JP6657865B2 - Resin sheet - Google Patents

Description

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

  In recent years, demand for small high-performance electronic devices such as smartphones and tablet PCs has been increasing. Along with this, there is a demand for further enhanced functions and smaller size of printed wiring boards used for these small electronic devices.

  Components such as bare chips, chip capacitors, and chip inductors 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 mounting amount is limited, and it is necessary to respond to recent demands for higher functionality and smaller size of printed wiring boards. Was difficult.

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

Japanese Patent No. 4114629

By the way, in order to improve the component embedding property in the concave portion (cavity) where the component of the component built-in circuit board is arranged, the content of the inorganic filler in the resin composition used for embedding the component with emphasis on resin flow. It is conceivable to use a resin having a relatively small molecular weight while suppressing the thermal expansion. 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 decreases the component embedding property in the cavity. There was a problem that it was easy.
Therefore, an object of the present invention is to provide a resin sheet that reduces the warpage of a substrate and has excellent component embedding properties.

The present inventors have conducted intensive studies on the above problems, and as a result, the curable resin composition forming the curable resin composition layer has an average particle size of 1.6 μm or less and a specific surface area [m ² / g] and a product of the true density [g / cm ³ ] of at least 74% by mass of an inorganic filler having a value of 6 to 8, and by setting the minimum melt viscosity of the curable resin composition layer to 12000 poise or less, The inventors have found that the above problems can be solved, and have completed the present invention. The present invention is based on such a new finding.

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 contains an inorganic filler, and the curable resin composition layer The content of the inorganic filler therein 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] of the inorganic filler and the true density [g / cm]. ³ ], and the minimum melt viscosity of the 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 contains (a) an epoxy resin, the epoxy resin contains 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], wherein
[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, and 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 further comprises 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 which is liquid at 25 ° C. 1 The resin sheet according to any one of [3] to [5], comprising at least one kind of 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, and has an alkylene structural unit and an alkyleneoxy structural unit. Having one or more structural units selected from butadiene structural units, isoprene structural units, isobutylene structural units, chloroprene structural units, urethane structural units, polycarbonate structural units, (meth) acrylate structural units, and polysiloxane structural units [6. ] The resin sheet according to [1].
[8] The resin sheet according to any one of [1] to [7], which is for a circuit board with a built-in component.
[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 the component embedding property can be provided.

FIG. 1A is a schematic diagram (1) illustrating a procedure for preparing a circuit board to which components are temporarily attached, which is used in the method of manufacturing a component-embedded circuit board using the resin sheet of the present invention. FIG. 1B is a schematic diagram (2) showing one procedure for preparing a circuit board to which components are temporarily attached, which is used in the method of manufacturing a component-containing circuit board using the resin sheet of the present invention. FIG. 1C is a schematic diagram (3) illustrating a procedure for preparing a circuit board to which components are temporarily attached, which is used in the method of manufacturing a component-embedded circuit board using the resin sheet of the present invention. FIG. 1D is a schematic diagram (4) illustrating a procedure for preparing a circuit board to which components are temporarily attached, 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 diagram showing one embodiment of the resin sheet of the present invention. FIG. 3A is a schematic diagram (1) illustrating a method for manufacturing a component built-in circuit board using the resin sheet of the present invention. FIG. 3B is a schematic diagram (2) illustrating a method for manufacturing a component built-in circuit board using the resin sheet of the present invention. FIG. 3C is a schematic diagram (3) for explaining the method for manufacturing the component built-in circuit board using the resin sheet of the present invention. FIG. 3D is a schematic view (4) illustrating a method for manufacturing a component-embedded circuit board using the resin sheet of the present invention. FIG. 3E is a schematic view (5) illustrating a method for manufacturing a component-embedded circuit board using the resin sheet of the present invention. FIG. 3F is a schematic view (6) illustrating a method for manufacturing a component built-in circuit board using the resin sheet of the present invention. FIG. 3G is a schematic diagram (7) for explaining the method for 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, the curable resin composition (“the resin composition layer”) used to form the curable resin composition layer (also referred to as “resin composition layer”) Resin composition ”).

<Curable resin composition>
The curable resin composition forming the curable resin composition layer has an average particle diameter of 1.6 μm or less and a product of the specific surface area [m ² / g] and the true density [g / cm ³ ] of 6. No particular limitation is imposed as long as the cured product (insulating layer) has sufficient hardness and insulating properties. Examples of the curable resin composition include a composition containing a curable resin and a curing agent thereof together with an inorganic filler. As the curable resin, a conventionally known curable resin used for forming an insulating layer of a printed wiring board can be used, and among them, an epoxy resin is preferable. Thus, in one embodiment, the curable resin composition comprises (a) an epoxy resin, (b) a curing agent, and (c) an inorganic filler. In one preferred embodiment, the curable resin composition has (a ′) an epoxy resin having an aromatic structure, (b) a curing agent, (c) an inorganic filler, and (d) a glass transition temperature. It includes a resin having a functional group at 25 ° C. or lower, and one or more resins selected from a resin having a functional group that is liquid at 25 ° C. In the present invention, the curable resin composition may further contain, if necessary, additives such as a thermoplastic resin, a curing accelerator, a flame retardant, and rubber particles.

  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 of the curable resin composition, And at least one resin selected from resins having a functional group which is liquid at 25 ° C., and (e) additives.

(A) Epoxy resin Examples of the epoxy resin include bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, bisphenol AF epoxy resins, and other bisphenol epoxy resins, dicyclopentadiene 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, glycidylamine type epoxy resin, glycidyl ester type Epoxy resin, cresol novolak type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having butadiene structure, alicyclic Examples include a formula epoxy resin, a heterocyclic epoxy resin, a spiro ring-containing epoxy resin, a cyclohexane dimethanol type epoxy resin, a naphthylene ether type epoxy resin, a trimethylol type epoxy resin, and a tetraphenylethane type epoxy resin. One epoxy resin may be used alone, or two or more epoxy resins may be used in combination.

  The epoxy resin is selected from the group consisting of bisphenol type epoxy resin, fluorine type epoxy resin (for example, bisphenol AF type epoxy resin), dicyclopentadiene type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin and a mixture of these epoxy resins. It is preferable to use one 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 epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, bisphenol AF Bisphenol type epoxy resin such as type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol 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, cresol novolak type epoxy resin, biphenyl type epoxy resin, naphthylene ether type epoxy resin, tetraphenylethane type epoxy resin and the like. That.

  From the viewpoint that the minimum melt viscosity of the curable resin composition layer can be reduced, the epoxy resin preferably contains a liquid epoxy resin at room temperature (hereinafter, referred to as a “liquid epoxy resin”). In addition, in this specification, "normal temperature" means 25 degreeC.

  Further, the epoxy resin preferably contains an epoxy resin having two or more epoxy groups in one 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 normal temperature (hereinafter referred to as “solid epoxy resin”). ) Is preferable. By using a liquid epoxy resin and a solid epoxy resin together as the epoxy resin, a curable resin composition having excellent flexibility can be obtained. Further, the breaking strength of the cured product (insulating layer) of the curable resin composition is also improved.

  Examples of the liquid epoxy resin (a1) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, phenol novolak type epoxy resin, and alicyclic ring having ester skeleton. Formula epoxy resins and epoxy resins having a butadiene structure are preferred, and bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol AF epoxy resins, and naphthalene epoxy resins are more preferred. Particularly, an epoxy resin containing an aromatic skeleton is also preferable for lowering the average linear thermal expansion coefficient. Specific examples of the liquid epoxy resin include “HP4032”, “HP4032D”, and “HP4032SS” (naphthalene-type epoxy resin) manufactured by DIC Corporation, “828US” and “jER828EL” (bisphenol A) manufactured by Mitsubishi Chemical Corporation. Type epoxy resin), "jER807" (bisphenol F type epoxy resin), "jER152" (phenol novolak type epoxy resin), "YL7760" (bisphenol AF type epoxy resin), "ZX1059" (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) A mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin), "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Corporation, "Celoxide 2021P" (ester skeleton) 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.

  Examples of the solid epoxy resin (a2) include a naphthalene type tetrafunctional epoxy resin, a cresol novolak type epoxy resin, a dicyclopentadiene type epoxy resin, a trisphenol type epoxy resin, a naphthol type epoxy resin, a biphenyl type epoxy resin, and a naphthylene ether type An epoxy resin, an anthracene type epoxy resin, a bisphenol A type epoxy resin, and a tetraphenylethane type epoxy resin are preferred, and a naphthalene type tetrafunctional epoxy resin, a naphthol type epoxy resin, and a biphenyl type epoxy resin are more preferred. In particular, a polyfunctional epoxy resin is preferable for increasing the number of crosslinking points and lowering the average coefficient of linear thermal expansion. Specific examples of the solid epoxy resin include “HP4032H” (naphthalene-type epoxy resin), “HP-4700”, “HP-4710” (naphthalene-type tetrafunctional epoxy resin), and “N-690” manufactured by DIC Corporation. (Cresol novolak epoxy resin), "N-695" (cresol novolak epoxy resin), "HP-7200", "HP-7200HH" "HP-7200L", (dicyclopentadiene epoxy resin), "EXA7311" "EXA7311-G3", "EXA7311-G4", "EXA7311-G4S", "HP6000" (naphthylene ether type epoxy resin), "EPPN-502H" (Nippon Kayaku Co., Ltd.) (trisphenol type epoxy) Resin), "NC7000L" (naphthol novolak 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 (Mitsubishi Chemical Corporation) "PG-100" and "CG-500" manufactured by Mitsubishi Chemical Corporation, "YL7800" (fluorene type epoxy resin), "jER1010" manufactured by Mitsubishi Chemical Corporation (solid bisphenol A type epoxy) 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 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 And iii) an effect of obtaining a cured product (insulating layer) having a 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. And more preferably 5% by mass or more. The upper limit of the content of the epoxy resin is not particularly limited as long as the effects of the present invention are exerted, but is preferably 40% by mass or less, more preferably 35% by mass or less, and further preferably 30% by mass or less.
Therefore, the content of the epoxy resin (a) 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 nonvolatile component in the curable resin composition is 100% by mass, unless otherwise specified.

  The epoxy equivalent of the epoxy resin is preferably from 50 to 5,000, more preferably from 50 to 3,000, further preferably from 80 to 2,000, and still more preferably from 110 to 1,000. When the content falls within this range, the crosslinked density of the cured product becomes sufficient and an insulating layer having a small surface roughness can be obtained. The epoxy equivalent can be measured according to JIS K7236 and is the mass of a resin containing one equivalent of an epoxy group.

  The weight average molecular weight of the epoxy resin is preferably from 100 to 5000, more preferably from 250 to 3000, and still more preferably from 400 to 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 the epoxy resin. Examples thereof include a phenol-based curing agent, a naphthol-based curing agent, an active ester-based curing agent, a benzoxazine-based curing agent, and a cyanate ester. And a carbodiimide-based curing agent. One type of curing agent may be used alone, or two or more types may be used in combination.

  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 a conductor layer (circuit wiring), a nitrogen-containing phenol-based curing agent is preferable, and a phenol resin having a triazine structure and an alkylphenol resin having a triazine structure are more preferable. Among them, it is preferable to use a triazine structure-containing phenol-based curing agent from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion (peeling strength) with the conductor layer.

  Specific examples of the phenol-based curing agent and the naphthol-based curing agent include, for example, “MEH-7700”, “MEH-7810”, “MEH-7851” manufactured by Meiwa Kasei Co., Ltd., and “MEH-7851” manufactured by Nippon Kayaku Co., Ltd. “NHN”, “CBN”, “GPH”, “SN170”, “SN180”, “SN190”, “SN475”, “SN485”, “SN495”, “SN375”, “SN395” manufactured by Toto Kasei Co., Ltd. "LA7052", "LA7054" and "LA3018" manufactured by DIC Corporation.

  The active ester-based curing agent is not particularly limited, but generally has a highly reactive ester group such as a phenol ester, a thiophenol ester, an N-hydroxyamine ester, or an ester of a heterocyclic hydroxy compound in one molecule. Are preferably used. The active ester-based 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-based curing agent obtained from a carboxylic acid compound and a hydroxy compound is preferable, and an active ester-based 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, phenolphthalein, 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, Benzene triol, dicyclopentadienyl diphenol, phenol novolak and the like can be mentioned.

  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 phenol novolak, and an active ester compound containing a benzoylated phenol novolak are preferred. Among them, an active ester compound having a naphthalene structure and an active ester compound having a dicyclopentadienyl diphenol structure are more preferable.

  As a commercially available active ester-based curing agent, as an active ester compound having a dicyclopentadienyl diphenol structure, "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T" (DIC Corporation) EXB9416-70BK (manufactured by DIC Corporation) as an active ester compound having a naphthalene structure, and DCDC (manufactured by Mitsubishi Chemical Corporation) as an active ester compound containing an acetylated phenol novolak. Examples of an active ester compound containing a benzoyl compound include “YLH1026” (manufactured by Mitsubishi Chemical Corporation).

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

  Examples of the cyanate ester-based curing agent include bisphenol A dicyanate, polyphenol cyanate (oligo (3-methylene-1,5-phenylene cyanate)), 4,4′-methylenebis (2,6-dimethylphenyl cyanate), 4'-ethylidene diphenyl 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 novolak and Polyfunctional cyanate resin derived from resol novolac, these cyanate resins and partially triazine of prepolymer. Specific examples of the cyanate ester-based curing agent include “PT30” and “PT60” (both are phenol novolac-type polyfunctional cyanate ester resins) and “BA230” (part or all of bisphenol A dicyanate) manufactured by Lonza Japan Co., Ltd. Is a tripolymer which is triazine-modified to form a trimer).

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

  In the present invention, (b) the curing agent preferably contains at least one selected from a phenol-based curing agent, a cyanate ester-based curing agent, and an active ester-based curing agent. More preferably, the composition contains at least one selected from an alkylphenol-based resin, a cyanate ester-based curing agent, and an active ester-based curing agent.

The content of the curing agent (b) in the curable resin composition is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.1% by mass, from the viewpoint of obtaining an insulating layer having a high peel strength and a low dielectric loss tangent. It is at least 5% by mass, more preferably at least 1% by mass. (B) The upper limit of the content of the curing agent is not particularly limited as long as the effects of the present invention are exerted, but is preferably 30% by mass or less, more preferably 25% by mass or less, and still more preferably 20% by mass or less. is there.
Therefore, the content of the curing agent (b) 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) the epoxy resin to the (b) curing agent is a ratio of [(a) the total number of epoxy groups of the epoxy resin]: [(b) the total number of reactive groups of the curing agent], and is 1: The range is preferably from 0.2 to 1: 2, more preferably from 1: 0.3 to 1: 1.5, and still more preferably from 1: 0.4 to 1: 1. Here, the reactive group of the curing agent is an active hydroxyl group, an active ester group, or the like, and differs depending on the type of the curing agent. In addition, the total number of epoxy groups of the epoxy resin is a value obtained by summing a value obtained by dividing the mass of the solid content of each epoxy resin by an epoxy equivalent for the epoxy resin, and the total number of reactive groups of the curing agent is The value obtained by dividing the mass of the solid content of the agent by the equivalent of the reactive group is the sum of all the curing agents. By setting the ratio between the epoxy resin and the curing agent in such a range, the heat resistance of the cured product (insulating layer) of the curable resin composition is further improved.

(C) Inorganic Filler The inorganic filler has an average particle diameter 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 not limited as long as it is 6 to 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, titanium Barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and phosphoric acid zirconium tungstate, and the like. Among these, silica is particularly preferred. As the silica, spherical silica is preferable. One kind of the inorganic filler may be used alone, or two or more kinds may be used in combination. Commercially available silica used as an inorganic filler include, for example, "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 Hostar Series" manufactured by Nippon Shokubai Co., Ltd., and commercial products of alumina include "AZ, AX" manufactured by Nippon Steel & Sumikin Materials Co., Ltd. Series "and the like.

  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, more preferably 1.4 μm or less. On the other hand, from the viewpoint of obtaining a resin varnish having an appropriate viscosity and having good handleability when forming a resin varnish using the curable resin composition, and a viewpoint of preventing an increase in melt viscosity of the curable resin composition layer. For example, 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 size 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 measured on a volume basis by a laser diffraction / scattering type particle size distribution measuring apparatus, and the median diameter can be measured by setting the median diameter as the average particle diameter. As the measurement sample, a sample in which an inorganic filler is dispersed in water by ultrasonic waves can be preferably used. As a laser diffraction particle size distribution measuring device, “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 Mountech Co., Ltd.) or the like can be used. The true density of the inorganic filler can be measured by using a micro ultra pycnometer (MUPY-21T manufactured by Kantachrome Instruments Japan (the same)).

According to the present invention, the product of the specific surface area [m ² / g] of the inorganic filler and the true density [g / cm ³ ] is 6 or more, so that the curable resin composition can flow into the cavity well. By setting the product to 8 or less, the average coefficient of linear thermal expansion can be reduced. 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, 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, more preferably 7.5 or less.

  From the viewpoint of increasing the moisture resistance and dispersibility of the inorganic filler, aminosilane-based coupling agents, epoxysilane-based coupling agents, mercaptosilane-based coupling agents, silane-based coupling agents, organosilazane compounds, titanate-based coupling agents And the like, and is preferably treated with one or more 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), "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., Shin-Etsu Chemical Co., Ltd. "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd. "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. "KBM-4803" (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 preferred. On the other hand, from the viewpoint of preventing an increase in the melt viscosity at the melt viscosity or sheet form a resin varnish, preferably 1 mg / ^{m 2} or less, more preferably 0.8 mg / ^{m 2} or less, 0.5 mg / ^{m 2} or less is more preferable.

  The amount of carbon per unit surface area of the inorganic filler can be measured after the inorganic filler after the surface treatment 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 ultrasonic cleaning is performed at 25 ° C. for 5 minutes. After removing the supernatant and drying the solid content, the amount of carbon 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. or the like 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) at least one resin 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 which is liquid at 25 ° C. (component (d)).
In one preferred embodiment, the curable resin composition contains the component (d) together with the epoxy resin (a ′) having the aromatic structure (the component (a ′)). By containing a flexible resin such as the component (d), the cured product (insulating layer) of the curable resin composition layer is reduced in elastic modulus and thermal expansion coefficient, and is manufactured using the resin sheet of the present invention. It is possible to suppress the occurrence of warpage of the obtained wiring board.

  The glass transition temperature of the resin having a functional group having a glass transition temperature (Tg) of the component (d) of 25 ° C. or lower is preferably 20 ° C. or lower, more preferably 15 ° C. or lower. Although the lower limit of the glass transition temperature of the component (d) is not particularly limited, it can be usually -15 ° C or higher.

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

  The component (d) preferably has a functional group capable of reacting with the component (a) or (a '). In a preferred embodiment, the functional group of the component (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 them, 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 having 3 to 10 carbon atoms, more preferably having 5 to 6 carbon atoms), a butadiene structural unit, an isoprene structural unit, an isobutylene structural unit, a chloroprene structural unit, It preferably has at least one structural unit selected from a urethane structural unit, a polycarbonate structural unit, a (meth) acrylate structural unit, and a polysiloxane structural unit, and preferably includes a butadiene structural unit, a urethane structural unit, and a (meth) acrylate structural unit. It is more preferred to have one or more structural units selected. In addition, "(meth) acrylate" refers to methacrylate and acrylate.

  One preferred embodiment of 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 resin which is liquid at 25 ° C. include acid anhydride group-containing saturated and / or butadiene resin which is liquid at 25 ° C., and phenolic hydroxyl group-containing saturated and / or butadiene which is liquid at 25 ° C. A resin, a liquid epoxy group-containing saturated and / or butadiene resin at 25 ° C., a liquid isocyanate group-containing saturated and / or butadiene resin liquid at 25 ° C., and a urethane group-containing saturated and / or butadiene resin liquid at 25 ° C. One or more resins selected from Here, the term “saturated and / or unsaturated butadiene resin” refers to a resin containing a saturated butadiene skeleton and / or unsaturated butadiene skeleton. In these resins, the saturated butadiene skeleton and / or unsaturated butadiene skeleton has a main chain. Or in the side chain.

  The number average molecular weight (Mn) of the functional group-containing saturated and / or unsaturated butadiene resin liquid at 25 ° C. is preferably 500 to 50,000, more preferably 1,000 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 functional group-containing saturated and / or unsaturated butadiene resin which is liquid at 25 ° C. is preferably 100 to 10000, more preferably 200 to 5000. The functional group equivalent is the mass of a resin containing one equivalent of a functional group. For example, the epoxy equivalent of the resin can be measured according to JIS K7236.

  As the epoxy group-containing saturated and / or unsaturated butadiene resin liquid at 25 ° C., a saturated and / or butadiene skeleton-containing epoxy resin liquid at 25 ° C. is preferable, and a polybutadiene skeleton-containing epoxy resin liquid at 25 ° C. A liquid hydrogenated polybutadiene skeleton-containing epoxy resin is more preferable, and a liquid polybutadiene skeleton-containing epoxy resin liquid at 25 ° C. and a hydrogenated polybutadiene skeleton-containing epoxy resin liquid at 25 ° C. are even 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 does not necessarily need to be an epoxy resin in which the polybutadiene skeleton is completely hydrogenated. Specific examples of the polybutadiene skeleton-containing resin liquid at 25 ° C. and the hydrogenated polybutadiene skeleton-containing resin liquid at 25 ° C. include “PB3600” and “PB4700” (polybutadiene skeleton epoxy resin) manufactured by Daicel Corporation, and Nagase Chemtex. And "FCA-061L" (hydrogenated polybutadiene skeleton epoxy resin).

  As the acid anhydride group-containing saturated and / or unsaturated butadiene resin liquid at 25 ° C., a saturated and / or unsaturated butadiene skeleton-containing acid anhydride resin liquid at 25 ° C. is preferable. As the phenolic hydroxyl group-containing saturated and / or unsaturated butadiene resin liquid at 25 ° C., a saturated and / or unsaturated butadiene skeleton-containing phenol resin liquid at 25 ° C. is preferable. As the isocyanate group-containing saturated and / or unsaturated butadiene resin liquid at 25 ° C., a saturated and / or unsaturated butadiene skeleton-containing isocyanate resin liquid at 25 ° C. is preferable. As the urethane group-containing saturated and / or unsaturated butadiene resin which is liquid at 25 ° C., a saturated and / or unsaturated butadiene skeleton-containing urethane resin which 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. Examples of the functional group-containing acrylic resin having a Tg of 25 ° C. or less include an acid anhydride group-containing acrylic resin having a Tg of 25 ° C. or less, a phenolic hydroxyl group-containing acrylic resin having a Tg of 25 ° C. or less, and an isocyanate group containing a Tg of 25 ° C. or less. 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 less, and an epoxy group-containing acrylic resin having a Tg of 25 ° C. or less are preferable.

  The number average molecular weight (Mn) of the functional group-containing acrylic resin having a Tg of 25 ° C. or less is preferably 10,000 to 1,000,000, and more preferably 30,000 to 9,000,000. 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 1,000 to 50,000, more preferably 2,500 to 30,000.

  As the epoxy group-containing acrylic resin having a Tg of 25 ° C. or less, an epoxy group-containing acrylate copolymer resin having a Tg of 25 ° C. or less is preferable, and 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, Tg 11 ° C))," SG-P3 "(manufactured by Nagase ChemteX Corporation) Epoxy group-containing acrylate copolymer resin (number average molecular weight Mn: 850000 g / mol, epoxy value 0.21 eq / kg, Tg 12 ° C.).

  As the acid anhydride group-containing acrylic resin having a Tg of 25 ° C. or less, an acid anhydride group-containing acrylate copolymer resin having a Tg of 25 ° C. or less is preferable.

  As the phenolic hydroxyl group-containing acrylic resin having a Tg of 25 ° C. or less, a phenolic hydroxyl group-containing acrylate copolymer resin having a Tg of 25 ° C. or less is preferable. As a specific example thereof, Nagase ChemteX Corp. SG-790 "(epoxy group-containing acrylate copolymer resin (number average molecular weight Mn: 500,000 g / mol, hydroxyl value 40 mg KOH / kg, Tg-32 ° C)).

  A preferred embodiment of the component (d) is a polyimide resin having a butadiene structural unit, a urethane structural unit, and an imide structural unit in the molecule, and the polyimide resin preferably has a phenol structure at a molecular terminal. .

  The number average molecular weight (Mn) of the polyimide resin is preferably from 1,000 to 100,000, more preferably from 10,000 to 15,000. 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 acid value of the polyimide resin is preferably 1 KOH / g to 30 KOH / g, and more preferably 10 KOH / g to 20 KOH / g.

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

  For details of the polyimide resin, the description of International Publication WO 2008/153208 can be referred to, and the contents thereof 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, it is preferable that the component (d) is dispersed in the curable resin composition layer.

  The content of the component (d) in the curable resin composition is not particularly limited, but is preferably 14% by mass or less, more preferably 13% by mass or less, and further preferably 12% by mass or less. 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-
As the thermoplastic resin, for example, phenoxy resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyimide resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polycarbonate resin, polyether Thermoplastic resins such as an ether ketone resin and a polyester resin are exemplified, and among these, a phenoxy resin is preferable. The thermoplastic resins may be used alone or in combination of two or more.

  The weight average molecular weight of the thermoplastic resin in terms of polystyrene 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 weight average molecular weight of the thermoplastic resin in terms of polystyrene is determined by using 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 calibration curve of standard polystyrene by measuring 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, bisphenol acetophenone skeleton, novolak skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene Phenoxy resins having one or more skeletons selected from the group consisting of a skeleton and a trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group and an epoxy group. The phenoxy resins may be used alone or in combination of two or more. Specific examples of the phenoxy resin include “1256” and “4250” (both phenoloxy resins containing a bisphenol A skeleton), “YX8100” (phenoxy resin containing a bisphenol S skeleton), and “YX6954” (produced by Mitsubishi Chemical Corporation). Bisphenol acetophenone skeleton-containing phenoxy resin), as well as "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, “Electric Butyral 4000-2”, “Electric Butyral 5000-A”, “Electric Butyral 6000-C”, and “Electric Butyral 6000-EP” manufactured by Denki Kagaku Kogyo KK. , S-Lek BH series, BX series, KS series, BL series, BM series, etc., manufactured by Sekisui Chemical Co., Ltd.

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

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

  Specific examples of the polyether sulfone 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 them, a phenoxy resin and a polyvinyl acetal resin are preferable as the thermoplastic resin from the viewpoint of obtaining an insulating layer having a lower surface roughness and having better adhesion to the conductor layer in combination with other components. Therefore, in a preferred embodiment, the thermoplastic resin component includes at least one selected from the group consisting 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. 10 to 10% by mass, more preferably 0.6 to 8% by mass.

-Curing accelerator-
Examples of the curing accelerator include a phosphorus-based curing accelerator, an amine-based curing accelerator, an imidazole-based curing accelerator, a guanidine-based curing accelerator, and the like; a phosphorus-based curing accelerator, an amine-based curing accelerator, and an imidazole-based curing accelerator A curing accelerator is preferred, and an amine-based curing accelerator and an imidazole-based curing accelerator are more preferred. The curing accelerator may be used alone or in combination of two or more.

  Examples of the phosphorus-based curing accelerator include triphenylphosphine, a phosphonium borate compound, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, and (4-methylphenyl) triphenylphosphonium thiocyanate , Tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate and the like, and triphenylphosphine and tetrabutylphosphonium decanoate are preferred.

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

  Examples of the imidazole-based curing accelerator include, for example, 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 Imidazole compounds such as 3-benzylimidazolium chloride, 2-methylimidazoline and 2-phenylimidazoline, and adducts of imidazole compounds and epoxy resins; 2-ethyl-4-methylimidazole, 1-benzyl-2-phenyl Imidazole is preferred.

  As the imidazole-based curing accelerator, a commercially available product may be used, 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-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 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.

  The content of the curing accelerator in the curable resin composition is not particularly limited, but is preferably used in the range of 0.05% by mass to 3% by mass.

-Flame retardant-
The curable resin composition may include a flame retardant. Examples of the flame retardant include organic phosphorus-based flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, silicone-based flame retardants, metal hydroxides, and the like. The flame retardants may be used alone or in combination of two or more.

  As the flame retardant, commercially available products may be used, and examples thereof include "HCA-HQ" manufactured by Sanko Co., Ltd. and "PX-200" manufactured by Daihachi Chemical Industry Co., Ltd.

  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 still more preferably 1.5% by mass. 10% by mass is more preferred.

-Organic filler-
The curable resin composition may further include an organic filler. As the organic filler, any organic filler that can be used when forming the insulating layer of the printed wiring board may be used, and 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, for example, “EXL2655” manufactured by Dow Chemical Japan Co., Ltd., “AC3816N” manufactured by Aika Kogyo KK, and the like.

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

  The curable resin composition may further contain, if necessary, a flame retardant, and other additives other than the organic filler.As such other additives, for example, an organic copper compound, an organic zinc Examples include organic metal compounds such as compounds and organic cobalt compounds, and resin additives such as organic fillers, thickeners, defoamers, leveling agents, adhesion promoters, and colorants.

-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 include an amino resin that is liquid at normal 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. Liquid amino resins include alkylated melamine resins such as methylmelamine. The alkylated melamine resin is, for example, reacting melamine with formaldehyde to replace a part or all of the hydrogen atoms of the amino group with a methylol group, and then further reacting with an alcohol compound to convert a part or all of the methylol group with alkoxymethyl. It is 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 includes a support and a curable resin composition layer formed of the curable resin composition, wherein the minimum melt viscosity of the curable resin composition layer is 12000 poise or less. I do. Further, the average linear thermal expansion coefficient between 25 ° C. and 150 ° C. of the insulating layer (cured product) obtained by curing the curable resin composition layer is preferably 17 ppm / ° C. or less.

  FIG. 2 shows an example of the resin sheet of the present invention. 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 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, the plastic material may be, for example, polyethylene terephthalate (hereinafter sometimes abbreviated as “PET”) or polyethylene naphthalate (hereinafter sometimes abbreviated as “PEN”). .), Acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), and polyethers. Ketone, polyimide and the like can be mentioned. Among them, polyethylene terephthalate and polyethylene naphthalate are preferable, and inexpensive polyethylene terephthalate is particularly preferable.

  When a metal foil is used as the support, examples of the metal foil include a copper foil and an aluminum foil, and a 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.) may be used. May be used.

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

  Further, as the support, a support with a release layer having a release layer on the surface to be joined to the curable resin composition layer may be used. Examples of the release agent used in the release layer of the support having a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. . The support with a release layer may be a commercially available product, for example, a PET film having a release layer containing an alkyd resin-based release agent as a main component, "Lumirror T6AM" manufactured by Toray Industries, Inc. Examples include "SK-1", "AL-5", and "AL-7" manufactured by Lintec Corporation.

  The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm. When a support with a release layer is used, the thickness of the entire support with a release layer is preferably within the above 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 10000 poise or less, from the viewpoint of achieving good embedding of components inside the cavity when manufacturing a component-containing circuit board. Preferably it is 8000 poise or less. The lower limit of the minimum melt viscosity of the curable resin composition layer is not particularly limited, and may be generally 500 poise or more, 1000 poise or more.

  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. In detail, when the curable resin composition layer is heated at a constant heating rate to melt the resin, the melt viscosity decreases with the temperature rise in the initial stage, and then melts with the temperature rise when the temperature exceeds a certain temperature. The 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 viscoelasticity 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 heating rate of 5 ° C./min, a frequency of 1 Hz, and a strain of 1 deg. be able to. As the dynamic viscoelasticity measuring device, for example, "Rheosol-G3000" manufactured by UBM Co., Ltd. may be mentioned.

  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 lower, preferably 16 ppm / ° C. or lower, more preferably 15 ppm / ° C. or lower. Although the lower limit of the average linear thermal expansion coefficient is not particularly limited, it can be usually 1 ppm / ° C. or more, 2 ppm / ° C. or more, 3 ppm / ° C. or more. The average coefficient of linear thermal expansion can be measured by a known method such as thermomechanical analysis. As the thermomechanical analyzer, for example, "Thermo Plus TMA8310" manufactured by Rigaku Corporation can be mentioned. In the present invention, the average coefficient of linear thermal expansion of the insulating layer is the average coefficient of linear thermal expansion in the plane direction at 25 to 150 ° C. when thermomechanical analysis is performed by a tensile load method.

  In the present invention, the thickness of the curable resin composition layer made of the curable resin composition is preferably 300 μm or less, 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 to the conductor layer after the roughening treatment, and from the viewpoint of ease of production of the resin sheet. Above, it can 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 bonded to the support 11 (that is, the surface opposite to the support). The protective film contributes to the attachment of dust and the like to the surface of the curable resin composition layer 12 and the prevention of scratches. As the material of the protective film, the same material as described for the support 11 may be used. Although the thickness of the protective film is not particularly limited, it is, for example, 1 μm to 40 μm. When manufacturing the printed wiring board, the resin sheet 10 can be used by peeling off the protective film.

  ADVANTAGE OF THE INVENTION The resin sheet of this invention can implement | achieve the favorable embedding | flush-mounting property of the component inside a cavity at the time of manufacture of a component built-in circuit board, and can implement | achieve the component built-in circuit board which suppressed the problem of the curvature. Therefore, the resin sheet of the present invention can be particularly preferably used for embedding components inside a cavity (for embedding a cavity) when manufacturing a circuit board with a built-in component, and is also suitable for use in mold underfill (sealing). 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, it can be used to form an insulating layer in the manufacture of a printed wiring board by a build-up method. It can be suitably used for forming a conductor layer by plating (for a build-up insulating layer of a printed wiring board in which a conductor layer is formed by plating).

<Production method of resin sheet>
Hereinafter, an example of the method for producing the resin sheet of the present invention will be described. A curable resin composition layer composed of a curable resin composition is formed on a support.

  As a method of forming the curable resin composition layer, for example, there is a method of applying the curable resin composition to a support, drying the applied film, and providing the curable resin composition layer.

  In this method, the curable resin composition layer prepares a resin varnish obtained by dissolving the curable resin composition in an organic solvent, and coats 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. , Aromatic hydrocarbons such as toluene and xylene, and amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone. One organic solvent may be used alone, or two or more organic solvents may be used in combination.

  Drying of the resin varnish may be performed by a known drying method such as heating or blowing hot air. 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 an organic solvent is used, the support is dried at 50 ° C. to 150 ° C. for 3 minutes to 10 minutes. A curable resin composition layer can be formed thereon.

  In the present invention, for example, a resin sheet may be prepared by forming a curable resin composition layer on a protective film and then laminating a support on the curable resin composition layer.

<Wiring board>
The wiring board of the present invention includes an insulating layer obtained by curing the curable resin composition layer of the resin sheet of the present 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 a first and a second main surface, and a cavity formed through the first and the second main surface; and a second circuit board of the circuit board. The resin sheet of the present invention is applied to a circuit board to which components are temporarily attached, including a temporary attachment material joined to the main surface and a component temporarily attached by the temporary attachment material inside the cavity of the circuit board. A first laminating step of vacuum lamination such that the curable resin composition layer is bonded to the first main surface of the circuit board; and (B) a heat treatment step of heat-treating the circuit board on which the resin sheet is laminated. And (C) removing the temporary bonding material from the second main surface of the circuit board, and then bonding the second resin sheet so that the curable resin composition layer is bonded to the second main surface of the circuit board. A second laminating step of vacuum laminating, and (D) a curable resin composition layer of the resin sheet. 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 to 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 to which components are temporarily attached (hereinafter, also referred to as a “component temporary attachment circuit board” or a “cavity board”) has first and second main surfaces, and the first and second main surfaces. A circuit board having a cavity formed therethrough, a temporary material joined to a second main surface of the circuit board, and a component temporarily attached by the temporary material inside the cavity of the circuit board And

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

  First, a circuit board is prepared (FIG. 1A). “Circuit board” refers to a plate-like substrate having opposing first and second main surfaces and having circuit wiring patterned on one or both of the first and second main surfaces. FIG. 1A schematically shows an end face of the circuit board 1, and the circuit board 1 includes a board 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 refers to the upper main surface of the illustrated circuit board, and the second main surface of the circuit board refers to the lower side of the illustrated circuit board. It represents the main surface.

  Examples of the substrate 2 used for the circuit substrate 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. When manufacturing a printed wiring board, an inner circuit board of an intermediate product on which an insulating layer and / or a conductor layer is to be further 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 still more preferably 250 μm. The thickness is particularly preferably 200 μm or less, 180 μm or less, 170 μm or less, 160 μm or less, or 150 μm or less. The lower limit of the thickness of the substrate 2 is not particularly limited, but is preferably 50 μm or more, more preferably 80 μm or more, and still more preferably 100 μm or more, from the viewpoint of improving the handling during transport.

  The dimensions of the circuit wiring 3 included in 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, still more preferably 30 μm or less, still more preferably 25 μm or less, particularly preferably 20 μm or less, and 19 μm, from the viewpoint of reducing the thickness of the component built-in circuit board. Or less, or 18 μm or less. Although the lower limit of the thickness of the surface wiring is not particularly limited, it is usually 1 μm or more, 3 μm or more, 5 μm or more.

  Next, a cavity (recess) for accommodating components is provided on the circuit board (FIG. 1B). As schematically shown in FIG. 1B, a cavity 2a penetrating 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, laser, plasma, an etching medium, or the like in consideration of the characteristics of the substrate 2.

  Although FIG. 1B shows only one cavity 2a, 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, still more preferably 8 mm or less, still 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, etc., depending on the opening size of the cavity 2a itself. Each pitch between the cavities 2a does not need to be the same over the circuit board, but 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, and a substantially circle. Although the opening size 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 more preferably 2 mm × 2 mm or less. . The lower limit of the opening size is usually 0.5 mm × 0.5 mm or more, though it depends on the size of the component to be housed. The opening shape and the opening size of the cavity 2a need not be the same over the circuit board but may be different.

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

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

  Next, the component is temporarily attached to the adhesive surface of the temporary attachment material exposed through the cavity (FIG. 1D). In the mode schematically shown in FIG. 1D, the component 5 is temporarily attached to the adhesive surface of the temporary attaching 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 passive components such as capacitors, inductors and resistors, and active components such as semiconductor bare chips. The same part 5 may be used for all cavities, or a different part 5 may be used for each cavity.

  When manufacturing the component temporary-attached circuit board, in addition to the above-described method, for example, the circuit wiring 3 may be provided after the cavity 2a is formed in the substrate 2, or the temporary-attaching material 4 may be provided on the second circuit board. After lamination on the main surface, the cavity 2a may be formed.

  A method for manufacturing a component built-in circuit board using the resin sheet of the present invention will be described. In the following description, the resin sheet of the present invention laminated on the first main surface and the second main surface of the component built-in circuit board will be referred to as a “first resin sheet 10” and a “second resin sheet 20”, respectively. ". The first resin sheet 10 and the second resin sheet 20 may be the same or different. 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 between the first resin sheet 10 and the second resin sheet 20. .

<(A) First lamination step (lamination of first resin sheet)>
First, the resin sheet (first resin sheet 10) of the present invention is laminated on a circuit board to 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 such that the curable resin composition layer 12 is bonded to the first main surface of the circuit board (FIG. 3A). See). Here, when the first resin sheet 10 has a configuration including a protective film that covers the curable resin composition layer 12, the protective film is peeled off and then laminated on the circuit board.

  The vacuum lamination of the first resin sheet 10 on the component temporary-attached circuit board 1 ′ is performed, for example, by heat-pressing the first resin sheet 10 to the component temporary-attached circuit board 1 ′ from the support 11 side under reduced pressure. It can be done by doing. Examples of a member (not shown; hereinafter, also referred to as a “heat-compression member”) that heat-presses the first resin sheet 10 to the component temporary-attached circuit board 1 ′ include, for example, a heated metal plate (such as a SUS mirror plate). Alternatively, a metal roll (SUS roll) or the like may be used. Note that the first resin sheet 10 does not directly press the thermocompression bonding member on the first resin sheet 10 but sufficiently follows irregularities caused by the circuit wiring 3 and the cavity 2a of the component temporary-attached circuit board 1 '. As described above, 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. It is in the range of 47 MPa, and the heating and pressing time is preferably in the range of 20 seconds to 400 seconds, and 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 by a commercially available vacuum laminator. Examples of commercially available vacuum laminators include a vacuum pressurized laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nichigo Morton Co., Ltd., and a two-stage build-up laminator manufactured by Nichigo Morton Co., Ltd.

  After the first laminating step, a smoothing process of the laminated first resin sheet 10 is performed under normal pressure (under atmospheric pressure), for example, by pressing a thermocompression bonding member from the first support 11 side. Preferably, a smoothing step is performed. The pressing conditions in the smoothing step can be the same as the heating and pressing conditions for the vacuum lamination.

  The smoothing step can be performed by a commercially available laminator. The first laminating step and the smoothing step may be continuously performed using the above-mentioned commercially available vacuum laminator.

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

<(B) Heat treatment step>
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, still more preferably 145 ° C. or lower, and even 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, further preferably 120 ° C. or higher, and still 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 may be generally 60 minutes or less.

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

  The heat treatment of the curable resin composition layer 12 in the heat treatment step may be performed in a state where the first support 11 is attached to the curable resin composition layer 12, and the first support 11 is peeled off. It may be carried out after exposing the curable resin composition layer 12. In a preferred embodiment, the heat treatment of the curable resin composition layer 12 is performed in a state where the first support 11 is attached to the first curable resin composition layer 12. This is advantageous in terms of preventing foreign matter from adhering 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 in a state where the first support 11 is attached, the first support 11 cures the curable resin composition layer 12. What is necessary is just to peel off before the process of providing a conductor layer (circuit wiring) on the obtained insulating layer (hardened | cured material), for example, even if it peels between a 1st heat processing process and the 2nd lamination process mentioned later. It may be peeled off between the second laminating step and the thermosetting step (described later) or may be peeled off after the thermosetting step. In a preferred embodiment, the first support 11 is peeled off after the thermosetting step. When a metal foil such as a copper foil is used as the first support 11, a conductive layer (circuit wiring) can be provided using the metal foil as described later. The support 11 need not be peeled off.

  In a preferred embodiment, a process of cooling the circuit board to room temperature (room temperature) may be performed between the first laminating 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 a heat treatment step (see FIG. 3C). Note that FIG. 3C shows an embodiment in which a heat treatment is performed with the first support 11 attached to obtain a curable resin composition layer (heat-treated body) 12 ′.

<(C) Second lamination step (lamination of second resin sheet)>
After the heat treatment step, the temporary attaching 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 figure) 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. . It is preferable to use the resin sheet of the present invention as the second resin sheet. The configurations of the second support and the second curable resin composition layer are the same as the above-described support and the curable resin composition layer of the resin sheet of the present invention. 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 including a plurality of curable resin composition layers having different compositions, or a desired minimum in the present invention) A material 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 temporary attaching material 4 may be performed according to a conventionally known method according to the type of the temporary attaching 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 temporary bonding material 4, the temporary bonding material 4 can be peeled off after the temporary bonding material 4 is irradiated with UV. The conditions such as the amount of UV irradiation may be publicly known conditions usually employed in the production of a circuit board with a built-in component.

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

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

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

  In the second laminating step, the second curable resin composition layer 22 and the second support 21 are laminated 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 It may be separated between the step and a curing step described later, or may be separated after the curing step. In a preferred embodiment, the second support 21 is peeled off after the curing step. When a metal foil such as a copper foil is used as the second support 21, a conductor layer (circuit wiring) can be provided using the metal foil as described later. The support 21 need not be peeled off.

<(D) Curing process>
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. As a result, the curable resin composition layer (heat-treated body) 12 ′ forms an insulating layer 12 ″ (cured product) on the first main surface of the circuit board 2, and the second main surface of the circuit board 2 Then, the second curable resin composition layer 22 forms the insulating layer 22 ″ (cured product) (see FIG. 3F).

  The conditions for the 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. The temperature ranges from 120C to 240C (preferably from 150C to 210C, more preferably from 170C to 190C), 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).

  Before thermosetting, the curable resin composition layer 12 and the second curable resin composition layers 12, 22 may be preheated at a temperature lower than the curing temperature. For example, prior to thermal curing, the curable resin composition layers 12, 22 are heated at a temperature of 50 ° C. or more and less than 120 ° C. (preferably 60 ° C. or more and 110 ° C. or less, more preferably 70 ° C. or more and 100 ° C. or less) 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 thermal curing 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 laminating step and the curing step.

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

  As described above, the embodiment using the temporary attachment material has been described in detail. However, instead of the temporary attachment material, a circuit board with a built-in component may be manufactured using a resin sheet. The resin sheet that can be used in place of the temporary attaching material may be the same as the second resin sheet described above, and may be the resin sheet of the present invention or another resin sheet. When a resin sheet is used instead of the temporary bonding material, the step of removing the temporary bonding material is unnecessary.

<Other steps>
When manufacturing a component built-in circuit board, a step of drilling an insulating layer (drilling step), a step of roughening the surface of the insulating layer (roughening step), and a step of forming a conductor layer on the roughened insulating layer surface (Conductor layer forming step). These steps may be performed according to various methods known to those skilled in the art used for manufacturing a circuit board with a built-in component. When the supports 11 and 21 of the resin sheets 10 and 20 are peeled after the curing step, the supports 11 and 21 are peeled between the curing step and the drilling step and between the drilling step and the roughening step. Alternatively, it may be performed between the roughening step and the conductor layer forming step.

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

  The roughening step is a step of performing a roughening treatment on the insulating layers 12 ″ and 22 ″. The procedure and conditions of the roughening treatment are not particularly limited, and well-known procedures and conditions generally used when forming the insulating layers 12 "and 22" of the component built-in circuit board can be adopted. For example, in the roughening treatment of the insulating layers 12 "and 22", a swelling treatment with a swelling liquid, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing liquid are performed in this order to roughen the insulating layers 12 "and 22". Can be processed. The swelling solution is not particularly limited, but includes an alkali solution, a surfactant solution, and the like, and is preferably an alkali solution. As the alkali 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 KK. The swelling treatment with the swelling liquid is not particularly limited, but can be performed, for example, by immersing the insulating layers 12 ″ and 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 the swelling liquid at 40 to 80C for 5 seconds to 15 minutes. Although it does not specifically limit as an oxidizing agent, For example, alkaline permanganate solution which melt | dissolved potassium permanganate and sodium permanganate in aqueous solution of sodium hydroxide is mentioned. The roughening treatment using an oxidizing agent such as an alkaline permanganate solution is preferably performed by immersing the first and second insulating layers in an oxidizing agent solution heated to 60 ° C. to 80 ° C. for 10 minutes to 30 minutes. The concentration of the permanganate in the alkaline permanganate solution is preferably from 5% by mass to 10% by mass. Commercially available oxidizing agents include, for example, alkaline permanganate solutions such as Concentrate P and Dosing Solution Securigans P manufactured by Atotech Japan KK. As the neutralizing solution, an acidic aqueous solution is preferable, and as a commercially available product, for example, Reduction Shoulicin Securiganto P manufactured by Atotech Japan KK can be mentioned. The treatment with the neutralizing solution can be performed by immersing the treated surface subjected to the roughening treatment with the oxidizing agent 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 in which the object subjected to the roughening treatment with the oxidizing agent solution is immersed 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 conductive 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. Including 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 Nickel alloy and copper-titanium alloy). Among them, from the viewpoints of versatility of conductor layer formation, cost, ease of patterning, etc., a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or a nickel-chromium alloy, copper A nickel alloy or an alloy layer of copper-titanium alloy is preferable, 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. Metal layers are 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 stacked. 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 a nickel-chromium alloy.

  The thickness of the conductive layer depends on the design of the desired component-containing 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, a conductor layer (circuit wiring) having a desired pattern can be formed by plating the surfaces of the first and second insulating layers by a conventionally known technique such as a semi-additive method or a full-additive method. Hereinafter, an example in which a 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 for exposing a part of the plating seed layer corresponding to a desired wiring pattern is formed on the formed plating seed layer. After a metal layer is formed on the exposed plating seed layer by electrolytic plating, the mask pattern is removed. Thereafter, the unnecessary plating seed layer is removed by etching or the like, so that a conductor layer having a desired pattern can be formed.

  Through these steps, a conductor (via wiring) is also formed in the via hole, and the circuit wiring 3 provided on the surface of the insulating layers 12 ″ and 22 ″ is electrically connected to the circuit wiring of the circuit board. 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 conductor layer may be formed by electrolytic plating using a metal foil as a plating seed layer.

  The method of manufacturing a component-embedded circuit board may also include a step of singulating the component-embedded circuit board.

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

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

  Examples of such a semiconductor device include various semiconductor devices provided for electric appliances (for example, computers, mobile phones, digital cameras, televisions, and the like) and vehicles (for example, motorcycles, automobiles, trains, ships, and aircrafts). .

  Hereinafter, the present invention will be described specifically 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.

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

(Preparation of inorganic filler)
Examples of the silicas 1 to 6 include "Adma Fine" 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. After performing surface treatment using “Sciqas Series” manufactured by Nippon Shokubai Co., Ltd. and “Sea Hostar Series” manufactured by Nippon Shokubai Co., Ltd., the particle size distribution and the specific surface area were measured by the following methods. Examples and Comparative Examples Used for
After performing surface treatment using "AZ series" and "AX series" manufactured by Nippon Steel & Sumitomo Metal Materials Co., Ltd., the particle size distribution and specific surface area were measured by the following method and used for Example 4. did.

(1) Measurement of Average Particle Size 100 mg of silica 1 to 6 powder 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 into a vial and ultrasonically measured. Dispersed for 20 minutes. The particle size distribution was measured by a batch cell method using a laser diffraction type particle size distribution analyzer (SALD-2200 manufactured by Shimadzu Corporation), and the average particle size was calculated.

(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 Mountech Co., Ltd.), and shown in Table 2.

(3) Measurement of True Density The true densities of silicas 1 to 6 and alumina were measured by a micro ultra pycnometer (MUPY-21T manufactured by Kantachrome Instruments Japan (the same company)) and shown in Table 2.

(Preparation of resin varnish 1)
4 parts of bisphenol type liquid epoxy resin (“ZX1059” manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd., epoxy equivalent about 169, 1: 1 mixture of bisphenol A type and bisphenol F type), naphthylene ether type epoxy resin (DIC Corporation) 10 parts of “EXA-7311-G4”, epoxy equivalent about 213), 6 parts of bixylenol type epoxy resin (“YX4000HK” manufactured by Mitsubishi Chemical Corporation, epoxy equivalent of about 185), 6 parts, biphenyl type epoxy resin (Nippon Kayaku ( (NC3000L), 10 parts of epoxy equivalent about 272) and 4 parts of a flame retardant (“PX-200” manufactured by Daihachi Chemical Industry Co., Ltd.) were stirred in a mixed solvent of 20 parts of solvent naphtha and 10 parts of cyclohexanone. While heating. After cooling to room temperature, 10 parts of a triazine skeleton-containing cresol novolak-based curing agent ("LA3018-50P" manufactured by DIC Corporation, a hydroxyl group equivalent of about 151, a 2-methoxypropanol solution having a solid content of 50%), and triazine 4 parts of skeleton-containing phenol novolak-based curing agent (“LA-7054” manufactured by DIC Corporation, MEK solution having a hydroxyl equivalent of about 125 and a solid content of 60%), and naphthol-based curing agent (“SN-” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) 495V ", 10 parts of MEK solution having a hydroxyl equivalent of about 231 and a solid content of 60%, 1 part of an amine-based curing accelerator (4-dimethylaminopyridine (DMAP), a MEK solution having a solid content of 5% by mass), and aminosilane-based 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 a glycidylamine type liquid epoxy resin (“630LSD” manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: about 95), 6 parts of a bixylenol type epoxy resin (“YX4000HK” manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: about 185), bisphenol 6 parts of AF type epoxy resin (“YL7760” manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: about 238), 15 parts of naphthalene type epoxy resin (“ESN475V” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent: about 330), and phenoxy resin 8 parts of “YX7553BH30” (manufactured by Mitsubishi Chemical Corporation, 1: 1 solution of cyclohexanone: methylethylketone (MEK) having a solid content of 30% by mass) is heated and dissolved in a mixed solvent of 20 parts of solvent naphtha and 5 parts of cyclohexanone with stirring. I let it. After cooling to room temperature, 12 parts of a triazine skeleton-containing cresol novolak-based curing agent (“LA3018-50P” manufactured by DIC Corporation, 2-methoxypropanol solution having a hydroxyl equivalent of about 151 and a solid content of 50%) were added thereto, 12 parts of an ester-based curing agent ("EXB-8000L-65M" manufactured by DIC Corporation, an active group equivalent of about 220, a MEK solution of a nonvolatile component of 65% by mass), and an amine-based curing accelerator (4-dimethylaminopyridine (DMAP)) , 5 parts by mass of MEK solution), 1 part of a flame retardant (“HCA-HQ” manufactured by Sanko Co., Ltd., 10- (2,5-dihydroxyphenyl) -10-hydro-9-oxa-10-phospha) 2 parts of phenanthrene-10-oxide, average particle size 2 μm, 2 parts of rubber particles (EXL2655, manufactured by Dow Chemical Japan Co., Ltd.), phenyltrimethoate 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 uniformly dispersed by a high-speed rotation mixer, and then filtered through a cartridge filter (“SHP050” manufactured by ROKITECHNO) to prepare a resin varnish 2.

(Preparation of resin varnish 3)
8 parts of bisphenol type liquid epoxy resin (“ZX1059” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent about 169, 1: 1 mixture of bisphenol A type and bisphenol F type), 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”, epoxy equivalent of about 170) manufactured by DIC, and biphenyl type epoxy resin (“NC3000L” manufactured by Nippon Kayaku Co., Ltd.) , Epoxy equivalent of about 272) and 12 parts of phenoxy resin ("YX7553BH30" manufactured by Mitsubishi Chemical Corporation, a 1: 1 solution of cyclohexanone: methyl ethyl ketone (MEK) having a solid content of 30% by mass) in 20 parts of solvent naphtha. And a mixed solvent of 5 parts of cyclohexanone with heating while stirring. After cooling to room temperature, 8 parts of a triazine skeleton-containing phenol novolak-based curing agent ("LA-7054" manufactured by DIC Corporation, an MEK solution having a hydroxyl equivalent of about 125 and a solid content of 60%), and a naphthol-based curing agent (“NS-485” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., MEK solution having a hydroxyl equivalent of about 212 and a solid content of 60%) 12 parts, imidazole-based hardening accelerator (“1B2PZ” 1-benzyl-manufactured by Shikoku Chemicals Co., Ltd.) 1 part of 2-phenylimidazole, 5% solids MEK solution), a flame retardant (“HCA-HQ” manufactured by Sanko Co., Ltd.), 10- (2,5-dihydroxyphenyl) -10-hydro-9-oxa-10 4 parts of phosphaphenanthrene-10-oxide, average particle diameter of 2 μm, and 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 mixture was filtered through a filter (“SHP050” manufactured by ROKITECHNO) to prepare a resin varnish 3.

(Preparation of resin varnish 4)
50 parts of component (d) produced as described below, bisphenol 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 (“YL7760” manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: about 238), 2 parts, and a flame retardant (“HCA-HQ” manufactured by Sanko Co., Ltd.), 10- (2,5-dihydroxyphenyl) 2))-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, average particle size 2 μm) was heated and dissolved in a mixed solvent of 15 parts of solvent naphtha and 5 parts of cyclohexanone with stirring. . There, 2 parts of an active ester-based curing agent ("EXB-8000L-65M" manufactured by DIC Corporation, an active group equivalent of about 220, a MEK solution of a nonvolatile component of 65% by mass), an imidazole-based curing accelerator (Shikoku Chemical Industry Co., Ltd.) Surface treatment with 1 part of "1B2PZ" 1-benzyl-2-phenylimidazole (manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573") (1 part) and a phenylaminosilane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.). 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 ) were mixed and uniformly dispersed by a high-speed rotating mixer. The mixture was filtered through a cartridge filter (“SHP050” manufactured by ROKITECHNO) to prepare a resin varnish 4.

[Production of (d) component]
50 g of G-3000 (bifunctional hydroxyl group-terminated polybutadiene, number average molecular weight = 5047 (GPC method), hydroxyl equivalent weight = 1798 g / eq., Solid content 100% by mass: manufactured by 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 uniformly dissolved. When it became uniform, the temperature was raised to 50 ° C., and 4.8 g of toluene-2,4-diisocyanate (isocyanate group equivalent = 87.08 g / eq.) Was added with stirring, and the reaction was carried out for about 3 hours. Next, the reaction product was cooled to room temperature, and 8.96 g of benzophenonetetracarboxylic dianhydride (anhydride equivalent = 161.1 g / eq.), 0.07 g of triethylenediamine, and ethyldiglycol were added thereto. 40.4 g of acetate (manufactured by Daicel Co., Ltd.) 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. The end point of the reaction was considered upon confirmation of disappearance of the NCO peak, 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 of polybutadiene structure: 50 / (50 + 4.8 + 8.96) × 100 = 78.4% by mass

(Preparation of resin varnish 5)
In place of 1,220 parts of silica of 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 ) was used. A resin varnish 5 was prepared in the same manner as the resin varnish 1, except that a cartridge filter (“SHP100” manufactured by ROKITECHNO) was used.

(Preparation of resin varnish 6)
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 ) is used instead of silica ^{2 and} 190 parts of resin varnish 2 Except for the above, a resin varnish 6 was prepared in the same manner as the resin varnish 2.

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

(Preparation of resin varnish 8)
10 parts of naphthalene type epoxy resin (“ESN475V” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent about 330), 5 parts of naphthalene type epoxy resin (“HP-4710” manufactured by DIC Corporation, epoxy equivalent about 170), biphenyl type 12 parts of an epoxy resin ("NC3000L" manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: about 272), and 1 part of phenoxy resin ("YX7553BH30" manufactured by Mitsubishi Chemical Corporation), cyclohexanone: methyl ethyl ketone (MEK) having a solid content of 30% by mass. : 1 solution) was heated and dissolved in a mixed solvent of 20 parts of solvent naphtha and 10 parts of cyclohexanone while stirring. After cooling to room temperature, 8 parts of a triazine skeleton-containing phenol novolak-based curing agent ("LA-7054" manufactured by DIC Corporation, an MEK solution having a hydroxyl equivalent of about 125 and a solid content of 60%), and a naphthol-based curing agent (“NS-485” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., MEK solution having a hydroxyl equivalent of about 212 and a solid content of 60%) 12 parts, imidazole-based hardening accelerator (“1B2PZ” 1-benzyl-manufactured by Shikoku Chemicals Co., Ltd.) 1 part of 2-phenylimidazole, 5% solids MEK solution), a flame retardant (“HCA-HQ” manufactured by Sanko Co., Ltd.), 10- (2,5-dihydroxyphenyl) -10-hydro-9-oxa-10 4 parts of phosphaphenanthrene-10-oxide, average particle diameter of 2 μm, and 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 mixture was filtered through a filter (“SHP050” manufactured by ROKITECHNO) to prepare a resin varnish 8.

  Table 1 shows the materials used for preparing each resin varnish and the amounts (parts by mass of non-volatile components) thereof. With respect to (a1) the liquid epoxy resin and (c) the inorganic filler, the contents (% by mass) in the nonvolatile components are also shown in Table 1.

(Examples 1-4 and Comparative Examples 1-4: Preparation of resin sheet)
As a support, a PET film (“Lumirror T6AM” manufactured by Toray Industries, Inc.) that has been release-treated with an alkyd resin-based release agent (“AL-5” manufactured by Lintec Corporation), a thickness of 38 μm, a softening point of 130 ° C., and “release” PET ") was prepared.
Each resin varnish was uniformly coated on a release PET by a die coater so that the thickness of the curable resin composition layer after drying became 25 μm, and dried at 80 ° C. to 110 ° C. for 4 minutes to release. A curable resin composition layer was obtained on the mold PET. Then, a polypropylene film ("Alphan MA-430" manufactured by Oji Ftex Co., Ltd., thickness: 20 m) is provided 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 joined. Thus, a resin sheet comprising a support, a curable resin composition layer, and a protective film in this order was obtained.

(Measurement of minimum melt viscosity of curable resin composition layer)
(1) Measurement of Minimum Melt Viscosity Only the curable resin composition layer was peeled from the release PET, and compressed with a mold to produce a measurement pellet (diameter: 18 mm, 1.2 to 1.3 g).
Using a pellet for measurement, using a dynamic viscoelasticity measurement device (“Rheosol-G3000” manufactured by UBM), 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 heating rate of 5 ° C./min. The melt viscosity (poise) was calculated and is 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 (“51010” manufactured by Lintec Co., Ltd., thickness 38 μm, 240 mm square) is a glass cloth base epoxy resin double-sided copper-clad laminate (“R5715ES” manufactured by Matsushita Electric Works, Ltd .; 7 mm, 255 mm square) on a glass cloth base epoxy resin double-sided copper-clad laminate, and four sides of the release PET film were fixed with polyimide adhesive tape (10 mm width).

  The curable resin composition layer was separated from each of the resin sheets (200 mm square) produced in Examples and Comparative Examples using a batch-type vacuum pressure laminator (Nichigo Morton's two-stage build-up laminator CVP700). Lamination processing was performed at the center so as to be in contact with the release surface of the mold PET film. The lamination process was performed by reducing the pressure to 13 hPa or less by reducing the pressure for 30 seconds, and then performing pressure bonding at 100 ° C. and a pressure of 0.74 MPa for 30 seconds.

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

  After the heat curing, 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 Co., Ltd.) on which the curable resin composition layer was laminated was peeled off to obtain a sheet-shaped 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 subjected to thermomechanical analysis by a tensile load method using a thermomechanical analyzer (“Thermo Plus TMA8310” manufactured by Rigaku Corporation). Was. Specifically, after the test piece was mounted on the thermomechanical analyzer, the measurement was continuously performed twice at a load of 1 g and at a heating rate of 5 ° C./min. Then, in two measurements, 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 Embedding Property Using the resin sheets prepared in Examples and Comparative Examples, a component temporary-attached circuit board was prepared according to the following procedure, and the component embedding property was evaluated.

(1) Preparation of a circuit board (cavity substrate) for temporarily attaching components A glass-clad base material BT resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.15 mm, “HL832NSF LCA” manufactured by Mitsubishi Gas Chemical Co., Ltd.) A cavity and a conductor pattern of 0.7 × 1.1 mm were formed on the entire surface of the size of 255 * 340 mm according to the design of the attached document. Next, the both surfaces were etched with a microetching agent (“CZ8100” manufactured by MEC Corporation) at 1 μm to roughen the copper surface, and then subjected to a rust prevention treatment (“CL8300” manufactured by MEC Corporation). Dry at 30 ° C. for 30 minutes.

(2) Fabrication of a component temporary-attached circuit board A 25-μm-thick polyimide film with adhesive (38 μm-thick polyimide, “PFDKE-1525TT” manufactured by Arisawa Seisakusho Co., Ltd.) is batched on one side of the board obtained in (1). The adhesive was arranged so as to be bonded to the substrate using a vacuum vacuum laminator (Nichigo Morton's two-stage build-up laminator “CVP700”) and laminated on one side. The lamination was performed by reducing the pressure to 13 hPa or less by reducing the pressure for 30 seconds, and then performing pressure bonding at 80 ° C. and a pressure of 0.74 MPa for 30 seconds. Next, a multilayer ceramic capacitor component (1005 = 1 * 0.5 mm size, thickness 0.14 mm) was temporarily attached to the cavity one by one to produce a component temporary attachment circuit board (cavity substrate).

(3) Evaluation test of component embedding property Using a batch-type vacuum pressurizing laminator (Nichigo Morton's two-stage build-up laminator “CVP700”), a protective film was formed from the resin sheets prepared in Examples and Comparative Examples. The curable resin composition layer that has been peeled off and exposed is bonded to the surface of the component temporary-attached circuit board (cavity substrate) prepared in (2) opposite to the surface on which the polyimide film with the adhesive is disposed. Laminated. The lamination was performed by reducing the pressure to 13 hPa or less by reducing the pressure for 30 seconds, and then performing pressure bonding at 120 ° C. and a pressure of 0.74 MPa for 30 seconds. Next, the laminated resin sheet was smoothed by hot pressing under atmospheric pressure at 120 ° C. and a pressure of 0.5 MPa for 60 seconds. An evaluation substrate A was prepared by peeling the polyimide film with the adhesive from the component temporary-attached circuit board cooled to room temperature. From the surface of the evaluation substrate A from which the polyimide film was peeled off, the resin flow in the cavity was observed with an optical microscope (magnification: 150) (10 cavities), and the component embedding property was evaluated according to the following criteria. The results are shown in Table 2. .
：: In all cavities, the outer peripheral portion of the multilayer ceramic capacitor component is covered with resin.
X: Even in one of the cavities, there is one in which voids are generated or resin is not embedded in the outer peripheral portion of the multilayer ceramic capacitor component.
Was determined.

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

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

In Table 2, along with the evaluation results, the types of the resin varnish used for forming each curable resin composition layer, the types of the inorganic filler, the content (% by mass), and the average in the resin sheets of Examples and Comparative Examples Particle diameter (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 coefficient of linear thermal expansion (ppm / ° C.) is also shown.

DESCRIPTION OF SYMBOLS 1 ... Circuit board 2 ... Substrate 2a ... Cavity 3 ... Conductor layer (circuit wiring)
4. Temporary material 5. Part 10. Resin sheet (first resin sheet)
11 Support (first support)
12: Curable resin composition layer 12 ': Curable resin composition layer (heat-treated body)
Reference numeral 12 '': an insulating layer 20: a second resin sheet 21: a second support 22: a second curable resin composition layer 22 ': a second curable resin composition layer (heat-treated body)
22 "... insulating layer 100 ... wiring board (component built-in circuit board)

Claims (11)

A resin sheet comprising a support and a curable resin composition layer provided on the support,
The curable resin composition layer contains 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] of the inorganic filler and the true density [g / cm ³ ] is 6 to 8,
A resin sheet in which the curable resin composition layer has a minimum melt viscosity of 12000 poise or less. The resin sheet according to claim 1, wherein the average particle size of the inorganic filler is 1.52 µm or less. Resin sheet according to claim 1 or 2 inorganic filler is silica. The curable resin composition layer contains (a) an epoxy resin,
The epoxy resin comprises a liquid epoxy resin,
The resin sheet according to any one of claims 1 to 3, 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 comprises a solid epoxy resin,
The ratio of the mass _{M S} of solid epoxy resin to the weight _{M L} of the liquid epoxy resin of the curable resin composition layer _(M S / _{M L)} is a resin sheet of claim 4 wherein 0.6 to 10 . (A) an epoxy resin, an epoxy resin having (a ') aromatic structure, the resin sheet according to claim 4 or 5. The curable resin composition layer further comprises one or more components 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 4 to 6 , comprising: 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,
1 selected from alkylene structural units, alkyleneoxy structural units, butadiene structural units, isoprene structural units, isobutylene structural units, chloroprene structural units, urethane structural units, polycarbonate structural units, (meth) acrylate structural units, and polysiloxane structural units The resin sheet according to claim 7 having the above structural unit. The resin sheet according to any one of claims 1 to 8 , which is for a circuit board with a built-in component. An insulating layer obtained by curing the curable resin composition layer of the resin sheet according to any one of claims 1 to 9 ,
A wiring board comprising: a conductor layer. A semiconductor device comprising the wiring board according to claim 10 .

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