JP5480497B2 - Method for producing surface-encapsulated silica-based particles, surface-encapsulated silica-based particles, and a resin composition for semiconductor encapsulation obtained by mixing the particles - Google Patents

Description

The present invention relates to a method for producing surface-sealed silica-based particles having excellent moisture resistance, which are obtained by sealing pores present on the surface of silica-based porous particles, and to the surface-sealed silica-based particles obtained from the method. . Furthermore, it is related with the resin composition for semiconductor sealing formed by mixing this surface sealing silica type particle | grain into a thermosetting resin as a filler.

A number of methods for producing silica-based porous particles and methods for coating the surface of inorganic oxide particles with a silica-based coating have been proposed to date. For example, Patent Document 1 discloses a method for producing inorganic oxide particles (eg, spherical silica powder) having an average particle size of 1 to 20 μm by spray drying a colloidal liquid containing primary particles having an average particle size of 2500 mm or less. It is disclosed.
Patent Document 2 discloses an outer surface of an aggregate of inorganic oxide fine particles having an average particle diameter of 1 to 100 μm obtained by spray drying a colloidal liquid containing inorganic oxide fine particles having an average particle diameter of 2 to 250 nm. A spherical porous particle is disclosed that is coated with a silica-based layer made of a hydrolyzate of an organosilicon compound represented by the chemical formula R _n Si (OR ′) _4-n .

Further, in Patent Document 3, a surface of the inorganic particles is formed by adding a silicate solution and an acid to an aqueous suspension of inorganic particles, and further exposing the mixed suspension to the influence of ultrasonic vibration. A method of coating with amorphous silica is disclosed.
However, although these patent documents disclose a method of coating the surface of inorganic oxide particles with a silica-based material, a method for sealing pores existing on the surface of silica-based porous particles is described in more detail. Does not describe any method for sealing only the pores existing on the surface of the particles while leaving the pores existing inside the silica-based porous particles as they are.

In addition, many proposals have been made for a resin composition for a semiconductor sealing material in which inorganic oxide fine particles are mixed as a filler. For example, Patent Document 4 discloses a resin composition for a semiconductor encapsulant in which a spherical silica particle aggregate composed of a fired product of polyorganosiloxane particles obtained by hydrolysis and condensation of an organosilicon compound is mixed. However, there is no description about using silica-based porous particles as a filler.
Furthermore, Patent Document 5 discloses a resin composition for a semiconductor sealing material in which porous silica obtained by a sol-gel method is mixed with an epoxy resin. However, since this porous silica is used for the purpose of trapping moisture entering from the outside, the pores existing on the particle surface are not sealed.

JP-A 61-270201 JP 2002-160907 A JP-A-6-192593 JP 2002-37620 A Japanese Patent Laid-Open No. 2001-220696

  In general, it is known that when silica-based porous particles are left in an atmosphere containing moisture such as air, moisture is adsorbed in the particles. Therefore, in order to improve the moisture resistance of the silica-based porous particles, a method of coating the particle surface with a silica-based material has been proposed. However, depending on the raw material used for the surface coating, it is intended to directly coat the surface of the silica-based porous particles using a conventionally known liquid silicon compound such as silicic acid, silicate, or organosilicon compound. These substances may soak into the inside of the particles and harden, and as a result, the pores existing inside the silica-based porous particles may be blocked. As a result, the porous characteristics of the silica-based porous particles may be lost.

Therefore, the present inventors have repeated intensive studies, and found that a mixed liquid obtained by adding an aqueous dispersion sol containing nano-sized silica fine particles to a suspension containing the silica-based porous particles was added to ammonia or ammonium hydroxide. Heat treatment at a temperature of 50 to 90 ° C. in the presence of an alkali compound such as to attach the silica fine particles and / or a dissolved product thereof at least inside the pores existing on the surface of the silica-based porous particles. After that, if the mixed solution is heat-treated at a temperature of 90 to 350 ° C., pores existing on the surface of the silica-based porous particles are sealed with at least the silica fine particles and / or a solution thereof. As a result, the present invention has been completed.

The method for producing surface-sealed silica-based particles according to the present invention is a method for producing surface-sealed silica-based particles having moisture resistance,
(1) A step of producing a silica-based porous particle having an average particle size of 0.5 to 50 μm by spray-drying a dispersion containing silica-based fine particles having an average particle size of 2 to 300 nm through a spray dryer;
(2) The silica-based porous particles obtained in the step (1) are suspended in pure water or ultrapure water, and then mixed with an aqueous dispersion sol containing silica fine particles having an average particle diameter of 2 to 50 nm. Process,
(3) The pores present on at least the surface of the silica-based porous particles by heat-treating the mixed solution obtained in the step (2) in the presence of an alkali compound at a temperature of 50 to 90 ° C. Attaching the silica fine particles and / or a dissolved product thereof to the inside of
(4) The mixed solution containing the silica-based porous particles obtained in the step (3) is heat-treated at a temperature of 90 to 350 ° C. to obtain fine particles present on the surface of the silica-based porous particles. A step of generating silica-based particles having pores sealed with at least the silica fine particles and / or a solution thereof; and (5) after separating and washing the surface-sealed silica-based particles obtained in the step (4). And a drying step.

In the step (1), it is preferable that the dispersion further contains silicic acid.
Moreover, in the said process (1), it is preferable that content of the solid content contained in the said dispersion liquid exists in the range of 1 to 50 weight%.
Furthermore, the porosity of the silica-based porous particles obtained from the step (1) is preferably in the range of 5 to 90%.
Moreover, it is preferable that the average pore diameter of the pore which exists on the surface of the silica type porous particle obtained from the said process (1) exists in the range of 2-25 nm.

In the step (2), the water-dispersed sol of silica fine particles preferably contains silica fine particles smaller than the average pore diameter of pores existing on the surface of the silica-based porous particles.
In the step (2), when the silica fine particle water-dispersed sol represents the weight of the silica fine particles as X and the weight of the silica-based porous particles as Y, the weight ratio (X / Y ) Is preferably mixed in the silica-based porous particle suspension at a ratio of 0.1 / 99.9 to 50/50.
In the step (3), the alkali compound is preferably ammonia or ammonium hydroxide.

It is preferable to include a step of further adding silicic acid to the mixed solution obtained from the step (3).
Further, in the adding step, the silicate represents the weight of the silica fine particles A, when expressed weight該珪acid (SiO ₂ equivalent value) in B, the weight ratio (B / A) 0.1 /99.9 to 30/70 are preferably added at such a ratio.

It is preferable to further include a step of adding an organosilicon compound represented by the following general formula (I) or a hydrolyzate thereof to the mixed liquid obtained from the step (3).
X _n Si (OR) _4-n (I)
(In the formula, X represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 3 carbon atoms, R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 0 to 3). .)
In the addition step, the organosilicon compound or a hydrolyzate thereof is represented by C as the weight of the silica fine particles, and the weight of the organosilicon compound or a hydrolyzate thereof as SiO ₂ is expressed as D. At this time, it is preferable to add at a ratio such that the weight ratio (D / C) is 0.1 / 99.9 to 30/70.

In the step (3), the heat treatment is preferably performed for 10 to 120 minutes.
Moreover, in the said process (4), it is preferable to perform the said heat processing over 5 to 20 hours.
Furthermore, it is preferable that the surface-sealed silica-based particles obtained from the step (5) are further fired at a temperature of 120 to 1000 ° C.

The surface-sealed silica-based particles according to the present invention are formed on the surface of silica-based porous particles having an average particle size of 0.5 to 50 μm obtained by spray drying a dispersion containing silica-based fine particles having an average particle size of 2 to 300 nm. The existing fine pores are silica fine particles having an average particle diameter of 2 to 50 nm and / or a dissolved product thereof, or dehydration / condensation polymer of the silica fine particles and / or a dissolved product thereof and silicic acid, or the silica fine particles and / or a dissolved product thereof. And a hydrolyzed / condensed polymer of an organosilicon compound represented by the following general formula (I).
X _n Si (OR) _4-n (I)
(In the formula, X represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 3 carbon atoms, R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 0 to 3). .)

The density of the surface-sealed silica-based particles is preferably in the range of 0.4 to 2.2 g / ml.
Furthermore, the specific surface area of the surface-sealed silica-based particles is preferably in the range of 5 to 400 m ² / g, and the pore volume is preferably in the range of 0.01 to 2.0 ml / g.
The compressive strength of the surface-sealed silica-based particles is preferably in the range of 0.1 to 300 kgf / cm ² .
Furthermore, the surface-sealed silica-based particles preferably have a moisture absorption rate of 1% or less when the particles are left in an air atmosphere at a temperature of 25 ° C. and a humidity of 90% for 7 days.

The resin composition for semiconductor encapsulation according to the present invention is characterized in that the above-mentioned surface-encapsulated silica-based particles are mixed with a thermosetting resin as a filler.
The thermosetting resin is preferably a curable epoxy resin having at least two epoxy groups in one molecule.
Further, the surface-sealed silica-based particles have a weight ratio (E / F) of 10 / when the weight of the surface-sealed silica-based particles is represented by E and the weight of the thermosetting resin is represented by F. It is preferable to mix at a ratio of 100 to 95/100.

  According to the production method of the present invention, it is possible to easily seal only the pores existing on the surface without blocking the pores existing inside the silica-based porous particles. The mechanism is not fully verified, but is considered to be as follows. The “pores existing on the surface of the silica-based porous particles” as used in the present invention means that a part or most of the pores are open toward the surface. It also includes pores having similar openings that appear when part of the surface of the silica-based porous particles is dissolved.

(1) Silica-based porous particles (secondary particles) obtained by spray-drying a dispersion containing silica-based fine particles (primary particles) having an average particle diameter of 2 to 300 nm on a spray dryer are aggregates of the primary particles. It is known that voids (so-called grain boundary voids) generated at the grain boundaries between the primary particles become pores, and these pores give the secondary particles porous properties. That is, since the pores are formed from continuous grain boundary voids, there are cases where the voids communicate from the particle surface to the inside of the particles. Therefore, conventionally known liquid silicon compounds such as silicic acid, silicates, and organosilicon compounds may penetrate from the pores present on the surface of the silica-based porous particles to the inside of the particles.

(2) However, in the present invention, silica fine particles having a nano-sized particle diameter are used as the surface sealing material for the silica-based porous particles, so that the silica fine particles are contained in the silica-based porous particles. Never invade.
(3) Further, based on the method of the present invention, the mixed liquid containing the silica fine particles and the silica-based porous particles is heated at a temperature of 50 to 90 ° C. in the presence of an alkali compound such as ammonia or ammonium hydroxide. When the treatment is performed, at least a part (particularly, the surface) of the silica fine particles dissolves and adheres to the inside of the pores existing on the surface of the silica-based porous particle, and the pores (particularly, the inside of the particle) It will be in the form of closing the entrance.

(4) Furthermore, when the mixed solution is heat-treated at a temperature of 90 to 350 ° C., the inside of the pores existing on the surface of the silica-based porous particle is blocked with the silica fine particles and / or the dissolved product thereof. The pores can be sealed. In this stage, a conventionally known liquid silicon compound such as silicic acid or an organosilicon compound can be further added to the mixed solution for the purpose of densely sealing the pores on the particle surface. This is because even when the liquid silicon compound is added, they hardly penetrate into the silica-based porous particles.

As a result, surface-sealed silica-based particles having excellent moisture resistance can be obtained by sealing only the pores existing on the surface of the silica-based porous particles without blocking the pores existing inside the silica-based porous particles. Can do.
Further, the surface-sealed silica-based particles obtained in this way are not only useful as a filler for a resin composition for semiconductor encapsulation, but are also suitably used for the inside of a printed wiring board substrate, a die attach film, and the like. can do.

  Hereinafter, the production method of the surface-sealed silica-based particles according to the present invention and the surface-sealed silica-based particles obtained from the method will be specifically described.

[Method for producing surface-encapsulated silica-based particles]
The method for producing surface-sealed silica-based particles according to the present invention is a method for producing surface-sealed silica-based particles having moisture resistance,
(1) A step of producing a silica-based porous particle having an average particle size of 0.5 to 50 μm by spray-drying a dispersion containing silica-based fine particles having an average particle size of 2 to 300 nm through a spray dryer;
(2) The silica-based porous particles obtained in the step (1) are suspended in pure water or ultrapure water, and then mixed with an aqueous dispersion sol containing silica fine particles having an average particle diameter of 2 to 50 nm. Process,
(3) The pores present on at least the surface of the silica-based porous particles by heat-treating the mixed solution obtained in the step (2) in the presence of an alkali compound at a temperature of 50 to 90 ° C. Attaching the silica fine particles and / or a dissolved product thereof to the inside of
(4) The mixed solution containing the silica-based porous particles obtained in the step (3) is heat-treated at a temperature of 90 to 350 ° C. to obtain fine particles present on the surface of the silica-based porous particles. A step of generating silica-based particles having pores sealed with at least the silica fine particles and / or a solution thereof; and (5) after separating and washing the surface-sealed silica-based particles obtained in the step (4). And a step of drying.
Next, this manufacturing method will be described for each step as follows.

Process (1 )
In this step, a dispersion containing silica-based fine particles (hereinafter sometimes referred to as “silica-based fine particle dispersion”) is spray-dried using a spray dryer, whereby silica having a particle size of 0.5 to 50 μm. A dry powder of system porous particles is prepared.
As the silica-based fine particle dispersion, a commercially available product produced by a conventionally known method can be used. However, in the present invention, it is desirable to use silica sol obtained by dispersing spherical silica-based fine particles or non-spherical silica-based fine particles having an average particle diameter of 2 to 300 nm, preferably 5 to 100 nm, in water.

In the method of the present invention, even if silica particles having an average particle diameter of less than 2 nm are included, they can be used satisfactorily. However, in the measurement method described below, an average particle diameter of less than 2 nm is measured. In this case, the lower limit value of the average particle diameter is defined as 2 nm. Moreover, when the said average particle diameter exceeds 300 nm, since the particle | grain intensity | strength of the silica type particle | grains obtained will fall by reducing the binder force of particle | grains, it is not preferable.
As such a silica-based fine particle dispersion, for example, a silica sol containing silica-based fine particles having an average particle size of about 8 nm (Cataloid SI-350, manufactured by JGC Catalysts & Chemicals Co., Ltd.), a silica-based material having an average particle size of about 15 nm. Examples thereof include a silica sol containing fine particles (Cataloid S-20L, manufactured by JGC Catalysts & Chemicals Co., Ltd.), a dispersion containing fumed silica having an average particle size of about 12 nm (AEROSIL 200 manufactured by Nippon Aerosil Co., Ltd.), and the like. The dispersion is preferably an aqueous dispersion, but in some cases may contain alcohols such as ethanol, propanol, and butanol.

Further, in the present invention, silicic acid can be further contained in the silica-based fine particle dispersion, although it varies depending on the intended use.
As the silicic acid, it is possible to use an alkali metal silicate, an organic base silicate or the like treated with a cation exchange resin and dealkalized (removal of Na ions, etc.). Examples of the silicate include alkali metal silicates such as sodium silicate (water glass) and potassium silicate, and silicates of organic bases such as quaternary ammonium silicate.

Among these, silicic acid having a pH of 2 to 6, preferably 2 to 3, and a silicon component content of 0.5 to 10% by weight, preferably 3 to 4% by weight, based on SiO ₂ It is desirable to use an aqueous solution (hereinafter sometimes referred to as “silicic acid aqueous solution”). Here, when the pH is less than 2, the treatment time required for cation exchange is unnecessarily long, and it is not economical, and when the pH exceeds 6, the degree of dealkalization is low, and thus obtained. Since the stability of silicic acid deteriorates, it is not preferable. Furthermore, when the content is less than 0.5% by weight, it is difficult to economically obtain the silica-based porous particles, and when the content exceeds 10% by weight, the stability of silicic acid is poor. This is not preferable. As the silicic acid aqueous solution having such properties, it is preferable to use a solution obtained by diluting water glass (sodium silicate) with water and then treating it with a cation exchange resin to dealkalize.

As described above, in the present invention, a mixed aqueous solution obtained by mixing the silica-based fine particle dispersion with the silicic acid aqueous solution can be used, but the silica-based porous material having many pores (or voids). In order to prepare particles, it is preferable to use only the silica-based fine particle dispersion or a solution obtained by adding a small amount of the aqueous silicic acid solution thereto. However, since the silicic acid aqueous solution also functions as a binder component between the particles of the silica-based fine particles, when it is necessary to produce silica-based porous particles having excellent compressive strength, the silicic acid aqueous solution is used as the silica-based fine particle. It is preferable to use a mixture of a relatively large amount of the fine particle dispersion.
However, when the amount of the silicic acid aqueous solution is increased, the porous characteristics of the resulting silica-based porous particles are reduced. Therefore, the amount of the mixture represents the weight of the silicic acid (SiO ₂ conversion standard) as G, When the weight of the silica-based fine particles is represented by H, the weight ratio (G / H) is 50/50 or less, preferably 0.1 / 99.9 to 30/70.

In addition, the spray drying in this step can be performed by a conventionally known method using a commercially available spray dryer (disc rotation type, nozzle type, etc.).
That is, the spray drying is performed by using the silica-based fine particle dispersion or a silica component-containing dispersion (hereinafter, simply referred to as “dispersion”) composed of a mixed aqueous solution of the silica-based fine particle dispersion and a silicic acid aqueous solution. For example, it is performed by spraying in a hot air stream at a rate of 1 to 3 liters / minute. At this time, the temperature of the hot air is preferably such that the inlet temperature is in the range of 70 to 400 ° C, preferably 100 to 300 ° C, and the outlet temperature is in the range of 40 to 60 ° C. Here, if the inlet temperature is less than 70 ° C., drying of solids contained in the dispersion becomes insufficient, and if it exceeds 400 ° C., the shape of the particles is distorted at the time of spray drying. Absent. Further, if the outlet temperature is less than 40 ° C., the degree of drying of the solid content is poor and adheres to the inside of the apparatus.

The dispersion is a solid content in the dispersion (when only the silica-based fine particle dispersion is used, it means the content of the silica-based fine particles, and the mixed aqueous solution is used. In this case, the total content of the silica-based fine particles and the silicic acid (however, the SiO ₂ conversion standard) is 1 to 50% by weight, preferably 5 to 30% by weight. It is preferable to use a spray dryer for spray drying. Here, when the solid content is less than 1% by weight, it is not economical, and when the solid content exceeds 50% by weight, the slurry viscosity increases and the shape of the spray-dried product is distorted. This is not preferable.
When the dispersion containing the silicic acid aqueous solution is spray dried using a spray dryer, the silicon compound contained in the silicic acid aqueous solution is dehydrated and polycondensed to become a silica component. Therefore, in the obtained silica type porous particle, it exists as a dehydration / condensation polymer of the silicon compound contained in the silicic acid aqueous solution.

The silica-based porous particles thus obtained have a shape that is generally spherical or nearly spherical. Moreover, although the average particle diameter changes also with the spray-drying conditions of the said dispersion liquid, etc., it is 0.5-50 micrometers, Preferably it is desirable to exist in the range of 1-20 micrometers.
Further, the porosity of the silica-based porous particles varies depending on the mixing ratio of the silicic acid aqueous solution, but is preferably in the range of 5 to 90%, preferably 10 to 80%.
Furthermore, the average pore diameter of the pores present on the surface of the silica-based porous particles varies depending on the average particle diameter of the silica-based fine particles and the amount of the silicic acid aqueous solution mixed, but is 2 to 25 nm, preferably 9 to A range of 17 nm is desirable.

Process (2 )
In this step, the silica-based porous particles obtained in the step (1) are suspended in pure water or ultrapure water, and then mixed with an aqueous dispersion sol containing silica fine particles having an average particle diameter of 2 to 50 nm. To do.
Here, pure water refers to ion-exchanged water, and ultrapure water refers to water in which impurities contained in pure water are further removed, and the impurity content is 0.01 μg / L or less.
Further, the silica-based porous particles suspended in the pure water or ultrapure water are not particularly limited, but it is preferable to mix so as to contain 5 to 50% by weight in the suspension. .

The silica fine particles may include silica-based fine particles having an average particle diameter of less than 2 nm, as in the case of the silica-based fine particles, but in the measurement method described below, Since it is difficult to measure an average particle diameter of less than 2 nm, the lower limit value of the average particle diameter is defined as 2 nm here. Further, if the average particle diameter exceeds 50 nm, even if the surface of the silica fine particles is dissolved in the step (3) described below, it is larger than the average pore diameter of the pores existing on the surface of the silica-based porous particles. This is not preferable because it is difficult to attach the silica fine particles and / or a solution thereof in the pores.
In this connection, the water-dispersed sol containing the silica-based fine particles preferably contains silica fine particles smaller than the average pore diameter of the pores existing on the surface of the silica-based porous particles.

Further, the water-dispersed sol of silica fine particles has a weight ratio (X / Y) of 0.1 / 99 when the weight of the silica fine particles is represented by X and the weight of the silica-based porous particles is represented by Y. It is preferable to mix in the suspension of the silica-based porous particles at a ratio of 9 to 50/50, preferably 5/95 to 30/70. Here, when the weight ratio is less than 0.1 / 99.9, it is difficult to sufficiently seal pores existing on the surface of the silica-based porous particles. Further, when the weight ratio exceeds 50/50, the silica fine particles present in the mixed solution and the dissolved product thereof (more specifically in the step (4)) when subjected to the subsequent step (4). After the heating is finished, the precipitate of the dissolved product, which is generated as the temperature of the mixed solution decreases, may become a nucleus and cause growth of new particles, which is not preferable. The latter phenomenon is likely to occur when silicic acid or an organosilicon compound is added to the mixed solution.

Process (3 )
In this step, the mixed liquid obtained in the step (2) is heat-treated in the presence of an alkali compound at a temperature of 50 to 90 ° C., preferably 60 to 80 ° C., so that at least the silica-based porous material is treated. The silica fine particles (including those in which the particle surface is dissolved) and / or a dissolved product thereof are adhered to the inside of the pores present on the particle surface.
Here, the alkali compound is not particularly limited, but it is preferable to use ammonia or ammonium hydroxide. The alkali compound is added to the mixed solution in this step, but may be added in advance in the step (2).
Moreover, it is preferable to add the said alkali compound so that pH of the said liquid mixture may become 9-12, Preferably it is the range of 10-11.5. Here, when the pH is less than 9, since the surface of the silica fine particles is hardly dissolved in a short time, it is difficult to sufficiently seal the pores present on the surface of the silica-based porous particles, Further, when the pH exceeds 12, not only all of the silica fine particles may be dissolved, but also the dissolution of the silica-based porous particles may cause the particles to collapse, It is not preferable.

When the mixed solution to which the alkali compound has been added is heated under a temperature condition of 50 to 90 ° C. with stirring, the silica fine particles are dissolved from the surface thereof and are fine particles present at least on the surface of the silica-based porous particles. It adheres to the inside of the hole.
Here, when the temperature is less than 50 ° C., the surface of the silica fine particles is hardly dissolved, so that it is difficult to sufficiently seal the pores existing on the surface of the silica-based porous particles. When the temperature exceeds 90 ° C., although it varies depending on the pH of the mixed solution, many of the silica fine particles may be dissolved, and water contained in the mixed solution starts to evaporate. It is not preferable.
This heat treatment operation can be performed in a non-pressure vessel such as glass or stainless steel, but in the step (4) described below, it is necessary to perform the heat treatment operation in a pressure vessel such as an autoclave. Alternatively, it may be performed in such a pressure vessel in advance.

The heat treatment is preferably performed for 10 to 120 minutes, preferably 30 to 60 minutes. Here, if the treatment time is less than 10 minutes, it may be difficult to sufficiently adhere the silica fine particles and / or a dissolved product thereof in the pores present on the surface of the silica-based porous particles, In addition, when the treatment time exceeds 120 minutes, although it depends on the pH of the mixed solution, dissolution of the porous silica particles may proceed, which is not preferable.
In this step, a part of the surface of the silica-based porous particles starts to dissolve, but in the case of the silica-based porous particles, the particle diameter is relatively large and the treatment time is also relatively short. In addition, there is a possibility that the silica fine particles are helped to adhere to the pores existing on the surface of the particles.

Process (4 )
In this step, the mixed solution containing the silica-based porous particles obtained in the step (3) is heat-treated at a temperature of 90 to 350 ° C., preferably 150 to 250 ° C. Silica-based particles in which pores present on the surface of the porous particles are sealed with at least the silica fine particles (including those in which the particle surface is dissolved) and / or a dissolved product thereof are generated.
Here, when the temperature is less than 90 ° C., pores present on the surface of the silica-based porous particles may not be sufficiently sealed, and when the temperature exceeds 350 ° C., The dissolution of the silica-based porous particles proceeds, and the dissolved product (and the dissolved silica particles) is deposited on the particles after the heating and becomes non-porous particles or non-spherical particles. This is not preferable.
This heat treatment operation needs to be performed by putting the mixed solution in a pressure vessel such as an autoclave because it is necessary to heat the mixed solution to a temperature of 90 to 350 ° C.

The heat treatment is preferably performed for 5 to 20 hours, preferably 10 to 16 hours. Here, when the treatment time is less than 5 hours, pores present on the surface of the silica-based porous particles may not be sufficiently sealed, and when the treatment time exceeds 20 hours. The dissolution of the silica-based porous particles proceeds, and the dissolved product (and the dissolved silica fine particles) is deposited on the particles after the heating and becomes non-porous particles or non-spherical particles. This is not preferable.
In this step, the silica fine particles contained in the mixed solution are dissolved, and the dissolved matter enters at least the inside of the pores existing on the surface of the silica-based porous particles, and is thus present on the surface of the particles. The pores to be sealed can be sealed.

Further, here, for the purpose of densely sealing the pores on the particle surface, after previously adding a liquid silicon compound such as silicic acid or an organosilicon compound into the mixed liquid obtained in the step (3), It can use for this process (4).
In addition, the liquid silicon compound added here does not penetrate into the pores present inside the silica-based porous particles for the reason described above.
Hereinafter, the addition of the liquid silicon compound will be described more specifically.

Addition of silicic acid The above-mentioned silicic acid can be used, and among these, the pH is in the range of 2-6, preferably 2-3, and the content of silicon component is SiO ₂ conversion standard. It is desirable to use an aqueous silicic acid solution in the range of 0.1 to 10% by weight, preferably 3 to 5% by weight.
The silicic acid has a weight ratio (B / A) of 0.1 / 99.9 to 0.1 when the weight of the silica fine particles is represented by A and the weight of the silicic acid (SiO ₂ conversion standard) is represented by B. It is preferable to mix at a ratio of 30/70, preferably 1/99 to 25/75. Here, the silicic acid is used for the purpose of densely sealing the pores present on the surface of the silica-based porous particles, and the weight ratio is less than 0.1 / 99.9, When the pores are difficult to seal densely and the weight ratio exceeds 30/70, dehydration / condensation polymer of silicic acid precipitates on the silica-based porous particles, and the characteristics of the particles May be changed, or the dehydration / condensation product may become a nucleus and cause the growth of new particles.

Thus, when the mixed solution to which the silicic acid is added is subjected to this step, dissolution of the silica fine particles and dehydration / condensation of the silicic acid occur, and the product is present on the surface of the porous silica. The inside of the hole can be fixed and sealed. Thereby, silica-based porous particles in which the pores on the particle surface are densely sealed are obtained.
The product is considered to partially adhere to the surface of the silica-based porous particles, but as far as seen from a cross-sectional photograph (TEM photograph) taken with a transmission electron microscope, The coating layer formed on the surface of the porous particles could not be confirmed. The result is shown in FIG.

Addition of organosilicon compound As the organosilicon compound, an organosilicon compound represented by the following general formula (I) or a hydrolyzate thereof is preferably used.
X _n Si (OR) _4-n (I)
(In the formula, X represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 3 carbon atoms, R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 0 to 3). .)

  More specifically, the organosilicon compound includes tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltrimethoxysilane. Ethoxysilane, ethyltriisopropoxysilane, octyltrimethoxysilane, octyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, trimethoxysilane, triethoxysilane, triisopropoxy Silane, fluorotrimethoxysilane, fluorotriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyl Ethoxysilane, dimethoxysilane, diethoxy silane, difluoromethyl dimethoxysilane, difluoro diethoxy silane, trifluoromethyl trimethoxy silane, trifluoromethyl triethoxy silane. Among these, it is preferable to use tetramethoxysilane, tetraethoxysilane, or a mixture thereof.

The organosilicon compound or a hydrolyzate thereof has a weight ratio when the weight of the silica fine particles is represented by C, and the weight of the organosilicon compound or the hydrolyzate thereof (SiO ₂ conversion standard) is represented by D. It is preferable to mix in such a ratio that (D / C) is 0.1 / 99.9 to 30/70, preferably 1/99 to 25/75. Here, the organosilicon compound is used for the purpose of densely sealing pores existing on the surface of the silica-based porous particles, as in the case of the above-described silicic acid, but the weight ratio is When the ratio is less than 0.1 / 99.9, it is difficult to densely seal the pores, and when the weight ratio exceeds 30/70, the hydrolyzate of the organosilicon compound is the silica-based one. This is not preferable because it may precipitate on the porous particles and change the properties of the particles, or the hydrolyzate may become a nucleus and cause growth of new particles.

Thus, when the mixed liquid to which the organosilicon compound or a hydrolyzate thereof is added is subjected to this step, dissolution of the silica fine particles and hydrolysis / condensation polymerization of the organosilicon compound occur, and the product is obtained. The fine pores existing on the surface of the silica-based porous material can be fixed inside the fine pores, thereby sealing the fine pores. Thereby, silica-based porous particles in which the pores on the particle surface are densely sealed are obtained.
In addition, although the catalyst for accelerating this hydrolysis reaction is required for the hydrolysis of the organosilicon compound, the alkaline compound such as ammonia or ammonium hydroxide added in the step (3) plays a role. Therefore, it is not necessary to add a new catalyst from outside the system.

Process (5)
In this step, the surface-sealed silica-based particles obtained in the step (4) are separated and washed and then dried.
Separation of the surface-encapsulated silica-based particles is performed using a commercially available apparatus such as a buhuner funnel, filter press, horizontal belt filter, synchro filter, precoat filter, drum filter, belt filter, tray filter, and centrifuge. Can do. As the separation method, a conventionally known method can be adopted.
The cake-like substance of the surface-sealed silica-based particles obtained in this way is preferably sufficiently washed with pure water such as ion exchange water or distilled water.

Next, the cake-like substance is preferably dried at room temperature to 200 ° C., preferably 50 to 150 ° C. for 1 to 24 hours, preferably 2 to 12 hours at normal pressure or reduced pressure. Here, if the drying temperature is less than room temperature, the cake-like substance cannot be sufficiently dried, and a sufficient drying effect can be obtained even when the drying temperature is 200 ° C. or less. In order to obtain the body, it is not necessary to exceed this temperature from an economic point of view. Further, if the drying time is less than 1 hour, the cake-like substance may not be sufficiently dried, and even if the drying time is 24 hours or less, it can be sufficiently dried. In order to obtain a dry powder, it is not necessary to exceed this time from an economic point of view.
The dry powder (particle group) of the surface-sealed silica-based particles obtained in this way is subjected to a pulverization apparatus such as a juicer mixer or a yary pulverizer as necessary to disintegrate agglomerates or lumps in advance. It is desirable to break up.

Firing step In this step, the dry powder of the surface-sealed silica-based particles obtained in the step (5) is fired as necessary.
Usually, the dry powder of the surface-sealed silica-based particles has a compressive strength in the range of 0.1 to 100 kgf / mm ² . Therefore, when using the surface-sealed silica-based particles for applications requiring high compressive strength, the dry powder of the surface-sealed silica-based particles needs to be fired. That is, it is desired that the dried powder of the surface-sealed silica-based particles obtained in the step (5) is baked at a temperature of 100 to 1000 ° C., preferably 120 to 800 ° C. for 1 to 24 hours. Here, when the firing temperature is less than 100 ° C., the siloxane bond between the primary particles constituting the surface-sealing silica-based particles is not sufficient, and thus improvement in compressive strength cannot be expected, and the firing temperature exceeds 1000 ° C. Then, the pores in the particles disappear due to the sintering of the particles, the desired porous properties cannot be maintained, and crystalline silica (quartz or the like) may be generated, which is not preferable.

In addition, when the firing time is less than 1 hour, the siloxane bond between the primary particles constituting the surface-sealing silica-based particles is not sufficient, so improvement in compressive strength cannot be expected, and the firing time exceeds 24 hours. However, it cannot be said that it is economical because a special effect cannot be obtained.
In this way, when the dried powder of the surface-sealed silica-based particles is subjected to a firing treatment, surface-sealed silica-based particles having a compressive strength in the range of 0.5 to 300 kgf / mm ² are obtained.
Therefore, according to the use, it can select and use suitably from the dry powder and baked powder of said surface sealing silica type particle | grains.

[Surface-sealed silica-based particles]
The surface-sealed silica-based particles according to the present invention are:
The pores present on the surface of silica-based porous particles having an average particle size of 0.5 to 50 μm obtained by spray-drying a dispersion containing silica-based fine particles having an average particle size of 2 to 300 nm are average particles having a diameter of 2 to 50 nm. Silica fine particles (including those in which the particle surface is dissolved, and the same shall apply hereinafter) and / or a dissolved product thereof, or the silica fine particles and / or a dehydrated / condensed polymer of silicic acid, or the silica fine particles and / or The solution is sealed with a hydrolyzed / condensed polymer of an organosilicon compound represented by the following general formula (I).
X _n Si (OR) _4-n (I)
(In the formula, X represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 3 carbon atoms, R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 0 to 3). .)

  As described above, the porosity of the silica-based porous particles is in the range of 5 to 90%, but the surface-sealed silica-based particles sealing the pores existing on the surface thereof are almost equivalent. Or it has a porosity close to this. Judging from this, it is considered that only the fine pores existing on the surface of the silica-based porous particles are sealed.

The surface-sealed silica-based particles have high moisture resistance, and the moisture absorption rate when the particles are left in an air atmosphere at a temperature of 25 ° C. and a humidity of 90% for 7 days is 1% or less.
Furthermore, the surface-sealed silica-based particles have the following physical characteristics.
(1) The density of the particles is in the range of 0.4 to 2.2 g / ml.
(2) The specific surface area of the particles is in the range of 5 to 400 m ² / g, and the pore volume is in the range of 0.01 to 2.0 ml / g.
(3) The compressive strength of the particles is in the range of 0.1 to 300 kgf / cm ² .

Next, a semiconductor sealing resin composition obtained by mixing the surface sealing silica-based particles with a thermosetting resin as a filler will be specifically described. However, since the surface-sealed silica-based particles can be sufficiently used for other uses such as a printed wiring board and a die attach film, the surface-sealed silica-based particles according to the present invention are limited to the uses described below. Not.

[Resin composition for semiconductor encapsulation]
The resin composition for semiconductor encapsulation according to the present invention is obtained by mixing the surface-encapsulated silica-based particles with a thermosetting resin as a filler.

  The thermosetting resin can be used without any particular limitation as long as it is generally used for semiconductor encapsulation. However, the thermosetting resin has at least two epoxy groups in one molecule. Is preferably used. Examples of such resins include bisphenol-type epoxy resins, novolak-type epoxy resins, triphenolalkane-type epoxy resins, epoxy resins having a biphenyl skeleton, epoxy resins having a naphthalene skeleton, dicyclopentadienephenol novolac resins, phenol-aralkyl-type epoxy resins. Glycidyl ester type epoxy resin, alicyclic epoxy resin, heterocyclic type epoxy resin, halogenated epoxy resin and the like. Moreover, about these resin compounds, you may use individually and may mix and use 2 or more types.

  The surface-sealed silica-based particles have a weight ratio (E / F) of 10/100 to 10 when the weight of the surface-sealed silica-based particles is represented by E and the weight of the thermosetting resin is represented by F. It is preferable to mix so as to be 95/100, preferably 30/100 to 80/100. Here, when the weight ratio is less than 10/100, the low thermal expansion coefficient effect and thermosetting curing, which are the characteristics of the surface-sealed silica-based particles, deteriorate, and when the weight ratio exceeds 95/100. Since the fluidity deteriorates, it becomes difficult to efficiently seal the semiconductor, which is not preferable.

  In the preparation of the semiconductor sealing resin composition, a curing agent such as a phenol compound, an amine compound, or an acid anhydride is used. As this hardening | curing agent, if it is used for the hardening | curing agent of an epoxy resin, it can be used without a restriction | limiting. Among these, bisphenol type resin, novolak resin, triphenolalkane type resin, resol type phenol resin, phenol aralkyl resin, biphenyl type phenol resin, naphthalene type phenol resin, cyclopentadiene having two or more phenolic hydroxyl groups in one molecule. It is preferable to use phenolic resins such as type phenolic resins and acid anhydrides such as methylhexahydrophthalic acid, methyltetrahydrophthalic acid, and methylnadic anhydride.

Furthermore, a coloring agent, a stress relaxation agent, an antifoaming agent, a leveling agent, a coupling agent, a flame retardant, a curing accelerator, and the like can be added to the semiconductor sealing resin composition as necessary.
Moreover, the said semiconductor sealing resin composition can be prepared by a conventionally well-known method. That is, the resin composition is prepared, for example, by mixing the thermosetting resin, the surface-sealing silica-based particles, the curing agent, and the additive as necessary, kneading with a roll mill or the like, and then depressurizing and defoaming. Prepared by processing.
Next, the measurement method used in the present invention is as follows.

[Measuring method]
(1) Average particle diameter of silica-based porous particles A slurry liquid (solid content concentration: 0.1 to 5% by mass) prepared by dispersing porous silica-based particles in a 40% by weight glycerin-containing aqueous solution is prepared. This is subjected to a dispersion treatment for 5 minutes by applying it to an ultrasonic generator (US-2 type, manufactured by Iuch). Next, a sample is taken from the dispersion whose concentration has been adjusted by adding the glycerin aqueous solution, and the sample is placed in a glass cell (size of 10 mm in length, 10 mm in width, and 45 cm in height). The average particle diameter is measured using Seiko Seisakusho: CAPA-700).

(2) Average particle size of silica-based fine particles (silica fine particles) 19.85 g of pure water was added to 0.15 g of silica-based fine particles having a nano-sized particle size or an aqueous dispersion sol of silica fine particles (solid content 20 wt%). A sample with a solid content of 0.15% prepared by mixing was placed in a quartz cell having a length of 1 cm, a width of 1 cm, and a height of 5 cm, and an ultrafine particle size analyzer (Otsuka Electronics Co., Ltd.) using a dynamic light scattering method. ), Model size ELS-Z2), and the particle size distribution of the particle group is measured. In addition, the average particle diameter as used in the field of this invention shows the value computed by cumulant analysis of this measurement result.

(3) Bulk density of silica-based porous particles or surface-sealed silica-based particles According to a measurement method using a bulk measuring device, a funnel, a sieve, and a precision balance as defined in Japanese Industrial Standard JIS5101-1964, silica-based porous particles The bulk density of the particles or surface-sealed silica-based particles is determined.

(4) Porosity of silica-based porous particles or surface-encapsulated silica-based particles Using the bulk density of silica-based porous particles or surface-encapsulated silica-based particles obtained in (3) above, the following calculation is performed. To do.
Porosity (%) = 100 − {(bulk density of amorphous silica) / (bulk density of silica-based porous particles or surface-sealed silica-based particles) × 100}

(5) Pore volume of silica-based porous particles or surface-sealed silica-based particles 10 g of dry powder of silica-based porous particles or surface-sealed silica-based particles is placed in a magnetic crucible and dried at a temperature of 105 ° C. for 1 hour. Then, it is placed in a desiccator and cooled to room temperature. Next, a 1 g sample is taken in a well-washed cell, nitrogen is adsorbed using a nitrogen adsorption device (manufactured by JGC Catalysts & Chemicals Co., Ltd.), and the pore volume is calculated from the following equation.
Pore volume (ml / g) = (0.001567 × (V−Vc) / w)
In the above formula, V is the adsorption amount (ml) in the standard state at a pressure of 735 mmHg, Vc is the cell blank capacity (ml) at a pressure of 735 mmHg, and W is the weight (g) of the sample. Further, the density ratio of nitrogen gas and liquid nitrogen is set to 0.001567.

(6) Specific surface area of silica-based porous particles or surface-sealed silica-based particles About 30 ml of dry powder of silica-based porous particles or surface-sealed silica-based particles is collected in a magnetic crucible (type B-2), 300 After drying at a temperature of 2 ° C. for 2 hours, put in a desiccator and cool to room temperature. Next, 1 g of a sample is taken, and the specific surface area (m ² / g) is measured by the BET method using a fully automatic surface area measuring device (manufactured by Yuasa Ionics Co., Ltd., Multisorb 12 type).

(7) Average pore diameter of surface pores of silica-based porous particles Using the pore volume calculated in (5) above and the specific surface area calculated in (6) above, the surface pores are The average pore diameter is calculated.
Average pore diameter (nm) = 4 × pore volume (ml / g) / specific surface area (m ² / g) × 1000

(8) pH of a mixed solution containing silica-based porous particles and silica fine particles
A dispersion prepared by adding ammonia or the like to a mixed liquid containing silica-based porous particles and silica fine particles to adjust the pH is stirred for 30 minutes or more in a thermostatic bath at 25 ° C., and then a standard solution with pH 4, 7, and 9 is used. Measurement is performed by inserting a glass electrode of a pH meter (F22, manufactured by Horiba, Ltd.) that has been corrected.

(9) Compressive strength of surface-encapsulated silica-based particles From the powder of surface-encapsulated silica-based particles, one particle having an average particle diameter of ± 0.5 μm was taken as a sample, and a micro compression tester (manufactured by Shimadzu Corporation) was used. MCTM-200), a load is applied to the sample at a constant load speed, and the weight at the time when the particles are broken is defined as the compressive strength (kgf / mm ² ). Further, this operation is repeated four times, the compressive strength is measured for five samples, and the average value is taken as the particle compressive strength.

(10) Moisture absorption rate of silica-based porous particles or surface-sealed silica-based particles A predetermined amount of silica-based porous particles or surface-sealed silica-based particles are placed in a magnetic crucible, and the weight thereof is measured with a precision electronic balance (ASONE, ASP214). ) To weigh. Next, the magnetic crucible is placed in a desiccator adjusted to a temperature of 25 ° C. and a humidity of 90% and left for 14 days. Thereafter, the magnetic crucible is taken out and its weight is weighed using a precision electronic balance. Next, the weight change is calculated, and the value is defined as the moisture absorption rate.

Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to the scope described in these examples.

[Example 1]
Process (1 )
A silica sol containing silica-based fine particles having an average particle size of 15 nm (manufactured by JGC Catalysts & Chemicals Co., Ltd., Cataloid S-20L, SiO ₂ content 20% by weight) was subjected to a spray dryer (manufactured by NIRO, NIRO ATMIZER), and the inlet Spray drying was performed under the conditions of a temperature of 240 ° C., an outlet temperature of 55 ° C., and a spray rate of 2 liters / minute to obtain a dry powder 1A of silica-based porous particles.
About the dry powder 1A of the silica-based porous particles thus obtained, the average particle diameter, bulk density, porosity, pore volume, average pore diameter (meaning the average pore diameter of the pores existing on the particle surface) And the moisture absorption rate were measured by the measurement methods described above. The results are shown in Table 1.

Process (2 )
3013 cc of pure water was added to 720 g of dry powder 1A of silica-based porous particles obtained in the step (1) and stirred. Next, 267 g of silica sol (Cataloid SI-350 manufactured by JGC Catalysts & Chemicals Co., Ltd., SiO ₂ content 30 wt%) containing silica fine particles having an average particle diameter of 8 nm was added to the obtained suspension and stirred. This obtained the liquid mixture (solid content: 20 weight%) which disperse | distributed the said silica type porous particle and the said silica particle. The pH of this mixed solution was 8.

Process (3 )
To 4000 g of the mixed solution obtained in the step (2), 30 g of ammonia water having an ammonia concentration of 29% by weight was added and stirred to obtain a mixed solution having a pH of 10.5. Next, the obtained mixed liquid was heated to a temperature of 70 ° C. and stirred at a speed of 200 rpm for 120 minutes.
As a result, at least the silica fine particles (including those in which the particle surface is dissolved) and / or the silica particles in which the dissolved matters are adhered to the inside of the pores existing on the surface of the silica-based porous particles. A liquid was obtained.

Process (4 )
4000 g of the mixed solution obtained in the step (3) was put in an autoclave and heated to a temperature of 150 ° C., and subjected to a heat treatment for 16 hours with stirring. Next, it was cooled to near room temperature and taken out of the system.
As a result, a mixed liquid containing silica-based particles in which pores existing on the surface of the silica-based porous particles are sealed with at least the silica fine particles (including those in which the particle surface is dissolved) and / or a dissolved product thereof. Got.

Process (5 )
The mixed solution obtained in the step (4) was filtered with a quantitative filter paper (No. 5C manufactured by Advantech Toyo Co., Ltd.) using a Buchner funnel (3.2 L manufactured by Sekiya Rika Glass Instruments Co., Ltd.) By repeatedly washing with water, a cake-like substance composed of an aggregate of the surface-sealed silica-based particles was obtained.
Next, the cake-like material was dried at a temperature of 120 ° C. for 16 hours. Next, the dried powder is passed through a juicer mixer (manufactured by Hitachi, Ltd.) to break up the agglomerates, and the dried powder 2A of surface-sealed silica-based particles (hereinafter referred to as “Example dried powder 2A”). Got.
Thus obtained Example dry powder 2A was measured for its average particle size, bulk density, porosity, specific surface area, pore volume, compressive strength and moisture absorption rate by the above measuring methods. The results are shown in Table 3.

Firing step Example dry powder 2A obtained in step (5) was fired at a temperature of 450C for 3 hours. As a result, a fired powder 3A of surface-encapsulated silica-based particles (hereinafter referred to as “Example fired powder 3A”) was obtained.
The thus-obtained Example fired powder 3A was measured for the average particle size, bulk density, porosity, specific surface area, pore volume, compressive strength, and moisture absorption rate by the measurement methods described above. The results are shown in Table 4.

[Examples 2 to 4]
In place of the silica sol used in Example 1, a silica-based fine particle dispersion containing silica-based fine particles manufactured by Catalyst Kasei Kogyo Co., Ltd. or Nippon Aerosil Co., Ltd. shown in Table 1 is used, and partly as necessary These silica sols were spray-dried in the same manner as in Example 1 by changing the spray-drying conditions, and dry powders 1B to 1D of silica-based porous particles shown in Table 1 were obtained.
Next, the operations in steps (2) to (5) of Example 1 were performed under the conditions shown in Table 2, and the surface-sealed silica-based particles 2B to 2D (hereinafter referred to as “Example Dry Powder 2B”). ~ 2D ").
As for Example dry powders 2B to 2D thus obtained, as in Example 1, the average particle diameter, bulk density, porosity, specific surface area, pore volume, compressive strength, and hygroscopicity were respectively set. It was measured. The results are shown in Table 3.

Next, the obtained Example dry powders 2B to 2D were fired under the same conditions as in Example 1 to obtain the fired powders 3B to 3D of the surface-sealing silica-based particles (hereinafter referred to as “Example Firing”). Powders 3B to 3D ”).
As for Example fired powders 3B to 3D thus obtained, the average particle diameter, bulk density, porosity, specific surface area, pore volume, compressive strength, and moisture absorption rate were measured in the same manner as in Example 1. did. The results are shown in Table 4.

[Examples 5 to 6]
Table 1 shows the silica-based fine particle dispersion containing the silica-based fine particles (SiO ₂ content of 100% by weight) used in Example 4 and the acidic silicic acid aqueous solution (containing 5% by weight of the silica component on the basis of SiO ₂ conversion). The mixed dispersion obtained by mixing at the indicated weight ratio and further stirring for 1 hour was subjected to a spray dryer (NIRO, manufactured by NIRO ATMIZER), and the inlet temperature was 240 ° C., the outlet temperature was 55 ° C., and the spraying speed was 2 liters / liter. Spray drying was performed under the conditions of minutes to obtain dry powders 1E to 1F of silica-based porous particles shown in Table 1.

Next, the operations of steps (2) to (5) shown in Example 1 were performed under the conditions shown in Table 2, and dry powders 2E to 2F of surface-sealed silica-based particles (hereinafter referred to as “Example dry powders”). 2E to 2F ").
As for Example dry powders 2E to 2F obtained in this manner, the average particle diameter, bulk density, porosity, specific surface area, pore volume, compressive strength and moisture absorption rate were respectively the same as in Example 1. It was measured. The results are shown in Table 3.

Next, the obtained Example dry powders 2E to 2F were calcined under the same conditions as in Example 1 to obtain calcined powders 3E to 3F of surface-sealing silica-based particles (hereinafter referred to as “Example calcining”). Powder 3E to 3F ”).
As for Example fired powders 3E to 3F thus obtained, the average particle diameter, bulk density, porosity, specific surface area, pore volume, compressive strength, and moisture absorption rate are the same as in Example 1. It was measured. The results are shown in Table 4.

[Example 7]
To the mixed solution 3000 g obtained in the step (3) of Example 1, 1333 g of an aqueous silicic acid solution containing 4.5% by weight of silicon component in terms of SiO ₂ was added.
Next, 4000 g of this mixed solution was put in an autoclave, heated to a temperature of 150 ° C., and subjected to heat treatment for 16 hours with stirring. Subsequently, it cooled to near room temperature and took out out of the system.

Next, the operations of the above steps (4) to (5) are performed under the conditions shown in Example 1, and a surface-powdered silica-based particle dry powder 2G (hereinafter referred to as “Example dry powder 2G”) is obtained. Obtained.
About the Example dry powder 2G thus obtained, the average particle diameter, bulk density, porosity, specific surface area, pore volume, compressive strength, and moisture absorption rate were measured in the same manner as in Example 1. . The results are shown in Table 5.

Next, the obtained Example dry powder 2G was fired under the same conditions as in Example 1 to obtain a fired powder 3G of surface-encapsulated silica-based particles (hereinafter, “Example fired powder 3G”). I got).
As for Example calcined powder 3G thus obtained, the average particle diameter, bulk density, porosity, specific surface area, pore volume, compressive strength, and moisture absorption rate were measured in the same manner as in Example 1. . The results are shown in Table 6.

[Example 8]
208 g of an aqueous tetraethoxysilane solution containing 28.8% by weight of the silicon component in terms of SiO ₂ was added to 3000 g of the mixed solution obtained in step (3) of Example 1.
Next, 3208 g of this mixed solution was put in an autoclave, heated to a temperature of 150 ° C., and subjected to heat treatment for 16 hours while stirring. Subsequently, it cooled to near room temperature and took out out of the system.

Next, the operations of the above steps (4) to (5) are performed under the conditions shown in Example 1, and the surface-sealed silica-based particle dry powder 2H (hereinafter referred to as “Example dry powder 2H”) is obtained. Obtained.
As for Example dry powder 2H thus obtained, the average particle size, bulk density, porosity, specific surface area, pore volume, compressive strength, and moisture absorption rate were measured in the same manner as in Example 1. . The results are shown in Table 5.

Next, the obtained Example dry powder 2H was calcined under the same conditions as in Example 1 to obtain a calcined powder 3H of surface-encapsulated silica-based particles (hereinafter, “Example calcined powder 3H”). I got).
For the Example calcined powder 3H thus obtained, the average particle diameter, bulk density, porosity, specific surface area, pore volume, compressive strength, and moisture absorption rate were measured in the same manner as in Example 1. . The results are shown in Table 6.

[Examples 9 to 10 and Comparative Examples 1 and 2]
2160 cc of pure water was added to 240 g of dry powder 1A of silica-based porous particles obtained in step (1) of Example 1 and stirred. Next, silica sol containing silica fine particles was added and stirred under the conditions shown in Table 7.

Next, the operations of the steps (3) to (5) are performed under the same conditions as in Example 1, and the surface-sealed silica-based particles 2I to 2L (hereinafter referred to as “Example Dry Powders 2I to 2I”). 2J "and" Comparative Example Dry Powder 2K-2L ").
About “Example dry powders 2I to 2J” and “Comparative example dry powders 2K to 2L” thus obtained, as in Example 1, the average particle diameter, bulk density, porosity, ratio The surface area, pore volume, compressive strength, and moisture absorption were each measured. The results are shown in Table 8.

Next, the obtained “Example dry powders 2I to 2J” and “Comparative example dry powders 2K to 2L” were fired under the same conditions as in Example 1 to obtain the surface-sealed silica-based particles. “Example fired powders 3I to 3J” and “Comparative example fired powders 3K to 3L” were obtained.
About “Example calcined powders 3I to 3J” and “Comparative example calcined powders 3K to 3L” thus obtained, as in Example 1, the average particle diameter, bulk density, porosity, ratio The surface area, pore volume, compressive strength, and moisture absorption were each measured. The results are shown in Table 9.

[Examples 11 to 12 and Comparative Examples 3 to 4]
Under the conditions shown in Table 10, 30 g of aqueous ammonia having a different ammonia concentration was added to 4000 g of the mixed solution obtained in Step (2) of Example 1 and stirred. Furthermore, since it is difficult to obtain a high pH (Comparative Example 4) only by adding aqueous ammonia, 80 g of a sodium hydroxide aqueous solution of 70% by weight NaOH was added and stirred. Next, the obtained mixed liquid was heated to a temperature of 70 ° C. and stirred at a speed of 200 rpm for 120 minutes.

Subsequently, the operations of the above steps (4) to (5) are performed under the same conditions as in Example 1, and the surface-sealed silica-based particles 2M to 2P (hereinafter referred to as “Example Dry Powder 2M to 2N "and" Comparative Example Dry Powders 2O-2P ").
About “Example dry powders 2M to 2N” and “Comparative example dry powders 2O to 2P” thus obtained, as in Example 1, the average particle diameter, bulk density, porosity, ratio The surface area, pore volume, compressive strength, and moisture absorption were each measured. The results are shown in Table 11.

Next, the obtained “Example dry powders 2M to 2N” and “Comparative example dry powders 2O to 2P” were fired under the same conditions as in Example 1 to obtain the surface-sealed silica-based particles. “Example fired powders 3M to 3N” and “Comparative example fired powders 3O to 3P” were obtained.
About “Example calcined powders 3M to 3N” and “Comparative example calcined powders 3O to 3P” thus obtained, as in Example 1, the average particle diameter, the bulk density, the porosity, the ratio The surface area, pore volume, compressive strength, and moisture absorption were each measured. The results are shown in Table 12.

[Examples 13 to 14 and Comparative Examples 5 to 6]
30 g of ammonia water having an ammonia concentration of 29% by weight was added to 4000 g of the mixture obtained in step (2) of Example 1 and stirred to obtain a mixture having a pH of 10.5. Subsequently, the obtained liquid mixture was heated to the temperature shown in Table 13, and stirred at a speed of 200 rpm for 120 minutes.

Subsequently, the operations of the above steps (4) to (5) are performed under the same conditions as in Example 1, and the dry powders 2Q to 2T (hereinafter referred to as “Example dry powder 2Q˜ 2R "and" Comparative Example Dry Powders 2S to 2T ").
About “Example dry powders 2Q to 2R” and “Comparative example dry powders 2S to 2T” thus obtained, as in Example 1, the average particle diameter, bulk density, porosity, ratio The surface area, pore volume, compressive strength, and moisture absorption were each measured. The results are shown in Table 14.

Next, the obtained “Example dry powders 2Q to 2R” and “Comparative example dry powders 2S to 2T” were fired under the same conditions as in Example 1 to obtain the surface-sealed silica-based particles. “Example fired powders 3Q to 3R” and “Comparative fired powders 3S to 3T” were obtained.
About “Example calcined powders 3Q-3R” and “Comparative example calcined powders 3S-3T” thus obtained, as in Example 1, the average particle diameter, bulk density, porosity, ratio The surface area, pore volume, compressive strength, and moisture absorption were each measured. The results are shown in Table 15.

[Examples 15 to 16 and Comparative Examples 7 to 8]
4000 g of the mixed solution obtained in the step (3) of Example 1 was put in an autoclave, heated under the temperature conditions shown in Table 16, and heat-treated for 16 hours with stirring. Next, it was cooled to near room temperature and taken out of the system.

Next, the operation of the step (5) is performed under the same conditions as in Example 1, and dry powders 2U to 2X (hereinafter, “Example dry powders 2U to 2V”) and “surface-sealed silica-based particles” and “ Comparative Example Dry Powder 2W to 2X ") was obtained.
About “Example dry powders 2U to 2V” and “Comparative example dry powders 2W to 2X” thus obtained, as in Example 1, the average particle diameter, bulk density, porosity, ratio The surface area, pore volume, compressive strength, and moisture absorption were each measured. The results are shown in Table 17.

Next, the obtained “Example dry powders 2U to 2V” and “Comparative example dry powders 2W to 2X” were fired under the same conditions as in Example 1 to obtain the surface-sealed silica-based particles. “Example calcined powders 3U to 3V” and “Comparative example calcined powders 3W to 3X” were obtained.
About “Example calcined powders 3U to 3V” and “Comparative example calcined powders 3W to 3X” thus obtained, as in Example 1, average particle diameter, bulk density, porosity, ratio The surface area, pore volume, compressive strength, and moisture absorption were each measured. The results are shown in Table 18.

[Comparative Example 9]
3584 g of an aqueous silicic acid solution containing 4.52% by weight of silicon component in terms of SiO ₂ is added to 378 g of dry powder 1A of silica-based porous particles obtained in step (1) of Example 1 for 120 minutes. Stir.
Next, 3962 g of this mixed solution was put in an autoclave, heated to a temperature of 150 ° C., and subjected to a heat treatment for 16 hours with stirring. Subsequently, it cooled to near room temperature and took out out of the system.

Next, the operation of the step (5) was performed under the same conditions as in Example 1 to obtain a dry powder 2Y of surface-sealed silica-based particles (hereinafter referred to as “Comparative Example Dry Powder 2Y”).
For the “Comparative Example Dry Powder 2Y” thus obtained, the average particle diameter, bulk density, porosity, specific surface area, pore volume, compressive strength, and moisture absorption rate were respectively the same as in Example 1. It was measured. The results are shown in Table 19.

Next, the obtained “comparative dry powder 2Y” was calcined under the same conditions as in Example 1 to obtain “comparative calcined powder 3Y” of surface-sealing silica-based particles.
For the “comparative fired powder 3Y” thus obtained, the average particle diameter, bulk density, porosity, specific surface area, pore volume, compressive strength, and moisture absorption rate were respectively the same as in Example 1. It was measured. The results are shown in Table 19.

[Example 17]
330 parts by weight of the surface-sealed silica-based particles obtained in Example 7, 100 parts by weight of phenol novolac type liquid epoxy resin (RE-403 manufactured by Nippon Kayaku Co., Ltd., viscosity: 4000 cps), aromatic as a curing agent 37 parts by weight of amine (Kayahard AA from Nippon Kayaku Co., Ltd.), 5 parts by weight of epoxy silane (KBM-403E from Shin-Etsu Silicon Co., Ltd.) as a coupling agent, defoamer (by Big Chem) BYK-A-506) 3 parts by weight were mixed, kneaded with a three-roll, and then defoamed to obtain a liquid semiconductor sealing resin composition.
Next, the simulated circuit was sealed by applying and curing the resin composition for semiconductor encapsulation on a semiconductor substrate provided with the simulated circuit. Next, a voltage was applied to the simulation circuit, a PTHB test (Pressure Temperature Humidity Bias Test) was performed, and an insulation resistance value (Ω) was measured. The measurement was performed using a gold-plated copper wiring comb-shaped electrode FPC at a temperature of 121 ° C., a humidity of 85%, and an insulation resistance measurement condition of 50 V × 1 min (n = 15).
As a result, it was found that there was little decrease in insulation resistance and excellent moisture resistance. Incidentally, the insulation resistance after leaving the base material in the above-mentioned atmosphere for 1000 hours was 5 × 10 ¹³ Ω, which is almost the same as when nonporous silica particles were used.

FIG. 1 is a photograph (TEM photograph) of a magnification of 250,000 times taken with a transmission electron microscope of a cross section of the surface-sealed silica-based particles obtained from the method of the present invention.

Claims (23)

A method for producing surface-sealed silica-based particles having moisture resistance,
(1) A step of producing a silica-based porous particle having an average particle size of 0.5 to 50 μm by spray-drying a dispersion containing silica-based fine particles having an average particle size of 2 to 300 nm through a spray dryer;
(2) The silica-based porous particles obtained in the step (1) are suspended in pure water or ultrapure water, and then mixed with an aqueous dispersion sol containing silica fine particles having an average particle diameter of 2 to 50 nm. Process,
(3) The pores present on at least the surface of the silica-based porous particles by heat-treating the mixed solution obtained in the step (2) in the presence of an alkali compound at a temperature of 50 to 90 ° C. Attaching the silica fine particles and / or a dissolved product thereof to the inside of
(4) The mixed solution containing the silica-based porous particles obtained in the step (3) is heat-treated at a temperature of 90 to 350 ° C. to obtain fine particles present on the surface of the silica-based porous particles. A step of generating silica-based particles having pores sealed with at least the silica fine particles and / or a solution thereof; and (5) after separating and washing the surface-sealed silica-based particles obtained in the step (4). The manufacturing method of the surface sealing silica type particle | grains characterized by including the process of drying. In the said process (1), the silicic acid is further included in the said dispersion liquid, The manufacturing method of the surface sealing silica type particle | grains of Claim 1 characterized by the above-mentioned. The surface-sealed silica system according to any one of claims 1 to 2, wherein in the step (1), the solid content in the dispersion is in the range of 1 to 50 wt%. Particle production method. The porosity of the silica type porous particle obtained from the said process (1) exists in the range of 5-90%, The manufacture of the surface sealing silica type particle in any one of Claims 1-3 characterized by the above-mentioned. Method. The surface according to any one of claims 1 to 4, wherein an average pore diameter of pores existing on the surface of the silica-based porous particles obtained from the step (1) is in the range of 2 to 25 nm. A method for producing sealing silica-based particles. In the step (2), the water-dispersed sol of silica fine particles includes silica fine particles smaller than the average pore diameter of pores existing on the surface of the silica-based porous particles. The manufacturing method of the surface sealing silica type particle | grains in any one. In the step (2), the water-dispersed sol of silica fine particles has a weight ratio (X / Y) when the weight of the silica fine particles is represented by X and the weight of the silica-based porous particles is represented by Y. The surface sealing according to any one of claims 1 to 6, wherein the surface sealing material is mixed in a suspension of the silica-based porous particles at a ratio of 0.1 / 99.9 to 50/50. A method for producing a silica-based particle. In the said process (3), the said alkali compound is ammonia or ammonium hydroxide, The manufacturing method of the surface sealing silica type particle | grains in any one of Claims 1-7 characterized by the above-mentioned. The method for producing surface-encapsulated silica-based particles according to any one of claims 1 to 8, further comprising a step of adding silicic acid to the mixed liquid obtained from the step (3). In the adding step, when the silicic acid is represented by A and the weight of the silica fine particles is represented by A and the weight of the silicic acid (SiO ₂ conversion standard) is represented by B, the weight ratio (B / A) is 0.1 / 99. The method for producing surface-encapsulated silica-based particles according to claim 9, wherein the silica is added at a ratio of 9 to 30/70. 9. The method according to any one of claims 1 to 8, further comprising a step of adding an organosilicon compound represented by the following general formula (I) or a hydrolyzate thereof to the mixed liquid obtained from the step (3). A method for producing the surface-sealed silica-based particles according to claim 1.
X _n Si (OR) _4-n (I)
(In the formula, X represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 3 carbon atoms, R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 0 to 3). .) In the addition step, the organosilicon compound or a hydrolyzate represents the weight of the silica fine particles in C, and when the weight of the organic silicon compound or its hydrolyzate (SiO ₂ equivalent value) expressed in D, The method for producing surface-sealed silica-based particles according to claim 11, wherein the weight ratio (D / C) is added at a ratio of 0.1 / 99.9 to 30/70. In the said process (3), the said heat processing is performed over 10 to 120 minutes, The manufacturing method of the surface sealing silica type particle | grains in any one of Claims 1-12 characterized by the above-mentioned. In the said process (4), the said heat processing are performed over 5 to 20 hours, The manufacturing method of the surface sealing silica type particle | grains in any one of Claims 1-13 characterized by the above-mentioned. The surface-sealed silica-based particles obtained from the step (5) are further fired at a temperature of 120 to 1000 ° C. Production method. The pores present on the surface of silica-based porous particles having an average particle size of 0.5 to 50 μm obtained by spray-drying a dispersion containing silica-based fine particles having an average particle size of 2 to 300 nm are average particles having a diameter of 2 to 50 nm. Silica fine particles, or surface-sealed silica-based particles having moisture resistance, which are sealed with the silica fine particles and a dissolved product thereof . The surface-sealed silica-based particle according to claim 16, wherein the density of the surface-sealed silica-based particle is in a range of 0.4 to 2.2 g / ml. The specific surface area of the surface-sealing silica-based particles is in the range of 5 to 400 m ² / g, and the pore volume is in the range of 0.01 to 2.0 ml / g. The surface-sealed silica-based particles according to any one of ˜17. The surface-encapsulated silica-based particle according to any one of claims 16 to 18, wherein the surface-encapsulated silica-based particle has a compressive strength in a range of 0.1 to 300 kgf / cm ² . 20. The moisture absorption rate when the surface-encapsulated silica-based particles are allowed to stand for 7 days in an air atmosphere at a temperature of 25 ° C. and a humidity of 90% is 1% or less. Surface-encapsulated silica-based particles. The resin composition for semiconductor sealing formed by mixing the surface sealing silica type particle | grains in any one of Claims 16-20 with a thermosetting resin as a filler. The resin composition for semiconductor encapsulation according to claim 21, wherein the thermosetting resin is a curable epoxy resin having at least two epoxy groups in one molecule. When the surface-sealed silica-based particles represent the weight of the surface-sealed silica-based particles as E and the weight of the thermosetting resin as F, the weight ratio (E / F) is 10/100 to The resin composition for semiconductor encapsulation according to any one of claims 21 to 22, wherein the resin composition is mixed at a ratio of 95/100.