JP2005306923A - INORGANIC POWDER AND COMPOSITION CONTAINING THE SAME - Google Patents

Abstract

Provided are an inorganic powder suitable for obtaining, for example, a semiconductor encapsulating material and a fat composition containing the same, which have good moldability even with a high filling ratio of the inorganic powder and have few burrs during molding.
In a volume-based frequency particle size distribution, particles having a maximum diameter in regions of 0.07 μm or more and less than 0.5 μm, 3 μm or more and less than 15 μm, and 30 μm or more and less than 70 μm, and 0.5 μm or more and less than 3 μm. An inorganic powder characterized in that a ratio A / B of A and a particle content B of 15 μm or more and less than 30 μm is 1.2 to 3.3. Moreover, the said inorganic powder is contained in any one of rubber | gum and resin, The composition characterized by the above-mentioned.
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Description

The present invention relates to an inorganic powder, and a composition containing the inorganic powder and either rubber or resin. Specifically, the present invention relates to an inorganic powder and a composition suitable for obtaining a semiconductor encapsulating material having good fluidity and moldability even with a high filling rate of the inorganic powder and having few burrs during molding.

  In recent years, in response to demands for smaller and lighter electronic devices and higher performance, semiconductor packages have been increasingly reduced in size, thickness, and pitch. As the mounting method, surface mounting suitable for high-density mounting on a wiring board or the like is becoming mainstream. As semiconductor packages and their mounting methods are progressing in this way, semiconductor sealing materials are also required to have higher performance, particularly improved solder heat resistance, moisture resistance, low thermal expansion, mechanical properties, electrical insulation, and other functions. Has been. In order to satisfy these requirements, a resin composition in which an epoxy resin is filled with an inorganic powder, particularly an amorphous silica powder, is generally used, and most of the semiconductor sealing material is based on this resin composition. It is desirable that the inorganic powder filled in the semiconductor sealing material is highly filled in an epoxy resin from the viewpoints of soldering heat resistance, moisture resistance, low thermal expansion, and mechanical strength.

However, the high filling of the inorganic powder raises the problem of increasing the melt viscosity of the semiconductor sealing material and increasing defects in molding processing such as unfilling, wire flow, and chip shift. The inside of the semiconductor package is composed of lead frames, semiconductor elements, bonding wires, etc., but with the progress of high-density mounting technology and microfabrication technology, the shape of the bonding wire increases, the number of wires increases, and the shape of the lead frame increases As a result, problems in molding process are increasingly being raised as undesirable problems.

  To solve this problem, try to optimize the shape and particle size distribution of the inorganic powder, or lower the melt viscosity by making the viscosity of resin components such as epoxy resins and phenol resin curing agents extremely low in the temperature range where sealing is formed. Attempts have been made to maintain and reduce defects in the molding process.

  As an improvement technique on the inorganic powder side so as not to impair the melt viscosity of the semiconductor encapsulating material even when highly filled with inorganic powder, the gradient of the straight line displayed in the Rosin Ramler diagram is 0.6 to 0.95, A method of widening the particle size distribution (Patent Document 1), a method of increasing the sphericity by 0.7 to 1.0 with a Wadel sphericity (Patent Document 2), and an average particle size of about 0.1 to 1 μm A method of adding a small amount of spherical fine powder (Patent Document 3) has been proposed.

  Moreover, as an improvement technique on the resin side, a method of reducing the melt viscosity of an epoxy resin or a phenol resin curing agent (Patent Document 4), a progress of a resin curing reaction due to a thermal history in a kneading process, and an increase in melt viscosity are prevented. Therefore, a method of combining the raw materials that do not proceed with the curing reaction at the premixing stage among the blended components, and performing melt kneading after melting and mixing these raw materials at a higher temperature (Patent Document 5), A method (Patent Document 6) that keeps the melt viscosity low by minimizing the progress of the curing reaction by optimizing selection and kneading conditions has been proposed.

Although improvements have been made by these technologies, it is still not sufficient for the rapid development of today's electronic field, especially semiconductor packages and their mounting methods. Development of a semiconductor encapsulating material that has good moldability even if it is high is eagerly desired. In addition, as a result of keeping the melt viscosity of the resin composition low in order to improve moldability, there is a new problem that the resin composition overflows from the air vent part of the mold at the time of molding, that is, the `` burr '' remarkably occurs. Closed up, it is also required to achieve both improved fluidity and reduced burr.
Japanese Patent Laid-Open No. 6-80863 JP-A-3-66151 JP-A-5-239321 Japanese Patent Laid-Open No. 9-291136 Japanese Patent Laid-Open No. 3-19564 JP-A-9-52228

  An object of the present invention is to provide an inorganic powder suitable for obtaining a semiconductor encapsulating material having good moldability even with a high filling rate of the inorganic powder and having few burrs during molding, and a fat composition containing the same. It is to be.

  In the volume-based frequency particle size distribution, the present invention has a maximum particle size in a region of 0.07 μm or more and less than 0.5 μm, 3 μm or more and less than 15 μm, and 30 μm or more and less than 70 μm, and a particle content of 0.5 μm or more and less than 3 μm. The inorganic powder is characterized in that the ratio A / B of A and the particle content B of 15 μm or more and less than 30 μm is 1.2 to 3.3. In this case, particles having a particle content of 0.07 μm or more and less than 0.5 μm are 3 to 6%, 3 μm or more and less than 15 μm are 40 to 60%, 30 μm or more and less than 70 μm are 20 to 40%, 0.5 μm or more and 3 μm. It is preferable that less than 8 to 10% and 15 to 30 μm is 2 to 9%. In addition, in the volume-based cumulative particle size distribution when particles of 3 μm or less are collected, it is particularly preferable that particles of 0.1 μm or less are contained in an amount of 10% or more and particles of less than 0.05 μm are not substantially contained. Moreover, it is preferable that any one of the inorganic powders is a spherical amorphous silica powder.

Furthermore, the present invention is a composition comprising any one of the above inorganic powders in one of rubber and resin.

  ADVANTAGE OF THE INVENTION According to this invention, the inorganic powder and composition suitable in order to obtain a semiconductor sealing material with favorable moldability and few burr | flash at the time of shaping | molding even if the filling rate of inorganic powder is high are provided.

  The inorganic powder of the present invention has the above particle size characteristics, and the maximum diameter is a particle diameter that exhibits a maximum value in the frequency particle size distribution of the inorganic powder.

In order to suppress the generation of burrs, it is necessary to prevent the flow of the resin composition flowing out from the mold air vent part, and it is most effective that the inorganic powder in the resin composition blocks the air vent part. Is. Therefore, in order to reduce burrs without impairing fluidity, it is desirable to form a close-packed structure of inorganic powder, and its complete realization is impossible. As a distribution, the present invention has been achieved as a result of various studies.

That is, in the present invention, particles in the region of 30 μm or more and less than 70 μm are the main material of the filler of the rubber / resin composition (hereinafter, particles of 30 μm or more and less than 70 μm are also referred to as “main material particles”). When the maximum diameter is less than 30 μm, the melt viscosity of the rubber / resin composition is remarkably increased, and the effect of suppressing the rubber / resin composition from flowing out from the air vent portion is reduced. Conversely, when the maximum diameter exceeds 70 μm, the particle size becomes an obstacle, and when the rubber / resin composition is used as a semiconductor sealing material, the semiconductor chip is damaged at the time of molding, causing wire cutting / wire flow. There is a risk of causing problems. It is particularly preferable to have a maximum diameter in the region of 40 μm or more and less than 60 μm.

Particles in the region of 3 μm or more and less than 15 μm enter the gaps between the main material particles to make the packing structure dense, reduce the melt viscosity, and reduce burrs, etc. (hereinafter referred to as “intervening coarse particles”) Also called.) The maximum diameter in this particle region is preferably about 0.1 to 0.2 times the maximum diameter of the main material particles, and preferably has a maximum diameter of 4 μm or more and less than 12 μm.

  Particles in the region of 0.07 μm or more and less than 0.5 μm enter further into the gap of the closely packed structure composed of the main material particles and the intervention coarse powder particles to make the packed structure more dense, and further lower the melt viscosity. Thus, the effect of preventing the occurrence of burrs can be remarkably enhanced (hereinafter, these particles are also referred to as “intervening fine powder particles”).

  Particles existing in the region of 15 μm or more and less than 30 μm (hereinafter, these particles are also referred to as “coarse powder adjusting particles”) have a dense packing structure of the main material particles and the intervention coarse powder particles by adjusting the blending amount thereof. Can be. Similarly, particles existing in the region of 0.5 μm or more and less than 3 μm (hereinafter, these particles are also referred to as “fine powder adjusting particles”) can be obtained by adjusting the amount of the intervening coarse particles and intervening fine particles. The filling structure can be made dense.

The ratio (A / B) of the fine powder adjusting particle content (A) and the coarse powder adjusting particle content (B) is preferably 1.2 to 3.3. When this ratio is significantly larger than 3.3, the number of particles that cannot enter the gaps between the main material particles increases, and the formation of a densely packed structure is hindered. On the other hand, if this ratio is significantly smaller than 1.2, the amount of fine powder of the entire constituent particles increases, so that the melt viscosity increases and the moldability may be significantly deteriorated.

  The composition ratio (volume content) of each particle is 3 to 6% of intervention fine powder particles (that is, particles of 0.07 μm or more and less than 0.5 μm), and intervention coarse powder particles (that is, particles of 3 μm or more and less than 15 μm). 40 to 60%, main material particles (that is, particles of 30 μm or more and less than 70 μm) are 20 to 40%, fine powder adjusting particles (that is, particles of 0.5 μm or more and less than 3 μm) are 8 to 10%, and coarse powder adjusting particles (that is, It is preferable that the particle | grains of 15 micrometers or more and less than 30 micrometers are 2-9%. With such a particle size configuration, it is possible to make it closer to the theoretical close packed structure, and the above-described effects of the present invention are promoted.

  In the inorganic powder of the present invention, in the volume-based cumulative particle size distribution when particles having a size of 3 μm or less are separated, the particles having a size of 0.1 μm or less are not contained in an amount of 10% or more, and less than 0.05 μm is substantially contained. It is preferable not to contain it. This is because such ultrafine particles inhibit the formation of the close-packed structure with the inorganic powder.

  In the present invention, “substantially does not contain particles of less than 0.05 μm” means that the number of particles of less than 0.05 μm is counted for any 100 photographs taken with an electron microscope at a magnification of 50,000 times. It is defined that the value converted as an average value per sheet is less than 50. The smaller the number of particles less than 0.05 μm, the better. However, when the average number of particles is 50 or more, the effect of the present invention is not rapidly lost. .

  The particle size distribution of the inorganic powder of the present invention is a value based on particle size measurement by a laser diffraction light scattering method, and as a particle size distribution measuring machine, for example, “Model LS-230” (manufactured by Beckman Coulter, Inc.) can be used. it can. In the measurement, as a pretreatment, water is used as a solvent, and a concentration of PIDS (Polarization Intensity Differential Scattering) is adjusted to 45 to 55% by mass and dispersed in a 200 W output homogenizer for 1 minute. In addition, 1.33 was used for the refractive index of water, and the refractive index of the powder material was taken into consideration for the refractive index of the powder. For example, amorphous silica was measured with a refractive index of 1.46. The measured particle size distribution was subjected to various analyzes by converting the particle diameter channel so that the log (μm) = 0.04 width.

Moreover, it is difficult to measure ultrafine particles of 0.1 μm or less by the above method. In order to accurately measure ultrafine particles of 0.1 μm or less, particles of 3 μm or less must be collected and measured by a dynamic light scattering method. When particles of 3 μm or more are present, measurement accuracy varies. An example of the measuring machine is “Microtrac UPA150” (manufactured by Nikkiso Co., Ltd.). At the time of measurement, as a pretreatment, water is used as a solvent, the concentration is adjusted to 1% by mass, the mixture is dispersed in a 200 W output homogenizer for 5 minutes, and then centrifuged. For the centrifugation, for example, a planetary mixer “Awatori Nertaro AR-360M” (manufactured by Shinky Corporation) can be used. In the present invention, centrifugation was performed for 10 minutes under the condition of revolution 2000 rpm. After centrifugation, the mixture was allowed to stand for 3 hours to precipitate coarse particles, and the supernatant was collected and used for measurement.

  The inorganic powder of the present invention is preferably spherical. As the degree of “spherical”, the average sphericity is preferably 0.85 or more. Generally, if the average sphericity of the inorganic powder is increased, the rolling resistance of the rubber / resin composition is decreased, and the melt viscosity tends to decrease. In the present invention, the average sphericity is particularly preferably 0.90 or more.

The average sphericity is obtained by taking a particle image taken with a stereomicroscope such as “Model SMZ-10” (Nikon Corporation), a scanning electron microscope or the like into an image analyzer such as Nihon Avionics Co., Ltd. It can measure as follows. That is, the projected area (A) and the perimeter (PM) of particles are measured from a photograph. When the area of a perfect circle corresponding to the perimeter (PM) is (B), the roundness of the particle can be displayed as A / B. Therefore, assuming a perfect circle having the same circumference as the sample particle (PM), PM = 2πr and B = πr ² , so that B = π × (PM / 2π) ² , and each particle Can be calculated as sphericity = A / B = A × 4π / (PM) ² . The sphericity of 200 arbitrary particles thus obtained was determined, and the average value was defined as the average sphericity.

As a method for measuring sphericity other than the above, a particle image analyzer, for example, “Model FPIA-1000” (manufactured by Sysmex Corporation) or the like can be used to calculate the sphericity from the roundness of individual particles. Degree = (roundness) ² can also be obtained by conversion.

  The inorganic powder in the present invention is an inorganic powder such as silica, alumina, titania, magnesia, calcia, aluminum nitride, silicon nitride, boron nitride, silicon carbide, etc., and those powders may be used alone or in combination of two or more. It may be. In particular, it is manufactured by a method that melts crystalline silica at a high temperature or a synthetic method from the viewpoint of close thermal expansion coefficient between the semiconductor chip and the semiconductor sealing material, solder heat resistance, moisture resistance, and low wear of the mold. Amorphized silica is most suitable. The amorphous ratio is determined by X-ray diffraction analysis of the sample using a powder X-ray diffractometer such as “Model Mini Flex” (manufactured by RIGAKU) in the range of 2θ of CuKα ray of 26 ° to 27.5 °. And can be measured from the intensity ratio of the specific diffraction peak. That is, crystalline silica has a main peak at 26.7 °, but amorphous silica has no peak. When amorphous silica and crystalline silica are mixed, a peak height of 26.7 ° corresponding to the ratio of crystalline silica can be obtained, so the X-ray of the sample relative to the X-ray intensity of the crystalline silica standard sample From the intensity ratio, the crystalline silica mixture ratio (X-ray diffraction intensity of the sample / X-ray diffraction intensity of the crystalline silica) is calculated, and the formula, amorphous ratio (%) = (1-crystalline silica mixture ratio) The amorphous ratio can be determined from x100.

  The inorganic powder of the present invention preferably has an Na ion concentration and a Cl ion concentration of 1 ppm or less in the extracted water as ionic impurities, and U and Th concentrations of 1 ppb or less as radioactive impurities, respectively. When there are many ionic impurities, there exists a possibility of having a bad influence on the reliability and moisture resistance of a semiconductor chip. Further, it is known that a large amount of radioactive impurities may cause a soft error due to α-rays, and care must be taken particularly when used for sealing a semiconductor memory.

  The inorganic powder of the present invention may be produced by any method as long as it has the characteristics defined in the present invention. For example, in a facility consisting of a melting furnace capable of forming a high-temperature flame and injecting silica powder raw material, and a collection system for the molten processed material, the particle size of the silica powder raw material, the amount of raw material supplied, Amorphous silica powder having various particle size configurations can be produced by adjusting temperature, furnace pressure, furnace air flow conditions, etc., and further classified, sieved and mixed. There are many known facilities (for example, JP-A-11-057451), which can be employed.

  Next, the composition of the present invention will be described. This composition contains the inorganic powder of the present invention in at least one of rubber and resin. The proportion of the inorganic powder in the composition is preferably 10 to 99% by mass.

  Examples of the rubber used in the present invention include silicone rubber, urethane rubber, acrylic rubber, butyl rubber, ethylene propylene rubber, and ethylene vinyl acetate copolymer. Examples of the resin include epoxy resins, silicone resins, phenol resins, melamine resins, urea resins, unsaturated polyesters, fluororesins, polyamides such as polyimide, polyamideimide, and polyetherimide, and 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) Examples thereof include resins. One or more of these rubbers or resins are used.

  Among these, as the resin for semiconductor sealing material, an epoxy resin having two or more epoxy groups in one molecule is preferable. Specific examples include phenol novolac type epoxy resins, orthocresol novolak type epoxy resins, epoxidized phenol and aldehyde novolak resins, glycidyl ethers such as bisphenol A, bisphenol F and bisphenol S, phthalic acid, Glycidyl ester acid epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, alkyl-modified polyfunctional epoxy resin obtained by reaction of polybasic acid such as dimer acid and epochlorohydrin, β-naphthol novolak-type epoxy resin, 1,6-dihydroxynaphthalene-type epoxy resin, 2,7-dihydroxynaphthalene-type epoxy resin, bishydroxybiphenyl-type epoxy resin, and halo such as bromine to impart flame retardancy Is introduced epoxy resin or the like down. Among these, from the viewpoint of moisture resistance and solder reflow resistance, orthocresol novolac type epoxy resins, bishydroxybiphenyl type epoxy resins, epoxy resins having a naphthalene skeleton, and the like are preferable.

  The epoxy resin curing agent is not particularly limited as long as it is cured by reacting with the epoxy resin. For example, phenol, cresol, xylenol, resorcinol, chlorophenol, t-butylphenol, nonylphenol, isopropylphenol, octylphenol, etc. Bisphenol compounds such as novolak-type resin, polyparahydroxystyrene resin, bisphenol A and bisphenol S obtained by reacting a mixture of one or more selected from the group with formaldehyde, paraformaldehyde or paraxylene under an oxidation catalyst , Trifunctional phenols such as pyrogallol and phloroglucinol, acid anhydrides such as maleic anhydride, phthalic anhydride and pyromellitic anhydride, metaphenylenediamine, diaminodiphenylmethane Aromatic amines such as diaminodiphenyl sulfone, and the like.

  The composition of the present invention may contain the following components as necessary. That is, as a low stress agent, silicone rubber, polysulfide rubber, acrylic rubber, butadiene rubber, rubbery substances such as styrene block copolymers and saturated elastomers, various thermoplastic resins, resinous substances such as silicone resins, Is an epoxy resin, a resin obtained by modifying a part or all of a phenol resin with aminosilicone, epoxysilicone, alkoxysilicone, or the like. As a silane coupling agent, γ-glycidoxypropyltrimethoxysilane, β- (3,4- Epoxy cyclohexyl) Epoxy silanes such as ethyltrimethoxysilane, aminopropyltriethoxysilane, ureidopropyltriethoxysilane, aminosilanes such as N-phenylaminopropyltrimethoxysilane, phenyltrimethoxysilane, methyltri Hydrophobic silane compounds such as methoxysilane and octadecyltrimethoxysilane, mercaptosilane, etc., surface treatment agents such as Zr chelate, titanate coupling agents, aluminum coupling agents, flame retardant aids such as Sb2O3, Sb2O4, Sb2O5, etc. Examples of flame retardants include halogenated epoxy resins and phosphorus compounds, and examples of colorants include carbon black, iron oxide, dyes, and pigments. Furthermore, a release agent such as wax can be added. Specific examples include natural waxes, synthetic waxes, metal salts of linear fatty acid salts, acid amides, esters, paraffins and the like.

  In particular, when high moisture resistance reliability and high temperature storage stability are required, the addition of various ion trapping agents is effective. Specific examples of the ion trapping agent include Kyowa Chemical Co., Ltd. trade names “DHF-4A”, “KW-2000”, “KW-2100”, and Toa Gosei Kagaku Kogyo Co., Ltd. trade names “IXE-600”.

  In the composition of the present invention, a curing accelerator can be blended in order to promote the reaction between the epoxy resin and the curing agent. Examples of the curing accelerator include 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, benzyldimethylamine, and 2-methylimidazole.

  The composition of the present invention is produced by blending a predetermined amount of each of the above materials with a blender, a Henschel mixer or the like, then kneading with a heating roll, kneader, uniaxial or biaxial extruder, etc., and cooling and then pulverizing. be able to.

  In order to seal the semiconductor using the composition of the present invention, a known molding method such as transfer molding or multi-plunger is employed.

Examples 1-5 Comparative Examples 1-18
Natural silica was pulverized, and the pulverized product was supplied into a high-temperature flame formed by combustion with LPG and oxygen in the melting furnace, and melted and spheroidized. The molten material was pneumatically transported to a collection system consisting of a gravity sedimentation chamber, a cyclone, a bag filter, and a blower, and classified. Six kinds of spherical amorphous silica having a single maximum diameter (0.1 μm, 0.4 μm, 5 μm, 12 μm, 36 μm, 58 μm) by adjusting flame forming conditions, raw material particle size, raw material supply amount, classification conditions, etc. A powder was produced. The powders were mixed as appropriate to produce 23 types of powders shown in Tables 1, 2 and 3. The sphericity was controlled mainly by adjusting the flame formation conditions and the raw material supply amount. Powder names A to E are inorganic powders according to the examples, and powder names F to W are inorganic powders according to the comparative example. In all of the powder names A to W, the amorphous ratio was 99% or more, and the average sphericity was 0.90 or more. The particle size characteristics of these powders were measured according to the above method. The results are shown in Table 1 (Example), Table 2 (Comparative Example), and Table 3 (Comparative Example).

  In order to evaluate the characteristics of the obtained spherical amorphous silica powder as a filler for a semiconductor encapsulating material, 4,4′- with respect to 90 parts (parts by mass, the same applies hereinafter) of spherical amorphous silica powders A to W. Bis (2,3-epoxypropoxy) -3,3 ′, 5,5′-tetramethylbiphenyl type epoxy resin 4.3 parts, tetrahydrophthalic anhydride 4.4 parts, triphenylphosphine 0.2 parts, γ- Add 0.5 parts of glycidoxypropyltrimethoxysilane, 0.2 parts of carbon black, and 0.4 parts of carnauba wax, dry blend with a Henschel mixer, and mix the resulting mixture in the same direction. Heat kneading with a machine (screw diameter D = 25 mm, kneading disk length 10 Dmm, paddle rotation speed 150 rpm, discharge rate 5 kg / h, heater temperature 105 to 110 ° C.)The discharged material was cooled with a cooling press and then pulverized to obtain a semiconductor sealing material. The moldability and burr length of the obtained material were evaluated according to the following methods. The results are shown in Table 1, Table 2, and Table 3.

(1) Formability (spiral flow)
The spiral flow value of the epoxy resin composition was measured using a transfer molding machine equipped with a spiral flow measurement mold according to EMMI-I-66 (Epoxy Molding Material Institute; Society of Plastic Industry). The transfer molding conditions were a mold temperature of 175 ° C., a molding pressure of 7.4 MPa, and a pressure holding time of 90 seconds.

(2) Burr length A 32-pin LOC (Lead on Chip) structure TSOP (Thin Small Outline Package; 10 mm × 21 mm, thickness 1.0 mm, simulated IC chip size 9 mm × 18 mm, lead frame 42 alloy) 48 pieces were produced by a transfer molding machine, and the average burr length was measured. The transfer molding conditions were a mold temperature of 175 ° C., a molding pressure of 7.4 MPa, and a pressure holding time of 90 seconds.

  As is clear from Tables 1 to 3, the composition mixed with the inorganic powder of the present invention has a good moldability and a low burr length even when the filling rate of the inorganic powder is 90% by mass or more. You can see that

  The inorganic powder of the present invention includes resin molded parts such as molding compounds for automobiles, portable electronic devices, home appliances, etc., as well as putty, sealing materials, marine buoyancy materials, synthetic wood, reinforced cement outer wall materials, lightweight outer wall materials, etc. Used as a filler. Further, the composition of the present invention is an electronic material obtained by heat-molding one or a plurality of prepregs for a printed circuit board, for example, a prepreg for a printed circuit board or a prepreg formed by impregnating and curing glass woven fabric, glass nonwoven fabric, or other organic base material. It is used for the production of parts, and further, wire covering materials, semiconductor encapsulants, varnishes and the like.

Claims (5)

In the volume-based frequency particle size distribution, each particle has a maximum diameter in the region of 0.07 μm or more and less than 0.5 μm, 3 μm or more and less than 15 μm, and 30 μm or more and less than 70 μm, and the particle content A is 0.5 μm or more and less than 3 μm and 15 μm or more. An inorganic powder, wherein the ratio A / B of the particle content B of less than 30 μm is 1.2 to 3.3. The particle content in the volume-based frequency particle size distribution is 3 to 6% for particles of 0.07 μm or more and less than 0.5 μm, 40 to 60% for particles of 3 to 15 μm, 20 to 40% for 30 to 70 μm, 0.5 μm 2. The inorganic powder according to claim 1, wherein 8 to 10% is less than 3 μm and 2 to 9% is 15 μm to less than 30 μm. 2. The volume-based cumulative particle size distribution when particles having a size of 3 μm or less are collected, wherein particles having a size of 0.1 μm or less are contained at 10% or more, and particles having a size of less than 0.05 μm are not substantially contained. Or the inorganic powder of 2. The inorganic powder according to claim 1, 2, or 3, wherein the inorganic powder is a spherical amorphous silica powder. A composition comprising the inorganic powder according to claim 1 in any one of rubber and resin.