JP5695960B2 - Amorphous silica particles - Google Patents

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 added to a resin component such as an epoxy resin to form a curable resin composition, if this is used as a semiconductor sealing material, the durability (strength of the cured product) ) May be insufficient, or the dispersibility in the resin component may deteriorate, resulting in a decrease in fluidity and difficulty in filling when used for underfill mounting such as high-density mounting.

  The present invention has been made paying attention to the above circumstances, and its purpose is to form a highly durable cured product when added to a curable resin to form a semiconductor sealing material. Amorphous silica particles that can be used suitably for underfill mounting such as high-density mounting with excellent dispersibility with respect to the curable resin and good fluidity. It aims at providing the sealing material for semiconductors using this.

As a result of intensive studies to solve the above problems, the present inventors have found that the durability of the cured product and the dispersibility in the resin component are adjacent to each other through oxygen, particularly among the silanol groups in the silica particles. A form in which one or more silanol groups are bonded to two Si atoms each (vicinal type) and / or a form in which two silanol groups are bonded to one Si atom (Geminal type) It is understood that the amount of silanol groups present in (the silanol groups in such a form that can be generated by water adsorption may be collectively referred to as “adsorbed water-derived silanol groups” hereinafter) has an effect. It was. Specifically, if there are too many adsorbed water-derived silanol groups, the resulting cured product will increase the hygroscopicity, resulting in reduced durability. If there are too few adsorbed water-derived silanol groups, the dispersibility in the resin component will be poor. It becomes. Moreover, with regard to the dispersibility in the resin component, the silica particles have been conventionally surface-treated with a silane coupling agent with the aim of improving the dispersion, but if there are too few adsorbed water-derived silanol groups, the silane coupling agent It was also found that the reactivity itself with the liquid crystal was lowered and the effect of improving dispersibility was not sufficiently obtained. Therefore, if the amount of the adsorbed water-derived silanol group is controlled within a specific range, that is, in the Fourier transform infrared absorption spectrum (FT-IR), the OH bond of the adsorbed water-derived silanol group having a peak top at 3400-3500 cm ^−1. Amorphous silica particles in which the ratio (I (adOH) / I (SiO)) of the peak maximum absorbance (I (adOH)) to the peak absorbance of the siloxane bond (I (SiO)) is in a specific range If used, when added to a curable resin to obtain a semiconductor encapsulant, a highly durable cured product can be obtained, and dispersibility in the resin component can be enhanced to ensure good fluidity. The present invention has been completed.

That is, the amorphous silica particles according to the present invention are amorphous silica particles used for a semiconductor sealing material, and have a peak top at 3400 to 3500 cm ⁻¹ in a Fourier transform infrared absorption spectrum (FT-IR). The ratio (I (adOH) / I (SiO)) of the maximum absorbance (I (adOH)) of the OH bond peak of the silanol group having and the maximum absorbance (I (SiO)) of the siloxane bond peak is 0.0010 or more It is less than 0.0025.

The amorphous silica particles of the present invention preferably have an average particle size of 0.45 μm or less, and the coefficient of variation in particle size is preferably less than 15%. Further, the amorphous silica particles of the present invention have a maximum absorbance (I (isoOH)) of OH bond peak of silanol group having a peak top in the vicinity of 3750 cm ⁻¹ and siloxane in Fourier transform infrared absorption spectrum (FT-IR). The ratio (I (isoOH) / I (SiO)) to the maximum absorbance (I (SiO)) of the binding peak is preferably 0.00010 or more and less than 0.002. Furthermore, the amorphous silica particles of the present invention are preferably surface-treated with a silane coupling agent.

  The sealing material for semiconductors of this invention is characterized by containing the amorphous silica particle of the said invention, an epoxy resin, and a hardening | curing agent. The curing agent is preferably an acid anhydride curing agent.

  According to the amorphous silica particles of the present invention, the maximum absorbance (I (adOH)) of the OH bond peak of the silanol group derived from adsorbed water and the maximum of the siloxane bond peak in the Fourier transform infrared absorption spectrum (FT-IR). Since the ratio (I (adOH) / I (SiO)) to the absorbance (I (SiO)) is controlled within a specific range, it is durable when added to a curable resin as a semiconductor encapsulant. Can be formed. In addition, since it has excellent dispersibility with respect to the curable resin and ensures good fluidity, it can be suitably used for underfill mounting such as high-density mounting.

Amorphous silica particles of the present invention have a maximum absorbance (I (adOH)) of OH bond peak of silanol group having a peak top at 3400-3500 cm ⁻¹ and siloxane in Fourier transform infrared absorption spectrum (FT-IR). The ratio (I (adOH) / I (SiO)) to the maximum absorbance (I (SiO)) of the binding peak is 0.0010 or more and less than 0.0025. That is, the amorphous silica particles of the present invention are those in which the amount of silanol groups derived from adsorbed water having a peak top at 3400 to 3500 cm ⁻¹ is controlled within a specific range. When the ratio (I (adOH) / I (SiO)) is 0.0010 or more, the dispersibility when added to a resin component such as an epoxy resin is increased, and the curable resin composition has good fluidity. Is obtained. In addition, when the surface treatment is performed with a silane coupling agent, the silane coupling agent is easily bonded to the surface of the silica particles, and the silane coupling agent is uniformly bonded to the surface of the silica particles, so that dispersibility can be further improved. It becomes possible. On the other hand, when the ratio (I (adOH) / I (SiO)) is less than 0.0025, the moisture absorption of the cured product when added to a resin component such as an epoxy resin and used as a semiconductor sealing material. Property can be suppressed, and a highly durable cured product can be formed. The ratio (I (adOH) / I (SiO)) is preferably 0.0013 or more, more preferably 0.0015 or more, preferably 0.0023 or less, more preferably 0.0021 or less.

  In order to control the ratio (I (adOH) / I (SiO)) within the above-described range, for example, when the amorphous silica particles are produced by a hydrolysis method, a wet heat treatment described later is performed and firing is performed. What is necessary is just to perform at the temperature of 900-1150 degreeC. In addition, it is also effective to control the ratio (I (adOH) / I (SiO)) to the above-mentioned range by setting the concentration of the silicon alkoxide as a raw material to 1.0 mol / L or more. .

The amorphous silica particles of the present invention further have a maximum absorbance (I (isoOH)) of the peak of the OH bond of a silanol group having a peak top in the vicinity of 3750 cm ⁻¹ in a Fourier transform infrared absorption spectrum (FT-IR). The ratio (I (isoOH) / I (SiO)) to the maximum absorbance (I (SiO)) of the peak of the siloxane bond is preferably 0.00010 or more and less than 0.002. Here, the silanol group having a peak top in the vicinity of 3750 cm ⁻¹ is a silanol group present in isolation among silanol groups in silica particles, that is, adjacent to both Si atoms to which the silanol group is bonded. It is a silanol group (Isolated type) that exists in a form in which no silanol group is bonded to the Si atom (hereinafter, this silanol group may be referred to as an “isolated silanol group”). That is, it is preferable that the amount of the isolated silanol group is also controlled within a specific range. When the ratio (I (isoOH) / I (SiO)) is less than 0.00010, when added to and dispersed in a resin component such as an epoxy resin, the dispersibility may be reduced, resulting in uneven dispersion. On the other hand, when the ratio (I (isoOH) / I (SiO)) is 0.002 or more, the cohesive force of particles tends to increase, and aggregation tends to easily occur during firing. The ratio (I (isoOH) / I (SiO)) is more preferably 0.00012 or more, further preferably 0.00013 or more, more preferably 0.00100 or less, still more preferably 0.00090 or less, and more Preferably it is 0.00060 or less, Most preferably, it is 0.00040 or less.

  In order to control the ratio (I (isoOH) / I (SiO)) within the above-described range, for example, when amorphous silica particles are produced by a hydrolysis method, a wet heat treatment described later is performed and firing is performed. Is carried out at a temperature of 900 to 1150 ° C., and the charge ratio of water and silicon alkoxide in the hydrolysis-condensation reaction is such that water is at least 1 mol, more preferably at least 3 mol and not more than 5 mol relative to silicon alkoxide. It is recommended that

The measurement conditions for obtaining the Fourier transform infrared absorption spectrum (FT-IR) of the amorphous silica particles of the present invention are not particularly limited, and for example, the conditions described later in the examples can be adopted. In the Fourier transform infrared absorption spectrum chart, the peak of silanol group derived from adsorbed water will appear as a broad peak at 3200～3600Cm ^-1, has a peak top (maximum value) 3400～3500Cm ^-1 (this time peak top It is not limited to one and may be two or more). The peak of the siloxane bond appears as a sharp peak having a peak top (maximum value) at 1000 to 1200 cm ⁻¹ . The peak of the isolated silanol group appears as a sharp peak having a peak top (maximum value) in the vicinity of 3750 cm ⁻¹ .

In the Fourier transform infrared absorption spectrum (FT-IR), for example, vibration due to OH bonds of water adsorbed on silica particles appears as a peak having a peak top in the vicinity of 3300 cm ^−1. It may overlap with the broad peak of the silanol group derived from it. However, even if the skirts overlap, the effect is small, and the height of the peak at 3400-3500 cm ⁻¹ sufficiently reflects the amount of silanol groups derived from the adsorbed water. Therefore, the ratio of the maximum absorbance (I (AdOH) / I (SiO)) can improve the durability of the cured product and the dispersibility in the resin component.

  The average particle diameter of the amorphous silica particles of the present invention is preferably 3 μm or less, more preferably 1.5 μm or less, still more preferably 1.0 μm or less, and most preferably 0.45 μm or less. If the average particle diameter of the silica particles is too large, it may be difficult to fill when using a curable resin composition containing silica particles as an underfill material for underfill mounting such as high-density mounting. However, if the average particle size of the silica particles is too small, the silica particles are likely to aggregate and may be difficult to disintegrate into primary particles. Therefore, the average particle size of the silica particles is preferably 0.05 μm or more, More preferably, it is 0.1 micrometer or more, More preferably, it is 0.15 micrometer or more. 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 obtained amorphous silica particles have the ratio (I (adOH) / I (SiO)) in the infrared spectrum controlled within 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 900 ° C. or higher and 1150 ° C. or lower. 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 a 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 azeotropic with water such as n-butanol or n-propanol is preferable in order to facilitate distilling 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 (the lower limit is more preferably 1.0 mol / L or more, further preferably 1.2 mol / L or more, more preferably 1.5 mol / L or more, and the upper limit is more preferably 3. 5 mol / L or less, more preferably 3 mol / L or less, still more preferably 2.5 mol / L or less, 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 ratio (I (adOH) / I (SiO)) in the infrared spectrum can be easily controlled in the above 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 3 mol / L or more, further preferably 4 mol / L or more, more preferably 5 mol / L or more, more preferably 20 mol / L or less, more preferably 10 mol / L or less). Is preferred. 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.

  Furthermore, the charge ratio of water and silicon alkoxide in the hydrolysis-condensation reaction is such that when the ratio (I (isoOH) / I (SiO)) is controlled within the above-mentioned range, water is equimolar to the silicon alkoxide. As described above, it is more preferable that the amount be 3 times mol or more and 5 times mol or less.

  The solvent (organic solvent, water), silicon alkoxide, and, if necessary, the catalyst, for example, may be mixed at the beginning (Aspect 1), after a part of the organic solvent, water and the catalyst are mixed in advance, Further, a mixed liquid of an organic solvent and silicon alkoxide may be added (particularly dropwise) (aspect 2), and the aspect 2 is particularly preferable. By slowly subjecting the silicon alkoxide to hydrolysis and condensation, silanol groups derived from excess adsorbed water in the silica particles obtained in the hydrolysis-condensation step are consumed, and the ratio in the infrared spectrum (I (adOH) / I Control of (SiO)) becomes easier.

  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 consume silanol groups derived from adsorbed water in silica particles, it is preferable to control the temperature of the hydrolytic condensation reaction to 35 ° C. or lower. By setting the reaction temperature to 35 ° C. or less, silanol groups derived from adsorbed water in the silica particles can be easily reduced, and the ratio (I (adOH) / I (SiO)) in the infrared spectrum can be easily controlled. 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 hydrolysis-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. Hydrolysis condensation is further promoted by such wet heat treatment, and the ratio (I (adOH) / I (SiO)) in the infrared spectrum of the silica particles obtained by subjecting the wet heat treatment to firing at a specific temperature described later. ) Can be controlled by 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 a wet heat treatment without drying, the reaction activity of the silica particles is higher, and the ratio (I (AdOH) / I (SiO)) is preferable because it becomes easier to control.

The dispersion subjected to the moist heat treatment (dispersion of silica particles are dispersed in a liquid medium), water that contained. 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). that has been. 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 constantly controlling the water concentration in the dispersion within the above range throughout the wet heat treatment, the ratio (I (adOH) / I (SiO)) of the obtained silica particles in the infrared spectrum is further controlled within the above range. It becomes easy to do.

  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-breaking of the siloxane bond is suppressed in the wet heat treatment.

  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, an external energy saving aspect of the heat source, as well as, or less coexisted was easily viewpoint et al 1 00 ° C. water and catalysts at normal pressure.
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)
It is preferable that the dried silica particles that have been powdered through the drying step are fired at a temperature of 900 ° C. or higher and 1150 ° C. or lower. By performing this baking together with the above-described wet heat treatment, the ratio (I (adOH) / I (SiO)) in the infrared spectrum can be controlled within the above range. When the firing temperature is less than 900 ° C., the amount of adsorbed water-derived silanol groups increases, so the value of the ratio (I (adOH) / I (SiO)) exceeds the upper limit of the range, and as a result. The hygroscopicity tends to increase and the durability of the resulting cured product tends to be low. On the other hand, when the firing temperature exceeds 1150 ° C., the amount of adsorbed water-derived silanol groups becomes too small, and the value of the ratio (I (adOH) / I (SiO)) falls below the range, and as a result. In addition, the dispersibility in the resin component tends to decrease. The firing temperature is more preferably 950 ° C. or higher, further preferably 1000 ° C. or higher, more preferably 1100 ° C. or lower, and still more preferably 1050 ° 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 at the time of firing is not particularly limited, but it is preferably performed in an oxidizing atmosphere, for example, in an air atmosphere.

  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 form a highly durable cured product and have excellent dispersibility with respect to the curable resin. It is possible to provide an underfill material that ensures fluidity enough to flow into a minute gap and has excellent 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 the dispersibility of the amorphous silica particles of the present invention, and the thickening suppression effect (fluidity) which is one of the effects when using the amorphous silica particles of the present invention. (Securing) is also preferable from the standpoint of exhibiting remarkably.

  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, it 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, phenol, cresols, ethylphenols, butylphenols, octylphenols, bisphenol A, brominated bisphenol A, bisphenol F, bisphenol S, naphthols; xylylene skeleton containing phenol novolac 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

(Infrared absorption spectrum)
Using a Fourier transform infrared spectrophotometer (“EXCALIBUR SERIES” manufactured by Varian Technologies Japan Limited), a range of 650 cm ^{−1 to} 4000 cm ⁻¹ was measured by the KBr method. In the infrared absorption spectrum obtained by the measurement, the maximum absorbance peak (peak of the OH bond of silanol group derived from adsorbed water) having a peak top at 3400～3500Cm ^-1 in broad peak appeared in 3200～3600Cm ^-1 ( I (adOH)), the maximum absorbance (I (isoOH)) of a sharp peak (isolated silanol group peak) appearing at 3750 cm ⁻¹ , and the maximum absorbance (I (SiO)) of a peak attributed to a siloxane bond And the following ratios were calculated.
Ratio of maximum absorbance of OH bond peak of silanol group derived from adsorbed water and maximum absorbance of siloxane bond peak: I (adOH) / I (SiO)
Ratio of maximum absorbance of OH bond peak of isolated silanol group and large absorbance of siloxane bond peak: I (isoOH) / I (SiO)

Example 1
A glass reactor having a capacity of 20 L equipped with a stirrer, a dropping device and a thermometer was charged with 770 parts by mass of methanol as a solvent and 268 parts by mass of 28% by mass ammonia water (water and catalyst), and the liquid was stirred. The temperature was adjusted to 20 ± 0.5 ° C. Meanwhile, a dropping device was charged with a solution in which 300 parts by mass of tetramethoxysilane (MS) as silicon alkoxide was dissolved in 128 parts by mass of methanol. And this solution was dripped over 2 hours from the dripping apparatus, and the hydrolysis condensation reaction of tetramethoxysilane was performed by continuing stirring for 1 hour after completion | finish of dripping.
The feed composition of the raw materials used in this reaction (concentrations of MS, water, and ammonia in a mixed solution composed of methanol, aqueous ammonia, water, and MS) is as shown in Table 1. Further, the water concentration in the dispersion obtained by the above reaction was as shown in Table 1 as the liquid composition before the wet heat treatment (the Si concentration and the ammonia concentration in the dispersion were almost the same as the charged composition). .
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).

  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 heat medium maintained at 150 ° C. while stirring at normal pressure. The liquid temperature was kept at 65 ° C. or higher (65 ° C. to 90 ° C.) for 5 hours or longer to perform wet heat treatment. At this time, a part of the solvent (methanol), ammonia, water and the like was distilled off to obtain a slurry having a liquid composition as shown in Table 1 as a liquid composition after the wet heat treatment.

  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.

  Next, the obtained dried silica particles are put in a crucible, heated at room temperature in an air atmosphere using an electric furnace, fired at the firing temperature shown in Table 1 for 1 hour, then cooled and ground, Amorphous silica particles (1) were obtained. Table 2 shows the average particle size, the coefficient of variation of the particle size, and the results of infrared absorption spectrum of the obtained amorphous silica particles.

(Examples 2-4 and Comparative Examples 1-2)
Table 1 shows the raw material charge composition in the hydrolytic condensation reaction, the dispersion composition before and after the wet heat treatment (water concentration before treatment, silica (Si equivalent) concentration, water concentration, ammonia concentration after treatment), and firing temperature. The same process (hydrolytic condensation reaction, wet heat treatment, drying, firing) as in Example 1 except that the amount of raw materials used and the time of each treatment (reaction time, heating time, etc.) were changed to be as follows. , Cooling, and pulverization) to obtain amorphous silica particles (2) to (4) and (C1) to (C2). The average particle diameter of each of the obtained amorphous silica particles, the coefficient of variation of the particle diameter, and the measurement results of the infrared absorption spectrum are as shown in Table 2.
Note that the Si concentration and the ammonia concentration in the dispersion before the wet heat treatment are substantially the same as the charged composition.

The following evaluation was performed about the amorphous silica particle obtained by the above Example and the comparative example.
<Fluidity>
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.)” 700G "; 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 curing accelerator as a curing accelerator Was prepared. 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.

  Immediately after the preparation, the curable resin composition can be poured into a casting mold composed of two release-treated glass plates having a length of 50 mm and a width of 10 mm and a 100 μm spacer, and can be poured up to how many mm in the length direction. I confirmed. And, it is evaluated as “◯” when completely injectable up to 50 mm, “△” when injectable within a range of less than 50 mm and 30 mm or more, and “X” when injectable within 30 mm or not at all. did.

<Durability>
First, a curable resin composition was prepared in the same manner as the evaluation of fluidity, and immediately, a casting mold composed of two release-treated glass plates having a length of 200 mm and a width of 50 mm and a 4 mm spacer was prepared. After injecting, heating at 180 ° C. for 6 hours in a heating furnace, cooling and taking out from the mold, a sheet-like cured product having a thickness of 4 mm was produced. Two rectangular test samples having a length of 80 mm and a width of 10 mm (4 mm thickness) were cut out from the obtained cured product, and one of the obtained test samples had a temperature of 120 ° C. and a gas phase pressure of 2 atm ( It was put into a pressure heating furnace set at 202.65 kPa) and held for 500 hours to perform heating and pressure treatment.
Next, an electromechanical universal testing machine (manufactured by INSTRON Co., Ltd.) according to JIS K6911 for a test sample (sample A) not subjected to heat and pressure treatment and a test sample (sample B) subjected to heat and pressure treatment ) To measure the bending strength of the sample (B) to the sample (A) (bending strength of the sample (B) / bending strength of the sample (A)). The case where the bending strength ratio was 0.9 or more was evaluated as “◎”, the case where it was 0.8 or more and less than 0.9 was evaluated as “◯”, and the case where it was less than 0.8 was evaluated as “x”.

Claims (7)

Amorphous silica particles used for a semiconductor sealing material,
In the Fourier transform infrared absorption spectrum (FT-IR), the maximum absorbance (I (adOH)) of the OH bond peak of the silanol group having a peak top at 3400-3500 cm ⁻¹ and the maximum absorbance (I (SiO )) And a ratio (I (adOH) / I (SiO)) of 0.0010 or more and less than 0.0025.   The amorphous silica particles according to claim 1, wherein the average particle diameter is 0.45 µm or less.   The amorphous silica particles according to claim 1 or 2, wherein the coefficient of variation in particle diameter is less than 15%. In the Fourier transform infrared absorption spectrum (FT-IR), the maximum absorbance (I (isoOH)) of the OH bond peak of the silanol group having a peak top near 3750 cm ⁻¹ and the maximum absorbance (I (SiO) of the siloxane bond peak) The amorphous silica particles according to any one of claims 1 to 3, wherein the ratio (I (isoOH) / I (SiO)) to 0.00010 is less than 0.002.   The amorphous silica particles according to any one of claims 1 to 4, which are surface-treated with a silane coupling agent.   A semiconductor sealing material comprising the amorphous silica particles according to claim 1, an epoxy resin, and a curing agent.   The semiconductor sealing material according to claim 6, wherein the curing agent is an acid anhydride curing agent.