KR101868161B1 - Varnish, prepreg, film with resin, metal foil-clad laminate, and printed circuit board - Google Patents

Abstract

The present invention relates to a resin having a functional group which reacts with an amino group and has a functional group which reacts with at least a part of the functional group of the resin having a polycyclic structure and a varnish obtained by reacting the amino group of the compound having an amino group in a solvent or a phenolic hydroxyl group Is a varnish obtained by reacting at least a part of the functional group of the resin containing a polycyclic structure with the phenolic hydroxyl group of the compound having a phenolic hydroxyl group in a solvent. Also, the prepreg, the resin-attached film, the metal foil-clad laminate, and the printed wiring board obtained by using any one of these varnishes.

Description

{VARNISH, PREPREG, FILM WITH RESIN, METAL FOIL-CLAD LAMINATE, AND PRINTED CIRCUIT BOARD}

TECHNICAL FIELD The present invention relates to a varnish for use in producing a laminated board and a printed wiring board for use in electronic equipment, and a prepreg, a resin-attached film, a metal foil-clad laminate, and a printed wiring board manufactured using the varnish.

BACKGROUND ART [0002] In recent years, electronic devices have become smaller and lighter in weight, and printed wiring boards used therefor are required to have high-density wiring by thin layering or micro wiring. In order to realize high-density wiring, a printed wiring board is required to have a low thermal expansion rate for the purpose of improving reliability of a fine wiring on a substrate. Particularly, in the use of a package substrate, which is a high-density printed wiring board for mounting a semiconductor device such as a semiconductor chip, required characteristics are more severe than in a core substrate or the like.

As a mounting method, a flip chip connection method is widely used instead of the conventional wire bonding method. The flip chip connection method is a method in which a wiring board and a semiconductor device are connected by a solder ball instead of a wire used for a wire bonding method and mounted. The semiconductor package using this mounting method includes a chip scale package (CSP), a package on package (PoP), and a system in package (SiP).

When connection is made by the solder balls, the solder balls and the wiring board are heated to about 300 DEG C at the time of solder reflow. The wiring board is generally made of a laminated board obtained by laminating a resin composition, a prepreg made of a fiber base or a support, a film with a resin and a metal foil, and wiring is formed of a metal foil. Therefore, the wiring board expands due to heat, and the difference in thermal expansion coefficient between the mounted electronic component (particularly, the semiconductor device) and the resin of the wiring board causes distortion of the substrate called warpage. In particular, So that cracks are generated and connection defects are caused.

The bending of the semiconductor package of the PoP structure will be described in detail with reference to Fig. First, the semiconductor package includes a semiconductor chip 10 on which a semiconductor package substrate 16 on which a through hole 20 is formed is electrically connected by a bonding wire 14, and a sealing agent 12 A sealed wiring board is provided through the solder balls 22 on the substrate 18. [ When heat is applied to the wiring board in this state, warping occurs due to a difference in coefficient of thermal expansion between the sealing material 12 and the chip 10 and the semiconductor package substrate 16, and a crack C is generated.

Under such circumstances, there is a demand for a laminate having low coefficient of thermal expansion which is less likely to warp. As a conventional laminated board, it is general that a resin composition containing an epoxy resin as a main component is impregnated with a woven fabric or a nonwoven fabric to form a plurality of prepregs, and then a metal foil is provided on one side or both sides of the prepreg to heat and press to be. Epoxy resins are excellent in balance of insulation, heat resistance and cost, but have a large thermal expansion rate. For this reason, it is common to add an inorganic filler such as silica as disclosed in Patent Document 1, for example, to lower the thermal expansion coefficient of the resin composition.

By further charging the inorganic filler, it is possible to further lower the thermal expansion rate. However, there is a limit to the difficulty in multi-layer wiring board and package board applications due to moisture absorption by the inorganic filler, deterioration of insulation reliability, poor adhesion of the resin-wiring layer, and deterioration of drilling workability.

Also, Patent Documents 2 and 3 disclose a method of increasing the crosslinking density of the resin composition and increasing the Tg to decrease the thermal expansion coefficient. However, raising the crosslinking density shortens the molecular chain between crosslinks, which has limitations in terms of reactivity and resin structure.

On the other hand, Patent Document 4 discloses a method using an epoxy resin having a polycyclic structure in which the molecular weight between cross-linking points is optimized as an effective means for reducing the thermal expansion coefficient. However, the conventional epoxy resin having a polycyclic structure has a low solubility in a solvent for crystallization due to mutual attraction of molecules in a polycyclic structure portion, and is recrystallized when it is returned to room temperature even if dissolved in an organic solvent by heating .

Patent Document 5 discloses a method using a resin including a polycyclic structure as an effective means for achieving low warpage. Patent Document 5 describes that a resin including a polycyclic structure is effective in the use of a sealing material. In the case of the sealing material application, varnishization is not required, and there is no problem of recrystallization when it is dissolved in an organic solvent.

However, when the development of the laminated board is studied, as described above, the resin containing a polycyclic structure is very difficult to use in an organic solvent and has a problem of poor storage stability at room temperature in a varnish state, It was necessary to dissolve the compound in a solvent and make it varnish.

Therefore, if the storage stability at room temperature of a resin containing a polycyclic structure can be improved, workability at the time of using the varnish improves, which is industrially significant.

Japanese Patent Application Laid-Open No. 2004-182851 Japanese Patent Application Laid-Open No. 2000-243864 Japanese Patent Application Laid-Open No. 2000-114727 Japanese Patent Application Laid-Open No. 2007-314782 Japanese Patent Application Laid-Open No. 2007-002110

It is an object of the present invention to provide a varnish having high storage stability at room temperature and excellent workability at the time of use, and a prepreg, a resin-attached film, a metal foil-clad laminate, and a printed wiring board using the varnish.

In order to achieve the above object, the inventors of the present invention have made extensive studies. The present invention is as follows.

[1] A varnish obtained by reacting a part of the functional group of a resin having a polycyclic structure with a functional group reacting with an amino group and the amino group of a compound having an amino group in a solvent.

[2] A process for producing a phenolic hydroxyl group-containing compound as described in [1] above, wherein a part of the functional group of the resin having a polycyclic structure and having a functional group reactive with the phenolic hydroxyl group is reacted with the phenolic hydroxyl group of the compound having a phenolic hydroxyl group , Varnish.

[3] The varnish according to [1] or [2], wherein the amino group-containing compound is any one of guanamine, dicyandiamide and aminotriazineinovolak.

[4] A varnish obtained by reacting a part of the functional group of a resin having a polycyclic structure with a functional group reacting with a phenolic hydroxyl group and the phenolic hydroxyl group of a compound having a phenolic hydroxyl group in a solvent.

[5] A varnish as described in [2] or [4], wherein the compound having a phenolic hydroxyl group is a phenol novolak resin or a cresol novolak resin.

[6] A varnish according to any one of [1] to [5], wherein the resin contains at least one epoxy group as the functional group.

[7] The resin composition according to any one of [1] to [6], wherein the resin has at least one selected from the group consisting of a biphenyl structure, a naphthalene structure, a biphenyl novolak structure, an anthracene structure and a dihydroanthracene structure , Varnish.

[8] A varnish comprising a resin component having a structure represented by the following formula (1).

(Wherein R < ¹ > is a residue of a compound having an amino group)

[9] A process for producing a varnish according to the above [8], wherein the presence ratio of the structure represented by the formula (1) to the sum of the respective abundance ratios of the structure represented by the formula (1) .

[10] A prepreg obtained by applying the varnish according to any one of [1] to [9] to a substrate and heating and drying the varnish.

[11] A prepreg according to the above [10], wherein the substrate is a glass woven fabric, a glass nonwoven fabric, an aramid woven fabric or an aramid nonwoven fabric.

[12] A resin-coated film obtained by applying the varnish according to any one of [1] to [9] to a film, followed by heating and drying.

[13] A metal foil-clad laminate having a conductor layer on at least one surface of the prepreg according to [10] or [11].

[14] A metal foil-clad laminate having a conductor layer on at least one surface of the resin-coated film according to [12] above.

[15] A printed wiring board comprising the conductor layer provided on at least one side of the metal foil-clad laminate according to [13] or [14].

According to the present invention, it is possible to provide a varnish having high storage stability at room temperature and excellent workability at the time of use, and a prepreg, resin-attached film, metal foil-clad laminate, and printed wiring board using the varnish.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory view showing a warp state of a semiconductor package having a PoP structure; FIG.
Fig. 2 is a DSC curve of YX-8800 and dicyandiamide at an equivalent ratio of 1: 1.

[1] Varnish:

The first varnish of the present invention is obtained by reacting at least part of the functional group of the resin having a polycyclic structure with a functional group reacting with an amino group and the amino group of the compound having an amino group in a solvent.

The first varnish of the present invention can also be referred to as a varnish comprising a resin component having a structure represented by the following formula (1).

≪ Formula 1 >

Wherein R < ¹ > is a residue of a compound having an amino group. The compound having an amino group will be described later.

The second varnish of the present invention is a varnish obtained by reacting at least a functional group of a resin having a functional group reactive with a phenolic hydroxyl group and containing a polycyclic structure and a phenolic hydroxyl group of a compound having a phenolic hydroxyl group in a solvent, to be. Compounds having a phenolic hydroxyl group will be described later.

In the present specification, the term " a resin having a functional group reactive with an amino group and having a polycyclic structure " and a " resin having a functional group reactive with a phenolic hydroxyl group and containing a polycyclic structure " Containing resin ".

The first varnish and the second varnish (hereinafter, simply referred to as the " varnish of the present invention ") of the present invention can be obtained by reacting a resin containing a polycyclic structure with a compound having an amino group or a compound having a phenolic hydroxyl group It is dispersed in a solvent and then subjected to a reaction by heating or the like to improve the solvent solubility of a resin containing a polycyclic structure to enable long-term storage. Further, since there is no need to contain an additive or the like for increasing solubility, deterioration of the properties of the resin is small, and the property retention is excellent.

Hereinafter, the varnish of the present invention will be described in detail.

(A resin containing a polycyclic structure)

The "polycyclic structure" of the resin having a polycyclic structure according to the present invention means a structure in which aromatic rings are bonded through a single bond or a structure in which aromatic rings are condensed.

Examples of structures in which aromatic rings are bonded through a single bond include biphenyl structures, biphenyl novolac structures, terphenyl structures, and the like.

Examples of the structure in which the aromatic ring is condensed include a naphthalene structure, a naphthalene novolac structure, an anthracene structure, a dihydroanthracene structure, a phenanthrene structure, a tetracene structure, a chrysene structure, a triphenylene structure, Pyrene structure, picene structure, and perylene structure.

Any of the above structures may be used alone or in combination of two or more. A biphenyl structure, a biphenyl novolak structure, a naphthalene structure, a naphthalene novolac structure, an anthracene structure, and a naphthalene structure in terms of characteristics (thermal expansion, heat resistance, etc.) of a laminate, a printed wiring board and a mounting substrate made using the varnish of the present invention A dihydroanthracene structure and the like are preferable, and a biphenyl structure, a biphenyl novolac structure, a naphthalene structure, an anthracene structure and a dihydroanthracene structure are more preferable. These are preferable because they have the feature that it is possible to easily express stacking because the steric structure is fixed.

A resin containing a polycyclic structure is preferably a thermosetting resin in view of heat resistance and dimensional stability after curing. Examples of the thermosetting resin include an epoxy resin and a cyanate resin, but an epoxy resin is preferable in terms of productivity and handleability.

In the case of an epoxy resin, the functional group which reacts with the amino group and the functional group which reacts with the phenolic hydroxyl group are epoxy groups.

Of the above epoxy resins, naphthalene novolak type epoxy resins and biphenyl novolac type epoxy resins are preferable from the viewpoint of moldability, and naphthalene type epoxy resins, anthracene type epoxy resins and dihydroanthracene type epoxy resins are preferable from the viewpoint of low thermal expansion properties Do. These may be used alone or in combination of two or more. However, in order to exhibit these performances, it is preferable to use them in a total amount of 30 mass% or more with respect to the total amount of the epoxy resin, more preferably 50 mass% or more.

Specific examples of preferred epoxy resins are shown below.

As the biphenyl novolak type epoxy resin, an epoxy resin represented by the following general formula (3) is preferable. As the epoxy resin having the structure represented by the general formula (3), for example, NC-3000 (manufactured by Nippon Kayaku Kabushiki Kaisha) is available as a commercial product.

In the formula, R ⁴ to R ⁷ are the same or different and each represents hydrogen or an alkyl group. Also, n is a number satisfying n > 0, preferably 1.5 < = n < = 4.0.

As the naphthalene novolak type epoxy resin, an epoxy resin having a structure represented by the following formula (4) is preferable. As the epoxy resin having the structure represented by the general formula (4), for example, ESN-175 (manufactured by Tokto Kasei Kabushiki Kaisha) is available as a commercial product.

In the formula, m is a number satisfying m > 0, preferably 2 m 7.

As the dihydroanthracene-type epoxy resin, an epoxy resin having a structure represented by the following formula (5) is preferable. As the epoxy resin having the structure represented by the general formula (5), for example, YX-8800 (manufactured by Japan Epoxy Resin Co., Ltd.) is available as a commercial product.

In the formula, R ⁸ and R ⁹ are the same or different and each represents an alkyl group having 4 or less carbon atoms. x represents an integer of 0 to 4, and y represents an integer of 0 to 6)

As the anthracene-type epoxy resin, an epoxy resin having a structure represented by the following formula (6) is preferable.

In the formulas, R ¹⁴ to R ¹⁷ are the same as R ⁴ to R ⁷ in the general formula (3).

(Compound having an amino group)

The compound having an amino group according to the present invention may have at least one amino group in the molecule, for example, " the equivalent of a compound having an amino group ": the " epoxy equivalent of an epoxy resin having a polycyclic structure & Is preferably 60 ° C or more and 200 ° C or less, more preferably 70 ° C or more and 190 ° C or less, and particularly preferably 80 ° C or more and 180 ° C or less. If the temperature is within the range of the exothermic initiation temperature, the curing reaction at room temperature does not progress rapidly, and storage stability (storage stability) is improved.

Measurement of the heat generation starting temperature can be performed by DSC (differential scanning calorimetry) measurement. Specifically, it can be found from the point (point A in FIG. 2) at which the curve rises in FIG. 2 (DSC curve obtained by performing the equilibrium ratio of YX-8800 and dicyandiamide at an equivalent ratio of 1: 1).

Examples of the compound having an amino group include guanamine such as benzoguanamine, acetoguanamine and spiroguanamine, guanamine resins derived therefrom, dicyandiamide, melamine or a melamine resin derived therefrom, triethylene Tetramine, aminotriazineinovolak resin, and the like. The molecular weight of these compounds is preferably 60 or more, more preferably 80 or more. With such a molecular weight, when a compound having an amino group is bonded and reacted with a resin containing a polycyclic structure, the resin containing the polycyclic structure becomes bulky enough to prevent alignment and crystallization. In addition, compounds having various kinds of amino groups may be used in combination. Of these, benzoguanamine, dicyandiamide, and aminotriazinoporphol resin are preferable from the standpoint of thermal expansion, heat resistance, reliability, etc. after laminated sheet molding.

Examples of the residue of the compound having an amino group represented by R ¹ in the formula (1) include residues of the above-exemplified resins or compounds.

(A compound having a phenolic hydroxyl group)

The compound having a phenolic hydroxyl group used in the present invention may have at least one hydroxyl group in the molecule, and more preferably two or more hydroxyl groups in terms of crosslinking. Examples thereof include naphthalene diol, phenol novolak resin, cresol novolak resin, bisphenol A type novolak resin, aminotriazine novolak resin, bismaleimide-containing aminotriazine novolak resin, bisphenol A and bisphenol F. Among them, phenol novolac resin and cresol novolak resin are preferable. The molecular weight of these compounds is not particularly limited, and several kinds of them may be used in combination.

Here, the exothermic onset temperature when the "epoxy equivalent of the epoxy resin having a polycyclic structure" is 1: 1 is preferably 60 ° C. or more and 200 ° C. or less, more preferably 70 ° C. or less More preferably not less than 190 ° C, and particularly preferably not less than 80 ° C but not more than 180 ° C. If the temperature is within the range of the exothermic initiation temperature, the curing reaction at room temperature does not progress rapidly, and storage stability (storage stability) is improved.

When a compound having a phenolic hydroxyl group is used, a curing accelerator described later is used in combination.

Further, the compound having a phenolic hydroxyl group can be used in combination with a compound having an amino group in the reaction in a solvent. In this case, the amount of the compound having a phenolic hydroxyl group is preferably 0.01 to 100 equivalents, more preferably 0.03 to 30 equivalents based on 1 equivalent of the compound having an amino group. 0.05 to 20 equivalents, the compound having a phenolic hydroxyl group and the compound having an amino group can be efficiently reacted with the thermosetting resin.

Here, it is preferable that the exothermic initiation temperature when the "epoxy equivalent of epoxy resin having a polycyclic structure" = 1: 1 is equal to or higher than 60 ° C. and equal to or lower than 200 ° C. More preferably 70 ° C or more and 190 ° C or less, and particularly preferably 80 ° C or more and 180 ° C or less. If the temperature is within the range of the exothermic initiation temperature, the curing reaction at room temperature does not progress rapidly, and storage stability (storage stability) is improved.

(A resin component having a structure represented by the general formula (1)

The resin component having the structure represented by the formula (1) according to the present invention can be obtained by reacting an epoxy resin having the above polycyclic structure with a compound having an amino group in a solvent. Specifically, a resin component having a structure represented by the formula (1) can be obtained by reacting at least part of the epoxy group of the epoxy resin with the amino group of the compound having an amino group.

Examples of the structure represented by the formula (1) of the present invention are shown below.

First, the resin component obtained from a compound having a biphenyl novolak type epoxy resin and an amino group represented by the general formula (3) has a structure represented by the following general formula (7).

In the formula, R ¹ is the same as in the formula (1). o is a number satisfying o > 0, and p is a number satisfying p >

The resin component obtained from the compound having the amino group and the naphthalene novolak type epoxy resin represented by the general formula (4) has a structure represented by the following general formula (8).

Wherein q is a number satisfying q > 0, and r is a number satisfying r >

The resin component obtained from the compound having the amino group and the dihydroanthracene epoxy resin represented by the general formula (5) includes those having a structure represented by the following general formula (9).

Wherein, R ⁸ and R ^9, x and y are the same as R ⁸ and R ^9, x and y in the formula (5).

In the varnish of the present invention, the presence ratio of the resin component represented by the formula (1) is preferably 40% or less with respect to the sum of the respective abundance ratios of the structure represented by the formula (1) and the structure represented by the formula Or more and 40% or less. Further, it is more preferably 8% or more and 40% or less, and particularly preferably 10% or more and 35% or less.

40% or less, a compound having an amino group added by denaturation prevents molecules of an epoxy resin having a polycyclic structure from aligning and crystallizing, whereby a varnish having excellent storage stability without recrystallization can be obtained.

On the other hand, if it exceeds 40%, there is a possibility that the curing reaction proceeds and the storage stability becomes insufficient.

(2)

In the present invention, the ratio of the epoxy resin having a polycyclic structure to the compound having an amino group and / or the compound having a phenolic hydroxyl group is preferably such that the ratio of the amino group equivalent and / Or the hydroxyl equivalent of the phenolic hydroxyl group is preferably in the range of 0.05 to 20, more preferably in the range of 0.10 to 10, and particularly preferably in the range of 0.20 to 5. When the epoxy equivalent is 0.05 to 20 based on the epoxy equivalent of the epoxy resin, the dissolution effect of the epoxy resin having a polycyclic structure does not become insufficient and the handling property is good. Further, in the above-mentioned range, when the abundance ratios of the formulas (1) and (2) are already within the above-mentioned range, it is possible to shorten the synthesis time and improve the storage stability.

In addition, the varnish of the present invention may contain the structure of the following formula (10) in the resin component.

(10), the ratio of the proportion of the structure represented by the formula (1), the proportion of the structure represented by the formula (2), and the proportion of the structure represented by the formula (10) The sum of the abundance ratios of the structures represented by formulas (1) and (10) is preferably 40% or less, more preferably 1% or more and 40% or less. Further, it is more preferably 5% or more and 35% or less, and particularly preferably 10% or more and 30% or less.

40% or less, a compound having an amino group added by denaturation prevents a molecule of an epoxy resin having a polycyclic structure from being aligned and crystallized, and a varnish having excellent storage stability without recrystallization can be obtained.

On the other hand, if it exceeds 40%, there is a possibility that the curing reaction proceeds and the storage stability becomes insufficient.

Further, by adjusting the equivalent ratio of the epoxy group: the curing agent to the reactor to 0.8 to 1.2, and setting the varnish, the properties after curing are improved.

In order to mix an epoxy resin having a polycyclic structure with a compound having an amino group and / or a compound having a phenolic hydroxyl group, it is preferable to add a solvent.

The solvent may be any solvent as long as a resin composition containing no solvent can be dissolved by reacting an epoxy resin having a polycyclic structure with a compound having an amino group and a compound having a phenolic hydroxyl group. In particular, acetone, methyl ethyl ketone, methyl butyl ketone , Toluene, xylene, ethyl acetate, N, N-dimethylformamide, N, N-dimethylacetamide, ethanol, ethylene glycol monomethyl ether and propylene glycol monomethyl ether acetate are preferable because of their excellent solubility. In particular, propylene glycol monomethyl ether is preferable in that it is possible to dissolve a resin having a high crystallinity.

The amount of these solvents may be any amount as long as a resin composition containing no solvent obtained by reacting an epoxy resin having a polycyclic structure with a compound having an amino group and a compound having a phenolic hydroxyl group is soluble, Is preferably in the range of 5 to 300 parts by mass, more preferably in the range of 30 to 200 parts by mass based on 100 parts by mass of the total amount of the resin component reacted with the resin and the compound having an amino group and the compound having a phenolic hydroxyl group. The above-mentioned solvents may be used in combination.

The weight average molecular weight of the resin component after the reaction according to the present invention is preferably from 800 to 4000, more preferably from 900 to 3500, and still more preferably from 950 to 3,000. The weight average molecular weight of the compound in varnish can be measured from, for example, GPC (measurement using a calibration curve of standard polystyrene by gel permeation chromatography). When the weight average molecular weight of the compound in the varnish is in the above range, the solubility of the resin including the polycyclic structure is improved without causing crystal precipitation, and the varnish becomes a good handleability.

The varnish of the present invention may contain a resin or a curing agent as required in the above components. Examples of the curing agent include acid anhydrides such as maleic anhydride and maleic anhydride copolymer, phenol compounds such as phenol novolak, cresol novolak, and aminotriazinobolak resin, and the like, . Any one kind of the curing agent may be used alone, or two or more kinds of curing agents may be used in combination.

The varnish of the present invention may contain a curing accelerator in the production of a laminated board. Examples of the curing accelerator include imidazoles and derivatives thereof, tertiary amines and quaternary ammonium salts and the like.

In the varnish of the present invention, other components may be blended if necessary insofar as the effect of the present invention is not impaired.

Examples of the other components include organic phosphorus flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, silicon flame retardants, flame retardants such as metal hydroxides, silicone fillers, nylon powders, organic fillers such as fluorine powders, Silicone-based, fluorine-based, and high-molecular antifoaming agents or leveling agents, adhesion-imparting agents such as imidazole-based, thiazole-based, triazole-based and silane-based coupling agents, ultraviolet absorbers such as benzotriazole-based, oxidizing agents such as hindered phenolics and styrenated phenols A photopolymerization initiator such as a benzophenone, a benzoquaternium, a thioxanthone and the like, a fluorescent brightener such as a stilbene derivative, a coloring agent such as phthalocyanine blue, phthalocyanine green, iodine green, disazo yellow, .

For imparting a low thermal expansion coefficient or flame retardancy, an inorganic filler or an additive may be added within a range not hindering the effect of the present invention. As the inorganic filler, silica, alumina, aluminum hydroxide, calcium carbonate, clay, talc, silicon nitride, boron nitride, titanium oxide, barium titanate, lead titanate, strontium titanate and the like can be used. This blending amount is preferably 300 parts by mass or less, preferably 200 parts by mass or less, based on 100 parts by mass of the total amount of the resin component not containing the solvent of the present invention, And also good handling properties are obtained.

Particularly, when a resin containing a polycyclic structure according to the present invention is used, the inorganic filler becomes a "crystal nucleus" for promoting crystallization, so care must be taken when a large amount of the inorganic filler is blended. As the additive, various silane coupling agents, curing accelerators, antifoaming agents and the like can be used. This blending amount is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, with respect to 100 parts by mass of the total amount of the resin component not containing a solvent, from the viewpoint of maintaining the properties of the resin composition. In order to uniformly disperse the inorganic filler, it is effective to use a pulverizer, a homogenizer, or the like.

The reaction of the resin containing a polycyclic structure according to the present invention with a compound having an amino group and / or a compound having a phenolic hydroxyl group is preferably carried out at a temperature of 80 ° C or higher and 250 ° C or lower, more preferably 85 ° C or higher and 245 ° C or lower And more preferably 90 ° C or more and 240 ° C or less.

The reaction time is preferably from 10 minutes to 30 hours, more preferably from 30 minutes to 20 hours, even more preferably from 1 hour to 15 hours.

By performing the reaction in these ranges, the presence ratio of the resin component represented by the formula (1), the resin component represented by the formula (1) and the presence ratio of the structure represented by the formula (9) can be adjusted.

The varnish of the present invention can be preferably used to form an organic insulating layer in the production of a multilayer printed wiring board and a package substrate. The varnish of the present invention can be applied to a circuit board to form an insulating layer, but industrially, it is preferably used in the form of a sheet-like laminated material such as an adhesive film or a prepreg.

[2] prepreg, resin-attached film, metal foil-clad laminate, printed wiring board:

In the resin-coated film of the present invention, the varnish of the present invention is applied (coated) to a support film, the solvent in the varnish is volatilized by drying, and the resin composition layer is formed by semi-curing (B staging). Further, a protective film may be appropriately provided on the resin composition layer.

The state of semi-curing is a range in which the adhesiveness of the substrate on which the resin composition layer and the conductor wiring are formed is ensured and the filling property (fluidity) of the substrate on which the conductor wiring is formed is secured when the varnish is cured .

As the coating method (coating machine), a die coater, a comer coater, a bar coater, a kiss coater, a roll coater, or the like can be used. As the drying method, heating or hot air spraying can be used.

The drying conditions are not particularly limited, but the drying is carried out so that the content of the organic solvent in the resin composition layer is usually 10 mass% or less, preferably 5 mass% or less. The resin composition layer is formed by drying a varnish containing, for example, 30 to 60 mass% of an organic solvent at 50 to 150 캜 for 3 to 10 minutes, depending on the amount of the organic solvent in the varnish and the boiling point of the organic solvent. Preferably, the drying conditions are suitably set in advance by a simple experiment.

The thickness of the resin composition layer formed in the resin-attached film is usually set to be not less than the thickness of the conductor layer. The thickness of the conductor layer included in the circuit board is preferably 5 to 70 탆, more preferably 3 to 50 탆, and most preferably 5 to 30 탆 for the light-weight shortening of the printed wiring board. Therefore, it is preferable that the thickness of the resin composition layer is 5% or more thicker than the thickness of such a conductor layer.

The support film in the present invention may be a film made of a polyolefin such as polyethylene, polypropylene, polyvinyl chloride or the like, a polyester such as polyethylene terephthalate (hereinafter may be abbreviated as " PET ") or polyethylene naphthalate, a polycarbonate, A metal foil such as an aluminum foil, a copper foil, and an aluminum foil.

The support film and the protective film to be described later may be subjected to a mold releasing treatment in addition to the mud treatment and the corona treatment.

The thickness of the support film is not particularly limited, but a protective film corresponding to the support film may be further laminated on the surface of the resin composition layer having a thickness of 10 to 150 탆, more preferably 25 to 50 탆, .

The thickness of the protective film is not particularly limited, but is, for example, 1 to 40 탆. By laminating a protective film, foreign matter can be prevented from being mixed. The resin-attached film may be rolled up and stored.

As a method of producing the printed wiring board (multilayer printed wiring board) of the present invention using the resin-attached film of the present invention, for example, a resin-attached film is laminated on one side or both sides of a circuit board using a vacuum laminator do.

Examples of the substrate used for the circuit board include a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, and a thermosetting polyphenylene ether substrate.

The term " circuit board " as used herein refers to a conductor wiring (circuit) formed on one side or both sides of the substrate as described above. Also, in the multilayer printed circuit board in which the conductor layer and the resin composition layer are alternately laminated, it is also included in the circuit board mentioned that one or both sides of the outermost layer of the multilayer printed wiring board is a conductor wiring (circuit). The surface of the conductor wiring layer may be previously subjected to a roughening treatment by blackening treatment or the like.

When a conductor layer is formed on at least one surface of the resin-coated film, the laminate is a metal foil-clad laminate.

In the laminate, if the resin-attached film has a protective film, the protective film is removed, and if necessary, the resin-attached film and the circuit board are preheated, and the resin-attached film is pressed and heated on the circuit board while being pressed and heated . In the present invention, a method of laminating a circuit board under reduced pressure by a vacuum laminating method is preferably used.

The lamination conditions are not particularly limited. For example, the lamination temperature is preferably 70 to 140 占 폚, the pressing pressure is preferably 0.1 to 1.1 MPa, and the air pressure is 20 mmHg (26.7 hPa) Lt; / RTI > The method of lamination may also be batch or continuous in rolls.

When the resin-attached film is laminated on a circuit board and then cooled to a temperature near room temperature, the support film is peeled off, and the resin composition layer can be formed on the circuit board by heat-curing. The conditions of the thermosetting may be appropriately selected depending on the type and content of the resin component in the resin composition, and preferably 20 to 180 minutes at 150 to 220 占 폚, more preferably 30 to 200 占 폚 at 160 to 200 占 폚, 120 minutes.

If the support film is not peeled off before the resin composition layer is formed, it is peeled off here. Then, if necessary, the resin composition layer formed on the circuit board is perforated to form via holes and through holes. The perforation can be carried out by a known method such as drilling, laser, plasma or the like, or by combining these methods as necessary. However, boring by a laser such as a carbon dioxide gas laser or a YAG laser is the most common method.

Subsequently, a conductor layer is formed on the resin composition layer by dry plating or wet plating. As the dry plating, known methods such as vapor deposition, sputtering, and ion plating can be used. In the case of wet plating, first, the surface of the cured resin composition layer is treated with an oxidizing agent such as permanganate (potassium permanganate, sodium permanganate, etc.), dichromate, ozone, hydrogen peroxide / sulfuric acid, nitric acid, do. As the oxidizing agent, an aqueous solution of sodium hydroxide (alkaline permanganic acid aqueous solution) such as potassium permanganate, sodium permanganate or the like is preferably used. Subsequently, a conductive layer is formed by a combination of electroless plating and electrolytic plating. Further, a conductive layer may be formed only by electroless plating by forming a plating resist having an inverse pattern as the conductor layer. Thereafter, as a method for forming a conductor wiring, for example, a known subtractive method, a semi-additive method, or the like can be used.

The prepreg of the present invention is produced by impregnating the varnish of the present invention to a sheet-like reinforcing base material made of fibers by a solvent method, and then heating it to B stage. That is, the varnish of the present invention can be a prepreg impregnated with a sheet-like reinforcing base material made of fibers.

As the sheet-like reinforcing base material made of fibers, for example, a well-known one used in a laminate for various electric insulating materials can be used. Examples of the material include inorganic fibers such as E glass, D glass, S glass and Q glass, organic fibers such as polyimide, polyester and polytetrafluoroethylene, and mixtures thereof.

These materials have shapes such as woven fabric, nonwoven fabric, roving, wadded strand mat, and surfacing mat, but the material and shape are selected depending on the intended use and performance of the intended molded product, The above materials and shapes can be combined. The thickness of the substrate is not particularly limited, and for example, about 0.03 to 0.5 mm can be used, and the surface treated with a silane coupling agent or the like is preferably subjected to carding treatment in terms of heat resistance, moisture resistance and workability .

The solvent method is a method in which the sheet-like reinforcing base material is immersed in the varnish of the present invention, the varnish is impregnated in the sheet-like reinforcing base material, and then dried.

Next, as a method for producing a multilayer printed wiring board using the prepreg produced as described above, for example, a prepreg of the present invention may be stacked on a circuit board, or if necessary, Sandwiched by metal plates, and press laminated under pressure and heating conditions. The pressing and heating conditions are preferably a pressure of 0.5 to 4 MPa and a temperature of 120 to 200 DEG C for 20 to 100 minutes. Further, similarly to the resin film, it is also possible to laminate the prepreg on the circuit board by the vacuum lamination method, followed by heating and curing. Thereafter, similarly to the above-described method, the surface of the cured prepreg is roughened, and then the conductor layer is formed by plating to produce a multilayer printed wiring board.

[Example]

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited thereto.

Example 1

200 g of a dihydroanthracene-type epoxy resin (trade name: YX-8800, manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent: 174 to 183) was added to a four-aperture separable flask equipped with a thermometer, 13.8 g of benzoguanamine (manufactured by Nihon Shokubai Kabushiki Kaisha) as a cresol novolac resin (trade name: KA-1165, manufactured by Dainippon Ink and Chemicals, Inc.), 13.8 g as a compound having a phenolic hydroxyl group and 170.2 g of propylene glycol monomethyl ether acetate as a solvent (manufactured by KANTO CHEMICAL Co., Ltd.), and the mixture was heated and stirred at 140 占 폚. After confirming dissolution of the material, it was further heated for 10 minutes, and 1 g of the varnish was taken. The weight average molecular weight before the reaction in terms of polystyrene was measured using high performance liquid chromatography (column: TSK-gel G-3000H manufactured by Tosoh Corporation) Respectively. After reacting for 5 hours while maintaining the temperature at 140 캜, 1 g of the varnish was taken and the weight average molecular weight in terms of polystyrene was determined by high performance liquid chromatography. Then, 92.0 g of a cresol novolak resin (KA-1165, trade name, manufactured by Dainippon Ink and Chemicals, Incorporated) was added and dissolved by heating at 100 占 폚 for 30 minutes to prepare a varnish.

One milliliter of the varnish thus prepared was used, and it was confirmed by particle gauge that there was no particle having a particle diameter of 5 mu m or more, and then it was stored at 5 DEG C, and the time for the material to precipitate from the varnish was visually confirmed. When precipitation of the material was confirmed, 1 ml of the varnish was taken and the presence or absence of particles having a particle diameter of 5 탆 or more was examined using a particle gauge. The time until the particles having a diameter of 5 탆 or more was identified as the storage time.

Example 2

, 27.6 g of benzoguanamine (manufactured by Nippon Shokubai Kabushiki Kaisha), 22.6 g of cresol novolak resin (KA-1165, trade name, manufactured by Dainippon Ink and Chemicals, Incorporated), 0.35 g of propylene glycol monomethyl ether (KA-1165, trade name, manufactured by Dainippon Ink and Chemicals, Incorporated) was added in an amount of 162.8 g, and the amount of the cresol novolak resin added after the reaction was changed to 56.3 g. , A varnish was prepared and the storage time was determined.

Example 3

(Trade name: KA-1165, manufactured by Dainippon Ink and Chemicals, Incorporated) as a compound having a phenolic hydroxyl group as a compound having an amino group and a melamine (manufactured by KANTO CHEMICAL Co., Ltd.) (KA-1165, trade name, manufactured by Dainippon Ink and Chemicals, Incorporated), 26.2 g of propylene glycol monomethyl ether acetate (manufactured by KANTO CHEMICAL Co., Ltd.), 172.2 g of propylene glycol monomethyl ether acetate Was changed to 46.0 g, a varnish was prepared in the same manner as in Example 1, and the storage time was determined.

Example 4

11.6 g of dicyandiamide (manufactured by Kanto Chemical Co., Ltd.) as a compound having an amino group and 118.8 g of propylene glycol monomethyl ether acetate as a solvent (manufactured by Kanto Chemical Co., Ltd.) were added after the reaction A varnish was prepared in the same manner as in Example 1 except that 65.8 g of cresol novolak resin (KA-1165, trade name, manufactured by Dainippon Ink and Chemicals, Incorporated) was used and the reaction time at 140 ° C was changed to 3 hours , And storage time.

Example 5

, 2.4 g of dicyandiamide (manufactured by Kanto Chemical Industry Co., Ltd.), 26.2 g of cresol novolak resin (trade name: KA-1165, manufactured by Dainippon Ink and Chemicals Inc.), 0.35 g of propylene glycol monomethyl ether acetate (KA-1165, trade name, manufactured by Dainippon Ink and Chemicals, Inc.) was changed to 46.0 g, which was added after the reaction and 137.4 g of the cresol novolak resin (KA-1165, manufactured by KANTO KAGAKU CHEMICAL INDUSTRIES, In the same manner, a varnish was prepared and the storage time was obtained.

Example 6

, 200 g of a naphthalene novolak type epoxy resin (trade name: ESN-175, epoxy equivalent: 254, manufactured by Tokto Chemicals Co., Ltd.) as an epoxy resin, 3.3 g of dicyandiamide (manufactured by Kanto Kagaku Co., Ltd.) 24.8 g of a phenol novolac resin (trade name: TD-2090, manufactured by Dainippon Ink and Chemicals, Inc.) as a compound, and 115.5 g of propylene glycol monomethyl ether acetate (manufactured by Kanto Kagaku Kabushiki Kaisha) g, 41.3 g of a phenol novolac resin (TD-2090, trade name, manufactured by Dainippon Ink and Chemicals, Inc.) added after the reaction, and the storage time at 140 ° C was changed to 3 hours. Varnishes were made and the storage time was determined.

Example 7

76.8 g of a biphenyl novolak type epoxy resin (trade name: NC-3000-H manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 284 to 294) in addition to the dihydroanthracene epoxy resin as the epoxy resin, (Trade name: KA-1165, manufactured by Dainippon Ink and Chemicals, Inc.) as a compound having a phenolic hydroxyl group and 62.6 g of triazinoborac (trade name: LA3018-50P, manufactured by DIC Co., (KA-1165, manufactured by Dainippon Ink and Chemicals, Incorporated), 14.8 g of propylene glycol monomethyl ether acetate (manufactured by KANTO CHEMICAL Co., Ltd.), 230.5 g of propylene glycol monomethyl ether acetate Manufactured by Kuraray Co., Ltd.) was changed to 124.9 g, the reaction temperature was set to 120 ° C, and the holding time was changed to 14 hours. A varnish was prepared in the same manner as in Example 1, It was.

Example 8

76.8 g of a biphenyl novolak type epoxy resin (trade name: NC-3000-H, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 284 to 294) in addition to the dihydroanthracene epoxy resin as the epoxy resin, , 3.8 g of anthiamide (manufactured by Kanto Chemical Co., Ltd.) and 18.1 g of cresol novolak resin (trade name: KA-1165, manufactured by Dainippon Ink and Chemicals Inc.) as a compound having a phenolic hydroxyl group, 113.0 g of propylene glycol monomethyl ether acetate (manufactured by KANTO CHEMICAL Co., Ltd.), 124.9 g of cresol novolak resin (KA-1165, trade name, manufactured by Dainippon Ink and Chemicals, Incorporated) A varnish was prepared in the same manner as in Example 1 except that the amount of propylene glycol monomethyl ether acetate (manufactured by Kanto Kagaku Kabushiki Kaisha) was changed to 115.1 g, The tube was nine hours.

Example 9

200.5 g of a biphenyl novolak type epoxy resin (trade name: NC-3000-H, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 284 to 294) as a dicarboxylic acid type epoxy resin as the epoxy resin, , 3.9 g of anthiamide (manufactured by Kanto Chemical Co., Ltd.) and 197.2 g of a cresol novolak resin (trade name: KA-1165, manufactured by Dainippon Ink and Chemicals Inc.) as a compound having a phenolic hydroxyl group, Except that 161.6 g of propylene glycol monomethyl ether acetate (manufactured by Kanto Chemical Co., Ltd.) and 164.7 g of propylene glycol monomethyl ether acetate (produced by Kanto Chemical Co., Ltd.) added after the reaction were used A varnish was produced in the same manner as in Example 1. And the storage time was obtained.

Comparative Example 1

200 g of a dihydroanthracene epoxy resin (trade name: YX-8800, manufactured by Japan Epoxy Resin Co., Ltd.), and 200 g of benzoguanamine (manufactured by Nippon Kayaku Co., Ltd.) as a compound having an amino group were added to a 4-opening separable flask equipped with a stirrer, (KA-1165, trade name, manufactured by Dainippon Ink and Chemicals, Inc.) as a compound having a phenolic hydroxyl group, 105.2 g of propylene glycol monomethyl as a solvent as a solvent (trade name, manufactured by Nihon Shokubai Kabushiki Gaika Co., Ltd.) 170.2 g of ether acetate (manufactured by KANTO CHEMICAL Co., Ltd.) was added and dissolved by heating at 140 DEG C to prepare a varnish.

One milliliter of the varnish thus prepared was used, and it was confirmed by particle gauge that there was no particle having a particle diameter of 5 mu m or more, and then it was stored at 5 DEG C, and the time for the material to precipitate from the varnish was visually confirmed. When precipitation of the material was confirmed, 1 ml of the varnish was taken and the presence or absence of particles having a particle diameter of 5 탆 or more was examined using a particle gauge. The time until the particles having a diameter of 5 탆 or more was identified as the storage time.

Comparative Example 2

, 27.6 g of benzoguanamine (manufactured by Nippon Shokubai Kabushiki Gaika Co., Ltd.), 78.9 g of cresol novolac resin (KA-1165, trade name, manufactured by Dainippon Ink and Chemicals, Inc.), and propylene glycol monomethyl ether acetate Manufactured by KANTO CHEMICAL CO., LTD.) Was changed to 162.8 g, a varnish was prepared in the same manner as in Comparative Example 1, and the storage time was obtained.

Comparative Example 3

, 4.6 g of melamine (manufactured by KANTO CHEMICAL Co., Ltd.) as a compound having an amino group, 72.2 g of a cresol novolak resin (KA-1165, trade name, manufactured by Dainippon Ink and Chemicals, Incorporated) Acetate (manufactured by KANTO CHEMICAL Co., Ltd.) was changed to 172.2 g, and the storage time was obtained.

Comparative Example 4

, 11.6 g of dicyandiamide (manufactured by Kanto Chemical Co., Ltd.), 65.8 g of cresol novolac resin (KA-1165, trade name, manufactured by Dainippon Ink and Chemicals, Inc.) and propylene glycol monomethyl ether acetate (Manufactured by KANTO CHEMICAL Co., Ltd.) was changed to 118.8 g, and the storage time was obtained.

Comparative Example 5

, 2.4 g of dicyandiamide (manufactured by KANTO CHEMICAL Co., Ltd.) as a compound having an amino group, 72.2 g of a cresol novolak resin (KA-1165, trade name of Dainippon Ink and Chemicals, Incorporated) A varnish was prepared in the same manner as in Comparative Example 1 except that the amount of the solvent was changed to 137.4 g of methyl ether acetate (manufactured by Kanto Kagaku Kabushiki Kaisha), and the storage time was determined.

Comparative Example 6

, 200 g of a naphthalene novolak type epoxy resin (ESN-175, trade name, manufactured by Tokushu Kika Kogyo Co., Ltd.) as an epoxy resin, 3.3 g of dicyandiamide as a compound having an amino group (manufactured by Kanto Kagaku Kabushiki Kaisha) 65.0 g of a phenol novolac resin (TD-2090, trade name, manufactured by Dainippon Ink and Chemicals, Inc.) as a compound and 115.5 g of propylene glycol monomethyl ether acetate (manufactured by Kanto Kagaku Kabushiki Kaisha) , A varnish was produced in the same manner as in Comparative Example 1, and the storage time was determined.

Comparative Example 7

76.8 g of a biphenyl novolak type epoxy resin (trade name: NC-3000-H manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 284 to 294) in addition to the dihydroanthracene epoxy resin as the epoxy resin, (Trade name: KA-1165, manufactured by Dainippon Ink and Chemicals, Inc.) as a compound having a phenolic hydroxyl group and 62.6 g of triazinoborac (trade name: LA3018-50P, manufactured by DIC Co., Ltd.) and 230.5 g of propylene glycol monomethyl ether acetate (manufactured by Kanto Kagaku Kabushiki Kaisha) were used in place of the propylene glycol monomethyl ether acetate (manufactured by Kanto Chemical Co., Ltd.), and the storage time was determined.

Comparative Example 8

76.8 g of a biphenyl novolak type epoxy resin (trade name: NC-3000-H, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 284 to 294) in addition to the dihydroanthracene epoxy resin as the epoxy resin, , 3.8 g of anthiamide (manufactured by Kanto Chemical Co., Ltd.) and 143.0 g of a cresol novolak resin (trade name: KA-1165, manufactured by Dainippon Ink and Chemicals Inc.) as a compound having a phenolic hydroxyl group, A varnish was prepared in the same manner as in Comparative Example 1 except that the amount of propylene glycol monomethyl ether acetate (manufactured by Kanto Kagaku Kabushiki Kaisha) was changed to 228.1 g, and the storage time was determined.

Comparative Example 9

200.5 g of a biphenyl novolak type epoxy resin (trade name: NC-3000-H, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 284 to 294) as a dicarboxylic acid type epoxy resin as the epoxy resin, , 3.9 g of anthiamide (manufactured by Kanto Chemical Co., Ltd.) and 197.2 g of a cresol novolak resin (trade name: KA-1165, manufactured by Dainippon Ink and Chemicals Inc.) as a compound having a phenolic hydroxyl group, A varnish was prepared in the same manner as in Comparative Example 1 except that 326.3 g of propylene glycol monomethyl ether acetate (manufactured by KANTO CHEMICAL Co., Ltd.) was used. And the storage time was obtained.

The results of measurement of the weight average molecular weight and storage time of the varnish prepared in the examples are shown in Table 1 below. The results of measurement of the storage time of the varnish prepared in the comparative example are shown in Table 2 below.

The storage time of Comparative Examples 1 to 6 in Table 2 is as short as 2 to 5 hours, whereas the storage time of Examples 1 to 6 of Table 1 has a storage time of 168 hours or more, i.e., one week or more. Epoxy resins including polycyclic structures shown in Examples and Comparative Examples are called crystalline epoxy resins and have low solubility in solvents. Therefore, even if the temperature of the varnish is increased to the melting point of the epoxy resin or more and melted, the resin is precipitated in a short time when returned to room temperature. On the other hand, in Examples 1 to 6, it is possible to achieve a storage time of 30 times or more of the comparative example under the storage condition of 5 占 폚 by reacting some functional groups of the epoxy resin. Therefore, it can be seen that it is important to react a part of the functional groups of the epoxy resin including the polycyclic structure in securing the storage time. Unlike the prior art, the varnish of the present embodiment can improve the solubility, thereby achieving stabilization of the varnish and preserving the varnish for a long period of time. Thus, the workability is excellent and the storage stability is high.

In addition, since the copper clad laminate produced by using the varnish of the embodiment has a low coefficient of thermal expansion, it can be said that occurrence of warpage, which has been a conventional problem, can be suppressed even in the case of a printed wiring board.

10: Semiconductor chip
12: Seal material (semiconductor package)
14: Bonding wire
16: Semiconductor package substrate
18: substrate
20: Through hole
22: solder ball
C: Crack generated by warping

Claims (16)

A resin component having a structure represented by the following formula (1), obtained by reacting a part of the functional group of the resin having a polycyclic structure with a functional group reactive with an amino group and the amino group of the compound having an amino group in a solvent, , Stored at 5 占 폚, and stored for at least 1 week until particles having particle diameters of 5 占 퐉 or more are identified.
≪ Formula 1 >

(Wherein R < ¹ > is a residue of a compound having an amino group) The varnish according to claim 1, wherein the phenolic hydroxyl group of the compound having a phenolic hydroxyl group and a part of the functional group of the resin having a polycyclic structure and having a functional group reactive with the phenolic hydroxyl group are reacted in the solvent. 3. The varnish according to claim 1 or 2, wherein the compound having an amino group is any one of guanamine, dicyandiamide and aminotriazineinovolak. In a solvent, a part of the functional group of the resin having a polycyclic structure and having a functional group reacting with the phenolic hydroxyl group, and the phenolic hydroxyl group of the compound having a phenolic hydroxyl group, And stored at 5 占 폚, and a storage time of one week or more before particles having a diameter of 5 占 퐉 or more are identified.
≪ Formula 10 >

The varnish according to claim 2 or 4, wherein the compound having a phenolic hydroxyl group is a phenol novolac resin or a cresol novolak resin. The varnish according to any one of claims 1 to 4, wherein the resin contains at least one epoxy group as the functional group. The varnish according to claim 1 or 4, wherein the resin has at least one selected from the group consisting of a biphenyl structure, a naphthalene structure, a biphenyl novolak structure, an anthracene structure and a dihydroanthracene structure. A varnish according to any one of claims 1 to 3, wherein the ratio of the proportion of the structure represented by the formula (1) and the structure represented by the formula (2) to the sum of the abundance ratio of the structure represented by the formula .
(2)

A prepreg obtained by applying the varnish according to any one of claims 1 to 4 to a substrate and heating and drying the varnish. The prepreg according to claim 9, wherein the substrate is a glass woven fabric, a glass nonwoven fabric, an aramid woven fabric or an aramid nonwoven fabric. A resin-coated film obtained by applying the varnish according to any one of claims 1 to 4 to a film, followed by heating and drying. A metal foil-clad laminate having a conductor layer on at least one surface of a prepreg according to claim 9. A metal foil-clad laminate having a conductor layer on at least one side of the resin-coated film according to claim 11. A printed wiring board comprising the conductor layer provided on at least one surface of the metal foil-clad laminate according to claim 12. A printed wiring board comprising a conductor layer provided on at least one surface of a metal foil-clad laminate according to claim 13. delete

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