JPH0214807A - Modified fused spherical silica and production thereof - Google Patents

Abstract

PURPOSE:To improve quality of modified fused spherical silica by subjecting the surface of fused silica having a specific average particle diameter to hydrophobizing treatment and forming a drescribed BET specific surface area. CONSTITUTION:Fused silica having an average particle diameter within the range of 1-100mum is treated with a ball mill, etc., coated with a synthetic resin solution to apply powerful shearing force thereto. In the process, the surface of the fused silica is effectively hydrophobized by the powerful shearing treatment to form a BET specific surface area of 13 times based on the theoretical specific surface area. The above-mentioned modified fused silica is substantially spherical particles and the surface thereof is simultaneously hydrophobized with an organic surface treating agent, such as silane coupling agent. Thereby, both filler effects on semiconductor sealing materials and quality of the modified fused silica are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to surface-modified modified fused spherical silica and a method for producing the same.

More specifically, the present invention relates to a modified fused spherical silica suitable for use as a filler in a resin-based semiconductor encapsulant material obtained by subjecting molten spherical silica to a mechanochemical reaction treatment, and a method for producing the same.

[Prior art] and [Problems to be solved by the invention] With the development of semiconductors, especially LSI and fiLsI, improvements in the properties of resin-based encapsulants used for the purpose of protecting the semiconductors are increasingly desired. ing. Conventionally, highly integrated LS
I. VLSI encapsulation has shifted from ceramic to inexpensive resin encapsulation, and epoxy resin is primarily used for resin encapsulation, with silicone resins and the like also being used. Currently, in order to impart thermal properties, workability, electrical properties, etc. to these resins, silicic acid fillers are mainly used.

As the silicic acid filler, crystalline silica or fused silica is appropriately used, or these are crushed to a predetermined particle size by an appropriate crushing means. The particle surface of these crushed silicas is silica with sharp fractured surfaces, and VLS
There are many problems in terms of filler properties required with the transition to I. For example, 255KDRM, I
In highly integrated LSI such as MDRM, the wiring pattern is 5p or less, which is extremely thin, and there is a risk of PIrm of the wiring due to mechanical molding and heat shrinkage during use. As the amount of heat generated increases with the transition to SI, silica is charged to release it.
For example, the trend is to increase the number of ari.

In view of these circumstances, the present inventors have been developing spherical fused silica products. In general, fused spherical silica is produced by exposing a silica raw material to an atmosphere at a temperature above the melting point such as in a flame and melting it, and then forming it into a spherical shape due to the surface tension, or by spraying pre-molten silica into a gas to form a spherical shape. It is well known that it can be obtained by However, the fused silica obtained in this way is almost completely fused silica, and its specific surface area is close to the theoretical value when measured by the BET method, and it is considered that there is almost no surface activity.

On the other hand, resin-based encapsulation materials are produced by mixing epoxy resin, curing agent, surface treatment agent, inorganic filler (silica), etc. to produce a compound with characteristics tailored to a specific application, and are typically produced by transfer molding. A molding method is used to encapsulate semiconductors with resin.

However, in this case, fused silica with a small specific surface area and low surface activity not only has a poor surface treatment with, for example, a silane coupling agent, but also does not adhere well to the epoxy resin set and objects, so that the fused silica has a low specific surface area and low surface activity. There are also problems such as moisture in the atmosphere that enters from the inside and causes corrosion of the wiring, resulting in a decrease in mechanical strength.

In view of these circumstances, the present inventors conducted intensive research to provide a sealing material filler with even better properties while taking advantage of the physical properties of fused spherical silica, and completed the invention IJI.

The present invention provides a highly filling material that can be used as a sealing material for semiconductors that are more highly integrated with the development of the semiconductor industry.
The object of the present invention is to provide modified fused spherical silica which has high mechanical strength and excellent moisture resistance and is suitable as a filler for resin-based semiconductor encapsulants, and a method for producing the same.

rMeans for solving problems] That is, in the present invention, the average particle diameter is 1 to lo.

fused spherical silica having a BET specific surface area of at least three times or more than the theoretical specific surface area of a perfect sphere of the particle diameter, the surface of which is hydrophobized. quality fused spherical silica, and an average particle size of 1
This invention relates to a method for producing modified fused spherical silica, characterized in that fused spherical silica having a weight of 100 gm to 100 gm is subjected to a mechanochemical reaction treatment by strong shearing in the presence of an organic surface treatment agent.

The present invention will be explained in detail below.

The modified fused spherical silica according to the present invention is obtained by surface-modifying extremely high-purity fused spherical silica particles with a content of α-ray emitters such as uranium and thorium of less than 1 pl)b. The particles are suitable as a filler for resin sealing that can follow highly integrated semiconductors.

The method for producing fused spherical silica is well known, and the production history thereof is not particularly limited in the present invention.

Typical manufacturing methods include melting high-purity natural quartz powder or high-purity synthetic silica powder with oxygen-propane, oxygen-hydrogen, etc. flames to form spheres, and melting pre-melted silica in air. There are methods such as spraying it into spheres.

In the present invention, spherical silica does not necessarily mean that the particle shape of fused silica is a true sphere, but when silica particles are melted without substantially agglomerating, or when silica particles are melted without substantially agglomerating, Refers to particles that take on an independent spherical shape due to their surface tension when a melt is sprayed.
Needless to say, spherical bodies with a more or less oval shape may also be included depending on manufacturing conditions.

In the present invention, such fused spherical silica preferably has an average particle diameter of 1 to 1004 m, preferably 5 to 50 uLlm.

This is a preferable particle size required as a filler for an encapsulant, or the specific surface area of such fused spherical silica as measured by the BET method is approximately close to the theoretical specific surface area of a true sphere of that particle size. It is.

For example, wet-method synthetic silica obtained by ion exchange treatment using metasilicon soda as a raw material (Japanese Patent Application No. 59-159)
Table 1 below shows the theoretical specific surface areas and specific surface areas measured by the 11ET method of fused spherical silica of various particle sizes obtained by flame melting silica (see No. 1:1:1).

Table 1 Such a tendency is of course the same for fused spherical silica based on Noh's manufacturing method.

However, since such fused spherical silica has low surface activity, it has poor reactivity even if it is surface-treated with a silane coupling agent, for example.The reason for this is that, as shown above, the specific surface area is small and silica This is thought to be because there are almost no silanol groups on the particle surface, so no reaction with functional groups occurs.

The modified fused spherical silica according to the present invention is a hydrophobic particle having a BET specific surface area that is at least 3 times or more, preferably 4 times or more, than the theoretical specific surface area that indicates whether such silica particles are true spheres of the particle size. It is characterized in that it has been surface-treated by chemical treatment and has been surface-modified to be suitable as an encapsulant filler.

Increasing the specific surface area can also be achieved, for example, by recovering semi-fused spherical silica particles, but in this case, the amount of water absorbed is large, making it not only unsuitable as a sealant filler but also difficult to reproduce industrially. Lacks sex.

Therefore, the present invention provides a method for producing surface-modified fused spherical silica with an average particle diameter of 1 to 100 hta
It can be obtained industrially with good reliability by subjecting fused spherical silica in the range of 1 to 100% by subjecting it to a mechanochemical reaction treatment by strong shearing operation.

Powerful shearing operations here include, for example, ordinary ball mills, centrifugal ball mills, vibrating ball mills, milling machines,
It is operated using a processing device such as a colloid mill or an ultrasonic dispersion machine, which causes a strong shearing force to act between the fused spherical silica particles, causing a mechanochemical reaction on the particle surface and increasing the specific surface area. This increases the amount of surface modification.

In addition, when using the above-mentioned processing apparatus, for example in a ball mill, it goes without saying that silica particles made of a material in which there are extremely few impurities mixed therein are used.

For this reason, it is preferable to use, for example, a ball mill coated with a synthetic resin such as nylon or urethane.

The processing method is carried out, for example, by placing the raw material of fused spherical silica particles together with a grinding ball in a ball mill and rotating the ball for a predetermined period of time, and this operation itself is well known to those who handle powder materials.

Although the operating time varies depending on the properties of the two-ball capacity of the device, the mixing ratio of the balls and the powder, etc., as mentioned above, it is sufficient that the operation time is such that the IIET specific surface area is at least three times larger than the theoretical specific surface area. To give just one example, it is approximately 4 hours or more, and it is desirable that the BET ratio is in the range of 5 to 5 m2/g.

The main purpose of this strong shearing operation is to cause a mechanochemical reaction of the molten spherical silica particles, and it is necessary to ensure that any treatment that involves crushing does not occur. be.

Particles with sharp fractured surfaces due to pulverization are not preferred as fillers even if the specific surface area increases.

According to experiments conducted by the present inventors, raw material silica particles
In the following cases, the particle size after treatment is almost the same as that before treatment, but if other particles are used as raw materials, the particle size tends to decrease due to pulverization, so requires caution.

Due to the mechanochemical reaction based on such strong shearing treatment, the specific surface area of the fused spherical silica particles increases, and silanol groups are generated on the surface, thereby activating the particle surface.

The amount of silanol groups can be quantitatively measured, for example, by the adsorption amount of a dye such as methylet.

As described above, in the absence of an organic surface treatment agent, surface activation based on strong shearing can be performed.The present invention provides that the surface activation based on strong shearing is carried out in the presence of an organic surface treatment agent during such strong shearing treatment. Hydrophobization can be effectively achieved by using a surface treatment agent and mechanochemical reaction such as fused spherical silica that accompanies activation.

Examples of such organic surface treatment agents include alcohols such as methanol, ethanol, and propatool, organic silicon compounds such as silane coupling agent or silicone oil, and higher fatty acids and esters thereof such as stearic acid and its esters. Furthermore, when using one or more of these, an organic solvent can be used together if necessary.

In the present invention, it is important to perform surface modification based on mechanochemical reactions while avoiding the presence of as much water as possible.

[Example] The present invention will be explained in more detail by referring to Reference Examples and Examples below.

Reference example Sodium metasilicate 9 Wood salt was dissolved in water and 4wt%Si
The solution of O□ was added to cation exchange resin IRA-1 manufactured by Organo.
The silica sol solution obtained by treatment with 2[]B is coagulated and precipitated in ammonium nitrate solution, and this is i! ! passed. Disperse the cake in water and wash with acid using IMIIN Shima liquid.
Next, water washing was performed.

This washed cake was dispersed in water again and then spray-dried using a spray dryer (Okawara Seisakusho QC-20). The average particle size of this silica gel with good fluidity and particle size adjustment is lo, Gp-m, and the BET specific surface area is 285 m''/
It was g. This was subjected to flame melting treatment using oxygen-propane gas to obtain fused spherical silica. The average particle diameter of this fused spherical silica is 9.5 gyaBET specific surface area is O,
:16 m"/H.

Next, 2 kg of this molten spherical silica was charged into a 10JI nylon ball mill, and nylon-coated iron balls 7
．． 8kg (ball diameter: 25φ, 15φ, 10φ)
5.8kg, 1.5kg, 0.5kg of seeds respectively)
A mechanochemical reaction was carried out by rotating the tube and performing one powerful shearing operation.

Samples were taken over time and observed for particle size, specific surface area, and degree of coloration by methylene blue, and the results shown in Table 2 were obtained.

(Note) Observation of the degree of coloration by methylene blue (MB) The sample was immersed in a methylene blue aqueous solution for 2 hours) 1 It was separated, washed, and dried, and the degree of coloration was observed. Depending on the degree of surface silanol, the color varies from light blue to H color to bluish-purple.

The evaluation was shown as follows.

Pale blue + [Note: Crushed silica stone (50jLm
) Blue +++ Purple +++ 10+ The properties of the modified fused spherical silica subjected to ball milling for 20 hours were investigated and the results are as shown in Table 3.

Table 3 Example 1 In the reference example, γ-chrysyl-xypropyltrimer-
Strong shearing treatment was performed under the same conditions and operations except that xysilane was prepared together with a small amount of benzene and added at 1.0% based on the amount of fused spherical silica, and the obtained silica had an average particle size of 1. The particle surface was made hydrophobic by reacting with a silane coupling agent in a mechanochemical reaction, and had excellent free-flowing properties.

Example 2 A solution prepared by dissolving 3 parts by weight of methylhydrodiene polysiloxane in 18 parts by weight of ethyl alcohol was added to 100 parts by weight of the fused spherical silica obtained in Reference Example, and the mixture was treated under the same treatment conditions and operations as in Reference Example. Strong cutting treatment was applied. The obtained silica was a spherical product with an average particle diameter of 14.8Ji.m, the surface of which had been made hydrophobic through a mechanochemical reaction, and had excellent free-flowing properties.

[Effect of the invention] The modified fused spherical silica according to the present invention has an average particle diameter of 1 to 1
The particles are substantially spherical particles having a particle size in the range of 0.00 gta, and the surface thereof has been surface-modified by making it hydrophobic with an organic surface treatment agent such as a silane coupling agent.

Such modified fused spherical silica becomes effective as a semiconductor encapsulant filler made of epoxy resin or the like.

Further, according to the production method according to the present invention, the modified fused spherical silica can be obtained industrially advantageously.

Applicant: Nippon Chemical Industry Co., Ltd. Agent: Hiroshi Watari Hebe

Claims (4)

[Claims] (1) Hydrophobizing the surface of fused spherical silica having an average particle diameter in the range of 1 to 100 μm and a BET specific surface area that is at least three times greater than the theoretical specific surface area of a true sphere of that particle diameter. Modified fused spherical silica that is characterized by the following characteristics: (2) Modified fused spherical silica contains α of uranium and thorium.
The modified fused spherical silica according to claim 1, wherein the content of radioactive substances is 1 ppb or less. (3) The modified fused spherical silica according to claim 1 or 2, wherein the surface is subjected to hydrophobization treatment with alcohol or an organic silicon compound. (4) Production of modified fused spherical silica characterized by subjecting fused spherical silica having an average particle diameter in the range of 1 to 100 μm to a mechanochemical reaction treatment by strong shearing operation in the presence of an organic surface treatment agent. Method.