JP4133653B2 - Method for producing surface-treated inorganic filler and surface treatment method for inorganic filler - Google Patents

Description

  The present invention relates to a manufacturing method and a surface treatment method of an inorganic filler for semiconductor element sealing materials such as IC, LSI, CPU, MPU, and CCD, and more particularly to a manufacturing method and a surface treatment method of an inorganic filler containing fine particles. .

  As a sealing material for semiconductor elements such as IC and LSI, epoxy resins containing a large amount of inorganic filler are widely used from the viewpoint of reliability. For this type of material, a surface-treated inorganic filler is usually used for the purpose of improving moisture resistance. Also, in recent years, for the purpose of further increasing the amount of the inorganic filler and improving the fluidity of the epoxy resin, for example, an inorganic filler containing a fine spherical filler having a particle size distribution of 1 μm or less as a particle size distribution in a predetermined ratio. Is being studied (see, for example, Patent Document 1).

  By the way, although several techniques are proposed about the surface treatment method of an inorganic filler (for example, refer patent document 2), the above-mentioned fine filler is uniformly surface-treated, and it is processing without agglomerating. It is very difficult. For this reason, when a fine filler is used, the surface treatment is usually not performed. However, when the surface treatment is performed, the surface of the filler is treated in a solvent containing a treatment agent such as a coupling agent. Then, the method of taking out the filler which surface-treated by distilling a solvent off can be considered.

JP 2001-189407 A JP 2002-322243

However, when this method is used, it is necessary to remove the solvent while preventing the filler from agglomerating. However, it is difficult to completely prevent the filler from agglomerating, and a crushing treatment must be performed in the subsequent step. No longer. Furthermore, even if pulverization is performed, it is impossible to reduce the particle size of the filler to the initial value. In particular, when the fine filler forms an agglomerate together with the coupling agent, there is a problem that the treatment agent gels due to a reaction such as hydrolysis and hardens the agglomerate. And when the filler containing this kind of hard aggregate is used for the sealing material of a semiconductor element, the gate of a metal mold | die is obstruct | occluded at the time of molding sealing of a semiconductor element, and an unfilling defect is produced.
Under such circumstances, there has been a strong demand for a surface treatment method for inorganic fillers containing fine particles having a small particle size.

  The present invention has been made in order to solve the above-described problems. After mixing the inorganic filler and the surface treatment agent, the mixture is pulverized to loosen the agglomeration, thereby uniformly treating with the surface treatment agent. An object of the present invention is to provide a method for producing an inorganic filler that does not aggregate and a surface treatment method.

The above-mentioned objects of the present invention are obtained by using an inorganic filler that is silica and / or alumina and a surface treatment agent composed of a silane coupling agent so that the amount of the surface treatment agent used relative to the inorganic filler is 0.1-3. After mixing with a stirrer / mixer so as to be in mass% , the mixture is replaced with a continuous crushing closed multi-stage shear shear extruder different from the stirrer / mixer or a continuous rotating ball mill and pulverized in a temperature range from room temperature to 75 ° C. It was achieved by a method for producing a surface-treated inorganic filler characterized in that:

In addition, the above-mentioned objects of the present invention are such that an inorganic filler that is silica and / or alumina and a surface treatment agent comprising a silane coupling agent are used in an amount of 0.1% of the surface treatment agent relative to the inorganic filler. After mixing with a stirrer / mixer so as to be ˜3% by mass , the mixture is replaced with a continuous pulverized closed multi-stage shear shear extruder or a continuous rotary ball mill different from the stirrer / mixer, and a temperature range from room temperature to 75 ° C. It was achieved by a surface treatment method of an inorganic filler, characterized in that it is pulverized with a surface treatment.

  As apparent from the above description, according to the production method of the present invention, the non-uniform coating of the surface treatment agent on the aggregates and inorganic filler generated during mixing can be almost completely eliminated by the pulverization step. Can be uniformly treated with the surface treatment agent to obtain an inorganic filler without aggregation. This eliminates the need for a post-process for screening the agglomerates and contributes to rationalization. Moreover, the resin for sealing a semiconductor element containing the inorganic filler obtained in the present invention has a low melt viscosity and an excellent workability. Further, the cured resin has little strength deterioration under high humidity and is effective in improving the reliability of the semiconductor element.

Embodiments of the present invention will be described below.
As an inorganic filler used in the present invention. Conventionally known fused crushed silica, fused spherical silica, crystalline silica, alumina, spherical alumina, silicon nitride, aluminum nitride and the like can be cited as representative examples.
The particle size distribution of the inorganic filler is not particularly limited, but those having a maximum particle size of 100 μm or less and an average particle size of about 3 to 30 μm can be used. In particular, those having a particle size distribution in which the proportion of the average particle diameter of 1 μm or less in the inorganic filler is 30% or less can be efficiently surface-treated by the present invention. Recently, inorganic fillers for underfill having an average particle size of 0.2 to 5 μm and a maximum particle size of about 5 μm have been used. Agents are also targeted. And this invention can surface-treat the inorganic filler which consists mostly of fine particles as mentioned above, and the filler currently used conventionally widely.

  Conventionally known silanes and coupling agents can be used as the surface treatment agent. As the coupling agent, for example, titanium, aluminum, chromium, and silane can be used, but the present invention is not limited thereto.

Typical silanes (silane coupling agents) include vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycid. Xylpropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styrylmethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxy propyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, 3-aminopropyltrimetho Silane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, Examples include functional silanes (silane coupling agents) such as bis (triethoxysilylpropyl) tetrasulfide and 3-isocyanate-propyltriethoxysilane. Nonfunctional silanes (silane coupling agents) include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, dimethyldiethoxysilane, methyltriethoxysilane, and phenyltrimethoxysilane. And silanes having an organic group and an alkoxy group such as phenyltriethoxysilane and hexyltrimethoxysilane.
These functional or non-functional silanes (silane coupling agents) may be used alone or in combination.

Although the usage-amount of the surface treating agent with respect to an inorganic filler is dependent also on the specific surface area of an inorganic filler, it is 0.1 to 3 weight% normally. The required amount of the surface treatment agent for surface treatment of the inorganic filler with a monomolecular film can be referred to the following model formula.
Use amount of surface treatment agent (g) = mass of filler (g) × specific surface area of filler (m ² / g) / minimum coverage of surface treatment agent molecule (m ² / g)
And when calculating based on this formula, if the amount of the surface treatment agent used is less than 0.1% by mass, the degree of surface treatment is insufficient and the surface of the inorganic filler cannot be treated uniformly, and this inorganic filling The strength of a semiconductor element sealing material using an agent is reduced under high humidity conditions. On the other hand, when the amount of the surface treatment agent used exceeds 3% by mass, the amount of the surface treatment agent is too large and the surface of the filler is thickly coated. Invite. Desirably, the use of the surface treatment agent is 0.2 to 2% by mass, and more desirably 0.3 to 2% by mass.

  And in the manufacturing method of this invention, an inorganic filler and a surface treating agent are mixed first. This mixing is for sufficiently adhering the surface treatment agent to the entire surface of the inorganic filler. For example, it is preferable to perform stirring and mixing using a high-speed stirring device such as a Henschel mixer. The apparatus used for stirring and mixing is not limited to the above, and any apparatus can be used. And it is good to stir-mix preferably for 5 to 60 minutes. When the stirring and mixing time is less than 5 minutes, the material is not sufficiently mixed, and the surface of the inorganic filler has portions with a high or low surface treatment agent concentration, resulting in uneven surface treatment. When the stirring and mixing time exceeds 60 minutes, a part of the coupling agent used for the surface treatment agent is hydrolyzed to cause a condensation reaction, and a strong aggregate is generated between the inorganic filler and the inorganic filler. For this reason, stirring and mixing is more preferably performed for 10 to 45 minutes, and more desirably for about 10 to 30 minutes. That is, in a preferred embodiment, the mixing is not excessively performed as in the prior art, and so to speak, the preliminary mixing is limited.

  In addition, as a specific method of mixing using a high-speed stirrer, a surface treatment agent may be applied to the inorganic filler using a spray or the like while stirring the inorganic filler in the device, or without using a spray. What is necessary is just to add a surface treating agent directly to a mixing apparatus. You may use a surface treating agent in the state which added water beforehand and was partially hydrolyzed. In particular, since the hydrolysis reaction becomes slow when the surface treatment agent is dried, it is preferable to add some water in advance to the inorganic filler and then perform mixing.

  Next, the mixture is pulverized using a continuous pulverizer. This pulverization step is for obtaining a surface-treated inorganic filler having an initial average particle diameter by pulverizing the aggregate, and in the pulverization step, the surface treatment agent is coated on the surface of the inorganic filler. Also do. In other words, in the preferred embodiment of the present invention, excessive surface treatment by excessive mixing is not performed in the mixing step as in the prior art, so to speak, only preliminary mixing is performed, and it is generated during (preliminary) mixing in the next pulverization step. It is characterized in that the surface treatment proceeds simultaneously while pulverizing the aggregate of the inorganic filler and pulverizing the coarse particles of the inorganic filler. In this way, the aggregation does not remarkably occur in the mixing step, and the generated aggregation can be removed in the pulverization step, and the surface treatment can be sequentially advanced in the mixing step and the pulverization step. Since the continuous pulverizer does not have too much impact energy, there is an advantage that the surface treatment agent can be prevented from being oxidized by the impact force.

  Specifically, it is preferable to use a continuous pulverized closed multi-stage shear shear extruder or a continuous rotary ball mill. In the case of a batch-type rotating ball mill or jet mill, impact energy is excessive, and the surface treatment agent is oxidized and deteriorated by impact force to generate harmful organic acids. That is, for example, when comparing a continuous rotary ball mill and a batch rotary ball mill, the former can perform grinding and surface treatment in a short time (simultaneously), whereas the latter has the same characteristics as the former. When trying to obtain a powder, the processing time becomes very long. Usually, the residence time of the material in the apparatus is about 3 to 15 minutes in the continuous rotary ball mill, whereas the residence time is 2 to 10 hours in the case of the batch type rotary ball mill.

  In the case of a continuous rotating ball mill, the ball diameter in the apparatus is about 5 mm or less, but the ball diameter of the batch rotating ball mill is about 20 to 100 mm, and the impact energy due to the collision between the balls is excessive accordingly. Become. Furthermore, in the case of a continuous rotating ball mill, processing can be performed while cooling from the outside of the apparatus, and the temperature in the mill can be controlled. On the other hand, in a batch rotating ball mill, cooling is not normally possible, and the temperature in the mill is close to 100 ° C. To rise. As described above, the impact energy is small, the treatment time is short, and the treatment temperature is relatively low (for example, room temperature). Therefore, in a continuous rotating ball mill, oxidation degradation due to the impact force of the surface treatment agent, and organic acid Occurrence can be prevented.

  In particular, when a continuous rotating ball mill is used, the surface treatment agent (particularly silane) can be uniformly coated on the surface of the inorganic filler while preventing the oxidation.

  In order to allow the surface treatment to proceed at a desired treatment temperature under reliable and optimum conditions, it is desirable that the continuous pulverizer has a heating mechanism and a cooling mechanism. In general, in order to ensure the reaction between the surface treatment agent and the surface of the inorganic filler, the treatment temperature in the pulverization step is preferably room temperature or higher, desirably from room temperature to 150 ° C.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited by them. Further, unless otherwise specified,% and part represent% by weight and part by weight, respectively.
A. Experimental Example 1 (Surface treatment of inorganic filler)

In a Henschel mixer (200 liters) equipped with a spray nozzle, 100 kg of spherical silica with an average particle size of 8 μm and a maximum particle size of 50 μm and a content of 20% or less is 20% as an inorganic filler, and mixed at a rotation speed of 1000 rpm Then, 1.5 kg of 3-glycidoxypropyltrimethoxysilane as a surface treatment agent was applied to the spherical silica surface while spraying from a spray nozzle. After coating, mixing was performed for 10 minutes, and then the mixture was taken out of the Henschel mixer.
Next, the taken mixture is put into a continuous rotating ball mill (dynamic mill MYD25 manufactured by Mitsui Mining Co., Ltd., screw rotation speed 500 rpm, ball diameter 5 mm, discharge amount 150 kg / hour), and pulverized while keeping the material temperature at 75 ° C. At the same time, surface treatment was performed. The discharge from the mill was cooled to obtain surface-treated silica A. The residence time of the mixture in the mill was about 10 minutes.

  Example 1 except that 100 kg of spherical silica having an average particle size of 0.5 μm and a maximum particle size of 5 μm was used as the inorganic filler, and 2.5 kg of 3-glycidoxypropyltrimethoxysilane was used as the surface treatment agent. Using the same Henschel mixer and mill, mixing and pulverization were performed under the same conditions to obtain surface-treated silica B.

  The same mixing conditions as in Example 1 except that 1.5 kg of 3-glycidoxypropyltrimethoxysilane was previously reacted with 0.1 kg of pure water and partially hydrolyzed as the surface treatment agent. Mixed. The mixture was subjected to a material temperature of 65 ° C. using a closed multi-stage shear shear extruder (KCK80X2V, manufactured by KSH Co., Ltd., rotating blade φ80, number of blades 4 sets, blade rotation speed 300 rpm, discharge rate 30 kg / hour). While maintaining, pulverization was performed to obtain surface-treated silica C. The residence time of the mixture in the closed multi-stage shear shear extruder was about 15 minutes.

  Aside from using 1.5 kg of 3-aminopropyltrimethoxysilane as a surface treatment agent, the same Henschel mixer and mill as in Example 1 were used, and mixing and pulverization were performed under the same conditions to obtain surface-treated silica D. Obtained.

Comparative Example 1
A surface-treated silica E was obtained by performing the mixing under the same conditions as in Example 1 except that the mixing was performed for 20 minutes and the grinding treatment was not performed.
Comparative Example 2
100 kg of spherical silica having an average particle size of 0.5 μm and a maximum particle size of 5 μm was used as the inorganic filler, and 2.5 kg of 3-glycidoxypropyltrimethoxysilane was used as the surface treatment agent, and mixing was performed for 20 minutes, Except that the grinding treatment was not performed, mixing was performed under the same conditions as in Example 1 to obtain surface-treated silica F.
Comparative Example 3
In the pulverization process, instead of the continuous rotary ball mill, a batch rotary ball mill (capacity: 100 liters) is used, and 50 kg of 25 mm diameter alumina balls and 50 kg of the mixture are put into the mill and pulverized for 4 hours. G was obtained. The temperature of the surface-treated silica when discharging the surface-treated silica from the mill was 85 ° C.

Evaluation of surface-treated silica Next, various evaluations of surface-treated silica were performed by the following methods.
1. Amount of coarse particles (including agglomerates) 100 g of silica before and after the surface treatment was weighed and classified with a water sieve using a 300 mesh sieve. After classification, the silica remaining on the sieve was dried and the weight was measured to obtain the amount of coarse particles. The larger the amount of coarse particles, the more agglomeration occurs.
2. Average Particle Size The silica particle size distribution before and after the surface treatment was measured using a cirrus laser measuring device. The higher the average particle size after the surface treatment, the more agglomeration occurs.
3. Extraction water conductivity 5 g of surface-treated silica was put in a pressure vessel containing 50 g of pure water, and water was extracted at 120 ° C. for 20 hours. After separating the silica with a centrifuge, the electrical conductivity of the extracted water was measured. The higher the electric conductivity, the more the silane coupling agent, which is a surface treatment agent, is oxidized to produce an organic acid, and the effect of the surface treatment is degraded.
Table 1 shows the evaluation results of each surface-treated silica.

  As is clear from Table 1, in the case of Examples 1 to 4, the surface-treated silica after the mixing and pulverization did not produce any aggregates, and the average particle diameter did not increase. From this, it can be seen that the original spherical silica or agglomerates generated during mixing were almost completely eliminated by pulverization by a continuous rotary ball mill. Further, it is considered that the non-uniform coating of silane on the spherical silica is made uniform by pulverization. For example, the spherical silica material also includes particles in which the particles are fused at the time of manufacture to form a wrinkle, but is surface-treated while being pulverized into single particles by a continuous rotary ball mill. Therefore, after the surface treatment, there were almost no aggregates of inorganic filler particles and large particles in which the inorganic fillers were fused together.

  In Examples 1, 3, and 4, it was found that the surface treatment can be performed without causing aggregation on an inorganic filler having an average particle size of less than 10 μm. In Examples 1, 3, and 4, an inorganic filler containing fine particles having a particle size of 1 μm or less was used. In this case, since the average particle size did not increase after the surface treatment, fine particles having a particle size of 1 μm or less. It was also found that surface treatment can be performed without causing aggregation. Similarly, in Example 2, it was found that surface treatment can be performed without causing aggregation on an inorganic filler having an average particle diameter of 0.5 μm.

  On the other hand, in Comparative Examples 1 and 2, since the pulverization process using the continuous pulverizer was not performed, a large amount of agglomerates were generated after the surface treatment, and the average particle diameter was increased. Moreover, in the case of the comparative example 3, since the grinding | pulverization process was performed using the batch-type grinding | pulverization apparatus, the extraction water conductivity raised and the organic acid produced | generated. From this, it was found that when a batch type pulverizer is used, oxidative degradation of silane as a surface treatment agent occurs.

B. Experimental Example 2 (Preparation of a resin composition for sealing a semiconductor element containing an inorganic filler)

  59.6 parts of biphenyl aralkyl type epoxy resin (NC3000P: manufactured by Nippon Kayaku Co., Ltd.), 38.4 parts of biphenyl aralkyl type phenol resin (MEH7851: manufactured by Meiwa Kasei Co., Ltd.), 1.2 parts of triphenylphosphine as a catalyst , 2 parts of carbon black, 1.5 parts of γ-glycidoxypropyltrimethoxysilane, 0.15 parts of carnauba wax, 800 parts of the surface-treated silica A prepared in Experimental Example 1, and evenly mixed with two heat rolls Then, this was cooled and pulverized to obtain a resin composition for encapsulating a semiconductor element.

  A resin composition for encapsulating a semiconductor element was produced under exactly the same conditions as in Example 5, except that the surface-treated silica C was used as the surface-treated silica to be blended in the resin composition.

  A resin composition for encapsulating a semiconductor element was produced under exactly the same conditions as in Example 5 except that the surface-treated silica D was used as the surface-treated silica to be blended in the resin composition.

Comparative Examples 4 and 5
A resin composition for encapsulating a semiconductor element was prepared under the same conditions as in Example 5 except that the surface-treated silicas E and G were used as the surface-treated silica to be blended in the resin composition, respectively. 4 and 5.

The following evaluation was performed about the obtained resin composition.
1) Spiral flow Spiral flow was measured by using a powder obtained by pulverizing the resin composition as a sample and using a spiral flow measurement mold. The measurement conditions were a mold temperature of 175 ° C., a pressure of 6.86 MPa, and a molding time of 90 seconds.
2) Melt viscosity Using a Koka flow tester, the resin composition was measured at a measurement temperature of 175 ° C, a nozzle diameter of 1 mm, and a pressure of 0.98 MPa.
Measurement was performed by a method according to JIS K6911.
4) Bending strength (PCT100Hr)
After preparing a test piece having the shape described in JIS K6911, the post-cured test piece was subjected to PCT (pressure cooker test: 121 ° C., 100% RH, 0.213 MPa) under a high temperature and high humidity condition. Left for 100 hours. After this treatment, measurement was performed by a method according to JIS K6911.
5) Gate clogging, presence or absence of internal voids 20 TQFP packages with a gate size of 150 × 100 μm were transfer molded with a resin composition and sealed. Transfer molding was performed at a pressure of 175 ° C. and a pressure of 6.86 MPa. About the package after sealing, the presence or absence of unfilling (gate clogging) was visually observed, and the presence or absence of voids when observed with soft X-rays was investigated.
6) Aluminum electrode corrosion An element designed for evaluating corrosion of an aluminum metal electrode was mounted on a 14-pin IC, and was molded by transfer molding under the above conditions with each composition and sealed. The sealed package was allowed to stand for 100 hours in a high-pressure oven at 125 ° C. and 85% humidity with a bias voltage of 15 V, and the corrosion of the electrodes was examined.
The obtained results are shown in Table 2.

  As is apparent from Table 2, in Examples 5 to 7, the bending strength of the resin composition does not decrease even under high temperature and high humidity conditions, and there is no gate clogging, internal voids, and aluminum electrode corrosion at all. As a result, the defect rate was 0%. On the other hand, in the case of Comparative Example 4, since the surface-treated silica E that has agglomerated is used, the bending strength is significantly reduced under high temperature and high humidity conditions, and gate clogging, internal voids, and aluminum electrode corrosion become significant. It was. From this, it was found that when the surface-treated silica having agglomerated is used for the resin composition, the moisture resistance is deteriorated. Further, in the case of Comparative Example 5, although the aggregation was not observed but the surface-treated silica G in which the silane coupling agent was oxidized and deteriorated was used, the gate clogging and the internal void did not occur, but the aluminum electrode corrosion could not be prevented and the moisture resistance It was found that the characteristics deteriorated significantly.

C. Experimental Example 3 (Preparation of a resin composition for sealing a semiconductor element containing an inorganic filler, part 2)

  55 parts of bisphenol F type epoxy resin (RE303S-L: manufactured by Nippon Kayaku Co., Ltd.), 15 parts of methyltetrahydroanhydrophthalic acid (MH700: manufactured by Shin Nippon Rika Co., Ltd.), 3,4-dimethyl-6- (2- A mixture of methyl-1-propenyl) -1,2,3,6-tetrahydrophthalic acid and 1-isopropyl-4-methyl-bicyclo (2.2.2) oct-5-ene-2,3-dicarboxylic acid ( Mixing ratio = 6: 4) (YH307: Japan Epoxy Resin Co., Ltd.) 30 parts, 130 parts of the surface-treated silica B prepared in Experimental Example 1, Curazole C11Z-PW (2-undecylimidazole: Shikoku Chemicals) as a curing catalyst A liquid epoxy resin composition was prepared by uniformly kneading 0.4 parts with three rolls.

Comparative Example 6
A resin composition for encapsulating a semiconductor element was produced under exactly the same conditions as in Example 8, except that the surface-treated silica F was used as the surface-treated silica to be blended in the resin composition.

The following evaluation was performed about each obtained resin composition.
1) Adhesive strength test For each resin composition, a truncated cone-shaped test piece (upper surface diameter 2 mm, lower surface diameter 5 mm, height 3 mm) was molded. The test piece was placed on a silicon chip coated with photosensitive polyimide and held at 150 ° C. for 3 hours to cure the polyimide. After curing, the shear strength of the obtained specimen was measured and used as the initial value. Further, the cured test piece was held for 168 hours under the PCT conditions, and the adhesive strength after moisture absorption was measured. The number of test pieces was five, and the average value was defined as the adhesive strength.
2) Penetration test After flip chip (chip size: 10 mm × 10 mm × 0.3 mm, bump diameter 120 μm, bump height 75 μm, bump pitch 200 μm) is placed on a hot plate at 100 ° C., each resin composition is applied to one side of the chip The sample was left for 5 minutes, and the presence of unfilled chips was examined by examining the penetration of the resin into the lower part of the chip using an ultrasonic flaw detector, and the number of unfilled chips / total number of chips was calculated. This penetration test is performed by sealing an underfill material of a flip chip type semiconductor element (a gap (gap) between the element and the substrate when the lower part of the semiconductor element and the organic substrate are sealed with bumps). In this case, the filling property (penetration by capillary flow) is evaluated when the epoxy resin composition for sealing a semiconductor element is used as a sealing agent for sealing.
The obtained results are shown in Table 3.

As is apparent from Table 3, in Example 8, there was almost no decrease in adhesiveness under high temperature and high humidity conditions, and the penetration test was also good. On the other hand, in the case of Comparative Example 6 using the surface-treated silica F in which a large amount of agglomerate was generated without using a continuous pulverizer, agglomeration occurred in the surface treatment process and the treatment was not performed uniformly. The decrease in adhesiveness under wet conditions became remarkable. Moreover, the result of the penetration test was bad and the filling property of the resin composition was poor.

Claims (2)

Stir and mix an inorganic filler that is silica and / or alumina and a surface treatment agent comprising a silane coupling agent so that the amount of the surface treatment agent used relative to the inorganic filler is 0.1 to 3% by mass. After the mixing in the apparatus, the mixture is replaced with a continuous pulverization closed multi-stage shear shear extruder different from the stirring and mixing apparatus or a continuous rotating ball mill and pulverized in a temperature range of room temperature to 75 ° C. A method for producing an inorganic filler. Stir and mix an inorganic filler that is silica and / or alumina and a surface treatment agent comprising a silane coupling agent so that the amount of the surface treatment agent used relative to the inorganic filler is 0.1 to 3% by mass. After mixing in the apparatus, the mixture is replaced with a continuous pulverization closed multi-stage shear shear extruder or continuous rotary ball mill different from the stirring and mixing apparatus, and pulverized in a temperature range from room temperature to 75 ° C. Surface treatment method.