JP2020076006A - Solventless curable resin composition, cured article and electronic component thereof - Google Patents

Abstract

To provide a curable resin composition for filling steps of conductor wiring circuit height of a printed wiring board, excellent in defoaming property and adhesiveness with a solder resist layer, and excellent in low warpage property.SOLUTION: There is provided a solventless curable resin composition containing (A) a liquid epoxy resin, (B) a liquid flexible epoxy resin, (C) an inorganic filler, and (D) a hardening accelerator.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solventless curable resin composition, and more specifically, to a solventless curable resin composition for filling a step in the height of a conductor wiring circuit of a printed wiring board, and a cured product thereof. The present invention relates to an electronic component to which a cured product is applied.

  Generally, in a printed wiring board used for electronic equipment, etc., when mounting electronic components on the printed wiring board, solder is prevented from adhering to unnecessary portions, and the conductor of the circuit is exposed to prevent oxidation or oxidation. In order to prevent corrosion due to humidity, a solder resist layer is formed in a region other than the connection holes on the substrate on which the circuit pattern is formed.

  By the way, in a printed wiring board used for a large current circuit such as a switching power supply circuit, a thick copper foil clad board is used in consideration of its large electric capacity, and a thick conductor wiring circuit is formed. .. A printed wiring board provided with such a thick conductor wiring circuit has a large step between the substrate surface and the conductor wiring circuit surface, and if the solder resist layer is applied directly on the printed wiring board, the surface of the solder resist layer Since the flatness is impaired, the solder resist layer is applied after the step of the conductor wiring circuit is filled with an insulating resin or the like to make the surface smooth.

  For example, Patent Document 1 proposes to fill the recesses between the conductor wiring circuits with an epoxy resin or the like to form an insulating layer. Further, in Patent Document 2, a thermosetting resin composition was applied on a printed wiring board so as to be equal to or higher than the height of a conductor wiring circuit by 1 to 500 μm, and the thermosetting resin composition was cured. After that, it is proposed to grind the surface of the cured product to adjust it to a desired height.

  Further, in Patent Document 3, in a thick conductor wiring circuit board in which the height of the conductor wiring circuit is 50 to 1000 μm, a solvent-free epoxy is used as an insulating material for filling a step between the substrate surface and the conductor wiring circuit surface. It has been proposed to use a resin or the like and apply the insulating material under reduced pressure.

JP, 2017-177469, A JP, 2004-356202, A JP, 2008-078595, A

  Since the insulating materials described in Patent Documents 1 and 2 are both solvent-based resin compositions containing a curable resin such as an epoxy resin, the insulating material has a large level difference so that the surface of the conductor wiring circuit becomes flat. When it is filled and cured, air bubbles may be mixed in and the insulation reliability may be reduced. In addition to the above-mentioned problem of defoaming property, the solvent-based curable resin also has a problem of insufficient adhesion to the solder resist layer provided on the circuit board.

  On the other hand, the insulating material of Patent Document 3 using the solvent-free resin composition does not have the above-mentioned problem, but when the resin is filled between the conductor wiring circuits on the substrate and cured, the substrate shrinks due to curing shrinkage of the resin. The warp may occur. It is possible to add a filler such as an inorganic filler to the resin composition in order to suppress the curing shrinkage of the resin, but the addition of the filler deteriorates the defoaming property even in a solventless resin composition. Can be considered.

  Therefore, an object of the present invention is to provide a solvent-free curable resin composition for filling a step in the height of a conductor wiring circuit of a printed wiring board, which is excellent in defoaming property and adhesiveness with a solder resist layer, and is low in It is intended to provide a solventless curable resin composition which is also excellent in warpage. Another object of the present invention is to provide a cured product of the solventless curable resin composition and an electronic component to which the cured product is applied.

  In the solventless curable resin composition for filling the step of the conductor wiring circuit height of the printed wiring board, the present inventors have found that when the addition amount of the inorganic filler is increased in order to suppress the curing shrinkage of the resin, Focusing on the fact that the solvent-based curable resin composition causes bubble entrapment and causes bubbles to be mixed, even when the addition amount of the inorganic filler is reduced, two specific epoxy resins as the curable resin component are used. It was found that a solventless curable resin composition excellent in defoaming property and adhesiveness with a solder resist layer and also excellent in low warp property can be realized by using together. The present invention is based on this finding.

That is, the solventless curable resin composition of the present invention,
(A) Liquid epoxy resin,
(B) Liquid flexible epoxy resin,
(C) an inorganic filler,
(D) a curing accelerator,
including.

  According to the embodiment of the present invention, the epoxy equivalent of at least one of the (A) liquid epoxy resin and the (B) liquid flexible epoxy resin is preferably 200 g / eq or more.

  According to an embodiment of the present invention, the liquid flexible epoxy resin (B) is 3 relative to the total amount of the liquid epoxy resin (A) and the liquid flexible epoxy resin (B). It is preferably contained in an amount of -40% by mass.

  Further, according to the embodiment of the present invention, it is preferable that the liquid flexible epoxy resin (B) is a liquid epoxy-modified polybutadiene resin.

  Further, according to an embodiment of the present invention, it is preferable that (E) a wetting and dispersing agent is further included.

  Further, according to an embodiment of the present invention, the (E) wetting and dispersing agent is 0.05 to 3.0 mass relative to the mass of the (C) inorganic filler removed from the solventless curable resin composition. % Is preferably included.

  A cured product according to another aspect of the present invention is obtained by curing the above solventless curable resin composition.

  An electronic component according to another aspect of the present invention has the above-mentioned cured product.

Furthermore, according to an embodiment of the present invention, an electronic component having a wiring circuit having a circuit thickness of 50 μm or more,
The cured product is filled in the depressions formed between the wiring circuits,
It is preferable that a solder resist layer is provided on a part of the surface of the wiring circuit and the surface of the cured product.

  According to the present invention, (A) a liquid epoxy resin and (B) a liquid flexible epoxy resin are used together as resin components, and a solvent-free curable resin composition containing no solvent is used. It is possible to realize a curable resin composition which is excellent in defoaming property and adhesiveness with a solder resist layer and also excellent in low warpage.

Observation of SEM cross section of thermosetting film of Example 2 (500 times) Observation of SEM cross section of thermosetting film of Comparative Example 2 (500 times)

[Solventless curable resin composition]
The solventless curable resin composition according to the present invention contains (A) a liquid epoxy resin, (B) a liquid flexible epoxy resin, (C) an inorganic filler, and (D) a curing accelerator as essential components. .. In the present invention, the “solvent-free system” means that the solvent for dissolving the resin components such as (A) and (B) is not substantially contained. Further, in the present invention, “liquid” means a liquid state having fluidity at 20 ° C. That is, in the solventless curable resin composition of the present invention, since the curable resin component in the liquid state having fluidity at 20 ° C. is used, the system can be substantially solvent-free. Therefore, it does not exclude resin components other than liquid (for example, solid or semi-solid resin components at 20 ° C.), and even the above-mentioned solid or semi-solid resin components at 20 ° C. As long as it is compatible with the liquid epoxy resin (A) or the liquid flexible epoxy resin (B), it may be contained in the solventless curable resin composition of the present invention. Hereinafter, each component constituting the solventless curable resin composition according to the present invention will be described.

<(A) Liquid epoxy resin>
The solventless curable resin composition according to the present invention contains (A) a liquid epoxy resin as an essential component. As the liquid epoxy resin, among known and commonly used compounds having one or more epoxy groups, those which are in a liquid state having fluidity at 20 ° C. can be used without particular limitation. The compounds having the above epoxy groups can be preferably used. For example, monoepoxy compounds such as butyl glycidyl ether, phenyl glycidyl ether, glycidyl (meth) acrylate, bisphenol A type epoxy resin, bisphenol S type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin Alicyclic epoxy resin, trimethylolpropane polyglycidyl ether, phenyl-1,3-diglycidyl ether, biphenyl-4,4′-diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol or propylene glycol. Examples of compounds having two or more epoxy groups in one molecule, such as diglycidyl ether, sorbitol polyglycidyl ether, tris (2,3-epoxypropyl) isocyanurate, and triglycidyl tris (2-hydroxyethyl) isocyanurate. Be done. These may be used alone or in combination of two or more according to the required characteristics. Among these, from the viewpoint of making the effect of the present invention more remarkable, bisphenol A type epoxy resin and its hydrogenated product, bisphenol F type epoxy resin and its hydrogenated product, alicyclic epoxy resin, phenol A novolac type epoxy resin, a glycidyl amine type epoxy resin and the like can be preferably used, and particularly preferably, a bisphenol A type epoxy resin and its hydrogenated product, and a bisphenol F type epoxy resin and its hydrogenated product are used. You can

  Specific examples of the liquid epoxy resin having fluidity at 20 ° C. include JER828 manufactured by Mitsubishi Chemical Co., YD-127, YD-128 manufactured by Nippon Steel & Sumikin Co., Ltd., and Huntsman Japan Co., Ltd. Bisphenol A type epoxy resin such as Araldite GY240, Araldite GY250, Araldite GY260, Araldite GY261, Araldite GY266, Araldite GY2600 (all are trade names), Epicron 840 and Epicron 850 (all trade names) manufactured by DIC Corporation; Sumikin Co., Ltd. YDF-170, YDF-175 (both are trade names) hydrogenated bisphenol A type epoxy resin; DIC Corporation Epicron 830, Epicron 830-S, Epicron 835, Mitsubishi Chemical Corporation Bisphenol F type epoxy resin such as JER807 (trade name) manufactured by Nippon Steel Co., Ltd. ST-3000 (trade name) hydrogenated bisphenol A type epoxy resin manufactured by Nippon Steel & Sumikin Co., Ltd .; Celoxide side 2021 manufactured by Daicel Corporation, Asahi Kasei Epoxy Co., Ltd. Alicyclic CY175, CY179 etc. (both are trade names) alicyclic epoxy resin manufactured by the company; JER152 manufactured by Mitsubishi Chemical Co., Ltd., Epicron N-730 manufactured by DIC Co. (both trade names) and other phenol novolac type epoxies Resins: JER604 (trade name) glycidyl amine type epoxy resin manufactured by Mitsubishi Chemical Co., Ltd., and the like.

  In the present invention, among the above liquid epoxy resins, bisphenol A type epoxy resin and bisphenol F type epoxy resin, or hydrogenated products thereof can be particularly preferably used. The bisphenol A type epoxy resin is preferably 20 to 70% by mass, and more preferably 30 to 60% by mass, based on the total amount of (A) liquid epoxy resin and (B) liquid flexible epoxy resin. .. When the blended amount of the liquid bisphenol A type epoxy resin is within the above range, the defoaming property of the resin composition and the cured film properties when the cured product is maintained while maintaining the heat resistance of the cured product. Can be compatible with both.

  The bisphenol F type epoxy resin is preferably 10 to 40% by mass, and preferably 15 to 30% by mass, based on the total amount of (A) liquid epoxy resin and (B) liquid flexible epoxy resin. More preferably. When the compounding amount of the liquid bisphenol F type epoxy resin is within the above range, both the defoaming property as the resin composition and the cured film property when it is a cured product can be achieved.

  Further, the liquid epoxy resin preferably has an epoxy equivalent of 200 g / eq or more, from the viewpoint of toughness of a cured product obtained by curing a solventless curable resin composition, and 200 to 500 g / eq. Is more preferable.

<(B) Liquid flexible epoxy resin>
The solventless curable resin composition of the present invention contains a liquid flexible epoxy resin in addition to the above-mentioned epoxy resin. As described above, in the case of a solventless curable resin composition, if the addition amount of the inorganic filler is increased too much in consideration of the curing shrinkage of the resin, so-called bubble biting may occur and the defoaming property may deteriorate. Be done. In the present invention, by adding a liquid flexible epoxy resin, it is possible to achieve both defoaming property and low warpage without increasing the addition amount of the inorganic filler more than necessary, and as a result, defoaming property and The present invention realizes a solventless curable resin composition which is excellent in adhesiveness with a solder resist layer and is also excellent in low warpage. The reason for this is not clear, but it is considered as follows.

  When a liquid epoxy resin and a liquid flexible epoxy resin are used in combination as the curable resin component, the liquid epoxy resin is not completely compatible due to the difference in properties between the two, and when the resin is cured, the liquid epoxy resin is A so-called "sea-island structure" is formed in which the cured epoxy resin is dispersed in the cured continuous phase. The liquid epoxy resin shrinks when it cures, but the cured part of the liquid flexible epoxy resin absorbs or disperses the shrinkage, so that it is possible to suppress the cure shrinkage when the resin composition as a whole is cured. It is considered possible.

  In the present invention, the liquid flexible epoxy resin is an epoxy resin having a property of having both flexibility and strength among the epoxy resins other than the above-mentioned “(A) liquid epoxy resin” and having a temperature of 20 ° C. Means a liquid state having fluidity. For example, ε-caprolactone modified epoxy resin, thiol epoxy resin, butadiene epoxy resin, aliphatic epoxy resin, phenoxy epoxy resin, rubber modified epoxy resin, amine modified epoxy resin, epoxidized polyene, dimer acid modified epoxy resin. , Polypropylene glycol diglycidyl ether, and the like. Among these, butadiene-based epoxy resin, epoxidized polyene, aliphatic epoxy resin, dimer acid-modified epoxy resin, polypropylene glycol diglycidyl ether and the like can be preferably used. ..

  The butadiene-based epoxy resin and the epoxidized polyene are those having a double bond in the residue of the polymer and a part of which is epoxidized. For example, a copolymerized polyene having a butadiene structure such as epoxidized polybutadiene. Examples of the epoxidized product, epoxidized copolymerized polyene having an isoprene structure such as epoxidized polyisoprene, and epoxidized natural rubber. Specific examples of such compounds include PB3600 and PB4700 manufactured by Daicel Corporation, JP-100 and JP-200 manufactured by Nippon Soda Co., Ltd., BF-1000 manufactured by ADEKA CORPORATION, and YX7400 series manufactured by Mitsubishi Chemical Corporation. Is mentioned.

  The dimer acid-modified epoxy resin is an epoxy resin modified with dimer acid, and is obtained by reacting at least one carboxyl group in the dimer acid structure with the epoxy resin. Specific examples of such a compound include JER871 manufactured by Mitsubishi Chemical Corporation.

  Specific examples of polypropylene glycol diglycidyl ether include EP-4000S, EP-4000L, EP-4003S, EP-4010S, and EP-4010L manufactured by ADEKA Corporation.

  Further, as a liquid flexible epoxy resin, an epoxy resin obtained by reacting a difunctional phenol compound with a difunctional aliphatic epoxy compound obtained by reacting a dihydric alcohol with epihalohydrin can be preferably used. Specific examples of such a compound include YX7100 series manufactured by Mitsubishi Chemical Corporation. Further, as the flexible and tough epoxy resin, EXA-4850 series commercially available from DIC Co., Ltd. can also be preferably used.

  Among the liquid flexible epoxy resins described above, the epoxy-modified polybutadiene resin can be preferably used from the viewpoint of compatibility with the liquid epoxy resin (A) and low warpage.

  From the viewpoint of suppressing the warp of the cured product, the above-mentioned flexible epoxy resin preferably has an epoxy equivalent of 200 g / eq or more, and more preferably 200 to 2000 g / eq.

  From the viewpoint of further enhancing the effect of the present invention, the compounding amount of the flexible epoxy resin is 3 with respect to the total amount of A) the liquid epoxy resin and (B) the liquid flexible epoxy resin. -40 mass% is preferred, and 15-40 mass% is more preferred.

<(C) Inorganic filler>
The solventless curable resin composition of the present invention contains (C) an inorganic filler as a filler for adjusting stress relaxation and linear expansion coefficient due to curing shrinkage and increasing the physical strength of the cured product. As the inorganic filler, a known inorganic filler used in ordinary resin compositions can be used. Specifically, for example, silica, barium sulfate, calcium carbonate, silicon nitride, aluminum nitride, boron nitride, alumina, magnesium oxide, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica, talc, non-metals such as organic bentonite. Examples thereof include fillers and metal fillers such as copper, gold, silver, palladium and silicone. These inorganic fillers may be used alone or in combination of two or more.

  Among these inorganic fillers, calcium carbonate, silica, barium sulfate, and aluminum oxide, which are excellent in low hygroscopicity and low volume expansion, are preferably used, and silica and calcium carbonate are more preferably used. The silica may be amorphous, crystalline, or a mixture thereof. Amorphous (fused) silica is particularly preferable. The calcium carbonate may be either natural heavy calcium carbonate or synthetic precipitated calcium carbonate.

  The shape of the inorganic filler is not particularly limited, and examples thereof include spheres, needles, plates, scales, hollows, irregular shapes, hexagons, cubics, flakes, and the like. From the viewpoint, spherical shape is preferable.

  Further, the average particle size of these inorganic fillers is 0.1 μm to 25 μm, preferably considering the dispersibility of the inorganic filler, the filling property into the hole, the smoothness when the wiring layer is formed in the filled part, and the like. A range of 0.1 μm to 15 μm is suitable. More preferably, it is 1 μm to 10 μm. The average particle diameter means an average primary particle diameter, and the average particle diameter (D50) can be measured by a laser diffraction / scattering method.

  The blending ratio of the inorganic filler is such that the above-mentioned (A) liquid epoxy resin and (B) liquid can be used from the viewpoints of the thermal expansion coefficient, defoaming property, adhesiveness, printability, filling property, etc. of the cured product. It is preferably 50 to 150% by mass, and more preferably 70 to 130% by mass, based on the total amount of the flexible epoxy resin.

  To the solventless curable resin composition of the present invention, a filler treated with a fatty acid for imparting thixotropy or an amorphous filler such as organic bentonite or talc can be added.

The fatty acid is represented by the general formula: (R1COO) _n- R2 (the substituent R1 is a hydrocarbon having 5 or more carbon atoms, the substituent R2 is hydrogen or a metal alkoxide, a metal, and n is 1 to 4). The compounds represented can be used. When the substituent R1 has 5 or more carbon atoms, the fatty acid can exert an effect of imparting thixotropy. More preferably, n is 7 or more.

  The fatty acid may be an unsaturated fatty acid having a double bond or a triple bond in the carbon chain, or may be a saturated fatty acid not containing them. For example, stearic acid (the number of carbon atoms and the number of unsaturated bonds, and the number in the parentheses is a numerical expression according to the position. 18: 0), hexanoic acid (6: 0), oleic acid (18: 1 (9)), icosane Examples thereof include acid (20: 0), docosanoic acid (22: 0), and melissic acid (30: 0). The substituent R1 of these fatty acids preferably has 5 to 30 carbon atoms. More preferably, it has 5 to 20 carbon atoms. In addition, for example, a skeleton having a long fatty acid chain (having 5 or more carbon atoms) with a coupling agent structure, such as a metal alkoxide in which the substituent R2 is a titanate substituent capped with an alkoxyl group, is used. It may be. For example, KR-TTS (trade name) manufactured by Ajinomoto Fine Techno Co., Ltd. can be used. In addition, metal soaps such as aluminum stearate and barium stearate can be used. As the metal element used for the metallic soap, calcium, zinc, lithium, magnesium, sodium and the like can be used in addition to aluminum.

  From the viewpoint of thixotropy, embedding property, defoaming property, etc., the proportion of the fatty acid to be incorporated is preferably 0.1 to 2 mass% with respect to the inorganic filler.

  The fatty acid may be blended by using an inorganic filler that has been surface-treated with a fatty acid in advance, and it becomes possible to more effectively impart thixotropy to the solventless curable resin composition. In this case, the blending ratio of the fatty acid can be reduced as compared with the case of using the untreated filler, and when all the inorganic fillers are the fatty acid-treated fillers, the blending ratio of the fatty acid is 0.1 to 1 with respect to the inorganic filler. It is preferably set to mass%.

  Further, the solventless curable resin composition of the present invention may contain a silane coupling agent. By blending the silane coupling agent, it becomes possible to improve the adhesion between the inorganic filler and the epoxy resin and suppress the occurrence of cracks in the cured product.

  Examples of the silane coupling agent include epoxysilane, vinylsilane, imidazolesilane, mercaptosilane, methacryloxysilane, aminosilane, styrylsilane, isocyanatesilane, sulfidesilane, and ureidosilane. The silane coupling agent may be blended by using an inorganic filler which has been surface-treated with the silane coupling agent in advance.

  The blending ratio of the silane coupling agent is from 0.05 to 2.5 parts by mass with respect to 100 parts by mass of the inorganic filler from the viewpoint of achieving both good adhesion and defoaming property between the inorganic filler and the epoxy resin. Is preferred.

<(D) Curing accelerator>
The solventless curable resin composition of the present invention contains (A) a liquid epoxy resin and (B) a liquid flexible epoxy resin for curing. As the curing accelerator, well-known and commonly used curing accelerators for curing an epoxy resin can be used. For example, amines, imidazoles, polyfunctional phenols, acid anhydrides, isocyanates, imidazole adducts, etc. There are imidazole latent curing accelerators, and polymers containing these functional groups, and a plurality of them may be used if necessary. Examples of amines include dicyandiamide and diaminodiphenylmethane. Examples of imidazoles include alkyl-substituted imidazoles and benzimidazoles. Examples of polyfunctional phenols include hydroquinone, resorcinol, bisphenol A and halogen compounds thereof, as well as novolak, which is a condensate with aldehyde, and resole resin. Examples of acid anhydrides include phthalic anhydride, hexahydrophthalic anhydride, methylnadic acid anhydride, and benzophenonetetracarboxylic acid. Examples of the isocyanates include tolylene diisocyanate and isophorone diisocyanate, and those obtained by masking this isocyanate with phenols may be used. These curing accelerators may be used alone or in combination of two or more.

  Among the above-mentioned curing accelerators, amines and imidazoles can be preferably used from the viewpoints of adhesion, storage stability, and heat resistance to the insulating portion and the conductor wiring circuit of electronic components such as a printed wiring board. .. Adduct compounds of aliphatic polyamines such as C2-C6 alkylenediamines, C2-C6 polyalkylenepolyamines, C8-C15 aromatic ring-containing aliphatic polyamines, or isophoronediamine, 1,3-bis An alicyclic polyamine adduct compound such as (aminomethyl) cyclohexane, or a mixture containing an adduct compound of the aliphatic polyamine and the adduct compound of the alicyclic polyamine as a main component is preferable. In particular, a curing accelerator containing an adduct compound of xylylenediamine or isophoronediamine as a main component is preferable.

  As the adduct compound of the aliphatic polyamine, those obtained by subjecting the aliphatic polyamine to an addition reaction with aryl glycidyl ether (particularly phenyl glycidyl ether or tolyl glycidyl ether) or alkyl glycidyl ether are preferable. Further, as the alicyclic polyamine adduct compound, those obtained by addition-reacting the alicyclic polyamine with n-butyl glycidyl ether, bisphenol A diglycidyl ether and the like are preferable.

  Examples of the aliphatic polyamine include alkylenediamine having 2 to 6 carbon atoms such as ethylenediamine and propylenediamine, polyalkylenepolyamine having 2 to 6 carbon atoms such as diethylenetriamine and triethylenetriamine, and aromatic ring-containing fat having 8 to 15 carbon atoms such as xylylenediamine. Group polyamine and the like can be mentioned. Examples of commercial products of modified aliphatic polyamines include FXE-1000 or FXR-1020, Fujicure FXR-1030, Fujicure FXR-1080, FXR-1090M2 (both trade names, manufactured by Fuji Kasei Kogyo Co., Ltd.), Ankamine 2089K. , Sunmide P-117, Sunmide X-4150, Ancamine 2422, Surwet R, Sunmide TX-3000, Sunmide A-100 (any trade name, manufactured by Air Products Japan Co., Ltd.) and the like.

  Examples of the alicyclic polyamine include isophorone diamine, 1,3-bis (aminomethyl) cyclohexane, bis (4-aminocyclohexyl) methane, norbornene diamine, 1,2-diaminocyclohexane, laromine and the like. Examples of 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, Ancamine 2228 (all are trade names. , Air Products Japan Co., Ltd.), Daito Clar F-5197, Daito Clar B-1616 (all are trade names, Daito Sangyo Co., Ltd.), Fujicure FXD-821, Fujicure 4233 (both are trade names, Fuji Kasei Kogyo Co., Ltd. Company), jER Cure 113 (trade name, manufactured by Mitsubishi Chemical Co., Ltd.), Laromin C-260 (trade name, manufactured by BASF Japan Co., Ltd.) and the like. Other examples of the polyamine type curing accelerator include EH-5015S (trade name, manufactured by ADEKA Co., Ltd.).

  Examples of imidazoles include a reaction product of an epoxy resin and imidazole. For example, 2-methylimidazole, 4-methyl-2-ethylimidazole, 2-phenylimidazole, 4-methyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 1 -Cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole and the like can be mentioned. Examples of commercially available imidazoles include imidazoles of 2E4MZ, C11Z, C17Z, 2PZ (all are trade names, these are reaction products of epoxy resin and imidazole), 2MZ-A, 2E4MZ-A, 2MZA-PW ( Any trade name, these are AZINE (azine) compounds of imidazole), 2MZ-OK, 2PZ-OK (any trade name, these are isocyanurate of imidazole), 2PHZ, 2P4MHZ (all are trade names, these are imidazole). (Hydroxymethyl form) (all of these are manufactured by Shikoku Chemicals Co., Ltd.) and the like. Examples of commercially available imidazole-type latent curing accelerators include Curesol P-0505 (trade name, manufactured by Shikoku Chemicals Co., Ltd.). The curing accelerator used in combination with the imidazole is preferably a modified aliphatic polyamine, a polyamine type curing accelerator, or an imidazole type latent curing accelerator.

  Among the above curing accelerators, from the viewpoint of storage stability of the solventless curable resin composition, at least two or more of the above curing accelerators may be contained, and one of them may be an imidazole. Good. Further, from the viewpoint of suppressing cracks and delamination, it is preferable that at least one of polyamine and indazole latent curing accelerator is contained. When it contains imidazoles, it is preferable to contain two or more imidazoles.

<(E) Wetting and dispersing agent>
The solventless curable resin composition of the present invention may contain any component other than the components (A) to (D) described above. For example, a wetting dispersant may be included so that (A) liquid epoxy resin and (B) liquid flexible epoxy resin and (C) inorganic filler are uniformly dispersed. Since the aggregation of the inorganic filler is suppressed by the action of the wetting and dispersing agent, the fluidity of the solventless curable resin composition is increased and the defoaming property is improved.

  As the wetting dispersant, known wetting dispersants can be used without particular limitation, and examples thereof include a copolymer containing an acid group, a pigment-affinity block copolymer, a phosphoric acid ester compound, and a polyether phosphoric acid ester. System compounds, fatty acid ester compounds, alkylene oxide copolymers, modified polyether polymers, fatty acid derivatives, urethane polymers and the like. Specific examples include DISKER BYK (registered trademark) series manufactured by BYK. Examples thereof include EFKA (registered trademark) series manufactured by BASF, SOLSPERSE (registered trademark) series manufactured by Lubrizol Japan, Disparlon series manufactured by Kusumoto Kasei Co., and Flowlen series manufactured by Kyoeisha Kagaku.

  The amount of the wetting dispersant compounded is preferably 0.05 to 3.0% by mass, and 0.1 to 2% by mass based on the mass of the solventless curable resin composition excluding the inorganic filler (C). It is more preferably 0.0% by mass, and further preferably 0.1 to 0.5% by mass. From the viewpoint of improving the dispersibility of the inorganic filler, it can be said that the larger the blending amount of the wetting dispersant, the more preferable, but from the perspective of forming a sea-island structure, the blending amount of the wetting dispersant is preferably within the above range.

  Further, the solventless curable resin composition of the present invention may be blended with other additives known and commonly used in the field of electronic materials. Other additives include thermal polymerization inhibitors, ultraviolet absorbers, plasticizers, flame retardants, antistatic agents, antiaging agents, antibacterial and antifungal agents, defoaming agents, leveling agents, fillers, thickeners, Adhesion-imparting agents, thixotropic agents, colorants, photoinitiating aids, sensitizers, release agents, surface treatment agents, dispersion aids, surface modifiers, stabilizers, phosphors and the like can be mentioned.

<Cured product>
The above-mentioned solventless curable resin composition is preferably used for manufacturing electronic parts such as printed wiring boards, and more preferably for electronic parts such as printed wiring boards having a wiring circuit having a circuit thickness of 50 μm or more. It can be used as an insulating material for filling the depressions formed between wiring circuits. The solventless curable resin composition of the present invention can be applied to the above-mentioned electronic component, filled in the depressions formed between the wiring circuits, and then cured by heating to obtain a cured product.

  The method for applying the solventless curable resin composition is not particularly limited, and includes a dip coating method, a flow coating method, a roll coating method, a bar coater method, a screen printing method, a curtain coating method, an inkjet coating method, a dispense method. Various methods such as a method can be applied. The viscosity suitable for coating is preferably 250 to 800 dPa · s (rotary viscometer 5 rpm, 25 ° C.).

  Curing of the solventless curable resin composition can be carried out by heating at 60 to 220 ° C. for 20 to 120 minutes, and a hot air circulation drying furnace, an IR furnace, a hot plate, a convection oven, etc. It is possible to use a method in which hot air in the dryer is brought into countercurrent contact with a device equipped with a heat source and a method in which the hot air is blown onto the support from a nozzle).

<Electronic parts>
The solventless curable resin composition of the present invention is used as an insulating material for filling a recess formed between wiring circuits of an electronic component such as a printed wiring board having a wiring circuit having a circuit thickness of 50 μm or more as described above. Can be used, but the solventless curable resin composition is filled in the depressions formed between the wiring circuits and then cured to form a cured product, and the cured product surface is subjected to treatment such as grinding as necessary. This improves the flatness of the surface of the wiring circuit of the electronic component. In the present invention, a solder resist layer may be provided on a part of the wiring circuit surface of the electronic component and the surface of the cured product. In the present invention, as described above, since the solvent-free curable resin composition contains (A) liquid epoxy resin and (B) liquid flexible epoxy resin as resin components, the surface of the cured product is It is possible to obtain an electronic component having high adhesiveness with the solder resist layer and high durability. Further, when it is a cured product, it forms a "sea-island structure" in which the resin component (A) liquid epoxy resin and (B) liquid flexible epoxy resin are appropriately compatible. It is possible to realize low warpage of the obtained electronic component.

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

[Preparation of solventless curable resin composition]
The components shown in Table 2 below are blended, stirred, kneaded and dispersed in a three-roll mill, and the curable resin compositions of Examples 1 to 10 and Comparative Examples 1 and 2 have viscosities of 250 to 800 dPa · s (rotation). Viscometer 5 rpm, 25 ° C) was adjusted.

In addition, * 1- * 13 in the following Table 2 represent the following components.
* 1: EPOX-MK R710: manufactured by Printec Co., Ltd. (bisphenol E type epoxy resin, epoxy equivalent 160 to 180 g / eq, liquid)
* 2: JER828: Mitsubishi Chemical Corporation (bisphenol A type epoxy resin, epoxy equivalent 184 to 194 g / eq, liquid)
* 3: JER807: Mitsubishi Chemical Corp. (bisphenol F type epoxy resin, epoxy equivalent 160-175 g / eq, liquid)
* 4: JER630: manufactured by Mitsubishi Chemical Co. (para-aminophenol type liquid epoxy resin (polyfunctional epoxy resin), epoxy equivalent 90 to 105 g / eq, liquid)
* 5: Eporide PB4700: manufactured by Daicel Corporation (epoxidized polybutadiene resin, epoxy equivalent 152-178 g / eq, liquid)
* 6: Eporide PB3600: manufactured by Daicel (epoxidized polybutadiene resin, epoxy equivalent 200 g / eq, liquid)
* 7: YX7105: manufactured by Mitsubishi Chemical Corporation (flexible epoxy resin, epoxy equivalent 480 g / eq, liquid)
* 8: Softon 1800: Bihoku Powder Co., Ltd., calcium carbonate CaCO ₃ (average particle size 1.25 μm)
* 9: Softon 2600: Calcium carbonate CaCO ₃ (average particle size 0.85 μm) manufactured by Bihoku Powder Co., Ltd.
* 10: 2MZ-AP: manufactured by Shikoku Chemicals (Imidazole-based epoxy resin curing agent)
* 11: SOLSPERSE 21000: Lubrizol Japan (wetting and dispersing agent)
* 12: EFKA 2580: BASF Japan Ltd. (antifoaming agent, modified polydimethylsiloxane)
* 13: DPM: solvent, dipropylene glycol methyl ether

[Evaluation of solventless curable resin composition]
(1) Fabrication of L / S (Line & Space) Evaluation Substrate Copper thickness 200 μm, both sides where a comb-tooth pattern circuit of L (line: wiring width) / S (space: interval width) = 50/50 μm is formed As a pretreatment, the printed wiring board was subjected to an etching treatment corresponding to 0.5 μm by CZ-8101 treatment manufactured by MEC.
Next, the curable resin compositions of Examples 1 to 10 and Comparative Examples 1 and 2 obtained above were printed on one surface of the double-sided printed wiring board by the screen printing method under the following printing conditions.
<Printing conditions>
Squeegee: Squeegee thickness 20 mm, hardness 70 °, diagonal polishing: 23 °
Plate: PET100 mesh bias plate Printing pressure: 50 kg, squeegee speed 30 mm / Sec
Squeegee angle: 80 °

  A double-sided printed wiring board on which each curable resin composition is printed is placed in a hot-air circulation type drying oven and heat-cured at 100 ° C for 30 minutes, and then the set temperature of the hot-air circulation type drying oven is set to 150 ° C. Then, the curable resin composition was cured by performing heat curing for 60 minutes after reaching 150 ° C. to obtain an evaluation substrate.

(2) Evaluation of Fillability (Printability) The evaluation substrate obtained as described above is cut into a width of 2 cm × 2 cm with a precision cutting machine and polished to fill the bottoms of the lines and spaces with the resin composition without gaps. It was evaluated whether or not (printing) was completed. The evaluation was performed by observing the cross section of 10 evaluation substrates by SEM (scanning electron microscope, JSM-7600F manufactured by JEOL Ltd.). The SEM was observed with a backscattered electron composition image at an acceleration voltage of 30 kV and a measurement magnification of 500 times. The evaluation criteria are as follows.
◯: No unfilled ×: One or more unfilled portions were present The evaluation results are shown in Table 2 below.

(3) Evaluation of defoaming property The evaluation substrate obtained as described above was cut into a piece having a width of 2 cm × 2 cm with a precision cutting machine and polished, and the state of the cross section was observed with an optical microscope to confirm that bubbles (voids) were hot. It was evaluated with 10 evaluation substrates whether or not they remained without being removed during curing. The evaluation criteria are as follows.
○: 1-3 voids were confirmed.
X: Four or more voids were confirmed.
The evaluation results were as shown in Table 2 below.

(4) Evaluation of Warp On a copper clad laminate having a thickness of 200 μm and a size of 100 × 100 mm (MCL-E-770G, Hitachi Chemical Co., Ltd., copper thickness 18 μm, CZ-8101 was used as a pretreatment, and an etching treatment equivalent to 1 μm was applied). The curable resin compositions of Examples 1 to 10 and Comparative Examples 1 and 2 obtained above were printed by the screen printing method under the following printing conditions.
<Printing conditions>
Squeegee: Squeegee thickness 20 mm, hardness 70 °, diagonal polishing: 23 °
Plate: PET100 mesh bias plate Printing pressure: 50 kg, squeegee speed 30 mm / Sec
Squeegee angle: 80 °
Subsequently, the copper-clad laminate printed with the curable resin composition is placed in a hot air circulation type drying oven and heat cured at 100 ° C. for 30 minutes, and then the set temperature of the hot air circulation type drying oven is set to 150. The temperature was set to 150 ° C., and after reaching 150 ° C., thermosetting was performed for 60 minutes to cure the curable resin composition, thereby obtaining an evaluation substrate.

The obtained evaluation board was evaluated according to the following criteria by measuring the amount of warpage at the four corners of the board using calipers.
⊚: Maximum warp value is less than 10 mm ○: Maximum warp value is 10 mm or more and less than 20 mm ×: Maximum warp value is 20 mm or more The evaluation results are shown in Table 2 below.

(5) Confirmation of Sea-Island Structure Expression As a pretreatment, a circuit-formed substrate (500 mm × 600 mm × 0.4 mmt (thickness)) was subjected to etching treatment equivalent to 0.5 μm by CZ-8101 treatment manufactured by MEC. The curable resin compositions of Examples 1 to 10 and Comparative Examples 1 and 2 obtained above were printed on the treated surface of the substrate by the screen printing method under the following printing conditions.
<Printing conditions>
Squeegee: Squeegee thickness 20 mm, hardness 70 °, diagonal polishing: 23 °
Plate: PET100 mesh bias plate Printing pressure: 50 kg, squeegee speed 30 mm / Sec
Squeegee angle: 80 °
Subsequently, the substrate on which the curable resin composition is printed is placed in a hot-air circulation type drying oven and heat-cured at 100 ° C. for 30 minutes, and then the set temperature of the hot-air circulation type drying oven is set to 150 ° C. Then, the curable resin composition was cured by performing heat curing for 60 minutes after reaching 150 ° C. to obtain an evaluation substrate.

The obtained evaluation substrate was cut into a piece having a width of 2 cm × 2 cm with a precision cutting machine, polished, and the cross section of the thermosetting film was observed to evaluate whether the sea-island structure was developed. The evaluation was performed by observing the cross section of 10 evaluation substrates by SEM (scanning electron microscope, JSM-7600F manufactured by JEOL Ltd.). The SEM was observed with a backscattered electron composition image at an acceleration voltage of 30 kV and a measurement magnification of 500 times. The evaluation criteria are as follows.
◯: Sea-island structure on cross section of thermoset film x: No sea-island structure on cross section of thermoset film The evaluation results are shown in Table 2 below. 1 and 2 show the results of SEM cross-section observation (500 times) of thermosetting films using the solventless curable resin compositions of Example 2 and Comparative Example 2, respectively.

(6) Adhesion with solder resist layer <Preparation of photo- and thermosetting resin composition>
First, each component was mixed in the proportions (parts by mass) shown in Table 1 above, stirred for 15 minutes with a stirrer, premixed, and then kneaded with a three-roll mill to form a light for forming a solder resist layer. -A thermosetting resin composition was prepared.

In addition, A in Table 1 represents an alkali-soluble resin solution prepared as follows.
<Alkali-soluble resin solution>
In an autoclave equipped with a thermometer, a nitrogen introducing device and an alkylene oxide introducing device, and a stirring device, 119.4 g of novolac type cresol resin (manufactured by Showa Denko KK, trade name "Shaunol CRG951", OH equivalent: 119.4), water 1.19 g of potassium oxide and 119.4 g of toluene were added, the system was replaced with nitrogen while stirring, and the temperature was raised by heating.
Next, 63.8 g of propylene oxide was gradually dropped from the above alkylene oxide introducing device, and reacted at 125 to 132 ° C. and 0 to 4.8 kg / cm 2 for 16 hours.
Thereafter, 1.56 g of 89% phosphoric acid was added to and mixed with the reaction solution cooled to room temperature to neutralize potassium hydroxide, and the solid content was 62.1% and the hydroxyl value was 182.2 g / eq. A propylene oxide reaction solution of the novolac type cresol resin was obtained. This was an average of 1.08 mol of alkylene oxide added per equivalent of the phenolic hydroxyl group.

  The obtained alkylene oxide reaction solution of novolac type cresol resin (293.0 g), acrylic acid (43.2 g), methanesulfonic acid (11.53 g), methylhydroquinone (0.18 g) and toluene (252.9 g) were stirred, a thermometer and an air blowing tube. Was added to the reactor equipped with, and air was blown at a rate of 10 ml / min, and the mixture was reacted at 110 ° C. for 12 hours while stirring.

  The water produced by the reaction was distilled out as an azeotropic mixture with toluene, and the amount was 12.6 g. Thereafter, the obtained reaction solution was cooled to room temperature, neutralized with 35.35 g of a 15% sodium hydroxide aqueous solution, and then washed with water. Then, toluene was distilled off while substituting 118.1 g of diethylene glycol monoethyl ether acetate with an evaporator to obtain a novolac type acrylate resin solution.

    Next, 332.5 g of the resulting novolac type acrylate resin solution and 1.22 g of triphenylphosphine were charged into a reactor equipped with a stirrer, a thermometer and an air blowing tube, and air was blown at a rate of 10 ml / min, While stirring, 60.8 g of tetrahydrophthalic anhydride was gradually added, and the mixture was reacted at 95 to 101 ° C for 6 hours. An alkali-soluble resin solution having a solid acid value of 88 mgKOH / g and a solid content of 71% was obtained.

Further, * 1 to * 6 in the above Table 1 represent the following components.
* 1: Irgacure OXE02 (ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime), manufactured by BASF Japan Ltd.)
* 2: jER828 (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 184-194 g / eq, liquid)
* 3: DPHA (dipentaerythritol hexaacrylate, manufactured by Nippon Kayaku Co., Ltd.)
* 4: C.I. I. Pigment Blue 15: 3
* 5: C.I. I. Pigment Yellow 147
* 6: SO-C2 (Silica SiO ₂ , manufactured by Admatechs Co., Ltd., D50 = 0.5 μm)

<Production of dry film>
The photo-thermosetting resin composition obtained as described above is applied onto a PET film (carrier film 38 μm) by using a lip coater, dried at a temperature of 80 ° C. for 10 minutes, and has a thickness of 15 μm. The thermosetting resin composition layer was formed on the carrier film. Next, a protective film (polypropylene film) was laminated on the light / thermosetting resin composition layer to obtain a laminated structure.

<Production of evaluation board>
The surface of the evaluation substrate obtained in “(1) Fabrication of L / S (line & space) evaluation substrate” on which the thermosetting film is formed is subjected to physical polishing by buffing until the copper circuit is exposed. did.
Next, the protective film of the dry film obtained above was peeled off, and the light / thermosetting resin layer side was attached so as to contact the polished surface of the evaluation substrate, and the batch type vacuum pressure laminator MVLP-500 (a famous machine (Manufactured by Mfg. Co., Ltd.) was heat-laminated under the conditions of pressure degree: 0.5 MPa, 80 ° C., 1 minute, and vacuum degree: 133.3 Pa to obtain an evaluation substrate having a dry film.

Next, after exposing the curable resin layer on the dry film carrier film through an exposure mask having a negative pattern of 80 μm in diameter using an exposure device equipped with a high-pressure mercury lamp (short arc lamp), the carrier film was peeled off. did. Thereafter, a 1 wt% Na ₂ CO ₃ aqueous solution at 30 ° C. was developed for 60 seconds under a spray pressure of 2 kg / cm ² .

Then, 1000 mJ / cm < ² > exposure was performed with the high pressure mercury lamp irradiation device. Then, the dry film was completely cured by heat curing at 180 ° C. for 60 minutes in a hot air circulation type drying furnace to obtain a resist pattern layer.

<Cross cut test>
With respect to the evaluation substrate on which the resist pattern layer was formed as described above, cross-cuts were inserted in a grid pattern according to the test method of JIS D 0202, and a peel test with an adhesive tape was performed to evaluate the peeling of the resist pattern layer. The criteria for judgment are as follows.
◯: No peeling was observed at all x: Peeling in the thermosetting resin layer The evaluation results are shown in Table 2 below.

(7) Measurement of glass transition temperature (Tg) and coefficient of thermal expansion (CTE (α1)) GTS-MP foil (manufactured by Furukawa Circuit Foil Co., Ltd.) was applied to the glossy side (copper foil) obtained above. The curable resin compositions of Examples 1 to 10 and Comparative Examples 1 and 2 were applied with an applicator, heated in a hot air circulation drying furnace at 100 ° C for 30 minutes, and then cured at 150 ° C for 60 minutes.

Subsequently, the cured product was peeled off from the copper foil, and a sample was cut into a measurement size (size of 3 mm × 10 mm), and the sample was subjected to a thermomechanical analyzer (TMA6100 manufactured by Seiko Instruments Inc.). In the TMA measurement, the test load was 5 g, and the sample was heated from room temperature at a temperature rising rate of 10 ° C./min and continuously measured twice. The glass transition temperature (Tg) was defined as the intersection of two tangents having different thermal expansion coefficients in the second time, and the coefficient of thermal expansion (CTE (α1)) in the region below Tg was evaluated. It can be said that the higher the Tg, the higher the heat resistance.
<Evaluation criteria of glass transition temperature (Tg)>
⊚: Tg is 140 ° C. or higher ○: Tg is 130 ° C. or higher and lower than 140 ° C. <Evaluation criteria for coefficient of thermal expansion (CTE (α1) >>
◯: less than 40 ppm x: 40 ppm or more The evaluation results are shown in Table 2 below.

(8) Pencil hardness measurement According to JIS K 5600, the pencil hardness of the surface of the evaluation substrate on which the thermosetting film was formed, obtained in “(1) Fabrication of L / S (line & space) evaluation substrate” And evaluated. The highest hardness at which the surface of the thermosetting film was not scratched was measured. The criteria for judgment are as follows.
⊚: 6H or more ◯: 4H or more and less than 6H The evaluation results are shown in Table 2 below.

Claims (10)

(A) Liquid epoxy resin,
(B) Liquid flexible epoxy resin,
(C) an inorganic filler,
(D) a curing accelerator,
A solventless curable resin composition containing:   The solventless curable resin composition according to claim 1, wherein the epoxy equivalent of at least one of the (A) liquid epoxy resin and the (B) liquid flexible epoxy resin is 200 g / eq or more.   The liquid flexible epoxy resin (B) is contained in an amount of 3 to 40 mass% with respect to the total amount of the liquid epoxy resin (A) and the liquid flexible epoxy resin (B). The solventless curable resin composition according to item 2.   The solventless curable resin composition according to any one of claims 1 to 3, wherein the liquid flexible epoxy resin (B) is a liquid epoxy-modified polybutadiene resin.   The solventless curable resin composition according to claim 1, further comprising (E) a wetting dispersant.   The wet dispersant (E) is contained in an amount of 0.05 to 3.0% by mass based on the mass of the solventless curable resin composition excluding the inorganic filler (C). Solvent-based curable resin composition.   A cured product obtained by curing the solventless curable resin composition according to any one of claims 1 to 6.   The cured product according to claim 7, which has a sea-island structure in which the liquid flexible epoxy resin (B) is dispersed in a continuous phase composed of the liquid epoxy resin (A).   An electronic component comprising the cured product according to claim 7. An electronic component having a wiring circuit having a circuit thickness of 50 μm or more,
The cured product is filled in the depressions formed between the wiring circuits,
The electronic component according to claim 9, wherein a solder resist layer is provided on a part of the surface of the wiring circuit and the surface of the cured product.