Glass cloth, method for manufacturing glass cloth, prepreg, printed circuit board

Abstract

The present invention provides a glass cloth which is woven with a glass yarn containing a plurality of glass filaments as warp and weft, and is surface-treated with a surface treatment agent, wherein the glass cloth contains a prescribed region, the region has a value of the following formula (1): (E1 / T1) / (W1 / L1)... (1) which is greater than 0 and is 0.14 or less, in the formula, E1 represents a curvature 2.5 cm ‑1 at the time of the second bending, a curvature 0.5 to +1.5 cm ‑1 between each unit length, a second bending stiffness, unit: N·cm 2 / cm, T1 represents a thickness of the region, unit: cm, L1 represents a beat-up interval of the warp, unit: cm, and W1 represents a warp width, unit: cm, in such a manner that a valley bottom line of a valley generated by bending is bent along a weft direction.

Description

Technical Field

[0001] This invention relates to glass cloth, a method for manufacturing glass cloth, prepreg, and printed circuit boards. Background Technology

[0002] Glass cloth is widely used as a substrate for printed circuit boards (PCBs) in electronic devices. In recent years, with the increasing performance and high-speed communication of information terminals such as smartphones, there is a growing demand for lower dielectric constants in PCBs (e.g., lower dielectric constants and lower dielectric loss tangents). To meet the requirements for lower dielectric constants in PCBs, the following method is employed: Regarding the materials constituting the substrate, glass cloth treated with a silane coupling agent and a low-dielectric resin such as polyphenylene ether (hereinafter also referred to as "matrix resin") are used, and the low-dielectric resin is impregnated into the glass cloth.

[0003] Compared to previously known epoxy resins, low-dielectric resins such as polyphenylene ether tend to have higher viscosity. Therefore, unimpregnated resin portions (voids) easily form in the glass fiber bundles within the substrate, making CAF (conductive anodic filaments) a problem. Thus, it is necessary to further improve resin impregnation to enhance CAF resistance.

[0004] Typically, methods to improve the resin impregnation of glass cloth include fiber opening processes such as using columnar or spray flow, vibration-based cleaning, or high-frequency vibration with a liquid as the medium. Methods for improving resin impregnation include impregnating the glass cloth in a liquid containing colloidal silica for fiber opening (see Patent Document 1), using a liquid containing colloidal silica as a glass fiber bundler (see Patent Document 2), and impregnating the glass cloth in an aqueous dispersion of resin particles and elastomer particles (see Patent Document 3).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2010-84236

[0008] Patent Document 2: Japanese Patent Application Publication No. 9-208268

[0009] Patent Document 3: Japanese Patent Application Publication No. 2018-115225 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] Regarding glass cloth, there is a pressing need to further improve its impregnation properties compared to high-viscosity, low-dielectric resins such as polyphenylene ether. In the methods described in Patent Documents 1 to 3, nanoparticles are attached to the glass cloth; however, concerns generally exist regarding the potential environmental and human health hazards of these nanoparticles, therefore, it is desirable to avoid the presence of nanoparticles such as colloidal silica. In other words, from the viewpoint of environmental and human health burden, there is room for improvement in the methods described in Patent Documents 1 to 3.

[0012] This invention was made in view of the aforementioned problems, and its object is to provide a glass cloth that is less burdensome to the environment and human body and can achieve good impregnation with low-dielectric resins. Furthermore, this invention also aims to provide prepregs and printed circuit boards using this glass cloth.

[0013] Solution for solving the problem

[0014] In order to solve the above-mentioned problems, the inventors conducted research and found that by setting specific areas on the glass cloth, the above-mentioned problems could be solved, thus completing the present invention.

[0015] That is, one technical solution of the present invention is as follows.

[0016] [1] A glass cloth is woven from glass yarn containing multiple glass filaments as warp and weft yarns, and is surface-treated with a surface treatment agent. The glass cloth includes a defined region, wherein the region is given by the following formula (1): (E1 / T1) / (W1 / L1)...(1) is greater than 0 and less than 0.14, where E1 represents a curvature of 2.5cm. -1 The curvature during the second bend is 0.5 to +1.5 cm. -1 The second bending stiffness per unit length between them, in N·cm 2 / cm,

[0017] T1 represents the thickness of the region, in cm.

[0018] L1 represents the warp yarn insertion interval, in cm.

[0019] W1 represents the warp width, in cm.

[0020] The valley bottom line of the valley created by the bending is bent in a manner that follows the weft direction.

[0021] [2] According to the glass cloth of technical solution 1, wherein the formula (1) is greater than 0 and less than 0.13.

[0022] [3] The glass cloth according to technical solution 1 or 2, wherein the thickness T1 of the region is 0.002 to 0.013 cm.

[0023] [4] The glass cloth according to any one of technical solutions 1 to 3, wherein the warp yarn insertion interval L1 is 0.021 to 0.25 cm.

[0024] [5] The glass cloth according to any one of technical solutions 1 to 4, wherein the amount of particles attached to the region is less than 100 particles / μm.

[0025] [6] The glass cloth according to any one of technical solutions 1 to 5, wherein the surface treatment agent comprises a silane coupling agent with an unsaturated double bond having free radical reactivity.

[0026] [7] The glass cloth according to any one of technical solutions 1 to 6, wherein the number of fibers with a length of 1 mm or more observed when a tension of 100 N / 1000 mm is applied by roller-to-roll is 10 fibers / m. 2 The weft slant of the weft yarn is below 4%.

[0027] [8] The glass cloth according to any one of technical solutions 1 to 7, wherein the glass cloth includes a region satisfying the following formula (2), namely (E2 / T2) / (W2 / L2)...(2) greater than 0 and less than 0.14, where E2 represents a curvature of 2.5cm. -1 The curvature during the second bend is 0.5 to +1.5 cm. -1 The second bending stiffness per unit length between them, in N·cm 2 / cm,

[0028] T2 represents the thickness of the region, in cm.

[0029] L2 represents the weft yarn insertion interval, in cm.

[0030] W2 indicates the weft width, in cm.

[0031] The valley bottom line of the valley created by the bending is bent in a manner that follows the warp direction.

[0032] [9] According to the glass cloth of technical solution 8, wherein the formula (2) is greater than 0 and less than 0.13.

[0033]

[10] The glass cloth according to technical solution 8 or 9, wherein the thickness T2 of the region is 0.002 to 0.013 cm.

[0034]

[11] The glass cloth according to any one of technical solutions 8 to 10, wherein the weft yarn insertion interval L2 is 0.021 to 0.25 cm.

[0035]

[12] The glass cloth according to any one of technical solutions 1 to 11, wherein the amount of particles attached to the region is 0 particles / μm.

[0036]

[13] The glass cloth according to technical solution 5 or 12, wherein the microparticles are inorganic microparticles and / or organic microparticles with a diameter of less than 3 μm.

[0037]

[14] According to the glass cloth of technical solution 13, the inorganic microparticles are at least one selected from the group consisting of colloidal silica, crystalline silica, alumina and boron nitride.

[0038] The organic microparticles are at least one selected from the group consisting of polyphenylene ether resin, epoxy resin, and styrene-based elastomers.

[0039]

[15] A prepreg, wherein the prepreg has a glass cloth as described in any one of technical solutions 1 to 14 and a matrix resin composition impregnated in the glass cloth.

[0040]

[16] A printed circuit board, wherein the printed circuit board has a glass cloth as described in any one of technical solutions 1 to 14 and a cured product of a matrix resin composition impregnated in the glass cloth.

[0041]

[17] A method for manufacturing glass cloth, which is the method for manufacturing glass cloth according to any one of technical solutions 1 to 13, wherein,

[0042] The manufacturing method of this glass cloth includes a fiber-opening process involving blowing dry ice particles.

[0043]

[18] The method for manufacturing glass cloth according to technical solution 17, wherein the fiber opening process is performed by bending with a curvature radius of less than 2.5 mm.

[0044] The effects of the invention

[0045] According to the present invention, a glass cloth capable of achieving good impregnation with low-dielectric resins can be provided. Furthermore, according to the present invention, prepregs and printed circuit boards using the glass cloth can also be provided. Attached Figure Description

[0046] Figure 1 This is a diagram illustrating an example of a method for measuring the bending stiffness of glass cloth according to an embodiment of the present invention.

[0047] Figure 2This is a diagram illustrating an example of a method for measuring the bending stiffness of glass cloth according to an embodiment of the present invention. Detailed Implementation

[0048] Hereinafter, embodiments of the present invention (hereinafter referred to as "this embodiment") will be described. However, the present invention is not limited to the following embodiments and can be implemented in various modifications within its scope. In this embodiment, the numerical range recorded using "~" includes the numerical values ​​recorded before and after "~". In addition, in this embodiment, in the numerical range recorded in stages, the upper or lower limit value recorded in a certain numerical range can be replaced with the upper or lower limit value of another numerical range recorded in stages. Furthermore, in this embodiment, the upper or lower limit value recorded in a certain numerical range can also be replaced with the value shown in the embodiment.

[0049] exist Figure 1 and Figure 2 The scale, shape, and length of the depicted items are sometimes exaggerated for clarity.

[0050] [Brief Structure]

[0051] The glass cloth of this embodiment is woven from glass yarn containing multiple glass filaments as warp and weft yarns, and is surface-treated with a surface treatment agent. The glass cloth includes a defined region, which is defined by the following formula (1):

[0052] (E1 / T1) / (W1 / L1)...(1) is greater than 0 and less than 0.14.

[0053] In equation (1), E1 represents a curvature of 2.5cm. -1 The curvature during the second bend is 0.5 to +1.5 cm. -1 Second bending stiffness per unit length (N·cm) 2 / cm), T1 represents the thickness of the area (cm), L1 represents the warp insertion interval (cm), and W1 represents the warp width (cm).

[0054] In equation (1), E1, more specifically, represents the curvature from 0 to +2.5cm. -1 The first bend, from curvature +2.5cm -1 Bending from 0 cm curvature to -2.5 cm curvature -1 The second bend and from curvature -2.5cm -1 Bending from 0 cm curvature to +2.5 cm curvature. -1 In the case of the third bend, the curvature of the third bend ranges from 0.5 to +1.5 cm. -1 The bending stiffness obtained between these parameters.

[0055] Equation (1) is satisfied by making E1 / T1 relatively small and W1 / L1 relatively large.

[0056] Here, to make E1 / T1 relatively small, the bending stiffness E1 needs to be relatively small and the thickness T1 relatively large. The bending stiffness E1 is a value that increases as the stiffness of the aforementioned region increases. Therefore, a relatively small E1 / T1 means that even if the aforementioned region has a certain thickness, its stiffness is small (i.e., it is easy to bend).

[0057] On the other hand, in order to make W1 / L1 relatively large, the yarn width W1 needs to be relatively large and the insertion interval L1 needs to be relatively small.

[0058] In an example illustrating the relationship between E1 / T1 and W1 / L1, from the perspective of addressing the requirement to increase W1 / L1, it becomes difficult to address the requirement to decrease E1 / T1 when the bending stiffness E1 increases. Conversely, from the perspective of addressing the requirement to decrease E1 / T1, a lower warp and weft yarn drive-in density is advantageous to reduce the bending stiffness E1, but this makes it difficult to address the requirement to increase W1 / L1.

[0059] Furthermore, when describing an example from the perspective of impregnation with the matrix resin, the aforementioned region, where the requirement to reduce E1 / T1 is met, has a lower bending stiffness relative to its thickness, thus facilitating good impregnation with the matrix resin. In this region, a lower bending stiffness E1 is preferable. This results in reduced adhesion between the filaments based on the sizing agent and the silane coupling agent, thereby implying improved impregnation. On the other hand, in the aforementioned region, where the requirement to increase W1 / L1 is met, the matrix resin is difficult to impregnate when L1 is small.

[0060] The inventors focused on E1 / T1 and W1 / L1, which sometimes have opposing viewpoints. Through in-depth research, the inventors discovered that by focusing not only on a smaller E1 / T1 but also on W1 / L1 to achieve good impregnation with the matrix resin, good overall impregnation with the matrix resin can be achieved based on formula (1), which combines W1 / T1 with W1 / L1.

[0061] Curvature +2.5cm -1 Curvature -2.5cm -1 The bending below is outside the range of elastic deformation in the aforementioned region. That is, at a curvature of +2.5cm... -1 In the first bend, the region is capable of plastic deformation.

[0062] Furthermore, the first bend is an initial bend towards one side of the aforementioned region, while the second bend is an initial bend towards the other side of the aforementioned region. Therefore, in the first and second bends, the initial load used for bending is larger compared to subsequent bends. On the other hand, the significance of focusing on the stiffness of the second bend (the stiffness during the third bend mentioned above) is that it is less susceptible to the influence of the initial load required for the first and second bends. Therefore, it is possible to accurately measure the curvature from 0.5 to +1.5 cm as part of the bending process. -1 The bending stiffness per unit length between. For this point, the bending stiffness can also be measured after the 3rd bend, the 4th bend, and the 5th bend, etc., but as the number of bends increases, the region tends to bend, and therefore, there is a tendency for the bending stiffness to decrease. In this case, it is difficult to accurately obtain the bending stiffness in the region required by Equation (1).

[0063] In this embodiment, in addition to the above, there is a significance in terms of "secondary bending stiffness" from the following point of view.

[0064] That is, the "second bend" in this embodiment refers to the bend performed on the glass cloth, which is the object of measurement, after it has undergone a prior bend (equivalent to the first bend and the second bend described above) in preparation for the measurement. By focusing on the "second bend" performed after such a prior bend, the stiffness specified as the main point of this embodiment can be accurately measured. The above view also applies to equation (2).

[0065] The aforementioned region can be at least a part of the total area of ​​the glass cloth, which can also be said to mean that at least a part of the glass cloth satisfies equation (1). In particular, when the aforementioned region is the entire total area of ​​the glass cloth, it can also be said that the entire glass cloth satisfies equation (1). The size of the aforementioned region is only required to be less than or equal to the total area of ​​the glass cloth, and its shape is not limited. The aforementioned region can be circular or rectangular.

[0066] From the viewpoint that it is easy to achieve glass cloth with good resin impregnation, Formula (1) is preferably 0.13 or less, more preferably 0.12 or less, and particularly preferably 0.10 or less.

[0067] Starting from the same point of view as equation (1), the following equation (2) is:

[0068] (E2 / T2) / (W2 / L2)...(2) Preferably, it satisfies that it is greater than 0 and less than 0.14.

[0069] In the formula, E2 represents a curvature of 2.5cm. -1 The curvature during the second bend is 0.5 to +1.5 cm. -1Second bending stiffness per unit length (N·cm) 2 / cm), T2 represents the thickness of the area (cm), L2 represents the weft yarn insertion interval (cm), and W2 represents the weft yarn width (cm).

[0070] From the viewpoint that it is easy to achieve glass cloth with good resin impregnation, Formula (2) is preferably 0.13 or less, more preferably 0.12 or less, and particularly preferably 0.10 or less.

[0071] Basically, when there is no anisotropy between the warp and weft yarns (L1 and L2 are within ±5% and the number of filaments in the warp and weft yarns is the same), the warp yarns are always under tension during the fiber opening process, so the adhesion between the filaments is difficult to peel off, and there is a tendency for E1 to be a larger value than E2. Regardless of whether there is anisotropy, as long as equation (1) is satisfied, it will not affect the effect of this embodiment.

[0072] From the viewpoint of improving yield by reducing wrinkles and skew through stress balance, it is preferable to have no anisotropy. On the other hand, from the viewpoint of improving permeability by increasing air permeability, L1 and L2 and / or W1 and W2 are preferably anisotropic, wherein the anisotropy values ​​of L1 and L2 and the anisotropy values ​​of W1 and W2 are preferably different.

[0073] Furthermore, the aforementioned region satisfies equation (1). This reduces adhesion between filaments caused by sizing agents or silane coupling agents, thereby enabling the production of glass cloth with good resin impregnation. To control the bending stiffness of the glass cloth to satisfy equation (1), as a fiber-opening process, dry ice shot peening or bending with a low radius of curvature can be performed.

[0074] Regarding the processing based on dry ice shot peening and the processing of bending with a low radius of curvature, the preferred forms are described below in the description related to the fiber splitting treatment method. According to the preferred forms described later, the bending stiffness can be easily adjusted to the range of Equation (1).

[0075] [Types of Glass]

[0076] In this embodiment, the glass fibers (glass filaments) constituting the glass cloth can typically be E-glass (alkali-free glass) used for printed circuit board applications; low-dielectric-constant glasses such as D-glass, L-glass, NE-glass, L2-glass, silica glass, and quartz glass; high-strength glasses such as S-glass and T-glass; and high-dielectric-constant glasses such as H-glass. The glass fibers can be composed of a single glass material or a combination of two or more glass fibers composed of different glass materials.

[0077] [Density and Spacing]

[0078] In this embodiment, the drive density of the warp and weft yarns constituting the glass cloth is preferably 10 to 120 yarns / inch, more preferably 40 to 100 yarns / inch. That is, the drive intervals L1 and L2 of the warp and weft yarns constituting the glass cloth are each preferably 0.021 to 0.25 cm, more preferably 0.025 to 0.064 cm, and even more preferably 0.030 to 0.055 cm.

[0079] [Weaving structure of glass cloth]

[0080] In this embodiment, the weaving structure of the glass cloth can include, for example, plain weave, square weave, satin weave, twill weave, etc. Among them, a plain weave structure is preferred.

[0081] [Yarn width]

[0082] In this embodiment, the warp yarn width W1 is preferably 0.015 to 0.055 cm, more preferably 0.025 to 0.045 cm. Furthermore, the weft yarn width W2 is preferably 0.030 to 0.070 cm, more preferably 0.034 to 0.060 cm, and even more preferably 0.040 to 0.055 cm.

[0083] 〔thickness〕

[0084] In this embodiment, the thicknesses T1 and T2 of the glass cloth are each preferably 0.002–0.015 cm, 0.002–0.013 cm, or 0.003–0.013 cm, more preferably 0.0035–0.013 cm, further preferably 0.004–0.013 cm, and particularly preferably 0.0045–0.013 cm. Generally, there is a tendency that the thicker the glass cloth, the worse the resin impregnation, i.e., there is a tendency that the requirement for improving resin impregnation becomes higher. It should be noted that the thickness of the portion of the glass cloth corresponding to the aforementioned region can be treated as the thicknesses T1 and T2 of the regions in formulas (1) and (2). It should be noted that T1 and T2 are substantially the same value within the same defined region.

[0085] [Number of filaments]

[0086] The number of filaments in both the warp and weft yarns is preferably 250 or less. By keeping the number of filaments to 250 or less, it is easier to reduce the thickness of the glass cloth. From the viewpoint of the strength and processability of the glass cloth, it is preferable to have 30 or more filaments, more preferably 40 or more, and even more preferably 50 or more.

[0087] In addition, having the same number of warp and weft filaments means that the ratio of the number of warp filaments to the number of weft filaments (weft / warp ratio) is between 0.94 and 1.06.

[0088] [Amount of attached particles]

[0089] A specified amount of particles may be attached to the aforementioned area.

[0090] The amount of particles adhering to the above-mentioned area (adhered particle amount) is preferably less than 100 particles / μm. Therefore, compared with conventional glass cloths with adhering nanoparticles such as colloidal silica, it poses less burden on the environment and human body.

[0091] To obtain a region with a particle count of 100 particles / μm or less, it is sufficient to use a glass cloth with a particle count below the aforementioned value. Such a glass cloth is obtained through a manufacturing process that does not involve steps that allow particles to adhere to the glass cloth. Specifically, by manufacturing the glass cloth without the steps described below, a glass cloth with a particle count below the aforementioned value can be obtained.

[0092] The process that is not included is:

[0093] The process of opening fibers involves immersing glass cloth in a liquid containing microparticles.

[0094] The process of using a liquid containing particulate matter as a glass fiber bundler;

[0095] Processes such as impregnating glass cloth in an aqueous dispersion of resin particles and elastomer particles.

[0096] The amount of particles adhering to the above-mentioned area is preferably 0 particles / μm. This makes it easy to achieve a glass cloth that imposes less burden on the environment and human health.

[0097] The particle size is less than 3 μm, and the particles are preferably inorganic and / or organic particles. Particularly preferred are inorganic particles selected from at least one group selected from colloidal silica, crystalline silica, alumina, and boron nitride, and organic particles selected from at least one group selected from polyphenylene ether resin, epoxy resin, and styrene-based elastomers. This allows for the easy production of glass cloth with less environmental and human health impact.

[0098] Surface treatment

[0099] In this embodiment, the glass yarn (including glass filaments) of the glass cloth is surface-treated with a surface treatment agent. This improves the reactivity with the matrix resin.

[0100] Here, the surface treatment agent preferably comprises a silane coupling agent (hereinafter also referred to as "silane coupling agent") containing unsaturated double bond groups with free radical reactivity. This facilitates improved reactivity with the matrix resin. Furthermore, it minimizes the formation of hydrophilic functional groups after reaction with the matrix resin, thus easily improving insulation reliability.

[0101] As a surface treatment agent, for example, a silane coupling agent represented by the following general formula (2) is preferably used. By using such a silane coupling agent, the moisture resistance is further improved, resulting in a tendency for further improvement in insulation reliability. In addition, the reactivity with the matrix resin is easily improved.

[0102] X(R) 3-n SiY n ...(2)

[0103] In the formula, X is an organic functional group having at least one of more than one unsaturated double bond groups, Y is an alkoxy group, n is an integer of 1 to 3, and R is a group selected from the group consisting of methyl, ethyl, and phenyl.

[0104] As shown by X, an organic functional group having one or more unsaturated double bonds can be exemplified by, for example, vinyl, allyl, vinylidene, acryloyloxy, and methacryloxy.

[0105] In general formula (2), as an alkoxy group, an alkoxy group with 5 or fewer carbon atoms is preferred for stabilizing the glass cloth.

[0106] Examples of known single substances or mixtures thereof include N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropylmethyldimethoxysilane and its hydrochloride, N-β-(N-di(vinylbenzyl)aminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-di(vinylbenzyl)aminoethyl)-N-γ-(N-vinylbenzyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-benzylaminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-vinyltrimethoxysilane, methacryloyloxypropyltrimethoxysilane, acryloyloxypropyltrimethoxysilane, etc.

[0107] As a solvent for dissolving or dispersing the silane coupling agent, either water or an organic solvent can be used, but from the viewpoint of safety and environmental protection, water is preferred as the main solvent. As a method for obtaining a treatment solution with water as the main solvent, the preferred method is either a method of directly adding the silane coupling agent to water, or a method of dissolving the silane coupling agent in a water-soluble organic solvent to prepare an organic solvent solution and then adding that organic solvent solution to water.

[0108] In addition, surfactants can be used in combination to improve the water dispersibility and stability of silane coupling agents in the treatment solution.

[0109] [Number of fibers]

[0110] For fibers larger than 1mm within the glass cloth, observation is performed under a tension of 100N / 1000mm applied by roller-to-roll. The preferred fiber count is 10 fibers / m. 2 The following is more preferably 8 units / m 2 Below. Furthermore, the ideal lower limit for the number of fibers is 0 fibers / m². 2 But it can also be 1 / m 2 That's all. From the perspective of easy observation and measurement, the number of hairs can be counted while halogen lamps are being used for illumination.

[0111] Latitude slope

[0112] When the weft slack is 4% or less, even if the glass cloth has a relative permittivity (Dk) of 5.0 or less and a thickness of 0.013 cm or less, cracking during the surface treatment and prepreg manufacturing processes can be suppressed or prevented. From this perspective, the weft slack is more preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. Furthermore, the lower limit of the weft slack can be 0% or more, or even greater than 0%.

[0113] Typically, measures to improve the resin impregnation of glass cloth are implemented by performing fiber-opening processing on the glass cloth, such as using columnar or spray flow methods, methods based on vibratory cleaners, or methods based on high-frequency vibration using liquid as a medium. There is a tendency to improve resin impregnation by increasing these processing forces. However, if the processing forces in the fiber-opening process are excessively increased, there is a tendency for fuzz and weft skew to easily form within the glass cloth. From the viewpoint of suppressing fuzz formation and weft skew, it is preferable not to excessively increase the processing forces during fiber opening.

[0114] [Bending stiffness]

[0115] In this embodiment, refer to Figure 1 and Figure 2 (a)~ Figure 2 (c) illustrates the method for determining the bending stiffness of the aforementioned region in the glass cloth. Figure 1 This is a top-view view of one side of the aforementioned area. Figure 2 (a)~ Figure 2 (c) is a diagram used to illustrate the bending action in the aforementioned region. It should be noted that... Figure 1 and Figure 2 It is the action during E1 measurement, in Figure 1 and Figure 2 In the process of changing the warp yarn Lmd and the weft yarn Ltdd, the action is the same as the action during E2 measurement.

[0116] The flexural stiffness of glass cloth can be determined using the "KES-FB2-A Bending Characteristic Tester" manufactured by KATO TECH CO.,LTD. Firstly, as... Figure 1 As shown, region 11 (test piece) is collected from glass cloth 10, where the warp direction Lmd × weft direction Ltd is measured. The warp direction Lmd and the weft direction Ltd can be the same or different. From the viewpoint of easily measuring bending stiffness E1 and E2, the warp direction Lmd and the weft direction Ltd can be selected from 5cm to 20cm respectively. As an example, both can be selected as 10cm.

[0117] When measuring the bending stiffness E1, the chuck 12 continuously holds the region 11 along the entire weft direction Ltd of the region 11. Specifically, the chuck 12 can be a chuck 12 in which the first chuck portion 12a and the second chuck portion 12b are positioned approximately parallel to each other and have a predetermined interval 13. The interval 13 is, for example, 1 cm.

[0118] Preferably, the center 14 between the first chuck portion 12a and the second chuck portion 12b overlaps with the center line 15 of the region 11, so that the first chuck portion 12a and the second chuck portion 12b continuously hold the region 11 in the entire weft direction Ltd.

[0119] As described above, the chuck 12 grips the area 11 (refer to...) Figure 2 (a)), at curvature K = -2.5 to +2.5 (cm) -1 A pure bending test with constant velocity curvature can be conducted within a range of 0.50 (cm). -1 / Second).

[0120] First bend: From K=0 to K=+2.5, bend in such a way that face 11A on one side of region 11 becomes a "valley" (see reference). Figure 2 (b)

[0121] Second bend: From K = +2.5 through K = 0 to K = -2.5, bend in such a way that the face 11B on the other side of region 11 becomes a "valley" (see reference). Figure 2 (c)).

[0122] The third bend: from K=-2.5 through K=0 to K=+2.5, the bend is made in such a way that one side of the face 11A of region 11 becomes a "valley" (see reference). Figure 2 (b)

[0123] In the first and third bends, the bending is performed such that the face 11A on one side of region 11 becomes a valley, and in the second bend, the bending is performed such that the face 11B on the other side of region 11 becomes a valley, thereby measuring the bending stiffness E1 in region 11.

[0124] During the measurement of E1, the warp yarns of the glass cloth 10 in region 11 are bent during the first bend, the second bend, and the third bend.

[0125] In the first, second, and third bends, the valley bottom line 16 of the valley created by the bend is bent in such a way that it is parallel to the weft direction Ltd of the weft yarn from the glass cloth 10.

[0126] In particular, in the first, second, and third bends, it is preferable to bend in such a way that the valley bottom line 16 of the valley created by the bend overlaps with the center line 15 of the region 11.

[0127] Here, the bending stiffness E1, obtained in the range of K = 0.5 to K = +1.5, in the "third bend" is measured. The unit is N·cm. 2 / cm. The measurement environment can be set to approximately 25°C and approximately 60% RH.

[0128] When measuring the bending stiffness E2, based on the interchange of the warp direction Lmd and the weft direction Ltd when measuring the bending stiffness E1, the weft yarns from the glass cloth 10 in region 11 are bent in the first bend, the second bend and the third bend.

[0129] In the first, second, and third bends, the valley bottom line 16 of the valley created by the bend is bent in such a way that it is parallel to the warp direction Lmd of the warp yarns from the glass cloth 10.

[0130] [Loss on Ignition]

[0131] In this embodiment, the loss on ignition of the glass cloth is preferably 0.10 to 1.20% by mass, more preferably 0.11 to 1.10% by mass, and even more preferably 0.12 to 1.00% by mass. By setting the loss on ignition to 0.10 to 1.20% by mass, resin impregnation can be ensured, and heat resistance can be imparted. The "loss on ignition" mentioned herein can be determined according to the method described in JIS R 3420. That is, firstly, the glass cloth is placed in a dryer at 110°C and dried for 60 minutes. After drying, the glass cloth is transferred to a desiccator and left to cool naturally to room temperature for 20 minutes. After natural cooling, the mass of the glass cloth is measured in units of 0.1 mg or less (first mass). Next, the glass cloth is heated in a muffle furnace at 625°C for 20 minutes. After heating in the muffle furnace, the glass cloth is transferred to a desiccator and left to cool naturally to room temperature for 20 minutes. After natural cooling, the mass of the glass cloth is measured in units of 0.1 mg or less (second mass). The difference between the first mass and the second mass is taken as the weight loss on ignition. The weight loss on ignition obtained by the above method is used to define the amount of silane coupling agent treated in the glass cloth.

[0132] [Method for manufacturing glass cloth]

[0133] The manufacturing method of the glass cloth according to this embodiment can be exemplified by, for example, a method having the following steps:

[0134] The weaving process of producing glass cloth by weaving glass yarn;

[0135] The degumming process involves removing the sizing agent from the glass yarn attached to the glass cloth.

[0136] Surface treatment processes based on silane coupling agents, etc.; and

[0137] The fiber-opening process is performed on the glass yarn of the glass cloth.

[0138] In a weaving method, weft yarns and warp yarns can be woven in a manner that presents a prescribed weaving structure.

[0139] As a degumming method, one example is removing the sizing agent by heating. It should be noted that the sizing agent is used to protect the glass yarn from breakage during weaving processes, etc. Examples of such sizing agents include starch-based binders and polyvinyl alcohol-based binders. Starch-based binders and polyvinyl alcohol-based binders each contain at least starch and polyvinyl alcohol, and may also be mixtures with waxes.

[0140] From the viewpoint of maintaining the breaking strength while sufficiently removing the sizing agent, the preferred temperature for removing the sizing agent by heating is 300 to 550°C, more preferably 350 to 480°C, and even more preferably 370 to 450°C.

[0141] The heating time can be adjusted appropriately according to the heating temperature, the thickness of the glass cloth, etc. From the viewpoint of maintaining the breaking strength and fully removing the sizing agent, it is preferred to be 20 to 80 hours, more preferably 25 to 70 hours, and even more preferably 30 to 60 hours.

[0142] In the degumming process of removing sizing agent from glass yarn attached to glass cloth, before and / or after removing the sizing agent by heating, the sizing agent before heating and / or combustion residues attached to the surface of the glass cloth after heating can be removed by washing with water.

[0143] In addition, as a surface treatment method, examples include contacting a surface treatment agent containing 0.1 to 3.0% by mass of a silane coupling agent with glass cloth and then drying it. It should be noted that regarding the contact between the surface treatment agent and the glass cloth, examples include immersing the glass cloth in the surface treatment agent; and applying the surface treatment agent to the glass cloth using a roller coater, die coater, or gravure coater. As for the drying method of the surface treatment agent, examples include hot air drying and drying using electromagnetic waves.

[0144] Furthermore, examples of fiber opening methods include dry ice shot peening and bending with a low radius of curvature. This fiber opening process can be performed simultaneously with weaving or after weaving. It can be performed before or after hot cleaning, or simultaneously with hot cleaning, or simultaneously with or after the surface treatment described later.

[0145] The following processes can also be performed: dry ice shot peening; fiber opening process that combines with bending with a low radius of curvature to apply water pressure to the glass cloth; fiber opening process using high-frequency vibration with water (e.g., degassed water, ion-exchanged water, deionized water, electrolyzed cation water, or electrolyzed anion water, etc.) as the medium; and processing by roller-based pressure.

[0146] Dry ice shot peening is a method of spraying (blowing) dry ice particles with a diameter of 5 to 300 μm from a height of 5 to 1000 mm at an air pressure of 0.05 to 1 MPa. More preferably, it is a method of spraying dry ice particles with a diameter of 5 to 300 μm from a height of 5 to 600 mm at an air pressure of 0.1 to 0.5 MPa. Within this range, it is expected that the glass fiber will not be damaged, resulting in improved impregnation.

[0147] The bending process is a fiber-opening method in which the filaments are passed through a roller with a radius of curvature R = 2.5 mm or less, preferably R = 2.0 mm or less, more than twice, and more preferably more than 10 times. If the radius of curvature R = 2.5 mm or less, the adhesion between the filaments caused by the sizing agent and silane coupling agent can be fully separated, and the effect of improved impregnation can be easily predicted.

[0148] [Prepreg]

[0149] The prepreg of this embodiment comprises the aforementioned low-dielectric glass cloth and a matrix resin composition impregnated with the low-dielectric glass cloth. The prepreg having the aforementioned glass cloth exhibits higher adhesion to the resin, resulting in a higher yield of the final product. Furthermore, due to its excellent dielectric properties and moisture resistance, it can also provide printed circuit boards with minimal variation in dielectric constant caused by environmental factors, particularly high humidity environments.

[0150] The prepreg of this embodiment can be manufactured using conventional methods. For example, it can be manufactured by impregnating the glass cloth of this embodiment with a varnish obtained by diluting a matrix resin such as epoxy resin with an organic solvent, and then using a drying oven to evaporate the organic solvent and cure the thermosetting resin to stage B (semi-cured state).

[0151] As the base resin, any of thermosetting resins or thermoplastic resins can be used. There are no particular limitations on the thermosetting resin; examples include:

[0152] a) An epoxy resin that is cured by reacting a compound having an epoxy group and a compound having at least one of the groups that react with an epoxy group, such as amino, phenol, acid anhydride, hydrazide, isocyanate, cyanate, and hydroxyl, under conditions without a catalyst, or by adding a catalyst with reaction catalytic ability such as an imidazole compound, a tertiary amine compound, a urea compound, or a phosphorus compound.

[0153] b) A free radical polymerizable cured resin that uses a thermally decomposable catalyst or a photodecomposable catalyst as a reaction initiator to cure a compound having at least one of the groups allyl, methacryl, and acryloyl.

[0154] c) Maleimide triazine resin cured by reacting a compound having a cyanate ester group with a compound having a maleimide group;

[0155] d) Thermosetting polyimide resins cured by reacting maleimide compounds with amine compounds;

[0156] e) Benzooxazine resins, etc., which are cross-linked and cured by heating polymerization of compounds containing benzoxazine rings.

[0157] Furthermore, there are no particular limitations on the thermoplastic resin used; examples include polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, aromatic polyamide, polyetheretherketone, thermoplastic polyimide, insoluble polyimide, polyamide-imide, fluoropolymers, etc. Additionally, thermosetting resins and thermoplastic resins can be used in combination.

[0158] Printed circuit boards

[0159] The printed circuit board of this embodiment includes the aforementioned prepreg. That is, the printed circuit board of this embodiment has the aforementioned glass cloth and a cured product of a matrix resin composition impregnated with the aforementioned glass cloth. The printed circuit board of this embodiment has higher adhesion to the resin, resulting in a higher yield of the final product. Furthermore, due to its excellent dielectric properties and excellent moisture resistance, it also exhibits minimal variation in dielectric constant caused by the influence of the usage environment, especially high humidity environments. Moreover, by using the aforementioned glass cloth, it is possible to achieve a product with less environmental and human burden, good impregnation with low-dielectric resins, and fewer pores.

[0160] Example

[0161] The present invention will now be described in detail based on embodiments.

[0162] (Example 1)

[0163] Prepare L-sized glass cloth (pattern 1078: average filament diameter 5μm, warp yarn density 54 yarns / inch, weft yarn density 54 yarns / inch, thickness 0.0046cm). Perform degreasing, surface treatment, and fiber opening treatment on the prepared glass cloth to obtain glass cloth 1.

[0164] As a degreasing treatment, in order to heat-decompose the spinning and weaving slubs adhering to the glass cloth, the glass cloth is placed in a heating furnace at an atmosphere temperature of 350°C to 400°C for 60 hours.

[0165] After degreasing, the glass cloth is surface-treated using a silane coupling agent. For the silane coupling agent, methacryloxypropyltrimethoxysilane (manufactured by Toray Dow Corning; Z6030) is used. The glass cloth is immersed in a treatment solution obtained by dispersing the methacryloxypropyltrimethoxysilane in water. Then, after extruding the liquid from the glass cloth, it is dried. Through the above treatment, the glass cloth is subjected to silane coupling agent treatment (surface treatment).

[0166] As a fiber-opening process, a method was adopted to spray dry ice particles of 5-50 μm using an air pressure of 0.4 MPa.

[0167] Using the evaluation method described later, the converted bending stiffness “(E1 / T1) / (W1 / L1)” is calculated, and it is confirmed that the specified area in the glass cloth 1 satisfies equation (1), that is, the glass cloth of this embodiment is obtained.

[0168] (Example 2)

[0169] As a fiber-opening process, the glass cloth was bent 10 times with a radius of curvature R = 1 mm. Otherwise, the glass cloth 2 was obtained by the same method as in Example 1. Using the evaluation method described later, the converted bending stiffness "(E1 / T1) / (W1 / L1)" was calculated, and it was confirmed that the specified area in the glass cloth 2 satisfies Equation (1), that is, the glass cloth of this embodiment was obtained.

[0170] (Example 3)

[0171] Using L-type glass cloth (style 3313: average filament diameter 6μm, warp yarn penetration density 60 yarns / inch, weft yarn penetration density 62 yarns / inch, thickness 0.0073cm), glass cloth 3 was obtained using the same method as in Example 1. Using the evaluation method described later, the converted bending stiffness "(E1 / T1) / (W1 / L1)" was calculated, and it was confirmed that the specified area in glass cloth 3 satisfies equation (1), that is, the glass cloth of this embodiment was obtained.

[0172] (Example 4)

[0173] Using L-type glass cloth (style 3313: average filament diameter 6μm, warp yarn penetration density 60 yarns / inch, weft yarn penetration density 62 yarns / inch, thickness 0.0073cm), glass cloth 4 was obtained by the same method as in Example 2. Using the evaluation method described later, the converted bending stiffness "(E1 / T1) / (W1 / L1)" was calculated, and it was confirmed that the specified area in glass cloth 4 satisfied equation (1), that is, it was confirmed that the glass cloth of this embodiment was obtained.

[0174] (Example 5)

[0175] Using L-sized glass cloth (style 2116: average filament diameter 7μm, warp yarn penetration density 60 yarns / inch, weft yarn penetration density 58 yarns / inch, thickness 0.0093cm), as the fiber opening treatment, dry ice particles of 10μm to 200μm were used. Otherwise, glass cloth 5 was obtained by the same method as in Example 1. Using the evaluation method described later, the converted bending stiffness "(E1 / T1) / (W1 / L1)" was calculated, and it was confirmed that the specified area in glass cloth 5 satisfies equation (1), that is, the glass cloth of this embodiment was obtained.

[0176] (Example 6)

[0177] Using L-type glass cloth (style 2116: average filament diameter 7μm, warp yarn penetration density 60 yarns / inch, weft yarn penetration density 58 yarns / inch, thickness 0.0093cm), glass cloth 6 was obtained using the same method as in Example 2. Using the evaluation method described later, the converted bending stiffness "(E1 / T1) / (W1 / L1)" was calculated, and it was confirmed that the specified area in glass cloth 6 satisfied equation (1), that is, the glass cloth of this embodiment was obtained.

[0178] (Comparative Example 1)

[0179] As a fiber-opening process, fiber opening was performed using a columnar stream sprayed from a high-pressure water sprayer at 0.9 MPa. Otherwise, the glass cloth was obtained using the same method as in Example 1. The equivalent bending stiffness “(E1 / T1] / (W1 / L1)” was calculated using the evaluation method described later.

[0180] (Comparative Example 2)

[0181] As a fiber-opening process, fiber opening was performed using a columnar stream sprayed from a 1.4 MPa high-pressure water sprayer. Otherwise, the glass cloth was obtained using the same method as in Example 3. The equivalent bending stiffness "(E1 / T1) / (W1 / L1)" was calculated using the evaluation method described later.

[0182] (Comparative Example 3)

[0183] As a fiber-opening process, fiber opening was performed using a columnar stream sprayed from a 1.7 MPa high-pressure water sprayer. Otherwise, the glass cloth was obtained using the same method as in Example 5. The equivalent bending stiffness "(E1 / T1) / (W1 / L1)" was calculated using the evaluation method described later.

[0184] [Measurement and Evaluation]

[0185] Various measurements and evaluations were performed on the glass cloths of the examples and comparative examples.

[0186] (Thickness measurement)

[0187] The thicknesses T1 and T2 of the glass cloth are determined as follows.

[0188] According to section 7.10 of JIS R 3420, using a micrometer, the spindle is rotated quietly until it gently contacts the measuring surface parallel to the surface, and the reading is taken after the ratchet emits three clicks. It should be noted that JIS R3420 specifies general test methods for glass fibers and products such as glass cloth using glass fibers.

[0189] (Infeed interval of warp and weft yarns)

[0190] Using a microscope, the number of glass yarn threads per inch was measured to obtain the insertion density (threads / inch). Based on this, the insertion intervals for the warp and weft yarns were determined. The value obtained for the warp yarns was used as the insertion interval L1 (cm) in Equation (1). The value obtained for the weft yarns was used as the insertion interval L2 (cm) in Equation (2).

[0191] (Measurement of yarn width)

[0192] The yarn width is determined using a high-precision camera. Specifically, the yarn width is determined by observing a portion of the glass cloth at any location with a size of 100mm x 100mm or larger. The value obtained for the warp yarn is used as the yarn width W1 (cm) in equation (1). Additionally, the value obtained for the weft yarn is used as the yarn width W2 (cm) in equation (2).

[0193] (Determination of bending stiffness)

[0194] The bending stiffness of the glass cloth was measured using a "KES-FB2-A Bending Characteristic Tester" manufactured by KATO TECH CO.,LTD. First, a test piece measuring 10 cm in the warp direction and 10 cm in the weft direction (corresponding to the "area" in technical solution 1) was collected from the glass cloth of the examples and comparative examples. Then, a chuck was used to continuously hold the test piece within a 10 cm range in the weft direction. Specifically, a chuck with a 1 cm gap between the first and second chuck portions and approximately parallel to each other was used. The first and second chuck portions were used to continuously hold the test piece within a 10 cm range in the weft direction, with the center of the first and second chuck portions overlapping the centerline of the test piece (see reference). Figure 1 and Figure 2 (a)

[0195] As described above, the chuck holds the sample piece at a curvature K = -2.5 to +2.5 (cm). -1 A pure bending test with constant velocity curvature was conducted within the range of 0.50 cm / s. -1 / Second).

[0196] First bend: From K=0 to K=+2.5, bend the test piece in such a way that one side of the surface becomes a "valley" (see reference). Figure 2 (b)

[0197] Second bend: From K=+2.5 through K=0 to K=-2.5, bend the test piece in such a way that the other side of the test piece becomes a "valley" (see reference). Figure 2 (c)).

[0198] Third bend: From K=-2.5 through K=0 to K=+2.5, bend the test piece in such a way that one side of the surface becomes a "valley" (see reference). Figure 2 (b)

[0199] In the first, second, and third bends, the warp yarns of the glass cloth in the test piece are bent. Specifically, in the first, second, and third bends, the valley bottom line of the valley created by the bend is bent in such a way that it follows the weft direction of the weft yarns of the glass cloth. More specifically, in the first, second, and third bends, the valley bottom line of the valley created by the bend is bent in such a way that it overlaps with the center line of the test piece.

[0200] Here, the bending stiffness obtained in the "third bend" within the range of K = 0.5 to K = +1.5 is measured as the second bending stiffness. The obtained value is used as the second bending stiffness E1 (N·cm) in equation (1). 2 / cm).

[0201] Similarly, the weft yarns from the glass cloth are bent, specifically in the first, second, and third bends, so that the bottom line of the valley created by the bend is along the warp direction of the warp yarns from the glass cloth; more specifically, in the first, second, and third bends, the bottom line of the valley created by the bend is bent so that it overlaps with the center line of the test piece. The bending stiffness obtained in the "third bend" within the range of K = 0.5 to K = +1.5 is measured as the second bending stiffness, and the obtained value is used as the bending stiffness E2 (N·cm) in equation (2). 2 / cm). It should be noted that the measurement environment was set at approximately 25°C and approximately 60% RH.

[0202] It should be noted that the term "second time" in the "second bending" of this embodiment is used with the intention of "the second bending that increases the curvature K".

[0203] In the first bend (from K=0 to K=+2.5);

[0204] The second bend (from K=+2.5 through K=0 to K=-2.5);

[0205] During the third bend (from K = -2.5 via K = 0 to K = +2.5), the stiffness in the range from K = 0.5 to K = +1.5 in the "third bend" that increases the curvature K for the second time is equivalent to the "second bend stiffness" in this embodiment.

[0206] (Evaluation of resin impregnation)

[0207] The glass cloth samples were taken in sizes of 50mm x 50mm or larger. Sampling was performed without bending or contact with the measurement area. Evaluation was conducted by counting the number of pores when castor oil (manufactured by Hayashi Junya Kogyo Co., Ltd.) at a liquid temperature of 24°C to 26°C was immersed in the sampled glass cloth for a specified time. A high-precision camera (frame size: 5120 x 5120 pixels) was set up perpendicular to the glass cloth. An LED light (PowerFlash Bar type illumination manufactured by CCS Co., Ltd.) was positioned 15cm away from the glass cloth, sandwiching it from the front and side. Light was then shone from both sides of the glass cloth.

[0208] Then, the number of pores larger than 160 μm existing between the glass filaments was measured using a high-precision camera (frame size: 5120×5120 pixels) within a 32 mm × 32 mm field of view. Measurements were taken three times, and the average value was used as the pore count. Pores correspond to the portion not impregnated with the matrix resin. Therefore, a lower pore count in the glass cloth indicates superior impregnation with the matrix resin.

[0209] (Determination of the amount of attached particles)

[0210] To prepare for the measurement, a piece of glass cloth cut to 4 cm squares was attached to the sample stage using carbon double-sided tape. Using a Keyence VHX-D500 microscope, observations of 1325 μm were performed along both the warp and weft threads, for a total of five repetitions. The frequency of particulate matter adhering to the glass cloth was determined based on the number of observed particles and the observation length. The number of adhering particles (particles / μm) was then calculated based on the obtained frequency.

[0211] <Measurement Conditions>

[0212] Measurement mode: Ultra-deep observation mode

[0213] Multiplier: 1000x

[0214] Preset: 25mm

[0215] (Determination of latitude slope)

[0216] The weft skew was determined as follows. First, the weft skew of the sample was determined according to JIS L1096. Specifically, one weft yarn in a 1000mm wide glass cloth stretched on a pair of rollers was visually observed. Using the TD tangent of the rollers and cloth as the reference line, the displacement from the reference line was measured, and the difference between the maximum and minimum displacement values ​​was calculated as the weft skew. This operation was performed 5 times, and the average value was calculated.

[0217] Then, the weft skew is calculated from the weft skew relative to the roll width. It should be noted that the weft skew is expressed by the following formula:

[0218] The weft skew (%) = {(weft skew) / (roller width)} × 100.

[0219] (Evaluation of the lint on the fiberglass cloth)

[0220] A tension of 100 N / 1000 mm was applied to the glass cloth obtained in the above embodiments and comparative examples using a roller-to-roll inspection table. Then, while irradiating with a halogen lamp, the tension was visually determined per 1 m. 2 The number of hairs (protrusions) larger than 1 mm (number / m) 2 ).

[0221] (Calculation of converted bending stiffness)

[0222] Using the values ​​obtained as described above, the converted bending stiffness is calculated according to equations (1) and (2). It should be noted that the thicknesses T1 and T2 are the same in each embodiment and comparative example.

[0223] (Prepreg and Printed Circuit Board Fabrication)

[0224] The glass cloth used in the embodiments can be used to manufacture prepregs and printed circuit boards using conventional methods. Furthermore, the desired functions have been confirmed to be performed on these prepregs and printed circuit boards.

[0225] The results relating to the examples and comparative examples are shown in Table 1.

[0226] [Table 1]

[0227]

[0228] Explanation of reference numerals in the attached figures

[0229] 10. Glass cloth; 11. Area (a designated area in the glass cloth); 11A: One side face; 11B: The other side face; 12. Chuck; 12a: First chuck section; 12b: Second chuck section; 13. Spacing; 14. Center between the first and second chuck sections; 15. Center line of the area; 16. Valley line; Lmd: Warp direction; Ltd: Weft direction.

Claims

1. A type of glass cloth, which is woven from glass yarn containing multiple glass filaments as warp and weft yarns, and surface-treated with a surface treatment agent, wherein, The glass cloth includes a defined area. The region is given by the following formula (1): (E1 / T1) / (W1 / L1)...(1) is greater than 0 and less than 0.

14. In the formula, E1 represents a curvature of 2.5cm. -1 The curvature during the second bend is 0.5 to +1.5 cm. -1 The second bending stiffness per unit length between them, in N·cm 2 / cm, T1 represents the thickness of the region, in cm. L1 represents the warp yarn insertion interval, in cm. W1 represents the warp width, in cm. The valley bottom line of the valley created by the bending is bent in a manner that follows the weft direction.

2. The glass cloth according to claim 1, wherein, The equation (1) is greater than 0 and less than 0.

13.

3. The glass cloth according to claim 1, wherein, The thickness T1 of the region is 0.002 to 0.013 cm.

4. The glass cloth according to claim 1, wherein, The warp yarn insertion interval L1 is 0.021 to 0.25 cm.

5. The glass cloth according to claim 1, wherein, The number of particles attached to the region is less than 100 per μm.

6. The glass cloth according to claim 1, wherein, The surface treatment agent contains a silane coupling agent with unsaturated double bonds that have free radical reactivity.

7. The glass cloth according to claim 1, wherein, The number of fibers longer than 1 mm observed when a tension of 100 N / 1000 mm was applied by roller-to-roll was 10 fibers / m. 2 The weft slant of the weft yarn is below 4%.

8. The glass cloth according to claim 1, wherein, The glass cloth includes a region that satisfies the following formula (2), namely (E2 / T2) / (W2 / L2)...(2) greater than 0 and less than 0.

14. In the formula, E2 represents a curvature of 2.5cm. -1 The curvature during the second bend is 0.5 to +1.5 cm. -1 The second bending stiffness per unit length between them, in N·cm 2 / cm, T2 represents the thickness of the region, in cm. L2 represents the weft yarn insertion interval, in cm. W2 indicates the weft width, in cm. The valley bottom line of the valley created by the bending is bent in a manner that follows the warp direction.

9. The glass cloth according to claim 8, wherein, Equation (2) is greater than 0 and less than 0.

13.

10. The glass cloth according to claim 8, wherein, The thickness T2 of the region is 0.002 to 0.013 cm.

11. The glass cloth according to claim 8, wherein, The weft yarn insertion interval L2 is 0.021 to 0.25 cm.

12. The glass cloth according to claim 1, wherein, The amount of particles attached to the region is 0 per μm.

13. The glass cloth according to claim 12, wherein, The particles are inorganic and / or organic particles with a diameter of less than 3 μm.

14. The glass cloth according to claim 13, wherein, The inorganic particles are at least one selected from the group consisting of colloidal silica, crystalline silica, aluminum oxide, and boron nitride. The organic microparticles are at least one selected from the group consisting of polyphenylene ether resin, epoxy resin, and styrene-based elastomers.

15. The glass cloth according to claim 8, wherein, The L1 and L2 and / or the W1 and W2 are anisotropic, the anisotropic values ​​of the L1 and L2 are different, and the anisotropic values ​​of the W1 and W2 are different.

16. A prepreg, wherein, The prepreg comprises a glass cloth according to any one of claims 1 to 15 and a matrix resin composition impregnated in the glass cloth.

17. A printed circuit board, wherein, The printed circuit board has a glass cloth as described in any one of claims 1 to 15 and a cured product of a matrix resin composition impregnated in the glass cloth.

18. A method for manufacturing glass cloth, comprising the method for manufacturing the glass cloth of claim 1, wherein, The manufacturing method of this glass cloth includes a fiber-opening process involving blowing dry ice particles.

19. The method for manufacturing glass cloth according to claim 18, wherein, Fiber opening is performed by bending with a curvature radius of less than 2.5 mm.

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