KR20230156726A - Curable Resin Composition - Google Patents

Abstract

[Problem] A curable resin composition that can be suitably used as a paste that can be applied or filled on a printed wiring board with a high degree of freedom in forming wiring, enabling the formation of a coating film without deviation, and producing a cured product that is stable over time and has a high relative permeability. The curable resin composition obtained is provided. [Solution] A curable resin composition comprising a thermosetting resin, a curing agent, a magnetic powder, and a diluting component, wherein the thermosetting resin has a 5% weight loss temperature of more than 180°C by thermogravimetric analysis, and the diluting component It is a curable resin composition characterized by a 5% weight loss temperature of 50°C or higher and 180°C or lower according to thermogravimetric analysis.

Description

Curable Resin Composition

The present invention relates to a curable resin composition that can be used as a filler for filling through holes or recesses such as through holes in printed wiring boards.

In response to recent demands for miniaturization and higher functionality for electronic devices, further multilayering and higher density are being demanded in the field of wiring boards as well. For example, a wiring board on which a plurality of circuit elements such as a power supply circuit, a high-frequency circuit, and a digital circuit are mounted on one board has also been proposed.

In a board on which such a plurality of circuit elements are mounted, noise generated from each circuit element affects adjacent circuit elements, so each circuit element must be mounted at a certain interval or a shield must be installed between each circuit element. You need to install it. Therefore, it is difficult to miniaturize and increase the density of a board on which a plurality of circuit elements are mounted.

Regarding the above problem, for example, in Patent Document 1, there is a case where a plurality of circuit elements are mounted on a multilayer wiring board by providing a magnetic material layer between each board or filling through vias with a magnetic material. Even so, a device that can reduce noise while being small and at low cost has been proposed. Additionally, Patent Document 2 proposes filling through holes and via holes with a conductive paste containing a magnetic filler for electrical interlayer connection in a multilayer wiring board.

Meanwhile, as printed wiring boards become more functional, frequency characteristics are being improved by removing excess portions of the plating film on the walls of through holes and via holes that are not related to interlayer conduction. For example, Patent Document 3 proposes a printed wiring board having a hole section in which a through hole or via hole is excavated halfway through a method called a backdrill method.

J.P. 2017-017175 A J.P. 2001-203463 A J.P. 2007-509487 A

In inductor elements for high frequency bands, a high Q value is required as a characteristic. The Q value can be improved by increasing the relative permeability (μ') of the insulating layer constituting the high frequency inductor element. Accordingly, there is a demand for a material capable of increasing the relative magnetic permeability of the insulating layer. In addition, as devices become smaller and more dense, the formation of coating films and the ability to fill small diameters and narrow gaps are required, and the demand for paste-type magnetic materials is also increasing.

In response to the above request, it is thought that the content of magnetic powder in the paste-type magnetic material should be increased in order to achieve a relative magnetic permeability close to that of the bulk magnetic material. However, as the content of magnetic powder increases, it becomes difficult to form a coating film without deviation. In particular, in paste-type magnetic materials containing a large amount of magnetic powder, the viscosity tends to change over time, making it difficult to form a coating film without variation. In addition, the relative permeability changed over time even after the coating film was formed, making it difficult to form a stable coating film with a constant relative permeability.

Therefore, the object of the present invention is a curable resin composition that can be suitably used as a paste that can be applied or filled on a printed wiring board with a high degree of freedom in forming wiring, and is capable of forming a coating film without variation, which is stable over time and has a high relative magnetic permeability. To provide a curable resin composition from which a cured product having a is obtained.

The present inventors investigated the reason why it is difficult to form a coating film without variation in paste-type magnetic materials and why the relative magnetic permeability changes over time. As a result, the components in the paste-type magnetic material volatilize above a certain level even at room temperature, causing changes over time. It was discovered that the viscosity changes, making it difficult to form a coating film without variation. In addition, it has been found that even after formation of a coating film, the relative permeability changes due to volatilization of specific components over time. The present invention is based on this knowledge. That is, the gist of the present invention is as follows.

[1] A curable resin composition comprising a thermosetting resin, a curing agent, magnetic powder, and a diluting component,

The thermosetting resin has a 5% weight loss temperature of more than 180°C according to thermogravimetric analysis,

The diluting component is a curable resin composition, characterized in that the 5% weight loss temperature according to thermogravimetric analysis is 50°C or more and 180°C or less.

[2] The curable resin composition according to [1], wherein the diluting component is contained in an amount of 30% by mass or less relative to the total amount of the thermosetting resin and the diluting component.

[3] The curable resin composition according to [1] or [2], wherein the thermosetting resin is in a liquid form.

[4] The curable resin composition according to any one of [1] to [3], wherein the thermosetting resin includes an epoxy resin having a viscosity of 1 Pa·s or less.

[5] The curable resin composition according to [4], comprising 35% by mass or more of the epoxy resin relative to the total thermosetting resin.

[6] The curable resin composition according to any one of [1] to [5], which is used as a filler for through holes or recesses of a printed wiring board.

According to the present invention, in a curable resin composition comprising a thermosetting resin, a curing agent, and magnetic powder, a thermosetting resin having a 5% weight loss temperature exceeding 180°C by thermogravimetric analysis, and a 5% weight loss temperature by thermogravimetric analysis. By including a dilution component with a temperature of 50°C or higher and 180°C or lower, it is possible to form a coating film without variation, and a curable resin composition that is stable over time and has a high relative magnetic permeability can be obtained, which can be used for wiring. It can be suitably used as a paste that can be applied or filled on printed wiring boards with a high degree of freedom of formation. Additionally, it can be suitably used as an insulating material for high-frequency inductor elements that require high relative magnetic permeability in the range of 10 MHz to 200 MHz.

<Curable resin composition>

The curable resin composition of the present invention contains a thermosetting resin, a curing agent, magnetic powder, and a diluting component as essential components. In addition, in this specification, “liquid state” shall refer to being in a liquid state or semi-liquid state (paste state) having fluidity at at least one of 20°C and 40°C. Below, each component is described in detail.

[Thermosetting resin]

As the thermosetting resin contained in the curable resin composition according to the present invention, any compound that can be cured by heat can be used without particular limitation as long as the 5% weight loss temperature according to thermogravimetric analysis is greater than 180°C. A more preferred 5% weight loss temperature is greater than 200°C. In addition, in this specification, "5% weight loss temperature by thermogravimetric analysis" refers to a differential calorimetric gravimetry device (e.g., TG/DTA6200, Hitachi High-Tech Science Corporation, TGA5500, TA Instruments Japan Inc., etc.) ), the weight of the sample was placed in an aluminum pan (non-airtight) under an air atmosphere, and the temperature was raised from 20°C to 500°C at a temperature increase rate of 10°C/min. The weight of the sample was, It refers to the temperature at which the weight is reduced by 5% compared to the sample weight before heating. In addition, when the thermosetting resin is diluted with a solvent, etc., the weight loss temperature of the thermosetting resin alone excluding the solvent is measured.

Thermosetting resins include triazine rings such as isocyanate compounds, block isocyanate compounds, amino resins, carbodiimide resins, cyclocarbonate compounds, epoxy resins, oxetane compounds, episulfide resins, urea resins, and melamine resins. Resins having, unsaturated polyester resins, maleimide resins such as bismaleimide compounds, polyurethane resins, diaryl phthalate resins, benzoxazine resins, polyimide resins, polyamidoimide resins, benzocyclobutene resins, novolac type Cyanate resin, cyanate ester resin such as bisphenol type cyanate resin such as bisphenol A type cyanate resin, bisphenol E type cyanate resin, tetramethylbisphenol F type cyanate resin, silicone resin, etc. Known One example is tolerance. These can be used individually or in combination of two or more types. Among these, epoxy resin is preferable.

The epoxy resin can be used without limitation as long as it has two or more epoxy groups per molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E (AD) type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy. Epoxy resins having a bisphenol-type skeleton such as resins, phenol novolak-type epoxy resins described later, cresol novolak-type epoxy resins, bisphenol A novolak-type epoxy resins, biphenyl-type epoxy resins, naphthol-type epoxy resins, naphthalene-type epoxy resins. Resin, dicyclopentadiene type epoxy resin, triphenylmethane type epoxy resin, aliphatic epoxy resin, phosphorus-containing epoxy resin, anthracene type epoxy resin, norbornene type epoxy resin, adamantane type epoxy resin, fluorene type epoxy resin. , aminophenol-type epoxy resin, aminocresol-type epoxy resin, and alkylphenol-type epoxy resin described later. The above-mentioned epoxy resins can be used alone or in combination of two or more types. Among these, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol E (AD) type epoxy resin are preferable. Additionally, the epoxy resin having a bisphenol-type skeleton may be liquid, semi-solid, or solid, but is preferably liquid from the viewpoint of fillability.

It is preferable to use two types of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin in combination. As these commercially available products, NIPPON STEEL Chemical & Material Co., Ltd. Product ZX-1059 (mixture of bisphenol A type and bisphenol F type epoxy resin) or jER 828, jER 834, jER 1001 (bisphenol A type epoxy resin), jER 807, jER 4004P (bisphenol F type epoxy resin) manufactured by Mitsubishi Chemical Corporation. , AIR WATER INC. Products such as R710 (bisphenol E type epoxy resin) can be mentioned.

Additionally, the curable resin composition of the present invention may contain a multifunctional epoxy resin as a thermosetting resin. Multifunctional epoxy resins include EP-3300E from ADEKA Corporation, a hydroxybenzophenone type liquid epoxy resin, jER 630 from Mitsubishi Chemical Corporation, and SUMITOMO CHEMICAL COMPANY, which are aminophenol type liquid epoxy resins (para-aminophenol type liquid epoxy resins). , ELM-100, a LIMITED product, jER 604, a glycidylamine-type epoxy resin manufactured by Mitsubishi Chemical Corporation, and NIPPON STEEL Chemical & Material Co., Ltd. Epotote YH-434, a SUMITOMO CHEMICAL COMPANY, LIMITED product, SUMI-EPOXY ELM-120, a phenol novolac type epoxy resin, D.E.N., a Dow Chemical Japan Limited product. 431, etc. These multifunctional epoxy resins can be used one type or in combination of two or more types.

In the present invention, the thermosetting resin is preferably in a liquid form rather than a solid form from the viewpoint of coating film formation of the curable resin composition, that is, coating properties such as printability. In particular, from the viewpoint of printability and fillability, the thermosetting resin preferably has a viscosity of 5 Pa·s or less at 25°C, more preferably 3 Pa·s or less, and still more preferably 1 Pa·s or less.

The blending amount of the above-mentioned thermosetting resin is preferably 3% by mass or more and 25% by mass or less, and more preferably 5% by mass or more and 15% by mass or less with respect to the entire composition.

In addition, as a thermosetting resin having a 5% weight loss temperature exceeding 180°C according to the thermogravimetric analysis described above, it is preferable to contain an epoxy resin having a viscosity of 1 Pa·s or less at 25°C. By containing such a low-viscosity epoxy resin, magnetic powder and other fillers can be highly filled and the viscosity of the curable resin composition can be lowered, thereby improving printability and, when applied to a printed wiring board, improving wiring formation. The degree of freedom can be increased. In addition, in this specification, viscosity means the viscosity measured based on JIS Z 8803:2011 10 "Viscosity measurement method using a cone-plate rotational viscometer", and specifically, a cone plate type viscometer (TVE) -33H, manufactured by Toki Sangyo Co., Ltd.), and for liquid materials with a viscosity of less than 10 Pa·s, a cone rotor of 3° It refers to the value measured under the conditions of 25°C, 5.0rpm, and 30 seconds using a cone/rotor of °×R9.7.

The amount of the epoxy resin with a viscosity of 1 Pa·s or less is preferably 35% by mass or more, and more preferably 60% by mass, based on the total thermosetting resin with a 5% weight loss temperature of more than 180°C by thermogravimetric analysis.

[Dilution ingredients]

The curable resin composition according to the present invention includes a dilution component that has a 5% weight loss temperature of 50°C or more and 180°C or less according to thermogravimetric analysis. By including such a dilution component, it is possible to form a coating film without variation, and a curable resin composition can be obtained that is stable over time and has a high relative magnetic permeability. The reason for this is not necessarily clear, but is assumed as follows. That is, the curable resin composition contains a thermosetting resin having a 5% weight loss temperature exceeding 180°C according to the above-mentioned thermogravimetric analysis, and a dilution component having a 5% weight loss temperature of 50°C or more and 180°C or less according to thermogravimetric analysis. By doing so, it is difficult for the components in the curable resin composition to volatilize under a room temperature environment such as when forming a coating film, and thus a rapid change in viscosity over time is suppressed. As a result, the applicability (printability) of the curable resin composition improves, and it becomes easier to form a coating film with a consistent film thickness. In addition, since the change in viscosity until the curing of the curable resin composition is small even after forming the coating film, agglomeration or precipitation of the magnetic powder is suppressed, so the coating has a stable relative permeability that does not decrease over time. It is believed that the cargo is obtained. Additionally, when the curable resin composition is cured (i.e., when heated), most of the diluted components volatilize and shrink, so it is believed that the magnetic powder ratio per volume in the cured product increases and the relative magnetic permeability improves. However, the above-described mechanism of action is entirely speculative and is not necessarily limited to this.

From the viewpoint of uniformity and relative magnetic permeability of the coating film, the 5% weight loss temperature determined by thermogravimetric analysis of the diluted component is preferably 60°C or higher and 160°C or lower, more preferably 70°C or higher and 150°C or lower, and 80°C. Above, 140°C or lower is more preferable.

Examples of diluting components with a 5% weight loss temperature of 50°C or higher and 180°C or lower according to thermogravimetric analysis include alicyclic epoxy resins such as LDO and low molecular weight glycidyl ether type epoxy resins, For example, butyl glycidyl ether, ethylhexyl glycidyl ether, aryl glycidyl ether, etc. can be used. Additionally, organic solvents such as ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum solvents, etc. can also be used. These diluting components may be used individually or as a mixture of two or more types.

The above-mentioned diluting components do not necessarily have to be all volatilized during curing of the curable resin composition, and some of them may act as one component during the curing reaction together with the thermosetting resin. For example, when an alicyclic epoxy resin such as LDO is used as a diluting component, curing shrinkage increases, and the relative magnetic permeability of the cured product can be significantly improved. In addition, by using a compound having the same functional group as the reactive functional group of the thermosetting resin as a diluting component, affinity with the thermosetting resin is improved and viscosity changes in the curable resin composition can be suppressed, thereby forming a coating film without variation. It gets easier. For example, when the thermosetting resin is an epoxy resin, using LDO, dipropylene glycol methyl ether, diethylene glycol monoethyl ether acetate, etc. as a diluent component has high affinity with the resin component and improves film formation over time. This improves.

The amount of the above-described diluting component is preferably 30% by mass or less relative to the total amount of the thermosetting resin and the diluting component, and is more preferably 5 to 20% by mass from the viewpoint of temporal stability of relative magnetic permeability and film formation.

[Hardener]

The curable resin composition according to the present invention contains a curing agent for curing the thermosetting resin described above. As the curing agent, known curing agents that are generally used for curing thermosetting resins can be used, for example, amines, imidazoles, polyfunctional phenols, acid anhydrides, isocyanates, and those containing these functional groups. There are polymers, and a plurality of them may be used as needed. Amines include dicyandiamide and diaminodiphenylmethane. Examples of imidazole include alkyl-substituted imidazole and benzoimidazole. Additionally, the imidazole compound may be an imidazole latent curing agent such as an imidazole adduct. Examples of multifunctional phenols include hydroquinone, resorcinol, bisphenol A and their halogen compounds, as well as novolac and resol resins, which are condensates thereof with aldehydes. Examples of acid anhydrides include phthalic anhydride, hexahydrophthalic anhydride, methylnadic anhydride, and benzophenone tetracarboxylic acid. Isocyanates include tolylene diisocyanate, isophorone diisocyanate, etc., and this isocyanate masked with phenol or the like may be used. These curing agents may be used individually, or two or more types may be used in combination.

Among the above-mentioned curing agents, amines and imidazoles can be suitably used from the viewpoints of adhesion to the conductive portion and the insulating portion, storage stability, and heat resistance. Adduct compounds of aliphatic polyamines such as alkylenediamines having 2 to 6 carbon atoms, polyalkylene polyamines having 2 to 6 carbon atoms, aromatic ring-containing aliphatic polyamines having 8 to 15 carbon atoms, or isophoronediamine, 1,3-bis It is preferable that the main component is an adduct compound of an alicyclic polyamine such as (aminomethyl)cyclohexane, or a mixture of an adduct compound of the above aliphatic polyamine and an adduct compound of the above alicyclic polyamine.

The adduct compound of the aliphatic polyamine is preferably obtained by adding an aryl glycidyl ether (particularly phenyl glycidyl ether or tolyl glycidyl ether) or an alkyl glycidyl ether to the aliphatic polyamine. Additionally, the adduct compound of the alicyclic polyamine is preferably obtained by addition reaction of n-butylglycidyl ether, bisphenol A diglycidyl ether, etc. to the alicyclic polyamine.

As aliphatic polyamines, alkylene diamines with 2 to 6 carbon atoms such as ethylene diamine and propylene diamine, polyalkylene polyamines with 2 to 6 carbon atoms such as diethylene triamine and triethylene triamine, and 8 to 6 carbon atoms such as xylylene diamine. and aromatic ring-containing aliphatic polyamines of 15. Examples of commercially available modified aliphatic polyamines include, for example, FujiCure FXE-1000 or FujiCure FXR-1020, FujiCure FXR-1030, FujiCure FXR-1080, FujiCure FXR-1090M2 (manufactured by T&K TOKA Corporation), Ancamine 2089K, and Sunmide P-117. , Sunmide

Examples of alicyclic polyamines include isophoronediamine, 1,3-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, norbornediamine, 1,2-diaminocyclohexane, Laromin, etc. You can. Commercially available modified alicyclic polyamines include, for example, Ancamine 1618, Ancamine 2074, Ancamine 2596, Ancamine 2199, Sunmide IM-544, Sunmide I-544, Ancamine 2075, Ancamine 2280, Ancamine 1934, and Ancamine 2228 (Evonik Japan Co. , Ltd. product), DAITOCURAR F-5197, DAITOCURAR B-1616 (DAITO SANGYO CO., LTD. product), Fuji CureFXD-821, Fuji Cure4233 (T&K TOKA Corporation product), jERcure113 (Mitsubishi Chemical Corporation product), Laromin C -260 (product of BASF Japan Ltd.), etc. In addition, examples of polyamine-type curing agents include EH-5015S (made by ADEKA Corporation).

Examples of imidazoles include reaction products of epoxy resins and imidazole. For example, 2-methyl imidazole, 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, 1-cyanoethyl -2-undecylimidazole, etc. can be mentioned. Commercially available imidazole compounds include, for example, imidazoles such as 2E4MZ, C11Z, C17Z, and 2PZ, AZINE compounds of imidazole such as 2MZ-A and 2E4MZ-A, 2MZ-OK, 2PZ-OK, etc. Isocyanurate of imidazole, and imidazole hydroxymethyl forms such as 2PHZ and 2P4MHZ (all manufactured by Shikoku Chemicals Corporation). Examples of commercially available imidazole-type latent curing agents include CUREDUCT P-0505 (manufactured by Shikoku Chemicals Corporation).

The compounding amount of the above-mentioned hardener is preferably 0.4% by mass or more and 2.5% by mass or less in terms of solid content with respect to the entire composition.

[Magnetic powder]

The curable resin composition according to the present invention contains magnetic powder. By including magnetic powder, noise electromagnetic waves in the nearby electromagnetic field can be suppressed or absorbed, so a printed wiring board with excellent noise suppression and other characteristics can be obtained even when a plurality of circuit elements are mounted. Additionally, it can be suitably used as an insulating material for high-frequency inductor elements that require high relative magnetic permeability in the range of 1MHz to 200MHz.

The magnetic powder can be used without particular restrictions, and includes Mg-Zn-based ferrite, Mn-Zn-based ferrite, Mn-Mg-based ferrite, Cu-Zn-based ferrite, Mg-Mn-Sr-based ferrite, and Ni-Zn-based ferrite. Hexagonal ferrites such as spinel-type ferrites, Ba-Zn-based ferrites, Ba-Mg-based ferrites, Ba-Ni-based ferrites, Ba-Co-based ferrites, and Ba-Ni-Co-based ferrites, and garnet-type ferrites such as Y-based ferrites. Non-conductive magnetic materials such as ferrites, pure iron powder, Fe-Si 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, Alternatively, conductive magnetic materials such as Fe alloys such as Fe-Cr-Al alloy powder, Ni alloys, and amorphous alloys such as Fe-based amorphous and Co-based amorphous.

When insulating properties are required for the cured product of the curable resin composition according to the present invention, it is necessary to use non-conductive magnetic powder as the magnetic powder. However, even if it is conductive magnetic powder, the mixing amount must be adjusted or the surface may be made of an insulating inorganic material or By coating with an organic material, non-conductive magnetic powder can be used.

Additionally, as the magnetic powder, a commercially available magnetic filler can be used. As a specific example of a commercially available magnetic filler, Sanyo Special Steel Co., Ltd. Product "PST-S", Epson Atmix Corporation product "AW2-08PF20F", "AW2-08PF10F", "AW2-08PF8F", "AW2-08PF3F", "Fe-3.5Si-4.5CrPF20F", "Fe-50NiPF20F" , “Fe-80Ni-4MoPF20F”, JFE Chemical Corp. Products "LD-M", "LD-MH", "KNI-106", "KNI-106GSM", "KNI-106GS", "KNI-109", "KNI-109GSM", "KNI-109GS", TODA KOGYO CORP. Products "KNS-415", "BSF-547", "BSF-029", "BSN-125", "BSN-714", "BSN-828", Japan Metals & Chemicals Co., Ltd. Product "JR09P2" etc. can be mentioned. One type of magnetic material may be used individually, or two or more types may be used together.

The shape of the magnetic powder is not particularly limited, and examples include spherical shape, needle shape, plate shape, scale shape, hollow shape, irregular shape, hexagonal shape, cubic shape, and flaky shape.

In addition, the average particle size of these magnetic powders is 0.1 ㎛ to 25 ㎛, preferably 0.1 ㎛, taking into account the dispersibility of the magnetic filler, the filling ability in the hole, and the smoothness when the wiring layer is formed in the hole filling portion. A range of from 15 ㎛ to 15㎛ is suitable. In addition, 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.

The above-mentioned magnetic powder is preferably contained in a ratio of 60 to 94 mass%, more preferably in a ratio of 75 to 94 mass%, and even more preferably in a ratio of 85 to 94 mass%, with respect to the entire curable resin composition. By keeping the content of the magnetic filler within the above range, properties such as noise suppression and fillability of the curable resin composition can be achieved at a higher level.

Additionally, from the viewpoint of uniform dispersibility in the curable resin composition, a dispersant may be used together. As a dispersant, phosphoric acid esters, acrylic copolymers, polyamines, polyurethanes, polyesters, polyacrylates, and phosphates and alkyl ammonium salts thereof having an acidic group or a basic group or both can be suitably used. The above-mentioned dispersants may be used individually or may be used in combination of plurality.

[Other ingredients]

The curable resin composition according to the present invention may contain a photocurable resin in combination with the thermosetting resin described above. Examples of the photocurable resin include curable resins that can be cured by radical addition polymerization with active energy rays. Specific examples of the radical addition polymerization reactive component having one or more ethylenically unsaturated groups in the molecule include commonly known polyester (meth)acrylate, polyether (meth)acrylate, and urethane (meth)acrylate. , carbonate (meth)acrylate, epoxy (meth)acrylate, etc. Specifically, diacrylates of glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, and propylene glycol; Acrylamides such as N,N-dimethylacrylamide, N-methylolacrylamide, and N,N-dimethylaminopropylacrylamide; Aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate and N,N-dimethylaminopropyl acrylate; Polyhydric alcohols such as hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tris-hydroxyethyl isocyanurate, or their ethylene oxide adducts, propylene oxide adducts, or ε-caprolactone addition. polyacrylates such as water; Polyacrylates such as phenoxyacrylate, bisphenol A diacrylate, and ethylene oxide or propylene oxide adducts of these phenols; glycerin diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane polyacrylates of glycidyl ether, such as triglycidyl ether and traglycidyl isocyanurate; Not limited to the above, acrylic is obtained by directly acrylating polyols such as polyether polyol, polycarbonate diol, hydroxyl-terminated polybutadiene, and polyester polyol, or urethane acrylate through diisocyanate. At least one type of acrylate, melamine acrylate, and each methacrylate corresponding to the acrylate can be mentioned. In addition, in this specification, (meth)acrylate is a general term for acrylates, methacrylates, and mixtures thereof, and the same applies to other similar expressions. The photocurable resin described above is preferably in a liquid form.

In addition, when promoting a heat curing reaction with an epoxy resin in the curable resin composition of the present invention or when making the composition of the present invention an alkali-developing type curable resin composition, a carboxyl group-containing resin is used as the curable resin. It is desirable. The carboxyl group-containing resin may be a carboxyl group-containing photosensitive resin having an ethylenically unsaturated group, and may have an aromatic ring or not.

When the curable resin composition of the present invention contains a photocurable resin, it is preferable to add a photopolymerization initiator. Examples of this photopolymerization initiator include benzoin compounds and alkyl ethers thereof such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and benzyl methyl ketal; Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, diethoxyacetophenone, 2,2-diethoxy-2 -Phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenylketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one Acetophenones such as; Anthraquinones such as methyl anthraquinone, 2-ethy anthraquinone, 2-tert-buty anthraquinone, 1-chloro anthraquinone, and 2-amy anthraquinone; Thioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 2-methylthioxanthone, 2,4-diisopropylthioxanthone, etc. thioxanthone; Ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; Benzophenones, such as benzophenone and 4,4-bismethylaminobenzophenone, are mentioned. These can be used alone or in combination of two or more types, and include tertiary amines such as triethanolamine and methyldiethanolamine; It can be used in combination with photopolymerization initiator aids such as benzoic acid derivatives such as 2-dimethylaminoethylbenzoic acid and ethyl 4-dimethylaminobenzoate.

In addition, the curable resin composition according to the present invention may contain fillers other than the above-mentioned magnetic powder in order to relieve stress due to curing shrinkage of the composition or to adjust the coefficient of linear expansion, as long as the effect of the present invention is not impaired. The filler is not particularly limited, and conventionally known fillers can be used, for example, silica, barium sulfate, calcium carbonate, silicon nitride, aluminum nitride, boron nitride, aluminum oxide, magnesium oxide, aluminum hydroxide, magnesium hydroxide, and mica. , talc, etc. These fillers may be used individually, or two or more types may be used together.

Among these fillers, calcium carbonate, silica, barium sulfate, and aluminum oxide, which are excellent in low hygroscopicity and low volume expansion, are suitably used, and among them, silica and calcium carbonate are more suitably used. Silica may be amorphous, crystalline, or a mixture thereof. Particularly preferred is amorphous (fused) silica. Additionally, the calcium carbonate may be either natural ground calcium carbonate or synthetic precipitated calcium carbonate.

In order to impart thixotropic properties, a filler treated with fatty acid or an amorphous filler such as organic bentonite or talc can be added to the curable resin composition according to the present invention.

Additionally, the curable resin composition of the present invention may contain a silane-based coupling agent. By mixing a silane-based coupling agent, it becomes possible to improve the adhesion between the above-mentioned magnetic powder or filler and the thermosetting resin and suppress the occurrence of cracks in the cured product.

If necessary, the curable resin composition according to the present invention may also contain an oxazine compound having an oxazine ring obtained by reacting a phenol compound, formalin, and a primary amine. By containing an oxazine compound, after curing the curable resin composition filled in the hole portion of the printed wiring board, when performing electroless plating on the formed cured product, roughening of the cured product using an aqueous potassium permanganate solution or the like is facilitated. , the peel strength from plating can be improved.

In addition, known colorants such as phthalocyanine blue, phthalocyanine green, disazo yellow, titanium oxide, carbon black, and naphthalene black may be added to the curable resin composition according to the present invention.

In addition, in order to provide storage stability during storage, known thermal polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, tert-butylcatechol, pyrogallol, and phenothiazine, and clay to adjust viscosity, etc. Known thickeners and thixotropic agents such as kaolin, organic bentonite, and montmorillonite can be added. In addition, known additives such as silicone-based, fluorine-based, polymer-based antifoaming agents, leveling agents, and adhesion imparting agents such as imidazole-based, thiazole-based, triazole-based, and silane coupling agents can be mixed. In particular, when organic bentonite is used, it is preferable because the portion protruding from the surface of the hole is easily formed in a protruding state that is easy to polish and remove, resulting in excellent polishing properties.

Considering applicability (printability), the curable resin composition according to the present invention preferably has a viscosity of 5 to 250 Pa·s, more preferably 7 to 200 Pa·s, and even more preferably 10 to 150 Pa·s. do. The viscosity of the curable resin composition is the amount of diluted components whose 5% weight loss temperature is 50°C or more and 180°C or less according to the above-mentioned thermogravimetric analysis, or the thermosetting resin whose 5% weight loss temperature is greater than 180°C according to thermogravimetric analysis. It can be adjusted depending on the type of ingredient or its mixing amount.

<Use of curable resin composition>

The above-mentioned curable resin composition can be widely and generally used, but it is preferably used for forming a cured film of a printed wiring board, more preferably for forming a permanent protective film, and is used as a solder resist, an interlayer insulating layer, a coverlay, or a hole filling ( It is more preferable to use it as a material. Among these uses, it is particularly preferable to use it as a filler for filling holes, specifically, as a filler for filling holes in through holes or recesses such as through holes in printed wiring boards.

When the above-mentioned curable resin composition is used as a filler for filling holes, the filler is formed by using known patterning methods such as screen printing, roll coating, die coating, and vacuum printing, for example, in through holes of a multilayer printed wiring board. It can be filled in a recess having a hole or bottom. The inner diameter of the hole filled with the curable resin composition is preferably 0.05 to 0.8 mm, and the depth is preferably 0.4 to 10 mm. Additionally, the inner diameter of the concave portion filled with the curable resin composition is preferably 0.1 mm or more and 0.8 mm or less in depth. At this time, it is preferable to completely fill the curable resin composition so that it slightly protrudes from the hole or recess.

By heating a multilayer printed wiring board whose holes and recesses are filled with a liquid curable resin composition at, for example, 80 to 160°C for about 30 to 180 minutes, the curable resin composition is cured and a cured product is formed. From the viewpoint of easily removing unnecessary portions of the cured product protruding from the substrate surface after filling holes by physical polishing, curing of the curable resin composition may be performed in two steps. That is, the curable resin composition can be pre-cured at a lower temperature and then main cured (final cured). The conditions for pre-curing are preferably heating at 80 to 110°C for about 30 to 180 minutes. Since the hardness of the pre-cured cured product is relatively low, unnecessary parts protruding from the surface of the substrate can be easily removed by physical polishing, resulting in a flat surface. Afterwards, it is heated and hardened. The conditions for main curing are preferably heating at 130 to 180°C for 30 to 180 minutes.

In both pre-curing and main curing, curing is carried out using a hot air circulation drying furnace, IR furnace, hot plate, convection oven, etc. (equipped with a steam-based air heating type heat source) to countercurrently contact the hot air in the dryer. method and a method of spraying the cured material from a nozzle). Among these, a hot air circulation type drying furnace is particularly preferable. At this time, due to low expansion, the cured product hardly expands or contracts, resulting in a final cured product with excellent dimensional stability, low hygroscopicity, adhesion, and electrical insulation. In addition, the hardness of the pre-cured product can be controlled by changing the heating time and heating temperature of the pre-curing.

Additionally, in the present invention, the curable resin composition may be cured by irradiating active energy rays as needed. When the curable resin composition contains a photocurable resin such as a photosensitive resin containing a carboxyl group, for example, using an ultraviolet ray exposure machine equipped with a high-pressure mercury lamp or a metal halide lamp, the curable resin composition is exposed to an integrated light amount of about 500 to 2000 mJ/cm2. By performing exposure (light irradiation), the exposed portion (light irradiated portion) is hardened. Additionally, for example, it can be heat-cured (post-cured) by heating to a temperature of about 100 to 180°C.

After curing the curable resin composition as described above, the unnecessary portion of the cured product protruding from the surface of the printed wiring board is removed by a known physical polishing method, flattened, and the wiring layer on the surface is patterned in a predetermined pattern. , a predetermined circuit pattern is formed. Additionally, if necessary, after roughening the surface of the cured product with an aqueous solution of potassium permanganate or the like, a wiring layer may be formed on the cured product by electroless plating or the like.

Example

Next, the present invention will be described in more detail using examples, but the present invention is not limited to these examples. In addition, in the following, “part” and “%” are all based on mass unless otherwise specified.

<Preparation of curable resin composition>

The various components shown in Table 1 below were mixed in the ratios (mass parts) shown in each table and mixed in a stirrer to prepare each curable resin composition of Examples 1 to 6 and Comparative Examples 1 and 2. In addition, the mixing amount of the magnetic powder in the table was adjusted to be constant on a weight basis for each curable resin composition. In addition, the content ratio of the diluting component in the table represents the content ratio (% by mass) relative to the total amount of the thermosetting resin and the diluting component, and the content ratio of the epoxy resin with a viscosity of 1 Pa·s or less is 5% weight loss temperature by thermogravimetric analysis. represents the content ratio (% by mass) of the entire thermosetting resin with a temperature exceeding 180°C. In addition, the content ratio of the magnetic powder represents the content ratio (% by mass) with respect to the entire composition.

In addition, *1 to *9 in Table 1 indicate the following components.

＊1: Alicyclic epoxy resin (TOMOE Engineering Co., Ltd. product, LDO, 5% weight loss temperature: 109.1℃)

＊2: 1,6-hexanediol diglycidyl ether (Mitsubishi Chemical Corporation, YED216D, 5% weight loss temperature: 172.0°C)

＊3: Dipropylene glycol methyl ether (Dow Chemical Japan Limited product, DOWANOL DPM, 5% weight loss temperature: 78.5℃)

＊4: Mixed solvent of ethanol, IPA, and NPA (Amakasu Chemical Industries product, ALCOZOLE K, 5% weight loss temperature by thermogravimetric analysis: 23.4°C (5% weight loss temperature as mixed solvent))

* 5: Triglycidylaminophenol type epoxy resin (Mitsubishi Chemical Corporation product, jER 630, viscosity: 0.5 to 1 Pa·s, liquid epoxy resin, 5% weight loss temperature: 250.6°C)

＊ 6: 50:50 mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin (NIPPON STEEL Chemical & Material Co., Ltd. product ZX-1059, viscosity: 1.9 to 2.6 Pa·s, liquid epoxy resin, 5% Weight loss temperature: 271.5℃)

＊ 7: Amorphous alloy magnetic powder (Epson Atmix Corporation product, AW02-08PF8F, average particle diameter 5㎛)

* 8: Copolymer compound containing an acid group (BYK JAPAN KK product, DISPERBYK-111)

* 9: Imidazole type hardener (Shikoku Chemicals Corporation product, 2MZA-PW) synthetic product)

In addition, the 5% weight loss temperature was measured using a differential calorimetry gravimetry device (TG/DTA6200, Hitachi High-Tech Science Corporation) under an air atmosphere, with a sample weight of 10 to 20 mg, an aluminum pan (non-airtight type), and 10 mg. The measurement was performed at a temperature increase rate of °C/min and a measurement temperature of 20 to 500°C.

<Evaluation of printing aptitude>

Each prepared curable resin composition was screen printed twice at 80 mesh on the surface of a copper foil substrate (150 mm x 95 mm, thickness 18 μm) without adjusting the viscosity, and a coating film was formed so that the film thickness after curing was 100 μm. Next, heat treatment at 150°C for 30 minutes was performed twice in a hot air circulation type drying furnace (DF610 manufactured by Yamato Scientific Co., Ltd.) to form a cured coating film.

For printability, it was confirmed whether there was any variation in the film thickness of the cured coating film (film thickness control). The film thickness was measured at 5 points at equal intervals of 15 mm within the cured film using a Digimatic Micrometer (manufactured by Mitutoyo Corporation), and the highest and lowest values were confirmed. The evaluation criteria for printing suitability were as follows.

○: The difference between the highest and lowest values is 30㎛ or less.

△: The difference between the highest and lowest values is more than 30㎛ and less than 50㎛

×: The difference between the highest and lowest values exceeds 50㎛

The evaluation results were as shown in Table 1 below.

<Evaluation of the aging stability of printing aptitude>

In order to reproduce the actual film formation process, 50 g of each prepared curable resin composition was first placed in an open container, High-Resist BHR-150, left to stand at 25°C for 20 minutes, and viscosity adjusted in the same manner as above. Instead, it was coated on the surface of a copper foil substrate and cured to form a cured film. The obtained cured coating film was evaluated for printability in the same manner as above.

The evaluation criteria for printing suitability were as follows.

○: The difference between the highest and lowest values is 30㎛ or less.

△: The difference between the highest and lowest values is more than 30㎛ and less than 50㎛

×: The difference between the highest and lowest values exceeds 50㎛

The evaluation results were as shown in Table 1 below.

<Evaluation of magnetic characteristics>

Each of the prepared curable resin compositions was screen-printed on the surface of copper foil attached to an etch-out plate without adjusting the viscosity, and a coating film was formed so that the film thickness after curing was 150 μm. Next, a cured film was formed by heat treatment at 150°C for 45 minutes in a hot air circulation drying furnace (DF610 manufactured by Yamato Scientific Co., Ltd.). Subsequently, the cured coating film was peeled from the copper foil, and the peeled cured coating film was cut into a toroidal shape with an outer diameter of 1.7 cm and an inner diameter of 0.5 cm to prepare an evaluation test piece. For each evaluation test piece obtained as described above, the relative permeability (μ') was measured at a temperature of 25°C and 100 MHz using an impedance analyzer E4291B manufactured by Keysight. The measurement results were as shown in Table 1 below.

<Evaluation of aging stability of magnetic characteristics>

In order to reproduce the actual film formation process, 50 g of each prepared curable resin composition was first placed in an open container, High-Resist BHR-150, left to stand at 25°C for 20 minutes, and viscosity adjusted in the same manner as above. Instead, it was coated on the surface of the copper foil attached to the etched-out plate and cured to form a cured film.

Subsequently, the cured coating film was peeled from the copper foil, the peeled cured coating film was cut into a toroidal shape with an outer diameter of 1.7 cm and an inner diameter of 0.5 cm, an evaluation test piece was produced, and the relative magnetic permeability was measured in the same manner as above. The evaluation criteria for the temporal stability of magnetic properties were as follows.

○: The relative magnetic permeability is not lower than the value measured in <Evaluation of magnetic properties>.

×: The relative magnetic permeability is lower than the value measured in <Evaluation of magnetic properties>.

The evaluation results were as shown in Table 1 below. In addition, "-" in the table means that a cured coating film could not be formed and the relative magnetic permeability could not be measured.

As is clear from the evaluation results in Table 1, the curable resin compositions according to the present invention (Examples 1 to 6) are excellent in the aging stability of printability and are also excellent in the aging stability of relative magnetic permeability. In addition, compared to Comparative Example 2, which does not contain a diluting component, the relative magnetic permeability is improved, and it can be seen that the magnetic properties are excellent.

On the other hand, in the curable resin composition (Comparative Example 1) containing a diluted component with a 5% weight loss temperature of less than 50°C according to thermogravimetric analysis, when the composition is left, some of the components in the composition volatilize even at room temperature, reducing the printability. It can be seen that the temporal stability is insufficient.

In addition, it can be seen that the curable resin composition containing no diluting component (Comparative Example 2) has poor printability and low relative magnetic permeability compared to other compositions.

<Evaluation of fillability>

Each of the curable resin compositions used in Examples 1 to 6 was filled into a through hole (with an inner diameter of 0.3 mm and a depth of 3.2 mm) of a multilayer printed wiring board by screen printing, and the board was placed against a rack. The composition was cured by heat treatment at 150°C for 30 minutes in a hot air circulation drying furnace (DF610 manufactured by Yamato Scientific Co., Ltd.) while the composition was placed at an angle of 90° ± 10° with respect to the surface.

Next, using a substrate in which the through hole was filled with a cured material, optical and electron microscopic observation of the cross section of the through hole after the hole was filled was performed to determine the presence or absence of cracks and delamination. Confirmed.

As a result, the occurrence of cracks and delamination (peeling) was not confirmed when filling holes using the curable resin composition of either example.

Claims (6)

A curable resin composition comprising a thermosetting resin, a curing agent, magnetic powder, and a diluting component,
The thermosetting resin has a 5% weight loss temperature of more than 180°C according to thermogravimetric analysis,
The diluting component is a curable resin composition, characterized in that the 5% weight loss temperature according to thermogravimetric analysis is 50°C or more and 180°C or less. According to paragraph 1,
A curable resin composition in which the dilution component is contained in an amount of 30% by mass or less relative to the total amount of the thermosetting resin and the dilution component. According to paragraph 1,
A curable resin composition in which the thermosetting resin is in a liquid form. According to paragraph 1,
A curable resin composition in which the thermosetting resin includes an epoxy resin having a viscosity of 1 Pa·s or less. According to paragraph 4,
A curable resin composition containing 35% by mass or more of the epoxy resin relative to the entire thermosetting resin. According to paragraph 1,
A curable resin composition used as a filler for through holes or recesses in printed wiring boards.