JPH0360421A - Production of spherical silica glass - Google Patents

Abstract

PURPOSE:To easily obtain spherical silica glass having uniform particle diameter by passing and dispersing sol obtained by hydrolysis of the silicic acid ester soln. of a raw material through a nozzle hole and dispersing it in a dispersion medium, separating and burning the produced gel. CONSTITUTION:Silicic acid ester such as methyl silicate and ethyl silicate is hydrolyzed by mixing and agitating this silicic acid ester, water and a catalyst e.g. such as aqueous ammonia. In the mixing ratio in this case, water is regulated to about 4-10 moles for 1 mole silicic acid ester. Further when aqueous ammonia is utilized for the catalyst, it is regulated to about 1X10<-4>-1X10<-3> mole for 1 mole silicic acid ester. In the case of dispersing sol obtained by hydrolysis into a dispersion medium such as butanol, this sol is passed and dispensed through a nozzle hole. After the obtained gel is sufficiently washed by the dispersion medium and dried, it is burned in the air e.g. at 1700 deg.C. Thereby spherical silica glass having uniform particle diameter is easily obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing spherical silica glass used as a filler for, for example, a sealing material for semiconductor elements. More specifically, the present invention relates to a method for producing spherical silica glass using a sol-gel method.

(Prior art) Currently, fillers for semiconductor device encapsulants have electrical insulating properties,
Silica glass powder is used which has material properties such as low coefficient of thermal expansion, high thermal conductivity, high strength and low dielectric constant.

Additionally, with the recent increase in the memory capacity of semiconductor devices, in addition to the above properties, the filler also needs to be highly pure and free of soluble impurities that corrode the M lead frame and α-ray emitting impurities that cause memory soft errors. Preventing damage to the lead frame and increasing filler filling rateε,
In order to improve the fluidity, that is, the moldability, of the sealant, silica glass is required to have a spherical shape and a wide particle size distribution.

Conventionally, the manufacturing method for this type of spherical silica glass is as follows:
There is a known method of producing spherical silica glass by crushing natural silica stone and crystal, and remelting and spheroidizing it. Hydrolyze in a 0□-H2 flame to create glass powder, sinter and crush it at a temperature of 1800 to 2000°C, and heat it again in a 02-H2 flame to make it spherical to produce spherical silica glass. The so-called gas phase method has been adopted.

However, this vapor phase method is 5ICJ! , hydrolysis, sintering, and remelting of the powder at a temperature of 1800-2000℃.
．． - Since the process is carried out in an H2 flame, a large amount of thermal energy is required, so there is a problem in that the proportion of energy costs in the manufacturing cost is extremely high, making the product expensive.

Therefore, assuming that the above-mentioned problems do not exist, JP-A-58-178
As disclosed in Publication No. 1H, a mixed solution of esterone silicate, water, and alcohol is dispersed and suspended in a liquid that is substantially incompatible with these to form a powdery gel,
The so-called sol-gel method, in which the resulting powdery gel is separated and fired to form spherical silica glass, is attracting attention.

However, the sol-gel method is a method of obtaining a powder-like gel by dispersing a mixed solution of silicate ester, water, and alcohol in a liquid that is substantially incompatible with the solution; There is a problem in that the shape of the gel is crushed into angular shapes, or the gel particles aggregate with each other, making it impossible to obtain a spherical gel.

Therefore, the present applicant previously proposed in Japanese Patent Application No. 1-43940 that a sol obtained by hydrolyzing a silicate ester raw material solution was dispersed in a dispersion medium to produce a gel, and the resulting gel was separated. In a method of manufacturing spherical silica glass by a sol-gel method involving firing, a method of manufacturing spherical silica glass using butanol as the dispersion medium was proposed.

(Problem to be solved by the invention) However, since the method described above is a method in which a sol is poured into a dispersion medium and dispersed while stirring the dispersion medium to obtain a spherical gel, the resulting gel is not a spherical gel. However, it is difficult to separate the spherical gel from the amorphous gel, and it is also difficult to control the particle size of the powdery gel that is produced. The problem is that you can't get it.

The present invention solves the above-mentioned problems and provides a method for manufacturing spherical silica glass using a sol-gel method, which can disperse the gel well without breaking or aggregating it, and can produce a spherical gel with a uniform particle size. The purpose is to provide.

(Means for Solving the Problems) As a result of intensive studies to achieve the above object, the present inventors found that
In the sol-gel method, it has been found that the particle size of the gel can be uniformly controlled by dispensing the gel using a nozzle when dispersing the sol in a dispersion medium.

The present invention has been made based on the above findings, and the method for producing spherical silica glass comprises: dispersing a sol obtained by hydrolyzing a silicate ester raw material solution in a dispersion medium to generate a gel; A sol that separates and bakes the resulting gel.
The method for producing spherical silica glass by a gel method is characterized in that when the sol is dispersed in a dispersion medium, the sol is dispensed through a nozzle hole.

Examples of the silicic acid ester used in the present invention include methyl silicate, ethyl silicate, and propyl silicate.

In addition, for hydrolysis of silicate ester, silicate ester, water, and a catalyst such as aqueous ammonia may be mixed and suspended by stirring, and the mixing ratio is 4 to 10 mol of water to 1 mol of silicate ester. If aqueous ammonia is used as a catalyst, lX10-' to 1 mole of silicate ester.
The amount is approximately 1×10 −3 mol.

Further, examples of the dispersion medium include butanol, hexanol, and the like. The amount of dispersion medium is generally about 1 to 3 times the volume of the silicate ester raw material solution.

(Example) Next, examples of the method of the present invention will be described.

FIGS. 1 and 2 show one embodiment of a nozzle used to carry out the method of the present invention, and in the figures, 1 indicates a nozzle. The nozzle 1 has a cylindrical main body 2 with an inner diameter of about 80 mm, and a diameter of 0.5 mm inserted removably below the main body 2.
The nozzle hole 3 is about 4 inφ, and the hole interval A is 1 to 4 in.
A nozzle plate 4 with a plurality of holes drilled at a size of about 20 times, an M5 removably fitted above the main body 2, and a supply device that supplies compressed air into the main body 2 via a control valve 6 on the side wall of the main body 2. The main body 2 is filled with sol S, and the air pressure is 0.5~
Compressed air of about 2 kg/c was supplied into the main body 2 through the supply pipe 7, and the gel S was dispensed into the dispersion medium through the nozzle hole 3.

A specific example of a method for manufacturing spherical silica glass using the above nozzle will be described together with a comparative example ε.

Example 1 First, 5 moles of distilled water and 5×IQ-' moles of ammonia water with a purity of 99.5% were added to 1 mole of distilled methyl silicate in a 500 cc beaker, and the mixture was stirred using a magnetic stirrer. The mixture was vigorously stirred for 3 minutes at a temperature of 25° C. to prepare about 250 cc of sol with a viscosity of 0.5 poise (Tokyo Keiki stationary viscometer).

Next, 32 nozzle holes 3 with a diameter of 3 mm (hole spacing A of 2.5
After filling 250 cc of the sol into the main body 2 of the nozzle 1 equipped with the nozzle plate 4, the sol is
100 kg/cd prepared separately from nozzle hole 3
Dispense into a butanol dispersion medium with a volume ratio twice that of the above sol amount into a 0cc beaker, and stir with a magnetic stirrer at a temperature of 25°C and a rotation speed of 3000 rpm.
Stir vigorously for 0 minutes to form a gel.

Immediately after stirring, the gel was allowed to stand still, and the average particle size and particle size (0°1 to 200 jIll) distribution were measured.
As a result, the average particle diameter was 35.0 μm, and the particle size distribution n was 1.97. Further, the produced gel was observed with an optical microscope (magnification: 50 times), and the observation results are shown in FIG.

In addition, the average particle size and particle size distribution of the gel can be measured using a laser diffraction particle size distribution analyzer. , A-500 (manufactured by Horiba)
This was done using

In addition, the particle size distribution n (a constant indicating the width of the distribution) is the cumulative % on the sieve.
Rosln-Ramler formula where R is rR=exp
(Uri/D36.8) "J was determined by the following formula.

n =IHJn R/71 ('D'l) /D36.
8) In the formula, R is the cumulative % on the sieve, exp is the base of the natural logarithm, and T
f r) HaR% (7) (!:8 (ri particle size, D
36. g represents the particle size when R power is 1.8%. Therefore, the smaller the value of n, the wider the particle size distribution, and the larger the value of n, the narrower the particle size distribution.

Next, the generated gel dispersion was separated into gel and filtrate by decantation, and the gel was washed twice with 500 cc of 95% pure butanol and once with 300 cc of distilled water, and then washed in an atmosphere at a temperature of 40°C and a humidity of 95%. It was dried in a constant temperature and humidity chamber for 24 hours.

The dried granular gel was heated in an electric furnace to a temperature of 800°C at a heating rate of 100°C/1 hour, fired at this temperature for 2 hours, and then further fired in a suspended state in air at a temperature of 1700°C. Spherical silica glass was obtained.

Comparative Example 1 Spherical silica glass was produced in the same manner as in Example 1 except that the sol was directly dispersed in the dispersion medium without using a nozzle.

Further, in the same manner as in Example 1, the average particle size and particle size distribution of the gel produced by allowing it to stand immediately after stirring were measured, and the average particle size was 37.9 pm, and the particle size distribution n was 1. It was 74. Further, the produced gel was observed with an optical microscope (magnification: 50 times), and the observation results are shown in FIG.

As is clear from FIGS. 4 and 5, in the method of Example 1 of the present invention, the gel was monodispersed as spherical particles with a particle size of about 2 to 200 μm. On the other hand, in the method of Comparative Example 1, in which the sol was directly dispersed into the dispersion medium without using a nozzle, the gel was well dispersed, but irregularly shaped fibrous gel was formed within the spherical gel. . This fibrous gel is formed by the flow of the dispersion medium while the sol is being fragmented by stirring.)
This is thought to be because the fibers were stretched and gelled.

Example 2 A spray nozzle as shown in the third figure was used instead of the nozzle of Example 1, and the air pressure supplied to the nozzle was 3 kg/
A spherical silica glass was prepared in the same manner as in Example 1, except for the difference in direction d.

Further, in the same manner as in Example 1, the average particle size and particle size distribution of the gel produced by allowing it to stand immediately after stirring were measured, and the average particle size was 15.3 μm, and the particle size distribution n was 1. It was 87. Further, when the produced gel was observed with an optical microscope, it was found to be monodispersed as spherical particles with a particle size of about 1 to 50 II m.

When dispersing the sol in a dispersion medium in this way, if the nozzle used is a spray nozzle, the average particle size of the resulting gel can be reduced.

The spray nozzle shown in the third figure used in this example will be explained.

The spray nozzle 11 includes a sol nozzle 13 having a hole 12 with a diameter of about 1 to 3 φ bored at its tip, an air nozzle 14 surrounding the outside of the sol nozzle t3, and a supply pipe that supplies compressed air to the air nozzle 14. 15, air pressure 1-5 kg
/ CD compressed air is supplied to the air nozzle 14 through the pipe 1
5, the sol S was atomized by the jet energy of compressed air from the air nozzle 14, and was sprayed from the tip of the spray nozzle 11.

Example 3.4.5.6 Spherical silica glass was produced in the same manner as in Example 1 except that the amount of water added to 1 mole of methyl silicate was 4 mol, 6 mol, 7.5 mol, and 10 mol. did.

In addition, in the same manner as in Example 1, the average particle size and particle size distribution of the gel produced by allowing it to stand immediately after stirring were measured. The results are shown in Table 1 together with the results of Example 1.

Comparative Example 2.3 Spherical silica glass was prepared in the same manner as in Example 1 except that the amount of water added was 3 mol and 15 mol per mol of methyl silicate.

In addition, in the same manner as in Example 1, the average particle size and particle size distribution of the -C-generated gel was measured by allowing it to stand immediately after stirring. The results are shown in Table 1.

As is clear from Table 1, the methods of Examples 3 to 6, in which the amount of water added to 1 mole of methyl silicate was 4 to 10 moles, were able to disperse spherical gels in the dispersion medium. Also,
The amount of water added to 1 mole of methyl silicate is from 4 moles to 10 moles.
The average particle size of the gel obtained tends to remain almost constant even when the amount of water is increased by molar, and as the amount of water added increases, the particle size distribution constant decreases, that is, the particle size distribution tends to widen. Do you get it.

On the other hand, in the method of Comparative Example 2 in which the amount of water added was 3 moles, the reaction rate was fast, and the viscosity of the sol rapidly increased, gelation occurred, and the sol could not be dispersed in the dispersion medium.

In addition, in the method of Comparative Example 3 in which the amount of water added was 15 mol, the reaction rate was slow, the viscosity of the sol increased slowly, and only a gel with broken particles was produced.

Therefore, in order to produce a uniform spherical gel, the amount of water added to methyl silicate is 4 mols of water per 1 mole of methyl silicate.
The amount may be about 10 moles.

Example 7.8.9 The amount of ammonia water added per 1 mole of methyl silicate was 2
X 10-'mol, 3X 1(1-'mol/Iz, 3X
A spherical silica glass was prepared in the same manner as in Example 1 except that the amount was 1 (1-' mol).

In addition, in the same manner as in Example 1, the average particle size and particle size distribution of the gel produced by allowing it to stand immediately after stirring were measured. The results are shown in Table 2 together with the results of Example 1.

Comparative Example 4.5 The amount of ammonia water added to 1 mole of methyl silicate was 5
Spherical silica glass was prepared in the same manner as in Example 1 except that the amounts were X 10-' mol and 3 X 10-3 mol.

In addition, in the same manner as in Example 1, the average particle size and particle size distribution of the gel produced by allowing it to stand immediately after stirring were measured. The results are shown in Table 2.

As is clear from Table 2, the methods of Examples 7 to 9, in which the amount of ammonia water added per mole of methyl silicate was IX], 0-' to lX1O-' mole, dispersed spherical gel in the dispersion medium I was able to do it.

Furthermore, as the amount of ammonia water added per mole of methyl silicate increases from lXl0-' mole to lXl0-3 mole, the average particle size of the gel obtained tends to increase, and the particle size distribution constant decreases. That is, it was found that the particle size distribution tended to become broader.

On the other hand, in the method of Comparative Example 4 in which the amount of ammonia water added was 5×1.0-' moles, the reaction rate was fast and the gel was not dispersed but in an aggregated state. Further, in the method of Comparative Example 5 in which the amount of ammonia water added was IXIQ-3 moles, the reaction rate was slow and only a gel with broken particles was produced.

Therefore, in order to produce a uniform spherical gel, the amount of ammonia water added to methyl silicate may be about 1 x 10-4 to I x 10-3 mol per 1 mol of methyl silicate.

Example 10511S12, i3.14 The viscosity of the sol obtained by adding water and aqueous ammonia to methyl silicate was 1.0 voids, 3.2 voids, and 5.7 po.r.
A spherical silica glass was prepared in the same manner as in Example 1 except that the pores were sized, 9.0 voids, and 10.0 voids.

In addition, in the same manner as in Example 1, the average particle size and particle size distribution of the gel produced by allowing it to stand immediately after stirring were measured. The results are shown in Table 3 together with the results of Example 1.

Comparative Example 6 A spherical silica glass was prepared in the same manner as in Example 1 except that the viscosity of the sol obtained by adding water and aqueous ammonia to methyl silicate was set to 20 voids.

In addition, in the same manner as in Example eAi i, the average particle size and particle size distribution of the gel produced by allowing it to stand immediately after stirring were measured. The results are shown in Table 3.

As is clear from Table 3, the viscosity of the sol obtained by adding water and aqueous ammonia to methyl silicate was C1.5 to C10.
The methods of Examples 10 to 14 with zero voids were able to disperse spherical gels in the dispersion medium. Furthermore, as the viscosity of the sol obtained by adding water and aqueous ammonia to methyl silicate increases from 0.5 to 10.0, the average particle size of the gel obtained tends to increase. It was found that even if the viscosity of the sol increases, the particle size distribution constant tends to remain almost unchanged.

On the other hand, in the method of Comparative Example 6 in which the viscosity of the sol obtained by adding water and aqueous ammonia to methyl silicate was 20 voids, the sol was gelled before being dispersed in the dispersion medium, and the gel was several hundred It was in the form of n~several chunks.

Therefore, in order to produce a uniform spherical gel, the viscosity of the sol obtained by adding water and aqueous ammonia to methyl silicate should be about 0.5 to 10.0 voids.

Example 15.16.17, Top 8 The diameter of the nozzle hole 3 of the nozzle plate 4 is 0.5111 Liuφ (hole spacing A is 20 times), the hole diameter is 1 Shidoφ (hole spacing A is 10 times),
The hole diameter is 2 mmφ (hole spacing A is 4 times), and the hole diameter is 4 mmφ (
A spherical silica glass was produced in the same manner as in Example 1, except that nozzle 1 was used with the hole spacing A being 1.5 times larger.

In addition, in the same manner as in Example 1, the average particle size and particle size distribution of the gel produced by allowing it to stand immediately after stirring were measured. The results are shown in Table 4 together with the results of Example 1.

Comparative Example 7 The diameter of the hole 3 of the nozzle plate 4 is 511! lφ (hole spacing A is 1x)
A spherical silica glass was produced in the same manner as in Example 1 except that the nozzle 1 was used.

In addition, in the same manner as in Example 1, the average particle size and particle size distribution of the gel produced by allowing it to stand immediately after stirring were measured. The results are shown in Table 4.

As is clear from Table 4, the methods of Examples 15 to 18 using the nozzle 1 in which the diameter of the nozzle hole 3 of the nozzle plate 4 is 0.5 m + mφ to 4 mmφ are capable of dispersing spherical gel in the dispersion medium. done.

On the other hand, in the method of Comparative Example 7 using the nozzle 1 in which the nozzle hole 3 diameter of the nozzle plate 4 was 4 mm, gel dispersion was good, but irregularly shaped fibrous gel was found in the spherical gel. was being generated.

Therefore, in order to generate uniform spherical gel, it is necessary to use the nozzle plate 4.
The diameter of the nozzle holes 3 may be approximately 0.5 to 4 mm, and the hole interval A may be approximately 1.5 to 20 times the hole diameter.

Example 19.29.21.22 The rotation speed when dispersing the sol in a dispersion medium and stirring it with a magnetic stirrer was 290 Orpm and 3300 rpm.
(In both cases, the stirring time is 80 minutes), or the stirring time is 10 minutes or 180 minutes (in both cases, the stirring speed is 300 minutes).
Spherical silica glass was produced in the same manner as in Example 1 except that the rotation speed was 0 rpm).

In addition, in the same manner as in Example 1, the average particle size and particle size distribution of the gel produced by allowing it to stand immediately after stirring were measured. The results are shown in Table 5 together with the results of Example 1.

As is clear from Table 5, the methods of Examples 18 to 2t, in which the rotational speed during stirring with a magnetic stirrer was 2900 rpm to 3300 rpm, were able to disperse spherical gels in the dispersion medium.

However, as the stirring time becomes longer, the stirring becomes excessive and the gel is more likely to be destroyed.
Preferably up to 0 minutes.

Example 23 When dispersing the sol in a dispersion medium and stirring it with a magnetic stirrer, first
200, manufactured by Yamato Scientific Co., Ltd.) at a frequency of 45K.
After stirring at Hz for 10 minutes, spherical silica glass was produced in the same manner as in Example 1 except that the mixture was stirred for 50 minutes at a rotational speed of 3000 rpm using a magnetic stirrer.

Further, in the same manner as in Example 1, the average particle size and particle size distribution of the gel produced by stirring and then standing were measured, and the average particle size was 24.3 gIn, and the particle size distribution n was 2. It was 06.

Example 24 When dispersing the sol in a dispersion medium and stirring it with a magnetic stirrer, first use a mixer (trade name MX-915C, manufactured by Matsushita Electric Industrial Co., Ltd.) at a rotation speed of 5000 rpm + 1.
Example 1 except that after stirring for 0 minutes, stirring was performed for 50 minutes at a rotation speed of 300 rpm using a magnetic stirrer.
Spherical silica glass was prepared in the same manner as above.

Further, in the same manner as in Example 1, the average particle size and particle size distribution of the gel produced by allowing it to stand immediately after stirring were measured, and the average particle size was 18.511 m, and the particle size distribution n was 2.19. there were.

When different stirring methods are used in combination when dispersing the sol in a dispersion medium and stirring it as in the methods of Examples 23 and 24, the average particle size of the resulting gel can be reduced.

(Effects of the Invention) As described above, according to the method for producing spherical silica glass of the present invention, when dispensing the sol into the dispersion medium, the sol is passed through the nozzle hole. The resulting gel is dispersed in the dispersion medium without agglomerating or being destroyed, and gels with the desired particle size can be produced uniformly without the presence of irregularly shaped gels. It has effects such as being able to easily manufacture silica glass.

[Brief explanation of drawings]

1 and 2 show one embodiment of a nozzle used in the method of the present invention, FIG. 1 is a cutaway view thereof, FIG. 2 is a plan view of a nozzle plate, and FIG. 3 is a nozzle used in the method of the present invention. Cutting section view of another embodiment of , No. 1 patent applicant Nippon Inuki Co., Ltd.

Claims (1)

[Claims] In the method for producing spherical silica glass by the sol-gel method, the sol obtained by hydrolyzing a silicate ester raw material solution is dispersed in a dispersion medium to form a gel, and the resulting gel is separated and fired. A method for producing spherical silica glass, which comprises dispensing the sol through a nozzle hole when dispersing the sol in a dispersion medium.