Method for producing inorganic oxide particles

Abstract

To provide a method for producing spherical inorganic particles which contain no carbon impurities and has no problems of insulation properties and electricity resistance when used as an inorganic filler for a sealing material.SOLUTION: There is provided a method for producing spherical inorganic particles which comprises a supply step of supplying raw material particles into a flame formed from a mixed gas containing hydrogen and oxygen and having a mixed ratio of a hydrocarbon gas of 10 ppm or less. There are used particles which contain a metal element constituting inorganic oxide particles in the state of a single metal or a semimetal element constituting inorganic oxide particles in a semimetal state as raw material particles and have a carbon atom content of 0.01 mass% or less relative to raw material particles and an average particle diameter of 1 μm or more and 100 μm or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing inorganic oxide particles.

Background Art

[0002] As semiconductor high integration progresses, higher performance such as electrical insulation and low expansion rate of the encapsulant for semiconductor chips is required. To meet such requirements, an encapsulant in which inorganic oxide particles such as silica particles are filled in a synthetic resin such as an epoxy resin is used. Here, among such inorganic oxide particles, the use of spherical inorganic particles can particularly enhance the filling property, and can also enhance the fluidity of the encapsulant when performing encapsulation. Further, as inorganic oxide particles, it is known that the closer the shape is to a perfect sphere, the more excellent the filling property, fluidity, and mold wear resistance are.

[0003] In relation to this, processes capable of producing inorganic oxide particles have also been studied. For example, Patent Document 1 discloses a technique in which spherical silica fine particles can be obtained by oxidatively burning a specific siloxane compound in a flame.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the inorganic oxide particles obtained in Patent Document 1 use a siloxane compound as a starting material, it is difficult to completely remove carbon particles. Since carbon particles have conductivity, there is a concern that a semiconductor encapsulant filled with inorganic oxide particles obtained by the above-described method may conduct electricity due to the carbon particles.

[0006] In the present invention, in view of the above circumstances, it is an object to provide a method for producing inorganic oxide particles capable of reducing the carbon content.

Means for Solving the Problems

[0007] According to one aspect of the present invention, there is provided a method for producing inorganic oxide particles. This production method includes a supply step of supplying raw material particles into a flame formed from a mixed gas containing hydrogen and oxygen and having a mixing ratio of a hydrocarbon gas of 10 ppm or less. As the raw material particles, those containing a metal element constituting the inorganic oxide particles in a metallic state or a metalloid element constituting the inorganic oxide particles in a metalloid state, having a carbon atom content of 0.01% by mass or less with respect to the raw material particles, and having an average particle diameter of 1 μm or more and 100 μm or less are used.

[0008] The present invention may also be provided in each of the following aspects. In the production method, when the stoichiometric ratio of oxygen atoms / metal atoms in the inorganic oxide particles is n O / n M , and when the amount of substance of metal atoms in the raw material particles supplied into the flame per unit time is N (mol), in the mixed gas, the volume V O (L) of oxygen supplied per unit time satisfies the relationship with the volume V H (L) of hydrogen supplied per unit time as follows:

Equation

Advantages of the Invention

[0009] According to the present invention, a method for producing inorganic oxide particles capable of reducing the carbon content can be provided.

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments, and each component shown in the following embodiments can be combined with each other.

[0011] <Method for Producing Inorganic Oxide Particles> The method for producing inorganic oxide particles according to this embodiment includes a supply step of supplying raw material particles into a flame formed from a mixed gas containing hydrogen and oxygen and having a mixing ratio of a hydrocarbon gas of 10 ppm or less. In such a production method, as the raw material particles, the metal elements constituting the inorganic oxide particles are included in the state of the metal alone, or the metalloid elements constituting the inorganic oxide particles are included in the state of the metalloid alone, and the content of carbon atoms is 0.01% by mass or less with respect to the raw material particles, and particles having an average particle diameter of 100 nm or more and 2 μm or less are used.

[0012] The present inventors have found that in the method for producing inorganic oxide particles as shown in Patent Document 1, when a substance containing carbon atoms is used as a fuel for forming a flame, carbon particles are formed due to this. In addition, it has been found that when a substance containing carbon atoms is used as a starting material, carbon particles are formed due to this. On the other hand, in the production method according to this embodiment, since the amount of carbon contained in the fuel for forming the flame, the metal source and the metalloid source which are the starting materials is small, the carbon content in the produced inorganic oxide particles is also small. Therefore, for example, when filled in a semiconductor encapsulant, it is difficult for energization to occur.

[0013] In the method for producing inorganic oxide particles of the present embodiment, raw material particles containing a metal element or a metalloid element in a single state are supplied into a flame, and the raw material particles are vaporized by the heat of the flame. The metal element or metalloid element vaporized in this way combines with oxygen and redeposits to form spherical inorganic oxide particles. In this way, since the metal element or metalloid element once undergoes a vaporization mechanism, inorganic oxide particles having an average particle diameter smaller than that of the raw material particles can be obtained.

[0014] 〔Inorganic Oxide Particles〕 The inorganic oxide particles are produced by the method for producing inorganic oxide particles according to the present embodiment.

[0015] The inorganic oxide particles are oxides of a metal element or a metalloid element. Here, the "metal element" refers to Li, Be, Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po, Fr, Ra, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, Cn, Uut, Uuq, Uup, Uuh, Uus, Uuo. The "metalloid element" refers to Si, As, Te, Te, At.

[0016] Specifically, the inorganic oxide particles include, in addition to oxides of a single metal element or metalloid element such as silica, alumina, titania, zirconia, iron oxide, nickel oxide, manganese oxide, cobalt oxide, etc., composite oxides containing a plurality of elements such as barium titanate, or solid solutions of a plurality of metal oxides such as an alumina-zirconia solid solution. In one embodiment, the inorganic oxide particles are silica or alumina.

[0017] The average particle diameter of the inorganic oxide particles is preferably 10 nm or more, 20 nm or more, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more, 90 nm or more, 100 nm or more, 120 nm or more, 150 nm or more, 200 nm or more, 250 nm or more, 300 nm or more, 350 nm or more, 400 nm or more, 450 nm or more, 500 nm or more. Further, the average particle diameter of the inorganic oxide particles is, for example, preferably 2 μm or less, 1.9 μm or less, 1.8 μm or less, 1.7 μm or less, 1.6 μm or less, 1.5 μm or less, 1.4 μm or less, 1.3 μm or less, 1.2 μm or less, 1.1 μm or less, 1 μm or less, 900 nm or less, 850 nm or less, 800 nm or less, 750 nm or less, 700 nm or less, 650 nm or less, 600 nm or less, 550 nm or less, 500 nm or less, 450 nm or less, 400 nm or less, 300 nm or less, 250 nm or less, 200 nm or less. When the average particle diameter of the inorganic oxide particles is within the required range, it can be used for various applications such as the above-described semiconductor encapsulant.

[0018] The average particle diameter in this specification means the 50% cumulative diameter (median diameter) in the volume-based cumulative particle size distribution. This "50% cumulative diameter in the volume-based cumulative particle size distribution" means the particle diameter (D50) when the cumulative value in the volume-based cumulative particle size distribution becomes 50% when measuring the particle size distribution by the laser diffraction scattering method for hexagonal boron nitride powder. The laser analysis scattering method is measured in accordance with the method described in JIS Z 8825:2013 "Particle Size Analysis - Laser Diffraction / Scattering Method". The measurement is performed using LS-13 320 manufactured by Beckman Coulter as a laser diffraction scattering method particle size distribution measuring device.

[0019] The BET specific surface area of the inorganic oxide particles is not particularly limited, but for example, 0.1 m 2 / g or more, 0.2 m 2 / g or more, 0.3 m 2 / g or more, 0.4 m 2 / g or more, 0.5 m 2 / g or more, 0.6 m 2 / g or more, 0.7 m 2 / g or more, 0.8 m2 0.9 m or more per g 2 1 m or more per g 2 It is preferably 0.9 m or more per g. On the other hand, as the BET specific surface area of the inorganic oxide particles, for example, 20 m 2 per g or less, 19 m 2 per g or less, 18 m 2 per g or less, 17 m 2 per g or less, 16 m 2 per g or less, 15 m 2 It is preferably 15 m or less per g. When the BET specific surface area of the inorganic oxide particles is within the required range, it can be used for various applications such as the above-described semiconductor encapsulants.

[0020] The BET specific surface area is a value measured by the BET single-point method using nitrogen gas in accordance with the method described in JIS Z 8830:2013 "Method for Measuring Specific Surface Area of Powder (Solid) by Gas Adsorption".

[0021] As described above, the content of carbon in the inorganic oxide particles is reduced. Specifically, the content of carbon particles having a maximum particle diameter of 20 μm or more in 1000 g of the inorganic oxide particles is not particularly limited, but for example, it is preferably 1000 or less, 95 or less, 90 or less, 85 or less, 80 or less, 75 or less, 70 or less, 65 or less, 60 or less, 55 or less, 50 or less. On the other hand, the content of carbon particles having a maximum particle diameter of 20 μm or more in 1000 g of the inorganic oxide particles may be, for example, 0 or more (including the case of 0).

[0022] The content of carbon particles in the inorganic oxide particles is measured as follows. First, 1000 g of the product (inorganic oxide particles) is dispersed in water, and the floating supernatant is collected on a filter with a pore size of 13 μm or less. Next, the black substance remaining on the filter is measured by SEM-EDX. Those with a carbon content of 50 atm% or more are regarded as carbon particles, and the maximum length (maximum particle diameter) from end to end among the images of the particles is measured. The maximum particle diameter is measured for all the particles on the filter, and the number of particles with a maximum particle diameter of 20 μm or more is measured. The above operations are repeated three times, and the arithmetic mean value of the number of particles with a maximum particle diameter of 20 μm or more in the three times is calculated as the content of carbon particles in the inorganic oxide particles.

[0023] 〔Raw material particles〕 The raw material particles are those used as a metal source or a metalloid source for producing inorganic oxide particles. Specifically, these raw material particles contain the metal elements constituting the inorganic oxide particles in the state of the metal simple substance, or contain the metalloid elements constituting the inorganic oxide particles in the state of the metalloid simple substance, and the content of carbon atoms is 0.01 mass% or less with respect to the raw material particles, and the average particle diameter is 1 μm or more and 100 μm or less.

[0024] "Containing the metal element in the state of the metal simple substance" means, for example, when using aluminum as the metal element, containing it in the state of metallic aluminum. Also, "the state of the metalloid simple substance" means, for example, when using silicon as the metalloid element, containing it in the state of metallic silicon.

[0025] In the method for producing inorganic oxide particles according to the present embodiment, the same metal elements and metalloid elements as the metal elements and metalloid elements contained in the inorganic oxide desired to be produced may be selected. For example, when producing silica particles as inorganic oxide particles, metallic silicon may be used as the raw material particles, and when producing alumina particles as inorganic oxide particles, metallic aluminum may be used as the raw material particles.

[0026] The average particle diameter of the raw material particles is not particularly limited as long as it is 1 μm or more and 100 μm or less. For example, it is preferably 1.2 μm or more, 1.5 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, 10 μm or more, 12 μm or more, 14 μm or more, 16 μm or more, 18 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more. Also, the average particle diameter of the raw material particles is, for example, preferably 95 μm or less, 90 μm or less, 85 μm or less, 80 μm or less, 75 μm or less, 70 μm or less, 65 μm or less, 60 μm or less, 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less. By the average particle diameter of the raw material particles being within the required range, inorganic oxide particles having an average particle diameter generally in the above-described range can be obtained.

[0027] The BET specific surface area of the raw material particles is not particularly limited, but for example, 0.5 m 2 / g or more, 0.6 m 2 / g or more, 0.7 m 2 / g or more, 0.8 m 2 / g or more, 0.9 m 2 / g or more, 1.0 m 2 / g or more, 1.1 m 2 / g or more, 1.2 m 2 / g or more, 1.3 m 2 / g or more, 1.4 m 2 / g or more, 1.5 m 2 / g or more, 1.7 m 2 / g or more, 2 m 2 / g or more, 2.5 m 2 / g or more, 3 m 2 / g or more is preferable. On the other hand, the BET specific surface area of the raw material particles is, for example, 5 m 2 / g or less, 4.5 m 2 / g or less, 4 m 2 / g or less, 3.5 m 2 / g or less, 3 m 2It is preferably below / g. By having the BET specific surface area of the raw material particles within the required range, inorganic oxide particles with a BET specific surface area generally within the above-described range can be produced.

[0028] The content of carbon atoms in the raw material particles is not particularly limited as long as it is 0.01 mass% or less with respect to the raw material particles. For example, it is preferably 0.007 mass% or less, 0.005 mass% or less, 0.002 mass% or less, 0.001 mass% or less. By having the content of carbon atoms in the raw material particles below the required amount, the carbon content contained in the obtained inorganic oxide particles can be suppressed. On the other hand, the content of carbon atoms in the raw material particles may be, for example, 0 mass% or more (including the case of 0 mass%).

[0029] The content of carbon atoms in the raw material particles can be measured in accordance with JIS G 1311-2:2012.

[0030] [Mixed gas] The mixed gas contains hydrogen and oxygen and has a mixing ratio of hydrocarbon gas of 10 ppm or less. That is, substantially, a flame is generated by the combustion of hydrogen contained in this mixed gas. In this specification, the "hydrocarbon gas" includes not only alkane compounds represented by methane, ethane, propane, butane, etc. and acetylene, but also those containing at least a carbon-hydrogen bond site in the chemical structure, and encompasses a group of compounds that can be mixed as a gas in the mixed gas.

[0031] Let the stoichiometric ratio of oxygen atoms / metal atoms in the inorganic oxide particles be n O / n M When the amount of substance of metal atoms in the raw material particles supplied into the flame per unit time is N (mol), in the mixed gas, the volume V O (L) of oxygen supplied per unit time, and the volume V H (L) of hydrogen supplied per unit time are in the relationship of [Number] Preferably, the ratio of hydrogen and oxygen in the mixed gas is within a required range, so that hydrogen can be sufficiently burned. In addition, when the hydrogen / oxygen ratio is less than 2, incomplete combustion of hydrogen can be suppressed, and the combustion efficiency of hydrogen can be further increased.

[0032] The mixing ratio of hydrocarbon gas in the mixed gas is preferably 10 ppm or less. By making the mixing ratio of hydrocarbon gas in the mixed gas equal to or less than the required amount, the carbon content contained in the obtained inorganic oxide particles can be suppressed. On the other hand, the mixing ratio of hydrocarbon gas in the mixed gas may be, for example, 0 ppm or more (including the case of 0 ppm). Note that the ppm unit in this specification means mass ratio. In addition, the mixing ratio of hydrocarbon gas in the mixed gas can be measured using GC-14B manufactured by Shimadzu Corporation under the conditions of a gas volume of 2.0 ml, a column of φ3 mm×2 m (made of SUS), a detection temperature of 120°C, and a carrier gas of N2 at 50 ml / min.

[0033] In the mixed gas, other gases can be included within the range where the mixing ratio of hydrocarbon gas satisfies 10 ppm or less. Examples of other gases include nitrogen, argon, air, etc. The content of other gases is not particularly limited, but for example, it is preferably 5% by volume or less, 4% by volume or less, 3% by volume or less, 2% by volume or less, 1% by volume or less, 0.7% by volume or less, 0.5% by volume or less, 0.2% by volume or less, 0.1% by volume or less, 0.07% by volume or less, 0.05% by volume or less, 0.02% by volume or less, 0.01% by volume or less, 0.007% by volume or less, 0.005% by volume or less, 0.002% by volume or less, 0.001% by volume or less. On the other hand, the content of other gases may be, for example, 0% by volume or more (including the case of 0% by volume).

[0034] 〔Flame〕 The flame is generated by the combustion of the above-described mixed gas, and inorganic oxide particles are formed by supplying raw material particles into the flame.

[0035] The temperature of the flame is not particularly limited, but for example, it is preferably 1600 °C or higher, 1650 °C or higher, 1700 °C or higher, 1750 °C or higher, 1800 °C or higher, 1850 °C or higher, 1900 °C or higher, 1950 °C or higher, 2000 °C or higher, 2050 °C or higher. On the other hand, the temperature of the flame may be, for example, 3000 °C or lower, 2950 °C or lower, 2900 °C or lower, 2850 °C or lower, 2800 °C or lower, 2750 °C or lower, 2700 °C or lower, 2650 °C or lower, 2600 °C or lower. By the temperature of the flame being within the required range, inorganic oxide particles closer to a true spherical shape can be produced.

[0036] The temperature of the flame is preferably, for example, 5 °C or higher, 10 °C or higher, 15 °C or higher, 20 °C or higher, 25 °C or higher, 30 °C or higher, 35 °C or higher, 40 °C or higher, 45 °C or higher, 50 °C or higher, 55 °C or higher, 60 °C or higher, 65 °C or higher, 70 °C or higher, 75 °C or higher, 80 °C or higher, 85 °C or higher, 90 °C or higher, 95 °C or higher, 100 °C or lower higher than the boiling point of the simple substance of the metal element or metalloid element used as the raw material particles. On the other hand, the temperature of the flame may be, for example, within the range of 200 °C or lower, 190 °C or lower, 180 °C or lower, 170 °C or lower, 160 °C or lower, 150 °C or lower, 140 °C or lower, 130 °C or lower, 120 °C or lower, 110 °C or lower, 100 °C or lower, 95 °C or lower, 90 °C or lower, 85 °C or lower, 80 °C or lower, 75 °C or lower, 70 °C or lower, 65 °C or lower, 60 °C or lower, 55 °C or lower, 50 °C or lower, 45 °C or lower, 40 °C or lower, 35 °C or lower, 30 °C or lower, 25 °C or lower, 20 °C or lower, 15 °C or lower, 10 °C or lower higher than the boiling point of the simple substance of the metal element or metalloid element used as the raw material particles. By the temperature of the flame being within the required range, inorganic oxide particles closer to a true spherical shape can be produced.

[0037] The method for forming the flame is not particularly limited as long as it can burn hydrogen, but for example, a burner can be used. In the following, the burner that can be used in the method for producing inorganic oxide particles of the present embodiment is not particularly limited, but for example, a burner having a composite tube structure as disclosed in JP-A-2005-288399 can be used.

[0038] The manufacturing method of the inorganic oxide particles according to this embodiment is not limited to the specific embodiments described above, and appropriate modifications can be made as long as the effects are not inhibited. For example, foreign substances contained in the inorganic oxide particles may be removed, or particles of a specific particle size may be taken out or removed using a sieve or the like.

[0039] As described above, such inorganic oxide particles can be used not only as a semiconductor encapsulant but also as various materials such as a phosphor material, a catalyst material, a filler material, an electronic material, and a paint.

[0040] According to the manufacturing method of the inorganic oxide particles according to this embodiment, inorganic oxide particles with a low carbon content can be obtained. In addition, by adjusting the type and size of the raw material particles, the heating conditions, etc., the size of the obtained inorganic oxide particles can also be controlled. Furthermore, since the carbon content in the raw material particles and the mixed gas is low, the amount of carbon dioxide generated in the manufacturing process can be reduced to zero, so that a highly environmentally compatible manufacturing process can be constructed.

Claims

1. A method for producing inorganic oxide particles, comprising: a supply step of supplying raw material particles into a flame formed from a mixed gas containing hydrogen and oxygen and having a hydrocarbon gas mixing ratio of 10 ppm or less; as the raw material particles, using particles that contain, in a state of a metal simple substance, a metal element constituting the inorganic oxide particles or contain, in a state of a metalloid simple substance, a metalloid element constituting the inorganic oxide particles, having a carbon atom content of 0.01 mass% or less with respect to the raw material particles and an average particle diameter of 1 μm or more and 100 μm or less; Let n be the stoichiometric ratio of oxygen atoms to metal atoms in the inorganic oxide particles Ｏ / n Ｍ When the amount of substance of metal atoms in the raw material particles supplied into the flame per unit time is N (mol), In the mixed gas, the volume V Ｏ (L) of oxygen supplied per unit time is the volume V Ｈ (L) of hydrogen supplied per unit time, and in the relationship therewith, 【Number 1】 a production method.

2. A method for producing inorganic oxide particles, comprising: a supply step of supplying raw material particles into a flame formed from a mixed gas containing hydrogen and oxygen and having a hydrocarbon gas mixing ratio of 10 ppm or less; as the raw material particles, using particles that contain, in a state of a metal simple substance, a metal element constituting the inorganic oxide particles or contain, in a state of a metalloid simple substance, a metalloid element constituting the inorganic oxide particles, having a carbon atom content of 0.01 mass% or less with respect to the raw material particles and an average particle diameter of 1 μm or more and 100 μm or less; wherein the temperature of the flame is 1600°C or higher, a production method.

3. A method for producing inorganic oxide particles, comprising: a supply step of supplying raw material particles into a flame formed from a mixed gas containing hydrogen and oxygen and having a hydrocarbon gas mixing ratio of 10 ppm or less; as the raw material particles, using particles that contain, in a state of a metal simple substance, a metal element constituting the inorganic oxide particles or contain, in a state of a metalloid simple substance, a metalloid element constituting the inorganic oxide particles, having a carbon atom content of 0.01 mass% or less with respect to the raw material particles and an average particle diameter of 1 μm or more and 100 μm or less; wherein the inorganic oxide particles have a content of carbon particles having a maximum particle diameter of 20 μm or more in 1000 g of 1000 or less, a production method.

4. In the production method according to any one of Claims 1 to 3, wherein the inorganic oxide particles are silica or alumina, a production method.

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