JP2003238141A - Surface modified spherical silica, its production method, and resin composition for semiconductor sealing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spherical silica and a resin composition for semiconductor sealing in which high reliability and good penetrability for filling a gap between an IC chip and a substrate can be obtained. <P>SOLUTION: The surface modified spherical silica includes 0.01-10 mass% of a silane coupling agent which has an average particle size of 0.1-20 μm and a specific surface area of three times a theoretical value or less, and contains an epoxy group and/or amino group on the surface of particles. The resin composition for semiconductor sealing includes the spherical silica in an amount of 30-90 mass%. The method of producing the spherical silica comprises (1) an emulsification process for preparing a W/O type emulsion in which the fine particle silica is dispersed in an aqueous alkali silicate solution being a dispersing phase, (2) a process for coagulating a spherical silica gel by mixing the emulsion with an aqueous mineral acid solution, (3) a process for drying the silica gel, (4) a process for crushing the gel during or after drying, (5) a process for firing the crushed gel at a temperature of 600-1,500°C, and (6) a surface treatment process for treating the fired silica with the silane coupling agent. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to non-porous spherical silica made from alkali silicate and a method for producing the same. More specifically, it is a non-porous spherical material having an extremely low thorium content, which is suitable for use as a filler for IC encapsulating resin, substrates, electronic materials and semiconductor manufacturing equipment, high-purity silica glass and quartz glass, and optical glass raw materials. It relates to a method for producing silica. In particular, the present invention relates to a non-porous spherical silica which is extremely excellent in fluidity at the time of resin mixing and invasion into a narrow gap as a filler for underfill of flip chips, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, with the rapid development of the electronic industry, high-purity silica has come to be used for electronic materials and semiconductor manufacturing. As a matter of course, as other properties, restrictions on the particle top size, fluidity at the time of resin mixing, etc. have been strongly demanded. In particular, in flip chip type semiconductor devices, non-porous spherical silica, which is excellent in fluidity when mixed with a resin, has been required as a filler for underfill, because it has good breakage of coarse particles. In particular, in the case of fillers for underfill, the viscosity at the time of resin mixing is regarded as important, and low viscosity, low thixotropy, and more desirably dilatancy are required. Among the resins, epoxy resins and silicone resins are particularly useful. Among them, when mixed with an epoxy resin composed of bisphenol A diglycidyl ether or bisphenol F diglycidyl ether, low thixotropy, preferably non-porosity showing dilatancy. Spherical silica was desired.

Conventionally, non-porous spherical silica having such good coarse-grain cutting, excellent fluidity when mixed with a resin, and low thixotropy is 1) having a maximum particle diameter of 45 μm and an average particle diameter of 2 to 10 μm. A fused spherical silica characterized in that the ratio of the specific surface area Sw1 of the particles to the theoretical specific surface area Sw2 of the particles, Sw1 / Sw2, is 1.0 to 2.5, and the surface of the particles is smooth.
000-7319).

2) Maximum particle size is 24 μm, average particle size is 1.7
Particle size of ~ 7μm, 3μm or less X1
There 100 / D50 wt% or _{more, (18 + 100 / D 50} ) a fine spherical silica having a particle size distribution, and the epoxy resin or silicone resin is liquid at room temperature, up to 80 weight the fine spherical silica % Spherical silica having a viscosity of 20 Pa · s or less at 50 ° C. (Japanese Patent Laid-Open No. 2000-63630).

Etc. have been proposed.

However, the non-porous spherical silica of 1) is a fused spherical silica as a raw material, and even if the surface fine powder is dissolved, the particle surface is also dissolved. As a result, irregularities on the particle surface and silanol groups on the surface remain. Will end up. Therefore, the expected fluidity cannot be obtained when the resin is mixed. The non-spherical spherical silica of 2) is also substantially fused spherical silica, and fine powder adheres to the surface. Further, even if the fine powder is dissolved as in the method 1), the expected fluidity cannot be obtained for the same reason as above.

The non-porous spherical silicas 1) and 2) exhibit low thixotropy at a viscosity meter measurement of 5 to 10 rpm, but the viscosity tends to increase at low rotational speed (thixotropy). This is not preferable for applications such as underfill materials that are permeated only by capillarity in a stationary state, and thixotropic properties are suppressed as much as possible, and further, fillers exhibiting dilatancy are desired as fillers for underfill.

On the other hand, in consideration of the interaction at the interface between the surface of the silica particles and the resin, the adhesiveness, etc., 3) a resin composition for semiconductor encapsulation comprising a resin and a filler which has been previously treated with a coupling agent (Japanese Patent Laid-Open No. 2000-242242). 63-2307
No. 29) has been proposed.

Further, 4) in an epoxy resin composition comprising an epoxy resin, a curing agent, a curing accelerator and a filler, large particles of ceramics which have been surface-treated with an aminosilane coupling agent and an average particle size of Of the average particle diameter of the large particles of the ceramics, which is ⅛ or less and 5 μm or less, and the small particles of the ceramics surface-treated with the epoxysilane coupling agent, and the weight of the small particles. An epoxy resin composition (Japanese Patent Laid-Open No. 5-32867) has been proposed, which is characterized in that composite particles containing 2/5 or less of the weight of the large particles are used as a filler.

However, none of 3) and 4) was satisfactory in the viscosity behavior at the time of resin blending and the permeability into narrow gaps.

[0011]

A liquid encapsulating composition using spherical silica according to the prior art has both high reliability and good penetration for filling a gap between an IC chip and a substrate. It is hard to say that it is present, and it has been desired to develop spherical silica that can obtain high reliability and good interpenetrating property.

[0012]

Means for Solving the Problems As a result of studies to improve the above-mentioned problems in the prior art, the present inventors have found that spherical silica having a high sphericity and a smooth surface is treated with a silane coupling agent. It was found that the fluidity during resin blending can be significantly improved by modifying. That is, it was found that the treatment of spherical silica having a small specific surface area with sphericity and surface smoothness was effective, and the present invention was completed.

The first aspect of the present invention is that "the average particle size is 0.1 to 2".
A surface-modified spherical silica having a particle size of 0 μm, a specific surface area of 3 times or less of a theoretical value, and 0.01 to 10% by mass of a silane coupling agent on the particle surface. Is the gist.

The second aspect of the present invention is summarized as "the surface-modified spherical silica of the first aspect, wherein the silane coupling agent contains an epoxy group and / or an amino group".

The third invention of the present invention is "a method for producing a surface-modified spherical silica according to the first or second invention, which comprises the following steps.

(1) An emulsification step for preparing a water-in-oil type (W / O type) emulsion in which fine particles are dispersed as an aqueous dispersion of an alkali silicate solution. (2) A water-in-oil type (W / O type) emulsion. Is mixed with an aqueous solution of mineral acid to coagulate spherical silica gel (3) Drying process to dry spherical silica gel (4) Disintegration process to disintegrate during or after drying (5) 1000 to 100 1500 ° C
The firing process (6) is a surface treatment process in which the fired spherical silica is treated with silane coupling.

The fourth invention of the present invention is "to an epoxy resin,
The surface-modified spherical silica of the first or second invention is
90 mass% compounding resin composition for encapsulation "
Is the gist.

Although the flow characteristics have been conventionally improved when a resin is compounded by treating a silica with a silane coupling agent, the treatment effect differs depending on the type of silica to be treated. Of the resin compositions for semiconductor encapsulation, those having a low resin viscosity are often preferred and used, and there has been a strong demand for a filler capable of achieving the lowest viscosity when the resin is compounded. As a result of repeated studies by the present developers, it was found that the surface smoothness and sphericity of the silica filler have a great influence on the resin compounding viscosity even after the silane coupling treatment. That is, by subjecting a silica filler having a smooth surface and a high sphericity to a silane coupling treatment, it is possible to obtain a resin composition having an extremely low viscosity at the time of compounding the resin. The smoothness and sphericity of the particle surface are represented by a specific surface area, and it is desirable that the specific surface area is 3 times or less than the theoretical value. Generally, the diameter is d
(μm) and the specific surface area SA of a true sphere without pores
Can be represented by formula (I) when its true specific gravity is D.

Formula (I): SA (m ² / g) = 6 / (d × D) From the formula (I), the ratio of true spheres of silica having a diameter of d (μm) and a true specific gravity of 2.2. Since the surface area SA (m ² / g) is represented by the following formula (II), for example, the theoretical value of the specific surface area of silica spheres having a diameter of 10 μm is about 0.27 m ² / g.

Formula (II): SA = 2.73 / d The specific surface area is a value determined by the BET method. In the present invention, Betasorb 4200 manufactured by Nikkiso Co., Ltd. was used.

The amount of the silane coupling agent treated on the silica particles may be appropriately selected within the range of 0.01 to 10% by mass. A large excess of the silane coupling agent causes significant agglomeration between particles, which may adversely affect the flow characteristics during resin blending. The amount of silane coupling agent treated is preferably 0.1 to 5
A mass% range is good. However, generally, the coating area per unit mass of each silane coupling agent is known, and it is desirable to add it by several percent from the coating area.

Since the particle size of the silica is used by being mixed with the resin, the average particle size is preferably 0.1 to 20 μm. Regarding the particle size distribution, it is desirable that the average particle size is 4 times or less for the sealing material that is poured into a narrow gap such as underfill. In the present invention, the average particle diameter means the median diameter. The particle size is a value measured by a laser diffraction / scattering method. In the present invention, Coulter LS
130 was used.

In the present invention, it is more preferable that the silica particles before the silane coupling treatment have a dilatancy when blended with an epoxy resin. Dilatancy is the viscosity of E type viscometer at rotation speed 1.0 rpm η1, 2.5
It means that η1 / η2 is less than 1 when the viscosity of rpm is η2. The dilatancy can be determined by using either bisphenol A type or F type epoxy resin. An E-type viscometer is preferable for the viscosity measurement.

The treatment of the silica with a silane coupling agent improves the fluidity characteristics when the resin is blended, but particularly when treated with a silane coupling agent containing an epoxy group and / or an amino group, the fluidity characteristics when the resin is blended. Is significantly improved. The structure is not particularly limited as long as it has an epoxy group and / or an amino group. Β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane as a silane coupling agent containing an epoxy group and / or an amino group, γ-
Glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, N-β (aminomethyl)
γ-aminopropylmethyldimethoxysilane, N-β (aminomethyl) γ-aminopropyltrimethoxysilane, N-β
(Aminomethyl) γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane and the like can be mentioned.

It is also possible to use a silane coupling agent containing an epoxy group and / or an amino group in combination with another silane coupling agent.

In the present invention, the spherical silica can be preferably used in a production method in which an aqueous solution of an alkali silicate is made into an emulsion and reacted with a mineral acid. As a concrete production method, a water-in-oil type (W / O type) emulsion in which finely-dispersed aqueous solution of alkali silicate is dispersed is prepared (emulsification step). It is preferable to use an emulsifying machine for the preparation of the emulsion from the viewpoint of adjusting the particle size. In the preparation of the emulsion, it is possible to sharpen the particle size distribution of the spherical silica produced by treating the emulsion with the emulsifying machine a plurality of times. As the liquid for forming the continuous phase, a liquid that does not react with the alkaline silicate aqueous solution and the mineral acid aqueous solution and is immiscible is used.
The type is not particularly limited, but from the viewpoint of demulsification treatment, it is preferable to use an oil having a boiling point of 100 ° C. or higher and a specific gravity of 1.0 or lower. The mass ratio of the aqueous alkali silicate solution to the oil is 8: 2 to 2: 8. It is preferably 8: 2 to 6: 4.

The oil as the liquid for forming the continuous phase is, for example, aliphatic hydrocarbons such as n-octane, gasoline, kerosene, and isoparaffin hydrocarbon oil, alicyclic hydrocarbons such as cyclononane and cyclodecane, Aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and tetralin can be used. From the viewpoint of emulsion stability, isoparaffin saturated hydrocarbons are preferable.

The emulsifier is not particularly limited as long as it has a stabilizing function for the W / O type emulsion, and a highly lipophilic surfactant such as a polyvalent metal salt of a fatty acid or a sparingly water-soluble cellulose ether is used. be able to. From the viewpoint of post-treatment, it is preferable to use a nonionic surfactant. Specific examples include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan fatty acid esters such as sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate,
Polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, and other polyoxyethylene sorbitan fatty acid esters, polyoxyethylene monolaurate, polyoxyethylene monopalmitate, polyoxyethylene monostearate, polyoxyethylene monooleate Examples thereof include polyoxyethylene fatty acid esters, stearic acid monoglyceride, oleic acid monoglyceride, and other glycerin fatty acid esters.

An appropriate amount of the emulsifier to be added is in the range of 0.05 to 5 mass% with respect to the alkali silicate aqueous solution to be emulsified. Further, considering the treatment in each step, 0.5 to 1 mass% is preferable.

The prepared water-in-oil type (W / O type) emulsion is mixed with an aqueous mineral acid solution to coagulate spherical silica gel (coagulation step). The mineral acid concentration is preferably 15 to 50 mass% in consideration of extraction of impurities. Further, the spherical silica gel produced by reacting so that the sulfuric acid concentration after coagulation becomes 10% by mass or more extracts metallic elements such as Fe and Al to 1 ppm or less, and extremely high-purity spherical silica gel is obtained.
As the mineral acid, sulfuric acid, nitric acid or hydrochloric acid can be used. Sulfuric acid is most desirable in terms of cost. However, for some metals, the solubility of sulfate is low, and in consideration of extractability and prevention of reprecipitation, it is effective to add nitric acid or hydrochloric acid at a liquid concentration of about 0.5 to 3%. Further, by adding other chelating agents such as hydrogen peroxide and ammonium persulfate, it is possible to further increase the purity. By adding a chelate or the like, radioactive elements such as U and Th can be suppressed to 1 ppb or less. It is possible to mix the emulsion with the aqueous mineral acid solution at room temperature of about 25 ° C.
It is also effective to extract impurities after the spherical silica gel is formed, and it is desirable to heat the silica gel within the range of 50 to 120 ° C. Further, considering the shortening of extraction time, about 80 to 100 ° C is desirable. By this heat treatment, the emulsion is demulsified, and the silica content is easily separated from the liquid phase. The spherical silica gel thus obtained is washed with pure water or ultrapure water to wash away the attached ionic metal element.
Using a highly pure aqueous solution of alkali silicate having a radioactive element content of 1 ppb or less is also effective for producing highly pure spherical silica gel.

Next, the produced spherical silica gel is dried (drying step). Moisture is still retained in the spherical hydrous silica particles. This water is divided into attached water and bound water. Usually, the attached water can be easily removed by heating it at a temperature of around 100 ° C, but it is difficult to completely remove the bound water even at a temperature of 400 ° C or higher. A drying process is performed to remove the attached water, and a baking process is performed to remove the bound water and to densify the silica particles.

In the steps of drying and firing, when the material is dried in a stationary state at the time of drying and fired in that state, sintering occurs between some of the particles, which causes an increase in particle diameter.
Sintering between particles can be suppressed by crushing during or after drying and firing, and even after firing, the maximum particle size is 4 times or less of the average particle size A good particle size distribution can be maintained.

The fluidized dryer is more effective because it is crushed while being dried. The drying treatment condition for removing the adhered water is preferably a temperature of 50 to 500 ° C., and practically 100 to 300 ° C. The processing time depends on the drying temperature, 1
It may be appropriately selected within the range of 40 minutes to 40 minutes. Usually 10 ~
Can be dried in 30 hours. Further, by crushing after drying, particles can be fired without sintering even if silica is not kept in a fluid state during drying and firing. When firing silica gel particles having an average particle diameter of 0.1 to 100 μm, crushing after drying is effective for preventing interparticle sintering.

For crushing before firing, a screen having a mesh size of 10 times or less of the maximum particle size is used. Preferably 1
It is preferable to use a screen having an opening of 5 times. It is more preferable to use a screen having a mesh size of 1 to 3 times. The method of crushing using a screen is not particularly limited, but a method using a vibrating screen or an ultrasonic screen or feeding the raw material into the inside of a horizontal cylindrical screen, and rotating the blade attached inside the screen at high speed , A method of continuously crushing (for example, a turbo screener manufactured by Turbo Industry) and the like. The material of the sieve is preferably one which is free from metal contamination.
In order to satisfy this, a resin sieve is preferable. The type of resin is not particularly limited, but polyethylene, polypropylene, nylon, carbon, acrylic, polyester, polyimide, fluororesin, etc. can be used. In order to suppress static electricity at the time of crushing, a resin whose chargeability is suppressed is effective. It is also possible to work under high humidity. Also,
It is also possible to add some water.

Further, crushing and classification can be carried out at the same time by using a screen having a mesh size equal to or smaller than the maximum particle size of the raw silica before crushing. From the particle size distribution of the raw material silica, a sieve having a mesh size equal to or larger than the particle size corresponding to 10% on the sieve is industrially useful.

The firing method after crushing is not particularly limited, but it can be fired at an arbitrary temperature of 600 to 1500 ° C. in a container such as quartz. Further, as other methods, a fluidized firing furnace, a rotary kiln, a flame firing furnace, or the like can be used. In some cases, very weak agglomeration may be observed after firing, but by crushing again using a screen, monodispersed fired silica particles without interparticle sintering and agglomeration can be obtained.

A large number of silanol groups (Si-OH) are present on the surface of silica particles obtained by the wet method, and these silanol groups combine with water in the atmosphere to form the above-mentioned bound water. This silanol group can be removed by calcining the obtained silica gel at a temperature of 1000 ° C. or higher. By this treatment, dense spherical silica having a small specific surface area and no sintering between particles can be obtained. The higher the firing temperature is, the more dense particles can be obtained, and the fluidity at the time of compounding the resin is improved. Therefore, the firing temperature is preferably 1100 ° C. or higher. Further, in order to reduce the silanol on the surface to the utmost, baking at 1150 ° C. or higher is preferable.

The firing time is 1 minute to 20 depending on the firing temperature.
It may be appropriately selected within the range of time. Usually, it can be reduced to a predetermined specific surface area in 2 to 10 hours. The atmosphere for performing the firing treatment may be oxygen, carbon dioxide gas, or the like, and if necessary, an inert gas such as nitrogen or argon may be used. Practically, it should be air.
As an apparatus used when performing the calcination treatment, a calcination furnace that treats the silica particles in a stationary state can be used.
It is also possible to use an apparatus that performs a calcination process while keeping the silica particles in a fluid state, such as a fluidized calcination furnace, a rotary kiln, or a flame calcination furnace. Electric heat or combustion gas can be used as the heating source. Although the water content of the silica gel before firing is not particularly limited, it is preferable to fire silica gel having a water content as low as possible in order to prevent solidification between particles during firing.
Re-crushing after firing is also effective in terms of dispersibility at the time of resin blending. The crushing method is not particularly limited, but it is desirable to use a resin screen.

The calcined spherical silica is treated by silane coupling (surface treatment step). The treatment method is not particularly limited, but considering that the surface of the silica particles is uniformly treated with the silane coupling agent, a method of dispersing the silane coupling agent in a solvent and immersing the silica particles is preferable.
The solvent is not particularly limited, but methanol, ethanol, n-
Propanol, i-propanol, butanol, isoamyl alcohol, alcohols such as ethylene glycol and propylene glycol, ketones such as acetone and methyl ethyl ketone, saturated hydrocarbons such as n-hexane and cyclohexane, toluene, xylene and the like can be used. The mixing ratio of the silane coupling agent and the solvent is not particularly limited, but may be appropriately selected within the range of 1: 1 to 1: 5000 mass ratio. When the silica particles are immersed in the mixed liquid of the solvent and the silane coupling agent, the treatment can be performed at a temperature of about 10 to 80 ° C. for 5 minutes to 10 hours. 2 considering the processing speed
It is desirable that the temperature is about 5 to 50 ° C and the range is from 30 minutes to 3 hours. By this dipping treatment, the silane coupling agent is selectively adsorbed on the silanol groups on the surface of silica, and a part is chemically bound by dehydration condensation.

After the immersion treatment, the solvent is volatilized. The temperature for volatilizing can be appropriately selected depending on the type of solvent. For example, in the case of hexane, when treating about 100 g of silica,
The solvent can be volatilized by heating at 80 ° C for about 2 hours.

After volatilizing the solvent, an aging step is provided to react the unreacted silane coupling agent with the silanol group. Aging can be appropriately selected within the range of 80 to 200 ° C.
100-150 ℃ considering the deterioration of silane coupling agent
The degree is desirable. After aging, it may have aggregated, so
It is desirable to disintegrate again. The crushing method is not particularly limited, but it is desirable to use a resin screen. The type of resin is preferably the type of resin described above in the production of silica. A screen having a mesh size of 10 times or less of the maximum particle size of untreated silica is suitable. It is preferable to use a screen having an opening of 1 to 5 times. It is more preferable to use a screen having a mesh size of 1 to 3 times.

The surface-modified spherical silica according to the present invention can be preferably used as a sealing material using an epoxy resin. That is, an epoxy resin composition comprising an epoxy resin and a curing agent to which the surface-modified spherical silica of the present invention is added in an amount of 30 to 90% can be used as an encapsulant having unprecedented high flow characteristics.

The epoxy compound is not particularly limited and may be a single component or a mixture of two or more components. Specific examples of the epoxy compound include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and diethylene glycol. Diglycidyl ether, trimethylolpropane triglycidyl ether,
(3 ', 4'-epoxycyclohexyl) methyl-3,
4-epoxycyclohexanecarboxylate, ε-caprolactone-modified 3,4-epoxycyclohexylmethyl 3 ′, 4′-epoxycyclohexanecarboxylate and the like can be mentioned. It is preferable to use bisphenol A diglycidyl ether or bisphenol F diglycidyl ether from the viewpoint of heat resistance and mechanical strength of the cured encapsulant obtained by curing.

Examples of the curing agent used in the present invention include aliphatic polyamines, alicyclic aliphatic polyamines, aromatic polyamines, acid anhydrides, phenol novolacs, polymercaptans and the like. In particular, it is preferable to use acid anhydrides because they are less irritating to the skin, have a long pot life, and have excellent heat properties, mechanical properties, and electrical properties of the cured product. The acid anhydride is not particularly limited as long as it has at least one acid anhydride group in the molecule, and may be a single component or a mixture of two or more components.

Specific examples of the acid anhydride include hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride,
3-Methyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, methyl nadic acid anhydride, 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride , Glycerol tris anhydro trimellitate, pyromellitic dianhydride, benzophenone tetracarboxylic acid anhydride, methylcyclohexene tetracarboxylic acid anhydride and the like.
Particularly, in consideration of fluidity when mixed with an epoxy compound, 4-methylhexahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, which is a liquid monofunctional acid anhydride at room temperature, Methyl nadic acid anhydride and the like are preferable.

The mixing ratio of the epoxy compound to the monofunctional acid anhydride and the polyfunctional acid anhydride is not particularly limited, but the total number of epoxy groups: the total number of acid anhydride groups is 10. It is preferable to mix them in the range of 10:10 to 10: 6. If there are many acid anhydride groups beyond this range,
The moisture resistance reliability of the cured product of the liquid epoxy resin encapsulating material may decrease, and if the number of acid anhydride groups is less than this range, the glass transition temperature of the cured product of the liquid epoxy resin encapsulating material decreases. However, the heat resistance may decrease.

The curing agent used in the present invention is
The curing agent is not limited to one kind, and, for example, an acid anhydride curing agent and a polyamine or a phenol novolac curing agent may be used in combination.

If necessary, the liquid encapsulating resin of the present invention may contain a curing accelerator, a plasticizer, a pigment, a surfactant, a leveling agent, an antifoaming agent and the like.

The curing accelerator that can be used in the present invention is not particularly limited, and examples thereof include 1-cyanoethyl-2-ethyl-4-methylimidazole and 2-
Methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-
Imidazole compounds such as methylimidazole, organic phosphine compounds such as triphenylphosphine and tributylphosphine, tertiary amine compounds such as triethylenediamine and benzyldimethylamine, triazole compounds, organic metal complex salts, organic acid metal salts, quaternary ammonium salts, etc. Can be mentioned. These may be used alone or in combination of two or more. The use of an imidazole compound is preferable because the heat resistance of the cured product of the liquid encapsulating resin is improved.

As the plasticizer, a silicone polymer,
Examples thereof include acrylic polymers. Examples of pigments include carbon and titanium oxide. Examples of the surfactant include polyethylene glycol fatty acid ester, sorbitan fatty acid ester, fatty acid monoglyceride and the like.

In particular, when the epoxy resin is a liquid type at room temperature, the content of the surface-modified spherical silica is 30 to 80% by mass, it has a low viscosity and a high gap permeability, and it can be suitably used as an underfill material.

[0052]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples.

Example 1 Preparation of Spherical Silica Gel Particles 1-1) Preparation of Emulsion JIS No. 3 water glass was concentrated as water glass and the viscosity at 25 ° C. was adjusted to 350 cp. Isoparaffin carbonized as a liquid for forming a continuous phase. Hydrogen oil (“ISOZOL 40
0 ", manufactured by Nippon Petrochemical Co., Ltd., and sorbitan monooleate (" Reodol SP-O10, manufactured by Kao ") was used as an emulsifying agent. After mixing each raw material and roughly stirring with a stirrer, it was emulsified at a rotation speed of 2980 rpm using an emulsifier and 415 g of an emulsion was collected.

1-2) Coagulation of spherical silica gel particles, extraction of impurities, and washing treatment 575 g of 28% sulfuric acid aqueous solution was prepared, and the above-mentioned emulsion was added thereto while stirring at room temperature. After the addition was completed, stirring was continued at room temperature for another 40 minutes. Next, 40 g of 62% industrial nitric acid was added with stirring, and the mixture was further stirred for 20 minutes, and then 100 with stirring.
Heated to ° C and held for 30 minutes. By this treatment, the emulsion-like reaction liquid was separated into an oil phase (upper layer) and an aqueous phase in which silica gel particles were dispersed (lower layer).

After removing the oil phase, the silica gel particles in the aqueous phase were filtered and washed by a conventional method. After washing the reaction solution with 0.01% sulfuric acid aqueous solution for replacement, use pure water and the pH of the washing solution is 4
Repeated until the above. Dehydration was performed using a Nutsche to obtain spherical hydrous silica particles.

2> Drying / Crushing / Firing Step of Spherical Hydrous Silica Particles The resulting hydrous silica particles were dried at a temperature of 120 ° C. for 20 hours, and
00 g of silica particles were obtained. The dried silica particles were crushed with a polyester mesh 33 μm sieve, and a quartz beaker (1
Liter) and baked at 1150 ° C. for 6 hours.

When the spherical silica particles a obtained by firing were analyzed, alkali metals such as Na, K and Li, alkaline earth metals such as Ca and Mg and Cr and F were used.
The concentration of each transition metal element such as e and Cu was 1 ppm or less, and the total of radioactive elements of U and Th was 0.1 ppb or less. Table 1 shows various measurement and observation results of the obtained spherical silica particles a. The obtained silica particles had an average particle diameter of 4.0 μm, a maximum particle diameter of 12 μm, and a true specific gravity of 2.19. The specific surface area measured by the BET method is 0.
It was 1.0 times the theoretical value at 7 m ² / g. In addition, from the electron micrograph, spherical silica particles having a content of particles having a sphericity of 0.9 or more of 90% or more and having a good surface smoothness were obtained.

3> Silane coupling treatment step on spherical silica particles 0.6 g of KBM-573 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent and 100 g of toluene were mixed and stirred for 30 minutes. 100 g of the spherical silica particles obtained above was added to a mixed solution of a silane coupling agent and toluene, and the mixture was further stirred for 30 minutes. Next, the solvent was removed using a rotary evaporator, and the mixture was aged at 120 ° C. for 2 hours. After aging, it was crushed with a polyester 33 μm sieve.

The particle size of silica before surface modification was measured using LS130 manufactured by Coulter. The specific surface area was measured using Betasorb 4200 manufactured by Nikkiso.

When measuring the resin compounding viscosity and the gap permeability, the epoxy resin used was Epicoat 815 manufactured by Japan Epoxy Resin and Epotote YDF-8170C manufactured by Tohto Kasei.
The compounding ratio was filler: epoxy resin = 70: 30 mass ratio. The resin compounding viscosity was measured at 50 ° C. using Toki Sangyo RE-80R, and the cone was 3 ° R14 cone (No. 4 cone). For the gap permeability, a gap of 75 μm was formed using a glass plate, and the time (second) for permeating the gap by 2 cm was measured. Gap permeability was measured at 110 ° C.

The above results are shown in Table 1.

Example 2 A surface-modified spherical silica was prepared in the same manner as in Example 1 except that KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the silane coupling agent in the silane coupling treatment step on the spherical silica particles a. Was manufactured and various evaluations were performed. The results are shown in Table 1.

Example 3 A surface-modified spherical silica was produced in the same manner as in Example 1 except that the amount of the silane coupling agent added was 0.2 g in the silane coupling treatment step on the spherical silica particles a. Various evaluations were made. The results are shown in Table 1.

Comparative Example 1 Spherical silica particles with fused spherical silica b having an average particle size of 4 μm
A surface-modified spherical silica was produced in the same manner as in Example 1 except that (Tatsumori Co. PLV-4) was used, and various evaluations were performed.
The results are shown in Table 1.

Comparative Example 2 Spherical silica particles b (PLV-4 manufactured by Tatsumori Co., Ltd.) had an average particle size of 4
Surface-modified spherical silica was produced in the same manner as in Example 2 except that fused spherical silica of μm was used, and various evaluations were performed. The results are shown in Table 1.

Comparative Examples 3 to 6 Spherical silica particles a and b before silane coupling treatment
Table 1 shows the results of various evaluations of the above.

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[Table 1]

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According to the method of the present invention, it is possible to obtain surface-modified spherical silica which exhibits extremely high flow characteristics when blended with a resin, as compared with the prior art. The surface-modified spherical silica obtained by the method of the present invention is a high-purity surface-modified spherical silica in which the content of radioactive elements is suppressed to an extremely low level.
It can also be suitably used for electronic parts and the like. Particularly, it can be suitably used as a filler for a liquid encapsulating material which is poured into a narrow gap.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nobutaka Kokubun             3-10-1, Daikokucho, Tsurumi-ku, Yokohama-shi, Kanagawa             Ryo Rayon Co., Ltd., Chemical Products Development Laboratory F term (reference) 4G072 AA38 AA41 BB07 GG01 GG03                       HH14 HH19 HH30 JJ11 LL06                       MM26 MM31 MM36 QQ06 UU01                 4J002 CD001 DJ016 FB136 FB146                       GQ00                 4M109 AA01 EB06 EB13

Claims (4)

[Claims] 1. An average particle size of 0.1 to 20 μm, a specific surface area of 3 times the theoretical value or less, and a silane coupling agent on the particle surface.
Surface-modified spherical silica containing 0.01 to 10% by mass. 2. The surface-modified spherical silica according to claim 1, wherein the silane coupling agent contains an epoxy group and / or an amino group. 3. The method for producing the surface-modified spherical silica according to claim 1, which comprises the following steps. (1) An emulsification step for preparing a water-in-oil type (W / O type) emulsion in which fine particles are dispersed with an aqueous solution of an alkali silicate as a dispersion phase. (2) A water-in-oil type (W / O type) emulsion is used as a mineral acid. Coagulation step of mixing with aqueous solution to coagulate spherical silica gel (3) Drying step of drying spherical silica gel (4) Disintegration step of disintegrating during or after drying (5) Disintegrated spherical silica gel at 600-1500 ° C Baking step of baking (6) Surface treatment step of processing the baked spherical silica with a silane coupling agent 4. A resin composition for encapsulation, comprising 30 to 90% by mass of the surface-modified spherical silica according to claim 1 or 2 mixed with an epoxy resin.