Resin film, printed wiring board, and semiconductor package

Abstract

The present invention relates to a resin film, a printed wiring board using the same, and a semiconductor package, the resin film comprising: an insulating member-forming resin layer containing a first resin composition; and an undercoat layer-forming resin layer that is provided on one surface side of the insulating member-forming resin layer and contains a second resin composition, the first resin composition containing: (A) a thermosetting resin; (B) a compound that is liquid at 25 DEG C, has a reactive group, and has a molecular weight of 1000 or less; and (C) an inorganic filler.

Description

Technical Field

[0001] The present embodiment relates to a resin film, a printed wiring board, and a semiconductor package. Background Art

[0002] In recent years, due to the miniaturization and performance improvement of electronic devices, the wiring density and integration have been increasing in the field of printed wiring boards and semiconductor packages.

[0003] In these electronic devices, insulating materials such as thermosetting resins can be used as sealing materials for semiconductor chips and substrate materials for printed circuit boards. However, when mounting components, stress caused by the difference in thermal expansion coefficients between the insulating material and the semiconductor chip can sometimes become a problem. The stress generated here can cause warping of the semiconductor package, which is a major cause of reduced reliability.

[0004] Therefore, as a method of making the thermal expansion coefficient of the insulating material close to the thermal expansion coefficient of the semiconductor chip, a method of mixing an inorganic filler into the insulating material has been developed.

[0005] Patent document 1 discloses the following technology with the aim of providing a thermosetting resin composition having low dielectric loss tangent, low thermal expansion, excellent embedding property and flatness of wiring: a polybutadiene-based elastomer modified with an acid anhydride is added to a thermosetting resin composition containing an inorganic filler and a polyimide compound, wherein the polyimide compound has a structural unit derived from a maleimide resin having at least two N-substituted maleimide groups and a structural unit derived from a diamine compound.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-012747 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, as an insulating material, a thermosetting resin film containing a thermosetting resin etc. may be used. For example, this resin film may be formed into an insulating layer by curing while embedding a circuit of a circuit board, or may be used as a sealing material for a semiconductor chip.

[0011] The dielectric loss tangent, low thermal expansion, embedding property of wiring etc. of the thermosetting resin composition of patent documentation 1 are excellent, on the other hand, when increasing the thickness of resin film, cracks are sometimes produced.This problem particularly occurs easily when using the thermosetting resin that is easy to obtain high heat resistance and when using the inorganic filling material that helps low thermal expansion.In order to solve the above problems, it is effective to think that improving the flexibility of resin film.

[0012] As a method for improving the flexibility of resin film, it is possible to consider a method of making the resin film contain a small amount of organic solvents that can keep the degree of solid. However, the resin film containing a small amount of organic solvents sometimes produces gaps in the solidified material due to the volatilized organic solvent during heat curing, or has unevenness on the surface of the solidified material. In addition, since the organic solvent volatilizes during heat curing, it is also necessary to equip a safer working environment. The larger the thickness of the resin film, the more obvious these problems are, so it is expected to be improved.

[0013] In addition, metal plating is sometimes applied to the cured product of the resin film for forming a circuit. Therefore, the cured product of the resin film is required to have good plating properties that can form a plating layer without expansion, peeling, etc. However, according to the research of the present inventors, it is clear that in a resin film with improved flexibility, sufficient plating properties cannot sometimes be obtained.

[0014] In view of such a situation, the present embodiment aims to provide a resin film capable of forming a cured product having excellent plating properties, excellent flexibility, and capable of suppressing the generation of volatile components during heat curing, and a printed wiring board and a semiconductor package using the resin film.

[0015] Means for solving problems

[0016] The present inventors have studied to solve the above-mentioned problems, and as a result, have found that the problems can be solved by the present embodiment described below.

[0017] That is, this embodiment relates to the following [1] to

[14] .

[0018] [1] A resin film having:

[0019] an insulating member-forming resin layer comprising a first resin composition; and

[0020] The undercoat layer-forming resin layer is provided on one side of the insulating member-forming resin layer and contains a second resin composition.

[0021] The first resin composition contains: (A) a thermosetting resin; (B) a compound that is liquid at 25° C., has a reactive group and has a molecular weight of 1000 or less; and (C) an inorganic filler.

[0022] [2] The resin film according to [1] above, wherein the component (A) is one or more selected from a maleimide resin having one or more N-substituted maleimide groups and a derivative of the maleimide resin.

[0023] [3] The resin film according to the above [2], wherein the maleimide resin having one or more N-substituted maleimide groups is a maleimide resin having a condensed ring of an aromatic ring and an aliphatic ring in its molecular structure and having two or more N-substituted maleimide groups.

[0024] [4] The resin film according to any one of [1] to [3], wherein the component (B) has, as the reactive group, one or more selected from a functional group containing an ethylenically unsaturated bond, an epoxy group, a hydroxyl group, a carboxyl group and an amino group.

[0025] [5] The resin film according to any one of [1] to [4], wherein the component (B) has two or more of the reactive groups in one molecule.

[0026] [6] The resin film according to any one of [1] to [5], wherein the component (B) is a di(meth)acrylate.

[0027] [7] The resin film according to any one of [1] to [6], wherein the content of the component (B) is 0.5 to 20% by mass relative to the total solid content (100% by mass) of the first resin composition.

[0028] [8] The resin film according to any one of [1] to [7], wherein the second resin composition contains (H) an inorganic filler.

[0029] The content of the (H) inorganic filler in the second resin composition is smaller than the content of the (C) inorganic filler in the first resin composition.

[0030] [9] The resin film according to [8] above, wherein the second resin composition further comprises: (F) a thermosetting resin; and (G) a compound that is liquid at 25°C, has a reactive group and has a molecular weight of 1000 or less.

[0031]

[10] The resin film according to any one of [1] to [9] above, wherein the thickness of the insulating member-forming resin layer is 80 μm or more.

[0032]

[11] The resin film according to any one of [1] to

[10] above, wherein the thickness of the primer layer-forming resin layer is 0.2 to 20 μm.

[0033]

[12] The resin film according to any one of [1] to

[11] , wherein the mass reduction rate after heat drying at 170° C. for 30 minutes in an air atmosphere is 2.0 mass % or less.

[0034]

[13] A printed wiring board comprising a cured product of the resin film according to any one of [1] to

[12] .

[0035]

[14] A semiconductor package comprising a cured product of the resin film according to any one of [1] to

[12] .

[0036] Effects of the Invention

[0037] According to the present embodiment, a resin film capable of forming a cured product having excellent plating properties, excellent flexibility, and capable of suppressing generation of volatile components during heat curing, and a printed wiring board and a semiconductor package using the resin film can be provided. DETAILED DESCRIPTION

[0038] In the present specification, a numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the minimum value and the maximum value, respectively.

[0039] For example, a numerical range such as "X to Y" (X, Y are real numbers) refers to a numerical range greater than X and less than Y. Also, a description such as "greater than X" in this specification refers to X and a numerical value greater than X. In addition, a description such as "less than Y" in this specification refers to Y and a numerical value less than Y.

[0040] The lower limit and the upper limit of the numerical range described in the present specification can be arbitrarily combined with the lower limit or the upper limit of other numerical ranges, respectively.

[0041] In the numerical range described in the present specification, the lower limit value or the upper limit value of the numerical range may be replaced with the value shown in the Examples.

[0042] Unless otherwise specified, each component and material exemplified in the present specification may be used alone or in combination of two or more.

[0043] In the present specification, when there are plural substances corresponding to each component in the resin composition, the content of each component in the resin composition refers to the total amount of the plural substances present in the resin composition unless otherwise specified.

[0044] In this specification, "resin composition" refers to a mixture containing at least two or more components of resins, and when the resin is a thermosetting resin, it also includes a material in which the mixture is in a B-stage state. The type and content of each component in the resin composition in a B-stage state refer to the type and content of each component before the B-stage state is formed, that is, the type and amount of the component mixed when the resin composition is produced.

[0045] In this specification, when expressing "layer", in addition to a solid layer, a layer in which a part is island-shaped, a layer with holes, and a layer in which the interface with the adjacent layer is unclear are also included in the "layer".

[0046] In this specification, "solid content" refers to components other than solvents, and also includes substances that are liquid, syrupy, and waxy at room temperature. Here, in this specification, room temperature means 25°C.

[0047] In this specification, "(meth)acrylate" refers to "acrylate" and its corresponding "methacrylate". Similarly, "(meth)acrylic acid" refers to "acrylic acid" and its corresponding "methacrylic acid", and "(meth)acryloyl" refers to "acryloyl" and its corresponding "methacryloyl".

[0048] The "molecular weight" of a compound in this specification refers to a molecular weight that can be calculated from the structural formula when the compound is not a polymer but the structural formula of the compound can be determined, and refers to a number average molecular weight when the compound is a polymer.

[0049] The number average molecular weight in this specification refers to a value measured by gel permeation chromatography (GPC; Gal Permeation Chromatography) and converted to polystyrene. Specifically, the number average molecular weight in this specification can be measured by the method described in the Examples.

[0050] The mechanism of action described in this specification is a guess, and does not limit the mechanism by which the effect of the resin composition of the present embodiment is exerted.

[0051] Any combination of the matters described in this specification is also included in this embodiment.

[0052] [Resin film]

[0053] The resin film of this embodiment has:

[0054] an insulating member-forming resin layer comprising a first resin composition; and

[0055] The undercoat layer-forming resin layer is provided on one side of the insulating member-forming resin layer and contains a second resin composition.

[0056] The first resin composition contains: (A) a thermosetting resin; (B) a compound that is liquid at 25° C., has a reactive group and has a molecular weight of 1000 or less; and (C) an inorganic filler.

[0057] In addition, in this specification, each component may be abbreviated as (A) component, (B) component, etc., respectively, and the same abbreviation method may be used for other components.

[0058] In addition, (B) a compound that is liquid at 25° C., has a reactive group, and has a molecular weight of 1000 or less may be referred to as “(B) reactive liquid compound”.

[0059] In the present embodiment, being in a liquid state at 25° C. means that the viscosity calculated by the following measurement method is 100,000 mPa·s or less.

[0060] <Viscosity measurement method>

[0061] Device: E-type viscometer

[0062] Conical rotor: 1°34'×R24

[0063] Temperature: 25℃

[0064] Sample volume: 1.0 mL

[0065] Speed: 20rpm

[0066] Hereinafter, in this specification, the viscosity at 25° C. means the viscosity measured by the above-mentioned method.

[0067] The reason why the resin film of the present embodiment can form a cured product having excellent plateability and excellent flexibility and can suppress the generation of volatile components during heat curing is presumed as follows.

[0068] The first resin composition contained in the insulating member forming resin layer of the resin film of the present embodiment contains (B) a compound that is liquid at 25° C. and has a molecular weight of 1000 or less as a component for improving the flexibility of the first resin composition. It is believed that the (B) reactive liquid compound is a liquid component with a relatively low molecular weight, and therefore can penetrate well into the molecules of the resin component, effectively weakening the intermolecular interaction of the resin component, thereby improving the flexibility of the resin film.

[0069] In addition, since the (B) reactive liquid compound has a reactive group, the (B) reactive liquid compound reacts with each other or with other components during the heat curing of the (A) thermosetting resin. That is, the (B) reactive liquid compound helps to improve flexibility and suppresses volatilization through the curing reaction. Therefore, it is believed that the resin film of this embodiment can suppress the generation of volatile components and improve flexibility compared to the case where an organic solvent or the like is used as a component for improving flexibility.

[0070] In addition, the resin film of the present embodiment has a primer layer-forming resin layer, which is arranged on one side of the insulating member forming resin layer and contains a second resin composition. Thus, it is believed that the cured product of the resin film of the present embodiment has a primer layer on the surface, which can improve the plating property.

[0071] <<Edge member forming resin layer>>

[0072] The insulating member forming resin layer included in the resin film of the present embodiment contains a first resin composition, and it is preferable that the first resin composition is formed into a layer.

[0073] The first resin composition contains: (A) a thermosetting resin; (B) a compound which is liquid at 25° C., has a reactive group and has a molecular weight of 1000 or less; and (C) an inorganic filler.

[0074] Hereinafter, each component which the first resin composition may contain will be described in order.

[0075] <(A) Thermosetting resin>

[0076] The first resin composition contains (A) a thermosetting resin.

[0077] (A) Thermosetting resins may be used alone or in combination of two or more.

[0078] (A) Thermosetting resins include, for example, epoxy resins, phenolic resins, maleimide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, and melamine resins.

[0079] Among them, the (A) thermosetting resin is preferably a maleimide resin from the viewpoint of heat resistance, and more preferably at least one selected from a maleimide resin having one or more N-substituted maleimide groups and a derivative of the maleimide resin.

[0080] In the following description, “one or more selected from a maleimide resin having one or more N-substituted maleimide groups and a derivative of the maleimide resin” may be referred to as “maleimide-based resin”.

[0081] In the following description, a maleimide resin having one or more N-substituted maleimide groups may be referred to as a "maleimide resin (AX)" or a "component (AX)".

[0082] In addition, a derivative of a maleimide resin having one or more N-substituted maleimide groups may be referred to as a "maleimide resin derivative (AY)" or a "(AY) component".

[0083] (Maleimide resin (AX))

[0084] The maleimide resin (AX) is not particularly limited as long as it is a maleimide resin having one or more N-substituted maleimide groups.

[0085] From the viewpoint of conductor adhesion and heat resistance, the maleimide resin (AX) is preferably an aromatic maleimide resin having two or more N-substituted maleimide groups, and more preferably an aromatic bismaleimide resin having two N-substituted maleimide groups.

[0086] It should be noted that, in this specification, "aromatic maleimide resin" refers to a compound having an N-substituted maleimide group directly bonded to an aromatic ring. In addition, in this specification, "aromatic bismaleimide resin" refers to a compound having two N-substituted maleimide groups directly bonded to an aromatic ring. In addition, in this specification, "aromatic polymaleimide resin" refers to a compound having three or more N-substituted maleimide groups directly bonded to an aromatic ring.

[0087] In addition, in this specification, "aliphatic maleimide resin" means a compound having an N-substituted maleimide group directly bonded to an aliphatic hydrocarbon.

[0088] As the maleimide resin (AX), from the viewpoints of dielectric properties, conductor adhesion and heat resistance, a maleimide resin having a condensed ring of an aromatic ring and an aliphatic ring in its molecular structure and having two or more N-substituted maleimide groups (hereinafter, sometimes referred to as "maleimide resin (A1)" or "(A1) component"). ] is preferred.

[0089] [Maleimide resin (A1)]

[0090] The maleimide resin (A1) is preferably an aromatic maleimide resin having a condensed ring of an aromatic ring and an aliphatic ring in its molecular structure and having two or more N-substituted maleimide groups from the viewpoint of dielectric properties, conductor adhesion and heat resistance.

[0091] The maleimide resin (A1) is more preferably an aromatic bismaleimide resin having a condensed ring of an aromatic ring and an aliphatic ring in its molecular structure and having two N-substituted maleimide groups.

[0092] From the viewpoints of dielectric properties, conductor adhesion and ease of production, the condensed ring contained in the maleimide resin (A1) preferably has a condensed bicyclic structure, and more preferably an indane ring.

[0093] As the maleimide resin (A1) containing an indane ring, an aromatic bismaleimide resin containing an indane ring is preferred.

[0094] It should be noted that, in this specification, the indane ring refers to a fused bicyclic structure of an aromatic 6-membered ring and a saturated aliphatic 5-membered ring. At least one of the ring-forming carbon atoms forming the indane ring has a bonding group for bonding to other groups constituting the maleimide resin (A1). The ring-forming carbon atom having the bonding group and other ring-forming carbon atoms may not have a bonding group, a substituent, etc. in addition to the above-mentioned bonding group, but preferably a divalent group is formed by having a bonding group other than the above-mentioned.

[0095] In the maleimide resin (A1), the indane ring is preferably contained in the form of a divalent group represented by the following general formula (A1-1).

[0096] [Chemical formula 1]

[0097]

[0098] (Where R a1 It is an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxyl group or a mercapto group. a1 is an integer from 0 to 3. a2 ~R a4 Each independently represents an alkyl group having 1 to 10 carbon atoms. * represents a bonding site. )

[0099] As R in the above general formula (A1-1) a1Examples of the alkyl group having 1 to 10 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc. These alkyl groups may be linear or branched.

[0100] As R a1 Examples of the alkyl group contained in the alkoxy group having 1 to 10 carbon atoms and the alkylthio group having 1 to 10 carbon atoms shown in the foregoing examples include the same groups as those for the alkyl group having 1 to 10 carbon atoms.

[0101] As R a1 Examples of the aryl group having 6 to 10 carbon atoms include phenyl and naphthyl.

[0102] As R a1 Examples of the aryl group contained in the aryloxy group having 6 to 10 carbon atoms and the arylthio group having 6 to 10 carbon atoms shown in the above-mentioned example include the same groups as those mentioned above for the aryl group having 6 to 10 carbon atoms.

[0103] As R a1 Examples of the cycloalkyl group having 3 to 10 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl and cyclodecyl.

[0104] In the above general formula (A1-1), n a1 When R is an integer of 1 to 3, from the viewpoint of solvent solubility and reactivity, a1 An alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms is preferred, and an alkyl group having 1 to 4 carbon atoms is more preferred.

[0105] As R a2 ~R a4 The alkyl group having 1 to 10 carbon atoms represented by a1 The same alkyl group. a2 ~R a4 An alkyl group having 1 to 4 carbon atoms is preferred, a methyl group or an ethyl group is more preferred, and a methyl group is further preferred.

[0106] In the above general formula (A1-1), n a1 is an integer from 0 to 3, n a1 If the value is 2 or 3, multiple R a1 They can be the same or different from each other.

[0107] Among the above, from the viewpoint of ease of production, the divalent group represented by the general formula (A1-1) is preferably n a1 0, R a2 ~R a4The divalent group represented by the following formula (A1-1a) which is a methyl group is more preferably a divalent group represented by the following formula (A1-1a′) or a divalent group represented by the following formula (A1-1a″).

[0108] [Chemical formula 2]

[0109]

[0110] (Wherein, * indicates the bonding site.)

[0111] As the maleimide resin (A1) containing a divalent group represented by the general formula (A1-1), a maleimide resin represented by the following general formula (A1-2) is preferred from the viewpoints of dielectric properties, conductor adhesion, heat resistance and ease of production.

[0112] [Chemical formula 3]

[0113]

[0114] (Where R a1 ~R a4 and n a1 and R in the above general formula (A1-1) a1 ~R a4 and n a1 Same. a5 Each is independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxyl group or a mercapto group. a2 Each independently represents an integer from 0 to 4. a3 A number between 0.95 and 10.0.)

[0115] In the above general formula (A1-2), a plurality of R a1 Each other, multiple n a1 Each other, multiple R a5 Each other, multiple n a2 They may be the same as or different from each other.

[0116] In n a3 If more than 1, multiple R a2 Each other, multiple R a3 Each other and multiple R a4 They may be the same as or different from each other.

[0117] As R in the above general formula (A1-2) a5The alkyl group having 1 to 10 carbon atoms, the alkoxy group having 1 to 10 carbon atoms, the alkylthio group having 1 to 10 carbon atoms, the aryl group having 6 to 10 carbon atoms, the aryloxy group having 6 to 10 carbon atoms, the arylthio group having 6 to 10 carbon atoms and the cycloalkyl group having 3 to 10 carbon atoms represented by the alkyl group include the same as the above R a1 The same groups are preferred.

[0118] In the above general formula (A1-2), n a2 It is an integer of 0 to 4, and is preferably an integer of 1 to 3, more preferably 2 or 3, and even more preferably 2, from the viewpoint of compatibility with other resins, dielectric properties, conductor adhesion, and ease of production.

[0119] It should be noted that by making n a2 When n is 1 or more, the benzene ring and the N-substituted maleimide group have a distorted conformation, and the intermolecular stacking is suppressed, thereby tending to further improve the solvent solubility. From the viewpoint of suppressing intermolecular stacking, a2 When R is greater than 1, a5 The substitution position is preferably the ortho position relative to the N-substituted maleimide group.

[0120] From the viewpoints of dielectric properties, conductor adhesion, solvent solubility, handling properties, and heat resistance, n in the general formula (A1-2) is a3 It is preferably a number of 0.98 to 8.0, more preferably a number of 1.0 to 7.0, and still more preferably a number of 1.1 to 6.0. a3 The average value of the number of structural units containing an indane ring is shown.

[0121] From the viewpoints of dielectric properties, conductor adhesion, solvent solubility and ease of production, the maleimide resin (A1) represented by the above general formula (A1-2) is more preferably a maleimide resin represented by the following general formula (A1-3) or a maleimide resin represented by the following general formula (A1-4).

[0122] [Chemical formula 4]

[0123]

[0124] (Where R a1 ~R a5 and n a1 and n a3 and R in the above general formula (A1-2) a1 ~R a5 and n a1 and n a3 same.)

[0125]

[0126] (Where R a1 ~R a4 and n a1 and n a3 and R in the above general formula (A1-2) a1 ~R a4 and n a1 and n a3 same.)

[0127] The maleimide resin (A1) represented by the general formula (A1-3) mentioned above may be, for example, a maleimide resin represented by the following general formula (A1-3-1), a maleimide resin represented by the following general formula (A1-3-2), a maleimide resin represented by the following general formula (A1-3-3), or the like.

[0128] [Chemical formula 5]

[0129]

[0130] (where n a3 With the above general formula (A1-2) in n a3 same.)

[0131] The maleimide resin (A1) represented by the general formula (A1-4) is more preferably a maleimide resin represented by the following general formula (A1-4-1) from the viewpoints of dielectric properties, conductor adhesion, solvent solubility, and ease of production.

[0132] [Chemical formula 6]

[0133]

[0134] (where n a3 With the above general formula (A1-2) in n a3 same.)

[0135] The number average molecular weight of the maleimide resin (A1) is not particularly limited, but is preferably 600 to 3000, more preferably 800 to 2000, and even more preferably 1000 to 1500 from the viewpoint of compatibility with other resins, conductor adhesion, and heat resistance.

[0136] The maleimide resin (AX) may be a maleimide resin (A2) other than the maleimide resin (A1) [hereinafter, sometimes referred to as "maleimide resin (A2)" or "component (A2)".].

[0137] [Maleimide resin (A2)]

[0138] As the maleimide resin (A2), a maleimide resin represented by the following general formula (A2-1) is preferred.

[0139] [Chemical formula 7]

[0140]

[0141] (Where X a11 It is a divalent organic group that does not contain a condensed ring of an aromatic ring and an aliphatic ring.)

[0142] X in the above general formula (A2-1) a11 It is a divalent organic group not including a condensed ring of an aromatic ring and an aliphatic ring.

[0143] As X in the above general formula (A2-1) a11 Examples of the divalent organic group represented include a divalent group represented by the following general formula (A2-2), a divalent group represented by the following general formula (A2-3), a divalent group represented by the following general formula (A2-4), a divalent group represented by the following general formula (A2-5), and a divalent group represented by the following general formula (A2-6).

[0144] [Chemical formula 8]

[0145]

[0146] (Where R a11 It is an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. a11 is an integer from 0 to 4. * indicates a bonding site. )

[0147] As R in the above general formula (A2-2) a11 The aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by the above-mentioned group includes, for example, alkyl groups having 1 to 5 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, and n-pentyl; alkenyl groups having 2 to 5 carbon atoms; and alkynyl groups having 2 to 5 carbon atoms. The aliphatic hydrocarbon group having 1 to 5 carbon atoms may be either linear or branched. As the aliphatic hydrocarbon group having 1 to 5 carbon atoms, an aliphatic hydrocarbon group having 1 to 3 carbon atoms is preferred, an alkyl group having 1 to 3 carbon atoms is more preferred, and a methyl group is further preferred.

[0148] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0149] In the above general formula (A2-2), n a11 It is an integer of 0 to 4, preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0, from the viewpoint of easy availability.

[0150] In n a11When the integer is 2 or more, multiple R a11 They can be the same or different from each other.

[0151] [Chemical formula 9]

[0152]

[0153] (Where R a12 and R a13 Each independently represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. a12 It is an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, an ether group, a thioether group, a sulfonyl group, a carbonyloxy group, a keto group, a single bond, or a divalent group represented by the following general formula (A2-3-1). a12 and n a13 Each independently represents an integer from 0 to 4.

[0154] *Indicates bonding location. )

[0155] As R in the above general formula (A2-3) a12 and R a13 The aliphatic hydrocarbon group having 1 to 5 carbon atoms and the halogen atom represented by can be exemplified by the above R a11 Same group.

[0156] As X in the above general formula (A2-3) a12 Examples of the alkylene group having 1 to 5 carbon atoms include a methylene group, a 1,2-ethylene group, a 1,3-propylene group, a 1,4-butylene group, and a 1,5-pentylene group.

[0157] As X in the above general formula (A2-3) a12 Examples of the alkylidene group having 2 to 5 carbon atoms include ethylidene, propylidene, isopropylidene, butylidene, isobutylidene, pentylidene and isopentylidene.

[0158] In the above general formula (A2-3), n a12 and n a13 Each independently represents an integer of 0 to 4, and is preferably an integer of 1 to 3, more preferably 1 or 2, and even more preferably 2, from the viewpoint of easy availability, compatibility with other resins, and suppression of gelation of the product during the reaction.

[0159] In n a12 or a13 When the integer is 2 or more, multiple R a12 Each other or multiple R a13 They may be the same as or different from each other.

[0160] X in the above general formula (A2-3) a12The divalent group represented by the general formula (A2-3-1) is as follows.

[0161] [Chemical formula 10]

[0162]

[0163] (Where R a14 and R a15 Each independently represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom. a13 It is an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, an ether group, a thioether group, a sulfonyl group, a carbonyloxy group, a keto group or a single bond. a14 and n a15 Each independently represents an integer of 0 to 4. * represents a bonding site. )

[0164] As R in the above general formula (A2-3-1) a14 and R a15 The aliphatic hydrocarbon group having 1 to 5 carbon atoms and the halogen atom represented by can be exemplified by the above R a11 Same group.

[0165] As X in the above general formula (A2-3-1) a13 The alkylene group having 1 to 5 carbon atoms and the alkylidene group having 2 to 5 carbon atoms represented by the formula (X) include the above-mentioned a12 Same group.

[0166] In the above general formula (A2-3-1), n a14 and n a15 Each independently represents an integer of 0 to 4, and is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0, from the viewpoint of easy availability.

[0167] In n a14 or a15 When the integer is 2 or more, multiple R a14 Each other or multiple R a15 They may be the same as or different from each other.

[0168] [Chemical formula 11]

[0169]

[0170] (where n a16 is an integer from 0 to 10. * indicates a bonding site. )

[0171] From the viewpoint of easy availability, n in the above general formula (A2-4) is a16 An integer of 0-5 is preferable, an integer of 0-4 is more preferable, and an integer of 0-3 is further preferable.

[0172] [Chemical formula 12]

[0173]

[0174] (where n a17 It is a number from 0 to 5. * indicates a bonding site. )

[0175] [Chemical formula 13]

[0176]

[0177] (Where R a16 and R a17 Each independently represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 5 carbon atoms. a18 is an integer from 1 to 8. * represents a bonding site. )

[0178] As R in the above general formula (A2-6) a16 and R a17 The aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by a11 Same group.

[0179] In the above general formula (A2-6), n a18 is an integer of 1 to 8, preferably an integer of 1 to 5, more preferably an integer of 1 to 3, and further preferably 1. a18 When the integer is 2 or more, multiple R a16 Each other or multiple R a17 They may be the same as or different from each other.

[0180] The maleimide resin (A2) is preferably a polymaleimide resin represented by the following general formula (A2-7).

[0181] [Chemical formula 14]

[0182]

[0183] (Where X a14 are each independently a divalent hydrocarbon group having 1 to 20 carbon atoms, n a19 is an integer from 2 to 5.)

[0184] As X in the above general formula (A2-7) a14 Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms include divalent aliphatic hydrocarbon groups such as alkylene groups having 1 to 5 carbon atoms and alkylidene groups having 2 to 5 carbon atoms; and divalent hydrocarbon groups including aromatic hydrocarbon groups represented by the following general formula (A2-8).

[0185] Examples of the alkylene group having 1 to 5 carbon atoms include methylene, 1,2-ethylene, 1,3-propylene, 1,4-butylene, 1,5-pentylene, etc. As the alkylene group having 1 to 5 carbon atoms, an alkylene group having 1 to 3 carbon atoms is preferred, an alkylene group having 1 or 2 carbon atoms is more preferred, and a methylene group is further preferred.

[0186] The alkylidene group having 2 to 5 carbon atoms is preferably an alkylidene group having 2 to 4 carbon atoms, more preferably an alkylidene group having 2 or 3 carbon atoms, and further preferably an isopropylidene group.

[0187] [Chemical formula 15]

[0188] *-X a15 -Ar a1 -X a16 -* (A2-8)

[0189] (Where Ar a1 is a divalent aromatic hydrocarbon group, X a15 and X a16 Each independently represents a divalent aliphatic hydrocarbon group having 1 to 5 carbon atoms. * represents a bonding site. )

[0190] As X in the above general formula (A2-8) a15 and X a16 The divalent aliphatic hydrocarbon group having 1 to 5 carbon atoms represented by a14 The alkylene group having 1 to 5 carbon atoms and the alkylidene group having 2 to 5 carbon atoms are the same groups as mentioned above. Among them, the methylene group is preferred.

[0191] As Ar in the above general formula (A2-8) a1 The divalent aromatic hydrocarbon group represented by the present invention includes, for example, phenylene, naphthylene, biphenylene, anthrylene, etc. Among them, biphenylene is preferred. Examples of biphenylene include 4,2'-biphenylene, 4,3'-biphenylene, 4,4'-biphenylene, 3,3'-biphenylene, etc., among which 4,4'-biphenylene is preferred.

[0192] In the above options, X in the above general formula (A2-7) a14 Preferably, it is a divalent hydrocarbon group containing an aromatic hydrocarbon group represented by the above general formula (A2-8), and more preferably, X in the above general formula (A2-8) is a15 and X a16 is a methylene group and Ar a1 It is a divalent hydrocarbon group of 4,4'-biphenylene.

[0193] In the above general formula (A2-7), n a19 It is an integer of 2-5, preferably an integer of 2-4, and more preferably 2 or 3.

[0194] As a maleimide resin (A2), an aromatic bismaleimide resin, an aromatic polymaleimide resin, an aliphatic maleimide resin etc. are mentioned, for example.

[0195] Specific examples of the maleimide resin (A2) include bis(4-maleimidophenyl)methane, m-phenylene bismaleimide, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, 4-methyl-1,3-phenylene bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, polyphenylmethane maleimide, biphenyl aralkyl maleimide, etc. Among them, biphenyl aralkyl maleimide is preferred.

[0196] (Maleimide resin derivative (AY))

[0197] As the maleimide resin derivative (AY), an aminomaleimide resin having a structural unit derived from the above-mentioned maleimide resin (AX) and a structural unit derived from a diamine compound is preferred.

[0198] The aminomaleimide resin has a structural unit derived from the maleimide resin (AX) and a structural unit derived from a diamine compound.

[0199] The aminomaleimide resin is obtained by, for example, subjecting a maleimide resin (AX) to Michael addition of a diamine compound.

[0200] As the diamine compound, for example, the same diamine compound as the amine compound having at least two primary amino groups in one molecule listed in Japanese Patent Application Laid-Open No. 2020-200406 can be used. Among them, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-[1,3-phenylenebis(1-methylethylidene)]dianiline, 4,4'-[1,4-phenylenebis(1-methylethylidene)]dianiline, and 3,3'-diethyl-4,4'-diaminodiphenylmethane are preferred.

[0201] Among the thermosetting resins (A) described above, from the viewpoints of dielectric properties, conductor adhesion and heat resistance, the thermosetting resin (A) is preferably a maleimide resin having a condensed ring of an aromatic ring and an aliphatic ring in its molecular structure and having two or more N-substituted maleimide groups.

[0202] The (A) thermosetting resin preferably has a viscosity at 25°C measured by the above method exceeding 100,000 mPa·s, and is more preferably solid at 25°C.

[0203] ((A) Content of thermosetting resin)

[0204] In the first resin composition, the content of (A) thermosetting resin is not particularly limited, but is preferably 5 to 60% by mass, more preferably 8 to 40% by mass, further preferably 10 to 30% by mass, and particularly preferably 15 to 25% by mass, relative to the total amount (100% by mass) of the resin components in the first resin composition.

[0205] When the content of the thermosetting resin (A) is above the lower limit, the heat resistance, formability, processability and conductor adhesion tend to be better. In addition, when the content of the thermosetting resin (A) is below the upper limit, the dielectric properties tend to be better.

[0206] In addition, the upper limit of the content of the thermosetting resin (A) may be 80% by mass or less, 70% by mass or less, or 60% by mass or less, relative to the total amount (100% by mass) of the thermosetting resin (A) and the reactive liquid compound (B). In addition, the lower limit of the content of the thermosetting resin (A) may be 5% by mass or more, 10% by mass or more, or 15% by mass or more, relative to the total amount (100% by mass) of the thermosetting resin (A) and the reactive liquid compound (B).

[0207] Here, in this specification, the "resin component" refers to a resin and a compound that forms a resin by a curing reaction.

[0208] For example, in the first resin composition, the component (A) and the component (B) correspond to the resin component.

[0209] When the first resin composition contains a resin or a compound that forms a resin by a curing reaction as an optional component in addition to the above components, these optional components are also included in the resin component. As an optional component corresponding to the resin component, there can be mentioned the component (D) and the component (E) described later.

[0210] On the other hand, the component (C) is not included in the resin component.

[0211] The content of the resin component in the first resin composition is not particularly limited, but is preferably 5 to 80% by mass, more preferably 10 to 60% by mass, and further preferably 20 to 40% by mass, relative to the total solid content (100% by mass) of the first resin composition, from the viewpoint of low thermal expansion, heat resistance, flame retardancy and conductor adhesion.

[0212] The content of the maleimide resin in the (A) thermosetting resin is not particularly limited, but is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass, relative to the total amount (100% by mass) of the (A) thermosetting resin.

[0213] When the content of the maleimide resin is above the lower limit, the heat resistance, formability, processability and conductor adhesion tend to be better. In addition, when the content of the maleimide resin is below the upper limit, the dielectric properties tend to be better.

[0214] <(B) Reactive liquid compound>

[0215] (B) The reactive liquid compound is not particularly limited as long as it is a compound that is liquid at 25° C., has a reactive group, and has a molecular weight of 1,000 or less.

[0216] (B) The reactive liquid compound may be used alone or in combination of two or more.

[0217] The reactive liquid compound (B) preferably has two or more reactive groups in one molecule, more preferably has 2 to 5 reactive groups, further preferably has 2 to 4 reactive groups, and particularly preferably has 2 or 3 reactive groups.

[0218] When the number of reactive groups is within the above range, volatilization during heat curing is more effectively suppressed, and excellent flexibility tends to be easily obtained.

[0219] The molecular weight of the reactive liquid compound (B) is 1,000 or less, preferably 100 to 800, more preferably 150 to 600, and even more preferably 200 to 400.

[0220] If the molecular weight of the reactive liquid compound (B) is above the above lower limit, there is a tendency to easily suppress the volatilization of the reactive liquid compound (B) before the first resin composition is heated and cured. In addition, if the molecular weight of the reactive liquid compound (B) is below the above upper limit, there is a tendency to easily obtain better flexibility.

[0221] The viscosity of the reactive liquid compound (B) at 25° C. is preferably 1 to 5000 mPa·s, more preferably 2 to 1000 mPa·s, and even more preferably 4 to 500 mPa·s.

[0222] When the viscosity of the reactive liquid compound (B) at 25°C is at least the above lower limit, volatilization of the reactive liquid compound (B) tends to be easily suppressed. On the other hand, when the viscosity of the reactive liquid compound (B) at 25°C is at most the above upper limit, better flexibility tends to be easily obtained.

[0223] (B) The viscosity of the reactive liquid compound at 25°C can be measured by the above-mentioned measurement method.

[0224] The (B) reactive liquid compound preferably has, as the reactive group, one or more selected from the group consisting of a functional group containing an ethylenically unsaturated bond, an epoxy group, a hydroxyl group, a carboxyl group, and an amino group.

[0225] It should be noted that, in the present specification, the "ethylenically unsaturated bond" refers to a carbon-carbon double bond capable of an addition reaction, and does not include a double bond of an aromatic ring.

[0226] Examples of the functional group containing an ethylenically unsaturated bond include a vinyl group, an allyl group, a 1-methylallyl group, an isopropenyl group, a 2-butenyl group, a 3-butenyl group, a styryl group, an N-substituted maleimide group, and a (meth)acryloyl group.

[0227] Among them, the reactive group is more preferably a functional group containing an ethylenically unsaturated bond or an epoxy group. From the viewpoint of easily obtaining more excellent dielectric properties, a functional group containing an ethylenically unsaturated bond is further preferred, and a (meth)acryloyl group is particularly preferred.

[0228] Specific examples of the (B) reactive liquid compound having a (meth)acryloyl group as a reactive group include (meth)acrylates such as mono(meth)acrylate, di(meth)acrylate, and tri- or higher-functional (meth)acrylate.

[0229] Examples of the mono(meth)acrylate include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, butyl(meth)acrylate, pentyl(meth)acrylate, hexyl(meth)acrylate, heptyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, octyl(meth)acrylate, isooctyl(meth)acrylate, nonyl(meth)acrylate, decyl(meth)acrylate, dodecyl(meth)acrylate, lauryl(meth)acrylate, tridecyl(meth)acrylate, stearyl(meth)acrylate, cyclohexyl(meth)acrylate, cyclopentyl(meth)acrylate, benzyl(meth)acrylate, dicyclopentenyl(meth)acrylate, dicyclopentenyloxyethyl(meth)acrylate, methoxyethyl(meth)acrylate, ethoxyethyl(meth)acrylate, butoxyethyl(meth)acrylate, phenoxyethyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate.

[0230] Examples of the di(meth)acrylate include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, tricyclodecane di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol F di(meth)acrylate, and dioxanediol di(meth)acrylate.

[0231] Examples of the dioxanediol di(meth)acrylate include 2-[5-ethyl-5-[(acryloyloxy)methyl]-1,3-dioxane-2-yl]-2,2-dimethylethyl acrylate and the like.

[0232] Examples of trifunctional or higher-functional (meth)acrylates include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0233] Among the above options, as the (meth)acrylate, di(meth)acrylate is preferred.

[0234] As the di(meth)acrylate, a diacrylate represented by the following general formula (B-1) or a dimethacrylate represented by the following general formula (B-2) is preferred, and a dimethacrylate represented by the following general formula (B-2) is more preferred.

[0235] [Chemical formula 16]

[0236]

[0237] (Where R b1 is an alkylene group having 1 to 20 carbon atoms. )

[0238] From the viewpoint of flexibility and suppression of volatilization, R in the above general formulas (B-1) and (B-2) b1 The alkylene group having 1 to 20 carbon atoms preferably has 4 to 18 carbon atoms, more preferably 6 to 15 carbon atoms, and even more preferably 8 to 12 carbon atoms.

[0239] Examples of the alkylene group having 1 to 20 carbon atoms include methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, tetradecylene, pentadecylene, etc. The alkylene group may be linear, branched or cyclic, and is preferably linear.

[0240] ((B) Content of reactive liquid compound)

[0241] In the first resin composition, the content of the reactive liquid compound (B) is not particularly limited, but is preferably 5 to 60% by mass, more preferably 8 to 40% by mass, further preferably 10 to 30% by mass, and particularly preferably 15 to 25% by mass, relative to the total amount (100% by mass) of the resin components in the first resin composition.

[0242] The content of the reactive liquid compound (B) in the first resin composition is not particularly limited, but is preferably 0.5 to 20% by mass, more preferably 1.0 to 15% by mass, and even more preferably 1.5 to 10% by mass, relative to the total solid content (100% by mass) of the first resin composition.

[0243] If the content of the reactive liquid compound (B) is above the lower limit, it is easy to obtain better flexibility. If the content of the reactive liquid compound (B) is below the upper limit, it is easy to suppress the generation of volatile components during heat curing.

[0244] <(C) Inorganic fillers>

[0245] The first resin composition tends to easily obtain more excellent low thermal expansion property, heat resistance and flame retardancy by containing the (C) inorganic filler.

[0246] In particular, since the resin film of the present embodiment is excellent in flexibility, the content of the (C) inorganic filler can be increased to further improve the low thermal expansion property.

[0247] (C) The inorganic filler may be used alone or in combination of two or more.

[0248] (C) Inorganic fillers include, for example, silica, alumina, titanium oxide, mica, beryllium oxide, 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, silicon carbide, etc. Among them, from the viewpoint of low thermal expansion, heat resistance and flame retardancy, silica, alumina, mica and talc are preferred, and silica and alumina are more preferred.

[0249] Examples of silica include precipitated silica with a high water content produced by a wet process, dry-process silica that contains almost no bound water, etc. Dry-process silica, further including crushed silica, fumed silica, fused silica, etc., depending on the production method.

[0250] From the viewpoint of improving dispersibility and adhesion with organic components, the (C) inorganic filler may be surface-treated with a surface treatment agent such as a silane coupling agent.

[0251] The average particle size of the inorganic filler (C) is not particularly limited, but is preferably 0.01 to 20 μm, more preferably 0.1 to 10 μm, further preferably 0.2 to 1 μm, and particularly preferably 0.3 to 0.8 μm from the viewpoint of dispersibility and fine wiring properties of the inorganic filler (C).

[0252] It should be noted that, in this specification, the average particle size refers to the particle size corresponding to the point of 50% volume when the total volume of the particles is set as 100% and the cumulative frequency distribution curve based on the particle size is obtained. The average particle size can be measured, for example, by a particle size distribution measuring device using a laser diffraction scattering method.

[0253] Examples of the shape of the (C) inorganic filler include spherical shapes and crushed shapes, and a spherical shape is preferred.

[0254] ((C) Content of inorganic filler)

[0255] The content of the (C) inorganic filler in the first resin composition is not particularly limited, but is preferably 20 to 95% by mass, more preferably 40 to 90% by mass, and even more preferably 60 to 80% by mass, relative to the total solid content (100% by mass) of the first resin composition.

[0256] If the content of (C) inorganic filler is above the above lower limit, low thermal expansion, heat resistance and flame retardancy tend to become better. In addition, if the content of (C) inorganic filler is below the above upper limit, formability and conductor adhesion tend to become better.

[0257] <(D) Elastomers having a molecular weight exceeding 1000>

[0258] The first resin composition preferably further contains (D) an elastomer having a molecular weight exceeding 1,000 [hereinafter, sometimes referred to as "(D) elastomer"].

[0259] There is a tendency that more excellent dielectric properties are easily obtained by the first resin composition containing the (D) elastomer.

[0260] In addition, the "elastomer" herein refers to a polymer having a glass transition temperature of 25° C. or less as measured by differential scanning calorimetry in accordance with JIS K 6240:2011.

[0261] (D) The elastomer may be used alone or in combination of two or more.

[0262] The molecular weight of the elastomer (D) exceeds 1,000, and is preferably 1,050 to 500,000, more preferably 1,100 to 350,000, and even more preferably 1,150 to 200,000.

[0263] When the molecular weight of the elastomer (D) is above the lower limit, the heat resistance of the first resin composition obtained tends to be better maintained. In addition, when the molecular weight of the elastomer (D) is below the upper limit, the dielectric properties and conductor adhesion of the first resin composition obtained tend to be better.

[0264] Preferred examples of the elastomer (D) include a conjugated diene polymer (D1), a modified conjugated diene polymer (D2), and a styrene-based elastomer (D3).

[0265] Preferred embodiments of these components are described below.

[0266] (Conjugated diene polymer (D1))

[0267] In this specification, the "conjugated diene polymer" refers to a polymer of a conjugated diene compound.

[0268] There is a tendency that more excellent dielectric properties are easily obtained by the first resin composition containing the conjugated diene polymer (D1).

[0269] The conjugated diene polymer (D1) may be used alone or in combination of two or more.

[0270] Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene.

[0271] The conjugated diene polymer (D1) may be a polymer of one conjugated diene compound or a copolymer of two or more conjugated diene compounds.

[0272] Furthermore, the conjugated diene polymer (D1) may be a copolymer of one or more conjugated diene compounds and one or more monomers other than the conjugated diene compound.

[0273] When the conjugated diene polymer (D1) is a copolymer, the polymerization method is not particularly limited, and any of random polymerization, block polymerization, and graft polymerization may be used.

[0274] The conjugated diene polymer (D1) is preferably a conjugated diene polymer having a plurality of vinyl groups in a side chain from the viewpoint of compatibility with other resins and dielectric properties.

[0275] The number of vinyl groups in one molecule of the conjugated diene polymer (D1) is not particularly limited, but is preferably 3 or more, more preferably 5 or more, and even more preferably 10 or more, from the viewpoint of compatibility with other resins and dielectric properties.

[0276] The upper limit of the number of vinyl groups in one molecule of the conjugated diene polymer (D1) is not particularly limited, and may be 100 or less, 80 or less, or 60 or less.

[0277] As the conjugated diene polymer (D1), for example, polybutadiene having 1,2-vinyl group, butadiene-styrene copolymer having 1,2-vinyl group, polyisoprene having 1,2-vinyl group, etc. can be cited. Among them, from the viewpoint of dielectric properties and heat resistance, polybutadiene having 1,2-vinyl group and butadiene-styrene copolymer having 1,2-vinyl group are preferred, and polybutadiene having 1,2-vinyl group is more preferred. In addition, as the polybutadiene having 1,2-vinyl group, a polybutadiene homopolymer having 1,2-vinyl group is preferred.

[0278] The 1,2-vinyl group derived from butadiene in the conjugated diene polymer (D1) means a vinyl group contained in the structural unit derived from butadiene represented by the following formula (D1-1).

[0279] [Chemical formula 17]

[0280]

[0281] In the case where the conjugated diene polymer (D1) is a polybutadiene with 1,2-vinyl, relative to all structural units from butadiene constituting the polybutadiene, the content of the 1,2-vinyl structural unit [hereinafter, sometimes referred to as "vinyl content". ] is not particularly limited, from the viewpoint of compatibility with other resins, dielectric properties and heat resistance, preferably 50 mol% or more, more preferably 70 mol% or more, further preferably 85 mol% or more. In addition, the upper limit of the vinyl content is not particularly limited, and can be 100 mol% or less, 95 mol% or less, or 90 mol% or less. As the structural unit with 1,2-vinyl, the structural unit from butadiene shown in the above formula (D1-1) is preferably.

[0282] From the same viewpoint, the polybutadiene having a 1,2-vinyl group is preferably a 1,2-polybutadiene homopolymer.

[0283] The number average molecular weight of the conjugated diene polymer (D1) is not particularly limited, but is preferably 1,050 to 3,000, more preferably 1,100 to 2,000, and even more preferably 1,150 to 1,500 from the viewpoint of compatibility with other resins, dielectric properties, and heat resistance.

[0284] (Modified conjugated diene polymer (D2))

[0285] The modified conjugated diene polymer (D2) is a polymer obtained by modifying a conjugated diene polymer.

[0286] The first resin composition contains the modified conjugated diene polymer (D2), thereby having good heat resistance and low thermal expansion, and tends to easily obtain more excellent dielectric properties.

[0287] The modified conjugated diene polymer (D2) may be used alone or in combination of two or more.

[0288] For example, when the (A) thermosetting resin includes a maleimide-based resin, the modified conjugated diene polymer (D2) is preferably a modified conjugated diene polymer obtained by modifying (d1) a conjugated diene polymer having a vinyl group in a side chain [hereinafter, sometimes referred to as "conjugated diene polymer (d1)"]. with (d2) a maleimide resin having two or more N-substituted maleimide groups [hereinafter, sometimes referred to as "maleimide resin (d2)".]. from the viewpoint of compatibility with other resins, dielectric properties and conductor adhesion.

[0289] As the conjugated diene polymer (d1), for example, the conjugated diene polymer having a vinyl group in a side chain described as the above conjugated diene polymer (D1) can be used, and the preferred embodiments are also the same.

[0290] The conjugated diene polymer (d1) may be used alone or in combination of two or more.

[0291] As the maleimide resin (d2), for example, the maleimide resin having two or more N-substituted maleimide groups described as the maleimide resin (AX) can be used, and the preferred embodiments are also the same.

[0292] The maleimide resin (d2) may be used alone or in combination of two or more.

[0293] The modified conjugated diene polymer (D2) preferably has a substituent (hereinafter sometimes referred to as "substituent (x)") formed by reacting a vinyl group of the conjugated diene polymer (d1) with an N-substituted maleimide group of the maleimide resin (d2) in a side chain.

[0294] From the viewpoint of compatibility with other resins, dielectric properties, low thermal expansion and heat resistance, the substituent (x) is preferably a group containing a structure represented by the following general formula (D2-1) or (D2-2) as a structure derived from the maleimide resin (d2).

[0295] [Chemical formula 18]

[0296]

[0297] (Where X d1 A divalent group formed by removing two N-substituted maleimide groups from the maleimide resin (d2), * d1 This is a site that bonds to a carbon atom derived from a vinyl group in a side chain of the conjugated diene polymer (d1).* d2 The site for bonding with other atoms.)

[0298] The modified conjugated diene polymer (D2) preferably has a substituent (x) and a vinyl group (y) in a side chain.

[0299] The extent to which the substituent (x) exists in the modified conjugated diene polymer (D2) can be determined by the extent to which the vinyl groups of the conjugated diene polymer (d1) are modified by the maleimide resin (d2) (hereinafter, sometimes referred to as “vinyl modification ratio”).

[0300] The vinyl modification rate is not particularly limited, but is preferably 20 to 70%, more preferably 30 to 60%, and further preferably 35 to 50%, from the viewpoint of compatibility with other resins, dielectric properties, low thermal expansion and heat resistance. Here, the vinyl modification rate is a value obtained by the method described in the Examples.

[0301] The vinyl group (y) is preferably a 1,2-vinyl group contained in the structural unit derived from butadiene.

[0302] The number average molecular weight of the modified conjugated diene polymer (D2) is not particularly limited, but is preferably 1,100 to 6,000, more preferably 1,300 to 4,000, and even more preferably 1,500 to 2,000 from the viewpoint of compatibility with other resins, dielectric properties, low thermal expansion and heat resistance.

[0303] The modified conjugated diene polymer (D2) can be produced by reacting the conjugated diene polymer (d1) with the maleimide resin (d2).

[0304] The method for reacting the conjugated diene polymer (d1) and the maleimide resin (d2) is not particularly limited. For example, the modified conjugated diene polymer (D2) can be obtained by placing the conjugated diene polymer (d1), the maleimide resin (d2), a reaction catalyst and an organic solvent in a reaction vessel and reacting them while heating, keeping warm, stirring, etc. as required.

[0305] The reaction temperature of the above reaction is preferably 70 to 120°C, more preferably 80 to 110°C, and even more preferably 85 to 105°C from the viewpoint of workability and suppression of gelation of the product during the reaction.

[0306] From the viewpoint of productivity and sufficient progress of the reaction, the reaction time of the above reaction is preferably 0.5 to 15 hours, more preferably 1 to 10 hours, and even more preferably 3 to 7 hours.

[0307] However, these reaction conditions can be appropriately adjusted according to the types of raw materials used, and are not particularly limited.

[0308] When the above reaction is carried out, the molar number (M m ) relative to the molar number (M) of the side chain vinyl groups possessed by the conjugated diene polymer (d1) v ) ratio (M m / M v ) is not particularly limited, but is preferably 0.001 to 0.5, more preferably 0.005 to 0.1, and further preferably 0.008 to 0.05, from the viewpoint of compatibility of the obtained modified conjugated diene polymer (D2) with other resins and suppression of gelation of the product in the reaction.

[0309] <Styrene elastomer (D3)>

[0310] The styrene-based elastomer (D3) is not particularly limited as long as it is an elastomer having a structural unit derived from a styrene-based compound.

[0311] There is a tendency that more excellent dielectric properties are easily obtained by the first resin composition containing the styrene-based elastomer (D3).

[0312] The styrene-based elastomer (D3) may be used alone or in combination of two or more.

[0313] The styrene-based elastomer (D3) preferably has a structural unit derived from a styrene-based compound represented by the following general formula (D3-1).

[0314] [Chemical formula 19]

[0315]

[0316] (Where R d1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R d2 It is an alkyl group having 1 to 5 carbon atoms. d1 is an integer from 0 to 5.)

[0317] As R in the above general formula (D3-1) d1 and R d2 The alkyl group having 1 to 5 carbon atoms represented by the present invention includes, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, etc. The alkyl group having 1 to 5 carbon atoms may be straight-chain or branched. Among them, the alkyl group having 1 to 3 carbon atoms is preferred, the alkyl group having 1 or 2 carbon atoms is more preferred, and the methyl group is still more preferred.

[0318] In the above general formula (D3-1), n d1 It is an integer of 0 to 5, preferably an integer of 0 to 2, more preferably 0 or 1, and further preferably 0.

[0319] The styrene-based elastomer (D3) may contain a structural unit other than the structural unit derived from a styrene-based compound.

[0320] Examples of the structural unit other than the structural unit derived from the styrene compound which the styrene elastomer (D3) may contain include a structural unit derived from butadiene, a structural unit derived from isoprene, a structural unit derived from maleic acid, and a structural unit derived from maleic anhydride.

[0321] The structural units derived from butadiene and the structural units derived from isoprene may be hydrogenated. When hydrogenated, the structural units derived from butadiene become structural units in which ethylene units and butene units are mixed, and the structural units derived from isoprene become structural units in which ethylene units and propylene units are mixed.

[0322] Examples of the styrene-based elastomer (D3) include hydrogenated products of styrene-butadiene-styrene block copolymers, hydrogenated products of styrene-isoprene-styrene block copolymers, and styrene-maleic anhydride copolymers.

[0323] The hydrogenated products of styrene-butadiene-styrene block copolymers include: SEBS formed by completely hydrogenating the carbon-carbon double bonds in the butadiene block, and SBBS formed by partially hydrogenating the carbon-carbon double bonds in the 1,2-bonding portion of the butadiene block. It should be noted that the complete hydrogenation in SEBS is usually 90% or more relative to the total carbon-carbon double bonds, can be 95% or more, can be 99% or more, and can also be 100%. In addition, the partial hydrogenation rate in SBBS is, for example, 60 to 85% relative to the total carbon-carbon double bonds. The hydrogenated product of styrene-isoprene-styrene block copolymer is obtained by hydrogenating the polyisoprene portion as SEPS.

[0324] Among them, SEBS and SEPS are preferred, and SEBS is more preferred, from the viewpoint of dielectric properties, conductor adhesion, heat resistance, glass transition temperature, and low thermal expansion.

[0325] The content of the structural unit derived from the styrene compound in the styrene elastomer (D3) [hereinafter sometimes referred to as "styrene content"] is not particularly limited, but is preferably 5 to 60% by mass, more preferably 7 to 40% by mass, and further preferably 10 to 20% by mass.

[0326] The melt flow rate (MFR) of the styrene elastomer (D3) is not particularly limited, but is preferably 0.1 to 20 g / 10 min, more preferably 1 to 10 g / 10 min, and further preferably 3 to 7 g / 10 min under the measurement conditions of 230°C and a load of 2.16 kgf (21.2 N).

[0327] The number average molecular weight of the styrene elastomer (D3) is not particularly limited, but is preferably 10,000 to 500,000, more preferably 50,000 to 350,000, and even more preferably 100,000 to 200,000.

[0328] Examples of the (D) elastomer other than the conjugated diene polymer (D1), the modified conjugated diene polymer (D2) and the styrene elastomer (D3) include polyolefin resins, polyphenylene ether resins, polyester resins, polyamide resins, polyacrylic acid resins and the like.

[0329] ((D) Elastomer content)

[0330] When the first resin composition contains (D) an elastomer, the content of the (D) elastomer is not particularly limited, but is preferably 10 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 50 to 60% by mass, relative to the total amount (100% by mass) of the resin components in the first resin composition.

[0331] When the content of the elastomer (D) is at least the above lower limit, more excellent dielectric properties tend to be easily obtained. On the other hand, when the content of the elastomer (D) is at most the above upper limit, more excellent heat resistance tends to be easily obtained.

[0332] The total content of one or more selected from the conjugated diene polymer (D1), the modified conjugated diene polymer (D2) and the styrene-based elastomer (D3) is not particularly limited, but is preferably 60 to 100 mass %, more preferably 80 to 100 mass %, and even more preferably 90 to 100 mass % relative to the total amount (100 mass %) of the elastomer (D), from the viewpoint of dielectric properties and conductor adhesion.

[0333] <(E) Curing accelerator>

[0334] The first resin composition further contains (E) a curing accelerator.

[0335] The first resin composition contains the (E) curing accelerator, thereby improving curability and tends to easily obtain more excellent dielectric properties, heat resistance, and conductor adhesion.

[0336] (E) The curing accelerator may be used alone or in combination of two or more.

[0337] From the viewpoint of efficiently forming the chemical bond of the resin component during heating, as (E) curing accelerator, it is preferred to include a radical polymerization initiator. The radical polymerization initiator plays a role as a polymerization initiator for free radical polymerization, and when exposed to energy such as light and heat, it decomposes into a substance with unpaired electrons. As the radical polymerization initiator, organic peroxides, inorganic peroxides, azo compounds, etc. described later can be cited, preferably organic peroxides.

[0338] Examples of the curing accelerator (E) include: acidic catalysts such as p-toluenesulfonic acid; amine compounds such as triethylamine, pyridine, tributylamine, and dicyandiamide; imidazole compounds such as methylimidazole, phenylimidazole, and 1-cyanoethyl-2-phenylimidazole; isocyanate-masked imidazole compounds such as an addition reaction product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole; tertiary amine compounds; quaternary ammonium compounds; phosphorus compounds such as triphenylphosphine; diisopropyl peroxide, 2,5-dimethyl Organic peroxides such as 2,5-bis(tert-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butylperoxyisopropyl monocarbonate, 1,3-di(tert-butylperoxyisopropyl)benzene; inorganic peroxides such as potassium persulfate, sodium persulfate, ammonium persulfate; azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2'-dimethylvaleronitrile); carboxylates of manganese, cobalt, zinc, etc.

[0339] Among them, from the viewpoint of the curing accelerating effect and storage stability, imidazole compounds, isocyanate-masked imidazole compounds, organic peroxides, and carboxylates are preferred, and isocyanate-masked imidazole compounds and organic peroxides are more preferred.

[0340] When the first resin composition contains (E) a curing accelerator, the content of the (E) curing accelerator is not particularly limited, but is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 4 to 8 parts by mass, relative to the total amount (100 parts by mass) of the (A) thermosetting resin and the (B) reactive liquid compound.

[0341] When the content of the curing accelerator (E) is at least the above lower limit, a sufficient curing acceleration effect tends to be easily obtained. On the other hand, when the content of the curing accelerator (E) is at most the above upper limit, storage stability tends to be further improved.

[0342] When the first resin composition contains a free radical polymerization initiator as the (E) curing accelerator, the content of the free radical polymerization initiator is not particularly limited, and is preferably 0.05 to 7 parts by mass, more preferably 0.5 to 5 parts by mass, and further preferably 2 to 4 parts by mass, relative to the total amount (100 parts by mass) of the (A) thermosetting resin and the (B) reactive liquid compound.

[0343] If the content of the radical polymerization initiator is above the lower limit, sufficient curing acceleration effect is easily obtained and the generation of volatile components is more easily suppressed. In addition, if the content of the radical polymerization initiator is below the upper limit, storage stability tends to be better.

[0344] <Other ingredients>

[0345] The first resin composition may further contain one or more optional components selected from resin materials other than the above-mentioned components, flame retardants, antioxidants, heat stabilizers, antistatic agents, ultraviolet absorbers, pigments, colorants, lubricants, organic solvents and additives other than these, as needed.

[0346] The above-mentioned optional components may be used alone or in combination of two or more.

[0347] The content of the optional components in the first resin composition is not particularly limited, and may be used as needed within a range that does not inhibit the effects of the present embodiment.

[0348] In addition, the first resin composition may not contain any of the above-mentioned components depending on the desired performance.

[0349] In addition, about the components which the said 1st resin composition can contain, the 2nd resin composition mentioned later can also contain all of them.

[0350] In particular, the description about the above-mentioned component (A) can be replaced with the description about the component (F) described later unless otherwise specified.

[0351] In addition, the description about the said (B) component can be replaced with the description about the (G) component mentioned later unless otherwise specified.

[0352] In addition, the description about the said (C) component can be replaced with the description about the (H) component mentioned later unless otherwise specified.

[0353] In addition, the description about the above-mentioned (D) component can be replaced with the description about the (I) component mentioned later unless otherwise specified.

[0354] In addition, unless otherwise specified, the description of the above-mentioned component (E) can be replaced with the description related to the component (J) described later.

[0355] In addition, regarding the description of the first resin composition, "the first resin composition" can be replaced with "the second resin composition" as needed.

[0356] <Thickness of the insulating member forming resin layer>

[0357] The thickness of the resin layer for forming the insulating component is not particularly limited and can be determined according to the application. From the perspective of effectively showing the characteristics of the resin film of this embodiment such as excellent flexibility, it is preferably 10 μm or more, more preferably 40 μm or more, further preferably 60 μm or more, and particularly preferably 80 μm or more.

[0358] The thickness of the insulating member forming resin layer is not particularly limited, but is preferably 1000 μm or less, more preferably 500 μm or less, further preferably 300 μm or less, and particularly preferably 200 μm or less from the viewpoint of economy and flexibility.

[0359] <<Undercoat-forming resin layer>>

[0360] The primer layer-forming resin layer included in the resin film of the present embodiment contains a second resin composition, and the second resin composition is preferably formed into a layer.

[0361] The second resin composition preferably contains one or more selected from (F) a thermosetting resin, (G) a compound that is liquid at 25° C., has a reactive group and has a molecular weight of 1000 or less [hereinafter, sometimes referred to as “(G) reactive liquid compound”], and (H) an inorganic filler.

[0362] <(F) Thermosetting resin>

[0363] The second resin composition tends to easily obtain more excellent heat resistance by containing the (F) thermosetting resin.

[0364] The description about the type of the (F) thermosetting resin is the same as that of the (A) thermosetting resin.

[0365] In the second resin composition, the content of the (F) thermosetting resin is not particularly limited, but is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, further preferably 15 to 40% by mass, and particularly preferably 20 to 30% by mass, relative to the total amount (100% by mass) of the resin components in the second resin composition.

[0366] When the content of the (F) thermosetting resin is greater than the above lower limit, the heat resistance, formability, processability and conductor adhesion tend to be better. In addition, when the content of the (F) thermosetting resin is less than the above upper limit, the dielectric properties tend to be better.

[0367] The upper limit of the content of the (F) thermosetting resin may be 80% by mass or less, 70% by mass or less, or 60% by mass or less, relative to the total amount (100% by mass) of the (F) thermosetting resin and the (G) reactive liquid compound. The lower limit of the content of the (F) thermosetting resin may be 5% by mass or more, 10% by mass or more, or 15% by mass or more, relative to the total amount (100% by mass) of the (F) thermosetting resin and the (G) reactive liquid compound.

[0368] <(G) Reactive liquid compound>

[0369] The second resin composition tends to easily obtain more excellent flexibility by containing the (G) reactive liquid compound.

[0370] The description of the type of the (G) reactive liquid compound is the same as that of the (B) reactive liquid compound.

[0371] In the second resin composition, the content of the (G) reactive liquid compound is not particularly limited, but is preferably 5 to 60% by mass, more preferably 8 to 40% by mass, further preferably 10 to 30% by mass, and particularly preferably 15 to 25% by mass, relative to the total amount (100% by mass) of the resin components in the second resin composition.

[0372] The content of the reactive liquid compound (G) in the second resin composition is not particularly limited, but is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and even more preferably 15 to 20% by mass relative to the total solid content (100% by mass) of the second resin composition.

[0373] When the content of the reactive liquid compound (G) is greater than or equal to the above lower limit, there is a tendency to easily obtain better flexibility. In addition, when the content of the reactive liquid compound (G) is less than or equal to the above upper limit, there is a tendency to easily suppress the generation of volatile components during heat curing.

[0374] <(H) Inorganic fillers>

[0375] The second resin composition tends to easily obtain more excellent low thermal expansion properties by containing the (H) inorganic filler.

[0376] The description of the types of the (H) inorganic filler is the same as that of the (C) inorganic filler.

[0377] Preferably, the second resin composition contains (H) an inorganic filler, the content of the (H) inorganic filler in the second resin composition by mass is less than the content of the (C) inorganic filler in the first resin composition by mass, and further preferably contains (F) a thermosetting resin and (G) a reactive liquid compound.

[0378] The content of the (H) inorganic filler in the second resin composition is not particularly limited, but is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass, relative to the total solid content (100% by mass) of the second resin composition.

[0379] When the content of the (H) inorganic filler is at least the above lower limit, the low thermal expansion property tends to be more favorable. When the content of the (H) inorganic filler is at most the above upper limit, the platability tends to be more favorable.

[0380] The difference [(1)-(2)] between the content (1) of the inorganic filler (C) in the first resin composition relative to the total solid content (100% by mass) of the first resin composition and the content (2) of the inorganic filler (H) in the second resin composition relative to the total solid content (100% by mass) of the second resin composition is not particularly limited, but is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, and even more preferably 50 to 70% by mass.

[0381] When the difference [(1)-(2)] is within the above range, it tends to be easier to achieve both low thermal expansion properties and platability.

[0382] The average particle size of the (H) inorganic filler is not particularly limited, but is preferably 0.005 to 0.1 μm, more preferably 0.01 to 0.05 μm, and further preferably 0.015 to 0.02 μm.

[0383] When the average particle size of the (H) inorganic filler is within the above range, the platability tends to be more favorable.

[0384] The content of the resin component in the second resin composition is not particularly limited, but is preferably 60 to 97% by mass, more preferably 70 to 95% by mass, and further preferably 85 to 92% by mass, relative to the total solid content (100% by mass) of the second resin composition.

[0385] When content of the resin component in the second resin composition is within the above range, the plating properties tend to be more favorable.

[0386] The resin components in the second resin composition refer to the component (F), the component (G), the component (I), the component (J), etc., and the component (H) is not included in the resin components.

[0387] <(I) Elastomers having a molecular weight exceeding 1000>

[0388] The second resin composition preferably further contains (I) an elastomer having a molecular weight exceeding 1000 [hereinafter, sometimes referred to as "(I) elastomer"].

[0389] There is a tendency that more excellent dielectric properties tend to be easily obtained by the second resin composition containing the (I) elastomer.

[0390] The description of the type of the elastomer (I) is the same as that of the elastomer (D).

[0391] The content of the elastomer (I) in the second resin composition is not particularly limited, but is preferably 10 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 50 to 60% by mass, relative to the total amount (100% by mass) of the resin components in the second resin composition.

[0392] When the content of the elastomer (I) is at least the above lower limit, more excellent dielectric properties tend to be easily obtained. On the other hand, when the content of the elastomer (I) is at most the above upper limit, more excellent heat resistance tends to be easily obtained.

[0393] <(J) Curing accelerator>

[0394] The second resin composition preferably further contains (J) a curing accelerator.

[0395] The second resin composition contains the (J) curing accelerator, thereby improving curability and tends to easily obtain more excellent dielectric properties, heat resistance, and conductor adhesion.

[0396] The description of the type of the (J) curing accelerator is the same as that of the (E) curing accelerator.

[0397] In the second resin composition, the content of the curing accelerator (J) is not particularly limited, but is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 1 to 5 parts by mass, relative to the total amount (100 parts by mass) of the thermosetting resin (F) and the reactive liquid compound (G).

[0398] When the content of the curing accelerator (J) is at least the above lower limit, a sufficient curing acceleration effect tends to be easily obtained. On the other hand, when the content of the curing accelerator (J) is at most the above upper limit, storage stability tends to be further improved.

[0399] When the second resin composition contains a free radical polymerization initiator as the (J) curing accelerator, the content of the free radical polymerization initiator is not particularly limited, but is preferably 0.05 to 7 parts by mass, more preferably 0.1 to 5 parts by mass, and further preferably 0.5 to 2 parts by mass, relative to the total amount (100 parts by mass) of the (F) thermosetting resin and the (G) reactive liquid compound.

[0400] If the content of the radical polymerization initiator is above the lower limit, sufficient curing acceleration effect is easily obtained and the generation of volatile components is more easily suppressed. In addition, if the content of the radical polymerization initiator is below the upper limit, storage stability tends to be better.

[0401] <Other ingredients>

[0402] The second resin composition may further contain other components that can be contained in the above-mentioned first resin composition.

[0403] <Thickness of the primer layer-forming resin layer>

[0404] The thickness of the undercoat layer-forming resin layer is not particularly limited, but is preferably 0.2 to 20 μm, more preferably 0.5 to 10 μm, further preferably 1 to 5 μm, and particularly preferably 1.5 to 3 μm.

[0405] If the thickness of the primer layer forming resin layer is above the lower limit, the plating property tends to be better. In addition, if the thickness of the primer layer forming resin layer is below the upper limit, the low thermal expansion property tends to be better.

[0406] The resin film of the present embodiment may have another layer between the insulating member forming resin layer and the undercoat layer forming resin layer, but a form in which the insulating member forming resin layer and the undercoat layer forming resin layer are directly laminated is preferred.

[0407] The resin film of the present embodiment may have layers other than the insulating member forming resin layer and the primer layer forming resin layer, but preferably has only the insulating member forming resin layer and the primer layer forming resin layer.

[0408] The resin film of this embodiment may be formed on a support, or may have a protective film on its surface. However, the support and the protective film are not included in the concept of the resin film.

[0409] <Thickness of resin film>

[0410] The thickness of the resin film is not particularly limited, but is preferably 15 μm or more, more preferably 45 μm or more, further preferably 65 μm or more, and particularly preferably 85 μm or more, from the viewpoint of effectively expressing the characteristic of the resin film of this embodiment, namely, excellent flexibility.

[0411] The thickness of the resin film of the present embodiment is not particularly limited, but is preferably 1020 μm or less, more preferably 510 μm or less, further preferably 305 μm or less, and particularly preferably 203 μm or less.

[0412] <Solvent content of resin film>

[0413] The content of the organic solvent in the resin film of this embodiment is preferably 2 mass % or less, more preferably 1 mass % or less, further preferably 0.5 mass % or less, and may be 0 mass % relative to the total amount of the resin film (100 mass %).

[0414] When the content of the organic solvent in the resin film is within the above range, the amount of the organic solvent volatilized during heat curing tends to be easily and sufficiently suppressed.

[0415] <Mass reduction rate of resin film at 170℃>

[0416] The mass reduction rate of the resin film of the present embodiment when heated and dried at 170° C. for 30 minutes in an air atmosphere [hereinafter sometimes referred to as “170° C. mass reduction rate”] is preferably 2.0 mass % or less, more preferably 1.5 mass % or less, further preferably 1.0 mass % or less, and may be 0 mass %.

[0417] When the mass reduction rate at 170° C. is within the above range, the amount of volatile components during heat curing tends to be easily suppressed.

[0418] The mass reduction rate at 170° C. can be measured by the method described in Examples.

[0419] <Dielectric properties of cured resin films>

[0420] The relative dielectric constant (Dk) of the cured product of the resin film of this embodiment at 10 GHz may be less than 3.0, less than 2.9, or less than 2.8. The smaller the relative dielectric constant (Dk), the better. The lower limit value is not particularly limited. Considering the balance with other physical properties, it may be, for example, 2.4 or more, or 2.5 or more.

[0421] The dielectric loss tangent (Df) of the cured product of the resin film of this embodiment at 10 GHz may be less than 0.0040, less than 0.0035, or less than 0.0030. The smaller the dielectric loss tangent (Df), the more preferred it is. The lower limit is not particularly limited, and considering the balance with other physical properties, it may be, for example, 0.0010 or more, or 0.0015 or more.

[0422] It should be noted that the relative dielectric constant (Dk) and the dielectric loss tangent (Df) are values ​​based on the cavity resonator perturbation method, and more specifically, are values ​​measured by the method described in the Examples.

[0423] The resin film of the present embodiment is suitable as, for example, a resin film for forming an insulating layer of a printed wiring board such as a multilayer printed wiring board or a resin film for semiconductor sealing of a semiconductor package.

[0424] <Method for producing resin film>

[0425] The method for producing the resin film of the present embodiment is not particularly limited, and the resin film can be produced, for example, by forming a primer layer forming resin layer on a support and forming an insulating member forming resin layer on the primer layer forming resin layer.

[0426] The undercoat layer-forming resin layer can be produced, for example, by applying a second resin composition containing an organic solvent [hereinafter, the second resin composition containing an organic solvent may be referred to as “second resin varnish”] on a support and then heating and drying the composition.

[0427] Examples of the support include plastic films, metal foils, and release papers.

[0428] Examples of the plastic film include films of polyolefins such as polyethylene, polypropylene, and polyvinyl chloride; polyester films such as polyethylene terephthalate [hereinafter, sometimes referred to as "PET"]. and polyethylene naphthalate; polycarbonate films, polyimide films, etc. Among them, polyethylene terephthalate films are preferred from the viewpoints of economic efficiency and handling properties.

[0429] As metal foil, for example, copper foil, aluminum foil, etc. can be cited. When copper foil is used as a support, the copper foil can also be used directly as a conductor layer to form a circuit. In this case, as copper foil, rolled copper foil, electrolytic copper foil, etc. can be used. When using a thin copper foil, from the viewpoint of improving workability, a copper foil with a carrier can be used.

[0430] The support may be a support subjected to a surface treatment such as matte treatment or corona treatment. Alternatively, the support may be a support subjected to a release treatment using a silicone resin-based release agent, an alkyd resin-based release agent, a fluororesin-based release agent, or the like.

[0431] The thickness of the support is not particularly limited, but is preferably 10 to 150 μm, more preferably 20 to 100 μm, and even more preferably 25 to 50 μm from the viewpoint of handling ease and economic efficiency.

[0432] As a coating device for coating the second resin varnish, for example, a coating device known to those skilled in the art such as a comma coater, a bar coater, a kiss coater, a roll coater, a gravure coater, a die coater, etc. These coating devices can be appropriately selected according to the film thickness to be formed.

[0433] The drying conditions after applying the second resin varnish may be appropriately determined according to the content, boiling point, etc. of the organic solvent, and are not particularly limited.

[0434] For example, in the case of a second resin varnish containing 30 to 50% by mass of an aromatic hydrocarbon solvent, the drying temperature is not particularly limited, but is preferably 50 to 200° C., more preferably 80 to 150° C., and even more preferably 100 to 130° C. from the viewpoint of productivity and making the second resin composition appropriately B-staged.

[0435] In the case of the second resin varnish, the drying time is not particularly limited, but is preferably 1 to 30 minutes, more preferably 2 to 15 minutes, and even more preferably 3 to 10 minutes from the viewpoint of productivity and making the second resin composition appropriately B-staged.

[0436] Next, the resin film of the present embodiment can be obtained by coating the first resin composition containing an organic solvent [hereinafter, the first resin composition containing an organic solvent is sometimes referred to as "first resin varnish"] on the above-formed primer layer-forming resin layer and then heating and drying the coating to form an insulating member-forming resin layer on the primer layer-forming resin layer.

[0437] The coating device for coating the first resin varnish may be the same as the coating device for coating the second resin varnish.

[0438] The drying conditions after applying the first resin varnish may be appropriately determined according to the content, boiling point, etc. of the organic solvent, and are not particularly limited.

[0439] For example, in the case of a first resin varnish containing 40 to 60% by mass of an aromatic hydrocarbon solvent, the drying temperature is not particularly limited, but is preferably 50 to 200° C., more preferably 80 to 150° C., and even more preferably 100 to 130° C. from the viewpoint of productivity and making the first resin composition appropriately B-staged.

[0440] In the case of the first resin varnish, the drying time is not particularly limited, but is preferably 1 to 30 minutes, more preferably 2 to 15 minutes, and even more preferably 3 to 10 minutes from the viewpoint of productivity and making the first resin composition appropriately B-staged.

[0441] [Printed circuit board]

[0442] The printed wiring board of the present embodiment is a printed wiring board having a cured product of the resin film of the present embodiment.

[0443] The printed wiring board of this embodiment preferably comprises: a circuit substrate; an insulating layer formed by a cured product of a resin layer for forming an insulating component possessed by a resin film of this embodiment in which a circuit possessed by the circuit substrate is embedded; a primer layer formed by a resin layer for forming a primer layer possessed by the resin film of this embodiment and disposed on a surface of the insulating layer opposite to the above-mentioned circuit substrate; and a circuit disposed on a surface of the primer layer opposite to the above-mentioned insulating layer.

[0444] Hereinafter, one aspect of the method for manufacturing a printed wiring board according to the present embodiment will be described.

[0445] When a printed wiring board is produced using the resin film of the present embodiment, first, the resin film of the present embodiment is laminated on one or both surfaces of a circuit board so that the insulating member forming resin layer faces the circuit board side.

[0446] Examples of the circuit board include a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, a thermosetting polyphenylene ether substrate, etc., on one or both sides of which a patterned conductor layer is formed.

[0447] Next, the circuit board on which the resin film is laminated is heated to cure the insulating member forming resin layer, thereby forming an insulating layer that embeds the circuit of the circuit board.

[0448] The heating temperature during heat curing is not particularly limited, but is preferably 100 to 300°C, more preferably 120 to 280°C, and further preferably 150 to 250°C.

[0449] The heating time during heat curing is not particularly limited, but is preferably 2 to 300 minutes, more preferably 5 to 200 minutes, and even more preferably 10 to 150 minutes.

[0450] The insulating layer formed by the above method has a primer layer formed of a primer layer-forming resin layer on the surface opposite to the circuit board.

[0451] Then, the holes can be opened as required.

[0452] The hole opening is a process of opening holes in a circuit substrate formed with an insulating layer and a primer layer by a method such as drilling, laser, plasma, or a combination thereof to form via holes (Japanese: ビアホール), through holes (Japanese: スルーホール), etc. Examples of the laser used for the hole opening include carbon dioxide laser, YAG laser, UV laser, excimer laser, etc.

[0453] Next, the surface of the primer layer may be roughened with an oxidant, and if vias and through holes are formed, the so-called "smear" generated when forming them may be removed with the oxidant. The roughening and removal of the smear may be performed simultaneously.

[0454] Next, a conductor layer is formed on the roughened surface of the primer layer by plating.

[0455] Examples of plating methods include electroless plating and electrolytic plating. Examples of metals for plating include copper, gold, silver, nickel, platinum, molybdenum, ruthenium, aluminum, tungsten, iron, titanium, chromium, and alloys containing at least one of these metal elements. Among them, copper and nickel are preferred, and copper is more preferred.

[0456] As a method for patterning the conductor layer and forming a circuit, for example, a subtractive method, a full additive method, a semi-additive process (SAP: SemiAdditive Process), a modified semi-additive process (m-SAP: modified Semi Additive Process) and the like can be used.

[0457] Furthermore, a multilayer printed wiring board can be manufactured by appropriately repeating necessary steps.

[0458] [Semiconductor package]

[0459] The semiconductor package of the present embodiment is a semiconductor package including a cured product of the resin film of the present embodiment.

[0460] The semiconductor package of the present embodiment may be a semiconductor package manufactured by mounting a semiconductor chip on a printed wiring board of the present embodiment, for example. The semiconductor chip may be mounted on the printed wiring board by a known method.

[0461] The semiconductor package of the present embodiment may be a semiconductor package produced by sealing a semiconductor chip with a cured product of the resin film of the present embodiment, for example.

[0462] Sealing of the semiconductor chip with the resin film can be performed, for example, by placing the resin film on the semiconductor chip so as to contact the insulating member forming resin layer, heating and melting the resin film to embed the semiconductor chip, and then heating and curing it in this state.

[0463] Example

[0464] Hereinafter, the present embodiment will be described in detail with reference to examples, but the present embodiment is not limited to the following examples.

[0465] (Method for determining number average molecular weight)

[0466] The number average molecular weight is converted by gel permeation chromatography (GPC) based on a calibration curve using standard polystyrene. The calibration curve uses standard polystyrene: TSKstandard POLYSTYRENE (model: A-2500, A-5000, F-1, F-2, F-4, F-10, F-20, F-40) (manufactured by Tosoh Corporation, trade name), and is approximated by a cubic formula. The measurement conditions of GPC are shown below.

[0467] [GPC measurement conditions]

[0468] Device: High-speed GPC device HLC-8320GPC

[0469] Detector: UV-8320 ultraviolet absorption detector [manufactured by Tosoh Corporation]

[0470] Column: Guard column; TSK Guardcolumn SuperHZ-L + column; TSKgel SuperHZM-N + TSKgelSuperHZM-M + TSKgel SuperH-RC (all manufactured by Tosoh Corporation, trade names)

[0471] Column size: 4.6×20mm (guard column), 4.6×150mm (column), 6.0×150mm (reference column)

[0472] Eluent: Tetrahydrofuran

[0473] Sample concentration: 10mg / 5mL

[0474] Injection volume: 25 μL

[0475] Flow rate: 1.00mL / min

[0476] Measuring temperature: 40℃

[0477] [Manufacturing of modified conjugated diene polymer]

[0478] Production Example 1

[0479] Into a 2L glass flask container equipped with a thermometer, a reflux condenser and a stirring device, which can be heated and cooled, 33.8 parts by mass of 1,2-polybutadiene homopolymer (number average molecular weight = 1200, vinyl content = 85% or more), 1.43 parts by mass of an aromatic bismaleimide resin containing an indane ring (the compound represented by the above general formula (A1-4-1), number average molecular weight = 1300), 0.0035 parts by mass of tert-butyl peroxyisopropyl carbonate and toluene as an organic solvent were added. Next, under a nitrogen atmosphere, the mixture was reacted at 90 to 100° C. while stirring for 5 hours, thereby obtaining a solution of a modified conjugated diene polymer (solid content concentration: 35% by mass). The number average molecular weight of the obtained modified conjugated diene polymer was 1700.

[0480] In addition, for the 1,2-polybutadiene homopolymer before the start of the reaction and the solution of the aromatic bismaleimide resin containing indane rings, and the solution after the reaction, GPC is measured by the above method to obtain the peak area of ​​the aromatic bismaleimide resin containing indane rings before and after the reaction. Next, the vinyl modification rate of the aromatic bismaleimide resin containing indane rings is calculated by the following formula. It should be noted that the vinyl modification rate is equivalent to the reduction rate of the peak area of ​​the aromatic bismaleimide resin containing indane rings based on the reaction.

[0481] Vinyl modification rate (%) = [(peak area derived from the aromatic bismaleimide resin containing an indane ring before the reaction) - (peak area derived from the aromatic bismaleimide resin containing an indane ring after the reaction)] × 100 / (peak area derived from the aromatic bismaleimide resin containing an indane ring before the reaction)

[0482] The vinyl modification ratio determined from the above formula was 40%.

[0483] [Manufacturing of resin film]

[0484] Examples 1 and 2

[0485] (Manufacturing of First and Second Resin Compositions)

[0486] After each component described in Table 1 was blended with toluene in the blending amount described in Table 1, the mixture was stirred and mixed while being heated at 25° C. or 50 to 80° C., thereby preparing a first resin composition having a solid content concentration of about 50% by mass and a second resin composition having a solid content concentration of about 38% by mass. It should be noted that in Table 1, the unit of the blending amount of each component is part by mass, and in the case of a solution, it refers to part by mass converted to solid content.

[0487] (Manufacturing of resin film)

[0488] The second resin composition obtained in each example was applied on one surface of a 50 μm thick PET film (manufactured by Toyobo Co., Ltd., trade name "Purex A53") so that the thickness of the primer layer-forming resin layer after drying was the thickness described in Table 1. Then, the second resin composition was heated and dried at 105° C. for 5 minutes to be in a B-stage state, thereby forming a primer layer-forming resin layer on the PET film.

[0489] Next, the first resin composition obtained in each example was applied on the primer-forming resin layer so that the thickness of the insulating member-forming resin layer after drying was the thickness described in Table 1. Then, the first resin composition was heated and dried at 105° C. for 5 minutes, thereby bringing the first resin composition into a B-stage state, and forming an insulating member-forming resin layer on the primer-forming resin layer. In this way, a single-sided PET film-coated resin film (the thickness of the resin film was 100 μm) having a PET film, a primer-forming resin layer, and an insulating member-forming resin layer in this order was produced.

[0490] Next, the obtained resin film with PET film on one side was cut into 200 mm×200 mm, and the resin films were overlapped so as to face each other. Next, a vacuum laminator was used to laminate the resin film at a temperature of 100° C. and a press time of 5 seconds, thereby obtaining a resin film with PET film on both sides (the thickness of the resin film was 200 μm).

[0491] (Manufacturing of resin sheets with copper foil on both sides)

[0492] The resin film with PET film on both sides obtained above was cut into a size of 90 mm in length × 50 mm in width, and the PET films on both sides were peeled off and removed. A Teflon (registered trademark) sheet with a thickness of 0.2 mm punched out to a size of 90 mm in length × 50 mm in width was placed on the copper foil, and the resin film after the PET film was peeled off was put into the punched out part, and further, the copper foil was placed thereon to obtain a laminate. It should be noted that the copper foil used a low-profile copper foil with a thickness of 18 μm (manufactured by Mitsui Mining and Smelting Co., Ltd., trade name "3EC-VLP-18"), and was arranged in a manner that the M side became the resin film side. Then, the above-mentioned laminate was heated and pressurized under the conditions of a temperature of 180°C, a pressure of 2.0 MPa, and a time of 60 minutes, and the resin film was formed into a resin plate while being cured, thereby making a resin plate with copper foil on both sides. The thickness of the resin plate portion of the obtained resin plate with copper foil on both sides is 0.2 mm.

[0493] (Manufacturing of Laminated Board with Cured Resin Layers on Both Sides)

[0494] The resin film with a PET film on one side obtained above was laminated on both sides of a double-sided copper-clad laminate (manufactured by Showa Denko Materials Co., Ltd., trade name "MCL-E-700GR") subjected to CZ treatment in such a manner that the resin film and the double-sided copper-clad laminate were in contact. The lamination was performed by the following method: after reducing the pressure at 100° C. for 15 seconds, the pressure was set to 0.5 MPa and pressed for 45 seconds, and then pressed at 130° C. for 60 seconds under the conditions of a crimping pressure of 0.5 MPa.

[0495] Next, the laminated board with the resin film with PET film on one side laminated on both sides was heated in an explosion-proof dryer at 180°C for 60 minutes to cure the resin film. Then, the PET films on both sides were removed, thereby obtaining a laminated board with a double-sided resin cured material layer having a resin cured material layer formed by curing the resin film on both sides. The resin cured material layer has an insulating layer as a cured material of the resin layer for forming an insulating member on the double-sided copper-clad laminated board side, and a primer layer on the exposed surface.

[0496] Comparative Example 1

[0497] In Example 1, except that the resin layer for forming the primer layer was not formed, a single-sided PET film (the thickness of the resin film was 100 μm) was prepared in the same manner as in Example 1, in which a resin layer for forming an insulating member was formed on one side of the PET film. Using this single-sided PET film-bearing resin film, a resin plate with copper foil on both sides and a laminated plate with resin cured material layers on both sides were prepared in the same manner as in Example 1.

[0498] [Measurement and evaluation methods]

[0499] The resin films with PET film on one side, the resin plates with copper foil on both sides, and the laminated plates with cured resin layers on both sides obtained in the above Examples and Comparative Examples were used to perform various measurements and evaluations according to the following methods.

[0500] (1. Evaluation method of flexibility)

[0501] The single-sided PET film obtained in each example was wound around a resin cylinder with a diameter of 85 mm at 25° C. with the resin film surface facing outward. The appearance of the wound resin film was visually observed and evaluated according to the following criteria. In the following criteria, A indicates the best.

[0502] <Flexibility Criteria>

[0503] A: No cracks in the resin film or peeling from the PET film were observed.

[0504] B: Cracks of the resin film or peeling from the PET film was observed.

[0505] (2. Determination and evaluation method of linear expansion coefficient and glass transition temperature)

[0506] The resin plate with copper foil on both sides obtained in each example was immersed in a 10% by mass solution of ammonium persulfate (Mitsubishi Gas Chemical Co., Ltd.) as a copper etching solution to remove the copper foil. The obtained resin plate was cut into a width of 0.4 mm and a length of 20 mm, and then dried at 105°C for 1 hour to serve as a test piece. The test piece was clamped at both ends of the long side direction of the test piece with upper and lower clamps in a manner that the interval between the clamps was 10 mm. Next, a thermomechanical measuring device (TMA) (Seiko Instruments Co., Ltd., trade name "SS6100") was used to measure the dimensional change under the conditions of tensile mode, temperature range of 30 to 300°C, heating rate of 5°C / min, and load of 4g. The inflection point of the dimensional change relative to temperature was taken as the glass transition temperature, and the average value of the dimensional change per unit temperature of 30 to 150°C was taken as the linear expansion coefficient, and evaluated according to the following criteria. In the following criteria, A represents the best.

[0507] <Determination criteria of linear expansion coefficient>

[0508] A: Less than 20ppm / K

[0509] B: 20ppm / K or more and less than 40ppm / K

[0510] <Criteria for determining glass transition temperature>

[0511] A: Above 180℃

[0512] B: less than 180℃

[0513] (3.25℃ tensile elastic modulus measurement and evaluation method)

[0514] The resin plate with copper foil on both sides obtained in each example was immersed in a 10% by mass solution of ammonium persulfate (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a copper etching solution to remove the copper foil. The obtained resin plate was cut into a width of 10 mm and a length of 40 mm, and then dried at 105°C for 1 hour to serve as a test piece. The test piece was clamped at both ends of the long side direction of the test piece with upper and lower clamps in a manner that the interval between the clamps was 20 mm. Next, a small desktop testing machine (manufactured by Shimadzu Corporation, trade name "EZ-TEST") was used to obtain the tensile modulus of the above test piece under an environment of 25°C and a tensile speed of 2 mm / min. Five identical samples were made, and the tensile modulus was obtained under the same conditions as above, and the average value was used as the 25°C tensile modulus. Other detailed conditions and the calculation method of the tensile modulus were carried out in accordance with the international standard ISO5271 (1993). The obtained 25°C tensile modulus was evaluated according to the following judgment criteria. In the following criteria, A indicates the best.

[0515] <25℃ tensile modulus of elasticity determination criteria>

[0516] A: less than 1.5GPa

[0517] B: 1.5GPa or above

[0518] (4. Evaluation method of plating properties)

[0519] The laminate with the resin cured material layer on both sides obtained in each example was immersed in a swelling solution (manufactured by Atotech Japan Co., Ltd., trade name "Swelling Dip Securiganth P") heated to 60°C for 10 minutes. Next, it was immersed in a roughening solution (manufactured by Atotech Japan Co., Ltd., trade name "CONCENTRATE COMPACT (Japanese: コンセートレートコンパクト) CP") heated to 80°C for 10 minutes. Next, it was immersed in a neutralizing solution (manufactured by Atotech Japan Co., Ltd., trade name "Reduction Solution Securiganth (Japanese: リダクションソリューションセキュリガント) P500") heated to 40°C for 5 minutes for neutralization. In this way, the surface of the resin cured material layer was roughened.

[0520] Next, degreasing cleaning was performed by treating with an alkaline cleaner at 60°C (manufactured by Atotech Japan Co., Ltd., trade name "Cleaner Securiganth 902") for 5 minutes. After cleaning, treating with a pre-dip solution at 23°C (manufactured by Atotech Japan Co., Ltd., trade name "Pre-dip Neoganth B") for 2 minutes. Then, treating with an activator solution at 40°C (manufactured by Atotech Japan Co., Ltd., trade name "Activator Neoganth 834") for 5 minutes to allow the palladium catalyst to adhere. Next, treat with a 30°C reducing solution (manufactured by Atotech Japan Co., Ltd., trade name "Reducer Neoganth (Japanese: リデューサーネオガント) WA") for 5 minutes. Next, add a chemical copper solution (manufactured by Atotech Japan Co., Ltd., trade name "Basic Printoganth (Japanese: ベーシックプリントガント) MSK-DK") and perform non-electrolytic plating until the plating thickness on the resin cured layer reaches 0.5μm. After non-electrolytic plating, in order to relieve the residual stress in the plating film and remove the residual hydrogen, a baking treatment is performed at 120°C for 15 minutes. Next, the surface treated with non-electrolytic plating is further electroplated until the plating thickness on the resin cured layer reaches 20μm, forming a copper plating layer. After electrolytic plating, heat at 180°C for 120 minutes.

[0521] The appearance of the obtained copper plating layer was visually observed and evaluated according to the following criteria. In the following criteria, A represents the best.

[0522] <Criteria for judging plating properties>

[0523] A: No expansion or peeling of the copper plating layer was observed.

[0524] B: Swelling or peeling of the copper plating layer was observed.

[0525] (5. Measurement and evaluation method of relative dielectric constant (Dk) and dielectric loss tangent (Df))

[0526] The resin plate with copper foil on both sides obtained in each example is immersed in a 10% by mass solution of ammonium persulfate (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a copper etching solution to remove the copper foil. The obtained resin plate is cut into 2 mm × 50 mm pieces, dried at 105°C for 1 hour, and used as a test piece. Next, according to the cavity resonator perturbation method, the relative dielectric constant (Dk) and dielectric loss tangent (Df) of the above test piece are measured at an atmosphere temperature of 25°C using a 10 GHz band, and evaluated according to the following criteria. In the following criteria, A represents the best.

[0527] <Criteria for determining relative dielectric constant (Dk)>

[0528] A: less than 2.8

[0529] B: 2.8 or above

[0530] <Determination criteria of dielectric loss tangent (Df)>

[0531] A: 0.0025 or more and less than 0.0030

[0532] B: 0.0030 or more

[0533] (6.170℃ mass reduction rate determination method)

[0534] After the PET film was peeled off from the resin film with a PET film on one side obtained in each example, the powder in the B-stage state obtained by crushing the resin film was used as an evaluation sample. Using this evaluation sample, the mass reduction rate when heated and dried at 170°C for 30 minutes in an atmospheric atmosphere [{(mass before heating - mass after heating at 170°C for 30 minutes) / (mass before heating)}×100] was taken as the mass reduction rate at 170°C. The results are shown in Table 1. It should be noted that in Table 1, "≤1.0" means that the mass reduction rate at 170°C is 1.0% by mass or less.

[0535] [Table 1]

[0536] Table 1

[0537]

[0538] It should be noted that the details of the components shown in Table 1 are as follows.

[0539] [Component (A), component (F)]

[0540] Maleimide resin: an aromatic bismaleimide resin containing an indane ring represented by the general formula (A1-4-1): number average molecular weight = 1300, solid at 25°C

[0541] [Component (B), component (G)]

[0542] 1,9-nonanediol diacrylate: liquid at 25°C (viscosity at 25°C = 8 mPa·s), molecular weight: 268.35

[0543] [(C) ingredient]

[0544] Silica: Spherical silica treated with aminosilane coupling agent, average particle size 0.5 μm

[0545] [Component (D), component (I)]

[0546] Modified conjugated diene polymer: the modified conjugated diene polymer obtained in Preparation Example 1, number average molecular weight 1700

[0547] Styrene elastomer: hydrogenated styrene thermoplastic elastomer (styrene-ethylene-butylene-styrene copolymer), trade name "Tuftec H1221", styrene content = 12% by mass, MFR under the measurement conditions of 230°C and a load of 2.16 kgf = 4.5 g / 10 min, number average molecular weight = 170,000

[0548] [Component (E), component (J)]

[0549] Organic peroxide: 1,3-di(tert-butylperoxyisopropyl)benzene

[0550] Imidazole curing accelerator: Isocyanate-masked imidazole, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "G-8009L"

[0551] [(H) ingredient]

[0552] ·Silicon dioxide: average particle size 0.016μm

[0553] According to the above results, the resin films of Examples 1 and 2 of the present embodiment have excellent flexibility and their cured products have excellent plating properties. In addition, the mass reduction rate of the resin films of Examples 1 and 2 at 170°C is 1.0 mass % or less, and the generation of volatile components during heat curing is suppressed. On the other hand, the resin film of Comparative Example 1 has poor plating properties.

[0554] Industrial Applicability

[0555] The resin film of the present embodiment can form a cured product having excellent plating properties, has excellent flexibility, and can suppress the generation of volatile components during heat curing. Therefore, the resin film of the present embodiment is useful for printed wiring boards, semiconductor packages, and the like.

Claims

1. A resin film comprising: an insulating member-forming resin layer comprising a first resin composition; and The undercoat layer-forming resin layer is provided on one side of the insulating member-forming resin layer and contains a second resin composition. The first resin composition contains: A thermosetting resin; B a compound which is liquid at 25° C., has a reactive group and has a molecular weight of 1000 or less; and C an inorganic filler.

2. The resin film according to claim 1, wherein The component A is one or more selected from a maleimide resin having one or more N-substituted maleimide groups and a derivative of the maleimide resin.

3. The resin film according to claim 2, wherein The maleimide resin having one or more N-substituted maleimide groups is a maleimide resin having a condensed ring of an aromatic ring and an aliphatic ring in its molecular structure and having two or more N-substituted maleimide groups.

4. The resin film according to any one of claims 1 to 3, wherein The component B has, as the reactive group, one or more selected from the group consisting of a functional group including an ethylenically unsaturated bond, an epoxy group, a hydroxyl group, a carboxyl group, and an amino group.

5. The resin film according to any one of claims 1 to 3, wherein The component B has two or more reactive groups in one molecule.

6. The resin film according to any one of claims 1 to 3, wherein The component B is di(meth)acrylate.

7. The resin film according to any one of claims 1 to 3, wherein The content of the component B is 0.5% by mass to 20% by mass based on 100% by mass, which is the total solid content of the first resin composition.

8. The resin film according to any one of claims 1 to 3, wherein The second resin composition contains H inorganic filler, The content of the H inorganic filler in the second resin composition, based on mass, is less than the content of the C inorganic filler in the first resin composition, based on mass.

9. The resin film according to claim 8, wherein The second resin composition further contains: F a thermosetting resin; and G a compound which is liquid at 25° C., has a reactive group and has a molecular weight of 1000 or less.

10. The resin film according to any one of claims 1 to 3, wherein The insulating member forming resin layer has a thickness of 80 μm or more.

11. The resin film according to any one of claims 1 to 3, wherein The thickness of the primer layer-forming resin layer is 0.2 μm to 20 μm. 12 . The resin film according to claim 1 , wherein the mass reduction rate after heat drying at 170° C. for 30 minutes in an air atmosphere is 2.0 mass % or less. 13 . A printed wiring board comprising a cured product of the resin film according to claim 1 . 14 . A semiconductor package comprising a cured product of the resin film according to claim 1 .

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