JPH01185373A - Silica and its production - Google Patents

Abstract

PURPOSE:To obtain silica effective in improving moldability when used as a filler for a semiconductor sealing resin, by mixing particulate silica with a microparticulate metal oxide having a specified primary particle diameter in a wet state and drying the mixture. CONSTITUTION:1-5wt.% microparticulate metal oxide of a primary particle diameter <=0.1mu is mixed with 1-5wt.% particulate silica of a particle diameter of 1-150mu in a wet state, and the mixture is dried to obtain the purpose silica. As said particulate silica, well-known semiconductor sealing silica, for example, a product prepared by grinding low-uranium rock crystal or fused quartz obtained by a melting process or a gas-phase synthetic process to a specified particle size can be used as such. Said metal oxide is exemplified by silica, alumina or titania, and amorphous silica is usually desirable.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to silica particularly suitable for semiconductor encapsulant,
Specifically, the present invention relates to silica which is useful as a filler material for resins that are semiconductor encapsulating materials, and whose purpose is to improve the moldability of the encapsulating resins.

[Prior art]

Conventionally, in order to seal semiconductor elements such as diodes, transistors, and C9LSIs, epoxy resins,
A silicone resin or the like is used, and as a filler for the resin, for example, granular silica having a particle size of generally 1 to 150 μm is used. Such filler silica used for semiconductor encapsulation (hereinafter also simply referred to as silica for semiconductor encapsulation materials) is generally made of crystalline quartz, fused silica, etc., which have the features of high thermal conductivity and low thermal expansion. In particular, granular materials obtained by crushing silica obtained by melting silica sand at high temperatures are often used.

Furthermore, in recent years, as semiconductors have become more highly integrated, the problem of soft errors caused by X-rays has arisen, so there is a particular desire for high-purity silica for semiconductor encapsulants with a small uranium-containing layer.

Therefore, in order to obtain such high-purity silica for semiconductor encapsulant, for example, low uranium-containing quartz is used.

A method of pulverizing low-uranium-containing fused silica synthesized by a wet or dry method using high-purity SiO/4, S-technique (OR) 4, etc. as a raw material, or a method of pulverizing fine powder silica obtained by the above-mentioned dry method using a flame. A method has been proposed in which the material is melted (sintered) at a high temperature to form a spheroid.

[Problem that the invention seeks to solve]

However, when the silica for semiconductor encapsulant obtained by the conventional method as described above is added to a resin and used for molding, the resin tends to flow out of the mold, causing the problem of causing so-called paris. was there. Further, when the usual specifications are applied to improve the occurrence of flakes during molding of such a resin, the flowability of the resin deteriorates, resulting in a circulation.

Therefore, in order to improve the moldability of conventional silica for semiconductor encapsulant materials, various measures have been taken to adjust the particle size distribution of colored silica, but there are still aspects that are not fully satisfied. .

[Means for solving problems]

The inventors of the present invention have conducted extensive research in order to solve the above-mentioned problems, especially as silica for semiconductor sealing materials.

As a result, we found that by kneading fine powder silica with a primary particle size of 0.1 μm or less into conventional silica for semiconductor encapsulant in a wet state, the moldability of the resulting silica-filled resin was significantly improved. , which led to the proposal of the present invention. That is, according to the present invention, the primary particle diameter is 0.1
The specific surface area of finely divided metal oxide particles with a particle size of 1 to 1. om''7y is provided.Furthermore, fixation in the present invention means that the primary particle diameter is 0.1 μm or less from the particle surface of the silica by at least ultrasonic vibration (cleaning). ) generally has a particle size of 1 to 150 μm, particularly 5 to 10 μm.
Particulate silica having a diameter of 0 μm is preferable, and for example, conventionally known silica for semiconductor sealing materials can be used as is. As described above, such conventionally known silica for semiconductor encapsulant is produced by pulverizing fused quartz obtained from low uranium-containing crystal, electric furnace melting, flame melting, or vapor phase synthesis to a predetermined particle size. It can also be obtained by a method such as a method of melting amorphous silica or precipitated V silica obtained from quartz silica, silicon halide, or sodium silicate as raw materials in a flame to form spherules to a predetermined particle size (thermal spraying method). I can do it.

In particular, the particle size obtained by the latter thermal spraying method is generally 1 to 1.
Spherical silica having a particle diameter of 50 μm has a uniform particle size, and due to its shape and surface characteristics due to its spherical shape, when it is filled into a resin as silica for semiconductor encapsulant as described above, it often generates particles. Therefore, for such conventional spherical silica for semiconductor encapsulant, the method of the present invention in which finely divided silica having a primary particle diameter of 01 μm or less is fixed to the particle surface of the silica is extremely effective.

On the other hand, in the present invention, the fine powder metal oxide to be fixed to the surface of silica particles is not particularly limited as long as the large particle size is 01 μm or less, and examples include silica, alumina,
Examples include titania, but non-crystalline silica is generally preferred. Such fine powder silica having a primary particle diameter of 0.01 μm or less, generally 0.05 to 0005 μm, can be produced by, for example, a dry process in which vaporized silicon tetrachloride is hydrolyzed with hydrogen in the gas phase at high temperatures.

A method of heating and reducing silica sand with coke in an arc furnace to oxidize the SIO vapor generated in the air, a method of producing perilla by the thermal spraying method described above, for example, a method of heating quartz or glass and evaporating it from the surface; It can be obtained by a method in which 5i02 gas is condensed to produce a by-product, or by a wet method in which it is reacted with a mineral acid such as sodium silicate in an aqueous solution.

The silica of the present invention generally has a particle size of 1 to 1 as described above.
A metal oxide such as finely powdered silica with a primary particle size of 0.1μ or less is fixed to the particle surface of fine silica particles with a diameter of 150μ, especially y~100μ, to obtain a specific surface area of 1td7y or less. It is extremely important to have good moldability by filling the resin with the silica. That is, the silica of the present invention is not simply mixed with the fine powder specific to granular silica and attached to the particle surface;
It is necessary that most of the fine powdered silica be fixed to the surface of the silica particles at least to the extent that it will not be detached from the particle surface by ultrasonic vibration. ′! ! In addition, the silica of the present invention has a specific surface area of 1 tn'/f or more by fixing fine powder silica to exhibit the desired good moldability.

In general, it is necessary to maintain the amount of 1 to 10 + 1"7g. In the case of IHJ, if the amount of finely powdered silica is small and the specific surface area is less than 1m'7y, it is necessary to sufficiently prevent the occurrence of paris during resin molding. In addition, in the case of silica with a specific surface area larger than 1 am'7y, the generation of paris can be suppressed, but this is preferable because it causes deterioration of fluidity. was determined by the N2 adsorption method.

Such silica of the present invention generally has a particle size of 1 to 15
It can be easily produced by mixing 1 to 5% by weight of finely powdered silica having a primary particle diameter of 01 μm or less with 0 μm granular silica in a wet state, and then drying the mixture. To specifically illustrate a typical manufacturing method of the present invention, for example, (1) granular silica having a particle size of 1 to 150 μm as described above is moistened with water to a ratio of 20 to 80%, and the primary particles are After uniformly mixing a predetermined amount of finely powdered silica with a particle diameter of 0.1 μm or less, it is generally dried at a temperature of 110°C or higher, crushed if necessary, and sieved to give a 1.
After uniformly mixing and containing a predetermined amount of fine powder silica with a particle size of 0.1μ or less, 20 to 80 g
i%, preferably 40 to 60% by weight, followed by drying at a temperature of 110°C or higher, crushing if necessary, and sieving; (3) particle size of 1 to 60% by weight; 150μ
m fine powder silica is heated to 110°C using a heating mill, for example.
(4) A method in which a slurry of finely powdered silica with a primary particle size of 0.01 μm or less is blown into the slurry using a spray nozzle while heating to a predetermined ratio, and (4) the primary particle size is 0.1 μm or less. A predetermined amount of finely powdered silica is uniformly mixed in advance, and granular silica with a particle size of 1 to 150 μm is mixed in a heated mixer with an agitator for 100 to 100 μm.
While heating to a temperature of 200° C., water is blown through a spray nozzle, generally from 1 to 5% by weight.

Preferably, a method of adding and drying at a ratio of 1 to 3 ml/t% is employed. The wetting medium used in the production method of the present invention is generally preferably water, but is not limited to this, and any liquid that evaporates and does not remain after heating and drying, such as alcohol, can be used.

[Action and effect]

According to the manufacturing method of the present invention, the base particle size is 1 to 15
The OH groups present on the particle surface of granular silica having a diameter of 0 μm and the OH groups possessed by fine powder silica having a primary particle diameter of 01 μm or less undergo a condensation reaction by drying in a wet state through a medium such as water. As a result, a strong adhesion is achieved. Therefore, the silica of the present invention has (
1) When filled in resin, granular silica with a particle size of 1 to 150 μm and fine powder silica with a primary particle size of 0.1 μm or less are difficult to separate, increasing the adhesive strength between the silica and the resin. (2) In the resin composition, the primary particle size is 0.
(3) Fine powder with a primary particle diameter of 0.1 μ or less, since the fine powder silica having a roughness of 1 μ or less is uniformly infused as a modifier, thereby improving the rheological properties of the resin composition itself. Since the amount of silica is as small as 1 to 5% by weight,
As a resin composition, the increase in viscosity is small, and fluidity does not deteriorate. From the effects of the present invention described above, the fine powdered gold #l oxide with a primary particle size of 0.1 μm or less in the present invention is not limited to silica, but alumina, titania, etc. can easily exhibit the same effect. Be expected.

〔effect〕

The present invention is particularly useful as silica for semiconductor encapsulant materials, and compared to conventional silica for semiconductor encapsulant materials, it is more effective when filled into an epoxy resin material, which is a resin for semiconductor encapsulant materials, and subjected to molding. The occurrence of flakes is almost eliminated, and moldability is improved without deterioration of fluidity.

Further, the manufacturing method of the present invention is extremely advantageous industrially because it can be easily improved using the conventionally known semiconductor sealing material silica.

〔Example〕

Examples of the present invention will be shown below, but the present invention is not limited to these Examples.

Example 1 Bar force was obtained using silicon tetrachloride (Si014) as a raw material. The specific surface area of this spherical silica was measured after being washed by ultrasonic vibration, and the result was 0.4 g/g.

Using the above spherical silica, fi! to a proportion of 50% by weight with water! After fji separation, fine powder silica (manufactured by Tokuyama Soda Co., Ltd., trade name Rheosil QS-102) having a primary particle diameter of 0.02 μm was added at a ratio of 15% by weight, and the mixture was heated using a heating mixer equipped with an agitator. Mix evenly, then 1
After drying and dry crushing at a temperature of 10℃, 1
Particles smaller than 0.05 μm were removed. The obtained silica has a specific surface area of 3.5tr/f and is shown in Figure 1 at a magnification of 5000.
An electron micrograph with a magnification of 4 cm (10 μm) is shown.

Furthermore, the silica obtained above was filled into an epoxy resin material used for a semiconductor sealing material at a ratio of 65% by weight, melted and kneaded, and then used in a mold. Qualitative observation of its moldability revealed that its fluidity was as good as that of conventional granular silica for semiconductor encapsulants, and the occurrence of flash in molds was almost eliminated, and its strength was improved. It was done. Note that when the above-mentioned spherical silica, which corresponds to the conventional silica for semiconductor encapsulant materials, was similarly used as a filler, a considerable amount of flash was observed in the mold.

In addition, after dispersing the silica 10I obtained above in 50cc of water using ultrasonic waves at the output of IOW for 20 minutes, the supernatant liquid was separated, the remaining silica was dried, and N
The specific surface area measured by 2-BFT method is 2.5 m'/f
/Met. Figure 2 is 5000 times that amount (4 cm is 10
It was an electron micrograph with .mu.m). It is observed that fine powdered silica is adhered to the surface of the silica.

For comparison, one portion of fine powder silica was added to the spherical silica described above.
The same (5000 times (4 cT)
An electron micrograph is shown in which n is 10 μil). In addition, the perforation force of this mixed silica was cleaned by ultrasonic waves under the same conditions as described above is shown in Figure 4, which is the same < 5000 times (4
An electron micrograph of CRN of 10 μm is shown. From these results, it is recognized that fine powdered silica is detached from the surface of silica.

Example 2 Fine powder silica (
Silica was prepared by adding 15% by weight of Rheolosil) and heating it to 150°C in a heating mixer equipped with an agitator, and while mixing, 150% water per 1J19 of the silica was introduced from a spray nozzle. did.

The specific surface area of the obtained silica was 3.3 m'/f, and after ultrasonic cleaning, it was L9 m'/f. In addition, the prepared silica was filled into an epoxy resin material in the same manner as in Example 1, and the moldability was evaluated to f#, and the fluidity was found to be equally good compared to spherical silica (unprepared silica). There was almost no occurrence of paris, and the strength was improved.

Example 3 While heating the same spherical silica used in Example 1 to 110°C in a heating mill, finely powdered silica (Rheolo Seal) was injected into a slurry of 10 layers prepared in advance with water through a spray nozzle. The finely divided silica corresponds to a proportion of 1.5% by weight! It was folded.

The specific surface area of the obtained silica was 3.4 m'7'f/, and after ultrasonic cleaning it was 2.3rn'/f. Moreover, as a result of being subjected to the same molding as in Example 1, the fluidity was equally good, there was almost no occurrence of flakes, and the strength was improved compared to spherical silica.

[Brief explanation of the drawing]

FIG. 1 corresponds to the micrometer of the present invention obtained in Example 1. FIG. 2 corresponds to the silica of the present invention obtained in Example after being cleaned by ultrasonic waves. In FIG. 3, 4 cm of silica (mixed silica of spherical silica and fine powder silica) obtained as a comparative example of the present invention corresponds to 10 μm. Moreover, FIG. 4 corresponds to a 10μ course of ultrasonic cleaning of the above-mentioned mixed silica.

Claims (1)

[Claims] 1) Fine powder metal oxide with a primary particle diameter of 0.1 μm or less fixed to the particle surface with a specific surface area of 1 to 10 m^2/
2) Add a fine powder metal oxide having a primary particle size of 0.1 μm or less to granular silica having a particle size of 1 to 150 μm.
A method for producing silica, which comprises mixing in a wet state at a ratio of 5% by weight and then drying.