JP2017103329A - Resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin sheet superior in the ability to embed a component while reducing the warp of a substrate.SOLUTION: A resin sheet comprises: a support body; and a curable resin composition layer provided on the support body. The curable resin composition layer includes an inorganic filler. The content of the inorganic filler in the curable resin composition layer is 74 mass% or more. The inorganic filler has an average particle diameter of 1.6 μm or less. Of the inorganic filler, the product of a specific surface area[m/g] and a true density [g/cm] is 6-8. The curable resin composition layer has a minimum melt viscosity of 12000 poise or less.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a resin sheet, a wiring board, and a semiconductor device.

  In recent years, the demand for small high-performance electronic devices such as smartphones and tablet PCs is increasing. Accordingly, there is a demand for further enhancement in function and size of printed wiring boards used in these small electronic devices.

  Components such as a bare chip, a chip capacitor, and a chip inductor are mounted on the printed wiring board. Conventionally, such components have been mounted only on the surface circuit of the printed wiring board, but the amount of mounting is limited, which can meet the recent demand for higher functionality and downsizing of the printed wiring board. Was difficult.

  As a solution to the above problem, there has been proposed a component built-in circuit board that is designed to be miniaturized (thinned) while increasing the mounting amount of the component by incorporating the component in the inner layer circuit board (see, for example, Patent Document 1). ).

Japanese Patent No. 4114629

By the way, in order to make the component embedding property excellent in the recess (cavity) in which the component of the component built-in circuit board is arranged, the content of the inorganic filler in the resin composition used for component embedding with emphasis on the resin flow Although it is conceivable to use a resin having a relatively low molecular weight while suppressing the above, the coefficient of thermal expansion becomes high and the substrate warpage tends to increase. On the other hand, in order to reduce the substrate warpage of the component built-in circuit board, it is conceivable to increase the content of the inorganic filler in the resin composition, but this increases the melt viscosity and reduces the component embedding property in the cavity. There was a problem that it was easy.
Therefore, the problem to be solved by the present invention is to provide a resin sheet that reduces the warpage of the substrate and is excellent in component embedding.

As a result of intensive studies on the above problems, the present inventors have found that the curable resin composition forming the curable resin composition layer has an average particle diameter of 1.6 μm or less and a specific surface area [m ² / g] and the true density [g / cm ³ ] of the composition containing 6 to 8% or more of the inorganic filler, and the minimum melt viscosity of the curable resin composition layer is 12000 poise or less, The present inventors have found that the above problems can be solved and have completed the present invention. The present invention is based on such novel findings.

That is, the present invention includes the following contents.
[1] A resin sheet comprising a support and a curable resin composition layer provided on the support, wherein the curable resin composition layer includes an inorganic filler and includes a curable resin composition layer. The content of the inorganic filler is 74% by mass or more, the average particle size of the inorganic filler is 1.6 μm or less, the specific surface area [m ² / g] and the true density [g / cm] of the inorganic filler. ³ ] The resin sheet whose product is 6-8, and the minimum melt viscosity of a curable resin composition layer is 12000 poise or less.
[2] The resin sheet according to [1], wherein the inorganic filler is silica.
[3] The curable resin composition layer includes (a) an epoxy resin, the epoxy resin includes a liquid epoxy resin, and the content of the liquid epoxy resin in the curable resin composition layer is 1% by mass or more. The resin sheet according to [1] or [2].
[4] (a) an epoxy resin further comprises a solid epoxy resin, solid ratio of epoxy resin mass M _S (M _{S /} M _L relative to the mass M _L of liquid epoxy resin of the curable resin composition layer ) Is 0.6 to 10. The resin sheet according to [3].
[5] The resin sheet according to [3] or [4], wherein (a) the epoxy resin is (a ′) an epoxy resin having an aromatic structure.
[6] The curable resin composition layer is further selected from component (d): a resin having a functional group having a glass transition temperature of 25 ° C. or lower, and a resin having a functional group that is liquid at 25 ° C. The resin sheet according to any one of [3] to [5], which contains at least a seed resin.
[7] The component (d) has at least one functional group selected from a hydroxyl group, an acid anhydride group, a phenolic hydroxyl group, an epoxy group, an isocyanate group, and a urethane group, an alkylene structural unit, and an alkyleneoxy structural unit. , Having at least one structural unit selected from a butadiene structural unit, an isoprene structural unit, an isobutylene structural unit, a chloroprene structural unit, a urethane structural unit, a polycarbonate structural unit, a (meth) acrylate structural unit, and a polysiloxane structural unit [6 ] The resin sheet as described in.
[8] The resin sheet according to any one of [1] to [7], which is for a component built-in circuit board.
[9] A wiring board comprising: an insulating layer obtained by curing the curable resin composition layer of the resin sheet according to any one of [1] to [8]; and a conductor layer.
[10] A semiconductor device comprising the wiring board according to [9].

  ADVANTAGE OF THE INVENTION According to this invention, the curvature of a board | substrate can be reduced and the resin sheet excellent in component embedding property can be provided.

FIG. 1A is a schematic diagram (1) showing a procedure for preparing a circuit board on which a component is temporarily used, which is used in the method for manufacturing a component-embedded circuit board using the resin sheet of the present invention. FIG. 1B is a schematic diagram (2) showing a procedure for preparing a circuit board on which a component is temporarily used, which is used in the method for manufacturing a component-embedded circuit board using the resin sheet of the present invention. FIG. 1C is a schematic diagram (3) showing a procedure for preparing a circuit board on which a component is temporarily attached, which is used in the method for manufacturing a component-embedded circuit board using the resin sheet of the present invention. FIG. 1D is a schematic diagram (4) showing a procedure for preparing a circuit board on which a component is temporarily used, which is used in the method of manufacturing a component-embedded circuit board using the resin sheet of the present invention. FIG. 2 is a schematic view showing one embodiment of the resin sheet of the present invention. FIG. 3A is a schematic diagram (1) for explaining a method for manufacturing a component-embedded circuit board using the resin sheet of the present invention. FIG. 3B is a schematic diagram (2) for explaining the method of manufacturing the component built-in circuit board using the resin sheet of the present invention. FIG. 3C is a schematic diagram (3) for explaining the method of manufacturing the component built-in circuit board using the resin sheet of the present invention. FIG. 3D is a schematic diagram (4) for explaining a method of manufacturing the component built-in circuit board using the resin sheet of the present invention. FIG. 3E is a schematic diagram (5) for explaining the method of manufacturing the component built-in circuit board using the resin sheet of the present invention. FIG. 3F is a schematic diagram (6) for explaining the method of manufacturing the component built-in circuit board using the resin sheet of the present invention. FIG. 3G is a schematic diagram (7) for explaining the method of manufacturing the component built-in circuit board using the resin sheet of the present invention.

  Before describing the resin sheet of the present invention in detail, in the resin sheet of the present invention, a curable resin composition (“" resin composition layer ") used when forming a curable resin composition layer (also referred to as“ resin composition layer ”). The resin composition ”is also described.

<Curable resin composition>
The curable resin composition forming the curable resin composition layer has an average particle size of 1.6 μm or less and a product of specific surface area [m ² / g] and true density [g / cm ³ ] of 6. If it contains the inorganic filler which is -8, it will not specifically limit, The hardened | cured material (insulating layer) should just have sufficient hardness and insulation. As a curable resin composition, the composition containing curable resin and its hardening | curing agent with an inorganic filler is mentioned, for example. As curable resin, the conventionally well-known curable resin used when forming the insulating layer of a printed wiring board can be used, and an epoxy resin is especially preferable. Accordingly, in one embodiment, the curable resin composition includes (a) an epoxy resin, (b) a curing agent, and (c) an inorganic filler. In one preferred embodiment, the curable resin composition comprises (a ′) an epoxy resin having an aromatic structure, (b) a curing agent, (c) an inorganic filler, and (d) a glass transition temperature. A resin having a functional group that is 25 ° C. or lower and one or more resins selected from resins having a functional group that is liquid at 25 ° C. In the present invention, the curable resin composition may further contain additives such as a thermoplastic resin, a curing accelerator, a flame retardant, and rubber particles as necessary.

  Hereinafter, (a) an epoxy resin, (b) a curing agent, (c) an inorganic filler, (d) a resin having a functional group having a glass transition temperature of 25 ° C. or lower, which can be used as a material for the curable resin composition, One or more resins selected from resins having functional groups that are liquid at 25 ° C., and (e) additives will be described.

(A) Epoxy resin Examples of the epoxy resin include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, and other bisphenol type epoxy resins, dicyclopentadiene type epoxy resins, and tris. Phenol type epoxy resin, naphthol novolak type epoxy resin, phenol novolak type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidyl amine type epoxy resin, glycidyl ester type Epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having butadiene structure, alicyclic ring Epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, cyclohexanedimethanol type epoxy resin, naphthylene ether type epoxy resin, trimethylol type epoxy resin, tetraphenylethane type epoxy resin and the like. An epoxy resin may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the epoxy resin include a bisphenol type epoxy resin, a fluorine type epoxy resin (for example, bisphenol AF type epoxy resin), a dicyclopentadiene type epoxy resin, a naphthalene type epoxy resin, a biphenyl type epoxy resin, and a mixture of these epoxy resins. It is preferable to use one or two or more selected epoxy resins.

  In a preferred embodiment, the epoxy resin (a) is preferably an epoxy resin (a ′) having an aromatic structure. The epoxy resin (a ′) having an aromatic structure is not particularly limited as long as it has an aromatic structure. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF Type epoxy resin, bisphenol type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol novolac type epoxy resin, phenol novolac type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol Type epoxy resin, anthracene type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, naphthylene ether type epoxy resin, tetraphenylethane type epoxy resin, etc. That.

  From the viewpoint that the minimum melt viscosity of the curable resin composition layer can be lowered, the epoxy resin preferably contains an epoxy resin that is liquid at room temperature (hereinafter referred to as “liquid epoxy resin”). In this specification, “room temperature” means 25 ° C.

  Moreover, it is preferable that an epoxy resin contains the epoxy resin which has a 2 or more epoxy group in 1 molecule. When the nonvolatile component of the epoxy resin is 100% by mass, at least 50% by mass or more is preferably an epoxy resin having two or more epoxy groups in one molecule. Among them, a liquid epoxy resin having two or more epoxy groups in one molecule and an epoxy resin having three or more epoxy groups in one molecule and solid at room temperature (hereinafter referred to as “solid epoxy resin”). ). A curable resin composition having excellent flexibility can be obtained by using a liquid epoxy resin and a solid epoxy resin in combination as an epoxy resin. Moreover, the breaking strength of the cured product (insulating layer) of the curable resin composition is also improved.

  The liquid epoxy resin (a1) includes bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, phenol novolac type epoxy resin, alicyclic ring having ester skeleton An epoxy resin having a butadiene structure and a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol AF type epoxy resin, and a naphthalene type epoxy resin are more preferable. In particular, the aromatic skeleton-containing epoxy resin is also preferable for reducing the average linear thermal expansion coefficient. Specific examples of the liquid epoxy resin include “HP4032”, “HP4032D”, “HP4032SS” (naphthalene type epoxy resin) manufactured by DIC Corporation, “828US”, “jER828EL” (bisphenol A) manufactured by Mitsubishi Chemical Corporation. Type epoxy resin), “jER807” (bisphenol F type epoxy resin), “jER152” (phenol novolac type epoxy resin), “YL7760” (bisphenol AF type epoxy resin), “ZX1059” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. ( Bisphenol A type epoxy resin and bisphenol F type epoxy resin mixture), “EX-721” (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Corporation, “Celoxide 2021P” (ester structure) manufactured by Daicel Corporation Alicyclic Epoxy with Resin), "PB-3600" (epoxy resin having a butadiene structure) and the like. These may be used alone or in combination of two or more.

  As the solid epoxy resin (a2), naphthalene type tetrafunctional epoxy resin, cresol novolac type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol type epoxy resin, biphenyl type epoxy resin, naphthylene ether type Epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, and tetraphenylethane-type epoxy resins are preferred, and naphthalene-type tetrafunctional epoxy resins, naphthol-type epoxy resins, and biphenyl-type epoxy resins are more preferred. In particular, a polyfunctional epoxy resin is preferable for increasing the number of crosslinking points and reducing the average linear thermal expansion coefficient. Specific examples of the solid epoxy resin include “HP4032H” (naphthalene type epoxy resin), “HP-4700”, “HP-4710” (naphthalene type tetrafunctional epoxy resin), “N-690” manufactured by DIC Corporation. "(Cresol novolac type epoxy resin)", "N-695" (Cresol novolac type epoxy resin), "HP-7200", "HP-7200HH", "HP-7200L", (Dicyclopentadiene type epoxy resin), "EXA7311 ”,“ EXA7311-G3 ”,“ EXA7311-G4 ”,“ EXA7311-G4S ”,“ HP6000 ”(naphthylene ether type epoxy resin),“ EPPN-502H ”(trisphenol type epoxy) manufactured by Nippon Kayaku Co., Ltd. Resin), "NC7000L" (naphthol novolac type epoxy) Fat), “NC3000H”, “NC3000”, “NC3000L”, “NC3100” (biphenyl type epoxy resin), “ESN475V” (naphthol type epoxy resin) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., “ESN485” (naphthol novolak type) Epoxy resin), “YX4000H”, “YL6121” (biphenyl type epoxy resin), “YX4000HK” (bixylenol type epoxy resin), “YX8800” (anthracene type epoxy resin), Osaka Gas Chemical (manufactured by Mitsubishi Chemical Corporation) “PG-100”, “CG-500” manufactured by Mitsubishi Chemical Corporation, “YL7800” (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation, “jER1010” (solid bisphenol A type epoxy manufactured by Mitsubishi Chemical Corporation) Resin), "jER1031S" (tetraphenyl) Tan epoxy resin) and the like.

Epoxy resin, if it contains solid epoxy resin and liquid epoxy resin, the ratio of the mass _{M S} of solid epoxy resin to the weight _{M L} of the liquid epoxy resin _(M S / _{M L)} is 0.6 to 10 The range of is preferable. The M S _/ M _L, With such a range, i) moderate tackiness is brought when used in the form of a resin sheet, ii) sufficient flexibility when used in the form of a resin sheet Is obtained, the handleability is improved, and iii) a cured product (insulating layer) having sufficient breaking strength can be obtained.

The content of the epoxy resin (a) in the curable resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, from the viewpoint of obtaining an insulating layer exhibiting good mechanical strength and insulation reliability. More preferably, it is 5% by mass or more. Although the upper limit of content of an epoxy resin is not specifically limited as long as the effect of this invention is show | played, Preferably it is 40 mass% or less, More preferably, it is 35 mass% or less, More preferably, it is 30 mass% or less.
Therefore, the content of the (a) epoxy resin in the curable resin composition is preferably 0.1 to 50% by mass, more preferably 10 to 45% by mass, and still more preferably 20 to 42% by mass. In the present invention, the content of each component in the curable resin composition is a value when the non-volatile component in the curable resin composition is 100% by mass unless otherwise specified.

  The epoxy equivalent of the epoxy resin is preferably 50 to 5000, more preferably 50 to 3000, still more preferably 80 to 2000, and even more preferably 110 to 1000. By becoming this range, the crosslinked density of hardened | cured material becomes sufficient and it can bring about an insulating layer with small surface roughness. The epoxy equivalent can be measured according to JIS K7236, and is the mass of a resin containing 1 equivalent of an epoxy group.

  The weight average molecular weight of an epoxy resin becomes like this. Preferably it is 100-5000, More preferably, it is 250-3000, More preferably, it is 400-1500. Here, the weight average molecular weight of the epoxy resin is a weight average molecular weight in terms of polystyrene measured by a gel permeation chromatography (GPC) method.

(B) Curing agent The curing agent is not particularly limited as long as it has a function of curing an epoxy resin. For example, a phenolic curing agent, a naphthol curing agent, an active ester curing agent, a benzoxazine curing agent, and a cyanate ester. Examples thereof include a system curing agent and a carbodiimide type curing agent. A hardening | curing agent may be used individually by 1 type, or may use 2 or more types together.

  As the phenol-based curing agent and the naphthol-based curing agent, a phenol-based curing agent having a novolak structure or a naphthol-based curing agent having a novolak structure is preferable from the viewpoint of heat resistance and water resistance. Further, from the viewpoint of adhesion to the conductor layer (circuit wiring), a nitrogen-containing phenol-based curing agent is preferable, and a triazine structure-containing phenol resin and a triazine structure-containing alkyl phenol resin are more preferable. Especially, it is preferable to use a triazine structure containing phenol type hardening | curing agent from a viewpoint which satisfies heat resistance, water resistance, and adhesiveness (peeling strength) with a conductor layer highly.

  Specific examples of the phenol-based curing agent and the naphthol-based curing agent include, for example, “MEH-7700”, “MEH-7810”, “MEH-7785” manufactured by Meiwa Kasei Co., Ltd., and Nippon Kayaku Co., Ltd. “NHN”, “CBN”, “GPH”, “SN170”, “SN180”, “SN190”, “SN475”, “SN485”, “SN495”, “SN375”, “SN395” manufactured by Toto Kasei Co., Ltd. "LA7052", "LA7054", "LA3018", etc. manufactured by DIC Corporation.

  Although there is no restriction | limiting in particular as an active ester type hardening | curing agent, Generally ester groups with high reaction activity, such as phenol ester, thiophenol ester, N-hydroxyamine ester, ester of heterocyclic hydroxy compound, are in 1 molecule. A compound having two or more in the above is preferably used. The active ester curing agent is preferably obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. In particular, from the viewpoint of improving heat resistance, an active ester curing agent obtained from a carboxylic acid compound and a hydroxy compound is preferable, and an active ester curing agent obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferable. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of the phenol compound or naphthol compound include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, phenolphthaline, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m- Cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, Benzenetriol, dicyclopentadienyl diphenol, phenol novolac and the like.

  Specifically, an active ester compound containing a dicyclopentadienyl diphenol structure, an active ester compound containing a naphthalene structure, an active ester compound containing an acetylated product of a phenol novolak, and an active ester compound containing a benzoylated product of a phenol novolak are preferred. Of these, active ester compounds containing a naphthalene structure and active ester compounds containing a dicyclopentadienyl diphenol structure are more preferred.

  Commercially available active ester curing agents include "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T" (DIC Corporation) as active ester compounds containing a dicyclopentadienyl diphenol structure. Manufactured product), "EXB9416-70BK" (manufactured by DIC Corporation) as an active ester compound containing a naphthalene structure, "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester compound containing an acetylated product of phenol novolac, Examples of the active ester compound containing a benzoylated compound include “YLH1026” (manufactured by Mitsubishi Chemical Corporation).

  Specific examples of the benzoxazine-based curing agent include “HFB2006M” manufactured by Showa Polymer Co., Ltd., “Pd” and “Fa” manufactured by Shikoku Kasei Kogyo Co., Ltd.

  Examples of the cyanate ester curing agent include bisphenol A dicyanate, polyphenol cyanate (oligo (3-methylene-1,5-phenylene cyanate)), 4,4′-methylene bis (2,6-dimethylphenyl cyanate), 4, 4'-ethylidenediphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis (4-cyanate) phenylpropane, 1,1-bis (4-cyanatephenylmethane), bis (4-cyanate-3,5- Bifunctional cyanate resins such as dimethylphenyl) methane, 1,3-bis (4-cyanatephenyl-1- (methylethylidene)) benzene, bis (4-cyanatephenyl) thioether, and bis (4-cyanatephenyl) ether; Phenol novolac and Polyfunctional cyanate resin derived from resol novolac, these cyanate resins and partially triazine of prepolymer. Specific examples of the cyanate ester curing agent include “PT30” and “PT60” (both phenol novolak polyfunctional cyanate ester resins) and “BA230” (part or all of bisphenol A dicyanate) manufactured by Lonza Japan Co., Ltd. And the like, and the like, and the like.

  Specific examples of the carbodiimide curing agent include “V-03” and “V-07” manufactured by Nisshinbo Chemical Co., Ltd.

  In the present invention, (b) the curing agent preferably contains at least one selected from a phenolic curing agent, a cyanate ester curing agent and an active ester curing agent, and includes a triazine structure-containing phenolic resin and a triazine structure. More preferably, it contains at least one selected from a containing alkylphenol-based resin, a cyanate ester-based curing agent, and an active ester-based curing agent.

The content of the (b) curing agent in the curable resin composition is not particularly limited. However, from the viewpoint of obtaining an insulating layer having high peel strength and a low dielectric loss tangent, it is preferably 0.1% by mass or more, more preferably 0.8%. 5 mass% or more, More preferably, it is 1 mass% or more. (B) Although the upper limit of content of a hardening | curing agent is not specifically limited as long as the effect of this invention is show | played, Preferably it is 30 mass% or less, More preferably, it is 25 mass% or less, More preferably, it is 20 mass% or less. is there.
Accordingly, the content of the (b) curing agent in the curable resin composition is preferably 0.1 to 30% by mass, more preferably 0.5 to 25% by mass, and still more preferably 1 to 20% by mass.

  The amount ratio of (a) epoxy resin to (b) curing agent is a ratio of [(a) total number of epoxy groups of epoxy resin]: [(b) total number of reactive groups of curing agent], 1: The range of 0.2 to 1: 2 is preferable, 1: 0.3 to 1: 1.5 is more preferable, and 1: 0.4 to 1: 1 is more preferable. Here, the reactive group of the curing agent is an active hydroxyl group, an active ester group or the like, and varies depending on the type of the curing agent. Moreover, the total number of epoxy groups of the epoxy resin is a value obtained by dividing the solid content mass of each epoxy resin by the epoxy equivalent for the epoxy resin, and the total number of reactive groups of the curing agent is each curing The value obtained by dividing the solid content mass of the agent by the reactive group equivalent is the sum of all the curing agents. The heat resistance of the hardened | cured material (insulating layer) of a curable resin composition improves more by making the quantity ratio of an epoxy resin and a hardening | curing agent into such a range.

(C) Inorganic filler The inorganic filler has an average particle size of 1.6 μm or less and a product of specific surface area [m ² / g] and true density [g / cm ³ ] (specific surface area × true density). ) Is 6-8, specifically, silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, Hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate , Bismuth titanate, titanium oxide, zirconium oxide, barium titanate, tita Barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and phosphoric acid zirconium tungstate, and the like. Of these, silica is particularly preferred. Moreover, spherical silica is preferable as the silica. An inorganic filler may be used individually by 1 type, and may be used in combination of 2 or more type. Examples of commercially available silica used as an inorganic filler include “Admafine” manufactured by Admatechs Co., Ltd., “SFP Series” manufactured by Denki Kagaku Kogyo Co., Ltd., and “SP (H) Series manufactured by Nippon Steel & Sumikin Materials Co., Ltd. ”,“ Sciqas Series ”manufactured by Sakai Chemical Industry Co., Ltd.,“ Sea Hoster Series ”manufactured by Nippon Shokubai Co., Ltd., and other commercial products of alumina include“ AZ, AX ”manufactured by Nippon Steel & Sumikin Materials Co., Ltd. Series "etc. are mentioned.

  In the present invention, the average particle size of the inorganic filler is 1.6 μm or less. The average particle size of the inorganic filler is preferably 1.5 μm or less, and more preferably 1.4 μm or less. On the other hand, when forming a resin varnish using a curable resin composition, a viewpoint of obtaining a resin varnish having an appropriate viscosity and good handleability, and a viewpoint of preventing an increase in melt viscosity of the curable resin composition layer From the above, the average particle size of the inorganic filler is preferably 0.5 μm or more, more preferably 0.6 μm or more, and further preferably 0.7 μm or more.

  The average particle diameter of the inorganic filler can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, the particle size distribution of the inorganic filler can be prepared on a volume basis by a laser diffraction / scattering particle size distribution measuring apparatus, and the median diameter can be measured as the average particle diameter. As the measurement sample, an inorganic filler dispersed in water by ultrasonic waves can be preferably used. As the laser diffraction particle size distribution measuring apparatus, “SALD-2200” manufactured by Shimadzu Corporation can be used.

  The specific surface area of the inorganic filler can be measured by the BET method. For the measurement of the specific surface area, a BET fully automatic specific surface area measuring device (Macsorb HM-1210 manufactured by Mountec Co., Ltd.) or the like can be used. The true density of the inorganic filler can be measured by using a micro-ultra pycnometer (MUTY-21T manufactured by Cantachrome Instruments Japan (same)).

According to the present invention, when the product of the specific surface area [m ² / g] and the true density [g / cm ³ ] of the inorganic filler is 6 or more, the flow of the curable resin composition into the cavity is excellent. If the product is 8 or less, the average linear thermal expansion coefficient can be lowered. The lower limit of the product of the specific surface area and the true density of the inorganic filler is preferably 6.1 or more, and more preferably 6.3 or more. The product of the specific surface area and the true density of the inorganic filler is preferably 7.7 or less, and more preferably 7.5 or less.

  Inorganic fillers are aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, organosilazane compounds, titanate coupling agents from the viewpoint of improving moisture resistance and dispersibility. It is preferable that it is processed with 1 or more types of surface treating agents. Examples of commercially available surface treatment agents include “KBM403” (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., and “KBM803” (3-mercaptopropyltrimethoxy manufactured by Shin-Etsu Chemical Co., Ltd.). Silane), Shin-Etsu Chemical "KBE903" (3-aminopropyltriethoxysilane), Shin-Etsu Chemical "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical "SZ-31" (hexamethyldisilazane) manufactured by KK, "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-4803" manufactured by Shin-Etsu Chemical Co., Ltd. (long-chain epoxy type) Silane coupling agent).

The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of the inorganic filler. Carbon content per unit surface area of the inorganic filler, from the viewpoint of improving dispersibility of the inorganic filler is preferably 0.02 mg / ^{m 2} or more, 0.1 mg / ^{m 2} or more preferably, 0.2 mg / ^{m 2} The above is more preferable. On the other hand, 1 mg / m ² or less is preferable, 0.8 mg / m ² or less is more preferable, and 0.5 mg / m ² or less is more preferable from the viewpoint of preventing an increase in the melt viscosity of the resin varnish or the sheet form. preferable.

  The amount of carbon per unit surface area of the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (for example, methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler surface-treated with the surface treatment agent and ultrasonically cleaned at 25 ° C. for 5 minutes. After removing the supernatant and drying the solid, the carbon amount per unit surface area of the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, “EMIA-320V” manufactured by Horiba, Ltd. can be used.

  The content of the inorganic filler (c) in the curable resin composition is 74% by mass or more, preferably 76% by mass or more, and more preferably 78% by mass or more. (C) The upper limit of the content of the inorganic filler is preferably 90% by mass or less, more preferably 85% by mass or less, from the viewpoint of obtaining an insulating layer on which fine wiring can be formed.

(D) One or more resins selected from a resin having a functional group having a glass transition temperature of 25 ° C. or lower and a resin having a functional group that is liquid at 25 ° C. (component (d)).
In a preferred embodiment, the curable resin composition contains the component (d) together with the epoxy resin (a ′) (component (a ′)) having an aromatic structure. By containing a flexible resin such as component (d), the elastic modulus and thermal expansion coefficient of the cured product (insulating layer) of the curable resin composition layer are reduced, and the resin sheet of the present invention is used. Generation | occurrence | production of the curvature of the obtained wiring board can be suppressed.

  The glass transition temperature of the resin having a functional group having a glass transition temperature (Tg) of component (d) of 25 ° C. or lower is preferably 20 ° C. or lower, more preferably 15 ° C. or lower. Although the minimum of the glass transition temperature of (d) component is not specifically limited, Usually, it can be set as -15 degreeC or more.

  If a resin having a functional group that is liquid at 25 ° C. is liquid at 25 ° C., the Tg of the resin is naturally considered to be 25 ° C. or lower.

  The functional group possessed by component (d) preferably has a functional group capable of reacting with component (a) or (a ′). In a preferred embodiment, the functional group (d) has at least one functional group selected from the group consisting of a hydroxyl group, an acid anhydride group, a phenolic hydroxyl group, an epoxy group, an isocyanate group, and a urethane group. It is. Among these, as the functional group, a hydroxyl group, an acid anhydride group, an epoxy group, and a phenolic hydroxyl group are preferable, and a hydroxyl group, an acid anhydride group, and an epoxy group are more preferable. However, when an epoxy group is included as a functional group, the component (d) does not have an aromatic structure.

  The component (d) is an alkylene structural unit having 2 to 15 carbon atoms (preferably 3 to 10 carbon atoms, more preferably 5 to 6 carbon atoms) from the viewpoint of obtaining a curable resin composition layer having a low elastic modulus. ), An alkyleneoxy structural unit having 2 to 15 carbon atoms (preferably 3 to 10 carbon atoms, more preferably 5 to 6 carbon atoms), a butadiene structural unit, an isoprene structural unit, an isobutylene structural unit, a chloroprene structural unit, It is preferable to have one or more structural units selected from a urethane structural unit, a polycarbonate structural unit, a (meth) acrylate structural unit, and a polysiloxane structural unit. From a butadiene structural unit, a urethane structural unit, and a (meth) acrylate structural unit More preferably, it has one or more selected structural units. “(Meth) acrylate” refers to methacrylate and acrylate.

  A preferred embodiment of the component (d) is a functional group-containing saturated and / or unsaturated butadiene resin that is liquid at 25 ° C. Examples of the functional group-containing saturated and / or unsaturated butadiene resins that are liquid at 25 ° C. include acid anhydride group-containing saturated and / or butadiene resins that are liquid at 25 ° C., and phenolic hydroxyl group-containing saturated and / or butadiene that are liquid at 25 ° C. Group consisting of resin, epoxy group-containing saturated and / or butadiene resin that is liquid at 25 ° C., isocyanate group-containing saturated and / or butadiene resin that is liquid at 25 ° C., and urethane group-containing saturated and / or butadiene resin that is liquid at 25 ° C. One or more resins selected from are preferred. Here, the “saturated and / or unsaturated butadiene resin” means a resin containing a saturated butadiene skeleton and / or an unsaturated butadiene skeleton, and in these resins, the saturated butadiene skeleton and / or the unsaturated butadiene skeleton is a main chain. Or may be contained in the side chain.

  The number average molecular weight (Mn) of the functional group-containing saturated and / or unsaturated butadiene resin which is liquid at 25 ° C. is preferably 500 to 50,000, more preferably 1000 to 10,000. Here, the number average molecular weight (Mn) of the resin is a number average molecular weight in terms of polystyrene measured using GPC (gel permeation chromatography).

  The functional group equivalent of the liquid functional group-containing saturated and / or unsaturated butadiene resin at 25 ° C. is preferably 100 to 10,000, more preferably 200 to 5,000. In addition, functional group equivalent is the mass of resin containing 1 equivalent of functional groups. For example, the epoxy equivalent of the resin can be measured according to JIS K7236.

  The epoxy group-containing saturated and / or unsaturated butadiene resin that is liquid at 25 ° C. is preferably a liquid saturated and / or butadiene skeleton-containing epoxy resin that is liquid at 25 ° C., and a polybutadiene skeleton-containing epoxy resin that is liquid at 25 ° C. A liquid hydrogenated polybutadiene skeleton-containing epoxy resin is more preferable, and a polybutadiene skeleton-containing epoxy resin that is liquid at 25 ° C. and a hydrogenated polybutadiene skeleton-containing epoxy resin that is liquid at 25 ° C. are more preferable. Here, the “hydrogenated polybutadiene skeleton-containing epoxy resin” refers to an epoxy resin in which at least a part of the polybutadiene skeleton is hydrogenated, and is not necessarily an epoxy resin in which the polybutadiene skeleton is completely hydrogenated. Specific examples of the polybutadiene skeleton-containing resin that is liquid at 25 ° C. and the hydrogenated polybutadiene skeleton-containing resin that is liquid at 25 ° C. include “PB3600” and “PB4700” (polybutadiene skeleton epoxy resin) manufactured by Daicel Corporation, Nagase ChemteX Corporation. "FCA-061L" (hydrogenated polybutadiene skeleton epoxy resin) manufactured by Co., Ltd. and the like can be mentioned.

  The acid anhydride group-containing saturated and / or unsaturated butadiene resin that is liquid at 25 ° C. is preferably a saturated and / or unsaturated butadiene skeleton-containing acid anhydride resin that is liquid at 25 ° C. The phenolic hydroxyl group-containing saturated and / or unsaturated butadiene resin that is liquid at 25 ° C. is preferably a saturated and / or unsaturated butadiene skeleton-containing phenol resin that is liquid at 25 ° C. The isocyanate group-containing saturated and / or unsaturated butadiene resin that is liquid at 25 ° C. is preferably a saturated and / or unsaturated butadiene skeleton-containing isocyanate resin that is liquid at 25 ° C. As the urethane group-containing saturated and / or unsaturated butadiene resin that is liquid at 25 ° C., a saturated and / or unsaturated butadiene skeleton-containing urethane resin that is liquid at 25 ° C. is preferable.

  Another preferred embodiment of the component (d) is a functional group-containing acrylic resin having a Tg of 25 ° C. or lower. The functional group-containing acrylic resin having a Tg of 25 ° C. or lower includes an acid anhydride group-containing acrylic resin having a Tg of 25 ° C. or lower, a phenolic hydroxyl group-containing acrylic resin having a Tg of 25 ° C. or lower, and an isocyanate group containing Tg of 25 ° C. One or more resins selected from the group consisting of an acrylic resin, a urethane group-containing acrylic resin having a Tg of 25 ° C. or lower, and an epoxy group-containing acrylic resin having a Tg of 25 ° C. or lower are preferred.

  The number average molecular weight (Mn) of the functional group-containing acrylic resin having a Tg of 25 ° C. or lower is preferably 10,000 to 1,000,000, more preferably 30,000 to 900,000. Here, the number average molecular weight (Mn) of the resin is a number average molecular weight in terms of polystyrene measured using GPC (gel permeation chromatography).

  The functional group equivalent of the functional group-containing acrylic resin having a Tg of 25 ° C. or lower is preferably 1000 to 50000, more preferably 2500 to 30000.

  The epoxy group-containing acrylic resin having a Tg of 25 ° C. or lower is preferably an epoxy group-containing acrylic ester copolymer resin having a Tg of 25 ° C. or lower. Specific examples thereof include “SG-” manufactured by Nagase ChemteX Corporation. 80H "(epoxy group-containing acrylate copolymer resin (number average molecular weight Mn: 350,000 g / mol, epoxy value 0.07 eq / kg, Tg11 ° C))," SG-P3 "(manufactured by Nagase ChemteX Corporation) ( Epoxy group-containing acrylic ester copolymer resin (number average molecular weight Mn: 850000 g / mol, epoxy value 0.21 eq / kg, Tg 12 ° C.)).

  The acid anhydride group-containing acrylic resin having a Tg of 25 ° C. or lower is preferably an acid anhydride group-containing acrylic ester copolymer resin having a Tg of 25 ° C. or lower.

  As the phenolic hydroxyl group-containing acrylic resin having a Tg of 25 ° C. or lower, a phenolic hydroxyl group-containing acrylic ester copolymer resin having a Tg of 25 ° C. or lower is preferable. Specific examples thereof include “manufactured by Nagase ChemteX Corporation” SG-790 "(epoxy group-containing acrylic ester copolymer resin (number average molecular weight Mn: 500,000 g / mol, hydroxyl value 40 mg KOH / kg, Tg-32 ° C)).

  Moreover, one suitable embodiment of (d) component is a polyimide resin which has a butadiene structural unit, a urethane structural unit, and an imide structural unit in a molecule | numerator, and it is preferable that this polyimide resin has a phenol structure at a molecule terminal. .

  The number average molecular weight (Mn) of the polyimide resin is preferably 1000 to 100,000, more preferably 10,000 to 15000. Here, the number average molecular weight (Mn) of the resin is a number average molecular weight in terms of polystyrene measured using GPC (gel permeation chromatography).

  The acid value of the polyimide resin is preferably 1 KOH / g to 30 KOH / g, more preferably 10 KOH / g to 20 KOH / g.

  The content of the butadiene structure in the polyimide resin is preferably 60% by mass to 95% by mass, and more preferably 75% by mass to 85% by mass.

  Details of the polyimide resin can be referred to the description of International Publication No. 2008/153208, the contents of which are incorporated herein.

  From the viewpoint of improving the breaking strength, the component (d) preferably has high compatibility with components other than the component (d). That is, the component (d) is preferably dispersed in the curable resin composition layer.

  Although content of (d) component in curable resin composition is not specifically limited, Preferably it is 14 mass% or less, More preferably, it is 13 mass% or less, More preferably, it is 12 mass% or less. Further, the lower limit is preferably 2% by mass or more, more preferably 3% by mass or more, and further preferably 4% by mass or more.

  The curable resin composition may contain additives (e) such as a thermoplastic resin, a curing accelerator, a flame retardant, and rubber particles in addition to the above (a), (b), (c), and (d). Good.

(E) Additive-Thermoplastic resin-
Examples of the thermoplastic resin include phenoxy resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyimide resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polycarbonate resin, and polyether. Examples thereof include thermoplastic resins such as ether ketone resins and polyester resins, and among these, phenoxy resins are preferred. A thermoplastic resin may be used individually by 1 type, or may be used in combination of 2 or more type.

  The polystyrene equivalent weight average molecular weight of the thermoplastic resin is preferably in the range of 5,000 to 100,000, more preferably in the range of 10,000 to 60,000, and still more preferably in the range of 20,000 to 60,000. The weight average molecular weight in terms of polystyrene of the thermoplastic resin is measured by a gel permeation chromatography (GPC) method. Specifically, the polystyrene-reduced weight average molecular weight of the thermoplastic resin is LC-9A / RID-6A manufactured by Shimadzu Corporation as a measuring device, and Shodex K-800P / K- manufactured by Showa Denko KK as a column. 804L / K-804L can be calculated using a standard polystyrene calibration curve by measuring the column temperature at 40 ° C. using chloroform or the like as a mobile phase.

  Examples of the phenoxy resin include bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenolacetophenone skeleton, novolac skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene Examples thereof include phenoxy resins having a skeleton and one or more skeletons selected from the group consisting of a trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. A phenoxy resin may be used individually by 1 type, and may be used in combination of 2 or more type. Specific examples of the phenoxy resin include “1256” and “4250” (both bisphenol A skeleton-containing phenoxy resin), “YX8100” (bisphenol S skeleton-containing phenoxy resin), and “YX6954” (manufactured by Mitsubishi Chemical Corporation). In addition, “FX280” and “FX293” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., “YL6954BH30”, “YX7553”, “YL7769BH30” manufactured by Mitsubishi Chemical Corporation, “YL6794”, “YL7213”, “YL7290”, “YL7482” and the like.

  Examples of the polyvinyl acetal resin include a polyvinyl formal resin and a polyvinyl butyral resin, and a polyvinyl butyral resin is preferable. Specific examples of the polyvinyl acetal resin include, for example, “Electrical butyral 4000-2”, “Electrical butyral 5000-A”, “Electrical butyral 6000-C” and “Electrical butyral 6000-EP” manufactured by Denki Kagaku Kogyo Co., Ltd. Sekisui Chemical Co., Ltd.'s S-REC BH series, BX series, KS series, BL series, BM series and the like.

  Specific examples of the polyimide resin include “Rika Coat SN20” and “Rika Coat PN20” manufactured by Shin Nippon Rika Co., Ltd. Specific examples of the polyimide resin include linear polyimide obtained by reacting a bifunctional hydroxyl group-terminated polybutadiene, a diisocyanate compound and a tetrabasic acid anhydride (polyimide described in JP-A-2006-37083), a polysiloxane skeleton. Examples thereof include modified polyimides such as containing polyimide (polyimides described in JP-A Nos. 2002-12667 and 2000-319386).

  Specific examples of the polyamide-imide resin include “Bilomax HR11NN” and “Bilomax HR16NN” manufactured by Toyobo Co., Ltd. Specific examples of the polyamideimide resin also include modified polyamideimides such as “KS9100” and “KS9300” (polysiloxane skeleton-containing polyamideimide) manufactured by Hitachi Chemical Co., Ltd.

  Specific examples of the polyethersulfone resin include “PES5003P” manufactured by Sumitomo Chemical Co., Ltd.

  Specific examples of the polysulfone resin include polysulfone “P1700” and “P3500” manufactured by Solvay Advanced Polymers Co., Ltd.

  Among these, phenoxy resin and polyvinyl acetal resin are preferable as the thermoplastic resin from the viewpoint of obtaining an insulating layer having a lower surface roughness and superior adhesion to the conductor layer in combination with other components. Therefore, in one suitable embodiment, a thermoplastic resin component contains 1 or more types selected from the group which consists of a phenoxy resin and a polyvinyl acetal resin.

  The content of the thermoplastic resin in the curable resin composition is preferably 0% by mass to 20% by mass, more preferably 0.5% by mass from the viewpoint of appropriately adjusting the melt viscosity of the curable resin composition layer. It is 10 mass%, More preferably, it is 0.6 mass%-8 mass%.

-Curing accelerator-
Examples of the curing accelerator include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, phosphorus-based curing accelerators, amine-based curing accelerators, and imidazole-based accelerators. A curing accelerator is preferable, and an amine-based curing accelerator and an imidazole-based curing accelerator are more preferable. A hardening accelerator may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of phosphorus curing accelerators include triphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl) triphenylphosphonium thiocyanate. , Tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate and the like, and triphenylphosphine and tetrabutylphosphonium decanoate are preferable.

  Examples of amine curing accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6, -tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo. (5,4,0) -undecene and the like are mentioned, and 4-dimethylaminopyridine and 1,8-diazabicyclo (5,4,0) -undecene are preferable.

  Examples of the imidazole curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl- 2 Phenylimidazolium trimellitate, 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine, 2,4-diamino-6- [2'-undecylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino- 6- [2′-Methylimidazolyl- (1 ′)]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl- 4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo [1,2-a] benzimidazole, 1-dodecyl-2-methyl Examples include imidazole compounds such as 3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, and adducts of imidazole compounds and epoxy resins, such as 2-ethyl-4-methylimidazole and 1-benzyl-2-phenyl. Imidazole is preferred.

  Commercially available products may be used as the imidazole curing accelerator, and examples thereof include “P200-H50” manufactured by Mitsubishi Chemical Corporation.

  Examples of the guanidine curing accelerator include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1- (o-tolyl) guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, Tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo [4.4.0] dec-5-ene, 7-methyl-1,5,7-triazabicyclo [4.4.0] Deca-5-ene, 1-methyl biguanide, 1-ethyl biguanide, 1-n-butyl biguanide, 1-n-octadecyl biguanide, 1,1-dimethyl biguanide, 1,1-diethyl biguanide, 1-cyclohexyl biguanide, 1 -Allyl biguanide, 1-phenyl biguanide, 1- ( - tolyl) biguanide, and the like, dicyandiamide, 1,5,7-triazabicyclo [4.4.0] dec-5-ene are preferred.

  Although content of the hardening accelerator in curable resin composition is not specifically limited, It is preferable to use in 0.05 mass%-3 mass%.

-Flame retardant-
The curable resin composition may contain a flame retardant. Examples of the flame retardant include an organic phosphorus flame retardant, an organic nitrogen-containing phosphorus compound, a nitrogen compound, a silicone flame retardant, and a metal hydroxide. A flame retardant may be used individually by 1 type, or may use 2 or more types together.

  Commercially available products may be used as the flame retardant, and examples thereof include “HCA-HQ” manufactured by Sanko Co., Ltd., “PX-200” manufactured by Eighth Chemical Industry Co., Ltd., and the like.

  The content of the flame retardant in the curable resin composition is not particularly limited, but is preferably 0.5% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and even more preferably 1.5% by mass to 10 mass% is more preferable.

-Organic filler-
The curable resin composition may further contain an organic filler. As the organic filler, any organic filler that can be used for forming an insulating layer of a printed wiring board may be used. Examples thereof include rubber particles, polyamide fine particles, and silicone particles, and rubber particles are preferable.

  As the rubber particles, commercially available products may be used, and examples thereof include “EXL2655” manufactured by Dow Chemical Japan Co., Ltd., “AC3816N” manufactured by Aika Industry Co., Ltd., and the like.

  The content of the organic filler in the curable resin composition is preferably 0.5 mass% to 20 mass%, more preferably 0.7 mass% to 10 mass%.

  The curable resin composition may further contain other additives other than the flame retardant and the organic filler as necessary. Examples of such other additives include organic copper compounds and organic zinc. Examples thereof include organometallic compounds such as compounds and organic cobalt compounds, and resin additives such as organic fillers, thickeners, antifoaming agents, leveling agents, adhesion imparting agents, and coloring agents.

-Liquid amino resin-
From the viewpoint of setting the minimum melt viscosity of the curable resin composition layer to 12000 poise or less, the curable resin composition may further contain an amino resin that is liquid at room temperature (liquid amino resin). The liquid amino resin can be used in place of the liquid epoxy resin or together with the liquid epoxy resin. Examples of the liquid amino resin include alkylated melamine resins such as methyl melamine. An alkylated melamine resin is prepared by, for example, reacting melamine with formaldehyde to replace some or all of the hydrogen atoms of the amino group with methylol groups, and further reacting with an alcohol compound to convert some or all of the methylol groups to alkoxymethyl. Obtained by conversion to a group.

[Resin sheet]
Hereinafter, the resin sheet of the present invention will be described.

  The resin sheet of the present invention comprises a support and a curable resin composition layer formed of a curable resin composition, and the minimum melt viscosity of the curable resin composition layer is 12000 poise or less. To do. Furthermore, it is preferable that the average linear thermal expansion coefficient between 25 degreeC and 150 degreeC of the insulating layer (hardened | cured material) formed by hardening | curing the said curable resin composition layer is 17 ppm / degrees C or less.

  An example of the resin sheet of the present invention is shown in FIG. In FIG. 2, the resin sheet 10 includes a support 11 and a curable resin composition layer 12 provided on the support 11.

<Support>
Examples of the support include a film made of a plastic material, a metal foil, and a release paper, and a film made of a plastic material and a metal foil are preferable.

  When a film made of a plastic material is used as the support, examples of the plastic material include polyethylene terephthalate (hereinafter sometimes abbreviated as “PET”) and polyethylene naphthalate (hereinafter abbreviated as “PEN”). .) Polyester, polycarbonate (hereinafter sometimes abbreviated as “PC”), polymethyl methacrylate (PMMA) and other acrylics, cyclic polyolefin, triacetyl cellulose (TAC), polyether sulfide (PES), polyether Examples include ketones and polyimides. Among these, polyethylene terephthalate and polyethylene naphthalate are preferable, and inexpensive polyethylene terephthalate is particularly preferable.

  When using metal foil as a support body, as metal foil, copper foil, aluminum foil, etc. are mentioned, for example, Copper foil is preferable. As the copper foil, a foil made of a single metal of copper may be used, and a foil made of an alloy of copper and another metal (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.). It may be used.

  The support may be subjected to mat treatment or corona treatment on the surface to be bonded to the curable resin composition layer.

  Moreover, as a support body, you may use the support body with a release layer which has a release layer in the surface joined to a curable resin composition layer. Examples of the release agent used for the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. . As the support with a release layer, a commercially available product may be used, for example, “Lumirror T6AM” manufactured by Toray Industries, Inc., which is a PET film having a release layer mainly composed of an alkyd resin release agent. “SK-1”, “AL-5”, “AL-7”, etc., manufactured by Lintec Corporation are included.

  Although the thickness of a support body is not specifically limited, The range of 5 micrometers-75 micrometers is preferable, and the range of 10 micrometers-60 micrometers is more preferable. In addition, when using a support body with a release layer, it is preferable that the thickness of the whole support body with a release layer is the said range.

<Curable resin composition layer>
In the present invention, the minimum melt viscosity of the curable resin composition layer is 12000 poise or less, preferably 10,000 poise or less, from the viewpoint of realizing good embedding of components inside the cavity when manufacturing a circuit board with built-in components. Preferably it is 8000 poise or less. The minimum of the minimum melt viscosity of a curable resin composition layer is not specifically limited, Usually, 500 poise or more, 1000 poise or more etc. can be used.

  Here, the “minimum melt viscosity” of the curable resin composition layer refers to the lowest viscosity exhibited by the curable resin composition layer when the resin of the curable resin composition layer is melted. Specifically, when the resin is melted by heating the curable resin composition layer at a constant rate of temperature rise, the melt viscosity decreases in the initial stage as the temperature rises, and then melts as the temperature rises above a certain temperature. Viscosity increases. “Minimum melt viscosity” refers to the melt viscosity at such a minimum point. The minimum melt viscosity of the curable resin composition layer can be measured by a dynamic viscoelastic method. Specifically, the minimum melt viscosity of the curable resin composition layer is obtained by performing dynamic viscoelasticity measurement under the conditions of a measurement start temperature of 60 ° C., a temperature increase rate of 5 ° C./min, a frequency of 1 Hz, and a strain of 1 deg. be able to. Examples of the dynamic viscoelasticity measuring apparatus include “Rheosol-G3000” manufactured by UBM Co., Ltd.

  In the present invention, the average linear thermal expansion coefficient between 25 ° C. and 150 ° C. of the insulating layer obtained by curing the curable resin composition layer is from the viewpoint of realizing a component built-in circuit board in which the problem of warpage is suppressed. 17 ppm / ° C. or less, preferably 16 ppm / ° C. or less, more preferably 15 ppm / ° C. or less. The lower limit of the average linear thermal expansion coefficient is not particularly limited, but can usually be 1 ppm / ° C. or higher, 2 ppm / ° C. or higher, 3 ppm / ° C. or higher, and the like. The average linear thermal expansion coefficient can be measured, for example, by a known method such as thermomechanical analysis. Examples of the thermomechanical analyzer include “Thermo Plus TMA8310” manufactured by Rigaku Corporation. In this invention, the average linear thermal expansion coefficient of an insulating layer is an average linear thermal expansion coefficient of 25-150 degreeC of a planar direction at the time of performing a thermomechanical analysis by the tension load method.

  In the present invention, the thickness of the curable resin composition layer comprising the curable resin composition is preferably 300 μm or less, and more preferably 200 μm or less. The lower limit of the thickness of the curable resin composition layer is not particularly limited, but is usually 10 μm from the viewpoint of obtaining an insulating layer exhibiting excellent peel strength with respect to the conductor layer after the roughening treatment and from the viewpoint of ease of production of the resin sheet. As described above, it may be 20 μm or more.

  The resin sheet 10 of the present invention may further include a protective film on the surface of the curable resin composition layer 12 that is not joined to the support 11 (that is, the surface opposite to the support). The protective film contributes to the adhesion of dust and the like to the surface of the curable resin composition layer 12 and the prevention of scratches. As the material for the protective film, the same material as described for the support 11 may be used. Although the thickness of a protective film is not specifically limited, For example, they are 1 micrometer-40 micrometers. The resin sheet 10 can be used by peeling off the protective film when manufacturing a printed wiring board.

  The resin sheet of the present invention can realize a good embedding property of the components inside the cavity when manufacturing the component-embedded circuit board, and can realize a component-embedded circuit board in which the problem of warpage is suppressed. Therefore, the resin sheet of the present invention can be particularly suitably used for embedding the components inside the cavity (for cavity embedding) in the production of the component built-in circuit board, and is also suitable for mold underfill (sealing) applications. Can be used for The resin sheet of the present invention can also be used for forming an insulating layer of a printed wiring board (for an insulating layer of a printed wiring board). Since the resin sheet of the present invention can provide an insulating layer on which fine wiring can be formed, in order to form an insulating layer in the production of a printed wiring board by a build-up method (build-up of a printed wiring board) It can be suitably used for an insulating layer), and can be more suitably used for forming a conductor layer by plating (for a build-up insulating layer of a printed wiring board on which a conductor layer is formed by plating).

<Method for producing resin sheet>
Hereinafter, an example of the manufacturing method of the resin sheet of this invention is demonstrated. A curable resin composition layer made of a curable resin composition is formed on the support.

  Examples of the method for forming the curable resin composition layer include a method in which the curable resin composition is applied to a support and the coating film is dried to provide the curable resin composition layer.

  In this method, the curable resin composition layer is prepared by preparing a resin varnish having a curable resin composition dissolved in an organic solvent, and applying the resin varnish on a support using a die coater or the like. It can be produced by drying.

  Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone and cyclohexanone, acetates such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate and carbitol acetate, and carbitols such as cellosolve and butyl carbitol. And aromatic hydrocarbons such as toluene and xylene, amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone. An organic solvent may be used individually by 1 type, or may use 2 or more types together.

  The resin varnish may be dried by a known drying method such as heating or hot air blowing. Depending on the boiling point of the organic solvent in the resin varnish, for example, when a resin varnish containing 30% by mass to 60% by mass of the organic solvent is used, the support is obtained by drying at 50 ° C. to 150 ° C. for 3 minutes to 10 minutes. A curable resin composition layer can be formed thereon.

  Moreover, in this invention, after forming a curable resin composition layer on a protective film, a support body may be laminated | stacked on a curable resin composition layer, and a resin sheet may be produced, for example.

<Wiring board>
The wiring board of this invention is equipped with the insulating layer formed by hardening | curing the curable resin composition layer of the resin sheet of this invention, and a conductor layer. Hereinafter, a component built-in circuit board which is an embodiment of the wiring board of the present invention will be described.

  The component built-in circuit board includes (A) a circuit board having first and second main surfaces, and a cavity formed between the first and second main surfaces, and a second of the circuit board. The resin sheet of the present invention is attached to a circuit board on which a component is temporarily attached, including a temporary attachment material bonded to the main surface and a part temporarily attached by the temporary attachment material inside the cavity of the circuit board. A first laminating step for vacuum lamination so that the curable resin composition layer is bonded to the first main surface of the circuit board; and (B) a heat treatment step for heat-treating the circuit board on which the resin sheet is laminated. And (C) after peeling the temporary attachment material from the second main surface of the circuit board, the second resin sheet is bonded to the second main surface of the circuit board so that the curable resin composition layer is bonded to the second main surface. A second lamination step of vacuum lamination, and (D) a curable resin composition layer of the resin sheet, and A step of thermally curing the curable resin composition layer of the second resin sheet, a can be prepared by a production method comprising in this order. Prior to the description of each step, a “circuit board on which components are temporarily attached” using the resin sheet 10 of the present invention will be described.

(Circuit board with parts temporarily attached)
A circuit board on which components are temporarily attached (hereinafter also referred to as “component temporary attachment circuit board” or “cavity board”) has first and second main surfaces, and the first and second main surfaces. A circuit board in which a cavity penetrating the circuit board is formed; a tacking material joined to the second main surface of the circuit board; and a component tacked by the tacking material inside the cavity of the circuit board Including.

  The component tack circuit board can be prepared according to any conventionally known procedure when the component built-in circuit board is manufactured. Hereinafter, an example of a procedure for preparing the component tack circuit board will be described with reference to FIGS. 1A to 1D, but is not limited to the following procedure.

  First, a circuit board is prepared (FIG. 1A). “Circuit substrate” refers to a plate-like substrate having first and second main surfaces facing each other and having circuit wiring patterned on one or both of the first and second main surfaces. In FIG. 1A, the end surface of the circuit board 1 is typically shown, and the circuit board 1 includes a substrate 2 and circuit wirings 3 such as via wirings and surface wirings. In the following description, for convenience, the first main surface of the circuit board represents the upper main surface of the illustrated circuit board, and the second main surface of the circuit board represents the lower side of the illustrated circuit board. It represents the main surface.

  Examples of the substrate 2 used for the circuit board 1 include a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, a thermosetting polyphenylene ether substrate, and the like, and a glass epoxy substrate is preferable. In addition, when the printed wiring board is manufactured, an inner layer circuit board of an intermediate product on which an insulating layer and / or a conductor layer is to be formed is also included in the “circuit board”.

  The thickness of the substrate 2 of the circuit board 1 is preferably thinner from the viewpoint of reducing the thickness of the component-embedded circuit board, preferably less than 400 μm, more preferably 350 μm or less, still more preferably 300 μm or less, and even more preferably 250 μm. Hereinafter, it is particularly preferably 200 μm or less, 180 μm or less, 170 μm or less, 160 μm or less, or 150 μm or less. Although the minimum of the thickness of the board | substrate 2 is not restrict | limited in particular, From a viewpoint of the handleability improvement at the time of conveyance, Preferably it is 50 micrometers or more, More preferably, it is 80 micrometers or more, More preferably, it is 100 micrometers or more.

  The dimensions of the circuit wiring 3 provided on the circuit board 1 may be determined according to desired characteristics. For example, the thickness of the surface wiring is preferably 40 μm or less, more preferably 35 μm or less, even more preferably 30 μm or less, even more preferably 25 μm or less, particularly preferably 20 μm or less, particularly 19 μm, from the viewpoint of reducing the thickness of the component built-in circuit board. Or 18 μm or less. The lower limit of the thickness of the surface wiring is not particularly limited, but is usually 1 μm or more, 3 μm or more, 5 μm or more, and the like.

  Next, a cavity (recess) for housing the component is provided in the circuit board (FIG. 1B). As schematically shown in FIG. 1B, a cavity 2 a that penetrates between the first and second main surfaces of the circuit board can be provided at a predetermined position of the board 2. The cavity 2a can be formed by a known method using, for example, a drill, a laser, plasma, an etching medium, or the like in consideration of the characteristics of the substrate 2.

  Although only one cavity 2a is shown in FIG. 1B, a plurality of cavities 2a can be provided at predetermined intervals. The pitch between the cavities 2a is preferably short from the viewpoint of miniaturization of the component built-in circuit board. The pitch between the cavities 2a is preferably 10 mm or less, more preferably 9 mm or less, even more preferably 8 mm or less, even more preferably 7 mm or less, and particularly preferably 6 mm or less, although it depends on the opening size of the cavity 2a itself. According to the method of the present invention, even when the cavities are provided at such a short pitch, occurrence of substrate warpage can be suppressed. The lower limit of the pitch between the cavities 2a is usually 1 mm or more, 2 mm or more, although depending on the opening size of the cavities 2a itself. Each pitch between the cavities 2a does not need to be the same across the circuit board, and may be different.

  The opening shape of the cavity 2a is not particularly limited, and may be an arbitrary shape such as a rectangle, a circle, a substantially rectangle, or a substantially circle. Moreover, although the opening dimension of the cavity 2a depends on the design of the circuit wiring, for example, when the opening shape of the cavity 2a is rectangular, it is preferably 5 mm × 5 mm or less, more preferably 3 mm × 3 mm or less, or 2 mm × 2 mm or less. . Although the minimum of the said opening dimension is based also on the dimension of the components accommodated, it is 0.5 mm x 0.5 mm or more normally. The opening shape and opening size of the cavity 2a do not need to be the same over the circuit board and may be different.

  Next, a temporary attachment material is laminated on the second main surface of the circuit board provided with the cavity (FIG. 1C). The tacking material is not particularly limited as long as it has an adhesive surface exhibiting sufficient tackiness for tacking a component, and any conventionally known tacking material may be used in the manufacture of the component built-in circuit board. In the embodiment schematically shown in FIG. 1C, the film-like temporary attachment material 4 is laminated so that the adhesive surface of the temporary attachment material 4 is bonded to the second main surface of the circuit board. Thereby, the adhesive surface of the temporary attachment material 4 comes to be exposed through the cavity 2a.

  Examples of the film-like tacking material include UC series (UV tape for wafer dicing) manufactured by Furukawa Electric Co., Ltd.

  Next, a part is temporarily attached to the adhesive surface of the temporary attachment material exposed through the cavity (FIG. 1D). In the embodiment schematically shown in FIG. 1D, the component 5 is temporarily attached to the adhesive surface of the temporary attachment material 4 exposed through the cavity 2a.

  As the component 5, an appropriate electrical component may be selected according to desired characteristics, and examples thereof include a passive component such as a capacitor, an inductor, and a resistor, and an active component such as a semiconductor bare chip. The same part 5 may be used for all the cavities, or a different part 5 may be used for each cavity.

  When manufacturing a component tack circuit board, in addition to the above method, for example, the circuit wiring 3 may be provided after the cavity 2a is formed in the substrate 2, or the tack material 4 may be provided on the second circuit board. The cavity 2a may be formed after being laminated on the main surface.

  A method for producing a component-embedded circuit board using the resin sheet of the present invention will be described. In the following description, the resin sheets of the present invention laminated on the first main surface and the second main surface of the component-embedded circuit board are referred to as “first resin sheet 10” and “second resin sheet 20”, respectively. May be written. As the 1st resin sheet 10 and the 2nd resin sheet 20, the same thing may be used and a different thing may be used. In the following description, the support 11 of the first resin sheet 10 may be referred to as the first support 11 in order to distinguish the first resin sheet 10 and the second resin sheet 20. .

<(A) 1st lamination process (lamination of 1st resin sheet)>
First, the resin sheet (first resin sheet 10) of the present invention is laminated on a circuit board on which components are temporarily attached (first lamination step). Specifically, the first resin sheet 10 is vacuum-laminated on the circuit board 1 ′ to which the components are temporarily attached so that the curable resin composition layer 12 is bonded to the first main surface of the circuit board (FIG. 3A). See). Here, when the 1st resin sheet 10 is a structure provided with the protective film which covers the curable resin composition layer 12, after laminating | stacking a protective film, lamination | stacking to a circuit board is performed.

  For example, the vacuum lamination of the first resin sheet 10 to the component temporary circuit board 1 ′ is performed by thermocompression bonding the first resin sheet 10 to the component temporary circuit board 1 ′ from the support 11 side under reduced pressure. Can be done. As a member (not shown; hereinafter, also referred to as a “heat-bonding member”) for heat-pressing the first resin sheet 10 to the component temporary circuit board 1 ′, for example, a heated metal plate (SUS end plate, etc.) Or a metal roll (SUS roll) etc. are mentioned. Instead of directly pressing the thermocompression bonding member on the first resin sheet 10, the first resin sheet 10 sufficiently follows the unevenness caused by the circuit wiring 3 and the cavity 2a of the component temporary circuit board 1 ′. It is preferable to press through an elastic material such as heat resistant rubber.

  The thermocompression bonding temperature is preferably in the range of 80 ° C. to 160 ° C., more preferably 100 ° C. to 140 ° C., and the thermocompression bonding pressure is preferably 0.098 MPa to 1.77 MPa, more preferably 0.29 MPa to 1. The range is 47 MPa, and the thermocompression bonding time is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. The vacuum lamination is preferably performed under a reduced pressure condition of a pressure of 26.7 hPa or less.

  Vacuum lamination can be performed with a commercially available vacuum laminator. Examples of the commercially available vacuum laminator include a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nichigo Morton, and a two-stage buildup laminator manufactured by Nichigo Morton.

  After the first lamination step, the laminated first resin sheets 10 are smoothed by pressing the thermocompression bonding member from the first support 11 side under normal pressure (under atmospheric pressure), for example. It is preferable to perform a smoothing step. The pressing conditions for the smoothing step can be the same conditions as the thermocompression bonding conditions for the vacuum lamination.

  The smoothing step can be performed with a commercially available laminator. In addition, you may perform a 1st lamination process and a smoothing process continuously using said commercially available vacuum laminator.

  After passing through the first laminating step, the curable resin composition layer 12 is filled in the cavity 2a, and the component 5 temporarily attached in the cavity 2a is embedded in the curable resin composition layer 12 (FIG. 3B). See).

<(B) Heat treatment process>
Next, the circuit board on which the first resin sheet 10 is laminated is subjected to heat treatment (heat treatment step). The heating temperature in this step is preferably 155 ° C. or lower, more preferably 150 ° C. or lower, further preferably 145 ° C. or lower, and still more preferably 140 ° C. or lower. The lower limit of the heating temperature is preferably 110 ° C. or higher, more preferably 115 ° C. or higher, still more preferably 120 ° C. or higher, and even more preferably 125 ° C. or higher.

  The heating time in the heat treatment step depends on the heating temperature, but is preferably 10 minutes or more, more preferably 15 minutes or more, and further preferably 20 minutes or more. The upper limit of the heating time is not particularly limited, but can usually be 60 minutes or less.

  The heat treatment of the curable resin composition layer 12 in the heat treatment step is preferably performed under atmospheric pressure (normal pressure).

  The heat treatment of the curable resin composition layer 12 in the heat treatment step may be performed with the first support 11 attached to the curable resin composition layer 12, and the first support 11 is peeled off. You may implement after exposing the curable resin composition layer 12. FIG. In a preferred embodiment, the heat treatment of the curable resin composition layer 12 is performed with the first support 11 attached to the first curable resin composition layer 12. This is advantageous in terms of preventing foreign matter adhesion and preventing damage to the curable resin composition layer.

  When the heat treatment of the curable resin composition layer 12 in the heat treatment step is performed with the first support 11 attached, the first support 11 cures the curable resin composition layer 12. What is necessary is just to peel before the process of providing a conductor layer (circuit wiring) in the insulating layer (hardened | cured material) obtained, for example, even if it peels between a 1st heat processing process and the 2nd lamination process mentioned later. The separation may be performed between the second lamination step and the thermosetting step (described later), or may be performed after the thermosetting step. In one suitable embodiment, the 1st support body 11 peels after a thermosetting process. When a metal foil such as a copper foil is used as the first support 11, it is possible to provide a conductor layer (circuit wiring) using such a metal foil as described later. The support 11 may not be peeled off.

  In a preferred embodiment, the circuit board may be cooled to room temperature (room temperature) between the first lamination step and the heat treatment step.

  In a preferred embodiment, the curable resin composition layer 12 becomes a curable resin composition layer (heat-treated body) 12 ′ through the heat treatment step (see FIG. 3C). FIG. 3C shows a mode in which a curable resin composition layer (heat treatment body) 12 ′ is obtained by heat treatment with the first support 11 attached.

<(C) Second Lamination Step (Lamination of Second Resin Sheet)>
After the heat treatment step, the tacking material 4 is peeled off from the second main surface of the circuit board to expose the second main surface of the circuit board 2. Then, the second resin sheet 20 is vacuum laminated so that the curable resin composition layer 22 is bonded to the second main surface (the lower side surface in the drawing) of the circuit board 2 (see FIG. 3D). Here, the second resin sheet includes a support 21 (also referred to as a second support) and a curable resin composition layer 22 (also referred to as a second curable resin composition layer) bonded to the support. . As the second resin sheet, it is preferable to use the resin sheet of the present invention. The configurations of the second support and the second curable resin composition layer are the same as those of the support of the resin sheet and the curable resin composition layer of the present invention described above. In addition, as the second resin sheet, a resin sheet having a configuration different from that of the first resin sheet (for example, a resin sheet having a plurality of curable resin composition layers having different compositions, or the expected minimum in the present invention) Those having a curable resin composition layer that does not satisfy the melt viscosity condition and the average linear thermal expansion coefficient condition) may be used.

  The peeling of the tacking material 4 may be performed according to a conventionally known method according to the type of the tacking material 4. For example, when a UV tape for wafer dicing such as UC series manufactured by Furukawa Electric Co., Ltd. is used as the tacking material 4, the tacking material 4 can be peeled after UV irradiation of the tacking material 4. The conditions such as the UV irradiation amount can be known conditions that are usually employed in the production of the component built-in circuit board.

  Through the heat treatment process, even when a circuit board with a high cavity density or a thin circuit board is used, the occurrence of substrate warpage can be suppressed, so the process from the heat treatment process to the second lamination process. The second stacking step can be smoothly performed without hindering the substrate transfer. Furthermore, since the curable resin composition layer is heat-treated under specific conditions, the positional change (displacement) of the component accompanying the vacuum lamination in the second lamination process can be suppressed, and the arrangement of the components A component built-in circuit board having excellent accuracy can be realized with a high yield.

  The vacuum lamination of the second resin sheet 20 in the second lamination step may employ the same method and conditions as the vacuum lamination of the first resin sheet 10 in the first lamination step.

  In a preferred embodiment, the circuit board may be cooled to room temperature (room temperature) between the heat treatment step and the second lamination step.

  In the second stacking step, the second curable resin composition layer 22 and the second support 21 are stacked on the second main surface of the circuit board 2 (see FIG. 3E).

  The second support 21 may be peeled off before the step of providing a conductor layer (circuit wiring) on the insulating layer obtained by curing the second curable resin composition layer 22. For example, the second laminate 21 You may peel between a process and the hardening process mentioned later, and may peel after a hardening process. In a preferred embodiment, the second support 21 is peeled after the curing step. When a metal foil such as a copper foil is used as the second support 21, it is possible to provide a conductor layer (circuit wiring) using such a metal foil, as will be described later. The support 21 may not be peeled off.

<(D) Curing step>
In the curing step, the curable resin composition layer 12 of the first resin sheet 10 and the second curable resin composition layer 22 of the second resin sheet 20 are thermally cured. Thereby, on the first main surface of the circuit board 2, the curable resin composition layer (heat treatment body) 12 ′ forms the insulating layer 12 ″ (cured product), and on the second main surface of the circuit board 2, The second curable resin composition layer 22 forms an insulating layer 22 ″ (cured product) (see FIG. 3F).

  The conditions for thermosetting are not particularly limited, and conditions usually employed when forming the insulating layer of the component built-in circuit board may be used.

  The thermosetting conditions of the curable resin composition layers 12 and 22 of the first and second resin sheets 10 and 20 are different depending on the composition of the curable resin composition used for each curable resin composition layer, but are cured. The temperature ranges from 120 ° C to 240 ° C (preferably from 150 ° C to 210 ° C, more preferably from 170 ° C to 190 ° C), and the curing time ranges from 5 minutes to 90 minutes (preferably from 10 minutes to 75 minutes). , More preferably 15 minutes to 60 minutes).

  Prior to thermosetting, the curable resin composition layer 12 and the second curable resin composition layers 12 and 22 may be preheated at a temperature lower than the curing temperature. For example, prior to thermosetting, at a temperature of 50 ° C. or higher and lower than 120 ° C. (preferably 60 ° C. or higher and 110 ° C. or lower, more preferably 70 ° C. or higher and 100 ° C. or lower), the curable resin composition layers 12 and 22 are held for 5 minutes. Preheating may be performed as described above (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes). When preheating is performed, such preheating is also included in the curing step.

  The thermosetting of each curable resin composition layer in the curing step is preferably performed under atmospheric pressure (under normal pressure).

  In a preferred embodiment, a process of cooling the circuit board to room temperature (room temperature) may be performed between the second lamination process and the curing process.

  In the present invention, the average linear thermal expansion coefficient between 25 ° C. and 150 ° C. of the insulating layers 12 ″, 22 ″ obtained by curing the curable resin composition layer 12 and the second curable resin composition layer 22 is From the viewpoint of reducing substrate warpage, it is preferably 17 ppm / ° C. or less, more preferably 15 ppm / ° C. or less.

  As mentioned above, although embodiment using a temporary attachment material was described in detail, it may replace with temporary attachment material and may manufacture a circuit board with a built-in component using a resin sheet. The resin sheet that can be used in place of the tacking material may be the same as that of the second resin sheet, and may be the resin sheet of the present invention or another resin sheet. When a resin sheet is used instead of the temporary attachment material, the temporary attachment material peeling step is unnecessary.

<Other processes>
When manufacturing a circuit board with built-in components, a step of drilling an insulating layer (drilling step), a step of roughening the surface of the insulating layer (roughening step), a conductor layer on the roughened insulating layer surface A step of forming (conductor layer forming step) may be included. These steps may be performed according to various methods known to those skilled in the art, which are used for manufacturing a component built-in circuit board. In addition, when peeling the support bodies 11 and 21 of each resin sheet 10 and 20 after a hardening process, peeling of the support bodies 11 and 21 is between a hardening process and a drilling process, between a drilling process and a roughening process. Or you may implement between a roughening process and a conductor layer formation process.

  The drilling step is a step of drilling holes in the insulating layers 12 ″ and 22 ″ (cured product), whereby holes such as via holes can be formed in the insulating layers 12 ″ and 22 ″. For example, holes can be formed in the insulating layers 12 ″ and 22 ″ using a drill, laser (carbon dioxide laser, YAG laser, etc.), plasma, or the like. In the component built-in circuit board, the insulating layers 12 ″ and 22 ″ are generally conducted by via holes.

  The roughening step is a step of roughening the insulating layers 12 ″ and 22 ″. The procedure and conditions for the roughening treatment are not particularly limited, and known procedures and conditions that are normally used when forming the insulating layers 12 ″ and 22 ″ of the component built-in circuit board can be employed. For example, the roughening treatment of the insulating layers 12 ″ and 22 ″ is performed by performing the swelling treatment with the swelling liquid, the roughening treatment with the oxidizing agent, and the neutralization treatment with the neutralizing solution in this order. Can be processed. Although it does not specifically limit as a swelling liquid, An alkaline solution, surfactant solution, etc. are mentioned, Preferably it is an alkaline solution, As this alkaline solution, a sodium hydroxide solution and a potassium hydroxide solution are more preferable. Examples of commercially available swelling liquids include Swelling Dip Securigans P and Swelling Dip Securigans SBU manufactured by Atotech Japan. The swelling treatment with the swelling liquid is not particularly limited, and can be performed, for example, by immersing the insulating layers 12 ″, 22 ″ in the swelling liquid at 30 to 90 ° C. for 1 minute to 20 minutes. From the viewpoint of suppressing the swelling of the resin in the insulating layers 12 ″ and 22 ″ to an appropriate level, it is preferable to immerse the insulating layers 12 ″ and 22 ″ in a swelling solution at 40 to 80 ° C. for 5 seconds to 15 minutes. Although it does not specifically limit as an oxidizing agent, For example, the alkaline permanganate solution which melt | dissolved potassium permanganate and sodium permanganate in the aqueous solution of sodium hydroxide is mentioned. The roughening treatment with an oxidizing agent such as an alkaline permanganic acid solution is preferably performed by immersing the first and second insulating layers in an oxidizing agent solution heated to 60 to 80 ° C. for 10 to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Examples of commercially available oxidizing agents include alkaline permanganate solutions such as Concentrate Compact P and Dosing Solution Securigans P manufactured by Atotech Japan Co., Ltd. As the neutralizing solution, an acidic aqueous solution is preferable, and as a commercially available product, for example, Reduction Sholysin Securigant P manufactured by Atotech Japan Co., Ltd. may be mentioned. The treatment with the neutralizing solution can be performed by immersing the treated surface subjected to the roughening treatment with the oxidant solution in the neutralizing solution at 30 to 80 ° C. for 5 to 30 minutes. From the viewpoint of workability and the like, a method of immersing an object subjected to roughening treatment with an oxidant solution in a neutralizing solution at 40 to 70 ° C. for 5 to 20 minutes is preferable.

  The conductor layer forming step is a step of forming a conductor layer (circuit wiring) on the roughened insulating layer surface.

  The conductor material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer is one or more selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin and indium. Contains metal. The conductor layer may be a single metal layer or an alloy layer. As the alloy layer, for example, an alloy of two or more metals selected from the above group (for example, nickel-chromium alloy, copper- A layer formed from a nickel alloy and a copper / titanium alloy). Among them, from the viewpoint of versatility of conductor layer formation, cost, ease of patterning, etc., single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or nickel / chromium alloy, copper / An alloy layer of nickel alloy or copper / titanium alloy is preferable, and a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or an alloy layer of nickel / chromium alloy is more preferable, and a single layer of copper is preferable. A metal layer is more preferred.

  The conductor layer may have a single layer structure or a multilayer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are laminated. When the conductor layer has a multilayer structure, the layer in contact with the insulating layer is preferably a single metal layer of chromium, zinc or titanium, or an alloy layer of nickel / chromium alloy.

  The thickness of the conductor layer depends on the design of the desired component built-in circuit board, but is generally 3 μm to 35 μm, preferably 5 μm to 30 μm.

  The method for forming the conductor layer is not particularly limited as long as a conductor layer (circuit wiring) having a desired pattern can be formed. In a preferred embodiment, the conductor layer can be formed by plating. For example, the surface of the first and second insulating layers can be plated by a conventionally known technique such as a semi-additive method or a full additive method to form a conductor layer (circuit wiring) having a desired pattern. Hereinafter, an example in which the conductor layer is formed by a semi-additive method will be described.

  First, a plating seed layer is formed on the surfaces of the two insulating layers 12 ″ and 22 ″ by electroless plating. Next, a mask pattern that exposes a part of the plating seed layer corresponding to a desired wiring pattern is formed on the formed plating seed layer. A metal layer is formed by electrolytic plating on the exposed plating seed layer, and then the mask pattern is removed. Thereafter, an unnecessary plating seed layer can be removed by etching or the like to form a conductor layer having a desired pattern.

  Through these steps, a conductor (via wiring) is also formed in the via hole, and the circuit wiring 3 provided on the surfaces of the insulating layers 12 ″ and 22 ″ is electrically connected to the circuit wiring on the circuit board, so that the component built-in circuit A plate 100 is obtained (see FIG. 3G).

  When a metal foil such as a copper foil is used as the first support 11 and the second support 21, a conductor layer may be formed by a subtractive method using the metal foil. Alternatively, the conductive layer may be formed by electrolytic plating using a metal foil as a plating seed layer.

  The method for manufacturing a component built-in circuit board may also include a step of separating the component built-in circuit board.

  In the singulation process, for example, the structure obtained by grinding with a conventionally known dicing apparatus having a rotary blade can be singulated into individual component built-in circuit board units.

[Semiconductor device]
The semiconductor device of the present invention includes the wiring board of the present invention (for example, the above-described component built-in circuit board).

  Examples of such semiconductor devices include various semiconductor devices used for electrical products (for example, computers, mobile phones, digital cameras, and televisions) and vehicles (for example, motorcycles, automobiles, trains, ships, and aircrafts). .

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following description, “parts” and “%” mean “parts by mass” and “% by mass”, respectively, unless otherwise specified.

<Production of resin sheet>
Using the resin varnish (curable resin composition) prepared by the following procedure, resin sheets of Examples and Comparative Examples were produced.

(Preparation of inorganic filler)
Silica 1-6 include “Admafine” manufactured by Admatechs Co., Ltd., “SFP Series” manufactured by Denki Kagaku Kogyo Co., Ltd., “SP (H) Series” manufactured by Nippon Steel & Sumikin Materials Co., Ltd., Sakai Chemical Industry ( After carrying out surface treatment by using "Sciqas series" manufactured by Nippon Shokubai Co., Ltd. and "Seahoster series" manufactured by Nippon Shokubai Co., Ltd., the particle size distribution and specific surface area were measured by the following methods. Examples and Comparative Examples Used for.
As alumina, after surface treatment was performed using “AZ series” and “AX series” manufactured by Nippon Steel & Sumikin Materials Co., Ltd., the particle size distribution and specific surface area were measured by the following methods and used in Example 4. did.

(1) Measurement of average particle diameter 100 mg of powder of silica 1-6 or 100 mg of alumina powder, 0.1 g of dispersant (“SN9228” manufactured by San Nopco Co., Ltd.) and 10 g of methyl ethyl ketone are weighed in a vial, and ultrasonically Dispersed for 20 minutes. Using a laser diffraction particle size distribution analyzer (SALD-2200 manufactured by Shimadzu Corporation), the particle size distribution was measured by the batch cell method, and the average particle size was calculated and shown in Table 2.

(2) Measurement of specific surface area The specific surface areas of silicas 1 to 6 and alumina were measured using a BET fully automatic specific surface area measuring device (Macsorb HM-1210 manufactured by Mountec Co., Ltd.) and shown in Table 2.

(3) Measurement of true density The true densities of silicas 1 to 6 and alumina were measured with a micro-ultra pycnometer (MUTY-21T manufactured by Cantachrome Instruments Japan (same)) and shown in Table 2.

(Preparation of resin varnish 1)
Bisphenol type liquid epoxy resin (“ZX1059” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent of about 169, 1: 1 mixture of bisphenol A type and bisphenol F type) 4 parts, naphthylene ether type epoxy resin (DIC Corporation) 10 parts "EXA-731-G4" manufactured by Epoxy, about 213), 6 parts bixylenol type epoxy resin ("YX4000HK" manufactured by Mitsubishi Chemical Corporation, about 185 epoxy equivalent), biphenyl type epoxy resin (Nippon Kayaku ( "NC3000L", 10 parts of epoxy equivalent 272), and 4 parts of a flame retardant ("PX-200" manufactured by Daihachi Chemical Industry Co., Ltd.) are stirred in a mixed solvent of 20 parts of solvent naphtha and 10 parts of cyclohexanone. The solution was dissolved while heating. After cooling to room temperature, 10 parts of a triazine skeleton-containing cresol novolac curing agent (“LA3018-50P” manufactured by DIC Corporation, hydroxyl equivalent of about 151, 2-methoxypropanol solution with a solid content of 50%), triazine 4 parts of skeleton-containing phenol novolac curing agent ("LA-7054" manufactured by DIC Corporation, MEK solution having a hydroxyl equivalent weight of about 125 and a solid content of 60%), naphthol curing agent ("SN-" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) "495V", hydroxyl group equivalent of about 231, MEK solution having a solid content of 60%) 10 parts, amine curing accelerator (4-dimethylaminopyridine (DMAP), MEK solution having a solid content of 5 mass%) 1 part, aminosilane coupling 2. Spherical silica 1 (average particle size 1.47 μm, specific surface area) surface-treated with an agent (“KBM573” manufactured by Shin-Etsu Chemical Co., Ltd.) 7m ² / g, carbon content 0.30 mg ^/ m 2 per unit surface area) were mixed 220 parts, after uniformly dispersed in a high-speed rotary mixer, and filtered through a cartridge filter (ROKITECHNO Co. "SHP050"), the resin Varnish 1 was prepared.

(Preparation of resin varnish 2)
6 parts of glycidylamine type liquid epoxy resin (Mitsubishi Chemical Corporation “630LSD”, epoxy equivalent of about 95), bixylenol type epoxy resin (Mitsubishi Chemical Corporation “YX4000HK”, epoxy equivalent of about 185), 6 parts 6 parts of AF type epoxy resin (Mitsubishi Chemical Corporation "YL7760", epoxy equivalent of about 238), 15 parts of naphthalene type epoxy resin (Nippon Steel & Sumikin Chemical Co., Ltd. "ESN475V", epoxy equivalent of about 330), and phenoxy resin (Mitsubishi Chemical Co., Ltd. "YX7553BH30", 30 parts by weight of cyclohexanone: methyl ethyl ketone (MEK) 1: 1 solution) 8 parts dissolved in a mixed solvent of 20 parts of solvent naphtha and 5 parts of cyclohexanone while stirring. I let you. After cooling to room temperature, there were 12 parts of a triazine skeleton-containing cresol novolac-based curing agent (“LA3018-50P” manufactured by DIC Corporation, hydroxyl equivalent of about 151, 2-methoxypropanol solution having a solid content of 50%), activity Ester-based curing agent (“EXB-8000L-65M” manufactured by DIC Corporation, MEK solution having an active group equivalent of about 220 and 65% by mass of nonvolatile components), amine-based curing accelerator (4-dimethylaminopyridine (DMAP)) , 1 part of MEK solution having a solid content of 5% by mass, flame retardant (“HCA-HQ”, 10- (2,5-dihydroxyphenyl) -10-hydro-9-oxa-10-phosphor manufactured by Sanko Co., Ltd.) 2 parts of phenanthrene-10-oxide, average particle size 2 μm, 2 parts of rubber particles (EXL2655, manufactured by Dow Chemical Japan Co., Ltd.), phenyltrimeth Shishiran (Shin-Etsu Chemical Co., Ltd., "KBM103") surface-treated with spherical silica 2 (average particle size 1.33, specific surface area 3.38m ² / g, per unit surface area of carbon amount 0.28 mg / ^{m 2} ) 190 parts were mixed and dispersed uniformly with a high-speed rotary mixer, and then filtered through a cartridge filter (“SHP050” manufactured by ROKITECHNO) to prepare a resin varnish 2.

(Preparation of resin varnish 3)
Bisphenol type liquid epoxy resin (“ZX1059” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent of about 169, 1: 1 mixture of bisphenol A type and bisphenol F type) 8 parts, naphthalene type liquid epoxy resin (manufactured by DIC Corporation) 4 parts of “HP4032SS”, epoxy equivalent of about 144), 3 parts of naphthalene type epoxy resin (“HP-4710” manufactured by DIC Corporation, about 170 epoxy equivalent), biphenyl type epoxy resin (“NC3000L” manufactured by Nippon Kayaku Co., Ltd.) ”, 12 parts of epoxy equivalent, and 5 parts of phenoxy resin (“ YX7553BH30 ”manufactured by Mitsubishi Chemical Corporation, 1: 1 solution of cyclohexanone: methyl ethyl ketone (MEK) having a solid content of 30% by mass), 20 parts of solvent naphtha. And dissolved in 5 parts of cyclohexanone by heating with stirring. After cooling to room temperature, 8 parts of a triazine skeleton-containing phenol novolac curing agent ("LA-7054" manufactured by DIC Corporation, MEK solution having a hydroxyl equivalent weight of about 125 and a solid content of 60%), naphthol curing agent 12 parts of “SN-485” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., MEK solution having a hydroxyl equivalent weight of about 212 and a solid content of 60%, imidazole-based curing accelerator (“1B2PZ” 1-benzyl- manufactured by Shikoku Chemicals Co., Ltd.) 1 part of 2-phenylimidazole, 5% solid content MEK solution), flame retardant ("HCA-HQ" manufactured by Sanko Co., Ltd.), 10- (2,5-dihydroxyphenyl) -10-hydro-9-oxa-10 -Phosphaphenanthrene-10-oxide (average particle size 2 μm) 4 parts, surface treated with an aminosilane coupling agent (“KBM573” manufactured by Shin-Etsu Chemical Co., Ltd.) Spherical silica 3 (average particle size 1.06 .mu.m, specific surface area 3.01m ² / g, carbon content 0.31 mg ^/ m 2 per unit surface area) 140 parts were mixed, after uniformly dispersed in a high-speed rotary mixer, the cartridge The resin varnish 3 was prepared by filtering with a filter (“SHP050” manufactured by ROKITECHNO).

(Preparation of resin varnish 4)
50 parts of the component (d) produced as described below, bisphenol type epoxy resin (“ZX1059” manufactured by Nippon Steel Chemical Co., Ltd., 1: 1 mixture of bisphenol A type and bisphenol F type, epoxy equivalent 169) 3 Parts, bisphenol AF type epoxy resin (Mitsubishi Chemical Corporation "YL7760", epoxy equivalent of about 238), and flame retardant (Sanko Co., Ltd. "HCA-HQ", 10- (2,5-dihydroxyphenyl) ) -10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, average particle size 2 μm) 2 parts were heated and dissolved in a mixed solvent of 15 parts solvent naphtha and 5 parts cyclohexanone with stirring. . There, 2 parts of an active ester curing agent (“EXB-8000L-65M” manufactured by DIC Corporation, an MEK solution having an active group equivalent of about 220 and 65% by mass of a non-volatile component), an imidazole curing accelerator (Shikoku Chemical Industries ( Co., Ltd. "1B2PZ" 1-benzyl-2-phenylimidazole, 5 parts solid MEK solution 1 part, and phenylaminosilane coupling agent (Shin-Etsu Chemical Co., Ltd., "KBM573") surface treatment 190 parts of spherical alumina (average particle size 1.52 μm, specific surface area 1.70 m ² / g, carbon amount per unit surface area 0.11 mg / m ² ), and uniformly dispersed with a high-speed rotary mixer, The resin varnish 4 was produced by filtration through a cartridge filter (“SHP050” manufactured by ROKITECHNO).

[Production of component (d)]
In a reaction vessel, 50 g of G-3000 (bifunctional hydroxyl group-terminated polybutadiene, number average molecular weight = 5047 (GPC method), hydroxyl group equivalent = 1798 g / eq., Solid content: 100 mass%: Nippon Soda Co., Ltd.) 23.5 g of ipsol 150 (aromatic hydrocarbon-based mixed solvent: manufactured by Idemitsu Petrochemical Co., Ltd.) and 0.005 g of dibutyltin laurate were mixed and dissolved uniformly. When the temperature became uniform, the temperature was raised to 50 ° C., and while further stirring, 4.8 g of toluene-2,4-diisocyanate (isocyanate group equivalent = 87.08 g / eq.) Was added and the reaction was carried out for about 3 hours. The reaction was then cooled to room temperature before 8.96 g benzophenonetetracarboxylic dianhydride (acid anhydride equivalent = 161.1 g / eq.), 0.07 g triethylenediamine, and ethyl diglycol. 40.4 g of acetate (manufactured by Daicel Corporation) was added, the temperature was raised to 130 ° C. with stirring, and the reaction was carried out for about 4 hours. The disappearance of the NCO peak at 2250 cm −1 was confirmed by FT-IR. Confirming the disappearance of the NCO peak was regarded as the end point of the reaction, and the reaction product was cooled to room temperature and then filtered through a 100 mesh filter cloth to obtain a polymer resin A having an imide skeleton, a urethane skeleton, and a butadiene skeleton.
Viscosity: 7.5 Pa · s (25 ° C, E-type viscometer)
Acid value: 16.9 mgKOH / g
Solid content: 50% by mass
Number average molecular weight: 13723
Glass transition temperature: -10 ° C
Content ratio of polybutadiene structure part: 50 / (50 + 4.8 + 8.96) × 100 = 78.4% by mass

(Preparation of resin varnish 5)
Instead of 1,220 parts of silica in the resin varnish 1, 220 parts of silica 4 (average particle size 1.73 μm, specific surface area 2.71 m ² / g, carbon amount per unit surface area 0.26 mg / m ² ) were used, A resin varnish 5 was prepared in the same manner as the resin varnish 1 except that it was a cartridge filter (“SHP100” manufactured by ROKITECHNO).

(Preparation of resin varnish 6)
Instead of silica ^{2 and} 190 parts of resin varnish 2, 190 parts of silica 5 (average particle size 1.11 μm, specific surface area 2.66 m ² / g, carbon amount per unit surface area 0.22 mg / m ² ) should be used. Except for the above, resin varnish 6 was prepared in the same manner as resin varnish 2.

(Preparation of resin varnish 7)
Instead of silica 3 and 140 parts of resin varnish 3, 120 parts of silica 6 (average particle size 0.77 μm, specific surface area 5.76 m ² / g, carbon amount per unit surface area 0.35 mg / m ² ) should be used. Except for the above, resin varnish 7 was prepared in the same manner as resin varnish 3.

(Preparation of resin varnish 8)
10 parts of naphthalene type epoxy resin (Nippon Steel & Sumikin Chemical Co., Ltd. "ESN475V", epoxy equivalent of about 330), 5 parts of naphthalene type epoxy resin (DIC Corporation "HP-4710", epoxy equivalent of about 170), biphenyl type 12 parts of epoxy resin (Nippon Kayaku Co., Ltd. “NC3000L”, epoxy equivalent of about 272), and phenoxy resin (Mitsubishi Chemical Co., Ltd. “YX7553BH30”, solid content 30% by mass of cyclohexanone: methyl ethyl ketone (MEK) 1 1 solution) 5 parts was dissolved by heating in a mixed solvent of 20 parts of solvent naphtha and 10 parts of cyclohexanone with stirring. After cooling to room temperature, 8 parts of a triazine skeleton-containing phenol novolac curing agent ("LA-7054" manufactured by DIC Corporation, MEK solution having a hydroxyl equivalent weight of about 125 and a solid content of 60%), naphthol curing agent 12 parts of “SN-485” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., MEK solution having a hydroxyl equivalent weight of about 212 and a solid content of 60%, imidazole-based curing accelerator (“1B2PZ” 1-benzyl- manufactured by Shikoku Chemicals Co., Ltd.) 1 part of 2-phenylimidazole, 5% solid content MEK solution), flame retardant ("HCA-HQ" manufactured by Sanko Co., Ltd.), 10- (2,5-dihydroxyphenyl) -10-hydro-9-oxa-10 -Phosphaphenanthrene-10-oxide (average particle size 2 μm) 4 parts, surface treated with an aminosilane coupling agent (“KBM573” manufactured by Shin-Etsu Chemical Co., Ltd.) Spherical silica 3 (average particle size 1.06 .mu.m, specific surface area 3.01m ² / g, carbon content 0.31 mg ^/ m 2 per unit surface area) 140 parts were mixed, after uniformly dispersed in a high-speed rotary mixer, the cartridge The resin varnish 8 was prepared by filtering with a filter (“SHP050” manufactured by ROKITECHNO).

  Table 1 shows the materials used for the production of each resin varnish and the blending amount (mass part of non-volatile content). Regarding the (a1) liquid epoxy resin and (c) inorganic filler, the content (% by mass) in the nonvolatile component is also shown in Table 1.

(Examples 1-4 and Comparative Examples 1-4: Production of resin sheet)
As a support, a PET film (“Lumirror T6AM” manufactured by Toray Industries, Inc.) having a release treatment with an alkyd resin release agent (“AL-5” manufactured by Lintec Corporation), a thickness of 38 μm, a softening point of 130 ° C., “release” Type PET ").
Each resin varnish is uniformly applied with a die coater so that the thickness of the curable resin composition layer after drying is 25 μm on the release PET, and dried at 80 ° C. to 110 ° C. for 4 minutes. A curable resin composition layer was obtained on the mold PET. Next, a polypropylene film (“Alphan MA-430” manufactured by Oji F-Tex Co., Ltd., thickness 20 μm) is used as a protective film on the surface of the curable resin composition layer that is not bonded to the support, and the curable resin composition. The layers were laminated so as to be bonded to the layers. Thereby, the resin sheet which consists of a support body, the curable resin composition layer, and the order of the protective film was obtained.

(Measurement of minimum melt viscosity of curable resin composition layer)
(1) Measurement of minimum melt viscosity Only pellets for measurement (diameter 18 mm, 1.2 to 1.3 g) were prepared by peeling only the curable resin composition layer from the release PET and compressing it with a mold.
Using pellets for measurement, using a dynamic viscoelasticity measuring device (“Rheosol-G3000” manufactured by UBM Co., Ltd.), using a parallel plate having a diameter of 18 mm for 1 g of the sample resin composition layer, The temperature was raised from a starting temperature of 60 ° C. to 200 ° C. at a rate of temperature increase of 5 ° C./min. The melt viscosity was calculated and shown in Table 2.

(Measurement of average linear thermal expansion coefficient of cured product (insulating layer) of curable resin composition layer)
The untreated surface of the release PET film (Lintec Co., Ltd. “501010”, thickness 38 μm, 240 mm square) is a glass cloth base epoxy resin double-sided copper-clad laminate (Matsushita Electric Works, Ltd. “R5715ES”, thickness 0. 7 mm, 255 mm square) was placed on a glass cloth base epoxy resin double-sided copper-clad laminate, and the four sides of the release PET film were fixed with polyimide adhesive tape (width 10 mm).

  Each resin sheet (200 mm square) produced in the examples and comparative examples was separated from the curable resin composition layer using a batch type vacuum pressure laminator (Nichigo Morton 2-stage buildup laminator CVP700). Lamination was performed at the center so as to contact the release surface of the molded PET film. The laminating process was performed by reducing the pressure for 30 seconds to a pressure of 13 hPa or less and then pressing the film at 100 ° C. and a pressure of 0.74 MPa for 30 seconds.

  Next, the film was thermally cured at 100 ° C. for 30 minutes after being placed in an oven at 100 ° C. and then transferred to an oven at 175 ° C. under a temperature condition of 175 ° C. for 30 minutes. Thereafter, the substrate was taken out in a room temperature atmosphere, and the release PET (support) was peeled off from the resin sheet, and then the curable resin composition layer was thermally cured under curing conditions for 90 minutes after being placed in an oven at 190 ° C. .

  After thermosetting, the polyimide adhesive tape was peeled off, and the curable resin composition layer was removed from the glass cloth base epoxy resin double-sided copper-clad laminate. Further, the release PET film (“501010” manufactured by Lintec Corporation) on which the curable resin composition layer was laminated was peeled to obtain a sheet-like cured product. The obtained cured product was cut into a test piece having a width of 5 mm and a length of 15 mm, and thermomechanical analysis was performed by a tensile load method using a thermomechanical analyzer (“Thermo Plus TMA8310” manufactured by Rigaku Corporation). It was. Specifically, after the test piece was mounted on the thermomechanical analyzer, the test piece was measured twice continuously under the measurement conditions of a load of 1 g and a heating rate of 5 ° C./min. The average linear thermal expansion coefficient (ppm / ° C.) in the plane direction in the range from 30 ° C. to 150 ° C. was calculated and shown in Table 2.

<Evaluation test>
1. Evaluation of component embeddability Using the resin sheets prepared in the examples and comparative examples, a component provisional circuit board was produced according to the following procedure, and component embeddability was evaluated.

(1) Preparation of component temporary mounting circuit board (cavity board) Glass cloth base BT resin double-sided copper clad laminate (copper foil thickness 18 μm, board thickness 0.15 mm, “HL832NSF LCA” manufactured by Mitsubishi Gas Chemical Co., Ltd.) On the entire surface of 255 * 340 mm size, a cavity and a conductor pattern of 0.7 × 1.1 mm were formed with the design of the attached material. Next, both sides are etched by 1 μm with a micro-etching agent (“CZ8100” manufactured by Mec Co., Ltd.) to roughen the copper surface, and further subjected to rust prevention (“CL8300” manufactured by Mec Co., Ltd.). Dry at 30 ° C. for 30 minutes.

(2) Fabrication of component temporary circuit board A batch of 25um thick polyimide film with adhesive (polyimide 38um thickness, manufactured by Arisawa Manufacturing Co., Ltd., "PFDKE-1525TT") is batched on one side of the board obtained in (1). Using a pressure-type vacuum press laminator (2-stage build-up laminator “CVP700” manufactured by Nichigo Morton Co., Ltd.), the adhesive was placed so as to be bonded to the substrate and laminated on one side. Lamination was performed by reducing the pressure for 30 seconds to a pressure of 13 hPa or less and then pressing the film at 80 ° C. and a pressure of 0.74 MPa for 30 seconds. Next, multilayer ceramic capacitor components (1005 = 1 * 0.5 mm size, thickness 0.14 mm) were temporarily attached to the cavities one by one to produce a component temporary circuit board (cavity substrate).

(3) Evaluation test of part embedding property Using a batch type vacuum pressure laminator (two-stage buildup laminator “CVP700” manufactured by Nichigo-Morton Co., Ltd.), a protective film is formed from the resin sheets produced in Examples and Comparative Examples. The curable resin composition layer that has been peeled and exposed is joined to the surface of the component temporary circuit board (cavity substrate) prepared in (2) on the side opposite to the surface on which the polyimide film with adhesive is disposed. Laminated. Lamination was performed by reducing the pressure for 30 seconds to a pressure of 13 hPa or less, and then pressure bonding at 120 ° C. and a pressure of 0.74 MPa for 30 seconds. Next, the laminated resin sheets were smoothed by hot pressing at 120 ° C. and a pressure of 0.5 MPa for 60 seconds under atmospheric pressure. Evaluation board | substrate A was produced by peeling the polyimide film with an adhesive from the component provisional circuit board cooled to room temperature. From the surface of the evaluation substrate A from which the polyimide film was peeled, the resin flow in the cavity was observed with an optical microscope (150 times) (10 cavities), and component embedding was evaluated according to the following criteria. The results are shown in Table 2. .
○: In all the cavities, the outer peripheral portion of the multilayer ceramic capacitor component is covered with resin.
X: Some of the cavities have voids or are not embedded with resin in the outer peripheral portion of the multilayer ceramic capacitor component.
It was judged.

2. Evaluation of warpage (1) Curing of resin sheet The evaluation substrate A produced in (3) was subjected to a heat treatment for 30 minutes after being placed in an oven at 100 ° C. under a temperature condition of 100 ° C., cooled to room temperature, and then the same as the surface from which the polyimide film with adhesive was peeled off. 1. Resin sheet Bonding was performed under the same conditions as in (3). Then, after being put in an oven at 100 ° C. for 30 minutes after being put into an oven at 100 ° C., and then transferred to an oven at 175 ° C. under a temperature condition of 175 ° C. for 30 minutes, thermosetting is performed, and insulating layers are formed on both sides of the substrate. Formed. Thereafter, the substrate on which the insulating layers are formed on both sides is taken out in a room temperature atmosphere, the release PET on both sides is peeled off, and the thermosetting resin composition is further cured at 190 ° C. for 90 minutes after being placed in an oven at 190 ° C. The component built-in circuit board was produced by thermosetting the layer, and used as an evaluation board B.

(2) Evaluation test of warpage amount After cutting the evaluation board B into 45 mm square pieces (n = 5), a reflow apparatus (“HAS-” manufactured by Nippon Antom Co., Ltd.) that reproduces the solder reflow temperature at a peak temperature of 260 ° C. 6116 ") (reflow temperature profile conforms to IPC / JEDEC J-STD-020C). Next, the lower surface of the substrate is heated with a reflow temperature profile conforming to IPC / JEDEC J-STD-020C (peak temperature 260 ° C.) using a shadow moire apparatus (“Thermoire AXP” manufactured by Akrometrix), The displacement (μm) of the 10 mm square part was measured, and the results are shown in Table 2.

In Table 2, along with the evaluation results, in the resin sheets of Examples and Comparative Examples, the type of resin varnish used for forming each curable resin composition layer, the type of inorganic filler, the content (mass%), the average Particle size (μm), specific surface area (m ² / g), true density (g / cm ³ ), product of true density and specific surface area, minimum melt viscosity (poise) of curable resin composition layer, insulation layer The average linear thermal expansion coefficient (ppm / ° C.) is also shown.

DESCRIPTION OF SYMBOLS 1 ... Circuit board 2 ... Board | substrate 2a ... Cavity 3 ... Conductor layer (circuit wiring)
4 ... Temporary material 5 ... Parts 10 ... Resin sheet (first resin sheet)
11 ... Support (first support)
12 ... curable resin composition layer 12 '... curable resin composition layer (heat-treated body)
12 "... insulating layer 20 ... 2nd resin sheet 21 ... 2nd support body 22 ... 2nd curable resin composition layer 22 '... 2nd curable resin composition layer (heat-processing body)
22 "... insulating layer 100 ... wiring board (component built-in circuit board)

Claims (10)

A resin sheet comprising a support and a curable resin composition layer provided on the support,
The curable resin composition layer includes an inorganic filler,
The content of the inorganic filler in the curable resin composition layer is 74% by mass or more,
The average particle size of the inorganic filler is 1.6 μm or less, and the product of the specific surface area [m ² / g] and the true density [g / cm ³ ] of the inorganic filler is 6 to 8,
The resin sheet whose minimum melt viscosity of a curable resin composition layer is 12000 poise or less.   The resin sheet according to claim 1, wherein the inorganic filler is silica. The curable resin composition layer includes (a) an epoxy resin,
The epoxy resin includes a liquid epoxy resin,
The resin sheet according to claim 1 or 2, wherein the content of the liquid epoxy resin in the curable resin composition layer is 1% by mass or more. (A) The epoxy resin further contains a solid epoxy resin,
4. The resin sheet according to claim 3, wherein the ratio (M _S / M _L ) of the mass M _S of the solid epoxy resin to the mass M _L of the liquid epoxy resin in the curable resin composition layer is 0.6 to 10. 5. .   The resin sheet according to claim 3 or 4, wherein (a) the epoxy resin is (a ') an epoxy resin having an aromatic structure. The curable resin composition layer further includes at least one component selected from component (d): a resin having a functional group having a glass transition temperature of 25 ° C. or lower, and a resin having a functional group that is liquid at 25 ° C. resin,
The resin sheet according to any one of claims 3 to 5, comprising: The component (d) has one or more functional groups selected from a hydroxyl group, an acid anhydride group, a phenolic hydroxyl group, an epoxy group, an isocyanate group, and a urethane group,
1 selected from an alkylene structural unit, an alkyleneoxy structural unit, a butadiene structural unit, an isoprene structural unit, an isobutylene structural unit, a chloroprene structural unit, a urethane structural unit, a polycarbonate structural unit, a (meth) acrylate structural unit, and a polysiloxane structural unit The resin sheet of Claim 6 which has the above structural unit.   The resin sheet according to claim 1, wherein the resin sheet is for a component built-in circuit board. An insulating layer formed by curing the curable resin composition layer of the resin sheet according to any one of claims 1 to 8,
A wiring board comprising a conductor layer.   A semiconductor device comprising the wiring board according to claim 9.

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