Sealing material for power semiconductor device, sealing member, and power semiconductor device

Abstract

The present disclosure relates to a sealing material for use in power semiconductor devices, the sealing material containing a compound having a vinyl phenyl group.

Description

Encapsulating material for power semiconductor device, encapsulant, and power semiconductor device

[0001] The present disclosure relates to an encapsulating material for a power semiconductor device, an encapsulant, a power semiconductor device, and a power semiconductor module.

[0002] In recent years, semiconductor devices have been used more frequently in high current or high voltage environments such as in automobiles, trains, wind power generation, solar power generation, etc., and as a result, emphasis has been placed on tracking resistance (high CTI). In particular, high tracking resistance is required for semiconductor devices known as power semiconductors.

[0003] In semiconductor devices, cured products of epoxy resin compositions are generally used as encapsulants for semiconductor elements (see, for example, Patent Documents 1 and 2). Patent Document 1 discloses a composition containing a dicyclopentadiene-type epoxy resin as an essential component for the purpose of improving the tracking resistance of the epoxy resin itself. Patent Document 2 discloses a composition in which spherical cristobalite is added to an epoxy resin composition.

[0004] JP 2005-213299 A JP 2013-112710 A

[0005] The present disclosure provides an encapsulating material for power semiconductor devices that can provide an encapsulating material having excellent tracking resistance. The present disclosure also provides an encapsulating material having excellent tracking resistance. Furthermore, the present disclosure provides a power semiconductor device and a power semiconductor module having excellent tracking resistance.

[0006] The present invention includes the following embodiments. The present invention is not limited to the following embodiments. One embodiment relates to an encapsulating material for use in a power semiconductor device, containing a compound having a vinylphenyl group. Another embodiment relates to an encapsulating material including a cured product obtained using the encapsulating material. Another embodiment relates to a power semiconductor device having a semiconductor element and the encapsulating material that encapsulates at least a portion of the semiconductor element. Another embodiment relates to a power semiconductor module having a plurality of elements selected from the group consisting of semiconductor elements and semiconductor devices, and the encapsulating material that encapsulates at least a portion of the plurality of elements.

[0007] According to the present disclosure, there is provided an encapsulating material for a power semiconductor device that can provide an encapsulant having excellent tracking resistance. Also, according to the present disclosure, there is provided an encapsulant having excellent tracking resistance. Furthermore, according to the present disclosure, there is provided a power semiconductor device and a power semiconductor module having excellent tracking resistance.

[0008] The following describes embodiments of the present invention. The present invention is not limited to the following embodiments. The following embodiments can be implemented alone or in combination. Combinations of multiple embodiments are also included in the present invention.

[0009] In the present disclosure, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in the present disclosure, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of another numerical range. The upper or lower limit of a numerical range described in the present disclosure may be replaced with a value shown in the Examples. A stepped numerical range may be created by selecting a numerical value from the upper and lower limit numerical values ​​described in stages in the present disclosure. The upper and lower limit numerical values ​​described in the present disclosure may be replaced with a value shown in the Examples. In the present disclosure, each component may contain multiple corresponding substances. 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, each structure in the polymer may contain multiple corresponding structures. When a polymer contains multiple structures corresponding to each structure, the content or amount of each structure refers to the total content or amount of the multiple structures present in the polymer, unless otherwise specified. In the present disclosure, the particles corresponding to each component may contain multiple types of particles. When a composition contains multiple types of particles corresponding to each component, the particle size of each component refers to the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0010] <Encapsulating Material> The encapsulating material is used in a power semiconductor device. The encapsulating material contains at least a compound having a vinylphenyl group. The encapsulating material may further contain a compound having a vinyl bond. In the present disclosure, a compound having a vinyl bond is a compound different from a compound having a vinylphenyl group, and is a compound that does not fall under the category of a compound having a vinylphenyl group. A compound having a vinyl bond does not have a vinylphenyl group. In the present disclosure, a compound having a vinylphenyl group may be referred to as a "vinylphenyl compound." In the present disclosure, a compound having a vinyl bond may be referred to as a "vinyl compound."

[0011] A cured product obtained using the encapsulating material can be used as an encapsulant for encapsulating one or both of a power semiconductor element and a power semiconductor device. The encapsulating material may be an encapsulant composition, and the encapsulant composition contains multiple types of compounds. In some embodiments, the encapsulating material is a radically polymerizable encapsulating material that can be polymerized by radical polymerization to form a cured product. The encapsulating material may be a radically polymerizable composition, and the radically polymerizable composition contains multiple types of compounds.

[0012] [Compound Having a Vinylphenyl Group] A vinylphenyl compound is a compound having at least one vinylphenyl group. The vinylphenyl compound has, for example, 1 to 20, 1 to 15, or 1 to 10 vinylphenyl groups. The vinylphenyl compound may consist of one type of vinylphenyl compound or may contain two or more types of vinylphenyl compounds. When an encapsulating material contains a vinylphenyl compound, the tracking resistance of the cured product is improved. One reason for this is the high reactivity of the vinylphenyl compound. High reactivity of the vinylphenyl compound facilitates sufficient curing reaction of the encapsulating material. As a result, the crosslink density of the resulting cured product increases, raising the thermal decomposition temperature and improving tracking resistance. In addition, a higher crosslink density also reduces the molding shrinkage of the cured product. However, these are speculations, and the present invention is not limited by these speculations.

[0013] The vinylphenyl group can be represented by any of the following formulas: From the viewpoint of obtaining a cured product with a low dielectric constant and dielectric dissipation factor, the vinylphenyl compound may contain a compound having a group represented by formula (p): * indicates the bonding position to other atoms.

[0014] In the total amount of vinylphenyl compounds contained in the encapsulating material, the ratio of groups represented by formula (p), groups represented by formula (m), and groups represented by formula (o) (molar ratio of groups represented by formula (p): groups represented by formula (m): groups represented by formula (o)) is, for example, 40 to 100: 0 to 60: 0 to 60, 70 to 90: 0: 10 to 30, or 40 to 60: 40 to 60: 0. The greater the ratio of groups represented by formula (p), the lower the dielectric constant and dielectric dissipation factor of the cured product tend to be.

[0015] The vinylphenyl compound may be a compound having a vinylphenylmethyl group (also referred to as a "vinylbenzyl group"). In the present disclosure, a compound having a vinylbenzyl group may be referred to as a "vinylbenzyl compound". The vinylbenzyl compound is an example of a vinylphenyl compound. The vinylphenyl compound may be a compound having a vinylphenylmethyloxy group (also referred to as a "vinylbenzyl ether group"). In the present disclosure, a compound having a vinylbenzyl ether group may be referred to as a "vinylbenzyl ether compound". The vinylbenzyl ether compound is an example of a vinylbenzyl compound and a vinylphenyl compound.

[0016] The vinylphenyl compound may be a monomer or polymer capable of radical polymerization. The vinylphenyl compound includes, for example, a monomer having a vinylphenyl group. In the present disclosure, a monomer having a vinylphenyl group may be referred to as a "vinylphenyl group-containing monomer." The vinylphenyl compound includes, for example, a polymer having a vinylphenyl group. In the present disclosure, a polymer having a vinylphenyl group may be referred to as a "vinylphenyl group-containing polymer." In the present disclosure, a monomer may be a compound that does not contain a repeating structural unit. A polymer may be a compound that contains a repeating structural unit. A polymer may be a polymer with a low degree of polymerization (i.e., an oligomer) or a polymer with a high degree of polymerization.

[0017] In some embodiments, the vinyl phenyl compound includes a compound having two vinyl phenyl groups. The compound having two vinyl phenyl groups may be a monomer or a polymer. In some embodiments, the vinyl phenyl compound includes a compound having three or more vinyl phenyl groups. The compound having three or more vinyl phenyl groups may be a monomer or a polymer.

[0018] The vinylphenyl compound includes, for example, a compound containing a structural unit represented by the following formula (Bb). (In the formula, X represents an organic group; each B independently represents a group containing a vinylphenyl group; each R independently represents a substituent; l represents an integer of 1 to 5; m represents an integer of 0 to 10; and * represents the bonding position to another atom.)

[0019] The term "independently" with respect to B means that, for example, when l is 2 or more and the structural unit represented by formula (Bb) has a plurality of Bs, the plurality of Bs may be the same "group containing a vinylphenyl group", or some or all of the Bs may be different "groups containing a vinylphenyl group". In this case, "independently" does not preclude l from being 1, and the structural unit represented by formula (Bb) may be a structural unit having one "group containing a vinylphenyl group". In the present disclosure, "(B) ｌThe same applies to statements similar to ".

[0020] Examples of X include X ｂ１ and X Ｂ１ Examples of the compound having a structural unit represented by formula (Bb) include a compound represented by formula (b1) described below and a polymer represented by formula (B1) described below.

[0021] (Vinylphenyl Group-Containing Monomer) In some embodiments, the vinylphenyl compound includes a vinylphenyl group-containing monomer. The vinylphenyl group-containing monomer includes a monomer having two vinylphenyl groups and may further include at least one selected from the group consisting of a monomer having one vinylphenyl group and a monomer having three vinylphenyl groups; or may include a monomer having two vinylphenyl groups, a monomer having one vinylphenyl group, and a monomer having three vinylphenyl groups. When the vinylphenyl group-containing monomer includes two or more vinylphenyl group-containing monomers, the average number of vinylphenyl groups contained in the vinylphenyl group-containing monomer is, for example, 1.2 to 2.8, 1.4 to 2.7, or 1.6 to 2.6.

[0022] The vinylphenyl group-containing monomer may further have an aromatic ring. The vinylphenyl group-containing monomer may have only one aromatic ring, or two or more aromatic rings. The number of carbon atoms in the aromatic ring may be, for example, 2 to 30, 6 to 20, or 9 to 15. The aromatic ring may be an aromatic hydrocarbon ring or an aromatic heterocyclic ring. The aromatic ring may be a monocyclic ring or a condensed polycyclic ring. Examples of aromatic hydrocarbon rings include benzene, naphthalene, anthracene, tetracene, fluorene, phenanthrene, indene, indane, and biphenylene. Examples of aromatic heterocyclic rings include pyridine, pyrazine, quinoline, isoquinoline, acridine, phenanthroline, furan, pyrrole, thiophene, carbazole, oxazole, oxadiazole, thiadiazole, triazole, benzoxazole, benzoxadiazole, benzothiadiazole, benzotriazole, and benzothiophene. From the viewpoint of the dielectric properties of the cured product, the aromatic ring may be an aromatic hydrocarbon ring or a fused polycyclic aromatic hydrocarbon ring. From the viewpoint of the dielectric constant and the dielectric loss tangent, the aromatic ring may be, for example, fluorene or indene; or may be indene. When the vinylphenyl group-containing monomer contains indene, it tends to be possible to obtain a cured product exhibiting a lower dielectric constant and dielectric loss tangent.

[0023] The aromatic ring, the aromatic hydrocarbon ring, the aromatic heterocycle, and the fused polycyclic aromatic hydrocarbon ring, which are examples of the aromatic ring, as well as the rings specifically mentioned above, may all be substituted or unsubstituted. In the case of substitution, examples of the substituent include an alkyl group, an alkenyl group, an aryl group, a heteroaryl group, and a monovalent group formed by bonding two or more groups selected from these. The number of carbon atoms in the alkyl group and the alkenyl group may be 1 to 18, 2 to 12, or 3 to 6. The number of carbon atoms in the aryl group and the heteroaryl group may be 2 to 30, 6 to 20, or 9 to 15. Examples of the monovalent group include an alkylaryl group, an arylalkyl group, and an alkylarylalkyl group.

[0024] The vinylphenyl group-containing monomer may include, for example, a monomer having one aromatic ring and 1 to 3 vinylphenyl groups bonded to the aromatic ring directly or via a linking group; a monomer having one aromatic hydrocarbon ring and 1 to 3 vinylphenyl groups bonded to the aromatic hydrocarbon ring directly or via a linking group; or a monomer having one indene ring and 1 to 3 vinylphenyl groups bonded to the indene ring directly or via a linking group. In these embodiments, the aromatic ring, aromatic hydrocarbon ring, and indene ring may each be substituted or unsubstituted. Examples of substituents are as described above. The linking group may be, for example, a group selected from the group consisting of an alkylene group (having, for example, 1 to 5 carbon atoms), an oxy group, a thio group, a sulfonyl group, a sulfinyl group, a carbonyl group, a carbonyloxy group, an imino group, and a divalent group formed by bonding two or more groups selected from these. The phrase "having one aromatic ring and 1 to 3 vinylphenyl groups bonded to the aromatic ring via linking groups" means "having one aromatic ring and 1 to 3 'linking groups bonded to the aromatic ring and 1 to 3 vinylphenyl groups bonded to the linking groups'."

[0025] The vinylphenyl group-containing monomer may have a saturated or unsaturated aliphatic hydrocarbon group, a saturated or unsaturated alicyclic hydrocarbon group, a group containing a hetero atom, or the like, instead of or in addition to the aromatic ring.

[0026] The weight average molecular weight (Mw) of the vinylphenyl group-containing monomer is, for example, 200 to 2,000, 200 to 1,000, 200 to 800, 250 to 750, or 300 to 700 from the viewpoint of moldability and handleability. In the present disclosure, the weight average molecular weight (Mw) and number average molecular weight (Mn) refer to values ​​measured in polystyrene equivalent terms by gel permeation chromatography (GPC). Specifically, the weight average molecular weight (Mw) and number average molecular weight (Mn) in the present disclosure can be measured by the method described in the examples.

[0027] In some embodiments, the vinyl phenyl compound includes a compound represented by formula (b1): (In the formula, X ｂ１ represents an organic group, each B independently represents a group containing a vinylphenyl group, 1 represents an integer of 1 to 5, each R independently represents a substituent, and m represents an integer of 0 to 5.

[0028] The organic group may be a group containing at least one carbon atom, for example, a group containing at least one selected from the group consisting of saturated aliphatic hydrocarbon groups, unsaturated aliphatic hydrocarbon groups, saturated alicyclic hydrocarbon groups, unsaturated alicyclic hydrocarbon groups, aromatic hydrocarbon ring groups, and aromatic heterocyclic groups. The organic group may or may not further contain a group containing a heteroatom. The organic group may be, for example, an aromatic hydrocarbon ring group or an aromatic heterocyclic group; or it may be an aromatic hydrocarbon ring group. Examples of the aromatic hydrocarbon ring in the aromatic hydrocarbon ring group and the aromatic heterocyclic ring in the aromatic heterocyclic group are as described above.

[0029] l may be 1 to 3. The vinylphenyl group-containing monomer, for example, in formula (b1), includes a compound in which l is 2, and may further include at least one compound selected from the group consisting of a compound in which l is 1 and a compound in which l is 3; or may include a compound in which l is 2, a compound in which l is 1, and a compound in which l is 3. When the vinylphenyl group-containing monomer includes multiple compounds represented by formula (b1), the average value of l in the compounds represented by formula (b1) is, for example, 1.2 to 2.8, 1.4 to 2.7, or 1.6 to 2.6.

[0030] Examples of the substituent represented by R include alkyl groups, alkenyl groups, aryl groups, heteroaryl groups, and monovalent groups formed by the bonding of two or more selected from these. The number of carbon atoms in the alkyl and alkenyl groups may be 1 to 18, 2 to 12, or 3 to 6. The number of carbon atoms in the aryl and heteroaryl groups may be 2 to 30, 6 to 20, or 9 to 15. Examples of the monovalent group include alkylaryl groups, arylalkyl groups, and alkylarylalkyl groups. m may be 0 to 2, or 0 or 1. When the vinylphenyl group-containing monomer contains multiple compounds represented by formula (b1), the average value of m in the compounds represented by formula (b2) is, for example, 0.0 to 1.8, 0.0 to 1.6, or 0.0 to 1.4. In some embodiments, the average value of m may be greater than 0.0, 0.1 or greater, 0.5 or greater, or 1.0 or greater.

[0031] In some embodiments, the vinyl phenyl compound includes a compound represented by the following formula (b2): When the vinyl phenyl compound includes a compound represented by the following formula (b2), better tracking resistance tends to be obtained. (In the formula, X ｂ２ represents an aromatic hydrocarbon ring group, B ｐ each independently represents a group represented by the following formula (Ph), each L independently represents a direct bond or a linking group, 1 represents an integer of 1 to 3, each R independently represents a substituent, and m represents an integer of 0 to 3. (In the formula, * represents the bonding position.)

[0032] Examples of the aromatic hydrocarbon ring in the aromatic hydrocarbon ring group are as described above. ｂ２ may be, for example, a fused polycyclic aromatic hydrocarbon ring group.

[0033] Examples of the linking group are as described above. The linking group may be, for example, an alkylene group (having, for example, 1 to 5 carbon atoms) or a methylene group. ｂ２ and B ｐ The same applies to descriptions similar to "L is a direct bond" in the present disclosure.

[0034] The vinylphenyl group-containing monomer may, for example, in formula (b2), include a compound in which l is 2, and may further include at least one compound selected from the group consisting of a compound in which l is 1 and a compound in which l is 3; or may include a compound in which l is 2, a compound in which l is 1, and a compound in which l is 3. When the vinylphenyl group-containing monomer includes multiple types of compounds represented by formula (b2), the average value of l in the compounds represented by formula (b2) is, for example, 1.2 to 2.8, 1.4 to 2.7, or 1.6 to 2.6.

[0035] Examples of the substituent represented by R are as set forth in formula (b1). m may be 0 to 2, or 0 or 1. When the vinylphenyl group-containing monomer includes multiple compounds represented by formula (b1), the average value of m in the compounds represented by formula (b2) is, for example, 0.0 to 1.8, 0.0 to 1.6, or 0.0 to 1.4. In some embodiments, the average value of m may be greater than 0.0, 0.1 or greater, 0.5 or greater, or 1.0 or greater.

[0036] From the viewpoint of obtaining a cured product having a low dielectric constant and a low dielectric loss tangent, the group represented by formula (Ph) may include a group represented by formula (p) above.

[0037] In some embodiments, the vinyl phenyl compound includes a compound represented by the following formula (b3): ​​When the vinyl phenyl compound includes a compound represented by the following formula (b3), better tracking resistance is obtained, and further, a low dielectric constant and a low dielectric loss tangent tend to be obtained. (In the formula, B ｈｂ each independently represents a hydrogen atom, a group represented by the following formula (Ba), or a group represented by the following formula (Bz), and at least one B ｈｂ is a group represented by the following formula (Bz). (In the formula, A represents an alkyl group, and * represents a bonding position.) (In the formula, * represents the bonding position.)

[0038] The alkyl group represented by A has, for example, 1 to 6 carbon atoms.

[0039] The vinylphenyl group-containing monomer may include a compound of formula (b3) in which the number of groups represented by formula (Bz) is 2, and may further include at least one selected from the group consisting of a compound in which the number of groups represented by formula (Bz) is 1 and a compound in which the number of groups represented by formula (Bz) is 3; or may include a compound in which the number of groups represented by formula (Bz) is 2, a compound in which the number of groups represented by formula (Bz) is 1, and a compound in which the number of groups represented by formula (Bz) is 3. When the vinylphenyl group-containing monomer includes multiple compounds of formula (b3), the average number of groups represented by formula (Bz) in the compounds represented by formula (b3) is, for example, 1.2 to 2.8, 1.4 to 2.7, or 1.6 to 2.6. The average number of groups represented by formula (Ba) in the compounds represented by formula (b3) is, for example, 0.0 to 1.8, 0.0 to 1.6, or 0.0 to 1.4. In some embodiments, the average number of groups represented by formula (Ba) may be greater than 0.0, 0.1 or more, 0.5 or more, or 1.0 or more.

[0040] From the viewpoint of obtaining a cured product having a low dielectric constant and a low dielectric loss tangent, the group represented by formula (Bz) may include a group represented by formula (Bz) in which the bonding position of the vinyl group to the benzene ring is para to the bonding position of the methylene group to the benzene ring.

[0041] The method for synthesizing the vinylphenyl group-containing monomer is not particularly limited. For example, when the vinylphenyl group-containing monomer is a compound represented by formula (b2), a method of reacting an aromatic hydrocarbon ring with a styrene having a halogenated methyl group in the presence of a basic compound can be mentioned. When synthesized by this method, the compound represented by formula (b2) has a methylene group as a linking group.

[0042] Examples of styrenes having a halogenated methyl group include o-chloromethylstyrene, m-chloromethylstyrene, and p-chloromethylstyrene, and these can be used alone or in combination of two or more. Examples of basic compounds include alkali metal hydroxides and alkali metal alkoxides. A phase transfer catalyst may be used in this reaction. Examples of phase transfer catalysts include tetrabutylphosphonium bromide and tetra-n-butylammonium bromide. The reaction can be carried out in a solvent. The reaction may be carried out under heating and stirring. A polymerization inhibitor may be added to the reaction system. The resulting product may be purified, as necessary, by known methods such as concentration, reprecipitation, and washing.

[0043] (Vinylphenyl Group-Containing Polymer) In some embodiments, the vinylphenyl compound includes a vinylphenyl group-containing polymer. The vinylphenyl compound may include a polymer having two vinylphenyl groups; or a polymer having three or more vinylphenyl groups. Examples of the vinylphenyl group-containing polymer include a polymer having a hydrocarbon chain skeleton and a vinylphenyl group; a polymer having a phenolic resin skeleton and a vinylphenyl group, and the like. Examples of polymers having a hydrocarbon chain skeleton include polyolefins, vinyl-based polymers, acrylic polymers, polydicyclopentadiene, and the like. Examples of phenolic resins include novolac-type phenolic resins, aralkyl-type phenolic resins, dicyclopentadiene-type phenolic resins, triphenylmethane-type phenolic resins, and resins of these phenolic resins that contain a naphthol structure instead of or in addition to the phenol structure.

[0044] The weight-average molecular weight (Mw) of the vinylphenyl group-containing polymer is, from the viewpoints of moldability and handleability, for example, 300 to 50,000, 500 to 30,000, or 1,000 to 10,000. From the viewpoints of improving the fluidity of the encapsulating material and obtaining good moldability, the weight-average molecular weight (Mw) may be 5,000 or less, or 2,500 or less.

[0045] In some embodiments, the vinyl phenyl compound comprises a polymer comprising a structure represented by formula (B1): (In the formula, X Ｂ１ represents an organic group, B represents a group containing a vinylphenyl group, R each independently represents a substituent, and m represents an integer of 0 to 10. * represents the bonding position to other atoms.

[0046] The organic group may be a group containing at least one carbon atom, for example, a group containing at least one selected from the group consisting of a saturated aliphatic hydrocarbon group, an unsaturated aliphatic hydrocarbon group, a saturated alicyclic hydrocarbon group, an unsaturated alicyclic hydrocarbon group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group. The organic group may or may not further contain a group containing a heteroatom.

[0047] Examples of the substituent represented by R include alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, and n-pentyl. When the alkyl group has 3 or more carbon atoms, it may be a linear alkyl group. m represents, for example, an integer of 0 to 5, an integer of 0 to 2, or 0.

[0048] In some embodiments, the vinyl phenyl compound includes a polymer represented by the following formula (B2): When the vinyl phenyl compound includes a polymer represented by the following formula (B2), better tracking resistance tends to be obtained. (In the formula, X Ｂ２ each independently represents a benzene ring or a naphthalene ring; each Y independently represents an organic group; B ｐ each independently represent a group represented by the following formula (Ph); each L independently represents a direct bond or a linking group; each R independently represents a substituent; each m independently represents an integer of 0 to 5; and n represents a number of 2 to 10. (In the formula, * represents the bonding position.)

[0049] The organic group may be a group containing at least one carbon atom, and examples thereof include alkylene groups such as a methylene group and an ethylene group; cycloalkylene groups such as tetrahydrodicyclopentadiene; arylalkylene groups such as a phenylmethylene group; and divalent organic groups containing an alkylene group and an arylene group.

[0050] From the viewpoint of obtaining a cured product having a low dielectric constant and a low dielectric loss tangent, the group represented by formula (Ph) may include a group represented by formula (p) above.

[0051] Examples of the linking group include an alkylene group (having, for example, 1 to 5 carbon atoms), an oxy group, a thio group, a sulfonyl group, a sulfinyl group, a carbonyl group, a carbonyloxy group, an imino group, and a divalent group formed by bonding two or more groups selected from these.

[0052] Examples of the substituent represented by R are as given in formula (B1). The substituent may be an alkyl group having 1 to 5 carbon atoms, or may be a methyl group. When the number of carbon atoms is 3 or more, the alkyl group may be a linear alkyl group. Each m independently represents, for example, an integer of 0 to 4, an integer of 0 to 2, or 0.

[0053] n is an average value in the polymer represented by formula (B2), and n is, for example, a number from 2 to 8, or a number from 3 to 5.

[0054] In some embodiments, the vinyl phenyl compound may comprise at least one selected from the group consisting of polymers represented by the formula: (In each formula, B ｐ each independently represents a group represented by the above formula (Ph), each L independently represents a direct bond or a linking group, and n represents a number from 2 to 10. The benzene ring and the naphthalene ring may each independently have a substituent at a substitutable position.

[0055] From the viewpoint of obtaining a cured product having a low dielectric constant and a low dielectric loss tangent, the group represented by formula (Ph) may include a group represented by formula (p) above.

[0056] Examples of the linking group are as given in formula (B2). The linking group may contain an oxy group from the viewpoint of obtaining good tracking resistance. The linking group may contain, for example, a methyleneoxy group. In this case, the polymer represented by the above formula may contain, for example, a methyleneoxy group. ｐ -CH ２ It includes a structure represented by -O-*.

[0057] When the benzene ring and the naphthalene ring in each formula have a substituent, examples of the substituent are as given for R in formula (B1). The substituent may be an alkyl group having 1 to 5 carbon atoms, or may be a methyl group. When the alkyl group has 3 or more carbon atoms, it may be a linear alkyl group. Alternatively, the benzene ring and the naphthalene ring in each formula may be unsubstituted, or may be a group selected from the group consisting of B ｐ It may not have any substituent other than -L-*.

[0058] n is an average value in the polymer represented by each formula, and n is, for example, a number from 2 to 8, or a number from 3 to 5.

[0059] When the vinylphenyl compound contains at least one selected from the group consisting of polymers represented by formula (B2-1) to formula (B2-11), excellent tracking resistance tends to be easily obtained. When the vinylphenyl compound contains at least one selected from the group consisting of polymers represented by formula (B2-3) and polymers represented by formula (B2-7), low dielectric constants and dielectric loss tangents are easily obtained. In particular, when the vinylphenyl compound contains a polymer represented by formula (B2-3), even lower dielectric constants and dielectric loss tangents are easily obtained.

[0060] In some embodiments, the vinyl phenyl compound includes a polymer represented by formula (B3-3) below, a polymer represented by formula (B3-7) below, or both. (In the formula, B ｂ each independently represents a group represented by the following formula (Bz), and n represents a number of 3 to 5. (In the formula, B ｂ each independently represents a group represented by the following formula (Bz), and n represents a number of 3 to 5. (In the formula, * represents a bonding position.)

[0061] From the viewpoint of obtaining a cured product having a low dielectric constant and a low dielectric loss tangent, the group represented by formula (Bz) may include a group represented by formula (Bz) in which the bonding position of the vinyl group to the benzene ring is para to the bonding position of the methylene group to the benzene ring.

[0062] The method for synthesizing the vinylphenyl group-containing polymer is not particularly limited. For example, when the vinylphenyl group-containing polymer is a compound represented by formula (B2), a method of reacting a phenolic resin with a styrene having a halogenated methyl group in the presence of a basic compound can be mentioned. When synthesized by this method, the compound represented by formula (B2) has a methyleneoxy group as a linking group.

[0063] Examples of the styrene having a halogenated methyl group, the basic compound, and the phase transfer catalyst are as described above. The reaction can be carried out in a solvent. The reaction can be carried out under heating and stirring. A polymerization inhibitor can be added to the reaction system. The resulting product can be purified, if necessary, by known methods such as concentration, reprecipitation, and washing.

[0064] Examples of phenolic resins include novolac-type phenolic resins, aralkyl-type phenolic resins, dicyclopentadiene-type phenolic resins, biphenyl-type phenolic resins, triphenylmethane-type phenolic resins, and resins containing a naphthol structure instead of or in addition to the phenol structure in these phenolic resins. Commercially available phenolic resins can be used.

[0065] The weight average molecular weight (Mw) of the phenolic resin is, for example, 300 to 30,000, 500 to 10,000, or 1,000 to 5,000 from the viewpoint of moldability and handleability of the encapsulating material. The number average molecular weight (Mn) of the phenolic resin is, for example, 200 to 10,000, 300 to 5,000, or 400 to 2,000 from the viewpoint of moldability and handleability. The hydroxyl equivalent of the phenolic resin is, for example, 50 to 500 g / eq, 100 to 400 g / eq, or 150 to 300 g / eq from the viewpoint of tracking resistance of the cured product. The hydroxyl equivalent can be measured by a method in accordance with JIS K 0070:1992.

[0066] (Content) The encapsulating material may contain only one type of vinylphenyl compound, or may contain two or more types of vinylphenyl compounds. The content of the vinylphenyl compound is, for example, 10 to 100 mass%, 15 to 80 mass%, or 20 to 60 mass%, based on the mass of the encapsulating material (excluding the mass of the filler if the encapsulating material contains a filler). When the content of the vinylphenyl compound is 10 mass% or more, the cured product tends to exhibit better tracking resistance. The content of the vinylphenyl compound is, for example, 50 mass% or less, 40 mass% or less, or 35 mass% or less. Considering the addition of optional components such as a polymerization initiator and a colorant, the content of the vinylphenyl compound may be less than 100 mass%.

[0067] When the vinylphenyl compound contains a vinylbenzyl compound, the content of the vinylbenzyl compound is, for example, 70% by mass or more, 80% by mass or more, or 90% by mass or more, based on the mass of the vinylphenyl compound. The upper limit of the content of the vinylbenzyl compound may be 100% by mass. When the vinylphenyl compound contains a vinylbenzyl ether compound, the content of the vinylbenzyl ether compound is, for example, 70% by mass or more, 80% by mass or more, or 90% by mass or more, based on the mass of the vinylphenyl compound. The upper limit of the content of the vinylbenzyl ether compound may be 100% by mass. When the sealing material contains a vinylbenzyl ether compound, tracking resistance tends to be improved.

[0068] When the vinylphenyl compound contains a vinylphenyl group-containing monomer and a vinylphenyl group-containing polymer, the content of the vinylphenyl group-containing monomer is, for example, 5 to 95 mass%, 50 to 90 mass%, or 70 to 88 mass%, based on the mass of the vinylphenyl compound. The content of the vinylphenyl group-containing polymer is, for example, 5 to 95 mass%, 10 to 50 mass%, or 12 to 30 mass%, based on the mass of the vinylphenyl compound.

[0069] When the encapsulating material contains a vinyl compound, the total content of the vinylphenyl compound and the vinyl compound is, for example, 70 to 100 mass%, 80 to 99 mass%, or 90 to 98 mass%, based on the mass of the encapsulating material (excluding the mass of the filler if the encapsulating material contains a filler). When the total content is 70 mass% or more, the cured product tends to exhibit better tracking resistance and a low molding shrinkage rate. Considering the addition of optional components such as a polymerization initiator and a colorant, the total content may be less than 100 mass%.

[0070] When the sealing material contains a vinyl compound, the content of the vinylphenyl compound is, for example, 10 to 90% by mass, 15 to 80% by mass, or 20 to 60% by mass, based on the total mass of the vinylphenyl compound and the vinyl compound. When the content of the vinylphenyl compound is 55% by mass or more, the cured product tends to exhibit better tracking resistance. From the viewpoint of obtaining a sufficient effect of the vinyl compound, the content of the vinylphenyl compound may be 90% by mass or less, or may be 50% by mass or less, 40% by mass or less, or 35% by mass or less.

[0071] [Compound Having a Vinyl Bond] The sealing material may further contain a vinyl compound. The vinyl compound is a compound having at least one vinyl bond. The vinyl bond may be a radical polymerizable carbon-carbon unsaturated bond. Examples of vinyl compounds include compounds in which the vinyl bond is CH ２ Examples of suitable vinyl compounds include compounds having a vinyl bond as a monovalent group represented by =CH-*, compounds having a vinyl bond as a divalent group represented by *-CH=CH-*, and compounds having both the monovalent group and the divalent group. The vinyl compound has, for example, 1 to 20, 1 to 15, or 1 to 10 vinyl bonds. The vinyl compound may consist of one type of vinyl compound or may contain two or more types of vinyl compounds. The vinyl compound does not have a vinylphenyl group. When the encapsulating material contains a vinyl compound, the curing properties are good and a cured product with a small molding shrinkage rate can be obtained.

[0072] The vinyl compound may be a monomer or polymer capable of radical polymerization. The vinyl compound includes, for example, a monomer having a vinyl bond. In the present disclosure, a monomer having a vinyl bond may be referred to as a "vinyl bond-containing monomer." The vinyl compound includes, for example, a polymer having a vinyl bond. In the present disclosure, a polymer having a vinyl bond may be referred to as a "vinyl bond-containing polymer."

[0073] In some embodiments, the vinyl compound includes a compound having two vinyl bonds. The compound having two vinyl bonds may be a monomer or a polymer. In some embodiments, the vinyl compound includes a compound having three or more vinyl bonds. The compound having three or more vinyl bonds may be a monomer or a polymer.

[0074] Examples of vinyl bond-containing monomers include olefin compounds such as ethylene, propylene, butadiene, isoprene, dimethylbutadiene, chloroprene, and 1,3-pentadiene; (meth)acrylic acid ester compounds such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tetra(meth)acrylate, and bisphenol A diglycidyl ether di(meth)acrylate; and carboxyl group-containing vinyl compounds such as (meth)acrylic acid, itaconic acid, maleic acid, and fumaric acid. halogen-containing vinyl compounds such as vinyl chloride and vinylidene chloride; nitrile group-containing vinyl compounds such as acrylonitrile and methacrylonitrile; amide group-containing vinyl compounds such as acrylamide, methacrylamide, N-methylolacrylamide and N-methylolmethacrylamide; maleimide compounds such as maleimide, N-phenylmaleimide and 4,4'-diphenylmethane bismaleimide; and nitrogen-containing vinyl compounds other than those mentioned above such as N-vinylpyrrolidone, 1-vinylimidazole and vinylcarbazole.

[0075] Examples of the vinyl bond-containing polymer include polymers having a hydrocarbon chain skeleton and a vinyl bond, polymers having a phenolic resin skeleton and a vinyl bond, polyamides, polyamideimides, or polyimides having a vinyl bond, etc. Examples of polymers having a hydrocarbon chain skeleton and phenolic resins are the same as those listed for the vinylphenyl group-containing polymer.

[0076] (Maleimide Compound) In some embodiments, the vinyl compound includes a compound having a maleimide group. In the present disclosure, a compound having a maleimide group may be referred to as a "maleimide compound." A maleimide compound is a compound having at least one maleimide group. The maleimide compound has, for example, 1 to 20, 1 to 15, or 1 to 10 maleimide groups. The maleimide compound may consist of one type of maleimide compound or may include two or more types of maleimide compounds. When the encapsulating material includes a maleimide compound, the curing properties are improved, the heat resistance is enhanced, and a cured product having a particularly low molding shrinkage rate can be obtained.

[0077] The maleimide group can be represented by the following formula: * indicates the bonding position to other atoms.

[0078] In some embodiments, the maleimide compound includes a compound having two maleimide groups, which may be referred to as a "bismaleimide" in the present disclosure.

[0079] In some embodiments, the vinyl compound includes a compound represented by formula (m1): (In the formula, X ｍ represents an organic group, and M represents a maleimide group.

[0080] The organic group may be a group containing at least one carbon atom, for example, a group containing at least one selected from the group consisting of saturated aliphatic hydrocarbon groups, unsaturated aliphatic hydrocarbon groups, saturated alicyclic hydrocarbon groups, unsaturated alicyclic hydrocarbon groups, aromatic hydrocarbon ring groups, and aromatic heterocyclic groups. The organic group may or may not further contain a group containing a heteroatom. From the viewpoint of improving the heat resistance of the cured product, the organic group is preferably a group containing at least one selected from the group consisting of aromatic hydrocarbon ring groups and aromatic heterocyclic groups.

[0081] In some embodiments, the vinyl compound may include at least one selected from the group consisting of compounds represented by the following formula: (In each formula, M represents a maleimide group, L ２ represents a direct bond or a linking group, R ｈａ each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and n represents an integer of 1 to 8. The benzene ring may each independently have a substituent at a substitutable position.

[0082] L ２ Examples of the linking group represented by the formula (m-2L) include an alkylene group (having, for example, 1 to 5 carbon atoms), an oxy group, a thio group, a sulfonyl group, a sulfinyl group, a carbonyl group, a carbonyloxy group, an imino group, and a group represented by the following formula (m-2L). Examples of the alkylene group having 1 to 5 carbon atoms include linear alkylene groups such as a methylene group, a 1,2-dimethylene group, a 1,3-trimethylene group, a 1,4-tetramethylene group, and a 1,5-pentamethylene group, and branched alkylene groups such as an isopropylene group, an isobutylene group, and a t-butylene group. (In the formula, L ２Ｌ represents a direct bond or a linking group. Each benzene ring may independently have a substituent at a substitutable position. * represents a bonding position.

[0083] L ２Ｌ Examples of the linking group represented by the formula (I) include an alkylene group (having, for example, 1 to 5 carbon atoms), an oxy group, a thio group, a sulfonyl group, a sulfinyl group, a carbonyl group, a carbonyloxy group, and an imino group. Examples of alkylene groups having 1 to 5 carbon atoms include L ２As mentioned above.

[0084] In the above formulas (m-1), (m-2), and (m-2L), the benzene rings may each independently be unsubstituted or may have a substituent at a substitutable position. Examples of the substituent include alkyl groups having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, and an n-pentyl group. The substituent may be an alkyl group having 1 to 3 carbon atoms, or may be a methyl group.

[0085] In the above formula (m-3), R ｈａ Examples of the alkyl group having 1 to 5 carbon atoms represented by the formula (I) are as described above. n represents, for example, an integer of 1 to 6, an integer of 1 to 3, or an integer of 4 to 6.

[0086] When the vinyl compound contains at least one selected from the group consisting of compounds represented by formula (m-1) and compounds represented by formula (m-2), excellent heat resistance tends to be easily obtained. ２ The vinyl compound may include a compound represented by formula (m-3) in which n is 4 to 8.

[0087] In some embodiments, the vinyl compound includes a polymer having a maleimide group. In the present disclosure, a polymer having a maleimide group may be referred to as a "maleimide group-containing polymer." The vinyl compound may include a polymer having two maleimide groups; or a polymer having three or more maleimide groups. Examples of maleimide compounds include polymers having a hydrocarbon chain skeleton and a maleimide group; polymers having a phenolic resin skeleton and a maleimide group; and polyamides, polyamideimides, or polyimides having maleimide groups. Examples of polymers having a hydrocarbon chain skeleton and phenolic resins are the same as those listed for the vinylphenyl group-containing polymer.

[0088] In some embodiments, the maleimide compound comprises a polymer represented by formula (M1): (In the formula, X Ｍeach independently represents a benzene ring or a naphthalene ring; each independently represents an organic group; M represents a maleimide group; each independently represents a direct bond or a linking group; each independently represents a substituent; each independently represents an integer of 0 to 5; and n represents a number of 2 to 10.

[0089] The organic group may be a group containing at least one carbon atom, and examples thereof include alkylene groups such as a methylene group and an ethylene group; cycloalkylene groups such as tetrahydrodicyclopentadiene; arylalkylene groups such as a phenylmethylene group; and divalent organic groups containing an alkylene group and an arylene group.

[0090] Examples of the linking group include an alkylene group (having, for example, 1 to 5 carbon atoms), an oxy group, a thio group, a sulfonyl group, a sulfinyl group, a carbonyl group, a carbonyloxy group, an imino group, and a divalent group formed by bonding two or more groups selected from these.

[0091] Examples of the substituent represented by R include alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, and n-pentyl. The substituent may be an alkyl group having 1 to 3 carbon atoms, or a methyl group. Each m independently represents, for example, an integer of 0 to 4, an integer of 0 to 2, or 0.

[0092] n is an average value in the polymer represented by formula (M), and n is, for example, a number from 2 to 8, or a number from 3 to 5.

[0093] In some embodiments, the maleimide compound may include at least one selected from the group consisting of polymers represented by the following formula: When the vinyl compound includes at least one selected from the group consisting of polymers represented by the following formula: (In each formula, M represents a maleimide group, each L independently represents a direct bond or a linking group, and n represents a number from 2 to 10. The benzene ring and the naphthalene ring may each independently have a substituent at a substitutable position.)

[0094] When the benzene ring and the naphthalene ring in each formula have a substituent, examples of the substituent are as given for R in formula (M1). The substituent may be an alkyl group having 1 to 3 carbon atoms or a methyl group. Alternatively, the benzene ring and the naphthalene ring in each formula may be unsubstituted or may not have a substituent other than M-L-*.

[0095] n is an average value in the polymer represented by each formula, and n is, for example, a number from 2 to 8, or a number from 3 to 5.

[0096] Specific examples of the maleimide compound include novolak-type maleimide compounds such as bis(4-maleimidophenyl)methane, polyphenylmethane maleimide, bis(4-maleimidophenyl)ether, bis(4-maleimidophenyl)sulfone, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, m-phenylene bismaleimide, 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane, 1,6'-bismaleimide-(2,2,4-trimethyl)hexane, 1,3-bis(3-maleimidophenoxy)benzene, 1,3-bis(4-maleimidophenoxy)benzene, and polyphenylmethane maleimide, and aralkyl-type maleimide compounds. The maleimide compound includes, for example, at least one selected from the group consisting of 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane, 1,6'-bismaleimide-(2,2,4-trimethyl)hexane, and polyphenylmethanemaleimide.

[0097] Commercially available maleimide compounds can be used. Examples of commercially available maleimide compounds include "BMI-80" (2,2-bis[4-(4-maleimidophenoxy)phenyl]propane), "BMI-1000, BMI-1000H, BMI-1100, BMI-1100H" (all 4,4'-diphenylmethane bismaleimide), and "BMI-2000, BMI-2300" (all phenylmethane bismaleimide), manufactured by Daiwa Chemical Industry Co., Ltd. maleimide), "BMI-3000, BMI-3000H" (both m-phenylene bismaleimide), "BMI-4000" (bisphenol A diphenyl ether bismaleimide), "BMI-5100" (3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide), "BMI-7000, BMI-7000H" (both 4-methyl-1,3-phenylene bismaleimide), "BMI-TMH" (1,6'-bismaleimide-(2,2,4-trimethyl)hexane); Designer Molecules Inc. Examples of such a polymer include "BMI-2500, BMI-2560, BMI-3000, BMI-5000, BMI-6100" manufactured by Isuzu Corporation; "NE-X470S" manufactured by DIC Corporation; and "MIR-3000-70MT" manufactured by Nippon Kayaku Co., Ltd.

[0098] (Content) When the sealing material contains a vinyl compound, the sealing material may contain only one type of vinyl compound, or may contain two or more types of vinyl compounds. When the sealing material contains a vinyl compound, the content of the vinyl compound is, for example, 10 to 90 mass%, 20 to 80 mass%, or 30 to 75 mass%, based on the mass of the sealing material (however, if the sealing material contains a filler, the mass of the filler is excluded). When the content is 10 mass% or more, the vinyl compound tends to have a sufficient effect. The vinyl compound content may be 40 mass% or more, 50 mass% or more, 55 mass% or more, or 60 mass% or more. When the vinyl compound content is 90 mass% or less, the vinylphenyl compound tends to have a heat resistance improving effect.

[0099] When the sealing material contains a vinyl compound, the content of the vinyl compound is, for example, 10 to 90% by mass, 20 to 85% by mass, or 30 to 80% by mass, based on the total mass of the vinylphenyl compound and the vinyl compound. When the content is 10% by mass or more, the vinyl compound tends to have a sufficient effect. The vinyl compound content may be 40% by mass or more, or 50% by mass or more. When the vinyl compound content is 90% by mass or less, the vinylphenyl compound tends to have an effect of improving heat resistance.

[0100] When the vinyl compound contains a maleimide compound, the content of the maleimide compound is, for example, 70% by mass or more, 80% by mass or more, or 90% by mass or more based on the mass of the vinyl compound. The upper limit of the content of the maleimide compound may be 100% by mass.

[0101] When the encapsulating material contains a maleimide compound, the encapsulating material may contain only one type of maleimide compound, or may contain two or more types of maleimide compounds. When the encapsulating material contains a maleimide compound, the content of the maleimide compound is, for example, 10 to 90 mass%, 20 to 80 mass%, or 30 to 75 mass%, based on the mass of the encapsulating material (excluding the mass of the filler if the encapsulating material contains a filler). When the content of the maleimide compound is 10 mass% or more, the cured product tends to exhibit a smaller mold shrinkage rate. In particular, from the viewpoint of reducing the mold shrinkage rate, the content of the maleimide compound may be 40 mass% or more, 50 mass% or more, 55 mass% or more, or 60 mass% or more. When the content of the maleimide compound is 90 mass% or less, the effect of improving heat resistance due to the vinylphenyl compound tends to be easily obtained.

[0102] When the encapsulating material contains a maleimide compound, the content of the maleimide compound is, for example, 10 to 90% by mass, 20 to 85% by mass, or 30 to 80% by mass, based on the total mass of the vinylphenyl compound and the maleimide compound. When the content of the maleimide compound is 10% by mass or more, the cured product tends to exhibit a smaller mold shrinkage. In particular, from the viewpoint of reducing the mold shrinkage, the content of the maleimide compound may be 40% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more. When the content of the maleimide compound is 90% by mass or less, the effect of improving heat resistance due to the vinylphenyl compound tends to be easily obtained.

[0103] When the encapsulating material contains a maleimide compound, from the viewpoints of dielectric properties, curability, moldability, and conductor adhesion, the ratio of the maleimide group content to the vinylphenyl group content in the encapsulating material (maleimide group (mol) / vinylphenyl group (mol)) may be, for example, 0.05 to 5.0, 0.20 to 3.0, or 0.30 to 1.0.

[0104] [Optional Components] The encapsulating material may contain optional components. Examples of optional components include the above-mentioned vinyl compounds, radical polymerization initiators, fillers, coupling agents, mold release agents, colorants, polymerization inhibitors, ion exchangers, flame retardants, stress relaxation agents, and other additives. In addition to the following examples, the encapsulating material may contain various additives as needed.

[0105] (Radical Polymerization Initiator) The sealing material may contain a radical polymerization initiator. When the sealing material is used for molding by heating, the radical polymerization initiator may be a thermal radical polymerization initiator that generates free radicals by heating. The thermal radical polymerization initiator may be, for example, an organic peroxide such as peroxyketal or dialkyl peroxide, or an azo compound such as azobisbutyronitrile or azobispropionitrile.

[0106] Examples of organic peroxides include 1,1,3,3-tetramethylbutylperoxyneodecanoate, di(4-t-butylcyclohexyl)peroxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, cumylperoxyneodecanoate, dilauroyl peroxide, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, and t-butylperoxyneodecanoate. Pivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyneoheptanoate, t-amylperoxy-2-ethylhexanoate, di-t-butylperoxyhexahydroterephthalate, t-amylperoxy-3,5, 5-trimethylhexanoate, 3-hydroxy-1,1-dimethylbutylperoxyneodecanoate, t-amylperoxyneodecanoate, di(3-methylbenzoyl) peroxide, dibenzoyl peroxide, di(4-methylbenzoyl) peroxide, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2, Examples of such peroxyalkylene compounds include 5-dimethyl-2,5-di(3-methylbenzoylperoxy)hexane, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexyl peroxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butyl peroxybenzoate, dibutyl peroxytrimethyl adipate, t-amyl peroxy normal octoate, t-amyl peroxy isononanoate, and t-amyl peroxybenzoate.

[0107] Examples of azo compounds include 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobis(1-acetoxy-1-phenylethane), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 4,4'-azobis(4-cyanovaleric acid), and 1,1'-azobis(1-cyclohexanecarbonitrile).

[0108] When the sealing material contains a radical polymerization initiator, the sealing material may contain only one type of radical polymerization initiator, or may contain two or more types of radical polymerization initiators. When the sealing material contains a radical polymerization initiator, the content of the radical polymerization initiator may be 0.1 to 5 mass%, or 0.2 to 3 mass%, based on the total mass of the vinylphenyl compound and the vinyl compound contained as needed (when the sealing material does not contain a vinyl compound, the mass of the vinylphenyl compound; the same applies below). For example, when the sealing material does not contain a vinyl compound, the sealing material may contain a radical polymerization initiator.

[0109] (Filler) The encapsulating material may contain a filler. When the encapsulating material contains a filler, the properties of the cured product, such as the thermal expansion coefficient, thermal conductivity, and elastic modulus, tend to be improved. Examples of fillers include inorganic fillers and organic fillers. In some embodiments, the encapsulating material contains an inorganic filler.

[0110] The inorganic filler may have an average particle size of 5 μm or more. From the viewpoint of improving the filling property of the sealing material, the inorganic filler may have an average particle size of 100 μm or less. The inorganic filler may have an average particle size of, for example, 5 to 100 μm, 8 to 50 μm, or 10 to 30 μm.

[0111] The average particle size of the inorganic filler can be determined by the following method. A thin sample is prepared from the encapsulating material or a cured product of the encapsulating material. 100 particles of the inorganic filler are randomly selected from an image of the thin sample taken with a scanning electron microscope. The major axis of each particle is measured, and the arithmetic average value is used as the average particle size of the inorganic filler.

[0112] The type of inorganic filler is not particularly limited. Examples include silica such as fused silica and crystalline silica; alumina, zirconia, titania, glass, talc, clay, and mica. The inorganic filler may be an inorganic filler having a flame retardant effect. Examples of inorganic fillers having a flame retardant effect include aluminum hydroxide; magnesium hydroxide; composite metal hydroxides such as a composite hydroxide of magnesium and zinc; and zinc borate.

[0113] The inorganic filler may contain silica to reduce the linear expansion coefficient, or alumina to improve thermal conductivity. The inorganic filler may be in the form of powder, spherical beads formed from powder, or fibers.

[0114] When the encapsulating material contains a filler, the encapsulating material may contain only one type of filler, or may contain two or more types of fillers. When the encapsulating material contains a filler, the filler content is, for example, 100 to 2,000 mass%, 250 to 1,500 mass%, or 350 to 700 mass%, based on the mass of the encapsulating material (excluding the mass of the filler). When the filler content is 100 mass% or more, the properties of the cured product, such as the thermal expansion coefficient, thermal conductivity, and elastic modulus, tend to be further improved. When the filler content is 2,000 mass% or less, the increase in viscosity of the encapsulating material is suppressed, the fluidity is further improved, and the moldability tends to be better. When the encapsulating material contains a filler, the filler content (excluding carbon black) is, for example, 50 to 90 volume%, 55 to 85 volume%, or 60 to 80 volume%, based on the volume of the encapsulating material. When the filler content is 50% by volume or more, the properties of the cured product tend to be further improved, such as the thermal expansion coefficient, thermal conductivity, and elastic modulus. When the filler content is 90% by volume or less, an increase in the viscosity of the sealing material is suppressed, and the flowability tends to be further improved, resulting in better moldability.

[0115] (Coupling Agent) The encapsulating material may contain a coupling agent. When the encapsulating material contains a coupling agent, the adhesiveness of the cured product or the adhesiveness between the resin component (vinylphenyl compound, vinyl compound included as needed, etc.) and the inorganic filler tends to be improved. Examples of coupling agents include silane coupling agents, titanate coupling agents, aluminum chelate coupling agents, and aluminum / zirconium coupling agents. Examples of silane coupling agents include epoxy silane coupling agents, mercapto silane coupling agents, amino silane coupling agents, alkyl silane coupling agents, ureido silane coupling agents, vinyl silane coupling agents, (meth)acrylic silane coupling agents, and disilazane coupling agents. In the present disclosure, when the encapsulating material contains a coupling agent, coupling agents having a vinylphenyl group are excluded from the scope of the above-mentioned vinylphenyl compounds, and coupling agents having a vinyl group are excluded from the scope of the above-mentioned vinyl compounds. In other words, vinylphenyl compounds and vinyl compounds are compounds other than compounds that fall under the category of coupling agents. When the sealing material contains a mercapto-based silane coupling agent or an amino-based silane coupling agent, the adhesiveness of the cured product tends to be improved.When the sealing material contains a vinyl-based silane coupling agent or a (meth)acrylic silane coupling agent, the moldability and strength of the cured product tend to be improved.

[0116] Examples of silane coupling agents include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyl Trimethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-anilinopropyltrimethoxysilane, γ-anilinopropyltriethoxysilane, γ-(N,N-dimethyl)aminopropyltrimethoxysilane, γ-(N,N-diethyl)aminopropyltrimethoxysilane, γ-(N,N-dibutyl)aminopropyltrimethoxysilane, γ-(N-methyl)anilinopropyltrimethoxysilane, γ-(N-ethyl)anilinopropyltrimethoxysilane γ-(N,N-dimethyl)aminopropyltrimethoxysilane, γ-(N,N-diethyl)aminopropyltriethoxysilane, γ-(N,N-dibutyl)aminopropyltriethoxysilane, γ-(N-methyl)anilinopropyltriethoxysilane, γ-(N-ethyl)anilinopropyltriethoxysilane, γ-(N,N-dimethyl)aminopropylmethyldimethoxysilane, γ-(N,N-diethyl)aminopropylmethyldimethoxysilane, γ-(N,N-dibutyl)aminopropyl Examples of such silane include methyldimethoxysilane, γ-(N-methyl)anilinopropylmethyldimethoxysilane, γ-(N-ethyl)anilinopropylmethyldimethoxysilane, N-(trimethoxysilylpropyl)ethylenediamine, N-(dimethoxymethylsilylisopropyl)ethylenediamine, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilane, vinyltrimethoxysilane, and γ-mercaptopropylmethyldimethoxysilane.

[0117] When the sealing material contains a coupling agent, the sealing material may contain only one type of coupling agent, or may contain two or more types of coupling agents. When the sealing material contains an inorganic filler and a coupling agent, the content of the coupling agent is, for example, 1 to 50 mass%, 10 to 45 mass%, or 20 to 40 mass%, based on the mass of the inorganic filler. When the content of the coupling agent is 1 mass% or more, the adhesiveness of the cured product tends to be improved. When the content of the coupling agent is 40 mass% or less, the moldability of the cured product tends to be improved.

[0118] (Release Agent) The encapsulating material may contain a release agent. When the encapsulating material contains a release agent, good releasability from the mold during molding is easily obtained. Examples of the release agent include known release agents such as 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 oxidized polyethylene and non-oxidized polyethylene.

[0119] When the sealing material contains a release agent, the sealing material may contain only one type of release agent, or may contain two or more types of release agents. When the sealing material contains a release agent, the content of the release agent is, for example, 0.01 to 10 mass%, 0.05 to 5 mass%, or 0.1 to 2 mass%, based on the total mass of the vinylphenyl compound and the vinyl compound contained as needed. When the content of the release agent is 0.01 mass% or more, sufficient release properties tend to be obtained. When the content of the release agent is 10 mass% or less, better adhesion tends to be obtained.

[0120] (Colorant) The sealing material may 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. The colorant may also function as a filler.

[0121] When the sealing material contains a colorant, the sealing material may contain only one type of colorant or two or more types of colorants. When the sealing material contains a colorant, the content of the colorant is, for example, 0.01 to 10 mass % or 0.1 to 5 mass % based on the total mass of the vinylphenyl compound and the vinyl compound contained as needed.

[0122] (Polymerization Inhibitor) The sealing material may contain a polymerization inhibitor. Examples of the polymerization inhibitor include phenolic compounds such as hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, and pyrogallol; and hindered amine compounds.

[0123] (Ion Exchanger) The sealing material may contain an ion exchanger. When the sealing material contains an ion exchanger, the moisture resistance and high-temperature storage characteristics of the power semiconductor device tend to be improved. Examples of the ion exchanger 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 exchanger may also function as a filler. The sealing material may contain only one type of ion exchanger, or may contain two or more types of ion exchangers.

[0124] (Flame Retardant) The sealing material may contain a flame retardant. Examples of flame retardants include organic or inorganic compounds containing halogen atoms, antimony atoms, nitrogen atoms, or phosphorus atoms, and metal hydroxides. The sealing material may contain only one type of flame retardant, or may contain two or more types of flame retardants.

[0125] (Stress Relaxant) The encapsulating material may contain a stress relaxation agent. When the encapsulating material contains a stress relaxation agent, warpage and cracking of the power semiconductor device tend to be reduced. Examples of stress relaxation agents include silicone oil; 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; and rubber particles having a core-shell structure such as methyl methacrylate-styrene-butadiene copolymer (MBS), methyl methacrylate-silicone copolymer, and methyl methacrylate-butyl acrylate copolymer (excluding vinyl phenyl compounds or compounds corresponding to vinyl compounds). When the encapsulating material contains a stress relaxation agent, the encapsulating material may contain only one type of stress relaxation agent, or two or more types of stress relaxation agents. Commercially available flexibility-imparting agents can be used as the stress relaxation agent.

[0126] [Comparative Tracking Index (CTI) of Cured Product] In some embodiments, the encapsulating material has a comparative tracking index (CTI) of the cured product measured in accordance with JIS C2134:2021 (IEC60112), for example, 530 V or more, 550 V or more, 580 V or more, or 600 V or more. A larger CTI tends to improve the reliability of the power semiconductor device.

[0127] In the present disclosure, the cured product for measurement may be a disk-shaped cured product produced by transfer molding using an encapsulating material. The molding conditions are a mold temperature of 175°C, a molding time of 120 seconds, and a molding pressure of 6.9 MPa, with the cured product having a diameter of 5 mm and a thickness of 3 mm. A tracking resistance tester (e.g., Yamayo Test Instruments Co., Ltd.'s "HAT-112-3") can be used for the measurement. Specifically, with the number of measurements n=5, 50 or more drops of a 0.1% by mass aqueous solution of ammonium chloride are dropped onto each cured product, and the maximum voltage at which none of the cured products breaks down is measured.

[0128] Since vinylphenyl compounds have good curability, when an encapsulating material contains a vinylphenyl compound, a cured product with a high crosslink density can be obtained, resulting in a high CTI. Furthermore, the CTI of the cured product tends to be high when the vinylphenyl compound has a vinylbenzyl ether group, when the resin component (e.g., vinylphenyl compound, vinyl compound) that forms the cured product has a high content of aromatic rings in the skeleton, or when the content of carbon black, which can be used as a colorant, is low.

[0129] [Molding Shrinkage of Cured Product] In some embodiments, the molding shrinkage of the cured product of the encapsulating material is, for example, 0.25% or less, 0.20% or less, 0.18% or less, or 0.15% or less. The smaller the shrinkage, the more likely it is that warpage of the power semiconductor device can be suppressed.

[0130] In the present disclosure, mold shrinkage (%) is measured by preparing a disk-shaped cured product by transfer molding, using the size of the cured product and the size of the mold used for transfer molding. The molding conditions are a mold temperature of 175°C, a molding time of 120 seconds, and a molding pressure of 6.9 MPa, and the curing conditions are a heating temperature of 175°C and a heating time of 6 hours. The size of the disk-shaped cured product used for measurement is, for example, about 80 mm in diameter and about 4 mm in thickness. The mold shrinkage (%) can be calculated using the following formula from the average diameter Rm (mm) of the front and back diameters of the cured product and the average inner diameter Rd (mm) of the mold corresponding to the front and back of the cured product: Mold shrinkage (%) = (Rd - Rm) / Rd x 100

[0131] If the resin component (vinyl phenyl compound, vinyl compound, etc.) that forms the cured product has a high content of aromatic rings in its skeleton and is rigid, the molding shrinkage rate tends to be small.

[0132] [Water Absorption of Cured Product] In some embodiments, the encapsulating material has a water absorption of 0.4% or less, 0.3% or less, 0.2% or less, or 0.1% or less after curing. The smaller the water absorption, the higher the reliability of the power semiconductor device.

[0133] In the present disclosure, water absorption (%) is measured by preparing a disk-shaped cured product by transfer molding, subjecting the cured product to a pressure cooker treatment, and using the masses of the cured product before and after the treatment. The molding conditions are a mold temperature of 175°C, a molding time of 120 seconds, and a molding pressure of 6.9 MPa, and the curing conditions are a heating temperature of 175°C and a heating time of 6 hours. The size of the disk-shaped cured product used for measurement is, for example, 50 mm in diameter and 3 mm in thickness. The conditions for the pressure cooker treatment are a pressure of 2 atm (0.2 MPa), a temperature of 121°C, a relative humidity of 100% RH, and a time of 20 hours. The masses of the cured product before and after the pressure cooker treatment are measured, and the water absorption (mass %) can be calculated using the following formula: Water absorption (mass %) = ((mass after treatment - mass before treatment) / mass before treatment) x 100

[0134] Unlike the reaction between an epoxy resin and a phenolic resin, the polymerization reaction of the vinylphenyl compound and the optional vinyl compound does not produce hydroxyl groups, which allows the water absorption of the cured product to be kept low.

[0135] [Method for Producing Encapsulating Material] The method for producing the encapsulating material is not particularly limited. For example, a method can be used in which predetermined amounts of components are thoroughly mixed using a mixer or the like, followed by melt-kneading, cooling, and pulverization. For melt-kneading, a kneader such as a twin-screw kneader; a roll such as a mixing roll; or an extruder such as an extruder can be used. The melt-kneading temperature is, for example, 70 to 140°C, or 80 to 130°C. The encapsulating material may be solid at room temperature and normal pressure (for example, 25°C, atmospheric pressure). The shape of the solid encapsulating material is not particularly limited, and examples include powder, granules, tablets, etc.

[0136] <Encapsulant> In some embodiments, the encapsulant includes a cured product obtained using the encapsulating material of the above embodiment. The encapsulant can be used to encapsulate power semiconductor elements, power semiconductor devices, and the like. The cured product can be produced, for example, by molding the encapsulating material and heating the resulting molded product. Heating conditions are, for example, 150 to 180°C for 2 to 16 hours.

[0137] <Power Semiconductor Device> The power semiconductor device has, for example, a power semiconductor element and the encapsulant of the above embodiment that encapsulates at least a portion of the power semiconductor element. The power semiconductor device may be, for example, a power semiconductor module that has a plurality of elements selected from the group consisting of power semiconductor elements and power semiconductor devices, and the encapsulant of the above embodiment that encapsulates at least a portion of the plurality of elements. The power semiconductor module may include electronic components other than power semiconductor elements, electronic component devices other than power semiconductor devices, etc.

[0138] Examples of power semiconductor elements include diodes, thyristors, and transistors such as IGBTs (insulated gate bipolar transistors), Si-based MOSFETs (metal oxide semiconductor field effect transistors), and SiC-based MOSFETs (metal oxide semiconductor field effect transistors). Materials for power semiconductor elements include Si (silicon), SiC (silicon carbide), and GaN (gallium nitride). The encapsulating material of the above embodiment is suitable as an encapsulating material for power semiconductor elements and power semiconductor devices made of SiC.

[0139] Examples of electronic components include active elements or components such as diodes, transistors, integrated circuits, and relays; passive elements or components such as resistors, capacitors, and coils; connectors, support members, terminals, and switches. Applications of power semiconductor devices include, for example, cars, trains, wind power generation, solar power generation, industrial electrical equipment; and household electrical equipment such as PCs (personal computers), smartphones, air conditioners, and televisions. The power semiconductor device may be a power semiconductor module having semiconductor elements other than power semiconductor elements, such as diodes, transistors, thyristors, photoelectric conversion elements, sensors, and ICs (integrated circuits); or it may be an intelligent power module.

[0140] The semiconductor device may be in a known package form, such as an insertion-mount package or a surface-mount package, including a lead frame type and a solder ball type. Specific examples include general resin-sealed integrated circuits (ICs) such as SIP (Single Inline Package), DIP (Dual Inline Package), PGA (Pin Grid Array), PLCC (Plastic Leaded Chip Carrier), QFP (Quad Flat Package), SOP (Small Outline Package), SOJ (Small Outline J-lead package), TSOP (Thin Small Outline Package), and TQFP (Thin Quad Flat Package). Further specific examples include MCPs (Multi-Chip Packages) such as MCMs (Multi-Chip Modules); and hybrid ICs.

[0141] A resin-encapsulated IC has a structure in which, for example, a semiconductor element is fixed on a lead frame, and terminal portions of the semiconductor element, such as bonding pads, are connected to leads by wire bonding, bumps, etc., and then encapsulated using an encapsulating material by transfer molding, etc. An MCM has a structure in which, for example, multiple semiconductor elements are connected to wiring formed on a support member by wire bonding, flip-chip bonding, solder, etc., and encapsulated with an encapsulating material.

[0142] For example, a method for manufacturing a power semiconductor device includes placing a power semiconductor on a support member and encapsulating at least a portion of the power semiconductor using the encapsulation material of the above embodiment. Examples of methods for encapsulating a power semiconductor element or a power semiconductor device include transfer molding, compression molding, and injection molding. Transfer molding can be performed under conditions of, for example, a mold temperature of 130 to 180°C, a molding pressure of 6 to 10 MPa, and a molding time of 60 to 120 seconds. The heating conditions for post-curing are, for example, 150 to 180°C for 2 to 16 hours.

[0143] <Examples of Embodiments> Examples of embodiments are listed below. The present invention is not limited to the following embodiments. (1) An encapsulating material for use in a power semiconductor device, containing a compound having a vinylphenyl group. (2) The encapsulating material according to (1) above, in which the compound having a vinylphenyl group includes a compound represented by formula (b3) above. (3) The encapsulating material according to (1) or (2) above, in which the compound having a vinylphenyl group includes at least one selected from the group consisting of a polymer represented by formula (B3-3) above and a polymer represented by formula (B3-7) above. (4) The encapsulating material according to any one of (1) to (3) above, in which the compound having a vinylphenyl group includes a compound having a vinylphenylmethyl group. (5) The encapsulating material according to any one of (1) to (4) above, in which a compound having a vinyl bond is included. (6) The encapsulating material according to (5) above, in which the compound having a vinyl bond includes a compound having a maleimide group. (7) The encapsulating material according to any one of (1) to (6) above, in which the power semiconductor device is a power semiconductor module. (8) An encapsulant comprising a cured product obtained using the encapsulating material according to any one of (1) to (7). (9) A power semiconductor device having a power semiconductor element and the encapsulant according to (8) that encapsulates at least a portion of the power semiconductor element. (10) A power semiconductor module having a plurality of elements selected from the group consisting of power semiconductor elements and power semiconductor devices, and the encapsulant according to (8) that encapsulates at least a portion of the plurality of elements.

[0144] The disclosure of this application is related to the subject matter described in Japanese Patent Application No. 2023-128621, filed on August 7, 2023, the entire disclosure of which is incorporated herein by reference.

[0145] The embodiments of the present invention will be described in more detail with reference to examples, but the embodiments of the present invention are not limited to the following examples.

[0146] Synthesis of Vinylphenyl Compounds (Synthesis Example 1: Synthesis of Vinylphenyl Compound 1) A phenolic resin, chloromethylstyrene, a phase transfer catalyst, pure water, a polymerization inhibitor, and a solvent listed in Table 1 were added to a 500 mL reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and an air pump. The resulting composition was stirred at 40°C while blowing air into it at a flow rate of 50 mL / min. Next, while maintaining the temperature at 70°C, a basic compound listed in Table 1 was added dropwise over 20 minutes, and the mixture was further stirred at 70°C for 4 hours. Air blowing was continued during the reaction. The composition was cooled to room temperature (25°C) and neutralized with a 10% by mass aqueous hydrochloric acid solution. The organic phase was then washed three times with pure water. The organic phase was then precipitated in methanol to obtain the target vinylphenyl compound 1. Infrared absorption (IR) spectroscopy confirmed that vinylphenyl compound 1 had a structure in which substantially all of the phenolic hydroxyl groups of a phenolic resin were replaced with vinylbenzyl ether groups (vinylphenylmethyloxy groups). The weight-average molecular weight of vinylphenyl compound 1 is shown in Table 1.

[0147] (Synthesis Example 2: Synthesis of vinylphenyl compound 2) Vinylphenyl compound 2 was obtained in the same manner as in Synthesis Example 1, except that the raw materials were changed to those shown in Table 1. Infrared absorption (IR) spectroscopic analysis confirmed that vinylphenyl compound 2 had a structure in which substantially all of the phenolic hydroxyl groups of the phenolic resin had been replaced with vinylbenzyl ether groups. The weight-average molecular weight of vinylphenyl compound 2 is shown in Table 1.

[0148] Synthesis Example 3: Synthesis of Vinylphenyl Compound 3 An aromatic hydrocarbon, chloromethylstyrene, a phase transfer catalyst, a polymerization inhibitor, and a solvent listed in Table 1 were added to a 500 mL reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet. The resulting composition was stirred at 40°C while blowing in nitrogen at a flow rate of 50 mL / min. Next, a basic compound listed in Table 1 was added dropwise over 20 minutes, and the mixture was further stirred at 60°C for 9 hours. Nitrogen blowing was continued during the reaction. The composition was cooled to room temperature (25°C), neutralized with a 10% by mass aqueous hydrochloric acid solution, and then washed twice with pure water. Thereafter, toluene was distilled off under reduced pressure, and the resulting viscous liquid was washed with methanol and then vacuum-dried to obtain vinylphenyl compound 3. Vinylphenyl compound 3 was １ H-nuclear magnetic resonance ( １ H-NMR analysis confirmed that the compound had a structure in which substantially all of the two hydrogen atoms directly bonded to the carbon atom at position 1 of the indene were substituted with vinylbenzyl groups (vinylphenylmethyl groups). GPC analysis confirmed that vinylphenyl compound 3 was a mixture of a compound having two vinylbenzyl groups and a compound having three vinylbenzyl groups, and that the average number of vinylbenzyl groups was in the range of 1.6 to 2.6. The weight-average molecular weight of vinylphenyl compound 3 is shown in Table 1.

[0149] In the examples, the weight average molecular weight (Mw) and number average molecular weight (Mn) were measured under the following conditions. The weight average molecular weight (Mw) and number average molecular weight (Mn) were calculated by gel permeation chromatography (GPC) from a calibration curve using standard polystyrene. The calibration curve was approximated by a cubic equation using standard polystyrene: TSKstandard POLYSTYRENE (Types: A-2500, A-5000, F-20, F-80) (Tosoh Corporation). Apparatus: High-speed GPC apparatus HLC-8320GPC (Tosoh Corporation) Detector: Ultraviolet absorption detector UV-8320 (Tosoh Corporation) Columns: Guard column; TSKgel guard column Super (HZ)-M + Column; TSKgel SuperMultipore HZ-M (2 columns), Reference column; TSKgel Super H-RC (2 columns) (all Tosoh Corporation) Column size: 4.6 x 20 mm (guard column), 4.6 x 150 mm (column), 6.0 x 150 mm (reference column) Eluent: Tetrahydrofuran Sample concentration: 10 mg / 1 mL Injection volume: 20 μL or 2 μL Flow rate: 0.35 mL / min Measurement temperature: 40°C

[0150] The compounds listed in Table 1 are as follows. In Table 1, the unit for each compound is "parts by mass." "-" means that the corresponding compound was not used. The hydroxyl group equivalent of the phenolic resin was measured by the method described above.

[0151] (Phenol resins) HE100C-30: aralkyl type phenol resin, Air Water Inc., weight average molecular weight (Mw) 2,350, number average molecular weight (Mn) 450, hydroxyl group equivalent 170 to 175 g / eq MEHC-7851M: biphenyl aralkyl type phenol resin, Meiwa Chemical Industry Co., Ltd., weight average molecular weight (Mw) 1,500, number average molecular weight (Mn) 900, hydroxyl group equivalent 201 to 220 g / eq (Aromatic hydrocarbons) Indene: molecular weight 116.2 (Chloromethylstyrene) CMS: a mixture of o-chloromethylstyrene and p-chloromethylstyrene, Wujin Linchuan Chemical Co., Ltd., o-chloromethylstyrene content of 17% by mass, p-chloromethylstyrene content of 83% by mass CMS-P: a mixture of m-chloromethylstyrene and p-chloromethylstyrene, AGC Seimi Chemical Co., Ltd., m-chloromethylstyrene content of 50% by mass, p-chloromethylstyrene content of 50% by mass (Phase transfer catalyst) Tetrabutylphosphonium bromide: Kanto Chemical Co., Ltd. Tetra-n-butylammonium bromide: Kanto Chemical Co., Ltd. (Polymerization inhibitor) Phenothiazine (organic solvent) Toluene 2-propanol (basic compound) Aqueous sodium hydroxide solution: Kanto Chemical Co., Ltd., concentration 48% by mass

[0152]

[0153] <Preparation of Encapsulating Material (Encapsulating Composition)> The vinylphenyl compounds obtained in Synthesis Examples 1 to 3 were each placed in a metal tray and left to stand in a vacuum dryer at a pressure of 0.1 MPa or less and a temperature of 70°C for 5 hours to remove the solvent.

[0154] [Examples 1 to 5 and Comparative Example 1] The vinylphenyl compound after removal of the solvent and the compounds shown in Table 2 were premixed (dry blended), and then kneaded in a twin-screw kneader (kneading temperature: 120°C). The kneaded product was cooled and pulverized to produce a powdered encapsulant composition.

[0155] The compounds listed in Table 2 are as follows. In Table 2, the unit for each compound is "parts by mass." "-" indicates that the corresponding compound is not included. The average particle size of the inorganic filler was measured by the method described above. The content (volume %) of the inorganic filler is the ratio of the volume of silica based on the volume of the encapsulant composition. "Vinyl phenyl group equivalent / maleimide group equivalent" is the ratio of the vinyl phenyl group equivalent (weight average molecular weight / number of functional groups) of the vinyl phenyl compound to the maleimide group equivalent (molecular weight calculated from the chemical formula / number of functional groups) of the maleimide compound.

[0156] (Vinylphenyl compounds) Vinylphenyl compound 1: the vinylphenyl compound (vinylbenzyl ether compound) obtained in Synthesis Example 1 Vinylphenyl compound 2: the vinylphenyl compound (vinylbenzyl ether compound) obtained in Synthesis Example 2 (Vinyl compounds) Maleimide compound 1: 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, K.I. Chemical Co., Ltd. "BMI-80" Maleimide compound 2: polyphenylmethane maleimide, Daiwa Chemical Industry Co., Ltd. "BMI-2300" (Epoxy compounds) Epoxy resin 1: triphenylmethane type epoxy resin, Nippon Kayaku Co., Ltd. "EPPN-501HY" Epoxy resin 2: biphenyl type epoxy resin, Mitsubishi Chemical Corporation "YX4000H" (Phenol resin) Phenolic resin: biphenyl aralkyl resin, UBE Inc. "MEHC7851-SS" (Other raw materials) Curing accelerator: phosphorus-based accelerator Coupling agent 1: 3-mercaptopropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd. "KBM-803" Coupling agent 2: N-phenyl-3-aminopropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd. "KBM-573" Mold release agent: Montan acid ester wax, Clariant Japan Co., Ltd. "HW-E" Colorant: Carbon black, Mitsubishi Chemical Corporation "MA100RMJ" Inorganic filler: Silica (average particle size 26.9 μm), Zhejiang Huafei Electronic Materials Co., Ltd. "SS-205"

[0157] <Preparation of Cured Product> A cured product was prepared using the encapsulant composition, and the tracking resistance, molding shrinkage, and water absorption were measured. The measurement results are shown in Table 2.

[0158] (Measurement of Tracking Resistance) Using a transfer molding machine (Technomarushi Co., Ltd.), a mold temperature of 175°C, a molding time of 120 seconds, and a molding pressure of 6.9 MPa, a disk-shaped molded product with a diameter of 5 mm and a thickness of 3 mm was obtained. The molded product was completely cured at 175°C for 6 hours. Using the cured product, a tracking resistance test was conducted using a tracking resistance tester HAT-112-3 (Yamayo Test Instruments Co., Ltd.) based on the method of JIS C2134:2021 (IEC60112). In the test, the number of measurements (n = 5) was measured, and 50 or more drops of a 0.1% aqueous solution of ammonium chloride were dropped onto each cured product, and the maximum voltage at which none of the cured products broke down was measured. The higher this maximum voltage, the better the tracking resistance.

[0159] (Measurement of Mold Shrinkage) Using a mold, a disc-shaped molded product (diameter approximately 80 mm x thickness approximately 4 mm) was molded using a transfer molding machine (Technomarushi Co., Ltd.) under conditions of a mold temperature of 175°C, a molding time of 120 seconds, and a molding pressure of 6.9 MPa. The molded product was then allowed to cool to 25°C. After cooling to 25°C, the molded product was heated and cured in an oven heated to 175°C for 6 hours, and the resulting cured product was allowed to cool to 25°C. After cooling, the diameters of the front and back of the cured product were measured, and the average of the two measurements was taken as Rm (mm). The inner diameter of the mold corresponding to the front of the cured product and the inner diameter of the mold corresponding to the back of the cured product were measured, and the average of the two measurements was taken as Rd (mm). The mold shrinkage (%) was calculated from Rm (mm) and Rd (mm) using the following formula: Mold shrinkage (%) = (Rd - Rm) / Rd x 100

[0160] (Measurement of Water Absorption) Using a transfer molding machine (Technomarushi Co., Ltd.), a disk-shaped molded product (diameter 50 mm x thickness 3 mm) was obtained under conditions of a mold temperature of 175°C, a molding time of 120 seconds, and a molding pressure of 6.9 MPa. The molded product was heated and cured at 175°C for 6 hours to obtain a cured product. Using a pressure cooker tester (Hirayama Seisakusho Co., Ltd.), the cured product was subjected to a pressure cooker treatment for 20 hours under conditions of a pressure of 2 atm (0.2 MPa), a temperature of 121°C, and a relative humidity of 100% RH. The mass of the cured product before and after the pressure cooker treatment was measured, and the water absorption (mass%) was calculated using the following formula: Water absorption (mass%) = ((mass after treatment - mass before treatment) / mass before treatment) x 100

[0161]

Claims

1. An encapsulating material for use in power semiconductor devices, comprising a compound having a vinylphenyl group.

2. The encapsulating material according to claim 1, wherein the compound having a vinylphenyl group includes a compound represented by the following formula (b3): (In the formula, B ｈｂ each independently represents a hydrogen atom, a group represented by the following formula (Ba), or a group represented by the following formula (Bz), ｈｂ is a group represented by the following formula (Bz). (In the formula, A represents an alkyl group, and * represents a bonding position.) (In the formula, * represents a bonding position.) 3. The encapsulating material according to claim 1 or 2, wherein the compound having a vinylphenyl group includes at least one selected from the group consisting of a polymer represented by the following formula (B3-3) and a polymer represented by the following formula (B3-7): (In the formula, B ｂ each independently represents a group represented by the following formula (Bz), and n represents a number from 3 to 5. The benzene ring may each independently have a substituent at a substitutable position. (In the formula, B ｂ each independently represents a group represented by the following formula (Bz), and n represents a number from 3 to 5. The benzene ring may each independently have a substituent at a substitutable position. (In the formula, * represents a bonding position.) 4. The sealing material according to any one of claims 1 to 3, wherein the compound having a vinylphenyl group includes a compound having a vinylphenylmethyl group.

5. The sealing material according to any one of claims 1 to 4, which contains a compound having a vinyl bond.

6. The sealing material according to claim 5, wherein the compound having a vinyl bond includes a compound having a maleimide group.

7. The sealing material according to any one of claims 1 to 6, wherein the power semiconductor device is a power semiconductor module.

8. A sealing material comprising a cured product obtained by using the sealing material according to any one of claims 1 to 7.

9. A power semiconductor device comprising: a power semiconductor element; and the encapsulant according to claim 8, which encapsulates at least a portion of the power semiconductor element.

10. A power semiconductor module comprising a plurality of devices selected from the group consisting of power semiconductor elements and power semiconductor devices, and the encapsulant according to claim 8 for encapsulating at least a portion of the plurality of devices.

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