist in the thermal interface layer, thereby expanding the heat transfer path, improving the filling rate in the thermal interface layer, and preventing damage to the interface of the device due to contact with the secondary particles. [Brief explanation of the drawings]

[0051] [Figure 1] FIG. 1 is a sequence diagram for explaining a method for manufacturing a heat dissipation material according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating the surface treatment process of the heat dissipation material according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a diagram illustrating the surface treatment process of the heat dissipation material according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram for explaining a method for manufacturing the heat dissipation material according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a diagram illustrating a process for manufacturing a thermal interface layer using the heat dissipation material manufactured by the method for manufacturing a heat dissipation material according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a diagram illustrating a process for manufacturing a thermal interface layer using the heat dissipation material manufactured by the method for manufacturing a heat dissipation material according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a diagram illustrating a process for manufacturing a thermal interface layer using a heat dissipation material manufactured by a method for manufacturing a heat dissipation material according to a modified example of the first embodiment of the present invention. [Figure 8] FIG. 8 is a sequence diagram illustrating a method for manufacturing a heat dissipation material according to a second embodiment of the present invention. [Figure 9] FIG. 9 is a diagram illustrating a method for manufacturing a heat dissipation material according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a diagram illustrating a method for manufacturing a heat dissipation material according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a SEM photograph of secondary particles produced according to Experimental Example 1 of the present invention. [Figure 12] FIG. 12 is a SEM photograph of secondary particles produced according to Experimental Example 1 of the present invention. [Figure 13] FIG. 13 is a SEM photograph of secondary particles produced according to Experimental Example 1 of the present invention. [Figure 14] FIG. 14 is a photograph showing the contact angle measured by the surface treatment of the secondary particles produced in Experimental Example 1 of the present invention. [Figure 15] FIG. 15 is a SEM photograph of secondary particles produced in Experimental Examples 2-1 to 2-6 of the present invention. [Figure 16] FIG. 16 is a SEM photograph of secondary particles produced according to Experimental Examples 3-1 to 3-4 of the present invention. [Figure 17] FIG. 17 is a SEM photograph of secondary particles produced according to Experimental Examples 4-1 to 4-3 of the present invention. [Figure 18] FIG. 18 shows an SEM image and an XRD analysis graph of secondary particles produced according to Experimental Example 1 of the present invention. [Figure 19] FIG. 19 shows an SEM image and an XRD analysis graph of secondary particles produced according to Experimental Example 1 of the present invention. [Figure 20] FIG. 20 is a SEM photograph of the preliminary secondary particles produced according to Experimental Example 1 of the present invention after ultrasonic dispersion. [Figure 21] FIG. 21 is a graph showing the particle size distribution of the secondary particles prepared according to Experimental Example 1 of the present invention after ultrasonic dispersion. [Figure 22] FIG. 22 is a SEM photograph of secondary particles produced according to Experimental Example 5 of the present invention. [Figure 23] FIG. 23 is an SEM photograph showing the crystal shape of a common melamine diborate. [Figure 24]FIG. 24 is a SEM photograph of secondary particles according to Experimental Example 5, which were produced by varying the mixing ratio of boric acid and melamine. [Figure 25] FIG. 25 is a SEM photograph of secondary particles according to Experimental Example 5, which were produced by varying the mixing ratio of boric acid and melamine. [Figure 26] FIG. 26 is a SEM photograph of boric acid formed in the process of producing secondary particles according to Experimental Example 5 of the present invention. [Figure 27] FIG. 27 is a SEM photograph of melamine formed during the process of producing secondary particles according to Experimental Example 5 of the present invention. [Figure 28] FIG. 28 is a diagram illustrating XRD characteristics depending on the heat treatment temperature of intermediate particles formed in the production process of secondary particles according to Experimental Example 6 of the present invention. [Figure 29] FIG. 29 is a diagram for explaining the XRD characteristics of secondary particles according to Experimental Example 6 of the present invention. [Figure 30] FIG. 30 is a diagram illustrating the BET specific surface area of ​​secondary particles according to Experimental Example 6 of the present invention. [Figure 31] FIG. 31 is a diagram for explaining the pore volume of secondary particles according to Experimental Example 6 of the present invention. [Figure 32] FIG. 32 is a diagram illustrating the PSA characteristics of secondary particles against ultrasonic impact according to Experimental Example 6 of the present invention. [Figure 33] FIG. 33 is a diagram illustrating the PSA characteristics of secondary particles against ultrasonic impact according to Experimental Example 6 of the present invention. [Figure 34] FIG. 34 is a diagram illustrating the PSA characteristics of secondary particles against ultrasonic impact according to Experimental Example 6 of the present invention. [Figure 35] FIG. 35 is a diagram illustrating the PSA characteristics of secondary particles against ultrasonic impact according to Experimental Example 6 of the present invention. [Figure 36] FIG. 36 is a diagram illustrating viscosity characteristics when secondary particles according to Experimental Example 6 of the present invention are dispersed in epoxy resin. [Figure 37]FIG. 37 is an SEM photograph showing the secondary particles dispersed in epoxy resin according to Experimental Example 6 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0052] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical concept of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments described herein are provided so that the disclosure will be thorough and complete, and will fully convey the concept of the present invention to those skilled in the art.

[0053] In this specification, when a component is described as being on another component, it means that the component is directly formed on the other component, or a third component may be interposed between them. Also, in the drawings, the shapes and sizes are exaggerated for the purpose of effectively explaining the technical contents.

[0054] Furthermore, in various embodiments of this specification, terms such as "first," "second," and "third" are used to describe various components, but these components should not be limited by such terms. These terms are used merely to distinguish one component from another. Thus, what is referred to as a "first" component in one embodiment may also be referred to as a "second" component in another embodiment. Each embodiment described and exemplified herein also includes its complementary embodiment. Furthermore, in this specification, "and / or" is used to mean that at least one of the preceding and following components is included.

[0055] In this specification, the singular expression includes the plural expression unless the context clearly dictates otherwise. Furthermore, the terms "comprise" or "have" are intended to specify the presence of features, numbers, steps, components, or combinations thereof described in the specification, and should not be understood to exclude the presence or possible addition of one or more other features, numbers, steps, components, or combinations thereof. Furthermore, in this specification, the term "coupled" is used to mean both indirectly and directly coupling multiple components.

[0056] In addition, in the following description of the present invention, if a detailed description of related publicly known functions or configurations is deemed to obscure the gist of the present invention, the detailed description will be omitted.

[0057] Figure 1 is a sequence diagram for explaining the manufacturing method of the heat dissipation material according to Example 1 of the present invention, Figures 2 and 3 are diagrams for explaining the surface treatment process of the heat dissipation material according to Example 1 of the present invention, and Figure 4 is a diagram for explaining the manufacturing method of the heat dissipation material according to Example 1 of the present invention.

[0058] As shown in FIGS. 1 to 4, primary particles 110 are prepared (S110).

[0059] According to one embodiment, the primary particles 110 are boron nitride (BN) having a hexagonal crystal structure, or according to another embodiment, the primary particles 110 are at least one of carbon (C), silicon carbide (SiC), diamond, beryllium oxide (BeO), boron phosphide (BP), aluminum nitride (AlN), beryllium sulfide (BeS), boron arsenide (BAs), silicon (Si), gallium nitride (GaN), aluminum phosphide (AlP), or gallium phosphide (GaP).

[0060] Also, according to one embodiment, the primary particles 110 have a flake and / or plate shape, as shown in FIG.

[0061] Alternatively, according to another embodiment, the primary particles 110 have at least one shape of a nanoparticle, a nanotube, a nanoflake, a nanoneedle, a nanofiber, a nanodot, a nanosheet, a nanoribbon, a nanoplate, a nanosphere, a nanohorn, a nanocone, or a nanoscroll.

[0062] As described above, when the primary particles 110 are boron nitride having a hexagonal crystal structure, the primary particles 110 are provided in a state of being exfoliated from bulk-type boron nitride.

[0063] As will be described later, a plurality of the primary particles 110 aggregate to form secondary particles 150. In this case, the smaller the size of the primary particles 110, the more spherical the secondary particles 150 are, thereby improving the flowability and dispersibility of the secondary particles 150 in the polymer resin. On the other hand, if the size of the primary particles 110 is too small, the interfaces between the primary particles 110 act as a heat transfer resistance, resulting in a decrease in thermal conductivity.

[0064] According to an embodiment of the present invention, the size of the secondary particles 150 is 1 to 10 μm or 1 to 5 μm, and the size of the primary particles 110 in the overall direction of at least two or all three of the three axes is 1 to 10% of the size of the secondary particles 150. Specifically, for example, the size of the primary particles 110 is about 10 nm or less in thickness and about 70 nm in the plane direction, or about 30 nm or less in thickness and about 200 nm in the plane direction.

[0065] According to one embodiment, a surface treatment is performed on the primary particles 110. As described above, for example, if the primary particles 110 are made of boron nitride, a plurality of nitrogen groups (N-terminations) are provided on the surfaces of the primary particles 110 as shown in FIG. 2. In this case, the nitrogen groups on the surfaces of the primary particles 110 are substituted with first functional groups 112 through a surface treatment process. For example, the first functional groups 112 are hydroxyl groups (OH), and the process of substituting the nitrogen groups with the first functional groups 112 is performed by immersing the primary particles 110 in a basic solution (e.g., NaOH) and then drying.

[0066] Alternatively, according to another embodiment, the nitrogen groups are substituted with the first functional groups 112 (hydroxyl groups) by a method in which the primary particles 110 are heat-treated (e.g., at 1,000°C) in air, immersed in an acidic solution (e.g., sulfuric acid, nitric acid, phosphoric acid, etc.), immersed in a basic solution (e.g., NaOH, KOH, etc.), and then oxidized with an oxidizing agent (e.g., KMnO4, H2O2, etc.).

[0067] Alternatively, according to another embodiment, the first functional group 112 substituting the nitrogen group on the surface of the primary particle 110 is a hydrogen group (-H). In this case, a thiol molecule such as epoxy thiol is used instead of epoxy silane, which will be described later.

[0068] Specifically, as shown in FIG. 3, at least a portion of the nitrogen group terminals of boron nitride are substituted with the first functional groups 112 (hydroxyl groups).

[0069] If, unlike the above, the primary particles 110 are not surface-treated and a large amount of nitrogen groups are present on the surfaces of the primary particles 110, the primary particles 110 aggregate together in a source solution prepared using the primary particles 110, reducing the degree of dispersion, and therefore reducing the sphericity of the secondary particles 150 formed by the aggregation of the primary particles 110. In addition, sintering does not proceed smoothly in the subsequent sintering process.

[0070] Meanwhile, as described above, according to an embodiment of the present invention, the nitrogen groups on the surfaces of the primary particles 110 are substituted with the first functional groups 112 (e.g., hydroxyl groups) through a surface treatment process. As a result, the primary particles 110 have high dispersibility in the source solution, which increases the sphericity of the secondary particles 150 formed by agglomeration of the primary particles 110. In addition, the sintering process is accelerated by the first functional groups 112 in the subsequent sintering process.

[0071] After the surface treatment process for the primary particles 110 is completed, the primary particles 110, a binder, a dispersant, and a solvent are mixed together to prepare a source solution (S120).

[0072] For example, the binder is polyvinyl alcohol, or the binder includes at least one of polyethylene glycol (PEG), methyl cellulose (MC), polyacrylic acid (PAA), polyacrylonitrile, and polyacrylamide.

[0073] For example, the dispersant is an aqueous solution of ammonium polymethacrylate, or the dispersant is an aqueous dispersant that includes at least one of polycarboxylic acid-based dispersants (acrylic acid-based, methacrylic acid-based, copolymers), phosphates, phosphate complex salts, arylsulfonic acids, and amine-based dispersants. Specifically, the dispersant includes an inorganic dispersant containing at least one of calcium phosphate salt, magnesium salt, hydrophilic silica, hydrophobic silica, and colloidal silica; or includes a nonionic polymer dispersant containing at least one of polyoxyethylene alkyl ether, polyoxyalkylene alkylphenol ether, sorbitan fatty acid ester, polyoxyalkylene fatty acid ester, glycerin fatty acid ester, polyvinyl alcohol, alkyl cellulose, and polyvinylpyrrolidone; or includes an ionic polymer dispersant containing at least one of polyacrylamide, polyvinylamine, polyvinylamine N-oxide, polyvinylammonium salt, polydialkyldiallylammonium salt, polyacrylic acid, polystyrene sulfonic acid, polyacrylate, polysulfonate, and polyaminoalkylacrylate.

[0074] For example, the solvent is pure water or ultrapure water, or the solvent is chloroform, chlorobenzene, acetic acid, acetone, acetonitrile, aniline, benzene, benzonitrile, benzyl alcohol, bromobenzene, bromoform, 1-butanol, 2-butanol, carbon disulfide, carbon tetrachloride, cyclohexane, cyclohexanone, decalin, dibromomethane, diethylene glycol, diethylene glycol ether, diethyl ether, dimethoxymethane, N,N-dimethylformamide, ethanol, ethylamine, ethylbenzene, ethylene glycol ether, ethylene glycol, ethylene oxide, formaldehyde, formic acid, glycerol, heptane, hexane, iodobenzene, mesitylene, methanol, methoxybenzene, methylamine, methylene bromide, methylene chloride, methylpyridine, morpholine, or the like. The solvent contains at least one of phosphorus, naphthalene, nitrobenzene, nitromethane, octane, pentane, pentyl alcohol, phenol, 1-propanol, 2-propanol, pyridine, pyrrole, pyrrolidine, quinoline, 1,1,2,2-tetrachloroethane, tetrachloroethylene, tetrahydrofuran, tetralin, tetramethylethylenediamine, thiophene, toluene, 1,2,4-trichlorobenzene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, triethylamine, triethylene glycol dimethyl ether, 1,3,5-trimethylbenzene, m-xylene, o-xylene, p-xylene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, and methylpyrrolidone.

[0075] Alternatively, for example, the solvent may include at least one of alcohol esters (glycerin), polyethers, amines, sulfonic acids, or cations as a non-aqueous dispersant (solvent-based dispersant). Specifically, the solvent may include at least one of fatty acid salts, alkyl sulfonates, alpha olefin sulfonates, alkanesulfonates, alkyl benzene sulfonates, sulfosuccinate salts, alkyl sulfates, alkyl ether sulfates, alkyl ether carboxylates, alpha sulfo fatty acid methyl ester salts, methyl taurate salts, glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, fatty acid alkanolamides, or alkyl glucosides.

[0076] The content of the primary particles 110 in the source solution is 1 to 10 wt %, the content of the dispersant is 0.1 to 1 wt %, and the content of the binder is 0.1 to 5 wt %.

[0077] The ratio of the primary particles 110, the solvent, and the dispersant in the source solution may be controlled so that the zeta potential of the source solution has a maximum value.

[0078] Next, as shown in FIGS. 1 and 4, the source solution is sprayed to form droplets 130, and the droplets 130 are dried to form preliminary secondary particles 140 in which a plurality of the primary particles 110 are aggregated (S130).

[0079] The source solution is atomized into the droplets 130 using an ultrasonic vibrator, or the source solution is atomized into the droplets 130 using a spray.

[0080] A plurality of the primary particles 110 exist within the droplets 130, and the size of the preliminary secondary particles 140 can be controlled depending on the size of the droplets 130. The droplets 130 are adjusted to 10 μm or less, or 3 μm or less, and in this case, the average size of the preliminary secondary particles 140 is about 2 μm.

[0081] The preliminary secondary particles 140 are collected using a centrifuge and then washed.

[0082] 1 and 4, the preliminary secondary particles 140 are sintered to form secondary particles 150, and a plurality of the secondary particles 150 are mixed with a polymer resin to form a heat dissipating material (S140). That is, the heat dissipating material includes the secondary particles 150 formed by sintering the preliminary secondary particles 140 dispersed in a matrix containing the polymer resin.

[0083] The step of sintering the preliminary secondary particles 140 is performed by heat treating the preliminary secondary particles 140 in an inert gas atmosphere. For example, the inert gas is nitrogen gas, and the sintering is performed at a temperature of 1500°C or more for 2 hours or more.

[0084] As described above, the first functional groups 112 (e.g., hydroxyl groups) are provided on the surfaces of the primary particles 110, and thus the first functional groups 112 act as a sintering aid in the process of sintering the preliminary secondary particles 140. As a result, the preliminary secondary particles 140 are easily sintered, and as a result, the interfacial bonding between the primary particles 110 in the preliminary secondary particles 140 is improved, and the thermal conductivity of the secondary particles 150 manufactured by sintering the preliminary secondary particles 140 is improved, and the compressive strength of the secondary particles 150 is also improved.

[0085] According to one embodiment, the compressive strength of the secondary particles 150 is controlled by the temperature at which the preliminary secondary particles 140 are heat-treated. Specifically, as the temperature at which the preliminary secondary particles 140 are heat-treated increases, the compressive strength of the secondary particles 150 increases. For example, the compressive strength of the secondary particles 150 is 5 MPa or less, more specifically, 0.2 to 2 MPa.

[0086] As a result, as will be described later, in the step of manufacturing a thermal interface layer using the heat dissipation material, at least a portion of the secondary particles 150 easily collapse, thereby creating multiple heat transfer paths within the thermal interface layer, improving thermal conductivity, and minimizing damage to the heat transfer layer and heat absorption layer in contact with the thermal interface layer.

[0087] Before mixing the secondary particles 150 with the polymer resin, the steps of surface-treating the secondary particles 150 to bond second functional groups to the surfaces of the secondary particles 150 and immersing the secondary particles 150 in a polymer solution to bond polymer groups to the surfaces of the secondary particles 150 are further performed. For example, the second functional groups are hydroxyl groups and the polymer groups are epoxy groups. In this case, for example, the secondary particles 150 are immersed in a basic solution (e.g., NaOH) to bond the second functional groups to the surfaces of the secondary particles 150, and the secondary particles 150 are immersed in an epoxysilane solution to bond polymer groups to the surfaces of the secondary particles 150.

[0088] Thereafter, the plurality of secondary particles 150 are mixed with the polymer resin to manufacture the heat dissipation material.

[0089] The secondary particles 150 manufactured according to the present embodiment are fillers used with the polymer resin, and may have high sphericity (e.g., 70% or more). As a result, the secondary particles 150 have high flowability and dispersibility within the polymer resin matrix, and thus a high fraction of the secondary particles 150 is provided within the polymer resin matrix. In other words, the higher the sphericity of the secondary particles 150, the higher the flowability and dispersibility within the polymer resin matrix, and thus the fraction of the secondary particles 150 within the polymer resin matrix is ​​increased.

[0090] For example, the polymer resin may be an epoxy resin, a urethane resin, a polyimide resin, nylon, polyisoprene, polydicyclopentadiene, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, silicone, polyketone, aramid, cellulose, polyimide, rayon, polymethyl methacrylate resin, polyvinylidene chloride, polyvinylidene fluoride, polyurethane, polyisobutylene, polychloroprene, polybutadiene, polypropylene, polyvinyl chloride, polyvinyl acetate, polystyrene, polyester, polyvinylpyrrolidone, polycyanoacrylate, polyacrylonitrile, polyamide The polymerizable polymer contains at least one of the following: polyarylene ethynylene, polyphenylene ethynylene, polythiophene, polyanylene, polypyrrole, polybutylene terephthalate, polyethylene terephthalate, aromatic polyamide, polyamide, polycarbonate, polystyrene, polyphenylene sulfide, polysulfone, polyether sulfone, polyether imide, polyether ether ketone, polyarylate, polymethyl methyl acrylate, polyvinyl alcohol, polypropylene, polyethylene, polyacrylonitrile butadiene styrene copolymer, and polystyrene butadiene styrene copolymer.

[0091] The secondary particles 150 have a particle size distribution of 1 to 10 μm, with one maximum peak at 1 to 5 μm.

[0092] Furthermore, the fraction of the secondary phase and the foreign material phase is 1% or less in an XRD analysis of the secondary particles 150. For example, when the primary particles 110 are hexagonal boron nitride, the secondary phase is at least one of cubic boron nitride, rhombohedral boron nitride, and wurtzite boron nitride, and the foreign material is at least one of boric anhydride, magnesium carbonate, zinc oxide, silicon oxide, and aluminum oxide.

[0093] In other words, XRD analysis of the secondary particles 150 reveals that the secondary particles 150 contain substantially more than 99% hexagonal boron nitride and 1% or less cubic boron nitride, rhombohedral boron nitride, or wurtzite boron nitride, thereby improving the thermal conductivity of the thermal interface layer manufactured using the heat dissipation material.

[0094] The material used for the surface treatment of the secondary particles 150 is controlled depending on the type of the polymer resin. When the polymer resin is an epoxy resin, the secondary particles 150 are surface-treated using at least one of epoxy silane, amino silane, mercapto silane, and isocyanate silane. When the polymer resin is a urethane resin, the secondary particles 150 are surface-treated using at least one of epoxy silane, amino silane, ureido silane, mercapto silane, and isocyanate silane. When the polymer resin is a polyimide resin, the secondary particles 150 include at least one of epoxy silane, amino silane, ureido silane, and isocyanate silane.

[0095] Furthermore, as described above, when the secondary particles 150 are used together with the polymer resin, a further filler (second filler) is further used in addition to the secondary particles 150 (first filler). For example, the second filler includes at least one of carbon, carbon black, CNT, graphite, aluminum flakes, magnesium oxide, aluminum nitride, copper, boric anhydride, magnesium carbonate, zinc oxide, silicon oxide, aluminum oxide, and stainless steel.

[0096] The secondary particles 150 may be provided in the form of solid pellets without being mixed with the polymer resin. In this case, the secondary particles 150 are provided in a mold and compressed to form the pellets.

[0097] 5 and 6 are diagrams illustrating a process for manufacturing a thermal interface layer using the heat dissipation material manufactured by the method for manufacturing a heat dissipation material according to the first embodiment of the present invention.

[0098] As shown in FIGS. 5 and 6, the secondary particles 150 described in FIGS. 1 to 4 are used as a heat dissipation material / filler to form a thermal interface layer between the heat generating part 210 and the heat absorbing part 220.

[0099] A plurality of the secondary particles 150 are disposed in a polymer resin matrix 160 containing a polymer resin, and pressure is applied to the heat generating part 210 and the heat absorbing part 220 to form the thermal interface layer.

[0100] If the compressive strength of the secondary particles 150 is too high and the secondary particles 150 do not collapse during the formation of the thermal interface layer, as shown in FIG. 5, the interfaces of the heat generating part 210 and the heat absorbing part 220 in contact with the secondary particles 150 may be damaged, such as cracks occurring at the interface.

[0101] Furthermore, a heat transfer path is formed only by the secondary particles 150 that maintain their shape without collapsing, and there is a limit to the creation of a heat transfer path between the heat generating part 210 and the heat absorbing part 220, and there is a limit to improving the filling rate of the secondary particles 150 relative to the volume of the thermal interface layer.

[0102] However, the secondary particles 150 according to an embodiment of the present invention have a compressive strength that allows them to maintain their aggregate shape and easily collapse during the formation of the thermal interface layer. Therefore, in the step of manufacturing the thermal interface layer using the heat dissipation material manufactured using the secondary particles 150, as shown in FIG. 6, the secondary particles 150 in the heat dissipation material are easily compressed with a load that exceeds the compressive strength of the secondary particles 150, causing at least a portion of the secondary particles 150 to collapse.

[0103] As a result, a plurality of pieces 152 are generated from the disintegrated secondary particles 150, and the plurality of pieces 152 and the undisintegrated secondary particles 150 coexist in a mixed state within the thermal interface layer.

[0104] The plurality of pieces are aggregates of the primary particles 110 or are the primary particles 110 .

[0105] The secondary particles 150 are broken down during the load application process, which prevents damage to the interface of the heat generating part 210 and the interface of the heat absorbing part 220 that come into contact with the secondary particles 150. In addition, the pieces 152 generated by the breakup of the secondary particles 150 further create a heat transfer path between the heat absorbing part 220 and the heat generating part 210, thereby improving the thermal conductivity of the thermal interface layer.

[0106] Furthermore, the coexistence of multiple pieces 152 and the non-disintegrating secondary particles 150 within the thermal interface layer produces the same effect as fillers having substantially different sizes being present within the thermal interface layer, resulting in an improved filling rate of the thermal interface layer.

[0107] FIG. 7 is a diagram illustrating a process for manufacturing a thermal interface layer using a heat dissipation material manufactured by a method for manufacturing a heat dissipation material according to a modified example of the first embodiment of the present invention.

[0108] As shown in FIG. 7, the secondary particles 150 described in FIGS. 1 to 4 are used as heat dissipation materials / filler pillars to form a thermal interface layer between the heat generating part 210 and the heat absorbing part 220 as described in FIGS. 5 and 6.

[0109] Specifically, a guide template 170 is provided between the heat generating part 210 and the heat absorbing part 220. The inner space of the guide template 170 is empty. That is, the guide template 170 provides a partition wall at the edges of the heat generating part 210 and the heat absorbing part 220, and the inner space can be open.

[0110] The heat dissipation material, which includes the polymer matrix 160 and the secondary particles 150 dispersed in the polymer matrix 160, is applied to the empty internal space of the guide template 170, and then pressure is applied to the heat generating part 210 and the heat absorbing part 220 to form the thermal interface layer.

[0111] The guide template 170 prevents the secondary particles 150 of the heat dissipation material from leaking out in large amounts during the formation of the thermal interface layer, has high compressive strength, and the thickness of the guide template 170 can be substantially the same as the thickness of the thermal interface layer. That is, the heat dissipation material is compressed by the thickness of the guide template 170 due to the pressure applied to the heat generating unit 210 and the heat absorbing unit 220.

[0112] In this case, the thickness of the guide template 170 is thinner than the diameter and thickness of the secondary particles 150, and the guide template 170 has a higher compressive strength than the secondary particles 150. As a result, the secondary particles 150 are easily collapsed by the pressure applied during the process of forming the thermal interface layer, and the pieces 152 generated by the collapse of the secondary particles 150 further create a heat transfer path between the heat absorption part 220 and the heat generation part 210, thereby improving the thermal conductivity of the thermal interface layer and the fill rate of the thermal interface layer.

[0113] FIG. 8 is a sequence diagram for explaining the method for manufacturing a heat dissipation material according to the second embodiment of the present invention, and FIGS. 9 and 10 are diagrams for explaining the method for manufacturing a heat dissipation material according to the second embodiment of the present invention.

[0114] As shown in FIGS. 8 to 10, primary particles 110 are prepared (S210).

[0115] According to one embodiment, the primary particles 110 are boron nitride (BN) having a hexagonal crystal structure, or according to another embodiment, the primary particles 110 are at least one of carbon (C), silicon carbide (SiC), diamond, beryllium oxide (BeO), boron phosphide (BP), aluminum nitride (AlN), beryllium sulfide (BeS), boron arsenide (BAs), silicon (Si), gallium nitride (GaN), aluminum phosphide (AlP), and gallium phosphide (GaP).

[0116] Also, according to one embodiment, the primary particles 110 have a flake and / or plate shape, as shown in FIG.

[0117] Alternatively, according to another embodiment, the primary particles 110 have at least one shape of a nanoparticle, a nanotube, a nanoflake, a nanoneedle, a nanofiber, a nanodot, a nanosheet, a nanoribbon, a nanoplate, a nanosphere, a nanohorn, a nanocone, or a nanoscroll.

[0118] As described above, when the primary particles 110 are boron nitride having a hexagonal crystal structure, the primary particles 110 are provided in a state of being separated from a large amount of boron nitride.

[0119] As will be described later, a plurality of the primary particles 110 aggregate to form secondary particles 150. In this case, the smaller the size of the primary particles 110, the more spherical the secondary particles 150 are, thereby improving the flowability and dispersibility of the secondary particles 150 in the polymer resin. On the other hand, if the size of the primary particles 110 is too small, the interfaces between the primary particles 110 act as a heat transfer resistance, resulting in a decrease in thermal conductivity.

[0120] According to an embodiment of the present invention, the size of the secondary particles 150 is 1 to 10 μm or 1 to 5 μm, and the size of the primary particles 110 in the overall direction of at least two or all three of the three axes is 1 to 10% of the size of the secondary particles 150. Specifically, for example, the primary particles 110 have a thickness of about 10 nm or less and a plane length of about 70 nm, or a thickness of about 30 nm or less and a plane length of about 200 nm.

[0121] According to one embodiment, a surface treatment is performed on the primary particles 110. As described above, for example, if the primary particles 110 are made of boron nitride, a plurality of nitrogen groups (N-terminations) as shown in FIG. 2 are provided on the surfaces of the primary particles 110. In this case, the nitrogen groups on the surfaces of the primary particles 110 are substituted with first functional groups 112 through a surface treatment process. For example, the first functional groups 112 are hydroxyl groups (OH), and the process of substituting the nitrogen groups with the first functional groups 112 is performed by immersing the primary particles 110 in a basic solution (e.g., NaOH) and then drying.

[0122] Alternatively, according to another embodiment, the nitrogen groups are substituted with the first functional groups 112 (hydroxyl groups) by a method in which the primary particles 110 are heat-treated (e.g., at 1,000°C) in air, immersed in an acidic solution (e.g., sulfuric acid, nitric acid, phosphoric acid, etc.), immersed in a basic solution (e.g., NaOH, KOH, etc.), and then oxidized with an oxidizing agent (e.g., KMnO4, H2O2, etc.).

[0123] Alternatively, according to another embodiment, the first functional group 112 substituting the nitrogen group on the surface of the primary particle 110 is a hydrogen group (-H). In this case, a thiol molecule such as epoxy thiol is used instead of epoxy silane, which will be described later.

[0124] Specifically, as shown in FIG. 3, at least a portion of the nitrogen group terminals of boron nitride are substituted with the first functional groups 112 (hydroxyl groups).

[0125] If, unlike the above, the primary particles 110 are not surface-treated and a large amount of nitrogen groups are present on the surfaces of the primary particles 110, the primary particles 110 aggregate together in a source solution prepared using the primary particles 110, reducing the degree of dispersion, and therefore reducing the sphericity of the secondary particles 150 formed by the aggregation of the primary particles 110. Furthermore, sintering does not proceed smoothly in the subsequent sintering process.

[0126] Meanwhile, as described above, according to an embodiment of the present invention, the nitrogen groups on the surfaces of the primary particles 110 are substituted with the first functional groups 112 (e.g., hydroxyl groups) through a surface treatment process. As a result, the primary particles 110 have high dispersibility in the source solution, and the sphericity of the secondary particles 150 formed by agglomeration of the primary particles 110 is increased. In addition, the sintering process is accelerated by the first functional groups 112 during the subsequent sintering process.

[0127] After the surface treatment process for the primary particles 110 is completed, the primary particles 110, a binder, a dispersant, and a solvent are mixed to prepare a dispersion solution (S220). In the dispersion solution, the proportion of the primary particles 110 is 1 to 40 wt%, the proportion of the dispersant is 0.1 to 1 wt%, and the proportion of the binder is 0.1 to 5 wt%.

[0128] The ratio of the primary particles 110 in the source solution, the ratio of the solvent, and the ratio of the dispersant are controlled so that the zeta potential of the dispersion solution has a maximum value.

[0129] For example, the binder is polyvinyl alcohol, or the binder includes at least one of polyethylene glycol (PEG), methyl cellulose (MC), polyacrylic acid (PAA), polyacrylonitrile, and polyacrylamide.

[0130] For example, the dispersant is an aqueous solution of ammonium polymethacrylate, or the dispersant is an aqueous dispersant that includes at least one of polycarboxylic acid-based dispersants (acrylic acid-based, methacrylic acid-based, copolymers), phosphates, phosphate complex salts, arylsulfonic acids, and amine-based dispersants. Specifically, the dispersant includes an inorganic dispersant containing at least one of calcium phosphate salt, magnesium salt, hydrophilic silica, hydrophobic silica, and colloidal silica; or includes a nonionic polymer dispersant containing at least one of polyoxyethylene alkyl ether, polyoxyalkylene alkylphenol ether, sorbitan fatty acid ester, polyoxyalkylene fatty acid ester, glycerin fatty acid ester, polyvinyl alcohol, alkyl cellulose, and polyvinylpyrrolidone; or includes an ionic polymer dispersant containing at least one of polyacrylamide, polyvinylamine, polyvinylamine N-oxide, polyvinylammonium salt, polydialkyldiallylammonium salt, polyacrylic acid, polystyrene sulfonic acid, polyacrylate, polysulfonate, and polyaminoalkylacrylate.

[0131] For example, the solvent is pure water or ultrapure water, or the solvent is chloroform, chlorobenzene, acetic acid, acetone, acetonitrile, aniline, benzene, benzonitrile, benzyl alcohol, bromobenzene, bromoform, 1-butanol, 2-butanol, carbon disulfide, carbon tetrachloride, cyclohexane, cyclohexanone, decalin, dibromomethane, diethylene glycol, diethylene glycol ether, diethyl ether, dimethoxymethane, N,N-dimethylformamide, ethanol, ethylamine, ethylbenzene, ethylene glycol ether, ethylene glycol, ethylene oxide, formaldehyde, formic acid, glycerol, heptane, hexane, iodobenzene, mesitylene, methanol, methoxybenzene, methylamine, methylene bromide, methylene chloride, methylpyridine, morpholine, or the like. The solvent contains at least one of phosphorus, naphthalene, nitrobenzene, nitromethane, octane, pentane, pentyl alcohol, phenol, 1-propanol, 2-propanol, pyridine, pyrrole, pyrrolidine, quinoline, 1,1,2,2-tetrachloroethane, tetrachloroethylene, tetrahydrofuran, tetralin, tetramethylethylenediamine, thiophene, toluene, 1,2,4-trichlorobenzene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, triethylamine, triethylene glycol dimethyl ether, 1,3,5-trimethylbenzene, m-xylene, o-xylene, p-xylene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, and methylpyrrolidone.

[0132] Alternatively, for example, the solvent may include at least one of an alcohol ester (glycerin), polyether, amine, sulfonic acid, or cationic dispersant as a non-aqueous dispersant (solvent-based dispersant). Specifically, the solvent may include at least one of a fatty acid salt, an alkyl sulfonate, an alpha olefin sulfonate, an alkane sulfonate, an alkyl benzene sulfonate, a sulfosuccinate ester salt, an alkyl sulfate ester salt, an alkyl ether sulfate ester salt, an alkyl ether carboxylate salt, an alpha sulfo fatty acid methyl ester salt, a methyl taurate salt, a glycerin fatty acid ester, a polyglycerin fatty acid ester, a sucrose fatty acid ester, a sorbitan fatty acid ester, a polyoxyethylene sorbitan fatty acid ester, a polyoxyethylene alkyl ether, a polyoxyethylene alkylphenyl ether, a polyoxyethylene fatty acid ester, a fatty acid alkanolamide, or an alkyl glucoside.

[0133] Next, a boron source and a nitrogen source are added to the dispersion solution and dissolved to prepare a base source (S230). For example, the boron source includes boric acid, and the nitrogen source includes melamine.

[0134] The base source is sprayed to form droplets, and the droplets are dried to form preliminary secondary particles 140 (S240). According to one embodiment, the preliminary secondary particles 140 include primary agglomerated particles 120 formed by agglomerating a plurality of the primary particles, and intermediate particles 130 formed by reacting the boron source and the nitrogen source. For example, the intermediate particles 130 are melamine diborate.

[0135] The sprayed droplets of the base source are rapidly dried to produce the preliminary secondary particles, and the shape of the intermediate particles 130 is controlled by the weight ratio of the boron source and the nitrogen source in the base source.

[0136] According to one embodiment, the shape of the intermediate particle 130 is controlled by the weight ratio of the boron source and the nitrogen source. Specifically, when the weight ratio of the boron source and the nitrogen source is 1:1, the intermediate particle 130 is columnar, when the weight ratio of the boron source and the nitrogen source is 1:1 to 7:1, the intermediate particle 130 is spherical with an uneven surface, and when the weight ratio of the boron source and the nitrogen source is 7:1 to 14:1, the intermediate particle 130 is spherical.

[0137] The base source is atomized into the droplets using an ultrasonic vibrator, or the base source is atomized into the droplets using a spray.

[0138] A plurality of the primary particles 110 exist within the droplet, and the size of the preliminary secondary particles 140 is controlled according to the size of the droplet. The droplet is adjusted to 10 μm or less, or 3 μm or less, in which case the average size of the preliminary secondary particles 140 is about 2 μm.

[0139] The preliminary secondary particles 140 are collected using a centrifuge and then washed.

[0140] The preliminary secondary particles 140 are sintered to form secondary particles 150, and a plurality of the secondary particles 150 are mixed with a polymer resin to form a heat dissipating material (S250). That is, the heat dissipating material includes the secondary particles 150 formed by sintering the preliminary secondary particles 140 dispersed in a matrix containing the polymer resin.

[0141] The step of sintering the preliminary secondary particles 140 is performed by heat treating the preliminary secondary particles 140 in an inert gas atmosphere. For example, the inert gas is nitrogen gas, and the sintering is performed at a temperature of 1100°C or more and less than 1500°C for 2 hours or more.

[0142] During the heat treatment of the preliminary secondary particles 140, the intermediate particles 130 are formed to have the same phase as the primary agglomerated particles 120. Specifically, the intermediate particles 130 react at a temperature of 900°C or higher to form the same h-BN phase as the primary agglomerated particles 120.

[0143] Furthermore, the secondary particles 150 can be produced at a relatively low temperature due to the intermediate particles 130. Specifically, when secondary particles are produced by sintering preliminary secondary particles made of the primary agglomerate particles 120 without the intermediate particles 130, the primary agglomerate particles 120 do not bond and sinter easily at a relatively low temperature of about 1100°C, and the secondary particles break down due to minute impacts, requiring a high heat treatment temperature of 1500°C or higher. However, when the phase made of the primary agglomerate particles 120 and the intermediate particles 130 sinters preliminary secondary particles 140 to produce the secondary particles 150, the primary agglomerate particles 120 are easily bonded and sintered by the intermediate particles 130, and the secondary particles 150 can be easily produced even at a relatively low temperature of about 1100°C.

[0144] As described above, the first functional groups 112 (e.g., hydroxyl groups) are provided on the surfaces of the primary particles 110, and therefore, the first functional groups 112 act as a sintering aid during the sintering of the preliminary secondary particles 140. As a result, the preliminary secondary particles 140 are easily sintered, and as a result, the interfacial bonding between the primary particles 110 within the preliminary secondary particles 140 is improved, and the thermal conductivity of the secondary particles 150 manufactured by sintering the preliminary secondary particles 140 is improved, and the compressive strength of the secondary particles 150 is also improved.

[0145] According to one embodiment, the compressive strength of the secondary particles 150 is controlled by the temperature at which the preliminary secondary particles 140 are heat-treated. Specifically, as the temperature at which the preliminary secondary particles 140 are heat-treated increases, the compressive strength of the secondary particles 150 increases. For example, the compressive strength of the secondary particles 150 is 5 MPa or less, more preferably 0.2 to 2 MPa.

[0146] As a result, as will be described later, in the step of manufacturing a thermal interface layer using the heat dissipation material, at least a portion of the secondary particles 150 easily collapse, thereby creating multiple heat transfer paths within the thermal interface layer, improving thermal conductivity, and minimizing damage to the heat transfer layer and heat absorption layer in contact with the thermal interface layer.

[0147] Before mixing the secondary particles 150 with the polymer resin, the secondary particles 150 are surface-treated to bond second functional groups to the surfaces of the secondary particles 150, and the secondary particles 150 are immersed in a polymer solution to bond polymer groups to the surfaces of the secondary particles 150. For example, the second functional groups are hydroxyl groups and the polymer groups are epoxy groups. In this case, for example, the secondary particles 150 are immersed in a basic solution (e.g., NaOH) to bond the second functional groups to the surfaces of the secondary particles 150, and the secondary particles 150 are immersed in an epoxysilane solution to bond polymer groups to the surfaces of the secondary particles 150.

[0148] Thereafter, the plurality of secondary particles 150 are mixed with the polymer resin to manufacture the heat dissipation material.

[0149] The secondary particles 150 manufactured according to the present embodiment are fillers used with the polymer resin, and may have high sphericity (e.g., 70% or more). As a result, the secondary particles 150 have high flowability and dispersibility within the polymer resin matrix, and thus, a high fraction of the secondary particles 150 is provided within the polymer resin matrix. In other words, the higher the sphericity of the secondary particles 150, the higher the flowability and dispersibility within the polymer resin matrix, and thus, the fraction of the secondary particles 150 within the polymer resin matrix can be increased.

[0150] For example, the polymer resin may be an epoxy resin, a urethane resin, a polyimide resin, nylon, polyisoprene, polydicyclopentadiene, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, silicone, polyketone, aramid, cellulose, polyimide, rayon, polymethyl methacrylate resin, polyvinylidene chloride, polyvinylidene fluoride, polyurethane, polyisobutylene, polychloroprene, polybutadiene, polypropylene, polyvinyl chloride, polyvinyl acetate, polystyrene, polyester, polyvinylpyrrolidone, polycyanoacrylate, polyacrylonitrile, polyamide The polymerizable polymer contains at least one of the following: polyarylene ethynylene, polyphenylene ethynylene, polythiophene, polyanylene, polypyrrole, polybutylene terephthalate, polyethylene terephthalate, aromatic polyamide, polyamide, polycarbonate, polystyrene, polyphenylene sulfide, polysulfone, polyether sulfone, polyether imide, polyether ether ketone, polyarylate, polymethyl methyl acrylate, polyvinyl alcohol, polypropylene, polyethylene, polyacrylonitrile butadiene styrene copolymer, and polystyrene butadiene styrene copolymer.

[0151] The secondary particles 150 have a particle size distribution of 1 to 10 μm, with one maximum peak in the range of 1 to 5 μm.

[0152] Furthermore, the fraction of the secondary phase and the foreign material phase is 1% or less in an XRD analysis of the secondary particles 150. For example, when the primary particles 110 are hexagonal boron nitride, the secondary phase is at least one of cubic boron nitride, rhombohedral boron nitride, and wurtzite boron nitride, and the foreign material is at least one of boric anhydride, magnesium carbonate, zinc oxide, silicon oxide, and aluminum oxide.

[0153] In other words, XRD analysis of the secondary particles 150 reveals that the secondary particles 150 substantially contain more than 99% hexagonal boron nitride and 1% or less cubic boron nitride, rhombohedral boron nitride, or wurtzite boron nitride, thereby improving the thermal conductivity of the thermal interface layer manufactured using the heat dissipation material.

[0154] The material used for the surface treatment of the secondary particles 150 can be controlled depending on the type of polymer resin. When the polymer resin is an epoxy resin, the secondary particles 150 are surface-treated using at least one of epoxy silane, amino silane, mercapto silane, and isocyanate silane. When the polymer resin is a urethane resin, the secondary particles 150 are surface-treated using at least one of epoxy silane, amino silane, ureido silane, mercapto silane, and isocyanate silane. When the polymer resin is a polyimide resin, the secondary particles 150 include at least one of epoxy silane, amino silane, ureido silane, and isocyanate silane.

[0155] Furthermore, as described above, when the secondary particles 150 are used together with the polymer resin, a further filler (second filler) is further used in addition to the secondary particles 150 (first filler). For example, the second filler includes at least one of carbon, carbon black, CNT, graphite, aluminum flakes, magnesium oxide, aluminum nitride, copper, boric anhydride, magnesium carbonate, zinc oxide, silicon oxide, aluminum oxide, and stainless steel.

[0156] The secondary particles 150 may be provided in the form of solid pellets without being mixed with the polymer resin, in which case the pellets are manufactured by providing the secondary particles 150 in a mold and compressing them.

[0157] The results of characteristic evaluations based on specific experimental examples of the present invention will be described below.

[0158] (Production of heat dissipation material according to Experimental Example 1) As primary particles, first h-BN nanoflakes with a thickness of approximately 10 nm or less and a size of approximately 70 nm in the plane direction, and second h-BN nanoflakes with a thickness of approximately 30 nm or less and a size of approximately 200 nm in the plane direction were prepared.

[0159] The first and second h-BN nanoflakes were surface-treated by immersing them in a 5 M NaOH solution at 60°C for 18 hours to replace the nitrogen groups (N-terminations) on the surfaces of the first and second h-BN nanoflakes with hydroxide groups (OH-terminations), improving their dispersibility in water and the sphericity of the secondary particles. This surface modification also facilitates the sintering of the first and second h-BN nanoflakes during the subsequent sintering process.

[0160] The surface-treated first and second h-BN nanoflakes were separately dispersed in a solvent with a dispersant and a binder to prepare a source solution. Water was used as the solvent, Darvan-C ammonium polymethacrylate solution was used as the dispersant, and PVA was used as the binder. The concentrations of the first and second h-BN nanoflakes were 5 wt%, 0.5 wt%, and 1.25 wt%, respectively.

[0161] The source solution was spray-dried to prepare spherical preliminary secondary particles. Specifically, the source solution was sprayed while controlling the droplet size to be 10 μm or less, and then dried to prepare spherical preliminary secondary particles.

[0162] Thereafter, the mixture was washed three times using a centrifuge and sintered in a nitrogen atmosphere at 1500° C. for two hours to produce secondary particles.

[0163] After the sintering process, the secondary particles were immersed in 5M NaOH at 60°C for 18 hours to be surface-treated to have hydroxyl groups, and then immersed in an epoxysilane solution at 80°C for 4 hours to be surface-treated to have epoxy groups.

[0164] 11 to 13 are SEM photographs of secondary particles produced in Experimental Example 1 of the present invention.

[0165] As shown in Figures 11 to 13, SEM photographs were taken of the secondary particles produced according to Experimental Example 1. Figure 11 is an SEM photograph (high magnification) of secondary particles produced to an average size of about 2 μm using 70 nm-sized primary particles, Figure 12 is an SEM photograph of secondary particles produced to an average size of about 2 μm using 200 nm-sized primary particles, and Figure 13 is an SEM photograph (low magnification) of secondary particles produced to an average size of 2 μm using 70 nm-sized primary particles.

[0166] 11 to 13, it can be seen that when relatively small primary particles are used, the secondary particles have higher sphericity than when relatively large primary particles are used, and it can be confirmed that there are fewer pores within the secondary particles.

[0167] FIG. 14 is a photograph showing the contact angle measured by the surface treatment of the secondary particles produced in Experimental Example 1 of the present invention.

[0168] As shown in Figure 14, the contact angles of secondary particles manufactured to an average size of approximately 2 μm using 70 nm-sized primary particles were measured. Figure 14(a) shows the contact angle of the secondary particles immediately after sintering, Figure 14(b) shows the contact angle of the secondary particles treated with NaOH, and Figure 14(c) shows the contact angle of the secondary particles treated with epoxysilane.

[0169] Figure 14 shows that the contact angle of the secondary particles was measured as high at 22.8° immediately after sintering, but when hydroxyl groups were bonded using NaOH, it became highly hydrophilic. After that, when epoxy groups were bonded using epoxysilane, the contact angle increased slightly again to 14.6°.

[0170] (Production of secondary particles according to Experimental Example 2-1) The first-h-BN nanoflakes described in Experimental Example 1 were prepared, and secondary particles were produced in the same manner as in Experimental Example 1. The proportion of primary particles in the source solution was controlled to 5 wt%. When spraying the source solution, the gas flow rate was controlled to 550-600 L / h, the pump rate to 15% (30 ml / min at 100%), and the inlet temperature to 150°C, to produce secondary particles according to Experimental Example 2-1.

[0171] (Production of secondary particles according to Experimental Example 2-2) Secondary particles were produced in the same manner as in Experimental Example 2-1, and the ratio of primary particles in the source solution was controlled to 3 wt %.

[0172] (Production of secondary particles according to Experimental Example 2-3) Secondary particles were produced in the same manner as in Experimental Example 2-1, and the ratio of primary particles in the source solution was controlled to 2 wt %.

[0173] (Production of secondary particles according to Experimental Example 2-4) Secondary particles were produced in the same manner as in Experimental Example 2-1, and the ratio of primary particles in the source solution was controlled to 1.5 wt %.

[0174] (Production of secondary particles according to Experimental Example 2-5) Secondary particles were produced in the same manner as in Experimental Example 2-1, and the ratio of primary particles in the source solution was controlled to 1.3 wt %.

[0175] (Production of secondary particles according to Experimental Example 2-6) Secondary particles were produced in the same manner as in Experimental Example 2-1, and the ratio of primary particles in the source solution was controlled to 1 wt %.

[0176] The conditions for producing secondary particles according to Experimental Examples 2-1 to 2-6 are as shown in Table 1 below.

[0177] [Table 1]

[0178] FIG. 15 is a SEM photograph of secondary particles produced in Experimental Examples 2-1 to 2-6 of the present invention.

[0179] Figure 15 shows that when the primary particle content is 5 wt% and 1 wt%, the secondary particle size differs by an average of 1 μm or more. It also shows that the h-BN nanoflake particles in the source solution cannot be dispersed evenly, and the higher the concentration, the greater the concentration difference between the ejected droplets, resulting in a decrease in the uniformity of the secondary particle size.

[0180] In addition, it was confirmed that D50 was 8 μm when the content of primary particles was 5 wt%, and D50 was 3 μm when the content of primary particles was 1 wt%.

[0181] (Production of secondary particles according to Experimental Example 3-1) Secondary particles were prepared in the same manner as in Experimental Example 2-1.

[0182] (Production of secondary particles according to Experimental Example 3-2) Secondary particles were produced in the same manner as in Experimental Example 3-1, and the gas flow rate during spraying of the source solution was controlled to 500 to 550 L / h.

[0183] (Production of secondary particles according to Experimental Example 3-3) Secondary particles were produced in the same manner as in Experimental Example 3-1, and the gas flow rate during spraying of the source solution was controlled to 450 to 500 L / h.

[0184] (Secondary particle production by Experimental Example 3-4) Secondary particles were produced in the same manner as in Experimental Example 3-1, and the gas flow rate during spraying of the source solution was controlled to 400 to 450 L / h.

[0185] The conditions for producing secondary particles according to Experimental Examples 3-1 to 3-4 are as shown in Table 2 below.

[0186] [Table 2]

[0187] FIG. 16 is a SEM photograph of secondary particles produced according to Experimental Examples 3-1 to 3-4 of the present invention.

[0188] As shown in Figure 16, the higher the gas flow rate, the higher the ejection force and the higher the energy of the ejected droplets. Also, the faster the ejected droplet velocity, the smaller the droplet size, which results in smaller agglomerated granules.

[0189] 16, it can be seen that the average size differs by up to 1 μm when the gas flow rate is 400 to 450 L / h compared to when the gas flow rate is 550 to 600 L / h. In other words, it can be seen that the size of the secondary particles can be controlled by controlling the gas flow rate.

[0190] (Production of secondary particles according to Experimental Example 4-1) Secondary particles were prepared in the same manner as in Experimental Example 2-1.

[0191] (Production of secondary particles according to Experimental Example 4-2) Secondary particles were produced in the same manner as in Experimental Example 3-1, and the inlet temperature was controlled to 170°C.

[0192] (Production of secondary particles according to Experimental Example 4-3) Secondary particles were produced in the same manner as in Experimental Example 3-1, and the inlet temperature was controlled to 190°C.

[0193] The conditions for producing secondary particles according to Experimental Examples 4-1 to 4-3 are as shown in Table 3 below.

[0194] [Table 3]

[0195] FIG. 17 is a SEM photograph of secondary particles produced according to Experimental Examples 4-1 to 4-3 of the present invention.

[0196] From Figure 17, we can see that as the temperature increases, the granule size increases but the sphericity decreases. This is because as the temperature increases, the surface tension of the scattered droplets decreases, making it impossible for them to maintain their spherical shape, and the solvent in the granules evaporates rapidly due to rapid drying, destroying the droplet structure.

[0197] 18 and 19 are SEM images and XRD analysis graphs of secondary particles produced according to Experimental Example 1 of the present invention.

[0198] As shown in FIGS. 18 and 19, SEM photographs of secondary particles manufactured using the first h-BN nanoflakes according to Experimental Example 1 were taken, and XRD analysis was performed.

[0199] 18 and 19, it can be seen that the fraction of secondary phases and foreign material phases is 1% or less, i.e., the secondary powder particles consist of more than 99% hexagonal boron nitride and contain 1% or less of cubic boron nitride, rhombohedral boron nitride, or wurtzite boron nitride.

[0200] FIG. 20 is an SEM photograph of the preliminary secondary particles prepared according to Experimental Example 1 of the present invention after ultrasonic dispersion, and FIG. 21 is a graph showing the particle size distribution of the secondary particles prepared according to Experimental Example 1 of the present invention after ultrasonic dispersion.

[0201] As shown in Figures 20 and 21, in Experimental Example 1, preliminary secondary particles were produced using the first h-BN nanoflakes, and the preliminary secondary particles before sintering and the secondary particles after sintering were dispersed in water and subjected to ultrasonic treatment under conditions of 20 KHz and 200 W.

[0202] From FIG. 20, it can be seen that in the case of the pre-sintered secondary particles, the granular and aggregated shapes are broken and many of the pre-sintered secondary particles return to primary particles again.

[0203] On the other hand, in the case of the secondary particles that have undergone the sintering process, when ultrasonic treatment is performed for 0, 10, 30, and 60 seconds, the peak value of the maximum particle size is slightly reduced, but as time passes, the amount of reduction is significantly reduced, and even after 60 seconds, it is confirmed that the maximum particle size is maintained at about 74%.

[0204] That is, the sintering aid provided during the secondary particle manufacturing process causes the primary particles to aggregate with high cohesive force to form the secondary particles, and as a result, the secondary particles do not collapse even when subjected to ultrasonic impact, maintaining a maximum particle size peak value of 40-90%. As a result, the secondary particles do not collapse during the manufacturing and / or distribution process and can maintain their spherical shape, thereby allowing the secondary particles to have high dispersibility and flowability within the polymer matrix.

[0205] The zeta potentials of the source solutions prepared by mixing the primary particles (first h-BN nanoflakes having a size of approximately 70 nm) described in Experimental Example 1, the solvent (water), and the dispersant (ammonium polymethacrylate aqueous solution) were measured according to the ratio of the primary particles and the dispersant, as shown in Tables 4 to 6 below.

[0206] From Tables 4 to 6 below, it can be seen that the zeta potential has a maximum value when the dispersant ratio is greater than 0.45 wt% and less than 0.55 wt%, and that the maximum zeta potential value increases as the ratio of primary particles decreases.

[0207] [Table 4]

[0208] [Table 5]

[0209] [Table 6]

[0210] In the above example for measuring the zeta potential, the proportion of the dispersant was fixed at 0.5 wt %, and the zeta potential depending on the proportion of the binder was measured as shown in Tables 7 to 9 below.

[0211] From Tables 7 to 9 below, it can be seen that when a binder is added, the maximum value of the zeta potential decreases slightly, and that the zeta potential reaches its maximum value when the binder ratio is greater than 1.20 wt% and less than 1.30 wt%.

[0212] [Table 7]

[0213] [Table 8]

[0214] [Table 9]

[0215] (Production of secondary particles according to Experimental Example 5) Boric acid (H3BO3), melamine (C3H6N6), and a dispersant were added to distilled water and stirred to react. The dispersant was Darvan-C, and the amount of the dispersant was 1 wt% or more. The mixture was stirred at 80°C for 24 hours or more to thoroughly disperse the boric acid and melamine ions in the solution.

[0216] A binder was added to the stirred reaction solution, followed by further stirring. PVA was used as the binder. The further stirring was carried out at a temperature of 90°C for 30 minutes or more.

[0217] The solution dispersed in water was spray-dried using an ultrasonic method to prepare preliminary secondary particles, and the preliminary secondary particles were sintered at a temperature of 1500°C or higher to prepare secondary particles.

[0218] FIG. 22 is a SEM photograph of secondary particles produced according to Experimental Example 5 of the present invention.

[0219] As shown in Fig. 22, an SEM photograph was taken of the secondary particles produced in the above-mentioned Experimental Example 5. From Fig. 22, it can be seen that the size of the spherical particles is about 1 to 2 µm based on D50.

[0220] FIG. 23 is an SEM photograph showing the crystal shape of a common melamine diborate.

[0221] As shown in FIG. 23, an SEM photograph was taken of melamine diborate, which is a compound precipitated by the reaction of a combination of precursors dissolved in a solution during the process of producing secondary particles according to Experimental Example 5.

[0222] As can be seen from FIG. 23, melamine diborate has a columnar crystal structure, and it was confirmed that in general precipitation, it dries into columnar particles with a primary circular structure.

[0223] 24 and 25 are SEM photographs of secondary particles according to Experimental Example 5, which were produced by varying the mixing ratio of boric acid and melamine.

[0224] As shown in Figures 24 and 25, secondary particles were produced according to Experimental Example 5 with different mixing ratios of boric acid and melamine, and then SEM photographs of the produced particles were taken. Specifically, Figure 24 shows a photograph of boric acid and melamine mixed at a weight ratio of 1:1, the upper photograph of Figure 25 shows a photograph of boric acid and melamine mixed at a weight ratio of 7:1 to 14:1, and the lower photograph of Figure 25 shows a photograph of boric acid and melamine mixed at a weight ratio of 1:1 to 7:1.

[0225] It can be seen from Figure 24 that when boric acid and melamine are mixed in a weight ratio of 1:1, the secondary particles have a short columnar shape. In contrast, it can be seen from Figure 25 that when boric acid and melamine are mixed in a weight ratio of 1:1 to 7:1, the secondary particles have a shrunken grape skin shape, and when boric acid and melamine are mixed in a weight ratio of 7:1 to 14:1, the secondary particles have a spherical shape.

[0226] FIG. 26 is an SEM photograph of boric acid formed during the process of producing secondary particles according to Experimental Example 5 of the present invention, and FIG. 27 is an SEM photograph of melamine formed during the process of producing secondary particles according to Experimental Example 5 of the present invention.

[0227] As shown in Figure 26, an SEM photograph was taken of the boric acid spray-dried in the process of producing secondary particles according to Experimental Example 5, and as shown in Figure 27, an SEM photograph was taken of the melamine spray-dried in the process of producing secondary particles according to Experimental Example 5. From Figure 26, it can be seen that the spray-dried boric acid has a hollow spherical shape, and from Figure 27, it can be seen that the spray-dried melamine has a solid spherical shape.

[0228] (Production of secondary particles according to Experimental Example 6) As primary particles, first h-BN nanoflakes with a thickness of approximately 10 nm or less and a size of approximately 70 nm in the plane direction, and second h-BN nanoflakes with a thickness of approximately 30 nm or less and a size of approximately 200 nm in the plane direction were prepared.

[0229] The first and second h-BN nanoflakes were surface-treated by immersing them in a 5 M NaOH solution at 60°C for 18 hours. This substituted nitrogen groups (N-terminations) on the surfaces of the first and second h-BN nanoflakes with hydroxyl groups (OH-terminations), improving their dispersibility in water and the sphericity of the secondary particles. This surface modification also facilitated the sintering of the first and second h-BN nanoflakes during the subsequent sintering process.

[0230] The surface-treated first and second h-BN nanoflakes were separately dispersed in a solvent with a dispersant and a binder to prepare dispersions. Water was used as the solvent, ammonium polymethacrylate aqueous solution (Darvan-C) was used as the dispersant, and PVA was used as the binder. The first and second h-BN nanoflakes were 40 wt%, the dispersant was 0.5 wt%, and the binder was 1.25 wt%.

[0231] Boric acid (H3BO3) and melamine (C3H6N6) were added to the dispersion solution and dissolved to prepare a base sauce. The boric acid and melamine were added in a weight ratio of 7:1 to 14:1.

[0232] The base source was spray-dried to produce spherical preliminary secondary particles. Specifically, the base source was sprayed while controlling the droplet size to 10 μm or less, and then dried to produce the spherical preliminary secondary particles. The preliminary secondary particles were composed of primary agglomerated particles formed by agglomerating a plurality of primary particles, and intermediate particles formed by the reaction of boric acid and melamine.

[0233] Thereafter, the mixture was washed three times using a centrifuge and sintered in a nitrogen atmosphere at 1100° C. for two hours to produce secondary particles.

[0234] FIG. 28 is a diagram illustrating XRD characteristics depending on the heat treatment temperature of intermediate particles formed in the production process of secondary particles according to Experimental Example 6 of the present invention.

[0235] FIG. 28 shows XRD (X-ray diffraction) characteristics of intermediate particles formed by the reaction of boric acid and melamine during the secondary particle manufacturing process according to Experimental Example 6, as a function of heat treatment temperature.

[0236] From FIG. 28, it can be seen that the intermediate particles are reacted at temperatures above 900° C. to form the h-BN phase.

[0237] FIG. 29 is a diagram for explaining the XRD characteristics of secondary particles according to Experimental Example 6 of the present invention.

[0238] 29 shows the XRD characteristics of a number of samples manufactured by controlling the content of intermediate particles relative to primary particles to different levels during the secondary particle manufacturing process according to Experimental Example 6. Specifically, MD0 represents secondary particles manufactured by controlling the content of intermediate particles relative to primary particles to 0 wt%, MD1 represents secondary particles manufactured by controlling the content of intermediate particles relative to primary particles to 1 wt%, MD5 represents secondary particles manufactured by controlling the content of intermediate particles relative to primary particles to 5 wt%, MD10 represents secondary particles manufactured by controlling the content of intermediate particles relative to primary particles to 10 wt%, and MD15 represents secondary particles manufactured by controlling the content of intermediate particles relative to primary particles to 15 wt%.

[0239] It can be seen from FIG. 29 that all of the samples have a single h-BN phase.

[0240] FIG. 30 is a diagram illustrating the BET specific surface area of ​​secondary particles according to Experimental Example 6 of the present invention.

[0241] As shown in Figure 30, during the secondary particle production process according to Experimental Example 6, the content of intermediate particles relative to primary particles was varied to produce a number of samples, and the BET specific surface area of ​​each sample was measured. MD0 to MD15 are as described in Figure 29. The measured BET specific surface areas are summarized in Table 10 below.

[0242] [Table 10]

[0243] From FIG. 30 and Table 10, it can be seen that as the content of intermediate particles increases, the BET specific surface area of ​​the secondary particles decreases.

[0244] FIG. 31 is a diagram for explaining the pore volume of secondary particles according to Experimental Example 6 of the present invention.

[0245] Figure 31 shows the pore volume measurement results for each sample produced by varying the content of intermediate particles relative to primary particles during the secondary particle production process according to Experimental Example 6. MD0 to MD15 are as described in Figure 29. The measured pore volumes are summarized in Table 11 below.

[0246] [Table 11]

[0247] From FIG. 31 and Table 11, it can be seen that as the content of intermediate particles increases, the pore volume of secondary particles decreases.

[0248] 32 to 35 are diagrams illustrating the PSA characteristics of secondary particles against ultrasonic impact according to Experimental Example 6 of the present invention.

[0249] 32 to 35 show the PSA characteristics of each sample measured against ultrasonic impact after varying the content of intermediate particles relative to primary particles during the secondary particle manufacturing process according to Experimental Example 6. MD0 to MD15 are as described in FIG.

[0250] 32 to 35 show that in the absence of intermediate particles (MD0), bonding or sintering between h-BN primary particles does not occur during heat treatment at 1100°C, causing the secondary particles to easily crumble due to ultrasonic impact, whereas in the presence of intermediate particles, 80% or more of the particle size maximum peak is maintained. That is, even when the secondary particles according to Experimental Example 6 are dispersed in water and subjected to ultrasonic treatment at 20 kHz and 200 W, the particle size maximum peak is maintained at over 80%.

[0251] FIG. 36 is a diagram illustrating viscosity characteristics when secondary particles according to Experimental Example 6 of the present invention are dispersed in epoxy resin.

[0252] 36 shows the results of manufacturing multiple samples by varying the content of intermediate particles relative to primary particles during the manufacturing process of secondary particles according to Experimental Example 6, dispersing each sample in epoxy resin, and measuring the viscosity. MD0 and MD1 are as described in FIG.

[0253] From Figure 36, it was confirmed that when there are no intermediate particles (MD0), all of the secondary particles in the epoxy resin break down and the viscosity increases rapidly, whereas when there are intermediate particles (MD1), the resin has Newtonian fluid properties (viscosity is maintained regardless of rpm).

[0254] FIG. 37 is an SEM photograph showing the secondary particles dispersed in epoxy resin according to Experimental Example 6 of the present invention.

[0255] Figure 37 shows SEM images of the dispersion state of multiple samples prepared by varying the content of intermediate particles relative to primary particles during the secondary particle preparation process according to Experimental Example 6, which were then dispersed in epoxy resin. The top image shows MD0, and the bottom image shows MD1. MD0 and MD1 are as described in Figure 29.

[0256] From Figure 37, it was confirmed that when there were no intermediate particles (MD0), all of the secondary particles collapsed in the epoxy resin, whereas when there were intermediate particles (MD1), the shape was maintained.

[0257] Although the present invention has been described in detail using preferred embodiments, the scope of the present invention should not be limited to the specific embodiments, but should be interpreted by the appended claims. Furthermore, it will be understood that various modifications and variations are possible within the scope of the present invention, as long as they do not deviate from the scope of the present invention, by those skilled in the art. [Industrial Applicability]

[0258] The heat dissipation material, the composition including the same, and the manufacturing method thereof according to the embodiments of the present invention are applicable to the heat dissipation industry.

Claims

1. providing primary particles; mixing the primary particles, a binder, a dispersant, and a solvent to prepare a dispersion solution; adding and dissolving a boron source and a nitrogen source in the dispersion solution to prepare a base source; spraying the base source to form droplets, and drying the droplets to form preliminary secondary particles including primary agglomerated particles formed by agglomerating a plurality of the primary particles and intermediate particles formed by reacting the boron source and the nitrogen source; sintering the preliminary secondary particles to prepare secondary particles; and mixing a plurality of the secondary particles with a polymer resin to prepare a heat dissipation material; the content of the intermediate particles is controlled to 1 wt % relative to the primary particles, In the step of preparing the base source, a weight ratio of the boron source to the nitrogen source added to the dispersion solution is controlled to be 7:1 or more and 14:1 or less; the primary particles include h-BN flakes; the boron source comprises boric acid; the nitrogen source comprises melamine; Examples of the solvent include pure water, ultrapure water, chloroform, chlorobenzene, acetic acid, acetone, acetonitrile, aniline, benzene, benzonitrile, benzyl alcohol, bromobenzene, bromoform, 1-butanol, 2-butanol, carbon disulfide, carbon tetrachloride, cyclohexane, cyclohexanone, decalin, dibromomethane, diethylene glycol, diethylene glycol ether, diethyl ether, dimethoxymethane, N,N-dimethylformamide, ethanol, ethylamine, ethylbenzene, ethylene glycol ether, ethylene glycol, ethylene oxide, formaldehyde, formic acid, glycerol, heptane, hexane, iodobenzene, mesitylene, methanol, methoxybenzene, methylamine, methylene bromide, methylene chloride, methylpyridine, morpholine, and naphthalene. a method for producing a heat dissipating material comprising at least one of benzene, nitrobenzene, nitromethane, octane, pentane, pentyl alcohol, phenol, 1-propanol, 2-propanol, pyridine, pyrrole, pyrrolidine, quinoline, 1,1,2,2-tetrachloroethane, tetrachloroethylene, tetrahydrofuran, tetralin, tetramethylethylenediamine, thiophene, toluene, 1,2,4-trichlorobenzene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, triethylamine, triethylene glycol dimethyl ether, 1,3,5-trimethylbenzene, m-xylene, o-xylene, p-xylene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, and methylpyrrolidone.

2. The method for manufacturing a heat dissipating material according to claim 1 , wherein the secondary particles are manufactured by sintering the preliminary secondary particles at a temperature of 1100° C. or more and less than 1500° C.

3. 2. The method for manufacturing a heat dissipating material according to claim 1, wherein in the process of manufacturing the secondary particles, the preliminary secondary particles are sintered so that the intermediate particles have the same phase as the primary agglomerated particles.

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