Spherical alumina powder, resin composition, semiconductor encapsulation material

Abstract

The purpose of the present invention is to provide a practical spherical alumina powder that exhibits excellent fluidity.　The present invention is a spherical alumina power that has a first maximum peak and a second maximum peak from the small-diameter side in the grain size measured by a laser-diffraction-scattering-type grain size distribution measurement instrument, such that a first maximum particle diameter showing the first maximum peak is within the range of 3-9 μm, a second maximum particle diameter showing the second maximum peak is within the range of 30-50 μm, and the cumulative value of the frequency of each particle diameter in five points obtained by dividing the range from the second maximum particle diameter-10 μm to the second maximum particle diameter+10 μm into four equal parts is 25-45 vol%.

Description

Technical Field

[0001] The present invention relates to spherical alumina powder, a resin composition, and a semiconductor encapsulating material.

Background Art

[0002] In recent years, in response to the demands for miniaturization, light weight, and high performance of electronic devices, the miniaturization, thinning, and narrow pitch of semiconductor packages have been rapidly accelerating. Also, the surface mounting suitable for high-density mounting on wiring boards and the like has become the mainstream of the mounting method. Thus, as semiconductor packages and their mounting methods have advanced, functional improvements have also been required for semiconductor encapsulating materials, and research has been intensively conducted on highly filling epoxy resins with ceramic powders, particularly spherical alumina powder. The problem with highly filling ceramic powders is that it increases the viscosity of the material and increases molding defects such as unfilled, wire flow, wire cutting, and chip shift.

[0003] To solve this, improvements have been made from the resin side and from the ceramic powder side. Improvements from the ceramic powder side include, for example, a method of increasing the sphericity of Wardell to 0.7 - 1.0 (Patent Document 1), a method of setting the gradient of the straight line shown in the Rosin-Rammler diagram to 0.6 - 0.95 and widening the particle size distribution (Patent Document 2), a method of providing several peaks in the particle size distribution to form a multimodal particle size distribution and approaching the closest packing structure of the ceramic powder (Patent Document 3), etc., but they are still insufficient. When the filling rate is increased, the viscosity of the material rapidly increases.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a practical spherical alumina powder showing good fluidity. [Means for Solving the Problems]

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the following present invention, and have completed the present invention. That is, the present invention is as follows.

[0007] [1] In the particle size distribution measured by a laser diffraction / scattering particle size distribution analyzer, having a first maximum peak and a second maximum peak from the small diameter side, the first maximum particle diameter indicating the first maximum peak is in the range of 3 to 9 μm, the second maximum particle diameter indicating the second maximum peak is in the range of 30 to 50 μm, and the cumulative value of the frequency of each particle diameter at five points obtained by equally dividing the range from the second maximum particle diameter - 10 μm to the second maximum particle diameter + 10 μm into four equal parts is 25 to 45% by volume. A spherical alumina powder. [2] The spherical alumina powder according to [1], wherein the cumulative value of the frequency in the peak range having the second maximum peak is 55% by volume or more. [3] The spherical alumina powder according to [1] or [2], wherein the cumulative value of the frequency in the peak range having the first maximum peak is 35% by volume or less. [4] The spherical alumina powder according to any one of [1] to [3], wherein the frequency at the first maximum particle diameter - 1 μm and the frequency at the first maximum particle diameter + 1 μm are each 50% or more of the frequency at the first maximum particle diameter. [5] The spherical alumina powder according to any one of [1] to [4], wherein the content of particles having a particle diameter of 55 μm or more is 0.1% by mass or less. [6] A resin composition containing a resin and the alumina powder according to any one of [1] to [5]. [7] A semiconductor encapsulating material containing the resin composition according to [6]. [Advantages of the Invention]

[0008] According to the present invention, it is possible to provide spherical alumina powder that exhibits good fluidity and is practical. [Embodiments for Carrying Out the Invention]

[0009] In the particle size distribution measured by a laser diffraction / scattering particle size distribution analyzer, the spherical alumina powder of the present invention has a first maximum peak and a second maximum peak from the smaller diameter side. The first maximum particle diameter indicating the first maximum peak is in the range of 3 to 9 μm, the second maximum particle diameter indicating the second maximum peak is in the range of 30 to 50 μm, and the cumulative value of the frequency of each particle diameter at five points obtained by equally dividing the range from the second maximum particle diameter - 10 μm to the second maximum particle diameter + 10 μm into four equal parts is 25 to 45% by volume.

[0010] As described above, the present invention sets the first maximum particle diameter indicating the first maximum peak and the second maximum particle diameter indicating the second maximum peak of the spherical alumina powder having the first maximum peak and the second maximum peak from the smaller diameter side within a predetermined range, respectively, and by defining the shape of the second maximum peak, a further improvement effect in fluidity can be obtained compared to the prior art.

[0011] The reason for obtaining the above improvement effect in fluidity is presumed as follows. Usually, when the powder is in a densely packed state, a liquid bridge is formed between the powder particles due to the influence of moisture in the atmosphere. When a liquid bridge is formed, the viscosity increases and the fluidity when made into a resin composition decreases. Based on such a phenomenon, in the present invention, the spherical alumina powder within the first maximum peak with a smaller diameter is present between and in the gaps of the spherical alumina powder particles within the second maximum peak with a larger particle diameter than this, so it is presumed that the liquid bridge is suppressed and high fluidity is exhibited even when the powder is in a dense state. Hereinafter, embodiments (this embodiment) of the present invention will be described in detail. [Spherical Alumina Powder] The spherical alumina powder according to this embodiment has a first maximum peak and a second maximum peak in the particle size distribution measured by a laser diffraction / scattering particle size distribution analyzer. By having at least multimodality with the first maximum peak and the second maximum peak, spherical alumina powder with a large particle size (spherical alumina powder within the second maximum peak) can easily enter between particles and gaps of spherical alumina powder with a small particle size (spherical alumina powder within the first maximum peak), making it easier to obtain close packing. Also, as described above, liquid crosslinking is suppressed by the spherical alumina powder within the first maximum peak, resulting in a practical spherical alumina powder.

[0012] Here, the first maximum particle diameter indicating the first maximum peak is in the range of 3 to 9 μm, preferably in the range of 4 to 8 μm. If the first maximum particle diameter is outside the range of 3 to 9 μm, the liquid crosslinking suppression effect is reduced, the viscosity of the resin composition containing the spherical alumina powder increases, and the spiral flow decreases. The second maximum particle diameter indicating the second maximum peak is in the range of 30 to 50 μm, preferably in the range of 35 to 48 μm. If the second maximum particle diameter is outside the range of 30 to 50 μm, the rolling resistance increases, the viscosity of the resin composition containing the spherical alumina powder increases, and the spiral flow decreases. As described above, the first maximum peak and the second maximum peak are measured by a laser diffraction / scattering particle size distribution analyzer. Specifically, they can be measured and calculated by the method described in the examples.

[0013] The cumulative value of the frequency of each particle size at five points obtained by equally dividing the range from the second maximum particle size - 10 μm to the second maximum particle size + 10 μm (i.e., the particle sizes of the second maximum particle size - 10 μm, the second maximum particle size - 5 μm, the second maximum particle size, the second maximum particle size + 5 μm, and the second maximum particle size + 10 μm) is 25 to 45% by volume, preferably 34 to 41% by volume. That the cumulative value is within the above range means that the second maximum peak has a sharper shape compared to the first maximum peak. And by having such a shape, good fluidity with reduced rolling resistance can be obtained. Conversely, if the above cumulative value is outside the range of 25 to 45% by volume, it becomes difficult to obtain good fluidity.

[0014] The frequency at the first maximum particle size - 1 μm and the frequency at the first maximum particle size + 1 μm are each preferably 50% or more of the frequency at the first maximum particle size, more preferably 70 to 95%. By being 50% or more of the frequency at the first maximum particle size as described above, the second maximum peak becomes broad. In such a broad state, the spherical alumina contributing to liquid bridge reduction has a larger variation in particle size, and it becomes easier to uniformly exist from small gaps to large gaps between the spherical alumina powders within the second maximum peak, and as a result, better fluidity can be obtained.

[0015] The cumulative value of the frequency of the particle size range in the peak range having the first maximum peak is preferably 35% by volume or less, more preferably 15 to 30%. By the cumulative value of the frequency being 35% by volume or less, good fluidity and viscosity can be achieved.

[0016] Also, the cumulative value of the frequency of the particle size range in the peak range having the second maximum peak is preferably 55% by volume or more, more preferably 65 to 85%. By the cumulative value of the frequency being 65% by volume or more, good fluidity and viscosity can be achieved.

[0017] The spherical alumina powder according to this embodiment preferably has a particle content of 55 μm or more of 0.1% by mass or less, and more preferably 0.05% or less. When the particle content is 0.1% by mass or less, the injectability into fine spaces such as between wires and between elements can be improved. In order to make the particle content of particles with a particle size of 55 μm or more 0.1% by mass or less, it may be adjusted by classification treatment by sieving.

[0018] Here, the range of the peak having the first maximum peak is the range from the particle size detected from the measurement lower limit to the particle size at which the frequency shows the minimum value through the first maximum peak. Further, the range of the peak having the second maximum peak refers to the range from the above minimum value to 55 μm through the second maximum peak. Also, the diameter at which the frequency becomes maximum within the above range is the maximum particle diameter.

[0019] The average particle diameter of the spherical alumina powder according to this embodiment is preferably 20 to 40 μm, and more preferably 25 to 35 μm. When the average particle diameter is 20 to 40 μm, an increase in viscosity can be prevented and the spiral flow can be brought into a good range. Here, the above average particle diameter is the volume-based cumulative 50% diameter (D50) measured by a laser diffraction scattering particle size distribution measuring machine, and can be measured and calculated by the method described in the examples.

[0020] The average sphericity of the spherical alumina powder according to this embodiment is preferably 0.9 or more, and more preferably 0.92 or more. When the average sphericity is 0.9 or more, an increase in viscosity can be prevented and the spiral flow can be brought into a good range. Here, the above average sphericity can be measured and calculated by the method described in the examples.

[0021] Also, the specific surface area is preferably 0.25 to 0.45 m 2 / g, and more preferably 0.3 to 0.4 m 2 / g. When the specific surface area is 0.25 to 0.45 m 2By being / g, an increase in viscosity can be prevented and the spiral flow can be brought into a good range. Here, the specific surface area is a value based on the BET method and can be measured and calculated by the BET single-point method.

[0022] In this embodiment, the cumulative value up to 10 μm is preferably 10 to 35% by volume, more preferably 15 to 30% by volume. By being 10 to 35% by volume, an increase in viscosity can be prevented and the spiral flow can be brought into a good range. The cumulative value up to 10 μm is measured with a laser diffraction / scattering particle size distribution analyzer.

[0023] The spherical alumina powder according to this embodiment can be produced, for example, as follows. First, the alumina raw material powder as a raw material is preferably alumina powder or aluminum hydroxide powder. Then, the alumina raw material powder having an average particle size substantially the same as the desired first maximum particle size is put into a high-temperature flame formed by a fuel gas such as hydrogen, natural gas, acetylene gas, propane gas, butane, LPG, etc., and melted and spheroidized to produce a first spherical alumina powder. Similarly, a second spherical alumina powder is produced by melting and spheroidizing the alumina raw material powder having an average particle size substantially the same as the desired second maximum particle size. Note that the average sphericity and specific surface area of the spherical alumina powder can be adjusted by controlling at least any one of the furnace temperature in which the high-temperature flame is formed, the particle size of the alumina raw material powder, and the input amount.

[0024] Next, the particle size distribution of the first spherical alumina powder is adjusted to a desired range using a sieve or a precision air classifier, etc. Similarly, the particle size distribution of the second spherical alumina powder is also adjusted to a desired range using a sieve or a precision air classifier, etc. The desired range at this time refers to a range in which the cumulative value of the frequency of each of the five particle diameters obtained by dividing the range from the second maximum particle diameter - 10 μm to the second maximum particle diameter + 10 μm into four equal parts is 25 to 45% by volume, the frequency at the first maximum particle diameter - 1 μm, and the frequency at the first maximum particle diameter + 1 μm are each 50% or more of the frequency at the first maximum particle diameter, and the like. In addition, by adjusting the feed amount and the like in precision air classification, the peak shape of the particle size distribution can be made sharp or broad.

[0025] Thereafter, the spherical alumina powder according to the present embodiment can be obtained by mixing the first spherical alumina powder and the second spherical alumina powder at a volume ratio of 5:95 to 25:75.

[0026] [Resin composition, semiconductor encapsulating material] The resin composition according to the present invention contains a resin and the alumina powder of the present invention described above. Further, the semiconductor encapsulating material according to the present invention contains the resin composition of the present invention described above.

[0027] Examples of the resin that can be used include polyamides such as epoxy resin, silicone resin, phenol resin, melamine resin, urea resin, unsaturated polyester, fluororesin, polyimide, polyamideimide, polyetherimide, etc., polyesters such as polybutylene terephthalate and polyethylene terephthalate, polyphenylene sulfide, wholly 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, and the like.

[0028] Among these, as the resin for semiconductor encapsulation materials, an epoxy resin having two or more epoxy groups in one molecule is preferable. For example, a phenol novolac type epoxy resin, an ortho-cresol novolac type epoxy resin, an epoxy resin obtained by epoxidizing a novolac resin of phenols and aldehydes, glycidyl ethers such as bisphenol A, bisphenol F, and bisphenol S, a glycidyl ester acid epoxy resin obtained by reacting a polybasic acid such as phthalic acid or dimer acid with epichlorohydrin, a linear aliphatic epoxy resin, an alicyclic epoxy resin, a heterocyclic epoxy resin, an alkyl-modified polyfunctional epoxy resin, a β-naphthol novolac type eoxy resin, a 1,6-dihydroxynaphthalene type epoxy resin, a 2,7-dihydroxynaphthalene type epoxy resin, a biphenyl type epoxy resin, and further an epoxy resin into which a halogen such as bromine is introduced to impart flame retardancy, etc. can be mentioned. Among them, from the viewpoints of moisture resistance and solder reflow resistance, an ortho-cresol novolac type epoxy resin, a biphenyl type epoxy resin, an epoxy resin having a naphthalene skeleton, etc. are suitable.

[0029] As the curing agent for the epoxy resin, for example, a novolac type resin obtained by reacting one or a mixture of two or more selected from the group of phenol, cresol, xylenol, resorcinol, chlorophenol, t-butylphenol, nonylphenol, isopropylphenol, octylphenol, etc. with formaldehyde, paraformaldehyde or paraxylene under an oxidation catalyst, a poly(para-hydroxystyrene) resin, a bisphenol compound such as bisphenol A and bisphenol S, trifunctional phenols such as pyrogallol and phloroglucinol, acid anhydrides such as maleic anhydride, phthalic anhydride and pyromellitic anhydride, aromatic amines such as metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and phenol aralkyl resins such as phenol aralkyl resins having a biphenylene skeleton can be mentioned. In order to accelerate the reaction between the epoxy resin and the curing agent, a curing accelerator such as triphenylphosphine, 1,8-diazabicyclo(5,4,0)undecene-7, etc. can be used.

[0030] The resin composition or semiconductor encapsulating material of the present invention may contain the following components as required. That is, as the low-stress agent, rubbery substances such as silicone rubber, polysulfide rubber, acrylic rubber, butadiene rubber, styrene block copolymer, and saturated elastomer, various thermoplastic resins, resinous substances such as silicone resin, and further resins obtained by modifying part or all of epoxy resin and phenolic resin with aminosilicone, epoxysilicone, alkoxysilicone, etc. can be mentioned. Examples of the silane coupling agent include epoxy silanes such as γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, amino silanes such as aminopropyltriethoxysilane, ureidopropyltriethoxysilane, phenylamino silane, and N-phenylaminopropyltrimethoxysilane, hydrophobic silane compounds such as phenyltrimethoxysilane, methyltrimethoxysilane, octadecyltrimethoxysilane, and mercapto silane. Examples of the surface treatment agent include Zr chelate, titanate coupling agent, aluminum-based coupling agent, etc. Examples of the flame retardant include halogenated epoxy resin and phosphorus compound, etc., and examples of the colorant include carbon black, iron oxide, dye, pigment, etc. Examples of the flame retardant aid include Sb2O3, Sb2O4, Sb2O5, etc. Examples of the release agent include natural waxes, synthetic waxes, metal salts of linear fatty acids, acid amides, esters, paraffin, etc.

[0031] The content of the spherical alumina powder of the present invention in the resin composition or semiconductor encapsulating material is preferably 50 to 95% by mass. By being in the above range, functions such as heat resistance and thermal conductivity can be imparted.

[0032] The resin composition or semiconductor encapsulating material of the present embodiment can be produced by blending a predetermined amount of each of the above materials using a blender, a Henschel mixer, etc., kneading the blend using a heating roll, a kneader, a single-screw or twin-screw extruder, etc., cooling the kneaded product, and then appropriately pulverizing it.

[0033] In addition, in order to encapsulate a semiconductor using the semiconductor encapsulating material of the present embodiment, conventional molding means such as transfer molding and multi-plunger are employed.

Examples

[0034] Hereinafter, the present invention will be described more specifically using examples and comparative examples. However, the present invention is not limited to the following examples as long as the gist thereof is not deviated from.

[0035] [Example 1] (Production of the first spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, spheroidized, and then classified by cyclone classification to obtain alumina powder with an average sphericity of 0.92 and an average particle diameter of 4 μm.

[0036] (Production of the second spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, spheroidized, and then classified by cyclone classification to obtain alumina powder with an average sphericity of 0.92 and an average particle diameter of 35 μm. The average particle diameter and average sphericity were measured as follows (the same applies to the following examples and comparative examples).

[0037] (Method for measuring the average particle diameter) The average particle diameter (volume basis) of the spherical alumina powder was measured by the laser diffraction scattering method (Microtrac (manufactured by Nikkiso Co., Ltd., product name "MT3300EX II")).

[0038] (Method for measuring the average sphericity) The average sphericity of the spherical alumina powder was measured as follows using a flow-type particle image analyzer with the product name "FPIA-3000" manufactured by Sysmex Corporation. The projected area (A) and perimeter (PM) of the particles were measured from the particle images. Assuming the area of a perfect circle corresponding to the perimeter (PM) is (B), the sphericity of the particle can be expressed as A / B. Therefore, assuming a perfect circle with the same perimeter as the perimeter (PM) of the sample particles, PM = 2πr and B = πr 2 so B = π × (PM / 2π) 2 and the sphericity of each particle can be calculated as circularity = A / B = A × 4π / (PM) 2 This was measured for 100 or more randomly selected particles, and the average value squared was defined as the average sphericity. The measurement solution was prepared by adding 20 ml of distilled water and 10 ml of propylene glycol to 0.1 g of the sample and performing ultrasonic dispersion treatment for 3 minutes.

[0039] The first spherical alumina powder and the second spherical alumina powder were mixed at a volume ratio of 25:75 to prepare the spherical alumina powder of Example 1 (average particle diameter 33 μm, specific surface area 0.32 m 2 / g, cumulative value up to 10 μm 20% by volume). The particle size distribution (particle diameter and frequency) of the spherical alumina powder of Example 1 was measured by the laser diffraction scattering method. The Microtrac mentioned above was used as the particle size distribution measuring instrument for the measurement. The results are shown in Table 1 below.

[0040] 89 parts by mass of the above-prepared spherical alumina powder, 5.5 parts by mass of a biphenyl-type epoxy resin (YX-4000HK manufactured by Japan Epoxy Resin Co., Ltd.), 4.8 parts by mass of a phenolic resin (MEHC-7800S manufactured by Meiwafosis Co., Ltd.), 0.15 parts by mass of triphenylphosphine (TPP manufactured by Hokko Chemical Industry Co., Ltd.), and 0.35 parts by mass of phenylaminosilane (KBM-573 manufactured by Shin-Etsu Chemical Co., Ltd.) were dry-blended using a Henschel mixer, and then heat-kneaded using a co-rotating twin-screw extruder (screw diameter D = 25 mm, L / D = 10.2, paddle rotation speed 50 to 120 rpm, discharge rate 3.0 kg / Hr, kneaded product temperature 98 to 100 °C) to obtain a resin composition. For the prepared resin composition, the spiral flow (fluidity) was carried out as follows. Note that the spiral flow is preferably 100 cm or more. For the viscosity measurement, the above-prepared spherical alumina powder was put into a bisphenol F-type liquid epoxy resin (epoxy equivalent 169, Epicoat 807; manufactured by Mitsubishi Chemical Corporation) so as to be 65% by volume (88.1% by mass) in the resin composition, and then stirring and defoaming treatment were carried out to prepare a resin composition for viscosity measurement. The results are shown in Table 1. Note that the viscosity is preferably 100 Pa·s or less.

[0041] (Fluidity) Using a spiral flow mold and in accordance with EMMI-66 (Epoxy Molding Material Institute; Society of Plastic Industry), the fluidity of the resin composition was evaluated. Note that the mold temperature was 175 °C, the molding pressure was 7.4 MPa, and the holding pressure time was 90 seconds.

[0042] (Viscosity) Using a B-type viscometer (trade name "TVB-10" manufactured by Toki Sangyo Co., Ltd.), the viscosity of the resin composition for viscosity measurement was measured at a temperature of 30 °C and a rotation speed of 10 rpm The viscosity of the resin composition for viscosity measurement was measured at a rotation speed of.

[0043] [Example 2] (Preparation of the First Spherical Alumina Powder) Alumina powder was introduced into the flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 4 μm.

[0044] (Production of the second spherical alumina powder) Alumina powder was introduced into the flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 38 μm.

[0045] The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 25:75 to produce the spherical alumina powder of Example 2 (average particle size 31 μm, specific surface area 0.30 m 2 / g, cumulative value up to 10 μm 17% by volume).

[0046] Using the spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the produced resin composition was measured for spiral flow (fluidity) and viscosity. The results are shown in Table 1 below.

[0047] [Example 3] (Production of the first spherical alumina powder) Alumina powder was introduced into the flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 8 μm.

[0048] (Production of the second spherical alumina powder) Alumina powder was introduced into the flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 33 μm.

[0049] The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 25:75 to produce the spherical alumina powder of Example 3 (average particle size 32 μm, specific surface area 0.31 m 3Cumulative value up to 10 μm was 23% by volume and it was produced.

[0050] Using the spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the produced resin composition was measured for spiral flow (fluidity) and viscosity. The results are shown in Table 1 below.

[0051] [Example 4] (Production of the first spherical alumina powder) Alumina powder was introduced into the flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 4 μm.

[0052] (Production of the second spherical alumina powder) Alumina powder was introduced into the flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 43 μm.

[0053] The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 25:75 to produce the spherical alumina powder of Example 4 (average particle size 32 μm, specific surface area 0.32 m 2 / g, cumulative value up to 10 μm was 24% by volume).

[0054] Using the spherical alumina powder, a resin composition was produced in the same manner as in Example 1, and the produced resin composition was measured for spiral flow (fluidity) and viscosity. The results are shown in Table 1 below.

[0055] [Example 5] (Production of the first spherical alumina powder) Alumina powder was introduced into the flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

[0056] (Production of the second spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle diameter of 36 μm.

[0057] The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 35:65 to prepare the spherical alumina powder of Example 5 (average particle diameter 29 μm, specific surface area 0.38 m 2 / g, cumulative value up to 10 μm 28% by volume).

[0058] Using the spherical alumina powder, a resin composition was prepared in the same manner as in Example 1, and the spiral flow (fluidity) and viscosity of the prepared resin composition were measured. The results are shown in Table 1 below.

[0059] [Example 6] (Preparation of the first spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle diameter of 5 μm.

[0060] (Preparation of the second spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was performed to obtain alumina powder with an average sphericity of 0.92 and an average particle diameter of 36 μm.

[0061] The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 20:80 to prepare the spherical alumina powder of Example 6 (average particle diameter 36 μm, specific surface area 0.30 m 2 / g, cumulative value up to 10 μm 15% by volume).

[0062] Using the spherical alumina powder, a resin composition was prepared in the same manner as in Example 1, and the spiral flow (fluidity) and viscosity of the prepared resin composition were measured. The results are shown in Table 1 below.

[0063] [Comparative Example 1] (Preparation of the first spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, spheroidized, and then classified by cyclone classification to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 2 μm.

[0064] (Preparation of the second spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, spheroidized, and then classified by cyclone classification to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 36 μm.

[0065] The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 25:75 to prepare the spherical alumina powder of Comparative Example 1 (average particle size 33 μm, specific surface area 0.40 m 2 / g, cumulative value up to 10 μm 20% by volume).

[0066] Using the spherical alumina powder, a resin composition was prepared in the same manner as in Example 1, and the spiral flow (fluidity) and viscosity of the prepared resin composition were measured. The results are shown in Table 1 below.

[0067] [Comparative Example 2] (Preparation of the first spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, spheroidized, and then classified by cyclone classification to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 10 μm.

[0068] (Preparation of the second spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, spheroidized, and then classified by cyclone classification to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 43 μm.

[0069] The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 25:75 to prepare the spherical alumina powder of Comparative Example 2 (average particle size 36 μm, specific surface area 0.27 m 2 / g, cumulative value up to 10 μm 15% by volume).

[0070] Using the spherical alumina powder, a resin composition was prepared in the same manner as in Example 1, and the prepared resin composition was measured for spiral flow (fluidity) and viscosity. The results are shown in Table 1 below.

[0071] [Comparative Example 3] (Preparation of the first spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, subjected to a spheroidization treatment, and then subjected to a classification treatment by cyclone classification to obtain an alumina powder having an average sphericity of 0.92 and an average particle size of 5 μm.

[0072] (Preparation of the second spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, subjected to a spheroidization treatment, and then subjected to a classification treatment by cyclone classification to obtain an alumina powder having an average sphericity of 0.92 and an average particle size of 28 μm.

[0073] The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 25:75 to prepare the spherical alumina powder of Comparative Example 3 (average particle size 26 μm, specific surface area 0.30 m 2 / g, cumulative value up to 10 μm 22% by volume).

[0074] Using the spherical alumina powder, a resin composition was prepared in the same manner as in Example 1, and the prepared resin composition was measured for spiral flow (fluidity) and viscosity. The results are shown in Table 1 below.

[0075] [Comparative Example 4] (Preparation of the first spherical alumina powder) Alumina powder was introduced into the flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was carried out to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

[0076] (Preparation of the second spherical alumina powder) Alumina powder was introduced into the flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was carried out to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 51 μm.

[0077] The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 25:75 to prepare the spherical alumina powder of Comparative Example 4 (average particle size 38 μm, specific surface area 0.29 m 2 / g, cumulative value up to 10 μm 23% by volume).

[0078] Using the spherical alumina powder, a resin composition was prepared in the same manner as in Example 1, and the prepared resin composition was measured for spiral flow (fluidity) and viscosity. The results are shown in Table 1 below.

[0079] [Comparative Example 5] (Preparation of the first spherical alumina powder) Alumina powder was introduced into the flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was carried out to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 5 μm.

[0080] (Preparation of the second spherical alumina powder) Alumina powder was introduced into the flame formed by LPG and oxygen gas, and after spheroidization treatment, classification treatment by cyclone classification was carried out to obtain alumina powder with an average sphericity of 0.92 and an average particle size of 39 μm.

[0081] The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 40:60 to prepare the spherical alumina powder of Comparative Example 5 (average particle size 25 μm, specific surface area 0.42 m 2 / g, a cumulative value up to 10 μm of 41% by volume was produced.

[0082] Using the spherical alumina powder, a resin composition was prepared in the same manner as in Example 1, and the prepared resin composition was measured for spiral flow (fluidity) and viscosity. The results are shown in Table 1 below.

[0083] [Comparative Example 6] (Production of the first spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, subjected to a spheroidization treatment, and then subjected to a classification treatment by cyclone classification to obtain an alumina powder having an average sphericity of 0.92 and an average particle diameter of 5 μm.

[0084] (Production of the second spherical alumina powder) Alumina powder was introduced into a flame formed by LPG and oxygen gas, subjected to a spheroidization treatment, and then subjected to a classification treatment by cyclone classification to obtain an alumina powder having an average sphericity of 0.92 and an average particle diameter of 36 μm.

[0085] The first spherical alumina powder and the second spherical alumina powder were mixed so that the volume ratio was 15:85 to prepare the spherical alumina powder of Comparative Example 6 (average particle diameter 39 μm, specific surface area 0.27 m 2 / g, a cumulative value up to 10 μm of 12% by volume was produced.

[0086] Using the spherical alumina powder, a resin composition was prepared in the same manner as in Example 1, and the prepared resin composition was measured for spiral flow (fluidity) and viscosity. The results are shown in Table 1 below.

[0087]

Table 1

Industrial Applicability

[0088] The spherical alumina powder of the present invention can be used as a filler for resin molded parts such as molding compounds for automobiles, portable electronic devices, and household electrical appliances, and further for putties, sealing materials, buoyancy materials for ships, synthetic woods, reinforced cement exterior wall materials, lightweight exterior wall materials, sealing materials, etc. Further, the resin composition of the present invention can be used for the production of, for example, prepregs for printed circuit boards, electronic components obtained by thermoforming one or more prepregs together with copper foil or the like, and further wire coating materials, sealing materials, varnishes, etc., which are obtained by impregnating and curing glass woven fabrics, glass non-woven fabrics, and other organic base materials. Further, the semiconductor encapsulant of the present invention can be used as an encapsulant that can be easily molded into small, thin, and narrow-pitch semiconductor packages.

Claims

1. In the particle size distribution measured by a laser diffraction scattering type particle size distribution measuring instrument, having a first maximum peak and a second maximum peak from the small diameter side, the first maximum particle diameter indicating the first maximum peak is in the range of 3 to 9 μm, the second maximum particle diameter indicating the second maximum peak is in the range of 34 to 50 μm, the cumulative value of the frequency of each particle diameter at 5 points obtained by equally dividing the range from the second maximum particle diameter - 10 μm to the second maximum particle diameter + 10 μm into 4 equal parts is 25 to 45% by volume, the cumulative value of the frequency in the range of the peak having the second maximum peak is 55% by volume or more, the cumulative value of the frequency in the range of the peak having the first maximum peak is 35% by volume or less, a spherical alumina powder in which the frequency at the first maximum particle diameter - 1 μm and the frequency at the first maximum particle diameter + 1 μm are each 50% or more of the frequency at the first maximum particle diameter.

2. The spherical alumina powder according to claim 1, wherein the content of particles having a particle diameter of 55 μm or more is 0.1% by mass or less.

3. A resin composition comprising a resin and the alumina powder according to claim 1 or 2.

4. A semiconductor encapsulating material comprising the resin composition according to claim 3.

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