JP2003231763A - Prepreg and metal foil-clad laminated sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high density printed-wiring material excellent in resistance to migration and in electric insulating properties. <P>SOLUTION: A prepreg is obtained by employing, as a reinforcing base material for a thermosetting resin, a glass cloth prime-coated with a gelation resin, which is obtained by impregnating or coating a glass cloth, treated with a coupling agent and subjected to a physical opening treatment, with a thermosetting resin previously diluted with an organic solvent and subsequently heating and drying it. A laminated sheet for a printed-wiring material and a metal foil-clad laminated sheet are obtained by curing the prepreg. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepreg and a laminate of printed wiring material for electrical insulating material. The laminate obtained by curing the prepreg of the present invention is excellent in migration resistance and electric insulation and is suitable for high density printed wiring material applications.

[0002]

As a printed wiring material for electronic devices,
A prepreg obtained by impregnating a glass cloth with a thermosetting resin such as an epoxy resin type or a BT (bismaleimide-triazine) resin type and heating and drying, a laminated plate obtained by heat curing the prepreg, the laminated plate and the prepreg. Heat-cured multilayer boards in combination with prepregs are widely used. In recent years, with the progress of downsizing of electronic devices, the demand for higher density of printed wiring boards is increasing rapidly, and along with this, it is indispensable to improve the reliability of migration resistance and electrical insulation.

Conventionally, as a method for improving migration resistance and electric insulation in a printed wiring board, reduction of ionic impurities of thermosetting resin used, combined use of antioxidant, special glass cloth surface treatment agent Although its use has been proposed, its application to high-density printed wiring materials is limited, and further improvement is required.

[0004]

At present, in order to increase the density of printed wiring materials, in double-sided printed wiring boards, the wiring patterns and through holes can be made thinner or thinner, and multilayer printed wiring can be obtained. On the board,
Inner via holes (IVH), blind via holes (BVH), etc. are used, but the intervals between lines, through holes, IVH, and BVH inevitably tend to become shorter, and migration resistance and electrical resistance of printed wiring materials are unavoidable. There is an urgent need for further improvement of insulation. An object of the present invention is to provide a high density printed wiring material excellent in migration resistance and electric insulation.

[0005]

DISCLOSURE OF THE INVENTION As a result of analyzing the cause of deterioration of migration resistance of a multilayer board, the inventors of the present invention form the multilayer board on the matte surface of the copper foil of the multilayer board or the inner copper foil circuit surface. It has been found that when the fiber bundle of the glass cloth is in direct contact, the insulation resistance is likely to deteriorate, and as a result of studying a method of suppressing this, a low concentration thermosetting resin (B) was previously prepared. A laminated plate obtained from a prepreg obtained by using a glass cloth in which the thermosetting resin (B) has penetrated into the fiber bundle of the glass cloth by being undercoated, as a reinforcing base material of the thermosetting resin (D), In multilayer boards, migration resistance and electrical insulation are greatly improved by reducing the possibility that the fiber bundle of glass cloth directly contacts the matte surface of copper foil and the circuit surface of the inner copper foil. And found the present invention This has led to the formation.

That is, according to the present invention, a glass cloth (A) which has been surface-treated with at least one or more coupling agents and which has been physically opened is a thermosetting resin (B) previously diluted with an organic solvent. ) Is used as a reinforcing base material for a thermosetting resin (D), and a prepreg, and a gelling resin undercoat glass cloth (C) obtained by impregnating or coating A laminated board for a printed wiring material obtained by curing the above, and a metal foil-clad laminated board.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As the glass cloth (A) used in the present invention, it is possible to use well-known ones used for various printed wiring materials. As the material and style of the glass cloth (A), known materials and styles used for various electric insulating materials can be used. Specific examples of the material include E glass, S glass, D
Glass, NE glass, quartz, etc. are mentioned. Regarding the style, a yarn obtained by bundling several tens to several thousands of filaments with a diameter of several μm to several tens of μm is plain weave, twill weave, satin weave, twill weave, etc. The glass cloth processed into the above is exemplified, and the material and style are appropriately selected according to the intended use and performance of the molded product, and if necessary, one kind or two or more kinds of materials and styles are appropriately combined and used. It is also possible. The thickness of the glass cloth (A) is not particularly limited, but is usually about 0.01 to 0.3 mm, and a range of 0.015 to 0.1 mm is preferably used.

Regarding the glass cloth (A) of the present invention,
A surface treatment agent such as a silane coupling agent has been subjected to a coupling treatment. These surface treatment agents are well known and are not particularly limited as long as they are generally used. Typical examples of the coupling agent include organosilane-based aminosilane-based compounds such as γ-aminopropyltriethoxyxylan and N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, and γ-glycidoxypropyltrimethylene. Epoxy silanes such as toshixylan, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, vinylsilanes such as γ-methacryloxypropyltrimethoxysilane, vinyltri (β-methoxyethoxy) silane, N-β- ( N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxyxylan hydrochloride and other cationic silane-based, phenylsilane-based, and the like are exemplified, and titanate-based and aluminum-based are also listed. One or more kinds It is also possible to use a suitable combination.

Further, the glass cloth (A) of the present invention has been subjected to a physical fiber opening treatment, and the method of the fiber opening treatment is a method generally used by glass cloth makers. There is no particular limitation. Specifically, ultrasonic processing, high-pressure water processing, mechanical processing, etc. are exemplified.

The thermosetting resin (B) used in the present invention is not particularly limited as long as it is a thermosetting resin used for printed wiring materials. As a typical example of the thermosetting resin (B), an epoxy resin,
Examples thereof include a cyanate ester resin, a bismaleimide-cyanate ester resin, a maleimide resin, and the like, and it is possible to use one kind or a suitable combination of two or more kinds according to the purpose. Suitable examples include thermosetting resins containing an epoxy resin or a cyanate ester resin as an essential component.

If desired, the thermosetting resin (B) used in the present invention may be used in combination with a curing agent or curing accelerator for the thermosetting resin (B). These are well known and are not particularly limited as long as they are commonly used as a curing agent and a curing accelerator for the thermosetting resin (B).

The cyanate ester resin which is a preferred embodiment of the thermosetting resin (B) of the present invention is not particularly limited as long as it is a compound having two or more cyanate groups in one molecule. . Specific examples thereof include 1,3- or 1,4-dicyanate benzene, 1,3,5-tricyanate benzene,
1,3-, 1,4-, 1,6-, 1,8-, 2,6- or 2,7-dicyanate naphthalene, 1,3,6-tricyanate naphthalene, 4,4'-dicyanate Biphenyl, bis (4-dicyanatephenyl)
Methane, 2,2-bis (4-cyanatephenyl) propane, 4,
4'-methylene bis (2,6 dimethyl phenyl cyanate), bis (4-cyanate phenyl) ether, bis (4-cyanate phenyl) thioether, bis (4-cyanate phenyl) sulfone, tris (4-cyanate phenyl) phosphite, Reaction of tris (4-cyanatephenyl) phosphate, tetramethylbiphenylcyanate, hexamethylbiphenylcyanate; novolac, phosphorus-containing novolac, hydroxyl group-containing thermoplastic oligomers (eg hydroxypolyphenylene ether, hydroxypolystyrene) with cyanogen halide Cyanates and the like obtained by the method described above can be used, and it is also possible to use one kind or two kinds or more as appropriate.

Further, a prepolymer having a weight average molecular weight of 500 to 5000 and having a triazine ring formed by trimerization of cyanate groups of these cyanate ester compounds is preferably used. The prepolymer is produced by polymerizing the above cyanate ester monomer with a catalyst such as an acid such as a mineral acid or a Lewis acid; a salt such as sodium alcoholate, a salt such as a tertiary amine, or a salt such as sodium carbonate. Is obtained by

The epoxy resin which is another preferred embodiment of the thermosetting resin (B) of the present invention is not particularly limited as long as it is a compound having two or more epoxy groups in one molecule. . Specific examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, polyfunctional phenol type epoxy resin,
Halogenated bisphenol A type epoxy resin, halogenated phenol novolac type epoxy resin, phosphorus-containing epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, polyol type epoxy resin, alicyclic epoxy resin; epoxy double bond such as butadiene Examples thereof include polyepoxy compounds that have been modified, polyglycidyl compounds obtained by the reaction of hydroxyl group-containing silicone resins with epichlorohydrin, and one kind or a mixture of two or more kinds can be used as appropriate.

To the thermosetting resin (B) of the present invention, various compounds (for example, a flexible additive, an organic flame retardant, various additives) may be added, if desired, within a range in which desired properties are not impaired. It is also possible to mix the agent). These are well known and are not particularly limited as long as they are commonly used.

As the kind of the organic solvent used in the present invention, as long as it is compatible with the thermosetting resin (B),
Although not particularly limited, ketone-based organic solvents such as acetone and methyl ethyl ketone are preferable. The gelled resin undercoat glass cloth (C) is obtained by a method of impregnating or coating the glass cloth (A) with the thermosetting resin (B) diluted with an organic solvent and heating and drying.

Gelation of the thermosetting resin (B) in the present invention is a state different from curing, and specifically, a state in which the resin does not exhibit fluidity when heated on a hot plate. The so-called B stage and C stage are located in the middle.

When the undercoat resin is in the B stage state, when the glass cloth is impregnated with the thermosetting resin (D) and applied, the undercoat resin is dissolved or peeled off, and in the C stage state, The affinity between the undercoat resin and the thermosetting resin (D) may decrease, and the thermal history of the final product such as a laminated board or a multilayer board may cause thermal deterioration of the undercoat resin. It does not meet the purpose of the invention.

Of the gelling resin undercoat glass cloth (C),
The amount of the undercoat (resin) of the thermosetting resin (B) varies depending on the type and molecular weight of the resin used, but is usually 1 to 20 wt%
And more preferably in the range of 3 to 15 wt%.
If the amount of the undercoat (resin) is less than 1% by weight, the amount of the resin is small enough to allow the thermosetting resin (B) to penetrate into the yarn bundle of the glass fiber. Since the concentration of the thermosetting resin (B) becomes high, it becomes difficult to sufficiently permeate the thermosetting resin (B) into the yarn bundle of glass fibers, which does not meet the object of the present invention.

The undercoating amount of the gelling resin undercoat glass cloth (C) of the present invention is the same as the resin amount of a normal prepreg (40
The content of the thermosetting resin varnish during coating is significantly low, and as a result, the thermosetting resin (B) is a fiber bundle of glass fiber of the glass cloth (A). It is possible to fully penetrate.

Laminates and multilayer boards obtained from a prepreg obtained by using the undercoated glass cloth (C) as a reinforcing base material for a thermosetting resin (D) are thermoset up to a yarn bundle of glass cloth fibers. Since the resin (B) has sufficiently penetrated, the possibility that the fiber bundle of the glass cloth directly contacts the matte surface of the copper foil or the inner copper foil circuit surface is greatly reduced.

On the other hand, in a normal prepreg, since the thermosetting resin varnish at the time of coating has a high viscosity, it is difficult for the thermosetting resin to sufficiently penetrate into the yarn bundle of the glass fiber, and the thermosetting resin is partially dispersed. Since a fiber bundle of impregnated glass fiber occurs in this area, the case where the mat surface of the copper foil and the inner layer copper foil circuit surface are likely to come into direct contact with each other easily occurs, and in the migration resistance test, the thermosetting resin is A short circuit is reached via the yarn bundle of impervious glass fibers.

The type of the thermosetting resin (B) can be used in the same system as the thermosetting resin (D) used when finally semi-curing to prepare a prepreg or in a different system,
It is also preferable to surface-treat the gelling resin undercoat glass cloth (C) with a silane coupling agent or the like.

The thermosetting resin (D) used in the present invention is not particularly limited as long as it is a thermosetting resin used for an electric insulating material, and is basically the above-mentioned. It is similar to the thermosetting resin (B). Various compounds may be blended with the thermosetting resin (D) of the present invention, if desired, as long as the desired properties are not impaired. These are not particularly limited as long as they are well known and generally used. Typical examples of the compound include polymerizable double bond-containing monomers such as unsaturated polyester and prepolymers thereof, polybutadiene,
Epoxidized butadiene, maleated butadiene, butadiene-acrylonitrile copolymer, polychloroprene,
Low molecular weight liquid to high molecular weight elastomers such as butadiene-styrene copolymer, polyisoprene, styrene-isoprene rubber, butyl rubber, fluororubber and natural rubber,
Polyethylene, polypropylene, polybutene, poly-4-
Methyl pentene, polystyrene, AS resin, ABS resin, MBS resin, polyethylene-propylene copolymer, 4
-Fluorinated ethylene-6-fluorinated ethylene copolymers; polycarbonate, polyphenylene ether, polysulfone,
Polyester, high molecular weight prepolymer or oligomer such as polyphenylene sulfide, polyurethane,
Examples include silicone compounds and the like, and it is possible to use one kind or a mixture of two or more kinds as appropriate. If necessary, in the case of a compound having a reactive group, a curing agent or a curing accelerator is appropriately blended. .

The thermosetting resin (D) of the present invention may be used in combination with a flame retardant, a filler, an additive, etc., as long as the desired characteristics are not impaired. These are well known,
There is no particular limitation as long as it is commonly used. As flame retardants, hydrates such as aluminum hydroxide and magnesium hydroxide, molybdenum compounds such as molybdenum oxide and zinc molybdate, inorganic substances such as zinc borate and zinc stannate, phosphoric acid esters and phosphorus such as melamine phosphate. Compounds, nitrogen-containing compounds such as melamine and benzoguanamine modified, etc., as the filler, natural silica, pyrogenic silica, amorphous silica, white carbon, titanium white, aerosil, kaolin, clay, talc,
Examples include calcined kaolin, calcined clay, calcined talc, wollastonite, natural mica, synthetic mica, magnesia, alumina, perlite, short glass fibers, glass fine powder, hollow glass, and other additives such as benzotriazole. UV absorbers, antioxidants such as hindered phenols and styrenated phenols, photopolymerization initiators such as thioxanthone, fluorescent whitening agents such as stilbene derivatives, photosensitizers, dyes, pigments, thickeners, lubricants, An antifoaming agent, a dispersant, a leveling agent, a brightening agent, a polymerization inhibitor, a thixotropy imparting agent and the like can be used in an appropriate combination as desired.

After the thermosetting resin (D) is impregnated or applied to the gelling resin undercoat glass cloth (C) of the present invention, it is usually dried in a dryer at 100 to 200 ° C. for 1 to 3 times.
The prepreg of the present invention is manufactured by semi-curing (B-stage) by a method of heating for 0 minutes. At this time, an organic solvent is used if necessary, but the type thereof is not particularly limited as long as it is compatible with the thermosetting resin (D). Representative examples thereof include acetone, methyl ethyl ketone, methyl cellosolve, propylene glycol methyl ether and its acetate, toluene, xylene, dimethylformamide and the like. It is also possible to use alone or in admixture of two or more kinds.

The total amount of the thermosetting resin {(B) + (D)} with respect to the glass cloth (A) is the resin content in the prepreg stage, and is in the range of 25 to 85% by weight, preferably 30 to 85% by weight. It is in the range of 80% by weight.

The metal foil-clad laminate of the present invention is a laminate formed by using the prepreg of the present invention described above. Specifically, one or more sheets of the prepreg of the present invention are appropriately laminated, and if desired, a metal foil such as copper or aluminum is arranged on one side or both sides of the prepreg, and the laminate is molded. The metal foil used is not particularly limited as long as it is used for electric insulating materials.

As a molding condition, a usual method for a laminated plate for an electric insulating material and a multi-layered plate can be applied. For example, using a multi-stage press, multi-stage vacuum press, continuous molding, autoclave molding machine, etc., temperature: 100 to 280 ° C., pressure: 2 to
It is generally 100 kg / cm ² , heating time: 0.05 to 5 hours. Also, a multilayer board can be manufactured by combining the prepreg of the present invention and a wiring board for an inner layer, which is separately prepared, and laminating and molding. Below are examples,
The present invention will be described in detail by showing a comparative example.

[0030]

Example 1 30 parts by weight of a prepolymer of 2,2-bis (4-cyanatephenyl) propane (BT2070, manufactured by Mitsubishi Gas Chemical),
Cresol novolac epoxy resin (ESCN220
H, manufactured by Sumitomo Chemical Co., Ltd.), and after dissolving 30 parts by weight of brominated bisphenol A type epoxy resin (Epiclon 153, manufactured by Dainippon Ink) in methyl ethyl ketone,
Mix 0.02 parts by weight of zinc octylate and mix with varnish (a-
1) was obtained. This varnish (a-1) was diluted with methyl ethyl ketone, impregnated and coated on E glass cloth having a thickness of 0.1 mm, dried by heating at 170 ° C. for 6 minutes, and the resin amount was 6% by weight.
A gelling resin undercoat glass cloth (a-2) of was obtained.

This resin-undercoated glass cloth (a-2) was sandwiched between release films and pressed at 170 ° C. and a pressure of 10 kg / cm ² , but no resin flow was observed and a gelled state was reached. This gelled resin undercoat glass cloth (a-
In 2), the varnish (a-1) was diluted with methyl ethyl ketone, impregnated, and dried by heating at 150 ° C. for 6 minutes to obtain a prepreg having a total resin amount of 44% by weight. Next, four sheets of this prepreg were stacked, and 18 μm electrolytic copper foils were placed on the top and bottom, and pressed at a pressure of 30 kg / cm ² and a temperature of 200 ° C. for 120 minutes to obtain a copper-clad laminate having a thickness of 0.4 mm. It was

Example 2 25 parts by weight of 2,2-bis (4-cyanatephenyl) propane and 5 parts by weight of bis (4-maleimidophenyl) methane were added to 1 part.
After reacting at 50 ° C. for 4 hours to perform prepolymerization,
Dissolved in a mixed solvent of methyl ethyl ketone and dimethylformamide, and brominated phenol novolac epoxy resin (BREN-S, manufactured by Nippon Kayaku) 40 parts by weight, cresol novolac epoxy resin (ESCN220H).
30 parts by weight and 0.02 parts by weight of zinc octylate were mixed to obtain a varnish (b-1).

This varnish (b-1) was diluted with methyl ethyl ketone, impregnated and coated on an E glass cloth having a thickness of 0.1 mm, and dried by heating at 160 ° C. for 6 minutes to give a gelled resin having a resin amount of 13% by weight. An undercoat glass cloth (b-2) was obtained.
This resin-undercoated glass cloth (b-2) was sandwiched between release films and pressed at 170 ° C. and a pressure of 10 kg / cm ² ,
No resin flow was observed, and a gelled state was reached.

This gelled resin undercoat glass cloth (b-
2) was immersed in a water-methanol solution of a silane coupling agent (Silane A187, manufactured by Nippon Unicar) and dried by heating to obtain a gelling resin undercoat glass cloth (b-3) surface-treated with the silane coupling agent. . The varnish (b-1) was diluted with methyl ethyl ketone to the gelling resin undercoat glass cloth (b-3) surface-treated with this silane coupling agent, impregnated and coated, and then heat-dried at 140 ° C. for 6 minutes to make a total. A prepreg having a resin amount of 44% by weight was obtained. next,
Four of these prepregs were stacked and in the same manner as in Example 1, a copper clad laminate having a thickness of 0.4 mm was obtained.

Example 3 Bisphenol A type epoxy resin (Epicoat 828,
54 parts by weight of Japan Epoxy), 18 parts by weight of phenol novolac resin (TD-2093, made by Dainippon Ink), Tetrabrom Bisphenol A (frame cut 1)
(20R, manufactured by Tosoh) 28 parts by weight was dissolved in methyl ethyl ketone and then 2-ethyl-4-methylimidazole 0.0
5 parts by weight were mixed to obtain a varnish (c-1). This varnish (c-1) was diluted with methyl ethyl ketone to a thickness of 0.
A 1 mm E glass cloth was impregnated and dried by heating at 160 ° C. for 6 minutes to obtain a gelled resin undercoat glass cloth (c-2) having a resin amount of 11% by weight.

The resin-undercoated glass cloth (c-2) was sandwiched between release films and pressed at 170 ° C. and a pressure of 10 kg / cm ² , but no resin flow was observed and the gelled state was reached. This gelling resin undercoat glass cloth (c-
In 2), the varnish (c-1) was diluted with methyl ethyl ketone, impregnated, and dried by heating at 140 ° C. for 6 minutes to obtain a prepreg having a total resin amount of 43% by weight. Next, 4 sheets of this prepreg are stacked, and 18 μm electrolytic copper foils are arranged on the top and bottom,
Pressing was performed for 120 minutes at a pressure of 30 kg / cm ² and a temperature of 180 ° C. to obtain a copper-clad laminate having a thickness of 0.4 mm.

Example 4 The gelling resin-undercoated glass cloth (a) obtained in Example 1
-2), the varnish (c-1) obtained in Example 3 was diluted with methyl ethyl ketone, impregnated and dried by heating at 140 ° C for 6 minutes to obtain a prepreg having a total resin amount of 43% by weight. . Next, four of these prepregs were stacked and a copper clad laminate having a thickness of 0.4 mm was obtained in the same manner as in Example 3.

Comparative Example 1 The varnish (b-1) obtained in Example 2 was diluted with methyl ethyl ketone, impregnated and coated on E glass cloth having a thickness of 0.1 mm, and dried by heating at 180 ° C. for 12 minutes, A C-staged resin undercoat glass cloth having a resin amount of 15% by weight was obtained. The C-staged resin undercoat glass cloth was immersed in a water-methanol solution of a silane coupling agent (silane A187) and heated and dried to obtain a C-staged resin undercoat glass cloth surface-treated with the silane coupling agent.

A C-staged resin undercoat glass cloth surface-treated with this silane coupling agent was added to the varnish (b
-1) is diluted with methyl ethyl ketone, impregnated and coated, 1
It was heated and dried at 40 ° C. for 6 minutes to obtain a prepreg having a total resin amount of 43% by weight. Next, stack 4 sheets of this prepreg,
A copper-clad laminate having a thickness of 0.4 mm was obtained in the same manner as in Example 1.

Comparative Example 2 The varnish (c-1) obtained in Example 3 was diluted with methyl ethyl ketone, impregnated and coated on E glass cloth having a thickness of 0.1 mm, and dried by heating at 150 ° C. for 6 minutes. A prepreg having a resin amount of 43% by weight was obtained. Next, four of these prepregs were stacked and a copper clad laminate having a thickness of 0.4 mm was obtained in the same manner as in Example 3.

Results of physical property evaluation

[Table 1]

Test method {insulation resistance} Treatment condition: 121 ° C. pressure cooker condition Measurement method: According to JIS C6481. {Migration resistance} Evaluation pattern: Drill diameter 0.35 mm, through hole wall spacing 0.3 mm, through hole 30 pairs.・ Treatment conditions: 85 ° C., 85% RH, 100 V applied ・ Judgment criteria: Insulation resistance is less than 10 ⁸ Ω.

[0043]

According to the present invention, a glass cloth which has been surface-treated with at least one or more coupling agents and which has been physically opened is preliminarily coated with a thermosetting resin in a gelled state. Laminates for printed wiring materials obtained by curing a prepreg that uses a gelling resin undercoat glass cloth as a reinforcing base material for thermosetting resin, and metal foil-clad laminates have migration resistance and electrical insulation. Its excellent properties make it ideal for high-density printed wiring materials.
The industrial practicality is extremely high.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F072 AA04 AA07 AB09 AB28 AC06                       AC08 AC12 AD11 AD23 AG03                       AH02 AH31 AJ04 AK05 AK14                       AL12                 4F100 AB01A AG00B AK01B BA02                       DG12B EH46B EJ67B EJ82B                       GB43 JB13B JG04

Claims (5)

[Claims] 1. A thermosetting resin (B) preliminarily diluted with an organic solvent to a glass cloth (A) which has been surface-treated with at least one coupling agent and which has been physically opened.
A prepreg characterized by using a gelling resin undercoat glass cloth (C) obtained by impregnating or coating with, and heating and drying as a reinforcing base material for a thermosetting resin (D). 2. A gelling resin undercoat glass cloth (C),
Undercoat (resin) amount of thermosetting resin (B) is 1 to 20 wt.
The prepreg according to claim 1, wherein the prepreg is%. 3. A gelling resin undercoat glass cloth (C) comprises:
The prepreg according to claim 1 or 2, which is surface-treated with at least one coupling agent. 4. The prepreg according to claim 3, wherein the thermosetting resin (B) contains a cyanate ester resin or an epoxy resin as an essential component. 5. A laminate for a printed wiring material, which is obtained by curing the prepreg according to claim 1, and a metal foil-clad laminate.