JP7238791B2 - Encapsulating composition and semiconductor device - Google Patents

Description

The present invention relates to encapsulation compositions and semiconductor devices.

In recent years, with miniaturization and high integration, there is concern about heat generation inside a semiconductor package. Since heat generation may deteriorate the performance of electrical or electronic components having semiconductor packages, members used in semiconductor packages are required to have high thermal conductivity. Therefore, it is required to improve the thermal conductivity of the sealing material of the semiconductor package.
As one method for increasing the thermal conductivity of the sealing material, there is a method of using 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, in the method described in Patent Document 1, the fluidity of the sealing material may deteriorate. For example, in a semiconductor package employing a method called wire bonding structure in which a semiconductor element and a substrate are connected via wires, a semiconductor element, a substrate, and wires electrically connecting them are made of a resin composition. It is formed by sealing. At this time, pressure is applied to the wires due to the flow of the encapsulant, which may cause displacement of the wires (wire drift) and insufficient protection of the semiconductor element.
Thus, it may be difficult to achieve both fluidity and high thermal conductivity of the sealing material.

An object of the present invention is to provide a sealing 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, 7 μm to 20 μm, and 30 μm to 70 μm.
<3> The sealing composition according to <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.
<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 sealing composition according to any one of <1> to <4>, obtained by sealing the semiconductor element.

ADVANTAGE OF THE INVENTION According to one form of this invention, the sealing composition which has excellent fluidity|liquidity and high thermal conductivity, and a semiconductor device using the same can be provided.

Modes for carrying out the encapsulating composition and semiconductor device of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps and the like) are not essential unless otherwise specified. The same applies to numerical values and their ranges, which do not limit the present invention.
In the present disclosure, the numerical range indicated using "-" includes the numerical values before and after "-" as the minimum and maximum values, respectively.
In the numerical ranges described step by step in the present disclosure, the upper limit or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described step by step. . Moreover, in the numerical ranges described in the present disclosure, the upper or lower limits of the numerical ranges may be replaced with the values shown in the examples.
In the present disclosure, each component may contain multiple types of applicable substances. When 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, a plurality of types of particles corresponding to each component may be included. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means a value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

<Sealing composition>
The encapsulating composition of the present disclosure contains an epoxy resin, a curing agent, and an inorganic filler, wherein the particle size distribution of the inorganic filler has at least three peaks, and the inorganic filler has a particle size of contains alumina of 1 μm or less.
The sealing composition of the present disclosure has excellent fluidity and high thermal conductivity. Although the reason is not clear, it is presumed as follows.
The inorganic filler contained in the sealing composition exhibits a particle size distribution with at least three peaks. That is, the inorganic filler contains at least inorganic particles with a large particle size, inorganic particles with a medium particle size, and inorganic particles with a small particle size. Since the inorganic filler contains large particle size inorganic particles, medium particle size inorganic particles, and small particle size inorganic particles, the sealing composition of the present disclosure is believed to have excellent fluidity.
Further, 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 inorganic particles having a small particle size as an inorganic filler contained in the sealing composition. By including alumina as the inorganic particles with a small particle size, the alumina, which is an inorganic particle with a small particle size, is likely to intervene between the inorganic particles with a large particle size and the inorganic particles with a medium particle size. Alumina, which exhibits high thermal conductivity, is interposed between the large-particle-size inorganic particles and the medium-particle-size inorganic particles, thereby promoting heat conduction between the large-particle-size inorganic particles and the medium-particle-size inorganic particles. be able to. As a result, the encapsulating compositions of the present disclosure are expected to have high thermal conductivity.

Each component constituting the sealing composition will be described below. The encapsulating composition of the present disclosure contains an epoxy resin, a curing agent, an inorganic filler, and optionally other ingredients.

-Epoxy resin-
The encapsulating composition contains an epoxy resin. The type of epoxy resin is not particularly limited, and known epoxy resins can be used.
Specifically, for example, selected from the group consisting of phenol 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, and an epoxidized novolak resin obtained by condensation or co-condensation (e.g., phenol novolak-type epoxy resins and ortho-cresol novolak-type epoxy resins); one diglycidyl ether; epoxidized phenol-aralkyl resin; epoxidized 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 resin obtained by reaction of epichlorohydrin with epichlorohydrin; glycidylamine type epoxy resin obtained by reaction of polyamine (e.g. diaminodiphenylmethane and isocyanuric acid) with epichlorohydrin; linear aliphatic epoxy resins obtained by oxidation with (eg, peracetic acid); and cycloaliphatic epoxy resins. Epoxy resins may be used alone 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 epoxy resin preferably has a high purity and a low hydrolyzable chlorine content. 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 a 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 1.5% by mass to 20% by mass, more preferably 2.0% by mass to 15% by mass, and 3.0% by mass to It is more preferably 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 40% by mass to 55% by mass. % by mass is more preferred.

-Curing agent-
The sealing composition contains a curing agent. The type of curing agent is not particularly limited, and known curing agents 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) Novolak resins obtained by condensation or co-condensation of at least one kind of aldehyde compound (e.g., formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde) under an acidic catalyst; phenol-aralkyl resins; biphenyl-aralkyl resins; and naphthol-aralkyl resins; One type of curing agent may be used alone, or two or more types may be used in combination. Among them, the curing agent is preferably a phenol-aralkyl resin from the viewpoint of improving reflow resistance. Curing agents may be used alone or in combination of two or more.

The curing agent is blended so that the equivalent of the functional group (for example, phenolic hydroxyl group in the case of novolak resin) of the curing agent is 0.5 to 1.5 equivalents with respect to 1 equivalent of the epoxy group of the epoxy resin. It is particularly preferred that the curing agent is 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 the strength in a cured state.

An inorganic filler may be used individually by 1 type, or may use 2 or more types together.
Examples of the combined use of two or more inorganic fillers include the use of two or more inorganic fillers having different components, average particle sizes, shapes, and the like.
The shape of the inorganic filler is not particularly limited, and examples thereof include powdery, spherical, fibrous and the like. A spherical shape is preferable from the viewpoint of fluidity during molding of the sealing composition and mold wear resistance.

The average circularity of the inorganic filler is preferably 0.80 or more, more preferably 0.85 or more, still more preferably 0.90 or more, and particularly preferably 0.93 or more. preferable. Moreover, the average circularity of the inorganic filler may be 1.0 or less.
The circularity of an inorganic filler is the circumference 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, and the circumference measured from the projected image of the inorganic filler. It is a numerical value obtained by dividing by the length (the length of the contour line), and is obtained by the following formula. The degree of circularity is 1.00 for a perfect circle.
Circularity = (perimeter of equivalent circle)/(perimeter of particle cross-sectional image)
Specifically, the average circularity is obtained by observing an image magnified 1000 times with a scanning electron microscope, arbitrarily selecting 10 inorganic fillers, and measuring the circularity of each inorganic filler by the above method. and calculated as the arithmetic mean value. The degree of 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 kinds of inorganic fillers are used in combination, the average circularity of the inorganic fillers means a value of a mixture of two or more kinds of inorganic fillers.

The inorganic filler is not particularly limited as long as it has at least three peaks in the particle size distribution and contains alumina with a particle size of 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, and zirconia. be done. Furthermore, examples of inorganic fillers having a flame retardant effect include aluminum hydroxide and zinc borate. Among these, alumina is preferable 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 even more preferably 60% by mass to 90% by mass. .
As the inorganic filler, alumina and silica may be used together. When alumina and silica are used together as inorganic fillers, the proportion of alumina in the inorganic filler is preferably 80% by mass to 95% by mass, and the proportion of silica is preferably 5% by mass to 20% by mass. More preferably, the proportion of silica is 82% to 92% by mass, the proportion of silica is 8% to 18% by mass, the proportion of alumina is 85% to 90% by mass, and the proportion of silica is 10% by mass. More preferably, it is in the range of 15% by mass to 15% by mass.

The particle size distribution of the inorganic filler has at least three peaks, preferably three peaks. The position of the peak in the particle size distribution of the inorganic filler is not particularly limited. It is more preferred to have peaks in the range 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 obtained by the following method.
Add the inorganic filler to be measured to the solvent (pure water) within the range of 0.02% by mass to 0.08% by mass, vibrate with a 110W bath-type ultrasonic cleaner for 1 minute to 10 minutes, Distribute the filler. About 40 mL of the dispersion liquid is injected into the measurement cell and measured at 25°C. The measuring device measures the volume-based particle size distribution with a laser diffraction/scattering particle size distribution measuring device (for example, Horiba, Ltd., LA920 (trade name)). Note that the refractive index of alumina is used as the refractive index. Even when the inorganic filler is a mixture of alumina and an inorganic filler other than alumina, the refractive index of alumina shall be used as the refractive index.

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% by volume to 40% by volume, more preferably 10% by volume to 35% by volume, and 15% by volume. % to 30% by volume is more preferred.
The ratio of alumina to the inorganic particles having a particle diameter 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. By determining the volume-based ratio of alumina to 50 inorganic particles of 1 μm or less, it is possible to obtain the ratio of alumina to the inorganic particles of 1 μm or less in particle size contained in the inorganic filler. 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% to 60% by volume, more preferably 25% to 55% by volume, and 30% by volume. % to 50% by volume is more preferred.
The ratio of alumina to the inorganic particles having a particle diameter of 10 μm or more contained in the inorganic filler can be obtained in the same manner as the ratio of alumina to the inorganic particles having a particle diameter of 1 μm or less contained in the inorganic filler.

The amount of the inorganic filler to be blended is in the range of 75% by mass to 97% by mass with respect to the entire encapsulating composition from the viewpoint of hygroscopicity, reduction of linear expansion coefficient, improvement of strength and resistance to soldering heat. Preferably, it is more preferably in the range of 80% by mass to 95% by mass.

In order for the inorganic filler to exhibit a particle size distribution having at least three peaks, for example, a method of blending three types of inorganic fillers with different average particle diameters can be mentioned, but it is not limited to this. For example, an inorganic filler with an average particle size of 0.3 μm to 0.7 μm, an inorganic filler with an average particle size of 7 μm to 20 μm, and an inorganic filler with 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, even more preferably 6 μm to 20 μm.
The average particle size of the inorganic filler is determined 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, and using a laser diffraction/scattering particle size distribution measuring device (for example, Horiba Co., Ltd. In the volume-based particle size distribution measured by Seisakusho LA920 (trade name)), it is determined as the particle diameter (D50%) when the accumulation from the small diameter side is 50%.

(Curing accelerator)
The sealing composition may further contain a curing accelerator. The type of curing accelerator is not particularly limited, and known curing accelerators 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- Cycloamidine compounds such as diaza-bicyclo[5.4.0]undecene-7; cycloamidine compounds such as maleic anhydride, 1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, and 2,3-dimethyl 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; Compounds having intramolecular polarization obtained by adding compounds having 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; imidazole compounds such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, derivatives of imidazole compounds; tributylphosphine, methyldiphenylphosphine, triphenylphosphine, tris(4- organic phosphine compounds such as methylphenyl)phosphine, diphenylphosphine, and phenylphosphine; intramolecular polarization obtained by adding a compound having a π bond such as maleic anhydride, the above quinone compound, diazophenylmethane, and phenolic resin to an organic phosphine compound; Phosphorus compounds having; Tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate, triphenylphosphine tetraphenylborate, 2-ethyl-4-methylimidazole tetraphenylborate, N-methylmorpholine tetraphenylborate, derivatives of tetraphenylboron salts adducts of phosphine compounds such as triphenylphosphonium-triphenylborane, N-methylmorpholine tetraphenylphosphonium-tetraphenylborate, and tetraphenylboron salts; A hardening accelerator may be used individually by 1 type, or may use 2 or more types together.

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

(Ion trap agent)
The sealing 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 an ion trapping agent that is commonly used in sealing materials used for manufacturing semiconductor devices. mentioned. A compound represented by the following general formula (II-1) or the following general formula (II-2) may be used as the ion trapping agent.

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

In addition, ion trapping agents other than those described above include hydrated oxides of elements selected from magnesium, aluminum, titanium, zirconium, antimony, and the like.
An ion trap agent may be used individually by 1 type, or may use 2 or more types together.

When the sealing composition contains an ion trapping agent, the content of the ion trapping agent is 1 part by mass with respect to 100 parts by mass of the epoxy resin in the sealing composition, from the viewpoint of achieving sufficient moisture resistance reliability. It is preferable that it is above. From the viewpoint of sufficiently exhibiting the effects of other components, the content of the ion trapping agent is preferably 15 parts by mass or less with respect to 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 the inorganic filler.

(coupling agent)
The sealing composition may further contain a coupling agent. The type of coupling agent is not particularly limited, and known coupling agents can be used. Coupling agents include, for example, silane coupling agents and titanium coupling agents. A coupling agent may be used individually by 1 type, or may use 2 or more types together.

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-aminopropyltrimethoxysilane, γ-(β-aminoethyl)aminopropyldimethoxymethylsilane, N-(trimethoxysilylpropyl)ethylenediamine, N-(dimethoxymethylsilylisopropyl)ethylenediamine, methyltrimethoxysilane, methyltriethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilane, γ-anilinopropyltrimethoxysilane silanes, vinyltrimethoxysilane and γ-mercaptopropylmethyldimethoxysilane.

Titanium coupling agents include, for example, isopropyl triisostearoyl titanate, isopropyl tris(dioctylpyrophosphate) titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, tetraoctylbis(ditridecylphosphite) titanate, tetra( 2,2-diallyloxymethyl-1-butyl)bis(ditridecylphosphite)titanate, bis(dioctylpyrophosphate)oxyacetate titanate, bis(dioctylpyrophosphate)ethylene titanate, isopropyltrioctanoyltitanate, isopropyldimethacryl iso Stearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctylphosphate) titanate, isopropyltricumylphenyl titanate and tetraisopropyl bis(dioctylphosphite) titanate.

When the sealing composition contains a coupling agent, the content of the coupling agent is preferably 3% by mass or less with respect to the entire sealing composition. .1% by mass or more is preferable.

(Release agent)
The sealing composition may further contain a release agent. The type of release agent is not particularly limited, and known release agents can be used. Specific examples include higher fatty acids, higher fatty acid esters, carnauba wax, and polyethylene waxes. The release agent may be used alone or in combination of two or more.
When the encapsulating composition contains a release agent, the content of the release agent is preferably 10% by mass or less with respect to 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.

(Colorant and modifier)
The encapsulating composition may contain a colorant (eg, carbon black). The sealing composition may also contain modifiers such as silicones and silicone rubbers. The colorant and the modifier may be used singly or in combination of two or more.

When conductive particles such as carbon black are used as the colorant, the conductive particles preferably contain 1% by mass or less of particles having a particle diameter of 10 μm or more.
When the encapsulating composition contains conductive particles, the content of the conductive particles is preferably 4% by mass or less with respect to the total amount of the epoxy resin and the curing agent.

<Method for preparing sealing composition>
A method for producing the sealing composition is not particularly limited, and a known method can be used. For example, it can be produced by sufficiently mixing a mixture of raw materials in a predetermined amount with a mixer or the like, kneading with a hot roll, an extruder or the like, and subjecting the mixture to cooling, pulverization, or the like. The state of the sealing composition is not particularly limited, and may be powder, solid, liquid, or the like.

<Semiconductor device>
A semiconductor device of the present disclosure includes a semiconductor element and a cured product of the sealing composition of the present disclosure obtained by sealing the semiconductor element.

A method for sealing a semiconductor element using a sealing composition is not particularly limited, and a known method can be applied. For example, a transfer molding method is generally used, but a compression molding method, an injection molding method, or the like may also be used.

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

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

(Examples 1 to 11 and Comparative Examples 1 and 2)
After pre-mixing (dry blending) the materials having the formulations shown in Tables 1 to 3, they were kneaded for about 15 minutes with a twin-screw roll (roll surface temperature: about 80°C), cooled and pulverized to obtain a powdery sealing composition. manufactured.

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

(Epoxy resin)
・ Epoxy resin 1: biphenyl type epoxy resin, epoxy equivalent: 186 g / eq
・ Epoxy resin 2: polyfunctional epoxy resin, epoxy equivalent: 167 g / eq
・ Epoxy resin 3: bisphenol type crystalline epoxy resin, epoxy equivalent: 192 g / eq
・ Epoxy resin 4: bis F type epoxy resin, epoxy equivalent: 159 g / eq

(curing agent)
Curing agent 1: polyfunctional phenolic resin, triphenylmethane-type phenolic resin with a hydroxyl equivalent of 102 g/eq Curing agent 2: polyfunctional phenolic resin, a biphenyl aralkyl resin with a hydroxyl equivalent of 205 g/eq Curing agent 3: phenol・ Aralkyl resin, hydroxyl equivalent: 170 g / eq

・Curing accelerator: Phosphorus-based curing accelerator ・Coupling agent: Epoxysilane (γ-glycidoxypropyltrimethoxysilane)
・Releasing agent: Montan acid ester ・Coloring agent: Carbon black ・Ion trapping agent: Hydrotalcite ・Modifying agent: 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 peak positions in the particle size distribution of the inorganic fillers of Examples 1 to 11 are as follows,
It had 3 peaks. Further, all of the sealing compositions according to Examples 1 to 11 contained alumina having a particle size of 1 μm or less. In addition, the average particle size of the whole inorganic filler is 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 positions of peaks in the particle size distribution of the inorganic filler of Comparative Example 1 were as follows, and had two peaks. In addition, the sealing composition according to Comparative Example 1 contained alumina with a particle size of 1 μm or less. In addition, the average particle size of the whole inorganic filler is shown below.
Comparative Example 1: 1.5 μm and 10 μm (average particle size: 11.3 μm)
Moreover, the positions of the peaks in the particle size distribution of the inorganic filler of Comparative Example 2 are as follows, and had three peaks. Also, the sealing composition according to Comparative Example 2 did not contain alumina having a particle size of 1 μm or less. In addition, the average particle size of the whole inorganic filler is shown below.
Comparative Example 2: 0.5 μm, 10 μm and 50 μm (average particle size: 6.5 μm)

<Evaluation of liquidity>
Fluidity evaluation of the sealing composition was performed by a spiral flow test.
Specifically, the sealing composition was molded using a spiral flow measurement mold conforming to EMMI-1-66, and the flow distance (cm) of the molding of the sealing composition was measured. Molding of the encapsulating composition was performed using a transfer molding machine under conditions of a mold temperature of 180° C., a molding pressure of 6.9 MPa, and a curing time of 120 seconds.
In addition, the fluidity was defined as A when 160 cm or more, B when 150 cm or more and less than 160 cm, and C when less than 150 cm.

<Evaluation of thermal conductivity>
Evaluation of the thermal conductivity of the encapsulating composition was performed by the following method.
Specifically, using the prepared encapsulating composition, transfer molding was performed under conditions of a mold temperature of 180° C., a molding pressure of 7 MPa, and a curing time of 300 seconds to obtain a cured product in the shape of a mold. The density of the resulting cured product measured by the 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 (LFA467, NETZSCH). The thermal conductivity (W/(m·K)) was calculated from the product of the thermal diffusivity measured above, the density measured by the Archimedes method, and the specific heat measured by DSC (differential calorimeter).
In addition, the thermal conductivity was rated A when it was 2.5 W/(m·K) or more, and rated B when it was less than 2.5 W/(m·K).

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 amount of inorganic filler Since the particle size distribution does not have three peaks, the fluidity is extremely lowered and the thermal conductivity is lowered.
Further, Comparative Example 2, in which the inorganic filler does not contain alumina having a particle diameter of 1 μm or less, corresponds to Examples 1, 5, 6, and 8, which have a particularly large amount of alumina having a particle diameter of 1 μm or less in the inorganic filler. Compared to 10 and 11, the fluidity was equal or decreased and the thermal conductivity was decreased.

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 technical standards mentioned herein are to the same extent as if each individual publication, patent application and technical standard were specifically and individually noted to be incorporated by reference. incorporated herein by reference.

Claims (4)

containing 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 peaks in the range of 0.3 μm to 0.7 μm, the range of 9 μm to 20 μm and the range of 40 μm to 70 μm,
The sealing composition , wherein the proportion of alumina in the inorganic filler is 60% by mass to 95% by mass . 2. The sealing composition according to claim 1 , wherein the proportion of alumina in inorganic particles having a particle diameter of 1 μm or less contained in said inorganic filler is 1% by volume to 40% by volume. 3. The sealing composition according to claim 1 , 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 3 , obtained by sealing the semiconductor element.