JP7249209B2 - Epoxy resin composition for casting, electronic component, and method for producing electronic component - Google Patents

Description

TECHNICAL FIELD The present invention relates to a casting epoxy resin composition, an electronic component cast and molded using the casting epoxy resin composition, and a method for producing the electronic component.

Conventionally, high impregnability, high electrical insulation, and workability are required for motors for railway vehicles, rotating machines for generators, coil products for various electrical equipment products, capacitors, and electronic parts. Thermosetting resin compositions, particularly epoxy resin compositions, are frequently used for insulation treatment of parts. For example, acid anhydride-curable epoxy resin compositions have excellent mechanical properties, electrical insulation properties, and high voltage properties at high temperatures. , the performance and reliability of which can be improved (see, for example, Patent Document 1).

However, for electronic parts such as film capacitors used in various devices such as electric vehicles (EV) and hybrid vehicles (HEV), considering the environment in which the parts are mounted, heat resistance, crack resistance, low Moisture permeability (small change in capacitor capacity) is required. On the other hand, if an ordinary epoxy resin composition is simply used, insulation may be insufficient and dielectric breakdown may occur. In addition, the sealing resin cured product of the epoxy resin composition is insufficient to prevent electrical deterioration. In addition, thermal stress and mechanical stress caused by cooling/heating cycles may cause cracks in the cured encapsulating resin. If cracks occur in the cured encapsulating resin, the capacitance of the capacitor will change, and normal operation will not be possible. Therefore, a cured product made of a resin composition is required to have low moisture permeability and crack resistance.

General techniques for improving the low moisture permeability and crack resistance of a cured product made of a resin composition include reducing the moisture permeability by supplementing moisture by adding porous silica, and reducing the resin portion by adding a large amount of filler. be done. Moreover, as a technique for improving the crack resistance, it is conceivable to add a large amount of silica to the resin composition to reduce the coefficient of linear expansion. However, the technique of adding a large amount of silica causes precipitation of the silica component in the resin composition during curing or precipitation of the silica component during storage of the resin. As a solution to this problem, fine silica powder or the like is blended during casting or molding, but this greatly impedes fluidity. As a further improvement method, in view of such problems, for example, Patent Document 2 discloses a two-liquid type containing spherical silica having an average particle size of 2 μm or less, two types of acid anhydrides, a curing accelerator, and an epoxy resin. An epoxy resin composition is disclosed. Further, Patent Document 3 discloses a two-component epoxy resin composition containing an inorganic thickener and a wetting and dispersing agent for rheology control.

JP-A-10-60084 JP-A-11-71503 Special table 2017-527641

In Patent Document 2, an attempt is made to prevent the occurrence of cracks due to the above-described thermal stress by reducing the coefficient of linear expansion using the epoxy resin composition to improve resistance to thermal cycling. However, even this method was insufficient for improving the sedimentation property of the silica component. In addition, Patent Document 3 does not disclose any knowledge regarding the prevention of sedimentation of silica components.

In recent high-performance film capacitors, the demand for improved low moisture permeability and crack resistance has become severe, and it has been difficult to achieve these performances with conventional resin systems.
The present invention has been made in view of such circumstances, and has low moisture permeability, excellent crack resistance, suppression of dielectric breakdown at high voltage, etc., and prevention of sedimentation of filler during storage and after curing. An object of the present invention is to provide a casting epoxy resin composition capable of forming a highly reliable resin portion, an electronic component cast from the resin composition, and a method for manufacturing the electronic component.

The inventors of the present invention have made intensive studies to solve the above problems, and as a result, found that an epoxy resin composition for casting containing an organophilic phyllosilicate can solve the above problems, and have completed the present invention. completed.
The present invention has been completed based on such findings.

That is, the present disclosure relates to the following.
[1] A casting epoxy resin composition comprising (A) an epoxy resin, (B) an acid anhydride, (C) an inorganic filler, (D) an organophilic phyllosilicate, and (E) a curing accelerator.
[2] The epoxy resin composition for casting according to the above [1], further comprising (F) a fumed metal oxide.
[3] A main agent containing (A) an epoxy resin, (C) an inorganic filler, and (D) an organophilic phyllosilicate, (B) an acid anhydride, (C) an inorganic filler, and (D) an organophilic phyllosilicate The casting epoxy resin composition according to the above [1], comprising an acid salt, and (E) a curing agent containing a curing accelerator.
[4] (A) epoxy resin, (C) inorganic filler, (D) organophilic phyllosilicate and/or (F) main agent containing fumed metal oxide, (B) acid anhydride, (C) inorganic The casting epoxy resin composition according to [2] above, comprising a filler, (D) an organophilic phyllosilicate, and (E) a curing agent containing a curing accelerator.
[5] The casting epoxy resin composition according to [3] or [4] above, wherein the (D) organophilic phyllosilicate is contained in the curing agent in an amount of 0.1 to 2.0% by mass.
[6] The above [4], wherein the main agent contains (F) a fumed metal oxide, and the content of the (F) fumed metal oxide contained in the main agent is 0.1 to 2.0% by mass. ] or the epoxy resin composition for casting according to [5].
[7] The casting epoxy resin composition according to any one of [1] to [6] above, wherein (A) the epoxy resin comprises a bisphenol A epoxy resin, an alicyclic epoxy resin, and a polynuclear epoxy resin. thing.
[8] The epoxy resin composition for casting according to any one of [1] to [7] above, wherein the (C) inorganic filler is spherical fused silica.
[9] The epoxy resin composition for casting according to any one of the above [1] to [8], wherein the organophilic phyllosilicate (D) has a pH of 6 to 9 when dispersed in water.
[10] An electronic component molded from the epoxy resin composition for casting according to any one of [1] to [9] above.
[11] An electronic component element is placed in a mold, and the casting epoxy resin composition according to any one of [1] to [9] is injected into the mold and semi-cured, A method of manufacturing an electronic component, wherein the epoxy resin composition is removed from the mold and completely cured by post-curing.

According to the present invention, a highly reliable resin portion is formed which has excellent low moisture permeability and crack resistance, suppresses dielectric breakdown at high voltage, etc., prevents filler sedimentation during storage and after curing, and has excellent reliability. A possible casting epoxy resin composition, an electronic component cast from the resin composition, and a method for manufacturing the electronic component can be provided.

1 is a schematic cross-sectional view of an electronic component in the process of being manufactured according to an embodiment of the present invention; FIG. It is a sectional view showing roughly an example of an electronic component manufactured by one embodiment of the present invention.

The present invention will be described in detail below.
The epoxy resin composition for casting of the present invention (hereinafter also simply referred to as "resin composition") comprises (A) an epoxy resin, (B) an acid anhydride, (C) an inorganic filler, and (D) an organophilic phyllosilicate. acid salt, and (E) a curing accelerator.

As the (A) epoxy resin used in the present invention, an epoxy resin having two or more glycidyl groups (epoxy groups) in one molecule is preferably used. Examples of such epoxy resins include bisphenol A type epoxy resin; bisphenol F type epoxy resin; bisphenol AD type epoxy resin; novolac type epoxy resin; glycidyl ester type epoxy resin; polyglycidyl ether; alicyclic epoxy resins; polynuclear epoxy resins such as naphthalene type epoxy resins, phenol novolac type epoxy resins, triphenylmethane type epoxy resins, and bisphenol novolac type epoxy resins. These may be used alone or in combination of two or more. In addition, when mixing and using 2 or more types, it should just be liquid when mixed.
In order to further impart heat resistance, in the present invention, the (A) epoxy resin preferably contains an alicyclic epoxy resin and a polynuclear epoxy resin in addition to the bisphenol A type epoxy resin.

(A) It is preferable that the bisphenol A type epoxy resin is 50% by mass or more, the alicyclic epoxy resin is 10% by mass or more, and the polynuclear epoxy resin is 10% by mass or more based on the total mass of the epoxy resin.

The content of (A) the epoxy resin in the resin composition is preferably 10 to 25% by mass, more preferably 10 to 20% by mass, and still more preferably 10 to 15% by mass, from the viewpoint of good curability. .

The acid anhydride (B) used in the present invention can be used without particular limitation as long as it has an acid anhydride group in the molecule that is usually used as a curing agent for epoxy resins. Examples include tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, methylhimic anhydride, methyltetrahydrophthalic anhydride and the like. Among them, methylhimic anhydride is preferable because it has resistance to moisture and good storage stability.
The acid anhydride (B) may be used alone or in combination of two or more.

The content of the acid anhydride (B) is preferably in the range of 0.7 to 1.1 equivalents, more preferably 0.8 to 1.0 equivalents, per equivalent of the epoxy group in the epoxy resin (A). is more preferred. (B) When the content of the acid anhydride is within the above range, properties such as heat resistance, mechanical properties, and moisture resistance of the cured product are improved.

Examples of (C) inorganic fillers used in the present invention include silica, alumina, calcium carbonate, aluminum hydroxide, talc, and mica. Among them, silica is preferably used. As silica, spherical fused silica, crushed fused silica, and the like can be used, and spherical fused silica is preferable. For example, specific brands of spherical fused silica include S3030, S210 [manufactured by Micron Co., Ltd., trade names], FB-5D, FB959 [manufactured by Denka Co., Ltd., trade names], and SC4500-SQ. [manufactured by Admatec Co., Ltd., trade name] and the like. Specific brands of crushed fused silica include Hughes Rex RD-8, Hues Rex RD-120, Hues Rex E-1, Hues Rex E-2 MSR-15, MSR-3500, and TZ-20. ) manufactured by Tatsumori, trade name] and the like.

The term "sphericity" as used herein is defined as "the ratio of the minimum particle size to the maximum particle size". For example, as a result of observation with a scanning electron microscope (SEM), the ratio of the observed minimum diameter to the maximum diameter should be 0.85 or more. (C) The inorganic filler preferably has a sphericity of 0.9 or more in consideration of fluidity.

In addition, the average particle size of the (C) inorganic filler is preferably 1 to 40 μm, more preferably 1 to 30 μm, from the viewpoint of fluidity and workability.
The average particle size of the (C) inorganic filler can be measured with a laser diffraction/scattering particle size distribution analyzer (eg, device name: SALD-3100 manufactured by Shimadzu Corporation).

(C) The content of the inorganic filler is preferably 30 to 80% by mass, more preferably 35 to 75% by mass, based on the total amount of the resin composition. (C) When the content of the inorganic filler is 30% by mass or more, the mechanical strength and crack resistance of the cured product can be improved. , castability and moldability can be improved.

(C) Inorganic filler can obtain even better insulation reliability and mechanical strength of the cured product by modifying the surface thereof by adding a coupling agent to the resin composition. Examples of coupling agents that can be used here include silane coupling agents, titanium-based coupling agents, and aluminum-based coupling agents. is preferred.
Examples of these silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, methyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane. , N-aminoethylaminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-3-(4-(3-aminopropoxy)butoxy)propyl-3-aminopropyltrimethoxysilane, and the like. be done. These may be used alone or in combination of two or more.

The organophilic phyllosilicate (D) used in the present invention is a clay thickener consisting of a mixture of needle-like sepolite and rod-like saponite. By containing (D) the organophilic phyllosilicate in the resin composition, precipitation of the (C) inorganic filler can be suppressed, and uniformity of the cured product of the resin composition can be improved. (D) The polarity of the organophilic phyllosilicate can be controlled by modifying the surface of the phyllosilicate with quaternary ammonium chloride depending on the type of amine in the organic solvent. For example, a quaternary ammonium salt formed from an aromatic amine and an aliphatic carboxylic acid (having about 14 to 18 carboxyl groups) has a high polarity. On the other hand, a quaternary ammonium salt formed by an aliphatic amine and an aliphatic carboxylic acid is less polar. (D) The organophilic phyllosilicate is preferably highly polar with a large degree of modification from the viewpoint of suppressing sedimentation of the (C) inorganic filler and improving the uniformity of the cured product, and has a pH of 6 to 9 when dispersed in water. is preferably (D) As a highly polar commercial product of organophilic phyllosilicate, there is GARAMITE (registered trademark) 7305 (pH 7.3 when dispersed in water).
The pH at the time of water dispersion is a value measured with a pH meter after dispersing 5 g of the (D) organic phyllosilicate in 100 cc of pure water and allowing it to stand for 24 hours.

(D) The content of organophilic phyllosilicate is preferably in the range of 0.1 to 1.2 parts by mass with respect to a total of 100 parts by mass of (A) epoxy resin and (B) acid anhydride. A range of 0.2 to 1.0 parts by mass is more preferable. (D) When the content of the organophilic phyllosilicate is 0.1 parts by mass or more, it is possible to suppress the sedimentation prevention of the filler, and when it is 1.2 parts by mass or less, voids in the cured product are suppressed. can do.

The (E) curing accelerator used in the present invention is not particularly limited. Ureas such as -(3-chloro-4-methylphenyl)-1,1-dimethylurea and 2,4-bis(3,3-dimethylureido)toluene; benzyldimethylamine, 1,8-diazabicyclo (5. 4.0) Tertiary amine compounds such as undecene-7 and triethylamine; 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole , 2-phenylimidazole and 2-phenyl-4-methylimidazole; and organic phosphine salt compounds such as triphenylphosphine salt.
The curing accelerator (E) may be used alone or in combination of two or more.

(E) The content of the curing accelerator is in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the acid anhydride (B) from the viewpoint of the balance of curing acceleration and physical properties of the cured product. It is preferably in the range of 0.1 to 5 parts by mass. (E) When the content of the curing accelerator is 0.1 parts by mass or more, the resin composition can be cured well, and the electrical properties, film thickness uniformity, etc. can be improved. By doing so, the storage stability can be improved.

The casting epoxy resin composition of the present invention preferably further contains (F) a fumed metal oxide from the viewpoint of preventing precipitation of the (C) inorganic filler. (F) Fumed metal oxides include fumed alumina and fumed silica, with fumed alumina being preferred. (F) As a commercial product of the fumed metal oxide, there is AEROXIDE (registered trademark) Alu C [manufactured by Nippon Aerosil Co., Ltd., trade name].
The specific surface area of (F) the fumed metal oxide determined by the BET method is preferably 80 to 120 m ² /g from the viewpoint of preventing sedimentation of the (C) inorganic filler.

(F) The content of the fumed metal oxide is 0.1 to 0 with respect to a total of 100 parts by mass of (A) the epoxy resin and (B) the acid anhydride, from the viewpoint of preventing precipitation of the (C) inorganic filler. A range of 0.5 parts by mass is preferred, and a range of 0.2 to 0.5 parts by mass is more preferred.

The epoxy resin composition for casting of the present invention comprises a main component comprising (A) an epoxy resin, (C) an inorganic filler, (D) an organophilic phyllosilicate and/or (F) a fumed metal oxide, and (B ) an acid anhydride, (C) an inorganic filler, (D) an organophilic phyllosilicate, and (E) a curing agent comprising a curing accelerator. can.

When the main agent contains (F) a fumed metal oxide, the content of the (F) fumed metal oxide contained in the main agent is 0.1 to 2 from the viewpoint of preventing precipitation of the (C) inorganic filler. The range of 0.0% by weight is preferred, the range of 0.1 to 1.0% by weight is more preferred, and the range of 0.1 to 0.5% by weight is even more preferred.
In addition, the content of the (D) organophilic phyllosilicate contained in the curing agent is 0.1 to 2.0% by mass from the viewpoint of preventing precipitation of the (C) inorganic filler and improving the uniformity of the cured product. is preferred, the range of 0.1 to 1.0% by weight is more preferred, and the range of 0.1 to 0.5% by weight is even more preferred.

The casting epoxy resin composition of the present invention contains, in addition to the components described above, pigments, dyes, antifoaming agents, and leveling agents that are generally blended in this type of composition within the scope of the object of the present invention. , and other additives can be blended as needed.

The epoxy resin composition for casting of the present invention has low moisture permeability and excellent crack resistance, suppresses dielectric breakdown at high voltage, etc., prevents sedimentation of filler during storage and after curing, and has high reliability. An excellent resin portion can be formed. Therefore, it can be suitably used for sealing electronic parts such as film capacitors.

Next, a method for manufacturing an electronic component using the casting epoxy resin of the present invention will be described.
The electronic component of the present invention is molded from the epoxy resin composition for casting. Specifically, capacitors and internal parts can be produced by subjecting the epoxy resin composition for casting to a vacuum pressure impregnation treatment. The vacuum pressure impregnation treatment is performed, for example, by injecting a capacitor or internal parts housed in a case into a resin composition and performing vacuum impregnation treatment (reduced pressure impregnation treatment) and pressure treatment. At this time, the vacuum impregnation treatment is preferably performed at a temperature of 40° C. to 80° C., a pressure of 100 Pa to 450 Pa, and a time of 30 minutes to 120 minutes. Further, the pressure treatment is preferably performed at a pressure of 2×10 ⁵ Pa or more and 10×10 ⁵ Pa or less for 15 minutes or more and 120 minutes or less, for example.

After the vacuum pressure impregnated capacitor and internal parts are returned to normal pressure, the impregnated resin composition is heated and cured. Heating and curing are preferably performed at a temperature of, for example, 60° C. or higher and 200° C. or lower.

In addition, instead of using a case, E-LIM (Epoxy-Liquid Injection Molding) molding method can be used for easy manufacturing in a mold. In the E-LIM molding method, an electronic component element is placed in a mold, and the epoxy resin composition for casting is injected and semi-cured, removed from the mold, and the epoxy resin composition is cured by post-curing. fully cured.
By using the E-LIM molding method, it is now possible to mold in several tens of minutes, which used to take 5 to 10 hours for resin curing in the conventional casting method, greatly improving productivity. . In the method for manufacturing an electronic component according to the present invention, the product can be removed from the mold by a short-time curing reaction, so productivity can be improved. Moreover, since most of the curing can be performed by post-curing, there is no need to set complicated molding and curing conditions in the molding stage.

Examples of the electronic components include stator core (coil) components containing windings, connectors, switches, relays, capacitors, transformers, resistors, integrated circuits, and light emitting diodes (LEDs).

A method of manufacturing an electronic component by the E-LIM molding method will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of an electronic component in the process of being manufactured according to an embodiment of the present invention, and FIG. 2 is an electronic component manufactured by applying an embodiment of the present invention. is a cross-sectional view schematically showing the .
In FIG. 1, 1 indicates an injection mold used as a mold in this embodiment. The mold 1 is composed of a lower mold 11 and an upper mold 12, and concave portions 11a and 12a are formed in the lower mold 11 and the upper mold 12, respectively. The concave portions 11 a and 12 a form a cavity 13 . The upper mold 12 is also provided with a sprue 14 serving as a resin injection port communicating with the cavity 13. The sprue 14 is connected to an injection nozzle 15 for injecting the epoxy resin composition 3 for casting. there is The injection molding epoxy resin composition 3 is injected into the cavity 13 from the injection nozzle 15 through the sprue 14, and injection molding is performed to manufacture an electronic component.

First, the electronic component element 2 is placed in the recess 11a of the lower mold 11 controlled to a predetermined temperature, the upper mold 12 connected with the injection nozzle 15 is fitted thereon, and the junction with the lower mold 11 is airtight. At the same time, the inside of the cavity 13 is sucked by a vacuum pump or the like (not shown) to reduce the pressure to, for example, 10 Torr (approximately 1.33 kPa). The electronic component element 2 has terminals 2a extending from the side surfaces of its body, and these terminals 2a are arranged so as to be sandwiched between the joints of the lower mold 11 and the upper mold 12 . In FIG. 1, 16 denotes a sealing member that airtightly seals the joint between the upper mold 12 and the lower mold 11 .

Next, the tip 15 a of the injection nozzle 15 is opened to inject the epoxy resin composition 3 for casting into the cavity 13 between the lower mold 11 and the upper mold 12 . The injection nozzle 15 has a plunger 15c arranged concentrically within a nozzle main pipe 15b. It is designed to be able to intermittently inject inside. The plunger 15c is lifted to open the tip portion 15a to inject the epoxy resin composition 3 for casting.

When the cavity 13 is sufficiently filled with the epoxy resin composition 3 for casting, the lower mold 11 and the upper mold 12 are heated to semi-cure the epoxy resin composition 3 for casting. Here, "semi-cured" refers to a state in which the composition in the mold is cured to a hardness that allows handling as a molded article.

The temperature conditions for semi-curing the epoxy resin composition used in the E-LIM molding method in the mold are preferably a relatively medium temperature range of 70 to 100° C., and the reaction time is preferably about 5 to 25 minutes. When the temperature is 70° C. or higher, the curing reaction proceeds sufficiently, and when the temperature is 100° C. or lower, the curing reaction proceeds slowly, and the voids of the electronic component element can be uniformly filled with the epoxy resin composition. Further, when the reaction time is 5 minutes or more, curing or gelation proceeds sufficiently, making it easier to take out the molded product from the mold. can be made

After that, the mold 1 is opened, and the electronic component element 2 sealed and molded with the semi-cured epoxy resin composition, which is a semi-cured molded product, is taken out. fully cured. The post-curing step can be performed by collectively leaving a plurality of semi-cured molded products taken out of the mold 1 on a heating stage or in a heating oven. Post-curing after removing the semi-cured molded product from the mold can be performed by heating at 100° C. or higher for 2 hours, for example.
As a result, an electronic component 5 in which the electronic component element 2 is covered and protected by the completely cured product 4 of the epoxy resin composition is obtained as shown in FIG. In the electronic component 5, the ends of the terminals 2a protrude outside the cured product 4 so that they can be connected to other devices.

EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. The materials used in the following examples and comparative examples are as shown in Table 1.

(Examples 1 to 8 and Comparative Examples 1 to 7)
A main agent was prepared by putting each component of the type and compounding amount described in the column of main agent in Table 2 into a universal mixer heated to 100° C. and mixing under vacuum for 1 hour. Next, each component of the type and compounding amount described in the column of the curing agent in Table 2 was put into a universal mixer heated to 60° C. and mixed under vacuum for 1 hour to prepare a curing agent. An epoxy resin composition for casting was prepared by mixing 100 parts by weight of the curing agent with 100 parts by weight of the main agent using a universal mixer.
In addition, in Table 2, a blank represents no compounding.

The properties of the casting epoxy resin compositions prepared in Examples 1 to 8 and Comparative Examples 1 to 7 and the properties of the cured products were measured and evaluated under the following measurement conditions. The evaluation results are shown in Table 2.

<Evaluation items>
(resin composition)
(1) Viscosity (main agent, hardener, mixture of main agent/hardener)
Based on the viscosity measurement method of JIS C 2105:2006, spindle No. 25 at a temperature of 60° C. and a rotation speed of 10 to 20 rpm.

(2) Gelation time In accordance with the test tube method of JIS C 2105:2006, weigh 10 g of the epoxy resin composition for casting into a test tube, and gel the resin composition in an oil bath at 110°C. We measured the time to Moreover, the temperature of the oil bath was changed to 140° C., and the time until gelation of the resin composition was similarly measured.

(3) Ash (sedimentation)
After injecting 40 g of the main agent into a plastic test tube, it was allowed to stand at 80° C. for 20 days. After injecting 40 g of the curing agent into a plastic test tube, it was left at 60° C. for 20 days. After standing, 10 mm of the upper part of the resin portion of each of the main agent and the curing agent was tested, baked, and the ash content (X _a ) was measured. Similarly, a 10-mm lower portion of the resin portion was tested and fired to measure the ash content (X _b ). A ratio (X _a /X _b ) was calculated from the ash content of the upper portion (X _a ) and the ash content of the lower portion (X _b ).
The firing was performed in an electric furnace at 450° C. for 1 hour and then at 950° C. for 2 hours.
A ratio (X _a /X _b ) closer to 1.00 indicates less filler sedimentation. A ratio (X _a /X _b ) of 0.8 or more was judged as good, and a ratio of less than 0.8 was judged as poor.

(cured product)
(4) Glass transition point (Tg)
The epoxy resin composition for casting was cured at 70°C for 2 hours, 90°C for 2 hours, and finally at 110°C for 2 hours. , the temperature was raised from room temperature (25° C.) to 250° C. (heating rate of 10° C./min), and the thermal expansion curve was measured and obtained from the midpoint of the displacement point.

(5) Filler sedimentation of cured product (uniformity of cured product)
After pouring 40 g of the mixture of the main agent and the curing agent into a plastic test tube, the mixture was cured at 100° C. for 1 hour, then at 120° C. for 1 hour, and finally at 150° C. for 2 hours. The upper 10 mm of the cured product was cut to measure the specific gravity (S _a ) of the cured product. Similarly, 10 mm of the lower portion of the cured product was cut to measure the specific gravity (S _b ) of the cured product. A ratio (S _a /S _b ) was calculated from the upper cured product specific gravity (S a ) and the lower cured product specific gravity (S _{b )} .
It should be noted that the closer the ratio (S _a /S _b ) is to 1.00, the less sedimentation of the filler.

(6) Heat resistance (heat loss)
A sample was prepared by curing the casting epoxy resin composition at 100° C. for 2 hours. The shape of the test piece was 50 mm in diameter and 3 mm in thickness. The test piece was left in a dryer at 200° C. to 250° C. and taken out every hour to measure the weight reduction. Life time was estimated from the rate of decrease at each temperature, and the temperature at which the temperature decreased by 3% for 20,000 hours was calculated.

(7) E-LIM formability (presence or absence of voids)
Using the mold 1 shown in FIG. 1, an electronic component element was sealed with the prepared epoxy resin composition for casting. That is, first, an electronic component element to be sealed was accommodated in the concave portion 11a of the lower mold 11 of the mold 1, and the upper mold 12 was fitted to assemble the mold 1. As shown in FIG. Next, the epoxy resin composition was introduced into the nozzle main pipe 15b of the injection nozzle 15, and the cavity 13 between the lower mold 11 and the upper mold 12 was evacuated to 10 Torr by a vacuum pump. The plunger 15c is operated to inject and fill the epoxy resin composition into the cavity 13 at a filling speed of 0.5 L/min and an injection temperature of 60° C., and then the lower mold 11 and the upper mold 12 are heated under a pressure of 0.5 MPa. Then, the epoxy resin composition was cured by heating at 100° C. for 10 minutes. After that, the mold 1 is opened, and the cured product is taken out from the mold 1 and then post-cured under the conditions of 100° C. for 2 hours, 150° C. for 2 hours, and 180° C. for 2 hours, and sealed with resin. manufactured electronic components.
The molded electronic component was cut along an arbitrary cut surface, and the presence or absence of voids in the cured product on the cut surface was visually confirmed.

(8) Moisture Permeability Test The casting epoxy resin composition was cured at 100° C. for 2 hours to prepare a test piece having a diameter of 70 mm and a thickness of 1 mm. Using the test piece, a moisture permeability test was conducted based on the JIS Z0208:1976 moisture permeability test method for moisture-proof packaging materials.
The temperature and humidity conditions were 85°C/85% RH. For the measurement, a test piece and a moisture absorbent/calcium chloride (anhydrous) were enclosed in a moisture permeable cup, weighed after 2000 hours, and the increase in mass of the cup was evaluated as the amount of permeation of water vapor (water absorption).
Incidentally, the lower the water absorption, the higher the moisture permeability.

(9) Dielectric constant of cured product (comparison of capacitor capacitance)
As a measure of the uniformity of the cured product, the dielectric constant value was investigated. The curing conditions were 100° C. for 2 hours. After casting the resin composition into a cylindrical container having a diameter of 100 mm×50 mm, the cured product portion having a thickness of 2 mm was cut from each of the upper portion and the lower portion to obtain a test piece. A test piece was used for measurement after coating the main electrode, the guard electrode, and the high-voltage side with a conductive paint.
The smaller the difference between the dielectric constants of the upper portion and the lower portion of the cured product, the higher the uniformity of the cured product.

(10) Dielectric Breakdown Voltage A sample was prepared by curing an epoxy resin composition for casting at 100° C. for 2 hours. The dielectric breakdown voltage was measured according to IEC 60243-1:2013 using a dielectric breakdown tester (manufactured by Tokyo Seiden Co., Ltd.). The unit is MΩ/m.

(11) Thermal cycle test (crack resistance)
A thermal cycle test was performed on the electronic component molded by the method (7) above. One cycle of test conditions was from -40°C/30 minutes to 110°C/30 minutes, and 1000 cycles were carried out. After the test, the cross section of the sample was cut, and the presence or absence of cracks was visually confirmed.

(12) Reliability test After leaving the electronic component molded by the method of (7) above in an atmosphere of 85 ° C. and 85% Rh, an LCR meter (manufactured by Keysight Technologies, model number: 4284A) was used to measure the capacitance, and the time until an abnormality occurred was examined and evaluated according to the following criteria.
A: No abnormality occurred after 1000 hours or more B: Abnormality occurred after 800 hours or more and less than 1000 hours C: Abnormality occurred after 600 hours or more but less than 800 hours D: Abnormality occurred after 400 hours or more and less than 600 hours means that the capacitance of the capacitor has decreased by 10% or more.

(D) Examples 1 to 8 using a casting epoxy resin composition containing an organophilic phyllosilicate exhibit little sedimentation of the filler during storage and after curing, low moisture permeability, and excellent heat resistance. , a cured product with excellent uniformity can be obtained, and a resin part with excellent reliability can be formed in an electronic component.

REFERENCE SIGNS LIST 1 mold 2 electronic component element 2a terminal 3 epoxy resin composition for casting 4 (fully) cured epoxy resin composition 5 electronic component 11 lower mold 11a concave portion of lower mold 12 upper mold 12a concave portion of upper mold 13 cavity 14 Sprue 15 Injection nozzle 15a Tip of injection nozzle 15b Nozzle main pipe 15c Plunger 16 Seal member

Claims (11)

(A) an epoxy resin, (B) an acid anhydride, (C) an inorganic filler, (D) a clay thickener consisting of a mixture of needle-shaped sepolite and rod-shaped saponite , and (E) a curing accelerator. Epoxy resin composition for casting. 2. The epoxy casting composition according to claim 1, further comprising (F) a fumed metal oxide. (A) an epoxy resin, (C) an inorganic filler, and (D) a main agent containing a clay thickener consisting of a mixture of needle-shaped sepolite and rod-shaped saponite , (B) an acid anhydride, and (C) an inorganic 2. The casting epoxy resin composition of claim 1 , comprising a filler, (D) a clay thickener comprising a mixture of needle-shaped sepolite and rod-shaped saponite , and (E) a curing agent containing a curing accelerator. thing. (A) an epoxy resin, (C) an inorganic filler, (D) a clay thickener comprising a mixture of needle-shaped sepolite and rod-shaped saponite, and/or (F) a main agent containing a fumed metal oxide, and (B ) an acid anhydride, (C) an inorganic filler, (D) a clay thickener comprising a mixture of needle-shaped sepolite and rod-shaped saponite , and (E) a curing agent containing a curing accelerator. The epoxy resin composition for casting described in . 5. The casting according to claim 3 or 4, wherein the hardening agent contains 0.1 to 2.0% by mass of (D) a clay thickener comprising a mixture of needle-shaped sepolite and rod-shaped saponite. epoxy resin composition for 6. The method according to claim 4 or 5, wherein the main agent contains (F) a fumed metal oxide, and the content of the (F) fumed metal oxide contained in the main agent is 0.1 to 2.0% by mass. Epoxy resin composition for casting as described. The epoxy resin composition for casting according to any one of claims 1 to 6, wherein the (A) epoxy resin comprises a bisphenol A epoxy resin, an alicyclic epoxy resin, and a polynuclear epoxy resin. The epoxy resin composition for casting according to any one of claims 1 to 7, wherein the inorganic filler (C) is spherical fused silica. The casting epoxy according to any one of claims 1 to 8, wherein (D) the clay thickener comprising a mixture of needle-shaped sepolite and rod-shaped saponite has a pH of 6 to 9 when dispersed in water. Resin composition. An electronic component molded from the casting epoxy resin composition according to any one of claims 1 to 9. An electronic component element is placed in a mold, the casting epoxy resin composition according to any one of claims 1 to 9 is injected into the mold, semi-cured, and then removed from the mold, A method for manufacturing an electronic component, characterized in that the epoxy resin composition is completely cured by post-curing.

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