JP2010209140A - Prepreg, metal-clad laminate and printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg which is excellent in laser processability, exhibits little coming-off of a resin, and is largely reduced in coefficient of thermal expansion in the X-Y direction, to provide a metal clad laminate using the prepreg, and to provide a printed circuit board excellent in connection reliability. <P>SOLUTION: There are provided the prepreg using, as a substrate, a woven fabric or a nonwoven fabric comprising organic fibers and a thermosetting resin composition consisting mainly of (A) a functional group-having acrylic rubber, (B) an epoxy resin having at least one kind selected from naphthol skeletons, naphthalenediol skeletons, biphenyl skeletons and dicyclopentadiene skeletons, (C) a novolak type phenolic resin having at least one kind selected from naphthol skeletons, naphthalenediol skeletons, biphenyl skeletons and dicyclopentadiene skeletons, (D) a bismaleimide-aminophenol addition reaction product, and (E) molten silica; the metal-clad laminate using the prepreg; and the printed circuit board using the metal-clad laminate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a prepreg, a metal-clad laminate, and a printed wiring board. More specifically, the present invention relates to a prepreg with excellent laser processability, extremely low resin dropout and low thermal expansion, a metal-clad laminate with excellent heat resistance, adhesion and moisture resistance, and a printed wiring board with excellent connection reliability. .

In recent years, with the reduction in size, weight, and functionality of electric / electronic devices, multilayer printed wiring boards used in such devices are increasingly required to be thinner and higher in density. In response to such a demand, a build-up type multilayer printed wiring board has been used.
This build-up type multilayer printed wiring board is prepared by, for example, laminating and arranging a prepreg impregnated with a thermosetting resin on a base material and a copper foil to produce a core material by thermocompression bonding. A buildup layer is formed by using prepreg. According to such a method, high-density wiring is possible as compared with the conventional multilayer printed wiring board.
Conventionally, a prepreg used for forming a core material or a build-up layer in a multilayer printed wiring board of a build-up method is manufactured by a combination of an epoxy resin having a high glass transition temperature (Tg) and a glass cloth. A build-up type multilayer printed wiring board using such a prepreg has a coefficient of thermal expansion of 15 to 18 ppm / ° C. in the XY direction or plane direction (fiber direction).

On the other hand, the thermal expansion coefficient of a silicon chip mounted on such a build-up type multilayer printed wiring board is about 3 ppm / ° C. For this reason, when the build-up type multilayer printed wiring board and the silicon chip are flip-chip mounted, stress is generated due to the difference in thermal expansion coefficient between them, and the connection reliability between them becomes insufficient. As a solution to such a problem, for example, an aramid fiber nonwoven fabric substrate in which an aramid fiber nonwoven fabric is impregnated with an epoxy resin as a thermosetting resin is known. Since the aramid fiber has a low coefficient of thermal expansion, it is possible to make a substrate excellent in low thermal expansion and dimensional stability by firmly connecting the resins with the aramid fiber (see, for example, Patent Document 1). ).
However, even in such a multilayer printed wiring board using a prepreg in which an aramid fiber nonwoven fabric is impregnated with an epoxy resin, the difference in thermal expansion coefficient between the silicon chip and the prepreg is still quite large. Further, in recent silicon chips, a low dielectric constant layer is formed on the surface for high-speed computation or the like, and the silicon chip becomes very brittle due to the formation of the low dielectric constant layer.
In order to solve such problems, when the thermal expansion coefficient of the multilayer printed wiring board for semiconductor packages used for mounting the silicon chip is reduced to the same level as the thermal expansion coefficient of the silicon chip, and the silicon chip is mounted In a multilayer printed wiring board for a semiconductor package using a prepreg obtained by impregnating and drying only a general-purpose epoxy resin such as bisphenol A as the insulating layer, in order to ensure the connection reliability of the prepreg, Although it has been proposed to use a woven fabric made of organic fibers having a negative coefficient of thermal expansion (see, for example, Patent Document 2), a printed wiring board is produced in response to the recent demand for high-definition wiring density. The performance is not sufficient in the present situation where improvement in yield and further improvement in reliability are strongly desired.
Therefore, a resin composition obtained by combining an epoxy resin having a specific structure different from an epoxy resin such as a bisphenol A type with a polyimide resin and / or a polyamideimide resin having a polysiloxane skeleton is obtained from an organic fiber having a negative coefficient of thermal expansion. A laminated board and a printed wiring board impregnated in a woven fabric have been proposed (see, for example, Patent Document 3), but this still does not provide sufficient performance.
Further, in the processing of small diameter vias, laser processing is prevalent, but as the diameter is further reduced, a prepreg having better laser processing properties is required. In such a situation, improvement using an organic fiber-based material as a base material has been studied, but there is still much room for improvement (see, for example, Patent Documents 4 and 5).

Japanese Patent Laid-Open No. 5-90721 JP 2006-203142 A JP 2007-2111182 A Japanese Patent Laid-Open No. 2005-2227 JP 2006-57074 A

  In view of the prior art as described above, the present invention is excellent in laser processing, has very little resin drop-off, and has a significantly reduced thermal expansion coefficient in the XY direction and a metal-clad laminate using the prepreg, An object of the present invention is to provide a printed wiring board having excellent connection reliability.

  As a result of diligent investigations, the present inventors have found that an acrylic rubber having a functional group, a resin having a specific structure, an addition reaction product of bismaleimide and aminophenol, and fused silica having a specific particle size are essential components. It was found that the above object could be achieved by using a thermosetting resin composition and using a woven or non-woven fabric composed of organic fibers as a base material.

That is, the present invention provides the following prepreg, a metal-clad laminate and a printed wiring board using the prepreg. (A) an acrylic rubber having a functional group,
(B) an epoxy resin having at least one selected from a naphthol skeleton, a naphthalenediol skeleton, a biphenyl skeleton, and a dicyclopentadiene skeleton,
(C) a novolak-type phenolic resin having at least one selected from a naphthol skeleton, a naphthalenediol skeleton, a biphenyl skeleton, and a dicyclopentadiene skeleton,
(D) an addition reaction product obtained by heating and reacting a bismaleimide represented by the following general formula (I) and an aminophenol represented by the following general formula (II);

(Wherein R ¹ represents a hydrogen atom or an alkyl group, R ² represents a divalent organic group selected from —O—, —CH ₂ —, —SO ₂ — and S—S—, and R ³ represents Represents a hydrogen atom, a halogen atom or an alkyl group.)

(In the formula, R ⁴ represents a hydrogen atom, a halogen atom or an alkyl group.)
(E) A prepreg characterized by using a thermosetting resin composition containing fused silica as an essential component and a woven or non-woven fabric composed of organic fibers as a base material.

2. (D) 5-60 mass% of addition reaction products of a component are contained in a thermosetting resin composition, The prepreg of said 1 characterized by the above-mentioned.
3. The prepreg according to 1 or 2 above, wherein the functional group in the component (A) is a hydroxyl group and / or a carboxyl group.
4). (E) The prepreg in any one of said 1-3 whose average particle diameter of the fused silica of a component is 0.05-2 micrometers and a largest particle diameter is 10 micrometers or less.
5). The prepreg according to any one of 1 to 4 above, wherein the acrylic rubber as the component (A) has a number average molecular weight of 10,000 to 100,000.
6). The prepreg according to any one of 1 to 5 above, wherein the organic fiber has a negative linear expansion coefficient and an elastic modulus is 70 GPa or more.
7). The prepreg according to any one of 1 to 6 above, wherein the organic fiber is any one selected from an aramid fiber, a polyparabenzoxazole fiber, and a polyarylate fiber.
8). A metal-clad laminate having an insulating layer formed by pressure-molding the prepreg according to any one of 1 to 7 under heating, and a metal foil integrated on at least one surface thereof.
9. 9. A printed wiring board comprising the metal-clad laminate and the semiconductor chip as described in 8 above.

  The present invention provides a prepreg, a metal-clad laminate, and a printed wiring board excellent in connection reliability, which have excellent laser processability, high heat resistance under moisture absorption, and a low coefficient of thermal expansion.

[Prepreg]
The prepreg of the present invention is characterized by using a thermosetting resin composition having the following components (A) to (D) as essential components and a woven or non-woven fabric composed of organic fibers as a base material. Is.
(Thermosetting resin composition)
<(A) Acrylic rubber>
The acrylic rubber used in the present invention is an acrylic ester having an alkyl group having 1 to 20 carbon atoms and a simple group having a functional group such as a hydroxyl group, a carboxyl group, an amino group, and an epoxy (glycidyl) group that acts as a crosslinking point. It is a polymer having a functional group such as a hydroxyl group, a carboxyl group, an amino group or an epoxy group in a side chain obtained by copolymerizing a monomer mixture.

  Specific examples of (meth) acrylic acid ester having an alkyl group having 1 to 20 carbon atoms include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, acrylic acid Isobutyl, ethylene glycol methyl ether acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, isobornyl acrylate, isodecyl acrylate, octadecyl acrylate, lauryl acrylate, allyl acrylate, acrylic acid N -Vinylpyrrolidone, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, isobutyl methacrylate, methacrylate Le ethylene glycol methyl ether, cyclohexyl methacrylate, isobornyl methacrylate, isodecyl methacrylate, octadecyl methacrylate, lauryl methacrylate, and allyl methacrylate.

  Examples of the monomer having a hydroxyl group include hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxystyrene, and hydroxyphenylmaleimide. Examples of the monomer having a carboxyl group include monocarboxylic acids such as acrylic acid and methacrylic acid, and maleic acid, fumaric acid, and itaconic acid.

  Examples of the monomer having an amino group include N, N-diethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N- Dialkylaminoalkyl (meth) acrylates such as dimethylaminopropyl (meth) acrylate and N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl acrylamide, N, N-diethylaminopropyl acrylamide, N, N- Dialkylaminoalkyl (meth) acrylamides such as diethylaminopropyl (meth) acrylamide, aminopropyl (meth) acrylate, aminobutyl (meth) acrylate, butylvinylbenzylamine, vinylphenylamine, p-a N-methylaminoethyl (meth) acrylate, Nt-butylaminoethyl (meth) acrylate, etc .; N- [2- (meth) acryloyloxyethyl] piperidine, N- [2- (meth) acryloyloxy Ethyl] pyrrolidine, N- [2- (meth) acryloyloxyethyl] morpholine, 4- [N, N-dimethylamino] styrene, 4- [N, N-diethylamino] styrene, 2-vinylpyridine, 4-vinylpyridine Etc. Examples of the monomer having an epoxy (glycidyl) group include glycidyl (meth) acrylate, allyl glycidyl ether, and methallyl glycidyl ether.

  The functional group of the acrylic rubber is preferably a hydroxyl group and / or a carboxyl group, and the amount of the monomer unit having a functional group is included in the constituent monomer unit of the acrylic rubber in an amount of 0.05 to 10% by mass. It is preferable. When the amount of the monomer having a functional group is less than 0.05% by mass or more than 10% by mass, the appearance of the prepreg is deteriorated, and when it is less than 0.05% by mass, the mechanical stability of the acrylic rubber is inferior. It is not preferable. It is particularly preferable that the content is 0.05 to 3% by mass.

  The number average molecular weight of the acrylic rubber is preferably 10,000 to 100,000. The number average molecular weight is a value measured by gel permeation chromatography (GPC) analysis, and means a standard polystyrene equivalent value. The GPC analysis can be performed, for example, using tetrahydrofuran (THF) as an eluent.

  The acrylic rubber can be obtained, for example, by a method of radical polymerization (mainly emulsion polymerization or suspension polymerization) of the monomer using a radical polymerization initiator that generates radicals. Examples of radical polymerization initiators include persulfates such as azobisisobutyronitrile (AIBN), tert-butyl perbenzoate, benzoyl peroxide, lauroyl peroxide, potassium persulfate, cumene hydroperoxide, and t-butyl hydroperoxide. Dicumyl peroxide, di-t-butyl peroxide, 2,2′-azobis-2,4-dimethylvaleronitrile, t-butyl perisobutyrate, t-butyl perpivalate, hydrogen peroxide / ferrous salt, Examples thereof include persulfate / sodium acid sulfite, cumene hydroperoxide / ferrous salt, benzoyl peroxide / dimethylaniline, and the like. These may be used alone or in combination of two or more.

  Acrylic rubber, if necessary, cross-linking agents such as isocyanate and melamine, polymer compounds such as epoxy resins, flame retardants such as rubber elastomers and phosphorus compounds, inorganic fillers such as silica, coupling agents, You may mix and use a pigment, a leveling agent, an antifoamer, an ion trap agent, etc.

  As the acrylic rubber having a functional group, a commercially available product can be used as it is. As commercially available products, SG-708-6T, SG-708-6, SG-70L (above, acrylic rubber manufactured by Nagase ChemteX), AREX-120, AREX-220, AREX-320, PHR-1H (above, Acrylic rubber manufactured by JSR), Lx-854 (acrylic rubber manufactured by Nippon Zeon), Nipol 1072, Nipol 1072B, Nipol 1072J (above, acrylic rubber manufactured by Nippon Zeon), Clinac X7.5 (acrylic rubber manufactured by Bayer), Hiker, CTBN1300XB, CTBN1300X15, or CTBNX1300XB (above, BF Goodrich Chemical Co., Ltd. acrylic rubber), Bomac GLS (Mitsui, DuPont Polychemical acrylic rubber), and the like.

  The blending ratio of the acrylic rubber as the component (A) is preferably 10 to 40% by mass, more preferably 15 to 30% by mass, based on the entire thermosetting resin composition. When the blending ratio is 10% by mass or more, adhesion with organic fibers is prevented from being lowered, and when it is 40% by mass or less, heat resistance is prevented from being lowered.

<(B) Epoxy resin>
The epoxy resin as component (B) is limited to the molecular structure, molecular weight, etc. as long as it has at least one selected from a naphthol skeleton, naphthalenediol skeleton, biphenyl skeleton and dicyclopentadiene skeleton in the molecular structure. Used without. Specific examples of such an epoxy resin include NC-7000L (product name, epoxy equivalent 234, manufactured by Nippon Kayaku Co., Ltd.), which is a polyfunctional epoxy resin having an α-naphthol skeleton, and a polyfunctional epoxy resin having a β-naphthol skeleton. ESN-175SV (trade name, epoxy equivalent 290 manufactured by Toto Kasei Co., Ltd.) which is a type epoxy resin, ESN-375 (trade name, epoxy equivalent 173 manufactured by Toto Kasei Co., Ltd.) which is a polyfunctional epoxy resin containing a naphthalenediol skeleton ), EXA-4700 (trade name, epoxy equivalent 164, manufactured by DIC), which is a tetrafunctional epoxy resin similarly containing a naphthalenediol skeleton, and NC-3000SH (Nipponization), a polyfunctional epoxy resin having a biphenyl skeleton. Product name, epoxy equivalent 291), polyfunctional epoxy having dicyclopentadiene skeleton It is a xy resin (manufactured by DIC, trade name, HP-7200HH, epoxy equivalent 280) and the like. These epoxy resins may be used individually by 1 type, and 2 or more types may be mixed and used for them.

In the present invention, an epoxy resin having two or more epoxy groups in one molecule other than the component (B) can be used in combination as long as the effects of the present invention are not impaired. Examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, novolac type epoxy resins, cresol novolac type epoxy resins, glycidyl ether type epoxy resins, alicyclic epoxy resins, and heterocyclic type epoxy resins. Etc.
(B) It is preferable that the mixture ratio of the epoxy resin which is a component is 10-60 mass% in the whole thermosetting resin composition, More preferably, it is 20-50 mass%. When the blending ratio is 10% by mass or more, the heat resistance is prevented from being lowered, and when it is 60% by mass or less, the adhesion with the organic fiber described later is prevented from being lowered.

<(C) Novolac type phenolic resin>
The novolak type phenolic resin as component (C) acts as a curing agent for the epoxy resin as component (B), and has at least a molecular structure selected from a naphthol skeleton, naphthalenediol skeleton, biphenyl skeleton and dicyclopentadiene skeleton. If it has 1 type, it will be used without being restrict | limited to molecular weight etc. Specific examples of such novolak-type phenol resins include SN-485 (trade name, hydroxyl equivalent 215, manufactured by Nippon Steel Chemical Co., Ltd.), a phenol containing a naphthalenediol skeleton, which is a cresol novolak resin having an α-naphthol skeleton. SN-395 which is a novolak resin (manufactured by Nippon Steel Chemical Co., Ltd., trade name, hydroxyl equivalent 105), MEH-7851-3H which is a phenol novolac resin having a biphenyl skeleton (trade name, hydroxyl equivalent 223 by Meiwa Kasei Co., Ltd.) And DPP-6125 (trade name, hydroxyl group equivalent 185, manufactured by Nippon Petrochemical Co., Ltd.), which is a phenol novolac resin containing a dicyclopentadiene skeleton. These phenol resins may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  In the present invention, a phenol resin other than the component (C) can be used in combination as long as the effects of the present invention are not impaired. As such a phenolic resin, in addition to a novolak type phenolic resin having no naphthol skeleton, naphthalenediol skeleton, biphenyl skeleton and dicyclopentadiene skeleton in the molecular structure, it has been conventionally used as a curing agent for epoxy resins. Various phenol resins, specifically, phenol or cresol resin such as cresol novolac type resin and phenol novolac type resin can be mixed and used. In this case, the phenol resin or cresol resin other than the component (C) is preferably 30% by mass or less of the entire component (C).

  The blending amount of the phenol resin is preferably in a range in which the ratio [number of phenolic hydroxyl groups / number of epoxy groups] of the number of phenolic hydroxyl groups of the phenol resin to the number of epoxy groups of the epoxy resin is 0.5 to 1. A range of 8 to 1 is more preferable. When it is 0.5 or more, the heat resistance is prevented from being lowered, and when it is 1 or less, the adhesion with the organic fiber described later is prevented from being lowered.

<(D) Addition reaction product of bismaleimide and aminophenol>
The component (D) is an addition reaction product obtained by heating and reacting bismaleimide and aminophenol.
Bismaleimide is represented by the following general formula (I).

In general formula (I), R ¹ represents a hydrogen atom or an alkyl group, and the alkyl group may be linear, branched or cyclic. R ² represents a divalent organic group selected from —O—, —CH ₂ —, —SO ₂ — and S—S—. R ³ represents a hydrogen atom, a halogen atom or an alkyl group, and the alkyl group may be linear, branched or cyclic.
Specific examples of the bismaleimide represented by the general formula (I) include 4,4′-diphenylmethane bismaleimide, 4,4′-diphenyl ether bismaleimide, 4,4′-diphenylsulfone bismaleimide, 4,4′- And dithiobis (N-phenylmaleimide).
Aminophenol is represented by the following general formula (II).

In the general formula (II), R ⁴ represents a hydrogen atom, a halogen atom or an alkyl group, and the alkyl group may be linear, branched or cyclic.
Specific examples of the aminophenol represented by the general formula (II) include ortho, meta or para isomer aminophenol and aminocresol, 2-amino-4-chlorophenol, 2-amino-4-chlorocresol, and the like. Examples include aminocresol, aminochlorophenol and aminobromophenol having positional isomers.

The heat reaction of bismaleimide and aminophenol may be melted and heated, or may be heated in a solvent such as dioxane, N, N-dimethylacetamide, or N-methyl-2-pyrrolidone.
The heating reaction under melting is, for example, when bismaleimide and aminophenol are stirred and the temperature is raised, it is melted at about 100 ° C., kept at a temperature of about 100 to 150 ° C., and then cooled to room temperature. Then, a solid or viscous addition reaction product can be obtained.
The proportion of the reaction is preferably 10 to 30 parts by mass of aminophenol with respect to 100 parts by mass of bismaleimide.
The content of the component (D) is preferably 5 to 60% by mass and more preferably 5 to 40% by mass in the thermosetting resin composition. By setting it as this range, heat resistance and adhesiveness are stabilized, and laser workability is improved.

<(E) fused silica>
The fused silica as the component (E) preferably has an average particle size of 0.05 to 2 μm and a maximum particle size of 10 μm or less. It is preferable to use a material having such an average particle size and maximum particle size since the fluidity of the thermosetting resin composition becomes good. For the measurement of the average particle size and the maximum particle size, for example, a laser diffraction scattering type particle size distribution measuring device can be used.
The fused silica as component (E) can be used after surface treatment with a silane-based or titanium-based coupling agent, etc., if necessary. Silane coupling agents include epoxy silanes such as γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropylmethyldiethoxysilane; γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) Examples include aminosilanes such as -γ-aminopropyltrimethoxysilane.

The blending ratio of the fused silica as the component (E) is preferably 20 to 50% by mass and more preferably 30 to 40% by mass in the entire thermosetting resin composition. When the blending ratio is 20% by mass or more, the heat resistance is prevented from being lowered, and when it is 50% by mass or less, the adhesion with organic fibers described later is prevented from being lowered.
Along with the fused silica as component (E), if necessary, synthetic silica, crystalline silica, alumina, zirconia, talc, clay, mica, calcium carbonate, magnesium hydroxide, aluminum hydroxide, titanium white, bengara, silicon carbide, Powders such as boron nitride, silicon nitride, and aluminum nitride, beads obtained by spheroidizing these, single crystal fibers, glass fibers, and the like can be used alone or in admixture of two or more.

<Additive>
The thermosetting resin composition according to the present invention includes a curing accelerator, a flame retardant such as a metal hydroxide and zinc borate, and an antifoaming agent as long as the effects of the present invention are not impaired in addition to the above-described components. , Leveling agents and other commonly used additives can be blended as required.

  As curing accelerators, 2-heptadecylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 4-methylimidazole, 4-ethylimidazole, 2-phenyl- 4-hydroxymethylimidazole, 2-enyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, etc. Imidazole compounds; trimethylphosphine, triethylphosphine, tributylphosphine, triphenylphosphine, tri (p-methylphenyl) phosphine, tri (nonylphenyl) phosphine, methyldiphenylphosphine, dibutyl Such as ruphenylphosphine, tricyclohexylphosphine, bis (diphenylphosphino) methane, 1,2-bis (diphenylphosphino) ethane, tetraphenylphosphonium tetraphenylborate, triphenylphosphinetetraphenylborate, triphenylphosphinetriphenylborane, etc. Organic phosphine compounds; diazabicycloalkene compounds such as 1,8-diazabicyclo [5,4,0] undecene-7 (DBU), 1,5-diazabicyclo (4,3,0) nonene-5; triethylamine, triethylenediamine , Tertiary amine compounds such as benzyldimethylamine, α-methylbenzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris (dimethylaminomethyl) phenol. These can be used alone or in admixture of two or more.

(Preparation of resin solution)
The thermosetting resin composition in the present invention is the above-mentioned essential components (A), (B), (C), (D) and (E), and the various additions blended as necessary. The agent is prepared as a resin solution (varnish) by uniformly dissolving or dispersing the agent in a suitable solvent.

The solvent used for dissolving or dispersing the thermosetting resin composition is not particularly limited, but a solvent having a boiling point of 220 ° C. or lower is preferably used in order to minimize the amount remaining in the prepreg. Specific examples of the solvent include γ-butyrolactone, N-methyl-2-pyrrolidone, dimethylacetamide, methyl ethyl ketone, toluene, acetone, ethyl cellosolve, methyl cellosolve, cyclohexanone, propylene glycol monomethyl ether, and the like. A mixture of more than one species can be used. Among the above solvents, propylene glycol monomethyl ether is preferably used.
The solid content concentration of the varnish is not particularly limited, but if it is too low, the amount of the resin impregnated in the prepreg decreases, and if it is too high, the viscosity of the varnish increases and the appearance of the prepreg may deteriorate. The range of 40-80 mass% is preferable, More preferably, it is 60-70 mass%.

(Base material)
As a base material impregnated with varnish, organic materials such as aramid fiber, polyparabenzoxazole fiber and polyarylate fiber having a negative coefficient of thermal expansion (JIS K7197) and a tensile elastic modulus (JIS L1013) of 70 GPa or more. A woven fabric or a nonwoven fabric made of fibers is preferred. The weaving method for the woven fabric is not particularly limited, but plain weaving is preferable from the viewpoint of flatness.

  Woven fabrics or nonwoven fabrics made of the above-mentioned organic fibers are commercially available, and as aramid fibers, for example, Asahi Schwer's aramid fiber woven fabric, Kevlar (manufactured by DuPont, trade name) using Technora fibers manufactured by Teijin Techno Products Co., Ltd. Examples thereof include aramid fiber woven fabrics KS1020, KS1080, and KS1220 (trade name, manufactured by Kanebo Co., Ltd.). Examples of the polyparabenzoxazole fibers include Asahi Sebel polyparabenzoxazole fiber woven fabric using Toyobo's Zylon-AS and Zylon HM fibers. Furthermore, as a polyarylate fiber, the polyarylate fiber woven fabric made from Asahi Sebel using Vectran UM fiber made by Kuraray Co., Ltd., etc. are mentioned.

(Manufacture of prepreg)
The prepreg of the present invention can be produced by applying or impregnating a varnish prepared as described above to a substrate and then drying to remove the solvent.
The amount of varnish impregnated in the prepreg is preferably in the range of 40 to 70% by mass as the solid content in the total amount with the base material. By setting the content to 40% by mass or more, it is possible to prevent an unimpregnated portion from being generated in the base material, and to prevent generation of voids and scum when a laminated board is formed. Further, by setting the content to 70% by mass or less, it is possible to prevent the thickness variation from becoming large and it is difficult to obtain a uniform laminated board or printed wiring board. The method of impregnating or applying the varnish to the substrate and the method of drying after impregnation or application are not particularly limited, and conventionally known methods can be used.

[Metal-clad laminates and printed wiring boards]
The laminate of the present invention can be produced by laminating a required number of the prepregs thus obtained and pressurizing them under heating. Moreover, the metal-clad laminate of the present invention can be produced by stacking a metal foil such as a copper foil on one side or both sides of the required number of prepregs, and applying pressure under heating.
Furthermore, the printed wiring board of the present invention can be manufactured by laminating semiconductor chips such as silicon chips by etching the metal-clad laminate in a conventional manner. The heating and pressurizing conditions for producing the laminated plate and the metal-clad laminated plate are not particularly limited, but usually a temperature of about 170 to 200 ° C., a pressure of about 5 to 50 MPa, and a time of 90 to 150 minutes. Degree.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these Examples. In the following examples and comparative examples, “part” represents “part by mass”.

[(D) Production of addition reaction product]
1,000 parts of 4,4′-diphenylmethane bismaleimide and 183 parts of m-aminophenol were mixed and melted at 100 ° C. while stirring, and then heated to 130 ° C. and held for 60 minutes for a heat reaction. Thereafter, it was cooled to room temperature to produce a solid addition reaction product.
The addition reaction product was pulverized, and 1000 parts of N-methyl-2-pyrrolidone was added to 1000 parts of the addition reaction product to prepare an addition reaction product solution.

[Varnish Preparation Example 1]: Acrylic rubber having a naphthol-based hydroxyl group and a carboxyl group (component (A): manufactured by Nagase Chemitech, trade name “SG-708-6T”, solid content 20 mass%, number average molecular weight 100,000 ) 1256 parts, polyfunctional epoxy resin having an α-naphthol skeleton (component (B): Nippon Kayaku Co., Ltd., trade name “NC-7000L”, epoxy equivalent 234) 552 parts, α-naphthol skeleton-containing cresol novolak resin ( Component (C): manufactured by Nippon Steel Chemical Co., Ltd., trade name “SN-485”, hydroxyl group equivalent 215) 113 parts, 489 parts of the addition reaction product solution (component (D)), fused silica (component (E): ad Made by Mattex, trade name “SE1050”, average particle size 0.3 μm, maximum particle size 5 μm) 1005 parts, 2-ethyl-4-methylimidazole (hereinafter “2E4MZ”) Propylene glycol monomethyl ether (hereinafter “PGMME”) was added as a solvent to a mixture consisting of 8.3 parts to prepare varnish 1 having a solid content of 65 mass%.

[Varnish Preparation Example 2]: Biphenyl-based “SG-708-6T” (component (A)) 1754 parts, polyfunctional epoxy resin having biphenyl skeleton (component (B): Nippon Kayaku Co., Ltd., trade name “NC” -3000SH ", epoxy equivalent 291) 646 parts, novolak type phenolic resin having biphenyl skeleton (component (C): manufactured by Meiwa Kasei Co., Ltd., trade name" MEH-7851-3H ", hydroxyl equivalent 223) 196 parts, the addition reaction To a mixture of 846 parts of the product solution (component (D)), 600 parts of “SE1050” (component (E)), and 9.0 parts of “2E4MZ”, and then adding “PGMME” as a solvent to a varnish having a solid content of 65% by mass 2 was prepared.

[Varnish Preparation Example 3]
Varnish 3 was prepared in the same manner as Varnish Preparation Example 1 except that the addition reaction product solution (component (D)) was not added.
[Varnish Preparation Example 4]
Varnish 4 was prepared in the same manner as in Varnish Preparation Example 1 except that acrylic rubber (component (A)) was not added.
[Varnish Preparation Example 5]
Varnish 5 was prepared in the same manner as in Varnish Preparation Example 1 except that fused silica (component (E)) was not added.

[Varnish Preparation Example 6]
Varnish 6 as in Varnish Preparation Example 1, except that 250 parts of polyimide resin (containing siloxane skeleton, manufactured by Ube Industries, trade name “UPA-83”) is used instead of the addition reaction product solution (component (D)) Adjusted.
[Varnish Preparation Example 7]
Varnish 7 was prepared in the same manner as in Varnish Preparation Example 1 except that 840 parts of polyamideimide resin (manufactured by Hitachi Chemical Co., Ltd., trade name “KS9005”) was used instead of the addition reaction product solution (component (D)).

[Varnish Preparation Example 8]
Acrylic rubber having a hydroxyl group and a carboxyl group (component (A): manufactured by Nagase Chemitech, trade name “SG-708-6T”, solid content 20 mass%, number average molecular weight 100,000) 1210 parts, α-naphthol skeleton Multifunctional epoxy resin (component (B): Nippon Kayaku Co., Ltd., trade name “NC-7000L”, epoxy equivalent 234) 552 parts, imide-modified novolak resin (component (C): Meiwa Kasei Co., Ltd., trade name “ MEH-8205 ”, hydroxyl group equivalent 146) 344 parts, fused silica (component (E): manufactured by Admatechs, trade name“ SE1050 ”, average particle size 0.3 μm, maximum particle size 5 μm) 968 parts,“ 2E4MZ ”8 To a mixture of 3 parts, “PGMME” was added as a solvent to prepare varnish 8 having a solid content of 65% by mass.

[Examples 1-1 to 3-2] [Comparative Examples 1-1 to 3-7]
As shown in Tables 1 to 3, the varnishes 1 to 8 prepared in the varnish preparation examples were prepared from Asahi Sebel Aramid fiber woven fabric (61 g / m ² , thermal expansion coefficient −5 ppm / ° C., Teijin Techno having an elastic modulus of 70 GPa. Technora fiber manufactured by Products), polyarylate fiber woven fabric manufactured by Asahi Sebel (61 g / m ² , thermal expansion coefficient -6 ppm / ° C., Kuraray Vectran UM fiber (liquid crystal polymer fiber) having an elastic modulus of 106 GPa) , Polyparabenzoxazole fiber woven fabric (64.5 g / m ² , thermal expansion coefficient -6 ppm / ° C., using SYRON HM fiber made by Toyobo Co., Ltd.) with elastic modulus of 270 GPa or Unitika E glass fiber woven fabric (54 g / m 2, trade name E06CSK) was impregnated and dried to obtain a prepreg having a resin impregnation amount of 65% by mass.

Eight prepregs obtained were overlapped, 18 μm thick copper foils were stacked on the top and bottom, sandwiched between stainless plates, and pressed under heating at 190 ° C. and 4 MPa for 130 minutes to obtain a copper-clad laminate.
The linear expansion coefficient in the XY direction (plane direction of the substrate) and the Z direction (thickness direction of the substrate) of the printed circuit board produced by etching the copper foil of this copper-clad laminate, peel strength of the copper foil (peel strength), Solder heat resistance and mesling resistance were tested.
In addition, a 0.03mm thick test silicon chip is mounted on a laminate by the C4 method, a vapor-phase thermal shock test is conducted, and through hole connection reliability and chip connection reliability are tested. The printed wiring board yield and laser processability were examined.

The measuring methods for the above physical properties are as follows.
(1) Linear expansion coefficient After etching the copper foil, each coefficient of thermal expansion in the X direction (machine feed direction of the woven fabric), Y direction (width direction of the woven fabric), and Z direction (thickness direction of the woven fabric) Using a thermomechanical analyzer TMA / SS6000 (trade name) manufactured by Instruments Co., Ltd., the temperature was measured under a temperature increase condition of 5 ° C./min in a nitrogen atmosphere by the TMA method. Similarly, each coefficient of thermal expansion in the X direction and the Y direction of the prepreg was measured.

(2) Copper foil peeling strength (peel strength)
It measured according to JIS C 6481.
(3) Solder heat resistance A sample was floated on each solder bath at 280 ° C. and 288 ° C. for 10 minutes to observe the presence or absence of swelling, and evaluated according to the following criteria.
◎: No blistering, ×: Bulging (4) Measeling resistance After 121 ° C and 2 atm saturated water vapor for 5 hours of moisture resistance treatment, it was immersed in a 260 ° C solder bath for 30 seconds. The presence or absence was observed and evaluated according to the following criteria. “PCT 2 hours” in the table means a pressure cooker test.
◎: Good, ○: Somewhat bad, ×: Bad (5) Connection reliability of through hole After drilling with a 0.5mmφ drill, through hole plating and circuit formation were performed, and a test sample of 500 continuous holes was prepared, This test sample was subjected to a liquid phase impact test of 25 ° C. × 30 seconds to 260 ° C. × 10 seconds, 200 cycles, and the conduction reliability was evaluated according to the following criteria.
◎: Good, △: Slightly defective, X: Defective (6) Connection reliability with chip Flip chip mounting of 0.03mm □ test silicon chip on the patterned copper-clad laminate by C4 method, and vapor phase A thermal shock test (heating and cooling between −55 ° C. and 150 ° C. was repeated 1000 times) was performed, and the conduction reliability was evaluated according to the following criteria.
○: Good, △: Somewhat bad, ×: Bad

(7) Pre-preg powder dropping The powder adhering to the prepreg surface was detached with cello tape (registered trademark), and the adhesion level was judged.
○: There is almost no adhering powder ×: There is much adhering powder (8) Printed wiring board yield Confirmation of appearance yield by circuit formation of the circuit board on which the pattern was formed on the copper clad laminate used in the test of (6) above did. Those in which there was no short circuit or disconnection in the circuit were considered good, and some of them were considered bad. 500 substrates were judged and judged by non-defective product rate (%).
○: Non-defective product rate is 90% or more ×: Non-defective product rate is less than 70% (9) Laser workability A laser sheet is attached to the front and back surfaces of a copper clad laminate, and a through hole with a hole diameter of 0.1 mm using a carbon dioxide laser. Processing was performed, and cross-sectional observation of the hole after plating was performed.
The level of hole shape was evaluated according to the following criteria.
○: No outgrowth △: Small outgrowth occurrence ×: Large outgrowth occurrence

  The prepreg and metal-clad laminate of the present invention have good laser processability, high heat resistance under moisture absorption, low thermal expansion coefficient, and excellent connection reliability, especially printed wiring boards, especially build-up systems It is extremely useful in the field of manufacturing multi-layer printed wiring.

Claims (9)

(A) an acrylic rubber having a functional group,
(B) an epoxy resin having at least one selected from a naphthol skeleton, a naphthalenediol skeleton, a biphenyl skeleton, and a dicyclopentadiene skeleton,
(C) a novolak-type phenolic resin having at least one selected from a naphthol skeleton, a naphthalenediol skeleton, a biphenyl skeleton, and a dicyclopentadiene skeleton,
(D) an addition reaction product obtained by heating and reacting a bismaleimide represented by the following general formula (I) and an aminophenol represented by the following general formula (II);

(Wherein R ¹ represents a hydrogen atom or an alkyl group, R ² represents a divalent organic group selected from —O—, —CH ₂ —, —SO ₂ — and S—S—, and R ³ represents Represents a hydrogen atom, a halogen atom or an alkyl group.)

(In the formula, R ⁴ represents a hydrogen atom, a halogen atom or an alkyl group.)
(E) A prepreg characterized by using a thermosetting resin composition containing fused silica as an essential component and a woven or non-woven fabric composed of organic fibers as a base material.   The prepreg according to claim 1, wherein the addition reaction product of component (D) is contained in the thermosetting resin composition in an amount of 5 to 60% by mass.   The prepreg according to claim 1 or 2, wherein the functional group in component (A) is a hydroxyl group and / or a carboxyl group.   The prepreg according to any one of claims 1 to 3, wherein the fused silica as the component (E) has an average particle size of 0.05 to 2 µm and a maximum particle size of 10 µm or less.   The prepreg according to any one of claims 1 to 4, wherein the acrylic rubber of component (A) has a number average molecular weight of 10,000 to 100,000.   The prepreg according to any one of claims 1 to 5, wherein the organic fiber has a negative linear expansion coefficient and an elastic modulus is 70 GPa or more.   The prepreg according to any one of claims 1 to 6, wherein the organic fiber is any one selected from an aramid fiber, a polyparabenzoxazole fiber, and a polyarylate fiber.   A metal-clad laminate having an insulating layer formed by pressure-molding the prepreg according to any one of claims 1 to 7 and having a metal foil integrated on at least one surface thereof.   A printed wiring board comprising the metal-clad laminate according to claim 8 and a semiconductor chip.