Curable resin composition, dry film, cured object, and electronic component

Abstract

Provided is a curable resin composition which contains a powder having a low volume resistivity, can be inhibited from suffering warpage due to curing shrinkage, and gives cured objects having excellent insulating properties. The curable resin composition comprises (A) a dicyclopentadiene-based epoxy resin, (B) an epoxy resin (which is not the dicyclopentadiene-based epoxy resin (A)), and a powder (C) having a volume resistivity of 1×106 Ω·cm or less, wherein the epoxy resin (B) has an epoxy equivalent in the range of 200-1,000.

Description

Curable resin composition, dry film, cured product, and electronic component

[0001] The present invention relates to a curable resin composition, a dry film, a cured product, and an electronic component. Related Applications

[0002] This application claims priority based on Japanese Patent Application No. 2024-028985, filed on February 28, 2024, the contents of which are incorporated herein by reference.

[0003] In recent years, electronic devices have become smaller and more powerful, and there is an increasing demand for smaller and thinner printed wiring boards as well as inductor components (coils) mounted on printed wiring boards. When manufacturing thin inductor components or inductor components with a coreless structure, a magnetic layer (insulating layer) is formed from a resin composition containing a magnetic filler.

[0004] For example, Patent Document 1 discloses that by using a paste composition containing core-shell structured particles with magnetic inorganic particles as the core and a matrix resin, it is possible to achieve properties such as high magnetic permeability, low tan δ, and high volume resistivity. Furthermore, Patent Document 2 discloses that by using a resin composition containing an epoxy resin, a magnetic filler, a curing agent, and an amphiphilic polyether block copolymer, it is possible to maintain magnetic permeability and suppress warping.

[0005] JP 2012-201726 A JP 2019-065208 A

[0006] However, since the magnetic powders described in Patent Documents 1 and 2 generally have low volume resistivities, it is difficult to simultaneously satisfy both magnetic properties and insulating properties. Furthermore, since curable resins are prone to warping due to cure shrinkage, it is difficult to simultaneously satisfy both insulating properties and warpage suppression.

[0007] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a curable resin composition containing a powder with low volume resistivity, which can suppress warping due to cure shrinkage, and which can produce a cured product with excellent insulating properties. Another object of the present invention is to provide a dry film containing the curable resin composition. Another object of the present invention is to provide a cured product containing a powder with low volume resistivity, which suppresses warping due to cure shrinkage, and which has excellent insulating properties, and an electronic component including the cured product.

[0008] The inventors have investigated the above problem and found that the volume resistivity is 1×10 ６ It has been found that, even when a powder having a resistivity of Ω cm or less is contained, the use of a dicyclopentadiene-type epoxy resin makes it possible to ensure the insulating properties of the cured product obtained by curing a curable resin composition. It has also been found that the use of a dicyclopentadiene-type epoxy resin in combination with a specific epoxy resin makes it possible to suppress warpage due to cure shrinkage of the curable resin composition. The present invention is based on these findings. That is, the gist of the present invention is as follows.

[0009] [1] (A) a dicyclopentadiene-type epoxy resin, (B) an epoxy resin (excluding the (A) dicyclopentadiene-type epoxy resin), and (C) an epoxy resin having a volume resistivity of 1×10 ６ [2] A curable resin composition according to [1], wherein the (A) dicyclopentadiene-type epoxy resin is a solid epoxy resin. [3] The (C) curable resin composition according to [1], wherein the (C) volume resistivity is 1×10 ６The curable resin composition according to [1] or [2], wherein the powder having a resistivity of Ω·cm or less is a magnetic powder. [4] The curable resin composition according to any one of [1] to [3], wherein the epoxy equivalent of the (B) epoxy resin is in the range of 200 to 700. [5] The curable resin composition according to any one of [1] to [4], wherein the epoxy equivalent of the (B) epoxy resin is in the range of 200 to 500. [6] The curable resin composition according to any one of [1] to [5], further comprising (D) a phenoxy resin. [7] The curable resin composition according to any one of [1] to [6], further comprising (E) a solvent. [8] The curable resin composition according to any one of [1] to [7], wherein the (B) epoxy resin comprises an epoxy resin having a propylene glycol skeleton. [9] A dry film comprising: a first film; and a resin layer formed on at least one surface of the first film and comprising the curable resin composition according to any one of [1] to [8].

[10] A cured product obtained by curing the curable resin composition according to any one of [1] to [8].

[11] A cured product obtained by curing the resin layer of the dry film according to [9].

[12] An electronic component having the cured product according to

[10] or

[11] .

[0010] The curable resin composition of the present invention contains a powder with low volume resistivity, which can suppress warping due to cure shrinkage and provide a cured product with excellent insulation. The dry film of the present invention contains a powder with low volume resistivity, which can suppress warping due to cure shrinkage and provide a cured product with excellent insulation. The cured product of the present invention and an electronic component including the cured product contain a powder with low volume resistivity, which can suppress warping due to cure shrinkage and provide excellent insulation.

[0011] In this specification, numerical ranges expressed using "to" include both ends of the range.

[0012] [Curable Resin Composition] The curable resin composition of the present invention comprises (A) a dicyclopentadiene-type epoxy resin, (B) an epoxy resin having an epoxy equivalent in the range of 200 to 1000 (excluding the (A) dicyclopentadiene-type epoxy resin), and (C) an epoxy resin having a volume resistivity of 1×10 ６ It contains at least powder of Ω·cm or less.

[0013] <(A) Dicyclopentadiene-Type Epoxy Resin> The curable resin composition of the present invention contains (A) a dicyclopentadiene-type epoxy resin. As a result, the cured product obtained by curing the curable resin composition of the present invention has an extremely low moisture absorption rate due to the rigid dicyclopentadiene skeleton of (A) the dicyclopentadiene-type epoxy resin, and therefore has improved insulation reliability under high-temperature and high-humidity environments.

[0014] The dicyclopentadiene epoxy resin (A) is not particularly limited as long as it has a dicyclopentadiene skeleton and an epoxy group, and examples thereof include epoxy resins represented by the following general formula (1): These dicyclopentadiene epoxy resins may be used alone or in combination of two or more types.

[0015]

[0016] In general formula (1), m R's each independently represent a hydrogen atom, a methyl group, an ethyl group, a propyl group, or a t-butyl group. Of the hydrogen atom, the methyl group, the ethyl group, the propyl group, and the t-butyl group, R's are preferably any of the hydrogen atom, the methyl group, and the t-butyl group, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom. n is an integer of 0 to 4, preferably 1, 2, 3, or 4, more preferably 2, 3, or 4, and even more preferably 2 or 3. m is an integer of 1 to 3, preferably 1 or 2, and more preferably 1.

[0017] The weight average molecular weight (Mw) of the (A) dicyclopentadiene type epoxy resin is not particularly limited, but is preferably 100 or more, more preferably 150 or more. The weight average molecular weight (Mw) is preferably 20,000 or less, more preferably 10,000 or less. Of these, the (A) dicyclopentadiene type epoxy resin is preferably a solid epoxy resin having a weight average molecular weight (Mw) of 150 or more and 10,000 or less. When the (A) dicyclopentadiene type epoxy resin is a solid epoxy resin, when a dry film having the curable resin composition of the present invention as a resin layer is formed, it becomes easy to control the fluidity during lamination.

[0018] In this specification, the weight average molecular weight (Mw) value can be measured by gel permeation chromatography (GPC) (polystyrene standard) using the following measuring device and measurement conditions: Measuring device: Waters "Waters 2695" Detector: Waters "Waters 2414", RI (differential refractometer) Column: Waters "HSPgel Column, HR MB-L, 3 μm, 6 mm × 150 mm" × 2 + Waters "HSPgel Column, HR1, 3 μm, 6 mm × 150 mm" × 2 Measurement conditions: Column temperature: 40°C RI detector set temperature: 35°C Developing solvent: tetrahydrofuran Flow rate: 0.5 mL / min Sample amount: 10 μL Sample concentration: 0.7% by mass

[0019] The epoxy equivalent of the (A) dicyclopentadiene epoxy resin is not particularly limited, but is preferably 200 or more, more preferably 220 or more. The epoxy equivalent is preferably 700 or less, more preferably 500 or less. Specifically, the epoxy equivalent is preferably in the range of 200 or more and 700 or less. Having the epoxy equivalent within the above range reduces moisture absorption and provides excellent heat resistance. In this specification, the epoxy equivalent value is measured in accordance with JIS K7236:2001.

[0020] (A) Commercially available dicyclopentadiene epoxy resins include, for example, HP-7200L (epoxy equivalent: 247, manufactured by DIC Corporation), HP-7200H (epoxy equivalent: 278, manufactured by DIC Corporation), and HP-7200 (epoxy equivalent: 257, manufactured by DIC Corporation).

[0021] The blending amount of the dicyclopentadiene epoxy resin (A) is preferably 0.2 parts by mass or more and 50 parts by mass or less, and more preferably 0.2 parts by mass or more and 30 parts by mass or less, relative to the total amount of the epoxy resin (B) described below. When the blending amount of the dicyclopentadiene epoxy resin (A) is 0.8 parts by mass or more, the insulating properties of the cured product of the curable resin composition can be improved.

[0022] <(B) Epoxy Resin> The curable resin composition of the present invention contains (B) an epoxy resin (excluding (A) a dicyclopentadiene-type epoxy resin) having an epoxy equivalent in the range of 200 to 1000. By using a dicyclopentadiene-type epoxy resin in combination with an epoxy resin having an epoxy equivalent in the range of 200 to 1000, warping of the cured product due to cure shrinkage of the curable resin composition can be suppressed.

[0023] The epoxy resin (B) has two or more epoxy groups per molecule, and can be any resin other than the dicyclopentadiene epoxy resin (A) described above. Examples include bisphenol A epoxy resin, bisphenol F epoxy resin, hydrogenated bisphenol A epoxy resin, brominated bisphenol A epoxy resin, bisphenol S epoxy resin, phenol novolac epoxy resin, cresol novolac epoxy resin, bisphenol A novolac epoxy resin, biphenyl epoxy resin, naphthol epoxy resin, naphthalene epoxy resin, triphenylmethane epoxy resin, alicyclic epoxy resin, aliphatic linear epoxy resin, phosphorus-containing epoxy resin, anthracene epoxy resin, norbornene epoxy resin, adamantane epoxy resin, fluorene epoxy resin, aminophenol epoxy resin, aminocresol epoxy resin, and alkylphenol epoxy resin.

[0024] The epoxy resin (B) may be in any of a liquid, semi-solid, or solid form, but is preferably in a liquid or semi-solid form from the viewpoint of flowability and film-forming properties. The term "liquid" refers to a liquid state having flowability at 20°C.

[0025] Furthermore, the curable resin composition of the present invention preferably contains an epoxy resin having a propylene glycol skeleton as the epoxy resin (B). By including an epoxy resin having a propylene glycol skeleton as the epoxy resin (B), flexibility can be imparted to the curable resin composition, thereby suppressing cure shrinkage during curing. As a result, warping of the cured product can be suppressed. Commercially available products of these epoxy resins include EP-4000S, EP-4000L, EP-4003S, EP-4010S, EP-4010L, and EP-4040L (manufactured by ADEKA Corporation, trade names), D.E.R. 732 (manufactured by The Dow Chemical Company, trade name), and Denacol EX-830, 832, 841, and 861 (manufactured by Nagase ChemteX Corporation, trade names).

[0026] The curable resin composition of the present invention may also contain, as the epoxy resin (B), an epoxy resin having a polyether skeleton or an epoxy resin having a bisphenol skeleton. Examples of epoxy resins having a polyether skeleton include epoxy resins having a linear or alicyclic polyether skeleton containing 2 to 12 carbon atoms. Commercially available products of these include jER YX7400 and jER YX7400N manufactured by Mitsubishi Chemical Corporation. Examples of epoxy resins having a bisphenol skeleton include bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol E (AD) epoxy resins, and bisphenol S epoxy resins.

[0027] These epoxy resins having a bisphenol skeleton may be used alone or in combination of two or more, but from the viewpoint of excellent filling properties and therefore a favorable effect on the properties after curing, it is preferable to use a combination of epoxy resins selected from bisphenol A epoxy resins, bisphenol F epoxy resins, and bisphenol E (AD) epoxy resins. Commercially available products of these include jER834, jER1001 (bisphenol A epoxy resins), and jER4004P (bisphenol F epoxy resins) manufactured by Mitsubishi Chemical Corporation.

[0028] The above-mentioned epoxy resins can be used alone or in combination of two or more.

[0029] The lower limit of the epoxy equivalent of the (B) epoxy resin is 200 or more, preferably 250 or more, and more preferably 300 or more. The upper limit of the epoxy equivalent is 1000 or less, preferably 700 or less, and more preferably 500 or less. An epoxy equivalent of 200 or more and 1000 or less is preferable because it is possible to achieve both warpage suppression and insulation properties.

[0030] <(C) Powder> The curable resin composition of the present invention includes (C) a powder having a volume resistivity of 1×10 ６ This includes powders with a volume resistivity of Ω·cm or less. Here, the volume resistivity of (C) powder is a value measured by the following method. 1.0 g of each powder is weighed and introduced into a powder resistivity measurement probe unit (radius 10.0 mm), and the sample is gradually pressurized using a powder resistivity measurement system (MCP-PD51 model, manufactured by Nitto Seiko Analytech Co., Ltd.) and an attached hydraulic pump. After reaching the target load (20 kN), the powder is measured with a low resistivity meter (Loresta-GP, manufactured by Nitto Seiko Analytech Co., Ltd.) at an electrode distance of 3 mm. The volume resistivity of (C) powder is 1×10 ６ There are no particular limitations as long as the resistivity is Ω·cm or less. It is preferable that such powder (C) contains an inorganic filler. Known inorganic fillers used in ordinary resin compositions can be used as the inorganic filler. Non-metallic fillers, metallic fillers, and the like can be used as the inorganic filler. Specific examples of non-metallic fillers include silica, barium sulfate, calcium carbonate, silicon nitride, aluminum nitride, boron nitride, alumina, magnesium oxide, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica, talc, and organic bentonite. Specific examples of metallic fillers include copper, gold, silver, palladium, and silicon. These inorganic fillers may be used alone or in combination of two or more.

[0031] The curable resin composition of the present invention may contain, as the powder (C), a filler treated with a fatty acid to impart thixotropy, or an amorphous filler such as organic bentonite or talc.

[0032] (C) Volume resistivity is 1 x 10 ６ The powder having a resistivity of Ω cm or less is preferably a magnetic powder. By including a magnetic powder in the curable resin composition of the present invention, noise electromagnetic waves in the near electromagnetic field can be suppressed or absorbed, resulting in an electronic component with excellent noise suppression and other properties even when multiple circuit elements are mounted. Furthermore, the composition can be suitably used as an insulating material for high-frequency inductor elements that require high magnetic permeability in the range of 1 MHz to 200 MHz.

[0033] The magnetic powder has a magnetic permeability of more than 1.0. The magnetic permeability can be measured at a temperature of 25°C and 100 MHz using, for example, an E5071C ENA network analyzer manufactured by Keysight Corporation, as described below, and the measured real part (μ') is the magnetic permeability.

[0034] The magnetic powder is not particularly limited, and non-conductive magnetic materials or conductive magnetic materials can be used. Examples of non-conductive magnetic materials that can be used include spinel ferrites, hexagonal ferrites, and garnet ferrites. Examples of non-conductive magnetic materials include spinel ferrites such as Mg-Zn ferrite, Mn-Zn ferrite, Mn-Mg ferrite, Cu-Zn ferrite, Mg-Mn-Sr ferrite, and Ni-Zn ferrite, hexagonal ferrites such as Ba-Zn ferrite, Ba-Mg ferrite, Ba-Ni ferrite, Ba-Co ferrite, and Ba-Ni-Co ferrite, and garnet ferrites such as Y ferrite, as well as pure iron powder and Fe-Si ferrite. Examples of conductive magnetic materials include Fe alloys such as alloy powder, Fe-Si-Al alloy powder, Ni powder, Fe-Ni alloy powder, Fe-Ni-Mo alloy powder, Fe-Ni-Mo-Cu alloy powder, Fe-Co alloy powder, Fe-Ni-Co alloy powder, Fe-Cr alloy powder, Fe-Cr-Si alloy powder, Fe-Ni-Cr alloy powder, and Fe-Cr-Al alloy powder, Ni alloys, and amorphous alloys such as Fe-based amorphous and Co-based amorphous.

[0035] The curable resin composition of the present invention is required to have insulating properties in its cured product, and the volume resistivity is 1×10 ６ Any magnetic powder having a resistivity of Ω cm or less can be used as powder (C). Even conductive magnetic powder can be used as powder (C) by adjusting the blending amount or by coating its surface with an insulating inorganic or organic material.

[0036] Furthermore, commercially available magnetic powders can be used as the magnetic powder. Specific examples of commercially available magnetic powders include "AW2-08PF20F," "AW2-08PF10F," and "AW2-08PF3F" manufactured by Epson Atmix Corporation, and "M03S," "M10S," and "NZ03S" manufactured by Powdertech Co., Ltd. One type of magnetic powder may be used alone, or two or more types may be used in combination.

[0037] The shape of the powder (C) is not particularly limited, and examples thereof include spherical, needle-like, plate-like, scaly, hollow, irregular, hexagonal, cubic, and flaky shapes.

[0038] The average particle size of the (C) powder can be appropriately selected taking into consideration the dispersibility in the liquid component, the ability to fill holes, and the smoothness when a wiring layer is formed on the filled holes. The average particle size of the (C) powder is preferably in the range of 0.01 μm to 25 μm, more preferably 0.01 μm to 15 μm. The average particle size means the average primary particle size, and the average particle size (D50) can be measured by a laser diffraction / scattering method.

[0039] The blending amount of the (C) powder is preferably 20 to 70% by volume, and more preferably 20 to 65% by volume, calculated as solid content, of the curable resin composition, from the viewpoint of achieving a balance between the thermal expansion coefficient, polishability, and adhesion of the cured product and the printability and hole-filling properties.

[0040] In addition, from the viewpoint of uniform dispersion of the powder (C) in the curable resin composition, a dispersant may be used in combination. As the dispersant, phosphate esters and acrylic copolymers having acidic groups, basic groups, or both, polyamines, polyurethanes, polyesters, polyacrylates, and their phosphates and alkylammonium salts, etc., having acidic groups, basic groups, or both, can be suitably used. The above-mentioned dispersants may be used alone or in combination.

[0041] <(D) Phenoxy Resin> The curable resin composition of the present invention may further contain (D) a phenoxy resin as a thermoplastic resin. When the curable resin composition contains (D) a phenoxy resin, the mechanical strength of the obtained cured product can be improved.

[0042] The thermoplastic resin is preferably soluble in a solvent. When the thermoplastic resin is soluble in a solvent, when a dry film is obtained from the curable resin composition, the flexibility of the dry film is improved, and the occurrence of cracks and powder fall can be suppressed. Examples of the thermoplastic resin include thermoplastic polyhydroxypolyether resins, phenoxy resins which are condensates of epichlorohydrin and various bifunctional phenol compounds, or phenoxy resins in which the hydroxyl groups of the hydroxyether moieties present in the skeleton are esterified using various acid anhydrides or acid chlorides, polyvinyl acetal resins, polyamide resins, polyamideimide resins, block copolymers, etc. The thermoplastic resins can be used alone or in combination of two or more.

[0043] Specific examples of (D) phenoxy resins include FX280 and FX293 manufactured by Nippon Steel Chemical & Material Co., Ltd., and YX8100, YX6954, YL6954, and YL6974 manufactured by Mitsubishi Chemical Corporation. Specific examples of polyvinyl acetal resins include the S-LEC KS series manufactured by Sekisui Chemical Co., Ltd., and specific examples of polyamide resins include the BP series manufactured by Nippon Kayaku Co., Ltd.

[0044] The blending amount of (D) phenoxy resin is preferably 0.5 to 30 mass %, more preferably 0.5 to 20 mass %, based on the total solid content of the epoxy resin in the curable resin composition. When the blending amount of (D) phenoxy resin is within the above range, excellent film formability is obtained, which is preferred.

[0045] <(E) Solvent> The curable resin composition of the present invention may further contain (E) solvent. In the curable resin composition of the present invention, the (E) solvent can function as a dispersion medium for the (C) powder. In addition, in the curable resin composition of the present invention, the solvent can function as a dilution solvent for adjusting the viscosity of the composition when used in combination with the (A) component and the (B) component.

[0046] Examples of the (E) solvent include organic solvents such as ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as methyl cellosolve, butyl cellosolve, methyl carbitol, ethyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, and acetate esters of the above glycol ethers; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. These can be used alone or in combination of two or more.

[0047] <Curing Accelerator> The curable resin composition of the present invention may contain a curing accelerator for accelerating the curing of the above-described components (A) and (B). Examples of the curing accelerator include known curing agents commonly used to cure thermosetting resins, such as amines, imidazoles, polyfunctional phenols, acid anhydrides, isocyanates, and polymers containing these functional groups. A plurality of these may be used as needed. Examples of amines include dicyandiamide and diaminodiphenylmethane. Examples of imidazoles include alkyl-substituted imidazoles and benzimidazoles. The imidazole compound may also be an imidazole latent curing agent, such as an imidazole adduct. Examples of polyfunctional phenols include hydroquinone, resorcinol, bisphenol A and its halogen compounds, as well as novolaks and resol resins, which are condensates of bisphenol A and aldehydes. Examples of acid anhydrides include phthalic anhydride, hexahydrophthalic anhydride, methylnadic anhydride, and benzophenonetetracarboxylic acid. Examples of isocyanates include tolylene diisocyanate and isophorone diisocyanate, and these isocyanates may be masked with phenols, etc. These curing agents may be used alone or in combination of two or more.

[0048] Among the above-mentioned curing accelerators, amines and imidazoles can be preferably used from the viewpoints of adhesion to the conductive part and the insulating part, storage stability, and heat resistance. Preferred are those containing as the main component an adduct compound of an aliphatic polyamine such as an alkylenediamine having 2 to 6 carbon atoms, a polyalkylenepolyamine having 2 to 6 carbon atoms, or an aromatic ring-containing aliphatic polyamine having 8 to 15 carbon atoms, or an adduct compound of an alicyclic polyamine such as isophoronediamine or 1,3-bis(aminomethyl)cyclohexane, or a mixture of the above-mentioned adduct compound of an aliphatic polyamine and the above-mentioned adduct compound of an alicyclic polyamine.

[0049] The adduct compounds of the aliphatic polyamines are preferably those obtained by addition reaction of the aliphatic polyamines with aryl glycidyl ethers (particularly phenyl glycidyl ether or tolyl glycidyl ether) or alkyl glycidyl ethers, and the adduct compounds of the alicyclic polyamines are preferably those obtained by addition reaction of the alicyclic polyamines with n-butyl glycidyl ether, bisphenol A diglycidyl ether, or the like.

[0050] Examples of aliphatic polyamines include alkylenediamines having 2 to 6 carbon atoms, such as ethylenediamine and propylenediamine, polyalkylenepolyamines having 2 to 6 carbon atoms, such as diethylenetriamine and triethylenetriamine, and aromatic ring-containing aliphatic polyamines having 8 to 15 carbon atoms, such as xylylenediamine. Examples of commercially available modified aliphatic polyamines include Fujicure FXE-1000, Fujicure FXR-1020, Fujicure FXR-1030, Fujicure FXR-1080, and Fujicure FXR-1090M2 (manufactured by Fuji Chemical Industry Co., Ltd.), Ancamine 2089K, Sanmaid P-117, Sanmaid X-4150, Ancamine 2422, Surwet R, Sanmaid TX-3000, and Sanmaid A-100 (manufactured by Air Products Japan Co., Ltd.).

[0051] Examples of alicyclic polyamines include isophoronediamine, 1,3-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, 1,2-diaminocyclohexane, and laromine. Commercially available modified alicyclic polyamines include, for example, Ancamine 1618, Ancamine 2074, Ancamine 2596, Ancamine 2199, Sunmaid IM-544, Sunmaid I-544, Ancamine 2075, Ancamine 2280, Ancamine 1934, and Ancamine 2228 (manufactured by Air Products Japan Co., Ltd.), Daitoclar F-5197 and Daitoclar B-1616 (manufactured by Daito Sangyo Co., Ltd.), Fujicure FXD-821 and Fujicure 4233 (manufactured by Fuji Chemical Industry Co., Ltd.), jER Cure 113 (manufactured by Mitsubishi Chemical Corporation), and Laromin C-260 (manufactured by BASF Japan Ltd.). Other examples of polyamine curing agents include EH-5015S (manufactured by ADEKA Corporation).

[0052] The imidazoles include, for example, reaction products of epoxy resins and imidazole, etc. Examples include 2-methylimidazole, 4-methyl-2-ethylimidazole, 2-phenylimidazole, 4-methyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and 1-cyanoethyl-2-undecylimidazole. Commercially available imidazole compounds include imidazoles such as 2E4MZ, C11Z, C17Z, and 2PZ, imidazole azine compounds such as 2MZ-A and 2E4MZ-A, imidazole isocyanurates such as 2MZ-OK and 2PZ-OK, and imidazole hydroxymethyl compounds such as 2PHZ and 2P4MHZ (all manufactured by Shikoku Chemical Industry Co., Ltd.). Commercially available imidazole-type latent curing agents include Curesol P-0505 (manufactured by Shikoku Chemical Industry Co., Ltd.).

[0053] The amount of the curing accelerator blended is preferably 0.4% by mass or more and 2.5% by mass or less in terms of solid content based on the total mass of the composition.

[0054] The curable resin composition of the present invention may further contain, as necessary, an oxazine compound having an oxazine ring obtained by reacting a phenol compound, formalin, and a primary amine. By containing the oxazine compound, when the curable resin composition filled in the holes of a printed wiring board or electronic component is cured and then electroless plating is performed on the resulting cured product, roughening of the cured product with an aqueous potassium permanganate solution or the like can be facilitated, and peel strength from the plating can be improved.

[0055] The curable resin composition of the present invention may also contain known colorants such as phthalocyanine blue, phthalocyanine green, disazo yellow, titanium oxide, carbon black, and naphthalene black.

[0056] In addition, known thermal polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, tert-butylcatechol, pyrogallol, and phenothiazine can be added to impart storage stability during storage, and known thickeners and thixotropic agents such as clay, kaolin, organic bentonite, and montmorillonite can be added to adjust viscosity. Other known additives that can be added include silicone-based, fluorine-based, and polymer-based antifoaming agents, leveling agents, and adhesion promoters such as imidazole-based, thiazole-based, triazole-based, and silane coupling agents. Organic bentonite is particularly preferred because it tends to form protruding portions that protrude from the hole surface and are easily polished and removed, resulting in excellent polishability.

[0057] In consideration of coatability (printability), the viscosity of the curable resin composition of the present invention is preferably 0.01 to 10 Pa s, and more preferably 0.1 to 5 Pa s. The viscosity of the curable resin composition can be adjusted by the amount of the above-mentioned (E) solvent, the type and amount of the (C) powder, etc.

[0058] [Dry Film] The dry film of the present invention comprises a first film and a resin layer obtained from the curable resin composition formed on the first film. The first film in the dry film of the present invention refers to a film that is adhered to at least the resin layer when the dry film is integrally molded by laminating the dry film onto a substrate or other base material by heating or the like so that the resin layer obtained from the curable resin composition formed on the dry film contacts the first film. The first film may be peeled from the resin layer in a step after lamination.

[0059] The dry film of the present invention is obtained by applying the above-mentioned curable resin composition onto a first film and drying the applied composition to obtain a dry film containing a resin layer.

[0060] In one embodiment of the present invention, a method for producing a dry film includes the following steps: applying a curable resin composition to one surface of a first film; and drying the applied curable resin composition to form a resin layer on one surface of the first film.

[0061] Specifically, the dry film is produced by diluting the curable resin composition of the present invention with an organic solvent to adjust the viscosity to an appropriate level, applying the resulting solution to a uniform thickness onto a first film using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, or the like, and drying the resulting solution for 1 to 30 minutes at a temperature of 50 to 130° C. There are no particular restrictions on the thickness of the applied film, but the thickness after drying is generally selected appropriately from the range of 1 to 150 μm, preferably 5 to 80 μm.

[0062] The amount of residual solvent in the resin layer is preferably 0.5 to 7.0% by mass. When the residual solvent is 7.0% by mass or less, bumping during thermal curing is suppressed, resulting in better surface flatness. Furthermore, excessively low melt viscosity that causes the resin component to flow can be suppressed, resulting in better flatness. When the residual solvent is 0.5% by mass or more, the flowability during lamination is good, resulting in better flatness and filling properties.

[0063] The first film can be any known film without particular limitation, and examples of suitable films include polyester films such as polyethylene terephthalate and polyethylene naphthalate, and films made of thermoplastic resins such as polyimide films, polyamideimide films, polypropylene films, and polystyrene films. Among these, polyester films are preferred from the viewpoints of heat resistance, mechanical strength, ease of handling, etc. A laminate of these films can also be used as the first film.

[0064] From the viewpoint of improving mechanical strength, the thermoplastic resin film as described above is preferably a film stretched in a uniaxial or biaxial direction.

[0065] The thickness of the first film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0066] After forming a resin layer of the curable resin composition of the present invention on the first film, it is preferable to further laminate a peelable second film on the surface of the resin layer for the purpose of preventing dust from adhering to the surface of the resin layer, etc. The second film in the dry film manufacturing method of the present invention refers to a film that is peeled from the resin layer before lamination when the dry film is laminated by heating or the like so that the resin layer side of the dry film is in contact with a base material such as a substrate to be integrally molded.

[0067] The second film that can be peeled off from the resin layer may be, for example, a polyethylene film, a polytetrafluoroethylene film, a polypropylene film, or surface-treated paper, as long as the adhesive strength between the resin layer and the second film is smaller than the adhesive strength between the resin layer and the first film when the second film is peeled off.

[0068] The thickness of the second film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0069] [Cured Product] The cured product of the present invention is obtained by curing the above-mentioned curable resin composition or the resin layer of the above-mentioned dry film. For example, it can be produced as follows.

[0070] The curable resin composition described above is applied to a substrate and dried to form a resin layer. When a dry film is used, the resin layer is formed on the substrate by laminating it onto the substrate using a laminator or the like so that the resin layer comes into contact with the substrate. The resin layer formed on the substrate is then thermally cured at a temperature of 80 to 250°C for 30 to 120 minutes to obtain a cured product.

[0071] The method for applying the curable resin composition onto the substrate is not particularly limited, and methods such as dip coating, flow coating, roll coating, bar coating, screen printing, curtain coating, etc. can be used. Thereafter, the organic solvent contained in the composition is evaporated and dried (pre-dried) at a temperature of 60 to 180°C to form a tack-free resin layer.

[0072] The method for laminating the dry film onto the substrate is not particularly limited, but is preferably carried out under pressure and heat using a vacuum laminator or the like. By using a vacuum laminator, even if a circuit-formed substrate is used and the circuit substrate surface is uneven, the dry film adheres to the circuit substrate, preventing the inclusion of air bubbles and improving the filling of recesses in the substrate surface. The pressure condition is preferably about 0.1 to 2.0 MPa, and the heating condition is preferably 40 to 120°C.

[0073] The substrate on which the resin layer is formed is not particularly limited, and examples thereof include printed wiring boards and flexible printed wiring boards on which circuits have been formed in advance using copper or the like, as well as copper-clad laminates for high-frequency circuits made of materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluororesin / polyethylene / polyphenylene ether, polyphenylene oxide / cyanate, and the like, including copper-clad laminates of all grades (FR-4, etc.), as well as metal substrates, polyimide films, cycloolefin polymer films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer plates, etc.

[0074] The cured product of the present invention has a volume resistivity of 1×10 ６ Although the cured product of the present invention contains the powder (C) having a low resistance of Ω cm or less, it has excellent insulating properties. ６ It has a resistance of Ω or more.

[0075] Furthermore, the cured product of the present invention is suppressed from warping due to cure shrinkage. Specifically, the amount of warping of the cured product of the present invention is less than 15 mm.

[0076] [Electronic Components] The electronic components of the present invention have a cured product obtained from the curable resin composition or the resin layer of the dry film of the present invention. For example, they can be used for manufacturing electronic components such as printed wiring boards. They are preferably used as a component of an inductor, and more preferably used to form a protective film for an inductor.

[0077] As described above, the curable resin composition of the present invention uses (A) a dicyclopentadiene-type epoxy resin, and therefore has a volume resistivity of 1×10 ６Despite containing (C) powder with a low resistivity of Ω cm or less, a cured product with excellent insulating properties can be obtained. Furthermore, the curable resin composition of the present invention can obtain a cured product in which warping due to cure shrinkage is suppressed by using (A) a dicyclopentadiene-type epoxy resin in combination with (B) an epoxy resin having an epoxy equivalent in the range of 200 to 1,000 (excluding the (A) dicyclopentadiene-type epoxy resin).

[0078] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" and "%" are all by mass unless otherwise specified.

[0079] <Preparation of Curable Resin Compositions> The components shown in Table 1 below were blended and mixed at room temperature using a three-roll mill to obtain the curable resin compositions shown in the same table. Note that each value in the table indicates parts by mass.

[0080] The components in Table 1 below are as follows: Dicyclopentadiene-type epoxy resin: HP-7200H, manufactured by DIC Corporation (epoxy equivalent: 278 [g / eq], weight-average molecular weight (Mw): 2400, number of functional groups: 2 or more, specific gravity: 1.2) Biphenyl-type epoxy resin: NC-3000H, manufactured by Nippon Kayaku Co., Ltd. (epoxy equivalent: 289 [g / eq], weight-average molecular weight (Mw): 2070, number of functional groups: 3 or more, specific gravity: 1.0) Propylene glycol-based epoxy resin: EP-4010L, manufactured by ADEKA Corporation (epoxy equivalent: 350 [g / eq], viscosity: 507 [Ps], number of functional groups: 2, specific gravity: 1.1) Polyether-based epoxy resin: jER, manufactured by Mitsubishi Chemical Corporation YX7400N (epoxy equivalent: 445 [g / eq], viscosity: 2.1 [Ps], number of functional groups: 2, specific gravity: 1.0) Bisphenol A type epoxy resin: Mitsubishi Chemical Corporation, jER-828 (epoxy equivalent: 189 [g / eq], viscosity: 130 [Ps], number of functional groups: 2, specific gravity: 1.2) Flexible skeleton epoxy resin: Mitsubishi Chemical Corporation, jER YX7110B80 (epoxy equivalent: 1004 [g / eq], viscosity: - [Ps], number of functional groups: 2, specific gravity: 1.2, solid content: 80% by mass) Powder A: Powder Tech Co., Ltd., M03S (volume resistivity: 1.1 × 10 ５ [Ω cm], specific gravity 4.8) Powder B: Powder Tech Co., Ltd., NZ03S (volume resistivity: 3.6 × 10 ５ [Ω cm], specific gravity 6.0) Phenoxy resin: YX-6954BH30 (specific gravity 1.2, solid content 30 mass%) manufactured by Mitsubishi Chemical Corporation Solvent: Cyclohexanone manufactured by Taishin Chemical Co., Ltd. Phenolic resin: HF-1M (specific gravity 1.3) manufactured by UBE Corporation Curing accelerator: 2E4MZ (specific gravity 1.0) manufactured by Shikoku Chemical Industry Co., Ltd.

[0081]

[0082] <Method for Measuring Powder Volume Resistivity> (Apparatus) - Powder Resistivity Measurement System MCP-PD51 Model, manufactured by Nitto Seiko Analytech Co., Ltd. - Low Resistivity Meter Loresta-GP, manufactured by Nitto Seiko Analytech Co., Ltd. - Low Resistivity Probe for Powder MCP-PD511 (Constant Current Application Method, Four-Probe Method), manufactured by Nitto Seiko Analytech Co., Ltd. (Measurement Conditions) - Target Load: 20 kN (Measurement Procedure) 1.0 g of each powder was weighed and introduced into a powder resistivity measurement probe unit (radius 10.0 mm), and the sample was gradually pressurized using the attached hydraulic pump. After the target load was reached, measurements were performed using the low resistivity meter Loresta-GP. The electrode distance was 3 mm.

[0083] <Preparation of Dry Film> The curable resin compositions of Examples 1 to 4 and Comparative Examples 1 to 3 obtained as described above were applied to a 38 μm thick polyester film (TN200, manufactured by Toyobo Co., Ltd.) using a K303 multicoater (manufactured by Matsuo Sangyo Co., Ltd.) to a thickness of 65 to 85 μm to form a curable resin composition layer. The film was then dried so that the residual solvent amount was 1.0 to 2.0 mass %, thereby preparing dry films of Examples 1 to 4 and Comparative Examples 1 to 3, each having a resin layer on one side of the first film.

[0084] <Evaluation of Insulation Properties> The dry films prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were laminated onto a printed wiring board measuring 150 mm x 95 mm and 1 mm thick, on which a comb-tooth pattern circuit with a copper thickness of 15 μm and an L / S (line width / line spacing) of 12 μm / 13 μm was formed (core substrate: MCL-E-679FG(R) (manufactured by Resonac Inc.), interlayer insulating material: GX92 (manufactured by Ajinomoto Fine-Techno Co., Ltd.), number of electrodes: 10 on each side, totaling 20, length of comb-shaped electrode portion: 10 mm, pretreatment: acid washing), using a two-chamber vacuum laminator CVP-300 (manufactured by Nikko Materials Co., Ltd.) under processing conditions of a temperature of 60°C, a pressure of 0.5 MPa, a vacuum holding time of 30 seconds, and a pressure time of 30 seconds. The substrate was then pressed at 60°C for 60 seconds, and then heat-treated at 100°C for 30 minutes, and then at 170°C for 30 minutes to cure the resin layer and form a cured product. Next, the polyethylene film was peeled off from the cured product, and the substrate was placed in a highly accelerated life tester (PC-422R8D, manufactured by Hirayama Manufacturing Co., Ltd.), and a voltage of 2 V was applied using an insulation degradation evaluation tester (MIG-8600B, manufactured by IMV Corporation) in an environment of 130°C and 85% RH, and the resistance value after 100 hours was measured. The insulation evaluation criteria were as follows. The results are shown in Table 2. (Evaluation criteria) ○: Resistance value was 1.0 x 10 ６ Ω or more ×: Resistance value is 1.0 × 10 ６ Less than Ω

[0085] <Warpage Evaluation> First, a 4 cm square piece of the dry film prepared in <Dry Film Preparation> was cut out and attached to the center of the shine side of an 18 μm thick copper foil cut into a 5 cm square piece, with the resin layer of the dry film in contact. Next, using a vacuum laminator MVLP-500 (manufactured by Meiki Seisakusho Co., Ltd.), lamination was performed under pressure conditions of a temperature of 60°C, a pressure of 0.5 MPa, a vacuum retention time of 14 seconds, and a pressure time of 30 seconds. The resin layer was then cured by heat treatment at 100°C for 30 minutes and then at 170°C for 30 minutes, forming a cured product in the center of the copper foil. Next, the polyester film was peeled off from the cured product, and the copper foil was placed on a flat wooden desk with the cured product facing upward. The distances from the plane to the four corners of the copper foil were measured, and the maximum value was taken as the amount of warpage. The warpage evaluation criteria were as follows. The results are shown in Table 2. (Evaluation criteria) ⊚: Warpage less than 13 mm ◯: Warpage 13 mm or more but less than 15 mm ×: Warpage 15 mm or more

[0086]

[0087] As shown in Table 2, the curable resin compositions of Examples 1 to 4 all contained a dicyclopentadiene-type epoxy resin, and therefore had a volume resistivity of 1.0 × 10 ６ Although the cured product contains powder A or powder B, the resistance of the cured product is 1.0 × 10 ６ Ω or more, demonstrating excellent insulating properties. Furthermore, the curable resin compositions of Examples 1 to 4 used an epoxy resin with an epoxy equivalent ranging from 200 to 1,000 as the epoxy resin used in combination with the dicyclopentadiene-type epoxy resin, and therefore were able to confirm that the amount of warpage of the cured product was suppressed. Furthermore, Examples 1 and 2 used a propylene glycol-skeleton epoxy resin as the epoxy resin used in combination with the dicyclopentadiene-type epoxy resin, and therefore were able to confirm that the amount of warpage was suppressed more than in Examples 3 and 4.

[0088] In contrast, the curable resin composition of Comparative Example 1 does not contain a dicyclopentadiene-type epoxy resin, and therefore the resistance value of the cured product is 1.0×10 ６The curable resin composition of Comparative Example 2 contains a dicyclopentadiene-type epoxy resin, but the epoxy equivalent of the epoxy resin used in combination with the dicyclopentadiene-type epoxy resin is less than 200, so the amount of warpage of the cured product could not be suppressed. The curable resin composition of Comparative Example 3 contains a dicyclopentadiene-type epoxy resin, but the epoxy equivalent of the epoxy resin used in combination with the dicyclopentadiene-type epoxy resin is more than 1,000, so the resistance value of the cured product was less than 1.0 × 10 ６ The hardness was less than Ω, and the amount of warping of the cured product could not be suppressed.

Claims

1. (A) dicyclopentadiene-type epoxy resin, (B) epoxy resin (excluding the dicyclopentadiene-type epoxy resin (A)), and (C) epoxy resin having a volume resistivity of 1 x 10 ６ a curable resin composition comprising at least a powder having a viscosity of Ω cm or less, and wherein the epoxy equivalent of the epoxy resin (B) is in the range of 200 to 1000.

2. The curable resin composition according to claim 1, wherein the dicyclopentadiene-type epoxy resin (A) is a solid epoxy resin.

3. (C) The volume resistivity is 1×10 ６ The curable resin composition according to claim 1 , wherein the powder having a resistivity of Ω·cm or less is a magnetic powder.

4. The curable resin composition according to claim 1, wherein the epoxy equivalent of the epoxy resin (B) is in the range of 200 to 700.

5. The curable resin composition according to claim 1, wherein the epoxy equivalent of the epoxy resin (B) is in the range of 200 to 500.

6. The curable resin composition according to claim 1, further comprising (D) a phenoxy resin.

7. The curable resin composition according to claim 1, further comprising (E) a solvent.

8. The curable resin composition according to claim 1, wherein the epoxy resin (B) comprises an epoxy resin having a propylene glycol skeleton.

9. A dry film comprising: a first film; and a resin layer made of the curable resin composition according to claim 1 provided on at least one surface of the first film.

10. A cured product obtained by curing the curable resin composition according to claim 1.

11. A cured product obtained by curing the resin layer of the dry film according to claim 9.

12. An electronic component comprising the cured product according to claim 10 or 11.

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