Resin composition, prepreg, metal foil with resin, laminate, printed wiring board, and semiconductor package

Abstract

Disclosed are: a resin composition which contains (A) a styrene-based elastomer that has a polar group, and (B) a thermosetting resin, wherein a cured product of the resin composition has a phase separation structure of a first phase that contains (A) the styrene-based elastomer that has a polar group and a second phase that contains a cured product of (B) the thermosetting resin; a prepreg which uses the resin composition; a metal foil with a resin; a laminate; a printed wiring board; and a semiconductor package.

Description

Resin composition, prepreg, resin-coated metal foil, laminate, printed wiring board, and semiconductor package

[0001] The present embodiment relates to a resin composition, a prepreg, a resin-coated metal foil, a laminate, a printed wiring board, and a semiconductor package.

[0002] With the rapid spread of information electronic devices, electronic devices are becoming smaller and thinner, and there is an increasing demand for higher density and higher functionality in printed wiring boards mounted on such electronic devices. Wiring board materials used in high-performance printed wiring boards are required to have heat resistance, electrical insulation, long-term reliability, adhesiveness, etc.

[0003] In substrates mounted with ceramic components such as semiconductor chips, cracks (hereinafter also referred to as "solder cracks") occur in the solder at the connection between the ceramic component and the substrate due to the difference in thermal expansion coefficient between the ceramic component and the substrate. Studies by the present inventors have shown that reducing the elastic modulus and increasing the elongation of the substrate are effective in suppressing the occurrence of solder cracks.

[0004] Patent Document 1 describes a resin composition that has low elasticity, high elongation, insulation reliability, heat resistance, and excellent adhesion to metal foil, the resin composition containing (A) an acrylic polymer and (B) a thermosetting resin, which forms a phase-separated structure of a first phase containing the (A) acrylic polymer and a second phase containing the (B) thermosetting resin, and the average domain diameter of the second phase is 20 μm or less.

[0005] International Publication No. 2017 / 195902

[0006] The technology of Patent Document 1 achieves a certain degree of low elastic modulus and high elongation, but in recent years, with the progress of finer BGA pitch and fillet-less solder, the demand for reliability of solder joints has become increasingly strict, and therefore there is a demand for even lower elastic modulus and higher elongation of substrates.

[0007] In view of the current situation, the present embodiment provides a resin composition that provides a cured product exhibiting a low elastic modulus and a high elongation percentage, and a prepreg, a resin-coated metal foil, a laminate, a printed wiring board, and a semiconductor package that use the resin composition.

[0008] As a result of extensive research, the present inventors have found that the resin composition of the present disclosure can achieve the above-mentioned object. The present disclosure includes the following embodiments [1] to

[13] . [1] A resin composition containing (A) a styrene-based elastomer having a polar group and (B) a thermosetting resin, wherein a cured product of the resin composition has a phase-separated structure consisting of a first phase containing the (A) styrene-based elastomer having a polar group and a second phase containing the (B) thermosetting resin. [2] The resin composition according to the above [1], wherein the (A) styrene-based elastomer having a polar group is a modified styrene-based elastomer having an N-substituted succinimide group in a side chain. [3] The resin composition according to the above [2], wherein the N-substituted succinimide group has a structure represented by the following formula (a1): [In formula (a1), X represents a monovalent organic group, and * represents a bonding site.] [4] The resin composition according to the above item [3], wherein X in formula (a1) represents a monovalent organic group having one or more selected from the group consisting of an isocyanate group, a hydroxyl group, a carboxyl group, a silanol group, a thiol group, a sulfo group, a phosphate group, a cyclic ether group, a carbonate group, a nitrile group, a (meth)acryloyl group, a vinyl group, a maleimide group, an imidazole group, an oxazoline group, a benzotriazole group, and a benzoxazine group. [5] The resin composition according to any one of the above items [2] to [4], wherein the N-substituted succinimide group has a structure represented by the following formula (a2) or (a3): [In formula (a2), X Ａ１ represents a residue of an amine compound having a hydroxyl group, and * represents a bond. Ａ２indicates a residue of a diamine compound, and * indicates a bonding site.] [6] The resin composition according to any one of [1] to [5] above, wherein the (B) thermosetting resin is an epoxy resin. [7] The resin composition according to any one of [1] to [6] above, wherein the content ratio of the (A) styrene-based elastomer having a polar group to the (B) thermosetting resin [(A) component:(B) component] is 5:95 to 70:30 by mass. [8] The resin composition according to any one of [1] to [7] above, wherein the phase-separated structure is a sea-island structure, the sea phase being the first phase and the island phase being the second phase. [9] A resin-coated metal foil having a metal foil and a resin layer containing a resin composition provided on one surface of the metal foil, wherein the resin composition contains the resin composition according to any one of [1] to [8] above or a semi-cured product of the resin composition.

[10] A prepreg containing the resin composition according to any one of [1] to [8] above or a semi-cured product of the resin composition.

[11] A laminate having a cured product of the resin composition according to any one of [1] to [8] above and a metal foil.

[12] A printed wiring board having a cured product of the resin composition according to any one of [1] to [8] above.

[13] A semiconductor package having the printed wiring board according to

[12] above and a semiconductor element.

[0009] According to the present embodiment, it is possible to provide a resin composition that provides a cured product exhibiting a low elastic modulus and a high elongation percentage, and a prepreg, a resin-coated metal foil, a laminate, a printed wiring board, and a semiconductor package that use the resin composition.

[0010] In the numerical ranges described herein, the upper or lower limit of the numerical range may be replaced with the values ​​shown in the examples. Furthermore, the lower and upper limits of a numerical range can be arbitrarily combined with the lower or upper limit of another numerical range. In the expression "AA to BB," the values ​​AA and BB at both ends are included as the lower and upper limits of the numerical range, respectively. In this specification, for example, "10 or more" means 10 and a value greater than 10, and this also applies when the numerical values ​​differ. Furthermore, for example, "10 or less" means a value less than 10 and a value less than 10, and this also applies when the numerical values ​​differ. Furthermore, unless otherwise specified, each component and material exemplified herein may be used alone or in combination of two or more types. In this specification, when multiple substances corresponding to each component are present in the resin composition, the content of each component in the resin composition refers to the total amount of the multiple substances present in the resin composition, unless otherwise specified.

[0011] In this specification, "resin component" refers to all components of the solid content constituting the resin composition, excluding inorganic compounds such as inorganic fillers, which will be described later. In this specification, "solid content" refers to components other than the solvent, and components that are liquid at 25°C are also considered to be solid content. The expression "containing XX" described in this disclosure may mean that XX is contained in a reacted state if XX is reactive, or may simply mean that XX is contained as is, or may include both of these aspects. Any combination of the items described in this specification is also included in this disclosure and this embodiment.

[0012] [Resin Composition] The resin composition of the present embodiment is a resin composition containing (A) a styrene-based elastomer having a polar group and (B) a thermosetting resin, and a cured product of the resin composition has a phase-separated structure of a first phase containing the (A) styrene-based elastomer having a polar group and a second phase containing a cured product of the (B) thermosetting resin.

[0013] The reason why the cured product of the resin composition of this embodiment exhibits low modulus and high elongation is unclear, but is speculated as follows. The use of a highly flexible elastomer is thought to be an effective method for achieving a low modulus and high elongation in the cured product. However, it has been difficult to form a good cured product with typical elastomers due to their low affinity with thermosetting resins. In contrast, the styrene-based elastomer (A) having polar groups contained in the resin composition of this embodiment not only possesses high flexibility due to the elastomer but also has a moderate affinity with the thermosetting resin (B) due to the introduction of polar groups. Therefore, it is thought that the cured product having a phase-separated structure formed from the styrene-based elastomer (A) having polar groups and the thermosetting resin (B) effectively exhibits the characteristics of both the elastomer and the thermosetting resin, resulting in a low modulus and high elongation. Below, each component contained in the resin composition of this embodiment is described.

[0014] <(A) Styrene-based elastomer having a polar group> The component (A) is not particularly limited as long as it is a styrene-based elastomer having a polar group. As the component (A), one type may be used alone, or two or more types may be used in combination.

[0015] Component (A) has a structural unit derived from a styrene-based compound. Examples of the styrene-based compound include styrene; and alkyl-substituted styrenes such as α-methylstyrene, o-methylstyrene, m-methylstyrene, and p-methylstyrene. The number of carbon atoms in the alkyl group of the alkyl-substituted styrene is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 or 2. The structural unit derived from the styrene-based compound may be one type alone, or two or more types.

[0016] The content of structural units derived from styrene-based compounds in component (A) (hereinafter also referred to as the "styrene content") is preferably 5 to 60 mass%, more preferably 10 to 50 mass%, and even more preferably 20 to 40 mass%.

[0017] The component (A) may contain a structural unit derived from a styrene-based compound, and the component (A) is preferably a copolymer having a structural unit derived from a styrene-based compound and a structural unit derived from a conjugated diene compound. Examples of conjugated diene compounds include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 1,3-pentadiene (piperylene), 1-phenyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3,4-dimethyl-1,3-hexadiene, and 4,5-diethyl-1,3-octadiene. Among these, from the viewpoints of availability and productivity, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. The structural unit derived from the conjugated diene compound may be one type alone or two or more types.

[0018] The copolymer having structural units derived from a styrene compound and structural units derived from a conjugated diene compound may be a hydrogenated styrene elastomer in which at least a portion of the structural units derived from the conjugated diene compound are hydrogenated, or may be an unhydrogenated styrene elastomer. However, from the viewpoint of achieving a low modulus of elasticity and high elongation of the cured product, a hydrogenated styrene elastomer is preferred. Examples of hydrogenated styrene elastomers include hydrogenated styrene-butadiene-styrene block copolymers (SEBS) and hydrogenated styrene-isoprene-styrene block copolymers. Among these, hydrogenated styrene-butadiene-styrene block copolymers (SEBS) are preferred from the viewpoint of achieving a low modulus of elasticity and high elongation of the cured product.

[0019] Component (A) has a polar group. In this embodiment, the term "polar group" refers to a group having polarity, and is preferably a group containing a heteroatom. The term "heteroatom" refers to all atoms other than carbon and hydrogen atoms. Examples of polar groups include imide groups, imino groups, amino groups, ammonium groups, amide groups, nitrile groups, hydroxyl groups, and carboxy groups. Among these, the polar group contained in component (A) is preferably a group containing one or more atoms selected from the group consisting of oxygen atoms and nitrogen atoms, more preferably a group containing oxygen atoms and nitrogen atoms, even more preferably an imide group, and even more preferably an N-substituted succinimide group, from the viewpoint of achieving a low modulus of elasticity and a high elongation of the cured product. The polar group may be present at the molecular terminal or on a side chain of component (A), but is preferably present on a side chain. From the viewpoint of achieving a low modulus of elasticity and a high elongation of the cured product, component (A) is preferably a modified styrene-based elastomer having an N-substituted succinimide group on a side chain.

[0020] A modified styrene-based elastomer having an N-substituted succinimide group in a side chain can be synthesized by reacting an acid anhydride group of a styrene-based elastomer modified with maleic anhydride (hereinafter also referred to as a "maleic anhydride-modified styrene-based elastomer") with a compound having an amino group.

[0021] The maleic anhydride-modified styrene elastomer may be produced by reacting maleic anhydride with a styrene elastomer not modified with maleic anhydride or a hydrogenated styrene elastomer not modified with maleic anhydride, or a commercially available product may be used.

[0022] The maleic anhydride-modified styrene elastomer can be synthesized, for example, by adding a radical generator to a mixture of a styrene elastomer not modified with maleic anhydride and maleic anhydride dissolved in a solvent under a nitrogen atmosphere, and then reacting them. The reaction temperature may be 20 to 150°C. After the reaction, it is preferable to remove unreacted maleic anhydride by extraction in order to prevent side reactions.

[0023] Examples of the radical generator that can be used include organic peroxides and azo compounds. Examples of organic peroxides include dicumyl peroxide, benzoyl peroxide, 2-butanone peroxide, tert-butyl perbenzoate, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, bis(tert-butylperoxyisopropyl)benzene, and tert-butyl hydroperoxide. Examples of azo compounds include 2,2'-azobis(2-methylpropanenitrile), 2,2'-azobis(2-methylbutanenitrile), and 1,1'-azobis(cyclohexanecarbonitrile). One type of radical generator may be used alone, or two or more types may be used in combination.

[0024] Examples of solvents include butyl cellosolve, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, xylene, mesitylene, methoxyethyl acetate, ethoxyethyl acetate, butoxyethyl acetate, and ethyl acetate. These may be used alone or in combination of two or more. Among these, toluene, xylene, and propylene glycol monomethyl ether are preferred from the viewpoint of solubility.

[0025] The acid value of the maleic anhydride-modified styrene elastomer is preferably 20 to 120 mgKOH / g, more preferably 25 to 100 mgKOH / g, still more preferably 30 to 90 mgKOH / g, and particularly preferably 35 to 80 mgKOH / g.

[0026] The weight average molecular weight (Mw) of the maleic anhydride-modified styrene elastomer is preferably 20,000 to 120,000, more preferably 30,000 to 110,000, still more preferably 40,000 to 100,000, and particularly preferably 50,000 to 80,000.

[0027] The amino group-containing compound to be reacted with the maleic anhydride-modified styrene-based elastomer is not particularly limited as long as it has one or more amino groups. Examples of the amino group-containing compound include amine compounds having a hydroxyl group, amine compounds having an isocyanate group, amine compounds having a carboxyl group, amine compounds having a silanol group, amine compounds having a thiol group, amine compounds having a sulfo group, amine compounds having a phosphate group, amine compounds having a vinyl group, amine compounds having a (meth)acryloyl group, amine compounds having a nitrile group, amine compounds having a cyclic ether group, and diamine compounds having two amino groups. In this specification, the term "(meth)acryloyl group" refers to an acryloyl group or a methacryloyl group. The amino group-containing compound may be used alone or in combination of two or more.

[0028] The N-substituted succinimide group contained in the modified styrene-based elastomer having an N-substituted succinimide group in the side chain may have a structure represented by the following formula (a1).

[0029]

[0030] In formula (a1), X represents a monovalent organic group, and * represents a bonding site. Examples of X include monovalent organic groups having one or more selected from the group consisting of an isocyanate group, a hydroxyl group, a carboxyl group, a silanol group, a thiol group, a sulfo group, a phosphate group, a cyclic ether group, a carbonate group, a nitrile group, a (meth)acryloyl group, a vinyl group, a maleimide group, an imidazole group, an oxazoline group, a benzotriazole group, and a benzoxazine group. From the viewpoints of reactivity, curability, heat resistance, and compatibility, X may be a monovalent organic group having one or more selected from the group consisting of an isocyanate group, a hydroxyl group, a carboxyl group, a maleimide group, and a benzoxazine group, or may be a monovalent organic group having an isocyanate group, a hydroxyl group, a carboxyl group, a maleimide group, or a benzoxazine group, or may be a monovalent organic group having a hydroxyl group or a maleimide group.

[0031] The N-substituted succinimide group may have a structure represented by the following formula (a2) or (a3):

[0032]

[0033] In formula (a2), X Ａ１ represents a residue of an amine compound having a hydroxyl group, and * represents a bond. Ａ２ indicates a residue of a diamine compound, and * indicates a bond. The residue refers to a group (structure) remaining in the raw material component after removing the functional group used for bonding.

[0034] The modified styrene elastomer having a group having a structure represented by formula (a2) may be a reaction product of a styrene elastomer modified with maleic anhydride and an amine compound having a hydroxyl group. Examples of the amine compound having a hydroxyl group include amines having an alcoholic hydroxyl group such as hydroxyethylamine, and amines having a phenolic hydroxyl group such as tyramine and dopamine.

[0035] The modified styrene-based elastomer having a group having a structure represented by formula (a3) ​​may be a reaction product of a styrene-based elastomer modified with maleic anhydride, a diamine compound, and maleic anhydride. Examples of the diamine compound include aliphatic diamines such as polyoxypropylene diamine, and aromatic diamines such as 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ketone, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane, and 9,9-bis(4-aminophenyl)fluorene.

[0036] From the viewpoint of achieving a low modulus of elasticity and a high elongation of the cured product, the component (A) is preferably a succinimide-modified styrene-based elastomer having an ethanolic hydroxyl group, a succinimide-modified styrene-based elastomer having a phenolic hydroxyl group, or a succinimide-modified styrene-based elastomer having a maleimide group.

[0037] The succinimide-modified styrene elastomer having an ethanolic hydroxyl group is not particularly limited, but is preferably one having a succinimide group having an ethanolic hydroxyl group represented by the following formula (a2').

[0038] (* indicates a joint.)

[0039] The succinimide-modified styrene-based elastomer having a phenolic hydroxyl group is not particularly limited, but is preferably one having a succinimide group having a phenolic hydroxyl group represented by the following formula (a2'').

[0040] (* indicates a joint.)

[0041] The succinimide-modified styrene-based elastomer having a maleimide group is not particularly limited, but is preferably one having a succinimide group having a maleimide group represented by the following formula (a3').

[0042] (m represents the number of repeating units of the structure in parentheses. * represents the bond.)

[0043] In view of solubility, m in formula (a3') is preferably an integer of 1 to 50, more preferably an integer of 1 to 30, and even more preferably an integer of 1 to 10.

[0044] (Weight Average Molecular Weight (Mw) of Component (A)) From the viewpoint of achieving a low modulus of elasticity and high elongation of the cured product, the weight average molecular weight (Mw) of component (A) is preferably 20,000 to 120,000, more preferably 30,000 to 110,000, even more preferably 40,000 to 100,000, and particularly preferably 50,000 to 80,000.

[0045] (Solubility Parameter (SP Value) of Component (A)) The solubility parameter (hereinafter also referred to as "SP value") of component (A) is preferably 8.0 to 15.0, more preferably 9.0 to 14.0, even more preferably 9.5 to 12.0, and particularly preferably 9.7 to 11.0. When the SP value of component (A) is within the above range, the affinity with the thermosetting resin (B) becomes appropriate, and a good phase-separated structure is easily formed. As a result, it tends to be easier to obtain a cured product with a lower elastic modulus and a higher elongation while maintaining good heat resistance, mechanical properties, electrical insulation reliability, etc.

[0046] In this embodiment, the SP value can be calculated by the Fedors method. In the Fedors method, the total molar cohesive energy and the total molar molar volume are calculated by adding up the molar cohesive energy and the molar molecular volume of each functional group shown in Table 1 based on the structure of the material, and the SP value is calculated by the following formula (1).

[0047]

[0048] SP value (δ ｉ ) = (ΔE ｉ / ΔV ｉ ) １／２ (1) (where ΔE ｉ is the total molar cohesive energy, ΔV ｉ indicates the total molar volume.)

[0049] For example, when the SP value of acetone is calculated by the above method, it is as follows: Acetone has the structural formula: CH ３ —C(═O)—CH ３ Number of members: CH ３ 2 C=O 1 C=O, and from Table 1, the total molar cohesive energy (ΔE ｉ ): (1125 x 2) + (4150 x 1) = 6400 Total molar volume (ΔV ｉ ): (33.5 × 2) + (10.8 × 1) = 77.8, and applying this to formula (1), the SP value (δ ｉ ) = (ΔE ｉ / ΔV ｉ )１／２ = (6400 / 77.8) １／２ The SP value is calculated as =9.07.

[0050] (Content of Component (A)) The content of component (A) in the resin composition of this embodiment is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, even more preferably 12 to 35 parts by mass, and particularly preferably 15 to 25 parts by mass, per 100 parts by mass of the solid content in the resin composition. When the content of component (A) is within the above range, it tends to be easier to obtain a cured product with a lower elastic modulus and a higher elongation while maintaining good heat resistance, mechanical properties, electrical insulation reliability, etc.

[0051] <(B) Thermosetting Resin> The resin composition of the present embodiment contains a thermosetting resin as component (B). One type of (B) thermosetting resin may be used alone, or two or more types may be used in combination.

[0052] Examples of the (B) thermosetting resin include epoxy resins, maleimide resins, modified polyphenylene ether resins, phenolic resins, polyimide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, melamine resins, etc. Among these, epoxy resins, maleimide resins, phenolic resins, polyimide resins, cyanate resins, and isocyanate resins are preferred, and epoxy resins are more preferred, from the viewpoint that, when used in combination with component (A), a cured product having a lower elastic modulus and a higher elongation percentage can be more easily obtained while maintaining good heat resistance, mechanical properties, electrical insulation reliability, etc.

[0053] (Epoxy Resin) As the epoxy resin, an epoxy resin having two or more epoxy groups in one molecule is preferred. Examples of epoxy resins include bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, tetrabromobisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and bisphenol S-type epoxy resins; novolac-type epoxy resins such as bisphenol A novolac-type epoxy resins, bisphenol F novolac-type epoxy resins, phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, biphenyl novolac-type epoxy resins, and naphthol novolac-type epoxy resins; aralkyl-type epoxy resins such as phenol aralkyl-type epoxy resins, biphenyl aralkyl-type epoxy resins, and naphthol aralkyl-type epoxy resins; stilbene-type epoxy resins; naphthylene ether-type epoxy resins; biphenyl-type epoxy resins; dihydroanthracene-type epoxy resins; epoxy resins containing a saturated dicyclopentadiene skeleton; cyclohexanedimethanol-type epoxy resins; spiro ring-containing epoxy resins; heterocyclic epoxy resins; alicyclic epoxy resins; aliphatic linear epoxy resins; and rubber-modified epoxy resins. Among these, from the viewpoints of the heat resistance and flame retardancy of the cured product and compatibility with component (A), bisphenol-type epoxy resins and aralkyl-type epoxy resins are preferred, and bisphenol A-type epoxy resins, tetrabromobisphenol A-type epoxy resins and biphenylaralkyl-type epoxy resins are more preferred.

[0054] The epoxy equivalent of the epoxy resin is preferably 100 to 600 g / eq, more preferably 200 to 500 g / eq, and even more preferably 250 to 450 g / eq. The epoxy equivalent is the mass (g / eq) of the epoxy resin per epoxy group, and can be measured according to the method specified in JIS K 7236:2001.

[0055] (SP Value of (B) Thermosetting Resin) The SP value of the (B) thermosetting resin is preferably 8.5 to 16.0, more preferably 9.5 to 15.0, even more preferably 10.0 to 13.0, and particularly preferably 10.5 to 12.0. When the SP value of the (B) thermosetting resin is within the above range, the affinity with the (A) component becomes appropriate, and a good phase-separated structure is easily formed. As a result, it tends to be easier to obtain a cured product with a lower elastic modulus and a higher elongation while maintaining good heat resistance, mechanical properties, electrical insulation reliability, etc.

[0056] (Content of (B) Thermosetting Resin) The content of the (B) thermosetting resin in the resin composition of this embodiment is preferably 10 to 80 parts by mass, more preferably 20 to 70 parts by mass, even more preferably 30 to 60 parts by mass, and particularly preferably 40 to 50 parts by mass, per 100 parts by mass of the solid content in the resin composition. When the content of the (B) thermosetting resin is within the above range, it tends to be easier to obtain a cured product with a lower elastic modulus and a higher elongation while maintaining good heat resistance, mechanical properties, electrical insulation reliability, etc.

[0057] (Content Ratio of Component (A) to Component (B)) In the resin composition of this embodiment, the content ratio of component (A) to component (B) [component (A) : component (B)] is preferably 5:95 to 70:30 by mass, more preferably 10:90 to 50:50, even more preferably 20:80 to 40:60, and particularly preferably 25:75 to 35:65. When the content ratio [component (A) : component (B)] is within the above range, a cured product with a lower elastic modulus and a higher elongation tends to be obtained more easily while maintaining good heat resistance, mechanical properties, electrical insulation reliability, and the like.

[0058] <(C) Curing Agent> The resin composition of the present embodiment may contain a (C) curing agent as needed. The (C) curing agent may be used alone or in combination of two or more types.

[0059] As the (C) curing agent, a known one can be used. When an epoxy resin is used as the (B) thermosetting resin, examples of the curing agent include phenolic resins such as phenol novolac resin, cresol novolac resin, naphthol cresol novolac resin, bisphenol A novolac resin, and biphenyl novolac phenolic resin; amine-based curing agents such as dicyandiamide, diaminodiphenylmethane, and diaminodiphenylsulfone; acid anhydride curing agents such as pyromellitic anhydride, trimellitic anhydride, and benzophenone tetracarboxylic acid; and mixtures thereof. Among these, phenolic resins are preferred, and naphthol cresol novolac resins are more preferred.

[0060] When the resin composition of the present embodiment contains a (C) curing agent, the content of the (C) curing agent is, from the viewpoint of obtaining good curability, preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 3 to 10 parts by mass, per 100 parts by mass of the solid content in the resin composition.

[0061] When the resin composition of the present embodiment contains an epoxy resin and a phenolic resin, the molar ratio of the total amount of phenolic hydroxyl groups derived from the phenolic resins contained in the resin composition of the present embodiment to the total amount of epoxy groups derived from the epoxy resins contained in the resin composition of the present embodiment (phenolic hydroxyl groups / epoxy groups) is preferably 0.1 to 1.0, more preferably 0.15 to 0.7, and even more preferably 0.2 to 0.4.

[0062] When the resin composition of this embodiment contains a curing agent (C), the content ratio of the component (A) to the components (B) and (C) in the resin composition of this embodiment [component (A) : component (B) and component (C)] is preferably 5:95 to 70:30 by mass, more preferably 10:90 to 50:50, even more preferably 20:80 to 40:60, and particularly preferably 25:75 to 35:65. When the content ratio [component (A) : component (B) and component (C)] is within the above range, a cured product with a lower elastic modulus and a higher elongation tends to be obtained more easily while maintaining good heat resistance, mechanical properties, electrical insulation reliability, etc.

[0063] <(D) Inorganic Filler> The resin composition of this embodiment may contain (D) an inorganic filler. By containing (D) an inorganic filler in the resin composition of this embodiment, the low thermal expansion, heat resistance, and flame retardancy of the cured product tend to be improved. One type of (D) inorganic filler may be used alone, or two or more types may be used in combination.

[0064] (D) Examples of inorganic fillers include silica, alumina, titanium oxide, mica, beryllia, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, clay, talc, aluminum borate, and silicon carbide. Among these, from the viewpoint of low thermal expansion, heat resistance, and flame retardancy, silica, alumina, mica, and talc are preferred, silica and alumina are more preferred, and silica is even more preferred. Examples of silica include crushed silica, fumed silica, and fused silica (fused spherical silica). (D) Inorganic fillers may be surface-treated with a surface treatment agent such as a silane coupling agent in order to improve dispersibility and adhesion to organic components.

[0065] (D) Average particle diameter of inorganic filler (D ５０ From the viewpoint of dispersibility of the inorganic filler (C) and fine wiring properties, the average particle diameter (D) of the inorganic filler (D) is preferably 0.1 to 10 μm, more preferably 0.2 to 1 μm, and even more preferably 0.3 to 0.8 μm. ５０ ) is the particle diameter at the point corresponding to 50% volume when a cumulative frequency distribution curve of particle diameters is calculated assuming the total volume of the particles to be 100%. The average particle diameter of (D) inorganic filler can be measured, for example, with a particle size distribution measuring device using a laser diffraction scattering method. The shape of (D) inorganic filler can be, for example, spherical or crushed, with spherical being preferred.

[0066] (Content of (D) Inorganic Filler) When the resin composition of the present embodiment contains the (D) inorganic filler, the content of the (D) inorganic filler is, from the viewpoints of the thermal expansion coefficient, heat resistance, and flame retardancy, preferably 5 to 80 parts by mass, more preferably 10 to 60 parts by mass, still more preferably 15 to 50 parts by mass, and particularly preferably 20 to 40 parts by mass, relative to 100 parts by mass of the solid content in the resin composition.

[0067] <(E) Curing Accelerator> The resin composition of this embodiment may contain a curing accelerator (E). By containing the curing accelerator (E), the resin composition of this embodiment tends to have improved curability and better heat resistance, conductor adhesion, etc. One type of (E) curing accelerator may be used alone, or two or more types may be used in combination.

[0068] Examples of the (E) curing accelerator include amine-based curing accelerators, imidazole-based curing accelerators, phosphorus-based curing accelerators, organometallic salts, acidic catalysts, and organic peroxides. In this embodiment, imidazole-based curing accelerators are not classified as amine-based curing accelerators. Examples of the amine-based curing accelerator include amine compounds having primary to tertiary amines, such as triethylamine, pyridine, tributylamine, dicyandiamide, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane; and quaternary ammonium compounds. Examples of the imidazole-based curing accelerator include imidazole compounds such as methylimidazole, 2-phenylimidazole, 2-undecylimidazole, and isocyanate-masked imidazole (e.g., an addition reaction product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole). Examples of phosphorus-based curing accelerators include tertiary phosphines such as triphenylphosphine; and quaternary phosphonium compounds such as the addition product of p-benzoquinone and tri-n-butylphosphine. Examples of organic metal salts include carboxylates of manganese, cobalt, zinc, and the like. Examples of acidic catalysts include p-toluenesulfonic acid. Examples of organic peroxides include dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3,2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butylperoxyisopropyl monocarbonate, and α,α'-di(t-butylperoxy)diisopropylbenzene. Among these, imidazole-based curing accelerators are preferred because they facilitate the achievement of good curability.

[0069] (Content of (E) Curing Accelerator) When the resin composition of the present embodiment contains the (E) curing accelerator, the content of the (E) curing accelerator is, from the viewpoint of the curability and storage stability of the resin composition, preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, still more preferably 0.1 to 3 parts by mass, and particularly preferably 0.2 to 1 part by mass, relative to 100 parts by mass of the (B) thermosetting resin.

[0070] <Other Optional Components> The resin composition of the present embodiment may further contain other optional components, such as resin materials other than the above components, flame retardants, antioxidants, heat stabilizers, antistatic agents, UV absorbers, pigments, colorants, lubricants, silane coupling agents, organic solvents, and other additives, as needed. Each of the other optional components may be used alone, or two or more may be used in combination. The content of the above optional components in the resin composition of the present embodiment is not particularly limited, and they may be used as needed within a range that does not impair the effects of the present embodiment. Furthermore, the resin composition of the present embodiment may not contain the above optional components, depending on the desired performance.

[0071] (Organic Solvent) The resin composition of this embodiment may contain an organic solvent from the viewpoint of handleability. In this specification, a resin composition containing an organic solvent may be referred to as a resin varnish. Examples of organic solvents include alcohol-based solvents such as ethanol, propanol, butanol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ether-based solvents such as tetrahydrofuran; aromatic hydrocarbon-based solvents such as toluene, xylene, and mesitylene; nitrogen-containing solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; sulfur-containing solvents such as dimethyl sulfoxide; and ester-based solvents such as γ-butyrolactone. Among these, from the viewpoint of solubility, alcohol-based solvents, ketone-based solvents, nitrogen-containing solvents, and aromatic hydrocarbon-based solvents are preferred, ketone-based solvents are more preferred, and methyl isobutyl ketone is even more preferred.

[0072] When the resin composition of this embodiment contains an organic solvent, the solids concentration of the resin composition of this embodiment containing an organic solvent is preferably 10 to 90% by mass, more preferably 30 to 80% by mass, and even more preferably 35 to 65% by mass. When the solids concentration is within the above range, the resin composition is easy to handle, and the impregnation into the substrate and the appearance of the produced prepreg are good. Furthermore, this makes it easy to adjust the solids concentration of the resin in the prepreg, as described below, and tends to make it easier to produce a prepreg having the desired thickness.

[0073] <Method for producing resin composition> The resin composition of this embodiment can be produced by mixing the respective components. At this time, the respective components may be dissolved or dispersed while stirring. The conditions such as the mixing order, temperature, and time are not particularly limited and may be set as desired depending on the types of raw materials, etc.

[0074] <Phase-separated structure of cured product of resin composition> The resin composition of this embodiment forms a phase-separated structure of a first phase containing (A) a styrene-based elastomer having a polar group and a second phase containing (B) a cured product of a thermosetting resin. Here, the phase-separated structure in this embodiment is a sea-island structure, a continuous spherical structure, a composite dispersed phase structure, or a co-continuous phase structure. These phase-separated structures are described in detail, for example, in "Polymer Alloy" (Polymer Alloy), p. 325 (1993) published by Tokyo Kagaku Dojin, and the continuous spherical structure is described in detail, for example, in Keizo Yamanaka and Takashi Iniue, POLYMER, Vol. 30, pp. 662 (1989). The phase-separated structure of the cured product of the resin composition of this embodiment may be any of a continuous spherical structure, a sea-island structure, a composite dispersed phase structure, or a co-continuous phase structure, but is preferably a sea-island structure from the viewpoints of ease of production, a low modulus of elasticity, and a high elongation. When the cured product of the resin composition of this embodiment has a sea-island structure, it is preferable that the sea phase is the first phase and the island phase is the second phase. If the component (A) has a reactive group before the resin composition is cured, the reactive group in the component (A) having the reactive group may be in a state where the reactive group has reacted during the curing process of the resin composition. That is, if the component (A) has a reactive group before the resin composition is cured, the styrene-based elastomer (A) having a polar group contained in the first phase may be the component (A) in which the reactive group is unreacted, or the component (A) in which the reactive group has reacted.

[0075] In the phase-separated structure possessed by the cured product of the resin composition of this embodiment, the average domain diameter of the second phase is preferably 0.1 to 20.0 μm, more preferably 0.3 to 10.0 μm, even more preferably 0.5 to 8.0 μm, still more preferably 1.0 to 7.0 μm, even more preferably 1.5 to 6.0 μm, still more preferably 2.0 to 5.5 μm, even more preferably 2.2 to 5.0 μm, and particularly preferably 2.5 to 4.5 μm. When the average domain diameter of the second phase is within the above range, it tends to be easier to obtain a cured product with a lower elastic modulus and higher elongation while maintaining good heat resistance, mechanical properties, electrical insulation reliability, etc.

[0076] The average domain diameter of the second phase can be measured, for example, when the phase-separated structure is a continuous spherical structure, a sea-island structure, or a composite dispersed phase structure, by observing the cross-sectional structure of the cured product obtained from the resin composition of this embodiment with a scanning electron microscope (SEM), measuring the maximum width of each of 100 second-phase domains, and calculating the average value. When the phase-separated structure is a bicontinuous structure, 100 arbitrary points are identified in the second-phase domain, and the vertical and horizontal domain diameters on the SEM photograph are measured at each point, and the average value of the smaller domain diameters is calculated to be the average domain diameter. More specifically, the average domain diameter of the second phase can be measured by the method described in the Examples. The cured product of the resin composition for measuring the average domain diameter of the second phase can be cured, for example, at 200°C for 60 minutes at a pressure of 4 MPa, specifically, under the conditions described in the Examples.

[0077] The phase separation structure can be adjusted by, for example, controlling the type of resin, the difference in SP value between component (A) and component (B), the type of curing accelerator, and curing conditions such as reaction temperature. For example, methods for adjusting the average domain size of the second phase to be small include selecting a component (B) with a high SP value, and further selecting a component (A) to be combined with component (B) that has an SP value close to that of component (B). The absolute value of the difference in SP value between component (A) and component (B) is preferably 0.1 to 9.0, more preferably 0.2 to 7.0, even more preferably 0.3 to 5.0, and particularly preferably 0.4 to 4.5. The absolute value of the difference in SP value between component (A) and component (B) is preferably adjusted depending on the type of component (B) selected. For example, when the SP value of component (B) is 13.5 or more and 16.0 or less, the absolute value of the difference in SP value between component (A) and component (B) is preferably 1.0 to 9.0, more preferably 1.5 to 7.0, even more preferably 2.0 to 5.0, and particularly preferably 3.0 to 4.5. When the SP value of component (B) is 8.5 or more and less than 13.5, the absolute value of the difference in SP value between component (A) and component (B) is preferably 0.1 to 5.0, more preferably 0.2 to 3.0, even more preferably 0.3 to 1.5, and particularly preferably 0.4 to 1.2. When the absolute value of the difference in SP value between component (A) and component (B) is within the above range, it tends to be easier to obtain a cured product with a lower elastic modulus and a higher elongation while maintaining good heat resistance, mechanical properties, electrical insulation reliability, etc.

[0078] <Storage modulus of cured product at 25°C> The storage modulus of the cured product of the resin composition of this embodiment is preferably 1.5 × 10 ９ Pa or less, more preferably 1.0 × 10 ９ Pa or less, more preferably 0.7 × 10 ９ Pa or less, and even more preferably 0.5 × 10 ９ Pa or less, particularly preferably 0.45 × 10 ９When the storage modulus at 25°C of the cured product is the above upper limit or less, the occurrence of solder cracks tends to be more easily suppressed. Furthermore, from the viewpoint of improving the mechanical strength of the cured product, the storage modulus at 25°C of the cured product of the resin composition of this embodiment is 0.01 × 10 ９ Pa or more, and ９ Pa or more, and ９ Pa or more, and ９ Pa or more, and ９ The storage modulus at 25°C of the cured product can be measured by the method described in the examples.

[0079] <Tensile elongation at 25°C of cured product> The tensile elongation at 25°C of the cured product of the resin composition of this embodiment is preferably 4.0% or more, more preferably 4.5% or more, even more preferably 5.0% or more, even more preferably 6.0% or more, and particularly preferably 7.0% or more. When the tensile elongation at 25°C of the cured product is equal to or greater than the above lower limit, the occurrence of solder cracks tends to be more easily suppressed. Furthermore, from the viewpoint of improving the heat resistance, mechanical strength, etc. of the cured product, the tensile elongation at 25°C of the cured product of the resin composition of this embodiment may be 20.0% or less, 15.0% or less, 12.0% or less, 11.0% or less, or 10.5% or less. The tensile elongation at 25°C of the cured product can be measured by the method described in the examples.

[0080] [Prepreg] The prepreg of the present embodiment is a prepreg containing the resin composition of the present embodiment or a semi-cured product of the resin composition. The prepreg of the present embodiment contains, for example, the resin composition of the present embodiment or a semi-cured product of the resin composition and a substrate.

[0081] The substrate contained in the prepreg of this embodiment can be, for example, a known substrate used in various laminates for electrical insulating materials. Examples of substrate materials include inorganic fibers such as E-glass, D-glass, S-glass, and Q-glass; organic fibers such as polyimide, polyester, and tetrafluoroethylene; and mixtures thereof. The substrate may have a shape such as woven fabric, nonwoven fabric, roving, chopped strand mat, or surfacing mat. Among these, glass cloth is preferred. From the viewpoints of thinning and ease of handling, the thickness of the substrate is preferably 10 to 100 μm, more preferably 20 to 50 μm.

[0082] The prepreg of this embodiment can be produced, for example, by impregnating or applying the resin composition of this embodiment to a substrate, and then heating and drying the composition to B-stage. The temperature and time for heating and drying can be, for example, 50 to 200°C and 1 to 30 minutes, from the viewpoints of productivity and appropriately B-staging the resin composition of this embodiment.

[0083] The content of the resin composition in the prepreg of the present embodiment is preferably 20 to 90% by mass, more preferably 30 to 85% by mass, and even more preferably 40 to 80% by mass, from the viewpoint of easily obtaining good moldability.

[0084] [Resin-Coated Metal Foil] The resin-coated metal foil of this embodiment is a resin-coated metal foil having a metal foil and a resin layer containing a resin composition provided on one side of the metal foil, wherein the resin composition contains the resin composition of this embodiment or a semi-cured product of the resin composition. The resin-coated metal foil of this embodiment can be produced by applying the resin composition of this embodiment to a metal foil and semi-curing (B-staging) the resin composition. Suitable conditions for the temperature and time of heat drying are the same as those suitable for heat drying in the prepreg manufacturing process of this embodiment. There are no particular restrictions on the method for applying the resin composition, and known coating machines such as die coaters, comma coaters, bar coaters, kiss coaters, and roll coaters can be used. Examples of metal foils for the resin-coated metal foil include copper foil and aluminum foil, but other metal foils can also be used. Among these, copper foil is preferred.

[0085] [Laminate] The laminate of the present embodiment is a laminate having a cured product of the resin composition of the present embodiment and a metal foil. Note that a laminate having a metal foil is sometimes called a metal-clad laminate.

[0086] Examples of metals for the metal foil include copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, and alloys containing one or more of these metal elements.

[0087] The laminate of this embodiment can be produced, for example, by placing metal foil on one or both sides of the prepreg of this embodiment, followed by hot-press molding to harden the prepreg. When hot-press molding, only one prepreg may be used, or two or more prepregs may be laminated together. For hot-press molding, for example, a multi-stage press, a multi-stage vacuum press, a continuous molding machine, an autoclave molding machine, or the like can be used. The hot-press molding conditions can be, for example, a temperature of 100 to 300°C, a time of 10 to 300 minutes, and a pressure of 1.5 to 5 MPa.

[0088] [Printed Wiring Board] The printed wiring board of this embodiment is a printed wiring board having a cured product of the resin composition of this embodiment. The printed wiring board of this embodiment can be produced, for example, by forming a conductor circuit on one or more materials selected from the group consisting of a cured product of the prepreg of this embodiment, a cured product of the resin film of this embodiment, and a laminate of this embodiment by a known method. Furthermore, a multilayer printed wiring board can also be produced by performing a multilayer adhesive process as necessary. The conductor circuit can be formed, for example, by appropriately performing drilling, metal plating, etching of metal foil, etc.

[0089] [Semiconductor Package] The semiconductor package of this embodiment is a semiconductor package including the printed wiring board of this embodiment and a semiconductor element. The semiconductor package of this embodiment can be manufactured, for example, by mounting a semiconductor chip, a memory, etc. on the printed wiring board of this embodiment by a known method.

[0090] The present embodiment will be specifically described below with reference to examples, although the present embodiment is not limited to the following examples.

[0091] In each example, the weight average molecular weight (Mw) was measured by the following method. It was 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-1, F-2, F-4, F-10, F-20, F-40) [manufactured by Tosoh Corporation, trade name]. The GPC measurement conditions are shown below. Apparatus: Pump: L-6200 type [manufactured by Hitachi High-Technologies Corporation] Detector: L-3300 type RI [manufactured by Hitachi High-Technologies Corporation] Column oven: L-655A-52 [manufactured by Hitachi High-Technologies Corporation] Column: Guard column; TSK Guard column HHR-L + column; TSKgel G4000HHR + TSKgel G2000HHR (all manufactured by Tosoh Corporation, trade names) Column size: 6.0 x 40 mm (guard column), 7.8 x 300 mm (column) Eluent: tetrahydrofuran Sample concentration: 30 mg / 5 mL Injection volume: 20 μL Flow rate: 1.00 mL / min Measurement temperature: 40°C

[0092] [Production Example 1: Production of succinimide-modified styrene-based elastomer (A-1) having ethanolic hydroxyl groups] 150 g of maleic anhydride-modified hydrogenated styrene-based elastomer (manufactured by Asahi Kasei Corporation, trade name "Tuftec M1913", weight average molecular weight (Mw) = 63,000, styrene content = 30% by mass) and 678.6 g of toluene were charged into a 1 L flask, and the temperature was raised to 80°C over approximately 0.5 hours with stirring, and then maintained at that temperature for 1 hour to dissolve the maleic anhydride-modified hydrogenated styrene-based elastomer. The temperature was then lowered to 40°C, and a solution of 2.0 g of ethanolamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) dissolved in 38 g of propylene glycol monomethyl ether (hereinafter referred to as PGME) was added dropwise. The temperature was then raised to 60°C over approximately 0.5 hours with stirring, and then maintained at that temperature for 1 hour. The temperature was then raised to 110°C in about 1 hour, and the temperature was maintained for 2 hours while circulating nitrogen, yielding a toluene solution of a succinimide-modified styrene-based elastomer (A-1) having an ethanolic hydroxyl group. The FT-IR spectrum of the component (A-1) was measured using a Fourier transform infrared spectrophotometer (manufactured by Shimadzu Corporation, trade name "IRSpirit"), revealing a peak at 1780 cm －１ The peak attributable to the acid anhydride group around 1700 cm disappeared. －１ It was confirmed that there was a peak near the peak due to the imide group. The component (A-1) has a succinimide group having an ethanolic hydroxyl group in the side chain. (* indicates a joint.)

[0093] [Production Example 2: Production of succinimide-modified styrene-based elastomer (A-2) having a phenolic hydroxyl group] 150 g of maleic anhydride-modified hydrogenated styrene-based elastomer (manufactured by Asahi Kasei Corporation, trade name "Tuftec M1913", weight average molecular weight (Mw) = 63,000, styrene content = 30% by mass) and 655.7 g of toluene were charged into a 1 L flask, and the temperature was raised to 80°C over approximately 0.5 hours with stirring, and then the temperature was maintained for 1 hour to dissolve the maleic anhydride-modified hydrogenated styrene-based elastomer. Next, the temperature was lowered to 40°C, and a solution of 4.5 g of tyramine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) dissolved in 85.5 g of PGME was added dropwise. Thereafter, the temperature was raised to 60°C over approximately 0.5 hours with stirring, and the temperature was maintained for 1 hour. The temperature was then raised to 110°C in about 1 hour, and the temperature was maintained for 2 hours while circulating nitrogen, yielding a toluene solution of a succinimide-modified styrene-based elastomer (A-2) having a phenolic hydroxyl group. The FT-IR spectrum of the component (A-2) was measured in the same manner as in Production Example 1, and a peak at 1780 cm －１ The peak attributable to the acid anhydride group around 1700 cm disappeared. －１ It was confirmed that there was a peak near the peak due to the imide group. The component (A-2) has a succinimide group having a phenolic hydroxyl group on the side chain. (* indicates a joint.)

[0094] [Production Example 3: Production of succinimide-modified styrene-based elastomer (A-3) having maleimide groups] 722 g of toluene and 150 g of maleic anhydride-modified hydrogenated styrene-based elastomer (manufactured by Asahi Kasei Corporation, trade name "Tuftec M1913", weight average molecular weight (Mw) = 63,000, styrene content = 30% by mass) were placed in a 1 L flask equipped with a condenser, a nitrogen inlet tube, a thermocouple, and a stirrer, and the temperature was raised to 80°C with stirring, and the temperature was maintained for 1.0 hour to dissolve the maleic anhydride-modified hydrogenated styrene-based elastomer. Next, the temperature in the flask was lowered to 30°C, and a solution of 6.6 g of polyoxypropylenediamine (manufactured by Huntsman, trade name "Jeffermine D230") dissolved in 6.6 g of toluene was added dropwise, and the mixture was stirred for 1.0 hour. Thereafter, 2.8 g of maleic anhydride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further incubated for 1.0 hour. After adding 0.53 g of p-toluenesulfonic acid, the temperature inside the flask was raised to the reflux temperature (approximately 110°C), and a dehydration cycloreaction reaction was carried out for 3.0 hours while circulating nitrogen, yielding a toluene solution of a succinimide-modified styrene-based elastomer (A-3) having maleimide groups. The FT-IR spectrum of component (A-3) was measured in the same manner as in Production Example 1, and a peak at 1780 cm was observed. －１ The peak attributable to the acid anhydride group around 1700 cm disappeared. －１ It was confirmed that there was a peak attributable to the imide group in the vicinity of the (A-3) component. １３ Measurement of the C-NMR spectrum (NMR apparatus: manufactured by Bruker) confirmed that two to three peaks attributable to the carbonyl carbon of the succinimide group and the carbonyl carbon of the maleimide group appeared in the region of 170 to 180 ppm. Note that the component (A-3) has a succinimide group with the following maleimide group in the side chain: (m １ is an integer from 1 to 10. * indicates a bond.)

[0095] [Production of Resin Composition] Examples 1 to 6, Comparative Examples 1 to 3 Of the components shown in Table 2, each component except for (E) curing accelerator was blended in the amounts shown in Table 2 (the values ​​in the table are parts by mass of solid content, and in the case of a solution or dispersion, are amounts converted to solid content), and dissolved in methyl isobutyl ketone. Then, (E) curing accelerator was blended in the amount shown in Table 2 to obtain a varnish with a solid content concentration of 40 mass%.

[0096] [Production of Prepreg] The varnish prepared above was impregnated into a glass cloth 1037 (manufactured by Asahi Schwebel Co., Ltd.) having a thickness of 0.028 mm, and then heated and dried at 140°C for 10 minutes to obtain a prepreg.

[0097] [Production of Resin-Coated Copper Foil] The varnish prepared above was applied to an electrolytic copper foil having a thickness of 18 μm (manufactured by Nippon Denkai Co., Ltd., product name "YGP-18") using a coater, and the foil was dried with hot air at 140°C for 6 minutes to produce a resin-coated copper foil having a resin composition layer thickness of 50 μm.

[0098] [Production of Copper-Clad Laminate] (Production of Double-Sided Copper-Clad Laminate Using Prepreg) Four sheets of the prepreg prepared above were stacked, and 18 μm-thick electrolytic copper foil (manufactured by Fukuda Metal Foil & Powder Co., Ltd., product name "CFT9L-UR-18") was stacked on both sides so that the adhesive surfaces faced the prepreg, and the laminate was molded under vacuum press conditions of 200° C., 60 minutes, and 4 MPa to produce a double-sided copper-clad laminate.

[0099] (Production of double-sided copper-clad laminate using resin-coated copper foil) Two resin-coated copper foils were stacked with the resin surfaces facing each other and molded under vacuum press conditions of 200°C for 60 minutes and 4 MPa to produce a double-sided copper-clad laminate.

[0100] [Evaluation Methods] Using the resin compositions, prepregs, resin-coated copper foils, and copper-clad laminates obtained by the above methods, evaluations were carried out according to the following methods. The results are shown in Table 2. For Comparative Examples 1 and 2, evaluations other than varnishability (compatibility of components) could not be carried out due to low compatibility of the components, so in Table 2, evaluation results other than varnishability (compatibility of components) are marked with "-".

[0101] (Varnish properties (compatibility of components)) The varnish prepared in each example was placed in a transparent container, and the appearance was visually observed after 24 hours. If the hue of the varnish was uniform and no sediment was found to have accumulated in the container, it was judged as "no separation," and if unevenness in the hue was found or sediment was found to have accumulated in the container, it was judged as "separation occurred."

[0102] (Varnish Properties (Viscosity)) The varnish prepared in each example was placed in a cup, and the temperature of the varnish was adjusted to 30°C using a water bath. Thereafter, the viscosity was measured using a BL-type viscometer (manufactured by Toki Sangyo Co., Ltd.) If the viscosity at 30°C was 800 mPa s or less, it was determined that there was no problem in producing a prepreg.

[0103] (Appearance of prepreg (presence or absence of aggregates)) The surface of the prepreg produced in each example was observed using a 20x magnifying glass to check for the presence or absence of aggregates. In Table 2, cases in which no aggregates were observed are marked "none".

[0104] (Storage modulus at 25°C) A double-sided copper-clad laminate prepared using a resin-coated copper foil was entirely etched, and the resulting laminate was cut into a width of 5 mm and a length of 30 mm. The storage modulus was measured at 25°C and a frequency of 10 Hz using a dynamic viscoelasticity measuring device (manufactured by UBM Co., Ltd.).

[0105] (Tensile elongation at 25°C) A double-sided copper-clad laminate prepared using a resin-coated copper foil was entirely etched, and the resulting laminate was cut into a width of 10 mm and a length of 100 mm. The tensile elongation was measured using an autograph (manufactured by Shimadzu Corporation) at a temperature of 25°C and a pulling rate of 1.0 mm / min.

[0106] (Heat Resistance) Double-sided copper-clad laminates prepared using the prepregs prepared in each example were cut into 50 mm squares to obtain test specimens. The test specimens were floated in a solder bath at 260°C, and the time elapsed from that point until bulging of the test specimen was visually observed was measured. The elapsed time was measured up to 300 seconds, and a time of 250 seconds or more was considered to be sufficient heat resistance. In Table 2, specimens in which no bulging was observed at 300 seconds were indicated as ">300."

[0107] (Average domain diameter of island phases) The cross section of the resin insulating layer of a double-sided copper-clad laminate produced from a resin-coated copper foil was smoothed with a microtome, lightly etched with a persulfate solution, and observed under an SEM. The maximum width of each of 100 island phase domains in the phase-separated structure was measured, and the average value was taken as the average domain diameter of the island phases. Note that the phase-separated structures of the cured materials obtained in Examples 1 to 6 were all sea-island structures, and scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) confirmed that component (A) formed the sea phase and component (B) formed the island phase.

[0108] (Electrical insulation reliability) Using a test pattern prepared by processing a double-sided copper-clad laminate made from prepreg so that the through-hole wall spacing was 350 μm, the insulation resistance of 400 holes for each sample was measured over time. The measurement conditions were an 85° C. / 85% RH atmosphere with 100 V applied, and the time until electrical breakdown occurred was measured. The measurement time was up to 2000 hours, and electrical insulation reliability was determined to be sufficient for 2000 hours or more. In Table 2, those samples that did not experience electrical breakdown at 2000 hours are indicated as “>2000.”

[0109]

[0110] The abbreviations for each material in Table 2 are as follows: [Component (A): Styrenic elastomer having a polar group] Styrene-based elastomer (A-1): Succinimide-modified styrene-based elastomer (A-1) having an ethanolic hydroxyl group, prepared in Production Example 1 Styrene-based elastomer (A-2): Succinimide-modified styrene-based elastomer (A-2) having a phenolic hydroxyl group, prepared in Production Example 2 Styrene-based elastomer (A-3): Succinimide-modified styrene-based elastomer (A-3) having a maleimide group, prepared in Production Example 3

[0111] [(A') Comparative Components] H1041: Styrene-based elastomer, product name, manufactured by Asahi Kasei Corporation, weight average molecular weight (Mw) = 73,300, styrene content = 30 mass% Acrylic polymer: product name "HAN5-M90S" manufactured by Negami Chemical Industrial Co., Ltd.

[0112] [Component (B): Thermosetting Resin] EPICRON 153: Tetrabromobisphenol A type epoxy resin, manufactured by DIC Corporation, trade name, epoxy equivalent 390 to 410 g / eq NC-3000-H: Biphenyl aralkyl type epoxy resin, manufactured by Nippon Kayaku Co., Ltd., trade name, epoxy equivalent 290 g / eq N-770: Phenol novolac type epoxy resin, manufactured by DIC Corporation, trade name, epoxy equivalent 183 to 193 g / eq

[0113] [Component (C): Curing agent] MEH-7000: naphthol cresol novolac resin, product name, manufactured by Meiwa Chemical Industry Co., Ltd., phenol hydroxyl group equivalent 139 g / eq KA-1165: cresol novolac resin, product name, manufactured by DIC Corporation, phenol hydroxyl group equivalent 119 g / eq

[0114] [Component (D): Inorganic filler] Spherical fused silica: average particle size 0.5 μm HK-001: aluminum hydroxide, product name manufactured by Kawai Lime Co., Ltd., average particle size 4.0 μm

[0115] [Component (E): Curing accelerator] 2-phenylimidazole

[0116] The results shown in Table 2 show that the cured products formed from the resin compositions of Examples 1 to 6 of this embodiment exhibit low modulus of elasticity and high elongation.

Claims

1. A resin composition containing (A) a styrene-based elastomer having a polar group and (B) a thermosetting resin, wherein the cured product of the resin composition has a phase-separated structure consisting of a first phase containing the (A) styrene-based elastomer having a polar group and a second phase containing the (B) thermosetting resin.

2. The resin composition according to claim 1, wherein (A) the styrene elastomer having a polar group is a modified styrene elastomer having an N-substituted succinimide group in the side chain.

3. The resin composition according to claim 2, wherein the N-substituted succinimide group has a structure represented by the following formula (a1): [In formula (a1), X represents a monovalent organic group, and * represents a bond.] 4. The resin composition according to claim 3, wherein X in formula (a1) is a monovalent organic group having at least one selected from the group consisting of an isocyanate group, a hydroxyl group, a carboxyl group, a silanol group, a thiol group, a sulfo group, a phosphate group, a cyclic ether group, a carbonate group, a nitrile group, a (meth)acryloyl group, a vinyl group, a maleimide group, an imidazole group, an oxazoline group, a benzotriazole group, and a benzoxazine group.

5. The resin composition according to claim 2, wherein the N-substituted succinimide group has a structure represented by the following formula (a2) or (a3): [In formula (a2), X Ａ１ represents a residue of an amine compound having a hydroxyl group, and * represents a bond. Ａ２ indicates a residue of a diamine compound, and * indicates a bond.] 6. The resin composition according to any one of claims 1 to 5, wherein the thermosetting resin (B) is an epoxy resin.

7. A resin composition according to any one of claims 1 to 5, wherein the content ratio of the (A) styrene-based elastomer having a polar group to the (B) thermosetting resin [(A) component:(B) component] is 5:95 to 70:30 by mass.

8. A resin composition according to any one of claims 1 to 5, wherein the phase-separated structure is a sea-island structure, the sea phase being the first phase, and the island phase being the second phase.

9. A resin-coated metal foil having a metal foil and a resin layer containing a resin composition provided on one surface of the metal foil, wherein the resin composition contains the resin composition according to any one of claims 1 to 5 or a semi-cured product of the resin composition.

10. A prepreg containing the resin composition according to any one of claims 1 to 5 or a semi-cured product of said resin composition.

11. A laminate comprising a cured product of the resin composition according to any one of claims 1 to 5 and a metal foil.

12. A printed wiring board having a cured product of the resin composition according to any one of claims 1 to 5.

13. A semiconductor package comprising the printed wiring board according to claim 12 and a semiconductor element.

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