Glass cloth, prepreg, and printed wiring board

Abstract

Glass cloth, prepreg, and printed wiring board. [Problem] The present invention aims to provide a low-dielectric glass cloth in which anisotropy of stress-strain characteristics is reduced, and a prepreg and a printed wiring board using the low-dielectric glass cloth. [Means for solving the problem] A glass cloth is provided, which is a glass cloth having a thickness of 40 μm or more and 100 μm or less, and in which glass filaments having a number of 120 or more and 500 or less are woven as warp filaments and weft filaments, the difference between the number of the filaments constituting the warp filaments and the number of the filaments constituting the weft filaments is 3 or less, the lower limit value of the filament width of the warp filaments is a value obtained by the following formula (1): 40 x α + 102 … Formula (1) {in the formula, α represents the average diameter (μm) of the filaments}, the ratio of the filament width of the warp filaments to the filament width of the weft filaments (warp filament width / weft filament width) divided by the average diameter of the filaments is a warp-weft filament width ratio coefficient of 0.125 or more and 0.142 or less.

Description

Technical Field

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

[0002] With the increasing sophistication of mobile communication systems and the development of AI and IoT in recent years, printed circuit boards (PCBs) used in high-end servers, routers / switches, supercomputers, base stations, and other communication equipment or measuring instruments are required to have high-capacity, high-speed data communication and / or signal processing, as well as high reliability. Therefore, there is an even stronger demand for reducing dimensional variations or warpage / twist during the PCB manufacturing process, or reducing the anisotropy of dimensional variations caused by heating.

[0003] As a method to improve the anisotropy of dimensional changes, warping / twisting, or heating-induced dimensional changes in the printed wiring board manufacturing process, glass cloths, such as those in Patent Documents 1 to 9, have been proposed.

[0004] Patent Document 1 discloses a glass cloth whose width direction difference is less than 10% when the elongation in the warp direction is less than 10% when a load of 50 N / inch is applied in the stress-deformation curve as a way to improve substrate warping during the molding of printed wiring boards.

[0005] Patent document 2 discloses a glass cloth with a thickness of 10 to 50 μm that is flattened by low tension (less than 49 N / m per 1 mm), so that the cross-sectional shape and undulation of the warp and weft yarns are the same, and the anisotropy in the XY direction is improved.

[0006] Patent document 3 discloses a method for obtaining a glass cloth with well-balanced opening of warp and weft fibers, free from wrinkles or coil bends, by opening the fibers under conditions where tension does not play a role.

[0007] Patent document 4 discloses that the diameter of the weft filament is greater than that of the warp filament, and the weft / warp ratio is set to be greater than or equal to 1.01 and less than 1.27, resulting in a glass cloth with small anisotropy and little warping / twisting due to dimensional changes.

[0008] Patent document 5 discloses that by setting the fabric density to be equal to the warp and weft (warp / weft ratio of 0.9 to 1.1), a glass cloth with excellent dimensional stability is formed.

[0009] Patent document 6 discloses that by adjusting the spacing between glass filaments, the relationship between fabric density and weaving shrinkage rate, and the bulk density to a specific range, glass cloth with small deviations in dimensional changes and small anisotropy in the longitudinal and transverse directions can be obtained.

[0010] Patent documents 7 and 8 disclose methods to reduce dimensional deviations in glass cloth with large warp and weft widths and small gaps between warp and weft yarns.

[0011] Patent document 9 discloses that by having small deviations in the width of both warp and weft yarns, and by having flattened yarn bundles for both warp and weft yarns and reducing the undulation angle of intersecting yarns, glass fibers and glass cloth with small dimensional variations are formed.

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent Document 1: Japanese Patent Application Publication No. 2017-132651

[0015] Patent Document 2: International Publication No. 2004 / 027136

[0016] Patent Document 3: Japanese Patent Application Publication No. 2002-38367

[0017] Patent Document 4: International Publication No. 2011 / 024870

[0018] Patent Document 5: Japanese Patent Application Publication No. 11-10711

[0019] Patent Document 6: Japanese Patent Application Publication No. 11-10712

[0020] Patent Document 7: Japanese Patent Application Publication No. 5-28065

[0021] Patent Document 8: Japanese Patent Application Publication No. 10-37038

[0022] Patent Document 9: Japanese Patent Application Publication No. 2006-52473 Summary of the Invention

[0023] The problem the invention aims to solve

[0024] While Patent Document 1 describes an improvement in the warpage of the glass cloth, it does not necessarily improve the anisotropy of the stress-deformation curve of the glass cloth. Because glass cloth is composed of warp and weft yarns, it is not possible to not only ensure that the elongation of the warp yarns under a certain load is equal in the width direction, but also to improve anisotropy. Therefore, even regarding the warpage of the glass cloth described in Patent Document 1, there is still room for improvement.

[0025] The anisotropy improvement method described in Patent Document 2 is effective in reducing anisotropy for glass cloth with few filaments and thinness, but for glass cloth with more than 200 filaments and a thickness of more than 40 μm, there is still room for improvement in terms of anisotropy of the stress-deformation curve.

[0026] The glass cloth manufacturing method described in Patent Document 3 describes that fiber opening is performed while the glass cloth is being transported in a clamped support state at its upper limit. It is described that the suppression of coil bending is effective, but there is a problem that the anisotropy of the stress-deformation curve is not improved.

[0027] Although the anisotropy of the stress-strain (SS) properties of the glass cloth described in Patent Document 4 has been improved, there are problems such as in-plane deviation of resin content and large deviation of hole precision due to the use of glass fibers with different counts for the warp and weft, resulting in a lack of practicality.

[0028] The glass cloth described in Patent Document 5 has an anisotropy problem that cannot improve the SS properties, even if the fabric density of the warp and weft yarns is the same.

[0029] The glass cloths described in Patent Documents 6 and 7 suffer from problems such as a large difference in fabric density between the warp and weft yarns, resulting in significant anisotropy in pore processing properties and heating dimensional changes (XY). Furthermore, both documents also exhibit the problem that if the difference in fabric density is large, the anisotropy of the stress-deformation curve is not improved.

[0030] Patent Document 8 describes a method for suppressing dimensional deviations in glass cloth, but it is insufficient in terms of anisotropy of the stress-deformation curve and dimensional deviations. Furthermore, the low weft fiber coverage and poor uniformity of glass distribution within the glass cloth surface lead to skew problems, making it unsuitable for high-speed mobile communication applications.

[0031] The glass cloth described in Patent Document 9 reduces dimensional variation by decreasing the undulation angle of the intersecting warp and weft yarns, but it does not improve the anisotropy of the warp and weft directions.

[0032] The present invention was made in view of the above-mentioned problems, and its object is to provide a low-dielectric glass cloth with reduced anisotropy of stress-deformation properties, as well as a prepreg and printed wiring board using the low-dielectric glass cloth.

[0033] Solution for solving the problem

[0034] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that by corresponding to the diameter of the filament and keeping the warp width and the ratio of the warp width to the weft width within a specified range, the above-mentioned problems can be solved, thus completing the present invention.

[0035] That is, the present invention is as described below. (1)

[0037] A type of glass cloth, which is woven from glass fibers with 120 to 500 filaments as warp and weft yarns, and has a thickness of 40 μm to 100 μm.

[0038] The difference between the number of filaments constituting the aforementioned warp yarn and the number of filaments constituting the aforementioned weft yarn is 3 or less.

[0039] The lower limit of the aforementioned warp width is above the value obtained using the following formula (1).

[0040] 40×α+102…Equation (1)

[0041] {In the formula, α: the average diameter of the warp filaments (μm)}

[0042] Furthermore, the ratio of the width of the warp yarn to the width of the weft yarn (warp yarn width / weft yarn width) divided by the aforementioned average diameter of the filaments, has a warp-to-weft yarn width ratio coefficient of 0.125 or higher and 0.142 or lower. (2)

[0044] According to the glass cloth described in Project 1, the thickness of the aforementioned glass cloth divided by the width of the aforementioned warp yarns, and the warp yarn width-thickness crimping shape index, are values ​​below those obtained using the following formula (2).

[0045] 0.2305×ln(α)-0.227…Equation (2)

[0046] {In the formula, α: the average diameter of the warp filaments (μm)}. (3)

[0048] A type of glass cloth, which is woven from glass fibers with 120 to 500 filaments as warp and weft yarns, and has a thickness of 40 μm to 100 μm.

[0049] The difference between the number of filaments constituting the aforementioned warp yarn and the number of filaments constituting the aforementioned weft yarn is 3 or less.

[0050] The lower limit of the aforementioned warp width is above the value obtained using the following formula (1).

[0051] 40×α+102…Equation (1)

[0052] {In the formula, α: the average diameter of the warp filaments (μm)}

[0053] Furthermore, the warp width-thickness curl shape index, obtained by dividing the thickness of the aforementioned glass cloth by the width of the aforementioned warp yarn, is below the value calculated using the following formula (2).

[0054] 0.2305×ln(α)-0.227…Equation (2)

[0055] {In the formula, α: the average diameter of the warp filaments (μm)}. (4)

[0057] The glass cloth according to any one of items 1 to 3, wherein the difference between the fabric density of the aforementioned warp yarns and the fabric density of the aforementioned weft yarns is 5 or less. (5)

[0059] The glass cloth according to any one of items 1 to 4, wherein the sum of the width of the aforementioned warp yarn and the width of the aforementioned weft yarn is 720 μm or more. (6)

[0061] According to any one of items 1 to 5, the weft yarn occupancy rate Y, which represents the proportion of weft yarns in the MD direction and is calculated using the following formula (3), is 88% or more and 104% or less.

[0062] Y = F / (25000 / G) × 100… Equation (3)

[0063] {In the formula, F is the weft width (μm), and G is the fabric density of the weft (threads / 25mm)}. (7)

[0065] The glass cloth according to any one of items 1 to 6, wherein the ratio (A / B ratio) of the elongation A in the weft direction generated when a load of 50N is applied to a width of 25mm in the weft direction to the elongation B in the warp direction generated when a load of 50N is applied to a width of 25mm in the warp direction is 1.0 or more and 1.9 or less. (8)

[0067] The glass cloth according to any one of items 1 to 7, wherein the elongation A in the weft direction when a load of 50N is applied per 25mm width in the weft direction and the elongation B in the warp direction when a load of 50N is applied per 25mm width in the warp direction are both 0.3% or more and 0.95% or less. (9)

[0069] The glass cloth according to any one of items 1 to 8 is composed of glass fibers with an elastic modulus of 50 GPa or more and 70 GPa or less. (10)

[0071] The glass cloth according to any one of items 1 to 9 is composed of glass fibers with an elastic modulus of 50 GPa or more and 64 GPa or less. (11)

[0073] A type of glass cloth, comprising glass filaments with a warp and weft yarns consisting of 120 to 500 filaments, and a thickness of 40 μm to 100 μm.

[0074] The difference between the number of filaments constituting the aforementioned warp yarns and the number of filaments constituting the aforementioned weft yarns is 3 or less, and

[0075] The ratio (A / B ratio) of the elongation A in the weft direction when a load of 50N is applied to every 25mm width in the weft direction to the elongation B in the warp direction when a load of 50N is applied to every 25mm width in the warp direction is 1.0 or more and 1.9 or less. (12)

[0077] A type of glass cloth, comprising glass fibers with an average number of 120 to 500 filaments on both the warp and weft, and a thickness exceeding 40 μm but less than 100 μm.

[0078] The difference between the number of filaments constituting the aforementioned warp yarns and the number of filaments constituting the aforementioned weft yarns is 3 or less, and

[0079] The elongation A in the weft direction when a load of 50N is applied to every 25mm width in the weft direction, and the elongation B in the warp direction when a load of 50N is applied to every 25mm width in the warp direction, are both greater than 0.3% and less than 0.95%. (13)

[0081] According to the glass cloth described in Project 11 or 12, the weft yarn occupancy rate Y, which represents the proportion of weft yarns in the MD direction and is calculated using the following formula (3), is 88% or more and 104% or less.

[0082] Y = F / (25000 / G) × 100… Equation (3)

[0083] {In the formula, F is the weft width (μm), and G is the fabric density of the weft (threads / 25mm)}. (14)

[0085] The glass cloth according to any one of items 11 to 13 is composed of glass fibers with an elastic modulus of 50 GPa or more and 70 GPa or less. (15)

[0087] The glass cloth according to any one of items 11 to 14 is composed of glass fibers with an elastic modulus of 50 GPa or more and 64 GPa or less.

[0088] The effects of the invention

[0089] According to the present invention, a glass cloth with excellent isotropic stress-deformation properties, as well as a prepreg and a printed wiring board using the glass cloth, can be provided. Attached Figure Description

[0090] Figure 1 A graph showing the measurement results of the elongation characteristics of type 1017 low dielectric glass cloth (conventional).

[0091] Figure 2 A graph showing the measurement results of the elongation characteristics of type 1027 low dielectric glass cloth (conventional).

[0092] Figure 3 A graph showing the measurement results of the elongation characteristics of type 1037 low dielectric glass cloth (conventional).

[0093] Figure 4 A graph showing the measurement results of the elongation characteristics of type 1067 low dielectric glass cloth (conventional).

[0094] Figure 5 A graph showing the measurement results of the elongation characteristics of a 1078 type low dielectric glass cloth (conventional, comparative example 3).

[0095] Figure 6 A graph showing the measurement results of the elongation characteristics of a 3313 type low dielectric glass cloth (conventional, comparative example 6).

[0096] Figure 7 A graph showing the measurement results of the elongation characteristics of type 2116 low dielectric glass cloth (conventional, comparative example 8).

[0097] Figure 8 A graph showing the measurement results of the elongation characteristics of a 1078 type low dielectric glass cloth (invention of this application, Example 4).

[0098] Figure 9 A graph showing the measurement results of the elongation characteristics of a 3313 type low dielectric glass cloth (the present invention, Example 6).

[0099] Figure 10 A graph showing the measurement results of the elongation characteristics of a 2116 type low dielectric glass cloth (the present invention, Example 8). Detailed Implementation

[0100] The embodiments of the present invention (hereinafter referred to as "this embodiment") will be described in detail below, but the present invention is not limited thereto and various modifications can be made without departing from its spirit.

[0101] The technical features of this embodiment will be described in more detail below.

[0102] The glass cloth of the first embodiment is a glass cloth with a thickness of 40μm or more and 100μm or less, in which the warp and weft threads are composed of glass filaments with a number of filaments of 120 or more and 500 or less, and the difference between the number of filaments constituting the warp threads and the number of filaments constituting the weft threads is 3 or less.

[0103] The lower limit of the width of the aforementioned warp threads is above the value obtained using the following formula (1).

[0104] 40×α+102…Equation (1)

[0105] {In the formula, α: the average diameter of the warp filaments (μm)}

[0106] Furthermore, the ratio of the width of the warp yarn to the width of the weft yarn (warp yarn width / weft yarn width) divided by the average diameter of the filaments, has a warp-to-weft yarn width ratio coefficient of 0.125 or higher and 0.142 or lower.

[0107] The glass cloth of this embodiment reduces the anisotropy of stress-deformation characteristics by keeping the warp and weft yarn widths within a specific range and the undulation structure of the warp and weft yarns within a specific range. Furthermore, the glass cloth of this embodiment is also characterized by eliminating bulkiness by forming the undulation structure of the warp and weft yarns within a specific range, thus obtaining a glass cloth with small thickness and excellent smoothness.

[0108] To reduce dimensional variations, warpage, or twisting in printed circuit boards (PCBs), and to minimize anisotropy in dimensional changes due to heating, enhancing the tensile stress resistance of the glass cloth used as a reinforcing material while reducing its longitudinal / transverse anisotropy is effective. Due to its woven structure, glass cloth exhibits tensile elongation in one direction (XY plane). This elongation stems not only from the reinforcing rigidity of the glass fibers but also significantly from the undulations of those fibers. Therefore, adjusting the balance of the undulations in the glass fibers constituting the glass cloth to optimize the elongation characteristics in the XY plane can be considered one method for improving the dimensional stability of PCBs.

[0109] For the glass cloth in this embodiment, the thickness is 40 μm or more and 100 μm or less. A thickness of 40 μm or more provides the strength required for large-sized or multi-layered printed circuit boards used in communication equipment or measuring instruments such as high-end servers, high-end routers / switches, supercomputers, and base stations. Furthermore, a thickness of 100 μm or less allows for an increase in the number of layers in the multi-layered printed circuit board, enabling high-density transmission lines while maintaining the thickness of the multi-layered printed circuit board. The thickness of the glass cloth is preferably more than 40 μm, more preferably 41 μm or more, and even more preferably 42 μm or more; on the other hand, it is preferably 98 μm or less, and more preferably 96 μm or less. The thickness of the glass cloth can be measured using the method described in the embodiments below.

[0110] The glass cloth of this embodiment is a glass cloth woven from glass fibers with a warp and weft yarn count of 120 to 500 filaments or more. In this specification, the filament count can be the average number of filaments. The preferred range for the average number of filaments is 140 to 400, a more preferred range is 160 to 300, and a further preferred range is 180 to 250.

[0111] In addition, the difference between the number of filaments constituting the aforementioned warp yarn and the number of filaments constituting the aforementioned weft yarn is 3 or less, preferably 2 or less, more preferably 1 or less, and even more preferably 0.

[0112] By having a filament count of 120 or more and 500 or less, a difference of 3 or less between the warp and weft filament counts, and meeting other conditions of this embodiment, the surface smoothness, in-plane uniformity of glass distribution, and hole machinability are not compromised, and the elongation behavior when a load is applied to the XY plane can be made similar in the warp and weft directions.

[0113] By using glass filaments with 120 or more filaments as warp and weft, the strength required for large-sized or multi-layer printed wiring boards can be obtained. Furthermore, conventional glass cloths composed of glass filaments with an average filament length of 120 or more suffer from increased anisotropy in stress-deformation characteristics. However, this invention improves this anisotropy, thereby suppressing dimensional changes or warping / twisting during the printed wiring board manufacturing process, and / or reducing anisotropy in heating-induced dimensional changes, thus improving the reliability of the printed wiring.

[0114] The average diameter of the glass filaments constituting the warp and weft is preferably 4 μm or more and 9 μm or less. A more preferred range for the average diameter of the filaments is 4.3 μm or more and 8 μm or less, and a further preferred range is 4.5 μm or more and 7.6 μm or less. By ensuring that the filament diameter and the average number of filaments are within the above-mentioned ranges, glass cloth with a thickness of 40 μm to 100 μm can be formed, and the strength required for large-sized printed wiring boards or highly multilayer printed wiring boards is obtained, which is therefore preferable.

[0115] The average diameter of the filament can be determined using the method described in the examples below.

[0116] For the glass cloth of this embodiment, the width of the warp yarn is greater than or equal to the value obtained by the following formula (1).

[0117] 40×α+102(μm)…Equation (1)

[0118] {In the formula, α: the average diameter of the warp filaments (μm)}

[0119] The preferred range of the width of the warp yarn is the value obtained by formula (1B) or higher, the more preferred range is the value obtained by formula (1C) or higher, and the even more preferred range is the value obtained by formula (1D) or higher.

[0120] 40×α+103(μm)…Equation (1B)

[0121] 40×α+104(μm)…Equation (1C)

[0122] 40×α+105(μm)…Equation (1D)

[0123] {where α is defined as in equation (1) above}

[0124] If the width of the warp yarn is above the lower limit calculated using Equation 1 above, the thickness of the warp yarn in the z-direction decreases, thus reducing the undulation of the weft yarn. Furthermore, as the weft yarn undulation decreases, at the intersection of warp and weft yarns, the force exerted by the weft yarn on the alternating vertical opening of the warp yarn increases the undulation of the warp yarn. Therefore, the undulations of the warp and weft yarns become similar, their elongation characteristics become similar, and the anisotropy of the stress-deformation curve is reduced.

[0125] In addition, for the glass cloth of this embodiment, the width of the warp yarn is the value obtained by formula (4) below.

[0126] 30×α+250(μm)…Equation (4)

[0127] {In the formula, α: the average diameter of the warp filaments (μm)}

[0128] The preferred range of the width of the warp yarn is the value obtained by formula (4B) below, the more preferred range is the value obtained by formula (4C) below, and the even more preferred range is the value obtained by formula (4D) below.

[0129] 30×α+240(μm)…Equation (4B)

[0130] 30×α+230(μm)…Equation (4C)

[0131] 30×α+220(μm)…Equation (4D)

[0132] {where α is defined as in equation (4) above}

[0133] If the warp width exceeds the aforementioned upper limit, the weft yarns need to be arranged in a way that avoids significant undulations in the XY direction. Therefore, large weft yarn undulations increase the anisotropy of the stress-deformation curve. When the warp width is below the aforementioned upper limit, the weft yarn undulations decrease, and the anisotropy of the stress-deformation curve is reduced.

[0134] The manufacturing of glass cloth involves multiple processes such as sizing and washing, and fiber opening, which involve changes in the configuration of the filament bundles that make up the warp fibers, resulting in changes in the shape of the bundles. For example, the initial processing is carried out while the bundles are immersed in water. In this process, the warp fibers are widened uniformly and significantly. As a result, the processing force is reduced as much as possible in subsequent processes, and the tension acting on the warp fibers is adjusted to be small to suppress the shrinkage of the warp fibers. As a result, the lower limit of the width of the aforementioned warp fibers can be controlled above the value obtained by formula (1).

[0135] In addition, for controlling the lower limit of warp width, it is also effective to use glass fibers with uniform twisting quality and fewer narrow twisting intervals due to deviations as warp fibers.

[0136] Here, the width of the warp and weft threads in the glass cloth is the average value obtained by observing the surface of a 100mm × 100mm glass cloth sample under a microscope, determining the width of all threads, and dividing the total width by the total number of threads. In this case, if the width of the glass threads varies within the sample, the width of the part with the largest width is taken as the width of that thread.

[0137] For the glass cloth of this embodiment, the warp-to-weft width ratio coefficient, calculated by dividing the ratio of the warp width to the weft width (warp width / weft width) by the average diameter of the filaments, is 0.125 or higher and 0.142 or lower. A preferred range for the warp-to-weft width ratio coefficient is 0.129 or higher and 0.142 or lower, a more preferred range is 0.132 or higher and 0.141 or lower, and a further preferred range is 0.133 or higher and 0.140 or lower.

[0138] If the warp width is within the range of this invention and the warp-to-weft width ratio is above the lower limit mentioned above, the thickness of the weft in the z-direction is small, and therefore the undulation of the weft is small. Consequently, the undulation of the warp increases, and thus the anisotropy of the stress-deformation curve is reduced.

[0139] If the warp width is within the range of this invention and the warp-to-weft width ratio is below the aforementioned upper limit, then the high rigidity of the weft yarn is maintained. Therefore, when the undulation of the weft yarn decreases, the force that opens the warp yarn to the upper limit at the intersection with the warp yarn takes effect, and the undulation of the warp yarn increases. The anisotropy of the stress-deformation curve is reduced.

[0140] If the warp width is within the range of this invention and the warp-to-weft width ratio is within the above range, then the warp is given undulations, the weft undulations are reduced, and thus the anisotropy of the stress-deformation curve is reduced.

[0141] The manufacturing of glass cloth involves multiple processes such as sizing and washing, and fiber opening, in which the configuration of the warp filaments changes and the shape of the filament bundles changes. For example, the initial processing is carried out while the filaments are immersed in water. In this process, the warp filaments are widened uniformly and significantly. As a result, in subsequent processes, the processing force is minimized as much as possible, and the tension acting on the warp filaments is adjusted to be small to suppress warp filament shrinkage. As described above, the warp filament width is widened. At the same time, the weft filament widening is suppressed by the suppression effect of the weft filament widening achieved by widening the warp filaments and the suppression effect of the weft filament widening achieved by reducing the processing force of the fiber opening process. This suppresses the excessive expansion of the weft filament width, thereby controlling the warp-to-weft filament width ratio within the aforementioned range.

[0142] In addition, for controlling the warp-to-weft yarn width ratio, it is also effective to use glass fibers with uniform twisting quality and fewer narrow twisting intervals due to deviations for the warp yarn, and / or to use glass fibers with fewer wide twisting intervals due to deviations for the weft yarn.

[0143] In this embodiment, the sum of the warp and weft widths of the glass cloth is preferably 720 μm or more. A more preferred range is 730 μm or more, a further preferred range is 740 μm or more, and an even more preferred range is 750 μm or more. By having a sum of 720 μm or more, the thickness at the intersection of the warp and weft yarns is kept small due to the overlap in the z-direction thickness, thus suppressing the increase of warp and weft yarn undulations and reducing the elongation of the warp and weft yarns. Therefore, this is preferable.

[0144] For the glass cloth of this embodiment, the proportion of weft yarns in the longitudinal direction (MD) is preferably 88% or more and 104% or less. A more preferred range for the proportion of weft yarns in the longitudinal direction is 90% or more and 103% or less, a more preferred range is 91% or more and 102% or less, and a more preferred range is 92% or more and 102% or less.

[0145] The ratio of weft threads along the length direction refers to the weft thread occupancy rate, which is obtained by formula (3) and is the value Y obtained by dividing the width of the weft thread by the spacing of the weft threads.

[0146] Y=F / (25000 / G)×100…(3)

[0147] (In the formula, F is the width of the weft yarn (μm), and G is the fabric density of the weft yarn (threads / 25mm).)

[0148] If the weft yarn content is 88.0% or higher, the glass cloth exhibits excellent in-plane uniformity and surface smoothness. Therefore, the ratio of glass to resin becomes more uniform in the insulating layer composed of glass cloth and resin. Consequently, the signal propagation speed of multiple transmission lines formed on this insulating layer tends to become equal, resulting in small signal arrival time deviations and stable signal processing. Therefore, this glass cloth is preferred for mobile communication systems, AI, and IoT applications.

[0149] For example, by adjusting the fabric density of the weft yarns and the width of the weft yarns in the fiber opening process, the proportion of weft yarns in the length direction can be controlled within the above range.

[0150] The fabric density of the warp yarns in the glass cloth is preferably 40 or more threads per 25 mm and 70 or less threads per 25 mm. A more preferred range for the fabric density of the warp yarns is 45 or more threads per 25 mm and 65 or less threads per 25 mm, a further preferred range is 47 or more threads per 25 mm and 63 or less threads per 25 mm, and an even more preferred range is 48 or more threads per 25 mm and 62 or less threads per 25 mm.

[0151] Furthermore, the difference between the fabric density of the warp yarns and the fabric density of the weft yarns is preferably 5 or less. A more preferred range for the difference between the fabric density of the warp yarns and the fabric density of the weft yarns is 4.5 or less, a further preferred range is 4.0 or less, an even more preferred range is 3.5 or less, and a particularly preferred range is 3.0 or less.

[0152] The glass cloth, which uses glass fibers with a warp density within the above-mentioned range and a filament count within the range of the present invention, provides excellent reinforcing strength for the printed wiring board and forms a thickness of 40 μm or more and 100 μm or less, and is therefore preferred.

[0153] By ensuring that the difference between the fabric density of the warp yarns and the fabric density of the weft yarns is within the aforementioned range, and that the width of the warp yarns and the width of the weft yarns are within the range of this invention, the anisotropy of the stress-deformation characteristics is improved.

[0154] The glass cloth of the present invention preferably has a thickness of glass cloth divided by the width of the warp yarn, and the warp yarn width-thickness curl shape index is a value obtained by formula (2) below.

[0155] 0.2305×ln(α)-0.227…Equation (2)

[0156] {In the formula, α: the average diameter of the warp filaments (μm)}

[0157] If the curl shape index is less than or below the value obtained using equation (2), then the undulations of the warp and weft are similar, the elongation characteristics of the warp and weft are similar, and the anisotropy of the stress-deformation curve is reduced. That is, the elongation of the warp increases and the elongation of the weft decreases.

[0158] To ensure that the warp width-thickness crimp shape index is below the value calculated using equation (2), the method of controlling the warp width within the range of this invention is effective. By widening the warp width, the thickness of the warp in the z-direction decreases, which is reduced along with the undulation of the weft along the warp. By reducing the undulation of the weft, at the intersection of the warp and weft, the force by which the weft alternately opens the warp in the vertical direction becomes stronger, thus increasing the undulation of the warp. As a result, the undulations of the warp and weft smoothly combine, the thickness decreases, and therefore the warp width-thickness crimp shape index easily becomes below the value calculated using equation (2).

[0159] In addition, in processes such as the sizing and washing process and the fiber opening process, where the configuration of the filament bundles constituting the warp yarns changes and the shape of the bundles changes, the conditions between each process are controlled in such a way that the tension or processing force acting on the glass cloth becomes uniform in the width direction, and the adjustment is made in such a way that the deviation of the warp yarn width is reduced. As a result, the warp yarn width, thickness and curl coefficient can be controlled within the above range.

[0160] If the processing force is increased during the process of processing while the glass cloth or fiber bundle is immersed in water, the warp width can be widened while the deviation of the warp width is minimized, which is therefore preferable. It is also preferable from the viewpoint that the processing force for subsequent processing will not increase compared to processing while immersed in water, thus suppressing the expansion of the warp width deviation.

[0161] As a second embodiment of the glass cloth of the present invention, a glass cloth is provided, which is a glass cloth with a thickness of 40μm or more and 100μm or less, woven from glass filaments with a number of 120 or more and 500 or less as warp and weft filaments, wherein the difference between the number of filaments constituting the warp filaments and the number of filaments constituting the weft filaments is 3 or less.

[0162] The lower limit of the width of the aforementioned warp threads is above the value obtained using the following formula (1).

[0163] 40×α+102…Equation (1)

[0164] {In the formula, α: the average diameter of the warp filaments (μm)}

[0165] Furthermore, the thickness of the aforementioned glass cloth divided by the width of the warp yarn, and the warp yarn width-thickness curl shape index, are values ​​obtained using the following formula (2).

[0166] 0.2305×ln(α)-0.227…Equation (2)

[0167] {In the formula, α: the average diameter of the warp filaments (μm)}

[0168] The glass cloth of the first and second embodiments is characterized in that the difference between the elongation in the weft direction and the elongation in the warp direction is small, and the ratio (A / B ratio) of the elongation A in the weft direction when a load of 50N is applied per 25mm width in the weft direction to the elongation B in the warp direction when a load of 50N is applied per 25mm width in the warp direction is suppressed to 1.0 or more and 1.9 or less. The preferred range of the ratio (A / B ratio) of the elongation A in the weft direction to the elongation B in the warp direction is 1.0% or more and 1.8% or less, and the more preferred range is 1.0% or more and 1.7% or less.

[0169] The ratio (A / B ratio) of the elongation A in the weft direction when a load of 50N is applied to every 25mm width in the weft direction to the elongation B in the warp direction when a load of 50N is applied to every 25mm width in the warp direction can be controlled within the above range by adjusting the warp width and weft width to the range of the present invention.

[0170] Here, elongation refers to the value calculated as follows.

[0171] The elongation of glass cloth under tension in the warp or weft direction is determined according to the method described in section 7.4, Tensile Strength, of JIS R3420, General Test Method for Glass. In this JIS method, a test piece approximately 30 mm wide and 250 mm long is taken from both the warp and weft directions of the fabric. The ends of the test piece are untied to form a clamping section approximately 25 mm wide with a spacing of approximately 150 mm. The piece is then stretched at a speed of approximately 200 mm / min, and the load at break is determined. In this invention, to improve measurement accuracy, the stretching speed is set to approximately 5 mm / min. Otherwise, the tensile test is performed under the same conditions as the method specified in the JIS, and the displacement under a 50 N load applied to a 25 mm width of glass cloth is determined. The value obtained using the following formula is defined as "elongation".

[0172] Elongation = {(Interval under load - Interval under no load) / Interval under no load} × 100

[0173] If the ratio of the elongation A in the weft direction to the elongation B in the warp direction (A / B) is within the above range, there is a tendency to improve the occurrence of warping and twisting in the processing of the printed wiring board, the anisotropy of dimensional changes in the processing, and the anisotropy of dimensional changes due to heating, and a printed wiring board with high reliability can be obtained, which is therefore preferred.

[0174] Furthermore, the glass cloth of the present invention is characterized by low elongation in both the weft and warp directions. When a load of 50 N is applied per 25 mm width in each warp direction, the elongation A in the weft direction and the elongation B in the warp direction can both be suppressed to 0.3% or more and 0.95% or less, preferably 0.4% or more, and more preferably 0.5% or more. Additionally, both elongation A and B are preferably 0.94% or less, and more preferably 0.93% or less.

[0175] The elongation A in the weft direction and the elongation B in the warp direction when a load of 50N is applied per 25mm width in each filament direction can be controlled within the above range by adjusting the warp width, weft width, and crimp structure coefficient to the range of the present invention.

[0176] If the elongation in both the weft and warp directions is below the aforementioned upper limit, the reinforcing effect of the glass cloth is significant, minimizing warping / twisting, dimensional changes, and the coefficient of thermal expansion of the printed wiring board; therefore, this is preferable. Furthermore, if the elongation in both the weft and warp directions is below the aforementioned upper limit, deviations in the stress-deformation characteristics of the glass cloth in the width direction are minimized, and defects such as coil bending, tilting wrinkles, winding wrinkles, and slack in the glass cloth manufacturing process and the manufacturing process using the prepreg are suppressed; therefore, this is also preferable.

[0177] If the elongation in both the weft and warp directions is at or above the aforementioned lower limit, stress caused by resin curing shrinkage or softening during printed wiring board processing is relaxed, and warping and twisting are suppressed, which is therefore preferable. Furthermore, if the elongation in both the weft and warp directions is at or above the aforementioned lower limit, external stress is relaxed even during glass cloth processing or processing using prepregs containing glass cloth, thus suppressing the formation of wrinkles and curling wrinkles, which is also preferable.

[0178] As a third embodiment of the present invention, a glass cloth is provided, which is a glass cloth with a thickness of 40 μm and 100 μm, wherein the warp and weft yarns are composed of glass filaments with a number of filaments of 120 or more and 500 or less, the difference between the number of filaments constituting the warp yarns and the number of filaments constituting the weft yarns is 3 or less, and the ratio (A / B ratio) of the elongation A in the weft direction when a load of 50 N is applied to a width of 25 mm in the weft direction and the elongation B in the warp direction when a load of 50 N is applied to a width of 25 mm in the warp direction is 1.0 or more and 1.9 or less.

[0179] As a fourth embodiment of the present invention, a glass cloth is provided, which is a glass cloth with a thickness of more than 40 μm and less than 100 μm, wherein the warp and weft yarns are composed of glass filaments with an average number of filaments of 120 or more and less than 500, the difference between the number of filaments constituting the warp yarns and the number of filaments constituting the weft yarns is 3 or less, and the elongation A in the weft direction when a load of 50 N is applied to a width of 25 mm in the weft direction and the elongation B in the warp direction when a load of 50 N is applied to a width of 25 mm in the warp direction are both 0.3% or more and 0.95% or less.

[0180] The glass cloths of the third and fourth embodiments may share common technical features with those of the glass cloths of the first and second embodiments, as needed. The elastic modulus of the glass fibers constituting the glass cloths of the first to fourth embodiments is preferably 50 GPa or more and 70 GPa or less, more preferably 50 GPa or more and 64 GPa or less, further preferably 52 GPa or more and 64 GPa or less, and even more preferably 54 GPa or more and 60 GPa or less.

[0181] Glass fibers with an elastic modulus between 50 GPa and 70 GPa tend to have a greater elongation under load compared to E-glass fibers with an elastic modulus of 74 GPa, and their stress-deformation anisotropy also tends to be greater. Therefore, the present invention significantly reduces the anisotropy of stress-deformation characteristics, and is thus preferred. Furthermore, glass fibers with an elastic modulus between 50 GPa and 70 GPa are more susceptible to external stresses, and are preferred from the viewpoint of easily controlling the warp and weft widths within the configuration range of this embodiment.

[0182] The elastic modulus of the glass fiber was determined using the method described in the examples below.

[0183] (Other technical features of glass cloth)

[0184] There are no particular limitations on the weaving structure of glass cloth; examples include plain weave, mat weave, satin weave, and twill weave. Plain weave is preferred.

[0185] The preferred weight of the glass cloth (weight per unit area) is 8–250 g / m². 2 More preferably 20-150 g / m 2 Further optimization is needed for 30-110 g / m 2 , with a preferred strength of 36-100g / m 2 .

[0186] (Surface treatment)

[0187] Fiberglass cloth can be surface-treated using surface treatment agents. There are no particular limitations on surface treatment agents; examples include silane coupling agents. Water, organic solvents, acids, dyes, pigments, surfactants, etc., can be used in combination as needed.

[0188] There are no particular limitations on silane coupling agents; for example, compounds represented by formula (I) can be listed.

[0189] X(R) 3-n SiY n …(I)

[0190] (In the formula, X is an organic functional group having at least one of amino and unsaturated double bond groups, Y is each independently an alkoxy group, n is an integer of 1 to 3, and R is each independently a group selected from the group consisting of methyl, ethyl, and phenyl.)

[0191] In formula (I), X is preferably an organic functional group having at least three of the amino and unsaturated double bond groups, and X is more preferably an organic functional group having at least four of the amino and unsaturated double bond groups.

[0192] In formula (I), for Y, any of the above-mentioned alkoxy groups can be used, but from the viewpoint of stabilizing the glass cloth, an alkoxy group with 5 or fewer carbon atoms is preferred.

[0193] As silane coupling agents, specifically, examples 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, and 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-β-(N-benzylaminoethyl)-γ-aminopropyltriethoxysilane and its hydrochloride, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, methacryloyloxypropyltrimethoxysilane, acryloyloxypropyltrimethoxysilane and other known individual compounds or mixtures thereof.

[0194] [Method for manufacturing glass cloth]

[0195] The method for manufacturing glass cloth in this embodiment is not particularly limited, and examples include a weaving process that involves weaving glass fibers to obtain glass cloth, and a fiber-opening process that involves opening the glass fibers of the glass cloth. In addition, as needed, the method for manufacturing glass cloth may include a desizing process that removes the sizing agent adhering to the glass fibers of the glass cloth, and a surface treatment process using a silane coupling agent.

[0196] There are no particular restrictions on the weaving method if the weft and warp yarns are woven in a manner that forms a prescribed weaving structure. Furthermore, there are no particular restrictions on the fiber opening method; examples include methods using spray water (high-pressure water fiber opening), vibrating washing machines, ultrasonic water, and liquid rolling mills. Similarly, there are no particular restrictions on the desizing method; examples include methods using spray water (high-pressure water fiber opening), vibrating washing machines, and ultrasonic water to wash away the sizing agent; and methods using heat to remove the sizing agent. Additionally, as a surface treatment method, methods such as contacting a surface treatment agent containing a silane coupling agent with the glass cloth and then drying it can be listed. It should be noted that for the contact of the surface treatment agent with the glass cloth, methods such as impregnating 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 can be listed. There are no particular restrictions on the drying method for the surface treatment agent; examples include hot air drying and drying methods using electromagnetic waves.

[0197] The width of the warp and weft yarns can be adjusted by changing the fabric density during weaving, the tension applied to the warp yarns during weaving, the weft beating pressure during weaving, the opening force and tension applied to the warp yarns during the opening process, and the desizing force and tension applied to the warp yarns during the desizing process.

[0198] [Prepreg]

[0199] The prepreg of this embodiment comprises the above-described glass cloth and a matrix resin composition impregnated in the glass cloth.

[0200] The prepreg of this embodiment can be manufactured using conventional methods. For example, in this embodiment, the prepreg can be manufactured by impregnating a varnish made by diluting a matrix resin such as epoxy resin with an organic solvent into the glass cloth, then using a drying oven to evaporate the organic solvent and cure the thermosetting resin to stage B (semi-cured state).

[0201] In addition to the epoxy resins mentioned above, other examples of matrix resin compositions include thermosetting resins such as bismaleimide resins, cyanate ester resins, unsaturated polyester resins, polyimide resins, bismaleimide-triazine resins (BT resins), and functionalized polyphenylene ether resins; thermoplastic resins such as polyphenylene ether resins, polyetherimide resins, liquid crystal polymers (LCPs) of fully aromatic polyesters, polybutadiene, and fluoropolymers; and mixed resins thereof. From the viewpoint of improving dielectric properties, heat resistance, solvent resistance, and molding properties, resins modified from thermoplastic resins using thermosetting resins can be used as matrix resin compositions.

[0202] In addition, the matrix resin composition may contain: inorganic fillers such as silica and aluminum hydroxide; flame retardants such as bromine-based, phosphorus-based, and metal hydroxides; other silane coupling agents; heat stabilizers; antistatic agents; ultraviolet absorbers; pigments; colorants; lubricants, etc.

[0203] Printed wiring board

[0204] The printed wiring board of this embodiment includes the aforementioned prepreg. The printed wiring board with the prepreg of this embodiment has a high yield rate and provides stable supply.

[0205] [Example]

[0206] The present invention will be specifically described below through examples.

[0207] <Properties of Glass Cloth>

[0208] Specifically, regarding the physical properties of glass fibers and glass cloth, the thickness of the glass cloth and the weft density (fabric density) of the warp and weft yarns are determined according to JIS R3420. The warp width and weft width of the glass cloth are determined according to the aforementioned method. The elongation in the warp direction and the elongation in the weft direction of the glass cloth are determined according to the aforementioned method in JIS 3420.

[0209] [Average diameter of the glass filaments]

[0210] Determined according to Method A of JIS R3420.

[0211] First, the coating is heated in an electric furnace at 625℃ for 20 minutes to remove the sizing agent using glass fibers. Then, the glass fibers are cut to lengths of 25mm or less, placed on a slide, and unfurled into long filaments. The diameter of each filament is measured using a microscope, with the outline of the filament as its diameter. The diameter of 25 filaments is randomly measured, and the average value is taken as the average diameter of the filament.

[0212] [Elastic Modulus]

[0213] For the modulus of elasticity, a glass block is obtained by melting and cooling the glass fibers used in the warp and weft yarns. This glass block is then used as a test piece and determined using the pulse-echo re-evaluation method.

[0214] <Comparative Example 1>

[0215] Both the warp and weft yarns use low dielectric glass fibers (AGY Corporation, LCD510, elastic modulus 61GPa) with an average filament diameter of 5.1μm and 200 filaments. The glass cloth (grey fabric) is woven using an air-jet loom with a warp yarn beating density of 53 threads / 25mm and a weft yarn beating density of 53 threads / 25mm.

[0216] The obtained fabric was subjected to sizing washing using a vibrating washing machine and fiber opening treatment using high-pressure water spray. Following desizing at 400°C for 24 hours, the fabric was impregnated in a treatment solution using a silane coupling agent as a surface treatment agent, squeezed out, and dried at 120°C for 1 minute. Finally, fiber opening processing using high-pressure water spray was performed to obtain a glass cloth with a width of 1285 mm.

[0217] It should be noted that, for the glass fiber used in the warp of Comparative Example 1, the average number of twists was 0.89 to 1.05, and the standard deviation of the number of twists was 0.05 to 0.33.

[0218] <Example 1>

[0219] Glass fibers with a standard deviation of twist number of 0.135 or less (average twist number of 0.93 to 1.02) were selected for use to enhance the processing force achieved by the vibrating washing machine in the pulp washing process (the rotation speed of the daisy roller is 1.5 times that of Comparative Example 1, and the stamping ratio is 1.04 times that of Comparative Example 1), and reduce the linear tension and spray pressure in the fiber opening process after silane coupling agent treatment (linear tension: 0.6 times that of Comparative Example 1, spray pressure: 0.5 times that of Comparative Example 1). Otherwise, the glass cloth was manufactured in the same manner as Comparative Example 1 to obtain a glass cloth with a width of 1285 mm.

[0220] When glass cloth is transported through air, the tension acting on the warp threads varies in the width direction due to the weight of the glass cloth itself. If processing with a variable warp filament configuration is performed under these conditions, the processing state of the warp threads will differ in the width direction. In this embodiment, the processing force of the vibrating washing machine that processes the glass cloth by immersing it in water is increased, while the fiber-opening processing force that is performed while the glass cloth is transported through air is reduced, thereby controlling the processing with a variable warp filament configuration in a way that is uniform in the width direction.

[0221] <Example 2>

[0222] The processing force achieved by the vibrating washing machine in the pulp washing process was increased (the rotational speed of the daisy roller was 1.7 times that of Comparative Example 1, and the stamping ratio was 1.06 times that of Comparative Example 1), and the linear tension and spray pressure in the fiber opening process after silane coupling agent treatment were reduced (linear tension: 0.55 times that of Comparative Example 1, spray pressure: 0.4 times that of Comparative Example 1). Otherwise, the glass cloth was manufactured in the same manner as Comparative Example 1 to obtain a glass cloth with a width of 1285 mm.

[0223] <Example 3>

[0224] The processing force achieved by the vibrating washing machine in the pulp washing process was increased (the rotational speed of the daisy roller was 2.0 times that of Comparative Example 1, and the stamping ratio was 1.09 times that of Comparative Example 1), and the linear tension and spray pressure in the fiber opening process after silane coupling agent treatment were reduced (linear tension: 0.5 times that of Comparative Example 1, spray pressure: 0.3 times that of Comparative Example 1). Otherwise, the glass cloth was manufactured in the same manner as in Example 2, and a glass cloth with a width of 1285 mm was obtained.

[0225] <Example 4>

[0226] The processing force achieved by the vibrating washing machine in the pulp washing process was increased (the rotational speed of the daisy roller was 2.5 times that of Comparative Example 1, and the stamping ratio was 1.14 times that of Comparative Example 1), and the linear tension and spray pressure in the fiber opening process after silane coupling agent treatment were reduced (linear tension: 0.4 times that of Comparative Example 1, spray pressure: 0.2 times that of Comparative Example 1). Otherwise, the glass cloth was manufactured in the same manner as in Example 2, and a glass cloth with a width of 1285 mm was obtained.

[0227] <Comparative Example 2>

[0228] The processing force achieved by the vibrating washing machine in the pulp washing process was reduced (the rotation speed of the daisy roller was 0.5 times that of Comparative Example 1, and the stamping ratio was 0.96 times that of Comparative Example 1). Otherwise, the glass cloth was manufactured in the same manner as Comparative Example 1 to obtain a glass cloth with a width of 1285 mm.

[0229] <Comparative Example 3>

[0230] Glass fibers with a standard deviation of twist of 0.135 or less (average twist of 0.93 to 1.02) were selected for use. Otherwise, the glass cloth was manufactured in the same manner as in Comparative Example 1, and a glass cloth with a width of 1285 mm was obtained.

[0231] <Comparative Example 4>

[0232] The processing force achieved by the vibrating washing machine in the pulp washing process was enhanced (the rotation speed of the daisy roller was 2.5 times that of Comparative Example 1, and the stamping ratio was 1.14 times that of Comparative Example 1). Otherwise, the glass cloth was manufactured in the same manner as Comparative Example 1 to obtain a glass cloth with a width of 1285 mm.

[0233] <Comparative Example 5>

[0234] The linear tension and spray pressure in the fiber opening process after silane coupling agent treatment were reduced (linear tension: 0.4 times compared to Comparative Example 1, spray pressure: 0.2 times compared to Comparative Example 1), and the glass cloth was manufactured in the same manner as in Comparative Example 1 to obtain a glass cloth with a width of 1285 mm.

[0235] <Example 5>

[0236] Both the warp and weft yarns are made of low dielectric glass fiber (AGY Corporation, LCD520, elastic modulus 56 GPa) with an average filament diameter of 5.1 μm and 200 filaments. The warp yarns are made of glass fiber with a standard deviation of twist of 0.135 or less (average twist of 0.93 to 1.02). Otherwise, the same as in Example 4, a glass cloth with a width of 1285 mm is obtained.

[0237] <Comparative Example 6>

[0238] Both the warp and weft yarns use low dielectric glass fibers (manufactured by AGY, LCDE340, elastic modulus 61GPa) with an average filament diameter of 6.2μm and 200 filaments. The glass cloth (grey fabric) is woven using an air-jet loom with a warp yarn bedding density of 59 threads / 25mm and a weft yarn bedding density of 61.5 threads / 25mm.

[0239] The obtained fabric was subjected to sizing and washing, followed by fiber opening treatment using high-pressure water spray. After desizing by heat treatment at 400°C for 24 hours, the glass cloth was impregnated in a treatment solution using a silane coupling agent as a surface treatment agent, squeezed out, and dried at 120°C for 1 minute. Finally, fiber opening processing using high-pressure water spray was performed to obtain glass cloth with a width of 1285 mm.

[0240] It should be noted that, for the glass fiber used in the warp of Comparative Example 6, the average number of twists was 0.90 to 1.05, and the standard deviation of the number of twists was 0.05 to 0.29.

[0241] <Example 6>

[0242] Glass fibers with a standard deviation of twist number of 0.135 or less (average twist number of 0.92 to 1.02) were selected for use to enhance the processing force achieved by the vibrating washing machine in the pulp washing process (the rotation speed of the daisy roller is 2.0 times that of Comparative Example 6, and the stamping ratio is 1.04 times that of Comparative Example 1), and reduce the linear tension and spray pressure in the fiber opening process after silane coupling agent treatment (linear tension: 0.8 times that of Comparative Example 6, spray pressure: 0.6 times that of Comparative Example 6). Otherwise, the glass cloth was manufactured in the same manner as in Comparative Example 6 to obtain a glass cloth with a width of 1285 mm.

[0243] <Example 7>

[0244] The processing force achieved by the vibrating washing machine in the pulp washing process was increased (the rotational speed of the daisy roller was 2.5 times that of Comparative Example 6, and the stamping ratio was 1.08 times that of Comparative Example 6), and the linear tension and spray pressure in the fiber opening process after silane coupling agent treatment were reduced (linear tension: 0.6 times that of Comparative Example 6, spray pressure: 0.2 times that of Comparative Example 6). Otherwise, the glass cloth was manufactured in the same manner as in Example 6, and a glass cloth with a width of 1285 mm was obtained.

[0245] <Comparative Example 7>

[0246] The linear tension and spray pressure in the fiber opening process after silane coupling agent treatment were reduced (linear tension: 0.6 times compared to Comparative Example 6, spray pressure: 0.2 times compared to Comparative Example 6), and the glass cloth was manufactured in the same manner as in Comparative Example 6 to obtain a glass cloth with a width of 1285 mm.

[0247] <Comparative Example 8>

[0248] Both the warp and weft yarns use low dielectric glass fibers (manufactured by AGY, LCE255, elastic modulus 61GPa) with an average filament diameter of 7.1μm and 200 filaments. The glass cloth (grey fabric) is woven using an air-jet loom with a warp yarn bedding density of 60 threads / 25mm and a weft yarn bedding density of 57 threads / 25mm.

[0249] The obtained fabric was subjected to sizing and washing, followed by fiber opening treatment using high-pressure water spray. After desizing by heat treatment at 400°C for 24 hours, the glass cloth was impregnated in a treatment solution using a silane coupling agent as a surface treatment agent, squeezed out, and dried at 120°C for 1 minute. Finally, fiber opening processing using high-pressure water spray was performed to obtain glass cloth with a width of 1285 mm.

[0250] It should be noted that, for the glass fiber used in the warp of Comparative Example 8, the average number of twists was 0.90 to 1.07, and the standard deviation of the number of twists was 0.06 to 0.30.

[0251] <Example 8>

[0252] Glass fibers with a standard deviation of twist number of 0.135 or less (average twist number of 0.92 to 1.03) were selected for use to enhance the processing force achieved by the vibrating washing machine in the pulp washing process (the rotation speed of the daisy roller is 2.0 times that of Comparative Example 8, and the stamping ratio is 1.04 times that of Comparative Example 8), and reduce the linear tension and spray pressure in the fiber opening process after silane coupling agent treatment (linear tension: 0.7 times that of Comparative Example 8, spray pressure: 0.6 times that of Comparative Example 8). Otherwise, the glass cloth was manufactured in the same manner as in Comparative Example 8 to obtain a glass cloth with a width of 1285 mm.

[0253] <Example 9>

[0254] The processing force achieved by the vibrating washing machine in the pulp washing process was increased (the rotational speed of the daisy roller was 2.5 times that of Comparative Example 8, and the stamping ratio was 1.08 times that of Comparative Example 8), and the linear tension and spray pressure in the fiber opening process after silane coupling agent treatment were reduced (linear tension: 0.5 times that of Comparative Example 8, spray pressure: 0.2 times that of Comparative Example 8). Otherwise, the glass cloth was manufactured in the same manner as in Example 8, and a glass cloth with a width of 1285 mm was obtained.

[0255] <Comparative Example 9>

[0256] The linear tension and spray pressure in the fiber opening process after silane coupling agent treatment were reduced (linear tension: 0.5 times compared with Comparative Example 8, spray pressure: 0.2 times compared with Comparative Example 8), and the glass cloth was manufactured in the same manner as in Comparative Example 8 to obtain a glass cloth with a width of 1285 mm.

[0257] <Comparative Example 10>

[0258] The processing force achieved by the vibrating washing machine in the pulp washing process was reduced (the rotation speed of the daisy roller was 0.5 times that of Comparative Example 8, and the stamping ratio was 0.96 times that of Comparative Example 1), and the linear tension and spray pressure in the fiber opening process after silane coupling agent treatment were increased (linear tension: 1.5 times that of Comparative Example 8, spray pressure: 1.2 times that of Comparative Example 8). Otherwise, the glass cloth was manufactured in the same manner as in Comparative Example 8, and a glass cloth with a width of 1285 mm was obtained.

[0259] The glass fiber composition, glass cloth fiber width composition, glass cloth structure, and stress-deformation characteristics of the examples and comparative examples are shown in Tables 1-4. The results of elongation characteristic measurements of conventional low-dielectric glass cloths, the low-dielectric glass cloths of Comparative Examples 3, 6, and 8, and the low-dielectric glass cloths of Examples 4, 6, and 8 are as follows: Figures 1-10 As shown in the figure. In the figure, the dashed line represents the elongation of the warp yarn, and the solid line represents the elongation of the weft yarn.

[0260] [Table 1]

[0261]

[0262] [Table 2]

[0263]

[0264] [Table 3]

[0265]

[0266] [Table 4]

[0267]

[0268] For the glass cloths of Examples 1 to 7, in the stress-deformation curves, the elongation in both the warp and weft directions is small, the ratio of the elongation in the warp direction to the elongation in the weft direction is small, and the anisotropy is small.

[0269] For the glass cloths of Comparative Examples 1 to 10, in the stress-deformation curves, one of the elongation in the warp direction or the elongation in the weft direction is large, and the ratio of the elongation in the warp direction to the elongation in the weft direction is large, indicating large anisotropy.

[0270] Figures 1-7The following types are shown: 1017 (thickness 15μm, glass filament diameter 4.0μm, number of glass filaments 50, warp fabric density 94.5 ends / 25mm, weft fabric density 95.5 ends / 25mm), 1027 (thickness 21μm, glass filament diameter 4.0μm, number of glass filaments 100, warp fabric density 74.0 ends / 25mm, weft fabric density 74.0 ends / 25mm), 1037 (thickness 25μm, glass filament diameter 4.5μm, number of glass filaments 100, warp fabric density 69.0 ends / 25mm, weft fabric density 72.0 ends / 25mm), and 1067 (thickness 31μm, glass filament diameter 5.1μm, number of glass filaments 100, warp fabric density 94.5 ends / 25mm, weft fabric density 95.5 ends / 25mm). The elongation characteristics of low-dielectric glass cloths of the following types were measured: type 1078 (thickness 47μm, glass filament diameter 5.1μm, glass filament count 200, warp density 52.5 / 25mm, weft density 52.5 / 25mm), type 3313 (thickness 74μm, glass filament diameter 6.2μm, glass filament count 200, warp density 59.0 / 25mm, weft density 61.0 / 25mm), and type 2116 (thickness 89μm, glass filament diameter 7.1μm, glass filament count 200, warp density 60.0 / 25mm, weft density 57.0 / 25mm). It should be noted that for these glass cloths, the warp and weft threads are made of the same glass fibers, but for the following purposes: (1) using glass fibers of the same rigidity for both warp and weft threads ensures that the strengthening effects such as dimensional stability and coefficient of thermal expansion are the same in both warp and weft directions; (2) improving surface smoothness; (3) ensuring uniform distribution of insulating resin and glass when forming the substrate for printed wiring boards; and (4) ensuring the accuracy of holes achieved through drilling and laser processing. The larger the diameter of the glass fibers constituting the glass cloth and the greater the number of filaments, the more the above characteristics will be significantly impaired if the warp and weft threads are not made of the same glass fibers. Therefore, glass cloths used for high-speed communication typically use glass cloths with the same warp and weft threads.

[0271] Depend on Figures 1-7 It is known that conventional low-dielectric glass cloths have the characteristic of significantly elongating in the weft direction compared to the warp direction when the same tensile load is applied. This difference, which is the ratio of the elongation in the weft direction to the elongation in the warp direction (rounded to two decimal places) under a load of 50N, is large for types 1017, 1027, 1037, 1067, 1078, 3313, and 2116, respectively, at 1.1, 1.2, 1.2, 1.3, 2.0, 2.0, and 2.3.

[0272] This is because, in the past, although the same glass fibers were used for both warp and weft, the weft fibers exhibited a greater degree of undulation compared to the warp fibers. This difference in undulation arises from the following reasons: the warp fibers are held under tension during weaving, thus minimizing undulation; conversely, while the warp fibers are held under tension and less prone to undulation, the weft fibers exhibit significant undulation. Furthermore, when the warp fibers are widened through flattening and fiber opening processes, the warp fibers are held under tension, thus preserving the undulation structure. The weft fibers intersect along the warp fibers in a manner that traces large arcs, increasing the undulation and further amplifying the difference in elongation characteristics between the warp and weft fibers. Moreover, once the warp fibers are widened through flattening and fiber opening processes, repeated flattening and fiber opening processes stretch the warp fibers under tension, thus eliminating undulation along with the shrinkage in fiber width. The weft fibers then further develop large undulations along the warp fibers, further increasing the difference in elongation characteristics between the warp and weft fibers.

[0273] Furthermore, the undulating structure of the weft yarn exhibits a characteristic that the more numerous the glass filaments and the larger the cross-sectional area of ​​the glass filament bundle, the more significantly the structure increases. From Figures 1 to 7 As can be seen from the examples, the ratio of the elongation in the weft direction to the elongation in the warp direction (rounded to two decimal places) is 1.1 for 1017 with 50 filaments, 1.2 for 1027, 1037, and 1067 with 100 filaments, 1.2 for 1027, 1037, and 1.3 for 1067, 1037, and 1067 with 200 filaments, respectively. Conversely, the ratio is 2.0 for 1078, 3313, and 2116 with 200 filaments, 2.0 for 2.0 for 2.3 for 200 filaments, showing a sharp increase. This is because, for glass fibers with 200 filaments, the thickness of the warp in the z-direction also increases, and the weft itself is also thicker, thus requiring significant variation in the weft thickness.

[0274] In other words, existing glass cloths, especially those with a thickness of 40μm or more composed of glass filaments with 200 filaments, tend to elongate approximately twice their original length in the weft direction under the same tensile stress. Therefore, the effect of enhancing dimensional changes during printed wiring board processing tends to weaken in the weft direction, potentially leading to problems such as warping and twisting during processing, anisotropy in dimensional changes, and anisotropy in dimensional changes due to heating.

[0275] Additionally, if referring to Figure 4 It can be seen that the low dielectric glass cloth of type 1067 described in the embodiment of Japanese Patent Application Publication No. 2017-132651 (Patent Document 1) has a large anisotropy of SS characteristics even if the difference in the elongation in the width direction is less than 10%, and the ratio of the elongation in the weft direction when a load of 50N is applied to every 25mm width in the weft direction to the elongation in the warp direction when a load of 50N is applied to every 25mm width in the warp direction (transverse / longitudinal ratio) is 1.31.

[0276] Compared to conventional glass cloths described above, the glass cloth of the present invention is characterized by reduced anisotropy of the stress-deformation curve. The preferred ratio (transverse / longitudinal) of the elongation in the weft direction to the elongation in the warp direction is 1.0 or more and 1.9 or less. A more preferred range for the ratio (transverse / longitudinal) of the elongation in the weft direction to the elongation in the warp direction is 1.0 or more and 1.8 or less, and a further preferred range is 1.0 or more and 1.7 or less.

[0277] Figures 8-10 The results of elongation characteristic measurements for Examples 4 (type 1078, thickness 44 μm, glass filament diameter 5.1 μm, number of glass filaments 200, warp fabric density 53 filaments / 25 mm, weft fabric density 53 filaments / 25 mm), Example 6 (type 3313, thickness 67 μm, glass filament diameter 6.2 μm, number of glass filaments 200, warp fabric density 59.0 filaments / 25 mm, weft fabric density 61.5 filaments / 25 mm), and Example 8 (type 2116, thickness 83 μm, glass filament diameter 7.1 μm, number of glass filaments 200, warp fabric density 60.0 filaments / 25 mm, weft fabric density 57.0 filaments / 25 mm) are shown. The elongation ratio (transverse / longitudinal) of the weft direction relative to the elongation ratio of the warp direction (rounded to two decimal places) is 1.4 and 1.6, 1.4, respectively. Compared with conventional glass cloth, the anisotropy of the stress-deformation curve is significantly improved. In addition, the undulating structure of the warp and weft is well balanced, and the glass fibers are tightly woven in the Z-axis direction. Therefore, it is also characterized by being able to be as thin as a few micrometers compared to conventional glass cloth using the same fibers.

Claims

1. A type of glass cloth, which is woven from glass fibers with a number of 120 or more and less than 500 filaments as warp and weft yarns, and has a thickness of 40 μm or more and 100 μm or less. The difference between the number of filaments constituting the warp yarn and the number of filaments constituting the weft yarn is 3 or less. The lower limit of the width of the warp yarn is above the value obtained using the following formula (1). 40×α+102···Equation (1) In the formula, α: the average diameter of the warp filaments, in μm. Furthermore, the warp-to-weft width ratio coefficient, calculated by dividing the ratio of the warp width to the weft width by the average diameter of the filaments, is greater than 0.125 and less than 0.

142. The ratio of the warp width to the weft width is the warp width / weft width.

2. The glass cloth according to claim 1, wherein, The thickness of the glass cloth is above 42μm and below 96μm.

3. The glass cloth according to claim 1, wherein, The glass cloth is a type of glass cloth woven from glass fibers with a number of filaments of 180 to 250 as both warp and weft.

4. The glass cloth according to claim 1, wherein, The difference between the number of filaments constituting the warp and the number of filaments constituting the weft is 0.

5. The glass cloth according to claim 1, wherein, The lower limit of the width of the warp yarn is above the value calculated using the following formula (1D). 40×α+105(μm)···Equation (1D) In the formula, α: the average diameter of the warp filaments, in μm.

6. The glass cloth according to claim 1, wherein, The ratio of the width of the warp yarn to the width of the weft yarn, calculated by dividing the average diameter of the filament by the warp-to-weft yarn width ratio coefficient, is greater than 0.133 and less than 0.

140. The ratio of the width of the warp yarn to the width of the weft yarn is the warp yarn width / weft yarn width.

7. The glass cloth according to claim 1, wherein, The width of the warp yarn is below the value obtained using the following formula (4). 30×α+250(μm)···Equation (4) In the formula, α: the average diameter of the warp filaments, in μm.

8. The glass cloth according to claim 1, wherein, The width of the warp yarn is below the value calculated using the following formula (4D). 30×α+220(μm)···Equation (4D) In the formula, α: the average diameter of the warp filaments, in μm.

9. The glass cloth according to claim 1, wherein, The thickness of the glass cloth divided by the width of the warp yarn, and the warp yarn width-thickness crimping shape index, are values ​​below those obtained using the following formula (2). 0.2305×ln(α)-0.227···Equation (2) In the formula, α: the average diameter of the warp filaments, in μm.

10. A type of glass cloth, which is woven from glass fibers with a number of 120 or more and less than 500 filaments as warp and weft fibers, and has a thickness of 40 μm or more and 100 μm or less. The difference between the number of filaments constituting the warp yarn and the number of filaments constituting the weft yarn is 3 or less. The lower limit of the width of the warp yarn is above the value obtained using the following formula (1). 40×α+102···Equation (1) In the formula, α: the average diameter of the warp filaments, in μm. Furthermore, the warp width-thickness crimping index, obtained by dividing the thickness of the glass cloth by the width of the warp yarn, is below the value calculated using the following formula (2). 0.2305×ln(α)-0.227···Equation (2) In the formula, α: the average diameter of the warp filaments, in μm.

11. The glass cloth according to any one of claims 1 to 10, wherein, The difference between the fabric density of the warp yarns and the fabric density of the weft yarns is less than 5 yarns / 25mm.

12. The glass cloth according to claim 11, wherein, The difference between the fabric density of the warp yarns and the fabric density of the weft yarns is less than 3.0 yarns / 25mm.

13. The glass cloth according to claim 11, wherein, The fabric density of the warp yarns is more than 40 yarns / 25mm and less than 70 yarns / 25mm.

14. The glass cloth according to claim 1 or 10, wherein, The sum of the width of the warp yarn and the width of the weft yarn is 720 μm or more.

15. The glass cloth according to claim 14, wherein, The sum of the width of the warp yarn and the width of the weft yarn is 750 μm or more.

16. The glass cloth according to claim 1 or 10, wherein, The weft yarn occupancy rate Y, which represents the proportion of the portion containing weft yarns in the length direction and is calculated using the following formula (3), is 88% or more and 104% or less. Y = F / (25000 / G) × 100 ··· Equation (3) In the formula, F is the weft width, G is the fabric density of the weft, F is in μm, and G is in threads / 25mm.

17. The glass cloth according to claim 16, wherein, The weft yarn occupancy rate Y is above 92% and below 102%.

18. The glass cloth according to claim 1 or 10, wherein, The ratio of the elongation A in the weft direction when a load of 50N is applied to every 25mm width in the weft direction to the elongation B in the warp direction when a load of 50N is applied to every 25mm width in the warp direction, i.e., the A / B ratio, is 1.0 or more and 1.9 or less.

19. The glass cloth according to claim 1 or 10, wherein, The elongation A in the weft direction when a load of 50N is applied to every 25mm width in the weft direction, and the elongation B in the warp direction when a load of 50N is applied to every 25mm width in the warp direction, are both greater than 0.3% and less than 0.95%.

20. The glass cloth according to claim 19, wherein, The elongation A in the weft direction when a load of 50N is applied to every 25mm width in the weft direction, and the elongation B in the warp direction when a load of 50N is applied to every 25mm width in the warp direction, are both greater than 0.5% and less than 0.93%.

21. The glass cloth according to claim 1 or 10, wherein it is composed of glass fibers with an elastic modulus of 50 GPa or more and 70 GPa or less.

22. The glass cloth according to claim 1 or 10, wherein it is composed of glass fibers with an elastic modulus of 50 GPa or more and 64 GPa or less.

23. The glass cloth according to claim 1 or 10, wherein it is composed of glass fibers with an elastic modulus of 54 GPa or more and 60 GPa or less.

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