TWI809042B - Fused spherical silica powder and its production method - Google Patents

Abstract

[Problem] To provide a silicon dioxide powder that contains particles with a somewhat larger particle size to ensure fluidity, but which reduces the amount of air bubbles existing in the particles to a level that can be used even in wafer-level packaging Even when used as fillers for encapsulation materials of type semiconductors, there are substantially no problems. [Solution] Provide a fused spherical silica powder, characterized in that: when measured by laser diffraction, it is a fused spherical silica powder with a cumulative volume 95% particle size (d95) in the range of 5 μm to 30 μm. For silicon powder, a part of the hardened body obtained by kneading and hardening the molten spherical silicon dioxide powder and epoxy resin at a mass ratio of 1:1 was ground and the exposed silicon dioxide section was observed under a microscope at 1,000 magnifications , the number of detectable air bubbles with a longest diameter of 5 μm or more is 50 or less per 10 cm ² of the hardened body grinding surface. It can be obtained by classifying fused silica obtained by using hydrophobized fumed silica as a raw material, setting the amount of silica supplied and the flame temperature within a specific range, and making it melt and spheroidize. .

Description

Fused spherical silica powder and its production method

The present invention relates to a novel fused spherical silicon dioxide powder and its manufacturing method. More specifically, it relates to a fused spherical silica powder with a small bubble content that can be suitably used as a filler for semiconductor packaging materials, etc., and a method for producing the same.

Silica is used in a variety of applications, and one of its uses is as a filler for semiconductor packaging materials. When used as a filler for semiconductor packaging materials, electrical insulation, high thermal conductivity, and low thermal expansion are required, and high filling of fillers is desired to satisfy these physical properties.

In order to obtain higher filling properties, it is better to use a particle size distribution to a certain extent as a filler than a material with a single particle size. Furthermore, those with larger particle diameters tend to increase the filling rate.

Also, at the same time, high formability is required and the fluidity of the filler-filled resin is desired, that is, low viscosity (at temperature: 25°C, shear rate (shear rate): 1s ^-1 viscosity: 1000Pa‧s or less ). In order to obtain such fluidity, in recent years, silica-based fillers generally use spherical ones.

Moreover, due to the increasing thinning and miniaturization of semiconductors, and the bulk packaging of a large number of wafers, the maximum allowable particle size of the filler is reduced and high filling becomes difficult. The necessity to maintain a high filler filling rate is increasing.

In terms of the filling characteristics obtained by being spherical and having an appropriate particle size distribution, and in terms of manufacturing cost, fused silica is superior to silica produced by other methods.

As a method for producing fused silica, the following methods are known: (1) a method of oxidizing silicon powder while melting; (2) melting a small amount of silica powder in a flame, and fusing a plurality of fused particles and and (3) burning and oxidizing a compound containing silicon atoms in a flame to produce tiny silicon dioxide and directly melting the tiny silicon dioxide in a flame, and by A method of producing by fusing molten particles to grow and spheroidize them, etc. For example, in Patent Document 1, fine silica particles obtained by burning an organosilane compound are further grown in a flame to obtain fused spherical silica powder with an average particle diameter of 0.05-5 μm. In Patent Document 2, fumed silica is melted in a flame to obtain fused silica containing a large amount of particles with a particle diameter of 3 μm or less. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2003-137533 [Patent Document 2] Japanese Patent Laid-Open No. 2000-191316

[Problem to be solved by the invention]

When air bubbles exist inside the silicon dioxide particles, the silicon dioxide particles filled in the packaging material will be cut off, Or grinding and air bubbles (voids) inside the particles are exposed. For this reason, recesses may be formed on the cross section or the ground surface of the encapsulating material. Figure 1 shows a schematic plan view of the ground surface of the package. Silica particles are usually dense particles 1 and do not generate voids on the grinding surface. When hollow particles 2 have air bubbles inside the particles, the air bubbles are exposed due to grinding and voids 3 are generated on the grinding surface. Fig. 2 shows a sectional view along line A-A of Fig. 1 . As shown in Fig. 2, the gap 3 on the ground surface becomes a concave portion. The occurrence of such recesses becomes a problem especially in the manufacture of semiconductor products via Fan Out Wafer Level Package (FOWLP). The production system of FOWLP can be performed as follows, for example. A plurality of semiconductor wafers that have been individually sliced are arranged on a substrate such as glass with the electrode surface facing upward. Second, package the semiconductor wafers in batches. Subsequently, the encapsulation material is ground to expose the electrodes. Subsequently, a photoresist is coated, exposed, and developed, so that the conductive metal is separated from the part where the photoresist has been removed to form a rewiring layer. Finally, each of the packaged plurality of semiconductor wafers is cut to obtain FOWLP type semiconductor products. If the silicon dioxide particles contained in the encapsulating material contain air bubbles, when the encapsulating material is ground, the air bubbles are exposed and recesses are formed on the ground surface. When the photoresist is placed in the concave portion, a concave portion is also formed in the photoresist, and in the next step, the conductive metal system is deposited unevenly in the concave portion. As a result, problems such as a reduction in product yield and a reduction in long-term reliability of semiconductor products due to defects in the formation of the rewiring layer may occur.

However, as mentioned above, in the production of fused silica, particle growth is obtained by melting and fusing among fine silica particles in a flame, and air bubbles are also involved during this fusion, and as a result, the produced Silicon dioxide also has the problem of things with air bubbles, which cannot be avoided.

The entrainment of the air bubbles can be reduced by improving the combustion conditions during production and the like. As a result, it was possible to reduce the air bubble content to a level that was undetectable using previous inspection methods. However, it is still at a level where problems may arise when attempting to use the WLP-type semiconductor packaging material filler having a step of partially cutting or grinding the packaging material as described above. In the manufacture of WLP-type semiconductor products, the grinding step is generally the last step, and defects generated at this stage directly lead to an increase in cost.

Of course, since there are no air bubbles larger than the particle size, the above-mentioned problem does not occur when particles with a larger particle size are completely excluded from the powder. Therefore, when the silica particles have a small particle size, there are few adverse effects caused by air bubbles. However, as mentioned above, in order to obtain a high filling rate, it is preferable that particles having a somewhat larger particle size also exist. The larger the particle size, the easier it is to contain air bubbles.

Therefore, the object of the present invention is to provide a novel silicon dioxide powder which, although it contains particles of a certain larger particle size, reduces the amount of such air bubbles to a level even when used as a packaging material for WLP type semiconductors. Even when using fillers, etc., there are substantially no problems. [Means to solve the problem]

The inventors of the present invention have intensively studied in view of the above-mentioned problems. Moreover, it was found that in the method of producing fused spherical silica powder by fusing and spheroidizing fine silica powder in a flame, the recovered fused silica powder is also limited by specifying the raw material silica powder and combustion conditions The particle size can solve the above-mentioned problems and the present invention has been completed.

That is, the present invention relates to a fused spherical silica powder, which is a fused spherical shape with a cumulative volume 95% particle diameter (d95) in the range of 5 μm to 30 μm when measured by laser diffraction. The silicon dioxide powder is characterized in that: the silicon dioxide section exposed by grinding a part of the hardened body formed by kneading and hardening the molten spherical silicon dioxide powder and epoxy resin at a mass ratio of 1:1, and The number of bubbles with a longest diameter of 5 μm or more detectable under a microscope at 1,000 magnifications is 50 or less per 10 cm ² of the polished surface of the hardened body. [Invention effect]

The amount of bubbles in the fused spherical silica powder of the present invention is very small. Therefore, when used as a filler for packaging materials of WLP type semiconductors, the effect of improving the product yield and long-term reliability of semiconductors can be achieved.

[Mode for Carrying Out the Invention]

The fused spherical silica powder of the present invention has a cumulative volume 95% particle size (d95) in the range of 5 μm to 30 μm when measured by laser diffraction. When the d95 is too small, it is difficult to obtain a high filling rate of the resin composition when used as a filler. On the other hand, when d95 is too large, there are problems such as poor permeability to the narrow portion of the resin composition when used as a filler. Preferably, d95 is 20 μm or less.

The meaning of excluding coarse particles is that when measured by laser diffraction, particles larger than 100 μm are preferably 0 mass %, particles larger than 75 μm are preferably 0 mass %, particles larger than 50 μm are 0 mass % % is the best.

The measurement by laser diffraction will be described in detail in Examples described later.

Moreover, when the silica powder of the present invention is measured under the above conditions, the cumulative volume 50% particle size (d50) is preferably in the range of 1-20 μm, more preferably in the range of 3-15 μm. In terms of removing coarse particles, when the fused spherical silica powder of the present invention is measured using a wet sieve, the amount of remaining particles at 106 μm is 0% by mass, and the amount of remaining particles at 45 μm is less than 0.1% by mass. , preferably 0.05% by mass or less, particularly preferably 0.01% by mass or less. Also, "106 μm remaining" refers to the ratio of particles remaining on the mesh without passing through the mesh with a pore opening of 106 μm.

By having such a particle size and viscosity distribution, when used as a filler for semiconductor packaging materials, especially liquid packaging materials for WLP semiconductor applications, high fluidity and good resistance to narrow parts can be obtained. permeability etc.

The silica powder of the present invention is spherical. Therefore, the resin composition has excellent fluidity when used as a filler for various resins. Here, the term "spherical" means that Wadell's practical circularity (circle equivalent diameter/maximum diameter) is 0.7 to 1.0. Here, the above-mentioned circle-equivalent diameter is defined as the projected cross-sectional area of the particle and the diameter of a circle having the same area, and the longest diameter is defined as the maximum distance between any two points on the projected outer periphery of the particle. The preferred Wadell practical circularity is 0.8~1.0. Silica usually produced by fusion method is spherical.

The silica powder of the present invention does not substantially contain air bubbles. Specifically, a part of the hardened body obtained by kneading and hardening silica powder and epoxy resin at a mass ratio of 1:1 was ground, and the exposed silica section was observed under a microscope at 1,000 magnifications The number of detectable air bubbles with a longest diameter of 5 μm or more is 50 or less per 10 cm ² of the polished surface of the hardened body.

When this evaluation method is described in more detail, it mixed and kneaded until it became uniform with respect to the room temperature hardening type epoxy resin so that the silica powder may become 50 mass %. Next, the kneaded product is filled in an appropriate mold so as not to trap air bubbles, and is cured at normal temperature. The mold for hardening is preferably a shape that can ensure a grinding surface of 1 cm ^or more when the hardened body is ground.

The hardened body that has been fully hardened is then partially ground to ensure the viewing surface. The polishing conditions are first rough grinding with diamond abrasive grains of about 1~3μm, and then using colloidal silica as the abrasive grains and setting the target of about 2 hours to polish the surface until the surface is not rough and shiny.

The obtained polished surface was observed under a microscope at 1000 magnifications. Any of an optical microscope, a polarizing microscope, and an electron microscope may be used as the microscope, and an optical microscope is preferred. In this microscope observation, it is necessary to observe an area of at least 1 cm ² or more in the grinding surface.

The cross section (polished surface) of the silica particles in the cured epoxy resin can be observed by the aforementioned grinding, so all the silica that can be identified in the observation range can be observed by the aforementioned microscope observation. Section and grasp whether there are bubbles. Then, the number of bubbles whose longest diameter (the distance between any two points on the circumference of the object, the maximum length) among the bubbles is 5 μm or more is counted. In addition, here, when one silica particle has a plurality of bubbles, the number of bubbles is calculated as a complex value, and the longest diameter of each bubble is measured.

The number of bubbles per 10 cm ² of the polished surface of the hardened body can be calculated from the number of bubbles with a longest diameter of 5 μm or more measured by such observation and the observed area.

The above-mentioned measurement of the number of bubbles can also be performed with the naked eye, but it is advantageous in terms of time and labor to perform the measurement using a digital microscope and image analysis software.

The number of bubbles with the longest diameter of 5 μm or more in the fused spherical silica powder of the present invention is preferably 10 or less, more preferably 5 or less, per 10 cm ² of the grinding surface of the hardened body. Also, the number of bubbles whose longest diameter is less than 5 μm is preferably as small as possible. However, since such tiny air bubbles tend to be embedded by the resist resin at the time of rewiring layer formation, their existence can be tolerated at the level of miniaturization of semiconductor wiring at the time of filing this application.

When the fused spherical silica powder of the present invention is considered to be used as a filler for semiconductor packaging materials, etc., the impurity content is preferably in the following range. That is, Fe is 10 ppm or less, preferably 7 ppm or less, Al is 0.7 ppm or less, preferably 0.6 ppm or less, U and Th are each 0.1 ppb or less, Na and K are each 1 ppm or less, and Cl is 1 ppm or less.

For the same reason, it is preferable that the fused spherical silica powder of the present invention does not contain ionic impurities. Therefore, the aqueous dispersion of molten spherical silica powder is preferably low in electrical conductivity and close to neutral in pH. Specifically, when 0.8g of silicon dioxide powder is dispersed in 80ml of pure water, the conductivity is preferably below 1.5μS/cm, more preferably below 1.4μS/cm, and more preferably below 1.3μS/cm. The pH is preferably 5.0~7.0, more preferably 5.5~7.0.

Also, the specific surface area obtained by the BET 1-point method using nitrogen gas is preferably 1~5m ² /g, more preferably 1.5~4m ² /g.

The fused spherical silica powder of the present invention preferably has less water content, specifically, less than 0.05% by mass, more preferably less than 0.02% by mass.

In order to improve the compatibility and reactivity with resin, the fused spherical silica powder of the present invention can also be treated with various surface treatment agents. Examples of the surface treatment agent include various silane compounds and silane coupling agents, titanate-based coupling agents, aluminate-based coupling agents, silicone oil, and the like.

Specific examples of silane compounds and silane coupling agents include hexamethyldisilazane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxy Silane, hexyltrimethoxysilane, decyltrimethoxysilane, phenyltrimethoxysilane, dimethyldiethoxysilane, dimethoxydiphenylsilane, 1,6-bis(trimethoxysilane base) hexane, trifluoropropyltrimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, 3-chloropropyltrichlorosilane, vinyltrimethoxysilane, ethylene Triethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3,(2.aminoethylamino)propylmethyldimethoxysilane, N-phenyl -3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, 3-glycidoxypropyltrimethoxysilane, 3-Glycidoxypropyltriethoxysilane, 3-Glycidoxypropylmethyldimethoxysilane, 3-Glycidoxypropylmethyldiethoxysilane, 2 -(3,4-Epoxycyclohexyl)ethyltrimethoxysilane, p-Styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methylpropene Acyloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxy Propyltrimethoxysilane, ginseng-(trimethoxysilylpropyl)isocyanurate, 3-ureapropyltrialkoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3 -Mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, etc.

The manufacturing method of the fused spherical silica powder of this invention is not limited, It can manufacture suitably using the following method. That is, the hydrophobized silica fume is used in a multi-layer tube burner, and oxygen or/oxygen-containing gas is accompanied by such that the ratio of the fume silica is 0.3kg/Nm ³ ~3kg/Nm ³ A method of recovering fused silica of 0.01 μm to 100 μm after being supplied from the central tube of the aforementioned multilayer tube burner and melted and spheroidized in a flame at 1400°C to 1700°C.

The fumed silica (also known as pyrogenic sillca, etc.) is used as a raw material, and it is hydrophobized. To the extent that the present inventors have studied, it is difficult to obtain the fused spherical silica powder of the present invention using hydrophilic fumed silica. The degree of hydrophobization should be such that the fume silica does not disperse in pure water at all, and the degree of hydrophobization (M value) using the methanol titration method is preferably at least 25% by volume, more preferably at least 30% by volume. Also, although Si powder, quartz powder, etc. can be used as raw materials to obtain fused spherical silica, when these are used as raw materials, the content of impurities in the obtained fused spherical silica tends to increase.

As a method of hydrophobization, the above-mentioned silanes (specifically, hexamethyldisilazane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, etc. are preferred) , the method of surface treatment of fumed silicon dioxide is preferred.

The particle properties of silicon dioxide used as a raw material are not particularly limited, but the specific surface area by the BET 1-point method of nitrogen adsorption is preferably 80-250 m ² /g, more preferably 100-230 m ² /g. Also, in order to reduce the amount of metal impurities in the molten spherical silica powder, it is better to have less impurity in the raw material silicon dioxide. Specifically, the contents of Fe, Al, U, Th, Na, and K are the same as those in the aforementioned The amount of metal impurities in the fused spherical silica powder is preferably equal to or less.

In the production method of the fused spherical silica powder of the present invention, the above-mentioned hydrophobized raw material fumed silica is melted in a flame, and the fused particles are fused to perform grain growth and spheroidization.

At the time of melting in the flame, etc., use a multi-layer tube burner and burn from the multi-layer tube with oxygen or/oxygen-containing gas in such a manner that the ratio of the raw material fume silica is 0.3kg/Nm ³ ~3kg/Nm ³ It is carried out by supplying the central tube of the device. As the multi-layer tube burner system, a two-layer tube burner, a three-layer tube burner, and the like can be used.

When the proportion of the raw material fumed silica supplied to the flame is too small, the proportion of particles below 1 μm in the obtained molten spherical silica powder becomes too large, and it tends to become a powder with a viscosity distribution that is not suitable for high filling body. Also, when the raw material fumed silica supplied to the flame is too much, it is likely to become a powder containing unmelted fumed silica particles, insufficiently melted particles with low sphericity, and the like. The ratio of the raw material fumed silica is preferably 0.5kg/Nm ³ -2.0kg/Nm ³ . Also, air is preferably used as the accompanying oxygen-containing gas.

When a multi-layer tube burner is used, for example, a three-layer tube burner, it is preferable to supply oxygen from two annular tubes and supply hydrogen from the outermost peripheral tube.

The flame temperature is set at 1400°C to 1700°C, preferably 1500°C to 1600°C. When the temperature is lower than 1400°C, it becomes a powder with insufficient fusion and spheroidization. On the other hand, when the temperature is higher than 1700°C, the cooling capacity must be increased because the process temperature rises, or the fuel consumption increases, resulting in increased manufacturing costs. Also, the higher the temperature, the stronger the tendency that the ratio of the small-diameter particles increases.

The flame temperature can be adjusted by the gas composition, supply rate, etc. of oxygen, hydrogen, nitrogen, etc. supplied to the burner.

In the production method of the fused spherical silica powder of the present invention, among the fused spherical silica powder generated in the flame, those having a particle diameter in the range of 0.01 μm to 100 μm are recovered. As a recovery method, first use a cyclone to recover particles with an average particle size of 0.01 μm to 1000 μm, and then use a sieve and/or a wind classifier to classify at a classification point of 8 μm to 100 μm to separate the fine particle side (below the classification point) The method of recovery is efficient and suitable. When using a sieve and/or wind classifier, it is better to set the classification point within the range of 10μm~50μm. By adjusting to such a classification point, it becomes easy to make the d95 of the fine grain side of the thing produced by the said method into the range of 5 micrometers - 30 micrometers. Also, since d95 does not fall within the range of 5 μm to 30 μm under all conditions, the conditions must be set appropriately according to the characteristics of the classifier used.

The advantage of recovery using a sieve is that there is virtually no possibility of recovering particles whose openings are larger than the sieve used. On the contrary, it takes a lot of time to recycle, and the industrial productivity is higher with the wind classifier. However, because the wind classifier also tends to recover a small amount of particles larger than the classification point, it also has the possibility of containing a small amount of particles with a particle size above the target upper limit. It is sufficient to recognize such advantages and disadvantages, and select appropriately according to the target particle size range, productivity, and the like. Moreover, it is also possible to classify using a sieve classifier and an air classifier in combination. Moreover, when classification is performed using a sieve, either dry classification or wet classification may be used.

Surface treatment of the fused spherical silica powder may be performed before classification using the above-mentioned sieve and/or air classifier, or after classification.

The surface treatment can be done by a known method according to the silane compound and silane coupling agent used, and it can be dry or wet. During surface treatment, especially wet surface treatment, since the particles may aggregate, it may be properly pulverized or further classified as necessary. By processing with a device that imparts mechanical stress, it is possible to obtain effects of agglomeration and crushing, adjustment of bulk density, and crushing of bubble-containing particles. Also, as a device for imparting mechanical stress, free vortex type centrifugal classifiers, forced vortex type centrifugal classifiers, ball mills, jet mills, two-roll mills, three-roll mills, stone mortar pulverizers, rotary paddle type Blender etc. [Example]

Hereinafter, examples and comparative examples are disclosed to describe the present invention more specifically, but the present invention is not limited by these examples.

In addition, the production conditions of fused spherical silica in Examples and Comparative Examples, and various physical property evaluation methods are as follows.

Hereinafter, a production method for producing fused silica will be described.

(1) Used in melting and spheroidizing of burners Using a three-layer tube burner, the raw material fumed silica and oxygen are supplied from the central tube, the oxygen is supplied from the second annular tube, and the hydrogen is supplied from the outermost peripheral tube. The flame temperature is adjusted by the hydrogen/oxygen ratio and the amount of silicon dioxide.

(2) Grading From the fused silica obtained above, the particles of 0.1 μm to 1000 μm are first recovered by a cyclone, and then the recovered silica is classified at a predetermined classification point using a wind classifier to separate the fine particle side Recycle.

Hereinafter, the physical property evaluation method will be disclosed.

(1) Hydrophobic degree (M value) of raw material fume silica

In a state where the raw material fume silica is floating on the surface of pure water, methanol is dropped while stirring. Find the amount of methanol required to suspend silicon dioxide in the total amount of pure water in volume %.

(2) Silica concentration

The silica concentration per unit volume was obtained by dividing the weight of silica introduced into the silica supply nozzle of the melting spheroidizing burner by the volume of oxygen supplied to the central tube.

(3) Flame temperature

The flame temperature of the burner is obtained by using the amount of hydrogen, oxygen, and fume silicon dioxide introduced into the silicon dioxide melting spheroidizing burner, and using the adiabatic flame temperature calculation formula.

(4) cumulative volume diameter

The cumulative volume 50% particle diameter (d50) and the 95% particle diameter (d95) were calculated by measuring with the aqueous dispersion medium using a laser diffraction scattering type viscosity distribution measuring device (MT-3300EX2) manufactured by Microtrac. Also, 250 mL of a dispersion medium and 0.02 g to 0.1 g of a sample were put into the sample slurry circulation tank of the measuring device. Next, after performing 40W ultrasonic dispersion for 1 minute while circulating the sample slurry, d50 and d95 were measured. Here, the above-mentioned sample input amount is adjusted in accordance with the instruction manual of the device so that the sample slurry concentration value (Sample Loading value) displayed on the screen of the personal computer for device control falls within 0.85 to 0.90.

(5) BET specific surface area

The specific surface area measuring device (SA-1000) manufactured by Shibata Rika Co., Ltd. was used to measure by the nitrogen adsorption BET 1-point method.

(6) Determination of Fe and A1 concentrations

The silicon dioxide particles were solubilized with hydrofluoric nitric acid, and measured by ICP emission spectrometry.

(7) Moisture Moisture in the silica particles was measured by the loss on drying method (at 110°C for 6 hours).

(8) Determination of pH and conductivity An aqueous dispersion of silica particles (8.0 g of silica/80 mL of pure water, 25° C.) was prepared, the pH was measured with a glass electrode method pH meter, and the conductivity was measured with an AC two-electrode method conductivity meter.

(9) U concentration The silica particles were solubilized with fluoronitric acid and measured using ICP-MS.

(10) Na ⁺ , Cl ^- concentration Silica particles were immersed in pure water at 110°C for 24 hours to prepare an eluting aqueous solution, and the Na ⁺ concentration was measured using an atomic absorption photometer, and the Cl ^- concentration was measured using ion chromatography.

(11) Viscosity of resin composition Epoxy resin (bisphenol A/F mixed resin ZX-1059 manufactured by Dongdu Chemical Co., Ltd.), and the silica particles of each example and comparative example were formulated at a ratio of silica 78: resin 22 (weight ratio), and the A revolving planetary gear mixer (AR-250 manufactured by THINKY Co.) was stirred with a stirring time of 8 minutes and a rotation speed of 1000 rpm, and further kneaded under the conditions of a defoaming time of 2 minutes and a rotation speed of 2000 rpm to obtain epoxy resin composition.

Next, the viscosity of the epoxy resin composition was measured on conditions of a temperature of 25° C., a plate gap of 50 μm, and a shear rate of 1 s ⁻¹ using a rheological viscometer (Rheostress RS600 manufactured by HAAKE).

(12) Number of bubbles contained Silica powder was mixed and kneaded until it became uniform with respect to room-temperature-curing epoxy resin (EpoxiCure 2 manufactured by BUEHLER company) so that it may become 50 mass %. Next, the kneaded product was filled into an embedding mold (plastic ring manufactured by BUEHLER, inner diameter 1 inch (25.4 mm)) so as not to entrap air bubbles, and fully hardened at room temperature.

Next, a part of the hardened body is ground to ensure a viewing surface. The grinding conditions are first rough grinding with abrasives with a particle size of 3 μm and 1 μm (METADI from BUEHLER, single crystal diamond suspension, water-based/abrasive particle size 3 μm, and then 1 μm) for rough grinding, and then with the abrasive for main grinding (MASTERMET2 colloidal silicon dioxide) is ground until a glossy finish is produced on the surface.

Using an optical microscope (MICROSCOPE VHX-5000 manufactured by KEYENCE Co., Ltd.), the range of 1 cm ² of the obtained polished surface was observed at 1000 times by epi-illumination/coaxial epi-illumination, and the longest diameter in the bubble was calculated ( Among the distances between any two points on the circumference of the object, the maximum length) is the number of 5 μm or more.

Also, here, when one silica particle has plural bubbles, it is counted as plural. This observation was performed using 10 samples, and the number of observed bubbles was totaled to calculate the number of bubbles per 10 cm ² of the cross-sectional area of the polished surface of the hardened body.

(13) Wadell Practical Circularity Put about 1 mg of silica powder on the center of a glass slide (2cm×4cm), add 2~3 drops of pure water to make a silica slurry, and place a cover glass on the slide so that air bubbles do not enter. Silicon oxide slurry is used to make preparations for observation. The prepared product was observed with an optical microscope DMLB (transmissive light source, 400 times magnification) manufactured by Leica, and the image of the silica particles was obtained using an image analyzer (Q500IW manufactured by Leica) to obtain the equivalent diameter/longest diameter per circle of each particle. . The measurement was repeated while moving the observation field of view until the number of measured particles reached a total of 500 or more, and the arithmetic mean value of the measured values was taken as the value of the Wadell's practical circularity of the silica powder.

Example 1 Using hydrophobic fumed silica with an M value of 47 and a BET specific surface area of 120m ² /g, the supply of fumed silica to the burner was set to 0.7kg/Nm ³ , and the flame The temperature was set to 1600° C. to obtain fused silica powder. Next, the obtained silica powder was collected after classification with a classification point of 10 μm. Table 1 shows the physical properties of the obtained fused spherical silica powder.

Use in embodiment 2~5 Using the hydrophobized fumed silica with the M value and BET specific surface area recorded in Table 1, the amount of silicon dioxide supplied, the flame temperature, and the classification point described in Table 1 were used, and molten spherical particles were produced in the same manner as in Example 1. Silica powder. Table 1 shows the physical properties of the obtained fused spherical silica powder.

Comparative Example 1 Use hydrophobic fumed silica with an M value of 47 and a BET specific surface area of 126m ² /g, set the supply rate of fumed silica to the burner at 0.3kg/Nm ³ , and set the flame temperature at 1800°C , Except that the classification point was 3 μm, fused silica was produced in the same manner as in Example 1. The physical properties of the obtained fused silica are shown in Table 1. Because the flame temperature is higher, the ratio of small particle size particles becomes higher, and the classification point at the time of manufacture is too small, so the d95 is smaller, so the resin composition Thickening during preparation was remarkable, and a resin composition could not be formed.

Comparative Example 2 Use hydrophobic fumed silica with an M value of 47 and a BET specific surface area of 115m ² /g, set the supply rate of fumed silica to the burner at 0.7kg/Nm ³ , and set the flame temperature at 1600°C , Except that the classification point was 5 μm, fused silica was produced in the same manner as in Example 1. The physical properties of the obtained fused silica are shown in Table 1. The d95 is small because the classification point at the time of manufacture is too small. Unlike Comparative Example 1, it was possible to form a resin composition, but it was remarkably high in viscosity.

However, when the fused silicas of Comparative Examples 1 and 2 are mixed with the fused silicas of Examples, it is considered that the viscosity of the resin composition becomes low and the number of bubbles is also reduced.

Comparative example 3 Fused silica was produced in the same manner as in Example 1, except that a hydrophilic substance (M value=0) was used as the raw material fumed silica. At this time, the number of bubbles contained was remarkably high.

Comparative Example 4 Fused silica was produced in the same manner as in Example 2, except that a substance having hydrophilicity (M value=0) and a BET specific surface area of 125 m ² /g was used as the raw material fume silica. At this time, the number of bubbles contained was remarkably high.

Comparative Example 5 When commercially available fused silica (d95: 29.5 μm, d50: 10 μm) was evaluated, the number of bubbles contained was remarkably high. Furthermore, by mixing and using the fused silica with a small particle size in Comparative Example 1 or 2 above, the large particle size and the small particle size particle are combined, although the filling characteristics are improved and the viscosity of the resin composition can be reduced, but It was determined that the number of bubbles contained could not be sufficiently reduced.

[Table 1]

1‧‧‧Dense silica particles 2‧‧‧Hollow silica particles 3‧‧‧The gap (recess) exposed by grinding

FIG. 1 is a schematic plan view showing a ground surface of a package. Fig. 2 is a sectional view along line A-A of Fig. 1 .

Claims (11)

A fused spherical silica powder, which is a fused spherical silica powder whose cumulative volume 95% particle size (d95) is in the range of 5 μm to 30 μm when measured by laser diffraction, characterized in that: The silica cross section exposed by grinding a part of the hardened body obtained by kneading and hardening the molten spherical silica powder and epoxy resin at a mass ratio of 1:1 can be detected under a microscope at 1,000 magnifications. The number of bubbles with a longest diameter of 5 μm or more is 50 or less per 10 cm ² of the polished surface of the hardened body. The fused spherical silica powder as described in item 1 of the scope of the patent application, wherein the surface of the particles is treated with a silane compound and/or a silane coupling agent. The fused spherical silica powder described in item 1 of the scope of the patent application, wherein the BET specific surface area is in the range of 1.0m ² /g~5.0m ² /g. The fused spherical silica powder as described in item 2 of the patent application, wherein the BET specific surface area is in the range of 1.0m ² /g~5.0m ² /g. The fused spherical silicon dioxide powder described in item 1 of the scope of application is used as a filling material for liquid semiconductor packaging materials. The fused spherical silicon dioxide powder described in item 2 of the scope of application is used as a filling material for liquid semiconductor packaging materials. The fused spherical silicon dioxide powder described in item 3 of the scope of the patent application is used as a filling material for liquid semiconductor packaging materials. A method for manufacturing the fused spherical silica powder as described in item 1 of the scope of the patent application, which is to use hydrophobization treatment until the hydrophobization degree (M value) of the methanol titration method is more than 25% by volume. Silicon oxide is supplied from the central tube of the multi-layer tube burner along with oxygen or/oxygen-containing gas in such a manner that the ratio of the aforementioned fumed silicon dioxide becomes 0.3 kg/Nm ³ ~3 kg/Nm ³ using a multi-layer tube burner. After melting and spheroidizing at 1400°C to 1700°C in a flame, fused silica of 0.01 μm to 100 μm is recovered. A method for manufacturing the fused spherical silica powder as described in item 3 of the scope of the patent application, which is to use hydrophobization treatment until the hydrophobization degree (M value) of the methanol titration method is more than 25% by volume. Silicon oxide is supplied from the central tube of the multi-layer tube burner along with oxygen or/oxygen-containing gas in such a manner that the ratio of the aforementioned fumed silicon dioxide becomes 0.3 kg/Nm ³ ~3 kg/Nm ³ using a multi-layer tube burner. After melting and spheroidizing at 1400°C to 1700°C in a flame, fused silica of 0.01 μm to 100 μm is recovered. The method for producing fused spherical silica powder as described in item 8 of the scope of the patent application, wherein, the method of recovering fused silica powder of 0.01 μm to 100 μm is to first use a cyclone to reduce the average particle size of 0.01 μm to 1000 μm The particles are recovered, and then, using a sieve and/or a wind classifier to classify at a classification point of 8 μm to 100 μm and recover the fine side. The method for producing fused spherical silica powder as described in item 9 of the scope of the patent application, wherein, the method of recovering fused silica powder of 0.01 μm to 100 μm is to first use a cyclone to reduce the average particle size of 0.01 μm to 1000 μm The particles are recovered, and then, using a sieve and/or a wind classifier to classify at a classification point of 8 μm to 100 μm and recover the fine side.