Spherical inorganic composition, resin composition, slurry composition, filler for semiconductor package sealing material, and method for analyzing voids in spherical inorganic composition

Abstract

Provided is a spherical inorganic composition that is suitable for a filler for a semiconductor package sealing material, and the like, as a result of improving the quality of particles of the spherical inorganic composition through accurate understanding of the properties of voids present in the particles of the spherical inorganic composition. In the spherical inorganic composition excluding elemental silica, the average particle size of the spherical inorganic composition as measured by laser diffraction particle size distribution measurement is 0.1-15 μm, and the number of particles of the spherical inorganic composition including voids having a diameter of at least 5 μm is at most 50 particles / mm3, and the number of particles of the spherical inorganic composition including voids having a diameter of at least 10 μm is at most 5 particles / mm3.

Description

Spherical inorganic composition, resin composition, slurry composition, filler for sealing material for semiconductor package, and method for analyzing voids in spherical inorganic composition

[0001] The present invention relates to a spherical inorganic composition, a resin composition, a slurry composition, a filler for sealing materials for semiconductor packages, and a method for analyzing voids in spherical inorganic compositions, and in particular to a spherical inorganic composition having voids inside, other than simple silica, and a composition containing the same.

[0002] Encapsulant is used to protect semiconductor IC chips from dust, dirt, and moisture in the air, and the IC chips are encapsulated to create semiconductor packages. The encapsulant is primarily a resin composition made up of a resin with high heat and chemical resistance and silica with a low thermal expansion coefficient. There are several methods for manufacturing semiconductor packages depending on the application and required performance. Fan-Out Wafer Level Package (FOWLP) and Fan-Out Panel Level Package (FOPLP) are used for packages that require high functionality and small size and are installed in mobile devices.

[0003] Various FOWLP processes include a polishing process to smooth the surface of the semiconductor package containing the encapsulant after encapsulating the IC chip. If hollow particles are present in the encapsulant, or if cavities are formed in the encapsulant due to the inclusion of air bubbles or other contaminants, depressions will form on the polished package surface, reducing surface smoothness and appearance, resulting in lower yields. Particularly in processes that involve polishing the surface of a semiconductor package and then forming a rewiring layer on that surface, the presence of hollow particles in the encapsulant can result in copper wiring being formed on the depressions on the package surface. In this state, if the package expands or contracts due to changes in the temperature environment, the hollow spaces in the depressions can cause the copper wiring to break and become disconnected. Without the hollow spaces, the copper wiring is surrounded by the encapsulant, preventing it from breaking even when it expands or contracts. Furthermore, while conventional copper wiring has a large line width of over 10 μm, making it highly rigid and resistant to breakage, as package functionality becomes more sophisticated and the line width becomes smaller, the rigidity of the copper wiring also decreases. For this reason, attention has been focused on reducing the amount of hollow particles contained in the encapsulating material (see, for example, Patent Documents 1 and 2).

[0004] Packages for servers have a different structure and manufacturing process than those described above. The package is mounted on an interposer or similar device using a flip-chip structure, and then the entire package is sealed. There are also manufacturing methods that involve two steps: underfilling the narrow gap under the chip and overmolding to protect the entire chip. There are also manufacturing methods that seal both the chip and the top of the chip at the same time. High fluidity is particularly required for bulk sealing. These types of packages also require a surface polishing process to smooth the package surface, and, as with the above, a low hollow particle content in the encapsulant filler is strongly required.

[0005] JP 2022-117398 A JP 2021-161008 A

[0006] As semiconductor packages become smaller and wiring becomes finer to meet the above-mentioned required characteristics, it is necessary to precisely remove the solid coarse particles used in fillers, and the size of the coarse particles that need to be removed is also becoming smaller.In addition, it is required to reduce the voids present inside the filler particles as much as possible, and therefore measuring the voids present inside filler particles is important from the perspective of quality control.

[0007] However, in conventional particle void measurement, the cross section of the particle is exposed by embedding it in resin or the like and grinding it. Therefore, the solid part of the particle and the void within it are measured. However, depending on the grinding position, the center of the void varies, and it is not necessarily the center of the filler, resulting in misalignment between the two. Even if the filler particle is cut to expose its cross section, the exact diameter of the void sphere is not exposed. The size and volume of the void are calculated from the cross-sectional diameter at a position away from the center, resulting in large errors. Furthermore, factors such as deformation or clogging of the void due to loads during grinding can cause errors. In particular, the larger the volume of the void, the more likely it is that a defect will occur due to a recess during the formation of the redistribution layer. This is because the resin components of the redistribution layer flow into the recess, causing localized loss of flatness.

[0008] The present invention has been made in consideration of the above points, and aims to accurately grasp the properties of the voids present in particles of spherical inorganic compositions other than silica alone, thereby improving the quality of the particles of the spherical inorganic compositions, and to provide spherical inorganic compositions suitable for resin compositions, slurry compositions, and fillers for sealing materials for semiconductor packages, and also to provide a method for analyzing the voids in spherical inorganic compositions other than silica alone.

[0009] That is, the spherical inorganic composition other than silica alone in the embodiment has an average particle size of 0.1 to 15 μm as measured by laser diffraction particle size distribution of the spherical inorganic composition, and the particles of the spherical inorganic composition containing voids with a diameter of 5 μm or more are 50 particles / mm ３ and the spherical particles of the inorganic composition containing voids of 10 μm or more in diameter are 5 particles / mm ３ The present invention is characterized by the following:

[0010] Furthermore, in the spherical inorganic composition, when the spherical inorganic composition is filled into a resin material having a solid content concentration of 70 mass %, a particle diameter of 150 μm detected by a cross-sectional analysis of the resin composition is ３ The spherical inorganic composition particles containing the above voids are 14 particles / mm ３ 35 μm or less detected by tomographic cross-section analysis ３ The spherical inorganic composition particles containing voids are 50 particles / mm ３ It may be the following.

[0011] Furthermore, the cross-sectional analysis of the spherical inorganic composition may be performed by X-ray CT or FIB-SEM.

[0012] Furthermore, the spherical inorganic composition may be made of alumina, calcium titanate, or a silica-alumina composite oxide.

[0013] Furthermore, the content of uranium element in the spherical inorganic composition may be 100 ppb or less.

[0014] Furthermore, the spherical inorganic composition may be surface-treated with a silane compound.

[0015] Furthermore, the resin composition of the embodiment may have a spherical inorganic composition other than simple silica, and a resin material that disperses the spherical inorganic composition.

[0016] Furthermore, the slurry composition of the embodiment may contain a spherical inorganic composition other than simple silica, and a dispersion medium for dispersing the spherical inorganic composition.

[0017] Furthermore, the filler for a semiconductor package sealant according to the embodiment may contain a spherical inorganic composition other than simple silica.

[0018] The method for analyzing voids in a spherical inorganic composition according to the embodiment is characterized by comprising a dispersion step in which the spherical inorganic composition excluding simple silica is dispersed in a resin composition, a cross-sectional analysis step in which the spherical inorganic composition together with the resin composition is subjected to cross-sectional analysis using X-ray CT or FIB-SEM, and a void calculation step in which a three-dimensional image is prepared from the cross-sectional analysis and the diameter and volume of voids present within the spherical inorganic composition are calculated.

[0019] Furthermore, the method for analyzing voids in a spherical inorganic composition may include a curing step of curing the resin composition after the dispersion step.

[0020] The present invention provides a spherical inorganic composition containing inorganic raw materials other than simple silica as a main component, the spherical inorganic composition having an average particle size of 0.1 to 15 μm as measured by laser diffraction particle size distribution measurement, and containing voids of 5 μm or more in diameter at a rate of 50 particles / mm ３ and the spherical particles of the inorganic composition containing voids of 10 μm or more in diameter are 5 particles / mm ３ The method is characterized by the following: the properties of the voids present in spherical inorganic particles other than simple silica can be accurately grasped, thereby improving the quality of the spherical inorganic particles. Furthermore, by applying the method for analyzing the voids in the spherical inorganic composition, the accuracy of measuring the voids present in the spherical inorganic composition can be improved.

[0021] The spherical inorganic composition, resin composition, slurry composition, filler for semiconductor package encapsulant, and method for analyzing voids in the spherical inorganic composition according to the embodiment are described below. The spherical inorganic particles according to the embodiment (excluding silica alone) can be dispersed in a resin material to form a resin composition, or dispersed in a liquid dispersion medium to form a slurry composition. They are particularly suitable for use as fillers for semiconductor package encapsulants, antenna-in-packages, etc.

[0022] (Spherical inorganic composition and filler for semiconductor package encapsulant) The spherical inorganic composition of the embodiment (excluding silica alone) is in the form of particles, and the particles are suitably used as fillers for semiconductor package encapsulants. As semiconductors, it is preferable to apply it to those produced using FOWLP and FOPLP techniques.

[0023] The spherical inorganic composition of the embodiment is formed from inorganic components other than silica particles, specifically alumina, calcium titanate, or silica-alumina composite oxide, and further includes metal oxides such as magnesia, zirconia, and titania. The properties required for spherical inorganic compositions of alumina, calcium titanate, and silica-alumina composite oxide are as follows: Alumina: In the case of alumina, when polishing the encapsulant in WLP and forming a rewiring layer on it, the polishing exposes the internal voids of the particles filled in the encapsulant, and the resin of the rewiring layer flows into the voids. This reduces the flatness of the rewiring layer and makes it more likely to cause electrical conduction defects. The content of particles with increased internal void volume is important for encapsulants for WLP. However, it is difficult to accurately grasp the internal voids of particles using cross-sectional observation in conventional techniques. In contrast, the embodiment makes it possible to accurately grasp the voids within alumina particles, thereby improving particle precision. Calcium titanate: When calcium titanate is added as a filler to increase the dielectric constant, the inclusion of highly hollow calcium titanate particles can cause a decrease in the dielectric constant. In particular, when used to fill substrates for high-frequency communications, the inclusion of highly hollow calcium titanate particles can cause a local decrease in the dielectric constant, leading to increased transmission loss. In this regard, the embodiments enable accurate identification of the voids in the calcium titanate particles, contributing to improved quality. Silica-alumina composite oxide: The silica-alumina composite oxide is used in, for example, photosensitive films, lenses, and adhesives used in photoelectric integration, by matching the refractive index of the filler itself to the matrix resin material, thereby improving the strength of the resin material while transmitting light. When adding a filler, the inclusion of highly hollow silica-alumina composite oxide particles can cause haze. In this regard, the embodiments enable accurate identification of the voids in the silica-alumina composite oxide, mitigating the refractive index problem.

[0024] The spherical inorganic composition is composed of components of the inorganic composition at 50% or more based on the mass of the composition, and preferably at 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more. In the spherical inorganic composition of the embodiment, simple silica may be present in the components due to unavoidable contamination during production. In other words, the use of simple silica is actively excluded from the raw materials, and the occurrence of unavoidable contamination with silica components is excluded. However, since silica-alumina-based composite oxides have a crystalline structure composed of silicon, aluminum, and oxygen, simple silica (SiO ２ ) is distinguished from

[0025] Compounds that may be contained in calcium titanate include titanium oxide, iron oxide, molybdenum oxide, silicon dioxide, etc. Impurities may be contained in the calcium titanate crystals or as independent particles.

[0026] Among spherical inorganic compositions, alumina is known to have α, γ, or θ crystal structures, while calcium titanate is known to have a perovskite structure. The proportion of crystalline components in spherical inorganic compositions varies depending on the type.

[0027] The material of the spherical inorganic composition of silica-alumina composite oxide is composed of an oxide (including composite oxide) containing silicon and aluminum, and has a crystallinity of 0.5% or less. The composition ratio of silicon and aluminum is preferably less than 50% by mass of aluminum based on the mass of silicon and aluminum, and more preferably 35%, 30%, 27.5%, 25%, or 20% as the upper limit. Furthermore, based on the moles of silicon, the moles of aluminum are preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more.

[0028] For each type of spherical inorganic composition, the D measured by laser diffraction particle size distribution measurement ５０ (median diameter) is 0.1 μm or more and 15 μm or less. ５０Examples of the lower limit are 0.2 μm, 0.5 μm, 1.0 μm, and 1.3 μm, and examples of the upper limit are 14.0 μm, 11.0 μm, 9.0 μm, 8.0 μm, 7.0 μm, and 6.0 μm. These upper and lower limit values ​​can be combined arbitrarily.

[0029] D ５０ is a value measured by laser diffraction particle size distribution measurement, and is the particle size that accounts for 50% of the smallest particle size on a volume basis. １００ is the particle size of 100% from the smallest particle size. ５０ , D １００ The value of D is calculated as a numerical value within the range of the measurement limit of laser diffraction particle size distribution measurement, and in reality, there are coarse particles and fine particles that cannot be detected by laser diffraction particle size distribution measurement. １００ There is no contradiction in the existence of particles with a particle size larger than the value of

[0030] D ５０ The value of is controlled by the manufacturing conditions of the spherical inorganic composition. In addition, it is adjusted by a classification operation and the addition of particulate materials with other particle size distributions. For the classification operation, centrifugal separation such as a cyclone is preferably used. The added particulate materials are also subjected to a classification operation.

[0031] The viscosity of the resin composition when filled into a resin material with a solid content of 80% by mass for the spherical inorganic composition is 1500 Pa·s or less (at a shear rate of 1 s －１ ), preferably 100 Pa s or less, more preferably 500 Pa s or less. As the resin material, an epoxy resin obtained by mixing bisphenol A type epoxy resin and bisphenol F type epoxy resin in a 1:1 ratio is used (for example, ZX-1059 manufactured by Nippon Steel Chemical Materials Co., Ltd.).

[0032] The specific surface area of ​​the spherical inorganic composition is 0.1 m ２ / g or more, 15m ２ The lower limit of the specific surface area is 0.2 m ２ / g, 0.5m ２ / g, 0.8m ２ / g is exemplified, and the upper limit is 10m ２ / g, 7m ２ / g, 5m ２ / g is an example of the specific surface area. The specific surface area is a value measured by the BET method using nitrogen. A smaller specific surface area is preferable because it reduces the viscosity when used in a slurry composition or the like. The method for controlling the specific surface area is not particularly limited, and the specific surface area can be adjusted by performing the synthesis of the spherical inorganic composition under conditions that reduce the amount of fine powder, or by controlling the residence time in a classifier to be longer during classification to reduce the amount of fine powder.

[0033] The voids contained in the spherical inorganic composition refer to hollow particles, which are bubbles generated during the production stage of the spherical inorganic composition. Obviously, the fewer voids (hollow particles) there are, the better. However, voids inevitably occur during the production of spherical inorganic compositions such as the above-mentioned alumina, calcium titanate, or silica-alumina composite oxide.

[0034] The voids (hollow particles) are 150 μm based on the case where the spherical inorganic composition is filled into the resin material so that the solid content concentration after addition is 70 mass %. ３ The spherical inorganic composition particles having the above voids are 14 particles / mm ３ Below, 10 pieces / mm ３ Below, 5 pieces / mm ３ or less, and most preferably 0 pieces / mm ３ In total, it is 35 μm or less. ３ The spherical inorganic composition particles having the above voids are 50 particles / mm ３ Below, 30 pieces / mm ３ Below, 15 pieces / mm ３ and most preferably 10 pieces / mm ３ The following is the result.

[0035] Furthermore, based on the case where the spherical inorganic composition is filled into a resin material so that the solid content concentration after addition is 70 mass %, the number of particles of the spherical inorganic composition having voids with a diameter of 5 μm or more is 50 / mm ３ Below, 30 pieces / mm ３ Below, 10 pieces / mm ３ and most preferably 10 pieces / mm ３ In addition, the number of spherical inorganic composition particles having voids of 10 μm or more in diameter is 10 particles / mm３ Below, 5 pieces / mm ３ or less, and most preferably 3 particles / mm ３ The following is the result.

[0036] The size of the voids (hollow particles) contained in each spherical inorganic composition has been evaluated by diameter. To measure the diameter of the voids (hollow particles), the spherical inorganic composition is embedded in a resin or the like, and then the resin block is cut to measure the diameter of the voids (hollow particles) from the cut surface of the spherical inorganic composition exposed on the cross section. However, when cutting the resin block, the spherical inorganic composition is dispersed in the resin, so the position of the spherical inorganic composition that becomes the cut surface is completely random. For example, if the cut surface is located away from the center of the spherical inorganic composition, the voids exposed on the cut surface of the spherical inorganic composition are measured as having an apparently small diameter. It is impossible for all of the spherical inorganic composition to be cut exactly at the center of the sphere. Therefore, measuring the size of the voids (hollow particles) based on the cutting position lacks precision.

[0037] Therefore, if the size of the voids (hollow particles) is to be precisely measured, it is necessary to grasp the void diameters in multiple cross-sectional portions of the spherical inorganic composition. Taking this into consideration, in an embodiment, a cross-sectional analysis is performed. Specifically, X-ray CT or FIB-SEM is used for the analysis. When using X-ray CT, a cross-sectional image of the resin mass in which the spherical inorganic composition is dispersed (embedded) is taken. It is desirable that the imaging interval (pitch) between the cross-sectional images be a fine range, such as 1 μm or less. From each cross-sectional image, the diameter of the voids (hollow particles) present within each individual spherical inorganic composition can be measured more sensitively. The volume of the voids (hollow particles) is then calculated. Even if the shape of the voids is not spherical but distorted, the volume of the distorted voids can also be calculated from image analysis of the combined cross-sectional images.

[0038] When using FIB-SEM, a focused ion beam is irradiated and scanned onto a resin mass in which spherical inorganic compositions are dispersed (embedded), gradually grinding the surface in a fine range of 1 μm or less. As a result, the voids (hollow particles) present within each spherical inorganic composition are gradually exposed. The diameter of each void present within each spherical inorganic composition is then measured according to the amount (depth) of grinding caused by ion beam irradiation. Using FIB-SEM, the volume of the voids (hollow particles) can also be calculated, and it is also possible to measure voids with irregular shapes.

[0039] The aforementioned number of measurements is a number calculated from analysis using X-ray CT or FIB-SEM. The measurement conditions for X-ray CT or FIB-SEM are to cut at a pitch of 1 μm or less and observe the void diameter at which the diameter is largest, or to construct three-dimensional data, and calculate the void diameter and void volume within the particle from the difference in contrast (brightness and darkness) between the surrounding resin, the spherical inorganic composition, and the voids. Alternatively, X-ray CT data is acquired under conditions of a voxel size of 2 μm or less, and the void diameter and void volume within the particle are calculated from the contrast difference. When analyzing using X-ray CT or FIB-SEM, the analysis range is 0.5 mm ３ That's all.

[0040] An essential point of view is to accurately measure the number of hollow particles with large void volumes. In fact, the void volume (volume) measured using X-ray CT or the like as in the embodiment deviates from the theoretical sphere volume calculated from the void diameter. This is because the void shape within the particle is often not a perfect sphere. By performing the cross-sectional analysis of the embodiment, the diameter and volume of the voids (hollow particles) for each spherical inorganic composition can be accurately detected and calculated. This improves the accuracy of quality control of the finished spherical inorganic composition. In particular, this contributes greatly to improving the yield when processing wiring with narrower line widths.

[0041] (Method for analyzing voids in spherical inorganic composition) The method for analyzing voids in spherical inorganic composition can be summarized as follows. First, the spherical inorganic composition is dispersed (embedded) in a resin composition. The resin is of the composition described above. The solids concentration of the spherical inorganic composition in the resin composition is adjusted to 60 to 80% by mass, preferably 70% by mass (dispersion process). The purpose of the dispersion process in the resin is to fix the position of each particle of the spherical inorganic composition for subsequent measurement analysis. Furthermore, after the dispersion process, a curing process is added to harden the resin composition. In this curing process, the resin composition is heated and irradiated with ultraviolet light, and the resin composition is prepared into a cured resin. Obviously, a thermosetting resin or an ultraviolet-curable resin is selected for the resin composition.

[0042] The spherical inorganic composition together with the resin composition is subjected to cross-sectional analysis using X-ray CT or FIB-SEM (cross-sectional analysis step). The cross-sectional analysis method is as described above. A three-dimensional image is prepared from the cross-sectional analysis, and the diameter and volume of voids present within the spherical inorganic composition are calculated (void calculation step). The cross-sectional analysis step and void calculation step can be performed in a consistent manner, and the analysis range, voxel size, etc. are appropriately adjusted to calculate the maximum diameter and volume of voids (hollow particles) present within each spherical inorganic composition.

[0043] The spherical inorganic composition of the embodiment is preferably surface-treated with a surface treatment agent such as a silane compound or a silazane compound. The silane compound or silazane compound is not particularly limited, and a silane compound or silazane compound having an appropriate functional group is selected as needed for the surface treatment. The surface treatment is performed using a combination of two or more silane compounds and silazane compounds.

[0044] For the surface treatment, it is preferable to use a surface treatment agent capable of introducing functional groups such as trimethylsilyl, isocyanate, amino, phenyl, phenylamino, vinyl, methacryl, and epoxy groups. For example, a titanate coupling agent, an aluminate coupling agent, or a silane compound having the functional group to be introduced can be reacted.

[0045] Examples of aluminate coupling agents include acetoalkoxyaluminum diisopropylate, aluminum alkylacetoacetate diisopropylate, aluminum ethylacetoacetate diisopropylate, aluminum trisethylacetoacetate, aluminum isopropylate, aluminum diisopropylate mono-secondary butylate, aluminum secondary butylate, aluminum ethylate, aluminum bisethylacetoacetate monoacetylacetonate, aluminum trisacetylacetonate, and aluminum monoisopropoxymonoroxyethylacetoacetate.

[0046] The surface treatment agent may be a single compound or a mixture of multiple compounds. The organic functional group is determined depending on the type of resin material and dispersion medium to be combined. The amount of the surface treatment agent is not particularly limited, and is 0.1 to 5.0 parts by mass per 100 parts by mass of the spherical inorganic composition.

[0047] For the spherical inorganic composition of the embodiment, the amount of alpha rays produced is 0.001 c / cm ２ In particular, it is desirable that the uranium concentration as an α-ray source is 100 ppb or less, further 5 ppb or less, preferably 3 ppb or less, and more preferably 1 ppb or less.

[0048] (Method for Producing Metal Oxide Particle Material) In producing the spherical inorganic composition of the embodiment, a representative method for producing each component will be presented, which includes a production step, a classification step, and other steps that may be adopted as necessary.

[0049] - Manufacturing process (spherical inorganic composition of alumina) Various crystalline aluminas (aluminum oxides) are used as raw particle materials, and particle materials with an average particle size larger than the average particle size (volume average particle size) of the spherical inorganic composition to be finally prepared are used as raw particle materials. Then, raw particle materials with the required volume average particle size can be obtained by a grinding operation. For example, the particle size distribution is adjusted after grinding the raw particle material. Alternatively, or in addition to adjusting the particle size distribution after grinding, the particle size distribution can be adjusted before grinding. To control the particle size distribution, it is preferable to remove particles with small particle sizes.

[0050] The raw material particle material is preferably produced by the VMC method (deflagration process). The VMC method is a method for producing spherical oxide microparticles by utilizing the deflagration phenomenon of metal powder, also known as the "Vaporized Metal Combustion Method." The spherical inorganic composition of alumina produced by the VMC method has high sphericity, is dense, and has excellent electrical properties. Metallic aluminum is used as the raw material particle material. The VMC method involves burning a combustible (such as hydrocarbon gas) with a burner in an oxygen-containing atmosphere to form a chemical flame as a high-temperature atmosphere, and then introducing an amount of raw material particle material into this chemical flame such that a dust cloud is formed, causing deflagration to occur and obtaining a particulate oxide. The high-temperature atmosphere is preferably an atmosphere of 2000°C or higher.

[0051] The VMC process works as follows: First, a vessel is filled with a gas containing oxygen, which is a reactive gas, and a chemical flame is formed in this reactive gas. Next, raw material particles are introduced into this chemical flame, forming a dust cloud. The chemical flame then imparts thermal energy to the surface of the raw material particles, raising the surface temperature of the metals that make up the raw material particles, causing the vapor of the contained metals to spread from the surface of the raw material particles to the surrounding area. This vapor reacts with oxygen gas, igniting and generating a flame. The heat generated by this flame further promotes the vaporization of the raw material particles, and the resulting vapor and oxygen gas mix, causing a chain reaction of ignition and propagation. Therefore, the smaller the particle size of the raw material particles, the larger the specific surface area and the improved reactivity, allowing for less energy input.

[0052] When alumina is produced by the VMC process, a mixture of large and small particle size material is obtained, and the large particle size fraction is therefore classified and used as the raw material particle size.

[0053] The pulverization method is not particularly limited, and common pulverization methods such as jet mills, ball mills, and vibrating ball mills can be used. Jet mills are particularly preferred because they reduce the amount of impurities derived from the pulverization media and have high pulverization efficiency on the micrometer order. Particle materials produced by the VMC method have a high degree of circularity and may contain a certain amount of fine particles with a particle size of less than 1 μm in the particle size distribution.

[0054] The particulate material made of metal oxide produced by the VMC method is used as it is or after classification as a crude raw material particulate material. Because the metals constituting the metal particulate material used as the raw material for the VMC method are easier to purify than the metal oxides, it is easy to increase the purity of the raw material particulate material obtained through the VMC method.

[0055] In addition to the preparation of spherical inorganic compositions of alumina by the VMC method described above, spherical inorganic compositions of alumina can also be prepared by a flame fusion method or the like. In the preparation of spherical inorganic compositions of alumina by the flame fusion method, the raw material alumina is pulverized to, for example, 5 μm or less, and granulation or the like is carried out according to the target particle size. Alternatively, heating is carried out at, for example, above 1000° C., which promotes the dissociation of moisture contained in the crystals and gasification of the moisture, making it easier to reduce voids.

[0056] By utilizing the principle of dust explosion in the VMC method, a large amount of spherical inorganic alumina composition can be obtained instantaneously. The resulting spherical inorganic alumina composition has a nearly perfect spherical shape. By adjusting the particle size, amount of raw material particles added, flame temperature, etc., it is possible to adjust the particle size distribution of the resulting spherical inorganic alumina composition. Furthermore, the raw material particles can be surface-treated with a silane compound, a silazane compound, etc. The type of silane compound that can be used is not particularly limited, and the types of surface treatment compounds described above can be used.

[0057] The raw material particles are dispersed in a carrier and then fed into the flame to be combusted. The speed at which the raw material particles are fed into the flame is not particularly limited. The carrier may be a gas such as nitrogen, argon, or air, or a liquid such as water or alcohol. There are no particular limitations on how the particles are dispersed, and when dispersed in a liquid, it is preferable to spray the particles into the flame in a mist form. For example, it is preferable that the raw material particles are contained in an amount of about 10% to 80% by volume of the total.

[0058] The flame used is a flame in an oxidizing atmosphere. For example, a flame in which flammable gases such as LPG, ammonia, and hydrogen are burned in an atmosphere containing excess oxygen is used. Thermal plasma is also included in the flame. The raw material particles introduced into the flame are vaporized by combustion and rapidly cooled to become raw alumina particles made of alumina. The obtained raw alumina particles are collected using a bag filter or the like.

[0059] Manufacturing Process (Spherical Inorganic Composition of Calcium Titanate) In the manufacturing of the spherical inorganic composition of calcium titanate according to the embodiment, calcium titanate is used as the raw material particle material, and a particle material having an average particle size larger than the average particle size (volume average particle size) of the spherical inorganic composition to be finally prepared is used as the raw material particle material. A grinding operation is then performed to produce a raw material particle material having the required volume average particle size. For example, the particle size distribution is adjusted after grinding the raw material particle material. Alternatively, or in addition to adjusting the particle size distribution after grinding, the particle size distribution can be adjusted before grinding. To control the particle size distribution, it is preferable to remove particles with small particle sizes.

[0060] In the production of spherical inorganic compositions of calcium titanate, raw material particles are heated and melted in a high-temperature atmosphere to form spheroids, followed by rapid cooling to obtain highly circular particles. The high-temperature atmosphere is at a temperature above the temperature at which calcium titanate can be softened or melted. The high-temperature atmosphere may be a flame or plasma formed by burning a combustible gas mixed with a combustion-assistant gas. Examples of combustible gases include propane gas, acetylene gas, and hydrogen gas. Furthermore, the raw material particles are introduced into the high-temperature atmosphere in the form of a dispersion dispersed in a carrier. Examples of carriers include inert gases such as nitrogen, combustion-assistant gases such as oxygen, combustible gases such as propane, water, alcohols such as methanol and isopropanol, and ketones such as acetone.

[0061] In the production of the spherical inorganic composition of calcium titanate, the surface may be treated with a silane compound or a silazane compound to introduce an alkyl group such as a phenyl group or a methyl group.

[0062] - Manufacturing process (spherical inorganic composition of silica-alumina-based composite oxide) When manufacturing the spherical inorganic composition of silica-alumina-based composite oxide, the raw particle material is a particle material containing metallic silicon and metallic aluminum. The metallic silicon and metallic aluminum may be a mixture of separate particle materials, or a particle material consisting of an alloy of metallic silicon and metallic aluminum. Since the purity of the raw particle material directly affects the purity of the spherical inorganic composition, the purity of the raw particle material is adjusted to the required purity.

[0063] Metallic silicon and metallic aluminum are made into a particulate material by dissolving them in a chemical solution and pulverizing them using an atomizer or the like. The abundance ratio of metallic silicon and metallic aluminum contained in the raw particle material is approximately the same as the abundance ratio of silicon and aluminum contained in the spherical composite oxide particulate material to be produced. The average particle size of the raw particle material is not particularly limited and is approximately 0.1 μm to 40 μm.

[0064] Furthermore, the raw material particles are subjected to a surface treatment. By performing the surface treatment, aggregation of the raw material particles is suppressed when the particles are introduced into a high-temperature oxidizing atmosphere (described later). Examples of the surface treatment include organic silicon compounds such as silane compounds, organic aluminum compounds such as aluminate coupling agents, and organic titanium compounds such as titanate coupling agents.

[0065] The VMC method is also used to produce spherical inorganic compositions of silica-alumina composite oxides, as with the alumina described above. As a result, the raw material particles are converted into oxides by a deflagration reaction, and the resulting oxides fall by gravity or other factors, are removed from the high-temperature oxidizing atmosphere, and are rapidly cooled, thereby forming spherical inorganic compositions of silica-alumina composite oxides. The compositions are then recovered using a bag filter or cyclone.

[0066] A spherical inorganic composition of silica-alumina composite oxide is surface-treated with a surface treatment agent such as an organosilicon compound (silane compound), an organoaluminum compound, or an organotitanium compound. In the surface treatment, the surface treatment agent is brought into direct contact with the surface of the composition (either liquid or gaseous), or the surface treatment agent is brought into contact with the surface of the composition after being dissolved in a solvent. After the surface treatment, the composition may be heated to promote the reaction between the surface treatment agent and the surface of the spherical inorganic composition of silica-alumina composite oxide.

[0067] Classification step: The classification step is a step of classifying the spherical inorganic composition prepared from each raw material until the content of coarse particles is below the upper limit mentioned above and the content of hollow particles with a particle size of 5 μm or more is below the upper limit mentioned above. The coarse particles consist of solid particles and hollow particles. Classification procedures include centrifugation in a gas or solvent, separation by specific gravity in a liquid, and dry or wet sieving. Classification is repeated until the desired particle size distribution is achieved.

[0068] Centrifugation is a method suitable for removing solid particles from among coarse particles. It is desirable that the solvent used for centrifugation has a low viscosity. Examples include methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and toluene. Solid coarse particles can be separated with high precision by performing centrifugation while the particles are dispersed in MEK at a concentration of approximately 10% by mass to 30% by mass (particularly 15% by mass to 25% by mass). Wet centrifugation can separate coarse particles by applying centrifugal force to the slurry to cause the coarse particles to settle and be removed.

[0069] To separate coarse particles consisting of hollow particles, it is preferable to separate hollow particles with a low specific gravity after dispersion in a liquid. Separation in a liquid is preferably performed by removing the hollow particles present in the supernatant after allowing the dispersion to stand or applying centrifugal force (hollow particle separation process). The liquid used is the same type as the liquid used in centrifugation. Furthermore, among the coarse particles, solid particles settle quickly, while hollow particles settle slowly or not at all. Therefore, by removing the supernatant in addition to the operation for removing the coarse particles described above, it is possible to simultaneously remove coarse particles consisting of solid particles and coarse particles consisting of hollow particles. Furthermore, when using a filter, classification is performed in the form of a dispersion slurry dispersed in a solvent. It is desirable to perform the filter classification operation multiple times. If performed multiple times, it is preferable to perform the filter classification operation while switching from a filter with a large pore size to a filter with a small pore size.

[0070] Other steps The surface treatments described above are included in the other steps. The surface treatments can be selectively combined. The surface treatment can be performed before, after, or during the classification step on the spherical inorganic composition prepared from the raw materials produced in the manufacturing process.

[0071] The amount of the surface treatment agent used for surface treatment is not particularly limited. For example, when a substance that reacts with the surface of particles, such as a silane compound or a silazane compound, is used as the surface treatment agent, an amount that reacts with 100%, 75%, 50%, 25%, etc., based on the amount of OH groups present on the surface of the particles to be treated is selected. Furthermore, an excess amount exceeding 100% (120%, 150%, etc.) can also be selected. In this case, unreacted surface treatment agent remains on the surface of the particles. The silane compound is not particularly limited, and examples thereof include compounds having a phenyl group, an alkyl group, a vinyl group, a methacrylic group, an epoxy group, a phenylamino group, an amino group, a styryl group, etc.

[0072] (Resin Composition) The resin composition of the embodiment is a composition obtained by dispersing a spherical inorganic composition prepared from the above-mentioned raw materials (alumina, calcium titanate, silica-alumina composite oxide) in a resin material (including a resin material precursor). The mixing ratio of the spherical inorganic composition and the resin material is not particularly limited. The resin material may be any appropriate material, such as an epoxy resin, an acrylic resin, or a silicone resin. It may also be a resin material precursor before curing.

[0073] (Slurry Composition) The slurry composition of the embodiment is a composition obtained by mixing a spherical inorganic composition prepared from the above-mentioned raw materials (alumina, calcium titanate, silica-alumina composite oxide) with a liquid dispersion medium (solvent, resin material precursor, etc.). The mixing ratio of the spherical inorganic composition to the dispersion medium is not particularly limited. In addition to the above-mentioned resin material precursor, examples of the dispersion medium include MEK, MIBK, alcohols such as hexane and 2-propanol.

[0074] The spherical inorganic compositions of the embodiments, and the manufacturing method and analytical method thereof were prepared and carried out as follows: Test Examples 1 to 15 show the preparation of each test example.

[0075] (Test Example 1: Alumina) Using metallic aluminum containing 5 ppb or less as a raw material, spherical alumina was prepared by the VMC method described above. This was then pulverized in a jet mill to an average particle size of 3 μm, and placed in a melting furnace under a high-temperature atmosphere (approximately 2000°C) to be spheroidized by rapid cooling. The obtained spherical alumina was wet classified to 5 μm in an aqueous solvent and dried. Alumina synthesized by the VMC method with an average particle size of 0.2 μm was blended to achieve a closest-packed design.

[0076] (Test Example 2: Alumina) Low-sodium crushed alumina with an average particle size of 3 μm was charged into a melting furnace and spheroidized. The resulting spherical alumina was wet classified to 10 μm in an aqueous solvent and dried. Alumina synthesized by the VMC method with an average particle size of 0.2 μm was blended to achieve a closest-packed design.

[0077] (Test Example 3: Alumina) Using metallic aluminum containing 5 ppb or less as a raw material, spherical alumina was prepared by the VMC method described above. This was then pulverized in a jet mill to an average particle size of 4 μm, and placed in a melting furnace under a high-temperature atmosphere (approximately 2000°C) to be spheroidized by rapid cooling. The obtained spherical alumina was wet classified to 10 μm in an aqueous solvent and dried. Alumina synthesized by the VMC method with an average particle size of 0.2 μm was blended to achieve a closest-packed design.

[0078] Test Example 4: Alumina Using metallic aluminum containing uranium at 20 ppb or less as a raw material, spherical alumina having an average particle size of 9.8 μm was produced by the VMC method described above, and the spherical alumina was classified into 10 μm particles by wet classification in an aqueous solvent and dried.

[0079] Test Example 5: Alumina Using metallic aluminum containing 5 ppb or less as a raw material, spherical alumina with an average particle size of 0.2 μm was produced by the VMC method described above, and the spherical alumina was classified into 5 μm particles by wet classification in an aqueous solvent and dried.

[0080] (Test Example 6: Alumina) Using metallic aluminum containing 5 ppb or less as a raw material, spherical alumina was prepared by the VMC method described above. This was then pulverized in a jet mill to an average particle size of 1.8 μm, and then placed in a melting furnace under a high-temperature atmosphere (approximately 2000°C) and spheroidized by rapid cooling. The obtained spherical alumina was wet classified to 3 μm in an aqueous solvent and dried. Alumina synthesized by the VMC method with an average particle size of 0.2 μm was blended to achieve a closest-packed design.

[0081] Test Example 7: Alumina Using metallic aluminum containing 5 ppb or less as a raw material, spherical alumina with an average particle size of 0.2 μm was produced by the VMC method described above, and the spherical alumina was classified into 3 μm particles by wet classification in an aqueous solvent and dried.

[0082] (Test Example 8: Calcium titanate) Crushed calcium titanate particles with an average particle size of 1.5 μm were introduced into a melting furnace with a flame of propane gas as a combustible gas and oxygen as a combustion-supporting gas, together with a carrier composed of air. The particles were sphericalized by surface tension during melting, then dropped out of the flame, cooled, and solidified. The resulting spherical calcium titanate was recovered. It was then classified to 5 μm by air classification.

[0083] Test Example 9: Calcium titanate The spherical calcium titanate obtained from the melting furnace in Test Example 8 was classified to 5 μm by wet classification in a 2-propanol solvent.

[0084] Test Example 10: Calcium titanate The spherical calcium titanate obtained from the melting furnace in Test Example 8 was used as it was.

[0085] (Test Example 11: Silica-Alumina Composite Oxide) Metallic silicon powder with an average particle size of 20 μm and a purity of 99% or higher and metallic aluminum powder with an average particle size of 25 μm and a purity of 99% or higher were blended at a mass ratio of Si:Al = 60:40 (raw material particles). According to the aforementioned VMC method, a melting furnace was charged with propane gas as a combustible gas and air as a combustion-supporting gas, and the raw material particles were introduced into a flame in a high-temperature oxidizing atmosphere. Due to the VMC method, the metallic material exploded and vaporized, forming droplets at a temperature below its boiling point, which solidified into spherical particles at a temperature below its melting point. The silica-alumina composite oxide resulting from solidification was recovered, subjected to wet gravity classification in an aqueous solvent to remove hollow particles, and then dried. Finally, a silica-alumina composite oxide with an average particle size of 0.2 μm was prepared.

[0086] Test Example 12: Silica-alumina composite oxide The spherical silica-alumina composite oxide obtained from the melting furnace in Test Example 11 was used as it was.

[0087] (Test Example 13: Silica-Alumina Composite Oxide) Metallic silicon powder with an average particle size of 20 μm and a purity of 99% or higher and metallic aluminum powder with an average particle size of 25 μm and a purity of 99% or higher were blended at a mass ratio of Si:Al = 60:40 (raw material particles). According to the aforementioned VMC method, a melting furnace was charged with propane gas as a combustible gas and air as a combustion-supporting gas, and the raw material particles were introduced into a flame in a high-temperature oxidizing atmosphere. Due to the VMC method, the metallic material exploded and vaporized, forming droplets below its boiling point, which solidified below its melting point to form spherical particles. The silica-alumina composite oxide resulting from solidification was recovered, subjected to wet gravity classification in an aqueous solvent to remove hollow particles, and then dried. Finally, a silica-alumina composite oxide with an average particle size of 0.5 μm was prepared.

[0088] Test Example 14: Silica-alumina composite oxide To 100 parts by mass of Aluminosol 10A manufactured by Kawaken Fine Chemical Co., Ltd., 40 parts by mass of 2-propanol was added, and 10 parts by mass of tetraethyl orthosilicate was added. After reacting at room temperature for 24 hours, the mixture was neutralized with aqueous ammonia to obtain a gel-like precipitate. The precipitate was fired at 1100°C, slowly cooled, washed with pure water, and dried at 160°C for 2 hours. After drying, the precipitate was pulverized using a jet mill to an average particle size of 2 μm or less. The pulverized product was then placed in a melting furnace and spheroidized.

[0089] Test Example 15: Silica-alumina composite oxide To 100 parts by mass of Aluminosol 10A manufactured by Kawaken Fine Chemical Co., Ltd., 40 parts by mass of 2-propanol was added, and 10 parts by mass of tetraethyl orthosilicate was added. After reacting at room temperature for 24 hours, the mixture was neutralized with aqueous ammonia to obtain a gel-like precipitate. The precipitate was washed with pure water and dried at 160°C for 2 hours. After drying, the precipitate was pulverized using a jet mill to an average particle size of 2 μm or less. The pulverized product was then placed in a melting furnace and spheroidized.

[0090] Test Example 16: Glass Glass frit having an average particle size of 21 μm was crushed to an average particle size of 2.3 μm, and then charged into a melting furnace to be spheroidized.

[0091] (Particle size distribution measurement) For each test example, the particle size after pulverization, melting, etc. was measured in an aqueous solvent using a laser diffraction particle size distribution measuring device SALD-7500 nano manufactured by Shimadzu Corporation. １０ , D ５０ (Median diameter), D ９０ The particle size distribution was calculated.

[0092] (Specific surface area measurement / BET method) 1.0 g of each test example was weighed and placed in a measurement cell. After pretreatment, the BET specific surface area value was measured by nitrogen adsorption. For the measurement, an automatic specific surface area and pore distribution measuring device TriStar (registered trademark)-II 3020 manufactured by Shimadzu Corporation was used. The pretreatment conditions were as follows: Degassing temperature: 300°C Degassing time: 30 minutes Cooling time: 4 minutes

[0093] (Component Analysis) The atomic composition of each test example was analyzed using an ICP (inductively coupled plasma atomic emission spectroscopy) device ICP-MS (measurement of U) manufactured by Shimadzu Corporation. For the measurement, each test example was completely dissolved in a mixed solution of nitric acid and hydrofluoric acid to form a solution, which was then subjected to the device.

[0094] (Content of hollow particles of 5 μm or more by cross-sectional observation) Liquid epoxy resin ZX1059 (manufactured by Nippon Steel Chemical & Material Co., Ltd.) and the spherical inorganic composition (filler) prepared in the test example were mixed, and then curing agent Ethacure 100 (manufactured by Mitsui Fine Chemicals, Inc.) was added and mixed. At this time, the spherical inorganic composition (filler) was adjusted to 70 mass %. The mixture of resin and spherical inorganic composition was heated to 170°C to cure the resin. After curing, the cured resin was cut and the cross section was polished.

[0095] An ArBlade (registered trademark) 5000 (manufactured by Hitachi High-Tech Corporation) was used for ion milling, and the cross section was osmium coated with osmium tetroxide gas and observed by SEM. Observation range: 9 mm ２ The number of spherical inorganic composition particles having an inner diameter (major axis) of 5 μm or more and containing voids within the particles was counted.

[0096] (Content of hollow particles of 5 μm or more by X-ray CT observation) Liquid epoxy resin ZX1059 (manufactured by Nippon Steel Chemical & Material Co., Ltd.) and the spherical inorganic composition (filler) prepared in the test example were mixed, and then curing agent Ethacure 100 (manufactured by Mitsui Chemicals Fine Co., Ltd.) was added and mixed. At this time, the spherical inorganic composition (filler) was adjusted to 70 mass %. The mixture of resin and spherical inorganic composition was heated to 170°C to cure the resin. After curing, the cured resin was cut and the cross section was polished.

[0097] The cured resin was scanned using a microfocus X-ray CT (Rigaku Corporation, nano-3DX). The setting conditions were 0.64 μm / voxel and the measurement range was 0.58 mm. ３ After scanning, the analysis software VG Studio MAX was used for image processing to calculate the void volume inside the spherical inorganic composition. ３ , 150 μm ３ The number of voids was counted.

[0098] (Content of Coarse Particles) The spherical inorganic composition prepared in each test example was sieved using a sieve with a mesh size of 10 μm or 5 μm. The mass before sieving and the mass of the particles remaining on the sieve were measured, and test examples in which the amount of residue was 500 ppm or less were marked with "Good", and test examples in which the amount of residue was more than 500 ppm were marked with "Poor".

[0099] (Filling property) Liquid epoxy resin ZX1059 (manufactured by Nippon Steel Chemical & Material Co., Ltd.) was mixed with the spherical inorganic composition (filler) prepared in the test example. At this time, the spherical inorganic composition (filler) was adjusted to 80% by weight (mass %). The viscosity at 25°C was measured using a rheometer ARES-G2 (manufactured by TA Instruments) (at a shear rate of 1 s －１ ) Then, it was evaluated whether it was 1500 Pa·s or less. A viscosity of 1500 Pa·s or less was evaluated as "Good", and a viscosity of 1500 Pa·s or more was evaluated as "Poor".

[0100] (Results) The results are as shown in Tables 1, 2, 3, and 4 below. From the top to bottom, the types, average particle sizes (μm), specific surface areas (m ２ / g), and the "5 μm or larger hollow volume (pieces / cm ２ ), hollow volume of 10 μm or more (pieces / cm ２ ), void volume 35μm ３ or more particles (pieces / cm ２ ), void volume 150μm ３ or more particles (pieces / cm ２ "), X-ray CT observation of "5 μm or more hollow amount (pieces / mm ３ ), hollow volume of 10 μm or more (pieces / mm ３ ), void volume 35μm ３ or more particles (pieces / mm ３ ), void volume 150μm ３ or more particles (pieces / mm ３ "), filling ability (good or bad), and U (uranium) content (ppb).

[0101]

[0102]

[0103]

[0104]

[0105] (Discussion) The smaller the average particle diameter of a spherical inorganic composition (the finer the particle size), the lower the content of hollow particles with large internal void volumes. However, fine particles have poor filling properties in resin. Therefore, they are not suitable for filler applications. Furthermore, in applications such as semiconductor encapsulation materials (fillers for encapsulation materials for semiconductor packages), filling properties are important for controlling the thermal expansion coefficient. To achieve both of these, by setting the average particle diameter to 0.5 μm or more, the spherical inorganic composition can also have sufficient filling properties.

[0106] In wafer-level packaging (WLP), when an encapsulant is polished and a redistribution layer is formed thereon, the polishing exposes the internal voids of the particles filled in the encapsulant, and the resin of the redistribution layer flows into the voids, reducing the flatness of the redistribution layer and making electrical conduction defects more likely to occur. Therefore, understanding the content of particles with large internal void volumes is particularly important for encapsulants for WLP. Conventional cross-sectional observation techniques have made it difficult to accurately grasp the internal voids of particles. In contrast, as disclosed in the examples, cross-sectional tomographic analysis can measure the internal voids of spherical inorganic compositions, improving the accuracy of evaluation. In particular, alumina spherical inorganic compositions can effectively address the above-mentioned problems of wafer-level packaging.

[0107] Spherical inorganic compositions of calcium titanate are advantageous for applications involving increasing the dielectric constant. When a filler is added to increase the dielectric constant, the inclusion of particles with a high hollowness can cause a decrease in the dielectric constant. In particular, when filling a substrate for high-frequency communications, the inclusion of particles with a high hollowness can cause a local decrease in the dielectric constant, leading to increased transmission loss, which is a problem. Therefore, the spherical inorganic composition of calcium titanate according to the embodiment has a reduced hollowness, making it possible to address the issue of dielectric constant modulation.

[0108] Spherical inorganic compositions of silica-alumina composite oxides are a good example of fillers for optical system materials. For example, the refractive index of the filler itself can be matched to the matrix resin material used in photosensitive films, lenses, adhesives used in photoelectric integration, and the like. When fillers are added to improve the strength of resin materials while allowing light to pass through, the inclusion of particles with a high hollow ratio can cause haze, reducing light transmittance and sensitivity. In this regard, the spherical inorganic compositions of silica-alumina composite oxides of the embodiment have a reduced hollow ratio, which reduces diffuse reflection and addresses the problem of haze.

Claims

1. A spherical inorganic composition whose main component is an inorganic material other than simple silica, wherein the average particle size of the spherical inorganic composition measured by laser diffraction particle size distribution measurement is 0.1 to 15 μm, and the particles of the spherical inorganic composition containing voids of 5 μm or more in diameter are distributed at a density of 50 particles / mm ３ the spherical inorganic composition particles containing voids of 10 μm or more in diameter are 5 particles / mm ３ A spherical inorganic composition characterized by:

2. A 150 μm particle size distribution detected by cross-sectional analysis of a resin material containing the spherical inorganic composition when the resin material has a solid content of 70% by mass. ３ The spherical inorganic composition particles containing the above voids are 14 particles / mm ３ 35 μm or less detected by the tomographic cross-section analysis ３ The spherical particles of the inorganic composition containing voids are 50 particles / mm ３ The spherical inorganic composition according to claim 1, characterized in that:

3. The spherical inorganic composition according to claim 2, wherein the cross-sectional analysis is performed by X-ray CT or FIB-SEM.

4. The spherical inorganic composition according to claim 1, which comprises alumina, calcium titanate, or a silica-alumina composite oxide.

5. The spherical inorganic composition according to claim 1, wherein the content of uranium element in said spherical inorganic composition is 100 ppb or less.

6. The spherical inorganic composition according to claim 4, wherein the spherical inorganic composition is surface-treated with a silane compound.

7. A resin composition comprising the spherical inorganic composition according to claim 1 and a resin material for dispersing said spherical inorganic composition.

8. A slurry composition comprising the spherical inorganic composition according to claim 1 and a dispersion medium for dispersing said spherical inorganic composition.

9. A filler for a sealing material for semiconductor packages, comprising the spherical inorganic composition according to claim 1.

10. A method for analyzing voids in a spherical inorganic composition, comprising: a dispersion step of dispersing a spherical inorganic composition excluding simple silica in a resin composition; a cross-sectional analysis step of performing cross-sectional analysis of the spherical inorganic composition together with the resin composition using X-ray CT or FIB-SEM; and a void calculation step of preparing a three-dimensional image from the cross-sectional analysis and calculating the diameter and volume of voids present in the spherical inorganic composition.

11. The method for analyzing voids in a spherical inorganic composition according to claim 10, wherein a curing step of curing the resin composition is provided after the dispersing step.

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