Glass cloth, prepreg and printed wiring board

Abstract

This invention provides a glass cloth. When this glass cloth is used in printed wiring boards, it can reduce time delay skew. The glass cloth of this invention uses glass fibers as both warp and weft yarns, and the ratio σt / σy of the standard deviation of the glass fiber bundle thickness of the warp yarns to the standard deviation σy of the glass fiber bundle thickness of the weft yarns is in the range of 0.3 to 0.9.

Description

Technical Field

[0001] This invention relates to glass cloth, prepreg, and printed wiring boards. Background Technology

[0002] Typically, the propagation speed of transmission lines formed on printed wiring boards is affected by the dielectric constant of the surrounding substrate. For example, in the case of microstrip lines, the propagation speed can be expressed by the following formula.

[0003] V=C / ε eff 1 / 2 Where C is the speed of light, ε eff The effective dielectric constant of the substrate.

[0004] In recent years, with the development of electronic devices, the demand for high-capacity, high-speed data communication technology has been increasing. At the same time, reducing the time delay skew between differential lines has become increasingly important for high-speed communication.

[0005] The glass cloth prepreg used in the aforementioned printed wiring boards has different dielectric properties between glass and resin, and the density distribution of the resin and glass cloth can affect the transmission of communication signals. For example, when differentially distributed lines are respectively arranged in the sparser and denser areas of the glass, the transmission signal between the lines will experience time delay skew due to the difference in effective dielectric constant, which may lead to a deterioration in transmission characteristics.

[0006] Previously, as a method to improve the uneven density of the glass cloth and reduce time delay skew, there is a known technique for making the glass density uniform by performing fiber opening treatment on the glass cloth and reducing the gaps in the glass cloth (for example, see Patent Document 1).

[0007] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2006-232952 Summary of the Invention

[0008] The problem that the invention aims to solve However, in order to stably perform the fiber opening process of the glass cloth, tension needs to be applied to the warp yarns of the glass cloth during the transport process. Therefore, the warp yarns are more difficult to open than the weft yarns. When the differential distribution lines are arranged along the warp direction, the density of the glass fibers is easily affected. As a result, when the glass cloth has a certain thickness, the effect of the density of the glass fibers is easily amplified. Therefore, in the printed wiring board using prepreg with added glass cloth, there is an increased time delay skew.

[0009] The purpose of this invention is to eliminate the above-mentioned problems and provide a glass cloth that can reduce delay skew when used in printed wiring boards.

[0010] Methods for solving problems The inventors have conducted extensive research on methods to reduce time delay skew in printed wiring boards using prepregs with added glass cloth. They discovered that even when the warp yarns cannot be fully opened compared to the weft yarns, the time delay skew of the printed wiring board can be reduced by controlling the time delay skew of the fiber bundle thickness between the warp and weft yarns within a certain range. They hypothesize that this is because, while suppressing the thickness deviation of the difficult-to-open warp yarns, the weft yarn thickness exhibits a certain degree of deviation, resulting in a moderate distribution of glass fibers and avoiding localized dense states. However, the present invention is not limited to the above hypothesis.

[0011] Therefore, in order to achieve the above objectives, the glass cloth of the present invention has the following technical content: the glass cloth uses glass fibers as warp and weft yarns, characterized in that the ratio of the standard deviation σt of the thickness of the glass fiber bundle in the warp yarn to the standard deviation σy of the thickness of the glass fiber bundle in the weft yarn, σt / σy, is in the range of 0.3 to 0.9.

[0012] By ensuring that the ratio σt / σy of the standard deviation of the glass fiber bundle thickness of the warp yarns to the standard deviation σy of the glass fiber bundle thickness of the weft yarns of the glass cloth is within the aforementioned range, the glass cloth of the present invention can reduce the time delay skew of the aforementioned printed wiring board.

[0013] Regarding the glass cloth of the present invention, if the ratio σt / σy of the standard deviation σt of the glass fiber bundle thickness of the warp yarns to the standard deviation σy of the glass fiber bundle thickness of the weft yarns exceeds 0.9, it is impossible to reduce the time delay skew of the printed wiring board. On the other hand, in the glass cloth of the present invention, it is technically difficult to achieve a ratio σt / σy of σt / σy of the standard deviation σt of the glass fiber bundle thickness of the warp yarns to the standard deviation σy of the glass fiber bundle thickness of the weft yarns being less than 0.3.

[0014] Furthermore, the open area ratio S of the glass cloth according to the present invention, which is calculated by the following formula (1), is preferably in the range of 90 to 100% based on the warp weaving density Wt, the average warp width Bt, the weft weaving density Wy, and the average weft width By.

[0015] (Equation 1) By making the fiber opening area ratio S within the aforementioned range, the glass cloth of the present invention can further reduce the time delay skew of the printed wiring board.

[0016] Furthermore, preferably, the ratio Rt / Ry of the difference between the maximum and minimum thickness of the glass fiber bundles of the warp yarns of the glass cloth of the present invention, i.e., the maximum-minimum difference Rt, to the difference between the maximum and minimum thickness of the glass fiber bundles of the weft yarns, i.e., the maximum-minimum difference Ry, is in the range of 0.3 to 0.9.

[0017] By keeping the ratio Rt / Ry within the aforementioned range, the glass cloth of the present invention can further reduce the time delay skew of the printed wiring board.

[0018] In addition, preferably, the warp yarn width opening rate Lt of the glass cloth of the present invention, calculated by the following formula (2), is in the range of 60 to 83%, and the weft yarn width opening rate Ly, calculated by the following formula (3), is, for example, 85% or more.

[0019] (Equation 2) (Equation 3) Even if the yarn width opening rate Lt of the warp yarn and the yarn width opening rate Ly of the weft yarn are respectively within the above range, the glass cloth of the present invention can reduce the time delay skew of the printed wiring board.

[0020] Furthermore, the thickness of the glass cloth of the present invention is preferably in the range of 18 to 100 μm. Even when the thickness of the glass cloth of the present invention is within the above range, the delay skew of the printed wiring board can be reduced.

[0021] Furthermore, the prepreg of the present invention is characterized by comprising the glass cloth of the present invention. By comprising the glass cloth of the present invention, the prepreg of the present invention can reduce the time delay skew of the printed wiring board.

[0022] In this case, the difference between the relative permittivity of the glass cloth and the relative permittivity of the matrix resin of the prepreg is preferably in the range of 1.5 to 3.0. Even when the difference between the relative permittivity of the glass cloth and the relative permittivity of the matrix resin of the prepreg is in the range of 1.5 to 3.0, the impact on communication signal transmission caused by the density of the resin and glass cloth in the printed wiring board can be reduced.

[0023] Furthermore, the printed wiring board of the present invention is characterized by comprising the prepreg of the present invention. By comprising the prepreg of the present invention in the printed wiring board of the present invention, delay skew can be reduced. Detailed Implementation

[0024] Next, embodiments of the present invention will be described in further detail.

[0025] The glass cloth of this embodiment is a glass cloth with glass fiber as the warp and weft yarn, wherein the glass fiber is a glass fiber bundle composed of multiple glass filaments.

[0026] In this embodiment, the ratio σt / σy of the standard deviation σt of the glass fiber bundle thickness of the warp yarns of the glass cloth to the standard deviation σy of the glass fiber bundle thickness of the weft yarns of the glass cloth is in the range of 0.3 to 0.9, preferably in the range of 0.35 to 0.85, more preferably in the range of 0.35 to 0.71, even more preferably in the range of 0.5 to 0.71, and most preferably in the range of 0.6 to 0.71. The glass fiber bundle thickness of the weft yarns and the glass fiber bundle thickness of the warp yarns of the glass cloth can be measured by the method described later.

[0027] Furthermore, the open area ratio S of the glass cloth in this embodiment, calculated by the warp yarn weaving density Wt, the average warp yarn width Bt, the weft yarn weaving density Wy, and the average weft yarn width By using the following formula (1), is preferably in the range of 90% to 100%. The warp and weft yarn widths of the glass cloth described above can be measured by the method described later, and the average warp yarn width Bt and the average weft yarn width By can be calculated respectively based on the measured warp and weft yarn widths. The aforementioned open fiber area ratio S is more preferably in the range of 95-100%, further preferably in the range of 96-99.9%, and most preferably in the range of 98.5-99.9%.

[0028] The warp yarn density Wt and the weft yarn density Wy are not particularly limited, and can each be in the range of 20 to 120 yarns / 25 mm. The warp yarn density Wt and the weft yarn density Wy can be different from each other. The warp yarn density Wt is more preferably in the range of 30 to 110 yarns / 25 mm, further preferably in the range of 40 to 100 yarns / 25 mm, and most preferably in the range of 50 to 70 yarns / 25 mm. The weft yarn density Wy is more preferably in the range of 30 to 110 yarns / 25 mm, further preferably in the range of 40 to 100 yarns / 25 mm, and most preferably in the range of 50 to 70 yarns / 25 mm.

[0029] Furthermore, in this embodiment, the ratio Rt / Ry of the difference between the maximum and minimum thickness of the glass fiber bundles of the warp yarns, i.e., the maximum-minimum difference Rt, and the difference between the maximum and minimum thickness of the glass fiber bundles of the weft yarns, i.e., the maximum-minimum difference Ry, is preferably in the range of 0.3 to 0.9.

[0030] The ratio of Rt / Ry is more preferably in the range of 0.4 to 0.9, further preferably in the range of 0.4 to 0.8, and most preferably in the range of 0.6 to 0.7.

[0031] In addition, the fiber opening rate Lt of the warp yarn, calculated by the following formula (2), is preferably in the range of 60 to 83%, and the fiber opening rate Ly of the weft yarn, calculated by the following formula (3), is preferably in the range of 85% or more.

[0032] (Equation 2) (Equation 3) The yarn width opening rate Lt of the aforementioned warp yarn is more preferably in the range of 63% to 83%, further preferably in the range of 63% to 75%, and most preferably in the range of 63% to 68%. Furthermore, the yarn width opening rate Ly of the aforementioned weft yarn is more preferably in the range of 88% or more, further preferably in the range of 90% or more, and most preferably in the range of 95% or more.

[0033] The warp yarn width opening rate Lt and the weft yarn width opening rate Ly can be calculated from the warp and weft yarn widths measured using the method described later.

[0034] Furthermore, the thickness of the glass cloth in this embodiment is preferably in the range of 18 to 100 μm. More preferably, the thickness of the glass cloth in this embodiment is in the range of 25 to 90 μm, even more preferably in the range of 30 to 80 μm, and most preferably in the range of 30 to 50 μm.

[0035] The thickness of the glass cloth mentioned above is the average value of the measurements taken at 15 points on the glass cloth using a micrometer, according to JIS R 3420:2013.

[0036] The glass cloth of this embodiment is a glass cloth woven from the above-mentioned glass fibers (glass fiber bundles) as warp and weft yarns, and can be manufactured, for example, by the following method.

[0037] First, a specified batch of glass (glass raw material) is melted and fiberized to obtain glass filaments. The diameter of the glass filaments is not particularly limited, but when used in printed wiring boards, the diameter is preferably in the range of 10 μm or less, more preferably in the range of 8 μm or less, and particularly preferably in the range of 3 μm to 7 μm.

[0038] The aforementioned glass filaments, for example, are bundled together in the range of 25 to 500, preferably 40 to 300, using a method that is already known, to form glass fibers. It should be noted that the process of melting and fiberizing a batch of glass to obtain glass filaments, and then bundling multiple of these glass filaments together to obtain glass fibers (glass fiber bundles) is called spinning.

[0039] The unit length mass of the aforementioned glass fiber (glass fiber bundle) is preferably in the range of 2 to 30 g / 1000 m, more preferably in the range of 4 to 25 g / 1000 m, and even more preferably in the range of 4 to 15 g / 1000 m.

[0040] The glass composition of the aforementioned glass fibers is not particularly limited. Examples include E-glass composition, high-strength and high-modulus glass composition, high-modulus and easily manufactured glass composition, or low-dielectric-constant and low-dielectric-loss tangent glass composition. For high-speed communication applications, low-dielectric-constant and low-dielectric-loss tangent glass composition is preferred, such as NE-glass, L-glass, or D-glass.

[0041] The above-mentioned E-glass composition is the most common glass composition, based on the total amount of glass fibers, including 52.0 to 56.0% by mass of SiO2, 12.0 to 16.0% by mass of Al2O3, a total of 20.0 to 25.0% by mass of MgO and CaO, and 5.0 to 10.0% by mass of B2O3.

[0042] The aforementioned high-strength, high-elasticity modulus glass composition comprises SiO2 in the range of 60.0–70.0% by mass relative to the total glass fiber content, Al2O3 in the range of 20.0–30.0% by mass, MgO in the range of 5.0–15.0% by mass, Fe2O3 in the range of 0–1.5% by mass, and Na2O, K2O, and Li2O in the range of 0–0.2% by mass. Preferably, the aforementioned high-strength, high-elasticity modulus glass composition contains Fe2O3 in the range of 0.15–1.50% by mass, ZrO2 in the range of 0.01–0.10% by mass, and Na2O, K2O, and Li2O in the range of 0.02–0.20% by mass.

[0043] The aforementioned high elastic modulus easy-to-manufacture glass composition includes SiO2 in the range of 57.0 to 60.0% by mass, Al2O3 in the range of 17.5 to 20.0% by mass, MgO in the range of 8.5 to 12.0% by mass, CaO in the range of 10.0 to 13.0% by mass, and B2O3 in the range of 0.5 to 1.5% by mass relative to the total amount of glass fibers, and together includes SiO2, Al2O3, MgO and CaO in the range of 98.0% or more.

[0044] The aforementioned low dielectric constant and low dielectric loss tangential glass composition includes SiO2 in the range of 48.0–62.0% by mass relative to the total amount of glass fibers, B2O3 in the range of 17.0–26.0% by mass, Al2O3 in the range of 9.0–18.0% by mass, CaO in the range of 0.1–9.0% by mass, MgO in the range of 0–6.0% by mass, Na2O, K2O and Li2O in the range of 0–0.5% by mass, TiO2 in the range of 0–5.0% by mass, SrO in the range of 0–6.0% by mass, F2 and Cl2 in the range of 0–3.0% by mass, and P2O5 in the range of 0–6.0% by mass.

[0045] Regarding the determination of the content of each component in the glass composition, Li, as a light element, can be measured using an ICP-based luminescence spectrophotometer, and other elements can be measured using a wavelength-dispersive X-ray fluorescence analyzer. Specifically, the content of each component in the glass composition can be measured using the following methods.

[0046] First, the glass cloth is cut to an appropriate size and placed in a platinum crucible. It is then melted in an electric furnace at a temperature of 1400–1650°C for 6 hours with stirring to obtain homogeneous molten glass. If the glass cloth surface has organic matter adhering to it, or if the glass fiber is primarily contained within organic matter (resin) as a reinforcing material, it can be heated in a muffle furnace at 300–650°C for 2–24 hours to remove the organic matter before proceeding with the above treatment.

[0047] Next, the obtained molten glass was poured onto a carbon plate to prepare glass cullets, which were then pulverized into powder to form glass powder. The glass powder was then decomposed by heating with acid, and Li, as a light element, was quantitatively analyzed using an ICP-based spectrophotometer. The glass powder was then pressed into disc-shaped samples using a press, and other elements were quantitatively analyzed using a wavelength-dispersive X-ray fluorescence spectrometer.

[0048] When performing quantitative analysis using a wavelength dispersive X-ray fluorescence analyzer, the following method can be employed. First, the content of each component in the test sample is measured using the fundamental parameter method. Then, based on the measurement results, at least three samples are prepared for establishing a standard curve, and the standard curve method is used for analysis. It should be noted that the content of each component in the above calibration curve samples can be quantitatively analyzed using an ICP emission spectrophotometer. Next, the above quantitative analysis results are converted into oxide content, and the content and total amount of each component are calculated accordingly. Based on these values, the content rate (mass%) of each component is determined.

[0049] Next, the glass fibers (glass fiber bundles) are used as warp or weft yarns and woven using a well-known loom to obtain the glass cloth of this embodiment. Examples of such looms include jet looms (air-jet or water-jet), shuttle looms, and rapier looms. Furthermore, examples of weaving methods using these looms include plain weave, satin weave, square plain weave, and twill weave; from a production efficiency perspective, plain weave is preferred.

[0050] In the aforementioned weaving process, a sizing agent can be used to bundle and protect the glass fibers (glass fiber bundles). For example, a sizing agent with a starch-based or PVA (polyvinyl alcohol) film composition can be used. The sizing agent may contain oils or softeners, etc.

[0051] In the glass cloth of this embodiment, the amount of sizing agent attached relative to 100 parts by weight of the glass fiber is preferably in the range of 0.1 to 5 parts by weight, more preferably in the range of 0.3 to 3 parts by weight, and even more preferably in the range of 0.5 to 2 parts by weight.

[0052] After the glass cloth of this embodiment is woven, it can undergo fiber opening treatment, and can also undergo further degreasing treatment and surface treatment. The above-mentioned fiber opening treatment, degreasing treatment and surface treatment can be performed in any order, and there is no restriction on the order of treatment.

[0053] The above-mentioned fiber opening process includes, for example, the following processes: applying a tension of 30 to 500 N to the warp yarns of the glass cloth of this embodiment while performing fiber opening treatment using the pressure of a fluid such as a water jet with a surface pressure of 1 to 8 MPa (high-pressure water fiber opening treatment); performing fiber opening treatment using water flow pressure such as ordinary spraying; performing fiber opening treatment using high-frequency vibration such as ultrasound with liquid as the medium; performing fiber opening treatment using roller pressing, etc., and using the above treatments to increase the yarn width of the warp and weft yarns.

[0054] As an example of the above-mentioned degreasing treatment, the following treatment can be used: the glass of this embodiment is placed in a heating furnace with an atmosphere temperature in the range of 300 to 500°C and kept for 40 to 80 hours, thereby heating and decomposing the organic matter attached to the glass fiber.

[0055] As an example of the above surface treatment, the following treatment can be used: immerse glass cloth in a silane coupling agent or a solution containing the silane coupling agent and a surfactant, squeeze out excess water, and then heat and dry it at a temperature of 90-120°C for 1-10 minutes.

[0056] The aforementioned silane coupling agents may include, for example, aminosilanes, ureosilanes, chlorosilanes, epoxysilanes, mercaptosilanes, vinylsilanes, (meth)acryloyloxysilanes, phenylsilanes, styrylsilanes, and isocyanate silanes. In this embodiment, the aforementioned silane coupling agents may be used alone or in combination of two or more.

[0057] Examples of aminosilanes include: γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-N'-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and γ-anilinepropyltrimethoxysilane.

[0058] Examples of ureosilanes include γ-ureopropyltriethoxysilane.

[0059] Examples of chlorosilanes include γ-chloropropyltrimethoxysilane.

[0060] Examples of epoxy silanes include β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane.

[0061] Examples of mercaptosilanes include γ-mercaptotrimethoxysilane and γ-mercaptopropyltrimethoxysilane.

[0062] Examples of vinyl silanes include vinyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane, and N-benzyl-β-aminoethyl-γ-aminopropyltrimethoxysilane.

[0063] Examples of (meth)acryloyloxysilanes include γ-acryloyloxypropyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane.

[0064] Examples of phenylsilanes include phenyltrimethoxysilane.

[0065] Examples of styrylsilanes include p-styryltrimethoxysilane.

[0066] Examples of isocyanate silanes include γ-isocyanate-propyltriethoxysilane.

[0067] In addition, examples of surfactants include nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants. In this embodiment, the surfactants mentioned above can be used alone or in combination of two or more.

[0068] Examples of nonionic surfactants include ethylene oxide and propylene oxide alkyl ethers, polyoxyethylene alkyl ethers, polyoxyethylene-polyoxypropylene-block copolymer ethers, alkyl polyoxyethylene-polyoxypropylene-block copolymer ethers, polyoxyethylene fatty acid esters, polyoxyethylene fatty acid monoesters, polyoxyethylene fatty acid diesters, polyoxyethylene sorbitol fatty acid esters, glycerol fatty acid ester ethylene oxide adducts, polyoxyethylene acrylate vinyl ethers, hydrogenated castor oil ethylene oxide adducts, alkylamine ethylene oxide adducts, fatty acid amide ethylene oxide adducts, glycerol fatty acid esters, polyglycerol fatty acid esters, pentaerythritol fatty acid esters, sorbitol fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyol alkyl ethers, fatty acid alkanolamides, alkynyldiol, alkynyl alcohol, alkynyldiol ethylene oxide adducts, and alkynyl alcohol ethylene oxide adducts.

[0069] Examples of cationic surfactants include alkyl dimethyl benzyl ammonium chloride, alkyl trimethyl ammonium chloride, alkyl dimethyl ethyl ammonium ethyl sulfate, higher alkylamine salts (acetate, hydrochloride, etc.), ethylene oxide adducts of higher alkylamines, condensates of higher fatty acids and polyalkylene polyamines, salts of higher fatty acids and alkanolamine esters, higher fatty acid amide salts, imidazoline cationic surfactants, and alkylpyridinium salts.

[0070] Examples of anionic surfactants include higher alcohol sulfates, higher alkyl ether sulfates, α-olefin sulfates, alkylbenzene sulfonates, α-olefin sulfonates, reaction products of fatty acid halides and N-methyl taurine, dialkyl sulfosuccinates, higher alcohol phosphates, and phosphates of higher alcohol ethylene oxide adducts.

[0071] Examples of amphoteric surfactants include amino acid-type amphoteric surfactants such as alkali metal salts of alkylaminopropionic acid, betaine-type amphoteric surfactants such as alkyl dimethyl betaine, and imidazoline-type amphoteric surfactants.

[0072] Next, the prepreg of this embodiment can be obtained by impregnating at least a portion of the glass cloth described above with resin using a method known in the art and placing it in a semi-cured state.

[0073] In the prepreg of this embodiment, the difference between the relative permittivity of the glass cloth and the relative permittivity of the matrix resin of the prepreg is preferably in the range of 1.5 to 3.0, more preferably in the range of 1.6 to 2.8, even more preferably in the range of 1.7 to 2.6, and particularly preferably in the range of 1.9 to 2.5.

[0074] When the glass fiber (glass fiber bundle) has the above-mentioned glass composition, such as E glass composition, high-strength and high-elastic modulus glass composition, high-elastic modulus and easy-to-manufacture glass composition, or low dielectric constant and low dielectric loss tangent glass composition, the relative dielectric constant of the glass cloth of this embodiment is in the range of 3.0 to 7.0 at a measurement frequency of 10 GHz, preferably in the range of 3.5 to 6.0, and more preferably in the range of 4.0 to 5.0.

[0075] At this time, examples of matrix resins whose relative permittivity difference with that of the glass cloth described in this embodiment is within the aforementioned range include epoxy resin, polyphenylene ether resin, maleimide resin, cyclic olefin polymer resin, and ODV resin. For high-speed communication applications, the matrix resin is preferably a thermosetting resin with low dielectric properties. Examples of such thermosetting resins include modified polyphenylene ether or reactive low molecular weight polyphenylene ether.

[0076] Next, the printed wiring board of this embodiment can be manufactured in the following manner. The prepreg described in this embodiment is cured, and multiple layers of the cured prepreg are stacked. Copper foil, such as low-roughness electrolytic copper foil, is then stacked on top and bottom of the prepreg, and hot-pressed to form a copper-clad laminate. The copper foil is then patterned to form a predetermined wiring pattern. The patterning can be performed using methods known to the public, such as photolithography.

[0077] Next, embodiments and comparative examples of the present invention will be described.

[0078] Example (Example 1) In this embodiment, firstly, glass filaments with a relative permittivity of 4.7 (measurement frequency 10GHz) composed of low dielectric constant and low dielectric loss tangent glass are bundled together to form glass fibers (glass fiber bundles), which are then used as warp and weft yarns respectively to weave a glass cloth equivalent to IPC4412 standard #1078 (using yarn: D500 (fiber diameter 5.0μm, yarn weight 10.1g / 1000m), warp weaving density: 53 yarns / 25mm, weft weaving density: 53 yarns / 25mm, unit area weight: 43g / m²). 2 ).

[0079] The warp yarn of the above-mentioned glass cloth is made of the following yarn: after coating the glass fiber protective agent (sizing agent) in the warping process, the warp yarn is pressed on a roller-type cylinder with the surface kept at a constant temperature of 120°C for drying to obtain the yarn.

[0080] Next, the woven glass cloth was heated at 450°C for 60 hours for degreasing treatment, and then subjected to water pressure fiber opening treatment using a jet stream with a water pressure of 6.0 MPa. The opened glass cloth was then immersed in an aqueous solution of a glass treatment agent prepared by dispersing 3-methacryloyloxypropyltrimethoxysilane (manufactured by Toray Dow Corning, trade name: OFS6030) and acetic acid in water, and then subjected to surface treatment by heating and drying, thereby obtaining a surface-treated opened glass cloth with a thickness of 43.2 μm.

[0081] Then, for the surface-treated open-fiber glass cloth obtained in this embodiment, the yarn widths of the warp and weft yarns constituting the surface-treated open-fiber glass cloth are measured according to the method described later, and the average warp yarn width, average weft yarn width, open-fiber area ratio S, warp yarn width open-fiber ratio Lt, and weft yarn width open-fiber ratio Ly are calculated. The results are shown in Table 1.

[0082] (Method for measuring yarn width) For the surface-treated open-fiber glass cloth obtained in this embodiment, a glass cloth sample with a longitudinal length of 110mm and a transverse length of 60mm was cut from three positions (100mm from each end and the center) in the width direction of the glass cloth using a digital microscope (manufactured by KEYENCE Co., Ltd.) at 100x magnification. The warp width and weft width were measured at 100 points along the warp and weft directions respectively, for a total of 300 points. The average warp width and average weft width were obtained based on the average value of the 300 measurement points.

[0083] Next, the surface-treated open-fiber glass cloth was cut into dimensions of 450mm longitudinally and 400mm transversely to obtain surface-treated open-fiber glass cloth sheets. These sheets were then impregnated in modified polyphenylene ether resin varnish and pre-dried at 150°C for 10 minutes to obtain a prepreg with a resin content of 60% by mass. The modified polyphenylene ether resin varnish was prepared from the following components: 70 parts by mass of reactive low molecular weight polyphenylene ether (manufactured by SABIC (Saudi Basic Industries Corporation), trade name: SA9000, dielectric constant: 2.5 (measurement frequency 1MHz)), 30 parts by mass of triallyl isocyanurate (manufactured by Evonik Japan, trade name: TAICROS), 1 part by mass of α,α'-bis(tert-butylperoxy)diisopropylbenzene (manufactured by Nippon Oil Co., Ltd., trade name: Perbutyl P), and toluene (manufactured by Fujifilm and Koko Pure Chemicals Co., Ltd.) was added as a solvent.

[0084] Next, two sheets of the prepreg are stacked, and low-roughness electrolytic copper foil (manufactured by Fukuda Metal Foil Industry Co., Ltd., trade name: CF-T4X-SV18, thickness 18μm) is stacked on top and bottom respectively. Using a vacuum hot press (manufactured by Kitagawa Seiki Co., Ltd.), the copper-clad laminate with a thickness of 0.21mm is obtained by heating and pressing in a vacuum for 1 hour at 205°C and surface pressure of 4MPa.

[0085] Subsequently, for the copper-clad laminate obtained in this embodiment, the fiber bundle thickness of the glass cloth warp and weft yarns contained in the copper-clad laminate was measured according to the method described later, and the ratio of the standard deviation σt of the warp glass fiber bundle thickness to the standard deviation σy of the weft glass fiber bundle thickness, σt / σy, and the ratio of the maximum and minimum difference Rt of the warp glass fiber bundle thickness to the maximum and minimum difference Ry of the weft glass fiber bundle thickness, Rt / Ry, were calculated. The results are shown in Table 1.

[0086] (Methods for measuring fiber bundle thickness) The copper-clad laminate obtained in this embodiment was cut into 14mm × 10mm pieces and embedded in epoxy resin (manufactured by Cemedine Co., Ltd., trade name: 1500). The cross-section was then ground parallel to the warp or weft direction to expose the intersection of the glass cloth warp and weft yarns on the surface. Using a scanning electron microscope (manufactured by Nippon Electron Co., Ltd., trade name: IT700HR), at 300x magnification, the thickness of 30 consecutive adjacent fiber bundles of glass cloth in the copper-clad laminate was measured. The warp fiber bundle thickness refers to the distance between the uppermost glass filaments in the warp yarn (glass filament) bundle and the lowermost glass filaments in the warp yarn bundle, both parallel to the weft direction. Similarly, the fiber bundle thickness of the weft yarn refers to the distance between two straight lines drawn parallel to the warp direction, one at the top of the uppermost glass filament of the weft yarn bundle and the other at the bottom of the weft yarn bundle. The fiber bundle thickness is measured at the intersection of the warp and weft yarns. That is, when measuring the fiber bundle thickness of the glass cloth warp yarn, the thickness of the fiber bundle containing at least one weft yarn above or below the warp yarn fiber bundle is measured; similarly, when measuring the fiber bundle thickness of the glass cloth weft yarn, the thickness of the fiber bundle containing at least one warp yarn above or below the weft yarn fiber bundle is measured.

[0087] Next, for the printed wiring board obtained by patterning one side of the copper foil of the copper-clad laminate obtained in this embodiment, the delay skew was measured and evaluated according to the method described later. The results are shown in Table 1.

[0088] (Methods for measuring and evaluating time delay skew) The copper foil on one side of the copper-clad laminate obtained in this embodiment is patterned to form 8 sets of differential microstrip lines parallel to the warp direction of the glass cloth. The wiring width is 130 μm. The spacing between a pair of differential lines is set to 1 / 2 of the warp spacing of the glass cloth used (25000 / Wt), and the groups of differential lines are staggered sequentially by 9 / 8 of the warp spacing. By using the above wiring, time delay skew data containing the following combination can be obtained: the line directly below which has the highest glass content and the highest effective dielectric constant, and the line directly below which has the highest resin content and the lowest effective dielectric constant. The time delay skew corresponding to a 100 mm line length is measured using a network analyzer (manufactured by Keysight Technology, trade name: N5227B).

[0089] Based on the above measurement results, the cases where the maximum value of the eight time delay skew values ​​is less than 2.5ps / 100mm are rated as ◎, the cases where the maximum value is greater than or equal to 2.5ps / 100mm but less than 3.5ps / 100mm are rated as 〇, and the cases where the maximum value is greater than or equal to 3.5ps / 100mm are rated as ×.

[0090] (Example 2) In this embodiment, in addition to using glass cloth equivalent to IPC 4412 standard #1280 (using yarn: D500 (fiber diameter 5.0μm, yarn weight 10.1g / 1000m), warp yarn weaving density: 59 threads / 25mm, weft yarn weaving density: 59 threads / 25mm, unit area weight: 48g / m²), 2 Apart from weaving, the surface-treated open-fiber glass cloth and copper-clad laminate are obtained in exactly the same manner as in Example 1.

[0091] Next, the warp and weft yarn widths, fiber bundle thicknesses, and time skew were measured in exactly the same manner as in Example 1. The average warp yarn width, average weft yarn width, open area ratio S, warp yarn width open rate Lt, weft yarn width open rate Ly, the ratio of the standard deviation σt of the warp glass fiber bundle thickness to the standard deviation σy of the weft glass fiber bundle thickness σt / σy, and the ratio of the maximum and minimum difference Rt of the warp glass fiber bundle thickness to the maximum and minimum difference Ry of the weft glass fiber bundle thickness Rt / Ry were calculated, and the time skew was evaluated. The results are shown in Table 1.

[0092] (Example 3) In this embodiment, except that glass fiber (glass fiber bundle) is made by bundling 200 glass filaments with a relative permittivity of 4.5 (measurement frequency 10 GHz) to weave glass cloth, and the fiber opening process is changed to water pressure fiber opening by jet spray with a water pressure of 5.0 MPa, it is completely the same as in Example 1, and a surface-treated fiber-opened glass cloth and a copper-clad laminate are obtained.

[0093] Next, the warp and weft yarn widths, fiber bundle thicknesses, and time skew were measured in exactly the same manner as in Example 1. The average warp yarn width, average weft yarn width, open area ratio S, warp yarn width open rate Lt, weft yarn width open rate Ly, the ratio of the standard deviation σt of the warp fiber bundle thickness to the standard deviation σy of the weft fiber bundle thickness (σt / σy), and the ratio of the maximum and minimum difference Rt of the warp fiber bundle thickness to the maximum and minimum difference Ry of the weft fiber bundle thickness (Rt / Ry) were calculated to evaluate the time skew. The results are shown in Table 1.

[0094] (Example 4) In this embodiment, except that the yarn dried in a non-contact manner in a chamber at a temperature of 120°C is used as the warp yarn of the glass cloth in the warping process, and the fiber opening process is changed to water pressure fiber opening using a jet stream with a water pressure of 7.0 MPa, the surface-treated fiber-opened glass cloth and copper-clad laminate are obtained in the same manner as in Example 3.

[0095] Next, the warp and weft yarn width, fiber bundle thickness, time skew, average warp yarn width, average weft yarn width, open area ratio S, warp yarn width open rate Lt, weft yarn width open rate Ly, the ratio of the standard deviation σt of the warp fiber bundle thickness to the standard deviation σy of the weft fiber bundle thickness σt / σy, and the ratio of the maximum and minimum difference Rt of the warp fiber bundle thickness to the maximum and minimum difference Ry of the weft fiber bundle thickness Rt / Ry were measured in exactly the same manner as in Example 1, and the time skew was evaluated. The results are shown in Table 1.

[0096] (Example 5) In this embodiment, in addition to using glass cloth equivalent to IPC 4412 standard #2116 (using yarn: E250 (fiber diameter 7.0μm, yarn weight 20.2g / 1000m), warp yarn weaving density: 59 threads / 25mm, weft yarn weaving density: 57 threads / 25mm, unit area weight: 95g / m²), 2 Apart from weaving, the surface-treated open-fiber glass cloth and copper-clad laminate are obtained in exactly the same manner as in Example 1.

[0097] Next, the warp and weft yarn widths, fiber bundle thicknesses, and time skew were measured in exactly the same manner as in Example 1. The average warp yarn width, average weft yarn width, open area ratio S, warp yarn width open rate Lt, weft yarn width open rate Ly, the ratio of the standard deviation σt of the warp glass fiber bundle thickness to the standard deviation σy of the weft glass fiber bundle thickness (σt / σy), and the ratio of the maximum and minimum difference Rt of the warp glass fiber bundle thickness to the maximum and minimum difference Ry of the weft glass fiber bundle thickness (Rt / Ry) were calculated. The time skew was also evaluated. The results are shown in Table 1.

[0098] (Comparative Example 1) In this comparative example, the surface-treated glass cloth and copper-clad laminate were obtained in exactly the same manner as in Example 1, except that no fiber opening process was performed.

[0099] Next, the warp and weft yarn widths, fiber bundle thicknesses, and time skew were measured in exactly the same manner as in Example 1. The average warp yarn width, average weft yarn width, open area ratio S, warp yarn width open rate Lt, weft yarn width open rate Ly, the ratio of the standard deviation σt of the warp fiber bundle thickness to the standard deviation σy of the weft fiber bundle thickness (σt / σy), and the ratio of the maximum and minimum difference Rt of the warp fiber bundle thickness to the maximum and minimum difference Ry of the weft fiber bundle thickness (Rt / Ry) were calculated to evaluate the time skew. The results are shown in Table 1.

[0100] It should be noted that in this comparative example, the fiber opening area ratio S, the warp yarn width fiber opening ratio Lt, and the weft yarn width fiber opening ratio Ly are calculated using the widths of the warp and weft yarns that have not undergone fiber opening treatment.

[0101] (Comparative Example 2) In this comparative example, except that the fiber opening treatment of the glass cloth was changed to water pressure fiber opening using a fan-shaped spray with a water pressure of 6.0 MPa, everything else was exactly the same as in Example 1, resulting in surface-treated fiber-opened glass cloth and copper-clad laminate.

[0102] Next, the warp and weft yarn widths, fiber bundle thicknesses, and time skew were measured in exactly the same manner as in Example 1. The average warp yarn width, average weft yarn width, open area ratio S, warp yarn width open rate Lt, weft yarn width open rate Ly, the ratio of the standard deviation σt of the warp glass fiber bundle thickness to the standard deviation σy of the weft glass fiber bundle thickness (σt / σy), and the ratio of the maximum and minimum difference Rt of the warp glass fiber bundle thickness to the maximum and minimum difference Ry of the weft glass fiber bundle thickness (Rt / Ry) were calculated, and the time skew was evaluated. The results are shown in Table 1.

[0103] (Comparative Example 3) In this comparative example, except that the fiber opening process of the glass cloth was changed to a non-contact ultrasonic fiber opening process, that is, the glass cloth was opened by a water medium vibrating by a 60Hz ultrasonic vibrator, the surface-treated fiber-opened glass cloth and copper-clad laminate were obtained in the same manner as in Example 1.

[0104] Next, the warp and weft yarn widths, fiber bundle thickness, and time skew were measured in exactly the same manner as in Example 1. The average warp yarn width, average weft yarn width, open area ratio S, warp yarn width open rate Lt, weft yarn width open rate Ly, the ratio of the standard deviation σt of the warp glass fiber bundle thickness to the standard deviation σy of the weft glass fiber bundle thickness (σt / σy), and the ratio of the maximum and minimum difference Rt of the warp glass fiber bundle thickness to the maximum and minimum difference Ry of the weft glass fiber bundle thickness (Rt / Ry) were calculated. The time skew was also evaluated. The results are shown in Table 1.

[0105] (Table 1) As shown in Table 1, when the glass cloth according to Examples 1 to 5 has a standard deviation σt of the warp glass fiber bundle thickness and a standard deviation σy of the weft glass fiber bundle thickness, σt / σy is in the range of 0.3 to 0.9, it can reduce time delay skew when used in printed wiring boards.

[0106] On the other hand, according to the glass cloth of Comparative Examples 1 to 3, when the ratio of the standard deviation σt of the warp glass filament thickness to the standard deviation σy of the weft glass filament thickness, σt / σy, exceeds 0.9, it is impossible to reduce the time delay skew when it is used for printed wiring boards.

Claims

1. A glass cloth comprising glass fibers as warp and weft yarns, wherein the glass cloth is characterized in that the ratio of the standard deviation σt of the glass fiber bundle thickness of the warp yarns to the standard deviation σy of the glass fiber bundle thickness of the weft yarns, σt / σy, is in the range of 0.3 to 0.

9.

2. The glass cloth of claim 1, wherein, Based on the warp weaving density Wt, average warp yarn width Bt, weft weaving density Wy, and average weft yarn width By of the glass cloth, the fiber opening area ratio S calculated by the following formula (1) is in the range of 90-100%. (Equation 1) 。 3. The glass cloth of claim 1, wherein, The ratio Rt / Ry of the difference between the maximum and minimum thickness of the warp glass fiber bundles of the glass cloth (i.e., the maximum-minimum difference Rt) and the difference between the maximum and minimum thickness of the weft glass fiber bundles (i.e., the maximum-minimum difference Ry) is in the range of 0.3 to 0.

9.

4. The glass cloth of claim 1, wherein, The fiber opening rate Lt of the warp yarns, calculated by the following formula (2), is in the range of 60% to 83%, and the fiber opening rate Ly of the weft yarns, calculated by the following formula (3), is in the range of 85% or higher. (Equation 2) (Equation 3) 。 5. The glass cloth of claim 1, wherein, The thickness of the glass cloth is in the range of 18 to 100 μm.

6. A prepreg, characterized by, The glass cloth comprising any one of claims 1 to 5.

7. The prepreg according to claim 6, wherein, The difference between the relative permittivity of the glass cloth and the relative permittivity of the matrix resin of the prepreg is in the range of 1.5 to 3.

0.

8. A printed wiring board, characterized by It includes the prepreg as described in claim 6.

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