JP7735724B2 - Thermosetting resin composition and semiconductor device - Google Patents

Description

This disclosure relates to a thermosetting resin composition and a semiconductor device.

In recent years, as electronic devices have become smaller, lighter, and more powerful, packaging density has increased. As a result, the mainstream of electronic component devices is shifting from traditional pin-insertion packages to surface-mount packages.

Surface-mount packages differ from conventional pin-insertion packages in their mounting method. Specifically, when attaching pins to a wiring board, conventional pin-insertion packages require soldering from the backside of the board after the pins are inserted into the board, preventing the package from being directly exposed to high temperatures. However, with surface-mount packages, the entire electronic component device is processed using a solder bath, reflow equipment, or the like, so the package is directly exposed to soldering temperatures (reflow temperatures). As a result, if the package absorbs moisture, the moisture rapidly expands during soldering. The resulting vapor pressure acts as peel stress, causing peeling between the insert (e.g., semiconductor element, lead frame) and the cured encapsulant (made of a thermosetting resin composition) that encapsulates the insert. This can lead to package cracks, poor electrical characteristics, and other problems. Therefore, there is a need for an encapsulant and its cured product that exhibits excellent adhesion to the insert and, ultimately, excellent solder heat resistance (reflow resistance).

To meet the above requirements, the use of silane coupling agents as modifiers for inorganic fillers contained in sealing materials has been investigated. Specifically, the use of epoxy group-containing silane coupling agents or amino group-containing silane coupling agents (see, for example, Patent Document 1), sulfur atom-containing silane coupling agents (see, for example, Patent Document 2), etc. has been investigated.

Furthermore, as an epoxy resin composition with excellent reflow resistance, an epoxy resin composition containing, as essential components, (A) an epoxy resin, (B) a phenolic resin, (C) a curing accelerator, (D) a phosphazene compound, (E) silica, and (F) at least one silane coupling agent selected from the group consisting of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidylpropyltriethoxysilane, and γ-glycidylpropyltrimethoxysilane has been disclosed (see, for example, Patent Document 3). Patent Document 3 uses silica that has been surface-treated with a silane coupling agent. The content of the surface-treated silica in the total epoxy resin composition is 85% to 93% by mass.

Japanese Patent Application Publication No. 11-147939 Japanese Patent Application Laid-Open No. 2000-103940 Japanese Patent Application Laid-Open No. 2004-67774

However, even with the sealing materials made of the epoxy resin compositions described in Patent Documents 1 and 2, the current situation is that they are still unable to provide practically sufficient reflow resistance.
On the other hand, the epoxy resin composition described in Patent Document 3 has a high content of surface-treated silica, which may deteriorate the flowability of the epoxy resin composition and easily cause unfilled areas, which tends to deteriorate reflow resistance.
The present disclosure has been made in view of the above-described conventional circumstances, and has an object to provide a thermosetting resin composition having excellent reflow resistance and a semiconductor device using this thermosetting resin composition.

Specific means for achieving the above object are as follows.
<1> A composition containing a thermosetting resin, a curing agent, and an inorganic filler,
the inorganic filler includes an inorganic filler that has been surface-treated with a coupling agent containing a primary amino group,
A thermosetting resin composition, wherein the content of the inorganic filler surface-treated with the coupling agent containing a primary amino group is 20% by mass to 60% by mass relative to the entire thermosetting resin composition.
<2> The thermosetting resin composition according to <1>, wherein the proportion of the inorganic filler surface-treated with the coupling agent containing a primary amino group in the entire inorganic filler is 75 mass % or less.
<3> The thermosetting resin composition according to <1> or <2>, wherein the amount of the coupling agent treatment of the inorganic filler that has been surface-treated with the coupling agent containing a primary amino group is 0.1 parts by mass to 5 parts by mass per 100 parts by mass of the inorganic filler before being surface-treated with the coupling agent containing a primary amino group.
<4> The thermosetting resin composition according to any one of <1> to <3>, wherein the coupling agent is an aminoalkyltrialkoxysilane.
<5> The thermosetting resin composition according to any one of <1> to <4>, wherein the inorganic filler surface-treated with the coupling agent containing a primary amino group has an angle of repose of 50° to 60°.
<6> The thermosetting resin composition according to any one of <1> to <5>, wherein the inorganic filler surface-treated with the coupling agent containing a primary amino group has a bulk density of 1.15 g/cm ³ to 1.40 g/cm ³ .
<7> A semiconductor device comprising: a semiconductor element; and a cured product of the thermosetting resin composition according to any one of <1> to <6>, which encapsulates the semiconductor element.
<8> The semiconductor device according to <7>, which is a surface mount type.
<9> The semiconductor device according to <7> or <8>, wherein both surfaces of the semiconductor element are in contact with the cured product directly or via a metal substrate.

This disclosure provides a thermosetting resin composition with excellent reflow resistance and a semiconductor device using this thermosetting resin composition.

Embodiments of the present disclosure are described in detail below. However, the present disclosure is not limited to the following embodiments. In the following embodiments, components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, and do not limit the present disclosure.

In the present disclosure, the term "process" includes not only a process that is independent of other processes, but also a process that cannot be clearly distinguished from other processes as long as the purpose of the process is achieved.
In the present disclosure, 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 stages in this disclosure, 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. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.
In the present disclosure, each component may contain multiple substances corresponding to the component. 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, the particles corresponding to each component may contain multiple types of particles. 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.

<Thermosetting resin composition>
The thermosetting resin composition of the present disclosure contains a thermosetting resin, a curing agent, and an inorganic filler, the inorganic filler being surface-treated with a coupling agent containing a primary amino group, and the content of the inorganic filler surface-treated with the coupling agent containing a primary amino group is 20% by mass to 60% by mass. Hereinafter, the "inorganic filler surface-treated with a coupling agent containing a primary amino group" may be referred to as a specific inorganic filler.
The reason why the thermosetting resin composition of the present disclosure has excellent reflow resistance is not clear, but is presumed to be as follows.
When the content of the specific inorganic filler is 20% by mass or more, the adhesion of the specific inorganic filler to inserts such as resins, semiconductor elements, and lead frames tends to be improved. On the other hand, when the content of the specific inorganic filler is 60% by mass or less, the reaction between the primary amino groups present on the surface of the specific inorganic filler and thermosetting resins such as epoxy resins is suppressed, and the occurrence of unfilled areas due to deterioration of the fluidity of the thermosetting resin composition tends to be suppressed. From the above, it is presumed that a thermosetting resin composition with excellent reflow resistance can be obtained by setting the content of the specific inorganic filler to 20% by mass to 60% by mass.

The thermosetting resin composition of the present disclosure contains a thermosetting resin, a curing agent, and an inorganic filler, and may contain other components as needed.
Each component contained in the thermosetting resin composition of the present disclosure will be described in detail below.

(thermosetting resin)
The thermosetting resin composition contains a thermosetting resin.
The type of thermosetting resin is not particularly limited, and examples thereof include epoxy resins, phenolic resins, thiol resins, urea resins, melamine resins, urethane resins, silicone resins, maleimide resins, and unsaturated polyester resins. In the present disclosure, "thermosetting resins" include those that exhibit both thermoplastic and thermosetting properties, such as acrylic resins containing epoxy groups. Thermosetting resins may be solid or liquid at room temperature and normal pressure (e.g., 25°C and atmospheric pressure), and are preferably solid. Thermosetting resins may be used alone or in combination of two or more.

The thermosetting resin preferably includes an epoxy resin.
The type of epoxy resin is not particularly limited as long as it has two or more epoxy groups in one molecule.
Specifically, novolac epoxy resins (phenol novolac epoxy resins, orthocresol novolac epoxy resins, etc.) are obtained by epoxidizing novolac resins obtained by condensing or co-condensing, under an acid catalyst, at least one phenolic compound selected from the group consisting of phenolic compounds such as phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, etc., and naphthol compounds such as α-naphthol, β-naphthol, dihydroxynaphthalene, etc., with an aliphatic aldehyde compound such as formaldehyde, acetaldehyde, propionaldehyde, etc.; triphenylmethane epoxy resins are obtained by epoxidizing triphenylmethane phenolic resins obtained by condensing or co-condensing, under an acid catalyst, the above-mentioned phenolic compounds with aromatic aldehyde compounds such as benzaldehyde, salicylaldehyde, etc. copolymerized epoxy resins obtained by epoxidizing novolak resins obtained by co-condensing the above-mentioned phenolic compounds and naphthol compounds with aldehyde compounds in the presence of an acid catalyst; diphenylmethane-type epoxy resins which are diglycidyl ethers of bisphenol A, bisphenol F, etc.; biphenyl-type epoxy resins which are diglycidyl ethers of alkyl-substituted or unsubstituted biphenols; stilbene-type epoxy resins which are diglycidyl ethers of stilbene-based phenolic compounds; sulfur-containing epoxy resins which are diglycidyl ethers of bisphenol S, etc.; epoxy resins which are glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol; and glycidyl ester-type epoxy resins which are glycidyl esters of polycarboxylic acids such as phthalic acid, isophthalic acid, and tetrahydrophthalic acid. Glycidylamine-type epoxy resins in which active hydrogen atoms bonded to nitrogen atoms of aniline, diaminodiphenylmethane, isocyanuric acid, etc. are substituted with glycidyl groups; dicyclopentadiene-type epoxy resins in which co-condensation resins of dicyclopentadiene and phenol compounds are epoxidized; alicyclic epoxy resins such as vinylcyclohexene diepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and 2-(3,4-epoxy)cyclohexyl-5,5-spiro(3,4-epoxy)cyclohexane-m-dioxane in which intramolecular olefin bonds are epoxidized; paraxylylene-modified epoxy resins which are glycidyl ethers of paraxylylene-modified phenolic resins; metaxylylene-modified epoxy resins which are glycidyl ethers of metaxylylene-modified phenolic resins; terpene-modified phenols Examples of the epoxy resin include terpene-modified epoxy resins, which are glycidyl ethers of dicyclopentadiene-modified phenolic resins; dicyclopentadiene-modified epoxy resins, which are glycidyl ethers of dicyclopentadiene-modified phenolic resins; cyclopentadiene-modified epoxy resins, which are glycidyl ethers of cyclopentadiene-modified phenolic resins; polycyclic aromatic ring-modified epoxy resins, which are glycidyl ethers of polycyclic aromatic ring-modified phenolic resins; naphthalene-type epoxy resins, which are glycidyl ethers of naphthalene ring-containing phenolic resins; halogenated phenol novolac-type epoxy resins; hydroquinone-type epoxy resins; trimethylolpropane-type epoxy resins; linear aliphatic epoxy resins obtained by oxidizing olefin bonds with peracids such as peracetic acid; and aralkyl-type epoxy resins obtained by epoxidizing aralkyl-type phenolic resins such as phenol aralkyl resins and naphthol aralkyl resins. Further examples of the epoxy resin include epoxidized silicone resins and aminophenol-type epoxy resins, which are glycidyl ethers of aminophenols. These epoxy resins may be used alone or in combination of two or more.

Among the above epoxy resins, from the viewpoint of the balance between heat resistance and fluidity, epoxy resins selected from the group consisting of biphenyl-type epoxy resins, stilbene-type epoxy resins, diphenylmethane-type epoxy resins, sulfur-containing epoxy resins, novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, triphenylmethane-type epoxy resins, copolymer-type epoxy resins, and aralkyl-type epoxy resins (these are referred to as "specific epoxy resins"). The specific epoxy resins may be used alone or in combination of two or more.

When the epoxy resin contains a specific epoxy resin, in order to maximize the performance of the specific epoxy resin, its content is preferably 30% by mass or more of the total epoxy resin, and more preferably 50% by mass or more.

Among the specific epoxy resins, from the viewpoint of fluidity, biphenyl-type epoxy resins, stilbene-type epoxy resins, diphenylmethane-type epoxy resins, and sulfur-atom-containing epoxy resins are more preferred, and from the viewpoint of heat resistance, dicyclopentadiene-type epoxy resins, triphenylmethane-type epoxy resins, and aralkyl-type epoxy resins are preferred.
Specific examples of preferred epoxy resins are shown below.

The biphenyl-type epoxy resin is not particularly limited as long as it is an epoxy resin having a biphenyl skeleton. For example, an epoxy resin represented by the following general formula (II) is preferred. Among the epoxy resins represented by the following general formula (II), commercially available products include YX-4000H (trade name, Mitsubishi Chemical Corporation), in which methyl groups are present at the 3,3', 5, and 5' positions (assuming that the oxygen atoms ^{in R8} are at the 4 and 4' positions) and the remaining ^R8 are hydrogen atoms; 4,4'-bis(2,3-epoxypropoxy)biphenyl, in which all ^R8 are hydrogen atoms; and YL-6121H (trade name, Mitsubishi Chemical Corporation), which is a mixture of a case in which all ^R8 are hydrogen atoms and a case in which methyl groups are present at the 3,3', 5, and 5' positions (assuming that the oxygen atoms ⁱⁿ R8 are at the 4 and 4' positions) and the remaining R8 are hydrogen atoms.

In formula (II), ^R8 represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aromatic group having 6 to 18 carbon atoms, and may be the same or different from each other. n represents an average value of 0 to 10.

The stilbene-type epoxy resin is not particularly limited as long as it is an epoxy resin having a stilbene skeleton. For example, an epoxy resin represented by the following general formula (III) is preferred. Among the epoxy resins represented by the following general formula (III), examples include a resin in which methyl groups are present at the 3, 3', 5, and 5' positions, where the oxygen atom-substituted positions of ^R9 are the 4 and ⁴ ' positions, and the other ^R9s are hydrogen atoms, and all ^R10s are hydrogen atoms, and a mixture of a resin in which three of the 3, 3', 5, and 5' positions of ^R9 are methyl groups and one is a t-butyl group, the other R9s are hydrogen atoms, and all ^R10s are hydrogen atoms.

In formula (III), R ⁹ and R ¹⁰ represent a hydrogen atom or a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different. n is an average value and represents a number from 0 to 10.

The diphenylmethane type epoxy resin is not particularly limited as long as it is an epoxy resin having a diphenylmethane skeleton. For example, an epoxy resin represented by the following general formula (IV) is preferred. Among the epoxy resins represented by the following general formula (IV), commercially available products include YSLV-80XY (Nippon Steel Chemical & Material Co., Ltd., trade name), in which all of R ¹¹ are hydrogen atoms, and R ¹² has methyl groups at the 3, 3', 5, and 5' positions, assuming that the oxygen atom substitution positions are the 4 and 4' positions, and the other R ¹² are hydrogen atoms.

In formula (IV), R ¹¹ and R ¹² represent a hydrogen atom or a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different. n is an average value and represents a number from 0 to 10.

The sulfur-containing epoxy resin is not particularly limited as long as it is an epoxy resin containing a sulfur atom. For example, an epoxy resin represented by the following general formula (V) can be mentioned. Among the epoxy resins represented by the following general formula (V), YSLV-120TE (trade name, Nippon Steel Chemical & Material Co., Ltd.) is commercially available, in which, assuming that the oxygen atom-substituted positions of R ¹³ are the 4 and 4' positions, t-butyl groups are at the 3 and 3' positions and methyl groups are at the 6 and 6' positions, and the other R ¹³ are hydrogen atoms.

In formula (V), R ¹³ represents a hydrogen atom or a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different from each other. n represents an average value of 0 to 10.

The novolac epoxy resin is not particularly limited as long as it is an epoxy resin obtained by epoxidizing a novolac phenolic resin. For example, an epoxy resin obtained by epoxidizing a novolac phenolic resin such as a phenol novolac resin, a cresol novolac resin, or a naphthol novolac resin using a method such as glycidyl etherification is preferred, and an epoxy resin represented by the following general formula (VI) is more preferred. Among the epoxy resins represented by the following general formula (VI), commercially available products include ESCN-190 and ESCN-195 (trade names, Sumitomo Chemical Co., Ltd.), in which all R ^14s are hydrogen atoms, R ^15s are methyl groups, and i=1; N-770 and N-775 (trade names, DIC Corporation), in which all ^{R 14s} are hydrogen atoms and i=0; YDAN-1000-10C (trade name, Nippon Steel Chemical & Material Co., Ltd.), a styrene-modified phenol novolac epoxy resin having a portion where all R ^14s are hydrogen atoms and i=0 and a portion where i=1 and R ¹⁵ is —CH(CH ₃ )—Ph; and a benzyl-modified cresol novolac epoxy resin having a portion where all R ^14s are hydrogen atoms, i=1, and R ^15s are methyl groups and a portion where i=2 and one R 15 is a methyl group and one is a benzyl group.

In formula (VI), R ¹⁴ represents a hydrogen atom or a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different. ^{R 15} represents a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different. Each i independently represents an integer of 0 to 3. n is an average value and represents a number of 0 to 10.

The dicyclopentadiene-type epoxy resin is not particularly limited as long as it is an epoxy resin obtained by epoxidizing a compound having a dicyclopentadiene skeleton as a raw material. For example, an epoxy resin represented by the following general formula (VII) is preferred. Among the epoxy resins represented by the following general formula (VII), HP-7200 (trade name, DIC Corporation), in which i = 0, is a commercially available product.

In formula (VII), R ¹⁶ represents a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different from each other. Each i independently represents an integer of 0 to 3. n is an average value and represents a number of 0 to 10.

The triphenylmethane-type epoxy resin is not particularly limited as long as it is an epoxy resin made from a compound having a triphenylmethane skeleton. For example, an epoxy resin obtained by glycidyl etherifying a triphenylmethane-type phenolic resin obtained from an aromatic aldehyde compound and a phenolic compound is preferred, and an epoxy resin represented by the following general formula (VIII) is more preferred. Among the epoxy resins represented by the following general formula (VIII), 1032H60 (trade name, Mitsubishi Chemical Corporation) and EPPN-502H (trade name, Nippon Kayaku Co., Ltd.), in which i is 0 and k is 0, are commercially available.

In formula (VIII), R ¹⁷ and R ¹⁸ represent a monovalent organic group having 1 to 18 carbon atoms and may be the same or different. Each i independently represents an integer of 0 to 3, and each k independently represents an integer of 0 to 4. n is an average value and represents a number of 0 to 10.

The copolymerized epoxy resin obtained by epoxidizing a novolac resin obtained from a naphthol compound, a phenol compound, and an aldehyde compound is not particularly limited as long as it is an epoxy resin made from a compound having a naphthol skeleton and a compound having a phenol skeleton as raw materials. For example, an epoxy resin obtained by glycidyl etherifying a novolac phenolic resin using a compound having a naphthol skeleton and a compound having a phenol skeleton is preferred, and an epoxy resin represented by the following general formula (IX) is more preferred. Among the epoxy resins represented by the following general formula (IX), NC-7300 (trade name, Nippon Kayaku Co., Ltd.), in which ^R21 is a methyl group, i is 1, j is 0, and k is 0, is commercially available.

In formula (IX), R ¹⁹ to R ²¹ represent monovalent organic groups having 1 to 18 carbon atoms, and may be the same or different. Each i is independently an integer of 0 to 3, each j is independently an integer of 0 to 2, and each k is independently an integer of 0 to 4. Each l and m is an average value and a number of 0 to 10, and (l + m) is a number of 0 to 10. The terminal of the epoxy resin represented by formula (IX) is either formula (IX-1) or (IX-2) below. In formulas (IX-1) and (IX-2), the definitions of R ¹⁹ to R ²¹ , i, j, and k are the same as those of R ¹⁹ to R ²¹ , i, j, and k in formula (IX). n is 1 (when bonding via a methylene group) or 0 (when bonding not via a methylene group).

Examples of epoxy resins represented by the general formula (IX) include random copolymers containing l structural units and m structural units randomly, alternating copolymers containing them alternately, copolymers containing them regularly, and block copolymers containing them in block form. Any of these may be used alone, or two or more may be used in combination.

Another preferred copolymer epoxy resin is Epiclon HP-5000 (trade name, DIC Corporation), a methoxynaphthalene-cresol-formaldehyde co-condensation epoxy resin containing the following two structural units in a random, alternating, or block order. In the general formula below, n and m are each average values and are numbers from 0 to 10, and (n + m) is a number from 0 to 10; preferably, n and m are each average values and are numbers from 1 to 9, and (n + m) is a number from 2 to 10.

The aralkyl epoxy resin is not particularly limited, as long as it is an epoxy resin made from a phenolic resin synthesized from at least one selected from the group consisting of phenolic compounds such as phenol and cresol, and naphthol compounds such as naphthol and dimethylnaphthol, and dimethoxyparaxylene, bis(methoxymethyl)biphenyl, or a derivative thereof. For example, epoxy resins obtained by glycidyl etherifying a phenolic resin synthesized from at least one selected from the group consisting of phenolic compounds such as phenol and cresol, and naphthol compounds such as naphthol and dimethylnaphthol, and dimethoxyparaxylene, bis(methoxymethyl)biphenyl, or a derivative thereof are preferred, and epoxy resins represented by the following general formulas (X) and (XI) are more preferred.

Among the epoxy resins represented by the following general formula (X), commercially available products include NC-3000S (trade name, Nippon Kayaku Co., Ltd.) in which i is 0 and ^{R 38} is a hydrogen atom, and CER-3000 (trade name, Nippon Kayaku Co., Ltd.) in which an epoxy resin in which i is 0 and R 38 is a hydrogen atom and an epoxy resin in which all R ⁸ of general formula (II) are hydrogen atoms are mixed in a mass ratio of 80:20. Furthermore, among the epoxy resins represented by the following general formula (XI), commercially available products include ESN-175 (trade name, Nippon Steel Chemical & Material Co., Ltd.) in which l is 0, j is 0, and k is 0.

In formulas (X) and (XI), R ³⁸ represents a hydrogen atom or a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different. R ³⁷ and R ³⁹ to R ⁴¹ represent monovalent organic groups having 1 to 18 carbon atoms, and may be the same or different. Each i is independently an integer of 0 to 3, each j is independently an integer of 0 to 2, each k is independently an integer of 0 to 4, and each 1 is independently an integer of 0 to 4. Each n is an average value, and is independently a number of 0 to 10.

With respect to R ⁸ to R ²¹ and R ³⁷ to R ⁴¹ in the above general formulas (II) to (XI), "all of them may be the same or different" means, for example, that all of the 8 to 88 R ^8s in formula (II) may be the same or different. The other R ⁹ to R ²¹ and R ³⁷ to R ⁴¹ also mean that all of the respective numbers contained in the formula may be the same or different. Furthermore, R ⁸ to R ²¹ and R ³⁷ to R ⁴¹ may be the same or different. For example, all of the R ^9s and R ^10s may be the same or different.
In addition, the monovalent organic group having 1 to 18 carbon atoms in the general formulae (III) to (XI) is preferably an alkyl group or an aryl group.

In the above general formulas (II) to (XI), n is an average value, and each independently is preferably in the range of 0 to 10. If n is 10 or less, the melt viscosity of the resin component does not become too high, and the viscosity of the thermosetting resin composition during melt molding tends to decrease, which tends to suppress the occurrence of filling defects, deformation of bonding wires (gold wires connecting semiconductor elements to leads), etc. It is more preferable to set n in the range of 0 to 4.

Specific examples of preferred epoxy resins that can be used in thermosetting resin compositions have been explained above in accordance with the general formulas (II) to (XI). However, more specific preferred epoxy resins include 4,4'-bis(2,3-epoxypropoxy)-3,3',5,5'-tetramethylbiphenyl from the standpoint of heat resistance, and 4,4'-bis(2,3-epoxypropoxy)-biphenyl from the standpoint of moldability and heat resistance.

The epoxy equivalent of the epoxy resin is not particularly limited. From the perspective of balancing various properties such as moldability, heat resistance, and electrical reliability, the epoxy equivalent of the epoxy resin is preferably 60 g/eq to 1000 g/eq, and more preferably 80 g/eq to 500 g/eq.

The epoxy resin may be liquid or solid. When the epoxy resin is solid, the softening point or melting point of the epoxy resin is not particularly limited. From the viewpoints of moldability and heat resistance, it is preferably 40°C to 180°C, and from the viewpoint of handleability during preparation of the thermosetting resin composition, it is more preferably 50°C to 130°C.
In the present disclosure, the softening point refers to a value measured by the ring and ball method of JIS K 7234:1986.
In the present disclosure, the melting point refers to a value measured in accordance with the visual method of JIS K 0064:1992.

From the standpoints of strength, fluidity, heat resistance, moldability, etc., the content of epoxy resin in the thermosetting resin composition is preferably 0.5% to 60% by mass, and more preferably 2% to 50% by mass.

(hardening agent)
The thermosetting resin composition contains a curing agent.
The type of curing agent is not particularly limited, as long as it is a compound that undergoes a curing reaction with the thermosetting resin used in combination. For example, curing agents that can be used in combination with an epoxy resin include phenol-based curing agents, amine-based curing agents, acid anhydride-based curing agents, polymercaptan-based curing agents, polyaminoamide-based curing agents, isocyanate-based curing agents, and blocked isocyanate-based curing agents. The curing agent may be used alone or in combination of two or more. The curing agent may be solid or liquid at room temperature and normal pressure (e.g., 25°C, atmospheric pressure), and is preferably solid.
When the thermosetting resin is an epoxy resin, the curing agent is preferably a phenol-based curing agent or an amine-based curing agent from the viewpoint of heat resistance.
Examples of phenolic curing agents include phenolic resins and polyhydric phenolic compounds having two or more phenolic hydroxyl groups per molecule. Specific examples include polyhydric phenolic compounds such as resorcinol, catechol, bisphenol A, bisphenol F, and substituted or unsubstituted biphenols; novolac phenolic resins obtained by condensing or co-condensing at least one phenolic compound selected from the group consisting of phenolic compounds such as phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol, and naphthol compounds such as α-naphthol, β-naphthol, and dihydroxynaphthalene, with an aldehyde compound such as formaldehyde, acetaldehyde, or propionaldehyde, under an acidic catalyst; and phenolic resins synthesized from the above phenolic compounds and dimethoxyparaxylene, bis(methoxymethyl)biphenyl, or the like. Examples of suitable phenol curing agents include aralkyl phenolic resins such as aryl aralkyl resins and naphthol aralkyl resins; paraxylylene and/or metaxylylene-modified phenolic resins; melamine-modified phenolic resins; terpene-modified phenolic resins; dicyclopentadiene-type phenolic resins and dicyclopentadiene-type naphthol resins synthesized by copolymerization of the above-mentioned phenolic compounds with dicyclopentadiene; cyclopentadiene-modified phenolic resins; polycyclic aromatic ring-modified phenolic resins; biphenyl-type phenolic resins; triphenylmethane-type phenolic resins obtained by condensing or co-condensing the above-mentioned phenolic compounds with aromatic aldehyde compounds such as benzaldehyde and salicylaldehyde under an acidic catalyst; and phenolic resins obtained by copolymerizing two or more of these. Furthermore, examples of phenolic curing agents include monohydric phenolic compounds having one phenolic hydroxyl group per molecule. These phenolic curing agents may be used alone or in combination of two or more.

Among phenolic curing agents, from the viewpoint of heat resistance, at least one selected from the group consisting of aralkyl phenolic resins, dicyclopentadiene phenolic resins, triphenylmethane phenolic resins, copolymerized phenolic resins of triphenylmethane phenolic resins and aralkyl phenolic resins, and novolac phenolic resins (these are referred to as "specific phenolic curing agents"). The specific phenolic curing agents may be used alone or in combination of two or more.

The total proportion of the aralkyl phenolic resin and the melamine-modified phenolic resin in the entire phenolic curing agent is preferably 40% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, and even more preferably 80% by mass to 100% by mass.
The proportion of the aralkyl phenol resin in the entire phenol-based curing agent is preferably 40% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, and even more preferably 80% by mass to 100% by mass.
The total proportion of the melamine-modified phenolic resins in the entire phenolic curing agent is preferably 0% by mass to 15% by mass, more preferably 0% by mass to 10% by mass, and even more preferably 0% by mass to 5% by mass.

Melamine-modified phenolic resin may be obtained by mixing a phenolic compound such as phenol with melamine and formalin, followed by a heating reaction.

Examples of aralkyl phenolic resins include phenol aralkyl resins and naphthol aralkyl resins synthesized from phenolic compounds and dimethoxy-para-xylene, bis(methoxymethyl)biphenyl, etc. Aralkyl phenolic resins may also be copolymerized with other phenolic resins. Examples of copolymerized aralkyl phenolic resins include copolymerized phenolic resins of triphenylmethane phenolic resin and aralkyl phenolic resin, copolymerized phenolic resins of salicylaldehyde phenolic resin and aralkyl phenolic resin, and copolymerized phenolic resins of novolac phenolic resin and aralkyl phenolic resin.

The aralkyl phenolic resin is not particularly limited as long as it is a phenolic resin synthesized from at least one compound selected from the group consisting of phenol compounds and naphthol compounds, and dimethoxy-para-xylene, bis(methoxymethyl)biphenyl, or a derivative thereof. For example, phenolic resins represented by the following general formulas (XII) to (XIV) are preferred.

In formulas (XII) to (XIV), R ²³ represents a hydrogen atom or a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different. R ²² , R ²⁴ , R ²⁵ , and R ²⁸ represent a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different. ^{R 26} and R ²⁷ represent a hydroxyl group or a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different. Each i is independently an integer of 0 to 3, each j is independently an integer of 0 to 2, each k is independently an integer of 0 to 4, and each p is independently an integer of 0 to 4. Each n is an average value, and is independently a number of 0 to 10.

Among the phenolic resins represented by the general formula (XII) above, MEH-7851 (trade name, Meiwa Kasei Co., Ltd.), in which i is 0 and all of R ²³ are hydrogen atoms, is commercially available.

Among the phenolic resins represented by the general formula (XIII) above, XL-225, XLC (Mitsui Chemicals, Inc., trade name), MEH-7800 (Meiwa Chemical Industry Co., Ltd., trade name), etc., in which i is 0 and k is 0, are commercially available.

Among the phenolic resins represented by the general formula (XIV), SN-170 (trade name, Nippon Steel Chemical & Material Co., Ltd.), in which j is 0, k is 0, and p is 0, and SN-395 (trade name, Nippon Steel Chemical & Material Co., Ltd.), in which j is 0, k is 1, R ²⁷ is a hydroxyl group, and p is 0, are commercially available.

The dicyclopentadiene-type phenolic resin is not particularly limited as long as it is a phenolic resin obtained from a compound having a dicyclopentadiene skeleton. For example, a phenolic resin represented by the following general formula (XV) is preferred. Among the phenolic resins represented by the following general formula (XV), phenolic resins in which i is 0 are commercially available.

In formula (XV), R ²⁹ represents a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different from each other. Each i independently represents an integer of 0 to 3. n is an average value and represents a number of 0 to 10.

The triphenylmethane-type phenolic resin is not particularly limited as long as it is a phenolic resin obtained using an aromatic aldehyde compound as a raw material. For example, a phenolic resin represented by the following general formula (XVI) is preferred.

Among the phenolic resins represented by the following general formula (XVI), MEH-7500 (product name, Meiwa Kasei Co., Ltd.), in which i is 0 and k is 0, is commercially available.

In formula (XVI), R ³⁰ and R ³¹ represent a monovalent organic group having 1 to 18 carbon atoms and may be the same or different. Each i is independently an integer of 0 to 3, and each k is independently an integer of 0 to 4. n is an average value and is a number of 0 to 10.

The copolymerized phenolic resin of a triphenylmethane-type phenolic resin and an aralkyl-type phenolic resin is not particularly limited, as long as it is a copolymerized phenolic resin of an aralkyl-type phenolic resin and a phenolic resin obtained from a compound having a benzaldehyde skeleton as a raw material. For example, a phenolic resin represented by the following general formula (XVII) is preferred.

Among the phenolic resins represented by the following general formula (XVII), HE-510 (trade name, Air Water Chemical Inc.), in which i is 0, k is 0, and q is 0, is commercially available.

In formula (XVII), R ³² to R ³⁴ represent monovalent organic groups having 1 to 18 carbon atoms, and may be the same or different. Each i is independently an integer of 0 to 3, each k is independently an integer of 0 to 4, and each q is independently an integer of 0 to 5. Each l and m is an average value and independently a number of 0 to 11, provided that the sum of l and m is a number of 1 to 11.

There are no particular restrictions on the novolac phenolic resin, as long as it is a phenolic resin obtained by condensing or co-condensing at least one phenolic compound selected from the group consisting of phenol compounds and naphthol compounds with an aldehyde compound in the presence of an acidic catalyst. For example, a phenolic resin represented by the following general formula (XVIII) is preferred.

Among the phenolic resins represented by the following general formula (XVIII), Tamanol 758 and 759 (trade names, manufactured by Arakawa Chemical Industries, Ltd.) and H-4 (trade name, manufactured by Meiwa Chemical Industry Co., Ltd.), in which i is 0 and all of R ³⁵ are hydrogen atoms, are commercially available.

In formula (XVIII), R ³⁵ represents a hydrogen atom or a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different. R ³⁶ represents a monovalent organic group having 1 to 18 carbon atoms, and may be the same or different. Each i independently represents an integer of 0 to 3. n is an average value and represents a number of 0 to 10.

The phrase "each may be the same or different" used with respect to R ²² to R ³⁶ in the above general formulas (XII) to (XVIII) means, for example, that all of the i R ^22s in formula (XII) may be the same or different from one another. The same applies to the other R ²³ to R ³⁶ , with respect to the respective numbers contained in the formula, all may be the same or different from one another. Furthermore, R ²² to R ³⁶ may be the same or different from one another. For example, all of R ²² and R ²³ may be the same or different, and all of R ³⁰ and R ³¹ may be the same or different.

In the above general formulas (XII) to (XVIII), n is preferably in the range of 0 to 10. If it is 10 or less, the melt viscosity of the resin component will not be too high, and the viscosity of the thermosetting resin composition during melt molding will also be low, making it less likely that filling defects, deformation of bonding wires (gold wires connecting semiconductor elements to leads), etc. will occur. The average n per molecule is preferably set in the range of 0 to 4.

Examples of monohydric phenol compounds include "Tinuvin 405,""Tinuvin900,""Tinuvin99-2,""Tinuvin326,""Tinuvin384-2," and "Tinuvin 928" (all manufactured by BASF).
In one embodiment, the proportion of the monohydric phenol compound in the entire phenolic curing agent is preferably 5% by mass to 20% by mass, more preferably 10% by mass to 19% by mass, and even more preferably 12% by mass to 18% by mass. In another embodiment, the proportion may be 5% by mass or less, 2% by mass or less, 1% by mass or less, or 0% by mass.

Specific examples of amine-based curing agents include aliphatic amine compounds such as diethylenetriamine, triethylenetetramine, n-propylamine, 2-hydroxyethylaminopropylamine, cyclohexylamine, and 4,4'-diamino-dicyclohexylmethane; aromatic amine compounds such as diethyltoluenediamine, 3,3'-diethyl-4,4'-diaminodiphenylmethane, dimethylthiotoluenediamine, and 2-methylaniline; imidazole compounds such as imidazole, 2-methylimidazole, 2-ethylimidazole, and 2-isopropylimidazole; and imidazoline compounds such as imidazoline, 2-methylimidazoline, and 2-ethylimidazoline. Among these, aromatic amine compounds are preferred from the standpoint of storage stability, with diethyltoluenediamine, 3,3'-diethyl-4,4'-diaminodiphenylmethane, and dimethylthiotoluenediamine being more preferred.

The functional group equivalent of the curing agent (hydroxyl group equivalent in the case of a phenol-based curing agent, and active hydrogen equivalent in the case of an amine-based curing agent) is not particularly limited. From the viewpoint of the balance of various properties such as moldability, heat resistance, and electrical reliability, it is preferably 10 g/eq to 1000 g/eq, and more preferably 30 g/eq to 500 g/eq.
The hydroxyl equivalent weight in the case of a phenolic curing agent is a value calculated based on the hydroxyl value measured in accordance with JIS K0070:1992, and the active hydrogen equivalent weight in the case of an amine curing agent is a value calculated based on the amine value measured in accordance with JIS K7237:1995.

When the curing agent is solid, there are no particular restrictions on its softening point or melting point. From the standpoints of moldability and heat resistance, it is preferably 40°C to 180°C, and from the standpoint of handleability during production of the thermosetting resin composition, it is more preferably 50°C to 130°C.

When the thermosetting resin is an epoxy resin, there are no particular restrictions on the equivalent ratio of the epoxy resin to the curing agent (number of moles of epoxy groups in the resin / number of moles of active hydrogen in the curing agent), but from the perspective of keeping the unreacted amounts of each to a minimum, it is preferable that it be, for example, 0.7 to 1.3.

(Curing accelerator)
The thermosetting resin composition may contain a curing accelerator. The type of curing accelerator is not particularly limited and can be selected depending on the type of curable resin, the desired properties of the thermosetting resin composition, and the like.

From the viewpoint of curability and fluidity, it is preferable that the curing accelerator contains a phosphonium compound. Specific examples of phosphonium compounds include triphenylphosphine, diphenyl(p-tolyl)phosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, tris(alkyl/alkoxyphenyl)phosphine, tris(dialkylphenyl)phosphine, tris(trialkylphenyl)phosphine, tris(tetraalkylphenyl)phosphine, tris(dialkoxyphenyl)phosphine, tris(trialkoxyphenyl)phosphine, and tris(tetraalkoxyphenyl)phosphine. A compound having intramolecular polarization, which is formed by adding a tertiary phosphine such as sphines, trialkylphosphines, dialkylarylphosphines, or alkyldiarylphosphines to a compound having a π bond, such as maleic anhydride, 1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, or phenyl-1,4-benzoquinone, or a compound having a π bond, such as diazophenylmethane. compounds which react with tertiary phosphines; compounds which react with tertiary phosphines; 4-bromophenol, 3-bromophenol, 2-bromophenol, 4-chlorophenol, 3-chlorophenol, 2-chlorophenol, 4-iodophenol, 3-iodophenol, 2-iodophenol, 4-bromo-2-methylphenol, 4-bromo-3-methylphenol, 4-bromo-2,6-dimethylphenol, 4-bromo-3,5-dimethylphenol, 4-bromo-2,6-di-tert-butylphenol, 4-chloro-1-naphthol, 1-bromo-2-naphthol, Examples include compounds with intramolecular polarization obtained by reacting halogenated phenolic compounds such as 2-naphthol, 6-bromo-2-naphthol, and 4-bromo-4'-hydroxybiphenyl, followed by a dehydrohalogenation process; salts of tetra-substituted phosphonium compounds such as tetraphenylphosphonium and tetra-substituted borates such as tetra-p-tolylborate; salts of tetra-substituted phosphonium compounds and anions resulting from the removal of protons from phenolic compounds; and salts of tetra-substituted phosphonium compounds and anions resulting from the removal of protons from carboxylic acid compounds.

The above phosphonium compound preferably contains a compound represented by the following general formula (I-1) (hereinafter also referred to as a specific curing accelerator).

In formula (I-1), R ¹ to R ³ are each independently a hydrocarbon group having 1 to 18 carbon atoms, and two or more of R ¹ to R ³ may be bonded to each other to form a cyclic structure, and R ⁴ to R ⁷ are each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 18 carbon atoms, and two or more of R ⁴ to R ⁷ may be bonded to each other to form a cyclic structure.

The "hydrocarbon group having 1 to 18 carbon atoms" described as R ¹ to R ³ in general formula (I-1) includes an aliphatic hydrocarbon group having 1 to 18 carbon atoms and an aromatic hydrocarbon group having 6 to 18 carbon atoms.

From the standpoint of fluidity, the aliphatic hydrocarbon group having 1 to 18 carbon atoms preferably has 1 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, and even more preferably 4 to 6 carbon atoms.

The aliphatic hydrocarbon group having 1 to 18 carbon atoms may be a linear or branched aliphatic hydrocarbon group having 1 to 18 carbon atoms, or an alicyclic hydrocarbon group having 3 to 18 carbon atoms. From the perspective of ease of production, a linear or branched aliphatic hydrocarbon group is preferred.

Specific examples of linear or branched aliphatic hydrocarbon groups having 1 to 18 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, hexyl, octyl, decyl, and dodecyl, as well as allyl and vinyl groups. The linear or branched aliphatic hydrocarbon groups may or may not have a substituent. Examples of the substituent include alkoxy groups such as methoxy, ethoxy, n-butoxy, and t-butoxy; aryl groups such as phenyl and naphthyl; hydroxyl groups; amino groups; and halogen atoms. The linear or branched aliphatic hydrocarbon groups may have two or more substituents, which may be the same or different. When the linear or branched aliphatic hydrocarbon group has a substituent, the total number of carbon atoms contained in the aliphatic hydrocarbon group and the substituent is preferably 1 to 18. From the standpoint of curability, unsubstituted alkyl groups are preferred, unsubstituted alkyl groups having 1 to 8 carbon atoms are more preferred, and n-butyl, isobutyl, n-pentyl, n-hexyl, and n-octyl groups are even more preferred.

Specific examples of alicyclic hydrocarbon groups having 3 to 18 carbon atoms include cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl, and cycloalkenyl groups such as cyclopentenyl and cyclohexenyl. The alicyclic hydrocarbon group may or may not have a substituent. Examples of the substituent include alkyl groups such as methyl, ethyl, n-butyl, and t-butyl; alkoxy groups such as methoxy, ethoxy, n-butoxy, and t-butoxy; aryl groups such as phenyl and naphthyl; hydroxyl groups; amino groups; and halogen atoms. The alicyclic hydrocarbon group may have two or more substituents, and in such cases, the substituents may be the same or different. When the alicyclic hydrocarbon group has a substituent, the total number of carbon atoms contained in the alicyclic hydrocarbon group and the substituent is preferably 3 to 18. When the alicyclic hydrocarbon group has a substituent, the position of the substituent is not particularly limited. From the standpoint of curability, unsubstituted cycloalkyl groups are preferred, unsubstituted cycloalkyl groups having 4 to 10 carbon atoms are more preferred, and cyclohexyl groups, cyclopentyl groups, and cycloheptyl groups are even more preferred.

Aromatic hydrocarbon groups having 6 to 18 carbon atoms preferably have 6 to 14 carbon atoms, and more preferably 6 to 10 carbon atoms. The aromatic hydrocarbon group may or may not have a substituent. Examples of the substituent include alkyl groups such as methyl, ethyl, n-butyl, and t-butyl; alkoxy groups such as methoxy, ethoxy, n-butoxy, and t-butoxy; aryl groups such as phenyl and naphthyl; hydroxyl groups; amino groups; and halogen atoms. The aromatic hydrocarbon group may have two or more substituents, and in such cases, the substituents may be the same or different. When the aromatic hydrocarbon group has a substituent, the total number of carbon atoms contained in the aromatic hydrocarbon group and the substituent is preferably 6 to 18. When the aromatic hydrocarbon group has a substituent, the position of the substituent is not particularly limited.

Specific examples of aromatic hydrocarbon groups having 6 to 18 carbon atoms include phenyl, 1-naphthyl, 2-naphthyl, tolyl, dimethylphenyl, ethylphenyl, butylphenyl, t-butylphenyl, methoxyphenyl, ethoxyphenyl, n-butoxyphenyl, and t-butoxyphenyl. The position of the substituent in these aromatic hydrocarbon groups may be any of the ortho, meta, and para positions. From the standpoint of fluidity, unsubstituted aryl groups having 6 to 12 carbon atoms or 6 to 12 carbon atoms including substituents are preferred, unsubstituted aryl groups having 6 to 10 carbon atoms or 6 to 10 carbon atoms including substituents are more preferred, and phenyl, p-tolyl, and p-methoxyphenyl are even more preferred.

The term "two or more of R ¹ to R ³ may be bonded to each other to form a cyclic structure" used as R ¹ to R ³ in general formula (I-1) means that two or three of R ¹ to R ³ are bonded to form a single divalent or trivalent hydrocarbon group as a whole. Examples of R ¹ to R ³ in this case include substituents that can form a cyclic structure when bonded to a phosphorus atom, such as alkylene groups such as ethylene, propylene, butylene, pentylene, and hexylene; alkenylene groups such as ethyleneylene, propylene, and butylene; aralkylene groups such as methylenephenylene; and arylene groups such as phenylene, naphthylene, and anthracenylene. These substituents may be further substituted with an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an amino group, a hydroxyl group, a halogen atom, or the like.

The "organic group having 1 to 18 carbon atoms" described as R ⁴ to R ⁷ in the above general formula (I-1) is meant to include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an aliphatic hydrocarbonoxy group, an aromatic hydrocarbonoxy group, an acyl group, a hydrocarbonoxycarbonyl group, and an acyloxy group, which have 1 to 18 carbon atoms and may be substituted or unsubstituted.

Examples of the aliphatic hydrocarbon group and aromatic hydrocarbon group include those listed above as examples of the aliphatic hydrocarbon group and aromatic hydrocarbon group represented by R ¹ to R ³ .

Examples of the aliphatic hydrocarbon oxy group include oxy groups having an oxygen atom bonded to the above-mentioned aliphatic hydrocarbon groups, such as methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, 2-butoxy, t-butoxy, cyclopropyloxy, cyclohexyloxy, cyclopentyloxy, allyloxy, and vinyloxy groups, as well as these aliphatic hydrocarbon oxy groups further substituted with alkyl, alkoxy, aryl, aryloxy, amino, hydroxyl, halogen, etc.

Examples of the aromatic hydrocarbon oxy group include oxy groups having a structure in which an oxygen atom is bonded to the above-mentioned aromatic hydrocarbon group, such as a phenoxy group, methylphenoxy group, ethylphenoxy group, methoxyphenoxy group, butoxyphenoxy group, or phenoxyphenoxy group, as well as aromatic hydrocarbon oxy groups further substituted with an alkyl group, alkoxy group, aryl group, aryloxy group, amino group, halogen atom, or the like.

Examples of the acyl group include aliphatic hydrocarbon carbonyl groups such as formyl, acetyl, ethylcarbonyl, butyryl, cyclohexylcarbonyl, and allylcarbonyl; aromatic hydrocarbon carbonyl groups such as phenylcarbonyl and methylphenylcarbonyl; and these aliphatic hydrocarbon carbonyl groups or aromatic hydrocarbon carbonyl groups further substituted with alkyl, alkoxy, aryl, aryloxy, amino, halogen atoms, etc.

Examples of the hydrocarbon oxycarbonyl group include aliphatic hydrocarbon oxycarbonyl groups such as methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, allyloxycarbonyl, and cyclohexyloxycarbonyl; aromatic hydrocarbon oxycarbonyl groups such as phenoxycarbonyl and methylphenoxycarbonyl; and these aliphatic hydrocarbon carbonyloxy groups or aromatic hydrocarbon carbonyloxy groups further substituted with an alkyl group, alkoxy group, aryl group, aryloxy group, amino group, halogen atom, etc.

Examples of the acyloxy group include aliphatic hydrocarbon carbonyloxy groups such as methylcarbonyloxy, ethylcarbonyloxy, butylcarbonyloxy, allylcarbonyloxy, and cyclohexylcarbonyloxy; aromatic hydrocarbon carbonyloxy groups such as phenylcarbonyloxy and methylphenylcarbonyloxy; and these aliphatic hydrocarbon carbonyloxy groups or aromatic hydrocarbon carbonyloxy groups further substituted with an alkyl group, alkoxy group, aryl group, aryloxy group, amino group, halogen atom, etc.

The term "two or more of R ^{4 to R 7 may be bonded to each other to form a cyclic structure" used in describing R 4 to R 7} in general formula (I-1) above means that two to four R ⁴ to R ⁷ may be bonded to form a single divalent to tetravalent organic group as a whole. In this case, R ⁴ to R ⁷ may include substituents capable of forming a cyclic structure, such as alkylene groups such as ethylene, propylene, butylene, pentylene, and hexylene; alkenylene groups such as ethyleneylene, propylene, and butylene; aralkylene groups such as methylenephenylene; and arylene groups such as phenylene, naphthylene, and anthracenylene, as well as oxy or dioxy groups thereof. These substituents may be further substituted with an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an amino group, a hydroxyl group, a halogen atom, or the like.

R ⁴ to R ⁷ in the general formula (I-1) above are not particularly limited. For example, they are preferably each independently selected from a hydrogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group, or a substituted or unsubstituted aryloxy group. Among these, from the viewpoint of availability of raw materials, a hydrogen atom, a hydroxyl group, an aryl group unsubstituted or substituted with at least one selected from the group consisting of an alkyl group and an alkoxy group, or a linear or cyclic alkyl group is preferred. Examples of unsubstituted aryl groups substituted with at least one selected from the group consisting of an alkyl group and an alkoxy group include a phenyl group, a p-tolyl group, an m-tolyl group, an o-tolyl group, and a p-methoxyphenyl group. Examples of linear or cyclic alkyl groups include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a 2-butyl group, a t-butyl group, an octyl group, and a cyclohexyl group. From the viewpoint of curability, it is preferred that R ⁴ to R ⁷ are all hydrogen atoms, or that at least one of R ⁴ to R ⁷ is a hydroxyl group and the rest are all hydrogen atoms.

In general formula (I-1), more preferably, two or more of R ¹ to R ³ are alkyl groups having 1 to 18 carbon atoms or cycloalkyl groups having 3 to 18 carbon atoms, and R ⁴ to R ⁷ are all hydrogen atoms, or at least one is a hydroxyl group and the rest are all hydrogen atoms. Even more preferably, R ¹ to R ³ are all alkyl groups having 1 to 18 carbon atoms or cycloalkyl groups having 3 to 18 carbon atoms, and R ⁴ to R ⁷ are all hydrogen atoms, or at least one is a hydroxyl group and the rest are all hydrogen atoms.

From the standpoint of rapid curing, it is preferable that the specific curing accelerator contains a compound represented by the following general formula (I-2):

In formula (I-2), R ¹ to R ³ are each independently a hydrocarbon group having 1 to 18 carbon atoms, and two or more of R ¹ to R ³ may be bonded to each other to form a cyclic structure, and R ⁴ to R ⁶ are each independently a hydrogen atom or an organic group having 1 to 18 carbon atoms, and two or more of R ⁴ to R ⁶ may be bonded to each other to form a cyclic structure.

Specific examples of R ¹ to R ⁶ in formula (I-2) are the same as the specific examples of R ¹ to R ⁷ in formula (I-1), and the preferred ranges are also the same.

Specific examples of specific curing accelerators include the addition reaction product of triphenylphosphine and 1,4-benzoquinone, the addition reaction product of tri-n-butylphosphine and 1,4-benzoquinone, the addition reaction product of tricyclohexylphosphine and 1,4-benzoquinone, the addition reaction product of dicyclohexylphenylphosphine and 1,4-benzoquinone, the addition reaction product of cyclohexyldiphenylphosphine and 1,4-benzoquinone, the addition reaction product of triisobutylphosphine and 1,4-benzoquinone, and the addition reaction product of tricyclopentylphosphine and 1,4-benzoquinone.

The specific curing accelerator can be obtained, for example, as an adduct of a tertiary phosphine compound and a quinone compound.
Specific examples of the tertiary phosphine compound include triphenylphosphine, tributylphosphine, dibutylphenylphosphine, butyldiphenylphosphine, ethyldiphenylphosphine, triphenylphosphine, tris(4-methylphenyl)phosphine, tris(4-ethylphenyl)phosphine, tris(4-n-propylphenyl)phosphine, tris(4-n-butylphenyl)phosphine, tris(isopropylphenyl)phosphine, tris(t-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, etc. From the viewpoint of moldability, triphenylphosphine and tributylphosphine are preferred.

Specific examples of quinone compounds include o-benzoquinone, p-benzoquinone, diphenoquinone, 1,4-naphthoquinone, and anthraquinone. From the standpoint of moisture resistance and storage stability, p-benzoquinone is preferred.

The thermosetting resin composition may contain a curing accelerator other than the phosphonium compound.
Specific examples of curing accelerators other than phosphonium compounds include diazabicycloalkenes such as 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) and 1,8-diazabicyclo[5.4.0]undecene-7 (DBU), cyclic amidine compounds such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 2-heptadecylimidazole; derivatives of the cyclic amidine compounds; phenol novolac salts of the cyclic amidine compounds or their derivatives; and combinations of these compounds with maleic anhydride, quinone compounds such as 1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, and phenyl-1,4-benzoquinone. compounds having intramolecular polarization obtained by adding a compound having a π bond, such as a compound having tetraphenylborate of DBU, a tetraphenylborate of DBN, a tetraphenylborate of 2-ethyl-4-methylimidazole, or a tetraphenylborate of N-methylmorpholine; cyclic amidinium compounds such as the tetraphenylborate salt of DBU, the tetraphenylborate salt of DBN, the tetraphenylborate salt of 2-ethyl-4-methylimidazole, or the tetraphenylborate salt of N-methylmorpholine; tertiary amine compounds such as pyridine, triethylamine, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, or tris(dimethylaminomethyl)phenol; derivatives of the above-mentioned tertiary amine compounds; and ammonium salt compounds such as tetra-n-butylammonium acetate, tetra-n-butylammonium phosphate, tetraethylammonium acetate, tetra-n-hexylammonium benzoate, or tetrapropylammonium hydroxide.

When the thermosetting resin composition contains a specific curing accelerator as a curing accelerator, the content of the specific curing accelerator is preferably 30% by mass or more of the total curing accelerator, more preferably 50% by mass or more, and even more preferably 70% by mass or more.

When the thermosetting resin composition contains a curing accelerator, the amount is preferably 0.1 to 30 parts by mass, and more preferably 1 to 15 parts by mass, per 100 parts by mass of the combined total of the thermosetting resin and curing agent. When the amount of curing accelerator is 0.1 part by mass or more per 100 parts by mass of the combined total of the thermosetting resin and curing agent, the composition tends to cure well in a short period of time. When the amount of curing accelerator is 30 parts by mass or less per 100 parts by mass of the combined total of the thermosetting resin and curing agent, the curing speed is not too fast, and a good molded product tends to be obtained.

(Inorganic filler)
The thermosetting resin composition contains an inorganic filler, which includes the specific inorganic filler as well as other inorganic fillers such as an inorganic filler that has not been surface-treated with a coupling agent and an inorganic filler that has been surface-treated with a coupling agent other than a coupling agent containing a primary amino group.
The type of inorganic filler is not particularly limited. Specific examples include inorganic materials such as silica (e.g., spherical silica, crystalline silica), glass, alumina, calcium carbonate, zirconium silicate, calcium silicate, silicon nitride, aluminum nitride, boron nitride, beryllia, zirconia, zircon, fosterite, steatite, spinel, mullite, titania, talc, clay, and mica. Inorganic fillers with flame retardant properties may also be used. Examples of inorganic fillers with flame retardant properties include aluminum hydroxide, magnesium hydroxide, composite metal hydroxides (e.g., magnesium-zinc composite hydroxide), and zinc borate. Among these, spherical silica is preferred from the viewpoint of reducing the linear expansion coefficient, and alumina is preferred from the viewpoint of high thermal conductivity. One type of inorganic filler may be used alone, or two or more types may be used in combination. The inorganic filler may be in the form of powder, beads formed by spheroidizing powder, or fibers.

The content of the inorganic filler in the thermosetting resin composition is not particularly limited. From the viewpoint of fluidity and strength, it is preferably 80% by mass to 95% by mass of the entire thermosetting resin composition, more preferably 82% by mass to 93% by mass, and even more preferably 84% by mass to 91% by mass. When the content of the inorganic filler is 80% by mass or more of the entire thermosetting resin composition, the properties of the cured product, such as the thermal expansion coefficient, thermal conductivity, and elastic modulus, tend to be further improved. When the content of the inorganic filler is 95% by mass or less of the entire thermosetting resin composition, an increase in the viscosity of the thermosetting resin composition is suppressed, and the fluidity is further improved, tending to result in better moldability.
The content of the inorganic filler in the thermosetting resin composition is not particularly limited. From the viewpoint of fluidity and strength, it is preferably 70 to 90% by volume of the entire thermosetting resin composition, more preferably 72 to 88% by volume, and even more preferably 75 to 85% by volume. When the content of the inorganic filler is 70% by volume or more of the entire thermosetting resin composition, the properties of the cured product, such as the thermal expansion coefficient, thermal conductivity, and elastic modulus, tend to be further improved. When the content of the inorganic filler is 90% by volume or less of the entire thermosetting resin composition, an increase in the viscosity of the thermosetting resin composition is suppressed, and the fluidity is further improved, tending to result in better moldability.

The average particle size of the inorganic filler is not particularly limited. For example, the volume average particle size is preferably 0.2 μm to 50 μm, and more preferably 0.5 μm to 30 μm.
When the volume average particle diameter is 0.2 μm or more, the increase in viscosity of the thermosetting resin composition tends to be further suppressed. When the volume average particle diameter is 50 μm or less, the filling ability into narrow gaps tends to be further improved. The volume average particle diameter of the inorganic filler refers to the value measured as the volume average particle diameter (D50) using a laser diffraction scattering particle size distribution measuring device.

From the viewpoint of the fluidity of the thermosetting resin composition, the particle shape of the inorganic filler is preferably spherical rather than angular, and the particle size distribution of the inorganic filler is preferably wide.

In this disclosure, the inorganic filler includes a specific inorganic filler, and the content of the specific inorganic filler is 20% to 60% by mass of the entire thermosetting resin composition. The content of the specific inorganic filler is preferably 21% to 55% by mass, and more preferably 22% to 50% by mass, of the entire thermosetting resin composition.

In the present disclosure, the proportion of the specific inorganic filler in the total inorganic filler is preferably 75% by mass or less, more preferably 70% by mass or less, and even more preferably 65% by mass or less. If the proportion of the specific inorganic filler in the total inorganic filler is 75% by mass or less, thickening of the thermosetting resin composition tends to be suppressed and storage stability tends to be improved. The proportion of the specific inorganic filler in the total inorganic filler may be 20% by mass or more.

The surface treatment method for inorganic fillers is selected appropriately depending on the type of inorganic filler. For example, if the inorganic filler is silica, surface treatment methods for the silica include adding a solution containing a coupling agent to a slurry containing silica, stirring, and then separating the surface-treated silica by filtration or other means and drying it, or spraying a coupling agent onto the silica and drying it.

The amount of coupling agent treatment of the specific inorganic filler is preferably 0.1 to 5 parts by mass, more preferably 0.3 to 4 parts by mass, and even more preferably 0.5 to 3 parts by mass, per 100 parts by mass of the inorganic filler before surface treatment with the coupling agent containing a primary amino group. If the amount of coupling agent treatment of the specific inorganic filler is 0.1 parts by mass or more, the dispersibility of the specific inorganic filler is improved, and the adhesiveness and moldability of the thermosetting resin composition tend to be improved. If the amount of coupling agent treatment of the specific inorganic filler is 5 parts by mass or less, the specific inorganic filler tends to be less likely to agglomerate.

The coupling agent containing a primary amino group used in the surface treatment of inorganic fillers may be any coupling agent having at least one primary amino group ( _-NH2 group) in the molecule. Specific examples of coupling agents having a primary amino group in the molecule include 3-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propyltriethoxysilane, 3-aminopropyltrimethoxysilane, and isopropyltri(N-aminoethyl-aminoethyl)titanate.
As the coupling agent having a primary amino group in the molecule, a silane coupling agent having a primary amino group in the molecule is preferred, and an aminoalkyltrialkoxysilane is more preferred. Examples of the aminoalkyltrialkoxysilane include 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane. Among these, at least one of 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane is more preferred, and 3-aminopropyltriethoxysilane is particularly preferred.

The bulk density of the specific inorganic filler is preferably 1.15 g/cm ³ to 1.40 g/cm ³ , more preferably 1.20 g/cm ³ to 1.38 g/cm ³ , and even more preferably 1.25 g/cm ³ to 1.35 g/cm ^3. When the bulk density of the specific inorganic filler is 1.15 g/cm ³ or more, the dispersibility of the specific inorganic filler in the thermosetting resin composition tends to be further improved. When the bulk density of the specific inorganic filler is 1.40 g/cm ³ or less, the fluidity of the thermosetting resin composition tends to be further improved.
In the present disclosure, bulk density refers to a value measured by the following method.
The bulk density is measured by a method in which a 200 ml measuring cylinder is tilted, the sample powder is gradually poured into it using a spoon up to the 200 ml mark, the measuring cylinder is then stoppered, and the measuring cylinder is then dropped 400 times from a height of 5 cm, after which the bulk density is calculated from the mass and volume of the sample powder.

The angle of repose of the specific inorganic filler is preferably 50° to 60°, more preferably 51° to 58°, and even more preferably 52° to 57°. If the angle of repose of the specific inorganic filler is 50° or more, uneven distribution of the specific inorganic filler in the thermosetting resin composition tends to be further suppressed. If the angle of repose of the specific inorganic filler is 60° or less, aggregation of the specific inorganic filler in the thermosetting resin composition tends to be further suppressed.
In the present disclosure, the angle of repose refers to a value measured by the injection method.

[Various additives]
In addition to the above-mentioned components, the thermosetting resin composition may contain various additives such as a coupling agent, an ion exchanger, a release agent, a flame retardant, a colorant, a stress relaxation agent, etc. In addition to the additives exemplified below, the thermosetting resin composition may also contain various additives known in the art, such as an ultraviolet absorber, as needed.

(Coupling Agent)
The thermosetting resin composition may include a coupling agent. In the present disclosure, the term "the thermosetting resin composition includes a coupling agent" means that the coupling agent is integrally blended into the thermosetting resin composition.
The type of coupling agent is not particularly limited, and known coupling agents can be used. Examples of coupling agents include silane coupling agents and titanium coupling agents. One type of coupling agent may be used alone, or two or more types may be used in combination.

Specific examples of silane coupling agents include epoxy-based silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and glycidoxyoctyltrimethoxysilane; amine-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propyltriethoxysilane, 3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane; 3-ureidopropyltriethoxysilane, octenyltrimethoxysilane, and methacryloxyoctyltrimethoxysilane.

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 dimethacrylisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri(dioctyl phosphate) titanate, isopropyl tricumylphenyl titanate, and tetraisopropyl bis(dioctyl phosphite) titanate.

When the thermosetting resin composition contains a coupling agent, the coupling agent is preferably at least one of an amine-based silane coupling agent and an epoxy-based silane coupling agent, from the viewpoint of improving the adhesiveness and moldability of the thermosetting resin composition.
When the thermosetting resin composition contains a coupling agent, the content of the coupling agent is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 8 parts by mass, and even more preferably 0.05 to 5 parts by mass, relative to 100 parts by mass of the inorganic filler, from the viewpoint of adhesion at the interface between the thermosetting resin and the inorganic filler.

(Ion exchanger)
The thermosetting resin composition may contain an ion exchanger. In particular, when the thermosetting resin composition is used as an encapsulating molding material, it is preferable to contain an ion exchanger from the viewpoint of improving the moisture resistance and high-temperature storage characteristics of electronic component devices. The ion exchanger is not particularly limited, and conventionally known ion exchangers can be used. Specific examples include hydrotalcite compounds and hydrous oxides of at least one element selected from the group consisting of magnesium, aluminum, titanium, zirconium, and bismuth. The ion exchangers may be used alone or in combination of two or more. Among these, hydrotalcites represented by the following general formula (B) are preferred:

Mg _(1-X) Al _X (OH) ₂ (CO ₃ ) _X/2・mH ₂ O ......(B)
(0<X≦0.5, m is a positive number)

When the thermosetting resin composition contains an ion exchanger, there are no particular restrictions on its content, as long as it is in an amount sufficient to capture ions such as halogen ions. For example, it is preferably 0.1 to 30 parts by weight, and more preferably 1 to 15 parts by weight, per 100 parts by weight of the combined thermosetting resin and curing agent.

(Release agent)
The thermosetting resin composition may contain a mold release agent from the viewpoint of obtaining good releasability from the mold during molding. There are no particular limitations on the mold release agent, and conventionally known ones can be used. Specific examples include carnauba wax, higher fatty acids such as montanic acid and stearic acid, higher fatty acid metal salts, ester waxes such as montanic acid esters, and polyolefin waxes such as polyethylene oxide and non-oxidized polyethylene. One type of mold release agent may be used alone, or two or more types may be used in combination.

When the thermosetting resin composition contains a release agent, the amount is preferably 0.01 to 15 parts by mass, and more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the combined total of the thermosetting resin and curing agent. When the amount of release agent is 0.01 parts by mass or more per 100 parts by mass of the combined total of the thermosetting resin and curing agent, sufficient release properties tend to be obtained. When the amount of release agent is 15 parts by mass or less per 100 parts by mass of the combined total of the thermosetting resin and curing agent, better adhesion tends to be obtained.

(Flame retardant)
The thermosetting resin composition may contain a flame retardant. The flame retardant is not particularly limited, and conventionally known flame retardants can be used. Specific examples include organic or inorganic compounds containing halogen atoms, antimony atoms, nitrogen atoms, or phosphorus atoms, and metal hydroxides. The flame retardants may be used alone or in combination of two or more.

When the thermosetting resin composition contains a flame retardant, the amount is not particularly limited as long as it is sufficient to achieve the desired flame retardant effect. For example, the amount is preferably 1 to 300 parts by weight, and more preferably 2 to 150 parts by weight, per 100 parts by weight of the combined total of the thermosetting resin and curing agent.

(Coloring agent)
The thermosetting resin composition may further contain a colorant. Examples of the colorant include known colorants such as carbon black, organic dyes, organic pigments, titanium oxide, red lead, and red iron oxide. The content of the colorant can be appropriately selected depending on the purpose, etc. One type of colorant may be used alone, or two or more types may be used in combination.

(Stress reliever)
The thermosetting resin composition may contain a stress relief agent such as silicone oil or silicone rubber particles. The inclusion of a stress relief agent can further reduce package warpage and package cracking. Examples of stress relief agents include commonly used known stress relief agents (flexibilizers). Specific examples include thermoplastic elastomers such as silicone, styrene, olefin, urethane, polyester, polyether, polyamide, and polybutadiene elastomers; rubber particles such as NR (natural rubber), NBR (acrylonitrile-butadiene rubber), acrylic rubber, urethane rubber, and silicone powder; methyl methacrylate-styrene-butadiene copolymer (MBS); methyl methacrylate-silicone copolymer; methyl methacrylate-butyl acrylate copolymer; copolymers of indenes (e.g., indene and alkylindene) with styrenes (e.g., alkylstyrene) and phenols, containing an aromatic olefin such as coumarone as another constituent monomer; and epoxy-modified silicone resins. The stress relief agents may be used alone or in combination of two or more.
When the thermosetting resin composition contains a stress relaxation agent, the content of the stress relaxation agent is preferably 1 to 50 parts by mass per 100 parts by mass of the total of the thermosetting resin and the curing agent.

(Method for preparing thermosetting resin composition)
The method for preparing the thermosetting resin composition is not particularly limited. A typical method includes thoroughly mixing predetermined amounts of components using a mixer or the like, melt-kneading the mixture using a mixing roll, extruder, or the like, cooling, and pulverizing the mixture. More specifically, a method includes uniformly stirring and mixing predetermined amounts of the components described above, kneading the mixture using a kneader, roll, extruder, or the like that has been preheated to 70°C to 140°C, cooling, and pulverizing the mixture.

The thermosetting resin composition is preferably solid at room temperature and normal pressure (e.g., 25°C, atmospheric pressure). When the thermosetting resin composition is solid, there are no particular restrictions on its shape, and examples include powder, granules, tablets, pellets, and granules. When the thermosetting resin composition is in tablet or pellet form, it is preferable from the standpoint of handleability that the dimensions and mass be set to suit the molding conditions of the package.

The method for curing the thermosetting resin composition is not particularly limited. The thermosetting resin composition may be cured by low-pressure transfer molding, injection molding, compression molding, or the like, and then post-cured.
The post-curing conditions can be appropriately set in consideration of the composition of the thermosetting resin composition, etc. The curing temperature for post-curing is, for example, preferably 160° C. to 240° C., more preferably 160° C. to 220° C., and even more preferably 175° C. to 200° C. The curing time for post-curing is, for example, preferably 1 hour to 48 hours, more preferably 3 hours to 24 hours, and even more preferably 5 hours to 24 hours.

<Semiconductor Device>
The semiconductor device of the present disclosure includes a semiconductor element and a cured product of the thermosetting resin composition of the present disclosure that encapsulates the semiconductor element.
The semiconductor element is not particularly limited, and examples thereof include a diode, a transistor, a thyristor, an IC (Integrated Circuit), and an LSI (Large Scale Integration).
Specific examples of semiconductor devices include DIP (Dual Inline Package), PLCC (Plastic Leaded Chip Carrier), QFP (Quad Flat Package), SOP (Small Outline Package), SOJ (Small Outline J-lead Package), TSOP (Thin Small Outline Package), TQFP (Thin Quad Flat Package), and QFN (Quad Flat Nozzle), which have a structure in which a semiconductor element is fixed on a lead frame, and terminal portions of the semiconductor element such as bonding pads are connected to lead portions by wire bonding, bumps, or the like, and then sealed using a thermosetting resin composition by transfer molding or the like. Examples of such a semiconductor device include a general resin-sealed IC such as a non-leaded IC; a TCP (Tape Carrier Package) having a structure in which a semiconductor element connected to a tape carrier by bumps is sealed with a thermosetting resin composition; a COB (Chip On Board) module, hybrid IC, multi-chip module, etc. having a structure in which a semiconductor element connected to wiring formed on a support member by wire bonding, flip chip bonding, solder, or the like is sealed with a thermosetting resin composition; and a BGA (Ball Grid Array), CSP (Chip Size Package), MCP (Multi Chip Package) having a structure in which a semiconductor element is mounted on the surface of a support member having terminals for connecting a wiring board formed on the back surface, and the semiconductor element and the wiring formed on the support member are connected by bumps or wire bonding, and then the semiconductor element is sealed with a thermosetting resin composition. Furthermore, these semiconductor devices may be stacked packages in which two or more semiconductor elements are mounted on a substrate in a stacked form, or may be lumped molded packages in which two or more semiconductor elements are encapsulated at once with a thermosetting resin composition.

The semiconductor device of the present disclosure is preferably a surface-mount type semiconductor device from the viewpoint of high-density packaging.
In the semiconductor device of the present disclosure, both surfaces of the semiconductor element may be in contact with the cured product of the thermosetting resin composition of the present disclosure either directly or via a metal substrate, such as a lead frame, an Ag-plated substrate, an Au-plated substrate, or a Ni/Pd/Au-plated substrate.
When both surfaces of the semiconductor element contact the cured product of the thermosetting resin composition directly or via a metal substrate, the contact area between the semiconductor element and the cured product increases. When the contact area between the semiconductor element and the cured product increases, peeling tends to occur at the interface between the semiconductor element and the cured product, which can result in deterioration of reflow resistance. Because the thermosetting resin composition of the present disclosure has excellent reflow resistance, applying the thermosetting resin composition of the present disclosure to a semiconductor device configured such that both surfaces of the semiconductor element contact the cured product of the thermosetting resin composition directly or via a metal substrate tends to be effective in preventing deterioration of reflow resistance.

The present disclosure will be explained in more detail below using examples, but the scope of the present disclosure is not limited to these examples.

[Preparation of Thermosetting Resin Composition]
The thermosetting resin compositions of Examples 1 to 3 and Comparative Examples 1 to 3 were prepared by mixing the following materials in the compositions (parts by mass) shown in Table 1 and performing roll kneading under conditions of a kneading temperature of 80°C and a kneading time of 15 minutes. When a thermosetting resin composition was prepared with the same composition as in Example 1 except that all of the inorganic fillers were replaced with Inorganic Filler 2, kneading became difficult. Therefore, the thermosetting resin composition in which all of the inorganic fillers were replaced with Inorganic Filler 2 was not evaluated.
In Table 1, "equivalent ratio (epoxy/phenol)" means the equivalent ratio between the epoxy resin and the curing agent.

Epoxy resin 1: a copolymer of methoxynaphthalene and cresol with formaldehyde, with an epoxy equivalent of 250 g/eq and a softening point of 58°C. Epoxy resin 2: a biphenyl-type epoxy resin with an epoxy equivalent of 196 g/eq and a softening point of 106°C. Curing agent 1: an aralkyl-type phenolic resin with a hydroxyl group equivalent of 175 g/eq and a softening point of 70°C. Curing agent 2: a melamine-modified phenolic resin with a hydroxyl group equivalent of 120 g/eq and a softening point of 90°C. Curing agent 3: 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine. Curing accelerator: addition reaction product of triphenylphosphine and 1,4-benzoquinone; Coupling agent 1: 3-glycidoxypropyltrimethoxysilane; Coupling agent 2: N-phenyl-3-aminopropyltrimethoxysilane; Mold release agent 1: Montan acid ester; Mold release agent 2: polyethylene oxide; Colorant: carbon black; Ion exchanger: hydrotalcite; Stress relaxation agent 1: indene-containing copolymer; Stress relaxation agent 2: epoxy-modified silicone resin; Inorganic filler 1: silica filler (spherical silica with an average particle size of 20 μm, angle of repose: 49°, bulk density: 1.42 g/cm ³ ) that has not been surface-treated with a coupling agent.
Inorganic filler 2: 3-aminopropyltriethoxysilane-treated silica filler (spherical silica with a volume average particle size of 20 μm, angle of repose: 53°, bulk density: 1.28 g/cm ³ , amount of 3-aminopropyltriethoxysilane treated per 100 parts by mass of silica before coupling agent treatment: 1 part by mass)

[evaluation]
Each thermosetting resin composition was evaluated under the following conditions.
The cured products of the thermosetting resin compositions were evaluated using cured products prepared under the following conditions. The evaluation results are shown in Table 1.
The cured product was obtained by molding the thermosetting resin composition using a transfer molding machine at a mold temperature of 175°C, a molding pressure of 8.3 MPa, and a curing time of 120 seconds, followed by post-curing at 175°C for 6 hours.

<Liquidity>
(Spiral Flow (SF) Evaluation)
Using a spiral flow measurement mold conforming to EMMI-1-66, the thermosetting resin composition was molded with 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, and the flow distance (inches) was determined.

(Gel time measurement)
The gel time (GT) of the thermosetting resin composition was measured using a Curastometer manufactured by JSR Trading Co., Ltd. Measurement was carried out at 180°C using 3 g of the thermosetting resin composition using a Curastometer manufactured by JSR Trading Co., Ltd., and the time until the torque curve rose was taken as the gel time (seconds).

-Adhesive strength after moisture absorption-
A thermosetting resin composition was applied to a silver-plated Cu lead frame (adhesion strength after moisture absorption 1) or a Ni-Pd-Au-plated Cu lead frame (adhesion strength after moisture absorption 2) as an adherend, and the thermosetting resin composition was cured under the above conditions to prepare a test specimen (adhesion surface 10 mm ² ). The test specimen was then humidified at 85°C and 85% RH for 96 hours. Using a DAGE bond tester, the shear speed (jig movement speed) was set to 50 μm/sec, and a force was applied in the shear direction to a position approximately 100 μm above the adherend surface of the cured product of the thermosetting resin composition to measure the force at which the adherend and the cured product of the thermosetting resin composition broke or peeled. The breakage or peeling force was measured while the test specimen was heated to 260°C.

-Reflow resistance 1-
A 28-pin SO (Small Outline) package (lead frame material: copper alloy, die pad top surface and lead tip silver-plated product) with a 3.2 mm x 2.2 mm x 0.37 mm silicon chip mounted on a 5.2 mm x 4.1 mm die pad was encapsulated using the curable resin compositions of Examples 1 and 2 and Comparative Examples 1 and 2, and then post-cured under the conditions described above. The resulting molded product was visually inspected for the absence of external cracks and confirmed for the absence of internal delamination using an ultrasonic flaw detector (Hitachi, Ltd., FS-200). The molded product was dried at 125°C for 12 hours and then humidified at 60°C and 60% RH for 120 hours. The reflow temperature was then set to 260°C in accordance with JEDEC regulations, and the reflow process was performed three times at the same temperature. The presence or absence of cracks on the outside of the package was visually observed, and the presence or absence of delamination inside the package was observed using an ultrasonic flaw detector. The percentage of packages that had either cracks or delamination out of 16 test packages was calculated.

-Reflow resistance 2-
A QFN (Quad Flat Non-leaded) package (lead frame material: copper alloy, Ni-Pd-Au plated) with a 3.0 mm x 3.0 mm x 0.37 mm silicon chip mounted on a 6.0 mm x 6.0 mm die pad was encapsulated using the curable resin compositions of Example 3 and Comparative Example 3, and then post-cured under the conditions described above. The absence of external cracks in the resulting molded product was confirmed visually, and the absence of internal peeling was confirmed using an ultrasonic flaw detector (Hitachi, Ltd., FS-200). The molded product was dried at 125°C for 12 hours and then humidified at 85°C and 60% RH for 168 hours. The reflow temperature was then set to 260°C in accordance with JEDEC regulations, and the reflow process was performed three times at the same temperature. The presence or absence of cracks on the outside of the package was visually observed, and the presence or absence of delamination inside the package was observed using an ultrasonic flaw detector. The percentage of packages that had either cracks or delamination out of 16 test packages was calculated.

Table 1 shows that the thermosetting resin compositions of the examples have superior reflow resistance compared to the thermosetting resin compositions of the comparative examples.

Claims (7)

Contains a thermosetting resin, a curing agent, and an inorganic filler,
the inorganic filler includes an inorganic filler that has been surface-treated with a coupling agent containing a primary amino group and an inorganic filler that has not been surface-treated with a coupling agent ,
the proportion of the inorganic filler surface-treated with the coupling agent containing a primary amino group in the entire inorganic filler is 30% by mass to 50% by mass;
A thermosetting resin composition in which the content of the inorganic filler surface-treated with the coupling agent containing a primary amino group relative to the entire thermosetting resin composition is 20% by mass to 60% by mass (excluding those in which the amount of coupling agent treatment of the inorganic filler surface-treated with the coupling agent containing a primary amino group is 3 parts by mass or more relative to 100 parts by mass of the inorganic filler before being surface-treated with the coupling agent containing a primary amino group) . 2. The thermosetting resin composition according to claim 1 , wherein the coupling agent is an aminoalkyltrialkoxysilane. 3. The thermosetting resin composition according to claim 1, wherein the inorganic filler surface-treated with the coupling agent containing a primary amino group has an angle of repose of 50° to 60°. The thermosetting resin composition according to any one of claims 1 to 3 , wherein the inorganic filler surface-treated with the coupling agent containing a primary amino group has a bulk density of 1.15 g/cm ³ to 1.40 g/cm ³ . A semiconductor device comprising: a semiconductor element; and a cured product of the thermosetting resin composition according to any one of claims 1 to 4 , which seals the semiconductor element. 6. The semiconductor device according to claim 5 , which is a surface mount type. 7. The semiconductor device according to claim 5 , wherein both surfaces of the semiconductor element are in contact with the cured product directly or via a metal substrate.