JP7734503B2 - Filler for electronic materials, method for producing filler for electronic materials, filler-containing resin composition for electronic materials, and slurry for electronic materials - Google Patents

Description

The present invention relates to a filler for electronic materials, a method for producing a filler for electronic materials, a filler-containing resin composition for electronic materials, and a slurry for electronic materials.

The trend toward improved transmission speeds and larger capacities in communication terminals used for wireless transmission has led to the use of higher frequency radio wave bands. However, as frequencies increase, the amount of power attenuation per unit length of radio waves (electromagnetic waves), i.e., transmission loss, increases. Transmission loss is significantly affected by the dielectric loss tangent (dielectric loss), which is the loss that occurs when electromagnetic waves propagate through a dielectric. For this reason, fillers used in electronic components for large-capacity, high-speed communication in communication terminals, passenger cars, etc., as well as in their sealants, are required to have the ability to suppress dielectric loss tangent.

Generally, when it comes to fillers added to small electronic components or their sealants, materials with high dielectric constants are preferred. However, the high dielectric constant of the filler itself increases the dielectric loss tangent. As such, fillers are required to have the contradictory properties of high dielectric constant and reduced dielectric loss tangent.

Furthermore, since fillers are added to resins, they are required to have the fluidity and adhesion of the resin after addition. In order to increase the dielectric constant of resins used in electronic components or their sealants, the amount of filler added to the resin also increases. Therefore, a decrease in fluidity due to an increase in the viscosity of the resin undesirably reduces work efficiency.

In addition, strontium titanate and calcium titanate have high dielectric constants, making them promising compounds for use as fillers (see Patent Document 1, etc.). However, there is a risk that basic components eluted from these compounds may cause poor curing of the resin. Furthermore, the problem of suppressing high dielectric constants and dielectric loss tangents has not yet been resolved.

International Publication No. WO2019/123916

Subsequent intensive research led the inventors to find a way to suppress the dielectric dissipation factor of the filler by using compounds such as strontium titanate and calcium titanate, which have good dielectric constants, and by appropriately processing the surface of these compounds.

The present invention has been made in consideration of the above points, and provides a filler for electronic materials that uses strontium titanate and calcium titanate and can suppress the dielectric loss tangent while maintaining a high dielectric constant as a filler, a method for producing a filler for electronic materials, a filler-containing resin composition for electronic materials, and a slurry for electronic materials.

That is, the filler for electronic materials of this embodiment is a filler for electronic materials comprising a substrate portion primarily composed of strontium titanate or calcium titanate, and a coating portion formed by a coupling agent present on the surface of the substrate portion, and is characterized in that, in the following measurement of the amount of carbon derived from a chemically bonded surface treatment agent after cleaning (I), the ratio (Rw) of the amount of carbon derived from a chemically bonded surface treatment agent after cleaning (C2 (%)) to the amount of carbon derived from a surface treatment agent before cleaning (C1 (%)), as shown by formula (i), satisfies the range of 0.1 to 1.0.

To measure the amount of carbon derived from the chemically bonded surface treatment agent after washing (I), 35 g of methyl ethyl ketone is added to 5 g of electronic material filler, the mixture is shaken and left to stand for 10 minutes, and a sediment is obtained by solid-liquid separation using a centrifuge. The supernatant is then discarded, and 35 g of methyl ethyl ketone is added to 5 g of the sediment, the mixture is shaken and left to stand for 10 minutes, and a sediment is obtained by solid-liquid separation using a centrifuge, which is then dried. The amount of carbon in the dried sediment is measured as the amount of carbon derived from the chemically bonded surface treatment agent after washing.

Furthermore, in the above-mentioned filler for electronic materials, the volume average particle size of the substrate portion may be in the range of 0.1 to 3 μm.

Furthermore, in the above-mentioned filler for electronic materials, the coupling agent may be a silane-based coupling agent, a titanium-based coupling agent, or an aluminate-based coupling agent.

Furthermore, the filler for electronic materials may have a dielectric dissipation factor of 0.04 or less at 1 GHz in accordance with JIS C 2138 (2007).

Furthermore, the chemically bonded amount (reaction amount) of the surface treatment agent calculated from the amount of carbon after cleaning derived from the chemically bonded surface treatment agent ^per specific surface area (Fs ( m2 )) of the filler for electronic materials measured by the ^BET method may satisfy the range of 1 to 9 μmol/ m2 .

Furthermore, the filler for electronic materials may have a viscosity of 500 Pa·s or less after being kneaded with the liquid epoxy resin in the following viscosity measurement (II).

For viscosity measurement (II), when the main component of the substrate is strontium titanate, 32.5 g of electronic material filler and 17.5 g of liquid epoxy resin (1900 to 2600 mPa·s) are mixed and kneaded, or when the main component of the substrate is calcium titanate, 29.75 g of electronic material filler and 20.25 g of liquid epoxy resin (1900 to 2600 mPa·s) are mixed and kneaded, and each is aged at 80°C for 1 hour to prepare a viscosity measurement varnish, and the viscosity of the viscosity measurement varnish at 25°C is measured using an E-type viscometer.

Furthermore, the pH of the water extracted from the filler for electronic materials may be in the range of 5 to 9.5.

Furthermore, the coating portion of the filler for electronic materials may contain a silicon compound.

The method for producing fillers for electronic materials is characterized by comprising a contacting step in which a coupling agent is brought into contact with the surface of a substrate whose main component is strontium titanate or calcium titanate, and a heating step in which the substrate that has come into contact with the coupling agent is heated.

Furthermore, in the above-mentioned method for producing a filler for electronic materials, the coupling agent may be a silane-based coupling agent or a titanium-based coupling agent.

Furthermore, in the above-mentioned method for manufacturing filler for electronic materials, the heating step may be performed at a temperature of 200°C or less.

Furthermore, the above-mentioned method for producing a filler for electronic materials may include a silicon compound addition step of adding a silicon compound between the contacting step and the heating step.

The filler-containing resin composition for electronic materials is characterized by containing a filler for electronic materials in a resin. The slurry for electronic materials is characterized by containing a filler for electronic materials and a liquid dispersion medium that disperses the filler for electronic materials and is substantially free of water.

The filler for electronic materials of the present invention comprises a substrate primarily composed of strontium titanate or calcium titanate, and a coating formed by a coupling agent present on the surface of the substrate. The filler for electronic materials has a ratio (Rw) of the amount of carbon derived from the chemically bonded surface treatment agent after cleaning (C2 (%)) to the amount of carbon derived from the surface treatment agent before cleaning (C1 (%)) in the range of 0.1 to 1.0. Therefore, the filler can use strontium titanate or calcium titanate to maintain a high dielectric constant as a filler while suppressing the dielectric loss tangent. Furthermore, the manufacturing method for the filler for electronic materials of the present invention can produce a filler that maintains a high dielectric constant while suppressing the dielectric loss tangent. Furthermore, by forming the filler into a filler-containing resin composition for electronic materials or a slurry for electronic materials, a suitable composition or slurry for electronic materials can be obtained.

1 is an electron microscope photograph of an example of a filler for electronic materials according to an embodiment. 1 is an electron microscope photograph of a substrate portion.

In an embodiment, the filler for electronic materials has a substrate containing strontium titanate or calcium titanate powder as the main component, and a coating is formed on the surface of the substrate by adding a coupling agent. The filler for electronic materials is mainly used as an additive to electronic component encapsulants, substrate materials, heat transfer materials, etc. It is also preferably used as a resin composition for electronic materials, as described below. The substrate contains strontium titanate or calcium titanate as the main component, and the proportion of the main component in the entire substrate is 95% by mass or more, preferably 97% by _mass or more. Components other than the main component are minor components. Examples of minor components include SrO, _CaO , BaO, _Na2O , _SiO2 , _Al3O3 , _Fe2O3 , _BaTiO3 , _TiO2 , _SrCO3 , and _CaCO3 .

To form the filler, the substrate is in powder or particulate form. It may also be in any shape, such as plate, flake, whisker, rod, or filament. Titanates are generally known as compounds with high dielectric constants, with barium titanate being particularly widely used. However, in the case of barium titanate, the large atomic radius of barium increases both the dielectric constant and the dielectric dissipation factor. Therefore, given the purpose of the invention, which is to suppress the dielectric dissipation factor, barium titanate is not necessarily an ideal example. Therefore, strontium titanate or calcium titanate are preferable, as they allow for easier control of the dielectric dissipation factor, even if they result in a slight decrease in dielectric constant.

The average volume particle diameter of the substrate satisfies the range of 0.1 to 3 μm. The particle diameter refers to the median diameter (D ₅₀ ) measured by known particle diameter measurement methods such as laser diffraction scattering and dynamic scattering. If the average volume particle diameter of the substrate is below 0.1 μm, as described below, the viscosity increases when the filler is added to a resin and kneaded. This reduces the efficiency of coating and other processes. If the average volume particle diameter of the substrate is above 3 μm, the particle diameter of the filler itself is large, causing segregation due to filler settling in the resin. Therefore, the average volume particle diameter of the substrate is preferably in the range of 0.1 to 3 μm, more preferably 0.2 to 2.5 μm, and even more preferably 0.3 to 2.0 μm.

A coating formed by a coupling agent exists on the surface of the substrate. That is, a coating made of a coupling agent is formed on the surface of strontium titanate or calcium titanate powder. This structure achieves a high dielectric constant due to the compound in the substrate and a suppressed dielectric loss tangent due to the compound in the coating.

The coupling agent is mainly selected from silane-based coupling agents, titanium-based coupling agents, or aluminate-based coupling agents. These coupling agents may be used alone or in combination. Silane-based coupling agents are compounds in which a silicon atom is bonded to a hydrocarbon group. The examples below use a methoxysilane-based silane-based coupling agent. Titanium-based coupling agents are compounds in which a hydrocarbon group or the like is bonded around a titanium atom. Aluminate-based coupling agents are compounds in which a hydrocarbon group or the like is bonded around an aluminum atom.

The coupling agent prevents the strontium titanate or calcium titanate in the base material from being exposed. The surface of the base material is protected by the coating of the coupling agent. This prevents the compounds in the base material from reacting with their surroundings and decomposing or changing. In addition, due to the influence of the hydrocarbon groups of the coupling agent, it is easier to disperse when added to resins, etc. and when kneaded.

In addition, a silicon compound is added along with the coupling agent. Examples of silicon compounds that can be used include silicon oxide and other compounds in which silicon is bonded to a hydrocarbon group, phenyl group, vinyl group, epoxy group, methacryl group, amino group, aminophenyl group, ureido group, mercapto group, isocyanate group, or acrylic group. The addition of a silicon compound along with a coupling agent strengthens the bonds between the coupling agents in the coating, which is advantageous for improving the physical properties in the examples described below. Furthermore, the ends of the three or more hydrocarbon groups bonded to the silicon may contain compounds having the aforementioned functional groups. Surface treatment with a silicon compound having a functional group at the end of the hydrocarbon group bonded to the silicon increases hydrophobicity, further suppresses moisture adsorption, and further reduces the dielectric tangent.

Fillers for electronic materials, formed from a substrate and a coating covering its surface, have a dielectric dissipation factor of 0.04 or less at 1 GHz in accordance with JIS C 2138 (2007). For materials formed from a substrate of strontium titanate or calcium titanate and a coating of a silane-based coupling agent or titanium-based coupling agent, the specific dielectric dissipation factor is a new requirement that has not been reported previously.

The preferred range for the dielectric dissipation factor of fillers for electronic materials is 0.04 or less, and even more preferably 0.02 or less. By reducing the dielectric dissipation factor, the loss that occurs when electromagnetic waves propagate through a dielectric is also reduced, avoiding energy loss. For this reason, it is desirable for the dielectric dissipation factor to be as small as possible. However, due to the influence of the dielectric constant of the dielectric of the base material, the value cannot be "0," and reducing the dielectric dissipation factor alone is undesirable as it will diminish the favorable dielectric constant of the dielectric of the base material. Therefore, the dielectric dissipation factor is specified as 0.04 or less.

In the filler for electronic materials of this embodiment, the surface of the substrate is coated with a coupling agent to form a coating. In other words, good cross-linking between the coupling agents and bonding between the coupling agent and the compound in the substrate are required. The coating formed from the coupling agent firmly adheres to the substrate, reducing the dielectric tangent and also protecting the substrate, which is important.

To evaluate the degree of adhesion between the substrate and coating, the completed electronic material filler is washed with an organic solvent. After washing, the amount of carbon in the remaining components is measured as the post-wash carbon amount derived from the chemically bonded surface treatment agent. Therefore, by comparing the pre-wash carbon amount (carbon amount) derived from the surface treatment agent of the electronic material filler with the post-wash carbon amount (carbon amount) derived from the chemically bonded surface treatment agent, the amount of coupling agent remaining in the electronic material filler can be determined. As mentioned above, coupling agents contain hydrocarbon groups (methoxy groups) and are highly soluble in organic solvents. However, the titanate in the substrate is hydrophilic and does not dissolve in organic solvents. Therefore, it is easy to dissolve and separate the unreacted coupling agent alone. The chemically bonded surface treatment agent is primarily the coupling agent that forms the coating.

Specifically, the carbon content C1 (%) derived from the surface treatment agent before cleaning and the carbon content C2 (%) derived from the chemically bonded surface treatment agent after cleaning are measured, and the C2/C1 ratio (Rw) is calculated using the formula (i) above. The ratio (Rw) is preferably in the range of 0.1 to 1.0. Furthermore, the ratio (Rw) is preferably in the range of 0.2 to 1.0, and more preferably in the range of 0.4 to 1.0. A higher ratio (Rw) indicates that the coupling agent is firmly bonded to the titanate in the substrate. If the C2/C1 ratio (Rw) is below 0.1, this means that 90% of the coupling agent has leaked out and is not useful in forming the coating. If the C2/C1 ratio (Rw) is 1, this means that no coupling agent has leaked out.

There are no limitations on the equipment used to measure the carbon content. In the examples described below, a simultaneous carbon/sulfur analyzer is used. This analyzer is a device that heats and burns carbon and sulfur components and quantitatively analyzes them using infrared light. When cleaning with an organic solvent, 35 g of methyl ethyl ketone is added to 5 g of electronic material filler, the mixture is shaken, and left to stand for 10 minutes. A centrifuge is used for solid-liquid separation, and the sediment is collected and the supernatant is discarded. 35 g of methyl ethyl ketone is added to 5 g of the sediment, the mixture is shaken, and left to stand for 10 minutes. A centrifuge is used for solid-liquid separation, and the sediment is collected and dried. The carbon content of the dried sediment is then measured using a simultaneous carbon/sulfur analyzer or the like.

Furthermore, in addition to the relative ratio of the residual coupling agent before and after cleaning, it is possible to specify a specific residual amount of coupling agent. That is, the chemically bonded amount (reaction amount) of the surface treatment agent is specified, calculated from the amount of carbon derived from ^the chemically bonded surface treatment agent after cleaning per specific surface area Fs ( m2 ) of the filler for electronic materials measured by the BET method. The amount of carbon after cleaning per specific surface area is preferably in the range of 1 to 9 μmol/ m2 ^. The amount of carbon after cleaning is the amount of coupling agent actually fixed to the substrate.

Here, when the chemically bonded amount (reaction amount) of the surface treatment agent calculated from the amount of carbon after cleaning derived from the chemically bonded surface treatment agent per specific surface area is less than 1 ^μmol / m2 , the amount of remaining coupling agent itself is small, and the performance required of the coated portion is not fully exhibited.When the chemically bonded amount (reaction amount) of the surface treatment agent calculated from the amount of carbon after cleaning derived from the chemically bonded surface treatment agent per specific surface area is more than ⁹ μmol/ m2 , the amount of coupling agent itself is large, and the coated portion becomes resistive, undesirably lowering the dielectric constant as a filler for electronic materials.

The electronic material filler of this embodiment is primarily added to sealing materials for electronic components, substrate materials, heat transfer materials, etc. Therefore, if the viscosity is increased when kneading with the resin to which it is added, kneading will not proceed smoothly. Furthermore, the load placed on the kneaded paste when it is dispensed is large, which can interfere with the coating process. Therefore, it is necessary to avoid excessively increasing the viscosity of the resin after kneading.

Therefore, the viscosity of the filler for electronic materials after mixing with the liquid epoxy resin is 500 Pa·s or less. If the viscosity after mixing exceeds 500 Pa·s, the increased viscosity results in poor application to the target object. While there is no specific lower limit, if the viscosity is below 100 Pa·s, the liquid will become excessively fluid, which can lead to dripping and other problems.

Specifically, when the substrate is strontium titanate, 32.5 g of the electronic material filler is mixed and kneaded with 17.5 g of liquid epoxy resin (1.9 to 2.6 Pa·s). Alternatively, when the substrate is calcium titanate, 29.75 g of the electronic material filler is mixed and kneaded with 20.25 g of liquid epoxy resin (1.9 to 2.6 Pa·s). Each mixture is then aged at 80°C for one hour to prepare a viscosity measurement varnish, and the viscosity of the viscosity measurement varnish at 25°C is measured using an E-type viscometer.

In the filler for electronic materials according to the embodiment, the strontium titanate and calcium titanate that form the substrate are susceptible to the effects of acid, resulting in the liberation of strontium and calcium. Therefore, a coating is formed on the surface of the substrate to protect the interior, and the coating is made basic. This makes it easier to protect the substrate from the effects of other acids during storage or use of the filler for electronic materials.

Therefore, the pH of the water extracted from the filler for electronic materials is preferably in the range of 5 to 9.5, and more preferably in the range of 7 to 9.5. It ranges from weakly acidic to alkaline. To measure the pH of the extracted water, 70 mL of deionized water is added to 3.5 g of the filler for electronic materials and shaken for 30 minutes. Solid and liquid are separated using a centrifuge, and the supernatant water is used for pH measurement.

The fillers for electronic materials in the embodiments described so far are added to resins to prepare filler-containing resin compositions for electronic materials. Examples of resins to which the fillers can be added include thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polystyrene, other olefin resins, polyimide resins, and liquid crystal polymers, as well as thermosetting resins such as fluororesins, urea resins, and phenolic resins, polyphenylene ethers, and bismaleimides. The fillers can also be added to elastic resins such as styrene-butadiene rubber and isoprene rubber, and silicone resins. For example, epoxy resins are used as the resin when manufacturing resin substrates such as electronic component packaging substrates and interlayer insulating films.

Examples of epoxy resins used in the resin composition include bisphenol A epoxy resins, bisphenol F epoxy resins, biphenyl epoxy resins, phenol novolac epoxy resins, naphthalene epoxy resins, and phenoxy epoxy resins. From the standpoints of heat resistance and thermal expansion coefficient, it is preferable that the weight of the electronic material filler blended into the resin composition be large. It is desirable that the electronic material filler be added in an amount of 80% by mass or more of the total mass of the resin composition.

Furthermore, the filler for electronic materials according to the embodiment can be dispersed in a liquid dispersion medium that is substantially free of water to prepare a slurry for electronic materials. Examples of the dispersion medium include methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, toluene, N-methylpyrrolidone, γ-butyrolactone, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate. The dispersion medium can be used alone or in combination. It is also possible to use an appropriate dispersant.

Next, a method for producing a filler for electronic materials according to an embodiment will be described. First, strontium titanate or calcium titanate granules are prepared and weighed out in a predetermined amount. A predetermined amount of the aforementioned silane-based coupling agent or titanium-based coupling agent is then weighed out and added. The two are then thoroughly mixed, and the coupling agent is brought into contact with the surface of the substrate made of strontium titanate or calcium titanate granules (the "contacting step"). The ratio of the coupling agent to the substrate is approximately 0.03 to 3% by weight.

When the coupling agent comes into contact with the surface of the substrate, reactions such as crosslinking between the coupling agents themselves or bonding between the substrate and the coupling agent are promoted even at room temperature. A coating derived from the coupling agent is then formed on the surface of the substrate. In addition, the substrate that has come into contact with the coupling agent is heated (the "heating step"). The heating step promotes reactions such as crosslinking and bonding of the coupling agent. The heating temperature in the heating step is 200°C or less, preferably 180°C or less. Heating above 200°C may cause thermal decomposition of the coupling agent. Furthermore, between the contacting step and the heating step, the aforementioned silicon compound, such as silicon oxide, is added (the "silicon compound addition step"). The formation of a coating by the silicon compound along with the coupling agent increases the stability of the coating.

Fillers for electronic materials were produced as prototypes 1 to 53, and the physical properties of each prototype were evaluated. Below, we will explain the raw materials used, production methods, and measurement and evaluation methods in that order.

[Raw materials used]
The substrates used were strontium titanate (manufactured by Fuji Titanium Industry Co., Ltd., volume average particle size: 1.5 μm), strontium titanate (manufactured by Sakai Chemical Industry Co., Ltd., volume average particle size: 0.3 μm), calcium titanate (manufactured by Fuji Titanium Industry Co., Ltd., volume average particle size: 1.5 μm), and calcium titanate (manufactured by Sakai Chemical Industry Co., Ltd., volume average particle size: 0.3 μm). Also, silicon oxide (manufactured by Admatechs Co., Ltd., silicon oxide: average particle size: 10 nm) was used.

Of the coupling agents, the following silane coupling agents were used: KBM-573 (N-phenyl-3-aminopropylmethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. (referred to as "coupling agent A" in the tables below); KBM-1003 (vinyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. (referred to as "coupling agent B" in the tables below); KBM-1083 (octenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. (referred to as "coupling agent C" in the tables below); and KBM-3063 (hexyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. (referred to as "coupling agent D" in the tables below).
As the titanium-based coupling agent, KR-TTS manufactured by Ajinomoto Fine-Techno Co., Ltd. (referred to as "coupling agent E" in the table below) was used.
As the aluminate-based coupling agent, AL-M manufactured by Ajinomoto Fine-Techno Co., Ltd. (referred to as "coupling agent F" in the table below) was used.

For the capping treatment in the prototype, SZ-31 (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd. was used.
The liquid epoxy resin used in the viscosity measurement was ZX-1059 manufactured by Tohto Kasei Co., Ltd.

[Preparation of filler for electronic materials]
・Prototype example 1
Prototype 1 consisted only of a substrate made of strontium titanate (volume average particle size: 1.5 μm).

・Prototype examples 2 to 11
Strontium titanate (volume average particle size: 1.5 μm) was used as the base material, and coupling agent A in the table below was added and mixed while varying the weight relative to the weight of the base material.

・Prototype example 12
The same composition as in Prototype Example 9 was used, and the mixture was heated at 180°C for 2 hours.

・Prototype examples 13 and 14
In prototype 13, strontium titanate (volume average particle size: 1.5 μm) was used as the base material, and coupling agent B in the table below was added and mixed based on the weight of the base material.
For Sample 14, Sample 13 was prepared, and then hexamethyldisilazane was added.

・Prototype examples 15 to 19
Strontium titanate (volume average particle size: 1.5 μm) was used as the base material, and coupling agent C in the table below was added and mixed while varying the weight relative to the weight of the base material.

・Prototype examples 20 to 25
Strontium titanate (volume average particle size: 1.5 μm) was used as the base material, and coupling agent C in the table below was added and mixed while changing the weight relative to the weight of the base material. After addition, the mixture was heated at 180° C. for 2 hours.

・Prototype example 26
Prototype 26 consisted of only a substrate portion made of strontium titanate (volume average particle size: 0.3 μm).

・Prototype examples 27 to 29
Strontium titanate (volume average particle size: 0.3 μm) was used as the base material, and coupling agent A in the table below was added and mixed while varying the weight relative to the weight of the base material.

・Prototype example 30
Prototype 30 had only a substrate portion made of calcium titanate (volume average particle size: 1.5 μm).

・Prototype examples 31 to 36
Calcium titanate (volume average particle size: 1.5 μm) was used as the base material, and coupling agent C in the table below was added and mixed while changing the weight relative to the weight of the base material. After addition, the mixture was heated at 180° C. for 2 hours.

・Prototype examples 37 to 41
Strontium titanate (volume average particle size: 1.5 μm) was used as the base material, and silicon oxide was added and mixed together with coupling agent A in the table below while varying the weight relative to the weight of the base material.

・Prototype examples 42 to 46
Strontium titanate (volume average particle size: 1.5 μm) was used as the base material, and silicon oxide was added and mixed together with coupling agent B in the table below while varying the weight relative to the weight of the base material.

・Prototype examples 47 to 50
Strontium titanate (volume average particle size: 1.5 μm) was used as the base material, and silicon oxide was added to the base material along with coupling agent B in the table below while varying the weight of the silicon oxide. After addition, the mixture was heated at 180° C. for 2 hours.

・Prototype examples 51 to 53
Strontium titanate (volume average particle size: 1.5 μm) was used as the base material, and coupling agent C (Prototype Example 51), coupling agent D (Prototype Example 52), and coupling agent F (Prototype Example 53) shown in the table below were added to the base material by weight and mixed. After addition, the mixture was heated at 180° C. for 2 hours.

[Measurement and evaluation methods]
The dielectric loss tangent of each prototype was measured in accordance with JIS C 2138 (2007). Specifically, the relative permittivity and dielectric loss tangent at 1 GHz were measured using a Keysight Network Analyzer (product name "E5071C") and a cavity resonator perturbation method. This measurement was performed in accordance with ASTM D2520 (JIS C 2565 (1992)).

Measurement of carbon amount (carbon content) derived from chemically bonded surface treatment agent 5 g of each prototype was weighed out and mixed with 35 g of methyl ethyl ketone, then shaken using a shaker and allowed to settle for 10 minutes. After solid-liquid separation using a centrifuge, the supernatant was discarded. 5 g of the sediment was mixed with 35 g of methyl ethyl ketone, then shaken using a shaker and allowed to settle for 10 minutes. After solid-liquid separation using a centrifuge, the supernatant was discarded to obtain a sediment. The sediment was dried to obtain a sample for carbon content measurement. This sample was used as the washed sample. Before washing, no methyl ethyl ketone was added and the sample was used for measurement as is.

The carbon content was measured using a LECO carbon/sulfur simultaneous analyzer (product name "CS-444LS Model") and a carbon standard sample of JSS061-8. The ratio Rw was calculated from the carbon content before and after cleaning.

Measurement of BET specific surface area: 1.0 g of each prototype was weighed out and placed in a measurement cell. After pretreatment, the BET specific surface area was measured. The measuring machine used was "Macsorb HMmodel-1208" (manufactured by MACSORB). The pretreatment was carried out under the following conditions:
Degassing temperature: 200°C
Degassing time: 30 minutes Cooling time: 4 minutes

Viscosity Measurement When the base material of the prototype was strontium titanate, 32.5 g of the prototype was mixed with 17.5 g of liquid epoxy resin (1900 to 2600 mPa s) and kneaded. When the base material of the prototype was calcium titanate, 29.75 g of the prototype was mixed with 20.25 g of the liquid epoxy resin.

After mixing, each mixture was aged at 80°C for 1 hour to prepare a varnish for viscosity measurement, and the viscosity of this varnish for viscosity measurement at 25°C was measured using an E-type viscometer.

pH Measurement: 3.5 g of each sample was weighed and placed in a plastic container, 70 ml of deionized water was poured into it, and the container was shaken for 30 minutes using a shaker. After solid-liquid separation using a centrifuge, the supernatant water was collected and the pH was measured.

Overall Evaluation The overall evaluation of the prototypes was based on the measurement results of each measurement item and was rated on a four-level scale, from the best "A" to "B,""C," and "D."
Evaluation "A": The dielectric loss tangent is 0.02 or less. The ratio Rw is 0.4 to 1.0. The chemically bonded amount (reaction amount) of the surface treatment agent calculated from the amount of carbon derived from the chemically bonded surface treatment agent per specific surface area after cleaning is 2.0 μmol/ m2 or ^more . The viscosity is 500 Pa s or less. The pH of the extracted water is 9.5 or less.
Rating "B": The dielectric loss tangent is 0.04 or less. The ratio Rw is 0.2 to 1.0. The chemically bonded amount (reaction amount) of the surface treatment agent calculated from the amount of carbon derived from the chemically bonded surface treatment agent per specific surface area after cleaning is 2.0 μmol/ m2 or ^more . The viscosity is 500 Pa·s or less. The pH of the extracted water is 9.5 or less.
Rating "C": The dielectric loss tangent is 0.02 or less. The ratio Rw is 0.1 to 1.0. The chemically bonded amount (reaction amount) of the surface treatment agent calculated from the amount of carbon derived from the chemically bonded surface treatment agent per specific surface area after cleaning is 2.0 μmol/ m2 or ^more . The viscosity is 500 Pa·s or less. The pH of the extracted water is 9.5 or less.
Evaluation "D": A prototype that does not fall under evaluations A, B, or C.

The prototypes rated "A" showed the best results and are most preferable as fillers for electronic materials.
The prototypes rated "B" showed good results and were next to those rated "A" as fillers for electronic materials.
The prototypes rated "C" are examples that can be used as fillers for electronic materials.
Samples rated "D" are not suitable as fillers for electronic materials.

[result]
For Prototype Examples 1 to 53, the individual raw materials and compositions are shown along with the measurement results and overall evaluation as shown in Tables 1 to 5. Also shown are photographs taken with an electron microscope (SEM). Figure 1 is a 20,000x magnified photograph of Prototype Example 6. Figure 2 is a 20,000x magnified photograph of Prototype Example 1.

[Consideration]
By comparing the photographs of FIG. 1 and FIG. 2, it was possible to confirm the formation of a coating portion by the coupling agent.

Prototypes 1, 26, and 30 are examples that do not contain a coupling agent. This is undesirable as it increases viscosity and worsens pH properties. Therefore, it can be said that a coupling agent is essential. While heating is optional, it is preferable to apply heat, as shown in prototypes 12, 20 to 25, and 31 to 36, as it is believed that this promotes reaction on the surface of the base material. While incorporating a silicon compound into the coating is optional, it is preferable to incorporate a silicon compound, as shown in prototypes 37 to 50, as this enhances the protective effect of the coating.

Prototypes 2 to 12 are examples in which the amount of coupling agent was varied. Prototypes 2, 3, and 4, which contain small amounts of coupling agent, show increased viscosity. Furthermore, samples 8 to 11, which contain large amounts of coupling agent, show a deterioration in dielectric tangent. A comparison of prototypes 9 and 12 shows improvement due to heat treatment. A comparison of prototypes 13 and 14 confirms that capping treatment reduces the dielectric tangent.

Prototypes 15 to 25 are examples in which the type of coupling agent was changed, and the relationship between the amount added shows similar trends to those of prototypes 2 to 12. Furthermore, an improvement was also confirmed in the ratio of the amount of carbon (carbon content) derived from the chemically bonded surface treatment agent before and after cleaning by heat treatment.

Prototypes 27 to 29 are examples in which the particle size of the substrate was reduced. Even with these particle sizes, good results were obtained.

In prototypes 31 to 36, the base material was changed to calcium titanate, and the relationship between the additive amounts showed similar trends to prototypes 2 to 12. Furthermore, an improvement was also confirmed in the ratio of the amount of carbon derived from the chemically bonded surface treatment agent before and after cleaning by heat treatment.

Prototypes 37 to 50 are examples in which the coating contains silicon oxide as a silicon compound. Good properties were confirmed in the ratio of carbon content (carbon amount) derived from the chemically bonded surface treatment agent, dielectric tangent, and viscosity before and after cleaning.

Prototypes 51 to 53 are examples in which the type of coupling agent was changed. As shown in these prototypes, even when a long-chain silane-based coupling agent and an aluminate-based coupling agent were used, favorable properties were confirmed in the ratio of carbon content (carbon amount) derived from the chemically bonded surface treatment agent before and after cleaning, as well as the dielectric tangent.

Claims (10)

a substrate portion containing strontium titanate or calcium titanate as a main component;
a coating portion formed on a surface of the base material by a coupling agent that is a silane-based coupling agent or an aluminate-based coupling agent ,
In the filler for electronic materials, in the following measurement (I) of the amount of carbon derived from a chemically bonded surface treatment agent after cleaning, the ratio (Rw) of the amount of carbon derived from a chemically bonded surface treatment agent after cleaning (C2(%))/the amount of carbon derived from a surface treatment agent before cleaning (C1(%)) represented by formula (i) satisfies the range of 0.2 to 1.0,
the filler for electronic materials has a dielectric loss tangent at 1 GHz in accordance with JIS C 2138 (2007) of 0.02 or less;
the chemically bonded amount (reaction amount) of the surface treatment agent calculated from the amount of carbon after cleaning derived from the chemically bonded surface treatment agent per specific surface area (Fs (m ² )) of the filler for electronic materials measured by the BET method satisfies the range of 1 to 9 μmol/m ² ;
The pH of the water extracted with the filler for electronic materials is in the range of 5 to 9.5.
A filler for electronic materials characterized by:
Measurement of post-wash carbon amount derived from chemically bonded surface treatment agent (I): 35 g of methyl ethyl ketone is added to 5 g of the filler for electronic materials, the mixture is shaken and left to stand for 10 minutes, and a sediment is obtained by solid-liquid separation using a centrifuge. The supernatant is discarded, and 35 g of methyl ethyl ketone is added to 5 g of the sediment, the mixture is shaken and left to stand for 10 minutes, and a sediment is obtained by solid-liquid separation using a centrifuge. The sediment is then dried. The carbon amount in the dried sediment is measured as the post-wash carbon amount derived from the chemically bonded surface treatment agent.
The pH of the water extracted with the filler for electronic materials is the pH of the supernatant water obtained by adding 70 mL of deionized water to 3.5 g of the filler for electronic materials, shaking the mixture for 30 minutes, and separating the solid and liquid using a centrifuge. The filler for electronic materials according to claim 1, wherein the volume average particle size of the substrate portion is in the range of 0.1 to 3 μm. 3. The filler for electronic materials according to claim 1 , wherein the filler for electronic materials has a viscosity of 500 Pa·s or less after being kneaded with a liquid epoxy resin in the following viscosity measurement (II).
Viscosity measurement (II): When the main component of the substrate is strontium titanate, 32.5 g of the filler for electronic materials is mixed and kneaded with 17.5 g of a liquid epoxy resin (1900 to 2600 mPa s), or when the main component of the substrate is calcium titanate, 29.75 g of the filler for electronic materials is mixed and kneaded with 20.25 g of a liquid epoxy resin (1900 to 2600 mPa s), and each is aged at 80°C for 1 hour to prepare a varnish for viscosity measurement, and the viscosity of the varnish for viscosity measurement at 25°C is measured using an E-type viscometer. 4. The filler for electronic materials according to claim 1, wherein the coating portion contains silicon oxide as a silicon compound different from the silane coupling agent . A method for producing the filler for electronic materials according to any one of claims 1 to 4 , comprising:
a contacting step of contacting a coupling agent with the surface of the substrate mainly composed of strontium titanate or calcium titanate;
a heating step of heating the substrate portion in contact with the coupling agent. 6. The method for producing a filler for electronic materials according to claim 5 , wherein the coupling agent is a silane-based coupling agent or a titanium-based coupling agent. 7. The method for producing a filler for electronic materials according to claim 5 , wherein the heating step is performed at 200°C or less. Between the contacting step and the heating step,
The method for producing a filler for electronic materials according to claim 5 , further comprising a silicon compound adding step of adding silicon oxide as a silicon compound different from the silane coupling agent . A filler-containing resin composition for electronic materials, comprising a resin containing the filler for electronic materials according to any one of claims 1 to 4 . The filler for electronic materials according to any one of claims 1 to 4 ,
a liquid dispersion medium in which the filler for electronic materials is dispersed and which does not substantially contain water;
A slurry for electronic materials, comprising: