JP4605864B2 - Method for producing spherical silica particle aggregate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spherical silica particle aggregate, a production method thereof, and a resin composition using the same. More specifically, the present invention is composed of non-attached / non-aggregating spherical silica particles, and has a wide particle size distribution range, and is suitable for silica fillers for semiconductor sealing materials, particularly flip-chip underfill materials. A spherical silica particle aggregate suitable for use as a semiconductor material, a method for efficiently producing such a spherical silica particle aggregate with a controllable degree of dispersion (CV value) in particle size distribution, and the above-mentioned spherical silica particle aggregate, It is related with the resin composition used as such.
[0002]
[Prior art]
Spherical silica particles are used as fillers for semiconductor resin encapsulants, but in recent years, as the degree of integration of semiconductors has increased, resin encapsulants that are highly filled with silica particles have been required. .
[0003]
By the way, a chip-on-board method has been conventionally used as a mounting method for electronic components. This chip-on-board system includes a pin grid array, a ball grid array, and the like, in which the chip is bonded to the substrate, the chip and the substrate are connected by wire bonding, and the chip is sealed with resin. is there.
[0004]
Conventional chip-on-board resins are blended with an inorganic filler typified by silica powder to reduce the stress strain resulting from the difference in thermal expansion coefficient between the substrate and the resin. Since it was on the chip, there was no problem even if the particle size of silica was not specified.
[0005]
However, in recent years, the flip chip method, which is a mounting method in which the chip and the substrate are electrically connected by bumps and the chip and the substrate are sealed with a resin, has been adopted. Problems began to arise. That is, in this flip chip method, when sealing a chip, since the distance between the chip and the substrate is as narrow as 100 μm or less, the conventional chip-on-board resin using silica having a particle size of 50 μm or more is used between the chip and the substrate. The resin is poorly filled and cannot be used for sealing.
[0006]
Particularly recently, the gap between the substrate and the chip has been narrowed to about 10 to 20 μm and tends to become narrower in the future, and a sealing material with excellent filling property (flowability) is required. The viscosity of the stopper itself and the filler size are important.
[0007]
Further, in order to achieve low thermal expansion and high thermal conductivity of the encapsulant, high filling with a filler is desired. For this purpose, a filler with a small particle size (submicron to several micron level) is required. Further, as the shape of the filler, a spherical filler is preferable from the viewpoint of local stress, deformation of gold wire at the time of low pressure transfer molding due to increase in melt viscosity at high filling, and cutting.
[0008]
On the other hand, memory cells have been reduced and miniaturized with higher integration, and soft error countermeasures have become important, and low α-rays have been required. The main cause of this α ray is uranium and thorium contained in the silica particles, which are currently at the 0.1 ppm level, but further reduction is desired, and there are also few ionic impurities. It is desired.
[0009]
For spherical silica particles, various techniques have been used so far, such as (1) fine fused spherical silica and a method for producing the same (Japanese Patent Publication No. 6-96445), (2) high purity spherical silica and a method for producing the same (Japanese Patent Laid-Open No. Hei 7- No. 69617), (3) Monodispersed spherical silica production method (JP-A-6-87608), (4) Spherical silicone fine particle production method (Japanese Patent Publication No. 5-88889), and the like.
[0010]
However, the fine fused spherical silica (1) has a uranium and thorium content of 1 ppb or less and an average particle size of 10 μm or less. In particular, there are many particles of 10 μm or more. The high-purity spherical silica (2) has a high purity such that the content of radioactive material is 1 ppb or less, the ionic impurities are 1 ppm or less, and the electric conductivity of boiled and extracted water is 10 μS / cm or less. However, according to the manufacturing method, it is difficult to control the particle size distribution, and there is a possibility that aggregated and coalesced particles exist. In addition, according to the production method of monodispersed spherical silica (3), it is possible to narrow the particle size control and particle size distribution by selecting the reaction conditions, but the control of the particle size distribution is not as it is. Is possible. In addition, looking at the shape of the particle size distribution, the distribution has a long tail from the peak centered on the particle size to the smaller or larger one, with ultrafine particles of 0.3 μm or less and 10 μm or more. Coarse particles are present. Further, according to the method (4) for producing spherical silicone fine particles, particles having a narrow particle size distribution or particles having a high CV value are obtained by high stirring, but it is not always easy to control the particle size distribution.
[0011]
The present inventors previously proposed a method for producing polyorganosiloxane fine particles using an anionic surfactant (Japanese Patent Laid-Open No. 11-181095). However, although the silica fine particles obtained by this method are suitable for liquid crystal spacers that require particles having a small CV value and a narrow particle size distribution, an anionic surfactant is used in the production of the particles. Since it is used, ionic impurities are likely to be mixed, it is not suitable as a filler for a semiconductor encapsulant, and it is not suitable as a filler for a semiconductor encapsulant from the viewpoint of a decrease in fluidity of the encapsulant.
[0012]
[Problems to be solved by the invention]
  Under such circumstances, the present invention is composed of non-bonded / non-aggregating spherical silica particles, has a wide particle size distribution range, and is a silica filler for semiconductor encapsulant, particularly an underfill material for flip chip. Of spherical silica particles suitable as a silica fillerBody, Efficient production with controllable CV valueThe lawIt is intended to provide.
[0013]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have a coalescence ratio of a certain value or less, the average particle diameter and the distribution width of the particle diameter are in a specific range, and the CV value. It has been found that a spherical silica particle aggregate having a certain value or more can meet the purpose as a silica filler for a semiconductor encapsulant.
[0014]
Furthermore, the concentration of nonionic surfactant and anionic surfactant and the concentration of ammonia as a hydrolysis catalyst are controlled to hydrolyze and condense the alkoxysilane compound and its partially hydrolyzed condensate to produce polyorganosiloxane particles. After the production, a CV value can be easily controlled by performing a washing treatment, a drying treatment, and a firing treatment in the presence of oxygen to easily obtain a spherical silica particle aggregate having a desired property. I found out.
[0015]
  The present invention has been completed based on such knowledge..
[0016]
  That is, the present invention
(A) Nonionic surfactant or anionic surfactant 1 × 10^-2~ 1x10^-FourAn aqueous solution containing% by weight has the general formula (I)
    R¹nSi (OR²)_4-n ... (I)
(Wherein R¹Is a non-hydrolyzable group having 1 to 20 carbon atoms, a (meth) acryloyloxy group or an epoxy group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, An aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, R²Represents an alkyl group having 1 to 6 carbon atoms, n represents an integer of 1 to 3, and R¹Each R¹May be the same or different, OR²If there is more than one, each OR²They may be the same or different. )
After adding and dissolving the organosilicon compound and / or its partially hydrolyzed condensate, the ammonia concentration is 0.25 × 10^-3~100× 10^-3Ammonia water is added so as to have a mole / liter to hydrolyze and condense the organosilicon compound and / or a partially hydrolyzed condensate thereof, and then the precipitated particles are grown, and then ammonia and / or amine are added. A process for producing polyorganosiloxane particles to be added and aged,
(B) a step of washing the particles obtained in the step (A),
(C) a step of drying the particles obtained in the step (B), and
(D) A step of firing the particles obtained in the step (C) in the presence of oxygen at a temperature of 350 to 1100 ° C.,
A method for producing a spherical silica particle aggregate characterized by comprising
Is to provide.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The true spherical silica particle aggregate of the present invention is an aggregate (powder) of non-bonding / non-aggregating true spherical silica particles, and the bonding rate is 0.1% or less. When the coalescence rate exceeds 0.1%, the object of the present invention is not sufficiently achieved, and the performance as a silica filler for semiconductor encapsulation, particularly as an underfill material for flip chip, becomes insufficient.
[0019]
The aggregate needs to have a particle size distribution width in the range of 0.3 to 10 μm. When particles having a particle size of less than 0.3 μm are present, when used as a silica filler for semiconductor encapsulation, the viscosity of the resin encapsulant increases, which causes a decrease in fluidity. On the other hand, if there is a particle having a particle size exceeding 10 μm, the particle may be larger than the gap between the substrate and the chip, making it unsuitable for the flip chip underfill material. In order to make the distribution width of the particle diameter within the above range, it is necessary to control the average particle diameter of the aggregate in the range of 0.6 to 6 μm. If the average particle size deviates from this range, it becomes difficult to obtain a desired particle size distribution width.
[0020]
Further, the true spherical silica particle aggregate of the present invention has a dispersion degree (CV value) of particle size distribution of 10% or more. When the CV value is less than 10%, the aggregate approaches monodispersion. In this case, if the particle size of the particles is small, the filling rate can be increased, but the viscosity of the resin sealing material is increased and the fluidity is increased. descend. On the other hand, when the particle size of the particles is large, an increase in the viscosity of the resin sealing material can be suppressed, but the filling rate decreases. Therefore, in the present invention, by increasing the CV value to 10% or more and broadening the distribution, the filling rate is improved and the increase in viscosity is suppressed. A preferable CV value is in the range of 10 to 40%, and particularly preferably in the range of 10 to 25%.
[0021]
In addition, the dispersion degree (CV value) of the particle size distribution is obtained by the following equation.
CV value (%) = (standard deviation of particle size / average particle size) × 100
Further, in the true spherical silica particle aggregate of the present invention, the water absorption is preferably 1.5% by weight or less when kept for 48 hours in an atmosphere of 30 ° C. and RH 90%. When the water absorption exceeds 1.5% by weight, the performance as a silica filler for semiconductor encapsulation becomes insufficient, which is not preferable. The water absorption rate is more preferably 1% by weight or less, and still more preferably 0.6% by weight or less.
[0022]
Further, the aggregate preferably has a total content of uranium and thorium of 0.5 ppb or less and an ionic impurity content of 1 ppm or less. Uranium and thorium are α-ray radioactive materials, and when their total content exceeds 0.5 ppb, it causes soft errors, particularly in high-density integrated circuit electronic components. A more preferable total content of uranium and thorium is 0.2 ppb or less.
[0023]
Further, alkaline metals such as Na, K and Li, alkaline earth metals such as Ca and Mg, and ionic impurities such as Cl cause corrosion of aluminum wiring. Therefore, in the present invention, these ionic impurities are used. The content of is preferably 1 ppm or less, more preferably 0.5 ppm or less.
[0024]
The aggregate of true spherical silica particles of the present invention has the general formula (I)
R¹nSi (OR²)_4-n                               ... (I)
(Wherein R¹Is a non-hydrolyzable group having 1 to 20 carbon atoms, a (meth) acryloyloxy group or an epoxy group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, An aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, R²Represents an alkyl group having 1 to 6 carbon atoms, n represents an integer of 1 to 3, and R¹Each R¹May be the same or different, OR²If there is more than one, each OR²They may be the same or different. )
A polyorganosiloxane particle aggregate obtained by hydrolyzing and condensing the organosilicon compound represented by the formula (1) is preferably fired in the presence of oxygen.
[0025]
R in the general formula (I)¹The alkyl group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 10 carbon atoms, and the alkyl group may be linear, branched or cyclic. Examples of this alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, and cyclopentyl. Group, cyclohexyl group and the like. As a C1-C20 alkyl group which has a (meth) acryloyloxy group or an epoxy group, the C1-C10 alkyl group which has the said substituent is preferable, and this alkyl group is linear, branched, Any of cyclic | annular form may be sufficient. Examples of the alkyl group having this substituent include γ-acryloyloxypropyl group, γ-methacryloyloxypropyl group, γ-glycidoxypropyl group, 3,4-epoxycyclohexyl group, and the like. The alkenyl group having 2 to 20 carbon atoms is preferably an alkenyl group having 2 to 10 carbon atoms, and the alkenyl group may be linear, branched or cyclic. Examples of the alkenyl group include vinyl group, allyl group, butenyl group, hexenyl group, octenyl group and the like. As a C6-C20 aryl group, a C6-C10 thing is preferable, for example, a phenyl group, a tolyl group, a xylyl group, a naphthyl group etc. are mentioned. As a C7-20 aralkyl group, a C7-10 thing is preferable, for example, a benzyl group, a phenethyl group, a phenylpropyl group, a naphthylmethyl group etc. are mentioned.
[0026]
On the other hand, R²The alkyl group having 1 to 6 carbon atoms represented by may be linear, branched or cyclic, and examples thereof include methyl, ethyl, n-propyl, isopropyl, n- Examples thereof include a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a cyclopentyl group, and a cyclohexyl group.
[0027]
Examples of the organosilicon compound represented by the general formula (I) include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyl Triethoxysilane, butyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ- Examples include methacryloyloxypropyltrimethoxysilane, dimethyldimethoxysilane, and methylphenyldimethoxysilane. Of these, methyltrimethoxysilane and vinyltrimethoxysilane are particularly preferred. One of these organosilicon compounds may be used alone, or two or more thereof may be used in combination.
[0028]
According to the method of the present invention, the spherical silica particle aggregate of the present invention having the above-described properties is shown in the following (A) production process of polyorganosiloxane particles, (B) washing treatment step, (C) drying treatment step, and (D) It can manufacture efficiently by performing a baking treatment process.
[0029]
Next, each step will be described.
(A) Process
In this step (A), the organosilicon compound represented by the general formula (I) and / or the hydrolysis condensate thereof is hydrolyzed and condensed in the presence of ammonia in an aqueous solution containing a surfactant. This is a process for producing polyorganosiloxane particles.
[0030]
In this step, a nonionic surfactant or an anionic surfactant is used as the surfactant. Here, as the nonionic surfactant, those having an HLB value in the range of 8 to 20 are preferably used. This HLB is an index representing the balance between hydrophilicity and lipophilicity, and the smaller the value, the higher the lipophilicity. When the HLB value deviates from the above range, the effect of the present invention is not sufficiently exhibited. In order to exhibit the effect of this invention better, what has a HLB value in the range of 10-17 is preferable.
[0031]
The nonionic surfactant is not particularly limited as long as it has an HLB value in the above range, and examples thereof include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene sterol ether, polyoxyethylene Ethylene lanolin derivatives, ethylene oxide derivatives of alkylphenol formalin condensates, polyoxyethylene polyoxypropylene block polymers, ether type nonionic surfactants such as polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene glycerin fatty acid ester, polyoxyethylene Ether ester type nonionic properties such as castor oil and hydrogenated castor oil, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester Surfactants, polyethylene glycol fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, ester type nonionic surfactants such as sucrose fatty acid esters, polyoxyethylene fatty acid amides, polyoxyethylene alkylamines, alkyls Examples thereof include nitrogen-containing nonionic surfactants such as amine oxides. Among these, ether type is preferable, and polyoxyethylene alkylphenyl ether is particularly preferable. These nonionic surfactants may be used alone or in combination of two or more.
[0032]
On the other hand, as the anionic surfactant, those having an HLB value in the range of 18 to 42 are preferably used. When the HLB value deviates from the above range, the effect of the present invention is not sufficiently exhibited. Such an anionic surfactant is not particularly limited as long as the HLB value is in the range of 18 to 42, but examples thereof include alkylaryl sulfonates, alkyl sulfates, fatty acid alkali salts, alkyl phosphates, Examples thereof include alkylphosphonates. Among these, alkyl aryl sulfonates having 8 to 18 carbon atoms in the alkyl group, alkyl sulfates having 8 to 18 carbon atoms in the alkyl group, and fatty acid alkali salts having 8 to 18 carbon atoms in the alkyl group are preferable. In particular, sodium dodecyl sulfate, dodecyl benzene sulfonate, and potassium oleate are preferred. Moreover, this anionic surfactant may be used independently and may be used in combination of 2 or more type.
[0033]
When the nonionic surfactant and the anionic surfactant are compared, it is advantageous to use the nonionic surfactant rather than the anionic surfactant from the viewpoint of mixing ionic impurities.
In the step (A), first, the nonionic surfactant or the anionic surfactant 1 × 10 is used.^-2~ 1x10^-FourAn aqueous solution containing% by weight is prepared. If the concentration of the surfactant deviates from the above range, particles having a low CV value are generated, particles having a CV value of 10% or more are not generated, and the object of the present invention cannot be achieved.
[0034]
Examples of the aqueous solution containing a nonionic surfactant or an anionic surfactant include a solution obtained by dissolving the surfactant in an aqueous solvent composed of water or a mixed solvent of water and a water-miscible organic solvent. It is done. Here, examples of the water-miscible organic solvent include lower alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone, dimethyl ketone and methyl ethyl ketone, and ethers such as diethyl ether and dipropyl ether. .
[0035]
Next, the organosilicon compound represented by the general formula (I) and / or its partial hydrolytic condensation is added to the aqueous solution containing the nonionic surfactant or the anionic surfactant at a predetermined concentration thus prepared. The product is preferably added in an amount of 0.01 to 0.3 parts by weight with respect to 1 part by weight of the aqueous medium, and dissolved by stirring to obtain a transparent solution. At this time, if the amount of the organosilicon compound or its hydrolysis condensate is less than the above range, the production efficiency is poor and impractical, and if it is more than the above range, gelation may not occur and particles may not be generated.
[0036]
Subsequently, ammonia water having a concentration of preferably 0.5 to 2 mol / liter is added to the clear solution._ThreeConcentration is 0.25 × 10^-3~ 150 × 10^-3The organic silicon compound and its hydrolysis condensate are hydrolyzed and condensed by adding the mixture so as to have a mol / liter and stirring slowly. At this time, NH_ThreeConcentration is 0.25 × 10^-3If it is less than mol / liter, hydrolysis and condensation reactions are unlikely to proceed, and there is a risk that particles will not precipitate, and 150 × 10^-3If it exceeds mol / liter, coalesced particles and aggregated particles are produced, and the object of the present invention cannot be achieved. That is, true spherical particles can be obtained by performing synthesis within this concentration range.
[0037]
The reaction temperature at this time depends on the raw material organosilicon compound and the kind of the hydrolysis condensate thereof, but is generally selected in the range of 0 to 60 ° C.
As the hydrolysis and condensation reaction proceed, particles are precipitated and further, the precipitated particles grow. After completion of the grain growth, ammonia and / or an amine are added and ripened. In this case, preferred examples of the amine include monomethylamine, dimethylamine, monoethylamine, diethylamine, and ethylenediamine.
[0038]
The amount of ammonia or amine added is not particularly limited, but is preferably selected so that the pH of the reaction system is in the range of 9.0 to 12.0. The aging temperature may be carried out at the same temperature as in the above reaction, or may be carried out by slightly raising the temperature. The aging time depends on the reaction temperature, pH, etc., and cannot be determined generally, but usually about 1 to 20 hours is sufficient.
In this way, true spherical polyorganosiloxane particles that are non-fusing and non-aggregating and have a large degree of dispersion (CV value) in the particle size distribution are obtained.
[0039]
(B) Process
The step (B) is a step of washing the polyorganosiloxane particles obtained in the step (A). There is no restriction | limiting in particular as washing | cleaning process of this particle | grain in this process, According to a conventional method, it wash | cleans sufficiently using lower alcohols, such as methanol.
After the cleaning treatment, if necessary, classification treatment may be performed to remove maximal particles or tiny particles, and a subsequent drying step may be performed. Although there is no restriction | limiting in particular as a classification processing method, The wet classification method which classifies using the sedimentation speed changes with particle sizes is preferable.
[0040]
(C) Process
The step (C) is a step of drying the polyorganosiloxane particles obtained by washing in the above (B) and further classification if necessary. The drying treatment in this step is usually performed at a temperature in the range of 100 to 200 ° C.
[0041]
(D) Process
The step (D) is a step of firing the polyorganosiloxane particles dried in the step (C) in the presence of oxygen. This calcination treatment is carried out in the presence of oxygen, but it is advantageous to perform calcination in air from the viewpoint of economy. The firing temperature is in the range of 350 to 1100 ° C. If the temperature is less than 350 ° C., the firing is insufficient, and it is not necessary to fire at a temperature higher than 1100 ° C., and it can be sufficiently fired at a temperature of 1100 ° C. or less. Thus, it is preferable to perform the baking treatment at a temperature at which the organic components are completely decomposed and removed. Moreover, there is no restriction | limiting in particular about a baking apparatus, An electric furnace, a rotary kiln, etc. can be used.
In this way, the spherical silica particle aggregate of the present invention having the above-described properties can be produced efficiently.
[0042]
The present invention also provides a resin composition containing 10 to 90% by weight of the spherical silica particle aggregate of the present invention having the above-described properties, particularly a resin composition used for a semiconductor resin encapsulant.
Examples of the resin composition used for the semiconductor resin encapsulant include (a) an epoxy resin, (b) a curing agent, (c) a spherical silica particle aggregate of the present invention, and, in some cases, various other types. The composition which contains an additive and content of this (C) component is 10 to 90 weight% can be mentioned.
[0043]
In the resin composition, the epoxy resin used as the component (a) is not particularly limited as long as it is a curable epoxy resin having two or more epoxy groups in one molecule. For example, bisphenol A type Examples include epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, novolac type epoxy resins, glycidyl ester type epoxy resins, alicyclic epoxy resins, and the like, and those having less chlorine ions and sodium ions are preferred. These epoxy resins can be used individually or in mixture of 2 or more types. Besides these epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, heterocyclic epoxy resins, hydrogenated bisphenol A type epoxy resins, aliphatic epoxy resins, aromatic, aliphatic or alicyclic An epoxy resin obtained by a reaction between a carboxylic acid of the formula and epichlorohydrin, a spiro ring-containing epoxy resin, or the like can be appropriately used in combination.
[0044]
Further, the curing agent used as the component (b) is preferably an acid anhydride type, and examples thereof include phthalic anhydride type derivatives such as methylhexahydrophthalic acid and methyltetrahydrophthalic acid, and methylnadic acid anhydride. These can be used alone or in admixture of two or more.
[0045]
The spherical silica particle aggregate of the present invention used as the component (c) is as described above. The content of the component (c) is selected in the range of 10 to 90% by weight, preferably 30 to 90% by weight, and more preferably 50 to 90% by weight.
[0046]
In the resin composition, various other additives such as a colorant, a stress relaxation agent, an antifoaming agent, a leveling agent, a coupling agent, and a flame retardant are added as necessary as long as the object of the present invention is not impaired. Further, a curing accelerator or the like can be appropriately blended.
[0047]
The resin composition of the present invention can be produced by thoroughly mixing the above-described components according to a conventional method, then performing a kneading treatment with, for example, a three roll, and then degassing under reduced pressure. The resin composition thus obtained is suitable as a semiconductor resin sealing material, particularly for flip chip sealing.
[0048]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
[0049]
Example 1
Polyoxyethylene alkyl aryl ether “Neugen EA-157 (HLB15)” which is a nonionic surfactant adjusted to various concentrations shown in Table 1 in a 300 ml plastic container set in a constant temperature bath at 30 ° C. (Made by Daiichi Kogyo Seiyaku Co., Ltd.) 20 g of methyltrimethoxysilane (MTMS) was added to 200 ml of an ion exchange aqueous solution and stirred with a magnetic stirrer until a transparent homogeneous solution was obtained. Next, 1 mol / liter ammonia water was added to this so that the concentration of the ammonia water with respect to the ion exchange water was 1.0 ml / liter, and the mixture was stirred at about 50 rpm. After the particles precipitated and grew and the solution became cloudy, the particle growth was observed with an optical microscope, and about 1.5 hours after the growth stopped, 2 ml of 25 wt% aqueous ammonia was added and aged overnight. .
[0050]
After completion of the reaction, the stirring was stopped and the particles and the solvent were separated by a centrifuge. Then, the supernatant was discarded, and methanol was further added to disperse the particles again. Again, particle separation by a centrifuge and particle washing by adding methanol were repeated three times. Finally, methanol was removed, and drying treatment was performed in an oven at 120 ° C. for 1 hour to obtain polymethylsilsesquioxane (PMSO) particles.
[0051]
The resulting dried particles are water-repellent and white powder having excellent fluidity. A solution in which this is dispersed in an aqueous surfactant solution is prepared, and 50000 particles are measured with a Coulter counter, and the average particle size is measured. And its CV value was measured. As a result of measuring the particle size distribution of the obtained particles with the entire peak as the measurement range, as shown in Table 1, the CV value varies depending on the surfactant concentration, and in Experiment Nos. 3 to 7, the CV value was 10%. PMSO particles having the above broad peaks were obtained.
Further, as a result of observation with a scanning electron microscope (SEM) at the same time, the particles were spherical and were monodisperse particles having no coalescence and aggregation. Also, there were no fine particles of less than 0.3 μm and coarse particles of 10 μm or more.
[0052]
[Table 1]
[0053]
Example 2
The concentration of the nonionic surfactant “Neugen EA-157” is set as shown in Table 2, and 1 mol / liter of ammonia water is adjusted so that the concentration of the ammonia water with respect to ion-exchanged water is 2.5 ml / liter. Except for the addition, the same operation as in Example 1 was performed to obtain dried PMSO particles.
The average particle size and CV value were measured with a Coulter counter in the same manner as in Example 1. As a result, as shown in Table 2, the CV value varied depending on the surfactant concentration. PMSO particles having a broad peak of at least% were obtained.
Further, as a result of observation with a scanning electron microscope (SEM) at the same time, the particles were spherical and were monodisperse particles having no coalescence and aggregation. Also, there were no fine particles less than 0.3 μm or coarse particles exceeding 10 μm.
[0054]
[Table 2]
[0055]
Example 3
Nonionic surfactant “Neugen EA-157” concentration of 1 × 10^-3PMSO particles after drying were obtained in the same manner as in Example 1 except that the concentration was 1% by weight and the concentration of 1 mol / liter ammonia water relative to ion-exchanged water was as shown in Table 3.
As in Example 1, the average particle size and CV value were measured with a Coulter counter. As shown in Table 3, broad particles having a particle size distribution with a CV value of 10% or more were obtained.
Further, as a result of observation with a scanning electron microscope (SEM) at the same time, the particles were spherical and were monodisperse particles having no coalescence and aggregation. Also, there were no fine particles less than 0.3 μm or coarse particles exceeding 10 μm.
[0056]
[Table 3]
[0057]
Example 4
1 × 10 in a 5000 ml separable flask set in a constant temperature bath at 30 ° C.^-3500 g of MTMS was added to 5000 ml of an EA-157 ion exchange aqueous solution adjusted to a concentration by weight, and stirred with a stirring blade until a transparent uniform solution was obtained. Next, 1 mol / liter ammonia water was added to this so that the concentration of the ammonia water with respect to the ion exchange water was 1.0 ml / liter, and the mixture was stirred at 30 rpm. After particles precipitated and grew and the solution became cloudy, particle growth was observed with an optical microscope. About 1.5 hours after the growth stopped, 10 ml of 25 wt% aqueous ammonia was added and aged overnight.
[0058]
After completion of the reaction, the stirring was stopped and the particles and the solvent were separated by a centrifuge. Then, the supernatant was discarded, and methanol was further added to disperse the particles again. Again, particle separation by a centrifuge and particle washing by adding methanol were repeated three times. Finally, the methanol was removed, and dried in an oven at 120 ° C. for 1 hour to obtain PMSO particles.
[0059]
The obtained dried white powder was measured 50000 pieces with a Coulter counter, and the average particle size and its CV value were measured. The particle size distribution of the obtained particles was measured using the entire peak as a measurement range. As a result, PMSO particles having a broad peak with an average particle size of 1.64 μm and a CV value of 13.1% were obtained.
[0060]
Further, as a result of observation with a scanning electron microscope (SEM) at the same time, the particles were spherical and were monodisperse particles having no coalescence and aggregation. Also, there were no fine particles less than 0.3 μm or coarse particles exceeding 10 μm.
The obtained white powder was once held at 400 ° C. for 24 hours while feeding air at a flow rate of 4 ml / min, and then calcined at 800 ° C. for 9 hours.
[0061]
The powder obtained after firing was a white powder which was easily dispersed in water, had excellent fluidity and had no agglomerates. As a result of measuring 50,000 particles with a Coulter counter, PMSO particles having a broad peak with an average particle diameter of 1.37 μm and a CV value of 13.4% were obtained. At the same time, as a result of observation with a scanning electron microscope (SEM), it was a monodisperse particle that was spherical and had no coalescence or aggregation. Also, there were no fine particles less than 0.3 μm or coarse particles exceeding 10 μm.
[0062]
As a result of measuring the particles after firing by IR, it was found that methyl groups as organic components were completely decomposed. Further, as a result of investigating the contents of uranium and thorium by ICP-MS, it was found that uranium was 0.1 ppb and thorium was 0.04 ppb, each of which was 0.1 ppb or less and highly pure. As a result of measurement by flameless atomic absorption, Fe was 0.3 ppm, K was 0.04 ppm, and Ca was 0.07 ppm. After extraction of ionic components, measurement was performed by ion chromatography analysis. Result, Cl^-It was found that the ions were below the detection limit of 1 ppm and had high purity.
Next, the water absorption at the time of hold | maintaining for 48 hours in 30 degreeC and RH90% atmosphere was 0.54%.
FIG. 1 shows a scanning electron micrograph of fired PMSO particles, and FIG. 2 shows a Coulter chart of fired PMSO particles.
[0063]
Comparative Example 1
Except that the concentration of the nonionic surfactant “Neugen EA-157” was as shown in Table 4, the same operation as in Example 1 was performed to obtain PMSO particles after drying.
The average particle size and CV value were measured using a Coulter counter in the same manner as in Example 1. As shown in Table 4, PMSO particles having a small CV value and a very uniform particle size were obtained.
[0064]
[Table 4]
[0065]
In FIG. 3, the scanning electron micrograph figure of the dry PMSO particle | grains obtained by experiment No. 1 of the comparative example 1 is shown.
[0066]
Comparative Example 2
Except for changing the concentration of 1 mol / liter ammonia water as shown in Table 5, the same operation as in Example 1 was performed to obtain dried PMSO particles. However, in Experiment No. 4, particles did not precipitate and PMSO particles were not obtained.
The average particle diameter and CV value were measured with a Coulter counter in the same manner as in Example 1. As a result, PMSO particles having a broad peak with a large CV value as shown in Table 5 were obtained.
On the other hand, as a result of observing with a scanning electron microscope (SEM) at the same time, there were particles that were true spherical, coalesced and agglomerated, and agglomerates exceeding 10 μm also existed.
[0067]
[Table 5]
[0068]
FIG. 4 shows a scanning electron micrograph of the dried PMSO particles obtained in Experiment No. 7 of Comparative Example 2.
In Experiments Nos. 17, 20, 23, and 25 of Example 3 and Experiments Nos. 5 to 7 of Comparative Example 2, the number of coalesced particles was measured by observing SEM photographs after washing the particles with a centrifuge. And the following formula
Adhesion rate (%) = (number of coalesced particles / measured total number of particles) × 100
Thus, the coalescence rate was calculated. The results are shown in Table 6.
[0069]
[Table 6]
[0070]
【The invention's effect】
The spherical silica particle aggregate of the present invention is composed of non-bonded and non-aggregating spherical silica particles, has a wide particle size distribution range, and is suitable for semiconductor filler silica fillers, especially flip chip underfill materials. It is suitable as a silica filler.
Moreover, according to the method of the present invention, the true spherical silica particle aggregate can be efficiently produced.
[Brief description of the drawings]
1 is a scanning electron micrograph of fired PMSO particles obtained in Example 4. FIG.
2 is a Coulter chart of calcined PMSO particles obtained in Example 4. FIG.
3 is a scanning electron micrograph of dry PMSO particles obtained in Experiment No. 1 of Comparative Example 1. FIG.
4 is a scanning electron micrograph of dry PMSO particles obtained in Experiment No. 7 of Comparative Example 2. FIG.

Claims (3)

(A) An aqueous solution containing 1 × 10 ⁻² to 1 × 10 ⁻⁴ wt% of a nonionic surfactant or an anionic surfactant is added to the general formula (I)
R ¹ nSi (OR ² ) _4-n (I)
(In the formula, R ¹ is a non-hydrolyzable group having 1 to 20 carbon atoms, a (meth) acryloyloxy group or an epoxy group having 1 to 20 carbon atoms, or 2 to 20 carbon atoms). An alkenyl group, an aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, R ² is an alkyl group having 1 to 6 carbon atoms, n is an integer of 1 to 3, and there are a plurality of R ¹ each R ¹ may be different from one another identical, if OR ² there are a plurality, each OR ² may be different even identical to each other.)
After adding and dissolving the organosilicon compound and / or its partially hydrolyzed condensate, ammonia water is added so that the ammonia concentration becomes 0.25 × 10 ⁻³ to 100 × 10 ⁻³ mol / liter. The organosilicon compound and / or the partially hydrolyzed condensate thereof are added and hydrolyzed and condensed, and then the precipitated particles are grown and then ripened by adding ammonia and / or amine. Manufacturing process,
(B) a step of washing the particles obtained in the step (A),
(C) a step of drying the particles obtained in the step (B), and (D) a firing treatment of the particles obtained in the step (C) at a temperature of 350 to 1100 ° C. in the presence of oxygen. Process,
The manufacturing method of the spherical silica particle aggregate | assembly characterized by including this. The method according to claim 1 , wherein in step (D), firing is performed at a temperature of 350 to 1100 ° C. in air. The method according to claim 1 or 2 , wherein in the step (D), a baking treatment is performed at a temperature at which the organic component is completely decomposed and removed .