CN113905984A - Spherical crystalline silica particles, spherical silica particle mixture, and composite material - Google Patents
Spherical crystalline silica particles, spherical silica particle mixture, and composite material Download PDFInfo
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- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/02—Granular materials, e.g. microballoons
- C04B14/04—Silica-rich materials; Silicates
- C04B14/06—Quartz; Sand
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- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
Abstract
Provided are spherical silica particles, a mixture of spherical silica particles, and a composite material, which have excellent dielectric properties and can also have excellent thermal properties and flowability. Spherical silica particles, and a spherical silica particle mixture and a composite material containing the same, characterized by containing 60% or more of a crystalline cristobalite phase and a crystalline quartz phase in total, the average diameter of polycrystalline crystal grains constituting the crystalline cristobalite phase or the quartz phase being 2 μm or more, and the dielectric loss tangent at 10GHz, as determined by the cut-off cylinder waveguide method (JIS R1660-1: 2004), being 0.0020 or less.
Description
Technical Field
The present invention relates to spherical crystalline silica particles having excellent dielectric characteristics suitable for forming a semiconductor sealing material and a wiring board for high frequency signals having a frequency of 3GHz or higher, a spherical silica particle mixture containing the particles, and a composite material obtained by compounding the spherical silica particle mixture with a resin.
Background
With the increase in the amount of information accompanying the advancement of communication technologies and the rapid expansion of the use of millimeter wave bands such as millimeter wave radars, the frequency has been increased. The semiconductor for processing these high-frequency signals and the circuit board for transmission are composed of electrodes and a dielectric, which are formed into a circuit pattern. In high-speed transmission of signals, it is important to suppress propagation delay of signals, and therefore a low relative dielectric constant (∈ r) is required. In addition, in order to suppress energy loss during signal transmission, the dielectric material needs to have a small dielectric loss tangent (tan δ). To achieve low dielectric loss, 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 important from the viewpoint of suppressing heat generation from the IC chip and mismatch with the thermal expansion of the electrode material when mounting the substrate, and mechanical properties are also important for high flexural strength and the like.
As the dielectric material, a ceramic filler, a resin, and a composite obtained by combining these materials are mainly used. In particular, as the use of millimeter wave bands has been expanded in recent years, ceramic fillers and resins having a low ∈ r and a low tan δ have been demanded. The ε r of the resin is small and suitable for high frequency, but tan δ and the thermal expansion coefficient are larger than those of the ceramic filler. Therefore, in a composite in which a filler for a millimeter wave band is compounded with a resin, it is preferable that (1) the ceramic filler itself is reduced in er and tan δ, and (2) the ceramic filler is highly filled to reduce the amount of the resin exhibiting a large tan δ.
Silica (SiO) has been conventionally used as a ceramic filler2) And (3) granules. If the silica particles are angular in shape, the flowability, dispersibility, and filling property in the resin are deteriorated, and abrasion of the production apparatus progresses. To improve these, spherical silica particles are widely used. It is considered that the closer the spherical silica filler is to a true sphere, the higher the filling property, fluidity and mold wear resistance are, and a filler having a high circularity has been desired. Further, it has been studied to further improve the filling property by optimizing the particle size distribution of the filler. However, if the filling ratio is excessively increased by spheroidizing the filler shape and optimizing the particle size distribution, the fluidity of the composite as a sealing material is reduced and the moldability is deteriorated. In order to ensure high fluidity, it is difficult to achieve a silica filler filling rate of 85 mass% or more, and the silica filler filling rate has conventionally been limited to less than 85 mass%.
Melt blowing is known as a method for producing spherical silica. In melt blowing, crushed silica particles as a raw material are passed through a flame at 2000 ℃ or higher to melt the particles, and the shape of the particles becomes spherical due to surface tension. The molten and spheroidized particles are recovered by air-stream conveyance so that the particles do not thermally adhere to each other, and the molten and spheroidized particles are quenched. Since the silica (fused silica) is rapidly cooled from the molten state, the silica (fused silica) has an amorphous (noncrystalline) structure.
Since the spherical fused silica is amorphous, its thermal expansion coefficient and thermal conductivity are low. The amorphous silica had a thermal expansion coefficient of 0.5ppm/K and a thermal conductivity of 1.4W/mK. These properties are substantially equal to the thermal expansion coefficient of quartz glass having an amorphous structure (amorphous structure) without having a crystalline structure. Therefore, by mixing the resin having a high thermal expansion coefficient, an effect of reducing the thermal expansion of the sealing material itself is obtained. By setting the thermal expansion coefficient of the composite material to a value close to Si as the sealing material, deformation due to thermal expansion behavior can be suppressed when the IC chip is sealed.
However, in a sealing material (compound) obtained by excessively filling amorphous silica having a low thermal expansion coefficient, the thermal expansion coefficient may be smaller than that of Si, and warpage or cracks may occur due to a heating temperature at the time of reflow or an operating temperature of a semiconductor device. In addition, since the thermal conductivity is low, the heat generated from the semiconductor device is also problematic to be dissipated.
As described above, as the properties required for the silica filler for high frequency of 3GHz or more, it is required to satisfy all the requirements such as excellent dielectric properties and ability to maintain the filling property, flowability, thermal properties, mechanical strength properties and mold wear resistance as a sealing material by blending a large amount of the silica filler in a resin, but such a silica filler and silica-resin composite are not present.
In view of such circumstances, the present inventors have aimed to provide a ceramic filler (spherical silica particles) having excellent dielectric characteristics in devices and substrates for 5G (5 th generation mobile communication system) having a frequency of 3GHz or more, and in-vehicle radars and the like using a millimeter wave band of 60GHz or more.
Prior art documents
Patent document
Patent document 1: international publication No. 2016/031823
Patent document 2: international publication No. 2018/186308
Disclosure of Invention
Technical problem to be solved by the invention
The present invention aims to provide spherical silica particles, a mixture of spherical silica particles, and a composite material, which have excellent dielectric properties and can also have excellent thermal properties and flowability.
Means for solving the problems
The present inventors have conducted intensive studies with a view to solving the above-mentioned problems. As a result, it has been found that it is effective to heat treat spherical molten (amorphous) silica to crystallize the silica and form a specific crystal structure in order to obtain silica particles having both excellent dielectric properties such as low dielectric constant and low dielectric loss tangent and excellent thermal properties such as high thermal conductivity and high thermal expansion coefficient. That is, it was confirmed for the first time that the spherical silica particles of the present invention have a significantly reduced dielectric loss tangent at a high frequency of 3GHz or more and a high thermal conductivity as compared with amorphous silica, and the present invention was completed.
Effects of the invention
The spherical silica particles of the present invention have a specific crystal structure, and therefore have excellent dielectric properties (low dielectric constant and low dielectric loss tangent) and also have excellent thermal properties () compared with conventional spherical crystalline silica particles. In addition, since the spherical shape and the narrow particle size distribution can improve the circularity, the high fluidity/high dispersibility and the high filling property are achieved at the same time. Therefore, the filler can be suitably used for a semiconductor, a substrate, or the like for transmitting a high-frequency signal.
Drawings
Fig. 1 is a diagram illustrating calculation of the imaging area and the circumference of a particle.
Detailed Description
According to the present invention, the following means is provided.
[1]
Spherical silica particles comprising a crystalline cristobalite phase and a crystalline quartz phase in a total amount of 60% or more, wherein the average diameter of polycrystalline crystal grains constituting the crystalline cristobalite phase or the quartz phase is 2 μm or more, and the dielectric loss tangent at 10GHz, as determined by the cut-off cylindrical waveguide method (JIS R1660-1: 2004), is 0.0020 or less.
[2]
The spherical silica particles according to [1], which comprise more than 0.5 mass% and not more than 2.0 mass% of aluminum in terms of oxide.
[3]
The spherical silica particles according to [1] or [2], wherein the ratio of the crystalline silica phase in the spherical silica particles is 30% or more.
[4]
The spherical silica particles according to any one of [1] to [3], wherein particles having a particle diameter of 10 μm or more have a circularity of 0.83 or more.
[5]
A mixture of spherical silica particles, comprising: 95 to 99.9 mass% of the spherical silica particles according to any one of [1] to [4 ]; and 0.1 to 5% by mass of ultrafine particles having an average particle diameter of 0.1 μm or less.
[6]
A composite material characterized by containing the spherical silica particles according to any one of [1] to [4] in a resin in an amount of 85 to 95 mass%.
As silicon dioxide (SiO)2) The crystal structure of (a) is cristobalite, quartz, tridymite, or the like. Silica having these crystalline structures has high thermal expansion and thermal conductivity compared to amorphous silica. Therefore, by replacing the fused (amorphous) silica with crystalline silica in an appropriate amount, the thermal conductivity can be improved while suppressing the difference in thermal expansion with the IC chip. Further, by optimizing the particle size distribution of the fused (amorphous) silica and the crystalline silica, a silica filler (spherical silica particles) further exhibiting high filling property can be obtained.
The spherical silica particles of the present invention contain 60% or more of a crystalline cristobalite phase and a crystalline quartz phase in total (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. When the content is 60% or more, excellent dielectric characteristics are exhibited. In general, the dielectric characteristics are improved as the proportion of crystalline silicon dioxide is increased. Silica other than crystalline silica is amorphous. The crystalline phase may be either a crystalline cristobalite phase or a crystalline quartz phase, and the crystalline cristobalite phase and the crystalline quartz phase may coexist. The spherical silica particles of the present invention may contain crystalline tridymite phase and crystalline quartz phase, as well as crystalline tridymite phase.
The presence ratio of the crystalline phase such as cristobalite or quartz can be measured by X-ray diffraction (XRD), for example. When the measurement is performed by XRD, the sum (Ic) of the integrated intensities of the crystalline peaks and the integrated intensity (Ia) of the amorphous halo portion can be calculated by the following formula.
X (crystalline phase ratio) ═ Ic/(Ic + Ia) × 100 (%)
The ratio of each crystal phase in the crystal phases contained in the spherical silica particles of the present invention is measured by XRD in the following manner unless otherwise specified. The ratio of each crystal phase was calculated as a mass ratio from the data of peaks of the crystalline quartz phase using PDF33-1161, the crystalline cristobalite phase using PDF11-695, and the crystalline tridymite phase using PDF18-1170, based on the ratio of the sum of the integrated intensities of the respective peaks. Further, since peak positions of maximum intensities from the cristobalite phase and the tridymite phase are close to each other, the intensity can be calculated by separating peaks, or the peak of the intensity of the 2 nd or later can be corrected based on the intensity ratio of pdf data and used for calculation.
The crystalline cristobalite phase and the crystalline quartz phase are composed of a plurality of crystallites, i.e., polycrystalline 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 cutting a cross section of a sample after resin filling, and averaging the areas of polycrystalline grains appearing in the cross section by area weighting. Crystalline silica can be expected to have high thermal conductivity as compared with amorphous silica, but when the grain size of the polycrystal is excessively small, sufficient thermal conductivity cannot be obtained due to scattering caused at grain boundaries. Therefore, in order to obtain sufficient thermal conductivity, the average diameter of the polycrystalline grain size needs to be 2 μm or more.
In the spherical silica particles of the present invention, the polycrystalline grain size (average diameter) is measured by an EBSD method (Electron Back Scatter Diffraction Pattern) after dispersing and filling the crystal powder in the epoxy resin, and cutting the cross section.
In order to verify the effect of improving the thermal conductivity of the spherical silica particles of the present invention, a resin may be kneaded with the spherical silica particles of the present invention to prepare a heat conductive sheet, and the thermal conductivity of the heat conductive sheet may be measured. First, spherical silica particles and a silicone resin (CY 52-276A/B, manufactured by Dow Corning corporation) were mixed at a filler content of 80 mass%, and the mixture was vacuum-degassed to 5Torr or less and kneaded. Then, the molded article is molded in a mold. And heating the die to 120 ℃, closing the die at 6-7 MPa, and forming for 40 minutes. The resin composition was taken out of the mold and cured at 140 ℃ for 1 hour. After cooling to room temperature, the resin composition was cut into pieces having thicknesses of 1.5, 2.5, 4.5, 6.5, 7.5 and 8.5mm, respectively, and processed into 2 cm-square plate-like samples. Each sample was tested for thermal resistance according to ASTM D5470. The sample was sandwiched by SUS304 blocks and compressed at 0.123MPa, and the thickness after compression was recorded. The relationship between the thermal resistance value and the thickness after compression thus obtained is linearly approximated, and the thermal conductivity can be derived from the slope thereof.
The spherical silica particles of the present invention have a dielectric loss tangent at 10GHz of 0.0020 or less as determined by the cut-off cylindrical waveguide method (JIS R1660-1: 2004). Without wishing to be bound by a particular theory, it is believed that the spherical silica particles of the present invention have a dielectric loss tangent that is greatly reduced as compared with an amorphous material and a high thermal conductivity by having the above-described crystal structure (ratio of the crystal phase and size of the polycrystalline grains).
The method for measuring the dielectric constant and dielectric loss tangent of the spherical silica particles of the present invention will be described. The determination was carried out using a composite material. The composite material was produced by kneading spherical silica particles in an amount of 0, 30, 50, 83 to 89 mass% based on the epoxy resin (YX-4000H, Mitsubishi chemical corporation) with a two-roll mill at a temperature of 100 ℃ using a powder of spherical silica particles and the epoxy resin. The kneaded sample was pulverized with a mortar and pestle. In a mold
The pulverized sample was filled and set in a press. After pressing at 1MPa for about 1 minute at a molding temperature of 175 ℃, the sheet was held at 5MPa for 9 minutes. After that, the mold was moved to a water-cooling press, and after cooling for about 10 minutes, the cured spherical silica particle-epoxy resin plate (silica-resin plate) was taken out from the mold. The silica-resin plate thus produced was cut with a peripheral knife and processed into about 10mm × 10 mm. In order to change the thickness of the cured silica-resin plate, grinding was carried out by high precision flat grinding (UX and SGM-5000, manufactured by Industrial Co., Ltd.) so that the thickness varied from 0.2mm to 1.0 mm.
Measurement of dielectric characteristics the silica-resin composite was measured at a frequency band of 10GHz according to the shielded cylindrical waveguide method (JIS R1660-1: 2004). The dielectric loss tangent of spherical silica particles was determined by extrapolating the value of 100% of spherical silica particles from the relationship between the dielectric loss tangent and the composite of spherical silica particles at 0, 30, 50, 83 to 89% by mass relative to the epoxy resin.
The method for producing spherical silica particles of the present invention will be explained.
The spherical silica particles of the present invention can be produced as follows: silica particle powder (amorphous) produced by the atmospheric meltblowing method is filled in a container made of alumina, and the heat treatment is performed at a heat treatment temperature of 800 to 1600 ℃ for 50 minutes to 16 hours in an atmospheric atmosphere. The preferable heat treatment time is 1 to 12 hours. If the time is less than 1 hour, crystallization may be insufficient, and if the heat treatment time is required to exceed 12 hours, the burden of production cost increases. In order to promote the crystallization of cristobalite, a small amount of Al may be added and the treatment may be carried out at 900 to 1600 ℃. By adjusting the treatment temperature and time, the existence ratio of amorphous and crystalline silica (cristobalite phase and quartz phase) can be controlled.
Here, the amount of Al added is preferably more than 0.5 mass% and 2.0 mass% or less in terms of oxide. When the amount is within this range, spherical silica particles having a sufficient degree of crystallization and suppressed increase in alkali content, increase in specific gravity, and the like due to Al can be obtained. If the amount is 0.5% by mass or less, the crystallinity tends to decrease, and if it exceeds 2.0% by mass, the increase in alkali content and the increase in specific gravity become significant, and as a result, the resin curing properties tend to be adversely affected, and the resin composition tends to be difficult to apply to mobile devices or vehicle-mounted applications requiring weight reduction.
In patent documents 1 and 2, the amount of aluminum added is limited to 5000 mass ppm (0.5 mass%) or less in terms of oxide, and a heat treatment at a higher temperature for a long time is required to achieve sufficient crystallization, and the pellets are likely to be thermally bonded to each other.
In the case of promoting the crystallization of quartz, quartz appears as a main phase when a small amount of an alkali metal or an alkaline earth metal is added and the quartz is treated at 800 to 1150 ℃ which is lower than the crystallization temperature of cristobalite. The amount of the alkali metal or alkaline earth metal added may be 0.1 to 3% by mass in terms of oxide. If too small, the quartz reaction is not promoted, and if too large, the purity of the silica particles is lowered. Examples of the alkali metal and alkaline earth metal include: lithium, sodium, potassium, rubidium, cesium, francium, beryllium, magnesium, calcium, strontium, barium, radium. From the viewpoint of efficiency of promoting the crystallization, Li and Ca are more preferable. The contents of aluminum, alkali metal, and alkaline earth metal can be measured by, for example, atomic absorption spectrometry or ICP mass spectrometry (ICP-MS).
In one embodiment of the present invention, the ratio of the crystalline silica phase in the spherical silica particles may be 30% by mass or more. Since cristobalite has a phase transition point between a low-temperature phase and a high-temperature phase at 200-250 ℃, it involves a large thermal expansion in practical use, and may be an obstacle depending on the application. When importance is attached to such a point, the quartz phase is preferably 30 mass% or more. Since the transformation point of the low-temperature phase and the high-temperature phase is 500 ℃ or higher, quartz does not become a practical obstacle. Within this range, spherical silica particles having thermal expansion characteristics suitable for semiconductor packages can be obtained. If less than 30 mass%, the thermal expansion caused by the phase transition of the cristobalite phase becomes excessive.
The spherical silica particles (amorphous) powder as a raw material of the spherical silica particles of the present invention can be produced by a melt-blowing method. Specifically, spherical silica particles (amorphous) powder is produced by melt-blowing using an apparatus in which a burner having a tube structure composed of a combustible gas supply tube, a combustion-supporting gas supply tube, and a crushed high-purity silica (quartz) supply tube is provided at the top of a production furnace, and the lower part of the production furnace is connected to a collection system (the generated powder is sucked by a blower and collected by a bag filter). LPG is supplied from a combustible gas supply pipe, and oxygen is supplied from a combustion-supporting gas supply pipe, thereby forming a high-temperature flame in the production furnace. Crushed silica powder (quartz) was supplied from a silica supply tube, and spherical silica powder was collected by a bag filter. The circularity of the spherical silica particles obtained by melt blowing can be 0.83 or more. The higher the circularity, the higher the fluidity, and therefore the circularity is preferably 0.83 or more. In the melt-blowing method, particles having a high circularity can be easily obtained. In order to set the circularity of spherical silica particles obtained by melt-blowing to 0.83 or more, it is necessary to form the silica powder as a raw material into a molten state to form a spherical shape, and therefore the temperature of the flame at the time of melt-blowing needs to be higher than the temperature at which silica is melted. In order to obtain spherical silica having a higher circularity, the flame temperature is preferably 2000 ℃ or higher.
Further, if the silica particles are brought into contact with each other at the time of melt blowing, the particles are bonded to each other and easily form an irregular shape, and therefore, it is preferable to supply the raw material to the flame in a gas flow so that the raw material is dispersed or to adjust the supply amount.
The spherical silica particles of the present invention can maintain the circularity of the spherical silica particles (amorphous particles) obtained by melt-blowing, without substantially decreasing the circularity before and after the above-described heat treatment for crystallization.
Unless otherwise specified, the circularity was measured at 6000 sizes of 10um or more using FPIA-3000 manufactured by marvensapaneco. If measurement is performed including a size of 10um or less, the resolution of the measurement device is generally insufficient, and the circularity may be calculated to be high. In this case, the circularity cannot be used as an index of fluidity. Therefore, the circularity was measured for a size of 10 μm or more. First, 10g of a powder sample such as silica particles to be measured and 200ml of distilled water are put in a beaker, and ultrasonic waves are applied to the sample by an ultrasonic homogenizer at a frequency of 20 to 30kHz of 150 to 500W for 30 seconds or more to disperse the sample sufficiently. The dispersed beaker was allowed to stand for 1 minute, 180ml of the supernatant side was discarded, and distilled water was newly added to make it 200 ml. The required amount is taken out therefrom by a pipette or the like, and measured by an optical measuring device. The particle size is defined as the equivalent circle diameter. This is the diameter of a circle having an area equal to the projected area on the measurement image, and is calculated by equation 1.
[ numerical formula 1]
The projected area is calculated by image processing, and as shown in fig. 1, the particle is subjected to image processing such as binary imaging, and the centers of the pixel cells in the outline of the particle are connected by a straight line to define an enclosed area. The objective lens of the measuring device is selected to be about 0.5-1 μm/pixel according to the number of pixels.
In one aspect of the present invention there is provided a mixture of spherical silica particles comprising: 95 to 99.9 mass% of the spherical silica particles; and 0.1 to 5% by mass of ultrafine particles having an average particle diameter of 0.1 μm or less.
When ultrafine particles having a particle size of 0.1 μm or less are appropriately blended with the spherical silica particles of the present invention, the filling ratio can be improved when the spherical silica particles are used as a filler. This is because the ultrafine particles enter the gaps between the spherical silica particles, and the volume occupied by the gaps is reduced, thereby increasing the filling ratio. The mixing ratio of the spherical silica particles and the ultrafine particles is preferably 95 mass% or more and 99.9 mass% or less for the spherical silica particles, and 0.1 mass% or more and 5 mass% or less for the ultrafine particles. If the ratio of ultrafine particles is too low, gaps between spherical silica particles are not filled, and the filling ratio is not increased. If the ratio of ultrafine particles is too high, the particles will overflow from the gaps between the spherical silica particles, and the overall volume will increase.
Herein, ultrafine particles mean particles that are spherical silica particles and have a particle diameter of 0.1 μm or less. In the production process of spherical silica particles, particles (ultrafine particles) having a particle diameter of 0.1 μm or less can be separated, and the ultrafine particles can be blended in a predetermined amount in the final production.
In addition, the particle size distribution of the spherical silica particles can be adjusted. The particle size distribution of the spherical silica particles (amorphous particles) after melt-blowing can be adjusted by adjusting the particle size distribution of the crushed silica powder (quartz) used in the melt-blowing raw material. The spherical silica particles obtained by the heat treatment for crystallization may have a slightly different particle size distribution from the spherical silica particles (amorphous particles), but the particle size of the spherical silica particles of the present invention can also be adjusted by predicting the amount of change in the particle size distribution, or by predicting the sieve content in the subsequent step, or the like. The silica particles of the present invention may have an average particle diameter (D50) of 1 to 100 μm. If the average particle size exceeds 100. mu.m, the particle size becomes too large when used as a filler for a semiconductor sealing material or the like, and gate clogging and mold wear may be easily caused, while if the average particle size is less than 1 μm, the particles become too fine and a large amount of the filler may not be filled. A more preferable upper limit of the average particle diameter is 50 μm, and a further more preferable upper limit is 40 μm. On the other hand, a more preferable lower limit of the average particle diameter is 3 μm, and still more preferably 5 μm. The average particle diameter can be determined by particle size distribution measurement by a wet laser diffraction method (laser diffraction scattering method).
The average particle diameter referred to herein is referred to as a median particle diameter, and the particle diameter distribution is measured by a laser diffraction method, and the particle diameter at which the frequency of the particle diameters is 50% in a cumulative manner is referred to as an average particle diameter (D50).
In the present specification, unless otherwise specified, the average particle diameter of spherical silica particles, ultrafine particles, and the like, which is related to the particle size distribution, is determined by particle size distribution measurement by a laser diffraction method, or the like. The particle size distribution by the laser diffraction method can be measured by CILAS920, manufactured by CILAS corporation, for example. The average particle diameter referred to herein is referred to as a median particle diameter, and the particle diameter distribution is measured by a method such as a laser diffraction method, and the particle diameter in which the frequency of the particle diameters is 50% in a cumulative manner is referred to as an average particle diameter (D50).
In one aspect of the present invention, a composite material of the spherical silica particles and a resin is provided.
In order to improve the dielectric characteristics of the composite material, it is effective to increase the filling rate of the silica filler in the resin composite (filler filling rate) and to reduce the amount of resin having poor low dielectric constant characteristics (for example, epoxy resin). In the composite material of the present invention, a filler filling rate of 85 mass% or more and less than 95 mass% can be achieved while maintaining high fluidity. In order to ensure high fluidity, it has been difficult to achieve a silica filler filling rate of 85 mass% or more, and it has been limited to less than 85 mass%, but if ultrafine particles of 0.1 μm or less are appropriately blended in the silica particles of the present invention, the filling rate can be further improved. Generally, if the filler filling ratio is increased, the fluidity is lowered, but if the addition amount of ultrafine particles having a particle size of 0.1 μm or less is 0.1 mass% or more and 5 mass% or less, both high filling property and high fluidity can be achieved. This makes it possible to obtain a composite of a resin and a silica filler having a low dielectric constant and a low dielectric loss tangent, which is suitable for increasing the frequency. However, if the silica filler filling rate exceeds 95 mass%, the amount of the resin decreases relatively, and it is difficult to obtain a resin composite.
In one aspect of the present invention, a composite material comprising the spherical silica particles and a resin. The composition of the composite material is explained. When a resin substrate such as a substrate for sealing or an interlayer insulating film is produced using the paste composition, an epoxy resin is preferably used as the resin. The epoxy resin is not particularly limited, and examples thereof include: bisphenol a type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, naphthalene type epoxy resin, phenoxy type epoxy resin, and the like. One of these may be used alone, two or more species having different important molecular weights may be used in combination, or one or two or more species may be used. Among these epoxy resins, bisphenol a type epoxy resins are particularly preferable from the viewpoint of availability and workability.
For example, in the case of manufacturing a semiconductor-related material such as a substrate for sealing or an interlayer insulating film, a known resin can be used as the resin used in the resin composite composition, but an epoxy resin is preferably used. The epoxy resin is not particularly limited, and for example, there can be used: bisphenol a type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, naphthalene type epoxy resin, phenoxy type epoxy resin, and the like. One of these may be used alone, or two or more species having different molecular weights may be used in combination. Among these, an epoxy resin having 2 or more epoxy groups in 1 molecule is preferable from the viewpoint of curability, heat resistance, and the like. Specifically, there may be mentioned: biphenyl type epoxy resins, phenol novolac type epoxy resins, o-cresol novolac type epoxy resins, epoxy resins obtained by epoxidizing phenol and aldehyde novolac type resins, glycidyl ester acid epoxy resins obtained by the reaction of glycidyl ethers such as bisphenol a, bisphenol F and bisphenol S, polybasic acids such as phthalic acid or dimer acid, and epichlorohydrin, linear aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, alkyl-modified polyfunctional epoxy resins, β -naphthol novolac type epoxy resins, 1, 6-dihydroxynaphthalene type epoxy resins, 2, 7-dihydroxynaphthalene type epoxy resins, bishydroxybiphenyl type epoxy resins, and epoxy resins into which a halogen such as bromine is introduced for imparting flame retardancy. Among these epoxy resins having 2 or more epoxy groups in 1 molecule, bisphenol a type epoxy resins are also particularly preferable.
In addition, in applications other than composite materials for semiconductor sealing materials, for example, resins other than epoxy resins can be used as resins used in resin composite compositions such as prepregs for printed boards and various engineering plastics. Specifically, in addition to the epoxy resin, there can be mentioned: polyamides such as silicon resin, phenol resin, melamine resin, urea resin, unsaturated polyester, fluorine resin, polyimide, polyamideimide, and polyetherimide; polyesters such as polybutylene terephthalate and polyethylene terephthalate; polyphenylene sulfide, aromatic polyester, polysulfone, liquid crystal polymer, polyethersulfone, polycarbonate, maleimide-modified resin, ABS resin, AAS (acrylonitrile-propylene rubber-styrene) resin, AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin.
For curing the resin, a known curing agent may be used, and a phenol-based curing agent may also be used. As the phenol-based curing agent, phenol novolac resin, alkylphenol novolac resin, polyvinyl phenol, or the like can be used alone or in combination.
The equivalent ratio of the phenolic curing agent to the epoxy resin (phenolic hydroxyl group equivalent/epoxy group equivalent) is preferably less than 1.0 and 0.1 or more. This eliminates the residue of the unreacted phenol curing agent, thereby improving the moisture absorption heat resistance.
From the viewpoint of heat resistance and thermal expansion coefficient, it is preferable that the amount of spherical silica particles to be blended in the composite material is large. It is usually preferably 70% by mass or more and 95% by mass or less, preferably 80% by mass or more and 95% by mass or less, and more preferably 85% by mass or more and 95% by mass or less, based on the entire mass of the composite material. This is because if the amount of silica powder blended is too small, it is difficult to obtain the effects of improving the strength of the sealing material, suppressing thermal expansion, and the like, and conversely, if it is too large, segregation due to aggregation of silica powder is likely to occur in the composite material regardless of the surface treatment of the silica powder, and the viscosity of the composite material is also likely to be too large, which makes it difficult to put the sealing material into practical use.
As the silane coupling agent, a known coupling agent can be used, but a silane coupling agent having an epoxy functional group is preferable.
Examples
The present invention will be explained by the following examples and comparative examples. However, the present invention is not limited to the following examples.
[ examples 1 to 4]
Spherical fused (amorphous) silica particles having an average particle diameter of 29 μm were produced by a melt-blowing method. Calcium oxide and aluminum oxide were added to the raw material powder during melt blowing so that the calcium concentration and the aluminum concentration in the silica particles were 1 mass% and 0.6 mass%, respectively, in terms of oxides. The prepared silicon dioxide particles are put into an alumina container and are subjected to heat treatment at 1400-900 ℃. The conditions of the examples and the measurement results obtained are shown in detail in table 1.
[ examples 5to 8]
In the same manner as in examples 1-4 except that spherical fused (amorphous) silica particles having an average particle diameter of 9 μm were produced by the melt-blowing method (the amount of ultrafine particles having a particle diameter of 0.1 μm or less was 3.0 mass), the produced silica particles were placed in an alumina container and subjected to a heat treatment at 1400 ℃. degree.900 ℃. The conditions of the examples and the measurement results obtained are shown in detail in table 1.
Comparative examples 1 to 4
Spherical fused (amorphous) silica particles having an average particle diameter of 29 μm were produced by a melt-blowing method. Calcium oxide and aluminum oxide were added to the raw material powder during melt blowing so that the calcium concentration and the aluminum concentration in the silica particles were < 0.01 mass% and 0.1 mass%, respectively, in terms of oxides. The prepared silicon dioxide particles are put into an alumina container and are subjected to heat treatment at 1400-900 ℃. The conditions of the comparative examples and the measurement results obtained are shown in detail in table 2.
Comparative examples 5to 8
Spherical fused (amorphous) silica particles having an average particle diameter of 9 μm were produced by a melt-blowing method. Calcium oxide and aluminum oxide were added to the raw material powder during melt blowing so that the calcium concentration and the aluminum concentration in the silica particles were < 0.01 mass% and 0.1 mass%, respectively, in terms of oxides. The prepared silicon dioxide particles are put into an alumina container and are subjected to heat treatment at 1400-900 ℃. The conditions of the comparative examples and the measurement results obtained are shown in detail in table 2.
Examples 3, 9 to 10 and comparative example 9
Spherical silica particles were produced under the same conditions as in example 3 except for the heat treatment time. Further, as described above, the prepared spherical silica particles were filled in the silicone resin by 80 mass%, and the polycrystalline size distribution was measured by EBSD of the cross-sectional sample. In addition, thermal conductivity was measured using samples cut out from the same samples. Under the conditions of comparative example 9, the crystal grains were insufficiently grown, resulting in a slightly inferior thermal conductivity, but sufficient thermal conductivity was obtained in examples 3, 9, and 10. These conditions and measurement results are shown in Table 3.
Comparative examples 10 to 11
In the same post-melt-blown silica as used in example 3, the aluminum concentration was changed to 0.4 mass% (comparative example 10) and 0.2 mass% (comparative example 11) in terms of oxide, and crystallization was performed under the same heat treatment conditions as in example 3. As a result, the amorphous content was high in comparative examples 10 and 11.
[ Table 1]
[ Table 2]
[ Table 3]
[ Table 4]
Claims (6)
1. A spherical silica particle characterized in that,
contains a crystalline cristobalite phase and a crystalline quartz phase in a total amount of 60% or more, and polycrystalline crystal grains constituting the crystalline cristobalite phase or the quartz phase have an average diameter of 2 μm or more and are expressed by JIS R1660-1: the dielectric loss tangent at 10GHz, which is determined by the method for cutting a cylindrical waveguide defined in 2004, is 0.0020 or less.
2. The spherical silica particles of claim 1,
the aluminum is contained in an amount exceeding 0.5 mass% and 2.0 mass% or less in terms of oxide.
3. Spherical silica particles according to claim 1 or 2,
the ratio of the crystalline quartz phase in the spherical silica particles is 30% or more.
4. Spherical silica particles according to any one of claims 1 to 3,
the spherical silica particles have a circularity of 0.83 or more, and particles having a particle diameter of 10 μm or more.
5. A mixture of spherical silica particles, characterized in that,
comprises the following steps: the spherical silica particles according to any one of claims 1 to 4, wherein the amount of the spherical silica particles is 95 to 99.9 mass%; and 0.1 to 5% by mass of ultrafine particles having an average particle diameter of 0.1 μm or less.
6. A composite material, characterized in that,
the spherical silica particles according to any one of claims 1 to 4 are contained in the resin in an amount of 85 mass% or more and 95 mass% or less.
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| JP2022117128A (en) * | 2021-01-29 | 2022-08-10 | 信越化学工業株式会社 | High-speed communication low-dielectric constant substrate for millimeter waves |
| TW202337826A (en) * | 2021-12-13 | 2023-10-01 | 日商日鐵化學材料股份有限公司 | Spherical crystalline silica particles, method for producing same, and resin composite composition and resin composite containing same |
| WO2023153357A1 (en) * | 2022-02-09 | 2023-08-17 | デンカ株式会社 | Spherical silica powder |
| WO2023189589A1 (en) * | 2022-03-28 | 2023-10-05 | デンカ株式会社 | Inorganic powder, method for producing same, and resin composition |
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| JP2005231973A (en) * | 2004-02-23 | 2005-09-02 | Sumitomo Chemical Co Ltd | Silica particle and method of manufacturing the same |
| CN106660813A (en) * | 2014-08-25 | 2017-05-10 | 新日铁住金高新材料株式会社 | Spherical crystalline silica particles and method for producing same |
| JP6374138B2 (en) * | 2016-04-28 | 2018-08-15 | 株式会社アドマテックス | Crystalline silica particle material, method for producing the same, slurry composition containing crystalline silica particle material, and resin composition containing crystalline silica particle material |
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| CN106660813A (en) * | 2014-08-25 | 2017-05-10 | 新日铁住金高新材料株式会社 | Spherical crystalline silica particles and method for producing same |
| JP6374138B2 (en) * | 2016-04-28 | 2018-08-15 | 株式会社アドマテックス | Crystalline silica particle material, method for producing the same, slurry composition containing crystalline silica particle material, and resin composition containing crystalline silica particle material |
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