JP2012227448A - Amorphous silica particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an amorphous silica particle capable of suppressing the generation of voids and the thickening with time when the amorphous silica particle is added to a hardening resin and is used as a sealant for a semiconductor.SOLUTION: The amorphous silica particle is an amorphous silica particle used for a sealant for a semiconductor, and is characterized that when a peak area of silicon atom in which a condensable group is not bonded thereto, is defined as A and a peak area of silicon atom in which two condensable groups are bonded thereto, is defined as B in a solid NMR spectrum, the ratio of both(%) represented by (B/A)×100 is less than 1.0%.

Description

  The present invention relates to amorphous silica particles that can be suitably used for a semiconductor sealing material such as an underfill material.

Conventionally, silica particles have been widely used as fillers for curable resin compositions used as semiconductor sealing materials such as underfill materials.
In recent years, as electronic devices have become more compact and functional, underfill mounting of electronic components mounted on electrical devices has been attempted with high density mounting, fine wiring, and low gap. Accordingly, silica particles used for semiconductor encapsulants are required to have a sharp particle size distribution, that is, a small variation coefficient of particle diameter.

  As a method for producing silica particles, methods such as a melting method and a gas phase method are also known. In particular, in order to obtain silica particles having a sharp particle size distribution, a method of hydrolyzing and condensing silicon alkoxide (alkoxysilane). (Hydrolysis method) has been preferably employed. As the hydrolysis method, for example, a dispersion of silica particles is obtained by hydrolyzing and condensing silicon alkoxide, and after concentrating without or concentrating to some extent, it is vacuum-dried and subjected to crushing as necessary. A method of firing at a predetermined temperature is common (for example, Patent Documents 1 to 3). Here, the reaction temperature for hydrolysis and condensation is usually from room temperature to about 40 ° C. at most. This is because if the reaction temperature is higher than that, the reaction rate becomes high and the particle growth becomes insufficient, so that only extremely fine particles can be obtained. Further, the concentration of the dispersion obtained by the reaction is usually performed at a relatively low temperature under reduced pressure from the viewpoint of production efficiency and energy cost reduction.

JP 2008-137854 A JP 2003-176121 A JP 2010-228997 A

  However, when the silica particles obtained by the hydrolysis method described above are used in the curable resin composition, the degree of polymerization of the epoxy resin is reduced during the curing, and gas is generated, which may cause voids. In addition, the curable resin composition thickens with time, and for example, it may be difficult to use as an underfill material.

  The present invention has been made paying attention to the above circumstances, and its purpose is to prevent voids and increase in viscosity over time when added to a curable resin to form a semiconductor sealing material. An object is to provide amorphous silica particles that can be suppressed.

  As a result of intensive studies to solve the above problems, the present inventors have found that the generation of voids and the increase in viscosity are caused by some of the alkoxy groups of the alkoxide in the silica particle raw material as they are or after hydrolysis. It was found that a substantial amount remained without condensation. If such unreacted condensable groups (alkoxy groups, hydroxyl groups, etc.) remain, when added to an epoxy resin to form a curable resin composition, the degree of polymerization of the epoxy resin decreases during curing and gas Occurred and voids were formed, or the condensable group reacted with the epoxy resin, resulting in thickening of the curable resin composition over time. Therefore, if the amount of the condensable group is suppressed to a certain amount or less, that is, the peak area of the silicon atom to which no condensable group is bonded in the solid state NMR spectrum, and the peak area of the silicon atom to which two condensable groups are bonded Using amorphous silica particles with a ratio of less than a specific value, it was found that even when added to a curable resin, generation of voids and thickening over time can be suppressed during curing, and the present invention was completed. .

  That is, the amorphous silica particles according to the present invention are amorphous silica particles used for a semiconductor encapsulant, and in the solid state NMR spectrum, the peak area of silicon atoms to which no condensable group is bonded is represented by A, When the peak area of the silicon atom to which two condensable groups are bonded is defined as B, the ratio (%) of both represented by (B / A) × 100 is less than 1.0%.

  The amorphous silica particles of the present invention preferably have a coefficient of variation in particle diameter of less than 15%, preferably an average particle diameter of 0.05 to 3 μm, and have a condensable group in the solid NMR spectrum. When the peak area of a silicon atom not bonded is A and the peak area of a silicon atom bonded with one condensable group is C, the ratio (%) of both expressed by (C / A) × 100 is 24. It is preferably less than 0.0%.

  According to the amorphous silica particles of the present invention, the predetermined peak area ratio in the solid state NMR spectrum is controlled within a specific range, so when added to a curable resin as a semiconductor encapsulant, Generation and thickening over time can be suppressed, and as a result, sealing with excellent conduction stability and strength can be achieved.

2 is a solid ²⁹ Si-NMR spectrum of the amorphous silica particles of Example 1. 2 is a solid ²⁹ Si-NMR spectrum of amorphous silica particles of Comparative Example 1.

The amorphous silica particles of the present invention have a solid NMR spectrum in which the peak area of silicon atoms to which no condensable group is bonded is A, and the peak area of silicon atoms to which two condensable groups are bonded is B. , (B / A) × 100, the ratio (%) of both is less than 1.0%. Here, a silicon atom to which a condensable group is not bonded (hereinafter sometimes referred to as “Si (SiO ₂ )”) has four non-reactive groups (oxygen atoms (hereinafter referred to as “oxygen atoms”) that constitute a siloxane bond). A silicon atom (hereinafter simply referred to as a siloxane bond), an alkyl group, an alkenyl group, an aryl group, etc.) and two condensable groups bonded together (hereinafter also referred to as “Si (SiX ₂ O)”) In addition to the condensable group, two non-reactive groups (such as a siloxane bond, an alkyl group, an alkenyl group, and an aryl group) are bonded. When the ratio ((B / A) × 100) is less than 1.0%, when silica particles are added to the curable resin and used as a semiconductor sealing material, generation of voids or time-lapse Thickening can be suppressed. The ratio ((B / A) × 100) is preferably 0.9% or less, more preferably 0.8% or less, and even more preferably 0.7% or less. This ratio is preferably as small as possible, particularly preferably 0.1% or less, and most preferably 0%.

In the amorphous silica particles of the present invention, in the solid state NMR spectrum, the peak area of silicon atoms to which no condensable group is bonded is A, and the peak area of silicon atoms to which one condensable group is bonded is C. Sometimes, the ratio (%) of both expressed by (C / A) × 100 is preferably less than 24.0%. Here, a silicon atom having one condensable group bonded thereto (hereinafter sometimes referred to as “Si (SiX ₁ O _1.5 )”) has three non-reactive groups (siloxane) in addition to the condensable group. A bond, an alkyl group, an alkenyl group, an aryl group, and the like). When the ratio ((C / A) × 100) is less than 24.0%, when silica particles are added to the curable resin and used as a semiconductor sealing material, generation of voids or over time Thickening can be suppressed more reliably. The ratio ((C / A) × 100) is preferably 22.0% or less, more preferably 21.0% or less, and further preferably 20.0% or less. This ratio is preferably as small as possible, particularly preferably 0.1% or less, and most preferably 0%.

  In the amorphous silica particles of the present invention, the above-described peak area A (peak area of silicon atom to which no condensable group is bonded), peak area B (peak area of silicon atom to which two condensable groups are bonded) The ratio of the peak area A to the sum of the peak areas C (peak areas of silicon atoms bonded with one condensable group) ([A / (A + B + C)] × 100) is preferably 80% or more. More preferably, it is 83% or more, More preferably, it is 85%.

The solid state NMR spectrum of the amorphous silica particles of the present invention can be obtained, for example, by performing solid ²⁹ Si-NMR measurement using tetramethylsilane as an internal standard substance. And the peak of the silicon atom (SiO ₂ ) to which the condensable group is not bonded and the silicon atom (SiX ₂ O) to which two condensable groups are bonded are analyzed by a peak analysis method using a Gaussian function. The peak area (peak area A, peak area B, peak area C) can be determined by separating the peak into a peak of silicon atom (SiX ₁ O _1.5 ) having one condensable group bonded thereto. For example, as an example of the solid ²⁹ Si-NMR spectrum, FIG. 1 shows the measurement results of the amorphous silica particles obtained in Example 1, and FIG. 2 shows the measurement results of the amorphous silica particles obtained in Comparative Example 1. Respectively. As can be seen from FIGS. 1 and 2, in the solid ²⁹ Si-NMR spectrum, the peak of separated SiO ₂ (reference numeral 3 in the figure) usually has a peak top in the vicinity of −110 δ / ppm, and was separated. The SiX ₁ O _1.5 peak (symbol 2 in the figure) usually has a peak top in the vicinity of −100 δ / ppm, and the separated SiX ₂ O peak (symbol 1 in the figure) is usually in the vicinity of −95 δ / ppm. Has a peak top. The solid ²⁹ Si-NMR measurement can be performed, for example, under the conditions described in Examples described later.

  The average particle size of the amorphous silica particles of the present invention is preferably 0.05 to 3 μm, more preferably 2 μm or less, further preferably 1.5 μm or less, more preferably 0.1 μm or more, and further preferably Is 0.15 μm or more, more preferably 0.3 μm or more. When the average particle diameter of the silica particles is too small, the silica particles are likely to aggregate and may be difficult to be pulverized into primary particles. On the other hand, when the average particle diameter of the silica particles is too large, it may be difficult to fill the curable resin composition containing silica particles as an underfill material for underfill mounting such as high-density mounting. The average particle diameter is a number-based average particle diameter, and can be measured, for example, by the method described in Examples described later.

  The amorphous silica particles of the present invention preferably have a particle diameter variation coefficient of less than 15%, more preferably 10% or less, and even more preferably 8% or less. Thus, since the coefficient of variation is small, it can be suitably used for underfill mounting such as high-density mounting. For example, the amorphous silica particles of the present invention produced as described below have a sharp particle size distribution and can realize a variation coefficient in the above range. The lower limit of the coefficient of variation is not particularly limited, but is usually 1% or more, preferably 2% or more, and more preferably 3% or more. The variation coefficient is a number-based variation coefficient of the particle diameter, and can be measured, for example, by the method described in Examples described later.

  The amorphous silica particles of the present invention can be produced, for example, by a hydrolysis method. According to the hydrolysis method, the particle size distribution can be narrowed. Moreover, in the present invention, the wet heat treatment described later is performed. By performing this wet heat treatment, the amorphous silica particles obtained have a predetermined peak area ratio in the solid NMR spectrum controlled in the above range. Specifically, for example, a step of hydrolyzing and condensing silicon alkoxide to produce silica particles, a step of subjecting the particles produced by the reaction to wet heat treatment at a temperature of 60 ° C. or higher in a liquid medium, A step of drying the particles after the wet heat treatment, and a step of firing the particles after the drying at a temperature of 800 ° C. to 1200 ° C. Hereinafter, an example of a preferable method for producing amorphous silica particles will be described in the order of the production steps.

(Hydrolysis condensation process of silicon alkoxide)
In order to obtain the amorphous silica particles of the present invention, first, a hydrolytic condensation reaction of silicon alkoxide is performed to produce silica particles. Hydrolytic condensation proceeds by stirring the silicon alkoxide in the presence of a catalyst (for example, ammonia, urea, amines, etc.) in water alone or in a solvent composed of water and an organic solvent, if necessary. As a result, spherical silica particles can be obtained in a state (dispersion liquid) dispersed in a liquid medium (solvent).

The silicon alkoxide may be any polyfunctional alkoxysilane having at least 2 (preferably 3 or more, particularly 4) alkoxy groups (particularly C _1-4 alkoxy groups) in one molecule. However, the silicon alkoxide has a non-reactive group such as an alkyl group such as a methyl group or an ethyl group; an alkenyl group such as a vinyl group; an aryl group such as a phenyl group; Also good. Examples of such silicon alkoxides include tetrafunctional silanes such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, and dimethoxydiethoxysilane; methyltrimethoxysilane, methyltriethoxysilane, and trimethoxy. 3 such as vinylsilane, triethoxyvinylsilane, 3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3- (2-aminoethylamino) propyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane Functional alkoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxy It includes known alkoxysilanes such as; run, diphenyldimethoxysilane, bifunctional alkoxysilanes such as diphenyl diethoxy silane. In order to obtain spherical and uniform silica particles, it is preferable to use at least one of tetrafunctional alkoxysilane and trifunctional alkoxysilane as the silicon alkoxide, and more preferably tetrafunctional alkoxysilane. In addition, as a silicon alkoxide, you may use together monofunctional alkoxysilanes, such as a trimethylmethoxysilane and a trimethylethoxysilane, with the said polyfunctional alkoxysilane. Silicon alkoxide may use only 1 type and may use 2 or more types together.

  The solvent may be water alone, but in order to obtain silica having a uniform particle diameter, it is preferable to contain an organic solvent in order to dissolve the silicon alkoxide. The organic solvent is preferably a hydrophilic one, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, 1 Alcohols such as 1,4-butanediol; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; Among these, from the viewpoint of drying efficiency at the time of drying performed after the reaction, those having a low boiling point (for example, a boiling point at normal pressure of 120 ° C. or lower) are preferable, and specifically, an aliphatic chain having 1 to 4 carbon atoms. More preferred are alcohols. Further, an organic solvent azeotroped with water such as n-butanol or propanol is preferred in order to easily distill off water that tends to cause secondary aggregation during drying. Only 1 type may be used for an organic solvent and it may use 2 or more types together. In addition, the content rate of the organic solvent in a solvent has preferable 50 mass% or less, More preferably, it is 30 mass% or less, More preferably, it is 10 mass% or less.

  The amount of silicon alkoxide used is such that the concentration of silicon alkoxide (Si concentration) relative to the total volume (charge) of the solvent, silicon alkoxide and catalyst used as necessary for carrying out the hydrolysis condensation reaction, 0.5 mol / L or more and 4 mol / L or less (lower limit is more preferably 1.0 mol / L or more, further preferably 1.2 mol / L or more, 1.5 mol / L or more, and upper limit is more preferably 3.5 mol / L. In the following, it is preferable that the range be 3 mol / L or less, more preferably 2.5 mol / L or less, and particularly preferably 2 mol / L or less. In particular, when the silicon alkoxide concentration at the time of charging the raw material is 1.0 mol / L or more, the predetermined peak area ratio in the solid NMR spectrum can be easily controlled by the range.

  Similarly, the concentration of water (that is, the concentration of water used relative to the total capacity (charge) of the solvent, silicon alkoxide and catalyst used as necessary) for carrying out the hydrolysis-condensation reaction was 2 mol / L or more and 25 mol / L or less (more preferably 5 mol / L or more and 20 mol / L or less) is preferable. Similarly, the concentration of the catalyst (that is, the concentration of the catalyst used with respect to the total volume (charge) of the solvent, silicon alkoxide and catalyst used as necessary for carrying out the hydrolysis condensation reaction) is 0.00. It is preferably 5 mol / L or more and 10 mol / L or less (more preferably 1 mol / L or more and 5 mol / L or less, more preferably 1 mol / L or more and 3 mol / L or less). In addition, when ammonia water is used, the concentration calculation is performed using ammonia contained in the ammonia water used as a catalyst and water contained as water.

  For example, the solvent (organic solvent, water), silicon alkoxide, and a catalyst used as necessary may be mixed together at the beginning (aspect 1), or a part of the organic solvent, water and the catalyst are mixed in advance. Thereafter, a mixed solution of an organic solvent and silicon alkoxide may be added (particularly dropwise) (Aspect 2), and the Aspect 2 is particularly preferable. By subjecting the silicon alkoxide to a slow hydrolysis and condensation reaction, the silica particles obtained in the hydrolysis and condensation step are likely to have few condensable groups, and a series of subsequent steps (wet heat treatment step, drying step, firing step) The amorphous silica particles obtained through the above process tend to have few condensable groups.

  The hydrolytic condensation reaction of silicon alkoxide is preferably performed at a temperature of less than 60 ° C., more preferably 55 ° C. or less, and even more preferably 50 ° C. or less. Thereby, since the reaction rate can be controlled, it is possible to sufficiently grow the particles to obtain silica particles having a desired particle diameter. In particular, in order to obtain silica particles with few condensable groups in the hydrolysis condensation step, it is preferable to control the temperature of the hydrolysis condensation reaction to 35 ° C. or lower. By setting the reaction temperature to 35 ° C. or less, it becomes easy to obtain silica particles with few unreacted condensable groups, and amorphous silica obtained through a series of subsequent steps (wet heat treatment step, drying step, firing step). The particles tend to have few condensable groups. For example, when obtaining fine silica particles having an average particle size of 0.50 μm or less (preferably 0.30 μm or less), from the viewpoint of particle size control, the reaction temperature is increased to increase particle nuclei. It may be advantageous to generate a high concentration. Even in such a case, it is preferable to control the temperature of the hydrolytic condensation reaction to 35 ° C. or lower. The lower limit of the reaction temperature during the hydrolysis condensation is not particularly limited, but is usually 0 ° C. or higher, preferably 5 ° C. or higher, more preferably 10 ° C. or higher. In addition, what is necessary is just to set the reaction time in the case of hydrolysis condensation suitably between 30 minutes or more and 100 hours or less according to reaction temperature etc., for example.

(Wet heat treatment process)
The silica particles produced by the hydrolysis condensation reaction are then subjected to a wet heat treatment in which heating is performed at a temperature of 60 ° C. or higher in a liquid medium. Thereby, the condensable group contained in the silica particle obtained can be reduced, and the predetermined peak area ratio in the solid NMR spectrum can be controlled within the above range. This wet heat treatment is usually performed by heating the reaction liquid obtained by the hydrolysis condensation reaction (a dispersion liquid in which silica particles are dispersed in a liquid medium (solvent)), but is not limited thereto. Instead, for example, the silica particles generated by the hydrolysis condensation reaction may be once isolated through drying and baking, and then dispersed in an appropriate liquid medium (solvent) and heated again. However, when the reaction liquid is heated as it is or when the silica particles separated from the reaction liquid are subjected to wet heat treatment without drying, the reaction activity of the silica particles is higher, and the condensable group reduction efficiency by wet heat treatment is higher. Since it increases, it is preferable.

  It is preferable that water is contained in the dispersion liquid (dispersion liquid in which silica particles are dispersed in a liquid medium) subjected to wet heat treatment. Furthermore, the dispersion liquid (dispersion liquid in which silica particles are dispersed in a liquid medium) always contains water during the wet heat treatment (in other words, while the liquid temperature of 60 ° C. or higher is maintained). It is preferable that Specifically, the preferable water concentration in the dispersion subjected to the wet heat treatment is 2 to 10 mol / L (more preferably 2 to 8 mol / L), and the water concentration in the dispersion is always 2 to 10 mol / L throughout the treatment. It is preferable to be maintained at L (more preferably 2 to 8 mol / L). By always controlling the water concentration in the dispersion within the above range throughout the wet heat treatment, silica particles with few condensable groups can be easily obtained.

  The dispersion to be subjected to the wet heat treatment (dispersion in which silica particles are dispersed in a liquid medium) preferably contains a hydrolysis catalyst such as ammonia and amines described above. Specifically, the catalyst concentration in the dispersion (reaction liquid) subjected to wet heat treatment is preferably 1 to 5 mol / L, more preferably 1 to 3 mol / L. In addition, when the wet heat treatment is completed (that is, when the liquid temperature is less than 60 ° C.), the catalyst is preferably reduced to 0.5 mol / L or less. When the catalyst concentration at the completion of the wet heat treatment is reduced to the above range, re-cleavage of the siloxane bond generated by condensation of the condensable group in the wet heat treatment is suppressed.

  The concentration of the silica particles in the dispersion (dispersion in which the silica particles are dispersed in the liquid medium) subjected to the wet heat treatment is preferably 1 mol / L or more, more preferably expressed in terms of silicon (Si) concentration. 1.2 mol / L or more, particularly preferably 1.5 mol / L or more. On the other hand, a preferable upper limit is 3 mol / L or less, and more preferably 2.0 mol / L or less. In addition, when the wet heat treatment is completed (that is, when the liquid temperature is less than 60 ° C.), the concentration of silica particles is usually 1 to 4 mol / L in terms of silicon (Si) concentration.

  In addition, the concentration of water, the concentration of the catalyst, and the concentration of silica particles (silicon concentration) in the dispersion subjected to the wet heat treatment can be measured by a titration method with respect to the concentrations of water and the catalyst. The silicon concentration can be calculated by theoretical calculation from the charged composition.

The heating temperature in the wet heat treatment may be at least 60 ° C. or higher, preferably 65 ° C. or higher, more preferably 70 ° C. or higher, and further preferably 75 ° C. or higher. The upper limit of the heating temperature in the wet heat treatment is preferably 200 ° C. or lower, more preferably 180 ° C. or lower, from the viewpoint of energy saving of the external heating supply source and the viewpoint of allowing water and catalyst to coexist even at normal pressure. Preferably it is 150 degrees C or less, Most preferably, it is 100 degrees C or less.
The wet heat treatment may be performed under normal pressure, reduced pressure, or increased pressure, and within a range where the heating temperature (liquid temperature) can be maintained in the above range, the degree of evaporation of the solvent and catalyst from the reaction solution, etc. It may be selected as appropriate in consideration. In addition, the atmosphere in the case of wet heat processing does not have a restriction | limiting in particular, For example, it can carry out in air atmosphere or nitrogen gas atmosphere.

(Drying process)
The dispersion after the wet heat treatment is then subjected to drying. The drying method is not particularly limited, and any of natural drying, atmospheric pressure heating drying, vacuum drying, and the like can be adopted, but vacuum drying is used to suppress secondary aggregation of silica particles in the drying process. In particular, vacuum drying using a vacuum instantaneous drying apparatus having a configuration to be described later is preferable.

  For the drying, the dispersion after the wet heat treatment may be used as it is, for example, by further concentrating the dispersion after the wet heat treatment or by adding a solvent (water or an organic solvent). You may make it use for drying, after adjusting the density | concentration and solvent composition of a silica particle. For example, in 100% by mass of the dispersion used for drying, the content of silica particles is preferably 5% by mass or more and 40% by mass or less, and more preferably 10% by mass or more and 30% by mass or less. If the content of the silica particles is 5% by mass or more, the solvent component to be vaporized and evaporated becomes small, so that the drying efficiency is improved. If the content is 40% by mass or less, for example, when using a vacuum instant drying device described later It is possible to avoid clogging the inside of the heating tube with silica particles. Moreover, in order to suppress the secondary aggregation of the silica particles, it is desirable to adjust to a solvent composition in which the proportion of the organic solvent contained in the dispersion used for drying is high and the proportion of moisture is low. In this case, specifically, when the total amount of the solvent constituting the dispersion is 100% by mass, the amount of the organic solvent other than water is preferably 50% by mass or more, more preferably 80% by mass or more. preferable.

  Hereinafter, the vacuum instantaneous drying apparatus preferably used in the drying process will be described. For example, one end of a heating tube that is heated externally and held under reduced pressure is connected to the supply part of the material to be dried (dispersion), and the other end is connected to a powder collecting chamber that is held under reduced pressure. The heating pipe has a configuration in which straight pipes and elbows are alternately connected. In such an apparatus, the dispersion liquid is heated while being transferred through the inside of the heating tube held at a reduced pressure, and a part or all of the solvent in the dispersion liquid is volatilized and a powder collection chamber held at a reduced pressure. If the silica particles are collected and the solvent remains, it is further dried. The temperature of the externally heated heating tube may be appropriately set according to the boiling point of the solvent, but is usually preferably about 150 ° C. or higher and 200 ° C. or lower. The temperature of the powder collection chamber is not particularly limited, but in order to remove the residual solvent, it is preferably about 150 ° C. or higher and 200 ° C. or lower as in the case of the heating tube. The pressure inside the heating tube and inside the powder collection chamber is preferably about 6 kPa to 27 kPa (gauge pressure). Moreover, it is preferable that the supply rate at the time of supplying a dispersion liquid to a heating tube from a supply part shall be 1 L / hour or more and 50 L / hour or less.

(Baking process)
The dried silica particles that have been powdered through the drying step are usually fired at a temperature of 800 ° C. or higher and 1200 ° C. or lower. By performing such firing, silica particles having low hygroscopicity can be obtained by condensing hydrophilic silanol groups and alkoxysilyl groups of the silica particles to form siloxane bonds and closing pores. When the firing temperature is less than 800 ° C., silanol groups remain, and a large number of fine pores tend to be formed on the surface of the silica particles, whereby the obtained silica particles have a relatively large hygroscopicity. There is a risk of becoming. On the other hand, when the firing temperature exceeds 1200 ° C., the silica particles are fused with each other, and there is a possibility that secondary agglomerates that cannot be pulverized even by a pulverizer are generated. The firing temperature is more preferably 900 ° C. or higher, further preferably 950 ° C. or higher, and still more preferably 1000 ° C. or higher. The upper limit of the firing temperature is usually 1150 ° C. or lower, preferably 1140 ° C. or lower, more preferably 1130 ° C. or lower. The firing time may be appropriately set according to the firing temperature, the particle size of the silica particles, and the like, but usually about 1 hour is sufficient. The atmosphere during firing is not particularly limited, but an oxidizing atmosphere, for example, an air atmosphere is preferable.

  The silica particles obtained through the firing may be subjected to a pulverization treatment as necessary in order to pulverize the secondary agglomerated particles into primary particles. For the pulverization treatment, for example, a high-speed rotating mill such as a hammer mill, a screen mill or a disk pin mill; a high-speed rotating mill with a built-in classifier such as a turbo mill or a cosmomizer; A crusher or a crusher may be used. The amorphous silica particles after pulverization can be further classified.

  Furthermore, the amorphous silica particles of the present invention are preferably surface-treated with a silane coupling agent. When the particle surface is coated with the organic group of the silane coupling agent by the surface treatment, the dispersibility in the curable resin (epoxy resin or the like) becomes good, and the fluidity as a semiconductor sealing material is improved. In addition, the surface treatment with the silane coupling agent may be performed by mixing the particles after firing with the silane coupling agent and heating before performing the pulverization treatment, or the presence of the silane coupling agent. You may make it perform a grinding | pulverization process and surface treatment simultaneously by grind | pulverizing below.

  Examples of the silane coupling agent include vinyl group-containing alkoxysilanes such as trimethoxyvinylsilane and triethoxyvinylsilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxy. Epoxy group-containing alkoxysilane such as propylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, etc. Methacryloxy group-containing alkoxysilane, 3-acryloxypropyltrimethoxysilane and other acryloxy group-containing alkoxysilane, 3-mercaptopropyltrimethoxysilane, etc. Alkoxysilane compounds such as mercapto group-containing alkoxysilanes and amino group-containing alkoxysilanes such as 3- (2-aminoethylamino) propyltrimethoxysilane; 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, methyltri Chlorosilane compounds such as chlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, methylvinyldichlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, methyldiphenylchlorosilane; tetraacetoxysilane, methyltriacetoxysilane, phenyltriacetoxysilane, dimethyldi Acyloxysilane compounds such as acetoxysilane, diphenyldiacetoxysilane, trimethylacetoxysilane; dimethyl Silanol compounds such as landiol, diphenylsilanediol, trimethylsilanol; 1,1,1,3,3,3-hexamethyldisilazane, 1,1,3,3-tetramethyldisilazane, 1,3-bis ( 3,3,3-trifluoropropyl) -1,1,3,3-tetramethyldisilazane, 1,3-bis (chloromethyl) tetramethyldisilazane, 1,3-diphenyltetramethyldisilazane, 1, 3-divinyl-1,1,3,3-tetramethyldisilazane, 2,2,4,4,6,6-hexamethylcyclotrisilazane, 2,4,6-trimethyl-2,4,6-tri Vinylcyclotrisilazane, heptamethyldisilazane, octamethylcyclotetrasilazane, hexamethyldisilazane lithium, hexamethyldisilazane sodium, hexame Silazanes such as potassium tildisilazane; 1,1,2,2-tetraphenyldisilane, 1,1,3,3-tetramethyldisiloxane, 1,2-bis (dimethylsilyl) benzene, 2- (dimethylsilyl) ) Pyridine, chlorodiisopropylsilane, chlorodimethylsilane, di-tert-butylsilane, dichloroethylsilane, dichloromethylsilane, diethoxymethylsilane, diethylsilane, dimethoxy (methyl) silane, dimethylphenylsilane, diphenylsilane, diphenylmethylsilane, Phenylsilane, N, O-bis (diethylhydrogensilyl) trifluoroacetamide, tert-butyldimethylsilane, tetrakis (dimethylsilyl) silane, tribenzylsilane, tributylsilane, triethoxysilane, triethyl Silane, trihexylsilane, triisopropylsilane, triphenyl silane, tris (trimethylsilyl) silane (Si-H) compounds such as silane; and the like. Among these, silazanes, vinyl group-containing alkoxysilanes, and epoxy group-containing alkoxysilanes are preferable because dispersibility in the resin can be further improved. A silane coupling agent may use only 1 type and may use 2 or more types together.

The amorphous silica particles of the present invention are amorphous silica particles used for a semiconductor sealing material. Specifically, the amorphous silica of the present invention is blended as a filler in a curable resin composition containing a resin component such as an epoxy resin.
The amorphous silica particles of the present invention are preferably used as an underfill material among semiconductor sealing materials. The underfill material is a curable resin composition that fills a gap between objects to be sealed (for example, a gap between a semiconductor chip and a substrate, a gap between solder balls) among semiconductor sealing materials. Such an underfill material is required to have such properties as being able to be sufficiently poured into a minute gap of an object to be sealed; being sufficiently cured to ensure connection reliability with respect to physical stress. As described above, the amorphous silica particles of the present invention can suppress the generation of voids and thickening over time, so that the fluidity is sufficient to be poured into the minute gaps of the object to be sealed. It is possible to provide an underfill material that is secured and excellent in connection reliability against physical stress.

Hereinafter, an underfill material will be described as an example of a semiconductor sealing material. However, the resin component and other components exemplified below are not unique to the underfill material, and can be used for all semiconductor sealing materials.
The content of the amorphous silica particles in the underfill material is 50 parts by mass or more (more preferably 80 parts by mass or more, more preferably 100 parts by mass or more) and 300 parts by mass or less (100 parts by mass). More preferably, it is 250 parts by mass or less, and more preferably 200 parts by mass or less.

  Examples of the resin component include an epoxy resin, a silicone resin, a polyimide resin, and a polyamide resin. These resins may be used alone or in combination of two or more. Among these, the epoxy resin is particularly excellent in dispersibility of the amorphous silica particles of the present invention, and the thickening suppression effect which is one of the effects when using the amorphous silica particles of the present invention is remarkable. It is also preferable from the point of being exhibited.

  The epoxy resin means a compound having at least one epoxy group in the molecule, and the epoxy group means one containing an oxirane ring which is a three-membered ether. Particularly preferred are polyfunctional epoxy compounds having two or more epoxy groups in the molecule. Examples thereof include aromatic epoxy compounds, aliphatic epoxy compounds, alicyclic epoxy compounds, and hydrogenated epoxy compounds. Among these, an alicyclic epoxy compound and a hydrogenated epoxy compound are preferable from the viewpoint that a cured product (sealing) excellent in heat resistance and light resistance can be easily obtained.

The aromatic epoxy compound is a compound having an aromatic ring and an epoxy group in the molecule. As the aromatic epoxy compound, for example, a glycidyl compound having an aromatic ring conjugated system such as a bisphenol skeleton, a fluorene skeleton, a biphenyl skeleton, a naphthalene ring or an anthracene ring is preferable. Specifically, bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, fluorene type epoxy compounds, aromatic epoxy compounds having a bromo substituent, etc. are preferred, and bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, etc. are more preferred. It is.
An aromatic glycidyl ether compound is also suitable as the aromatic epoxy compound. Examples of the aromatic glycidyl ether compound include an epibis type glycidyl ether type epoxy resin, a high molecular weight epibis type glycidyl ether type epoxy resin, and a novolak / aralkyl type glycidyl ether type epoxy resin.

  As the aliphatic epoxy compound, for example, an aliphatic glycidyl ether type epoxy resin is suitable. Examples of the aliphatic glycidyl ether type epoxy resin include those obtained by a condensation reaction between a polyol compound and epihalohydrin. Examples of the polyol compound include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (PEG 600), propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol (PPG), glycerol, diethylene Examples include glycerol, tetraglycerol, polyglycerol, trimethylolpropane and multimers thereof, pentaerythritol and multimers thereof, mono / polysaccharides such as glucose, fructose, lactose and maltose, etc., propylene glycol skeleton, alkylene skeleton, oxyalkylene Those having a skeleton are preferred. As the aliphatic glycidyl ether type epoxy resin, an aliphatic glycidyl ether type epoxy resin having a propylene glycol skeleton, an alkylene skeleton and an oxyalkylene skeleton in the central skeleton is preferable.

The alicyclic epoxy compound is a compound having an alicyclic epoxy group. Examples of the alicyclic epoxy group include an epoxycyclohexane group (epoxycyclohexane skeleton), an epoxy group added to a cyclic aliphatic hydrocarbon directly or via a hydrocarbon, and the like.
Examples of the alicyclic epoxy compound include 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, epsilon-caprolactone-modified 3,4-epoxycyclohexylmethyl 3 ′, 4′-epoxycyclohexanecarboxylate. Epoxy compounds having an epoxycyclohexane group such as bis- (3,4-epoxycyclohexyl) adipate; 1,2-epoxy-4- (2-oxiranyl) cyclohexane of 2,2-bis (hydroxymethyl) -1-butanol Examples thereof include adducts and epoxy resins containing heterocyclic rings such as triglycidyl isocyanurate. Among these, a compound having an epoxycyclohexane group is preferable. Moreover, the polyfunctional alicyclic epoxy compound which has two or more alicyclic epoxy groups in a molecule | numerator is suitable at the point which can raise a hardening rate more. A compound having one alicyclic epoxy group in the molecule and an unsaturated double bond group such as a vinyl group is also preferably used.

  The hydrogenated epoxy compound is a compound obtained by hydrogenating (reducing) an unsaturated bond of a compound having an unsaturated bond and an epoxy group in the molecule. The hydrogenated epoxy compound is preferably a compound having a glycidyl ether group directly or indirectly bonded to a saturated aliphatic cyclic hydrocarbon skeleton, and a polyfunctional glycidyl ether compound is preferred. The hydrogenated epoxy compound is preferably a complete or partial hydrogenated product of an aromatic epoxy compound, more preferably a hydrogenated product of an aromatic glycidyl ether compound, and still more preferably an aromatic polyfunctional glycidyl. It is a hydrogenated product of an ether compound. Specifically, hydrogenated bisphenol A type epoxy compound, hydrogenated bisphenol S type epoxy compound, hydrogenated bisphenol F type, which are hydrogenated compounds of bisphenol A type epoxy compound, bisphenol S type epoxy compound, bisphenol F type epoxy compound Epoxy compounds are preferred. More preferred are hydrogenated bisphenol A type epoxy compounds and hydrogenated bisphenol F type epoxy compounds.

  The epoxy resin preferably contains a polyfunctional epoxy compound having a weight average molecular weight of 2000 or less (preferably a weight average molecular weight of 1000 or less). The content of the polyfunctional epoxy compound having such a predetermined weight average molecular weight is preferably 40% by mass or more, more preferably 60% by mass or more, more preferably 80% by mass in 100% by mass of the epoxy resin. As described above, the content is particularly preferably 100% by mass.

  In the epoxy resin-based underfill material, a conventionally known epoxy resin curing agent can be used to cure the epoxy resin as a resin component. As the curing agent, an acid anhydride curing agent, a phenol curing agent, an amine curing agent, or the like can be used as an addition curing agent. In addition, only 1 type may be used for a hardening | curing agent and it may use 2 or more types together.

  Examples of the acid anhydride curing agent include hydrogenated phthalic anhydride (including derivatives) (tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, hexahydrophthalic anhydride). , Methylhexahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, etc.), nadic acid anhydride, methyl nadic acid anhydride, het acid anhydride, hymic acid anhydride, 5- (2,5-dioxotetrahydro Furyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trialkyltetrahydrophthalic anhydride-maleic anhydride adduct, alicyclic carboxylic anhydrides such as chlorendic acid; dodecenyl succinic anhydride, Fats such as polyazeline acid anhydride, polysebacic acid anhydride, polydodecanedioic acid anhydride Carboxylic anhydride: phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol trimellitic anhydride, biphenyltetracarboxylic anhydride, and other aromatic carboxylic anhydrides Etc.

  Examples of the phenolic curing agent include bisphenol A, tetrabromobisphenol A, bisphenol F, bisphenol S, 4,4′-biphenylphenol, 2,2′-methylene-bis (4-methyl-6-tert-butylphenol). ), 2,2′-methylene-bis (4-ethyl-6-tert-butylphenol), 4,4′-butylene-bis (3-methyl-6-tert-butylphenol), 1,1,3-tris ( 2-methyl-4-hydroxy-5-tert-butylphenol), trishydroxyphenylmethane, pyrogallol, phenols having a diisopropylidene skeleton; phenols having a fluorene skeleton such as 1,1-di-4-hydroxyphenylfluorene ; Polyphenols such as phenolized polybutadiene Novolak resins made from various phenols such as diol compounds, phenols, cresols, ethylphenols, butylphenols, octylphenols, bisphenol A, brominated bisphenol A, bisphenol F, bisphenol S, naphthols; phenol novolac containing xylylene skeleton Various novolak resins such as resins, dicyclopentadiene skeleton-containing phenol novolak resins, and fluorene skeleton-containing phenol novolak resins are exemplified.

  Examples of the amine curing agent include aliphatic polyamine curing agents and aromatic polyamine curing agents. Aliphatic polyamine-based curing agents include chain aliphatic polyamines such as diethylenetriamine, triethylenetriamine, tetraethylenepentamine, dipropylenediamine, diethylaminopropylamine; cyclics such as N-aminoethylpiperazine, mensendiamine, and isophoronediamine Aliphatic polyamines; m-xylenediamine, xylylenediamine, and aliphatic polyamines having an aromatic ring such as xylylenediamine trimer. Examples of the aromatic polyamine curing agent include metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone and the like. As the amine-based curing agent, various modified amines obtained by modifying the above-described amine-based curing agent for the purpose of adjusting pot life, curing rate, compatibility with resin, and the like can also be used.

  In particular, in the epoxy resin-based underfill material containing the amorphous silica particles of the present invention, it is preferable to use an acid anhydride-based curing agent as the curing agent in order to secure excellent fluidity by keeping the viscosity low. Of these, alicyclic carboxylic anhydrides are preferable, and hydrogenated phthalic anhydride (including derivatives) is more preferable. Moreover, in order to improve the adhesiveness of the hardened | cured material with respect to a board | substrate, copper wiring, and an electrode, an amine type hardening | curing agent is preferable. Further, among the amine-based curing agents, aliphatic polyamines are preferable from the viewpoint of excellent fluidity as an underfill material, among which chain aliphatic polyamines and cyclic aliphatic polyamines are preferable, and cyclic aliphatic polyamines are more preferable.

  The mixing ratio of the epoxy resin and the addition type curing agent is preferably 0.5 to 1.6 equivalents of the addition type curing agent with respect to one chemical equivalent of the epoxy resin. The addition type curing agent is more preferably 0.7 to 1.4 equivalents, and still more preferably 0.9 to 1.2 equivalents per chemical equivalent of the epoxy resin.

In the epoxy resin-based underfill material, a conventionally known curing accelerator may be used in combination with the curing agent. Examples of the curing accelerator include organic base acid salts or aromatic compounds having tertiary nitrogen. Examples of the organic base acid salt include organic onium salts such as organic phosphonium salts and organic ammonium salts, and organic base acid salts having tertiary nitrogen. Examples of organic phosphonium salts include phosphonium bromides having four phenyl rings such as tetraphenyl phosphonium bromide and triphenyl phosphine / toluene bromide. Examples of organic ammonium salts include tetraoctyl ammonium bromide, tetra Examples include tetra (C1-C8) alkylammonium bromides such as butylammonium bromide and tetraethylammonium bromide. Examples of acid salts of organic bases having tertiary nitrogen include alicyclic bases having tertiary nitrogen in the ring. Examples include acid salts and organic acid salts of various imidazoles. A hardening accelerator may use only 1 type and may use 2 or more types together.
The amount of the curing accelerator used is preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.03% by mass or more, with respect to 100% by mass of the total amount of the epoxy resin and the curing agent. 3% by mass or less.

  In the epoxy resin-based underfill material, a cation curing catalyst such as a conventionally known thermal cation curing catalyst or photo cation curing catalyst may be contained instead of the above-mentioned addition type curing agent. The content of the cationic curing catalyst is preferably 0.01 to 10% by mass with respect to 100% by mass of the total amount of the epoxy resin.

  The underfill material includes the amorphous silica particles of the present invention and the resin component described above, as well as an antioxidant, a reactive diluent, a saturated compound having no unsaturated bond, a pigment, a dye, and an antioxidant. Adhesives such as additives, UV absorbers, light stabilizers, plasticizers, non-reactive compounds, chain transfer agents, thermal polymerization initiators, anaerobic polymerization initiators, polymerization inhibitors, inorganic fillers, organic fillers, coupling agents, etc. Improving agent, heat stabilizer, antibacterial / antifungal agent, flame retardant, matting agent, antifoaming agent, leveling agent, wetting / dispersing agent, anti-settling agent, thickener / anti-sagging agent, anti-coloring agent, An emulsifier, slip / scratch prevention agent, anti-skinning agent, desiccant, antifouling agent, antistatic agent, conductive agent (electrostatic aid) and the like may be contained.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

In the following examples and comparative examples, the physical properties of amorphous silica particles were measured by the following methods.
(Average particle size and coefficient of variation)
Scanning electron micrographs of arbitrarily collected amorphous silica particles were taken, the diameters of 50 arbitrary particles in the obtained photographs were measured with calipers, and the number average value was obtained. In the scanning electron micrograph, the measurement magnification is set so that the number of particles is 50 to 100 in the field of view of one photograph (for example, 10000 for silica particles having an average particle diameter of 1 μm). Set the measurement magnification to double).
The variation coefficient of the particle diameter was calculated by the following formula after obtaining the standard deviation of the particle size by the following formula.

Ｄ_i：粒子径
Ｄ_ave：平均粒子径

D _i : Particle diameter D _ave : Average particle diameter

(Solid ²⁹ Si-NMR spectrum)
As a device, “AVANCE400” manufactured by BRUKER was used, and solid ²⁹ Si-NMR measurement was performed under the following conditions using tetramethylsilane as an internal standard substance. Then, a peak area A of Si (SiO ₂ ) (−110 ppm), a peak area C of Si (SiX ₁ O _1.5 ) (−100 ppm), and a peak area B of Si (SiX ₂ O) (−95 ppm) are obtained, The following values regarding the silicon atomic ratio were calculated.
Si (SiX ₂ O) / Si (SiO ₂ ) = (B / A) × 100 (%)
Si (SiX ₁ O _1.5 ) / Si (SiO ₂ ) = (C / A) × 100 (%)
Si (SiO ₂ ) / Si (SiX ₂ O) + Si (SiX ₁ O _1.5 ) + Si (SiO ₂ ) = [A / (B + C + A)] × 100 (%)

^<29 Si-NMR measurement conditions>
Equipment: “AVANCE400” manufactured by BRUKER
Sample tube: 7 mm Zirconia rotation speed: 6 kHz
Observation nucleus: ²⁹ Si nucleus Observation nuclear resonance frequency: 79.487 MHz
¹ H nuclear resonance frequency: 400.132 MHz
Pulse program: DD / MAS (Dipole decoupling method)
Observation nuclear pulse width: 2.7 μs (45 ° pulse)
Repetition time: 170 seconds Integration frequency: 256 Observation temperature: Room temperature standard substance Chemical shift value: Sodium 3- (trimethylsilyl) propane-1-sulfonate (1.534 ppm) External standard

Example 1
[Hydrolysis condensation step]
A 20 L glass reactor equipped with a stirrer, a dropping device and a thermometer is charged with 800 parts by mass of methanol as a solvent, 200 parts by mass of 28% by mass ammonia water (water and catalyst), and 100 parts by mass of water. The liquid temperature was adjusted to 30 ± 0.5 ° C. while stirring. Meanwhile, 500 parts by mass of tetramethoxysilane as silicon alkoxide was charged into the dropping device. And it dripped over 2 hours from a dripping apparatus, and after completion | finish of dripping, by continuing further stirring for 1 hour, hydrolytic condensation of tetramethoxysilane is performed and the dispersion liquid of the spherical silica particle with an average particle diameter of 0.31 micrometer is obtained. It was.
In the above reaction, the composition of the charging standard of each raw material during the reaction was tetramethoxysilane concentration (Si concentration): 1.8 mol / L, water concentration: 7.4 mol / L, ammonia concentration: 1.8 mol / L. It was. In addition, the water concentration in the obtained reaction solution was 3.8 mol / L (note that the Si concentration and the ammonia concentration were almost the same as the charged standard concentrations).
The water concentration in the dispersion was measured by the Karl Fischer method, and the ammonia concentration in the dispersion was measured by the neutralization titration method (the same applies to the following measurement of water concentration and ammonia concentration).

[Wet heat treatment process]
Next, the obtained dispersion of silica particles is transferred to a round flask equipped with a stirrer and a cooling tube, and heated from the outside of the reactor with a heating medium maintained at 150 ° C. while stirring at normal pressure. The temperature was maintained at 65 ° C. or higher (65 ° C. to 90 ° C.) for 5 hours or longer, and wet heat treatment was performed. At this time, a part of the solvent (methanol), ammonia, water, and the like is distilled off, and the silica particle concentration is 20% by mass (silicon (Si) concentration is 3.3 mol / L), and the water is 14% by mass (7.8 mol). / L), a slurry containing 0.5% by mass of ammonia (0.3 mol / L) and the balance of methanol (about 65% by mass) was obtained (measurement method of each concentration was performed in each reaction solution after the above reaction). Same as concentration measurement).

[Drying process]
Next, the obtained slurry was dried with a vacuum dryer. The vacuum drying apparatus used was provided with a heating tube made of SUS316 in which two straight tubes having an inner diameter of 10 mm and a length of 800 mm were connected by one 180 ° elbow having a length (length of the inner wall on the outer peripheral side) of 160 mm, One end of the heating tube is connected to the slurry supply unit, and the other end is connected to the powder collecting chamber. Specifically, the inside of the heating tube and the inside of the collection chamber are depressurized to 50 Torr (6.6 kPa), the temperature of the collection chamber is 150 ° C., and external heating means is used so that the temperature inside the heating tube is 175 ° C. While heating with superheated steam, the slurry obtained above was supplied from the slurry supply unit to the heating tube at a supply rate of 20 L / hour. Thereby, dry silica particles were obtained.

[Baking process]
Next, the obtained dried silica particles were put in a crucible, baked at 800 ° C. for 1 hour using an electric furnace, then cooled and ground to obtain amorphous silica particles (1). Table 1 shows the average particle diameter, the coefficient of variation of the particle diameter, and the solid ²⁹ Si-NMR spectrum of the obtained amorphous silica particles. In addition, the obtained ²⁹ Si-NMR spectrum chart is shown in FIG.

(Example 2)
Amorphous silica particles (2) were obtained in the same manner as in Example 1, except that the firing temperature in the firing step in Example 1 was changed from 800 ° C to 1000 ° C. Table 1 shows the average particle diameter, the coefficient of variation of the particle diameter, and the solid ²⁹ Si-NMR spectrum of the obtained amorphous silica particles.

(Comparative Example 1)
The silica particle dispersion obtained by the hydrolytic condensation reaction in Example 1 was directly subjected to drying as a slurry without being subjected to wet heat treatment, and the firing temperature in the firing step was changed from 800 ° C to 1000 ° C. Except that, comparative amorphous silica particles (C1) were obtained in the same manner as in Example 1. Table 1 shows the average particle diameter, the coefficient of variation of the particle diameter, and the solid ²⁹ Si-NMR spectrum of the obtained amorphous silica particles. In addition, the obtained ²⁹ Si-NMR spectrum chart is shown in FIG.

The following evaluation was performed about the amorphous silica particle obtained by the above Example and the comparative example.
<Flow stability>
First, a curable resin composition containing amorphous silica particles was prepared. That is, 100 parts by mass of a bisphenol A type epoxy resin (“jER (registered trademark) 828” manufactured by Mitsubishi Chemical Corporation) and an acid anhydride-based curing agent (“Rikacid (registered trademark) MH—manufactured by Shin Nippon Rika Co., Ltd.)” 700 G "; 4-methylhexahydrophthalic anhydride / hexahydrophthalic anhydride = 70/30 (mass ratio) 80 parts by mass and a resin composition obtained by mixing 1 part by mass of an imidazole-based curing accelerator as a curing accelerator Next, 60 parts by mass of amorphous silica particles were added to 40 parts by mass of the resin composition, mixed, and stirred to prepare a curable resin composition.

The viscosity (initial viscosity) of the curable resin composition immediately after production was measured, and after this curable resin composition was allowed to stand at 25 ° C. for 24 hours, the viscosity of the curable resin composition (viscosity after 24 hours) was measured again. The viscosity change rate was calculated based on the following formula. The viscosity was measured under the conditions of 25 ° C. and 5 rpm with a CP-42 cone attached to a Brookfield viscometer.
Viscosity change rate (%) = (viscosity after 24 hours / initial viscosity-1) × 100
The case where the viscosity change rate was less than 100% was evaluated as “◯”, the case where it was 100 to 200% was evaluated as “Δ”, and the case where it was over 200% was evaluated as “×”.

<Occurrence of voids>
First, a curable resin composition was prepared in the same manner as the flow stability evaluation, and immediately, a casting mold comprising two release-treated glass plates having a length of 200 mm and a width of 50 mm and a 4 mm spacer. And heated at 180 ° C. for 6 hours in a heating furnace, then cooled and taken out of the mold to prepare a sheet-like cured product having a thickness of 4 mm. Then, the obtained cured product was cut into a rectangle having a length of 80 mm and a width of 10 mm (thickness: 4 mm) to obtain a test sample, and an ultrasonic cross-section observation device (SAT) for a range of 10 mm × 10 mm of the test sample surface. Was used to examine the presence or absence of voids having a diameter of 5 μm or more.

Claims (4)

Amorphous silica particles used for a semiconductor sealing material,
In a solid state NMR spectrum, (B / A) × 100, where A is the peak area of a silicon atom to which no condensable group is bonded, and B is the peak area of a silicon atom to which two condensable groups are bonded. Amorphous silica particles characterized in that the ratio (%) of both is less than 1.0%.   The amorphous silica particles according to claim 1, wherein the coefficient of variation in particle diameter is less than 15%.   The amorphous silica particles according to claim 1 or 2, having an average particle diameter of 0.05 to 3 µm.   In a solid state NMR spectrum, when the peak area of a silicon atom to which no condensable group is bonded is A and the peak area of a silicon atom to which one condensable group is bonded is C, (C / A) × 100 The amorphous silica particles according to any one of claims 1 to 3, wherein the ratio (%) of the two is less than 24.0%.

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