JP7732282B2 - Encapsulating resin composition and electronic device - Google Patents

Description

The present invention relates to an encapsulating resin composition and an electronic device manufactured using the encapsulating resin composition as an encapsulant.

In recent years, as heat-generating electronic components such as ICs have become more sophisticated and faster, the amount of heat generated by the electronic devices they are installed in has increased, and semiconductor encapsulants are also required to have high heat dissipation properties. To improve the thermal conductivity of resin compositions, it is common to fill them with inorganic fillers such as aluminum nitride, boron nitride, alumina, and crystalline silica. Of these, alumina, which offers an excellent balance of thermal conductivity, chemical stability, and cost, is the most commonly used heat-dissipating filler.

However, when the amount of alumina powder added to the resin increases, the viscosity of the resin composition increases, reducing moldability and resulting in reduced productivity. Furthermore, because alumina has a high Mohs hardness, contact with the metal parts of a mold when the viscosity is high can easily cause wear on the equipment. To solve these problems, it is necessary to reduce the viscosity of the resin composition filled with alumina powder. Proposed methods for adjusting the viscosity of resin compositions include using alumina that is nearly spherical rather than irregularly shaped, such as crushed or without cutting edges, and blending alumina particles with several different average particle sizes into the resin (see, for example, Reference 1).

Patent Document 1 discloses a highly thermally conductive inorganic powder that is a mixture of spherical inorganic powder with a particle size range of 3 to 40 μm and a circularity of 0.80 or more, and spherical or non-spherical inorganic powder with a particle size range of 0.1 to 1.5 μm and a circularity of 0.30 or more but less than 0.80. The examples also disclose an alumina mixed powder containing non-spherical aluminum oxide powder with an average particle size of 0.5 μm or 0.3 μm and spherical aluminum oxide powder with an average particle size of 15 μm or 8 μm.

Japanese Patent Application Laid-Open No. 2003-137627

However, with the technology described in Patent Document 1, when a high amount of alumina powder is added, the resin composition experiences a significant increase in viscosity, leaving room for improvement in the moldability of the resin composition and the reliability of the resulting electronic devices.

The present invention has been developed in consideration of the above-mentioned problems, and aims to provide an encapsulating resin composition that exhibits high fluidity and excellent moldability during molding, and high thermal conductivity and excellent heat dissipation properties when cured, as well as an electronic device manufactured using the same that exhibits excellent reliability.

The inventors discovered that by using a combination of alumina particles and aluminum oxide/aluminum borate composite particles as an inorganic filler, it is possible to obtain an encapsulating resin composition that exhibits high fluidity during molding and high thermal conductivity during curing, leading to the completion of the present invention.

According to the present invention,
Epoxy resin,
a phenolic resin hardener;
A curing accelerator;
an inorganic filler including a first inorganic filler and a second inorganic filler;
An encapsulating resin composition comprising:
the inorganic filler is contained in an amount of 80% by mass or more and 95% by mass or less with respect to the entire encapsulating resin composition,
the first inorganic filler comprises first spherical alumina particles having a 50% volume cumulative particle diameter D50 of 10 μm or more and 50 μm or less, and second spherical alumina particles having a 50% volume cumulative particle diameter D50 of 0.1 μm or more and less than 10 μm;
the second inorganic filler is a composite particle containing aluminum oxide and aluminum borate,
the composite particles are composed of small-sized composite particles having a 50% volume cumulative particle diameter D50 of 0.5 μm or more and 5 μm or less, and large-sized composite particles having a 50% volume cumulative particle diameter D50 of 5 μm or more and 20 μm or less,
the first spherical alumina particles are contained in an amount of 60% by volume or more and 80% by volume or less based on the total volume of the inorganic filler;
the second spherical alumina particles are contained in an amount of 5% by volume or more and 20% by volume or less based on the total volume of the inorganic filler;
the small particle size composite particles are contained in an amount of 5% by volume or more and 15% by volume or less based on the total volume of the inorganic filler;
The large particle size composite particles are contained in an amount of 5% by volume or more and 15% by volume or less based on the total volume of the inorganic filler.
An encapsulating resin composition is provided.

Further, according to the present invention,
A semiconductor element;
an encapsulant that encapsulates the semiconductor element,
The electronic device is provided, wherein the encapsulant is made of a cured product of the encapsulating resin composition.

The present invention provides an encapsulating resin composition that exhibits high fluidity and excellent moldability during molding, and high thermal conductivity and excellent heat dissipation properties when cured, as well as highly reliable electronic devices manufactured using the same.

FIG. 1 is a diagram showing a cross-sectional structure of an example of a double-sided sealed electronic device manufactured using the resin composition of the present embodiment. FIG. 1 is a diagram showing a cross-sectional structure of an example of a single-sided sealed electronic device manufactured using the resin composition of the present embodiment.

Embodiments of the present invention will be described below with reference to the drawings. In all drawings, similar components are designated by similar reference numerals, and descriptions will be omitted where appropriate. Furthermore, all drawings are for illustrative purposes only. The shapes and dimensional ratios of each component in the drawings do not necessarily correspond to actual products. In this specification, the notation "a to b" in describing a range of values means "a or more and b or less," unless otherwise specified. For example, "5 to 90% by mass" means "5% by mass or more and 90% by mass or less."

Hereinafter, an embodiment of the present invention will be described.
The encapsulating resin composition of the present embodiment (hereinafter may be simply referred to as "resin composition") is a resin material used as an encapsulant for encapsulating a semiconductor element mounted on a substrate, and contains an epoxy resin, a phenolic resin curing agent, a curing accelerator, and an inorganic filler containing a first inorganic filler and a second inorganic filler, wherein the first inorganic filler is alumina particles, and the second inorganic filler is composite particles containing aluminum oxide and aluminum borate.

The resin composition of this embodiment contains a combination of alumina particles and aluminum oxide/aluminum borate composite particles as inorganic fillers, thereby achieving both high fluidity during molding and high thermal conductivity of the cured product.

The components used in the resin composition of this embodiment are described below.

(epoxy resin)
Examples of epoxy resins used in the semiconductor encapsulation resin composition of this embodiment include crystalline epoxy resins such as bisphenol type epoxy resins, such as bisphenol A type epoxy resins, bisphenol F type epoxy resins, and tetramethylbisphenol F type epoxy resins, biphenyl type epoxy resins, stilbene type epoxy resins, and hydroquinone type epoxy resins; novolac type epoxy resins such as cresol novolac type epoxy resins, phenol novolac type epoxy resins, and naphthol novolac type epoxy resins; phenylene skeleton-containing phenol aralkyl type epoxy resins, biphenylene skeleton-containing phenol aralkyl type epoxy resins, and the like. Examples of suitable epoxy resins include phenol aralkyl epoxy resins such as alkyl-type epoxy resins, phenylene skeleton-containing naphthol aralkyl epoxy resins, and alkoxynaphthalene skeleton-containing phenol aralkyl epoxy resins; trifunctional epoxy resins such as triphenolmethane epoxy resins and alkyl-modified triphenolmethane epoxy resins; modified phenol epoxy resins such as dicyclopentadiene-modified phenol epoxy resins and terpene-modified phenol epoxy resins; and heterocycle-containing epoxy resins such as triazine nucleus-containing epoxy resins. These may be used alone or in combination of two or more. Among these, biphenyl epoxy resins are preferred because they can maintain an optimal melt viscosity, have good moldability, and are low cost. The epoxy equivalent of the epoxy resin is preferably 90 to 300. If the epoxy equivalent is too low, reactivity with the curing agent tends to decrease. If the epoxy equivalent is too high, the strength of the cured product of the resin composition tends to decrease.

The epoxy resin preferably contains at least one of bisphenol-type epoxy resin, biphenyl-type epoxy resin, novolac-type epoxy resin (e.g., o-cresol novolac epoxy resin), phenol aralkyl-type epoxy resin, and triphenol methane-type epoxy resin. Phenol aralkyl-type epoxy resin with a biphenylene skeleton is particularly preferred for controlling the high-temperature elastic modulus.

The epoxy resin may contain at least one selected from the group consisting of epoxy resins represented by the following general formula (1), epoxy resins represented by the following general formula (2), epoxy resins represented by the following general formula (3), epoxy resins represented by the following general formula (4), and epoxy resins represented by the following general formula (5). Among these, epoxy resins containing one or more selected from the epoxy resins represented by the following general formula (1) and the epoxy resins represented by the following general formula (4) are preferred.

In general formula (1),
Ar ¹ represents a phenylene group or a naphthylene group, and when Ar ¹ is a naphthylene group, the glycidyl ether group may be bonded to either the α-position or the β-position.
^Ar2 represents any one of a phenylene group, a biphenylene group, and a naphthylene group.
R _{1 a} and R 1 _b each independently represent a hydrocarbon group having 1 to 10 carbon atoms.
g is an integer of 0 to 5, and h is an integer of 0 to 8. ⁿ³ represents the degree of polymerization, and its average value is 1 to 3.

In general formula (2),
A plurality of Rc's each independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms.
ⁿ⁵ represents the degree of polymerization, and its average value is 0 to 4.

In general formula (3),
A plurality of R _d and R _e each independently represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms.
ⁿ⁶ represents the degree of polymerization, the average value of which is 0 to 4.

In general formula (4),
A plurality of _Rfs each independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms.
ⁿ⁷ represents the degree of polymerization, and its average value is 0 to 4.

In general formula (5),
A plurality of R _g 's each independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms.
n ⁸ represents the degree of polymerization, the average value of which is 0 to 4.

The number molecular weight of the epoxy resin is not particularly limited and may be appropriately selected from the viewpoints of flowability, curability, etc. As an example, the number molecular weight is about 100 to 700. Furthermore, from the viewpoint of flowability, etc., the ICI viscosity of the epoxy resin at 150°C is preferably 0.1 to 5.0 poise.
The epoxy resins may be used alone or in combination of two or more.

The epoxy equivalent of the epoxy resin is preferably 100 to 400 g/eq, more preferably 150 to 350 g/eq. If the encapsulating resin composition contains multiple types of epoxy resins, it is preferable that the overall epoxy equivalent of the multiple types of epoxy resins be within the above numerical range.

The amount of epoxy resin contained is not particularly limited, but is preferably 1% by mass or more, and more preferably 2% by mass or more, relative to the total amount of the resin composition. If the lower limit of the blending ratio is within this range, there is little risk of a decrease in fluidity during the encapsulation process. Furthermore, there is also no particular limit to the upper limit of the blending ratio of the entire resin composition, but it is preferably 20% by mass or less, and more preferably 15% by mass or less, relative to the total amount of the resin composition. If the upper limit of the blending ratio is within this range, there is little decrease in the glass transition temperature of the resin composition.

(Phenol resin hardener)
Examples of phenolic resin curing agents used in the resin composition of this embodiment include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, bisphenol novolac, and phenol-biphenyl novolac resin; polyvinylphenol; multifunctional phenolic resins such as triphenolmethane-type phenolic resin; modified phenolic resins such as terpene-modified phenolic resin and dicyclopentadiene-modified phenolic resin; phenol aralkyl-type phenolic resins such as phenylene and/or biphenylene skeleton-containing phenol aralkyl resin and phenylene and/or biphenylene skeleton-containing naphthol aralkyl resin; and bisphenol compounds such as bisphenol A and bisphenol F. As the phenolic resin curing agent, one or a combination of two or more of the above specific examples can be used. Of the above specific examples, the phenolic resin curing agent preferably contains a phenylene and/or biphenylene skeleton-containing phenol aralkyl resin. This allows for good curing of the epoxy resin in the resin composition.

The lower limit of the blending ratio of the phenolic resin curing agent is not particularly limited, but is preferably 0.5% by mass or more, and more preferably 1% by mass or more, of the total resin composition. A lower limit within this range ensures sufficient fluidity. The upper limit of the blending ratio of the curing agent is also not particularly limited, but is preferably 15% by mass or less, and more preferably 10% by mass or less, of the total resin composition. A higher limit within this range ensures the desired fluidity and meltability of the resin composition.

Furthermore, the compounding ratio of the epoxy resin to the phenolic resin-based curing agent is preferably such that the equivalent ratio (EP)/(OH) between the number of epoxy groups (EP) in the epoxy resin and the number of phenolic hydroxyl groups (OH) in the phenolic resin-based curing agent is 0.8 or more and 1.3 or less. When the equivalent ratio is within this range, sufficient curing can be achieved when the resin composition is molded. Furthermore, when the equivalent ratio is within this range, the fluidity and meltability of the resin composition can be adjusted to desired ranges.

(Curing accelerator)
The curing accelerator used in the resin composition of this embodiment can be any accelerator that can accelerate the curing reaction between the phenolic resin and the phenolic resin curing agent, and is not particularly limited. Examples of the accelerator include onium salt compounds; organic phosphines such as triphenylphosphine, tributylphosphine, and trimethylphosphine; tetra-substituted phosphonium compounds; phosphobetaine compounds; adducts of phosphine compounds and quinone compounds; adducts of phosphonium compounds and silane compounds; imidazole compounds such as 2-methylimidazole, 2-ethyl-4-methylimidazole (EMI24), 2-phenyl-4-methylimidazole (2P4MZ), 2-phenylimidazole (2PZ), 2-phenyl-4-methyl-5-hydroxyimidazole (2P4MHZ), and 1-benzyl-2-phenylimidazole (1B2PZ); and tertiary amines such as 1,8-diaza-bicyclo[5.4.0]undecene-7 (DBU), triethanolamine, and benzyldimethylamine. These may be used alone or in combination of two or more.

The content of the curing accelerator is preferably 0.1% by mass or more and 2% by mass or less, based on the total amount of the epoxy resin and phenolic resin curing agent. If the content of the curing accelerator is less than the above lower limit, the curing acceleration effect may not be enhanced. On the other hand, if the content is more than the above upper limit, problems with flowability and moldability may occur, and production costs may increase.

(inorganic filler)
The resin composition of the present embodiment contains a combination of alumina particles as a first inorganic filler and composite oxide particles as a second inorganic filler. Each inorganic filler will be described below.

(Alumina particles)
The alumina particles used in the resin composition of this embodiment have the effect of imparting thermal conductivity to the resin composition. Alumina particles have higher thermal conductivity than other inorganic fillers such as silica particles, making thermal design easier when used as a sealant. Furthermore, alumina particles are less expensive than other inorganic fillers (e.g., magnesium oxide, boron nitride, aluminum nitride, diamond, etc.) that have higher thermal conductivity than silica particles, and are also easier to increase sphericity and have excellent heat resistance.

In one embodiment, the alumina particles include first alumina particles having a 50% volume cumulative particle size D50 of 10 to 50 μm as measured by laser diffraction scattering.

In a preferred embodiment, the alumina particles include, in addition to the first alumina particles, second alumina particles having a 50% volume cumulative particle size D50 of 0.1 μm or more and 10 μm or less.

If the 50% volume cumulative particle diameter D50 of the alumina particles is less than 0.1 μm, the viscosity of the resin composition will be extremely high, resulting in poor filling properties and workability in the encapsulation process. Furthermore, if the 50% volume cumulative particle diameter D50 of the alumina particles is less than 0.1 μm, the elastic modulus of the cured resin composition will decrease, resulting in warping of the resulting package. On the other hand, if the 50% volume cumulative particle diameter D50 of the alumina particles exceeds 50 μm, there is a risk of poor filling. Even if filling is possible, voids will be generated during filling, making this method inappropriate. By incorporating a combination of the first and second alumina particles described above, the encapsulating resin composition of the present invention can achieve both good filling properties and good workability in the encapsulation process.

When first alumina particles having a 50% volume cumulative particle size D50 of 10 to 50 μm are used in combination with second alumina particles having a 50% volume cumulative particle size D50 of 0.1 μm or more and 10 μm or less, the proportion of the first alumina particles to the total alumina particles is 60 to 100% by volume, and preferably 80 to 100% by volume.

By using alumina particles with the above particle size distribution, fluidity is improved, which results in good workability in the sealing process and reduced filling defects, making it possible to obtain a resin composition suitable as a sealant.

The shape of the alumina particles is not particularly limited and may be spherical, flaky, granular, or powdery.

In a preferred embodiment, the alumina particles preferably include spherical alumina particles having a sphericity of 0.8 or greater, preferably 0.9 or greater. Such spherical alumina particles exist in a state close to the closest packing in the encapsulant, thereby improving the thermal conductivity of the resulting encapsulant. Furthermore, resin compositions containing such spherical alumina have improved fluidity and are easy to handle during the encapsulation process.

Here, in this specification, "sphericity" is defined as "the ratio of the minimum diameter to the maximum diameter of a particle" in a two-dimensional image observed with a scanning electron microscope (SEM). In other words, in this embodiment, this refers to a ratio of the minimum diameter to the maximum diameter of an alumina particle in a two-dimensional image observed with a scanning electron microscope (SEM) of 0.8 or more.

(composite particles)
The encapsulating resin composition of this embodiment contains composite particles containing aluminum oxide and aluminum borate as the second inorganic filler. Examples of the composite particles include composite particles composed of aluminum oxide, aluminum borate, and titanium dioxide, composite particles composed of aluminum oxide, aluminum borate, and tungsten trioxide, or combinations thereof. Examples of commercially available composite particles include Dipyroxide #7321, #7323, and #7330 manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.

The 50% volume cumulative particle size D50 of the composite particles that are the second inorganic filler is, for example, 0.5 μm or more and 20 μm or less, and preferably 0.5 μm or more and 15 μm or less.

In one embodiment, the particle size distribution curve representing the volume-based frequency distribution of the composite particles that are the second inorganic filler has two peaks between 0.5 and 20 μm, and preferably between 0.5 and 15 μm.

The composite particles that are the second inorganic filler are not particularly limited and may be spherical, scaly, granular, or powder-like, but preferably have a rounded shape without corners, and the closer to a sphere the more preferable. This improves fluidity and allows for the production of a resin composition that is easy to handle during the encapsulation process.

The amount of composite particles blended is, for example, 1 to 30% by volume, and preferably 5 to 20% by volume, based on the total inorganic filler (total of the first and second inorganic fillers). Using an inorganic filler with such a particle size distribution improves fluidity, thereby improving workability in the encapsulation process and reducing filling defects, resulting in a resin composition suitable for use as an encapsulant.

The inorganic filler in the resin composition in one embodiment may be, for example, as in the following formulation examples: The blending amount in the following formulation examples is a ratio (volume %) to the total amount of inorganic filler used.
(Combination example 1)
First alumina particles having a 50% volume cumulative particle size D50 of 10 to 50 μm: 70 to 90% by volume
Composite particles with a 50% volume cumulative particle size D50 of 0.5 μm or more and 20 μm or less: 10 to 30% by volume
(Combination example 2)
First alumina particles having a 50% volume cumulative particle size D50 of 10 to 50 μm: 70 to 85% by volume
Second alumina particles having a 50% volume cumulative particle size D50 of 0.1 μm or more and 10 μm or less: 5 to 15% by volume
Composite particles with a 50% volume cumulative particle size D50 of 0.5 μm or more and 20 μm or less: 5 to 15% by volume
(Combination example 3)
First alumina particles having a 50% volume cumulative particle size D50 of 10 to 50 μm: 70 to 85
Small particle diameter composite particles having a 50% volume cumulative particle diameter D50 of 0.5 μm or more and 20 μm or less: 5 to 15% by volume
(Combination example 4)
First alumina particles having a 50% volume cumulative particle size D50 of 10 to 50 μm: 60 to 80% by volume
Second alumina particles having a 50% volume cumulative particle size D50 of 0.1 μm or more and 10 μm or less: 5 to 20% by volume
Small particle diameter composite particles having a 50% volume cumulative particle diameter D50 of 0.5 μm or more and 5 μm or less: 5 to 15% by volume
Large particle size composite particles with a 50% volume cumulative particle size D50 of 5 μm or more and 20 μm or less: 5 to 15% by volume

(Other inorganic fillers)
The resin composition of this embodiment may contain other inorganic fillers in addition to the above-mentioned alumina particles and composite oxide particles. Examples of other inorganic fillers include silica such as fused crushed silica, fused spherical silica, crystalline silica, and secondary agglomerated silica; calcium carbonate, magnesium oxide, silicon nitride, aluminum nitride, boron nitride, titanium oxide, silicon carbide, aluminum hydroxide, magnesium hydroxide, titanium white, talc, clay, mica, and glass fiber. The particle shape of these solid fillers is preferably as spherical as possible, and the loading amount can be increased by mixing fillers of different particle sizes.
When other inorganic fillers are used, the amount of the fillers to be added is preferably 0.5 to 5% by volume based on the total amount of the inorganic fillers.

The content of the inorganic filler is, for example, 80 to 95% by mass, preferably 85 to 95% by mass, and more preferably 88 to 95% by mass, based on the total resin composition. The amount of inorganic filler refers to the total amount of the first inorganic filler, the second inorganic filler, and, if used, the other inorganic fillers described above. By using the inorganic filler in the above-mentioned amount, the resulting resin composition has high thermal conductivity and excellent workability.

(Other additives)
The resin composition of this embodiment may further contain other additives in addition to the above-mentioned components, as needed. Examples of other additives include coupling agents, fluidity imparting agents, mold release agents, ion scavengers, stress reducing agents, colorants, and flame retardants. Representative components are described below.

(Coupling Agent)
Specific examples of the coupling agent include vinyl silanes such as vinyltrimethoxysilane and vinyltriethoxysilane; epoxy silanes such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane; styryl silanes such as p-styryltrimethoxysilane; methacryl silanes such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane; acrylic silanes such as 3-acryloxypropyltrimethoxysilane; N-2-(aminoethyl)-3-amino Examples of the coupling agent include aminosilanes such as N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and phenylaminopropyltrimethoxysilane; isocyanurate silanes; alkyl silanes; ureidosilanes such as 3-ureidopropyltrialkoxysilane; mercaptosilanes such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane; isocyanate silanes such as 3-isocyanatopropyltriethoxysilane; titanium-based compounds; aluminum chelates; and aluminum/zirconium-based compounds. The coupling agent may be a combination of one or more of the above specific examples.

(Fluidity imparting agent)
The fluidity imparting agent acts to suppress the reaction of non-latent curing accelerators, such as phosphorus atom-containing curing accelerators, during melt-kneading of the resin composition, thereby improving the productivity of the resin composition.Specific examples of the fluidity imparting agent include compounds in which hydroxyl groups are bonded to two or more adjacent carbon atoms constituting an aromatic ring, such as catechol, pyrogallol, gallic acid, gallic acid esters, 1,2-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, and derivatives thereof.

(Release agent)
Specific examples of the release agent include natural waxes such as carnauba wax, synthetic waxes such as Montan acid ester wax and oxidized polyethylene wax, higher fatty acids such as zinc stearate and metal salts thereof, paraffin, carboxylic acid amides such as erucic acid amide, etc. One or more of the above specific examples can be blended as the release agent.

(Ion scavenger)
Specific examples of the ion scavenger include hydrotalcites such as hydrotalcite and hydrotalcite-like substances, and hydrated oxides of elements selected from magnesium, aluminum, bismuth, titanium, and zirconium. One or more of the above specific examples can be blended as the ion scavenger.

(low stress agent)
Specific examples of the low stress agent include silicone compounds such as silicone oil and silicone rubber, polybutadiene compounds, and acrylonitrile-butadiene copolymer compounds such as acrylonitrile-carboxyl group-terminated butadiene copolymer compounds. One or more of the above specific examples can be blended as the low stress agent.

(Coloring agent)
Specific examples of the colorant include carbon black, red iron oxide, titanium oxide, etc. One or more of the above specific examples of the colorant may be blended.

(Flame retardant)
Specific examples of the flame retardant include aluminum hydroxide, magnesium hydroxide, zinc borate, zinc molybdate, phosphazene, carbon black, etc. One or more of the above specific examples may be blended as the flame retardant.

(Production of encapsulating resin composition)
The resin composition of this embodiment can be produced by uniformly mixing the above components and optional additives to a predetermined content using a mixer or blender such as a tumbler mixer or Henschel mixer, and then kneading the mixture while heating using a kneader, roll, disper, azimuth homomixer, planetary mixer, or the like. The kneading temperature must be within a range in which a curing reaction does not occur, and although this varies depending on the composition of the epoxy resin and phenolic resin curing agent, melt-kneading at approximately 70 to 150°C is preferred. After kneading, the mixture may be cooled and solidified, and the kneaded mixture may be processed into powder, granules, tablets, or sheets.

One method for obtaining a granular resin composition is to pulverize the kneaded material using a pulverizer. The kneaded material may also be formed into a sheet and then pulverized. Examples of pulverizers that can be used include a hammer mill, a stone mill, and a roll crusher.

One method for obtaining a granular or powdered resin composition is to use a granulation method, such as the hot-cut method, in which a small-diameter die is installed at the outlet of a kneading device and the molten mixture ejected from the die is cut to a predetermined length using a cutter or similar. In this case, after obtaining a granular or powdered resin composition using a granulation method such as the hot-cut method, it is preferable to degas the resin composition before its temperature drops significantly.

The resin composition of this embodiment produced as described above has a thermal diffusivity of 2.52 mm ² /sec or more, preferably 2.55 mm 2 /sec or more, and more preferably 2.57 mm ² /sec or more, of the cured product measured by the laser ^flash method.

Furthermore, the thermal conductivity of the cured product of the resin composition of this embodiment, as measured by the laser flash method, is 8.32 W/m·K or more, preferably 8.42 W/m·K or more, more preferably 8.48 W/m·K or more, and particularly preferably 8.58 W/m·K or more.

The melt viscosity of the resin composition of this embodiment is, for example, 1 to 150 Pa·s or more, and preferably 5 to 100 Pa·s. If the viscosity is less than this value, the inorganic filler may settle, and a uniform molded product may not be obtained. If the viscosity exceeds this value, the filling ability may decrease, and voids or unfilled areas may occur. Here, the melt viscosity is the melt viscosity of the resin composition when measured using a high-performance flow tester with a slit diameter of 0.5 mm, a measurement temperature of 175°C, and a load of 40 kgf.

(electronic equipment)
An example of an electronic device manufactured using the encapsulating resin composition according to this embodiment as a encapsulant will be described.
FIG. 1 is a cross-sectional view showing a double-sided sealed electronic device 100 according to this embodiment.
The semiconductor device 100 of this embodiment comprises an electronic element 20, a bonding wire 40 connected to the electronic element 20, and a sealing material 50, the sealing material 50 being composed of a cured product of the resin composition described above.

More specifically, the electronic element 20 is fixed to the substrate 30 via the die attach material 10, and the electronic device 100 has outer leads 34 connected via bonding wires 40 to electrode pads (not shown) provided on the electronic element 20. The bonding wires 40 can be set taking into consideration the electronic element 20 being used, and for example, Cu wires can be used.

Figure 2 shows the cross-sectional structure of an example of a single-sided sealed electronic device obtained by sealing an electronic element mounted on a circuit board using the resin composition of this embodiment. An electronic element 401 is fixed to a circuit board 408 via a die attach material 402. Electrode pads 407 of the electronic element 401 are connected to electrode pads 407 on the circuit board 408 by bonding wires 404. The surface of the circuit board 408 on which the electronic element 401 is mounted is sealed with a sealing material 406 composed of a cured product of the resin composition of this embodiment. The electrode pads 407 on the circuit board 408 are internally bonded to solder balls 409 on the non-sealed side of the circuit board 408.

A method for manufacturing a semiconductor device using the encapsulating resin composition according to this embodiment will be described below.
The semiconductor device according to this embodiment is manufactured, for example, by the steps of obtaining an encapsulating resin composition by the above-described method for manufacturing an encapsulating resin composition, mounting an electronic element on a substrate, and encapsulating the electronic element using the encapsulating resin composition. Techniques that can be used to form the encapsulant include, for example, transfer molding, compression molding, and injection molding. The encapsulating step is performed by curing the resin composition at a temperature of about 80°C to 200°C for about 10 minutes to 10 hours.

Types of electronic elements that can be encapsulated include, but are not limited to, semiconductor elements such as integrated circuits, large-scale integrated circuits, transistors, thyristors, diodes, and solid-state imaging devices. The resulting electronic device may be in the form of, but is not limited to, a dual in-line package (DIP), a plastic leaded chip carrier (PLCC), a quad flat package (QFP), a low-profile quad flat package (LQFP), a small outline package (SOP), a small outline J-lead package (SOJ), a thin small outline package (TSOP), a thin quad flat package (TQFP), a tape carrier package (TCP), a ball grid array (BGA), and a chip-size package (CSP).

Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted.
Examples of embodiments are given below.
1. Epoxy resin;
a phenolic resin hardener;
A curing accelerator;
an inorganic filler including a first inorganic filler and a second inorganic filler;
An encapsulating resin composition comprising:
the first inorganic filler is alumina particles,
the second inorganic filler is a composite particle containing aluminum oxide and aluminum borate;
Sealing resin composition.
2. The encapsulating resin composition according to 1., wherein the second inorganic filler includes composite particles composed of aluminum oxide, aluminum borate, and titanium dioxide, composite particles composed of aluminum oxide, aluminum borate, and tungsten trioxide, or a combination thereof.
3. The encapsulating resin composition according to 1. or 2., wherein the second inorganic filler has a 50% volume cumulative particle size D50 of 0.5 μm or more and 20 μm or less.
4. The encapsulating resin composition according to any one of 1. to 3., wherein a particle size distribution curve representing a volume-based frequency distribution of the second inorganic filler has two peaks between 0.5 and 20 μm.
5. The encapsulating resin composition according to any one of 1. to 4., wherein the second inorganic filler has a rounded shape without corners.
6. The encapsulating resin composition according to any one of 1. to 5., wherein the alumina particles include spherical alumina.
7. The encapsulating resin composition according to any one of 1. to 6., wherein the alumina particles include alumina particles having a 50% volume cumulative particle size D50 of 10 μm or more and 50 μm or less.
8. The encapsulating resin composition according to 7., wherein the alumina particles further include alumina particles having a 50% volume cumulative particle size D50 of 0.1 μm or more and less than 10 μm.
9. The encapsulating resin composition according to any one of 1. to 8., wherein the inorganic filler is contained in an amount of 80% by mass or more and 95% by mass or less with respect to the entire encapsulating resin composition.
10. The encapsulating resin composition according to any one of 1. to 9., wherein the melt viscosity of the encapsulating resin composition is 1 Pa s or more and 150 Pa s or less, as measured using a Koka type flow tester with a slit diameter of 0.5 mm, a measurement temperature of 175°C, and a load of 40 kgf.
11. The encapsulating resin composition according to any one of 1. to 10., wherein the inorganic filler further includes at least one selected from silica, calcium carbonate, aluminum hydroxide, magnesium oxide, boron nitride, aluminum nitride, talc, and mica.
12. The encapsulating resin composition according to any one of 1. to 11., further comprising a stress reducing agent.
13. A semiconductor element;
an encapsulant that encapsulates the semiconductor element,
13. An electronic device, wherein the encapsulant is a cured product of the encapsulating resin composition according to any one of 1. to 12.

The present invention will be explained below using examples and comparative examples, but the present invention is not limited to these.

The components used in the examples and comparative examples are shown below.
(epoxy resin)
Epoxy resin 1: Biphenyl-type epoxy resin having the following structural formula (manufactured by Mitsubishi Chemical Corporation, YX4000HK)

(Phenol resin hardener)
Curing agent 1: Novolac phenolic resin (manufactured by Sumitomo Bakelite Co., Ltd., PR-55617)

(Alumina particles)
Alumina particles 1: spherical alumina (average particle diameter (D50) 42 μm)
Alumina particles 2: spherical alumina (average particle diameter (D50) 0.6 μm)

(composite particles)
Composite particle 1: Dipyroxide #7321 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., a composite having a composition of 90 to 99% aluminum oxide/1 to 5% aluminum borate/<1% titanium dioxide (rutile), average particle size (D50) 1 μm)
Composite particle 2: Dipyroxide #7323 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., a composite having a composition of 90 to 99% aluminum oxide/1 to 5% aluminum borate/<1% tungsten trioxide, average particle size (D50) 3 μm)
Composite particle 3: Dipyroxide #7330 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., a composite having a composition of 90 to 99% aluminum oxide/1 to 5% aluminum borate/<1% tungsten trioxide, average particle size (D50) 10 μm)

(Coupling Agent)
Coupling agent 1: N-phenylaminopropyltrimethoxysilane (manufactured by Dow Corning Toray Co., Ltd., CF-4083)

(Curing accelerator)
Curing accelerator 1: A curing accelerator represented by the following formula (P1) (tetraphenylphosphonium bis(naphthalene-2,3-dioxy)phenylsilicate)

(wax)
Wax 1: Carnauba wax (TOWAX-132, manufactured by Toagosei Co., Ltd.)
Wax 2: Erucic acid amide (NOF Corporation, Alflow P-10)

(Coloring agent)
Colorant 1: Carbon black (ERS-2001, manufactured by Tokai Carbon Co., Ltd.)
(Ion scavenger)
Ion scavenger 1: magnesium aluminum hydroxide carbonate hydrate (manufactured by Kyowa Chemical Industry Co., Ltd., DHT-4H)

(low stress agent)
Low-stress agent 1: Epoxy polyether modified silicone oil (FZ-3730, manufactured by Toray Dow Corning Co., Ltd.)

( Reference Examples 1 to 6, Examples 7 and 8 , Comparative Example 1)
The raw materials having the composition shown in Table 1 were pulverized and mixed for 5 minutes using a supermixer. The mixed raw materials were then melt-kneaded in a co-rotating twin-screw extruder with a 65 mm cylinder inner diameter at a screw speed of 400 rpm and a resin temperature of 100°C. Next, the melt-kneaded resin composition was fed from above a 20 cm diameter rotor at a rate of 2 kg/hr, and the rotor was rotated at 3000 rpm to generate centrifugal force, causing the composition to pass through multiple small holes (1.2 mm diameter) on the outer periphery of a cylinder heated to 115°C. The mixture was then cooled to obtain a granular encapsulating resin composition. The resulting granular encapsulating resin composition was stirred for 3 hours in an air stream adjusted to 15°C and 55% RH.

(Evaluation of kneadability)
When the mixed raw materials were melt-kneaded at a resin temperature of 100°C in a co-rotating twin-screw extruder with a cylinder inner diameter of 65 mm, those that could be kneaded at a screw rotation speed of 200 rpm were evaluated as "good" for kneadability, and those that could not maintain a rotation speed of 200 rpm due to an increase in the rotation torque of the twin-screw extruder were evaluated as "fair." The results are shown in Table 1.

The encapsulating resin compositions obtained by the above method were evaluated for the following items by the methods described below.
(fluidity (spiral flow))
Using a low-pressure transfer molding machine (KTS-15, manufactured by Kotaki Seiki Co., Ltd.), the resin composition was injected into a spiral flow measurement mold conforming to EMMI-1-66 under conditions of a mold temperature of 175°C, an injection pressure of 6.9 MPa, and a dwell time of 120 seconds, and the flow length was measured. Spiral flow is an index of fluidity, with a larger value indicating better fluidity. The unit is cm.

(High-grade viscosity)
Using a Koka flow tester (Shimadzu Corporation, CFT-500C), the Koka viscosity was measured under the test conditions of a temperature of 175°C, a load of 40 kgf (piston area 1 cm ² ), a die hole diameter of 0.50 mm, and a die length of 1.00 mm. The unit of the Koka viscosity is Pa·s.

(thermal diffusivity)
The resulting encapsulating resin composition was heat-treated at 180°C and 10 MPa for 40 minutes to obtain a cured product. The thermal diffusivity ( ^m2 /s) of the cured product in the thickness direction was then measured using a laser flash method. The results are shown in Table 1.

The encapsulating resin composition of the example exhibited a good balance of thermal conductivity and fluidity, making it suitable for use as an encapsulating material.

10 Die attach material 20 Electronic element 30 Base material 32 Die pad 34 Outer lead 40 Bonding wire 50 Sealing material 100 Electronic device 401 Electronic element 402 Die attach material 404 Bonding wire 406 Sealing material 407 Electrode pad 408 Circuit board 409 Solder ball

Claims (9)

Epoxy resin,
a phenolic resin hardener;
A curing accelerator;
an inorganic filler including a first inorganic filler and a second inorganic filler;
An encapsulating resin composition comprising:
the inorganic filler is contained in an amount of 80% by mass or more and 95% by mass or less with respect to the entire encapsulating resin composition,
the first inorganic filler comprises first spherical alumina particles having a 50% volume cumulative particle diameter D50 of 10 μm or more and 50 μm or less, and second spherical alumina particles having a 50% volume cumulative particle diameter D50 of 0.1 μm or more and less than 10 μm;
the second inorganic filler is a composite particle containing aluminum oxide and aluminum borate,
the composite particles are composed of small-sized composite particles having a 50% volume cumulative particle diameter D50 of 0.5 μm or more and 5 μm or less, and large-sized composite particles having a 50% volume cumulative particle diameter D50 of 5 μm or more and 20 μm or less,
the first spherical alumina particles are contained in an amount of 60% by volume or more and 80% by volume or less based on the total volume of the inorganic filler;
the second spherical alumina particles are contained in an amount of 5% by volume or more and 20% by volume or less based on the total volume of the inorganic filler;
the small particle size composite particles are contained in an amount of 5% by volume or more and 15% by volume or less based on the total volume of the inorganic filler;
The large particle size composite particles are contained in an amount of 5% by volume or more and 15% by volume or less based on the total volume of the inorganic filler.
Sealing resin composition. The encapsulating resin composition according to claim 1, wherein the second inorganic filler includes composite particles composed of aluminum oxide, aluminum borate, and titanium dioxide, composite particles composed of aluminum oxide, aluminum borate, and tungsten trioxide, or a combination thereof. The encapsulating resin composition according to claim 1 or 2, wherein the 50% volume cumulative particle size D50 of the second inorganic filler is 0.5 μm or more and 20 μm or less. The encapsulating resin composition according to any one of claims 1 to 3, wherein the particle size distribution curve representing the volume-based frequency distribution of the second inorganic filler has two peaks between 0.5 and 20 μm. The encapsulating resin composition according to any one of claims 1 to 4, wherein the second inorganic filler has a rounded shape without any corners. 6. The encapsulating resin composition according to claim 1, wherein the melt viscosity of the encapsulating resin composition is 1 Pa s or more and 150 Pa s or less, as measured using a high-speed flow tester with a slit diameter of 0.5 mm, a measurement temperature of 175°C, and a load of 40 kgf. 7. The encapsulating resin composition according to claim 1 , wherein the inorganic filler further comprises at least one selected from the group consisting of silica, calcium carbonate, aluminum hydroxide, magnesium oxide, boron nitride, aluminum nitride, talc, and mica. The encapsulating resin composition according to claim 1 , further comprising a stress reducing agent. A semiconductor element;
an encapsulant that encapsulates the semiconductor element,
An electronic device, wherein the encapsulant comprises a cured product of the encapsulating resin composition according to claim 1 .