Resin composition, dry film, and cured product

Abstract

Provided is a resin composition having excellent low-temperature embeddability and thermal characteristics. Also provided are a dry film and a cured product obtained by using the resin composition. One form of the present invention is a resin composition. The resin composition contains a (A) branched polyphenylene ether, a (B) crosslinking agent, a (C) surface-modified silica filler, and a (D) radical polymerization initiator. The (C) surface-modified silica filler includes a silica filler and a coating, and the coating covers at least a part of the surface of the silica filler and contains a siloxane structure containing a styrenic double bond.

Description

Resin composition, dry film, and cured product

[0001] This invention relates to resin compositions, dry films, and cured products.

[0002] In recent years, the frequency of signals from electronic devices has been increasing due to the widespread adoption of high-capacity, high-speed communication technologies such as 5G and millimeter-wave radar for automotive ADAS (Advanced Driver-Assistance Systems).

[0003] Printed circuit boards embedded in such electronic devices have traditionally used curable resin compositions, primarily composed of epoxy resin, as interlayer insulators. However, cured products made from such compositions have high dielectric constants (Dk) and dielectric loss tangents (Df), leading to increased transmission loss for high-frequency signals and problems such as signal attenuation and heat generation. For this reason, polyphenylene ether, which exhibits excellent low dielectric properties, has attracted attention.

[0004] For example, Patent Document 1 discloses a thermosetting resin composition that can suppress resin residue while obtaining a low dielectric loss tangent by containing a predetermined amount of polyphenylene ether, a predetermined resin component, and a filler such as silica filler.

[0005] Japanese Patent Publication No. 2017-206578

[0006] When fillers such as silica fillers are added to resin compositions related to conventional technology, a reduction in the coefficient of thermal expansion can be expected. However, in resin compositions containing polyphenylene ether, the addition of silica fillers sometimes resulted in a deterioration of the embedding properties of circuit boards at low temperatures.

[0007] Therefore, the object of the present invention is to provide a resin composition that is excellent in embedding properties and thermal properties at low temperatures, and a dry film and cured product obtained using the resin composition.

[0008] One aspect of the present invention is a resin composition. The resin composition comprises (A) a branched polyphenylene ether, (B) a crosslinking agent, (C) a surface-modified silica filler, and (D) a radical polymerization initiator. The (C) surface-modified silica filler comprises a silica filler and a coating, the coating covering at least a portion of the surface of the silica filler and containing a siloxane structure including a styrene double bond.

[0009] Another aspect of the present invention is a dry film comprising a resin layer formed by the resin composition.

[0010] Yet another aspect of the present invention is a cured product obtained using the resin composition or the resin layer of the dry film.

[0011] The present invention provides a resin composition that exhibits excellent embedding properties and thermal characteristics at low temperatures, and a dry film and cured product obtained using the resin composition.

[0012] If isomers exist for the compounds described herein, all possible isomers are usable in the present invention unless otherwise specified.

[0013] In this specification, phenols used as raw materials for polyphenylene ether (PPE) and that can become constituent units of polyphenylene ether are collectively referred to as "raw material phenols."

[0014] In this specification, when describing raw material phenols, expressions such as "ortho position" or "para position" refer to the position of the phenolic hydroxyl group (ipso position) unless otherwise specified.

[0015] In this specification, when the term "ortho position" is used, it refers to "at least one of the ortho positions." Therefore, unless there is a particular contradiction, when the term "ortho position" is used, it may be interpreted as referring to either one of the ortho positions, or to both of the ortho positions.

[0016] In this specification, polyphenylene ethers in which some or all of the functional groups (e.g., hydroxyl groups) of polyphenylene ether have been modified may be simply referred to as "polyphenylene ether." Therefore, when the term "polyphenylene ether" is used, it includes both unmodified and modified polyphenylene ethers, unless otherwise specified.

[0017] In this specification, mainly monovalent phenols are disclosed as raw material phenols, but polyvalent phenols may also be used as raw material phenols as long as they do not hinder the effects of the present invention.

[0018] Where the upper and lower limits of a numerical range are described separately in this specification, all combinations of each lower limit and each upper limit shall be substantially described to the extent that they are not inconsistent.

[0019] In this specification, the term "solids" is used to mean non-volatile components (components other than volatile components such as solvents).

[0020] In this specification, components contained in a resin composition and components contained in the resin layer, which is the dried coating film of the resin composition, may not be distinguished in the description.

[0021] The weight-average molecular weight (and number-average molecular weight) can be measured using known measurement methods, such as gel permeation chromatography (GPC) as the molecular weight in terms of polystyrene.

[0022] The following describes the resin compositions relating to this disclosure, followed by a description of the dry films and cured products obtained using the resin compositions relating to this disclosure.

[0023] <<<Resin Composition>>> The resin composition according to this disclosure comprises (A) a branched polyphenylene ether, (B) a crosslinking agent, (C) a surface-modified silica filler, and (D) a radical polymerization initiator. The resin composition according to this disclosure may also contain other components as needed. Each component is described in detail below.

[0024] <<(A) Branched polyphenylene ether>> The branched polyphenylene ether is obtained from raw material phenols containing at least phenols satisfying the following conditions. (Condition) It has hydrogen atoms at the ortho and para positions.

[0025] Since the phenols satisfying the above conditions have hydrogen atoms at the ortho position, when they are oxidative polymerized with phenols, ether bonds can be formed not only at the ipso and para positions but also at the ortho position. Therefore, the polyphenylene ether obtained using such phenols as raw material phenols can form a branched-chain structure. That is, the branched polyphenylene ether has a part of its structure branched by a benzene ring in which at least three positions, namely the ipso, ortho, and para positions, are ether-bonded.

[0026] The branched polyphenylene ether may be a mixture of two or more types of branched polyphenylene ethers synthesized using different raw material phenols. Also, the raw material phenols may contain other phenols that do not satisfy the above conditions.

[0027] The branched polyphenylene ether preferably contains a functional group having an unsaturated carbon bond. The unsaturated carbon bond refers to an ethylenic or acetylenic carbon-carbon multiple bond (double bond or triple bond). The functional group having an unsaturated carbon bond is not particularly limited, and an alkenyl group (e.g., vinyl group, allyl group), an alkynyl group (e.g., ethynyl group), or a (meth)acryloyl group is preferably used. From the viewpoint of excellent curability, a vinyl group, an allyl group, or a (meth)acryloyl group is more preferable, and from the viewpoint of excellent low dielectric characteristics, an allyl group is even more preferable. Note that the carbon number of these functional groups having an unsaturated carbon bond can be, for example, 15 or less, 10 or less, 8 or less, 5 or less, 3 or less, etc. The equivalent weight of the functional group having an unsaturated carbon bond can be appropriately changed according to the curability and use of the resin composition, etc.

[0028] Branched polyphenylene ether containing a functional group having an unsaturated carbon bond can be produced, for example, by (Method 1) a method of synthesizing polyphenylene ether using phenols containing a functional group having an unsaturated carbon bond as raw material phenols, or (Method 2) a method of synthesizing polyphenylene ether using phenols not containing a functional group having an unsaturated carbon bond as raw material phenols and modifying the obtained polyphenylene ether to introduce a functional group having an unsaturated carbon bond into the polyphenylene ether.

[0029] Examples of the branched polyphenylene ether include the polyphenylene ether disclosed in International Publication No. 2020 / 017570.

[0030] The weight average molecular weight (Mw) of the branched polyphenylene ether is preferably 1,000 or more, 1,500 or more, 2,000 or more, etc., and preferably 150,000 or less, 100,000 or less, 80,000 or less, etc.

[0031] The branched polyphenylene ether preferably has a polydispersity index {PDI: weight average molecular weight (Mw) / number average molecular weight (Mn)} of 1.5 to 20.

[0032] The content of the branched polyphenylene ether in the resin composition is preferably 10% by mass or more, 20% by mass or more, or 30% by mass or more, and preferably 90% by mass or less, 80% by mass or less, or 70% by mass or less, based on the total solid content excluding the filler.

[0033] <<(B) Crosslinking agent>> As the crosslinking agent, conventionally known ones can be used. Examples of the crosslinking agent include vinyl benzyl ether-based compounds synthesized by the reaction of phenol and vinyl benzyl chloride; allyl ether-based compounds synthesized by the reaction of phenol and allyl chloride; trialkenyl isocyanurate; diallyl phthalate synthesized by the reaction of phthalic acid and allyl alcohol; etc. The crosslinking agent may be used alone or in combination of two or more.

[0034] The crosslinking agent is preferably trialkenyl isocyanurate or diallyl phthalate, and more preferably triallyl isocyanurate (hereinafter referred to as TAIC®) or triallyl cyanurate (hereinafter referred to as TAC).

[0035] The crosslinking agent content in the resin composition is preferably 5% by mass or more, 10% by mass or more, or 15% by mass or more, based on the total solid content of the resin composition excluding fillers, and is also preferably 50% by mass or less, 40% by mass or less, or 30% by mass or less.

[0036] <<(C) Surface-Modified Silica Filler>> A surface-modified silica filler comprises a silica filler and a coating that covers at least a portion of the surface of the silica filler. The coating contains a siloxane structure (a network of siloxane bonds) that includes styrene double bonds. In other words, a surface-modified silica filler is a silica filler that has been surface-treated with a silane coupling agent having styrene double bonds at its ends. In this case, functional groups containing styrene double bonds are bonded to some of the Si atoms in the siloxane structure that constitutes the coating, and the coating and the silica filler are bonded via siloxane bonds.

[0037] By using such surface-modified silica fillers, the compatibility between the silica filler and branched polyphenylene ethers, etc., is improved. Furthermore, the silica filler can react with crosslinking agents, etc., via the coating, making it easier to form cured products with excellent embedding properties and thermal properties. In addition, if the branched polyphenylene ether contains hydrocarbon groups with unsaturated carbon bonds, crosslinking occurs between the crosslinking agent, branched polyphenylene ether, and surface-modified silica filler, making it easier to form cured products with excellent performance.

[0038] The content of surface-modified silica filler in the resin composition is preferably 1% by mass or more, 10% by mass or more, 20% by mass or more, or 30% by mass or more, based on the total solid content of the resin composition, and is also preferably 90% by mass or less, 85% by mass or less, or 80% by mass or less.

[0039] From another perspective, the content of surface-modified silica filler in the resin composition is preferably 50 parts by mass or more, 100 parts by mass or more, 150 parts by mass or more, or 400 parts by mass or more, when the content of branched polyphenylene ether in the resin composition is 100 parts by mass, and also preferably 900 parts by mass or less, 800 parts by mass or less, 700 parts by mass or less, or 600 parts by mass or less.

[0040] The following describes the silica filler and silane coupling agent that are preferably used to construct the surface-modified silica filler. For the surface-modified silica filler, commercially available products that have been surface-treated with a silane coupling agent may be used.

[0041] <Silica Filler> The silica filler may be any of the following: fused silica, spherical silica, amorphous silica, crystalline silica, or fine silica powder.

[0042] The average particle size of the silica filler (or surface-modified silica filler) is preferably 0.001 μm or more, 0.01 μm or more, 0.02 μm or more, 0.05 μm or more, or 0.1 μm or more, and preferably 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 10 μm or less, 2.0 μm or less, 1.0 μm or less, or 0.5 μm or less. Here, the average particle size of the silica filler (or surface-modified silica filler) can be determined as the median diameter (d50, volume basis) based on the cumulative distribution from the measured particle size distribution by the laser diffraction / scattering method using a commercially available laser diffraction / scattering particle size distribution analyzer.

[0043] <Silane coupling agent> The silane coupling agent is not particularly limited as long as it has a styrene double bond at its terminus.

[0044] The silane coupling agent may have only one styrene double bond or may have two or more.

[0045] Examples of silane coupling agents include those shown in the following formula (1).

[0046]

[0047] In formula (1), R １ , R ２ , R ３ Each of these is independently an alkyl group having 1 to 4 carbon atoms, preferably a methyl group or an ethyl group. ４ This is a single bond or a hydrocarbon group having 1 to 10 carbon atoms (preferably 1 to 5 carbon atoms, or 1 to 3 carbon atoms) (preferably an alkylene group), and is preferably a single bond.

[0048] The method for treating the surface of the silica filler with a coupling agent is not particularly limited, and known methods can be used. Typically, the silica surface can be treated by generating silanol groups by hydrolyzing the alkoxy groups of the coupling agent, contacting the coupling agent with silica, and causing dehydration condensation between the silanol groups of the coupling agent and the hydroxyl groups present on the silica surface. This treatment may be carried out in a heated or dry environment as needed. When treating the surface of silica with a coupling agent, the amount of silane coupling agent used should be appropriately adjusted. Specifically, when treating the surface of silica filler with a silane coupling agent, the amount of silane coupling agent added is preferably 0.01 to 20 parts by mass, more preferably 0.05 to 10 parts by mass, and even more preferably 0.1 to 7 parts by mass, per 100 parts by mass of the solid content of the silica filler, from the viewpoint of the effect of reducing CTE by increasing the reaction sites between the filler and the resin in the cured coating film and the effect of reducing melt viscosity.

[0049] Here, whether or not a coating (a coating having a siloxane structure containing styrene double bonds) is formed covering at least a portion of the surface of the silica filler can be confirmed, for example, as follows: Method A is a confirmation method based on the amount of silica filler charged when preparing surface-modified silica filler using a silane coupling agent (a confirmation method based on the raw materials of the resin composition), and Method B is a confirmation method (a confirmation method based on the resin composition) in which the resin composition is made into a film to expose the silica filler and the surface of the silica filler is chemically analyzed.

[0050] <Method A: Confirmation method based on the amount of silica filler charged>In a slurry containing a silica filler and a silane coupling agent having a styrene double bond, a surface modification reaction of the silica filler is carried out. The slurry after the reaction is centrifuged at 50,000 rpm for 15 minutes. The liquid component of the supernatant obtained by centrifugation is analyzed using a gas chromatography analyzer (8890GC / 5977MS manufactured by Agilent Technologies Co., Ltd., column: DB-1MS 30 m × 0.250 mm, 0.25 μm thick). Using the obtained result and the calibration curve separately prepared using only the silane coupling agent, the content (free amount) of the silane coupling agent in the supernatant is quantified. The value obtained by subtracting the free amount from the charged amount of the silane coupling agent used when preparing the slurry is defined as the coating amount. When the coating amount is greater than 0, it is judged that a silica filler having a film covering at least a part of the surface is formed. Moreover, the modification rate of the silane coupling agent at this time can be calculated by the following formula. (Formula) (Charged amount of coupling agent - Amount of released coupling agent) / Amount of non-volatile components in slurry × 100 (%)

[0051] <Method B: Confirmation method by chemical analysis of the filler surface in the resin composition>(Evaluation method) Sample: On the surface of the resin composition film, the side where the silica filler is partially exposed is used as the measurement surface. The resin composition film is produced, for example, by adjusting the thickness as necessary so that the silica filler is exposed, applying the resin composition onto a substrate, and drying. Mass spectrometry (before treatment): By time-of-flight secondary ion mass spectrometry (ToF-SIMS), the ion images of m / z 91 (C ７ H ７ ＋ ), 77 (C ６ H ５ ＋ ), 103 and 104 (C ８ H ７ ＋ / C ８ H ８ ＋ ), and the Si / SiO ２ -related ion images (m / z 28 (Si ＋ ), 44 (SiO ＋ ), 60 and 76 (SiO２ － )) are obtained and the pixel correlation coefficient r between the two is calculated. Tagging process: Pentafluorobenzenethiol (1% by mass acetonitrile solution) is spin-coated onto the sample surface (2000 rpm, 30 seconds), and 365 nm UV (approximately 5 mW / cm²) is exposed to a nitrogen atmosphere. ２ Irradiate with ) for 2 minutes. Then wash and dry with isopropanol. Mass spectrometry / XPS (after processing): C by ToF-SIMS ６ F ５ ＋ CF ３ ＋ We obtained an ion image of Si / SiO ２ The pixel correlation coefficient r with the associated ion image is calculated. Furthermore, the signals for F 1s and Si 2p are measured by X-ray photoelectron spectroscopy (XPS), and the F 1s / Si 2p atomic ratio within the analysis field is determined. (Measurement equipment and conditions) The measurement equipment and conditions applied to ToF-SIMS and XPS are as follows: ToF-SIMS: IONTOF's "Hybrid SIMS (equipped with Orbitrap)". Primary ion: Bi ３＋ , 30 keV, sputtering: Ar gas cluster (n = 1000-5000, 2-10 keV) XPS: Kratos "AXIS Supra+" Al Kα monochromatic line, minute spot (≤100 μm), high-resolution measurement (pass energy 20-40 eV) (Judgment criteria) If the following two or more conditions are met, it is determined that a coating having a siloxane structure containing styrene double bonds has been formed on the surface of the silica filler. 1. Image of fluorine-derived ions after tagging treatment (C ６ F ５ ＋ or CF ３ ＋ ) and Si / SiO ２ 1. The pixel correlation coefficient r of the related ion image is 0.60 or higher. 2. m / z 91(C) before and after tagging. ７ H ７ ＋ The average intensity of ) decreases by more than 20%. 3. The F 1s / Si 2p atomic ratio in XPS is 0.05 or higher.

[0052] <<(D) Radical polymerization initiators>> Radical polymerization initiators are compounds that generate active species (also called free radicals) in response to heat or ultraviolet light, and can easily form crosslinked structures. Radical polymerization initiators are not particularly limited, and photoradical polymerization initiators, thermal radical polymerization initiators, etc., can be used. Radical polymerization initiators can be used alone or in combination of two or more types.

[0053] <Thermal Radical Polymerization Initiators> Examples of thermal radical polymerization initiators include azo polymerization initiators (e.g., 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionic acid)dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis[2 Examples include (5-methyl-2-imidazolin-2-yl)propane dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(N,N'-dimethylene isobutylamidine) dihydrochloride, etc.; peroxide-based polymerization initiators (e.g., dibenzoyl peroxide, t-butyl permaleate, lauroyl peroxide, etc.); and redox polymerization initiators.

[0054] <Photo-radical polymerization initiators> Examples of photo-radical polymerization initiators include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators.

[0055] Specifically, examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one [trade name: Omnirad 651, manufactured by IGM Resins], and anisoine.

[0056] Examples of acetophenone-based photopolymerization initiators include 1-hydroxycyclohexylphenyl ketone [trade name: Omnirad 184, manufactured by IGM Resins], 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one [trade name: Omnirad 2959, manufactured by IGM Resins], 2-hydroxy-2-methyl-1-phenyl-propan-1-one [trade name: Omnirad 1173, manufactured by IGM Resins], and methoxyacetophenone.

[0057] Examples of α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)-phenyl]-2-hydroxy-2-methylpropan-1-one.

[0058] Examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)-oxime.

[0059] Benzoin-based photopolymerization initiators include, for example, benzoin. Benzyl-based photopolymerization initiators include, for example, benzyl. Benzophenone-based photopolymerization initiators include, for example, benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenyl ketone, and the like.

[0060] Ketal-based photopolymerization initiators include, for example, benzyldimethylketal. Thioxanthone-based photopolymerization initiators include, for example, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

[0061] Examples of acylphosphine-based photopolymerization initiators include bis(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)(2,4,4-trimethylpentyl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-n-butylphosphine oxide, bis(2,6-dimethoxybenzoyl)-(2-methylpropan-1-yl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-(1-methylpropan-1-yl)phosphine oxide, and bis(2,6-dimethoxybenzoyl Bis(2,6-dimethoxybenzoyl)cyclohexylphosphine oxide, Bis(2,6-dimethoxybenzoyl)octylphosphine oxide, Bis(2-methoxybenzoyl)(2-methylpropan-1-yl)phosphine oxide, Bis(2-methoxybenzoyl)(1-methylpropan-1-yl)phosphine oxide, Bis(2,6-diethoxybenzoyl)(2-methylpropan-1-yl)phosphine oxide, Bis(2,6-diethoxybenzoyl)(1-methylpropan-1-yl)phosphine oxide -yl)phosphine oxide, bis(2,6-dibutoxybenzoyl)(2-methylpropan-1-yl)phosphine oxide, bis(2,4-dimethoxybenzoyl)(2-methylpropan-1-yl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)(2,4-dipentoxyphenyl)phosphine oxide, bis(2,6-dimethoxybenzoyl)benzylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylpropylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-f Phenylethylphosphine oxide, bis(2,6-dimethoxybenzoyl)benzylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylpropylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylethylphosphine oxide, 2,6-dimethoxybenzoylbenzylbutylphosphine oxide, 2,6-dimethoxybenzoylbenzyloctylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,5-diisopropylphenylphosphine oxide, bis(2,4,6-Trimethylbenzoyl)-2-methylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-4-methylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,5-diethylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,3,5,6-tetramethylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl) Examples include -2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)isobutylphosphine oxide, 2,6-dimethitoxybenzoyl-2,4,6-trimethylbenzoyl-n-butylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-dibutoxyphenylphosphine oxide, 1,10-bis[bis(2,4,6-trimethylbenzoyl)phosphine oxide]decane, tri(2-methylbenzoyl)phosphine oxide, etc.

[0062] The content of the radical polymerization initiator in the resin composition is preferably 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, based on the total solid content of the resin composition excluding fillers, and is also preferably 10% by mass or less, 5% by mass or less, or 3% by mass or less.

[0063] <<Other Ingredients>> Other ingredients include elastomers, flame retardant enhancers (phosphorus compounds, etc.), cellulose nanofibers, resin components (cyanate ester resins, epoxy resins, phenol novolac resins, etc.), dispersants, curing accelerators, adhesion enhancers, etc.

[0064] The resin composition relating to this disclosure preferably contains an elastomer as another component. Conventionally known elastomers can be used. Examples of elastomers include diene-based synthetic rubbers (polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, polychloroprene rubber, nitrile rubber, ethylene-propylene rubber, etc.), non-diene-based synthetic rubbers (ethylene-propylene rubber, butyl rubber, acrylic rubber, polyurethane rubber, fluororubber, silicone rubber, epichlorohydrin rubber, etc.), natural rubber, styrene-based elastomers, olefin-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, acrylic-based elastomers, and silicone-based elastomers, as well as modified versions thereof.

[0065] The elastomer content in the resin composition is preferably 1% by mass or more, 5% by mass or more, or 10% by mass or more, based on the total solid content of the resin composition excluding fillers, and is also preferably 50% by mass or less, 40% by mass or less, or 30% by mass or less.

[0066] The resin composition relating to this disclosure may be provided in the form of a solvent-containing varnish.

[0067] Suitable solvents include conventionally usable solvents such as chloroform, methylene chloride, and toluene, as well as relatively safe solvents such as N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), cyclohexanone, propylene glycol monomethyl ether acetate (PMA), diethylene glycol monoethyl ether acetate (CA), methyl ethyl ketone, and ethyl acetate. N,N-dimethylformamide (DMF) may also be used as the solvent. One solvent may be used, or two or more solvents may be used.

[0068] The solvent content in the resin composition can be adjusted as appropriate depending on the intended use of the resin composition.

[0069] The resin composition relating to this disclosure may contain (A) polyphenylene ethers other than branched polyphenylene ethers (linear polyphenylene ethers). The content of linear polyphenylene ethers in the resin composition is preferably 10% by mass or less, 5% by mass or less, 3% by mass or less, or 1% by mass or less, based on the total solid content of the resin composition excluding fillers.

[0070] The resin composition relating to this disclosure may contain silica fillers other than (C) surface-modified silica fillers (other silica fillers). In that case, the content of other silica fillers in the resin composition is preferably 50% by mass or less, 30% by mass or less, 10% by mass or less, or 1% by mass or less, based on the total amount of solids in the resin composition.

[0071] <<<Dry Film>>> The dry film according to this disclosure comprises a resin layer formed from a resin composition. The dry film according to this disclosure can be manufactured by applying the resin composition according to this disclosure to a first film (e.g., a carrier film) and drying it to form a resin layer as a dry coating. A second film (e.g., a protective film) can be laminated onto the resin layer as needed.

[0072] The first film is a film that supports the resin layer of the dry film, and when it is laminated onto a substrate such as a substrate by heating or other means to form an integral structure, it is at least in close contact with the resin layer. As the first film, for example, films made of thermoplastic resins such as polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyimide films, polyamide-imide films, polyethylene films, polytetrafluoroethylene films, polypropylene films, and polystyrene films, and surface-treated paper can be used. Among these, polyester films can be suitably used from the viewpoint of heat resistance, mechanical strength, and handling. The thickness of the first film is not particularly limited and is generally selected appropriately in the range of 10 to 150 μm depending on the application. The surface of the first film on which the resin layer is provided may be treated with a release agent. In addition, sputtering or copper foil may be formed on the surface of the first film on which the resin layer is provided.

[0073] The second film is provided on the side of the resin layer opposite the first film to the resin layer of the dry film, for the purpose of preventing dust and other particles from adhering to the surface of the resin layer of the dry film and improving handling. The second film is peeled off from the resin layer before lamination when the dry film is laminated onto a substrate such as a substrate by heating or other means so that the resin layer side of the dry film is in contact with it. As the second film, for example, a film made of thermoplastic resin as exemplified in the first film, and surface-treated paper can be used, but among these, polyester film, polyethylene film, and polypropylene film are preferred. The thickness of the second film is not particularly limited and is generally selected appropriately in the range of 10 to 150 μm depending on the application. The side of the second film on which the resin layer is provided may be treated with a release agent. Furthermore, it is preferable that the adhesive force between the resin layer and the second film is less than the adhesive force between the resin layer and the first film when the second film is peeled off.

[0074] When manufacturing a dry film, either the first film or the second film may be used as the film to which the resin composition according to this disclosure is coated.

[0075] <<<Cured Product>>> The cured product according to this disclosure is obtained by curing the resin composition according to this disclosure or the resin layer of the dry film according to this disclosure. The curing method is not particularly limited, and conventionally known methods can be used. Examples of curing methods include heating at 150 to 230°C.

[0076] The specific method for obtaining a cured product from a resin composition can be appropriately modified depending on the composition of the resin composition. For example, a process can be carried out in which the resin composition is applied to a circuit substrate on which a circuit pattern has been formed (e.g., by applying with an applicator), followed by a drying process to dry the resin composition as needed, and then a thermocuring process to thermally crosslink the polyphenylene ether by heating (e.g., by heating with an inert gas oven, hot plate, vacuum oven, vacuum press, etc.). The conditions for each step (e.g., coating thickness, drying temperature and time, heating temperature and time, etc.) can be appropriately modified depending on the composition of the resin composition and its intended use.

[0077] Furthermore, when obtaining a cured product using a dry film with a three-layer structure in which a resin layer is sandwiched between a first film and a second film, a printed circuit board can be manufactured in the following manner. The second film is peeled off from the dry film, heat-laminated onto a circuit board on which a circuit pattern has been formed, and then a heat-curing process is carried out. The heat-curing process may be carried out by curing in an oven or by hot plate pressing. When laminating or hot plate pressing the circuit-formed substrate and the dry film of the present invention, copper foil or the circuit-formed substrate can also be laminated at the same time. A printed circuit board can be manufactured by forming patterns or via holes at positions corresponding to predetermined positions on the circuit-formed substrate using laser irradiation or drilling, thereby exposing the circuit wiring. In this case, if there are residual components (smear) that cannot be completely removed on the circuit wiring in the patterns or via holes, a desmear treatment may be performed. The first film can be peeled off at any of the following timings: after lamination, after heat curing, after laser processing, or after desmear treatment.

[0078] Because the cured product according to this disclosure can have excellent low dielectric properties and mechanical properties, it can be suitably applied to various electronic components, including high-capacity, high-speed communication systems such as fifth-generation communication systems (5G) and millimeter-wave radar for automotive ADAS (Advanced Driver-Assistance Systems).

[0079] Next, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to these.

[0080] <<<Raw Materials>>> <<Polyphenylene Ether>> <Branched PPE>> 19.8 g (0.16 mol) of 2,6-dimethylphenol and 2.42 g (0.018 mol) of 2-allylphenol were added to a 500 mL separable flask, and the resulting mixture was dissolved in 261 g of toluene. Further preparation was carried out so that the mixture contained 0.18 mass% di-μ-hydroxo-bis[(N,N,N',-tetramethylethylenediamine)copper(II)]chloride (Cu / TMEDA) and 0.16 mass% tetramethylethylenediamine (TMEDA). Dry air was blown into the reaction solution at a flow rate of 75 mL / min, and the mixture was stirred at a stirring speed of 200 rpm using a four-bladed paddle blade, and the reaction was carried out at 40°C for a predetermined time to obtain a reaction solution containing polyphenylene ether. After stopping the heating of the reaction solution and the blowing of dry air, di-μ-hydroxor-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)]chloride (Cu / TMEDA) was removed by filtration, reprecipitation was performed with a mixture of 1,200 mL of methanol, 4.0 mL of concentrated hydrochloric acid, and 27.0 mL of water, and the solution was removed by vacuum filtration. After washing with methanol, the solution was dried at 80°C for 24 hours to obtain reactive branched polyphenylene ether. The number-average molecular weight (Mn) of the obtained reactive branched polyphenylene ether (branched PPE) was 14,000, and the weight-average molecular weight was 38,000 (Mw).

[0081] The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of branched PPE were determined by gel permeation chromatography (GPC). In the GPC, a Shodex K-805L column was used, with a column temperature of 40°C, a flow rate of 1 mL / min, chloroform as the eluent, and polystyrene as the standard substance.

[0082] <Linear PPE> 2.28 g of bisphenol A and 100 g of 2,6-dimethylphenol were added to a 500 mL separable flask, and the resulting mixture was dissolved in 261 g of toluene. Furthermore, the mixture was adjusted to contain 0.18 mass% of di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) and 0.16 mass% of tetramethylethylenediamine (TMEDA). Dry air was blown into the reaction mixture at a flow rate of 75 mL / min, and the mixture was stirred at a stirring speed of 200 rpm using a four-bladed paddle. The reaction was carried out at 40°C for a predetermined time to obtain a reaction solution containing polyphenylene ether. After stopping the heating of the reaction solution and the blowing of dry air, di-μ-hydroxor-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)]chloride (Cu / TMEDA) was removed by filtration, reprecipitation was performed with a mixture of 1,200 mL of methanol, 4.0 mL of concentrated hydrochloric acid, and 27.0 mL of water, and the solution was removed by vacuum filtration. After washing with methanol, it was dried at 80°C for 24 hours to obtain linear PPE as polyphenylene ether with Mn = 10,000 (PDI = 4).

[0083] <<Crosslinking Agents>> • Product Name: TAIC, manufactured by Mitsubishi Chemical Corporation, triallyl isocyanurate • Product Name: DAP, manufactured by Osaka Soda Co., Ltd., diallyl phthalate

[0084] <<Filler>> <Example of preparation of surface-modified filler> - As a filler component, spherical silica filler (manufactured by Denka Co., Ltd., product name: SFP-20M, d50 = 0.4 μm, specific surface area 11.2 m²) 2A filler dispersion was obtained by adding 44 parts by mass of cyclohexanone as a solvent and 2 parts by mass of KBM-1403 (manufactured by Shin-Etsu Chemical Co., Ltd.: 4-vinylphenyltrimethoxysilane) as a silane coupling agent to 100 parts by mass of silica filler ( / g) to disperse the surface-modified filler. Since this surface-modified filler is treated with a silane coupling agent, it has a structure in which at least a part of the surface of the silica filler is covered with a film, and the film contains a siloxane structure containing a styrene double bond. <Other fillers> ・Product name SC2050-HNF, manufactured by Admatex Co., Ltd., a filler surface-modified with a silane coupling agent having a vinyl group

[0085] <<Radical Polymerization Initiator>> Product Name: Perbutyl P40, manufactured by NOF Corporation, α,α'-bis(t-butylperoxy-m-isopropyl)benzene

[0086] <<Other Ingredients>> <Elastomer> ・Product name: H1051, manufactured by Asahi Kasei Corporation

[0087] <<<Preparation of Resin Composition>>> <<Example 1>> 100 g (100 parts by mass) of branched PPE, which is a polyphenylene ether, was dissolved completely by adding 900 g (900 parts by mass) of cyclohexanone as a solvent and stirring thoroughly in a rotating / revolving mixer. To the obtained branched PPE resin solution, 50 g (50 parts by mass) of TAIC, a crosslinking agent, 629 g (440 parts by mass in terms of solid content) of surface modifying filler, and 35 g (35 parts by mass) of ToughTec H1051, an elastomer, were added and stirred in a rotating / revolving mixer. Finally, 3 g (3 parts by mass) of perbutyl P40, a radical polymerization initiator, was added and stirred thoroughly in a rotating / revolving mixer to obtain the varnish of the resin composition of Example 1.

[0088] <<Examples 2-4 and Comparative Examples 1-3>> Varnishes of resin compositions according to Examples 2-4 and Comparative Examples 1-3 were obtained in the same manner as in Example 1, except that the values ​​of each component and their content were as shown in Table 1 below.

[0089] <<<Evaluation>>> <<Preparation of Test Cured Films>> The varnish of the resin composition of each example and comparative example was applied with an applicator onto a first film, a 38 μm thick high-smooth grade PET film (manufactured by Toray Industries, Inc.: product name "R80"), so that the thickness after drying was 35 μm. The varnish was then dried in a hot air circulating drying oven at 90°C for 15 minutes to obtain test dry films for each example and comparative example. The test dry films for each example and comparative example were laminated to a smooth copper foil using a vacuum laminator (manufactured by Nikko Materials Co., Ltd. "CVP-600") at 130°C and 0.8 MPa so that the resin layer of the dry film was in contact with it. The oven was then heated to 200°C in an inert oven with nitrogen completely filled, and heated for 60 minutes to cure. The first film was peeled off, and the copper foil was etched to obtain a test cured film.

[0090] <Film Formation Properties> The cured test films of each of the above examples and comparative examples were observed and evaluated according to the following criteria. (Evaluation Criteria) A: The cured film is uniform. C: The cured film is non-uniform or crumbled during etching of the copper foil.

[0091] <Embedding Properties> For each example and comparative example, a dry film for testing and a core substrate were prepared, which was a copper-clad laminate with a copper thickness of 35 μm, on which circular venting holes with a diameter of 200 μm were formed in a grid pattern at 900 μm intervals using a subtractive method. Laminated a laminate by using a vacuum laminator ("CVP-600" manufactured by Nikko Materials Co., Ltd.) at 130°C and 0.8 MPa so that the resin layers of the dry film were in contact with both sides of the core substrate. An inert oven was used to completely fill the laminate with nitrogen and raise the temperature to 200°C, heating the laminate for 60 minutes to cure it, and the first film was peeled off the laminate to obtain a substrate for embedding properties testing. This substrate was observed with an optical microscope to evaluate the presence or absence of voids. (Evaluation Criteria) A: No voids in the embedded area, and the material is embedded. C: Voids are present in the embedded area.

[0092] <Coefficient of Thermal Expansion (CTE)> Test cured films of each example and comparative example were cut to obtain a measurement size (3 mm x 30 mm), and the CTE was measured using a TMA (Thermomechanical Analysis) Q400 manufactured by T.A. Instrument Japan Co., Ltd. The measurement conditions were tensile mode, with a chuck distance of 16 mm, a load of 30 mN, and under a nitrogen atmosphere, the temperature was raised from -50 to 300°C at 10°C / min, then cooled from 300 to -50°C at 10°C / min, and then raised again from -50 to 300°C at 10°C / min for measurement. The average coefficient of thermal expansion (CTE) from 50°C to 100°C during the second heating cycle was determined. (Evaluation Criteria) A: CTE(α1) is 30 ppm / K or less B: CTE(α1) is greater than 30 ppm / K and 40 ppm / K or less C: CTE(α1) is greater than 40 ppm / K

[0093] <Dielectric Properties> Test cured films of each example and comparative example were cut to the measurement size (45 mm x 80 mm), and the dielectric constant (Dk) and dielectric loss tangent (Df) were measured using the SPDR (Split Post Dielectric Resonator) resonator method. The measuring instrument used was a vector network analyzer E5071C manufactured by Keysight Technologies LLC, an SPDR resonator, and a calculation program manufactured by QWED. The measurement conditions were a frequency of 10 GHz and a measurement temperature of 25°C. (Dk evaluation criteria) A: Dk is 3.2 or less B: Dk is greater than 3.2 and 3.4 or less C: Df is greater than 3.4 (Df evaluation criteria) A: Df is 0.0030 or less C: Df is greater than 0.0030

[0094]

[0095] The resin composition according to this disclosure readily forms a cured product with excellent embedding properties and thermal properties. Therefore, it is suitably applicable to a variety of uses, including electronic components. Cross-reference of related applications

[0096] This application claims priority based on Japanese Patent Application No. 2024-199694, filed with the Japan Patent Office on November 15, 2024, all of which disclosures are incorporated herein by reference in their entirety.

Claims

1. A resin composition comprising (A) a branched polyphenylene ether, (B) a crosslinking agent, (C) a surface-modified silica filler, and (D) a radical polymerization initiator, wherein (C) the surface-modified silica filler comprises a silica filler and a coating, the coating covering at least a portion of the surface of the silica filler and containing a siloxane structure including a styrene double bond.

2. A dry film comprising a resin layer formed by the resin composition described in claim 1.

3. A cured product obtained using the resin composition according to claim 1 or the resin layer of the dry film according to claim 2.

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