Resin fiber sheet, prepreg, and method for producing prepreg

Abstract

Provided are: a resin fiber sheet and a prepreg which use a laminated sheet as a raw material and which achieve excellent heat resistance, dielectric constant, dielectric loss tangent and dimensional stability (little warping); and a method for producing a prepreg using the resin fiber sheet. In one embodiment of the present invention, provided is a resin fiber sheet constituted from a poly(phenylene ether) composition fiber. The poly(phenylene ether) composition fiber contains more than 0 mass% and not more than 95 mass% of a poly(phenylene ether) and a total of not less than 5 mass% and less than 100 mass% of a liquid crystal polyester and / or a syndiotactic polystyrene, and has a single fiber diameter of 1-50 μm.

Description

[Technical Field]

[0001] The present invention relates to a resin fiber sheet, a prepreg, and a method for producing a prepreg. [Background technology]

[0002] In recent years, with the remarkable progress in information network technology and the expansion of services utilizing information networks, electronic devices are being required to handle larger amounts of information and to process faster. To meet these demands, printed wiring boards mounted on electronic devices are strongly required to have low dielectric constants and low dielectric loss tangents in addition to the traditional properties of insulation reliability, heat resistance, rigidity, flame retardancy, etc. Therefore, further improvements in the dielectric constants and dielectric loss tangents of resin compositions (hereinafter also referred to as matrix resin compositions) and glass cloth substrates, which are the main insulating materials constituting printed wiring boards, are being investigated.

[0003] As a matrix resin composition, a mixture of polyphenylene ether (hereinafter also referred to as PPE), which has a low dielectric constant, a low dielectric loss tangent, and high heat resistance, is preferably used as the material for the above-mentioned printed wiring board. For example, Patent Document 1 describes that a resin composition containing a specific modified polyphenylene ether, a specific cyanurate compound as a crosslinking agent, a copolymer of butadiene and styrene, and an organic peroxide in predetermined proportions can provide a matrix resin composition with an excellent low dielectric constant and a low dielectric loss tangent.

[0004] As the glass cloth substrate, low-dielectric-constant glass cloth such as NE glass or L glass, which has a composition different from that of general E glass, is preferably used. Generally, to lower the dielectric constant, it is necessary to increase the amount of SiO2 and B2O3 in the glass composition. To date, low-dielectric-constant glass compositions actually used in glass cloth for printed wiring boards have often been adjusted to contain 45% to 60% SiO2 and 15% to 30% B2O3 (Patent Documents 2 and 3). Meanwhile, the use of organic fibers as low-dielectric-constant substrates other than glass cloth has been investigated (Patent Documents 4 and 5). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-82200 A [Patent Document 2] Japanese Patent Application Publication No. 63-2831 [Patent Document 3] Japanese Patent Application Publication No. 11-292567 [Patent Document 4] Special Publication No. 2017-502179 [Patent Document 5] Japanese Patent Application Laid-Open No. 2008-069478 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with future high-speed transmission of 200 Gbps or more, the problem of signal skew (skew) is becoming apparent. This problem is primarily caused by local variations in the dielectric constant of the insulating layer of the substrate. While the dielectric constant of a typical low-dielectric-constant matrix resin composition is approximately 2.0 to 3.0, that of a low-dielectric-constant glass cloth substrate is approximately 4.6 to 4.8, and local variations in the dielectric constant of the low-dielectric-constant glass cloth substrate within the substrate are becoming a major problem. While the organic fibers described in Patent Documents 4 and 5 can reduce the above-mentioned signal skew problem, the organic fibers do not provide sufficient heat resistance and dimensional stability for use as substrates, prepregs, and laminates.

[0007] An object of the present invention is to provide a resin fiber sheet and prepreg that are raw materials for laminates that have excellent heat resistance, dielectric constant, dielectric dissipation factor, and dimensional stability (low warpage), as well as a method for producing a prepreg using the resin fiber sheet. [Means for solving the problem]

[0008] The gist of the present invention is as follows. [1] A resin fiber sheet made of polyphenylene ether composition fibers, The polyphenylene ether composition fiber is a resin fiber sheet containing more than 0% by mass and 95% by mass or less of polyphenylene ether, and 5% by mass or more and less than 100% by mass of liquid crystal polyester or syndiotactic polystyrene, or both of them, in total, and having a single fiber diameter of 1 to 50 μm. [2] 2. The resin fiber sheet according to item 1, wherein the polyphenylene ether composition fiber contains 5 to 40 mass % of polyphenylene ether and 60 to 95 mass % in total of liquid crystal polyester or syndiotactic polystyrene or both of them. [3] 3. The resin fiber sheet according to item 1 or 2, wherein the toughness of the polyphenylene ether composition fiber is 5 or more and 30 or less. [4] 4. The resin fiber sheet according to any one of items 1 to 3, wherein the polyphenylene ether composition fiber has a thermal stress rise temperature of 100°C or higher and 190°C or lower. [5] The toughness of the polyphenylene ether composition fiber is 5 or more and 30 or less, and 5. The resin fiber sheet according to any one of items 1 to 4, wherein the polyphenylene ether composition fiber has a thermal stress rise temperature of 100°C or higher and 190°C or lower. [6] 6. The resin fiber sheet according to any one of items 1 to 5, wherein the polyphenylene ether has a number average molecular weight of 9,000 to 21,000. [7] 7. The resin fiber sheet according to any one of items 1 to 6, wherein the resin fiber sheet is a resin fiber cloth woven to have a warp and weft weaving density of 20 to 200 threads / inch and an opening ratio of 1 to 30%. [8] Item 6. The resin fiber sheet according to item 5, wherein the resin fiber sheet is a resin fiber cloth woven to have a warp and weft density of 20 to 90 threads / inch and an opening ratio of 1 to 30%. [9] The resin fiber sheet is a nonwoven fabric, 7. The resin fiber sheet according to any one of items 1 to 6, wherein the polyphenylene ether composition fiber is composed of single yarns having a single yarn diameter of 1 to 50 μm.

[10] A prepreg comprising the resin fiber sheet according to any one of items 1 to 9 and a matrix resin composition.

[11] Item 11. The prepreg according to item 10, wherein the matrix resin composition comprises at least one thermosetting resin selected from the group consisting of epoxy resins, cyanate ester resins, bismaleimide resins, polyphenylene ether resins, and bismaleimide-triazine resins.

[12] Item 12. The prepreg according to item 11, wherein the polyphenylene ether resin comprises a low-molecular-weight polyphenylene ether having a number-average molecular weight of 1,000 to 5,000.

[13] 13. The prepreg according to any one of items 10 to 12, wherein the matrix resin composition further contains a silica filler.

[14] Item 14. The prepreg according to item 13, wherein the silica filler is spherical silica with an average particle size of 2 μm or less.

[15] Item 15. The prepreg according to item 13 or 14, wherein the content of the silica filler in the matrix resin composition is 10 to 50% by mass.

[16] 16. The prepreg according to any one of items 10 to 15, wherein the matrix resin composition further contains a crosslinking agent.

[17] Item 17. The prepreg according to item 16, wherein the crosslinking agent is a styrene-butadiene copolymer having a number average molecular weight of 1,000 to 7,000 and containing 20% ​​by mass or more of structural units derived from styrene.

[18] Item 18. The prepreg according to item 16 or 17, wherein the content of the crosslinking agent in the matrix resin composition is 3 to 30% by mass.

[19] a varnish preparation step of preparing a matrix resin composition varnish containing a low-molecular-weight polyphenylene ether having a number-average molecular weight of 1,000 to 5,000 and an organic solvent; an impregnation step of impregnating the resin fiber sheet according to any one of items 1 to 9 with the matrix resin composition varnish; and a drying step of drying the resin fiber sheet impregnated with the matrix resin composition varnish; A method for producing a prepreg, comprising:

[20] Item 20. The method for producing a prepreg according to Item 19, wherein the organic solvent is substantially free of aromatic compounds. [twenty one] Item 21. The method for producing a prepreg according to Item 19 or 20, wherein the matrix resin composition varnish further contains a silica filler. [twenty two] Item 22. The method for producing a prepreg according to Item 21, wherein the silica filler is spherical silica with an average particle size of 2 μm or less. [twenty three] 23. The method for producing a prepreg according to any one of items 19 to 22, wherein the matrix resin composition varnish further contains a crosslinking agent. [twenty four] Item 24. The method for producing a prepreg according to Item 23, wherein the crosslinking agent is a styrene-butadiene copolymer having a number average molecular weight of 1,000 to 7,000 and containing 20% ​​by mass or more of structural units derived from styrene. [twenty five] 25. The method for producing a prepreg according to any one of items 19 to 24, wherein in the impregnation step, the resin fiber sheet is impregnated with the matrix resin composition varnish by applying a tension of 200 N / m or less.

[26] 19. The prepreg according to any one of items 10 to 18, which is for forming an insulating layer of a printed wiring board.

[27] 19. The prepreg according to any one of items 10 to 18, which is used to form a build-up insulating layer of a printed wiring board.

[28] A prepreg with a support, comprising the prepreg according to any one of items 10 to 18 and a support disposed on one or both sides of the prepreg.

[29] Item 29. The prepreg with support according to item 28, wherein the support is a resin film or a metal foil.

[30] continuously unwinding the support; a first coating step of continuously coating the support with a matrix resin composition varnish; A step of unwinding the resin fiber sheet according to any one of items 1 to 9 by applying tension to the resin fiber sheet while contacting it with a non-specular roll; a step of contacting the matrix resin composition varnish applied to the support with the surface of the resin fiber sheet to obtain a first resin fiber sheet composite; a first drying step of drying the first resin fiber sheet composite; A method for producing a prepreg with a support, comprising:

[31] a second coating step of continuously coating a matrix resin composition varnish onto the first resin fiber sheet composite dried in the first drying step to obtain a second resin fiber sheet composite; a second drying step of drying the second resin fiber sheet composite; Item 31. The method for producing a prepreg with a support according to Item 30, further comprising:

[32] 19. A laminate comprising the prepreg according to any one of items 10 to 18.

[33] 27. A printed wiring board comprising an insulating layer formed from a cured product of the prepreg according to Item 26.

[34] 28. A printed wiring board comprising a build-up insulating layer formed from a cured product of the prepreg according to Item 27.

[35] Item 34. A semiconductor device comprising the printed wiring board according to Item 33.

[36] Item 35. A semiconductor device comprising the printed wiring board according to item 34. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a resin fiber sheet and a prepreg that are raw materials for a laminated plate that has excellent heat resistance, dielectric constant, dielectric tangent, and dimensional stability (low warpage), as well as a method for producing a prepreg using the resin fiber sheet. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described. The following embodiment is one aspect of the present invention, and therefore the present invention is not limited to only the following embodiment. Therefore, the following embodiment can be appropriately modified and carried out within the scope of the gist of the present invention. Furthermore, in this specification, unless otherwise specified, the symbol "to" means that the numerical values ​​at both ends thereof are included as the upper and lower limits. In this specification, the upper and lower limits of a numerical range can be combined in any way.

[0011] <Resin fiber sheet> The resin fiber sheet according to this embodiment is made of polyphenylene ether (PPE) composition fibers. In one embodiment, the PPE composition fiber constituting the resin fiber sheet contains more than 0% by mass but not more than 95% by mass of PPE, and 5% by mass or more but less than 100% by mass of liquid crystal polyester, syndiotactic polystyrene, or both. In one embodiment, the PPE composition fiber has a single yarn diameter of 1 to 50 μm. The PPE composition fiber may be a fiber formed by bundling 10 to 500 single yarns each having a single yarn diameter of 1 to 50 μm, or may be composed of the above single yarns. In one embodiment, the resin fiber sheet may be a resin fiber cloth that is a woven fabric, and in another embodiment, may be a nonwoven fabric. In one embodiment, the resin fiber cloth is a woven fabric in which the warp and weft density of the PPE composition fibers is 20 to 200 threads / inch and the opening ratio is 1 to 30%. In one embodiment, the PPE composition fibers constituting the resin fiber cloth are fibers formed by bundling 10 to 500 single yarns each having a diameter of 1 to 50 μm. In one embodiment, the PPE composition fiber constituting the nonwoven fabric is a single yarn having a diameter of 1 to 50 μm. The basis weight of the PPE composition fiber constituting the nonwoven fabric is 5 to 100 g / m 2 The basis weight is more preferably 50 g / m 2 or less, or 30 g / m 2 or less than 20 g / m 2The basis weight is measured according to ISO 9073-1. The present inventors have particularly focused on the fact that a resin fiber cloth in which PPE composition fibers containing a specific polyphenylene ether and either a liquid crystal polyester or syndiotactic polystyrene or both of these are woven in a specific manner, or a nonwoven fabric composed of the PPE composition fibers, can be used as a raw material for a laminated board that has excellent heat resistance, dielectric constant, dielectric dissipation factor, and dimensional stability (low warpage). Hereinafter, preferred examples of PPE composition fibers in resin fiber sheets, more specifically in woven fabrics and nonwoven fabrics, will be described.

[0012] The PPE contained in the PPE composition fiber contains phenylene ether units as repeating structural units, and the phenylene group in the phenylene ether unit may or may not have a substituent.

[0013] The structural units of the PPE contained in the PPE composition fibers may be the same as those exemplified below for the low-molecular-weight PPE contained in the matrix resin composition according to one embodiment.

[0014] The PPE may also contain other structural units in addition to phenylene ether units. The amount of the other structural units is typically 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or 5% or less of the total number of structural units. However, the amount of the other structural units may exceed 30% of the total number of structural units as long as it does not impair the effects of the present invention.

[0015] Specific examples of PPE include poly(2,6-dimethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenylene ether), copolymers of 2,6-dimethylphenol and other phenols (e.g., 2,3,6-trimethylphenol, 2-methyl-6-butylphenol, etc.), and PPE copolymers obtained by coupling 2,6-dimethylphenol with biphenols or bisphenols.

[0016] The PPE contained in the PPE composition fiber preferably has a number-average molecular weight of 9,000 to 21,000. When the number-average molecular weight of the PPE is 9,000 or more, the heat resistance required for the substrate and the chemical resistance to solvents for matrix resin composition varnishes and cleaning solutions for the substrate tend to be good. When the number-average molecular weight of the PPE is 21,000 or less, the extrusion moldability during preparation of the PPE composition and during spinning tends to be good. The number-average molecular weight of the PPE is more preferably 9,500 or more or 10,000 or more, and more preferably 17,000 or less or 16,000 or less.

[0017] The number average molecular weight and weight average molecular weight of the present disclosure are each determined in terms of standard polystyrene by performing gel permeation chromatography (hereinafter, GPC) measurement and calculating the relationship between the molecular weight of a standard polystyrene sample measured under the same conditions and the elution time.

[0018] In one embodiment, the PPE preferably comprises or consists of a combination of a PPE component having a number-average molecular weight of 9,000 to 12,000 and a PPE component having a number-average molecular weight of 14,000 to 17,000. This improves both heat resistance and moldability. In particular, adjusting the blending amount of the PPE component having a number-average molecular weight of 9,000 to 12,000 to 30 to 60 mass% relative to 100 mass% of PPE further improves both heat resistance and moldability, and also increases the affinity between the resin fiber sheet and the matrix resin composition varnish during prepreg production, improving the heat resistance and adhesiveness of the resulting laminate.

[0019] The number average molecular weight of the PPE component having a number average molecular weight of 9,000 to 12,000 may more preferably be 9,500 or more, or 10,000 or more, and may be 11,500 or less, or 11,000 or less, respectively.

[0020] The number average molecular weight of the PPE component having a number average molecular weight of 14,000 to 17,000 may more preferably be 14,500 or more, or 15,000 or more, and may be 16,500 or less, or 16,000 or less, respectively.

[0021] The PPE composition fiber contains a liquid crystal polyester and / or a syndiotactic polystyrene. Both of these polymers can exhibit crystallinity due to the highly ordered structure of the polymer molecules, while also exhibiting excellent fluidity, which can improve the heat resistance, mechanical strength, and / or solvent resistance of the PPE composition fiber and also contribute to the production of a PPE composition fiber with good dimensional stability.

[0022] Liquid crystal polyester (hereinafter also referred to as LCP) is composed of repeating structural units derived from, for example, aromatic diol, aromatic dicarboxylic acid, aromatic hydroxycarboxylic acid, etc., and its chemical structure is not particularly limited as long as it does not impair the effects of the present invention. Furthermore, the liquid crystal polyester may contain structural units derived from, for example, aromatic diamine, aromatic hydroxyamine, aromatic aminocarboxylic acid, etc., within the range that does not impair the effects of the present invention.

[0023] The liquid crystalline polyester preferably has a melting point of 200°C to 400°C. When the melting point of the liquid crystalline polyester is 200°C or higher, the heat resistance and chemical resistance required for the substrate tend to be good. When the melting point of the liquid crystalline polyester is 400°C or lower, the extrusion moldability during preparation of the PPE composition and during spinning, and the orientation during spinning tend to be good. The melting point of the liquid crystalline polyester is more preferably 200°C to 380°C, or 210°C to 350°C.

[0024] Syndiotactic polystyrene (hereinafter also referred to as sPS) is a styrene polymer that mainly has a syndiotactic structure. Here, the syndiotactic structure is a stereochemical structure in which the phenyl groups in the side chains are alternately positioned in opposite directions relative to the main chain formed by carbon-carbon bonds, and the stereoregularity can be determined by nuclear magnetic resonance spectroscopy ( 13 It is analyzed by C-NMR. 13 Tacticity measured by C-NMR can be expressed by the proportion of consecutive structural units, for example, dyads for 2 units, triads for 3 units, and pentads for 5 units. In a typical embodiment, a polystyrene resin having a syndiotactic structure may have a syndiotacticity of 75% or more, preferably 85% or more, for racemic dyads, or 30% or more, preferably 50% or more, for racemic pentads.

[0025] The syndiotactic polystyrene preferably has a weight-average molecular weight of 30,000 to 500,000. When the weight-average molecular weight of sPS is 30,000 or more, the heat resistance and chemical resistance required for the substrate tend to be good. When the weight-average molecular weight of sPS is 500,000 or less, the extrusion moldability during the preparation of the PPE composition and during spinning tends to be good. The weight-average molecular weight of sPS is more preferably 100,000 to 400,000, or 100,000 to 300,000.

[0026] In one embodiment, the PPE content in the PPE composition fiber is greater than 0% by mass and not greater than 95% by mass, preferably 5-95% by mass, 10-70% by mass, 15-60% by mass, or 20-50% by mass. PPE inherently has excellent heat resistance. In addition, when the PPE content is greater than 0% by mass, particularly 5% by mass or greater, the cured prepreg tends to exhibit excellent dielectric uniformity and signal shifts are favorably prevented. In particular, in embodiments in which the matrix resin contains PPE (preferably low-molecular-weight PPE), the adhesion between the matrix resin and the PPE composition fiber and the permeability of the matrix resin into the PPE composition fiber tend to be excellent. On the other hand, when the PPE content in the PPE composition fiber is 95% by mass or less, the melt spinnability is excellent. Furthermore, from the viewpoint of spinnability, the upper limit of the content is preferably 50% by mass or 40% by mass.

[0027] In one embodiment, the total content of LCP and / or sPS in the PPE composition fiber is 5% by mass or more and less than 100% by mass, and preferably 5 to 95% by mass, 10 to 90% by mass, 20 to 85% by mass, or 30 to 80% by mass.

[0028] When the PPE composition fiber contains PPE and LCP, the LCP content in the PPE composition fiber is preferably 2.5% by mass or more, or 5% by mass or more, and preferably 95% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less, or 30% by mass or less. When the LCP content is 2.5% by mass or more, particularly 5% by mass or more, excellent heat resistance is achieved. When the LCP content is 95% by mass or less, excellent spinnability is achieved, and when it is 30% by mass or less, stable spinning without thread breakage is possible. In addition, in applications where a low dielectric loss tangent is particularly required, the LCP content is preferably zero.

[0029] When the PPE composition fiber contains PPE and sPS, the sPS content in the PPE composition fiber is, in one embodiment, 2.5% by mass or more, 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, or 60% by mass or more, and preferably 95% by mass or less, 90% by mass or less, or 85% by mass or less. When the sPS content is 2.5% by mass or more, particularly 5% by mass or more, the PPE fiber composition has excellent solvent resistance, dielectric constant, and dielectric loss tangent. In particular, when the sPS content is 40% by mass or more, the effect of the sPS crystallinity is more pronounced, resulting in excellent dimensional stability (low warpage). When the sPS content is 95% by mass or less, the PPE fiber composition has excellent heat resistance.

[0030] When the PPE composition fiber contains both LCP and sPS and the total content is 5% by mass or more but less than 100% by mass, 5 to 95% by mass, 10 to 90% by mass, 20 to 85% by mass, or 30 to 80% by mass, the dielectric constant, dielectric loss tangent, heat resistance, and mechanical strength are particularly excellent, which is preferable.

[0031] In one embodiment, the toughness of the polyphenylene ether composition fiber is 5 or more and 30 or less. From the viewpoint of weaving properties, the toughness is preferably 5 or more, 7 or more, or 8 or more, and from the viewpoint of spinnability of the raw yarn, the toughness is preferably 30 or less, 20 or less, 17 or less, 15 or less, or 13 or less. The toughness is a value measured by the method described in the [Examples] section of this disclosure.

[0032] In one embodiment, the thermal stress rise temperature of the polyphenylene ether composition fiber is 100° C. or higher and 190° C. or lower. From the viewpoints of heat resistance and dimensional stability, the thermal stress rise temperature is preferably 100° C. or higher, 120° C. or higher, or 130° C. or higher, and from the viewpoint of toughness of the raw yarn, it is preferably 190° C. or lower, 180° C. or lower, 170° C. or lower, or 160° C. or lower. The thermal stress rise temperature is a value measured by the method described in the [Examples] section of this disclosure.

[0033] In a preferred embodiment, the polyphenylene ether composition fiber contains 5 to 40 mass % of polyphenylene ether and 60 to 95 mass % in total of liquid crystal polyester or syndiotactic polystyrene or both of them, from the viewpoint of spinnability.

[0034] In addition to PPE, LCP, and / or sPS, the PPE composition fiber may further contain additional components such as a styrene-based elastomer, a flame retardant, an antioxidant, an oil, and other additives, as needed.

[0035] The styrene-based elastomer is preferably at least one selected from the group consisting of styrene-butadiene block copolymer, styrene-ethylene-butadiene block copolymer, styrene-ethylene-butylene block copolymer, styrene-butadiene-butylene block copolymer, styrene-isoprene block copolymer, styrene-ethylene-propylene block copolymer, styrene-isobutylene block copolymer, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-ethylene-butadiene block copolymer, hydrogenated styrene-butadiene-butylene block copolymer, hydrogenated styrene-isoprene block copolymer, and styrene homopolymer (polystyrene), and more preferably a hydrogenated styrene-butadiene block copolymer.

[0036] Conventional known flame retardants can be used. Examples include inorganic flame retardants such as antimony trioxide, aluminum hydroxide, magnesium hydroxide, and zinc borate; aromatic bromine compounds such as hexabromobenzene, decabromodiphenylethane, 4,4-dibromobiphenyl, and ethylenebistetrabromophthalimide; and phosphorus-based flame retardants such as resorcinol bis-diphenyl phosphate and resorcinol bis-dixylenyl phosphate. These flame retardants can be used alone or in combination of two or more.

[0037] In one embodiment, the total content of the additional components in the PPE composition fiber is 0 to 20% by mass, preferably 0 to 15% by mass, 0 to 10% by mass, or 0 to 5% by mass.

[0038] The PPE composition can be prepared by melt-kneading the above raw materials in a twin-screw extruder or the like at, for example, 300°C or higher. Furthermore, this PPE composition can be heated to, for example, 280°C or higher by a conventional spinning method, specifically, for example, melt spinning, and then passed through a spinneret and extruded and spun to produce multifilament fibers. The optimal spinning speed varies depending on the resin composition. For example, for a composition with a PPE content of 5 to 40% by mass and an sPS content of 60 to 95% by mass, a spinning speed of 1000 to 4000 m / min is preferred. A spinning speed of 1000 m / min or higher tends to provide good toughness. Furthermore, a spinning speed of 4000 m / min or lower tends to result in reduced toughness and less fiber breakage. A more preferred range for the spinning speed is 1500 to 3000 m / min. Furthermore, it is preferable to further draw the fibers obtained by spinning to improve toughness and thermal stability (increase in thermal stress rise temperature). Drawing may be a separate process from spinning, or a spin-draw take-up method in which spinning and drawing are performed continuously may be used. The elongation of the drawn yarn is preferably 15 to 40%, more preferably 20 to 35%, from the viewpoint of quality, such as fuzz and yarn breakage. The draw ratio is preferably adjusted to achieve the above elongation. The preheating temperature for drawing is preferably 90 to 120°C. At 90°C or higher, yarn breakage and single yarn breakage are unlikely to occur. Furthermore, at 120°C or lower, toughness is unlikely to decrease. The heat setting temperature after drawing is preferably 120 to 180°C. At 120°C or higher, the thermal stress rise temperature is unlikely to decrease, and at 180°C or lower, toughness is unlikely to decrease. A more preferred heat setting temperature is 130 to 170°C. Furthermore, the relaxation ratio after heat setting is preferably 0.96 to 0.99. At 0.96 or higher, the winding tension is unlikely to decrease, and yarn breakage tends to be less likely. Furthermore, at 0.99 or lower, the thermal stress rise temperature tends to be less likely to decrease. The relaxation ratio is more preferably in the range of 0.965 to 0.985. The relaxation ratio is a value obtained by dividing the winding speed by the drawing speed. The diameter of a single yarn (a single yarn constituting the multifilament in one embodiment) is 1 to 50 μm in one embodiment, and may be preferably 5 to 50 μm, 5 to 30 μm, 5 to 20 μm, or 5 to 15 μm. The number of single yarns constituting the multifilament in one embodiment is 10 to 500, and may be preferably 10 to 200, 10 to 100, or 10 to 50.When the single yarn diameter is 1 μm or more, the necessary tensile strength is exhibited in the subsequent weaving and spreading processes, making fluffing (single yarn breakage) less likely to occur. When the single yarn diameter is 50 μm or less, the thickness generally required for circuit board applications can be achieved, and in particular, when the single yarn diameter is 30 μm or less, a thickness of 30 to 100 μm, which is suitable for circuit board applications, can be achieved. When the number of single yarns constituting the multifilament is 10 or more, the dielectric constant of the insulating layer of the circuit board can be made uniform by adjusting the subsequent weaving and spreading processes, and when the number of single yarns constituting the multifilament is 500 or less, the above-mentioned fluffing (single yarn breakage) is less likely to occur.

[0039] In one embodiment of the resin fiber cloth, the resin fiber cloth is produced by weaving the above-mentioned PPE composition fibers to a warp and weft density of 20 to 200 threads / inch and an opening ratio of 1 to 30%. When the warp and weft density is 20 threads / inch or more, warping can be prevented and the dielectric constant of the insulating layer of the substrate can be made uniform. When the warp and weft density is 200 threads / inch or less, entanglement of fibers can be prevented and fluff (single yarn breakage) can be suppressed. The warp and weft density is preferably 20 threads / inch to 150 threads / inch, or 20 threads / inch to 90 threads / inch, or 30 threads / inch to 70 threads / inch.

[0040] When the opening ratio is 1% or more, the matrix resin easily penetrates the resin fiber cloth, improving resin impregnation and heat resistance. Furthermore, since there are adequate areas where the resin fiber cloth is not present, the adhesion between the insulating layer of the substrate and the metal foil (e.g., copper foil) is improved. When the opening ratio is 30% or less, the dielectric constant of the insulating layer of the substrate can be made uniform, and the PPE composition fibers are adequately dispersed, improving heat resistance. The opening ratio is preferably 5% to 25%, or 10% to 20%. The warp and weft weave density and opening ratio are values ​​measured by the method described in the Examples section of the present disclosure. The weave structure is not particularly limited, but examples include plain weave, sash weave, satin weave, and twill weave. Among these, plain weave structures are more preferred.

[0041] The fiber surface of the resin fiber sheet may be surface-treated by a silane coupling agent treatment, a corona treatment, a plasma treatment, or the like. Among these, the fiber surface of the resin fiber sheet is preferably treated with an inert gas plasma. Such surface treatments tend to further improve the heat resistance and adhesiveness required for the substrate.

[0042] The resin fiber sheet of the present disclosure may be, in another embodiment other than the PPE composition fiber of this embodiment, for example, an amorphous resin composition fiber that exhibits a glass transition temperature of 150° C. or higher. Specific examples include fibers of a resin composition containing one or more members selected from polyamideimide, polyetherimide, polyethersulfone, polysulfone, polyarylate, etc., and the sPS of the present disclosure.

[0043] <Prepreg> The prepreg according to this embodiment includes the resin fiber sheet and a matrix resin composition. The matrix resin composition may be impregnated into the resin fiber sheet. In this embodiment, the matrix resin composition preferably contains at least one thermosetting resin selected from the group consisting of epoxy resins, cyanate ester resins, bismaleimide resins, polyphenylene ether resins, and bismaleimide-triazine resins (BT resins). In a preferred embodiment, a polyphenylene ether resin is used as the matrix resin. In this case, the matrix resin composition preferably contains a low-molecular-weight PPE having a number-average molecular weight of 1,000 to 5,000. The number-average molecular weight is preferably 1,000 or more, 1,500 or more, or 2,000 or more, and preferably 5,000 or less, 4,500 or less, or 4,000 or less. The matrix resin composition typically further contains a curing agent and an inorganic filler in addition to the matrix resin.

[0044] As an example, the prepreg according to the present embodiment can be produced by a process comprising the steps of: preparing a matrix resin composition varnish, preferably a matrix resin composition varnish containing at least one thermosetting resin selected from the group consisting of epoxy resins, cyanate ester resins, bismaleimide resins, bismaleimide-triazine resins (BT resins), and low-molecular-weight polyphenylene ethers having a number-average molecular weight of 1,000 to 5,000, and an organic solvent (hereinafter, sometimes referred to as "matrix resin composition varnish"); an impregnation step of impregnating the resin fiber sheet with the matrix resin composition varnish; and a drying step of drying the resin fiber sheet impregnated with the matrix resin composition varnish using a hot air dryer or the like; The thermosetting resin can be produced by a method comprising the steps of: The thermosetting resin is preferably a low-molecular-weight polyphenylene ether having a number-average molecular weight of 1,000 to 5,000.

[0045] In the impregnation step, the resin fiber sheet is preferably impregnated with the matrix resin composition varnish under tension of 200 N / m or less. From the viewpoint of dimensional stability (warpage) of the substrate, the tension is preferably 200 N / m or less, 150 N / m or less, or 100 N / m or less.

[0046] The proportion of the matrix resin composition (as solid content) in the prepreg of this embodiment is preferably 30% by mass to 80% by mass, more preferably 40% by mass to 70% by mass. When the proportion is 30% by mass or more, the prepreg tends to have better insulation reliability when used for electronic substrates, etc. When the proportion is 80% by mass or less, the prepreg tends to have better mechanical properties, such as flexural modulus, when used for electronic substrates, etc.

[0047] [Matrix resin composition] The matrix resin composition according to this embodiment preferably contains at least one thermosetting resin selected from the group consisting of epoxy resins, cyanate ester resins, bismaleimide resins, polyphenylene ether resins, and bismaleimide-triazine resins (BT resins). The polyphenylene ether resin preferably contains or is a low-molecular-weight PPE having a number-average molecular weight of 1,000 to 5,000. In one embodiment, the matrix resin composition contains (a) a low-molecular-weight PPE having a number-average molecular weight of 1,000 to 5,000, (b) a crosslinking agent, and / or (c) a silica filler, and may optionally contain (d) an organic peroxide, (e) a thermoplastic resin, and / or (f) a flame retardant. The matrix resin composition may also be formed into a matrix resin composition varnish containing (g) an organic solvent. The following describes the components that can constitute the matrix resin composition.

[0048] [(a) Low molecular weight PPE] Low molecular weight PPEs contain phenylene ether units as repeating structural units. The phenylene groups in the phenylene ether units may or may not have substituents. As used herein, the term "polyphenylene ether" includes dimers, trimers, oligomers, and polymers.

[0049] The PPE may also contain other structural units in addition to phenylene ether units. The amount of the other structural units is typically 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or 5% or less of the total number of structural units. However, the amount of the other structural units may exceed 30% of the total number of structural units as long as it does not impair the effects of the present invention.

[0050] Specific examples of PPE include poly(2,6-dimethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenylene ether), copolymers of 2,6-dimethylphenol with other phenols (e.g., 2,3,6-trimethylphenol, 2-methyl-6-butylphenol, etc.), PPE copolymers obtained by coupling 2,6-dimethylphenol with biphenols or bisphenols, and PPEs with linear or branched structures obtained by heating poly(2,6-dimethyl-1,4-phenylene ether) or the like with phenolic compounds such as bisphenols or trisphenols in toluene in the presence of an organic peroxide to undergo a redistribution reaction. Further examples include PPEs in which the terminal hydroxyl groups of these PPEs have been replaced with functional groups containing carbon-carbon double bonds. Specific examples of the functional group having a carbon-carbon double bond include a vinyl group, an allyl group, an isopropenyl group, a 1-butenyl group, a 1-pentenyl group, a p-vinylphenyl group, a p-isopropenylphenyl group, a m-vinylphenyl group, a m-isopropenylphenyl group, an o-vinylphenyl group, an o-isopropenylphenyl group, a p-vinylbenzyl group, a p-isopropenylbenzyl group, a m-vinylbenzyl group, a m-isopropenylbenzyl group, an o-vinylbenzyl group, an o-isopropenylbenzyl group, a p-vinylphenylethenyl group, a p-vinylphenylpropenyl group, a p-vinylphenylbutenyl group, a m-vinylphenylethenyl group, a m-vinylphenylpropenyl group, a m-vinylphenylbutenyl group, an o-vinylphenylethenyl group, an o-vinylphenylpropenyl group, an o-vinylphenylbutenyl group, a methacryl group, an acryl group, a 2-ethyl acryl group, and a 2-hydroxymethyl acryl group.

[0051] The low-molecular-weight PPE has a number-average molecular weight of 1,000 to 5,000. When the matrix resin composition of this embodiment contains such a low-molecular-weight PPE, an increase in viscosity of the matrix resin composition varnish can be suppressed, thereby improving the coatability of the matrix resin composition varnish onto a substrate. By improving the coatability, various properties required of the matrix resin composition or its cured product can also be improved. The number-average molecular weight of the low-molecular-weight PPE is preferably 1,000 to 3,500, or 1,500 to 3,000.

[0052] The matrix resin composition may contain one type of low-molecular-weight PPE (that is, PPE having a number-average molecular weight of 1,000 to 5,000), or a combination of two or more types of PPE having a number-average molecular weight of 1,000 to 5,000.

[0053] [(b) Crosslinking agent] In one embodiment, the matrix resin composition further comprises a crosslinking agent. In this embodiment, any crosslinking agent capable of initiating or accelerating a crosslinking reaction can be used. The number-average molecular weight of the crosslinking agent is preferably 9,000 or less, 8,000 or less, 7,000 or less, 6,000 or less, or 5,000 or less. A number-average molecular weight of 9,000 or less of the crosslinking agent can suppress an increase in the viscosity of the matrix resin composition varnish and achieve good resin fluidity during heat molding. From the viewpoint of prepreg coatability, the number-average molecular weight of the crosslinking agent is preferably 100 or more, 200 or more, 300 or more, 500 or more, or 1,000 or more. The number-average molecular weight of the crosslinking agent is a value measured using GPC in terms of standard polystyrene.

[0054] From the viewpoint of crosslinking reactivity, the crosslinking agent preferably has an average of two or more carbon-carbon unsaturated double bonds per molecule. The crosslinking agent may be composed of one or more compounds. When the crosslinking agent is a polymer or oligomer, the carbon-carbon unsaturated double bond is typically located at the molecular end (i.e., the end of the main chain or branched chain), but this embodiment is not limited thereto.

[0055] Specifically, the crosslinking agent is preferably a styrene-butadiene copolymer containing 20% ​​by mass or more of styrene-derived structural units. Such crosslinking agents are highly compatible with the PPE composition fibers and the PPE (preferably low-molecular-weight PPE) used as the matrix resin, and tend to improve the heat resistance and interlayer adhesion of the substrate. Commercially available crosslinking agents may be used, such as Ricon 100, Ricon 181, Ricon 257, and Ricon 184, both of which are manufactured by Cray Valley.

[0056] Other examples of crosslinking agents include trialkenyl isocyanurate compounds such as triallyl isocyanurate (TAIC), trialkenyl cyanurate compounds such as triallyl cyanurate (TAC), polyfunctional methacrylate compounds having two or more methacrylic groups in the molecule, polyfunctional acrylate compounds having two or more acrylic groups in the molecule, polyfunctional vinyl compounds having two or more vinyl groups in the molecule such as polybutadiene, vinylbenzyl compounds such as divinylbenzene having vinylbenzyl groups in the molecule, and polyfunctional maleimide compounds having two or more maleimide groups in the molecule such as 4,4'-bismaleimidediphenylmethane. These crosslinking agents are preferably used in combination with a styrene-butadiene copolymer. By including at least one of the compounds described above in the crosslinking agent, the crosslink density during the curing reaction (crosslinking reaction) is further increased, which tends to further improve the heat resistance of the cured product of the matrix resin composition.

[0057] In one embodiment, the crosslinking agent is a styrene-butadiene copolymer having a number-average molecular weight of 1,000 to 7,000 and containing 5% or more by mass of structural units derived from styrene. Such styrene-butadiene copolymers are particularly preferred in terms of resin permeability and adhesiveness to PPE composition fibers. The number-average molecular weight of the styrene-butadiene copolymer is more preferably 1,000 to 6,000, or 1,000 to 5,000. The proportion of styrene-derived structural units in the styrene-butadiene copolymer is preferably 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, and preferably 95% by mass or less, 90% by mass or less, or 85% by mass or less. In one embodiment, the styrene-derived structural units can be confirmed by NMR.

[0058] In the matrix resin composition, the mass ratio of matrix resin (in one embodiment, low-molecular-weight PPE):crosslinking agent is preferably 25:75 to 95:5, more preferably 32:68 to 85:15, from the viewpoint of balancing the low dielectric constant and low dielectric loss tangent upon curing with the crosslink density of the crosslinked structure.

[0059] The content of the crosslinking agent in the matrix resin composition is preferably 3% by mass or more, 4% by mass or more, or 5% by mass or more, and preferably 30% by mass or less, 25% by mass or less, or 20% by mass or less.

[0060] [(c) Silica filler] The matrix resin composition may contain a silica filler. The silica filler is preferably spherical silica. In order to improve the impregnation of the matrix resin into the PPE resin composition fibers, the average particle size of the silica filler is preferably 2 μm or less, 1.8 μm or less, or 1.5 μm or less. In order to improve the dispersibility of the silica filler in the matrix resin and to improve the dimensional stability (warpage) of the substrate, the average particle size of the silica filler is preferably 0.1 μm or more, 0.2 μm or more, or 0.3 μm or more. In one embodiment, the average particle size is a value measured by dynamic light scattering (DLS).

[0061] The content of the silica filler in the matrix resin composition is preferably 10 to 50 mass%, 10 to 45 mass%, or 10 to 40 mass%, in terms of easily achieving high dispersibility and providing excellent elastic modulus and dimensional stability (warpage) of the substrate.

[0062] The silica filler may be surface-treated with a silane coupling agent or the like.

[0063] [(d) Organic peroxide] In this embodiment, any organic peroxide capable of promoting the polymerization reaction of a matrix resin composition containing a matrix resin (in one embodiment, a low molecular weight PPE) and a crosslinking agent can be used. Examples of organic peroxides include benzoyl peroxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, di-t-butyl peroxide, t-butylcumyl peroxide, di(2-t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumyl peroxide, di-t-butylperoxyisophthalate, t-butylperoxybenzoate, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide, and trimethylsilyltriphenylsilyl peroxide. Radical generators such as 2,3-dimethyl-2,3-diphenylbutane can also be used as a reaction initiator for the matrix resin composition. Among these, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, di(2-t-butylperoxyisopropyl)benzene, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexane are preferred from the viewpoint of providing a cured product having excellent heat resistance and mechanical properties, as well as a low dielectric constant and a low dielectric dissipation factor.

[0064] The one-minute half-life temperature of the organic peroxide is preferably 155°C to 185°C, or 160°C to 180°C, or 165°C to 175°C. In this specification, the one-minute half-life temperature is the temperature at which the organic peroxide decomposes and the amount of active oxygen is reduced to half in one minute. The one-minute half-life temperature is determined by a method in which an organic peroxide is dissolved in a solvent inert to radicals, such as benzene, to a concentration of 0.05 mol / L to 0.1 mol / L, and the organic peroxide solution is thermally decomposed under a nitrogen atmosphere.

[0065] When the one-minute half-life temperature of the organic peroxide is 155°C or higher, the matrix resin (in one embodiment, low-molecular-weight PPE) can be sufficiently melted before the reaction with the crosslinking agent can be initiated when the matrix resin composition is subjected to heat and pressure molding, which tends to result in excellent moldability. On the other hand, when the one-minute half-life temperature of the organic peroxide is 185°C or lower, the decomposition rate of the organic peroxide is sufficient under normal heat and pressure molding conditions (e.g., a maximum temperature of 200°C), allowing the crosslinking reaction with the crosslinking agent to proceed efficiently and slowly, making it possible to form a cured product with good electrical properties (particularly dielectric tangent).

[0066] Examples of organic peroxides having a one-minute half-life temperature in the range of 155°C to 185°C include t-hexylperoxyisopropyl monocarbonate (155.0°C) (the one-minute half-life temperature is in parentheses, the same applies below), t-butylperoxy-3,5,5-trimethylhexanoate (166.0°C), t-butylperoxylaurate (159.4°C), t-butylperoxyisopropyl monocarbonate (158.8°C), t-butylperoxy 2-ethylhexyl monocarbonate (161.4°C), t-hexylperoxybenzoate (160.3°C), 2,5-dimethyl-2,5-di(benzoylperoxy)hexano ... Examples of peroxides include hexane (158.2°C), t-butyl peroxyacetate (159.9°C), 2,2-di-(t-butylperoxy)butane (159.9°C), t-butyl peroxybenzoate (166.8°C), n-butyl 4,4-di-(t-butylperoxy)valerate (172.5°C), di(2-t-butylperoxyisopropyl)benzene (175.4°C), dicumyl peroxide (175.2°C), di-t-hexyl peroxide (176.7°C), 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (179.8°C), and t-butylcumyl peroxide (173.3°C).

[0067] The content of the organic peroxide is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, based on 100% by mass of the total mass of the matrix resin (in one embodiment, the low-molecular-weight PPE) and the crosslinking agent, from the viewpoint of being able to increase the reaction rate, and is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, from the viewpoint of being able to keep the dielectric constant and dielectric dissipation factor of the obtained cured product low.

[0068] [(e) Thermoplastic resin] The matrix resin composition may contain a thermoplastic resin other than the matrix resin (low-molecular-weight PPE in one embodiment) and the crosslinking agent. The thermoplastic resin is preferably at least one selected from the group consisting of block copolymers of vinyl aromatic compounds and aliphatic hydrocarbon compounds having carbon-carbon unsaturated double bonds, hydrogenated products thereof (hydrogenated block copolymers obtained by hydrogenating block copolymers of vinyl aromatic compounds and aliphatic hydrocarbon compounds having carbon-carbon unsaturated double bonds), and homopolymers of vinyl aromatic compounds. The content of vinyl aromatic compound-derived units in the block copolymer or hydrogenated product thereof is preferably 20% by mass or more, and can be 99% by mass or less. Having a content of vinyl aromatic compound-derived units in the block copolymer or hydrogenated product thereof of 20% by mass or more further improves the compatibility between the matrix resin (low-molecular-weight PPE in one embodiment) and the thermoplastic resin, which tends to further improve the adhesion strength between the cured prepreg and the metal foil.

[0069] The vinyl aromatic compound may be any compound having an aromatic ring and a vinyl group in the molecule, such as styrene. The aliphatic hydrocarbon compound having a carbon-carbon unsaturated double bond may be any compound having a linear or branched chain structure in the molecule, such as ethylene, propylene, butylene, isobutylene, butadiene, and isoprene. From the viewpoint of achieving even better compatibility with the matrix resin (low-molecular-weight PPE in one embodiment), the thermoplastic resin is preferably at least one selected from the group consisting of styrene-butadiene block copolymers, styrene-ethylene-butadiene block copolymers, styrene-ethylene-butylene block copolymers, styrene-butadiene-butylene block copolymers, styrene-isoprene block copolymers, styrene-ethylene-propylene block copolymers, styrene-isobutylene block copolymers, hydrogenated styrene-butadiene block copolymers, hydrogenated styrene-ethylene-butadiene block copolymers, hydrogenated styrene-butadiene-butylene block copolymers, hydrogenated styrene-isoprene block copolymers, and styrene homopolymers (polystyrene), and more preferably at least one selected from the group consisting of styrene-butadiene block copolymers, hydrogenated styrene-butadiene block copolymers, and polystyrene.

[0070] The hydrogenation rate of the hydrogenated product is not particularly limited, and some carbon-carbon unsaturated double bonds derived from the aliphatic hydrocarbon compound having a carbon-carbon unsaturated double bond may remain.

[0071] The weight-average molecular weight of the thermoplastic resin is preferably 30,000 to 300,000, more preferably 31,000 to 290,000. When the weight-average molecular weight is 30,000 or more, the matrix resin composition of this embodiment tends to have better heat resistance when cured. When the weight-average molecular weight is 300,000 or less, the matrix resin composition of this embodiment tends to have better resin fluidity during thermoforming. The weight-average molecular weight is a value determined by gel permeation chromatography using standard polystyrene conversion.

[0072] The content of the thermoplastic resin is preferably 2 to 20 parts by mass, based on 100 parts by mass of the total of the matrix resin (in one embodiment, the low-molecular-weight PPE) and the crosslinking agent. When the content is 2 parts by mass or more, the matrix resin composition of this embodiment tends to exhibit a low dielectric constant, a low dielectric loss tangent, and good adhesion to the metal foil when cured. When the content is 20 parts by mass or less, the matrix resin composition of this embodiment tends to have even better resin fluidity during heat molding.

[0073] [(f) Flame retardants] The matrix resin composition preferably contains a flame retardant. From the viewpoint of improving heat resistance, the flame retardant is preferably one that is incompatible with other components contained in the matrix resin composition after curing. Preferably, the flame retardant is incompatible with the matrix resin (low-molecular-weight PPE in one embodiment) and / or the crosslinking agent in the matrix resin composition after curing. Examples of flame retardants include inorganic flame retardants such as antimony trioxide, aluminum hydroxide, magnesium hydroxide, and zinc borate; aromatic bromine compounds such as hexabromobenzene, decabromodiphenylethane, 4,4-dibromobiphenyl, and ethylenebistetrabromophthalimide; and phosphorus-based flame retardants such as resorcinol bis-diphenylphosphate and resorcinol bis-dixylenylphosphate. These flame retardants may be used alone or in combination of two or more. Among these, decabromodiphenylethane is preferred from the viewpoint of achieving a low dielectric constant and a low dielectric loss tangent when the matrix resin composition is cured.

[0074] The content of the flame retardant is not particularly limited, but from the viewpoint of maintaining flame retardancy at the UL Standard 94V-0 level, it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, relative to 100 parts by mass of the total of the matrix resin (low-molecular-weight PPE in one embodiment) and the crosslinking agent. Furthermore, from the viewpoint of maintaining low dielectric constant and dielectric loss tangent of the obtained cured product, the content of the flame retardant is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0075] In addition to the above components, the matrix resin composition may further contain additives such as a heat stabilizer, an antioxidant, a UV absorber, a surfactant, and a lubricant.

[0076] [(g) Organic solvent] The matrix resin composition may be in the form of a matrix resin composition varnish containing an organic solvent, from the viewpoint of obtaining suitable fluidity when impregnating a resin fiber sheet. In the prepreg production process, it is preferable to impregnate a resin fiber sheet with the matrix resin composition varnish and then dry and remove the solvent using a hot air dryer or the like. The solid components in the matrix resin composition may be dissolved or dispersed in the varnish. The amount of the organic solvent may be appropriately adjusted so that the fluidity of the matrix resin composition varnish falls within a suitable range. For example, the amount of the solvent in the matrix resin composition varnish may be 20 to 80% by mass, 30 to 70% by mass, or 40 to 60% by mass.

[0077] From the viewpoints of the solubility of components in the matrix resin composition and the coatability of the resin fiber sheet, preferred organic solvents are methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, and chloroform. These organic solvents are used singly or in combination. On the other hand, it is preferable that the organic solvent is substantially free of aromatic compounds (i.e., compounds having an aromatic ring), such as toluene and xylene. In one embodiment, the organic solvent is substantially free of aromatic compounds. Specifically, the organic solvent being substantially free of aromatic compounds means that the content of aromatic compounds in the organic solvent is less than 1% by mass, and may be 0.5% by mass or less, 0.2% by mass or less, 0.1% by mass or less, or 0% by mass. When the content of aromatic compounds is less than 1% by mass, the tensile strength of the prepreg after coating can be maintained satisfactorily. In another embodiment, the organic solvent is substantially free of toluene. Specifically, the organic solvent being substantially free of toluene means that the toluene content in the organic solvent is less than 1% by mass, and may be 0.5% by mass or less, 0.2% by mass or less, 0.1% by mass or less, or 0% by mass.

[0078] <Uses of prepreg> The prepreg of this embodiment can be used, for example, to form an insulating layer of a printed wiring board, or a build-up layer of a printed wiring board (that is, a wiring layer of the board when the printed wiring board is a build-up board).

[0079] <Prepreg with support> This embodiment also provides a prepreg with a support, which has a support and the prepreg of this embodiment supported on the support. The prepreg with a support may have a support on one or both sides of the prepreg. Examples of the prepreg with a support include a resin-coated metal foil and an interlayer insulating material. The support may be a resin film, a metal foil, or the like. The (a) low-molecular-weight PPE, (b) crosslinking agent, (c) silica filler, (d) organic peroxide, (e) thermoplastic resin, (f) flame retardant, and (g) organic solvent can each be those described above.

[0080] Examples of resin films include films of one or more polymers selected from polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic polymers such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, cellulose polymers such as triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimides, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, with polyethylene terephthalate being particularly preferred due to its low cost.

[0081] Examples of metal foils include copper foil and aluminum foil, with copper foil being preferred. The copper foil may be a foil made of copper alone, or a foil made of an alloy of copper and other metals (e.g., one or more selected from tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0082] The surface of the support to be bonded to the prepreg may be subjected to a surface treatment such as matte treatment or corona treatment.

[0083] <Method of manufacturing prepreg with support> The method for producing a prepreg with a support body in this embodiment is as follows: continuously unwinding the support; a first coating step of continuously coating a matrix resin composition varnish onto the support; A step of unwinding the resin fiber sheet of the present embodiment by applying tension while contacting it with a non-specular roll; a step of contacting the matrix resin composition varnish applied to the support with the surface of the resin fiber sheet to obtain a first resin fiber sheet composite; a first drying step of drying the first resin fiber sheet composite; may include:

[0084] The above method is a second coating step of continuously coating a matrix resin composition varnish onto the first resin fiber sheet composite dried in the first drying step to obtain a second resin fiber sheet composite; a second drying step of drying the second resin fiber sheet composite; It may further include.

[0085] <Coating process> In the coating step, the matrix resin varnish is continuously applied to the support being fed. The method for applying the matrix resin composition varnish to the support is not particularly limited, and various methods, such as a slot die, gravure coater, bar coater, roll coater, doctor coater, PDN coater, blade coater, and impregnation coater, can be used. These methods can be appropriately selected taking into consideration the thickness of the coating liquid layer to be produced, the physical properties of the materials such as the coating liquid, and the coating conditions.

[0086] <Resin fiber sheet unwinding process> In this step, in parallel with the application step, the resin fiber sheet may be unwound under tension while being in contact with a non-specular roll. The roll that unwound the resin fiber sheet may be provided with a unit that detects the tension of the resin fiber sheet and a unit that controls the tension, and the tension may be controlled by these.

[0087] [Non-mirror roll] When continuously producing a prepreg with a support, it is preferable to unwind the resin fiber sheet while it is in contact with a non-specular roll. A non-specular roll can diffusely reflect reflected light when irradiated with light, has good sliding properties with the resin fiber sheet, and is easy to control tension, thereby suppressing wrinkle defects. A preferred non-specular roll is a matte roll that has been blasted to create a fine irregularity on the roll surface. A preferred non-specular roll is a roll in which a specular roll is laminated with a resin tape that has good sliding properties, such as a polytetrafluoroethylene (PTFE) or silicone resin tape. The degree of fine irregularity on the roll surface is preferably in the range of 0.5 to 10.0 μm, more preferably 0.6 to 5.0 μm, and even more preferably 0.7 to 3.0 μm, in terms of arithmetic mean roughness (Ra).

[0088] When Ra is 0.5 μm or more, the sliding property between the roll and the resin fiber sheet is good, making it easier to control the tension.When Ra is 10.0 μm or less, localized friction such as the fibers of the resin fiber sheet getting caught on the convex parts of the fine irregularities is less likely to occur, reducing damage such as fraying of the fibers of the resin fiber sheet.

[0089] The arithmetic mean roughness (Ra) of the fine irregularities on the roll surface can be measured using an optical microscope with a confocal optical system. For example, the OPTELICS S130 device manufactured by Lasertec Corporation is suitable. The Ra of a non-specular roll is measured under the following conditions: After acquiring data on the irregularities of the roll surface using an objective lens magnification of 20x and a wavelength selection of 546 nm, the processing range (line ROI button) of the Z Image data is selected so that the processing range is approximately 100 μm in the direction parallel to the roll width (i.e., the direction of the rotation axis), and the arithmetic mean roughness (Ra) is calculated in LM measurement mode. The Ra value is calculated by measuring five arbitrary positions where the resin fiber sheet comes into contact, and the average value is used.

[0090] As another preferred embodiment of the method for producing a prepreg with a support, a production method including a step of laminating a resin fiber sheet on the surface of a matrix resin layer that is solid at room temperature and formed on a support, and then heating and pressurizing the surface of the resin fiber sheet opposite the matrix resin layer side while the surface is laminated on one or both sides of a substrate. The substrate may be the prepreg or flexible film of the present disclosure. In one embodiment, the flexible film may be made of the same material as the support of the present disclosure. Heating is preferably carried out to a temperature equal to or higher than the glass transition temperature (Tg) of the matrix resin that is solid at room temperature, and the pressure applied can be adjusted appropriately depending on the type of resin and heating conditions.

[0091] <Laminated plate (laminate body)> This embodiment also provides a laminate (laminate) obtained using the prepreg or supported prepreg of this embodiment. For example, a metal-clad laminate can be obtained by laminating and curing the prepreg of this embodiment and a metal foil. The metal-clad laminate preferably has a configuration in which a cured prepreg (also referred to as a "cured composite") and a metal foil are laminated and adhered together, and is suitable for use as a material for electronic circuit boards. Examples of metal foil include aluminum foil and copper foil, with copper foil being preferred due to its low electrical resistance. The cured composite to be combined with the metal foil may be one or more sheets, and the metal foil is layered on one or both sides of the composite depending on the application to form a laminate. Examples of methods for producing a laminate include forming the prepreg described above, layering it on a metal foil, and then curing the matrix resin composition to obtain a laminate in which the cured laminate and the metal foil are layered. Another example of a method for producing a laminate includes forming the prepreg, laminating a resin fiber sheet thereon, and then laminating another prepreg on top of the resin fiber sheet, and then heating and pressurizing the resulting laminate under vacuum conditions to obtain a laminate.

[0092] <Printed wiring board> The printed wiring board according to the present embodiment may be a metal-clad laminate from which a portion of the metal foil has been removed, and may include an insulating layer formed from a cured product of the prepreg according to the present embodiment, or a build-up insulating layer formed from a cured product of the prepreg according to the present embodiment. The printed wiring board of this embodiment can typically be formed by a method of pressurizing and heat molding using the prepreg of this embodiment described above. Examples of the substrate include the same resin fiber sheet as described above for the prepreg. By being manufactured from the prepreg of this embodiment, the printed wiring board of this embodiment has excellent heat resistance and electrical properties (low dielectric constant and low dielectric loss tangent), and can suppress fluctuations in electrical properties due to environmental changes. It also has excellent insulation reliability and mechanical properties.

[0093] <Semiconductor device> This embodiment also provides a semiconductor device including the printed wiring board of this embodiment, that is, the semiconductor device can be manufactured using the printed wiring board of this embodiment.

[0094] Examples of semiconductor devices include various semiconductor devices applied to electrical appliances (for example, computers, mobile phones, digital cameras, and televisions), vehicles (for example, motorcycles, automobiles, trains, ships, and aircraft), and the like.

[0095] The semiconductor device according to this embodiment can be manufactured by mounting a semiconductor chip, which is a component, on a conductive portion of a printed wiring board, i.e., a portion of the printed wiring board that transmits an electrical signal. The conductive portion may be located on the surface of the semiconductor device or embedded inside the semiconductor device, and its location is not limited. Furthermore, the semiconductor chip encompasses all electrical circuit elements formed using semiconductor materials.

[0096] The mounting method of the semiconductor chip when manufacturing the semiconductor device according to this embodiment is not particularly limited, and examples thereof include wire bonding mounting, flip chip mounting, a mounting method using BBUL (Bumpless Build-Up Layer), a mounting method using anisotropic conductive film (ACF), a mounting method using non-conductive film (NCF), etc. BBUL is a mounting method in which the semiconductor chip is directly embedded in a recess in a printed wiring board without providing bumps, thereby connecting the semiconductor chip to the wiring on the printed wiring board. [Example]

[0097] The present embodiment will be described in detail below with reference to examples, but the present embodiment is not limited to these examples.

[0098] <Preparation of PPE composition for resin fiber sheet> PPE compositions were obtained by melt-kneading PPE, sPS, LCP, or atactic PS (polystyrene) having the number-average molecular weights (Mn) shown in Table 1 at 320°C in a twin-screw extruder in the blending ratios (by mass) shown in Table 1. The materials used are as follows: PPE (product name "S202A", manufactured by Asahi Kasei, Mn: 15,000) PPE (product name "S203A", manufactured by Asahi Kasei, Mn: 11,000) sPS (product name "60ZC", manufactured by Idemitsu Kosan, Mw: 250,000) sPS (product name "90ZC", manufactured by Idemitsu Kosan, Mw: 200,000) LCP (product name "A-8100", manufactured by Ueno Pharmaceuticals, melting point 220°C) Atactic PS (product name "GPPS680", manufactured by PS Japan, Mw: 200,000)

[0099] <Production of resin fibers> The compositions shown in Table 1 were extruded and spun through a spinneret in a melt spinning machine to produce multifilaments. The spinning temperature was adjusted to a spinneret surface temperature of 293°C. The spinneret had a hole diameter of 0.23 mm and 24 holes. The spinning speed was also changed because the appropriate spinning speed differs depending on the resin composition. After spinning, the fibers were stretched at a preheating temperature of 100°C and a draw ratio resulting in an elongation of 20%, and then heat-set at 155°C. A fiber of 46 dtex and 24 filaments was wound at a relaxation ratio of 0.980. Two of these fibers were combined to finally obtain a fiber of 92 dtex and 48 filaments.

[0100] <Production of cloth as a resin fiber sheet> The above multifilament was woven, physically processed, desized, surface treated, and opened to produce a cloth with a warp and weft density of 30 threads / inch, a thickness of 100 μm, and an opening ratio as shown in Table 1.

[0101] <Preparation of Matrix Resin Composition Varnish> [material] The following materials were used: (low molecular weight PPE) Methacrylic-terminated PPE (product name "SA9000", manufactured by Sabic Innovative Plastics, Mn: 2756) (Crosslinking agent) ·RICON100 (manufactured by CRAY VALLEY, molecular weight: 4500) TAIC (Mitsubishi Chemical Corporation, molecular weight: 249.7) (organic peroxide) Bis(1-tert-butylperoxy-1-methylethyl)benzene (product name "Perbutyl P", manufactured by NOF Corporation) (Flame retardant) Decabromodiphenylethane (product name "SAYTEX8010", manufactured by Albemarle) (Silica filler) Spherical silica, average particle size 1.1 μm (Admatechs, SO-C4)

[0102] Each material was weighed in advance, and methyl ethyl ketone (as an organic solvent) was placed in a container. While stirring with a mixer, the following materials were added in the mass ratios shown below, and mixed for 5 hours or more to prepare a matrix resin composition varnish with a solids content of 50 mass%. Varnish 1: Low molecular weight PPE / RICON100 / TAIC / organic peroxide / flame retardant / silica filler = 55 / 10 / 10 / 1 / 14 / 10 Varnish 2: Low molecular weight PPE / TAIC / organic peroxide / flame retardant / silica filler = 55 / 20 / 1 / 14 / 10

[0103] <Prepreg production> [Examples 1 to 7, Comparative Examples 1 and 2] The cloth was impregnated with the resin composition varnish at a constant tension of about 100 N / m, scraped off with a slit, and dried at 120°C for 3 minutes to prepare a prepreg.

[0104] [Reference example 1] A prepreg was prepared in the same manner as in Example 1, except that a low dielectric constant glass cloth L2116 (weave density 60×58 threads / inch, thickness 95 μm, opening ratio 5%) was used.

[0105] <Evaluation method> (1) Number average molecular weight The number-average molecular weight and weight-average molecular weight were determined by gel permeation chromatography (GPC) by comparing the elution time with that of standard polystyrene of known molecular weight. Specifically, a measurement sample with a sample concentration of 0.2 w / vol% (solvent: chloroform) was prepared, and the measurement was performed using a HLC-8220GPC (Tosoh Corporation) measurement device, a Shodex GPC KF-405L HQ x 3 (Showa Denko K.K.) column, chloroform as the eluent, an injection volume of 20 μL, a flow rate of 0.3 mL / min, a column temperature of 40°C, and a detector: RI.

[0106] (2) Single yarn diameter The cross sections of 100 randomly selected filaments were imaged using a scanning electron microscope (Hitachi Science Systems SEMEDX3 Type N), the diameters were measured, and the average values ​​were calculated. .

[0107] (3) Weave density of the cross section Measurements were taken in both the warp and weft directions in accordance with JIS R3420.

[0108] (4) Cloth opening ratio A 100 mm square (approximately 4 inch wide) was cut from the center of the cloth roll, and the total warp width (i.e., the total width of the warp threads in the entire 100 mm × 100 mm cloth) and total weft width (i.e., the total width of the weft threads in the entire 100 mm × 100 mm cloth) were measured in an optical microscope image of the cloth surface, and the average values ​​for each of the warp and weft threads were calculated. Based on this average value and the weave density of the warp and weft threads calculated above, the opening ratio was calculated according to the following formula. Opening rate = (25.4 mm ÷ warp density - warp width mm) x (25.4 mm ÷ weft density - weft width mm) ÷ ((25.4 mm ÷ warp density) x (25.4 mm ÷ weft density))

[0109] (5) Thickness of the cloth Measurements were carried out in accordance with JIS R3420.

[0110] (6) Weavability The occurrence of yarn breakage and machine stoppage during weaving was evaluated relatively within the examples and comparative examples, with A being good, B being slightly bad, and C being bad.

[0111] (7) Dielectric constant and dielectric loss tangent (electrical properties, 10 GHz) Six prepregs were stacked and heated from room temperature at a rate of 3°C / min while applying a pressure of 5kg / cm 2 After the temperature reached 130°C, the material was heated at a rate of 3°C / min while applying a pressure of 40 kg / cm. 2 After the temperature reached 200°C, the pressure was increased to 40 kg / cm while maintaining the temperature at 200°C. 2The laminate was fabricated by vacuum pressing under the conditions of 10 GHz and 60 minutes. The dielectric constant and dielectric loss tangent of this laminate were measured by the cavity resonance method. The measurement equipment used was a network analyzer (N5230A, manufactured by Agilent Technologies) and a cavity resonator (Cavity Resonator CP series, manufactured by Kanto Electronics Application Development Co., Ltd.).

[0112] (8) Amount of board warpage As in (7) above, two prepregs were stacked to prepare a laminate, and four 50 mm square specimens were randomly cut out. The amount of warpage at each of the four corners of each specimen (the larger of the front and back) was measured with a vernier caliper. The average value of the four corners was calculated and used as the amount of warpage of the substrate. The results are shown in Table 1.

[0113] (9) Toughness Fiber samples were measured for tensile strength and elongation in accordance with JIS L1013 (2010), and a tensile strength-elongation curve was plotted. The test conditions were a constant-speed extension type tester, a grip distance of 20 cm, and a pulling speed of 20 cm / min. If the tensile strength at break was less than the maximum strength, the maximum tensile strength and the elongation at that time were measured. Furthermore, toughness, which is the product of strength (A) and the square root of elongation (B), was calculated. Strength (A) = Tensile strength at break (cN) / Fineness (dtex) Elongation (B) = Elongation at break (%) Toughness = (A) × {(B)} 1 / 2

[0114] (10) Thermal stress rise temperature Measurements were taken at a heating rate of 150°C / min using an Intec KE-2S thermal stress measuring instrument (formerly Kanebo Engineering). The sample was 0.1m x 2 loops, and the initial tension was set to fineness (dtex) x 0.03cN. The thermal stress rise temperature is the temperature at which the stress rises.

[0115] (11) Overall rating Products that satisfied all of the following criteria were rated as excellent: toughness 5 to 30, thermal stress rise temperature 100 to 190°C, weavability A, cloth dielectric constant 3.0 or less, cloth dielectric dissipation factor 0.001 or less, and substrate warpage 5 mm or less. Products that satisfied the other above conditions but weavability B were rated as good, and all other conditions were rated as poor.

[0116] As shown in Table 1, the overall evaluation was excellent or good under the conditions shown in the examples, but was poor under the conditions shown in the comparative examples.

[0117] [Table 1]

Claims

1. A resin fiber sheet made of polyphenylene ether composition fibers, The polyphenylene ether composition fiber contains 10% by mass or more and 50% by mass or less of polyphenylene ether and 50% by mass or more and 90% by mass or less of syndiotactic polystyrene, the content of components other than the polyphenylene ether and the syndiotactic polystyrene in the polyphenylene ether composition fiber is 0% by mass or more and 5% by mass or less; The polyphenylene ether composition fiber has a single fiber diameter of 1 to 50 μm.

2. The resin fiber sheet according to claim 1, wherein the polyphenylene ether composition fiber has a toughness of 5 or more and 30 or less.

3. The resin fiber sheet according to claim 1 or 2, wherein the polyphenylene ether composition fiber has a thermal stress rise temperature of 100°C or higher and 190°C or lower.

4. The toughness of the polyphenylene ether composition fiber is 5 or more and 30 or less, and The resin fiber sheet according to claim 1 or 2, wherein the polyphenylene ether composition fiber has a thermal stress rise temperature of 100°C or higher and 190°C or lower.

5. The resin fiber sheet according to claim 1 or 2, wherein the number average molecular weight of the polyphenylene ether is 9000 to 21000.

6. The resin fiber sheet according to claim 1 or 2, wherein the resin fiber sheet is a resin fiber cloth woven to a warp and weft density of 20 to 200 threads / inch and an opening rate of 1 to 30%.

7. The resin fiber sheet according to claim 4, wherein the resin fiber sheet is a resin fiber cloth woven to have a warp and weft weaving density of 20 to 90 threads / inch and an opening rate of 1 to 30%.

8. The resin fiber sheet is a nonwoven fabric, 3. The resin fiber sheet according to claim 1, wherein the polyphenylene ether composition fiber is composed of single yarns having a single yarn diameter of 1 to 50 μm.

9. A prepreg comprising the resin fiber sheet according to claim 1 or 2 and a matrix resin composition.

10. 10. The prepreg according to claim 9, wherein the matrix resin composition comprises at least one thermosetting resin selected from the group consisting of epoxy resins, cyanate ester resins, bismaleimide resins, polyphenylene ether resins, and bismaleimide-triazine resins.

11. The prepreg according to claim 10, wherein the polyphenylene ether resin comprises a low molecular weight polyphenylene ether having a number average molecular weight of 1,000 to 5,000.

12. The prepreg of claim 9 , wherein the matrix resin composition further comprises a silica filler.

13. 13. The prepreg according to claim 12, wherein the silica filler is spherical silica with an average particle size of 2 μm or less.

14. The prepreg according to claim 12, wherein the content of the silica filler in the matrix resin composition is 10 to 50 mass%.

15. The prepreg of claim 9 , wherein the matrix resin composition further comprises a crosslinker.

16. The prepreg according to claim 15, wherein the crosslinking agent is a styrene-butadiene copolymer having a number average molecular weight of 1000 to 7000 and containing 20% ​​by mass or more of structural units derived from styrene.

17. The prepreg according to claim 15, wherein the content of the crosslinking agent in the matrix resin composition is 3 to 30 mass%.

18. a varnish preparation step of preparing a matrix resin composition varnish containing a low-molecular-weight polyphenylene ether having a number-average molecular weight of 1,000 to 5,000 and an organic solvent; an impregnation step of impregnating the resin fiber sheet according to claim 1 or 2 with the matrix resin composition varnish; and a drying step of drying the resin fiber sheet impregnated with the matrix resin composition varnish; A method for producing a prepreg, comprising:

19. The method for producing a prepreg according to claim 18, wherein the organic solvent is substantially free of aromatic compounds.

20. The method for producing a prepreg according to claim 18 , wherein the matrix resin composition varnish further contains a silica filler.

21. The method for producing a prepreg according to claim 20, wherein the silica filler is spherical silica with an average particle size of 2 μm or less.

22. The method for producing a prepreg according to claim 18 , wherein the matrix resin composition varnish further contains a crosslinking agent.

23. The method for producing a prepreg according to claim 22, wherein the crosslinking agent is a styrene-butadiene copolymer having a number average molecular weight of 1000 to 7000 and containing 20% ​​by mass or more of structural units derived from styrene.

24. The method for producing a prepreg according to claim 18, wherein in the impregnation step, the resin fiber sheet is impregnated with the matrix resin composition varnish while applying a tension of 200 N / m or less.

25. The prepreg according to claim 9, which is used to form an insulating layer of a printed wiring board.

26. The prepreg according to claim 9, which is used to form a build-up insulating layer of a printed wiring board.

27. A prepreg with a support, comprising: the prepreg according to claim 9; and a support disposed on one or both sides of the prepreg.

28. The prepreg with support according to claim 27, wherein the support is a resin film or a metal foil.

29. continuously unwinding the support; a first coating step of continuously coating the support with a matrix resin composition varnish; A step of unwinding the resin fiber sheet according to claim 1 or 2 by applying tension to the resin fiber sheet while contacting it with a non-specular roll; a step of contacting the matrix resin composition varnish applied to the support with the surface of the resin fiber sheet to obtain a first resin fiber sheet composite; a first drying step of drying the first resin fiber sheet composite; A method for producing a prepreg with a support, comprising:

30. a second coating step of continuously coating a matrix resin composition varnish onto the first resin fiber sheet composite dried in the first drying step to obtain a second resin fiber sheet composite; a second drying step of drying the second resin fiber sheet composite; The method for producing a prepreg with a support body according to claim 29, further comprising:

31. A laminate comprising the prepreg according to claim 9.

32. A printed wiring board comprising an insulating layer formed from a cured product of the prepreg according to claim 25.

33. A printed wiring board comprising a build-up insulating layer formed from a cured product of the prepreg according to claim 26.

34. A semiconductor device comprising the printed wiring board according to claim 32.

35. A semiconductor device comprising the printed wiring board according to claim 33.

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