TW202342636A - Curable resin composition - Google Patents

Abstract

The present invention provides a curable resin composition with excellent heat resistance, low coefficient of thermal expansion (CTE), crack resistance, as well as superior fillability and adhesion to copper plating. The curable resin composition of the present invention comprises (A) epoxy resin, (B) epoxy resin hardener, and (C) inorganic filler. The (A) epoxy resin includes at least three types of epoxy resins with different functional group numbers or molecular backbone structures, wherein the three types of epoxy resins comprise epoxy resins with functional group numbers of 2 or less, and epoxy resins with aromatic rings and functional group numbers of 4 or more.

Description

Hardening resin composition

The present invention relates to a curable resin composition, and relates to a curable resin composition suitable for use as a filling material for filling holes such as through-holes or recessed portions of printed circuit boards.

As electronic devices become smaller and more functional, printed circuit boards are required to have finer patterns, smaller mounting areas, and higher density mounting of components. Therefore, a multilayer substrate such as a double-sided substrate or a build-up circuit board provided with through holes, that is, through-holes, for forming interlayer connections for electrically connecting different wiring layers to each other is used. The build-up circuit board is attached to the core. Insulating layers and conductor circuits are formed on the material in sequence, and through-holes are used to connect the layers to make it multi-layered.

In this type of printed circuit board, holes such as recesses between conductor circuits on the surface or through-holes and through-holes where a wiring layer is formed on the inner wall surface are generally filled with a curable resin filling material. As the curable resin filler, generally epoxy resin as a curable resin component, an epoxy resin hardener, and a curable resin filler containing an inorganic filler are used.

In addition, improvements in heat resistance and low CTE (coefficient of thermal expansion) of printed circuit boards are progressing, and along with this, curable resin fillers are also required to have heat resistance and low CTE. For example, the temperature of mounting electronic components on a package substrate is as high as about 250°C. Therefore, there is a demand for a curable resin filler material that has better heat resistance than conventional ones, has low CTE, and has excellent crack resistance and adhesion to copper. . For example, Patent Document 1 proposes a curable resin composition that can form a hole insulating layer that is excellent in crack resistance and adhesion and is excellent in insulation reliability, heat resistance, moisture resistance, PCT resistance, and the like. [Prior technical literature]

[Patent Document] [Patent Document 1] Japanese Patent Application Publication No. 2009-269994

In recent years, in package substrates such as IC substrates, the thickness of the substrate has increased due to multi-layering, and the length of the through hole has increased while the hole diameter has tended to become smaller. Therefore, a filling material with excellent filling properties (printability) is more desired than ever before. Although heat resistance or CTE can be reduced by increasing the blending ratio of inorganic fillers, there is a tendency for filling properties (printability) to deteriorate, and it can be said that there is a trade-off relationship between these characteristics.

Therefore, an object of the present invention is to provide a curable resin composition that is excellent in heat resistance, low CTE, and crack resistance, and is also excellent in filling properties and adhesion to copper plating.

The inventors of the present invention focused on epoxy resins and found that the above problems can be solved by combining a plurality of epoxy resins with different functional groups. The present invention is based on these findings. That is, the gist of this invention is as follows.

[1] A curable resin composition containing: (A) Epoxy resin, (B) Epoxy resin hardener, and (C) Inorganic filler, It is characterized in that the (A) epoxy resin includes at least three kinds of epoxy resins with different functional group numbers or molecular skeleton structures, and the three kinds of epoxy resins at least include an epoxy resin with a functional group number of 2 or less and a functional group number of 4 or more. Epoxy resin with aromatic ring. [2] The curable resin composition according to [1], wherein the epoxy resin having 4 or more functional groups is liquid at room temperature. [3] The curable resin composition according to [1] or [2], wherein the (A) epoxy resin further contains an epoxy resin with 3 functional groups. [4] The curable resin composition according to [3], which contains 10 to 90 mass % of the inorganic filler (C) relative to the total solid content of the curable composition. [5] The curable resin composition according to any one of [1] to [4], wherein the (C) inorganic filler contains silica. [6] The curable resin composition according to any one of [1] to [5], which is used as a filling material for through holes or recesses of a printed circuit board.

According to the present invention, by combining three or more epoxy resins with different functional groups or molecular skeleton structures, it is possible to achieve excellent heat resistance, low CTE, and crack resistance, and also have better filling properties and adhesion to copper plating. It is an excellent curable resin composition.

＜Cureable resin composition＞ The curable resin composition of the present invention contains (A) epoxy resin, (B) epoxy resin hardener and (C) inorganic filler as essential components. In addition, in this specification, "liquid state" means a fluid liquid state or a semi-liquid state (paste state). Each component is described in detail below.

[Epoxy resin] The curable resin composition of the present invention contains at least three types of epoxy resins having different functional group numbers or molecular skeleton structures as curable component epoxy resins. In addition, in this specification, the number of functional groups means an epoxy group (glycidyl group), and the molecular skeleton structure means a compound in which the epoxy group is substituted with a hydrogen atom.

In the present invention, at least two of the three types of epoxy resins are epoxy resins with functional groups of 2 or less and epoxy resins with aromatic rings with functional groups of 4 or more. In a curable resin composition mainly containing an epoxy resin as a curable component, by containing an epoxy resin with a functional group number of 2 or less and an epoxy resin with an aromatic ring with a functional group number of 4 or more, and a molecular skeleton structure and These two different epoxy resins or an epoxy resin with a functional group number of 3 can form a hardening resin composition that not only has excellent heat resistance, low CTE and crack resistance, but also has filling properties and close contact with copper plating. Compatibility is also excellent. The reason for this is not clear, but by containing a polyfunctional epoxy resin having an aromatic ring with a functional group number of 4 or more, the cross-linking density of the cured product becomes higher, so the heat resistance of the cured product is improved and the CTE is reduced. Therefore, there is no need to mix a large amount of inorganic fillers like conventional curable resin compositions, so the printability and filling properties are improved. In addition, the volume shrinkage during hardening is suppressed and the crack resistance is improved, and it is easy to be etched during the desmear step. As a result, it is speculated that the adhesion to copper plating is also improved due to the surface unevenness effect. On the other hand, when only 4 or more polyfunctional epoxy resins are included, the water absorption rate due to amine during etching becomes too high, which leads to a decrease in adhesion to copper plating. In addition, in the combination of epoxy resins with only 2 or 3 functional groups, the volume shrinkage becomes large, so cracks are likely to occur during hardening, and the CTE is not sufficiently reduced.

＜Epoxy resin with 2 or less functional groups＞ Among epoxy resins with 2 or less functional groups, examples of epoxy resins with 2 functional groups (hereinafter also referred to as bifunctional epoxy resins) include bisphenol A diglycidyl ether type epoxy resin, bisphenol A diglycidyl ether type epoxy resin, Phenol F diglycidyl ether type epoxy resin, bisphenol E type epoxy resin, bisphenol S diglycidyl ether type epoxy resin, resorcinol diglycidyl ether type epoxy resin, hydroquinone diglycidyl ether Type epoxy resin, diglycidyl terephthalate type epoxy resin, bisphenoxyethanol-diglycidyl ether type epoxy resin, bisphenol-diglycidyl ether type epoxy resin, dicresol-diglycidyl ether type epoxy resin Glyceryl ether type epoxy resin, novolac glycidyl ether type epoxy resin, glycidyl hexahydrophthalate and other epoxy resins with aromatic skeleton, cyclohexanedimethanol diglycidyl ether, butanediol diglycidyl ether , diglycidyl hexahydrophthalate and other epoxy resins with aliphatic skeleton, but are not limited thereto.

Examples of epoxy resins with one functional group (hereinafter also referred to as monofunctional epoxy resins) include alkyl glycidyl ethers, alkenyl glycidyl ethers, and alkyl glycidyl esters having 6 to 36 carbon atoms. , epoxy resins with aliphatic skeletons such as alkenyl glycidyl esters, and epoxy resins with aromatic skeletons such as phenyl glycidyl ether and phenyl glycidyl esters, but are not limited thereto. In addition, the chain length of the alkyl group is usually about 6 to 18.

Only one type of epoxy resin with a functional group number of 2 or less may be used, or two or more epoxy resins may be used in combination. However, in the present invention, from the viewpoint of crack resistance or adhesion to copper plating, , preferably an epoxy resin containing 2 functional groups.

From the viewpoint of crack resistance or adhesion to copper plating, the epoxy resin with the above functional group number of 2 or less preferably contains 5 to 70 parts by mass when the total solid content of the epoxy resin is 100 parts by mass. parts by mass, preferably 10 to 50 parts by mass.

＜Epoxy resin with aromatic ring with 4 or more functional groups＞ Among epoxy resins having an aromatic ring with a functional group number of 4 or more, examples of an epoxy resin having an aromatic ring with a functional group number of 4 (hereinafter also referred to as tetrafunctional epoxy resin) include: bisphenol A type epoxy Resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, phenol novolak type epoxy resin, m-phenylene Epoxy resins that are liquid at room temperature, such as dimethylamine type epoxy resin, or bixylenol type epoxy resin, cresol novolak type epoxy resin, ginseng phenol type epoxy resin, naphthalene type Epoxy resins such as phenol type epoxy resin, biphenyl type epoxy resin, naphthyl ether type epoxy resin, onion type epoxy resin, tetraphenylethane type epoxy resin, etc. are solid at room temperature, but are not Limited to this.

Examples of the epoxy resin having an aromatic ring with 5 functional groups (hereinafter also referred to as pentafunctional epoxy resin) include 2,4,6-s[(4-hydroxyphenyl)methyl]-1,3- Benzene glycol type epoxy resin, etc.

Examples of the epoxy resin having an aromatic ring with 6 or more functional groups (hereinafter also referred to as 6 or more functional epoxy resins) include 2,3,6,7,10,11-hexaepoxypropoxytris Phenylene group, etc., but are not limited thereto.

As for the epoxy resin having an aromatic ring with a functional group number of 4 or more, only one type may be used, or two or more types of epoxy resins may be used in combination. However, in the present invention, a tetrafunctional epoxy resin is preferably used. Moreover, among the tetrafunctional epoxy resins, from the viewpoint of the balance between filling properties (printability) and crack resistance, a tetrafunctional epoxy resin that is liquid at room temperature is preferred. Furthermore, among the tetrafunctional epoxy resins that are liquid at room temperature, m-xylylenediamine type epoxy resin and the like are preferably used from the viewpoint of heat resistance.

From the viewpoint of heat resistance and low CTE, the epoxy resin having an aromatic ring with a functional group number of 4 or more preferably contains 5 to 50 parts by mass when the total solid content of the epoxy resin is 100 parts by mass. , preferably 10 to 40 parts by mass.

The blending ratio of the above-mentioned epoxy resin with 2 or less functional groups and the epoxy resin with an aromatic ring with 4 or more functional groups is preferably 90:10 to 10:90 in terms of solid content, more preferably 90:90: 10~20:80, even better is 90:10~40:60.

＜Other epoxy resins＞ The curable resin composition of the present invention contains epoxy resins other than the above two types of epoxy resins. The "two types of epoxy resins other than epoxy resins" here means the case where two types of epoxy resins are included, namely an epoxy resin with a functional group number of 2 or less and an epoxy resin with an aromatic ring with a functional group number of 4 or more. Below, an epoxy resin with the same number of functional groups as the epoxy resin but a different molecular skeleton structure, or an epoxy resin with an arbitrary molecular skeleton structure and a functional group number of 3 (hereinafter also referred to as a trifunctional epoxy resin), etc. In the present invention, the epoxy resin preferably contains one or more bifunctional epoxy resins, one or more tetrafunctional epoxy resins having aromatic rings, and one or more trifunctional epoxy resins.

Examples of the trifunctional epoxy resin include triskeleton-containing epoxy resin, aminophenol type epoxy resin, aminocresol type epoxy resin, triphenyl glycidyl ether methane type epoxy resin, etc. However, It is not limited to this. Only one type of these trifunctional epoxy resins may be used, or two or more types of epoxy resins may be used in combination.

When a trifunctional epoxy resin is included as the epoxy resin, as the blending ratio, from the viewpoint of printability or heat resistance, when the total solid content of the epoxy resin is 100 parts by mass, it is preferred to include 10~ 50 parts by mass, preferably 20 to 40 parts by mass.

When an epoxy resin with a functional group of 3 is included, the blending amount of an epoxy resin with a functional group of 2 or less, an epoxy resin with a functional group of 3, and an epoxy resin with an aromatic ring with a functional group of 4 or more, shall be determined in the solid state. In terms of ingredient conversion, the preferred range is 80~10:10~45:10~45, and the preferred range is 70~10:15~45:15~45.

In addition, an epoxy resin having no aromatic ring and having a functional group number of 4 or more may also be included. Examples of such epoxy resins include alicyclic epoxy resins having an ester skeleton, cyclohexane-type epoxy resins, cyclohexanedimethanol-type epoxy resins, epoxy resins having a butadiene structure, and bicyclic epoxy resins. Pentadiene epoxy resin, dipenterythritol hexaglycidyl ether, sorbitol hexaglycidyl ether, etc.

The blending amount of the total solid content of the epoxy resin is preferably 5 to 70 parts by mass, more preferably 10 to 60 parts by mass relative to the total solid content of the curable resin composition.

In addition, when considering coating properties such as film formation properties of the curable resin composition, that is, printability, the epoxy resin used in the present invention is preferably in a liquid form rather than a solid form. In particular, the viscosity of the epoxy resin is preferably 20 Pa･s or less, more preferably 10 Pa･s or less, and still more preferably 5 Pa･s or less. In addition, the viscosity here refers to the viscosity measurement method based on JIS K8803: 2011-10 cone-plate rotational viscometer, using a cone-plate viscometer (TV-33H manufactured by Toki Sangyo Co., Ltd.) with 25 Viscosity measured at ±1℃, 5rpm, 30 seconds.

[(B) Epoxy resin hardener] (B) The epoxy resin hardener can be used as long as it has the effect of accelerating the hardening reaction of the epoxy resin, and is not particularly limited. Examples include amines, imidazoles, polyfunctional phenols, acid anhydrides, isocyanates, and the like. A variety of polymers with functional groups can be used as needed. Amines include dicyandiamide, diamine diphenylmethane, etc. Imidazoles include alkyl-substituted imidazole, benzimidazole, etc. Moreover, the imidazole compound may be an imidazole latent hardener such as an imidazole adduct. Polyfunctional phenols include hydroquinone, resorcinol, bisphenol A and its halides, as well as novolaks and resol phenolic resins which are condensates with aldehydes. Acid anhydrides include phthalic anhydride, hexahydrophthalic anhydride, methyl Nadic anhydride (Methyl Nadic Anhydride), benzophenone tetracarboxylic acid, etc. Examples of isocyanates include tolylene diisocyanate, isophorone diisocyanate, and the like, and those in which this isocyanate is masked with phenols or the like can also be used. One type of these hardeners may be used alone, or two or more types may be used in combination.

Among the above-mentioned curing agents, amines and imidazoles are suitably used from the viewpoint of adhesion to the conductive part or the insulating part, storage stability, and heat resistance. Preferred are aliphatic polyamines such as alkylene diamines with 2 to 6 carbon atoms, polyalkylene polyamines with 2 to 6 carbon atoms, and aliphatic polyamines containing aromatic rings with 8 to 15 carbon atoms. Addition compounds of amines, or addition compounds of alicyclic polyamines such as isophorone diamine, 1,3-bis(aminomethyl)cyclohexane, or addition compounds of the above aliphatic polyamines The main component is a mixture with an addition compound of the above-mentioned alicyclic polyamine.

As the addition compound of the aliphatic polyamine, an aryl glycidyl ether (especially phenyl glycidyl ether or tolyl glycidyl ether) or an alkyl glycidyl ether is preferably added to the aliphatic polyamine. Those who gain by reaction. Moreover, as the addition compound of the said alicyclic polyamine, it is preferable that it is obtained by the addition reaction of n-butyl glycidyl ether, bisphenol A diglycidyl ether, etc., and this alicyclic polyamine.

Examples of aliphatic polyamines include alkylenediamines having 2 to 6 carbon atoms such as ethylenediamine and propylenediamine, and polyalkanes having 2 to 6 carbon atoms such as diethylenetriamine and triethylenetriamine. Polyamines, xylenediamine and other aliphatic polyamines containing aromatic rings with 8 to 15 carbon atoms. Examples of commercially available modified aliphatic polyamines include Fujicure FXE-1000, Fujicure FXR-1020, Fujicure FXR-1030, Fujicure FXR-1080, and Fujicure FXR-1090M2 (T&K TOKA CO., LTD. (manufactured by Evonik Japan Co., Ltd.), ANCAMINE 2089K, SUNMIDE P-117, SUNMIDE X-4150, ANCAMINE 2422, Serwet R, SUNMIDE TX-3000, SUNMIDE A-100 (made by Evonik Japan Co., Ltd.), etc.

Examples of alicyclic polyamines include isophorone diamine, 1,3-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, norbornene diamine, 1 ,2-Diaminocyclohexane, Laromin, etc. Examples of commercially available modified alicyclic polyamines include: ANCAMINE 1618, ANCAMINE 2074, ANCAMINE 2596, ANCAMINE 2199, SUNMIDE IM-544, SUNMIDE I-544, ANCAMINE 2075, ANCAMINE 2280, ANCAMINE 1934, ANCAMINE 2228 (manufactured by Evonik Japan Co., Ltd.), Daitocurar F-5197, Daitocurar B-1616 (manufactured by Daito Industrial Co., Ltd.), Fujicure FXD-821, Fujicure 4233 (manufactured by T&K TOKA CO., LTD.), jERCURE 113 ( Mitsubishi Chemical Co., Ltd.), Laromin C-260 (BASF JAPAN Co., Ltd.), etc. Examples of the polyamine type curing agent include EH-5015S (manufactured by ADEKA Corporation) and the like.

Imidazole refers to, for example, the reaction product of epoxy resin and imidazole. Examples include: 2-methylimidazole, 4-methyl-2-ethylimidazole, 2-phenylimidazole, 4-methyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 2 -Ethyl imidazole, 2-isopropylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl- 2-Undecyl imidazole, etc. Examples of commercially available imidazole compounds include imidazoles such as 2E4MZ, C11Z, C17Z, and 2PZ, AZINE (azine) compounds of imidazoles such as 2MZ-A and 2E4MZ-A, and imidazoles such as 2MZ-OK and 2PZ-OK. Isocyanuric acid, 2PHZ, 2P4MHZ and other imidazole hydroxymethyl compounds (all manufactured by Shikoku Chemical Industry Co., Ltd.), etc. Examples of commercially available imidazole type latent curing agents include Cure Duct P-0505 (manufactured by Shikoku Chemical Industry Co., Ltd.).

When the total solid content of (A) epoxy resin is 100 parts by mass, the blending amount of the above-mentioned hardener is preferably 1 to 100 parts by mass, more preferably 2 to 30 parts by mass, and particularly preferably 3 to 20 parts by mass. parts by mass. In particular, when the blending amount of (B) the epoxy resin hardener is 3 parts by mass or more, generally speaking, the preliminary hardening speed of the resin composition will not be slowed down, and the composition in the deep part of the hole will be sufficiently hardened. As a result, the occurrence of cracks, so it is better. In addition, when the blending amount of (B) the epoxy resin hardener is 50 parts by mass or less, the storage stability becomes good, and generally the preliminary curing speed of the resin composition does not become too fast, and the cured product is less likely to remain. pores, so it is better.

[(C) Inorganic filler] (C) The inorganic filler is contained in order to adjust stress relaxation or linear expansion coefficient due to hardening shrinkage of the filler material. As the inorganic filler, conventional inorganic fillers used in ordinary resin compositions can be used. Specific examples include silicon dioxide, barium sulfate, calcium carbonate, silicon nitride, aluminum nitride, boron nitride, aluminum oxide, magnesium oxide, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica, and talc. , organic bentonite and other non-metallic fillers, and copper, gold, silver, palladium, silicon, alloy, ferrite and other metal fillers. One type of these inorganic fillers may be used alone, or two or more types may be used in combination.

Among these inorganic fillers, calcium carbonate, silica, barium sulfate, and alumina, which are excellent in low hygroscopicity and low volume expansion, are suitably used, and among these, silica is more suitably used. The silica may be either amorphous or crystalline, or a mixture thereof. Particularly preferred is amorphous (fused) silica.

The shape of the inorganic filler is not particularly limited. Examples include: spherical, needle-shaped, plate-shaped, scaly, hollow, irregular, hexagonal, cubic, flake, etc. From the perspective of high blending of inorganic fillers It seems that it is preferably spherical.

In addition, considering the dispersibility of the inorganic filler, the filling ability of the hole portion, the smoothness when forming the wiring layer in the hole-filled portion, etc., the average particle size of the inorganic filler is preferably 0.1 μm ~ 25 μm, preferably Range of 0.1μm~15μm. More preferably, it is 1μm~10μm. In addition, the average particle size means the average primary particle size, and the average particle size (D50) can be measured by the laser diffraction/scattering method.

The blending ratio of the inorganic filler is preferably a ratio relative to the total solid content of the curable resin composition from the viewpoint of achieving a thermal expansion coefficient, abrasiveness, adhesion, and printability or hole-filling properties as a cured product. The content is 10 to 90 mass%, more preferably 20 to 80 mass%, and particularly preferably 40 to 75 mass%.

[Other ingredients] The curable resin composition of the present invention may also contain curable resins other than the above-mentioned epoxy resin as curable components. Examples thereof include isocyanate compounds, blocked isocyanate compounds, amine resins, carbodiimide resins, and cyclic carbonates. Compounds, oxetane compounds, episulfide resins, urea resins, melamine resins and other resins with tricyclic rings, unsaturated polyester resins, bismaleimine compounds and other malein compounds Imine resin, polyurethane resin, diallyl phthalate resin, benzophenone resin, polyimide resin, polyamide-imide resin, benzocyclobutene resin, Cyanate ester resins such as novolak type cyanate ester resin, bisphenol A type cyanate ester resin, bisphenol E type cyanate ester resin, tetramethyl bisphenol F type cyanate ester resin, etc. , polysilicone resin and other familiar users. These components can be used alone or in combination of two or more.

In addition, fillers treated with fatty acids, or irregular fillers such as organic bentonite and talc may be added to the curable resin composition of the present invention to impart thixotropy.

As the above-mentioned fatty acid, the general formula can be used: (R ¹ COO) _n -R ² (The substituent R ¹ is a hydrocarbon with 5 or more carbon atoms, the substituent R ² is hydrogen or a metal alkoxide, or a metal, and n is 1 to 4 ) the compound shown. When the number of carbon atoms in the substituent R ¹ is 5 or more, the fatty acid exhibits the effect of imparting thixotropy. More preferably, n is 7 or more.

The fatty acid may be an unsaturated fatty acid having double bonds or triple bonds in the carbon chain, or a saturated fatty acid not containing such. Examples include: stearic acid (the number of carbon atoms and the number of unsaturated bonds and their positions in parentheses are numerical values; 18:0), hexanoic acid (6:0), oleic acid (18:1(9)), ethanol Conic acid (20:0), behenic acid (22:0), triaconic acid (30:0), etc. The carbon number of the substituent R1 of these fatty acids is preferably 5 to 30. More preferably, the carbon number is 5 to 20. For example, a metal alkoxide having a titanate substituent capped with an alkoxy group as the substituent R2 may be a coupling agent structure having a long (carbon number of 5 or more) aliphatic chain skeleton. By. For example, the trade name KR-TTS (manufactured by Ajinomoto Fine-Techno Co., Inc.) or the like can be used. In addition, metal soaps such as aluminum stearate and barium stearate (both manufactured by Kawamura Chemical Industry Co., Ltd.) can be used. Other metal soap elements include Ca, Zn, Li, Mg, Na, etc.

When the curable resin composition of the present invention contains a fatty acid, from the viewpoint of thixotropy, embedding property, defoaming property, etc., the blending ratio of the fatty acid is preferably 0.1 to 2 parts by mass relative to 100 parts by mass of the inorganic filler. Proportion.

Fatty acids can be blended by using inorganic fillers that have been surface-treated with fatty acids in advance, which can more effectively impart thixotropy to the curable resin composition. In this case, the blending ratio of fatty acids can be lower than when using untreated fillers. When all inorganic fillers are fatty acid-treated fillers, the blending ratio of fatty acids is preferably 0.1 to 1 part by mass relative to 100 parts by mass of inorganic fillers.

In addition, the curable resin composition of the present invention may also contain a silane coupling agent. By blending a silane coupling agent, the adhesion between the inorganic filler and the epoxy resin can be improved, and the occurrence of cracks in the cured product can be suppressed.

Examples of the silane-based coupling agent include epoxy silane, vinyl silane, imidazole silane, mercapto silane, methacryloxy silane, amino silane, styryl silane, isocyanate silane, thioether silane, and urea silane. Silane etc. In addition, the silane-based coupling agent can also be blended by using an inorganic filler that has been surface-treated with a silane-based coupling agent in advance.

When the curable resin composition of the present invention contains a silane coupling agent, from the viewpoint of achieving both the adhesion and defoaming properties of the inorganic filler and the epoxy resin, the amount of the silane coupling agent should be higher than 100 parts by mass of the inorganic filler. The preferred combined ratio is 0.05~2.5 parts by mass.

The curable resin composition of the present invention may also be blended with other 㗁𠯤 compounds having a 㗁𠯤 ring obtained by reacting a phenol compound, formalin and a primary amine as required. By containing the 㗁𠯤 compound, after the curable resin composition filled in the holes of the printed circuit board is cured, when electroless plating is performed on the formed cured product, it can be easily cured with a potassium permanganate aqueous solution or the like. The roughening of the material can improve the peeling strength with the plating layer.

In addition, conventional colorants such as phthalocyanine blue, phthalocyanine green, disazo yellow, titanium oxide, carbon black, and naphthalene black used in ordinary screen printing resist inks can also be added.

In addition, conventional thermal polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, tertiary butylcatechol, pyrogallol, and phenothiol can be added to provide storage stability during storage. properties, or add clay, kaolin, organic bentonite, microcrystalline kaolinite and other commonly known tackifiers and thixotropic agents to adjust the viscosity. In addition, conventional additives such as silicone-based, fluorine-based, polymer-based defoaming agents, leveling agents, or adhesion-imparting agents such as imidazole-based, thiazole-based, triazole-based, and silane coupling agents may be blended. class. In particular, it is preferable to use organic bentonite because it is easy to form a protruding state in which the portion protruding from the surface of the hole is easily polished/removed, and has excellent grindability. Furthermore, conventionally used coloring agents such as phthalocyanine blue, phthalocyanine green, iodine green, disazo yellow, crystal violet, titanium oxide, carbon black, and naphthalene black may also be blended.

When the curable resin composition of the present invention mainly contains liquid epoxy resin as the epoxy resin, it is not necessary to use a diluting solvent. However, as long as pores are not generated, a diluting solvent can also be added. For adjusting the viscosity of curable resin compositions.

Examples of diluting solvents include: ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; methylserosol, butylserosu, methylcarbitol, butyl Glycol ethers such as carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate and acetate esters of the above glycol ethers; ethanol , propanol, ethylene glycol, propylene glycol and other alcohols; aliphatic hydrocarbons such as octane and decane; petroleum-based solvents such as petroleum ether, naphtha, hydrogenated naphtha, solvent naphtha and other petroleum solvents.

[Applications of curable resin compositions] The curable resin composition of the present invention can generally be used widely, but it is preferably used to form a cured film for a printed circuit board, more preferably it is used to form a permanent protective film, and further preferably it is used as a solder resist, an interlayer insulating layer, and a covering layer. Filling (material) used for filling layers or holes. Among these uses, a filling material for hole filling is particularly preferred, and specifically, a filling material for filling holes or recessed portions such as through-holes in a printed circuit board is particularly preferred.

When the above-mentioned curable resin composition is used as a filling material for hole filling, the filling material can be filled into, for example, a multilayer printed circuit using a conventional patterning method such as screen printing, roll coating, die coating, or vacuum printing. The hole part of the through hole of the board or the recessed part with the bottom. The inner diameter of the hole or recess filled with the curable resin composition is not particularly limited, but in package substrates such as IC substrates, server substrates, automotive substrates, etc., it is 0.05 to 0.8 mm, and the depth is 0.4 to 10 mm. At this time, it is preferable to completely fill until the curable resin composition protrudes slightly from the hole or the recessed portion.

Therefore, the viscosity of the curable resin composition of the present invention at 25±1°C is preferably in the range of 100 to 1000 dPa･s, more preferably 200 to 800 dPa･s, and particularly preferably 200 to 600 dPa･s. By setting it within the above range, holes can be easily filled, and recesses and through holes can be satisfactorily filled without generating voids or the like. In addition, the viscosity here refers to the viscosity measurement method based on JIS K8803: 2011-10 cone-plate rotational viscometer, using a cone-plate viscometer (TV-33H manufactured by Toki Sangyo Co., Ltd.) with 25 Viscosity measured at ℃, 5 rpm, 30 seconds.

By heating a multilayer printed circuit board filled with holes or recesses with the curable resin composition at, for example, 80 to 160° C. for about 30 to 180 minutes, the curable resin composition is cured to form a cured product. From the viewpoint that unnecessary portions of the cured material protruding from the substrate surface after the holes are filled can be easily removed by physical grinding, the curing of the curable resin composition can also be performed in two stages. That is, the curable resin composition can be preliminarily hardened at a lower temperature, and then can be fully hardened (complete hardened). As a pre-hardening condition, it is preferable to heat at 80~110°C for about 30~180 minutes. The hardness of the hardened material to be hardened is low, so the unnecessary parts protruding from the substrate surface can be easily removed by physical grinding to form a flat surface. Afterwards, it is heated to officially harden. As a condition for formal hardening, it is best to heat at 130~180℃ for about 30~180 minutes.

Regarding hardening, in both preliminary hardening and main hardening, a hot air circulation drying oven, IR oven, hot plate, convection oven, etc. can be used (using a heat source with an air heating method using steam to cause the hot air in the dryer to proceed Countercurrent contact method, and blowing from the nozzle to the object to be hardened). Among them, the hot air circulation drying furnace is particularly suitable. At this time, due to the low expansion property, the cured product hardly expands or shrinks, and becomes a final cured product with good dimensional stability and excellent low moisture absorption, adhesion, and electrical insulation properties. In addition, the hardness of the preliminary hardening material can be controlled by changing the heating time and heating temperature of the preliminary hardening.

After curing the curable resin composition in the above manner, the unnecessary portions of the cured material protruding from the surface of the printed circuit board are removed and planarized by a conventional physical polishing method, and then the wiring layer on the surface is patterned into a predetermined pattern. , forming a predetermined circuit pattern. In addition, if necessary, after the surface of the cured product is roughened with a potassium permanganate aqueous solution 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 further detail using examples, but the present invention is not limited to these examples. In addition, unless otherwise stated, the following "parts" and "%" are based on mass.

<Preparation of curable resin composition> The various components shown in Table 1 below were blended in the proportions (parts by mass) shown in each table and mixed with a mixer to prepare curable resin compositions of Examples 1 to 7 and Comparative Examples 1 to 6.

In addition, *1~*9 in Table 1 indicate the following components. *1: 2-functional bisphenol A type epoxy resin (NIPPON STEEL Chemical & Material Co., Ltd., YD-127) *2: 2-functional biphenol F type epoxy resin (NIPPON STEEL Chemical & Material Co., Ltd., YDF-170) *3: Trifunctional phenol type epoxy resin (manufactured by Mitsubishi Chemical Co., Ltd., jER-630) *4: 4-functional m-xylylenediamine type epoxy resin (MITSUBISHI GAS CHEMICAL COMPANY, INC., TERTAD-X) *5: 4-functional diallyl bisphenol A type epoxy resin (manufactured by SHOWA DENKO Karenz Co., Ltd., Shofree BATG) *6: 4-functional neopentaerythritol tetraallyl ether type epoxy resin (manufactured by SHOWA DENKO Karenz Co., Ltd., Shofree PETG) *7: Tetrafunctional diamine diphenylmethane type epoxy resin (manufactured by Mitsubishi Chemical Co., Ltd., jER-604) *8: 5-functional siloxane skeleton epoxy resin (manufactured by Mitsubishi Chemical Co., Ltd., YL-9028) *9: Imidazole hardener (manufactured by Shikoku Kasei Co., Ltd., CUREZOL 2MZA-PW) *10: Imidazole-epoxy adduct type latent hardener (manufactured by T&K TOKA CO., LTD., Fujicure FXR-1121) *11: Fused silica (manufactured by Denka Company Limited, FB-7SDC) *12: Heavy calcium carbonate (MARUO CALCIUM CO., LTD., Super 4S)

＜Evaluation of volume shrinkage＞ The density before hardening (D1) and the density after hardening (D2) of the curable resin composition of each Example and Comparative Example were measured. The measurement was carried out in the following manner.

(Measurement of the density of the curable resin composition before curing) After fully defoaming each curable resin composition with a vacuum stirring or rotation-revolving mixer, use a metal pycnometer with a capacity of 100 ^cm3 , and use the pycnometer method ( The density (D1) of the curable resin composition is measured based on JIS K5600-2-4: 2014).

(Density measurement of curable resin composition after curing) Each curable resin composition was applied to the glossy side of GTS-MP foil (manufactured by Furukawa Circuit Foil Co., Ltd.) using an applicator so that the thickness of the coating film before curing would be 100 to 150 μm. (copper foil), the curable resin composition was cured by heating at 150° C. for 60 minutes in a hot air circulation drying furnace, and the obtained cured product was peeled off from the copper foil to form a measurement sample. The density (D2) of the sample measured by the water displacement method (according to JIS K7112:1999).

(Calculation of volume shrinkage) Using D1 and D2 measured in the above manner, the volume shrinkage rate defined by the following formula is calculated. Volume shrinkage (%)=(D2-D1)/D2×100 The calculated volume shrinkage is shown in Table 1 below.

＜Evaluation of ink viscosity＞ The viscosity at 25° C. was measured for each curable resin composition of the Examples and Comparative Examples. That is, a 0.2 ml sample was collected, and the viscosity was measured at 25°C, 5 rpm, and 30 seconds using a cone and plate viscometer (TV-33H manufactured by Toki Industrial Co., Ltd.) based on JIS K8803: 2011-10. Measure.

＜Preparation of evaluation substrate＞ By screen printing method, the curable resin compositions of each example and comparative example were printed from a glass epoxy substrate (having a through hole with a conductor layer formed by panel plating) under the following printing conditions. The thickness of the through hole is 1.6 mm/the diameter of the through hole. 0.15mm (after plating) / one side of the glass epoxy substrate with a pitch of 1mm) is filled into the through hole. After filling, the curable resin composition was cured by heating at 110° C. for 30 minutes and then at 150° C. for 60 minutes in a hot air circulation drying oven to obtain an evaluation substrate. (Printing conditions) Scraper : Scraper thickness 20mm flat scraper (hardness 70°) Screen version: PET150 mesh twill version Printing pressure: 50kg Scraper speed: 10mm/Sec Scraper angle: 95° (angle of attack 5°)

＜Evaluation of printability＞ Using the substrate produced in <Preparation of Evaluation Substrate>, observe the substrate surface on the printing surface and the reverse side with an optical microscope to confirm the state of the ink protruding from the through hole. 5000 through holes were observed and the printability was evaluated. The evaluation criteria are as follows. ◎: Curable resin composition protrudes from all through holes ○: The curable resin composition has 1 to 10 unprotruded through holes. △: The curable resin composition has 11 to 100 unprotruded through holes. ×: The curable resin composition has more than 101 non-protruding through holes. The evaluation results are shown in Table 1 below.

＜Evaluation of crack resistance＞ Using the substrate produced in <Preparation of Evaluation Substrate>, a cross section passing through the center of the through hole in the substrate was cut and polished with a precision cutting machine, and the surface state of the cross section was observed with an optical microscope. 200 through holes were observed and the crack resistance was evaluated. The evaluation criteria are as follows. ◎: No cracks occurred ○: Cracks occurred in 1~2 holes △: Cracks occur in holes 2 to 20 ×: Cracks occurred in more than 21 holes The evaluation results are shown in Table 1 below.

<Measurement of glass transition temperature (Tg) and coefficient of thermal expansion (CTE (α1))> Each curable resin composition was applied to the glossy side (copper foil) of GTS-MP foil (manufactured by Furukawa Circuit Foil Co., Ltd.) with an applicator so that the thickness of the coating film before curing would be 100 to 150 μm. ), the curable resin composition is cured by heating at 150° C. for 60 minutes in a hot air circulation drying furnace. The obtained hardened material was peeled off from the copper foil and cut into a measurement size (3 mm×16 mm) to form a measurement sample. TMA measurement was performed on the obtained measurement sample using a thermomechanical analysis device (TMA Q400, manufactured by TA Instruments Japan Inc.). The TMA measurement system uses a test load of 5g to heat the sample from room temperature to 300°C at a heating rate of 10°C/min, and performs two consecutive measurements. The intersection point of two tangent lines with different thermal expansion coefficients for the second time is defined as the glass transition temperature (Tg). Furthermore, the thermal expansion coefficient CTE (α1) in the region lower than the glass transition temperature was calculated.

＜Heat resistance evaluation＞ The heat resistance was evaluated based on the glass transition temperature (Tg) measured in the above manner. The evaluation criteria are as follows. ◎: Tg is 180℃ or above 〇: Tg is 170℃ or more and less than 180℃ △: Tg is 150℃ or more and less than 170℃ ×: Tg is less than 150℃ The evaluation results are shown in Table 1 below.

＜CTE Evaluation＞ Evaluation of CTE was performed based on CTE (α1) measured in the above manner. The evaluation criteria are as follows. ◎：CTE (α1) is less than 20ppm ○: CTE (α1) is 20 ppm or more and less than 30 ppm △: CTE (α1) is 30ppm or more and less than 40ppm ×: CTE(α1) is 40ppm or more The evaluation results are shown in Table 1 below.

＜Evaluation of adhesion to copper plating＞ (Preparation of test substrate for adhesion evaluation) The copper-clad substrate (plate thickness: 1.6 mm) was subjected to copper surface roughening treatment (CZ treatment) (manufactured by MEC Co., Ltd., CZ8101, etching amount: 1.0 μm), and the surfaces of each example and comparative example were hardened by screen printing. The curable resin composition is printed on the whole surface of the treated surface, and the curable resin composition is cured by heating at 110°C for 30 minutes and then at 150°C for 60 minutes in a hot air circulation drying oven. Thereafter, the surface of the hardened product was polished to about 20 μm with High-cut buff #320 to obtain a resin laminated substrate. The surface of the obtained laminated substrate was processed in the following order of roughening treatment (*1), electroless copper plating treatment (*2), and electrolytic copper plating treatment (*3). Next, annealing treatment was performed at 180° C. for 60 minutes in a hot air circulation drying furnace to obtain a test substrate for adhesion evaluation.

(Roughening process (※1)) The resin laminated substrate obtained above (preparation of test substrate for adhesion evaluation) was immersed in commercially available wet permanganate desmear (Swelling Dip Securiganth P, manufactured by Atotech Japan K.K.) at 60°C for 5 minutes ( Swelling treatment), immersed in potassium permanganate (Concentrate Compact CP, manufactured by Atotech Japan K.K.) at 80°C for 10 minutes (roughening treatment), and then immersed in a neutralizing solution (reduction securigant, manufactured by Atotech Japan K.K.) at 40°C P500) for 5 minutes (reduction treatment), and then dried at 100°C for 30 minutes.

(Electrolytic plating treatment (※2)) The roughened resin laminated substrate was subjected to electroless copper plating (Thru-Cup PEA, manufactured by Uemura Industrial Co., Ltd.). The thickness of the electroless copper plating layer formed is about 1 μm.

(Electroplated copper treatment (※3)) The resin laminated substrate on which the electroless copper plating layer was formed was heated at 150° C. for 30 minutes, and then copper sulfate electroplating was performed in the following steps to form an electroless copper plating layer with a thickness of 25 μm on the resin layer.

A cutout with a width of 10 mm and a length of 60 mm was made on the copper-plated layer of the test substrate obtained in the above (Preparation of test substrate for adhesion evaluation), and one end was peeled off and clamped with a clamp, and a desktop tensile test was performed. The peeling strength (N/cm) when the copper plating layer was peeled off to a length of 35 mm was measured with an instrument (AG-X manufactured by Shimadzu Corporation) at an angle of 90 degrees and a speed of 50 mm/minute. The evaluation criteria for adhesion to copper plating are as follows. ◎: Peel strength is 5.0 or more ○: Peel strength is 4.0 or more and less than 5.0 △: Peel strength is 3.0 or more and less than 4.0 ×: Peel strength is less than 3.0 The evaluation results are shown in Table 1 below.

[Table 1]

From the evaluation results in Table 1, it is clear that the curability of an epoxy resin containing at least three types of epoxy resins with different numbers of functional groups or molecular skeleton structures, and including an epoxy resin with two or less functions and an epoxy resin with an aromatic ring with four or more functions Among the resin compositions (Examples 1 to 7), they are excellent in heat resistance, low CTE, and crack resistance, and are also excellent in filling properties and adhesion to copper plating. On the other hand, it is known that as epoxy resins, there are curable resin compositions containing two kinds of epoxy resins but not containing three or more kinds of epoxy resins, and curable resin compositions containing three or more kinds of epoxy resins but not containing four or more functional epoxy resins. In the curable resin composition of aromatic ring epoxy resin (Comparative Examples 1 to 6), heat resistance, low CTE, crack resistance, heat resistance, filling properties, and adhesion to copper plating cannot be well balanced. promote.

without

without

Claims (6)

A curable resin composition, the curable resin composition contains: (A) Epoxy resin, (B) Epoxy resin hardener, and (C) inorganic filler, It is characterized in that the (A) epoxy resin includes at least three kinds of epoxy resins with different functional group numbers or molecular skeleton structures, and the three kinds of epoxy resins at least include an epoxy resin with a functional group number of 2 or less and a functional group number of 4 or more. Epoxy resin with aromatic ring. The curable resin composition according to claim 1, wherein the epoxy resin having an aromatic ring with a functional group number of 4 or more is liquid at room temperature. The curable resin composition according to claim 1 or 2, wherein the (A) epoxy resin further includes an epoxy resin with a functional group number of 3. The curable resin composition according to claim 1 or 2, which contains 10 to 90 mass % of the (C) inorganic filler relative to the total solid content of the curable resin composition. The curable resin composition according to claim 1 or 2, wherein the (C) inorganic filler contains silica. The curable resin composition according to claim 1 or 2 is used as a filling material for through holes or recesses of a printed circuit board.