JP6623640B2 - Prepreg - Google Patents

Description

  The present invention relates to a prepreg.

  2. Description of the Related Art In recent years, data communication used in information communication has been rapidly increased in speed and capacity. Therefore, there is a demand for a printed wiring board that achieves both high frequency characteristics and multi-layered wiring in the above electronic devices.

  Printed wiring boards used for information communication are required to have a low dielectric constant (low Dk) and a low dielectric loss tangent (low Df) in order to reduce signal propagation delay and reduce transmission loss. In order to fulfill these requirements, a resin material containing polyphenylene ether is used as an insulating layer between multi-layered wirings in a printed wiring board. Polyphenylene ether is a compound that has excellent electrical properties (low dielectric constant and low dielectric loss tangent) and is expected to be effective in increasing transmission speed and reducing transmission loss. Attempts have been made to apply a prepreg laminate using this polyphenylene ether to a printed wiring board in order to improve the performance and multilayer the printed wiring board. Examples of such a prepreg are disclosed in Patent Documents 1 and 2.

JP 2006-516297 A International Publication No. 2009/041137

  By the way, when a prepreg and a copper pattern are laminated to obtain a copper-clad laminate, it is necessary that the prepreg can be filled with the prepreg so that voids do not occur between the copper patterns. The prepreg is required to have such a formability that it can be filled between the patterns. However, in the prepregs disclosed in Patent Literature 1 and Patent Literature 2, the minimum melt viscosity is large, and thus the moldability cannot be sufficiently obtained.

  An object of the present invention is to improve the moldability of a prepreg by lowering the viscosity.

A prepreg according to an embodiment of the present invention includes a polyphenylene ether resin composition containing polyphenylene ether and a cross-linking curing agent, wherein the polyphenylene ether has a general formula (1)
And the number average molecular weight is 1,000 or more and 7000 or less. In the general formula (1), X represents an aryl group, (Y) _m represents a polyphenylene ether moiety, and R ¹ , R ² , and R ³ Each independently represents a hydrogen atom, an alkyl group, an alkenyl group or an alkynyl group, m represents an integer of 1 to 100, n represents an integer of 1 to 6, q represents an integer of 1 to 4, and The melt viscosity is 50,000 Pa · s or less.

  The prepreg according to one embodiment of the present invention has a number average molecular weight of 1000 or less, an epoxy compound containing no halogen atom having at least two epoxy groups in one molecule, a polyphenylene ether having a number average molecular weight of 5000 or less, a cyanate ester. A thermosetting resin composition comprising a compound, a curing catalyst for accelerating the reaction of the epoxy compound and the polyphenylene ether with the cyanate ester compound as a curing agent, and a resin varnish containing a halogen-based flame retardant. The melt viscosity is 50,000 Pa · s or less.

  A filler containing silica dispersed in the polyphenylene ether resin composition may be included.

  The number average molecular weight of the polyphenylene ether may be 3000 or less.

  The dielectric loss tangent Df of the polyphenylene ether resin composition may be 0.007 or less at 10 GHz.

  According to the present invention, the moldability of the prepreg can be improved by lowering the viscosity.

<Embodiment 1>
Hereinafter, the prepreg according to the present invention will be described in detail. However, the prepreg of the present invention is not construed as being limited to the description of the following embodiments and examples.

[Structure of prepreg]
The prepreg according to the first embodiment of the present invention includes a resin composition containing polyphenylene ether and a crosslinkable curing agent, and a base material.

(Polyphenylene ether)
The polyphenylene ether contained in the resin composition of the present invention is represented by the above general formula (1) and may have a number average molecular weight of 1,000 to 7000.

In the above general formula (1), X represents an aryl group, (Y) _m represents a polyphenylene ether moiety, and R ^{1 to} R ³ each represent a hydrogen atom, an alkyl group, an alkenyl group or an alkynyl group. In the general formula (1), n is an integer of 1 or more and 6 or less, and q is an integer of 1 or more and 4 or less. Here, preferably, n is an integer of 1 or more and 4 or less, more preferably, n is 1 or 2, and ideally, n is 1. Preferably, q is an integer of 1 to 3, and more preferably, q is 1 or 2, and ideally, q is 1.

(Aryl group)
As the aryl group in the general formula (1), an aromatic hydrocarbon group can be used. Specifically, a phenyl group, a biphenyl group, an indenyl group, and a naphthyl group can be used as the aryl group, and an aryl group is preferably used. Here, the aryl group includes a diphenyl ether group or the like in which the above aryl group is bonded with an oxygen atom, a benzophenone group or the like bonded with a carbonyl group, and a 2,2-diphenylpropane group or the like bonded with an alkylene group. May be. Further, the aryl group may be substituted by a general substituent such as an alkyl group (preferably a C ₁ -C ₆ alkyl group, particularly a methyl group), an alkenyl group, an alkynyl group and a halogen atom. However, since the "aryl group" is substituted by a polyphenylene ether moiety via an oxygen atom, the limit on the number of general substituents depends on the number of polyphenylene ether moieties.

(Polyphenylene ether part)
The polyphenylene ether moiety in the general formula (1) is represented by the following general formula (2) and comprises a phenyloxy repeating unit. Here, the phenyl group may be substituted by a general substituent.

In the above general formula (2), R ^{4 to} R ⁷ each represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group or an alkenylcarbonyl group. In the general formula (2), m represents an integer of 1 to 100. Here, the value of m is adjusted so that the number average molecular weight of the polyphenylene ether of the general formula (1) is 1,000 or more and 7000 or less. That is, m is not a fixed value but may be a variable within a certain range such that the number average molecular weight of the entire polyphenylene ether contained in the polyphenylene ether resin composition is 1,000 or more and 7000 or less.

  Here, when the number average molecular weight of the polyphenylene ether exceeds 7000, the fluidity at the time of molding decreases, and multilayer molding becomes difficult. On the other hand, if the number average molecular weight of the polyphenylene ether is less than 1,000, the original excellent dielectric properties and heat resistance of the polyphenylene ether resin may not be obtained. In order to obtain better fluidity, heat resistance and dielectric properties, the number average molecular weight of the polyphenylene ether is preferably 1200 or more and 5000 or less. More preferably, the number average molecular weight of the polyphenylene ether is 1500 or more and 4500 or less, and further preferably, the number average molecular weight of the polyphenylene ether is 3000 or less.

  Further, the polyphenylene ether having the above number average molecular weight has very good compatibility when blended with a cross-linking type curing agent. In other words, the lower the number average molecular weight of polyphenylene ether, the higher the compatibility with the mixture. Therefore, viscosity increase due to phase separation hardly occurs, and volatilization of the low molecular weight cross-linking curing agent is suppressed. As a result, the filling property of the polyphenylene ether resin composition into via holes and the like can be improved.

  As the alkyl group, alkenyl group and alkynyl group in the general formula (2), those similar to the alkyl group, alkenyl group and alkynyl group in the general formula (1) described below can be used. As the alkenylcarbonyl group in the polyphenylene ether portion, a carbonyl group substituted by the above alkenyl group can be used. Specifically, an acryloyl group and a methacryloyl group can be used.

Here, the polyphenylene ether moiety in the general formula (2) is a substituent such as a vinyl group, a 2-propylene group (allyl group), a methacryloyl group, an acryloyl group, a 2-propyne group (propargyl group) as the substituents R ^{4 to} R ⁷ . It may have an unsaturated hydrocarbon-containing group. When the substituents R ^{4 to} R ⁷ of the polyphenylene ether moiety are provided with the above-mentioned unsaturated hydrocarbon-containing group, a more remarkable effect of the crosslinkable curing agent can be obtained.

  The polyphenylene ether having the above group at the terminal has a good interaction with the crosslinking type curing agent. Therefore, the heat resistance can be improved only by adding a relatively small amount of the crosslinking type curing agent, and a low dielectric constant can be realized.

(Alkyl group)
As the alkyl group in the general formulas (1) and (2), a saturated hydrocarbon group can be used. As the above alkyl group, a C ₁ -C ₁₀ alkyl group may be used. Preferably, a C ₁ -C ₆ alkyl group is used as the above alkyl group. More preferably, a C ₁ -C ₄ alkyl group may be used as the above-mentioned alkyl group. More preferably, a C ₁ -C ₂ alkyl group may be used as the above-mentioned alkyl group. Specifically, as the alkyl group, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group can be used.

(Alkenyl group)
As the alkenyl group in the general formulas (1) and (2), an unsaturated hydrocarbon group having at least one carbon-carbon double bond in the structure can be used. As the alkenyl group, a C ₂ -C ₁₀ alkenyl group may be used. Preferably, a C ₂ -C ₆ alkenyl group is used as the alkenyl group. More preferably, a C ₂ -C ₄ alkenyl group may be used as the alkenyl group. Specifically, as the alkenyl group, an ethylene group, a 1-propylene group, a 2-propylene group, an isopropylene group, a butylene group, an isobutylene group, a pentylene group, and a hexylene group can be used.

(Alkynyl group)
As the alkynyl group in the general formulas (1) and (2), an unsaturated hydrocarbon group having at least one carbon-carbon triple bond in the structure can be used. As the alkynyl group, a C ₂ -C ₁₀ alkynyl group may be used. Preferably, a C ₂ -C ₆ alkynyl group is used as the alkynyl group. More preferably, a C2-C4 alkynyl group may be used as the alkynyl group. Specifically, as the alkynyl group, an ethyne group, a 1-propyne group, a 2-propyne group, an isopropyne group, a butyne group, an isobutyne group, a pentyne group, and a hexyne group can be used.

(Cross-linking curing agent)
As the crosslinkable curing agent contained in the present resin composition, a curing agent that three-dimensionally crosslinks polyphenylene ether can be used. Specifically, a polyfunctional vinyl compound, a vinylbenzyl ether-based compound, an allyl ether-based compound, or a trialkenyl isocyanurate can be used as the crosslinkable curing agent. Polyfunctional vinyl compounds include divinylbenzene, divinylnaphthalene, and divinylbiphenyl. Vinyl benzyl ether compounds are synthesized by the reaction of phenol and vinyl benzyl chloride. The allyl ether compound is synthesized by a reaction of a styrene monomer, phenol, and allyl chloride. Trialkenyl isocyanurate has good compatibility, and triallyl isocyanurate (hereinafter, TAIC) or triallyl cyanurate (hereinafter, TAC) can be used.

  (Meth) acrylate compounds (methacrylate compounds and acrylate compounds) can be used as the cross-linking curing agent in addition to the above materials. In particular, it is preferable that a functional (meth) acrylate compound having a functionality of 3 or more and 5 or less be contained in an amount of 3 to 20 mass% based on the total amount of the resin composition. As the methacrylate compound having a functionality of 3 or more and 5 or less, trimethylolpropane trimethacrylate (TMPT) can be used. On the other hand, as the acrylate compound having a functionality of 3 or more and 5 or less, trimethylolpropane triacrylate or the like can be used. Can be. By using the above-mentioned crosslinking type curing agent, the heat resistance of the resin composition can be further improved.

  When the functionality of the (meth) acrylate compound is less than 3 or more than 5, the heat resistance is lower than that of a (meth) acrylate compound having a functionality of 3 or more and 5 or less. In addition, even when the (meth) acrylate compound has a functionality of 3 or more and 5 or less, if the content is less than 3% by mass based on the total amount of the present resin composition, the effect of improving the heat resistance of the present resin composition is sufficient. Can not get to. On the other hand, if it exceeds 20% by mass, the dielectric properties and the moisture resistance will decrease.

  The content ratio of the polyphenylene ether to the crosslinking type curing agent in the present resin composition is preferably 30/70 or more and 90/10 or less. Preferably, the content ratio is 50/50 or more and 90/10 or less. More preferably, the above content ratio is set to be 60/40 or more and 90/10 or less.

  Here, when the content ratio of the polyphenylene ether is smaller than the lower limit, the rigidity of the entire resin composition is reduced. Under the influence, it is difficult to form a multilayered resin composition as a whole. On the other hand, when the content ratio of the polyphenylene ether is larger than the upper limit, the heat resistance of the entire resin composition decreases. By adjusting the content ratio of the polyphenylene ether and the cross-linking type curing agent to the above range, good fluidity and compatibility of the resin composition can be obtained. Therefore, the embedding property of the resin composition into a via hole or the like can be improved.

(Base material)
The base material included in the prepreg of the present invention is, for example, a glass cloth. Note that the substrate may be formed of an organic material.

(Other additives)
The resin composition of the present invention can optionally contain one or more additives selected from unmodified polyphenylene ether, a filler of an inorganic or organic material, a flame retardant, and a reaction initiator. . Further, a general additive component of a resin composition used for manufacturing an electronic device such as a printed wiring board may be added.

(Unmodified polyphenylene ether)
In the resin composition of the present invention, an unmodified polyphenylene ether having a number average molecular weight of 9,000 or more and 18,000 or less can be added in addition to the above-mentioned polyphenylene ether. By adding unmodified polyphenylene ether, control of fluidity of the resin composition and improvement of heat resistance can be realized. Further, precipitation of additional components such as a filler in the resin composition can be suppressed. Here, the unmodified polyphenylene ether is a polyphenylene ether having no carbon-carbon unsaturated group in the molecule, and the added amount thereof is a total mass of 100 parts by mass of the polyphenylene ether and the crosslinking type curing agent. It is preferably 3 parts by mass or more and 70 parts by mass or less.

  Furthermore, in order to improve heat resistance, adhesion and dimensional stability, styrene-butadiene block copolymer, styrene-isoprene block copolymer, 1,2-polybutadiene, 1,4-polybutadiene, maleic acid-modified polybutadiene, acrylic acid-modified polybutadiene And at least one compatibilizer selected from epoxy-modified polybutadiene.

(Filling material)
By adding a filler of an inorganic material (hereinafter, referred to as an inorganic filler) to the present resin composition, the prepreg using the present resin composition can have a reduced thermal expansion coefficient and improved rigidity. Examples of the inorganic filler include silica, boron nitride, wollastonite, talc, kaolin, clay, mica, alumina, zirconia, titania, and other metal oxides, nitrides, silicides, borides, and the like. In particular, by adding a low dielectric constant filler such as silica or boron nitride, the resin composition can have a low dielectric constant.

  By adding a filler of an organic material (hereinafter referred to as an organic filler) to the present resin composition, the dielectric constant of a prepreg using the present resin composition can be reduced. As the organic filler, a fluorine-based, polystyrene-based, divinylbenzene-based, polyimide-based, or the like can be used. Examples of the fluorine-based filler (a filler containing a fluorine-containing compound) include polytetrafluoroethylene (PTFE), polyperfluoroalkoxy resin, polyfluoroethylene propylene resin, polytetrafluoroethylene-polyethylene copolymer, polyvinylidene fluoride, and poly (vinylidene fluoride). Chlorotrifluoroethylene resin or the like can be used. These can be used alone or in combination of two or more.

  In addition, hollow polymer fine particles can be used as the organic filler. In particular, by using a hollow body whose shell material is a material having a low dielectric constant such as divinylbenzene or divinyl biphenyl, the dielectric constant of the prepreg can be reduced.

  Fine particles having an average particle diameter of 10 μm or less can be used as the inorganic filler or the organic filler. The average particle size here may be a value described in a material such as a catalog of the filler to be added, or may be an average value or a median value of a plurality of randomly extracted fillers. By setting the average particle size of the filler to the above condition, a prepreg having high smoothness and high reliability can be obtained.

(Flame retardants)
By adding a flame retardant to the present resin composition, the prepreg using the present resin composition can have improved water resistance, moisture resistance, heat resistance to moisture absorption, and glass transition point. As the flame retardant, a brominated organic compound, for example, an aromatic bromine compound can be used. Specifically, decabromodiphenylethane, 4,4-dibromobiphenyl, ethylenebistetrabromophthalimide, or the like can be used. Preferably, the brominated organic compound is contained in an amount of from 8% by mass to 20% by mass with respect to the total amount of the resin composition.

  If the bromine content is lower than the lower limit, the prepreg has low flame retardancy and cannot maintain the UL standard 94V-0 level flame retardancy. On the other hand, when the content of bromine is larger than the upper limit, bromine is easily dissociated when the prepreg is heated, and the heat resistance of the prepreg decreases.

(Reaction initiator)
By adding a reaction initiator to the present resin composition, a more remarkable effect of the crosslinking type curing agent can be obtained. As the reaction initiator, a general material can be used as long as it can improve the properties such as heat resistance of the resin composition by promoting the curing of the resin composition at an appropriate temperature and time. Specifically, α, α′-bis (t-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) -3-hexyne, benzoyl peroxide , 3,3 ', 5,5'-Tetramethyl-1,4-diphenoquinone, chloranil, 2,4,6-tri-t-butylphenoxyl, t-butylperoxyisopropyl monocarbonate, azobisisobutyronitrile And the like. Here, if necessary, a metal carboxylate may be added to further promote the curing reaction.

[Prepreg manufacturing method]
A method for producing a prepreg according to the first embodiment of the present invention will be described. First, a varnish is formed by mixing a polyphenylene ether, a cross-linking curing agent, and an additive with an organic solvent. The organic solvent is not particularly limited as long as it does not dissolve the brominated organic compound but dissolves the resin component and does not adversely affect the reaction. For example, ketones such as methyl ethyl ketone, ethers such as dibutyl ether, esters such as ethyl acetate, amides such as dimethylformamide, aromatic hydrocarbons such as benzene, toluene, xylene, and chlorinated hydrocarbons such as trichloroethylene. Are used alone or in combination of two or more. The concentration of the resin solid content of the varnish may be appropriately adjusted according to the operation of impregnating the base material with the varnish, and may be, for example, from 40% by mass to 90% by mass.

  A prepreg can be obtained by impregnating the base material with the above varnish, drying by heating and removing the organic solvent and semi-curing the resin in the base material. In the prepreg according to the present invention, a glass cloth can be used as the base material.

  The amount of the varnish impregnated into the base material is preferably such that the mass ratio of the resin solid content in the prepreg is 35% by mass or more. Since the dielectric constant of the base material is higher than the dielectric constant of the resin, in order to reduce the dielectric constant of the printed wiring board obtained using this prepreg, the content of the resin solid content in the prepreg is determined by the above mass ratio. It is good to increase. The substrate impregnated with the varnish can be heated at a temperature of 80 ° C. or more and 180 ° C. or less for a time of 1 minute or more and 10 minutes or less. At this time, heating is performed so that the minimum melt viscosity of the resin composition in the prepreg becomes 50,000 Pa · s or less. For example, when heating at a temperature of 170 ° C., the heating time is preferably 3 minutes or more and less than 10 minutes, and more preferably 5 minutes or more and 9 minutes or less. The heating conditions of the substrate impregnated with the varnish are not limited to the above conditions, but are determined so that the minimum melt viscosity of the resin composition in the prepreg is 50,000 Pa · s or less. Here, the minimum melt viscosity of the resin composition in the prepreg is a minimum value of the melt viscosity of the resin composition in the prepreg in a temperature range from room temperature to 200 ° C.

  The resin composition in the prepreg thus formed preferably has a dielectric constant Dk at 10 GHz of 2.7 or less, more preferably 2.5 or less. The dielectric loss tangent Df at 10 GHz is preferably 0.007 or less, more preferably 0.005 or less.

[Manufacturing method of printed wiring board (laminate)]
Here, a method of manufacturing a laminate using the prepreg manufactured as described above will be described. First, one or a plurality of prepregs are stacked, and a metal foil such as a copper foil is stacked on both upper and lower surfaces or one surface thereof, and the laminate is heated and pressed. By this molding, a laminate (for example, a copper-clad laminate) having a metal foil on both sides or one side can be produced. A printed wiring board can be obtained by patterning and etching the metal foil of the laminate to form a circuit. Further, a multilayer printed wiring board can be manufactured by laminating a plurality of prepregs with a metal foil having a circuit formed therebetween and performing heating and press molding.

The heat and pressure molding conditions vary depending on the content ratio of the raw materials of the resin composition according to the present invention, but are generally 170 ° C. or more and 230 ° C. or less, and the pressure is 1.0 MPa or more and 6.0 MPa or less (10 kg / cm ² or more and 60 kg or less). / Cm ² or less) under the condition of heating and pressurizing for an appropriate time.

  The metal foil used in the laminate has a surface roughness (ten-point average roughness: Rz) of 2 μm or less, and has a surface on the side where the resin layer is formed by the prepreg (surface on the side in contact with the prepreg). However, it is possible to use a copper foil that has been treated with zinc or a zinc alloy in order to prevent rust and improve the adhesion to the resin layer, and that has been subjected to a coupling treatment with a vinyl group-containing silane coupling agent or the like. Such a copper foil has good adhesion to a resin layer (insulating layer), and a printed wiring board having excellent high-frequency characteristics can be obtained. When the copper foil is treated with zinc or a zinc alloy, zinc or a zinc alloy can be formed on the surface of the copper foil by a plating method.

  The laminate and the printed wiring board thus obtained can realize low Dk and low Df. Further, a laminate or a printed wiring board having high moldability, water resistance, moisture resistance, heat resistance to moisture absorption, and high glass transition point can be obtained. Particularly, when the minimum melt viscosity of the prepreg is 50,000 Pa · s or less, good moldability can be obtained.

<Embodiment 2>
Hereinafter, the prepreg according to the present invention will be described in detail. However, the prepreg of the present invention is not construed as being limited to the description of the following embodiments and examples.

[Structure of prepreg]
The prepreg according to the second embodiment of the present invention includes a resin composition including a resin varnish having an epoxy compound, a polyphenylene ether, a cyanate ester compound, a curing catalyst, and a halogen-based flame retardant, and a base material. Here, the epoxy compound has a number average molecular weight of 1000 or less and does not contain a halogen atom having at least two epoxy groups in one molecule. The polyphenylene ether has a number average molecular weight of 5000 or less. The curing catalyst promotes the reaction between the epoxy compound and polyphenylene ether and the cyanate ester compound as a curing agent.

(Epoxy compound)
As the epoxy compound, a dicyclopentadiene type epoxy compound, a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, a phenol novolak type epoxy compound, a naphthalene type epoxy compound, a biphenyl type epoxy compound and the like can be used. These can be used alone or in combination of two or more. Of the above, dicyclopentadiene type epoxy compounds, bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, and biphenyl type epoxy compounds are preferred because of their good compatibility with polyphenylene ether. The present resin composition preferably does not contain a halogenated epoxy compound, but may be added as needed as long as the effects of the present invention are not impaired.

  The content ratio of the epoxy compound in the prepreg of the present embodiment is preferably 20% by mass or more and 60% by mass or less based on the total amount of components of the epoxy compound, the polyphenylene ether, and the cyanate ester compound. More preferably, the content ratio of the epoxy compound is not less than 30% by mass and not more than 50% by mass. By setting the content of the epoxy compound in the above range, sufficient heat resistance and excellent mechanical and electrical properties can be maintained.

(Polyphenylene ether)
The polyphenylene ether has a number average molecular weight of 5000 or less, preferably 1500 or more and 4000 or less.

  If the number average molecular weight of the polyphenylene ether exceeds 5,000, the fluidity will deteriorate and the reactivity with the epoxy group will decrease. For this reason, a long time is required for the curing reaction, and unreacted ones that are not taken into the curing system increase to lower the glass transition temperature, so that a sufficient improvement in heat resistance cannot be obtained.

  The content ratio of the polyphenylene ether in the prepreg of the present embodiment is preferably 20% by mass or more and 60% by mass or less based on the total amount of the epoxy compound, the polyphenylene ether, and the cyanate ester compound. More preferably, the content ratio of the polyphenylene ether is not less than 20% by mass and not more than 40% by mass. When the content ratio of the polyphenylene ether is within the above range, excellent dielectric properties can be obtained.

(Cyanate compound)
As the cyanate ester compound, a compound having two or more cyanate groups in one molecule can be used. Specifically, 2,2-bis (4-cyanatophenyl) propane, bis (3,5-dimethyl-4-cyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) ethane, etc. Alternatively, an aromatic cyanate compound such as a derivative thereof can be used. These can be used alone or in combination of two or more.

  A cyanate ester compound is a component that acts as a curing agent for an epoxy compound to form an epoxy resin and forms a rigid skeleton. Therefore, a high glass transition point (Tg) can be obtained. In addition, high fluidity of the obtained resin varnish can be maintained because of low viscosity.

  The content of the cyanate ester compound in the prepreg of the present embodiment is preferably 20% by mass or more and 60% by mass or less based on the total amount of the epoxy compound, the polyphenylene ether, and the cyanate compound. More preferably, the content ratio of the cyanate ester compound is preferably 20% by mass or more and 40% by mass or less. When the content ratio of the cyanate ester compound is in the above range, sufficient heat resistance can be obtained, the impregnation property to the base material is excellent, and crystals can be hardly precipitated even in the resin varnish.

(Curing catalyst)
As the curing catalyst, organic metal salts such as Zn, Cu and Fe of organic acids such as octanoic acid, stearic acid, acetylacetonate, naphthenic acid and salicylic acid; tertiary amines such as triethylamine and triethanolamine; Imidazoles such as 4-imidazole and 4-methylimidazole can be used. These can be used alone or in combination of two or more. Among the above, organic metal salts, particularly zinc octoate, are preferred because higher heat resistance can be obtained.

  In the case of using an organic metal salt, for example, the content ratio of the curing catalyst in the prepreg of the present embodiment is 0.005 to the total amount (100 parts by mass) of the components of the epoxy compound, the polyphenylene ether, and the cyanate ester compound. It can be not less than 5 parts by mass and not more than 5 parts by mass. When imidazoles are used, for example, the content ratio of the curing catalyst is 0.01 to 5 parts by mass based on the total amount (100 parts by mass) of the epoxy compound, polyphenylene ether, and cyanate compound. It can be:

(Halogen flame retardant)
As the halogen-based flame retardant, a halogen-based flame retardant that does not dissolve in a varnish prepared with a solvent such as toluene can be used. Specifically, ethylene dipentabromobenzene, ethylene bistetrabromophthalimide, decabromodiphenyl oxide, tetradecabromodiphenoxybenzene, bis (tribromophenoxy) ethane, or the like can be used as the halogen-based flame retardant. Among the above, particularly ethylenedipentabromobenzene, ethylenebistetrabromophthalimide, decabromodiphenyloxide, and tetradecabromodiphenoxybenzene have a high heat resistance at a melting point of 300 ° C. or higher, and thus improve the heat resistance of the prepreg. Can be. When a halogen-based flame retardant having a melting point of 300 ° C. or higher and having high heat resistance is used, elimination of halogen at a high temperature can be suppressed, so that a decrease in heat resistance due to decomposition of a cured product can be suppressed.

  The average particle size of the halogen-based flame retardant in the dispersed state is 0.1 μm or more and 50 μm or less, more preferably 1 μm or more and 10 μm or less, so that the heat resistance and the insulation between layers can be sufficiently maintained. The above average particle diameter can be measured by a particle size distribution meter (SALD-2100) manufactured by Shimadzu Corporation.

  The content ratio of the halogen-based flame retardant in the prepreg of the present embodiment is such that the halogen concentration is 5% by mass or more and 30% by mass or less in the total amount of the resin components (that is, components excluding the inorganic components) in the obtained cured product. It is preferable to contain them in an appropriate ratio.

(Base material)
The base material included in the prepreg of the present invention is, for example, a glass cloth. Note that the substrate may be formed of an organic material.

(Filling material)
The resin composition of the present invention may optionally contain an inorganic filler. The inorganic filler can obtain the effects of improving dimensional stability during heating and improving flame retardancy. Specific examples of the inorganic filler include silica such as spherical silica, alumina, talc, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica, aluminum borate, barium sulfate, and calcium carbonate. Further, as the inorganic filler, a material which has been surface-treated with an epoxysilane type or aminosilane type silane coupling agent can be used. By containing an inorganic filler surface-treated with a silane coupling agent, it is possible to improve heat resistance during moisture absorption and adhesion between layers.

  The content ratio of the inorganic filler in the prepreg of the present embodiment is 10 parts by mass or more and 100 parts by mass or less based on the total amount (100 parts by mass) of the components of the epoxy compound, the polyphenylene ether, and the cyanate ester compound. It is good to make it contain at an appropriate ratio. Preferably, the content of the inorganic filler is preferably set to a ratio of 20 parts by mass or more and 70 parts by mass or less. More preferably, the content of the inorganic filler may be contained at a ratio of 20 parts by mass or more and 50 parts by mass or less. By setting the content of the inorganic filler in the above range, the dimensional stability can be improved without lowering the fluidity and the adhesion to the metal foil.

  The resin composition of the present invention may contain, in addition to the above-mentioned inorganic filler, a general additive component of a resin composition used for manufacturing an electronic device such as a printed wiring board. For example, heat stabilizers, antistatic agents, ultraviolet absorbers, flame retardants, dyes and pigments, lubricants and the like may be added.

[Prepreg manufacturing method]
The resin composition of the prepreg according to the second embodiment of the present invention is an epoxy compound, polyphenylene ether, and the components of the cyanate ester compound are all dissolved in the resin varnish, the component of the inorganic filler, It is not dissolved but dispersed in the resin varnish. Such a resin varnish is prepared, for example, as follows.

  First, a predetermined amount of an epoxy compound and a cyanate ester compound are dissolved in a resin solution of polyphenylene ether. This dissolution may be performed at room temperature or may be performed while heating. By using a material that dissolves in a solvent such as toluene at room temperature as the epoxy compound and the cyanate ester compound, the formation of precipitates in the resin varnish can be suppressed.

  Here, when an inorganic filler is added as an additive, a resin varnish is prepared by adding a filler and then dispersing the mixture to a predetermined dispersion state using a ball mill, a bead mill, a planetary mixer, a roll mill, or the like. Is done.

  A prepreg can be obtained by impregnating and drying the base material with the resin varnish obtained as described above in the same manufacturing method as in the first embodiment. Further, a printed wiring board (laminate) can be obtained by the same manufacturing method as in the first embodiment.

  The resin composition in the prepreg thus formed preferably has a dielectric constant Dk at 10 GHz of 2.8 or less, more preferably 2.6 or less. The dielectric loss tangent Df at 10 GHz is preferably 0.009 or less, more preferably 0.007 or less.

  Hereinafter, the prepregs according to Embodiments 1 and 2 of the present invention are manufactured, and the results of evaluating the minimum melt viscosity, the dielectric constant (Dk), the dielectric loss tangent (Df), and the moldability will be specifically described. Examples 1 to 3 shown below correspond to the examples of the first embodiment, and Examples 4 to 7 correspond to the examples of the second embodiment.

  First, the polyphenylene ether used in Examples 1 to 3 and Comparative Example 1 will be described.

(Polyphenylene ether (1))
3.88 g (17.4 mmol) of CuBr _{2 and} 0.75 g of N, N′-di-t-butylethylenediamine (4.10 g) were placed in a 12-liter vertical reactor equipped with a stirrer, a thermometer, an air introduction tube, and a baffle plate. 4 mmol), 28.04 g (277.6 mmol) of n-butyldimethylamine and 2600 g of toluene were stirred and stirred at a reaction temperature of 40 ° C., and 2,2 ′, 3,3 ′, 12,5 g (0.48 mol) of 5,5'-hexamethyl- (1,1'-biphenol) -4,4'-diol, 233.7 g (1.92 mol) of 2,6-dimethylphenol, 2,3,3 64.9 g (0.48 mol) of 6-trimethylphenol, 0.51 g (2.9 mmol) of N, N'-di-t-butylethylenediamine, n-butyldiamine A mixed solution of 10.90 g (108.0 mmol) of tylamine was dropped over 230 minutes while performing bubbling at a flow rate of 5.2 L / min with a mixed gas obtained by mixing nitrogen and air to adjust the oxygen concentration to 8%. Then, stirring was performed.

  After completion of the dropwise addition, 1500 g of water in which 19.89 g (52.3 mmol) of tetrasodium ethylenediaminetetraacetate was dissolved was added to stop the reaction. The aqueous layer and the organic layer were separated, and the organic layer was washed with a 1N aqueous hydrochloric acid solution and then with pure water. The obtained solution was concentrated to 50 wt% by an evaporator to obtain 836.5 g of a toluene solution of a bifunctional phenylene ether oligomer (resin “A”). The resin “A” had a number average molecular weight of 986, a weight average molecular weight of 1,530, and a hydroxyl equivalent of 471.

  In a reactor equipped with a stirrer, a thermometer, and a reflux tube, 836.5 g of a toluene solution of the resin “A”, 162.6 g of vinylbenzyl chloride (trade name: CMS-P; manufactured by Seimi Chemical Co., Ltd.), 1600 g of methylene chloride, 12.95 g of benzyldimethylamine, 420 g of pure water and 178.0 g of a 30.5 wt% NaOH aqueous solution were charged, and the mixture was stirred at a reaction temperature of 40 ° C. After stirring for 24 hours, the organic layer was washed with a 1N aqueous hydrochloric acid solution and then with pure water. The obtained solution was concentrated by an evaporator, dropped into methanol for solidification, and the solid was recovered by filtration and dried in vacuo to obtain 503.5 g of “polyphenylene ether (1)”. The “polyphenylene ether (1)” had a number average molecular weight of 1187, a weight average molecular weight of 1675, and a vinyl group equivalent of 590 g / vinyl group.

(Polyphenylene ether (2))
9.36 g (42.1 mmol) of CuBr _{2 and} 1.81 g of N, N′-di-t-butylethylenediamine were placed in a 12-liter vertical reactor equipped with a stirrer, a thermometer, an air introduction tube, and a baffle plate. 5 mmol), 67.77 g (671.0 mmol) of n-butyldimethylamine, and 2600 g of toluene were stirred and stirred at a reaction temperature of 40 ° C., and 2,2 ′, 3,3 ′, 12,532.g (0.48 mol) of 5,5′-hexamethyl- (1,1′-biphenol) -4,4′-diol, 878.4 g (7.2 mol) of 2,6-dimethylphenol, N, N ′ A mixed solution of 1.22 g (7.2 mmol) of di-t-butylethylenediamine and 26.35 g (260.9 mmol) of n-butyldimethylamine, A mixed gas adjusted to an oxygen concentration of 8% by mixing nitrogen and air was added dropwise over 230 minutes while bubbling at a flow rate of 5.2 l / min, followed by stirring.

  After the completion of the dropwise addition, 1500 g of water in which 48.06 g (126.4 mmol) of tetrasodium ethylenediaminetetraacetate was dissolved was added to stop the reaction. The aqueous layer and the organic layer were separated, and the organic layer was washed with a 1N aqueous hydrochloric acid solution and then with pure water. The obtained solution was concentrated to 50% by weight using an evaporator to obtain 1981 g of a toluene solution of a bifunctional phenylene ether oligomer (resin “B”). The resin “B” had a number average molecular weight of 1975, a weight average molecular weight of 3,514, and a hydroxyl equivalent of 990.

  In a reactor equipped with a stirrer, a thermometer, and a reflux tube, 833.4 g of a toluene solution of the resin "B", 76.7 g of vinylbenzyl chloride (trade name: CMS-P; manufactured by Seimi Chemical Co., Ltd.), 1600 g of methylene chloride, 6.2 g of benzyldimethylamine, 199.5 g of pure water and 83.6 g of a 30.5 wt% NaOH aqueous solution were charged, and the mixture was stirred at a reaction temperature of 40 ° C. After stirring for 24 hours, the organic layer was washed with a 1N aqueous hydrochloric acid solution and then with pure water. The obtained solution was concentrated by an evaporator, dropped into methanol for solidification, and the solid was recovered by filtration and dried in vacuo to obtain 450.1 g of “polyphenylene ether (2)”. The vinyl “polyphenylene ether (2)” had a number average molecular weight of 2,250, a weight average molecular weight of 3,920, and a vinyl group equivalent of 1,189 g / vinyl group.

  Next, a method for manufacturing a prepreg, a dielectric constant, and a dielectric loss tangent evaluation sample of Examples 1 to 3 and Comparative Example 1 will be described.

[Example 1]
70 parts by mass of the above-mentioned polyphenylene ether (1) was prepared, 100 parts by mass of toluene was added as a solvent, mixed at 80 ° C. for 30 minutes, stirred and completely dissolved. To the polyphenylene ether solution thus obtained, 30 parts by mass of "TAIC" manufactured by Nippon Kasei Co., Ltd. as a cross-linking curing agent, and brominated organic compound ethylene bis (pentabromophenyl) (albemarl) as a flame retardant 20 parts by mass of "SAYTEX8010 (trade name)" manufactured by Japan Co., Ltd. and 14 parts by mass of spherical synthetic (fused) silica ("SC2050 (trade name)" manufactured by Admatex Co., Ltd.) as an inorganic filler were compounded. . These were mixed, dispersed and dissolved in toluene as a solvent and diluted to a solid content of 65% to obtain a varnish of a resin composition. Since the above-mentioned flame retardant is a brominated organic compound which does not react with polyphenylene ether and TAIC, in the varnish which is a resin composition, the flame retardant was dispersed without being dissolved in toluene.

  Next, a varnish was impregnated with a glass cloth (IPC No. # 2116) as a base material, and then heated and dried at 170 ° C. for 5 minutes to remove the solvent and remove the solvent to prepare a prepreg having a resin content of 55% by mass. Got. The lowest melt viscosity is measured by measuring the melt viscosity of the resin composition in the prepreg from room temperature to 200 ° C. at a heating rate of 2 ° C./min using a rheometer viscosity measuring device (ARES-G2, manufactured by TA Instruments). Was evaluated. As a result of the evaluation, the minimum melt viscosity of the resin composition in the prepreg was 10,000 Pa · s. The resin composition in the prepreg had a dielectric constant Dk at 10 GHz of 2.5 and a dielectric loss tangent Df at 10 GHz of 0.005. In addition, the characteristic of the resin composition is a value obtained by measuring a resin composition to which a similar heat history was added without a glass cloth.

Eight prepregs thus obtained are stacked, and 35 μm copper foil (“3EC-III” manufactured by Mitsui Kinzoku Kogyo Co., Ltd.) is placed on both sides thereof, at a pressure of 30 kg / cm ² and a temperature of 210 ° C. for 150 minutes. Vacuum pressing was performed to obtain a 0.8 mm double-sided copper-clad laminate for a printed wiring board.

  Using a test piece from which the copper foil of the double-sided copper-clad laminate was removed, a dielectric constant Dk of 10 GHz and a dielectric loss tangent Df of 10 GHz were measured using a measuring device by a cavity resonator perturbation method (“Agilent 8722ES” manufactured by Agilent Technologies, Inc.). Was measured. As a result, the dielectric constant Dk at 10 GHz of the copper-clad laminate was 3.4, and the dielectric loss tangent Df at 10 GHz was 0.005.

Using the double-sided copper-clad laminate obtained as described above as a core material, a pattern having a copper hole of 20 mm × 20 mm (residual copper ratio: 70%) was prepared and subjected to an inner layer treatment. The prepreg and the copper foil were laminated on both surfaces of the core material, and were subjected to heat and pressure molding at a pressure of 30 kg / cm ² and a temperature of 210 ° C. for 150 minutes.

  In order to evaluate the moldability, the outer copper foil of the four-layer substrate (four copper wiring layers) was etched over the entire surface. The moldability was determined based on whether the copper missing portion was completely filled with the resin in the prepreg or insufficiently filled (including the case where voids could be confirmed). This determination is made visually using the permeability of the resin. As a result of the determination of the moldability, the resin in the prepreg was completely filled in the copper-leaved portion, and had good moldability.

[Example 2]
In Example 2, a varnish was produced using polyphenylene ether (2) instead of polyphenylene ether (1) used in Example 1. The varnish of Example 2 was manufactured in the same manner as in Example 1. In Example 2, the heating and drying conditions were set at a temperature of 170 ° C. for 7 minutes. Then, the same evaluation as in Example 1 was performed.

  In Example 2, as a result of evaluation of the minimum melt viscosity, the minimum melt viscosity of the resin composition in the prepreg was 30,000 Pa · s. The resin composition in the prepreg had a dielectric constant Dk at 10 GHz of 2.5 and a dielectric loss tangent Df at 10 GHz of 0.005. The copper-clad laminate had a dielectric constant Dk at 10 GHz of 3.4 and a dielectric loss tangent Df at 10 GHz of 0.005. As a result of the determination of the moldability, it was found that the resin in the prepreg was completely filled in the copper-leached portion, and the moldability was good.

[Example 3]
In Example 3, a varnish was produced using the polyphenylene ether (1) used in Example 1. The varnish of Example 3 was manufactured in the same manner as in Example 1. In Example 3, the heating and drying conditions were a temperature of 170 ° C. and 9 minutes. Then, the same evaluation as in Example 1 was performed.

  In Example 3, as a result of evaluation of the minimum melt viscosity, the minimum melt viscosity of the resin composition in the prepreg was 50,000 Pa · s. The resin composition in the prepreg had a dielectric constant Dk at 10 GHz of 2.5 and a dielectric loss tangent Df at 10 GHz of 0.005. The copper-clad laminate had a dielectric constant Dk at 10 GHz of 3.4 and a dielectric loss tangent Df at 10 GHz of 0.005. As a result of the determination of the moldability, it was found that the resin in the prepreg was completely filled in the copper-leached portion, and the moldability was good.

[Comparative Example 1]
In Comparative Example 1, which is a comparative example of Examples 1 to 3, a varnish was produced using the polyphenylene ether (1) used in Example 1. The varnish of Comparative Example 1 was manufactured in the same manner as in Example 1. In Comparative Example 1, the heating and drying conditions were 170 ° C. for 10 minutes. Then, the same evaluation as in Example 1 was performed.

  In Comparative Example 1, as a result of the evaluation of the minimum melt viscosity, the minimum melt viscosity of the resin composition in the prepreg was 60000 Pa · s. The resin composition in the prepreg had a dielectric constant Dk at 10 GHz of 2.5 and a dielectric loss tangent Df at 10 GHz of 0.005. The copper-clad laminate had a dielectric constant Dk at 10 GHz of 3.4 and a dielectric loss tangent Df at 10 GHz of 0.006. As a result of the determination of the moldability, the filling of the resin in the prepreg into the copper bleeding portion was insufficient, and good moldability was not shown.

  Table 1 shows the configurations and evaluation results of Examples 1 to 3 and Comparative Example 1.

  As shown in Table 1, in Examples 1 to 3 in which the minimum melt viscosity was 50,000 Pa · s or less as compared with Comparative Example 1 in which the minimum melt viscosity was high, good moldability was obtained.

  Subsequently, the polyphenylene ether and the epoxy compound used in Examples 4 to 7 and Comparative Example 2 will be described.

(Polyphenylene ether (3))
As the “polyphenylene ether (3)”, a polyphenylene ether having a hydroxyl group at the end of the polyphenylene ether (SA90 manufactured by SABIC Innovative Plastics) was used. The number average molecular weight of “polyphenylene ether (3)” is 1,700.

(Epoxy compound (1))
As the epoxy compound, a dicyclopentadiene type epoxy compound (“Epiclon HP7200 (trade name)” manufactured by DIC Corporation) was used. Epicron HP7200 has a number average molecular weight of 550.

(Epoxy compound (2))
As the epoxy compound, a naphthalene skeleton-modified epoxy resin ("Epiclon HP4032D (trade name)" manufactured by DIC Corporation) was used. Epicron HP4032D has a number average molecular weight of 280.

  Next, a description will be given of a method of manufacturing a prepreg, a dielectric constant, and a dielectric loss tangent evaluation sample of Examples 4 to 7 and Comparative Example 2.

[Example 4]
30 parts by mass of the above polyphenylene ether (3) was prepared, toluene was added as a solvent, and the mixture was stirred and completely dissolved. To the polyphenylene ether solution thus obtained, 45 parts by mass of the epoxy compound (1) and 2,2-bis (4-cyanatophenyl) propane (Mitsubishi Gas Chemical Co., Ltd.) as a cyanate ester compound were used. After adding 25 parts by mass of “CA210 (trade name)” manufactured by Co., Ltd., the mixture was stirred for 30 minutes to completely dissolve. Further, 25 parts by weight of the above-mentioned "SAYTEX8010" as a flame retardant and 24 parts by weight of the above-mentioned "SC2050" as an inorganic filler are added, and these are mixed, dispersed, and dissolved in toluene as a solvent to obtain a solid. The resulting mixture was diluted to 65% to obtain a varnish of the resin composition. The flame retardant did not dissolve, but was dispersed in the resin varnish with an average particle diameter of 1 μm or more and 10 μm or less.

  Next, a varnish was impregnated with a glass cloth (IPC No. # 2116) as a base material, and then heated and dried at 170 ° C. for 5 minutes to remove the solvent and remove the solvent to prepare a prepreg having a resin content of 55% by mass. Got. As a result of evaluation of the minimum melt viscosity, the minimum melt viscosity of the resin composition in the prepreg was 10,000 Pa · s. The resin composition in the prepreg had a dielectric constant Dk at 10 GHz of 2.6 and a dielectric loss tangent Df at 10 GHz of 0.007. The copper-clad laminate had a dielectric constant Dk at 10 GHz of 3.6 and a dielectric loss tangent Df at 10 GHz of 0.005. As a result of the determination of the moldability, it was found that the resin in the prepreg was completely filled in the copper-leached portion, and the moldability was good. In addition, each evaluation is the same as that of Example 1.

[Example 5]
In Example 5, a varnish was produced using the epoxy compound (2) in place of the epoxy compound (1) used in Example 4. The varnish of Example 5 was manufactured in the same manner as in Example 4. In Example 5, the heating and drying conditions were a temperature of 170 ° C. and 9 minutes. Then, the same evaluation as in Example 1 was performed.

  In Example 5, as a result of evaluation of the minimum melt viscosity, the minimum melt viscosity of the resin composition in the prepreg was 50,000 Pa · s. The resin composition in the prepreg had a dielectric constant Dk at 10 GHz of 2.6 and a dielectric loss tangent Df at 10 GHz of 0.007. The copper-clad laminate had a dielectric constant Dk at 10 GHz of 3.6 and a dielectric loss tangent Df at 10 GHz of 0.005. As a result of the determination of the moldability, it was found that the resin in the prepreg was completely filled in the copper-leached portion, and the moldability was good.

[Example 6]
In Example 6, compared with Example 4, a varnish was produced with a content ratio of polyphenylene ether (3) being small (20 parts by mass) and epoxy compound (1) being large (55 parts by mass). Except for the method of compounding the varnish of Example 6, the production method was the same as that of Example 4. In Example 6, the heating and drying conditions were 170 ° C. for 5 minutes. Then, the same evaluation as in Example 1 was performed.

  In Example 6, as a result of evaluation of the minimum melt viscosity, the minimum melt viscosity of the resin composition in the prepreg was 10,000 Pa · s. The resin composition in the prepreg had a dielectric constant Dk at 10 GHz of 2.6 and a dielectric loss tangent Df at 10 GHz of 0.007. The copper-clad laminate had a dielectric constant Dk at 10 GHz of 3.6 and a dielectric loss tangent Df at 10 GHz of 0.004. As a result of the determination of the moldability, it was found that the resin in the prepreg was completely filled in the copper-leached portion, and the moldability was good.

[Example 7]
In Example 7, compared to Example 5, a varnish was produced with a content ratio of polyphenylene ether (3) being small (20 parts by mass) and epoxy compound (2) being large (55 parts by mass). Except for the method of compounding the varnish of Example 7, the production method was the same as that of Example 5. In Example 7, the heating and drying conditions were 170 ° C. for 9 minutes. Then, the same evaluation as in Example 1 was performed.

  In Example 7, as a result of evaluation of the minimum melt viscosity, the minimum melt viscosity of the resin composition in the prepreg was 50,000 Pa · s. The resin composition in the prepreg had a dielectric constant Dk at 10 GHz of 2.6 and a dielectric loss tangent Df at 10 GHz of 0.007. The copper-clad laminate had a dielectric constant Dk at 10 GHz of 3.6 and a dielectric loss tangent Df at 10 GHz of 0.005. As a result of the determination of the moldability, it was found that the resin in the prepreg was completely filled in the copper-leached portion, and the moldability was good.

[Comparative Example 2]
In Comparative Example 2, which is a comparative example of Examples 4 to 7, a varnish was produced using the polyphenylene ether (3) used in Example 4. The method for producing the varnish of Comparative Example 2 was the same as that of Example 1. In Comparative Example 2, the heating and drying conditions were set at a temperature of 170 ° C. for 10 minutes. Then, the same evaluation as in Example 1 was performed.

  In Comparative Example 2, as a result of the evaluation of the minimum melt viscosity, the minimum melt viscosity of the resin composition in the prepreg was 60000 Pa · s. The resin composition in the prepreg had a dielectric constant Dk at 10 GHz of 2.6 and a dielectric loss tangent Df at 10 GHz of 0.007. The copper-clad laminate had a dielectric constant Dk at 10 GHz of 3.6 and a dielectric loss tangent Df at 10 GHz of 0.008. As a result of the determination of the moldability, the filling of the resin in the prepreg into the copper bleeding portion was insufficient, and good moldability was not shown.

  Table 2 shows configurations and evaluation results of Examples 4 to 7 and Comparative Example 2.

  As shown in Table 2, better moldability was obtained in Examples 4 to 7 in which the minimum melt viscosity was 50,000 Pa · s or less as compared with Comparative Example 2 in which the minimum melt viscosity was high.

  As described above, according to the prepregs according to Examples 1 to 7 of the present invention, the minimum melt viscosity is 50,000 Pa · s or less, and good moldability can be realized.

  The present invention is not limited to the above embodiment, and can be appropriately changed without departing from the gist.

Claims (5)

An epoxy compound having a number average molecular weight of 1,000 or less and containing no halogen atom having at least two epoxy groups in one molecule, selected from dicyclopentadiene-type epoxy compounds or naphthalene skeleton-modified epoxy resins ,
A polyphenylene ether having a number average molecular weight of 5,000 or less and having a terminal hydroxyl group ;
2,2-bis (4-cyanatophenyl) propane as a cyanate ester compound, and
Including a thermosetting resin composition having a resin varnish containing a halogen-based flame retardant,
Minimum melt viscosity is Ri der following 50,000Pa · s, and
Dielectric constant Dk at 10GHz is 2.8 or less, a prepreg dielectric loss tangent Df at 10GHz is characterized der Rukoto 0.007. The prepreg according to claim 1, wherein the resin varnish further contains a curing catalyst that promotes a reaction between the epoxy compound and the polyphenylene ether and the cyanate ester compound as a curing agent. The prepreg according to claim 1 or 2 , further comprising a filler containing silica dispersed in the thermosetting resin composition. The prepreg according to any one of claims 1 to 3, wherein the polyphenylene ether has a number average molecular weight of 3000 or less. Eight sheets of the prepreg are stacked, copper foil of 35 μm is arranged on both sides thereof, and the pressure is 30 kg / cm. ^Two Vacuum pressing was performed at a temperature of 210 ° C. for 150 minutes to produce and evaluate a 0.8 mm double-sided copper-clad laminate for a printed wiring board. The dielectric constant Dk at 10 GHz was 3.6 or less, and the dielectric constant Dk was 10 GHz or less. 5. The prepreg according to claim 1, wherein the dielectric tangent Df of the prepreg is 0.005 or less.