Resin films, printed circuit boards, and semiconductor packages

Abstract

A resin film comprising a resin composition including a curable resin and an inorganic filler, wherein the content of the inorganic filler is greater than 50 volume% and the minimum melt viscosity is 2000 Pa·s or less.

Description

Technology Field

[0001] The present disclosure relates to a resin film, a printed circuit board, and a semiconductor package. Background Technology

[0002] Insulating materials are used in electronic components such as printed circuit boards and semiconductor packages for the purpose of protecting components and wiring or for electrical insulation. As such insulating materials, resin compositions in various forms, such as liquid, tablet, and sheet forms, are being developed.

[0003] For example, Patent Document 1 describes a resin film comprising a compound having an N-substituted maleimide group as a curable resin. Prior art literature

[0004] International Publication No. 2023 / 282313 The problem to be solved

[0005] A resin film containing a curable resin is sometimes used for the purpose of filling concave areas of a substrate having irregularities formed on its surface.

[0006] Specifically, a resin film is placed on a substrate having irregularities formed on its surface, and the resin film is heated to soften it. In this state, the resin film is pressed to deform it so as to fill the concave portions of the substrate. If the deformation of the resin film at this time is insufficient, there is a risk of defects occurring, such as voids being curled up. However, generally, making the resin sheet more deformable tends to increase the coefficient of thermal expansion after curing. An increase in the coefficient of thermal expansion may cause other problems, such as increased warping of the substrate to which the resin sheet is attached.

[0007] In light of the above circumstances, one embodiment of the present disclosure aims to provide a resin film having excellent deformability before curing and a low coefficient of thermal expansion after curing, a printed circuit board obtained using the resin film, and a semiconductor package obtained using the resin film. means of solving the problem

[0008] Specific means for solving the above problem include the following aspects.

[0009] <1> A resin composition comprising a curable resin and an inorganic filler, and

[0010] A resin film having a content of the above-mentioned inorganic filler of more than 50 volume% and a minimum melt viscosity of 2000 Pa·s or less.

[0011] <2> The above-mentioned curable resin includes a radical polymerizable curable resin, <1> Resin film listed in

[0012] <3> The above-mentioned curable resin comprises a curable resin having a molecular weight of 2000 or less, <1> or <2> Resin film listed in

[0013] <4> The above-mentioned inorganic filler having a content of 70 volume% or less, <1> inside <3> A resin film described in any one of the following items.

[0014] <5> For use as a sealant for semiconductor packages, <1> inside <4> A resin film described in any one of the following items.

[0015] <6> For forming an insulating layer of a printed circuit board, <1> inside <4> A resin film described in any one of the following items.

[0016] <7> <1> inside <4> A printed circuit board comprising a cured resin film as described in any one of the claims.

[0017] <8> <1> inside <4> A semiconductor package comprising a cured resin film as described in any one of the claims. Effects of the invention

[0018] According to one embodiment of the present disclosure, a resin film having excellent deformability before curing and a low coefficient of thermal expansion after curing, a printed circuit board obtained using the resin film, and a semiconductor package obtained using the resin film are provided. Specific details for implementing the invention

[0019] In the present disclosure, the term “process” includes, in addition to processes independent from other processes, processes that cannot be clearly distinguished from other processes, provided that the purpose of such processes is achieved.

[0020] In the numerical range indicated using “to” in the present disclosure, the numerical values ​​described before and after “to” are included as the minimum value and the maximum value, respectively.

[0021] In the numerical ranges described stepwise in the present disclosure, an upper or lower limit value described in one numerical range may be substituted with an upper or lower limit value of another numerical range described stepwise. Additionally, in the numerical ranges described in the present disclosure, an upper or lower limit value of said numerical range may be substituted with a value shown in the examples.

[0022] In the present disclosure, each component may include multiple types of corresponding substances. Where multiple types of substances corresponding to each component exist in the composition, the content or content of each component refers to the content or content of the total of the multiple substances present in the composition, unless specifically mentioned otherwise.

[0023] In the present disclosure, "resin composition" means a mixture of at least two components containing at least a resin. If the resin composition includes a curable component, a state in which at least a portion of the curable component has reacted is also included in the resin composition.

[0024] In the present disclosure, "solids" means components other than volatile components such as solvents.

[0025] In the present disclosure, “(meth)acrylate” means “acrylate” or “methacrylate,” “(meth)acryl” means “acryl” or “methacryl,” and “(meth)acryloyl” means “acryloyl” or “methacryloyl.”

[0026] In the present disclosure, the term "molecular weight" of a compound means the molecular weight that can be calculated from the structural formula when the compound is not a polymer and the structural formula of the compound can be determined, and means the number average molecular weight or weight average molecular weight when the compound is a polymer.

[0027] The mechanisms of action described in this specification are conjectures and do not limit the mechanisms by which the resin composition according to this embodiment exerts its effects.

[0028] An embodiment comprising any combination of the details described in this specification is also included in this embodiment.

[0029] Suzy Film

[0030] The resin film of the present disclosure comprises a resin composition including a curable resin and an inorganic filler, wherein the content of the inorganic filler is greater than 50 volume% and the minimum melt viscosity is 2000 Pa·s or less.

[0031] As shown in the embodiments described below, the resin film of the present disclosure has excellent deformability before curing and also has a low coefficient of thermal expansion after curing.

[0032] As a measure to make the resin sheet easier to deform before curing, it is considered to increase the flexibility of the resin sheet by reducing the amount of inorganic filler. However, reducing the amount of inorganic filler increases the coefficient of thermal expansion after the resin sheet is cured. An increase in the coefficient of thermal expansion may cause other problems, such as increased warping of the substrate to which the resin sheet is attached.

[0033] The resin film of the present disclosure makes it easy to deform the resin film before curing without reducing the amount of inorganic filler by setting the minimum melt viscosity to 2000 Pa·s or less.

[0034] That is, the resin film of the present disclosure can satisfy both of the contradictory characteristics of ease of deformation before curing and reduction of the coefficient of thermal expansion after curing.

[0035] From the perspective of ease of deformation before curing, the lowest melt viscosity of the resin film is preferably 1800 Pa·s or less, more preferably 1700 Pa·s or less, and even more preferably 1600 Pa·s or less.

[0036] The lower limit of the minimum melt viscosity of the resin film is not particularly limited, but from the perspective of balance with other characteristics of the resin film, it is preferable that it be 600 Pa·s or higher, more preferable that it be 800 Pa·s or higher, and even more preferable that it be 1000 Pa·s or higher.

[0037] In the present disclosure, the lowest melt viscosity of the resin film is measured using a rheometer under the conditions described in the examples.

[0038] From the perspective of suppressing the warping of the substrate, it is desirable for the coefficient of thermal expansion of the resin film after curing to be as low as possible. For example, it is desirable for the coefficient of thermal expansion of the resin film after curing to be 25.0 ppm / K or less, and more desirable for it to be 20.0 ppm / K or less.

[0039] In the present disclosure, the coefficient of thermal expansion of the resin film after curing is measured by thermomechanical analysis (TMA) under the conditions described in the examples.

[0040] The resin film of the present disclosure comprises a resin composition comprising a curable resin and an inorganic filler.

[0041] Hereinafter, each component that may be contained in the resin composition constituting the resin film of the present disclosure will be described.

[0042] (Curing resin)

[0043] The resin composition includes a curable resin.

[0044] In the present disclosure, the term "curable resin" refers to a resin that exhibits the property of curing by causing a chemical reaction through treatment such as heating or irradiation with active rays.

[0045] Examples of curable resins that may be included in the resin composition include compounds having functional groups such as N-substituted maleimide groups, vinyl groups, (meth)acryloyl groups, epoxy groups, hydroxyl groups, carboxyl groups, and amino groups as reactive groups.

[0046] From the perspective of suitability for the manufacturing process of electronic components and heat resistance, it is preferable that the curable resin be a thermosetting resin that exhibits the property of curing upon heating.

[0047] One type of curable resin may be used alone, or two or more types may be used in combination.

[0048] From the perspective of handling properties of the resin film, it is preferable that at least one of the curable resins included in the resin composition is in a solid state at 25°C, and it is more preferable that at least one of the curable resins included in the resin composition is in a solid state at 25°C and at least one is in a liquid state at 25°C.

[0049] The curable resin included in the resin composition may be radical polymerizable.

[0050] A resin composition containing a radical polymerizable curable resin is less prone to changes in properties during storage compared to, for example, a resin composition containing an epoxy resin. For this reason, it offers advantages such as the ability to store at room temperature.

[0051] Among radical polymerizable curable resins, maleimide resin is preferred in terms of heat resistance and dielectric properties (low dielectric constant).

[0052] In the present disclosure, maleimide resin means a compound having an N-substituted maleimide group as a reactive group.

[0053] In terms of curing reactivity, it is preferable that the maleimide resin be a compound having two N-substituted maleimide groups (hereinafter also referred to as bis-maleimide resin) or a compound having three or more N-substituted maleimide groups (hereinafter also referred to as polymaleimide resin).

[0054] In terms of heat resistance, it is preferable that the maleimide resin be a compound having an N-substituted maleimide group directly bonded to an aromatic ring (hereinafter also referred to as aromatic maleimide resin), and it is more preferable that the maleimide resin be a compound having two or three or more N-substituted maleimide groups directly bonded to an aromatic ring (hereinafter also referred to as aromatic bismaleimide resin or aromatic polymaleimide resin).

[0055] The maleimide resin included in the resin composition may be of only one type or two or more types.

[0056] The maleimide resin included in the resin composition may be a compound having N-substituted maleimide groups at each of the two ends of the molecule. Examples of compounds having N-substituted maleimide groups at each of the two ends of the molecule include compounds represented by the following formula (A1).

[0057]

[0058] During the meal, X a11 is a divalent organic group. X a11 The structure of the divalent organic group represented by X is not particularly limited. a11 The divalent organic group represented by may include a structure in which homologous structural units are connected, and may further include an N-substituted maleimide group.

[0059] Maleimide resins may include condensed rings of aromatic and aliphatic rings. A preferred example of a condensed ring of aromatic and aliphatic rings is a monocyclic ring. A monocyclic ring refers to a condensed binary structure of an aromatic six-membered ring and a saturated aliphatic five-membered ring. The monocyclic ring included in the maleimide resin is preferably included as a divalent group represented by the following general formula (A1-1).

[0060]

[0061] During the meal, R a1 is an alkyl group having 1 to 10 carbon atoms, an alkyloxy 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. R a2 to R a4 Each is independently an alkyl group having 1 to 10 carbon atoms. * indicates a bonding site (likewise below).

[0062] R a1 Examples of alkyl groups having 1 to 10 carbon atoms represented by include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups. These alkyl groups may be either straight-chain or branched-chain.

[0063] R a1 Examples of alkyl groups included in the alkyloxy group having 1 to 10 carbon atoms and the alkylthio group having 1 to 10 carbon atoms represented by are the same as the alkyl group having 1 to 10 carbon atoms.

[0064] R a1 Examples of aryl groups having 6 to 10 carbon atoms represented by phenyl groups, naphthyl groups, etc.

[0065] R a1Examples of aryl groups included in the aryloxy group having 6 to 10 carbon atoms and the arylthio group having 6 to 10 carbon atoms represented by are the same as the aryl group having 6 to 10 carbon atoms.

[0066] R a1 Examples of cycloalkyl groups having 3 to 10 carbon atoms represented by include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, etc.

[0067] In terms of solubility and reactivity with respect to the solvent, R a1 It is preferable that the silver is 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, and more preferable that the silver is an alkyl group having 1 to 4 carbon atoms.

[0068] R a2 to R a4 Examples of alkyl groups having 1 to 10 carbon atoms represented by include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups. These alkyl groups may be either straight-chain or branched-chain. Among these, R a2 to R a4 It is preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl or ethyl group, and even more preferably a methyl group.

[0069] n a1 n is an integer from 0 to 3. a1 If this is 2 or 3, 2 or 3 Rs a1 It may be the same or different.

[0070] The divalent group represented by the general formula (A1-1) is, in terms of ease of manufacture, n a1 This is 0, and R a2 to R a4It is preferable that each is a methyl group. Specifically, a divalent group represented by the following formula (A1-1a) is preferred, and a divalent group represented by the following formula (A1-1a') or a divalent group represented by the following formula (A1-1a'') is more preferred.

[0071]

[0072] The maleimide resin containing the ring is preferably an aromatic maleimide resin, more preferably an aromatic bismaleimide resin, and even more preferably a compound represented by the following general formula (A1-2).

[0073]

[0074] During the meal, R a1 to R a4 and n a1 is identical to that in general formula (A1-1). R a5 Each is independently an alkyl group having 1 to 10 carbon atoms, an alkyloxy 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 n are each independently integers from 0 to 4. a3 It is a number between 0.95 and 10.0.

[0075] Among the foods, multiple R a1 , plural n a1 , multiple R a5 or multiple n a2 Each may be the same or different.

[0076] n a3 If this exceeds 1, multiple R a2 , multiple R a3 or multiple R a4 Each may be the same or different.

[0077] R a5 Examples of alkyl groups having 1 to 10 carbon atoms represented by include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups. These alkyl groups may be either straight-chain or branched-chain.

[0078] R a5 Examples of alkyl groups included in the alkyloxy group having 1 to 10 carbon atoms and the alkylthio group having 1 to 10 carbon atoms represented by are the same as the alkyl group having 1 to 10 carbon atoms.

[0079] R a5 Examples of aryl groups having 6 to 10 carbon atoms represented by phenyl groups, naphthyl groups, etc.

[0080] R a5 Examples of aryl groups included in the aryloxy group having 6 to 10 carbon atoms and the arylthio group having 6 to 10 carbon atoms represented by are the same as the aryl group having 6 to 10 carbon atoms.

[0081] R a5 Examples of cycloalkyl groups having 3 to 10 carbon atoms represented by include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, etc.

[0082] In terms of solvent solubility and ease of manufacture, R a5 It is preferably 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, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group.

[0083] n in the formula a2 is an integer from 0 to 4, and is preferably an integer from 1 to 3, more preferably 2 or 3, and even more preferably 2, in terms of compatibility with other resins, dielectric properties, conductor adhesion and ease of manufacturing.

[0084] Also, n a2 When α is greater than 1, the benzene ring and the N-substituted maleimide group have twisted loci, and solvent solubility tends to be further improved due to the inhibition of intermolecular stacking. In terms of inhibiting intermolecular stacking, n a2 If is 1 or greater, R a5 It is preferable that the substitution position be an ortho position with respect to the N-substituted maleimide group.

[0085] n in the formula a3 With respect to dielectric properties, conductor adhesion, solvent solubility, handling properties, and heat resistance, the value is preferably 0.98 to 8.0, more preferably 1.0 to 7.0, and even more preferably 1.1 to 6.0. In addition, n a3 It represents the average value of the number of structural units containing the ring.

[0086] The maleimide resin represented by general formula (A1-2) is more preferably represented by the following general formula (A1-3) or, in terms of dielectric properties, conductor adhesion, solvent solubility, and ease of manufacturing.

[0087]

[0088] During the meal, R a1 to R a5 , n a1 and n a3 is identical to that in general formula (A1-2).

[0089]

[0090] During the meal, R a1 to R a4 , n a1 and n a3 is identical to that in general formula (A1-2).

[0091] Examples of maleimide resins represented by general formula (A1-3) include the maleimide resin represented by the following general formula (A1-3-1), the maleimide resin represented by the following general formula (A1-3-2), and the maleimide resin represented by the following general formula (A1-3-3).

[0092]

[0093] During the meal, n a3 is identical to that in general formula (A1-2).

[0094] The maleimide resin (A1) represented by the general formula (A1-4) is preferably represented by the following general formula (A1-4-1).

[0095]

[0096] During the meal, n a3 is identical to that in general formula (A1-2).

[0097] Maleimide resins containing a monoringe can be synthesized by known methods. For example, maleimide resins containing a monoringe can be synthesized by the method described in International Publication No. 2023 / 282313.

[0098] When the resin composition comprises a maleimide resin as a curable resin and also comprises a maleimide resin comprising a monocyclic ring as the maleimide resin, it is preferable that the content of the maleimide resin comprising the monocyclic ring be 50 mass% or more of the total maleimide resin, more preferable that it be 70 mass% or more, and even more preferable that it be 80 mass% or more. The content of the maleimide resin comprising the monocyclic ring may be 100 mass% of the total maleimide resin.

[0099] The number average molecular weight of the maleimide resin containing the monocyclic group is not particularly limited. In terms of compatibility with other resins, conductor adhesion, and heat resistance, the number average molecular weight of the maleimide resin is preferably 600 to 3,000, more preferably 800 to 2,000, and even more preferably 1,000 to 1,500.

[0100] In the present disclosure, the number average molecular weight or weight average molecular weight of a compound is measured in polystyrene equivalent by gel permeation chromatography (GPC). The measurement conditions for GPC are shown below.

[0101] Device: High-speed GPC device HLC-8320GPC

[0102] Detector: UV absorption detector UV-8320 [Manufactured by Toso Co., Ltd.]

[0103] Column: Guard Column; TSK Guardcolumn SuperHZ-L+ Column; TSKgel SuperHZM-N+TSKgel SuperHZM-M+TSKgel SuperH-RC (All manufactured by Toso Co., Ltd., product names)

[0104] Column Size: 4.6×20㎜ (Guard Column), 4.6×150㎜ (Column), 6.0×150㎜ (Reference Column)

[0105] Eluent: Tetrahydrofuran

[0106] Sample concentration: 10 mg / 5 mL

[0107] Injection volume: 25μL

[0108] Flow rate: 1.00 mL / min

[0109] Measured temperature: 40℃

[0110] The calibration curve is approximated as a cubic equation using standard polystyrene: TSK standard POLYSTYRENE (Type; A-2500, A-5000, F-1, F-2, F-4, F-10, F-20, F-40) (manufactured by Toso Co., Ltd., product name).

[0111] If the resin composition includes a maleimide resin other than a maleimide resin containing a ring as a curable resin, the type thereof is not particularly limited.

[0112] Specific examples of maleimide resins other than maleimide resins containing a monocyclic ring include N,N'-ethylenebismaleimide, N,N'-hexamethylenebismaleimide, N,N'-(1,3-phenylene)bismaleimide, N,N'-[1,3-(2-methylphenylene)]bismaleimide, N,N'-[1,3-(4-methylphenylene)]bismaleimide, N,N'-(1,4-phenylene)bismaleimide, bis(4-maleimidephenyl)methane, bis(3-methyl-4-maleimidephenyl)methane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide, bis(4-maleimidephenyl)ether, bis(4-maleimidephenyl)sulfone, bis(4-maleimidephenyl)sulfide, Bis(4-maleimidephenyl)ketone, bis(4-maleimidecyclohexyl)methane, 1,4-bis(4-maleimidephenyl)cyclohexane, 1,4-bis(maleimidemethyl)cyclohexane, 1,4-bis(maleimidemethyl)benzene, 1,3-bis(4-maleimidephenoxy)benzene, 1,3-bis(3-maleimidephenoxy)benzene, bis[4-(3-maleimidephenoxy)phenyl]methane, bis[4-(4-maleimidephenoxy)phenyl]methane, 1,1-bis[4-(3-maleimidephenoxy)phenyl]ethane, 1,1-bis[4-(4-maleimidephenoxy)phenyl]ethane, 1,2-bis[4-(3-maleimidephenoxy)phenyl]ethane, 1,2-Bis[4-(4-maleimidephenoxy)phenyl]ethane, 2,2-Bis[4-(3-maleimidephenoxy)phenyl]propane, 2,2-Bis[4-(4-maleimidephenoxy)phenyl]propane, 2,2-Bis[4-(3-maleimidephenoxy)phenyl]butane, 2,2-Bis[4-(4-maleimidephenoxy)phenyl]butane, 2,2-Bis[4-(3-maleimidephenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-Bis[4-(4-maleimidephenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 4,4-Bis(3-maleimidephenoxy)biphenyl, 4,4-Bis(4-maleimidephenoxy)biphenyl, bis[4-(3-maleimidephenoxy)phenyl]ketone, bis[4-(4-maleimidephenoxy)phenyl]ketone, bis(4-maleimidephenyl)disulfide, bis[4-(3-maleimidephenoxy)phenyl]sulfide, bis[4-(4-maleimidephenoxy)phenyl]sulfide,Bis[4-(3-maleimidephenoxy)phenyl]sulfoxide, Bis[4-(4-maleimidephenoxy)phenyl]sulfoxide, Bis[4-(3-maleimidephenoxy)phenyl]sulfone, Bis[4-(4-maleimidephenoxy)phenyl]sulfone, Bis[4-(3-maleimidephenoxy)phenyl]ether, Bis[4-(4-maleimidephenoxy)phenyl]ether, 1,4-Bis[4-(4-maleimidephenoxy)-α,α-dimethylbenzyl]benzene, 1,3-Bis[4-(4-maleimidephenoxy)-α,α-dimethylbenzyl]benzene, 1,4-Bis[4-(3-maleimidephenoxy)-α,α-dimethylbenzyl]benzene, Examples include 1,3-bis[4-(3-maleimidephenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(4-maleimidephenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-maleimidephenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(3-maleimidephenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(3-maleimidephenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, polyphenylmethanemaleimide, biphenylalalkyl maleimide, etc.

[0113] The resin composition may include an aminomaleimide resin having a structural unit derived from a maleimide resin and a structural unit derived from a diamine compound as the maleimide resin.

[0114] When the resin composition includes maleimide resin as a curable resin, the proportion of maleimide resin in the total curable resin is not particularly limited. The proportion of maleimide resin in the total curable resin may be, for example, 40 volume% or more, 45 volume% or more, or 50 volume% or more. The proportion of maleimide resin in the total curable resin may be, for example, 75 volume% or less, 70 volume% or less, or 65 volume% or less.

[0115] The resin composition may include a compound having a (meth)acryloyl group as a curable resin. From the perspective of balancing the properties of the resin film, it is preferable that the resin composition include, respectively, a compound having an N-substituted maleimide group and a compound having a (meth)acryloyl group as a curable resin.

[0116] The resin composition may include only one compound having a (meth)acryloyl group or two or more.

[0117] Examples of compounds having a (meth)acryloyl group include (meth)acrylic acid esters, such as di(meth)acrylic acid esters and (meth)acrylic acid esters with three or more functional groups.

[0118] As di(meth)acrylic acid esters, 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 Examples include bisphenol A di(meth)acrylate, ethoxylated bisphenol F di(meth)acrylate, and dioxane glycol di(meth)acrylate.

[0119] Examples of dioxane glycol di(meth)acrylates include acrylic acid 2-[5-ethyl-5-[(acryloyloxy)methyl]-1,3-dioxane-2-yl]-2,2-dimethylethyl.

[0120] Examples of (meth)acrylic acid esters with three or more functions include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc.

[0121] From the perspective of balancing the properties of the resin film, it is preferable for the resin composition to include a di(meth)acrylic acid ester, more preferable for a di(meth)acrylic acid ester containing an alkylene group, and even more preferable for a di(meth)acrylic acid ester in which (meth)acryloyl groups are bonded to both ends of the alkylene group.

[0122] As for the di(meth)acrylic acid ester containing an alkylene group, the diacrylic acid ester represented by the following general formula (B-1) and the dimethacrylic acid ester represented by the following general formula (B-2) are preferred, and the dimethacrylic acid ester represented by the following general formula (B-2) is more preferred.

[0123]

[0124] During the meal, R b1 It is an alkylene group having 1 to 20 carbon atoms.

[0125] R in the above general formulas (B-1) and (B-2) b1 The number of carbon atoms in the alkylene group having 1 to 20 carbon atoms shown here is preferably 4 to 18, more preferably 6 to 15, and even more preferably 8 to 12.

[0126] Examples of alkylene groups having 1 to 20 carbon atoms include methylene groups, ethylene groups, propylene groups, butylene groups, pentylene groups, hexylene groups, heptylene groups, octylene groups, nonylene groups, decylene groups, undecylene groups, dodecylene groups, tetradecylene groups, pentadecylene groups, etc. The alkylene groups may be straight-chain, branched-chain, or cyclic, but are preferably straight-chain.

[0127] The resin composition may include a compound having a vinyl group as a curable resin. From the perspective of balancing the properties of the resin film, it is preferable that the resin composition include, respectively, a compound having an N-substituted maleimide group and a compound having a vinyl group as curable resins.

[0128] The resin composition may include only one type of compound having a vinyl group or two or more types.

[0129] Examples of compounds having vinyl groups include conjugated diene polymers.

[0130] In the present disclosure, "conjugated diene polymer" means a polymer of a conjugated diene compound.

[0131] Examples of conjugated diene compounds include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, etc.

[0132] The conjugated diene polymer may be a homopolymer of one type of conjugated diene compound, or a copolymer of two or more types of conjugated diene compounds.

[0133] The conjugated diene polymer may be a copolymer of one or more conjugated diene compounds and one or more monomers other than conjugated diene compounds.

[0134] When the conjugated diene polymer is a copolymer, the polymerization mode is not particularly limited and may be random polymerization, block polymerization, or graft polymerization.

[0135] In terms of compatibility with other resins included in the resin composition and dielectric properties, as a conjugated diene polymer, a conjugated diene polymer having a plurality of vinyl groups in a side chain is preferred, and a conjugated diene polymer having a plurality of 1,2-vinyl groups in a side chain is more preferred.

[0136] The number of vinyl groups in one molecule of the conjugated diene polymer is not particularly limited, but from the perspective of compatibility with other resins and dielectric properties, it is preferably 3 or more, more preferably 5 or more, and even more preferably 10 or more.

[0137] The upper limit of the number of vinyl groups in one molecule of a conjugated diene polymer is not specifically limited, but may be 100 or fewer, 80 or fewer, or 60 or fewer.

[0138] Examples of conjugated diene polymers include polybutadiene having 1,2-vinyl groups, butadiene-styrene copolymer having 1,2-vinyl groups, and polyisoprene having 1,2-vinyl groups. Among these, polybutadiene having 1,2-vinyl groups and butadiene-styrene copolymer having 1,2-vinyl groups are preferred from the viewpoint of dielectric properties and heat resistance, and polybutadiene having 1,2-vinyl groups is more preferred. As for polybutadiene having 1,2-vinyl groups, polybutadiene homopolymer having 1,2-vinyl groups is preferred.

[0139] When the conjugated diene polymer is a polybutadiene having 1,2-vinyl groups, the content of structural units having 1,2-vinyl groups [hereinafter referred to as "vinyl group content"] with respect to the total butadiene-derived structural units constituting the polybutadiene is not particularly limited. From the perspective of compatibility with other resins included in the resin composition, dielectric properties, and heat resistance, the vinyl group content is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 85 mol% or more. In addition, there is no particular limit on the upper limit of the vinyl group content, and it may be 100 mol% or less, 95 mol% or less, or 90 mol% or less.

[0140] The number average molecular weight of the conjugated diene polymer is not particularly limited. In terms of compatibility with other resins, dielectric properties, and heat resistance, it is preferably 1,000 to 3,000, more preferably 1,100 to 2,000, and even more preferably 1,150 to 1,500.

[0141] (Weapon filler)

[0142] The resin composition includes an inorganic filler.

[0143] As the resin composition contains inorganic fillers, the thermal expansion rate of the cured product tends to be reduced, and heat resistance and flame retardancy are improved.

[0144] The inorganic filler included in the resin composition may be of only one type or two or more types.

[0145] Examples of inorganic fillers include silica, alumina, titanium oxide, beryllia, barium titaniumate, potassium titaniumate, strontium titaniumate, calcium titaniumate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, aluminum borate, silicon carbide, etc. Among these, silica and alumina are preferred from the perspective of low thermal expansion, heat resistance, and flame retardancy.

[0146] The average particle size of the inorganic filler is not particularly limited, but is preferably 0.01 μm to 20 μm, more preferably 0.1 μm to 10 μm, and even more preferably 0.5 μm to 5 μm in terms of dispersibility in the resin composition and suitability for fine wiring.

[0147] In the present disclosure, the average particle size of the inorganic filler refers to the particle size (volume average particle size, D50) at which the volume accumulation in the volume-based particle size distribution curve reaches 50%. The volume-based particle size distribution curve is obtained, for example, by laser diffraction scattering.

[0148] The shape of the inorganic filler is not particularly limited, but it is preferable that it be spherical.

[0149] Inorganic fillers may be surface-treated with a coupling agent to improve dispersibility and adhesion to organic components. Examples of coupling agents include silane coupling agents and titanate coupling agents. Among these, silane coupling agents are preferred. Examples of silane coupling agents include aminosilane coupling agents, vinylsilane coupling agents, and epoxysilane coupling agents.

[0150] (Elastomer)

[0151] The resin composition may include an elastomer.

[0152] In the present disclosure, "elastomer" means a compound having a glass transition temperature of 25°C or lower as measured by differential scanning calorimetry according to JIS K 6240:2011, and having either a number average molecular weight or a weight average molecular weight of 10,000 or more.

[0153] The number average molecular weight or weight average molecular weight of the elastomer can be selected in the range of, for example, 10,000 to 500,000.

[0154] The elastomer included in the resin composition may be one type or two or more types.

[0155] The elastomer included in the resin composition may have properties as a curable resin (i.e., having reactive groups) or may not have properties as a curable resin (i.e., not having reactive groups).

[0156] Examples of elastomers include polystyrene-based elastomers, polyolefin-based elastomers, polyurethane-based elastomers, polyphenylene ether-based elastomers, polyester-based elastomers, polyamide-based elastomers, and polyacrylic-based elastomers.

[0157] From the perspective of the dielectric properties of the cured product, it is preferable that the resin composition include a polystyrene-based elastomer. Examples of polystyrene-based elastomers include those having structural units derived from styrene compounds represented by the following general formula (D3-1).

[0158]

[0159] During the meal, R d1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R d2 is an alkyl group having 1 to 5 carbon atoms. d1 is an integer from 0 to 5.)

[0160] R in the food d1 and R d2 Examples of alkyl groups having 1 to 5 carbon atoms represented by α-1 include methyl groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, t-butyl groups, n-pentyl groups, etc. The alkyl groups having 1 to 5 carbon atoms may be either straight-chain or branched-chain. Among these, alkyl groups having 1 to 3 carbon atoms are preferred, alkyl groups having 1 or 2 carbon atoms are more preferred, and methyl groups are even more preferred.

[0161] n in the formula d1 Silver is an integer from 0 to 5, preferably an integer from 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0162] Polystyrene-based elastomers may contain structural units other than structural units derived from styrene compounds.

[0163] Structural units other than those derived from styrene compounds that can be contained in polystyrene-based elastomers include structural units derived from butadiene, structural units derived from isoprene, structural units derived from maleic acid, structural units derived from maleic anhydride, etc.

[0164] The above butadiene-derived structural unit and the above isoprene-derived structural unit may be hydrogenated. When hydrogenated, the butadiene-derived structural unit becomes a structural unit mixed with an ethylene unit and a butylene unit, and the isoprene-derived structural unit becomes a structural unit mixed with an ethylene unit and a propylene unit.

[0165] Specifically, examples of polystyrene-based elastomers include hydrogenated styrene-butadiene-styrene block copolymers, hydrogenated styrene-isoprene-styrene block copolymers, and styrene-maleic anhydride copolymers.

[0166] Examples of hydrogenation agents for styrene-butadiene-styrene block copolymers include SEBS, which is formed by completely hydrogenating carbon-carbon double bonds in the butadiene block, and SBBS, which is formed by partially hydrogenating carbon-carbon double bonds at 1,2-bond sites in the butadiene block. Furthermore, in SEBS, complete hydrogenation is typically 90% or more of the total carbon-carbon double bonds, but may be 95% or more, 99% or more, or 100%. In addition, the partial hydrogenation rate in SBBS is, for example, 60% to 85% of the total carbon-carbon double bonds. That is, SBBS contains carbon-carbon double bonds as reactive groups within the molecular chain.

[0167] Examples of hydrogenated styrene-isoprene-styrene block copolymers include SEPS formed by hydrogenating the polyisoprene portion.

[0168] The number average molecular weight of the elastomer 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.

[0169] The weight average molecular weight of the elastomer 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.

[0170] (Curing accelerator)

[0171] The resin composition may include a curing accelerator. By including a curing accelerator, the curability of the resin composition is improved, and the dielectric properties and heat resistance of the cured product tend to be improved.

[0172] The type of curing accelerator is not particularly limited and can be selected depending on the type of curable resin included in the resin composition, etc.

[0173] As curing accelerators, 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 mascumidazole compounds such as the addition reaction product of hexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole; tertiary amine compounds; quaternary ammonium compounds; phosphorus-based compounds such as triphenylphosphine; and organic peroxides such as dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexine-3, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butylperoxyisopropyl monocarbonate, and 1,3-di(t-butylperoxyisopropyl)benzene; Examples include inorganic peroxides such as potassium persulfate, sodium persulfate, and ammonium persulfate; azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2'-dimethylvaleronitrile); and carboxylates of manganese, cobalt, and zinc.

[0174] When the resin composition includes a curable resin capable of radical polymerization, it is preferable to include a radical polymerization initiator as a curing accelerator. Examples of radical polymerization initiators include organic peroxides, inorganic peroxides, azo compounds, etc., among the curing accelerators mentioned above. From the perspective of improving curability, organic peroxides are preferred.

[0175] The curing accelerator included in the resin composition may be one type or two or more types.

[0176] When the resin composition contains a curing accelerator, the content 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 with respect to the total amount of resin components (100 parts by mass).

[0177] If the content of the curing accelerator is 0.1 parts by mass or more, a sufficient curing accelerating effect tends to be obtained. If the content of the curing accelerator is 15 parts by mass or less, the storage stability of the resin composition tends to be better.

[0178] When the resin composition includes a radical polymerization initiator as a curing accelerator, the content is not particularly limited, but is preferably 0.05 to 7 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 2 to 4 parts by mass with respect to the total amount of resin components (100 parts by mass).

[0179] If the content of the radical polymerization initiator is above the above lower limit, it tends to be easier to obtain a sufficient curing acceleration effect. In addition, if the content of the radical polymerization initiator is below the above upper limit, storage stability tends to be better.

[0180] (Other ingredients)

[0181] The resin composition may include components other than the above components (other components) as needed. Examples of other components include flame retardants, antioxidants, heat stabilizers, antistatic agents, UV absorbers, colorants, lubricants, etc.

[0182] Other components included in the resin composition may be one type or two or more types.

[0183] (Content of major ingredients)

[0184] The content of the main components included in the resin composition (curable resin, inorganic filler, and elastomer included as needed) is not particularly limited and can be selected according to the application of the resin film, desired characteristics, etc.

[0185] From the perspective of imparting sufficient curability to the resin film, it is preferable that the content of the curable resin included in the resin composition be 10 volume% or more, more preferable that it be 15 volume% or more, and even more preferable that it be 20 volume% or more.

[0186] From the perspective of balance with other components, the content of the curable resin included in the resin composition is preferably 45 volume% or less, more preferably 33 volume% or less, and even more preferably 30 volume% or less.

[0187] When the resin composition includes an elastomer, the content of the elastomer can be selected in the range of, for example, 1 volume% to 30 volume%.

[0188] In order to lower the melt viscosity of the resin film before curing, the elastomer content may be 0 volume% or 10 volume% or less.

[0189] The content of the resin component included in the resin composition is not particularly limited if it is less than 50 volume. The content of the resin component can be selected, for example, in the range of 30 volume% to 45 volume%.

[0190] From the perspective of lowering the melt viscosity of the resin film before curing, it is desirable for the resin composition to include a curable resin with a small molecular weight.

[0191] Specifically, for example, it is preferable that the proportion of the curable resin having a molecular weight of 2000 or less in the total curable resin be 70 volume% or more, 80 volume% or more, or 90 volume% or more. The proportion of the curable resin having a molecular weight of 2000 or less in the total curable resin may be 100 volume%.

[0192] The content of inorganic filler included in the resin composition is not particularly limited as long as it exceeds 50 volume%. From the perspective of keeping the coefficient of thermal expansion after curing low, it is preferable that the content of inorganic filler be 52 volume% or more, and more preferable that it be 55 volume% or more.

[0193] From the perspective of balance with other characteristics of the resin film, it is preferable that the content of the inorganic filler in the resin film be 70 volume% or less, and more preferable that it be 65 volume% or less.

[0194] The content of each component described above is based on the solid content included in the resin composition.

[0195] In the present disclosure, the term "resin component" refers to a component corresponding to an organic material among the solid components included in the resin composition.

[0196] (Various characteristics of resin films)

[0197] The thickness of the resin film is not particularly limited and can be selected according to the application of the resin film, etc. The thickness of the resin film may be, for example, 10㎛ or more, 50㎛ or more, 80㎛ or more, or 100㎛ or more.

[0198] The thickness of the resin film may be, for example, 1,000 μm or less, 700 μm or less, or 500 μm or less.

[0199] From the perspective of handling the resin film, it is preferable that the resin film be placed on a support.

[0200] The material of the support is not particularly limited and may include resin, metal, paper, etc. If necessary, a release treatment may be performed on the surface of the support that contacts the resin film.

[0201] The thickness of the support is not particularly limited, but from the perspective of handling and economy, it is preferably 10㎛ to 150㎛, more preferably 20㎛ to 100㎛, and even more preferably 25㎛ to 50㎛.

[0202] A resin film disposed on a support can be produced by, for example, applying a resin varnish obtained by adding an organic solvent to a resin composition onto the support and drying to remove the organic solvent.

[0203] The content of the organic solvent in the resin film after drying is preferably 2 mass% or less, more preferably 1 mass% or less, even more preferably 0.5 mass% or less, with respect to the total amount (100 mass%) of the resin film, and may be 0 mass%.

[0204] If the content of the organic solvent in the resin film is within the above range, the amount of volatilization of the organic solvent during heat curing is sufficiently suppressed.

[0205] The resin film may be in a state where at least a portion of the curable component contained in the resin film has reacted.

[0206] The resin film may have a protective film disposed on its surface. For example, the resin film may have a support disposed on one side and a protective film disposed on the other side.

[0207] The material of the protective film is not particularly limited and may include resin, metal, paper, etc. If necessary, a release treatment may be performed on the surface of the protective film that contacts the resin film.

[0208] The thickness of the protective film is not particularly limited, but from the perspective of handling and economy, it is preferably 10㎛ to 150㎛, more preferably 20㎛ to 100㎛, and even more preferably 25㎛ to 50㎛.

[0209] The uses of the resin film of the present disclosure are not particularly limited. Examples of preferred uses include forming an insulating layer of a printed circuit board and sealing a semiconductor device included in a semiconductor package. Since the resin film of the present disclosure has excellent deformability before heating, it can be suitably used for applications involving, for example, filling a depression formed in a substrate.

[0210] Since the resin film of the present disclosure has excellent deformability before heating, it is suitable for applications involving the filling of concave portions with a large aspect ratio. For example, it is suitable for applications involving the filling of concave portions with an aspect ratio of 5 or more. The aspect ratio of the concave portion is a value calculated by dividing the depth of the concave portion by the width or diameter of the concave portion.

[0211] Printed Wiring Board

[0212] The printed circuit board of the present disclosure comprises a cured product of the resin film described above. The cured product of the resin film may be, for example, an insulating layer disposed on a substrate included in the printed circuit board. The printed circuit board may be a multilayer printed circuit board.

[0213] Hereinafter, an example of a method for manufacturing a printed circuit board using the resin film of the present disclosure will be described.

[0214] First, a resin film is placed on a substrate. The placement of the resin film may be performed while applying pressure and heating. The resin film may be placed on only one side of the substrate or on both sides.

[0215] As a substrate for a printed circuit board, a conductive layer formed as a circuit on the surface (circuit board) can be used. The substrate can be selected without particular limitation from known substrates such as glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates.

[0216] Next, the resin film placed on the substrate is cured to form an insulating layer. The curing conditions are set considering the components contained in the resin film, etc.

[0217] The insulating layer formed by curing the resin film may be subjected to perforation, shaping, polishing, etc., as necessary.

[0218] A conductive layer may be further disposed on an insulating layer formed by curing a resin film. The placement of the conductive layer can be performed by known methods such as plating.

[0219] Semiconductor Package

[0220] The semiconductor package of the present disclosure comprises a cured product of the resin film described above. The cured product of the resin film may also be a sealing agent disposed around, for example, an electronic component disposed on a substrate.

[0221] Hereinafter, an example of a method for manufacturing a semiconductor package using the resin film of the present disclosure is described. First, the resin film is placed on an electronic component, such as a semiconductor chip, disposed on a substrate. Next, the resin film is heated and pressed as needed to embed the electronic component in the resin film. Subsequently, by curing the resin film with the embedded electronic component, a semiconductor package can be manufactured in which the area around the electronic component is sealed by the cured resin film.

[0222] Examples

[0223] The present embodiment will be described in detail below with reference to examples. However, the present embodiment is not limited to the following examples.

[0224] (Production of resin film)

[0225] A resin varnish with a solid content of about 50 mass% was prepared by mixing the components shown in Table 1 with a solvent (toluene). Unless otherwise noted, the unit of the mixing amount of the components listed in Table 1 is "volume%".

[0226] Next, a resin varnish was applied to one side of a PET film to form a resin varnish layer. Then, by heating and drying at 105°C for 5 minutes, the solvent contained in the resin varnish layer was evaporated, thereby obtaining a resin composition layer with a PET film disposed on one side.

[0227] Next, a resin composition layer with a PET film disposed on one side was overlapped with a resin composition layer with a PET film disposed on the other side. In this state, the resin composition layers were bonded using a vacuum laminator at a temperature of 100°C and a pressurization time of 5 seconds to obtain a resin film with PET films disposed on both sides.

[0228] (Curing treatment of resin film)

[0229] The PET film of the resin film obtained above was peeled off. Next, a low-profile copper foil with a thickness of 12 μm (manufactured by Mitsui Kinzoku Kogyo Co., Ltd., product name "3EC-VLP-12") was placed on both sides of the resin film with the S side facing the resin film. In this state, the low-profile copper foil and the resin film were bonded using a vacuum laminator to obtain a laminate. The bonding conditions were set to a temperature of 100°C, a vacuum time of 30 seconds, a pressurization time of 20 seconds, and a pressure of 0.1 MPa. A curing treatment was performed on this laminate by heating at a temperature of 180°C for 1 hour to obtain a cured resin film (thickness: 120 μm).

[0230] (Measurement of the coefficient of thermal expansion)

[0231] A test specimen with a width of 0.4 mm, a length of 20 mm, and a thickness of 0.12 mm was prepared from the cured resin film obtained by performing a curing treatment.

[0232] For this test specimen, the coefficient of thermal expansion was measured by thermomechanical analysis (TMA). The measurement was performed using the SS6100 manufactured by Seiko Instruments under tensile mode, a temperature range of 30°C to 300°C, a heating rate of 5°C / min, and a load of 4g. Both ends of the test specimen in the long direction were gripped with grippers, and the spacing between the grippers was set to 10 mm. The average value of the change in length per unit temperature from 30°C to 150°C was defined as the coefficient of linear expansion (CTE, ppm / K). The results are shown in Table 1.

[0233] (Measurement of melt viscosity)

[0234] Test specimens measuring 30 mm × 30 mm were prepared from a resin film prior to curing treatment. The shear viscosity of the specimens was measured using a rheometer (TA Instruments DHR-20, parallel plate diameter: 20 mm) under conditions of a temperature range of 30°C to 300°C, a heating rate of 5°C / min, and a load of 1 g. The lowest measured shear viscosity was taken as the lowest melt viscosity (Pa·s). The results are shown in Table 1.

[0235] (Assessment of landfill suitability)

[0236] The embedment ability of the resin film before curing treatment was evaluated by the following test.

[0237] One side of the evaluation substrate was formed by cutting a grid pattern containing 10 vertical and 5 horizontal grooves. The depth of the grooves was 1 mm, the width was 0.1 mm, and the spacing between adjacent grooves was 7 mm.

[0238] A resin film, prior to curing treatment, was attached to the surface of the evaluation substrate where the grid pattern was formed using a vacuum laminator. In this state, vacuuming was performed for 30 seconds, and embedding treatment into the grooves of the resin film was performed under conditions of 0.1 MPa and 100°C.

[0239] The surface of the substrate after the burial treatment was visually inspected, and the number of voids observed in a 30 mm × 30 mm area was counted. The results are shown in Table 1.

[0240] In addition, the surface roughness of the substrate after the burial treatment was measured. A laser microscope was used for the measurement, and the measurement area was set to 20 mm × 10 mm. The results are shown in Table 1.

[0241]

[0242] The details of the components listed in Table 1 are as follows.

[0243] Curable resin 1: Aromatic bismaleimide resin containing a monocyclic group represented by the general formula (A1-4-1), number average molecular weight: 1,300, solid phase at 25°C

[0244] Curable Resin 2: Polybutadiene homopolymer having 1,2-vinyl groups, vinyl group content: 85% or more, number average molecular weight: 1,200, liquid phase at 25°C

[0245] Curable Resin 3: Nonanediol dimethacrylate, molecular weight: 296.4, liquid phase at 25°C

[0246] Elastomer: SEBS

[0247] Inorganic filler 1: Silica particles with a volume average particle size of 2.4 µm

[0248] Inorganic Filler 2: Silica particles with a volume average particle size of 1.0 µm

[0249] Coupling agent: 3-Methacryloxypropyltrimethoxysilane

[0250] Curing Accelerator 1: 1,3-Di(t-butylperoxyisopropyl)benzene

[0251] Curing Accelerator 2: Imidazole-based Curing Accelerator

[0252] As shown in Table 1, the resin films of Examples 1 and 2, which have an inorganic filler content of more than 50 volume% and a minimum melt viscosity of 2000 Pa·s or less, have fewer voids observed after landfill treatment and smaller surface roughness values ​​compared to the resin films of Comparative Examples 1 and 2, which have a minimum melt viscosity greater than 2000 Pa·s. In addition, the resin films of Examples 1 and 2 have a smaller CTE after curing compared to the resin film of Comparative Example 3, which has an inorganic filler content of 50 volume%.

[0253] From the above results, it was found that a resin film having an inorganic filler content of more than 50 volume% and a minimum melt viscosity of 2000 Pa·s or less has excellent deformability before curing and also has a low coefficient of thermal expansion after curing.

[0254] The disclosure of Japanese Patent Application No. 2024-013690 is incorporated herein by reference in its entirety.

[0255] All documents, patent applications, and technical specifications described in this specification are incorporated by reference into this specification to the same extent as when individual documents, patent applications, and technical specifications are specifically and individually described by reference.

Claims

Claim 1 A resin film comprising a resin composition including a curable resin and an inorganic filler, wherein the content of the inorganic filler is greater than 50 volume% and the minimum melt viscosity is 2000 Pa·s or less. Claim 2 In claim 1, the resin film comprises a curable resin having radical polymerization properties. Claim 3 In claim 1, the resin film comprises a curable resin having a molecular weight of 2000 or less. Claim 4 A resin film according to claim 1, wherein the content of the inorganic filler is 70 volume% or less. Claim 5 A resin film for use as a sealing material for a semiconductor package, in any one of paragraphs 1 to 4. Claim 6 A resin film for forming an insulating layer of a printed circuit board, in any one of claims 1 to 4. Claim 7 A printed circuit board comprising a cured resin film described in any one of claims 1 to 4. Claim 8 A semiconductor package comprising a cured resin film described in any one of claims 1 to 4.

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