Gallium-containing aluminum oxide particles, and slurry composition and resin composite composition containing the same

Abstract

Provided is a novel alumina particle, particularly an alumina particle having a gallium content within a specific range as measured by inductively coupled plasma mass spectrometry (ICP-MS), and a slurry composition and a resin composite composition containing the same. An alumina particle having an average particle diameter of 0.5 to 30.0 µm and a gallium content of 1.0 to 60.0 ppm as measured by inductively coupled plasma mass spectrometry (ICP-MS), and a slurry composition and a resin composite composition containing the same.

Description

Technical Field

[0001] This invention relates to gallium-containing alumina particles, and more particularly to alumina particles with gallium content within a specific range as determined by inductively coupled plasma mass spectrometry (ICP-MS), as well as slurry compositions and resin composite compositions containing the alumina particles. Background Technology

[0002] In recent years, due to the increasing functionality and speed of electronic devices such as mobile phones, the heat generated by internal electronic components has increased. To ensure the normal operation of these devices, efficiently dissipating this heat to the outside has become a crucial issue. Common heat dissipation methods include heat sinks and heat-dissipating adhesives. These are attached or coated and pressed between the heat-generating element and the heat sink fins, thereby eliminating gaps between them and achieving efficient heat dissipation. Furthermore, the semiconductors themselves inside electronic components also generate significant heat due to their increased functionality and speed, requiring heat-dissipating properties in the sealing materials protecting them.

[0003] Generally, heat sinks or thermal adhesives, and semiconductor sealing materials are composed of thermally conductive inorganic fillers and resins. (Sometimes, such mixtures of fillers and resins are also referred to as resin compositions or resin composite compositions.) The thermally conductive inorganic fillers use inexpensive aluminum hydroxide or alumina (hereinafter, alumina), and raw materials such as silicon carbide, boron nitride, or aluminum nitride, which are expected to have high thermal conductivity. As for the resin, silicone resin is generally used for heat sinks or thermal adhesives, while epoxy resin is generally used for semiconductor sealing materials.

[0004] Generally, in thermally conductive inorganic fillers, particles with better symmetry in their crystal structure (α and θ phases in the case of alumina) exhibit less scattering due to lattice incompleteness, thus resulting in higher thermal conductivity (e.g., Non-Patent Document 1). On the other hand, a high content of α and θ phases leads to a loss of surface smoothness (e.g., Patent Document 1). Furthermore, due to the high hardness of the α phase, reports have indicated a deterioration in wear characteristics caused by a large amount of α phase (e.g., Patent Document 2). For example, during the mixing process of fillers and resins in heat sink manufacturing, problems such as wear on the mixing equipment may occur (e.g., Patent Documents 1 and 2). Therefore, the design of materials that combine high thermal conductivity and smooth surface shape in thermally conductive inorganic fillers is an important technical challenge.

[0005] Patent Document 2 discloses a method of spraying aluminum hydroxide powder or a slurry of aluminum hydroxide powder into a flame through a feed pipe with strong dispersing function to obtain spherical alumina powder. It discloses that by this method, the main crystalline phase of the spherical alumina powder is composed of δ and α, which can improve mold wear characteristics. However, according to Patent Document 1, even particles with an average sphericity of 0.90 or higher in the spherical alumina particles obtained by this method have surface irregularities derived from the aluminum hydroxide raw material, leaving room for improvement.

[0006] Furthermore, Patent Document 1 discloses a method for obtaining spherical alumina by feeding aluminum hydroxide or alumina at a specific feed rate as a raw material, melting it at 2050~2300°C, and then rapidly cooling it with dry ice. This method yields highly fluid spherical alumina powder with a δ-phase peak intensity / θ-phase peak intensity ratio (δ-phase peak intensity / θ-phase peak intensity) of 1.0 or higher in X-ray diffraction and controlled surface shape. However, because the rapid cooling process involves feeding low-temperature dry ice into a high-temperature melting furnace during the flame melting of the alumina raw material, it is considered to place a heavy load on the manufacturing equipment, making stable industrial production difficult. Additionally, there is room for improvement regarding surface shape control and mold wear characteristics.

[0007] Prior art literature

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2011-102215

[0010] Patent Document 2: Japanese Patent Application Publication No. 2001-19425

[0011] Non-patent literature

[0012] Non-Patent Literature 1: Kittel's Introduction to Solid State Physics, 5th Edition Summary of the Invention

[0013] The technical problem that the invention aims to solve

[0014] As mentioned above, attempts were made to design materials that combine high thermal conductivity with excellent surface smoothness for alumina particles, but the results were insufficient and further improvements are needed. Furthermore, from the perspective of stable industrial production, a manufacturing method that does not place excessive load on the manufacturing equipment is also required.

[0015] Technical means for solving technical problems

[0016] The inventors conducted a detailed study of alumina particles and discovered that by controlling the gallium content in the alumina particles within a specific range, they achieved exceptionally high thermal conductivity and excellent surface smoothness. Furthermore, they found that this method allows for the control of these properties without placing excessive load on the manufacturing apparatus.

[0017] While not wishing to be bound by a specific theory, it is believed that by controlling the presence ratio of α, θ, and δ phases obtained by X-ray diffraction (XRD) and analysis by the Rietveld method, especially by setting the θ phase to a certain amount, the smoothness of the surface shape can be improved.

[0018] The present invention is an invention that solves the aforementioned problems based on the above insights, and its main purpose is as described in the scope of protection. [1]

[0020] A gallium-containing aluminum oxide particle, characterized in that,

[0021] The average particle size is 0.5~30.0 μm, and the gallium content determined by inductively coupled plasma mass spectrometry (ICP-MS) is 1.0~60.0 ppm. [2]

[0023] As described in [1], gallium-containing aluminum oxide particles,

[0024] The ratio of the presence of α, θ, and δ phases, determined by X-ray diffraction (XRD) and analyzed by the Ridwald method, is expressed as (α+θ) / δ≧2.0. [3]

[0026] Gallium-containing aluminum oxide particles as described in [1] or [2],

[0027] The ratio of the presence of the θ and δ phases, determined by X-ray diffraction (XRD) and analyzed by the Riedwald method, is expressed as θ / δ≧2.0. [4]

[0029] Gallium-containing aluminum oxide particles as described in any of [1] to [3],

[0030] Roundness is 0.90 or higher. [5]

[0032] A slurry composition, characterized in that,

[0033] Contains gallium-containing aluminum oxide particles as described in any one of [1] to [4]. [6]

[0035] The slurry composition as described in [5],

[0036] It also contains at least one inorganic filler selected from amorphous spherical alumina particles, crystalline spherical silica particles, titanium dioxide particles, magnesium oxide particles, aluminum nitride particles, boron nitride particles, barium titanate particles, calcium titanate particles, carbon fiber, talc, mica, kaolin, calcium oxide, zinc oxide, barium sulfate, calcium sulfate, and alkaline earth basic carbonates (calcium carbonate, magnesium carbonate, etc.). [7]

[0038] A resin composite composition, characterized in that,

[0039] Contains gallium-containing aluminum oxide particles as described in any one of [1] to [4]. [8]

[0041] The resin composite composition as described in [7],

[0042] It also contains at least one inorganic filler selected from amorphous spherical alumina particles, crystalline spherical silica particles, titanium dioxide particles, magnesium oxide particles, aluminum nitride particles, boron nitride particles, barium titanate particles, calcium titanate particles, carbon fiber, talc, mica, kaolin, calcium oxide, zinc oxide, barium sulfate, calcium sulfate, and alkaline earth basic carbonates (calcium carbonate, magnesium carbonate, etc.).

[0043] Invention Effects

[0044] The alumina particles of the present invention, with gallium content controlled within a specific range, exhibit particularly excellent thermal conductivity and high-level surface smoothness.

[0045] Furthermore, the gallium-containing alumina particles exhibit exceptional industrial stability in achieving these characteristics without placing excessive load on the manufacturing equipment.

[0046] Furthermore, by controlling the gallium content in the alumina particles, the balance between thermal conductivity and surface smoothness can be easily controlled. That is, the required level of thermal conductivity varies depending on the application, and the required level of wear resistance for equipment such as mixing plants varies depending on the equipment itself, but the aforementioned balance can be controlled based on these desired characteristics.

[0047] Furthermore, the aforementioned effects are particularly useful when the gallium-containing alumina particles are used as fillers in products requiring thermal conductivity, such as heat sinks, thermal adhesives, and semiconductor sealing materials. Detailed Implementation

[0048] (The gallium content, determined by inductively coupled plasma mass spectrometry (ICP-MS), ranged from 1.0 to 60.0 ppm.)

[0049] The alumina particles provided by one embodiment of the present invention are characterized in that,

[0050] The gallium content, determined by inductively coupled plasma mass spectrometry (ICP-MS), is 1.0 to 60.0 ppm. The preferred upper limit is 40.0, more preferably 30.0, further preferably 20.0, and even more preferably 10.0 ppm. The preferred lower limit is 2.0, more preferably 3.0 ppm.

[0051] By controlling the gallium content in the alumina particles within the aforementioned range, it is possible to achieve both excellent thermal conductivity and low wear resistance.

[0052] The details are not yet clear, but if the gallium content is less than 1.0 ppm, the surface unevenness accompanying crystallization becomes significant during the manufacture of alumina particles, such as in the cooling process after the alumina raw material has melted. Since the cooling of alumina particles is considered to occur from the surface, crystallization is induced from the surface. As a result, the surface unevenness is considered to become significant, and the smoothness of the alumina particle surface is significantly reduced. That is, when the Ga content is less than 1.0 ppm, due to the high symmetry and the tendency for surface unevenness from the crystal inertia to be significant during crystallization, the content of the α-phase and θ-phase increases, thus making the particle surface unevenness during cooling crystallization significant. Therefore, in the mixing process of alumina particles and resin, the unevenness of the alumina particle surface (caused by low smoothness) becomes a cause of so-called equipment wear, leading to wear on the mixing equipment. Furthermore, the fluidity of the resin composition is significantly reduced.

[0053] If the gallium content exceeds 60.0 ppm, the thermal conductivity tends to decrease due to the reduced content of α and θ phases, making it difficult to achieve both excellent thermal conductivity and good wear resistance (low wear resistance to equipment).

[0054] That is, by controlling the Ga content in the alumina particles within an appropriate range, the ratio of the α phase, δ phase, and θ phase is appropriately controlled, resulting in a balance between exceptionally good thermal conductivity and low wear resistance.

[0055] To achieve both the aforementioned characteristics (low risk of equipment wear and excellent thermal conductivity), conventional cooling processes during particle manufacturing, such as rapid cooling with dry ice, have proven extremely difficult. Surprisingly, this invention creates particles that combine these characteristics (low risk of equipment wear and excellent thermal conductivity) by controlling the Ga content.

[0056] [Methods for determining Ga content]

[0057] The determination of Ga content uses ICP-MS, which ensures the quantification of trace components (ppm level). In ICP-MS determination, the sample needs to be dissolved to prepare a solution. However, since alumina is a difficult substance to dissolve, it is dissolved using methods such as pressurized acid decomposition. Then, the solution is analyzed using ICP-MS.

[0058] (Average particle size is 0.5 to 30.0 μm)

[0059] In one embodiment of the present invention, the alumina particles have an average particle size of 0.5 to 30.0 μm. If the average particle size is less than 0.5 μm, the particle agglomeration increases, and the lubricity (flowability) of the composition containing the alumina particles, typically a slurry composition and a resin composite composition, may sometimes decrease, which is undesirable. If the average particle size exceeds 10.0 μm, the miscibility with other components in the composition containing the alumina particles, typically a slurry composition and a resin composite composition, may sometimes decrease. The average particle size of the alumina particles can be appropriately adjusted according to the desired use and properties of the composition containing them. Therefore, the lower limit of the average particle size can be 1.0 µm or 3.0 µm. In addition, the upper limit of the average particle size can be 20.0 µm, 15.0 µm, or 10.0 µm. Furthermore, the alumina particles in one embodiment of the present invention can be manufactured based on a melt-blowing method. In the melt-blowing method, the particle size of the melt-blown alumina particles can be adjusted by adjusting the particle size of the raw material used.

[0060] Here, average particle size refers to average particle size (D50), which means the median particle size D50 of the cumulative volume in the volume-based particle size distribution determined by laser diffraction scattering particle size distribution method. Furthermore, the laser diffraction scattering particle size distribution method is a method of determining the particle size distribution by irradiating a dispersion of alumina particles with a laser and determining the particle size distribution based on the intensity distribution pattern of the diffracted / scattered light emitted from the dispersion. In one embodiment of the present invention, a laser diffraction scattering particle size distribution measuring device, "Mastersizer 3000" (manufactured by Malvern), is used. Moreover, the average particle size can also be determined for alumina particle raw materials in the same way.

[0061] (The ratio of the presence of α, θ, and δ phases, determined by X-ray diffraction (XRD) and analyzed by the Ridwald method, is expressed as (α+θ) / δ≧2.0)

[0062] As an embodiment of the present invention, the alumina particles, determined by X-ray diffraction (XRD) and analyzed by the Riedwald method, have an α-phase, θ-phase, and δ-phase ratio that can be expressed as (α+θ) / δ ≥ 2.0. The upper limit of (α+θ) / δ can be 10.0 or less, or preferably 8.0 or less. The lower limit of (α+θ) / δ is preferably 3.0 or more, more preferably 4.0 or more, or even more preferably 5.0 or more.

[0063] By controlling the presence ratio of α-phase, θ-phase, and δ-phase within the above-mentioned range, the presence ratio of α-phase, θ-phase, and δ-phase is appropriately controlled, resulting in a balance between exceptionally good thermal conductivity and low wear resistance.

[0064] [Quantitative methods for α-phase, θ-phase, and δ-phase]

[0065] The α, θ, and δ phases of alumina particles were quantitatively determined by Riedwald analysis of the particle X-ray diffraction data. X-ray diffraction measurements of the alumina particles were performed using a Bruker D2PHASER powder X-ray diffractometer. The obtained X-ray diffraction patterns were analyzed using the Riedwald method to quantify each phase and calculate (α+θ) / δ and θ / δ. The analysis referenced the PDF-4 2020 database (α: 04-004-2852, θ: 01-086-1410, δ: 04-021-8098). Furthermore, the measurement conditions are described below.

[0066] <Measurement Conditions>

[0067] Light source: Cu Kα (=0.1541nm)

[0068] Scanning range: 10~90°

[0069] Scanning speed: 0.02° / s

[0070] In addition, the reliability factor Rwp value, which is used as an indicator of the reliability of the analysis in the Ridwald analysis, is set to be less than 10%.

[0071] (The ratio of the presence of the θ and δ phases, determined by X-ray diffraction (XRD) and analyzed by the Riedwald method, is expressed as θ / δ ≥ 2.0.)

[0072] As an embodiment of the present invention, the alumina particles, determined by X-ray diffraction (XRD) and analyzed by the Riedwald method, have an α-phase, θ-phase, and δ-phase ratio that can be expressed as θ / δ ≥ 2.0. The upper limit of θ / δ can be 10.0 or less, preferably 8.0 or less, and more preferably 6.0 or less. The lower limit of θ / δ is preferably 3.0 or more, more preferably 4.0 or more, and more preferably 5.0 or more.

[0073] By controlling the presence ratio of the α, θ, and δ phases within the aforementioned range, the proportions of the α, θ, and δ phases are appropriately controlled, resulting in a further balance between exceptionally good thermal conductivity and low wear resistance. Furthermore, the θ and δ phases are quantified using the aforementioned quantitative method.

[0074] (Roundness of 0.90 or higher)

[0075] The alumina particles of one embodiment of the present invention can be manufactured based on the melt-blowing method. In the melt-blowing method, the shape of the obtained alumina particles can be adjusted according to the amount of raw material fed into the flame per unit time and the type of fuel gas, and spherical alumina particles can be obtained.

[0076] The term "spherical" encompasses not only particles that are perfectly spherical but also those that are approximately spherical. Specifically, the following steps are used to determine spherical shape: First, photograph the particle as a two-dimensional image. Focusing on the shape of the two-dimensional image (i.e., circular or approximately circular), measure its roundness (circumference of an equivalent circle / circumference of the particle's projected image). Measure the roundness of more than 100 particles and calculate the average. Particles with an average roundness of 0.90 or higher are considered spherical.

[0077] The roundness of spherical alumina particles can also be above 0.90.

[0078] The higher the roundness of the spherical particles, the more it reduces the abrasiveness of compositions containing these alumina particles, typically slurry compositions and resin composite compositions, or improves lubricity (flowability), thereby resulting in a superior user experience (texture). Roundness can be 0.91 or higher, 0.92 or higher, 0.93 or higher, 0.94 or higher, or 0.95 or higher. Theoretically, the upper limit for roundness is 1.0, but from a manufacturing management perspective, it can also be set below 0.98 or 0.97.

[0079] [Methods for determining roundness]

[0080] Roundness can be determined using an electron microscope or optical microscope and an image analysis device, such as the FPIA from Sysmex. Two-dimensional images of the particles are obtained using these devices. The roundness of this two-dimensional image is then determined (circumference of an equivalent circle / circumference of the projected image of the particle). The roundness of more than 100 particles is determined, and the average value is taken as the roundness of that particle.

[0081] (Slurry composition containing gallium-containing aluminum oxide particles)

[0082] According to one embodiment of the present invention, a slurry composition containing gallium-containing alumina particles is provided. Using a composition containing alumina particles and a dispersion medium, a slurry composition can be obtained. The slurry composition can be used in resin composite compositions, etc., as described later. The slurry composition of one embodiment of the present invention can reduce abrasion or improve lubricity (flowability), and furthermore, can yield a resin composite composition with excellent flowability.

[0083] The dispersion medium in the slurry composition can be appropriately adjusted to include water or a known organic solvent, depending on the intended use of the slurry composition. Multiple dispersion media can also be used in combination. Typically, the dispersion medium is a liquid, such as water or an organic solvent. Examples of organic solvents include alkane solvents such as hexane, heptane, octane, and decane; alcohol solvents such as methanol, ethanol, and propanol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and aromatic solvents such as benzene, toluene, ethylbenzene, and xylene. Ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone are preferred.

[0084] In the manufacture of the slurry composition, for example, in addition to gallium-containing alumina particles and a dispersion medium, known dispersants, pigments, fragrances, preservatives, pure water, surfactants, etc., may be added as needed, and compounded by known methods such as mixing.

[0085] The dispersant in the slurry composition may be adjusted appropriately with water or a known organic solvent, depending on the intended use of the slurry composition. Multiple dispersants may also be used in combination.

[0086] Dispersants may include, for example, those containing at least one selected from nonionic and cationic dispersants.

[0087] There are no particular limitations on the nonionic dispersant used; any known nonionic dispersant can be used. Examples include polymers containing polyoxyethylene chains. Examples of polymers containing polyoxyethylene chains include alkyl polyoxyethylene ethers, alkyl polyoxyethylene-polyoxypropylene ethers, alkyl polyoxypropylene-polyoxyethylene ethers, polyoxyethylene-polyoxypropylene ethers (polyoxyethylene-propylene block copolymers), fatty acid polyoxyethylene esters, fatty acid polyoxyethylene sorbitan esters, fatty acid polyoxyethylene sorbitan esters, polyoxyethylene sorbitan monoalkyl ethers, polyoxyethylene alkyl ether sulfates, polyoxyethylene castor oil (hydrogenated castor oil), and ethynylene glycol ethylene oxide adducts. Examples of alkyl polyoxyethylene ethers include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oil-based ether, polyoxyethylene octyl ether, polyoxyethylene cetyl ether, polyoxyethylene octylphenyl ether, and polyoxyethylene nonylphenyl ether. Examples of fatty acid polyoxyethylene sorbitan esters include polyoxyethylene sorbitan monolaurate.

[0088] There are no particular limitations on the cationic dispersant, and any known cationic dispersant can be used. Examples include alkylamine salts, acylamine salts, quaternary ammonium salts, ammonium salts having amide, ester, or ether bonds, imidazoline, imidazoline salts, and amine derivatives. The cationic dispersant can be either a low-molecular-weight compound or a high-molecular-weight compound, but from the viewpoint of dispersibility of alumina particles, a high-molecular-weight compound is preferred. Examples of such high-molecular-weight dispersants include polyethyleneimine, aminoalkyl ester copolymers of (meth)acrylate, polyvinyl imidazoline, polyvinylpyridine derivatives, polyoxyethylene alkylamines, and polyoxyethylene alkylamides. Examples of polyvinylpyridine derivatives include copolymers of vinylpyridine and (meth)acrylate, and copolymers of vinylpyridine and (meth)acrylate with oxyethylene-containing high-molecular-weight compounds. Examples of copolymers of vinylpyridine and (meth)acrylate with oxyethylene-containing high-molecular-weight compounds include copolymers of vinylpyridine and (meth)acrylate with polyoxyethylene. Among these, from the viewpoint of dispersibility of alumina particles, amine-type high-molecular-weight dispersants are preferred.

[0089] In addition, known surface treatment agents can be cited as dispersants. By containing surface treatment agents, the dispersibility of alumina particles in the slurry composition with the dispersion medium, and the dispersibility or affinity of the resin in the resin composite composition are improved. For example, compounds having at least one functional group selected from alkyl such as methyl, ethyl, propyl, butyl, vinyl, ethenyl, propylene, alkenyl, phenyl, amino, phenylamino, acryloyl, methacryl, epoxy, styryl, silane coupling agents, and silazanes can be cited. More preferably, silane coupling agents having SiH, SiOH, SiOR (R is a hydrocarbon group) and silazanes such as hexamethylenedisilazane can be cited.

[0090] Examples of silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. Examples of alkoxysilane compounds include hexyltrimethoxysilane, octyltriethoxysilane, and phenyltriethoxysilane. Examples of silazane compounds include hexamethyldisilazane and trimethylsilane. From the viewpoint of excellent reactivity, silazane compounds are more preferred. Hexamethyldisilazane and trimethylsilane are even more preferred.

[0091] The content of gallium-containing alumina particles in the slurry composition (the total content of such particles when including "inorganic fillers" or "other fillers" described later) can be appropriately adjusted according to the intended use of the slurry composition. Typically, from the viewpoint of enabling the gallium-containing alumina particles of one embodiment of the invention to manifest their effect, the content is 50 to 95 wt%. More preferably, the lower limit is 55 wt%, more preferably 60 wt%, more preferably 65 wt%, and more preferably 70 wt%. More preferably, the upper limit is 93 wt%, more preferably 90 wt%, and more preferably 85 wt%.

[0092] (Inorganic packing)

[0093] Furthermore, in manufacturing the above-mentioned slurry composition and the resin composite composition described later, in addition to the gallium-containing alumina particles as an embodiment of the present invention, other inorganic fillers may be incorporated. Examples of such inorganic fillers include amorphous spherical alumina particles, crystalline spherical silica particles, titanium dioxide particles, magnesium oxide particles, aluminum nitride particles, boron nitride particles, barium titanate particles, calcium titanate particles, carbon fiber, talc, mica, kaolin, calcium oxide, zinc oxide, barium sulfate, calcium sulfate, and alkaline earth basic carbonates (calcium carbonate, magnesium carbonate, etc.). The proportion of the inorganic fillers may be adjusted appropriately according to the intended use of the slurry composition or resin composite composition. Typically, from the viewpoint of enabling the gallium-containing alumina particles of one embodiment of the present invention to exhibit their effects, the ratio may be (weight of gallium-containing alumina particles): (weight of other inorganic fillers) = 5:95 to 90:10.

[0094] (Resin composite composition containing gallium-containing aluminum oxide particles)

[0095] According to one embodiment of the present invention, a resin composite composition containing gallium-containing alumina particles is provided. Using a composition containing gallium-containing alumina particles and resin, a resin composite composition can be obtained.

[0096] For example, using gallium-containing alumina particles, resin composite compositions of semiconductor sealing materials (especially solid sealing materials), interlayer insulating films, etc., can be obtained. Furthermore, by curing these resin composite compositions, resin composites such as sealing materials (cured bodies) and semiconductor packaging substrates can be obtained. In applications such as semiconductor sealing materials, interlayer insulating films, heat sinks, and thermal pastes, by using gallium-containing alumina particles as one embodiment of the present invention, resin composite compositions with excellent thermal conductivity can also be prepared, and therefore can be suitably used.

[0097] In manufacturing the aforementioned resin composite composition, for example, in addition to gallium-containing alumina particles and resin, curing agents, curing accelerators, flame retardants, silane coupling agents, etc., may be added as needed, and the composite is compounded by known methods such as mixing. Then, it is molded into granules, films, etc., depending on the application.

[0098] In addition to the gallium-containing alumina particles and resin, the inorganic filler can also be incorporated into the resin composite composition. The inorganic filler incorporated into the resin composite composition (or slurry composition) may be amorphous spherical alumina particles, crystalline spherical silica particles, titanium dioxide particles, magnesium oxide particles, aluminum nitride particles, boron nitride particles, barium titanate particles, calcium titanate particles, or carbon fibers. The proportion of the inorganic filler can be adjusted appropriately according to the intended use of the resin composite composition, but from the viewpoint of enabling the gallium-containing alumina particles of one embodiment of the present invention to exhibit their effect, it is preferable that (weight of gallium-containing alumina particles): (weight of other inorganic fillers) = 95:5 to 60:40.

[0099] Furthermore, when manufacturing a resin composite by curing the resin composite composition, for example, heat is applied to the resin composite composition to melt it, it is processed into a shape corresponding to the application, and then heat is applied at a higher temperature than when it is melted to completely cure it. In this case, known methods such as transfer molding can be used.

[0100] For example, in the manufacture of semiconductor-related materials such as packaging substrates or interlayer insulating films, known resins can be used as the resin composite composition, but epoxy resins are preferred. There are no particular limitations on the epoxy resin; for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, phenolic resin, cresol-phenolic resin, naphthalene type epoxy resin, phenoxy type epoxy resin, etc., can be used. One of these can be used alone, or two or more with different molecular weights can be used in combination. From the viewpoints of curability and heat resistance, epoxy resins having two or more epoxy groups per molecule are preferred. Specifically, examples include biphenyl-type epoxy resins, phenolic epoxy resins, o-cresol phenolic epoxy resins, epoxy resins obtained by epoxidizing phenolic and aldehyde resins, glycidyl ethers such as bisphenol A, bisphenol F, and bisphenol S, glycidyl ester epoxy resins obtained by reacting polybasic acids such as phthalic acid or dimer acids with epichlorohydrin, linear aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, alkyl-modified polyfunctional epoxy resins, β-naphthol phenolic epoxy resins, 1,6-dihydroxynaphthyl type epoxy resins, 2,7-dihydroxynaphthyl type epoxy resins, dihydroxybiphenyl type epoxy resins, and epoxy resins incorporating halogens such as bromine to impart flame retardancy. Among these epoxy resins having two or more epoxy groups per molecule, bisphenol A type epoxy resins are particularly preferred.

[0101] In addition, for applications other than composite materials used in semiconductor sealing materials, such as prepregs for printed circuit boards and resin composite compositions of various engineering plastics, resins other than epoxy resins can also be used. Specifically, in addition to epoxy resins, examples include silicone resins, phenolic resins, melamine resins, urea-formaldehyde resins, unsaturated polyesters, fluoropolymers, polyimides, polyamide-imides, polyether-imides, and other polyamides; polyesters such as polybutylene terephthalate and polyethylene terephthalate; polyphenylene sulfide, aromatic polyesters, polysulfones, liquid crystal polymers, polyethersulfones, polycarbonates, maleimide-modified resins, ABS resins, AAS (acrylonitrile-acrylic rubber-styrene) resins, and AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resins.

[0102] As a curing agent for resin composite compositions, known curing agents can be used to cure the resin, such as phenolic curing agents. Phenolic curing agents can be used alone, such as phenolic resins, alkylphenolic resins, polyvinylphenols, etc., or in combination of two or more.

[0103] The amount of the phenolic curing agent is preferably in an equivalent ratio (phenolic hydroxyl equivalent / epoxy group equivalent) of 0.1 or more and less than 1.0 to the epoxy resin. This eliminates the residue of unreacted phenolic curing agent and improves moisture absorption and heat resistance.

[0104] From the viewpoint of heat resistance and thermal expansion coefficient, the amount of gallium-containing alumina particles added to the resin composite composition according to one embodiment of the present invention is preferably high, typically suitable at 70% by mass or more and 95% by mass or less, preferably 80% by mass or more and 95% by mass or less, and more preferably 85% by mass or more and 95% by mass or less. This is because if the amount of gallium-containing alumina particles is too small, it is difficult to obtain the effects of improving the strength of the sealing material and suppressing thermal expansion. On the other hand, if the amount is too large, regardless of the surface treatment of the gallium-containing alumina particles, it is easy to cause segregation due to the agglomeration of gallium-containing alumina particles in the composite material, and the viscosity of the composite material also becomes too high, making it difficult to use as a sealing material. In addition, when the "other fillers" are used in conjunction, the preferred amount added to the resin composite composition is the combined amount of gallium-containing alumina particles and "other fillers".

[0105] In addition to resins, additives such as silane coupling agents, curing agents, colorants, and curing delay materials can also be used.

[0106] In addition, regarding silane coupling agents, any known coupling agents can be used, but coupling agents with epoxy functional groups are preferred.

[0107] In addition, using resin composite compositions, heat sinks, heat dissipation pastes, etc., can be obtained.

[0108] In obtaining the heat sink, in addition to gallium-alumina particles and resin, appropriate additives are also added, and the composite is formed using known methods such as mixing. The resulting composite is then molded into a sheet shape using known methods.

[0109] For example, in the manufacture of heat sinks, the resin used as the resin composite composition can be a known resin, specifically including silicone resin, phenolic resin, melamine resin, urea-formaldehyde resin, unsaturated polyester, fluoropolymer, polyimide, polyamide-imide, polyetherimide, and other polyamides; polyesters such as polybutylene terephthalate and polyethylene terephthalate; polyphenylene sulfide, aromatic polyester, polysulfone, liquid crystal polymer, polyethersulfone, polycarbonate, maleimide-modified resin, ABS resin, AAS (acrylonitrile-acrylic rubber-styrene) resin, and AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin. Silicone resin is preferred. There are no particular limitations on the silicone resin; for example, peroxide-cured, addition-cured, condensation-cured, and UV-cured types can be used.

[0110] In addition to resins, additives such as silane coupling agents, curing agents, colorants, and curing delay materials can also be used.

[0111] In obtaining the aforementioned thermal paste, in addition to gallium alumina particles and resin, appropriate additives are also incorporated, and the paste is compounded using known methods such as mixing. Here, the resin used in the thermal paste is also referred to as base oil.

[0112] For example, in the manufacture of thermal paste, the resin used as the resin composite composition can be a known resin, specifically including silicone resin, phenolic resin, melamine resin, urea-formaldehyde resin, unsaturated polyester, fluoropolymer, polyimide, polyamide-imide, polyetherimide and other polyamides; polyesters such as polybutylene terephthalate and polyethylene terephthalate; polyphenylene sulfide, aromatic polyester, polysulfone, liquid crystal polymer, polyethersulfone, polycarbonate, maleimide modified resin, ABS resin, AAS (acrylonitrile-acrylic rubber-styrene) resin, AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin, mineral oil, synthetic hydrocarbon oil, ester oil, polyethylene glycol oil, silicone oil, fluorinated oil, etc.

[0113] In addition to resins, additives such as silane coupling agents, colorants, and thickeners can also be used. Thickeners that can be used include calcium soap, lithium soap, aluminum soap, calcium complex soap, aluminum complex soap, lithium complex soap, barium complex soap, bentonite, urea, PTFE, sodium terephthalate, silica gel, and organo-modified bentonite.

[0114] (Method for manufacturing alumina particles)

[0115] As one embodiment of the present invention, the gallium-containing alumina particles are not particularly limited in their manufacturing method, and can be manufactured by the following method. This manufacturing method is capable of appropriately manufacturing the above-mentioned gallium-containing alumina particles and may include the following steps.

[0116] (1) A process for manufacturing alumina particles by melting at least one of alumina, boehmite, or aluminum hydroxide in a flame and then cooling it, and

[0117] (2) A process of classifying the alumina particles by sieves or the like after the process of manufacturing the alumina particles.

[0118] (1) The process of manufacturing alumina particles involves molten alumina particles (hereinafter also referred to as "raw material") by immersing them in a flame and then cooling them. These raw materials can be immersed in the flame while suspended in a carrier gas. Air, oxygen, propane, etc., can be used as the carrier gas.

[0119] The flame is preferably formed inside a heat-resistant furnace. Preferably, the flame is formed at the top of the furnace, and raw materials are supplied to this flame. The molten alumina particles settle continuously due to gravity and are recovered from the bottom of the furnace. By setting the flame so that it does not form below the raw materials in the furnace, the descending alumina particles are cooled and granulated.

[0120] The area in the upper part of the heat-resistant furnace where the supplied raw materials are melted by flame is called the melting zone, and the area in the lower part of the heat-resistant furnace where the molten alumina particles are cooled is called the cooling zone.

[0121] There are no particular limitations on the method of flame formation. Fuel (known fuels such as propane, LPG, LNG, hydrogen, and ammonia) and combustion-supporting gas (air or oxygen) can be supplied to the molten zone separately through a burner, or a mixture of fuel and combustion-supporting gas can be supplied to the molten zone through a burner, or a mixture of raw materials, fuel, and combustion-supporting gas can be supplied to the molten zone through a burner to form a flame. In particular, from the viewpoint of increasing the maximum flame temperature and increasing the temperature gradient within the heat-resistant furnace, a method of flame formation that supplies a mixture of fuel and combustion-supporting gas or a mixture of raw materials, fuel, and combustion-supporting gas to the molten zone is preferred.

[0122] Furthermore, in the molten zone, if sufficient heat required for melting is applied to the raw material particles, the number of non-spherical irregular particles can be reduced. This allows for adjustment of the bulk density of the alumina particles. Additionally, the roundness and bulk density can be adjusted by varying the amount of fuel gas introduced into the flame per unit time. Moreover, the particle size of the melt-blown alumina particles can be adjusted by changing the particle size of the raw material powder used.

[0123] The raw materials for alumina particles can be at least one of alumina, boehmite, or aluminum hydroxide. When these raw materials are introduced into a flame, the alumina remains in its alumina state, while the boehmite or aluminum hydroxide forms alumina through oxidation or dehydration reactions.

[0124] In the cooling zone, refrigerants can also be used. There are no particular restrictions on the refrigerant, but from the viewpoint of not reducing the purity of the alumina particles, distilled water or ion-exchanged water that does not contain air or impurities such as sodium ions or chloride ions is preferred.

[0125] In the grading process of (2), a sieve with a specified mesh size can be used to appropriately grade the alumina particles obtained in the alumina particle manufacturing process. Additional pre-treatment or post-treatment, such as separating them into coarse / fine particles using a cyclone separator, may also be added as needed. Through this process, the desired particle size, particle size distribution, specific surface area, and bulk density can be obtained.

[0126] As an embodiment of the present invention, the gallium-containing alumina particles can be obtained as long as the state of alumina particles having the Ga content specified in the present invention can be obtained in the above-described (1) process.

[0127] For example, the raw material of alumina particles may have the Ga content specified in one embodiment of the present invention. Alternatively, a Ga source such as gallium oxide or gallium hydroxide may be added at the same time as the raw material is put into the flame.

[0128] Example

[0129] An embodiment of the present invention will be described through the following examples and comparative examples. However, an embodiment of the present invention is not limited to the following examples and is not intended to be construed as such.

[0130] Alumina particles containing a specified amount of gallium were fed into a flame formed by LPG and oxygen, i.e., alumina particles were manufactured by melt-blowing. The average particle size of the alumina particles was adjusted by controlling the particle size of the fed alumina particles. Furthermore, the flame formation conditions, particle size of the raw material, raw material supply rate, and grading conditions were adjusted to manufacture gallium-containing alumina particles with the physical properties shown in Table 1. The physical properties of the obtained alumina particles are shown in Table 1.

[0131] [Table 1]

[0132]

[0133] The methods for determining each physical property value are described below.

[0134] [Average Particle Size]

[0135] The average particle size (D50) was determined using a laser diffraction / scattering particle size distribution measuring device, the "Mastersizer 3000" (manufactured by Malvern).

[0136] [Methods for determining Ga content]

[0137] The Ga content was determined by ICP-MS. To dissolve the alumina, the sample was prepared by pressurized acid decomposition. The Ga content was then determined by ICP-MS.

[0138] [Quantitative methods for α-phase, θ-phase, and δ-phase]

[0139] The quantification of the α, θ, and δ phases of the alumina particles described in the Examples and Comparative Examples was performed using Riedwald analysis of the particle X-ray diffraction data. X-ray diffraction measurements of the alumina particles were conducted using a Bruker D2PHASER powder X-ray diffractometer. The obtained X-ray diffraction patterns were analyzed using the Riedwald method to quantify each phase and calculate (α+θ) / δ and θ / δ. The analysis referenced the database PDF-4 2020 (α: 04-004-2852, θ: 01-086-1410, δ: 04-021-8098). Furthermore, the measurement conditions are as follows.

[0140] <Measurement Conditions>

[0141] Light source: Cu Kα (=0.1541nm)

[0142] Scanning range: 10~90°

[0143] Scanning speed: 0.02° / s

[0144] In addition, in the Ridwald analysis, the reliability factor Rwp value used as an indicator of reliability for the analysis was less than 10%.

[0145] [Methods for evaluating thermal conductivity]

[0146] The alumina particles described in the examples and comparative examples, Mitsubishi Chemical's biphenyl epoxy resin "YX-4000H", and Shikoku Chemical Industry Co., Ltd.'s "2-ethyl-4-methylimidazolium" as the curing agent were weighed into a metal dish in a mass ratio of 80:15:5. The mixture was heated and kneaded on a heating plate set to 175°C until homogeneous. This state was maintained for 5 hours to produce a 5 mm thick sheet-like resin composite composition. The sheet-like resin composition, cooled in a constant temperature bath at 25°C, was placed on a heating plate heated to 100°C. Thermal conductivity was evaluated by the time it took for the surface not in contact with the heating plate to reach 80°C. The group with the shortest time to reach 80°C was denoted as ◎, the next shortest as ○, the next shortest as △, and the longest as ×. ◎ indicates particularly excellent thermal conductivity. Furthermore, industrially, a value between ○ and △ indicates sufficiently excellent thermal conductivity.

[0147] [Method for determining the hardness of the composition]

[0148] The alumina particles described in the examples and comparative examples and the biphenyl-based epoxy resin "YX-4000H" manufactured by Mitsubishi Chemical were weighed into a metal dish at a mass ratio of 4:1. The mixture was heated and kneaded on a heating plate set to 175°C until it became homogeneous. The mixture was cooled in a constant temperature bath at 25°C to prepare a sheet-like resin composite composition with a thickness of 5 mm. The hardness of the sheet-like resin composition was measured using an ASKER TYPE E hardness tester for evaluation of abrasion resistance. The group with the lowest hardness was marked with ◎, the next lowest with ○, the next lowest with △, and the highest with ×. ◎ indicates particularly low abrasion resistance, which can be considered excellent in industrial applications. In addition, if the hardness is ○ to △, it can be said that the thermal conductivity is sufficiently excellent in industrial applications.

[0149] [Roundness]

[0150] Roundness was determined using an electron microscope or optical microscope and an image analysis device. In this example and comparative example, an FPIA device manufactured by Sysmex was used. These devices were used to determine the roundness of the particles (circumference of an equivalent circle / circumference of a projected image of the particle). The roundness of more than 100 particles was measured, and the average value was taken as the roundness of the powder.

[0151] Industrial availability

[0152] The alumina particles of one embodiment of the present invention exhibit excellent thermal conductivity and a high level of surface smoothness. In another embodiment, a slurry composition and a resin composite composition containing alumina particles are also provided, which, based on the properties of the alumina particles, can achieve excellent thermal conductivity, wear resistance (less wear on equipment), and other effects.

Claims

1. A gallium-containing aluminum oxide particle, characterized in that, The average particle size is 0.5~30.0 μm, and the gallium content determined by inductively coupled plasma mass spectrometry (ICP-MS) is 1.0~60.0 ppm.

2. The gallium-containing aluminum oxide particles as described in claim 1, The ratio of the presence of α, θ, and δ phases, determined by X-ray diffraction (XRD) and analyzed by the Riedwald method, is expressed as (α+θ) / δ≧2.

0.

3. The gallium-containing aluminum oxide particles as described in claim 1, The ratio of the presence of the θ and δ phases, determined by X-ray diffraction (XRD) and analyzed by the Riedwald method, is expressed as θ / δ≧2.

0.

4. The gallium-containing aluminum oxide particles as described in claim 1, Roundness is 0.90 or higher.

5. A slurry composition, characterized in that, It contains gallium-containing aluminum oxide particles as described in any one of claims 1 to 4.

6. The slurry composition as described in claim 5, It also contains at least one inorganic filler selected from amorphous spherical alumina particles, crystalline spherical silica particles, titanium dioxide particles, magnesium oxide particles, aluminum nitride particles, boron nitride particles, barium titanate particles, calcium titanate particles, carbon fiber, talc, mica, kaolin, calcium oxide, zinc oxide, barium sulfate, calcium sulfate, and alkaline earth basic carbonates. The basic carbonates of the alkaline earth family include calcium carbonate and magnesium carbonate.

7. A resin composite composition, characterized in that, It contains gallium-containing aluminum oxide particles as described in any one of claims 1 to 4.

8. The resin composite composition as described in claim 7, It also contains at least one inorganic filler selected from amorphous spherical alumina particles, crystalline spherical silica particles, titanium dioxide particles, magnesium oxide particles, aluminum nitride particles, boron nitride particles, barium titanate particles, calcium titanate particles, carbon fiber, talc, mica, kaolin, calcium oxide, zinc oxide, barium sulfate, calcium sulfate, and alkaline earth basic carbonates. The basic carbonates of the alkaline earth family include calcium carbonate and magnesium carbonate.

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