TW202436581A - Sealing composition, manufacturing method of sealing composition, and semiconductor device - Google Patents

Abstract

A sealing composition contains an epoxy resin, a curing agent, and an inorganic filler having a void fraction of 18 volume% or less.

Description

Sealing composition, manufacturing method thereof, and semiconductor device

The present invention relates to a sealing composition, a manufacturing method thereof and a semiconductor device.

In recent years, along with miniaturization and high integration, there are concerns about heat generation inside semiconductor packages. There is a risk that the performance of electrical or electronic components having semiconductor packages may be reduced due to heat generation, so high thermal conductivity is required for components used in semiconductor packages. Therefore, it is required that the sealing material of the semiconductor package has high thermal conductivity. In addition, when sealing the semiconductor package, high fluidity is required for the sealing material. When using, for example, alumina as an inorganic filler, there is a situation where the high thermal conductivity of the sealing material can be achieved but the fluidity of the sealing material is reduced, and the high thermal conductivity of the sealing material and the improvement of fluidity are in a trade-off relationship. Therefore, there is a situation where it is difficult to take into account both high thermal conductivity and improved fluidity.

As an example of a sealing material using alumina as an inorganic filler, there is known an epoxy resin composition for semiconductor sealing, which comprises (A) an epoxy resin, (B) a hardener, and (D) an inorganic filler containing spherical alumina and spherical silica as essential components, wherein the spherical alumina comprises (d1) a first spherical alumina having an average particle size of 40 μm or more and 70 μm or less, and (d2) a second spherical alumina having an average particle size of 10 μm or more and 15 μm or less, and the spherical silica comprises (d3) a first spherical silica having an average particle size of 4 μm or more and 8 μm or less, and (d4) a second spherical silica having an average particle size of 0.05 μm or more and 1.0 μm or less. The second spherical silica with a size of less than μm, the total amount of (d3) + (d4) is 17% or more and 23% or less relative to the total inorganic filler, the ratio of (d3) / (d4) is (d3) / (d4) = 1/8 or more and 5/4 or less, and the amount of the inorganic filler in the total resin composition is 85% to 95% by mass (for example, refer to Patent Document 1). [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 2006-273920

[Problem to be solved by the invention] However, by using alumina as a high thermal conductive filler, the hardening and formability of the sealing material may deteriorate. Therefore, it is difficult to develop a high thermal conductive sealing material that ensures fluidity, formability and hardening properties.

This disclosure is made in view of the above-mentioned previous situation, and its purpose is to provide a sealing composition having excellent curability, fluidity and formability and excellent thermal conductivity when the cured product is made, and a method for manufacturing the sealing composition, as well as a semiconductor device using the sealing composition. [Means for solving the problem]

Specific means for achieving the above-mentioned subject are as follows. <1> A sealing composition comprising an epoxy resin, a hardener, and an inorganic filler having a porosity of 18 volume % or less. <2> The sealing composition as described in <1>, wherein the volume average particle size of the inorganic filler is 4 μm to 100 μm. <3> The sealing composition as described in <1> or <2>, wherein the inorganic filler comprises at least one of aluminum oxide and silicon dioxide. <4> The sealing composition as described in any one of <1> to <3>, wherein the specific surface area of the inorganic filler is 0.7 m ² /g to 4.0 m ² /g. <5> A semiconductor device comprising a semiconductor element and a hardened product of the sealing composition as described in any one of <1> to <4>, which is formed by sealing the semiconductor element. <6> A method for producing a sealing composition, comprising: a step of determining the composition of an inorganic filler so that the porosity becomes a predetermined value; and a step of mixing the inorganic filler of the composition determined by the step, an epoxy resin, and a hardener. [Effect of the Invention]

According to the present disclosure, a sealing composition having excellent curability, fluidity and formability and excellent thermal conductivity when cured, a method for manufacturing the sealing composition, and a semiconductor device using the sealing composition can be provided.

The following is a detailed description of the sealing composition and its manufacturing method and the form of the semiconductor device used to implement the present invention. However, the present invention is not limited to the following implementation forms. In the following implementation forms, its constituent elements (including element steps, etc.) are not required unless specifically stated. The same is true for numerical values and their ranges, which do not limit the present invention. In the present disclosure, the numerical values recorded before and after the "~" in the numerical range represented by "~" are respectively the minimum value and the maximum value. In the numerical range recorded in stages in the present disclosure, the upper limit or lower limit recorded in one numerical range can also be replaced by the upper limit or lower limit of other numerical ranges recorded in stages. In addition, in the numerical range described in this disclosure, the upper limit or lower limit of the numerical range may also be replaced with the value shown in the embodiment. In this disclosure, each component may also contain a plurality of corresponding substances. When there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, the content rate or content of each component refers to the total content rate or content of the plurality of substances present in the composition. In this disclosure, a plurality of particles corresponding to each component may also be included. When there are a plurality of particles corresponding to each component in the composition, unless otherwise specified, the particle size of each component refers to the value of the mixture of the plurality of particles present in the composition.

<Sealing composition> The sealing composition disclosed herein contains an epoxy resin, a hardener, and an inorganic filler having a porosity of 18 volume % or less. The porosity of the inorganic filler is a value indicating the ratio of voids to the total bulk volume of the inorganic filler ((volumetry of voids/total volume of inorganic filler) × 100 (%)). When using inorganic fillers made of the same raw materials, if the weight of the inorganic filler is the same, the total volume of the inorganic filler decreases as the porosity decreases. If the total 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 value obtained by subtracting the total volume of the inorganic filler from the volume of the sealing composition becomes larger. Hereinafter, this value is sometimes referred to as the "amount of residual resin". The inventors of the present invention focused on the amount of residual resin in the sealing composition and studied the effect of the amount of residual resin on the curability, fluidity and formability of the sealing composition and the thermal conductivity when the cured product is made. As a result, it was found that as the amount of residual resin increases (that is, the porosity of the inorganic filler decreases), the curability, fluidity, formability and thermal conductivity of the sealing composition when the cured product is made are improved, thereby completing the present invention. Although the reason why the curability, fluidity, formability, and thermal conductivity of the sealing composition when the amount of residual resin increases are not clear, it is believed that the viscosity of the sealing composition decreases and the fluidity improves as the amount of residual resin increases. In addition, it is speculated that the dispersion of the sealing composition during kneading becomes better as the amount of residual resin increases, which helps to improve the curability, formability, and thermal conductivity of the cured product.

The components constituting the sealing composition are described below. The sealing composition disclosed herein contains an epoxy resin, a hardener, and an inorganic filler, and may contain other components as required.

-Epoxy resin- The sealing composition contains epoxy resin. The type of epoxy resin is not particularly limited, and a known epoxy resin can be used. Specifically, for example, there can be mentioned: a novolac resin obtained by epoxidizing at least one 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 salicylic aldehyde) under an acidic catalyst (e.g., phenol novolac type epoxy resin and o-cresol novolac type epoxy resin); a novolac resin selected from bisphenols (e.g., bisphenol A, bisphenol AD, bisphenol F and bisphenol S) and diphenols (e.g., alkyl-substituted or non-alkyl-substituted bisphenols); At least one diglycidyl ether selected from the group consisting of substituted biphenols (e.g., substituted biphenols); epoxides of phenol-aralkyl resins; epoxides of adducts or polyadducts of phenol compounds and at least one selected from the group consisting of dicyclopentadiene and terpene compounds; glycidyl ester type epoxy resins obtained by the reaction of polyacids (e.g., phthalic acid and dimer acid) with epichlorohydrin; glycidylamine type epoxy resins obtained by the reaction of polyamines (e.g., diaminodiphenylmethane and isocyanuric acid) with epichlorohydrin; linear aliphatic epoxy resins obtained by oxidizing olefinic bonds with peroxyacids (e.g., peracetic acid); and aliphatic epoxide resins. Epoxy resins can be used alone or in combination of two or more.

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

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

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

-Hardener- The sealing composition contains a hardener. The type of hardener is not particularly limited, and a known hardener can be used. Specifically, for example: a novolac resin obtained by condensing or co-condensing at least one 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) with an aldehyde compound (e.g., formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylic aldehyde) under an acidic catalyst; a phenol·aralkyl resin; a biphenyl·aralkyl resin; and a naphthol·aralkyl resin. The hardener may be used alone or in combination of two or more.

The curing agent is preferably formulated so that the equivalent of the functional group of the curing agent (for example, phenolic hydroxyl group in the case of novolac resin) becomes 0.5 to 1.5 equivalents per 1 equivalent of epoxy group of the epoxy resin, and the curing agent is particularly preferably formulated so that the equivalent becomes 0.7 to 1.2 equivalents.

-Inorganic filler- The sealing composition contains an inorganic filler. By including the inorganic filler, the hygroscopicity of the sealing composition tends to decrease, and the strength in the cured state tends to increase.

The inorganic filler may be used alone or in combination of two or more. As an example of using two or more inorganic fillers in combination, for example, two or more inorganic fillers having different components, average particle sizes, shapes, etc. may be used. The shape of the inorganic filler is not particularly limited, and for example, powder, spherical, fibrous, etc. may be used. In terms of fluidity and mold wear resistance during molding of the sealing composition, a spherical shape is preferred.

In the present disclosure, the porosity of the inorganic filler is 18 volume % or less, preferably 16 volume % or less, more preferably 15 volume % or less, and further preferably 14 volume % or less. The porosity of the inorganic filler may also be 7 volume % or more. When the inorganic filler is one kind, the porosity of the inorganic filler refers to the porosity of the one kind of inorganic filler, and when the inorganic filler is two or more kinds, the porosity of the inorganic filler refers to the porosity of the mixture of the two or more kinds of inorganic fillers.

The void ratio of the inorganic filler is a value measured by the following method. The sealing composition is placed in a crucible and placed at 800°C for 4 hours to be ashed. The particle size distribution of the obtained ash is measured using a laser diffraction/scattering particle size distribution measuring device (e.g., LA920, manufactured by Horiba, Ltd.) and the refractive index of alumina. The void ratio ε is calculated from the particle size distribution using the following Ouchiyama equation. The Ouchiyama equation is described in detail in the following reference. N. Ouchiyama and T. Tanaka, Ind. Eng. Chem. Fundam., 19, 338 (1980) N. Ouchiyama and T. Tanaka, Ind. Eng. Chem. Fundam., 20, 66 (1981) N. Ouchiyama and T. Tanaka, Ind. Eng. Chem. Fundam., 23, 490 (1984)

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The inorganic filler preferably includes at least one of alumina and silica, and more preferably includes alumina from the viewpoint of high thermal conductivity. All of the inorganic filler may be alumina, or alumina and other inorganic fillers may be used in combination. When the inorganic filler includes alumina, the thermal conductivity of the sealing composition tends to be improved. As silica, spherical silica, crystalline silica, etc. can be listed. As other inorganic fillers other than silica that can be used in combination with alumina, zirconia, magnesium oxide, calcium silicate, calcium carbonate, potassium titanium oxide, silicon carbide, silicon nitride, boron nitride, aluminum nitride, ceria, zirconium oxide, etc. can be listed. Furthermore, as inorganic fillers with flame retardant effects, aluminum hydroxide, zinc borate, etc. can be listed.

When alumina and silicon dioxide are used together as inorganic fillers, the content of alumina in the inorganic filler is preferably 50 volume % or more, more preferably 70 volume % or more, and further preferably 85 volume % or more. In addition, the content of alumina in the inorganic filler may be 99 volume % or less.

From the viewpoint of hygroscopicity, reduction of linear expansion coefficient, improvement of strength and solder heat resistance, the content of the inorganic filler is preferably 60 volume % or more, more preferably 70 volume % or more, and further preferably 75 volume % or more relative to the entire sealing composition. The content of the inorganic filler may also be 95 volume % or less.

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

Add the inorganic filler to be measured to the solvent (pure water) in the range of 1% to 5% by mass, and add 1% to 8% by mass of a surfactant, and use a 110 W ultrasonic cleaner to shake for 30 seconds to 5 minutes to disperse the inorganic filler. Pour about 3 mL of the dispersion into the measurement tank and measure at 25°C. The measurement device uses a laser diffraction/scattering particle size distribution measurement device (for example, LA920, manufactured by Horiba, Ltd.) to measure the volume-based particle size distribution. The average particle size is calculated as the particle size (D50%) at which the cumulative particle size from the small diameter side in the volume-based particle size distribution reaches 50%. The refractive index is the refractive index of aluminum oxide. When the inorganic filler is a mixture of aluminum oxide and other inorganic fillers, the refractive index is the refractive index of aluminum oxide.

From the viewpoint of fluidity and formability, the specific surface area of the inorganic filler is preferably 0.7 m ^{2 /} g to 4.0 m ² /g, more preferably 0.9 m ² /g to 3.0 m ² /g, and further preferably 1.0 m ² /g to 2.5 m ² /g. The fluidity of the sealing composition tends to become higher as the specific surface area of the inorganic filler is smaller. In the present disclosure, the specific surface area of the inorganic filler, for example, when alumina is used alone as the inorganic filler, refers to the specific surface area of alumina, and when alumina and other inorganic fillers are used as the inorganic filler, refers to the specific surface area of the mixture of the inorganic fillers. The specific surface area (Brunauer-Emmett-Teller, BET) of an inorganic filler can be measured based on nitrogen adsorption capacity in accordance with JIS Z 8830:2013. As an evaluation device, AUTOSORB-1 (trade name) from QUANTACHROME can be used. When measuring the BET specific surface area, it is considered that the moisture adsorbed on the surface and structure of the sample affects the gas adsorption capacity, so it is better to first perform a pretreatment by heating to remove the moisture. In the pretreatment, the measurement tank with 0.05 g of the measurement sample is depressurized to less than 10 Pa using a vacuum pump, and then heated at 110°C and maintained for more than 3 hours, and then naturally cooled to room temperature (25°C) while maintaining the depressurization. After the pretreatment, the evaluation temperature was set to 77 K and the evaluation pressure range was set to be less than 1 under the relative pressure (equilibrium pressure relative to the saturated vapor pressure).

(Hardening accelerator) The sealing composition may further contain a hardening accelerator. The type of hardening accelerator is not particularly limited, and a known hardening accelerator may be used. Specifically, cyclic amidine compounds such as 1,8-diaza-bicyclo[5.4.0]undecene-7, 1,5-diaza-bicyclo[4.3.0]nonene, 5,6-dibutylamino-1,8-diaza-bicyclo[5.4.0]undecene-7, and maleic anhydride added to the cyclic amidine compound, 1,4-benzoquinone, 2,5-toluoquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone Compounds with intramolecular polarization formed by quinone compounds such as 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, phenyl-1,4-benzoquinone, compounds with π bonds such as diazonium phenylmethane, phenol resins, etc.; tertiary aminated compounds such as benzyldimethylamine, triethanolamine, dimethylaminoethanol, tris(dimethylaminomethyl)phenol, etc. compounds, derivatives of tertiary amine compounds; imidazole compounds and derivatives of imidazole compounds such as 2-methylimidazole, 2-phenylimidazole, and 2-phenyl-4-methylimidazole; organic phosphine compounds such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, tri(4-methylphenyl)phosphine, diphenylphosphine, and phenylphosphine; phosphorus compounds with intramolecular polarization formed by adding maleic anhydride, the quinone compound, diazonophenylmethane, phenol resin, and other compounds having π bonds to organic phosphine compounds; tetraphenylborates and derivatives of tetraphenylborates such as tetraphenylphosphonium tetraphenylborate, triphenylphosphine tetraphenylborate, 2-ethyl-4-methylimidazole tetraphenylborate, and N-methylmorpholine tetraphenylborate; adducts of phosphine compounds such as triphenylphosphonium-triphenylborane and N-methylmorpholine tetraphenylphosphonium-tetraphenylborate with tetraphenylborates, etc. One hardening accelerator may be used alone or two or more may be used in combination.

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

(Ion scavenger) The sealing composition may further contain an ion scavenger. The ion scavenger that can be used in the present disclosure is not particularly limited as long as it is an ion scavenger generally used in a sealing material for manufacturing semiconductor devices. Examples of the ion scavenger 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 scavengers are commercially available. For example, the compound represented by the general formula (II-1) is available as "DHT-4A" (Kyowa Chemical Industry Co., Ltd., trade name). In addition, the compound represented by the general formula (II-2) is available as "IXE500" (Toagosei Co., Ltd., trade name).

In addition, as ion scavengers other than those mentioned above, hydrous oxides of elements selected from magnesium, aluminum, titanium, zirconium, antimony, etc. can be listed. The ion scavengers can be used alone or in combination of two or more.

When the sealing composition contains an ion scavenger, the content of the ion scavenger is preferably 1 part by mass or more relative to 100 parts by mass of the epoxy resin from the viewpoint of achieving sufficient moisture resistance reliability. From the viewpoint of fully exerting the effects of other components, the content of the ion scavenger is preferably 15 parts by mass or less relative to 100 parts by mass of the epoxy resin.

The average particle size of the ion scavenger is preferably 0.1 μm to 3.0 μm, and the maximum particle size is preferably 10 μm or less. The average particle size of the ion scavenger can be measured in the same manner as 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 a known coupling agent may be used. Examples of coupling agents include silane coupling agents and titanium coupling agents. A coupling agent may be used alone or in combination of two or more.

Examples of the silane coupling agent include vinyl trichlorosilane, vinyl triethoxysilane, vinyl tri(β-methoxyethoxy)silane, γ-methacryloyloxypropyl trimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, γ-glycidyloxypropyl trimethoxysilane, vinyl triacetoxysilane, γ-butyl propyl trimethoxysilane, γ-aminopropyl triethoxysilane, γ-[bis(β-hydroxyethyl)]aminopropyl triethoxysilane, 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-anilinopropyltrimethoxysilane, vinyltrimethoxysilane and γ-butylpropylmethyldimethoxysilane.

Examples of the titanium coupling agent include isopropyl triisostearyl titanium ester, isopropyl tri(dioctyl pyrophosphate) titanium ester, isopropyl tri(N-aminoethyl-aminoethyl) titanium ester, tetraoctyl di(di-tridecyl phosphite) titanium ester, tetra(2,2-diallyloxymethyl-1-butyl) di(di-tridecyl phosphite) titanium ester, and di(dioctyl pyrophosphate) titanium ester. Titanium (isopropyl) oxyacetate, bis(dioctyl pyrophosphate) ethylidene titanium, isopropyl trioctyl titanium, isopropyl dimethacryl isostearyl titanium, isopropyl tri-dodecylbenzenesulfonyl titanium, isopropyl isostearyl diacryl titanium, isopropyl tri(dioctyl phosphate) titanium, isopropyl tricumylphenyl titanium and tetraisopropyl di(dioctyl phosphite) titanium.

When the sealing composition contains a coupling agent, the content of the coupling agent is preferably 3 mass % or less, and is preferably 0.1 mass % or more in terms of exerting its effect, relative to the entire sealing composition.

(Release agent) The sealing composition may further contain a release agent. There is no particular limitation on the type of release agent, and a known release agent may be used. Specifically, for example, higher fatty acids, palm wax, and polyethylene wax may be listed. A release agent may be used alone or in combination of two or more. When the sealing composition contains a release agent, the content of the release agent is preferably 10% by mass or less relative to the total amount of the epoxy resin and the hardener, and preferably 0.5% by mass or more from the viewpoint of exerting its effect.

(Colorant and modifier) The sealing composition may also contain a colorant (e.g., carbon black). In addition, the sealing composition may also contain a modifier (e.g., silicone and silicone rubber). The colorant and modifier may be used alone or in combination of two or more.

When conductive particles such as carbon black are used as a coloring agent, the content of conductive particles having a particle size of 10 μm or more is preferably 1% by mass or less. When the sealing composition contains conductive particles, the content of conductive particles is preferably 3% by mass or less relative to the total amount of epoxy resin and hardener.

<Method for producing a sealing composition> The method for producing a sealing composition disclosed herein comprises: a step of determining the composition of an inorganic filler material so that the void ratio becomes a predetermined value; and a step of mixing the inorganic filler material, epoxy resin, and hardener of the composition determined by the step. The predetermined void ratio is preferably 18 volume % or less, more preferably 16 volume % or less, further preferably 15 volume % or less, and particularly preferably 14 volume % or less. The method of determining the composition of an inorganic filler material so that the void ratio becomes a predetermined value is not particularly limited. When the shape of the inorganic filler material is spherical, the void ratio of the inorganic filler material can be calculated based on the particle size distribution of the inorganic filler material. Therefore, the particle size distribution of a plurality of inorganic fillers can be measured in advance and accumulated, the porosity of the inorganic filler can be determined according to the characteristics of the sealing composition, and the plurality of inorganic fillers can be combined in such a way as to obtain the porosity determined in advance, thereby determining the composition of the inorganic filler. As a method for calculating the porosity of the inorganic filler based on the particle size distribution of the inorganic filler, there can be cited a method of calculating using the aforementioned Ouchiyama equation, etc. Then, the inorganic filler, epoxy resin, hardener, and other components used as needed, whose composition is determined in such a way as to obtain the porosity determined in advance, can be fully mixed by a mixer, etc., and then kneaded by a hot roll, an extruder, etc., and subjected to cooling, pulverization, etc. to produce the sealing composition. The state of the sealing composition is not particularly limited and may be in powder, solid, liquid, etc.

<Semiconductor device> The semiconductor device disclosed herein includes a semiconductor element and a cured product of the sealing composition disclosed herein that seals the semiconductor element.

The method of sealing the semiconductor element using the sealing composition is not particularly limited, and a known method can be applied. For example, transfer molding is generally used, but compression molding, injection molding, etc. can also be used.

The semiconductor device disclosed herein is preferably used as an IC, a large-scale integrated circuit (LSI), etc. [Example]

Hereinafter, the embodiments of the present invention will be described, but the present invention is not limited thereto. In addition, unless otherwise specified, the numerical values in the table refer to "parts by mass".

(Example 1 to Example 6 and Comparative Example 1 to Comparative Example 3) The following components are pre-mixed (dry blended) at the blending ratio (mass parts) shown in Table 1 or Table 2, kneaded using a double-screw kneader, and then cooled and pulverized to produce a powdered sealing composition.

[Table 1] Project Comparison Example 1 Comparison Example 2 Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 （A）Epoxy A1 62.5 62.5 62.5 62.5 62.5 62.5 A2 twenty four twenty four twenty four twenty four twenty four twenty four A3 16.7 16.7 16.7 16.7 16.7 16.7 (B) Hardener B1 56.1 56.1 56.1 56.1 56.1 56.1 (C) Hardening accelerator C1 3.3 3.3 3.3 3.3 3.3 3.3 (D) Filling D1 871 874 931 1258 1249 912 D2 731 609 499 331 150 50 D3 263 364 405 243 405 810 D4 66 91 108 113 151 195 D5 13 13 13 13 13 13 Filler content [volume %] 77 77 77 77 77 77

[Table 2] Project Comparison Example 3 Embodiment 5 Embodiment 6 （A）Epoxy A1 40 40 40 A2 twenty four twenty four twenty four A3 39.2 39.2 39.2 (B) Hardener B1 58.7 58.7 58.7 (C) Hardening accelerator C1 3.3 3.2 3.1 (D) Filling D6 1680 1716 1745 D4 268 229 199 D5 14 14 14 Filler content [volume %] 78 78 78

(A) Epoxy resin · A1···Bisphenol type crystalline epoxy resin, epoxy equivalent: 192 g/eq · A2···Biphenyl type epoxy resin, epoxy equivalent: 192 g/eq · A3···Bisphenol F type epoxy resin, epoxy equivalent: 158 g/eq (B) Hardener · B1···Triphenylmethane type phenol resin, triphenylmethane type phenol resin with hydroxyl equivalent of 104 g/eq (C) Hardening accelerator · C1···Phosphorus-based hardening accelerator (addition product of tributylphosphine and benzoquinone) (D) Filler (inorganic filler) ·D1···Alumina filler with an average particle size (D50, the particle size corresponding to 50% of the volume from the small diameter side) of 10.4 μm and a specific surface area of 1.5 m ² /g ·D2···Alumina filler with an average particle size of 1.6 μm and a specific surface area of 3.3 m ² /g ·D3···Alumina filler with an average particle size of 43.9 μm and a specific surface area of 0.15 m ² /g ·D4···Alumina filler with an average particle size of 0.7 μm and a specific surface area of 8.0 m ² /g ·D5···Silica filler with a specific surface area of 200 m ² /g ·D6···Average particle size of 11.7 μm and a specific surface area of 2.2 m ² /g of alumina filler/silicon dioxide filler = 9/1 (mass ratio) mixture

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

<Hardening property> Hardening property is evaluated based on the gelation time measured as follows using a gelation tester. 0.5 g of the obtained sealing composition is placed on a hot plate heated to 175°C, and the sample is uniformly expanded into a 2.0 cm to 2.5 cm circle using a clamp at a rotation speed of 20 rpm to 25 rpm. The time from the sample being placed on the hot plate until the viscosity of the sample disappears, the sample becomes a gel state, and it is peeled off from the hot plate is measured, and this is set as the gelation time (sec) for measurement. The results are shown in Table 3 or Table 4. When the same amount of catalyst (hardening accelerator) is used relative to 100 parts by mass of epoxy resin, the shorter the gelling time, the better the hardening property.

<Flowability> The obtained sealing composition was passed through two sieves (upper section: 2.38 mm, lower section: 0.5 mm), and 7 g of the sample remaining in the lower section was weighed. The sealing composition was placed on a smooth mold heated to 180°C, and an 8 kg smooth mold heated to 180°C was placed on the sample and left for 60 seconds. Thereafter, the average value (mm) of the major diameter (mm) and minor diameter (mm) of the obtained disk-shaped molded product was calculated, and the average value (mm) was set as the disk flow (DF). The results are shown in Table 3 or Table 4. The longer the disk flow, the better the flowability.

<Formability> 15 g of the obtained sealing composition was placed on a mold at 180°C on a hot plate and formed with a curing time of 90 seconds. After forming, the length of the longest portion of the sealing composition flowing on the narrow slits of 50 μm, 30 μm, 20 μm, 10 μm, 5 μm and 2 μm made in the mold was measured using a vernier ruler, and the measured value was set as the burr length. The results are shown in Table 3 or Table 4. The shorter the burr, the better the formability.

<Thermal conductivity> Using the obtained sealing composition, a test piece for thermal conductivity evaluation was prepared using a vacuum hand-pressing machine at a mold temperature of 175°C to 180°C, a molding pressure of 7 MPa, and a curing time of 600 seconds. Then, the heat diffusion rate in the thickness direction of the molded test piece was measured. The heat diffusion rate was measured using a laser flash method (device: LFA467 nanoflash, manufactured by NETZSCH). Pulse light irradiation was performed under the conditions of a pulse width of 0.31 (ms) and an applied voltage of 247 V. The measurement was performed at an ambient temperature of 25°C ± 1°C. In addition, the density of the test piece was measured using an electronic densimeter (AUX220, Shimadzu Corporation). The specific heat is the theoretical specific heat of the sealing composition calculated using the literature value of the specific heat of each material and the blending ratio. Then, the value of thermal conductivity is obtained by using formula (1) and multiplying the specific heat and density by the heat diffusion rate. λ=α×Cp×ρ···Formula (1) (In formula (1), λ represents thermal conductivity (W/(m·K)), α represents heat diffusion rate (m ² /s), Cp represents specific heat (J/(kg·K)), and ρ represents density (kg/m ³ )) The results are shown in Table 3 or Table 4.

[Table 3] Comparison Example 1 Comparison Example 2 Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Void ratio [%] 23.4 20.2 17.5 15.9 14.6 13.6 Specific surface area [m ² /g] 2.5 2.5 2.5 2.5 2.5 2.5 Average particle size [μm] 5.0 6.4 7.9 8.5 11.7 24.3 Gel time [sec] 67 58 52 52 48 49 Flowability (DF) [mm] 94 105 107 112 113 114 Burr [mm] 6.8 4.5 3.4 3.0 2.1 2.6 Thermal conductivity λ[W/(m·K)] 4.5 4.6 4.9 4.8 5.2 5.5

[Table 4] Comparison Example 3 Embodiment 5 Embodiment 6 Void ratio [%] 18.1 16.7 16.0 Specific surface area [m ² /g] 3.4 3.1 2.9 Average particle size [μm] 8.7 8.9 9.2 Gel time [sec] 50 51 50 Flowability (DF) [mm] 115 119 123 Burr [mm] 3.2 3.1 2.9 Thermal conductivity λ[W/(m·K)] 4.0 4.1 4.2

The evaluation results in Tables 3 and 4 clearly show that the sealing compositions of Examples 1 to 6, in which the void ratio of the inorganic filler is 18 volume % or less, are superior in curability, fluidity, and formability compared to the sealing compositions of Comparative Examples 1 to 3, in which the void ratio of the inorganic filler exceeds 18 volume %. In addition, the thermal conductivity of the cured products of the sealing compositions of Examples 1 to 6 is equal to or higher than the thermal conductivity 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 by reference in its entirety into this specification. All documents, patent applications, and technical specifications described in this specification are incorporated by reference into this specification to the same extent as if each document, patent application, and technical specification were specifically and individually described as being incorporated by reference.

Claims (6)

A sealing composition comprises an epoxy resin, a hardener, and an inorganic filler having a porosity of 18 volume % or less. The sealing composition according to claim 1, wherein the volume average particle size of the inorganic filler is 4 μm to 100 μm. In the sealing composition according to claim 1 or claim 2, the inorganic filler comprises at least one of aluminum oxide and silicon dioxide. 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 comprises a semiconductor element and a cured product of the sealing composition according to any one of claims 1 to 4, which seals the semiconductor element. A method for manufacturing a sealing composition, comprising: a step of determining the composition of an inorganic filler so that the porosity becomes a predetermined value; and a step of mixing the inorganic filler, epoxy resin, and hardener of the composition determined by the step.