JP7571810B2 - Encapsulating composition and semiconductor device - Google Patents

Description

The present invention relates to an encapsulating composition and a semiconductor device.

In recent years, with miniaturization and high integration, there has been concern about heat generation inside semiconductor packages. Since heat generation may cause a decrease in the performance of electric or electronic components that have semiconductor packages, materials used in semiconductor packages are required to have high thermal conductivity. Therefore, there is a demand for high thermal conductivity of the encapsulating material of semiconductor packages.
One method for increasing the thermal conductivity of a sealing material is to use alumina, which is a highly thermally conductive filler, as an inorganic filler contained in the sealing material (see, for example, Patent Document 1).

JP 2006-273920 A

However, the method described in Patent Document 1 may cause the fluidity of the encapsulant to deteriorate. For example, a semiconductor package employing a method called a wire bonding structure in which a semiconductor element and a substrate are connected via wires is formed by encapsulating a semiconductor element, a substrate, and the wires electrically connecting them with a resin composition. In this case, pressure is applied to the wires due to the flow of the encapsulant, which may cause the wires to be misaligned (wire sweep) or may not adequately protect the semiconductor element.
Thus, it may be difficult to achieve both flowability and high thermal conductivity in the sealing material.

One aspect of the present invention has been made in consideration of the above-mentioned conventional circumstances, and aims to provide an encapsulating composition having excellent fluidity and high thermal conductivity, and a semiconductor device using the same.

Specific means for achieving the above object are as follows.
<1> Contains an epoxy resin, a curing agent, and an inorganic filler,
The particle size distribution of the inorganic filler has at least three peaks,
The sealing composition, wherein the inorganic filler contains alumina having a particle size of 1 μm or less.
<2> The sealing composition according to <1>, wherein the particle size distribution of the inorganic filler has peaks in the range of 0.3 μm to 0.7 μm, the range of 7 μm to 20 μm, and the range of 30 μm to 70 μm.
<3> The sealing composition according to <1> or <2>, wherein the inorganic filler contains inorganic particles having a particle diameter of 1 μm or less, and the proportion of alumina in the inorganic particles is 1 vol % to 40 vol %.
<4> The sealing composition according to any one of <1> to <3>, wherein the inorganic filler has an average circularity of 0.80 or more.
<5> A semiconductor device comprising: a semiconductor element; and a cured product of the encapsulating composition according to any one of <1> to <4>, which encapsulates the semiconductor element.

According to one aspect of the present invention, it is possible to provide a sealing composition having excellent fluidity and high thermal conductivity, and a semiconductor device using the same.

Hereinafter, the embodiment for carrying out the encapsulating composition and semiconductor device of the present invention will be described in detail. However, the present invention is not limited to the following embodiment. In the following embodiment, the components (including element steps, etc.) are not essential unless specifically stated. The same applies to the numerical values and their ranges, and do not limit the present invention.
In the present disclosure, the numerical ranges indicated using "to" include the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.
In the present disclosure, each component may contain multiple types of the corresponding substance. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified.
In the present disclosure, a composition may contain multiple types of particles corresponding to each component. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple 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, the particle size distribution of the inorganic filler having at least three peaks, and the inorganic filler contains alumina having a particle diameter of 1 μm or less.
The sealing composition of the present disclosure has excellent fluidity and high thermal conductivity, and although the reason for this is not clear, it is presumed to be as follows.
The inorganic filler contained in the sealing composition shows a particle size distribution having at least three peaks. That is, the inorganic filler is composed of at least inorganic particles having a large particle size, inorganic particles having a medium particle size, and inorganic particles having a small particle size. Since the inorganic filler contains inorganic particles having a large particle size, inorganic particles having a medium particle size, and inorganic particles having a small particle size, it is considered that the sealing composition of the present disclosure has excellent flowability.
In addition, the inorganic filler contains alumina having a particle size of 1 μm or less, and alumina exhibits high thermal conductivity as described above. In addition, alumina having a particle size of 1 μm or less corresponds to small particle size inorganic particles as an inorganic filler contained in the sealing composition. By containing alumina as small particle size inorganic particles, alumina, which is a small particle size inorganic particle, is easily interposed between large particle size inorganic particles and medium particle size inorganic particles. By interposing alumina exhibiting high thermal conductivity between large particle size inorganic particles and medium particle size inorganic particles, it is possible to promote thermal conduction between the large particle size inorganic particles and the medium particle size inorganic particles. As a result, it is presumed that the sealing composition of the present disclosure has high thermal conductivity.

The components constituting the sealing composition are described 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 the epoxy resin is not particularly limited, and any known epoxy resin can be used.
Specifically, for example, novolak resins obtained by condensing or co-condensing at least one selected from the group consisting of phenolic compounds (e.g., phenol, cresol, xylenol, resorcin, 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 salicylaldehyde) under an acidic catalyst are epoxidized (e.g., phenol novolak type epoxy resins and orthocresol novolak type epoxy resins); bisphenols (e.g., bisphenol A, bisphenol AD, bisphenol F, and bisphenol S) ) and biphenols (e.g., alkyl-substituted and unsubstituted biphenols); epoxidized products of phenol-aralkyl resins; epoxidized products of adducts or polyadditions of phenolic compounds with at least one selected from the group consisting of dicyclopentadiene and terpene compounds; glycidyl ester type epoxy resins obtained by reacting polybasic acids (e.g., phthalic acid and dimer acid) with epichlorohydrin; glycidylamine type epoxy resins obtained by reacting polyamines (e.g., diaminodiphenylmethane and isocyanuric acid) with epichlorohydrin; linear aliphatic epoxy resins obtained by oxidizing olefin bonds with peracids (e.g., peracetic acid); and alicyclic epoxy resins. The epoxy resins may be used alone or in combination of two or more.

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

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

The content of the epoxy resin in the sealing composition is preferably 1.5% by mass to 20% by mass, more preferably 2.0% by mass to 15% by mass, and further preferably 3.0% by mass to 10% by mass.
The content of the epoxy resin in the sealing composition excluding the inorganic filler is preferably 30% by mass to 65% by mass, more preferably 35% by mass to 60% by mass, and further preferably 40% by mass to 55% by mass.

- Hardener -
The sealing composition contains a curing agent. The type of the curing agent is not particularly limited, and any known curing agent can be used.
Specifically, for example, novolak resins obtained by condensing or co-condensing at least one selected from the group consisting of phenolic compounds (e.g., phenol, cresol, resorcin, 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 salicylaldehyde) under an acid catalyst; phenol-aralkyl resins; biphenyl-aralkyl resins; and naphthol-aralkyl resins; may be mentioned. The curing agent may be used alone or in combination of two or more kinds. Among them, phenol-aralkyl resins are preferable as the curing agent from the viewpoint of improving reflow resistance. The curing agent may be used alone or in combination of two or more kinds.

It is preferable to mix the curing agent so that the equivalent of the functional group of the curing agent (for example, a phenolic hydroxyl group in the case of a novolac resin) is 0.5 to 1.5 equivalents per equivalent of the epoxy group of the epoxy resin, and it is particularly preferable to mix the curing agent so that the equivalent is 0.7 to 1.2 equivalents.

- Inorganic filler -
The sealing composition contains an inorganic filler, which tends to reduce the moisture absorption of the sealing composition and improve the strength in a cured state.

The inorganic fillers may be used alone or in combination of two or more kinds.
The use of two or more types of inorganic fillers in combination may, for example, be of two or more types of inorganic fillers differing in components, average particle size, shape, or the like.
The shape of the inorganic filler is not particularly limited, and examples thereof include powder, spheres, fibers, etc. From the viewpoints of flowability during molding of the sealing composition and mold abrasion, a spherical shape is preferred.

The average circularity of the inorganic filler is preferably 0.80 or more, more preferably 0.85 or more, even more preferably 0.90 or more, and particularly preferably 0.93 or more. The average circularity of the inorganic filler may be 1.0 or less.
The circularity of an inorganic filler is a numerical value obtained by dividing the perimeter of a circle calculated from the equivalent circle diameter, which is the diameter of a circle having the same area as the projected area of the inorganic filler, by the perimeter (length of the outline) measured from the projected image of the inorganic filler, and is calculated by the following formula. The circularity of a perfect circle is 1.00.
Circularity=(perimeter of equivalent circle)/(perimeter of cross-sectional image of particle)
Specifically, the average circularity is a value calculated as the arithmetic mean value by observing an image magnified 1000 times with a scanning electron microscope, randomly selecting 10 inorganic fillers, measuring the circularity of each of the inorganic fillers by the above-mentioned method, and calculating the average value. The circularity, the perimeter of the equivalent circle, and the perimeter of the projected image of the particle can be determined by commercially available image analysis software.
When two or more types of inorganic fillers are used in combination, the average circularity of the inorganic fillers refers to the value of a mixture of two or more types of inorganic fillers.

The inorganic filler is not particularly limited in terms of material, particle size, etc., so long as it contains alumina whose particle size distribution has at least three peaks and whose particle size is 1 μm or less.
Examples of inorganic fillers include silica such as spherical silica and crystalline silica, alumina, zircon, magnesium oxide, calcium silicate, calcium carbonate, potassium titanate, silicon carbide, silicon nitride, boron nitride, aluminum nitride, beryllia, zirconia, etc. Examples of inorganic fillers having a flame retardant effect include aluminum hydroxide, zinc borate, etc. Among these, alumina is preferred from the viewpoint of high thermal conductivity.
The proportion of alumina in the inorganic filler is preferably 60% by mass to 95% by mass, more preferably 60% by mass to 92% by mass, and further preferably 60% by mass to 90% by mass.
Alumina and silica may be used in combination as the inorganic filler. When alumina and silica are used in combination as the inorganic filler, the ratio of alumina in the inorganic filler is preferably 80% by mass to 95% by mass and the ratio of silica is preferably 5% by mass to 20% by mass, more preferably 82% by mass to 92% by mass and the ratio of silica is preferably 8% by mass to 18% by mass, and further preferably 85% by mass to 90% by mass and the ratio of silica is preferably 10% by mass to 15% by mass.

The particle size distribution of the inorganic filler has at least three peaks, and preferably has three peaks. The positions of the peaks in the particle size distribution of the inorganic filler are not particularly limited, and for example, it is preferable for the peaks to be in the ranges of 0.3 μm to 0.7 μm, 7 μm to 20 μm, and 30 μm to 70 μm, and it is more preferable for the peaks to be in the ranges of 0.3 μm to 0.6 μm, 7 μm to 15 μm, and 40 μm to 70 μm.

The particle size distribution of the inorganic filler can be determined by the following method.
The inorganic filler to be measured is added to a solvent (pure water) in the range of 0.02% by mass to 0.08% by mass, and the inorganic filler is dispersed by vibrating it for 1 to 10 minutes in a 110 W bath-type ultrasonic cleaner. Approximately 40 mL of the dispersion is poured into a measurement cell and measured at 25°C. The measurement device is a laser diffraction/scattering type particle size distribution measurement device (for example, LA920 (product name) by Horiba, Ltd.), which measures the volumetric particle size distribution. The refractive index used is that of alumina. Even when the inorganic filler is a mixture of alumina and an inorganic filler other than alumina, the refractive index used is that of alumina.

The proportion of alumina in the inorganic particles having a particle diameter of 1 μm or less contained in the inorganic filler is preferably 1 vol% to 40 vol%, more preferably 10 vol% to 35 vol%, and even more preferably 15 vol% to 30 vol%.
The proportion of alumina in the inorganic particles having a particle size of 1 μm or less contained in the inorganic filler can be measured by the following method.
For each inorganic particle confirmed to have a particle diameter of 1 μm or less by a scanning electron microscope, the constituent elements are identified by energy dispersive X-ray spectrometry to determine the material of the inorganic particle. The volume ratio of alumina in 50 inorganic particles having a particle diameter of 1 μm or less contained in the inorganic filler can be determined by determining the volume ratio of alumina. The particle diameter of each inorganic particle is the equivalent circle diameter, which is the diameter of a circle having the same area as the projected area.

The proportion of alumina in the inorganic particles having a particle diameter of 10 μm or more contained in the inorganic filler is preferably 20 vol% to 60 vol%, more preferably 25 vol% to 55 vol%, and even more preferably 30 vol% to 50 vol%.
The proportion of alumina in inorganic particles having a particle size of 10 μm or more contained in the inorganic filler can be determined in the same manner as the proportion of alumina in inorganic particles having a particle size of 1 μm or less contained in the inorganic filler.

From the viewpoints of moisture absorption, reduction of the linear expansion coefficient, strength improvement, and solder heat resistance, the amount of inorganic filler to be mixed is preferably within the range of 75% by mass to 97% by mass, and more preferably within the range of 80% by mass to 95% by mass, of the entire sealing composition.

In order to make the inorganic filler have a particle size distribution with at least three peaks, for example, a method of blending three kinds of inorganic fillers with different average particle sizes can be mentioned, but is not limited to this. For example, an inorganic filler having an average particle size of 0.3 μm to 0.7 μm, an inorganic filler having an average particle size of 7 μm to 20 μm, and an inorganic filler having an average particle size of 30 μm to 70 μm may be used in combination.
The average particle size of the inorganic filler as a whole is preferably 4 μm to 30 μm, more preferably 5 μm to 25 μm, and even more preferably 6 μm to 20 μm.
The average particle size of the inorganic filler is determined as the particle size (D50%) at which the accumulation from the small diameter side reaches 50% in the volume-based particle size distribution measured with a laser diffraction/scattering particle size distribution measuring device (e.g., LA920 (product name) manufactured by Horiba, Ltd.) using a dispersion of the inorganic filler prepared in the same manner as in the measurement of the particle size distribution of the inorganic filler.

(Cure Accelerator)
The sealing composition may further contain a curing accelerator. The type of the curing accelerator is not particularly limited, and any known curing accelerator may be used.
Specifically, cycloamidine compounds such as 1,8-diaza-bicyclo[5.4.0]undecene-7, 1,5-diaza-bicyclo[4.3.0]nonene, and 5,6-dibutylamino-1,8-diaza-bicyclo[5.4.0]undecene-7; cycloamidine compounds with maleic anhydride, 1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, and 2,3-dimethoxy-5-methyl-1,4-benzoquinone; quinone compounds such as phenyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, etc., compounds having intramolecular polarization obtained by adding compounds having a π bond such as diazophenylmethane and phenol resin; tertiary amine compounds such as benzyldimethylamine, triethanolamine, dimethylaminoethanol, tris(dimethylaminomethyl)phenol, etc., and derivatives of tertiary amine compounds; 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, Examples of the curing accelerator include imidazole compounds such as thiimidazole, derivatives of imidazole compounds, organic phosphine compounds such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, tris(4-methylphenyl)phosphine, diphenylphosphine, and phenylphosphine, and phosphorus compounds having intramolecular polarization obtained by adding a compound having a π bond such as maleic anhydride, the above-mentioned quinone compound, diazophenylmethane, and phenolic resin to an organic phosphine compound, tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate, triphenylphosphine tetraphenylborate, 2-ethyl-4-methylimidazole tetraphenylborate, and N-methylmorpholine tetraphenylborate, and derivatives of tetraphenylboron salts, and adducts of phosphine compounds such as triphenylphosphonium-triphenylborane and N-methylmorpholine tetraphenylphosphonium-tetraphenylborate with 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% to 8% by mass based on the total amount of the epoxy resin and the curing agent.

(Ion trapping agent)
The sealing composition may further include 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 an ion trapping agent that is generally used in sealing materials used in the manufacture of semiconductor devices, and examples of the ion trapping agent include hydrotalcite, etc. As the ion trapping agent, a compound represented by the following general formula (II-1) or the following general formula (II-2) may be used.

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 the 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. For example, "DHT-4A" (Kyowa Chemical Industry Co., Ltd., product name) is a commercially available example of the compound represented by general formula (II-1). For example, "IXE500" (Toagosei Co., Ltd., product name) is a commercially available example of the compound represented by general formula (II-2).

Other examples of ion trapping agents include hydrous oxides of elements selected from magnesium, aluminum, titanium, zirconium, antimony, and the like.
The ion trapping agent may be used alone or in combination of two or more kinds.

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 in the sealing composition from the viewpoint of realizing sufficient moisture resistance reliability. From the viewpoint of fully exerting the effects of other components, the content of the ion trapping agent is preferably 15 parts by mass or less per 100 parts by mass of the epoxy resin in the sealing composition.

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 size of the ion trapping agent can be measured in the same manner as for the inorganic filler.

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

Examples of silane coupling agents include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-[bis(β-hydroxyethyl)]aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, Methoxysilane, 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-mercaptopropylmethyldimethoxysilane.

Examples of titanium coupling agents include isopropyl triisostearoyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl phosphite) titanate, bis(dioctyl pyrophosphate)oxyacetate titanate, bis(dioctyl pyrophosphate)ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearoyl titanate, isopropyl tridodecyl benzenesulfonyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumyl phenyl 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 total sealing composition, and from the viewpoint of exerting its effect, it is preferable that the content of the coupling agent is 0.1% by mass or more.

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

(Colorants and Modifiers)
The sealing composition may contain a colorant (e.g., carbon black). The sealing composition may also contain a modifier (e.g., silicone and silicone rubber). The colorant and modifier may each be used alone or in combination of two or more kinds.

When conductive particles such as carbon black are used as the colorant, the conductive particles preferably have a content of particles having a particle diameter of 10 μm or more of 1 mass % or less.
When the sealing composition contains conductive particles, the content of the conductive particles is preferably 4 mass % or less based on the total amount of the epoxy resin and the curing agent.

<Method of producing sealing composition>
The method for producing the encapsulating composition is not particularly limited, and can be performed by a known method. For example, the encapsulating composition can be produced by thoroughly mixing a mixture of raw materials in a predetermined amount using a mixer or the like, kneading the mixture using a hot roll, an extruder, or the like, and then cooling, pulverizing, or the like. The state of the encapsulating composition is not particularly limited, and may be in a 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 that seals the semiconductor element.

There are no particular limitations on the method for encapsulating a semiconductor element using the encapsulating composition, and any known method can be used. For example, the transfer molding method is common, but compression molding method, injection molding method, etc. may also be used.

The semiconductor device disclosed herein is suitable for use as an IC, LSI (Large-Scale Integration), etc.

The following describes examples of the present invention, but the present invention is not limited to these. In addition, the numerical values in the table mean "parts by mass" unless otherwise specified.

(Examples 1 to 11 and Comparative Examples 1 and 2)
The materials shown in Tables 1 to 3 were premixed (dry blended), then kneaded for about 15 minutes with a biaxial roll (roll surface temperature: about 80° C.), and cooled and pulverized to produce a powdered sealing composition.

Details of the materials in the table are as follows. Also, "-" in the table indicates that the corresponding ingredient is not contained.

(Epoxy resin)
Epoxy resin 1: biphenyl type epoxy resin, epoxy equivalent: 186 g/eq
Epoxy resin 2: multifunctional epoxy resin, epoxy equivalent: 167 g/eq
Epoxy resin 3: bisphenol type crystalline epoxy resin, epoxy equivalent: 192 g/eq
Epoxy resin 4: BisF type epoxy resin, epoxy equivalent: 159 g/eq

(Hardening agent)
Curing agent 1: Multifunctional phenolic resin, triphenylmethane type phenolic resin with hydroxyl equivalent of 102 g/eq. Curing agent 2: Multifunctional phenolic resin, biphenyl aralkyl resin with hydroxyl equivalent of 205 g/eq. Curing agent 3: Phenol aralkyl resin, hydroxyl equivalent: 170 g/eq.

・Cure accelerator: Phosphorus-based cure accelerator ・Coupling agent: Epoxy silane (γ-glycidoxypropyltrimethoxysilane)
Release agent: Montan acid ester Colorant: Carbon black Ion trapping agent: Hydrotalcite Modifier: Silicone

(Inorganic filler)
Inorganic filler 1: a mixture of alumina and silica (average particle size: 8.6 μm)
Inorganic filler 2: Silica (average particle size: 9.5 μm)
Inorganic filler 3: Alumina (average particle size: 0.4 μm)
Inorganic filler 4: Silica (average particle size: 0.8 μm)
Inorganic filler 5: Silica (average particle size: 0.1 μm)
Inorganic filler 6: Silica (average particle size: 13.0 μm)
Inorganic filler 7: Silica (average particle size: 2.2 μm)
Inorganic filler 8: Silica (average particle size: 0.8 μm)
Inorganic filler 9: a mixture of alumina and silica (average particle size: 7.4 μm)
Inorganic filler 10: Silica (average particle size: 1.5 μm)
Inorganic filler 11: Silica (average particle size: 22.0 μm)
Inorganic filler 12: Alumina (average particle size: 14.9 μm)
Inorganic filler 13: Alumina (average particle size: 10.4 μm)
Inorganic filler 14: Alumina (average particle size: 2.0 μm)
Inorganic filler 15: a mixture of alumina and silica (average particle size: 43.9 μm)

The positions of the peaks in the particle size distribution of the inorganic fillers of Examples 1 to 11 are as follows:
There were three peaks. All of the sealing compositions according to Examples 1 to 11 contained alumina having a particle size of 1 μm or less. The average particle size of the entire inorganic filler is also shown below.
Example 1: 0.45 μm, 10 μm and 40 μm (average particle size: 8.1 μm)
Example 2: 0.5 μm, 10 μm and 50 μm (average particle size: 8.7 μm)
Example 3: 0.5 μm, 10 μm and 50 μm (average particle size: 7.6 μm)
Example 4: 0.5 μm, 10 μm and 50 μm (average particle size: 7.7 μm)
Example 5: 0.5 μm, 10 μm and 50 μm (average particle size: 6.6 μm)
Example 6: 0.5 μm, 10 μm and 51 μm (average particle size: 6.2 μm)
Example 7: 0.5 μm, 10 μm and 51 μm (average particle size: 7.7 μm)
Example 8: 0.5 μm, 10 μm and 51 μm (average particle size: 6.6 μm)
Example 9: 0.5 μm, 10 μm and 51 μm (average particle size: 10.8 μm)
Example 10: 0.45 μm, 10 μm and 51 μm (average particle size: 6.4 μm)
Example 11: 0.4 μm, 9 μm and 45 μm (average particle size: 7.8 μm)
On the other hand, the position of the peak in the particle size distribution of the inorganic filler of Comparative Example 1 was as follows, and there were two peaks. The sealing composition according to Comparative Example 1 contained alumina having a particle diameter of 1 μm or less. The average particle diameter of the entire inorganic filler is also shown below.
Comparative Example 1: 1.5 μm and 10 μm (average particle size: 11.3 μm)
The positions of the peaks in the particle size distribution of the inorganic filler of Comparative Example 2 were as follows, and the inorganic filler had three peaks. The sealing composition according to Comparative Example 2 did not contain alumina having a particle diameter of 1 μm or less. The average particle diameter of the inorganic filler as a whole is also shown below.
Comparative Example 2: 0.5 μm, 10 μm and 50 μm (average particle size: 6.5 μm)

<Liquidity assessment>
The flowability of the sealing composition was evaluated by a spiral flow test.
Specifically, the encapsulating composition was molded using a spiral flow measurement die conforming to EMMI-1-66, and the flow distance (cm) of the molded product of the encapsulating composition was measured. The encapsulating composition was molded using a transfer molding machine under the conditions of a die temperature of 180° C., a molding pressure of 6.9 MPa, and a curing time of 120 seconds.
In addition, the fluidity was rated as A for 160 cm or more, B for 150 cm or more but less than 160 cm, and C for less than 150 cm.

<Evaluation of thermal conductivity>
The thermal conductivity of the sealing composition was evaluated by the following method.
Specifically, the prepared sealing composition was used for transfer molding under the conditions of a mold temperature of 180°C, molding pressure of 7 MPa, and curing time of 300 seconds to obtain a mold-shaped cured product. The density of the obtained cured product measured by Archimedes method was 2.8 g/cm ³ to 3.0 g/cm ^3. The thermal diffusivity of the cured product was measured by the laser flash method using a thermal diffusivity measuring device (NETZSCH, LFA467). The thermal conductivity (W/(m·K)) was calculated from the product of the thermal diffusivity measured above, the density measured by Archimedes method, and the specific heat measured by DSC (differential scanning calorimeter).
In addition, thermal conductivity of 2.5 W/(m·K) or more was rated A, and thermal conductivity of less than 2.5 W/(m·K) was rated B.

As shown in Tables 4 to 6, from the results of Examples 1 to 11 having three peaks and Comparative Example 1 having two peaks, regardless of the proportion of alumina in the inorganic filler, the fluidity was extremely reduced and the thermal conductivity was reduced by not having three peaks in the particle size distribution of the inorganic filler.
In addition, Comparative Example 2, which does not contain alumina having a particle diameter of 1 μm or less in the inorganic filler, showed the same or lower fluidity and lower thermal conductivity compared to Examples 1, 5, 6, 8, 10, and 11, which have a particularly large amount of alumina having a particle diameter of 1 μm or less in the inorganic filler.

The disclosure of Japanese Patent Application No. 2017-254883, filed on December 28, 2017, is incorporated herein by reference in its entirety.
All publications, patent applications, and standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or standard was specifically and individually indicated to be incorporated by reference.

Claims (5)

Contains an epoxy resin, a curing agent, and an inorganic filler,
The particle size distribution of the inorganic filler has at least three peaks,
The inorganic filler contains alumina having a particle size of 1 μm or less,
The particle size distribution of the inorganic filler has a peak in the range of 40 μm to 70 μm,
The ratio of alumina in the inorganic filler is 60% by mass to 90% by mass,
The sealing composition , wherein the inorganic filler as a whole has an average particle size of 4 μm to 20 μm . The sealing composition according to claim 1, wherein the particle size distribution of the inorganic filler has peaks in the ranges of 0.3 μm to 0.7 μm, 7 μm to 20 μm, and 40 μm to 70 μm. The sealing composition according to claim 1 or 2, wherein the proportion of alumina in the inorganic particles having a particle diameter of 1 μm or less contained in the inorganic filler is 1% by volume to 40% by volume. The sealing composition according to any one of claims 1 to 3, wherein the inorganic filler has an average circularity of 0.80 or more. 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 seals the semiconductor element.