JP2024019300A - Encapsulating composition, production method therefor, and semiconductor device - Google Patents

Abstract

To provide an encapsulating composition that offers superior curability, fluidity and moldability, a cured product of which exhibits superior thermal conductivity.SOLUTION: An encapsulating composition comprises an epoxy resin, a hardener, and an inorganic filler having a void content of 18 vol.% or lower.SELECTED DRAWING: None

Description

The present invention relates to a sealing composition, a method for manufacturing the same, and a semiconductor device.

In recent years, with miniaturization and higher integration, there has been concern about heat generation inside semiconductor packages. Because heat generation may cause deterioration in the performance of electrical or electronic components including semiconductor packages, members used in semiconductor packages are required to have high thermal conductivity. Therefore, it is required that the sealing material for semiconductor packages has high thermal conductivity.
Furthermore, when sealing a semiconductor package, the sealing material is required to have high fluidity.
For example, when alumina is used as an inorganic filler, it is possible to increase the thermal conductivity of the encapsulant, but the fluidity of the encapsulant may decrease. There is a trade-off relationship. Therefore, it may be difficult to achieve both high thermal conductivity and improved fluidity.

An example of a sealing material using alumina as an inorganic filler is a semiconductor sealant whose essential components include (A) an epoxy resin, (B) a curing agent, and (D) an inorganic filler containing spherical alumina and spherical silica. an epoxy resin composition for use in which the spherical alumina is (d1) a first spherical alumina having an average particle diameter of 40 μm or more and 70 μm or less; and (d2) a second spherical alumina having an average particle diameter of 10 μm or more and 15 μm or less. The spherical silica includes (d3) a first spherical silica having an average particle diameter of 4 μm or more and 8 μm or less, and (d4) a second spherical silica having an average particle diameter of 0.05 μm or more and 1.0 μm or less. The total amount of (d3)+(d4) is 17% or more and 23% or less of the total inorganic filler, and the ratio of (d3)/(d4) is (d3)/(d4)=1. An epoxy resin composition for semiconductor encapsulation is known, which is characterized in that the ratio is 1/8 or more and 5/4 or less, and the amount of inorganic filler is 85% by mass to 95% by mass based on the total resin composition (for example, (See Patent Document 1).

JP2006-273920A

However, by employing alumina, which is a highly thermally conductive filler, the curability and moldability of the sealing material may deteriorate. Therefore, it is a challenge to develop a highly thermally conductive encapsulant that ensures fluidity, moldability, and curability.

The present disclosure has been made in view of the above-mentioned conventional circumstances, and provides a sealing composition that has excellent curability, fluidity, and moldability, and has excellent thermal conductivity when made into a cured product, a method for producing the same, and a sealing composition. An object of the present invention is to provide a semiconductor device using the composition.

Specific means for achieving the above object are as follows.
<1> A sealing composition containing an epoxy resin, a curing agent, and an inorganic filler having a porosity of 18% by volume or less.
<2> The sealing composition according to <1>, wherein the inorganic filler has a volume average particle diameter of 4 μm to 100 μm.
<3> The sealing composition according to <1> or <2>, wherein the inorganic filler contains at least one of alumina and silica.
<4> The sealing composition according to any one of <1> to <3>, wherein the inorganic filler has a specific surface area of 0.7 m ² /g to 4.0 m ² /g.
<5> A semiconductor device comprising a semiconductor element and a cured product of the sealing composition according to any one of <1> to <4>, which is obtained by sealing the semiconductor element.
<6> Determining the composition of the inorganic filler so that the porosity becomes a predetermined value;
A method for producing a sealing composition, comprising the step of mixing an inorganic filler having a composition determined in the step, an epoxy resin, and a curing agent.

According to the present disclosure, there is provided an encapsulating composition that has excellent curability, fluidity, and moldability, and excellent thermal conductivity when made into a cured product, a method for producing the same, and a semiconductor device using the encapsulating composition. I can do it.

EMBODIMENT OF THE INVENTION Hereinafter, the sealing composition of this invention, its manufacturing method, and the form for implementing a semiconductor device are demonstrated in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including elemental steps and the like) are not essential unless otherwise specified. The same applies to numerical values and their ranges, and they do not limit the present invention.
In the present disclosure, numerical ranges indicated using "~" include the numerical values written before and after "~" as minimum and maximum values, respectively.
In the numerical ranges described step by step in this disclosure, the upper limit or lower limit described in one numerical range may be replaced with the upper limit or lower limit of another numerical range described step by step. . Furthermore, in the numerical ranges described in this disclosure, the upper limit or lower limit of the numerical range may be replaced with the values shown in the Examples.
In the present disclosure, each component may contain multiple types of corresponding substances. If there are multiple types of substances corresponding to each component in the composition, the content rate or content of each component is the total content rate or content of the multiple types of substances present in the composition, unless otherwise specified. means quantity.
In the present disclosure, each component may include a plurality of types of particles. When a plurality of types of particles corresponding to each component are present in the composition, the particle diameter of each component means a value for a mixture of the plurality of types of particles present in the composition, unless otherwise specified.

<Sealing composition>
The sealing composition of the present disclosure contains an epoxy resin, a curing agent, and an inorganic filler having a porosity of 18% by volume or less.
The porosity of the inorganic filler is a value representing the proportion of voids in the bulk volume of the inorganic filler ((volume of voids/bulk volume of inorganic filler)×100(%)). When using inorganic fillers made of the same material, if the weight of the inorganic fillers is the same, the bulk volume of the inorganic fillers decreases as the porosity decreases. When the bulk volume of the inorganic filler contained in the sealing composition decreases, even if the content of the inorganic filler contained in the sealing composition is the same, the bulk volume of the inorganic filler decreases from the volume of the sealing composition. The value obtained by subtracting becomes larger. Hereinafter, this value may be referred to as "amount of surplus resin."
The present inventors focused on the amount of surplus resin in the sealing composition, and investigated the effects of the amount of surplus resin on the curability, fluidity, and moldability of the sealing composition, as well as on the thermal conductivity when made into a cured product. Upon investigation, we found that as the amount of surplus resin increases (in other words, the porosity of the inorganic filler decreases), the curability, fluidity, moldability, and thermal conductivity of the sealing composition when made into a cured product decrease. The present invention was completed after discovering that this can be improved.
It is not clear why the curability, fluidity, moldability, and thermal conductivity of the sealing composition improve as the amount of surplus resin increases, but as the amount of surplus resin increases, It is believed that the viscosity of the sealing composition is reduced and the fluidity is improved. In addition, it is assumed that an increase in the amount of surplus resin improves the dispersibility of the sealing composition during kneading, contributing to improvements in curability, moldability, and thermal conductivity when made into a cured product. be done.

Each component constituting the sealing composition will be explained below. The sealing composition of the present disclosure contains an epoxy resin, a curing agent, and an inorganic filler, and may contain other components as necessary.

-Epoxy resin-
The sealing composition contains an epoxy resin. The type of epoxy resin is not particularly limited, and any known epoxy resin can be used.
Specifically, for example, selected from the group consisting of phenolic compounds (e.g., phenol, cresol, xylenol, resorcinol, catechol, bisphenol A and bisphenol F) and naphthol compounds (e.g., α-naphthol, β-naphthol and dihydroxynaphthalene). and an aldehyde compound (e.g., formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde) under an acidic catalyst. at least one selected from the group consisting of biphenols (e.g., bisphenol A, bisphenol AD, bisphenol F, and bisphenol S); and biphenols (e.g., alkyl-substituted or unsubstituted biphenols); One type of diglycidyl ether; Epoxidized product of phenol/aralkyl resin; Epoxidized product of adduct or polyadduct of a phenol compound and at least one selected from the group consisting of dicyclopentadiene and terpene compounds; Polybasic acid ( Glycidyl ester-type epoxy resins obtained by the reaction of epichlorohydrin with epichlorohydrin (e.g., phthalic acid and dimer acid); glycidylamine-type epoxy resins obtained by the reaction of polyamines (e.g., diaminodiphenylmethane and isocyanuric acid) with epichlorohydrin; Examples include linear aliphatic epoxy resins obtained by oxidation with (for example, peracetic acid); and alicyclic epoxy resins. Epoxy resins may be used singly or in combination of two or more.

From the viewpoint of preventing corrosion of aluminum wiring or copper wiring on elements such as integrated circuits (ICs), the purity of the epoxy resin is preferably high, and the amount of hydrolyzable chlorine is preferably low. From the viewpoint of improving the moisture resistance of the sealing composition, the amount of hydrolyzable chlorine is preferably 500 ppm or less on a mass basis.

Here, the amount of hydrolyzable chlorine is a value determined by potentiometric titration after dissolving 1 g of the sample epoxy resin in 30 mL of dioxane, adding 5 mL of 1N-KOH methanol solution, and refluxing for 30 minutes.

The content of the epoxy resin in the sealing composition is preferably 2.5% by mass to 6% by mass, more preferably 3.5% by mass to 5.5% by mass, and 3.5% by mass. % to 5.0% by mass is more preferable.
The content of the epoxy resin in the sealing composition excluding the inorganic filler is preferably 40% by mass to 70% by mass, more preferably 45% to 64% by mass, and 48% to 55% by mass. More preferably, it is expressed in mass %.

-Hardening agent-
The sealing composition contains a curing agent. The type of curing agent is not particularly limited, and any known curing agent can be used.
Specifically, for example, selected from the group consisting of phenolic compounds (e.g. phenol, cresol, resorcinol, catechol, bisphenol A and bisphenol F) and naphthol compounds (e.g. α-naphthol, β-naphthol and dihydroxynaphthalene) Novolac resin obtained by condensing or co-condensing at least one aldehyde compound (for example, formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde) under an acidic catalyst; phenol/aralkyl resin; biphenyl/aralkyl resin; and naphthol aralkyl resins. One type of curing agent may be used alone, or two or more types may be used in combination.

The curing agent is blended so that the equivalent of the functional group (for example, phenolic hydroxyl group in the case of novolac resin) of the curing agent is 0.5 to 1.5 equivalents per equivalent of epoxy group in the epoxy resin. In particular, it is preferable that the curing agent be blended in an amount of 0.7 to 1.2 equivalents.

-Inorganic filler-
The encapsulating composition includes an inorganic filler. Including an inorganic filler tends to reduce the hygroscopicity of the sealing composition and improve its strength in a cured state.

One type of inorganic filler may be used alone or two or more types may be used in combination.
Examples of cases where two or more types of inorganic fillers are used in combination include cases where two or more types of inorganic fillers having different components, average particle diameters, shapes, etc. are used.
The shape of the inorganic filler is not particularly limited, and examples include powder, spherical, and fibrous shapes. From the viewpoint of fluidity and mold abrasion resistance during molding of the sealing composition, a spherical shape is preferable.

In the present disclosure, the porosity of the inorganic filler is 18 vol% or less, preferably 16 vol% or less, more preferably 15 vol% or less, and even more preferably 14 vol% or less. The porosity of the inorganic filler may be 7% by volume or more. When there is one type of inorganic filler, the porosity of the inorganic filler means the porosity of one type of inorganic filler, and when there are two or more types of inorganic fillers, the porosity of the inorganic filler means the porosity of a mixture of two or more types of inorganic fillers.

The porosity of the inorganic filler refers to a value measured by the following method.
The sealing composition is placed in a crucible and left at 800° C. for 4 hours to incinerate. The particle size distribution of the obtained ash is measured using a laser diffraction/scattering particle size distribution measuring device (for example, Horiba, Ltd., LA920) by applying the refractive index of alumina. The porosity ε is calculated from the particle size distribution using Ouchiyama's formula below. Regarding Ouchiyama's formula, please refer to the following document for details.
N. Ouchiyama and T. Tanaka, Ind. Eng. Chem. Fundament. , 19, 338 (1980)
N. Ouchiyama and T. Tanaka, Ind. Eng. Chem. Fundament. , 20, 66 (1981)
N. Ouchiyama and T. Tanaka, Ind. Eng. Chem. Fundament. , 23, 490 (1984)

The inorganic filler preferably contains at least one of alumina and silica, and more preferably contains alumina from the viewpoint of high thermal conductivity. All of the inorganic fillers may be alumina, or alumina and other inorganic fillers may be used in combination. When the inorganic filler contains alumina, the thermal conductivity of the sealing composition tends to improve. Examples of silica include spherical silica and crystalline silica.
Other inorganic fillers other than silica that can be used in combination with alumina include zircon, magnesium oxide, calcium silicate, calcium carbonate, potassium titanate, silicon carbide, silicon nitride, boron nitride, aluminum nitride, beryllia, zirconia, etc. . Further, examples of inorganic fillers having a flame retardant effect include aluminum hydroxide, zinc borate, and the like.

When alumina and silica are used together as an inorganic filler, the content of alumina in the inorganic filler is preferably 50 volume% or more, more preferably 70 volume% or more, and 85 volume% or more. It is more preferable that Further, the content of alumina in the inorganic filler may be 99% by volume or less.

The content of the inorganic filler is preferably 60% by volume or more, and 70% by volume based on the entire sealing composition, from the viewpoints of hygroscopicity, reduction of linear expansion coefficient, improvement of strength, and soldering heat resistance. The content is more preferably 75% by volume or more, and even more preferably 75% by volume or more. The content of the inorganic filler may be 95% by volume or less.

From the viewpoint of high thermal conductivity, the average particle diameter of the inorganic filler is preferably 4 μm to 100 μm, more preferably 7 μm to 70 μm, and even more preferably 7 μm to 40 μm. In the present disclosure, the average particle size of the inorganic filler is the average particle size of alumina when alumina is used alone as the inorganic filler, and the average particle size of alumina when alumina and another inorganic filler are used together as the inorganic filler. When the particle diameter is 1, it refers to the average particle diameter of the inorganic filler as a whole.
The thermal conductivity of the cured product of the sealing composition tends to increase as the average particle size of the inorganic filler increases.
The average particle diameter of the inorganic filler can be measured by the following method.

Add the inorganic filler to be measured to a solvent (pure water) in a range of 1% to 5% by mass together with 1% to 8% by mass of a surfactant, and wash in a 110W ultrasonic cleaner for 30 seconds to 5%. Vibrate for a minute to disperse the inorganic filler. About 3 mL of the dispersion liquid is injected into a measurement cell and measured at 25°C. The measuring device measures the volume-based particle size distribution using a laser diffraction/scattering particle size distribution measuring device (for example, Horiba, Ltd., LA920). The average particle diameter is determined as the particle diameter (D50%) when the accumulation from the small diameter side is 50% in the volume-based particle size distribution. Note that the refractive index of alumina is used as the refractive index. When the inorganic filler is a mixture of alumina and other inorganic fillers, the refractive index of alumina is used as the refractive index.

The specific surface area of the inorganic filler is preferably 0.7 m ² /g to 4.0 m 2 ^/ g, and 0.9 ^{m 2} /g to 3.0 m ² /g from the viewpoint of fluidity and moldability. More preferably, it is 1.0 m ² /g to 2.5 ^{m 2} /g.
The fluidity of the sealing composition tends to increase as the specific surface area of the inorganic filler decreases.
In the present disclosure, the specific surface area of the inorganic filler is defined as the specific surface area of alumina when, for example, alumina is used alone as the inorganic filler, and the specific surface area of alumina when alumina and other inorganic fillers are used together as the inorganic filler. If present, it refers to the specific surface area of the mixture of inorganic fillers.
The specific surface area (BET specific surface area) of the inorganic filler can be measured from the nitrogen adsorption capacity according to JIS Z 8830:2013. As the evaluation device, AUTOSORB-1 (trade name) manufactured by QUANTACHROME can be used. When measuring the BET specific surface area, it is thought that moisture adsorbed on the sample surface and structure affects the gas adsorption ability, so it is preferable to first perform pretreatment to remove moisture by heating. .
In the pretreatment, the measurement cell containing 0.05 g of the measurement sample was depressurized to 10 Pa or less using a vacuum pump, heated to 110°C, held for more than 3 hours, and then heated to room temperature (while maintaining the depressurized state). Cool naturally to 25°C. After performing this pretreatment, the evaluation temperature is set to 77 K, and the evaluation pressure range is measured as relative pressure (equilibrium pressure with respect to saturated vapor pressure) less than 1.

(hardening accelerator)
The sealing composition may further contain a curing accelerator. The type of curing accelerator is not particularly limited, and any known curing accelerator can be used.
Specifically, 1,8-diaza-bicyclo[5.4.0]undecene-7, 1,5-diaza-bicyclo[4.3.0]nonene, 5,6-dibutylamino-1,8- Cyclamidine compounds such as diaza-bicyclo[5.4.0]undecene-7; maleic anhydride, 1,4-benzoquinone, 2,5-torquinone, 1,4-naphthoquinone, 2,3-dimethyl in the cycloamidine compound Quinone compounds such as benzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, phenyl-1,4-benzoquinone, diazo Compounds with intramolecular polarization obtained by adding compounds with π bonds such as phenylmethane and phenolic resins; tertiary amine compounds such as benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; Derivatives of tertiary amine compounds; derivatives of imidazole compounds and imidazole compounds such as 2-methylimidazole, 2-phenylimidazole, and 2-phenyl-4-methylimidazole; tributylphosphine, methyldiphenylphosphine, triphenylphosphine, tris(4- Organic phosphine compounds such as (methylphenyl)phosphine, diphenylphosphine, and phenylphosphine; intramolecular polarization obtained by adding compounds with π bonds such as maleic anhydride, the above quinone compounds, diazophenylmethane, and phenol resins to organic phosphine compounds; Phosphorus compounds containing; tetraphenylboron salts and derivatives of tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate, triphenylphosphine tetraphenylborate, 2-ethyl-4-methylimidazole tetraphenylborate, N-methylmorpholine tetraphenylborate, etc. ; Examples include adducts of phosphine compounds such as triphenylphosphonium-triphenylborane, N-methylmorpholinetetraphenylphosphonium-tetraphenylborate, and tetraphenylboron salts. One type of curing accelerator may be used alone, or two or more types may be used in combination.

The content of the curing accelerator is preferably 0.1% by mass to 8% by mass based on the total amount of the epoxy resin and curing agent.

(ion trap agent)
The encapsulation composition may further contain an ion trapping agent.
The ion trapping agent that can be used in the present disclosure is not particularly limited as long as it is a commonly used ion trapping agent in sealing materials used for manufacturing semiconductor devices. Examples of the ion trapping agent include compounds represented by the following general formula (II-1) or the following general formula (II-2).

Mg _1-a Al _a (OH) ₂ (CO ₃ ) _a/2・uH ₂ O (II-1)
(In general formula (II-1), a is 0<a≦0.5, and u is a positive number.)
BiO _b (OH) _c (NO ₃ ) _d (II-2)
(In general formula (II-2), b is 0.9≦b≦1.1, c is 0.6≦c≦0.8, and d is 0.2≦d≦0.4.)

Ion trapping agents are commercially available. As the compound represented by the general formula (II-1), for example, "DHT-4A" (Kyowa Chemical Industry Co., Ltd., trade name) is available as a commercial product. Further, as a compound represented by the general formula (II-2), for example, "IXE500" (trade name, manufactured by Toagosei Co., Ltd.) is available as a commercial product.

In addition, examples of ion trapping agents other than those mentioned above include hydrous oxides of elements selected from magnesium, aluminum, titanium, zirconium, antimony, and the like.
One type of ion trap agent may be used alone, or two or more types may be used in combination.

When the sealing composition contains an ion trapping agent, the content of the ion trapping agent is preferably 1 part by mass or more per 100 parts by mass of the epoxy resin from the viewpoint of achieving sufficient moisture resistance reliability. . From the viewpoint of fully exhibiting the effects of other components, the content of the ion trapping agent is preferably 15 parts by mass or less based on 100 parts by mass of the epoxy resin.

Further, the average particle size of the ion trapping agent is preferably 0.1 μm to 3.0 μm, and the maximum particle size is preferably 10 μm or less. The average particle diameter of the ion trapping agent can be measured in the same manner as in the case of the inorganic filler.

(coupling agent)
The sealing composition may further contain a coupling agent. The type of coupling agent is not particularly limited, and any known coupling agent can be used. Examples of the coupling agent include a silane coupling agent and a titanium coupling agent. One type of coupling agent may be used alone, or two or more types may be used in combination.

Examples of the silane coupling agent include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. , γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-[bis(β-hydroxyethyl)]aminopropyltriethoxysilane, N -β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-(β-aminoethyl)aminopropyldimethoxymethylsilane, N-(trimethoxysilylpropyl)ethylenediamine, N-(dimethoxymethylsilylisopropyl)ethylenediamine, Methyltrimethoxysilane, methyltriethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilane, γ-anilinopropyltrimethoxy Examples include silane, vinyltrimethoxysilane and γ-mercaptopropylmethyldimethoxysilane.

Examples of the titanium coupling agent include isopropyl triisostearoyl titanate, isopropyl tris(dioctylpyrophosphate) titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, and tetra( 2,2-diallyloxymethyl-1-butyl)bis(ditridecylphosphite) titanate, bis(dioctylpyrophosphate)oxyacetate titanate, bis(dioctylpyrophosphate)ethylene titanate, isopropyltrioctanoyltitanate, isopropyldimethacryliso Stearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumylphenyl titanate and tetraisopropyl bis(dioctyl phosphite) titanate.

When the sealing composition contains a coupling agent, the content of the coupling agent is preferably 3% by mass or less based on the entire sealing composition, and from the viewpoint of exhibiting its effect, the content of the coupling agent is 0. .1% by mass or more is preferable.

(Release agent)
The sealing composition may further contain a mold release agent. The type of mold release agent is not particularly limited, and any known mold release agent can be used. Specific examples include higher fatty acids, carnauba wax, and polyethylene wax. One type of mold release agent may be used alone, or two or more types may be used in combination.
When the sealing composition contains a mold release agent, the content of the mold release agent is preferably 10% by mass or less based on the total amount of the epoxy resin and the curing agent, from the viewpoint of exhibiting its effect. is preferably 0.5% by mass or more.

(Colorants and modifiers)
The encapsulant composition may also contain a colorant (eg, carbon black). The encapsulating composition may also contain modifiers (eg, silicones and silicone rubbers). The colorant and the modifier may be used alone or in combination of two or more.

When using conductive particles such as carbon black as a coloring agent, it is preferable that the content of conductive particles having a particle diameter of 10 μm or more is 1% by mass or less.
When the sealing composition contains conductive particles, the content of the conductive particles is preferably 3% by mass or less based on the total amount of the epoxy resin and the curing agent.

<Method for manufacturing sealing composition>
A method for producing a sealing composition of the present disclosure includes a step of determining the composition of an inorganic filler so that the porosity has a predetermined value, an inorganic filler having the composition determined by the step, and an epoxy resin. and a curing agent. The predetermined porosity is preferably 18% by volume or less, more preferably 16% by volume or less, even more preferably 15% by volume or less, particularly 14% by volume or less. preferable.
The method of determining the composition of the inorganic filler so that the porosity becomes a predetermined value is not particularly limited. When the shape of the inorganic filler is spherical, the porosity of the inorganic filler can be calculated based on the particle size distribution of the inorganic filler. Therefore, the particle size distribution of multiple inorganic fillers is measured and accumulated in advance, and the porosity of the inorganic filler is determined according to the characteristics of the sealing composition. The composition of the inorganic filler may be determined by combining these inorganic fillers.
Examples of a method for calculating the porosity of an inorganic filler based on the particle size distribution of the inorganic filler include a method of calculating using the Ouchiyama equation described above.
Next, the inorganic filler whose composition has been determined to have a predetermined porosity, the epoxy resin, the curing agent, and other components used as necessary are thoroughly mixed using a mixer or the like, and then heated. A sealing composition can be produced by kneading with a roll, extruder, etc., and then undergoing treatments such as cooling and pulverization. The state of the sealing composition is not particularly limited, and may be powder, solid, liquid, or the like.

<Semiconductor device>
The semiconductor device of the present disclosure includes a semiconductor element and a cured product of the sealing composition of the present disclosure, which seals the semiconductor element.

The method of sealing a semiconductor element using a sealing composition is not particularly limited, and any known method can be applied. For example, although a transfer molding method is common, a compression molding method, an injection molding method, etc. may also be used.

The semiconductor device of the present disclosure is suitable as an IC, an LSI (Large-Scale Integration), or the like.

Examples of the present invention will be described below, but the present invention is not limited thereto. Moreover, the numerical values in the table mean "parts by mass" unless otherwise specified.

(Examples 1 to 6 and Comparative Examples 1 to 3)
The components shown below were premixed (dry blended) at the blending ratios (parts by mass) shown in Table 1 or Table 2, then kneaded with a twin-screw kneader, cooled and ground to produce a powdery sealing composition.

(A) Epoxy resin・A1...Bisphenol type crystalline epoxy resin, epoxy equivalent: 192g/eq
・A2...Biphenyl type epoxy resin, epoxy equivalent: 192g/eq
・A3...Bisphenol F type epoxy resin, epoxy equivalent: 158g/eq
(B) Curing agent・B1...Triphenylmethane type phenol resin, triphenylmethane type phenol resin with a hydroxyl equivalent of 104 g/eq (C) Curing accelerator・C1...Phosphorous curing accelerator (tributylphosphine and benzoquinone adduct)
(D) Filler (inorganic filler)
・D1... Alumina filler with an average particle diameter (D50, particle diameter corresponding to 50% volume accumulation from the small diameter side) of 10.4 μm and a specific surface area of 1.5 m ² /g.・D2... Average particle diameter 1. Alumina filler with an average particle diameter of 43.9 μm and a specific surface area of 0.15 m ² /g. D4: an average particle diameter of 0.7 μm and a specific surface area of 0.15 m ² /g. 8.0 m ² /g alumina filler D5...Silica filler with a specific surface area of 200 m ² /g D6...Alumina filler/silica filler with an average particle diameter of 11.7 μm and a specific surface area of 2.2 m ² /g = 9/1 (mass ratio) mixture

<Porosity, specific surface area and average particle diameter>
The porosity, specific surface area, and average particle diameter of the inorganic filler were measured by the methods described above. The results obtained are shown in Table 3 or Table 4.

<Curability>
Curability was evaluated based on gel time measured as follows using a gelling tester.
Place 0.5 g of the sealing composition obtained above on a hot plate heated to 175°C, and use a jig to rotate the sample 2.0 cm to 2 cm at a rotation speed of 20 rpm to 25 rpm. It was spread evenly into a .5 cm circle. The time from when the sample was placed on the hot plate until the sample lost its viscosity, turned into a gel state, and peeled off from the hot plate was measured, and this time was measured as gel time (sec).
The results are shown in Table 3 or Table 4. When the same amount of catalyst (amount of curing accelerator) is used for 100 parts by mass of epoxy, the shorter the gel time, the better the curability.

<Liquidity>
The sealing composition obtained above was passed through a two-stage sieve (upper stage: 2.38 mm, lower stage: 0.5 mm), and 7 g of the sample remaining in the lower stage was weighed. The sealing composition was placed on a smooth mold heated to 180°C, and an 8 kg smooth mold also heated to 180°C was placed on top of the sample and left for 60 seconds. Thereafter, the average value (mm) of the major axis (mm) and minor axis (mm) of the obtained disc-shaped molded product was determined, and the average value (mm) was defined as the disc flow (DF).
The results are shown in Table 3 or Table 4. The longer the disc flow, the better the fluidity.

<Moldability>
15 g of the sealing composition obtained above was placed on a mold at 180° C. on a press hot plate and molded for a curing time of 90 seconds. After molding, use calipers to measure the length of the longest part of the 50 μm, 30 μm, 20 μm, 10 μm, 5 μm, and 2 μm slits in which the sealing composition has flowed, and use this measurement value. It has a burr length.
The results are shown in Table 3 or Table 4. The shorter the burr, the better the moldability.

<Thermal conductivity>
Using the sealing composition obtained above, a test piece for thermal conductivity evaluation was prepared using a vacuum hand press molding machine under conditions of a mold temperature of 175°C to 180°C, a molding pressure of 7 MPa, and a curing time of 600 seconds. did. Next, the thermal diffusivity in the thickness direction of the molded test piece was measured. The thermal diffusivity was measured by a laser flash method (device: LFA467 nanoflash, manufactured by NETZSCH). Pulsed light irradiation was performed under conditions of a pulse width of 0.31 (ms) and an applied voltage of 247V. The measurements were carried out at an ambient temperature of 25°C±1°C. Further, the density of the above test piece was measured using an electronic hydrometer (AUX220, Shimadzu Corporation). For the specific heat, the theoretical specific heat of the sealing composition calculated from the literature values of the specific heat of each material and the blending ratio was used.
Thermal conductivity values were then obtained by multiplying the thermal diffusivity by the specific heat and density using equation (1).
λ=α×Cp×ρ...Formula (1)
(In formula (1), λ is thermal conductivity (W/(m・K)), α is thermal diffusivity (m ² /s), Cp is specific heat (J/(kg・K)), and ρ is density (kg/m ³ ) is shown respectively.)
The results are shown in Table 3 or Table 4.

As is clear from the evaluation results in Tables 3 and 4, the sealing compositions of Examples 1 to 6 in which the porosity of the inorganic filler was 18 vol.% or less, Compared to the sealing compositions of Comparative Examples 1 to 3, which have excellent curability, fluidity, and formability. Further, the thermal conductivity of the cured products of the sealing compositions of Examples 1 to 6 is equal to or higher than that of the cured products of the sealing compositions of Comparative Examples 1 to 3.

The disclosure of Japanese Patent Application No. 2017-254885 filed on December 28, 2017 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference. Incorporated herein by reference.

Claims (6)

A sealing composition containing an epoxy resin, a curing agent, and an inorganic filler having a porosity of 18% by volume or less. The sealing composition according to claim 1, wherein the inorganic filler has a volume average particle diameter of 4 μm to 100 μm. The sealing composition according to claim 1 or 2, wherein the inorganic filler contains at least one of alumina and silica. The sealing composition according to any one of claims 1 to 3, wherein the inorganic filler has a specific surface area of 0.7 m ² /g to 4.0 m ² /g. A semiconductor device comprising a semiconductor element and a cured product of the sealing composition according to any one of claims 1 to 4, which is obtained by sealing the semiconductor element. a step of determining the composition of the inorganic filler so that the porosity becomes a predetermined value;
A method for producing a sealing composition, comprising the step of mixing an inorganic filler having a composition determined in the step, an epoxy resin, and a curing agent.