TW202106623A - Spherical crystalline silica particles, spherical silica particle mixture, and composite material - Google Patents

Abstract

To provide: spherical silica particles that have excellent dielectric properties and can have both excellent thermal properties and excellent fluidity; a spherical silica particle mixture; and a composite material. Provided are: spherical silica particles characterized by containing at least 60% in total of crystalline cristobalite phase and crystalline quartz phase in which the average size of the polycrystalline grains constituting the crystalline cristobalite phase or quartz phase is 2 [mu]m or more and a dielectric loss tangent at 10 GHz is 0.0020 or less as determined by the cut-off circular waveguide method (JIS R1660-1:2004); a spherical silica particle mixture containing the same; and a composite material.

Description

Spherical crystalline silica particles, mixtures of spherical silica particles and composite materials

The present invention relates to a spherical crystalline silicon dioxide particle with excellent dielectric properties suitable for forming a high-frequency signal corresponding to a high frequency of 3GHz or higher, and a high-frequency semiconductor sealing material and a wiring substrate, and spherical silicon dioxide containing the same Particle mixture and composite material formed by compounding it with resin.

As the amount of information increases with the advancement of communication technology, the use of millimeter wave bands such as millimeter wave radar is rapidly expanding, and the frequency is gradually increasing. The semiconductor for processing these high-frequency signals and the circuit substrate for transmission are composed of electrodes and dielectrics in circuit patterns. For high-speed signal transmission, it is important to suppress the propagation delay of the signal, so a low relative permittivity (εr) is required. In addition, in order to suppress the energy loss during signal transmission, the dielectric tangent (tanδ) of the dielectric material must be small. To make the dielectric loss low, the dielectric material must have low polarity and low dipole moment. In addition to these dielectric properties, thermal properties such as thermal conductivity and thermal expansion coefficient are very important due to the suppression of heat generation and thermal expansion of the IC chip when mounting the substrate, and the mechanical properties are also important. Very important.

Dielectric materials mainly use ceramic fillers, resins and composite materials made of these composites. Especially with the expansion of the use of the millimeter wave band in recent years, ceramic fillers and resins with lower εr and lower tanδ are required. The εr of resin is small and suitable for high frequency, but the tanδ and thermal expansion coefficient are larger than ceramic filler. Therefore, the composite material formed by compounding the filler for the millimeter wave band and the resin is suitable for (1) low εr and low tanδ of the ceramic filler itself, and (2) high filling of the ceramic filler to reduce the amount of resin showing large tanδ.

For ceramic fillers, silicon dioxide (SiO ₂ ) particles have been used in the past. If the shape of the silicon dioxide particles is angular, the fluidity, dispersibility, and filling properties in the resin will deteriorate, and the manufacturing device will gradually wear out. To improve this situation, spherical silica particles are widely used today. This is because it is believed that the closer the spherical silica filler is to the real ball, the better the filling, fluidity, and mold abrasion resistance. Therefore, fillers with high roundness have been pursued so far. In addition, it has been studied to further improve the filling performance by seeking the appropriate particle size distribution of the filler. However, if the filling rate is excessively increased through the spheroidization of the filler shape and the appropriateness of the particle size distribution, the fluidity of the composite material as a sealing material will decrease, and the formability will deteriorate. To ensure high fluidity, it is difficult to increase the filling rate of silica filler to 85% by mass or more, and it has been limited to less than 85% by mass in the past.

The manufacturing method of spherical silica is known as spraying. In the thermal spraying, the crushed silica particles used as the raw material are passed through a flame above 2000°C to melt the particles, and the shape of the particles will become spherical due to surface tension. In addition, air transport is performed so that the melted and spheroidized particles are recovered without being welded to each other, and the melted particles will be rapidly cooled. Due to the rapid cooling from the molten state, the silica (fused silica) has an amorphous (amorphous) structure.

Since the spherical molten silica is amorphous, its thermal expansion rate and thermal conductivity are low. The thermal expansion rate of amorphous silicon dioxide is 0.5ppm/K, and the thermal conductivity is 1.4W/mK. These physical properties are approximately the same as the thermal expansion coefficient of quartz glass that does not have a crystalline structure but has an amorphous (amorphous) structure. Therefore, the effect of reducing the thermal expansion of the sealing material itself can be obtained by mixing with a resin with a high thermal expansion rate. As a sealing material, by making the thermal expansion coefficient of the composite material close to the value of Si, it is possible to suppress the deformation due to the thermal expansion behavior when sealing the IC chip.

However, the thermal expansion coefficient of the sealing material (composite material) made of excessively high filling of amorphous silicon dioxide with low thermal expansion coefficient may become smaller than that of Si, and may be affected by the heating temperature during reflow or the semiconductor device. Warping or cracking occurs due to the operating temperature. In addition, due to the low thermal conductivity, the dissipation of heat generated by the semiconductor device is also a problem.

As mentioned above, the properties required for silica fillers corresponding to high frequencies above 3GHz must show excellent dielectric properties and meet the filling properties that can be blended into resin in large quantities to maintain the performance as a sealing material. Fluidity, thermal properties, mechanical strength performance and mold abrasion resistance are all requirements, but the silica filler and silica-resin composite material does not exist.

In view of the foregoing, the present inventors intend to provide a device/substrate for 5G (fifth generation mobile communication system) with a frequency of 3GHz or higher, and an automotive radar that uses a millimeter wave band of 60GHz or higher. Ceramic filler with electrical characteristics (spherical silica particles).

Prior art literature Patent literature Patent Document 1: International Publication No. 2016/031823 Patent Document 2: International Publication No. 2018/186308

The object of the present invention is to provide spherical silicon dioxide particles, spherical silicon dioxide particle mixtures and composite materials that have excellent dielectric properties and can also have excellent thermal properties and fluidity.

Means to solve the problem The inventors of the present invention have made great efforts to conduct research with the objective of solving the above-mentioned problems. As a result, it was found that to prepare silicon dioxide particles with excellent dielectric properties such as low dielectric constant and low dielectric tangent, and excellent thermal properties such as high thermal conductivity and high thermal expansion rate, the effective method is to melt the spherical (amorphous) (Quality) Silicon dioxide undergoes heat treatment to crystallize it to form a specific crystal structure. That is, the spherical silicon dioxide particles of the present invention have been confirmed for the first time that the dielectric tangent at high frequencies above 3 GHz is significantly lower than that of amorphous ones and exhibits high thermal conductivity, thus completing the present invention.

Invention effect The spherical silicon dioxide particles of the present invention have a specific crystalline structure, so they have excellent dielectric properties (low dielectric constant and low dielectric tangent), and are more excellent than conventional spherical crystalline silicon dioxide particles The thermal characteristics (). In addition, due to its spherical shape and narrow particle size distribution, it can achieve high roundness, so it has both high fluidity/high dispersion and high filling properties, so it can be used as a filler for semiconductors for high-frequency signal transmission. , Substrate, etc.

According to the present invention, the following aspects can be provided. [1] A spherical silica particle characterized by comprising a total of 60% or more of a crystalline white silica phase and a crystalline quartz phase, constituting the average of the polycrystalline crystal grains of the crystalline white silica phase or the quartz phase The diameter is 2 μm or more, and the dielectric tangent at 10 GHz calculated by the cut-off cylindrical waveguide method (JIS R1660-1: 2004) is 0.0020 or less. [2] The spherical silicon dioxide particles as in [1], which contain more than 0.5% by mass and less than 2.0% by mass in terms of aluminum in terms of oxides. [3] The spherical silica particles of [1] or [2], wherein the ratio of the crystalline quartz phase in the aforementioned spherical silica particles is 30% or more. [4] The spherical silica particles according to any one of [1] to [3], wherein the roundness of particles with a particle diameter of 10 μm or more among the aforementioned spherical silica particles is 0.83 or more. [5] A mixture of spherical silica particles, characterized by comprising: 95% by mass or more and 99.9% by mass or less, such as the spherical silica particles in any one of [1] to [4], and 0.1 mass % Or more and less than 5 mass% of ultrafine particles with an average particle size of 0.1 μm or less. [6] A composite material characterized by containing 85% by mass or more and 95% by mass or less of spherical silica particles such as any one of [1] to [4] in a resin.

The crystalline structure of silicon dioxide (SiO ₂ ) includes white silica, quartz, tridymite and so on. Compared with amorphous silicon dioxide, silicon dioxide with these crystalline structures has a higher thermal expansion rate and thermal conductivity. Therefore, by replacing the molten (amorphous) silicon dioxide with an appropriate amount of crystalline silicon dioxide, the thermal expansion difference between it and the IC chip can be suppressed, and the thermal conductivity can be improved. In addition, by optimizing the particle size distribution of fused (amorphous) silica and crystalline silica, silica fillers (spherical silica particles) exhibiting higher filling properties can be prepared.

The spherical silica particles of the present invention contain a total of 60% or more of a crystalline white silica phase and a crystalline quartz phase (hereinafter sometimes collectively referred to as "crystalline phase"). That is, the content of the crystalline phase in the spherical silica particles is 60% or more. As long as it is above 60%, it will exhibit excellent dielectric properties. On the whole, the higher the ratio of crystalline silica, the better the dielectric properties. Silicon dioxide other than crystalline silicon dioxide is amorphous. The crystalline phase may be one of a crystalline white silica phase or a crystalline quartz phase, or a crystalline white silica phase and a crystalline quartz phase coexist. In addition, the spherical silica particles of the present invention may contain crystalline tridymite in addition to the crystalline white silica phase and the crystalline quartz phase.

The abundance ratio of crystalline phases such as white silica and quartz can be measured by, for example, X-ray diffraction (XRD). When measuring by XRD, the sum (Ic) of the integrated intensity of the crystalline peaks and the integrated intensity (Ia) of the amorphous halo can be calculated using the following formula.

X (crystal ratio)=Ic/(Ic+Ia)×100　　　(%)

The ratios of the various crystal phases in the crystal phases contained in the spherical silica particles of the present invention are those determined by XRD according to the key points described below, unless otherwise specified. The crystalline quartz phase uses the peak data of PDF 33-1161, the crystalline white silica phase uses the peak data of PDF11-695, and the crystalline tridymite phase uses the peak data of PDF18-1170. From the integrated intensity of each peak The ratio of sum is calculated by mass ratio to calculate the ratio of each crystal phase. In addition, the peak positions of the maximum intensity derived from the white silica phase and the tridymite phase are very close. Therefore, the peaks can be separated to calculate the intensity, or the peaks after the second highest intensity can be calculated based on the intensity ratio of the pdf data. Use it for calculation after correction.

The aforementioned crystalline white silica phase and crystalline quartz phase are composed of a plurality of microcrystals, that is, composed of polycrystalline crystal grains. In the spherical silica particles of the present invention, the average diameter of the polycrystalline grains is 2 μm or more. Here, the average diameter is obtained by inserting a sample into a resin and cutting out a cross section, and then averaging the area weighted by the area of the polycrystalline grains exposed in the cross section. For crystalline silicon dioxide, it can be expected that its thermal conductivity is higher than that of amorphous silicon dioxide. However, if the polycrystalline grain size is too small, the scattering of the grain boundary will make it impossible to obtain sufficient thermal conductivity. Therefore, in order to obtain sufficient thermal conductivity, the average diameter of the polycrystalline grain size must be 2 μm or more.

In the spherical silica particles of the present invention, the polycrystalline crystal grain size (average diameter) is measured by EBSD method (Electron Back Scatter Diffraction Pattern) after crystalline powder is dispersed and filled in epoxy resin and the cross section is cut. .

In addition, in order to verify the effect of improving the thermal conductivity of the spherical silica particles of the present invention, the resin and the spherical silica particles of the present invention can be kneaded to form a thermal conductive sheet, and then the thermal conductivity can be measured. First, spherical silica particles and polysiloxane resin (CY52-276A/B manufactured by Dow Corning Corporation) were mixed at a filler rate of 80% by mass, and evacuated to 5 Torr or less for kneading. Then it is molded with a mold. The mold is heated to 120°C and closed at 6~7MPa for 40 minutes. The resin composition was taken out from the mold and cured at 140°C for 1 hour. After cooling to room temperature, the resin composition was sliced into thicknesses of 1.5, 2.5, 4.5, 6.5, 7.5, and 8.5 mm, and processed into 2 cm square sheet samples. The thermal resistance of each sample is measured in accordance with ASTM D5470. The sample was sandwiched with a SUS304 block and compressed at 0.123 MPa, and the thickness after compression was recorded. The relationship between the thermal resistance value obtained in the above method and the thickness after compression can be linearly approximated, and the thermal conductivity can be derived from the slope.

Regarding the spherical silica particles of the present invention, the dielectric tangent at 10 GHz calculated by the cut-off cylindrical waveguide method (JIS R1660-1: 2004) is 0.0020 or less. Although not limited to a specific theory, it is speculated that the spherical silica particles of the present invention have the above-mentioned crystal structure (crystal phase ratio and polycrystalline grain size), and have a dielectric tangent much lower than that of amorphous ones. High thermal conductivity can be obtained.

The method of measuring the dielectric constant and dielectric tangent of the spherical silica particles of the present invention will be described. The measurement is performed using composite materials. The composite material is made by using spherical silicon dioxide particle powder and epoxy resin (YX-4000H manufactured by Mitsubishi Chemical) at a temperature of 100℃ with a two-roll mill to knead 0, 30, 50, and 50 to the epoxy resin. 83~89% by mass of spherical silica particles. The kneaded sample is crushed with a mortar and pestle. Fill the pulverized sample into a mold (50φ) and set it in a pressing machine. After pressing at a molding temperature of 175°C at 1 MPa for about 1 minute, it was maintained at 5 MPa for 9 minutes. After that, the mold is moved to water-cooled pressing, and after cooling for about 10 minutes, the hardened spherical silica particles-epoxy resin board (silicon dioxide-resin board) is taken out of the mold. Cut the produced silicon dioxide-resin board with a peripheral blade and process it to approximately 10mm×10mm. In order to change the thickness of the hardened silicon dioxide-resin board, it is ground with high-precision surface grinding (SGM-5000 manufactured by Hidewa Kogyo), and the thickness varies between 0.2mm and 1.0mm. The dielectric properties are measured by measuring the above-mentioned silica-resin composite in the 10 GHz band according to the cut-off cylindrical waveguide method (JIS R1660-1: 2004). According to the relationship between epoxy resin and spherical silica particles of 0, 30, 50, 83~89 mass% relative to epoxy resin and the relationship between the dielectric tangent, 100% of spherical silica particles are extrapolated The value obtained is used as the dielectric tangent of the spherical silica particles.

The manufacturing method of the spherical silica particles of the present invention will be described.

The spherical silica particles of the present invention can be filled with silica particle powder (amorphous) produced by the spray method in the atmosphere into a container made of alumina, and the heat treatment temperature is 800°C to 1600°C. The following is manufactured with a heat treatment time of 50 minutes to 16 hours and treatment in an atmospheric environment. The preferred heat treatment time is 1-12 hours. If it is less than 1 hour, the crystallization may not be sufficient, and if the heat treatment time of more than 12 hours is required, the burden on the manufacturing cost will increase. To promote the crystallization of white silica, a small amount of Al can be added and processed at 900°C to 1600°C. By adjusting the processing temperature and time, the abundance ratio of amorphous and crystalline silica (white silica phase and quartz phase) can be controlled.

Here, the addition amount of Al is preferably more than 0.5% by mass and 2.0% by mass or less in terms of oxides. As long as it is within this range, it is possible to obtain spherical silica particles that have sufficient crystallinity and suppressed increase in alkalinity and specific gravity due to Al. If it is 0.5% by mass or less, the crystallinity tends to decrease. If it is greater than 2.0% by mass, the alkali content rises and the specific gravity rises significantly. As a result, it will adversely affect the curing properties of the resin, and it may become difficult to apply to the pursuit. The trend of lightweight mobile devices and automotive applications.

In addition, in Patent Document 1 and Patent Document 2, the amount of aluminum added is limited to 5000 ppm by mass (0.5% by mass) in terms of oxides. To achieve sufficient crystallization, heat treatment at a higher temperature and a long time is required. A situation where particles become easy to fuse.

To promote the crystallization of quartz, if a trace amount of alkali metal or alkaline earth metal is added and treated at a low temperature of 800~1150℃ compared with the crystallization temperature of white silica, quartz will appear as the main phase. The addition amount of alkali metals and alkaline earth metals can be 0.1-3% by mass in terms of oxides. If it is too small, Quartzization cannot be promoted, and if it is too large, the purity of the silica particles will decrease. Examples of alkali metals and alkaline earth metals include lithium, sodium, potassium, rubidium, cesium, thorium, beryllium, magnesium, calcium, strontium, barium, and radium. From the viewpoint of the efficiency of promoting quartzization, Li and Ca are preferred. In addition, the content of aluminum, alkali metals, and alkaline earth metals can be measured by, for example, atomic absorption spectroscopy and ICP mass analysis (ICP-MS).

In one aspect of the present invention, the ratio of the crystalline quartz phase in the spherical silica particles may be 30% by mass or more. The white silica has a phase transition point between a low temperature phase and a high temperature phase at 200-250°C. Therefore, it is actually accompanied by a large thermal expansion, which may sometimes cause obstacles depending on the application. If this point is important, the quartz phase is preferably 30% by mass or more. The phase transition point between the low-temperature phase and the high-temperature phase of quartz is above 500°C, so it will not cause practical hindrance. As long as it falls within this range, spherical silicon dioxide particles having thermal expansion characteristics suitable for semiconductor packages can be produced. If it is less than 30% by mass, the thermal expansion due to the phase change of the white silica phase becomes too large.

The spherical silicon dioxide particle (amorphous) powder used as the raw material of the spherical silicon dioxide particle of the present invention can be manufactured by the spray method. Specifically, a device is used to produce spherical silicon dioxide particles (amorphous) powder by thermal spraying. The device uses a combustible gas supply tube, a combustion-supporting gas supply tube, and a crushed high-purity two The burner of the tube structure composed of the silica (quartz) supply tube is installed on the top of the manufacturing furnace, and the lower part of the manufacturing furnace is connected to a collection system (the powder is sucked by a blower and collected by a bag filter). In addition, LPG is supplied from the combustible gas supply pipe and oxygen is supplied from the combustion-supporting gas supply pipe, thereby forming a high-temperature flame in the manufacturing furnace. In addition, crushed silicon dioxide powder (quartz) is supplied from the silicon dioxide supply pipe, and spherical silicon dioxide powder is collected by a bag filter. The roundness of spherical silica particles obtained by thermal spraying can be 0.83 or more. The higher the roundness, the better the fluidity, so the roundness should be above 0.83. As long as the spray method is used, particles with high roundness can be easily obtained. In order to make the spherical silica particles obtained by spraying have a roundness of 0.83 or more, the raw silicon dioxide powder must be melted into a spherical shape. Therefore, the flame temperature during spraying must be set higher than that of the Silicon will melt at a higher temperature. In order to obtain spherical silica with higher roundness, the flame temperature should be above 2000°C. In addition, if the silica particles come into contact with each other during the thermal spraying, the particles will bond to each other and easily become distorted. Therefore, it is advisable to disperse the raw materials in a gas stream to supply or adjust the supply amount when supplying the raw materials into the flame.

In addition, the roundness of the spherical silica particles of the present invention hardly decreases before and after the heating treatment for crystallization, and the roundness of the spherical silica particles (amorphous) obtained by thermal spraying can be maintained. .

。 投影面積係進行影像處理來計算，如圖1，將粒子進行2值影像化等影像處理後，用直線連結粒子輪廓部之各像素單元的中央，定義為所包圍住的面積。測定裝置的物鏡係因應像素數選定為0.5-1μm/pixel左右。In this manual, unless otherwise specified, the roundness is measured using the FPIA-3000 manufactured by Malvern Panalytical Company for 6000 pieces of 10um or more in size. If the size below 10um is included in the measurement, the overall resolution of the measurement device will be insufficient, and the calculated roundness may be higher. At this time, roundness cannot be used as an indicator of fluidity. Therefore, the roundness is measured for the size of 10 μm or more. First, put 10g of powder sample such as silicon dioxide particles to be measured and 200ml of distilled water into a beaker, and use an ultrasonic homogenizer to set the ultrasonic wave to a frequency of 20~30kHz and 150~500W for dispersion treatment for more than 30 seconds. , Disperse it fully. After the beaker after dispersion was allowed to stand still for 1 minute, 180 ml of the supernatant side was removed, and new distilled water was added to make it 200 ml. After taking out the required amount with a pipette, etc., it is measured with an optical measuring device. The particle size is defined by the circle equivalent diameter. This is the diameter of a circle with an area equal to the projected area on the measured image, and is calculated by the following: [Math. 1]

. The projected area is calculated by image processing. As shown in Figure 1, after the particles are subjected to image processing such as binary imaging, the center of each pixel unit of the particle outline is connected by a straight line, and the area is defined as the enclosed area. The objective lens of the measuring device is selected to be about 0.5-1μm/pixel according to the number of pixels.

One aspect of the present invention provides a mixture of spherical silica particles containing 95% by mass or more and 99.9% by mass or less of the aforementioned spherical silica particles, and an average of 0.1% by mass or more and 5% by mass or less Ultrafine particles with a particle size of 0.1μm or less. If the spherical silica particles of the present invention are appropriately blended with ultrafine particles of less than 0.1 μm, the filling rate of the spherical silica particles can be improved when the spherical silica particles are used as a filling material. The reason is that the ultrafine particles enter the gap between the spherical silica particles, and the volume occupied by the gap is reduced, thereby increasing the filling rate. The blending ratio of spherical silica particles and ultrafine particles should be 95% by mass or more and 99.9% by mass or less for spherical silica particles, and the ultrafine particles should be 0.1% by mass or more and 5% by mass or less. . If the ratio of ultrafine particles is too low, the gaps between spherical silica particles cannot be filled, and the filling rate will not increase. If the ratio of ultrafine particles is too high, they will overflow from the gaps between spherical silica particles and increase the overall volume. Here, the so-called ultrafine spherical silica particles refer to those having a particle size of 0.1 μm or less. It is possible to separate the particles with a particle size of 0.1 μm or less (ultrafine particles) in the manufacturing step of spherical silica particles, and to blend a predetermined amount of ultrafine particles when the final product is formed. In addition, the particle size distribution of spherical silica particles can also be adjusted. By adjusting the particle size distribution of the crushed silica powder (quartz) used as the raw material for thermal injection, the particle size distribution of the spherical silica particles (amorphous) after thermal injection can be adjusted. Through the heat treatment for crystallization, the spherical silica particles obtained will be slightly different from the spherical silica particles (amorphous) in particle size distribution. However, by predicting the change in particle size distribution or in the follow-up The sieving in the step can also adjust the particle size distribution of the spherical silica particles of the present invention. The average particle size (D50) of the silica particles of the present invention can also be 1-100 μm. If the average particle size is greater than 100μm, when it is used as a filler for semiconductor sealing materials, the particle size may become too thick, which may easily cause gate clogging or mold wear. If the average particle size is less than 1μm, it will There are cases where the particles become too small to be filled in large quantities. The preferred upper limit of the average particle size is 50 μm, more preferably 40 μm. On the other hand, the lower limit of the average particle diameter is preferably 3 μm, more preferably 5 μm. In addition, the average particle size here can be calculated by measuring the particle size distribution by the wet laser diffraction method (laser diffraction scattering method). Here, the average particle size is referred to as the median particle size, and the particle size distribution is measured by the laser diffraction method, and the particle size with the cumulative particle size frequency of 50% is taken as the average particle size (D50).

In this specification, unless otherwise specified, the average particle size of the particle size distribution of spherical silica particles and ultrafine particles is calculated by measuring the particle size distribution by the laser diffraction method. The particle size distribution obtained by the laser diffraction method can be measured using, for example, CILAS920 manufactured by CILAS Corporation. Here, the average particle size is referred to as the median particle size. The particle size distribution is measured by a laser diffraction method or the like, and the average particle size (D50) is the particle size whose particle size frequency accumulates to 50%.

In addition, one aspect of the present invention can provide a composite material of the aforementioned spherical silica particles and resin. In order to improve the dielectric properties of the composite material, an effective method is to increase the filling rate (filler filling rate) of the silica filler in the resin composite material and reduce the amount of resin with poor low dielectric constant characteristics (such as epoxy resin). The composite material of the present invention can maintain high fluidity and achieve a filler filling rate of more than 85% by mass and less than 95% by mass. In order to ensure high fluidity, it is difficult to set the filling rate of silica filler to 85% by mass or more. In the past, it has been limited to less than 85% by mass. However, if the silica particles of the present invention are appropriately blended with ultrafine particles of less than 0.1μm , Can further improve the filling rate. Generally speaking, if the filler filling rate is increased, the fluidity will decrease. However, if the addition amount of ultrafine particles of 0.1μm or less is set to 0.1% by mass or more and 5% by mass or less, it is possible to achieve both high filling properties and high fluidity. Thereby, a composite of silica filler and resin can be obtained. The composite is suitable for high frequency frequency and has low dielectric constant and dielectric tangent. However, if the filling rate of the silica filler is greater than 95% by mass, the amount of resin becomes relatively small and it is difficult to obtain a resin composite material.

One aspect of the present invention includes the composite material of the aforementioned spherical silica particles and resin. The composition of the composite material is explained. When the slurry composition is used to manufacture a resin substrate such as a package substrate or an interlayer insulating film, it is preferable to use an epoxy resin as the resin. The epoxy resin is not particularly limited, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, naphthalene type epoxy resin, phenoxy Basic epoxy resin, etc. One of these may be used alone, or two or more kinds having different important molecular weights may be used in combination, and one or two or more kinds may be used. Among these epoxy resins, bisphenol A type epoxy resins are particularly preferred from the viewpoint of availability and disposal.

For example, when manufacturing semiconductor-related materials such as package substrates or interlayer insulating films, well-known resins can be used as the resin used in the resin composite composition, and epoxy resins are preferably used. The epoxy resin is not particularly limited. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, naphthalene can be used. Type epoxy resin, phenoxy type epoxy resin, etc. One of these may be used alone, or two or more kinds having different molecular weights may be used in combination. Among these, from the viewpoint of curability, heat resistance, etc., epoxy resin having two or more epoxy groups in one molecule is preferred. Specific examples include: biphenyl type epoxy resin, phenol novolac type epoxy resin, o-cresol novolac type epoxy resin, products obtained by epoxidizing phenolic and aldehyde phenolic resins, bisphenol A, bisphenol Glycidyl ethers such as F and bisphenol S, glycidyl ester acid epoxy resins, linear aliphatic epoxy resins obtained by the reaction of polybasic acids such as phthalic acid or dibasic acid and epichlorohydrin Resin, alicyclic epoxy resin, heterocyclic epoxy resin, alkyl modified polyfunctional epoxy resin, β-naphthol novolac epoxy resin, 1,6-dihydroxynaphthalene epoxy resin, 2, 7-dihydroxynaphthalene type epoxy resin, bishydroxybiphenyl type epoxy resin, and epoxy resin introduced with halogen such as bromine in order to impart flame retardancy. Among the epoxy resins having two or more epoxy groups in one molecule, bisphenol A type epoxy resins are particularly preferred.

In addition, for applications other than composite materials for semiconductor sealing materials, for example, resins used in resin composite compositions such as prepregs for printed circuit boards and various engineering plastics can also be applied to resins other than epoxy resins. Specifically, in addition to epoxy resins, polysiloxane resins, phenol resins, melamine resins, urea resins, unsaturated polyesters, fluororesins, polyimides, polyimides, and polyethers can be cited. Polyamides such as imines; polyesters such as polybutylene terephthalate and polyethylene terephthalate; polyphenylene sulfide (Polyphenylene sulfide), aromatic polyester, polysulfide, liquid crystal polymer, Polyether ash, polycarbonate, maleimide modified resin, ABS resin, AAS (acrylonitrile-acrylic rubber-styrene) resin, AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin .

To harden the aforementioned resin, a well-known hardener may be used, and a phenol-based hardener may be used. The phenolic curing agent may be used alone or in combination of two or more kinds of phenol phenol resin, alkyl phenol phenol resin, polyvinyl phenol, and the like.

The blending amount of the aforementioned phenolic hardener is preferably such that the equivalent ratio of the epoxy resin (phenolic hydroxyl equivalent/epoxy equivalent) is less than 1.0 and more than 0.1. Thereby, no unreacted phenol hardener remains, and the moisture absorption and heat resistance are improved.

The amount of spherical silica particles to be blended into the composite material is as large as possible from the viewpoint of heat resistance and thermal expansion rate. Relative to the overall mass of the composite material, it is usually 70% by mass or more and 95% by mass or less, and preferably 80% by mass or more and 95% by mass or less, more preferably 85% by mass or more and 95% by mass or less. . The reason is that if the mixing amount of silica powder is too small, it will be difficult to improve the strength of the sealing material and inhibit thermal expansion. On the contrary, if it is too much, it will be easily caused by the composite material regardless of the surface treatment of the silica powder. The segregation caused by the agglomeration of silica powder and the viscosity of the composite material have become too large, making it difficult to be used as a sealing material.

In addition, as the silane coupling agent, a well-known silane coupling agent may be used, and one having an epoxy-based functional group is preferred. Example

The present invention is illustrated by the following examples and comparative examples. However, the present invention is not limited and interpreted by the following examples.

[Example 1-4] The spherical molten (amorphous) silica particles with an average particle diameter of 29μm were produced by the spray method. The calcium oxide and aluminum oxide are blended in the raw material powder at the time of spraying so that the calcium concentration and aluminum concentration in the silica particles become 1% by mass and 0.6% by mass in terms of oxides, respectively. And put the prepared silicon dioxide particles into an alumina container, and perform a heat treatment at 1400-900°C. Table 1 lists the conditions of each example and the measurement results obtained in detail.

[Example 5-8] The spherical molten (amorphous) silica particles with an average particle diameter of 9μm were produced by the spray method (the addition amount of ultrafine particles below 0.1μm is 3.0 mass), except that the same method as in Example 1-4 , Put the prepared silicon dioxide particles into an alumina container, and perform a heat treatment at 1400-900°C. Table 1 lists the conditions of each example and the measurement results obtained in detail.

[Comparative Example 1-4] The spherical molten (amorphous) silica particles with an average particle diameter of 29μm were produced by the spray method. Calcium oxide and aluminum oxide are blended in the raw material powder at the time of spraying so that the calcium concentration and aluminum concentration in the silica particles become <0.01% by mass and 0.1% by mass in terms of oxides, respectively. And put the prepared silicon dioxide particles into an alumina container, and perform a heat treatment at 1400-900°C. Table 2 lists the conditions of each comparative example and the measurement results obtained in detail.

[Comparative Example 5-8] Spherical molten (amorphous) silica particles with an average particle diameter of 9μm were produced by the spray method. Calcium oxide and aluminum oxide are blended in the raw material powder at the time of spraying so that the calcium concentration and aluminum concentration in the silica particles become <0.01% by mass and 0.1% by mass in terms of oxides, respectively. And put the prepared silicon dioxide particles into an alumina container, and perform a heat treatment at 1400-900°C. Table 2 lists the conditions of each comparative example and the measurement results obtained in detail.

[Example 3, 9-10, Comparative Example 9] Except for the heat treatment time, spherical silica particles were produced under the same conditions as in Example 3. And the spherical silicon dioxide particles produced were filled with 80% by mass in polysiloxane resin as described above, and the EBSD of the cross-sectional sample was used to measure the polycrystalline grain size distribution. And the thermal conductivity is measured from a sample cut from the same sample. Under the conditions of Comparative Example 9, the crystal grain growth was insufficient, and the thermal conductivity showed a slightly worse result, but in Examples 3, 9 and 10, sufficient thermal conductivity was obtained. The conditions and measurement results are summarized in Table 3.

[Comparative Example 10-11] For the same post-sprayed silicon dioxide used in Example 3, the aluminum concentration was changed to 0.4% by mass (Comparative Example 10) and 0.2% by Mass (Comparative Example 11) in terms of oxides, and the The crystallization was carried out under the same heat treatment conditions as in Example 3. As a result, Comparative Examples 10 and 11 showed a result that the amorphous ratio was relatively high.

[Table 1]

[Table 2]

[table 3]

[Table 4]

Figure 1 is a diagram illustrating the calculation of the particle's shooting area and circumference.

Claims (6)

A spherical silica particle characterized in that it contains a total of 60% or more of a crystalline white silica phase and a crystalline quartz phase, and the average diameter of the polycrystalline grains constituting the crystalline white silica phase or the quartz phase is 2 μm The above, and the dielectric tangent at 10 GHz calculated by the cut-off cylindrical waveguide method (JIS R1660-1: 2004) is 0.0020 or less. For example, the spherical silica particles of claim 1, which contain more than 0.5% by mass and less than 2.0% by mass in terms of aluminum in terms of oxides. Such as the spherical silica particles of claim 1 or 2, wherein the ratio of the crystalline quartz phase in the aforementioned spherical silica particles is 30% or more. The spherical silica particles according to any one of claims 1 to 3, wherein the roundness of particles with a particle size of 10 μm or more among the aforementioned spherical silica particles is 0.83 or more. A mixture of spherical silica particles, characterized by comprising: 95% by mass or more and 99.9% by mass or less of spherical silica particles as in any one of claims 1 to 4, and 0.1% by mass or more and less than 5 Ultrafine particles with an average particle size of 0.1μm or less with mass% or less. A composite material characterized in that it contains 85% by mass or more and 95% by mass or less of spherical silica particles according to any one of claims 1 to 4 in a resin.

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