Glass cloth, prepregs, and printed circuit boards

Abstract

This disclosure aims to provide a glass cloth that can improve the skew of printed circuit boards and has excellent productivity and resin impregnation properties. [Solution] According to this disclosure, a glass cloth is provided which is composed of glass threads made of a plurality of glass filaments as warp and weft threads. The thickness of the glass cloth is in the range of 26 to 36 μm, and the warp width and weft width are in the range of 211 to 300 μm and 326 to 400 μm, respectively, or the thickness is in the range of 42 to 58 μm, and the warp width and weft width are in the range of 267 to 385 μm and 425 to 550 μm, respectively. Furthermore, the coefficient of variation of the dielectric constant of the glass cloth at 10 GHz, as measured using a split cylinder resonator, is 8.0% or less.

Description

[Technical Field]

[0001] This disclosure relates to glass cloth, prepregs, and printed circuit boards. [Background technology]

[0002] Currently, with the increasing performance of information terminals such as smartphones and the advancement of high-speed communication represented by 5G communication, there is a significant progress in reducing the dielectric constant and dielectric loss tangent of insulating materials used in printed circuit boards for high-speed communication in order to reduce transmission loss.

[0003] Currently, information terminals such as smartphones are becoming more high-performance, and high-speed communication, exemplified by 5G communication, is progressing. Against this backdrop, for example, there is a demand for further improvements in heat resistance and insulation reliability for printed circuit boards used in high-speed communication. Furthermore, as the miniaturization of wiring patterns on printed circuit boards progresses, there is a strong desire to improve the delay (skew) of propagated signals caused by differences in the distribution of matrix resin and glass cloth in printed circuit boards.

[0004] Various efforts have been made to improve skew, and Patent Document 1 discloses a prepreg that is effective in reducing skew. Furthermore, as an example of further improvement of skew, Patent Document 2 reports that the skew of printed circuit boards is improved by processing glass cloth while untwisting glass yarn. Patent Document 3 improves skew by dispersing hexagonal boron nitride in a matrix resin. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Public Gazette 2013 / 140812 [Patent Document 2] International Public Relations No. 2023 / 238763 [Patent Document 3] Japanese Patent Publication No. 2017-170748

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, even in Patent Documents 1 to 3, there is still room for further improvement in skew in the glass cloth. Also, for example, in Patent Document 2, since the glass yarn is untwisted, fluff is likely to occur in the glass cloth, which is likely to cause a decrease in the productivity of the prepreg. Furthermore, from the viewpoint of suppressing voids in the prepreg and the like, a glass cloth with high resin impregnation property is required. Therefore, an object of the present disclosure is to provide a glass cloth that can improve the skew of a printed wiring board and is excellent in productivity and resin impregnation property.

Means for Solving the Problems

[0007] Some aspects of the present disclosure are exemplified below. [1] A glass cloth composed of glass yarns made of a plurality of glass filaments as warp and weft, where the thickness of the glass cloth is in the range of 26 to 36 μm, the warp width and the weft width of the glass cloth are in the ranges of 211 to 300 μm and 326 to 400 μm, respectively, and the coefficient of variation of the dielectric constant at 10 GHz of the glass cloth measured using a split cylinder resonator is 8.0% or less. [2] A glass cloth composed of glass yarns made of a plurality of glass filaments as warp and weft, where the thickness of the glass cloth is in the range of 42 to 58 μm, the warp width and the weft width of the glass cloth are in the ranges of 267 to 385 μm and 425 to 550 μm, respectively, and the coefficient of variation of the dielectric constant at 10 GHz of the glass cloth measured using a split cylinder resonator is 8.0% or less. [3] A glass cloth composed of a plurality of glass filaments as warp and weft threads, where the thickness of the glass cloth is in the range of 13 to 19 μm, where the warp width and weft width of the glass cloth are in the ranges of 125 to 135 μm and 200 to 240 μm, respectively, and the coefficient of variation of the dielectric constant at 10 GHz, measured using a split cylinder resonator, of the glass cloth is 8.0% or less. [4] A glass cloth composed of a plurality of glass filaments as warp and weft threads, where the thickness of the glass cloth is in the range of 17 to 25 μm, where the warp width and weft width of the glass cloth are in the ranges of 178 to 198 μm and 310 to 342 μm, respectively, and the coefficient of variation of the dielectric constant at 10 GHz, measured using a split cylinder resonator, of the glass cloth is 8.0% or less. [5] A glass cloth composed of a plurality of glass filaments as warp and weft threads, where the thickness of the glass cloth is in the range of 20 to 30 μm, where the warp width and weft width of the glass cloth are in the ranges of 176 to 232 μm and 329 to 353 μm, respectively, and the coefficient of variation of the dielectric constant at 10 GHz, measured using a split cylinder resonator, of the glass cloth is 8.0% or less. [6] The glass cloth according to any one of Items 1 to 5, where the dielectric constant is in the range of 3.8 to 4.5. [7] The glass cloth described in any one of items 1 to 6, wherein the glass yarn contains, based on its total mass, SiO2 in the range of 45 to 55 mass%, B2O3 in the range of 17 to 27 mass%, Al2O3 in the range of 11 to 21 mass%, CaO and MgO in total in the range of 2.7 to 5.7 mass%, and Li2O, K2O and Na2O in total in the range of 0 to 0.15 mass%. [8] The glass cloth described in item 7, wherein the glass yarn contains, based on its total mass, 0.15 to 0.45 mass% of TiO2, 2.5 to 7.5 mass% of P2O5, and 0 to 0.02 mass% of SrO in terms of oxides. [9] The glass cloth described in any one of items 1 to 6, wherein the glass yarn contains, based on its total mass, SiO2 in the range of 48 to 58 mass%, B2O3 in the range of 18 to 28 mass%, Al2O3 in the range of 8 to 18 mass%, CaO and MgO in total in the range of 3.4 to 6.4 mass%, and Li2O, K2O and Na2O in total in the range of 0 to 0.15 mass%.

[10] The glass cloth described in item 9, wherein the glass yarn contains, based on its total mass, 0.9 to 2.9 mass% of TiO2, 0 to 0.03 mass% of P2O5, and 0 to 3 mass% of SrO in terms of oxides.

[11] The glass cloth described in any one of items 1 to 6, wherein the glass yarn contains, based on its total mass, SiO2 in the range of 48 to 58 mass%, B2O3 in the range of 17 to 27 mass%, Al2O3 in the range of 11 to 21 mass%, CaO and MgO in total in the range of 3.5 to 6.5 mass%, and Li2O, K2O and Na2O in total in the range of 0 to 0.1 mass%.

[12] The glass cloth according to item 11, wherein the glass yarn contains, based on its total mass, TiO2 in the range of 0 to 0.3 mass%, P2O5 in the range of 0 to 4.2 mass%, and SrO in the range of 0 to 1 mass% in terms of oxides.

[13] The glass cloth described in any one of items 1 to 6, wherein the glass yarn contains, based on its total mass, SiO2 in the range of 47 to 57 mass%, B2O3 in the range of 22 to 32 mass%, Al2O3 in the range of 8 to 18 mass%, CaO and MgO in total in the range of 1.4 to 4.4 mass%, and Li2O, K2O and Na2O in total in the range of 0.1 to 1.0 mass%.

[14] The glass cloth according to item 13, wherein the glass yarn contains, based on its total mass, 0 to 1 mass% of TiO2, 0 to 0.2 mass% of P2O5, and 0 to 0.3 mass% of SrO in terms of oxides.

[15] The glass cloth described in any one of items 1 to 6, wherein the glass yarn contains, based on its total mass, SiO2 in the range of 47 to 57 mass%, B2O3 in the range of 18 to 28 mass%, Al2O3 in the range of 9 to 19 mass%, CaO and MgO in total in the range of 3.4 to 6.4 mass%, and Li2O, K2O and Na2O in total in the range of 0 to 0.3 mass%.

[16] The glass cloth described in item 15, wherein the glass yarn contains, based on its total mass, 0.01 to 0.3 mass% of TiO2, 0 to 0.2 mass% of P2O5, and 0 to 0.3 mass% of SrO in terms of oxides.

[17] The glass cloth described in any one of items 1 to 6, wherein the glass yarn contains, based on its total mass, SiO2 in the range of 47 to 57 mass%, B2O3 in the range of 20 to 30 mass%, Al2O3 in the range of 8 to 18 mass%, CaO and MgO in total in the range of 3.0 to 7.0 mass%, and Li2O, K2O and Na2O in total in the range of 0 to 0.3 mass%.

[18] The glass cloth described in item 17, wherein the glass yarn contains, based on its total mass, 1.0 to 5.0 mass% of TiO2, 0 to 0.1 mass% of P2O5, and 0 to 0.2 mass% of SrO in terms of oxides.

[19] The glass cloth described in item 6, wherein the dielectric constant is in the range of 4.0 to 4.3.

[20] The glass cloth described in any one of items 1 to 6, wherein the dielectric loss tangent at 10 GHz, as measured using a split-cylinder resonator, is 0.0025 or less. [twenty one] The glass cloth described in any one of items 1 to 6, wherein the dielectric loss tangent of the glass cloth, as measured using a split-cylinder resonator, is 0.0023 or less at 10 GHz. [twenty two] The glass cloth described in any one of items 1 to 6, wherein the dielectric loss tangent at 10 GHz, as measured using a split-cylinder resonator, is 0.0020 or less. [twenty three] The glass cloth described in any one of items 1 to 6, wherein the dielectric loss tangent at 10 GHz, as measured using a split-cylinder resonator, is in the range of 0.0010 to 0.0018. [twenty four] The glass cloth described in any one of items 1 to 6, wherein the dielectric loss tangent at 10 GHz, as measured using a split-cylinder resonator, is in the range of 0.0018 to 0.0020. [twenty five] A glass cloth according to any one of items 1 to 6, wherein the coefficient of variation of the dielectric constant is 6.0% or less.

[26] A glass cloth according to any one of items 1 to 6, wherein the coefficient of variation of the dielectric constant is 4.0% or less.

[27] A glass cloth according to any one of items 1 to 6, wherein the coefficient of variation of the dielectric constant is 2.0% or less.

[28] The glass cloth described in item 1, wherein the warp width and weft width of the glass cloth are in the range of 213 to 290 μm and 335 to 390 μm, respectively.

[29] The glass cloth described in item 1, wherein the warp width and weft width of the glass cloth are in the range of 215 to 275 μm and 345 to 380 μm, respectively.

[30] The glass cloth described in item 1, wherein the warp width and weft width of the glass cloth are in the range of 218 to 260 μm and 350 to 375 μm, respectively.

[31] The glass cloth described in item 1, wherein the standard deviations of the warp width and weft width of the glass cloth are within the range of 16 μm or less and 34 μm or less, respectively.

[32] The glass cloth described in item 2, wherein the warp width and weft width of the glass cloth are in the range of 270 to 370 μm and 440 to 540 μm, respectively.

[33] The glass cloth described in item 2, wherein the warp width and weft width of the glass cloth are in the range of 275 to 360 μm and 450 to 530 μm, respectively.

[34] The glass cloth described in item 2, wherein the warp width and weft width of the glass cloth are in the range of 285 to 350 μm and 460 to 500 μm, respectively.

[35] The glass cloth described in item 2, wherein the standard deviations of the warp width and weft width of the glass cloth are 26 μm or less and 39 μm or less, respectively.

[36] The glass cloth described in item 3, wherein the warp width and weft width of the glass cloth are in the range of 126-134 μm and 204-236 μm, respectively.

[37] The glass cloth described in item 3, wherein the warp width and weft width of the glass cloth are in the range of 127-133 μm and 208-232 μm, respectively.

[38] The glass cloth described in item 3, wherein the standard deviations of the warp width and weft width of the glass cloth are within the range of 15 μm or less and 24 μm or less, respectively.

[39] The glass cloth described in item 4, wherein the warp width and weft width of the glass cloth are in the range of 180 to 196 μm and 313 to 339 μm, respectively.

[40] The glass cloth described in item 4, wherein the warp width and weft width of the glass cloth are in the range of 182 to 194 μm and 316 to 336 μm, respectively.

[41] The glass cloth described in item 4, wherein the standard deviations of the warp width and weft width of the glass cloth are in the range of 20 μm or less and 40 μm or less, respectively.

[42] The glass cloth described in item 5, wherein the warp width and weft width of the glass cloth are in the range of 183 to 225 μm and 332 to 350 μm, respectively.

[43] The glass cloth described in item 5, wherein the warp width and weft width of the glass cloth are in the range of 190 to 218 μm and 335 to 347 μm, respectively.

[44] The glass cloth described in item 5, wherein the standard deviations of the warp width and weft width of the glass cloth are in the range of 20 μm or less and 43 μm or less, respectively.

[45] The glass cloth described in any one of items 1 to 44, wherein the coefficient of variation of the TEX of the glass yarn is 4.0% or less.

[46] The glass cloth described in any one of items 1 to 44, wherein the coefficient of variation of the TEX of the glass yarn is 3.0% or less.

[47] A prepreg comprising a glass cloth as described in any one of items 1 to 46, and a matrix resin.

[48] Printed circuit boards, including the prepreg described in item 47.

[49] Integrated circuits, including printed circuit boards as described in item 48.

[50] Electronic equipment, including printed circuit boards as described in item 48. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide glass cloth that can improve the skew of printed circuit boards and has excellent productivity and resin impregnation properties. [Modes for carrying out the invention]

[0009] The following describes examples of embodiments of this disclosure, but this disclosure is not limited thereto, and various modifications are possible without departing from its essence. In this disclosure, numerical ranges indicated using "~" represent numerical ranges that include the numbers before and after "~" as the lower and upper limits, respectively. In addition, in this disclosure, in numerical ranges described in stages, the upper or lower limit indicated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in this disclosure, the upper or lower limit indicated in one numerical range may also be replaced with the values ​​shown in the examples. In this disclosure, the term "process" includes not only independent processes, but also processes that are not clearly distinguishable from other processes, as long as the function of the process is achieved.

[0010] Glass cloth The glass cloth described herein is a glass cloth composed of glass threads made of multiple glass filaments as warp and weft threads. Examples of the weaving structure of the glass cloth include plain weave, twill weave, satin weave, and twill weave. Among these, the plain weave structure is preferred.

[0011] [Dielectric loss tangent and dielectric constant of glass cloth] Preferably, the dielectric loss tangent (Df) of the glass cloth, measured using a split-cylinder resonator, is 0.0025 or less at 10 GHz. Having the dielectric loss tangent of the glass cloth within this range reduces transmission loss in printed circuit boards, facilitating high-speed signal communication. From the viewpoint of easily obtaining the effect of reducing transmission loss, the dielectric loss tangent of the glass cloth is more preferably 0.0023 or less, even more preferably 0.0021 or less, particularly preferably 0.0020 or less, and may also be 0.0019 or less, or 0.0018 or less. There is no particular lower limit for the dielectric loss tangent, but it is preferably 0.0010 or higher, and more preferably in the range of 0.0010 to 0.0018. Furthermore, from the viewpoint of easily achieving both high yield and fluff quality of glass yarn and a low dielectric loss tangent when made into glass cloth, the dielectric loss tangent of the glass cloth is preferably in the range of 0.0017 to 0.0020, and more preferably in the range of 0.0018 to 0.0020. The dielectric constant (Dk) of the glass cloth is preferably in the range of 3.8 to 4.5, and more preferably in the range of 4.0 to 4.3, from the viewpoint of minimizing the dielectric constant difference with the matrix resin and improving skew performance. The dielectric loss tangent and dielectric constant of the glass cloth are measured by the method described in the examples.

[0012] [Glass cloth, cloth type P] The glass cloth of this disclosure has a thickness in the range of 26 to 36 μm, and the warp and weft widths of the glass cloth are in the range of 211 to 300 μm and 326 to 400 μm, respectively (also referred to as "Cloth Type P" in this disclosure), and the coefficient of variation of the dielectric constant at 10 GHz, as measured using a split cylinder resonator of the glass cloth, is in the range of 8.0% or less.

[0013] The glass cloth (cloth type P) of this disclosure, having the above configuration, can provide a glass cloth with excellent skew characteristics, as well as excellent productivity and resin impregnation. The reason for this is not limited to theory, but is presumed to be as follows. That is, a printed circuit board has a copper foil pattern for sending and receiving electrical signals on the surface of a laminate composed of a matrix resin and a glass cloth. The surface of the glass cloth is discontinuous, with a mixture of voids filled with matrix resin and glass threads, and the dielectric constants of the glass cloth and the matrix resin are different, which mainly causes a difference in signal speed between the matrix resin portion and the glass thread portion (generally called "skew"). Therefore, in order to improve skew with glass cloth, it is effective to widen the width of the glass cloth threads to make the surface of the glass cloth more uniform. Widening the width of the glass cloth threads also leads to an improvement in resin impregnation. Printed circuit boards are made from prepregs obtained by impregnating glass cloth with a resin composition and then partially curing it. By using glass cloth with high resin impregnation properties, the occurrence of voids (generally called air pockets) where the resin is not impregnated is reduced in the prepreg and printed circuit board, improving insulation reliability. Furthermore, having excellent resin impregnation properties also leads to improved heat resistance of printed circuit boards and the like. Here, a common method for widening the fiber width of glass cloth is to open the fibers. However, widening the fiber width by opening the fibers of glass cloth causes the surface of the glass cloth to become fuzzy, leading to a decrease in productivity. In other words, there is a trade-off between improving skew and resin impregnation properties and productivity (fuzz quality). Therefore, after diligent research, the inventors have found that by designing the thickness of the glass cloth, as well as the warp and weft widths, to be within an appropriate range, the fiber width can be sufficiently opened without having to strongly open the fibers of the glass cloth.In other words, when the warp and weft widths of the glass cloth are in the ranges of 211-300 μm and 326-400 μm, respectively, a thickness of 26 μm or more of the glass cloth eliminates the need to excessively widen the fiber width of the glass cloth and eliminates the need to strengthen the fiber opening process of the glass cloth, thereby improving the fluff quality of the glass cloth and leading to increased productivity. On the other hand, when the thickness of the glass cloth is 36 μm or less, the fiber width is sufficiently opened, improving skew and resin impregnation. Furthermore, since printed circuit boards using low-dielectric glass cloth are used to form very fine patterns, there is a need to improve the skew characteristics of the glass cloth more than ever before. As a result of our investigation, the inventors have found that in addition to setting the thickness, warp width, and weft width of the glass cloth within the above ranges, it is possible to significantly improve the skew characteristics of printed circuit boards by setting the coefficient of variation of the dielectric constant of the glass cloth at 10 GHz, measured using a split cylinder resonator, to 8.0% or less. The reason for this is that, conventionally, skew characteristics were thought to be a phenomenon caused by the difference in dielectric constant between the glass cloth and the matrix resin. However, the inventors have found that during the heating and de-oiling process of the glass cloth, elements such as boron, which are easily volatile when heated, fluctuate within the glass cloth surface, causing significant variations in the dielectric constant within the glass cloth surface, which also affects the skew characteristics. Therefore, the inventors conceived the idea of ​​reducing the difference in skew performance not only between the glass cloth and the matrix resin, but also between glass cloths themselves, by suppressing the variation in dielectric constant within the glass cloth surface. As a result of diligent research, as described below, by performing a process that makes the glass composition more uniform within the glass cloth surface, the variation in dielectric constant within the glass cloth surface is reduced, leading to a significant improvement in the skew performance of the printed circuit board. As a result, it is possible to obtain glass cloth that achieves a high degree of balance between productivity, skew characteristics, and resin impregnation properties.

[0014] The thickness of the glass cloth (cloth type P) is in the range of 26 to 36 μm, preferably in the range of 27 to 35 μm, more preferably in the range of 28 to 34 μm, even more preferably in the range of 29 to 33 μm, and particularly preferably in the range of 30 to 32 μm. When the thickness of the glass cloth is within the above range, a glass cloth can be obtained that has a higher degree of balance between productivity, skew characteristics, and resin impregnation properties.

[0015] The warp and weft widths of the glass cloth (cloth type P) are in the range of 211-300 μm and 326-400 μm, respectively, preferably in the range of 213-290 μm and 335-390 μm, more preferably in the range of 215-275 μm and 345-380 μm, respectively, and particularly preferably in the range of 218-260 μm and 350-375 μm, respectively. Alternatively, the warp and weft widths of the glass cloth (cloth type P) may be in the range of 211-280 μm and 326-400 μm, 215-270 μm and 335-390 μm, respectively, 220-260 μm and 345-380 μm, or 225-250 μm and 350-375 μm, respectively. If the warp and weft widths of the glass cloth are within the above range, a glass cloth with a higher degree of balance between productivity and skew characteristics can be obtained.

[0016] The standard deviations of the warp and weft widths of the glass cloth (cloth type P) are preferably 16 μm or less and 34 μm or less, respectively. If the standard deviation of the yarn width is within the above range, it is easier to obtain an improvement in the skew characteristics of the glass cloth. From the viewpoint of obtaining an even easier improvement in skew characteristics, the standard deviations of the warp and weft widths of the glass cloth are more preferably 15 μm or less and 33 μm or less, even more preferably 14 μm or less and 32 μm or less, and particularly preferably 13 μm or less and 31 μm or less. The standard deviation of the yarn width can be reduced, for example, by performing a fiber-opening treatment that widens the yarn width of the glass cloth. It is preferable to perform a fiber-opening treatment using a high-pressure spray or the like after surface treatment with a silane coupling agent, and it is more preferable to combine this with ultrasonic treatment of the glass cloth in water after heat de-oiling treatment to eliminate adhesion between glass filaments. The lower limit of the standard deviations of the warp and weft widths is not limited, but may be, for example, 5 μm or more and 10 μm or more, respectively.

[0017] The glass cloth (cloth type P) has a dielectric constant variation coefficient of 8.0% or less at 10 GHz, as measured using a split-cylinder resonator. As a result of the inventors' investigations, as described below, it has been found that by controlling the amount of Na ions and Mg ions adhering to the surface of the glass cloth and adjusting the heating de-oiling conditions, it is possible to suppress compositional variations of the glass yarn and reduce the dielectric constant variation coefficient of the glass cloth to 8.0% or less. From the viewpoint of easily obtaining the effect of improving skew characteristics, the dielectric constant variation coefficient of the glass cloth is preferably in the range of 6.0% or less, more preferably in the range of 4.0% or less, and particularly preferably in the range of 2.0% or less. The lower limit of the dielectric constant variation coefficient is not limited, but may be greater than 0%, for example, 1.0% or more.

[0018] The weft and warp density of the glass cloth (cloth type P) is preferably 55 to 75 threads / 25 mm, more preferably 57 to 73 threads / 25 mm, even more preferably 59 to 71 threads / 25 mm, and particularly preferably 61 to 73 threads / 25 mm. If the weft density is within the above range, a glass cloth with a higher degree of balance between productivity, skew characteristics, and resin impregnation can be obtained. The weft and warp density may be the same or different.

[0019] [Glass cloth, cloth type Q] Another embodiment of the glass cloth of this disclosure is a glass cloth having a thickness in the range of 42 to 58 μm, with warp and weft thread widths in the range of 267 to 385 μm and 425 to 550 μm, respectively (also referred to in this disclosure as "Cloth Type Q"), and having a coefficient of variation of dielectric constant at 10 GHz of 8.0% or less, as measured using a split-cylinder resonator of the glass cloth.

[0020] The glass cloth (cloth type Q) of this disclosure, having the above configuration, can provide a glass cloth with excellent skew characteristics, as well as excellent productivity and resin impregnation. The reason for this is the same as for cloth type P described above, except that the thickness of the glass cloth and the appropriate range of warp and weft widths are different.

[0021] The thickness of the glass cloth (cloth type Q) is in the range of 42 to 58 μm, preferably in the range of 43 to 57 μm, more preferably in the range of 44 to 56 μm, even more preferably in the range of 45 to 55 μm, and particularly preferably in the range of 46 to 53 μm. When the thickness of the glass cloth is within the above range, a glass cloth can be obtained that has a higher degree of balance between productivity, skew characteristics, and resin impregnation properties.

[0022] The warp and weft widths of the glass cloth (cloth type Q) are in the range of 267-385 μm and 425-550 μm, respectively, preferably in the range of 270-370 μm and 440-540 μm, more preferably in the range of 275-360 μm and 450-530 μm, respectively, and particularly preferably in the range of 285-350 μm and 460-500 μm, respectively. Alternatively, the warp and weft widths of the glass cloth (cloth type Q) may be in the range of 267-350 μm and 425-550 μm, respectively, in the range of 280-340 μm and 440-540 μm, respectively, in the range of 285-330 μm and 450-530 μm, respectively, and in the range of 290-320 μm and 460-500 μm, respectively. If the warp and weft widths of the glass cloth are within the above range, a glass cloth can be obtained that achieves a higher level of balance between productivity, skew characteristics, and resin impregnation properties.

[0023] The standard deviations of the warp and weft thread widths of the glass cloth (cloth type Q) are preferably in the range of 26 μm or less and 39 μm or less, respectively. If the standard deviation of the thread width is within the above range, it is easier to obtain an improvement in the skew characteristics of the glass cloth. From the viewpoint of obtaining an even easier improvement in skew characteristics, the standard deviations of the warp and weft thread widths of the glass cloth are more preferably in the range of 25 μm or less and 38 μm or less, even more preferably in the range of 24 μm or less and 37 μm or less, and particularly preferably in the range of 23 μm or less and 36 μm or less. The adjustment of the standard deviation of the thread width is the same as for cloth type P. The lower limits of the standard deviations of the warp and weft thread widths are not limited, but for example, they may be 10 μm or more and 20 μm or more, respectively.

[0024] The glass cloth (cloth type Q) has a dielectric constant variation coefficient of 8.0% or less at 10 GHz, as measured using a split-cylinder resonator. As a result of the inventors' investigations, as described below, it has been found that by controlling the amount of Na ions and Mg ions adhering to the surface of the glass cloth and adjusting the conditions of heat de-oiling, it is possible to suppress compositional variations of the glass yarn and reduce the dielectric constant variation coefficient of the glass cloth to 8.0% or less. From the viewpoint of easily obtaining the effect of improving skew characteristics, the dielectric constant variation coefficient of the glass cloth is preferably in the range of 6.0% or less, more preferably in the range of 4.0% or less, and particularly preferably in the range of 2.0% or less. The lower limit of the dielectric constant variation coefficient is not limited, but may be greater than 0%, for example, 1.0% or more.

[0025] The weft and warp density of the glass cloth (cloth type Q) is preferably 43 to 63 threads / 25 mm, more preferably 45 to 61 threads / 25 mm, even more preferably 47 to 59 threads / 25 mm, and particularly preferably 49 to 57 threads / 25 mm. If the weft density is within the above range, a glass cloth with a higher degree of balance between productivity, skew characteristics, and resin impregnation can be obtained. The weft and warp density may be the same or different.

[0026] [Glass cloth, cloth type R] The glass cloth of this disclosure has a thickness in the range of 13 to 19 μm, and the warp and weft widths of the glass cloth are in the range of 125 to 135 μm and 200 to 240 μm, respectively (also referred to as "Cloth Type R" in this disclosure), and the coefficient of variation of the dielectric constant at 10 GHz, as measured using a split cylinder resonator of the glass cloth, is in the range of 8.0% or less.

[0027] The glass cloth (Cloth Type R) of this disclosure, having the above configuration, can provide a glass cloth with excellent skew characteristics, as well as excellent productivity and resin impregnation. The reason for this is not limited to theory, but is presumed to be as follows. That is, a printed circuit board has a copper foil pattern for transmitting and receiving electrical signals on the surface of a laminate composed of a matrix resin and a glass cloth. The surface of the glass cloth is discontinuous, with a mixture of voids filled with matrix resin and glass threads, and the dielectric constants of the glass cloth and the matrix resin are different, which mainly causes a difference in signal speed between the matrix resin portion and the glass thread portion (commonly called "skew"). Therefore, in order to improve skew with glass cloth, it is effective to widen the width of the glass cloth threads to make the surface of the glass cloth more uniform. Widening the width of the glass cloth threads also leads to an improvement in resin impregnation. Printed circuit boards are made from prepregs obtained by impregnating glass cloth with a resin composition and then partially curing it. By using glass cloth with high resin impregnation properties, the occurrence of voids (generally called air pockets) where the resin is not impregnated is reduced in the prepreg and printed circuit board, improving insulation reliability. Furthermore, having excellent resin impregnation properties also leads to improved heat resistance of printed circuit boards and the like. Here, a common method for widening the fiber width of glass cloth is to open the fibers. However, widening the fiber width by opening the fibers of glass cloth causes the surface of the glass cloth to become fuzzy, leading to a decrease in productivity. In other words, there is a trade-off between improving skew and resin impregnation properties and productivity (fuzz quality). Therefore, after diligent research, the inventors have found that by designing the thickness of the glass cloth, as well as the warp and weft widths, to be within an appropriate range, the fiber width can be sufficiently opened without having to strongly open the fibers of the glass cloth.In other words, when the warp and weft widths of the glass cloth are in the ranges of 125-135 μm and 200-240 μm, respectively, a thickness of 13 μm or more of glass cloth eliminates the need to excessively widen the fiber width of the glass cloth and eliminates the need to strongly open the fiber, thus improving the fluff quality of the glass cloth and leading to increased productivity. On the other hand, when the thickness of the glass cloth is 19 μm or less, the fiber width is sufficiently opened, improving skew and resin impregnation. Furthermore, since printed circuit boards using low-dielectric glass cloth are used to form very fine patterns, there is a need to improve the skew characteristics of the glass cloth more than ever before. As a result of our investigation, the inventors have found that in addition to setting the thickness, warp width, and weft width of the glass cloth within the above ranges, the coefficient of variation of the dielectric constant of the glass cloth at 10 GHz, measured using a split cylinder resonator, to 8.0% or less can significantly improve the skew characteristics of printed circuit boards. The reason for this is that, conventionally, skew characteristics were thought to be a phenomenon caused by the difference in dielectric constant between the glass cloth and the matrix resin. However, the inventors have found that during the heating and de-oiling process of the glass cloth, elements such as boron, which are easily volatile when heated, fluctuate within the glass cloth surface, causing significant variations in the dielectric constant within the glass cloth surface, which also affects the skew characteristics. Therefore, the inventors conceived the idea of ​​reducing the difference in skew performance not only between the glass cloth and the matrix resin, but also between glass cloths themselves, by suppressing the variation in dielectric constant within the glass cloth surface. As a result of diligent research, as described below, by performing a process that makes the glass composition more uniform within the glass cloth surface, the variation in dielectric constant within the glass cloth surface is reduced, leading to a significant improvement in the skew performance of the printed circuit board. As a result, it is possible to obtain glass cloth that achieves a high degree of balance between productivity, skew characteristics, and resin impregnation properties.

[0028] The thickness of the glass cloth (cloth type R) is in the range of 13 to 19 μm, preferably in the range of 14 to 18 μm, and particularly preferably in the range of 15 to 17 μm. When the thickness of the glass cloth is within the above range, a glass cloth can be obtained that has a higher degree of balance between productivity, skew characteristics, and resin impregnation properties.

[0029] The warp and weft widths of the glass cloth (Cloth Type R) are in the range of 125-135 μm and 200-240 μm, respectively, preferably in the range of 126-134 μm and 204-236 μm, more preferably in the range of 127-133 μm and 208-232 μm, respectively, and particularly preferably in the range of 128-132 μm and 209-230 μm, respectively. If the warp and weft widths of the glass cloth are within the above ranges, a glass cloth with a higher degree of balance between productivity and skew characteristics can be obtained.

[0030] The standard deviations of the warp and weft widths of the glass cloth (cloth type R) are preferably 15 μm or less and 24 μm or less, respectively. If the standard deviation of the yarn width is within the above range, it is easier to obtain an improvement in the skew characteristics of the glass cloth. From the viewpoint of obtaining an even easier improvement in skew characteristics, the standard deviations of the warp and weft widths of the glass cloth are more preferably 14 μm or less and 23 μm or less, even more preferably 13 μm or less and 22 μm or less, and particularly preferably 12 μm or less and 21 μm or less. The standard deviation of the yarn width can be reduced, for example, by performing a fiber-opening treatment that widens the yarn width of the glass cloth. It is preferable to perform a fiber-opening treatment using a high-pressure spray or the like after surface treatment with a silane coupling agent, and it is more preferable to combine this with ultrasonic treatment of the glass cloth in water after heat de-oiling treatment to eliminate adhesion between glass filaments. The lower limit of the standard deviation of the warp and weft widths is not limited, but may be, for example, 2 μm or more and 5 μm or more, respectively.

[0031] The glass cloth (cloth type R) has a dielectric constant variation coefficient of 8.0% or less at 10 GHz, as measured using a split-cylinder resonator. As a result of the inventors' investigations, as described below, it has been found that by controlling the amount of Na ions and Mg ions adhering to the surface of the glass cloth and adjusting the heating de-oiling conditions, it is possible to suppress compositional variations of the glass yarn and reduce the dielectric constant variation coefficient of the glass cloth to 8.0% or less. From the viewpoint of easily obtaining the effect of improving skew characteristics, the dielectric constant variation coefficient of the glass cloth is preferably in the range of 6.0% or less, more preferably in the range of 4.0% or less, and particularly preferably in the range of 2.0% or less. The lower limit of the dielectric constant variation coefficient is not limited, but may be greater than 0%, for example, 1.0% or more.

[0032] The weft and warp density of the glass cloth (Cloth Type R) is preferably 88-98 threads / 25mm, more preferably 89-97 threads / 25mm, even more preferably 90-96 threads / 25mm, and particularly preferably 91-95 threads / 25mm. If the weft density is within the above range, a glass cloth with a higher degree of balance between productivity, skew characteristics, and resin impregnation can be obtained. The weft and warp density may be the same or different.

[0033] [Glass cloth, cloth type S] The glass cloth of this disclosure has a thickness in the range of 17 to 25 μm, and the warp width and weft width of the glass cloth are in the range of 178 to 198 μm and 310 to 342 μm, respectively (also referred to as "Cloth Type S" in this disclosure), and the coefficient of variation of the dielectric constant at 10 GHz, as measured using a split cylinder resonator of the glass cloth, is in the range of 8.0% or less.

[0034] The glass cloth (cloth type S) of this disclosure, having the above configuration, can provide a glass cloth with excellent skew characteristics, as well as excellent productivity and resin impregnation. The reason for this is not limited to theory, but is presumed to be as follows. That is, a printed circuit board has a copper foil pattern for transmitting and receiving electrical signals on the surface of a laminate composed of a matrix resin and a glass cloth. The surface of the glass cloth is discontinuous, with a mixture of voids filled with matrix resin and glass threads, and the dielectric constants of the glass cloth and the matrix resin are different, which mainly causes a difference in signal speed between the matrix resin portion and the glass thread portion (commonly called "skew"). Therefore, in order to improve skew with glass cloth, it is effective to widen the width of the glass cloth threads to make the surface of the glass cloth more uniform. Widening the width of the glass cloth threads also leads to an improvement in resin impregnation. Printed circuit boards are made from prepregs obtained by impregnating glass cloth with a resin composition and then partially curing it. By using glass cloth with high resin impregnation properties, the occurrence of voids (generally called air pockets) where the resin is not impregnated is reduced in the prepreg and printed circuit board, improving insulation reliability. Furthermore, having excellent resin impregnation properties also leads to improved heat resistance of printed circuit boards and the like. Here, a common method for widening the fiber width of glass cloth is to open the fibers. However, widening the fiber width by opening the fibers of glass cloth causes the surface of the glass cloth to become fuzzy, leading to a decrease in productivity. In other words, there is a trade-off between improving skew and resin impregnation properties and productivity (fuzz quality). Therefore, after diligent research, the inventors have found that by designing the thickness of the glass cloth, as well as the warp and weft widths, to be within an appropriate range, the fiber width can be sufficiently opened without having to strongly open the fibers of the glass cloth.In other words, when the warp and weft widths of the glass cloth are in the ranges of 178-198 μm and 310-342 μm, respectively, a thickness of 17 μm or more of glass cloth eliminates the need to excessively widen the fiber width of the glass cloth and eliminates the need to strongly open the fiber, thus improving the fluff quality of the glass cloth and leading to increased productivity. On the other hand, when the thickness of the glass cloth is 25 μm or less, the fiber width is sufficiently opened, improving skew and resin impregnation. Furthermore, since printed circuit boards using low-dielectric glass cloth are used to form very fine patterns, there is a need to improve the skew characteristics of the glass cloth more than ever before. As a result of our investigation, the inventors have found that in addition to setting the thickness, warp width, and weft width of the glass cloth within the above ranges, the coefficient of variation of the dielectric constant of the glass cloth at 10 GHz, measured using a split-cylinder resonator, to 8.0% or less can be used to significantly improve the skew characteristics of printed circuit boards. The reason for this is that, conventionally, skew characteristics were thought to be a phenomenon caused by the difference in dielectric constant between the glass cloth and the matrix resin. However, the inventors have found that during the heating and de-oiling process of the glass cloth, elements such as boron, which are easily volatile when heated, fluctuate within the glass cloth surface, causing significant variations in the dielectric constant within the glass cloth surface, which also affects the skew characteristics. Therefore, the inventors conceived the idea of ​​reducing the difference in skew performance not only between the glass cloth and the matrix resin, but also between glass cloths themselves, by suppressing the variation in dielectric constant within the glass cloth surface. As a result of diligent research, as described below, by performing a process that makes the glass composition more uniform within the glass cloth surface, the variation in dielectric constant within the glass cloth surface is reduced, leading to a significant improvement in the skew performance of the printed circuit board. As a result, it is possible to obtain glass cloth that achieves a high degree of balance between productivity, skew characteristics, and resin impregnation properties.

[0035] The thickness of the glass cloth (cloth type S) is in the range of 17 to 25 μm, preferably in the range of 18 to 24 μm, more preferably in the range of 19 to 23 μm, and particularly preferably in the range of 20 to 22 μm. When the thickness of the glass cloth is within the above range, a glass cloth can be obtained that has a higher degree of balance between productivity, skew characteristics, and resin impregnation properties.

[0036] The warp and weft widths of the glass cloth (cloth type S) are in the range of 178-198 μm and 310-342 μm, respectively, preferably in the range of 180-196 μm and 313-339 μm, more preferably in the range of 182-194 μm and 316-336 μm, respectively, and particularly preferably in the range of 184-192 μm and 320-333 μm, respectively. If the warp and weft widths of the glass cloth are within the above ranges, a glass cloth with a higher degree of balance between productivity and skew characteristics can be obtained.

[0037] The standard deviations of the warp and weft widths of the glass cloth (cloth type S) are preferably 20 μm or less and 40 μm or less, respectively. If the standard deviation of the yarn width is within the above range, it is easier to obtain an improvement in the skew characteristics of the glass cloth. From the viewpoint of obtaining an even easier improvement in skew characteristics, the standard deviations of the warp and weft widths of the glass cloth are more preferably 19 μm or less and 39 μm or less, even more preferably 18 μm or less and 38 μm or less, and particularly preferably 17 μm or less and 37 μm or less. The standard deviation of the yarn width can be reduced, for example, by performing a fiber-opening treatment that widens the yarn width of the glass cloth. It is preferable to perform a fiber-opening treatment using a high-pressure spray or the like after surface treatment with a silane coupling agent, and it is more preferable to combine this with ultrasonic treatment of the glass cloth in water after heat de-oiling treatment to eliminate adhesion between glass filaments. The lower limit of the standard deviations of the warp and weft widths is not limited, but may be, for example, 5 μm or more and 10 μm or more, respectively.

[0038] The glass cloth (cloth type S) has a dielectric constant variation coefficient of 8.0% or less at 10 GHz, as measured using a split-cylinder resonator. As a result of the inventors' investigations, as described below, it has been found that by controlling the amount of Na ions and Mg ions adhering to the surface of the glass cloth and adjusting the heating de-oiling conditions, it is possible to suppress compositional variations of the glass yarn and reduce the dielectric constant variation coefficient of the glass cloth to 8.0% or less. From the viewpoint of easily obtaining the effect of improving skew characteristics, the dielectric constant variation coefficient of the glass cloth is preferably in the range of 6.0% or less, more preferably in the range of 4.0% or less, and particularly preferably in the range of 2.0% or less. The lower limit of the dielectric constant variation coefficient is not limited, but may be greater than 0%, for example, 1.0% or more.

[0039] The weft and warp density of the glass cloth (cloth type S) is preferably 65-80 threads / 25mm, more preferably 67-79 threads / 25mm, even more preferably 68-78 threads / 25mm, and particularly preferably 69-77 threads / 25mm. If the weft density is within the above range, a glass cloth with a higher degree of balance between productivity, skew characteristics, and resin impregnation can be obtained. The weft and warp density may be the same or different.

[0040] [Glass cloth, cloth type T] The glass cloth of this disclosure has a thickness in the range of 20 to 25 μm, and the warp and weft widths of the glass cloth are in the range of 176 to 232 μm and 239 to 353 μm, respectively (also referred to as "Cloth Type T" in this disclosure), and the coefficient of variation of the dielectric constant at 10 GHz, as measured using a split cylinder resonator of the glass cloth, is in the range of 8.0% or less.

[0041] The glass cloth (cloth type T) of this disclosure, having the above configuration, can provide a glass cloth with excellent skew characteristics, as well as excellent productivity and resin impregnation. The reason for this is not limited to theory, but is presumed to be as follows: A printed circuit board has a copper foil pattern for transmitting and receiving electrical signals on the surface of a laminate composed of a matrix resin and a glass cloth. The surface of the glass cloth is discontinuous, with a mixture of voids filled with matrix resin and glass threads, and the dielectric constants of the glass cloth and the matrix resin are different, which mainly causes a difference in signal speed between the matrix resin portion and the glass thread portion (generally called "skew"). Therefore, in order to improve skew with glass cloth, it is effective to widen the width of the glass cloth threads to make the surface of the glass cloth more uniform. Widening the width of the glass cloth threads also leads to an improvement in resin impregnation. Printed circuit boards are made from prepregs obtained by impregnating glass cloth with a resin composition and then partially curing it. By using glass cloth with high resin impregnation properties, the occurrence of voids (generally called air pockets) where the resin is not impregnated is reduced in the prepreg and printed circuit board, improving insulation reliability. Furthermore, having excellent resin impregnation properties also leads to improved heat resistance of printed circuit boards and the like. Here, a common method for widening the fiber width of glass cloth is to open the fibers. However, widening the fiber width by opening the fibers of glass cloth causes the surface of the glass cloth to become fuzzy, leading to a decrease in productivity. In other words, there is a trade-off between improving skew and resin impregnation properties and productivity (fuzz quality). Therefore, after diligent research, the inventors have found that by designing the thickness of the glass cloth, as well as the warp and weft widths, to be within an appropriate range, the fiber width can be sufficiently opened without having to strongly open the fibers of the glass cloth.In other words, when the warp and weft widths of the glass cloth are in the ranges of 176-232 μm and 329-353 μm, respectively, a thickness of 20 μm or more of the glass cloth eliminates the need to excessively widen the fiber width of the glass cloth and eliminates the need to strongly open the fiber, thus improving the fluff quality of the glass cloth and leading to increased productivity. On the other hand, when the thickness of the glass cloth is 30 μm or less, the fiber width is sufficiently opened, improving skew and resin impregnation. Furthermore, since printed circuit boards using low-dielectric glass cloth are used to form very fine patterns, there is a need to improve the skew characteristics of the glass cloth more than ever before. As a result of our investigation, the inventors have found that in addition to setting the thickness, warp width, and weft width of the glass cloth within the above ranges, the coefficient of variation of the dielectric constant of the glass cloth at 10 GHz, measured using a split cylinder resonator, to 8.0% or less can significantly improve the skew characteristics of printed circuit boards. The reason for this is that, conventionally, skew characteristics were thought to be a phenomenon caused by the difference in dielectric constant between the glass cloth and the matrix resin. However, the inventors have found that during the heating and de-oiling process of the glass cloth, elements such as boron, which are easily volatile when heated, fluctuate within the glass cloth surface, causing significant variations in the dielectric constant within the glass cloth surface, which also affects the skew characteristics. Therefore, the inventors conceived the idea of ​​reducing the difference in skew performance not only between the glass cloth and the matrix resin, but also between glass cloths themselves, by suppressing the variation in dielectric constant within the glass cloth surface. As a result of diligent research, as described below, by performing a process that makes the glass composition more uniform within the glass cloth surface, the variation in dielectric constant within the glass cloth surface is reduced, leading to a significant improvement in the skew performance of the printed circuit board. As a result, it is possible to obtain glass cloth that achieves a high degree of balance between productivity, skew characteristics, and resin impregnation properties.

[0042] The thickness of the glass cloth (cloth type T) is in the range of 20 to 30 μm, preferably in the range of 21 to 29 μm, more preferably in the range of 22 to 28 μm, even more preferably in the range of 23 to 27 μm, and particularly preferably in the range of 24 to 26 μm. When the thickness of the glass cloth is within the above range, a glass cloth can be obtained that has a higher degree of balance between productivity, skew characteristics, and resin impregnation properties.

[0043] The warp and weft widths of the glass cloth (cloth type T) are in the range of 176-232 μm and 329-353 μm, respectively, preferably in the range of 183-225 μm and 332-350 μm, more preferably in the range of 190-218 μm and 335-347 μm, respectively, and particularly preferably in the range of 197-211 μm and 338-344 μm, respectively. If the warp and weft widths of the glass cloth are within the above ranges, a glass cloth with a higher degree of balance between productivity and skew characteristics can be obtained.

[0044] The standard deviations of the warp and weft widths of the glass cloth (cloth type T) are preferably 20 μm or less and 43 μm or less, respectively. If the standard deviation of the yarn width is within the above range, it is easier to obtain an improvement in the skew characteristics of the glass cloth. From the viewpoint of obtaining an even easier improvement in skew characteristics, the standard deviations of the warp and weft widths of the glass cloth are more preferably 19 μm or less and 42 μm or less, even more preferably 18 μm or less and 41 μm or less, and particularly preferably 17 μm or less and 40 μm or less. The standard deviation of the yarn width can be reduced, for example, by performing a fiber-opening treatment that widens the yarn width of the glass cloth. It is preferable to perform a fiber-opening treatment using a high-pressure spray or the like after surface treatment with a silane coupling agent, and it is more preferable to combine this with ultrasonic treatment of the glass cloth in water to eliminate adhesion between glass filaments after heat de-oiling treatment. The lower limit of the standard deviations of the warp and weft widths is not limited, but may be, for example, 5 μm or more and 10 μm or more, respectively.

[0045] The glass cloth (cloth type T) has a dielectric constant variation coefficient of 8.0% or less at 10 GHz, as measured using a split-cylinder resonator. As a result of the inventors' investigations, as described below, it has been found that by controlling the amount of Na ions and Mg ions adhering to the surface of the glass cloth and adjusting the heating de-oiling conditions, it is possible to suppress compositional variations of the glass yarn and reduce the dielectric constant variation coefficient of the glass cloth to 8.0% or less. From the viewpoint of easily obtaining the effect of improving skew characteristics, the dielectric constant variation coefficient of the glass cloth is preferably in the range of 6.0% or less, more preferably in the range of 4.0% or less, and particularly preferably in the range of 2.0% or less. The lower limit of the dielectric constant variation coefficient is not limited, but may be greater than 0%, for example, 1.0% or more.

[0046] The weft and warp density of the glass cloth (cloth type T) is preferably 60-80 threads / 25mm, more preferably 61-79 threads / 25mm, even more preferably 62-78 threads / 25mm, and particularly preferably 63-77 threads / 25mm. If the weft density is within the above range, a glass cloth with a higher degree of balance between productivity, skew characteristics, and resin impregnation can be obtained. The weft and warp density may be the same or different.

[0047] [Glass thread] The average filament diameter of the glass filaments constituting the glass thread is preferably 2.5 to 9.0 μm, more preferably 2.5 to 7.5 μm, even more preferably 3.5 to 7.0 μm, even more preferably 3.5 to 6.5 μm, and particularly preferably 3.5 to 6.0 μm. When the filament diameter is within the above range, the breaking strength of the filaments is increased, making it less likely for fuzz to form in the resulting glass cloth.

[0048] The coefficient of variation of the filament diameter is preferably 10.0% or less, more preferably 7.0% or less, even more preferably 5.0% or less, even more preferably 4.0% or less, and particularly preferably 0.03% or less. When the coefficient of variation of the glass fiber filament diameter is 10.0% or less, the variation in the TEX of the glass yarn is reduced, thereby suppressing variations in the dielectric constant of the glass cloth. As a result, the skew characteristics of the printed circuit board are improved. The coefficient of variation of the TEX of the glass yarn is preferably 4.0% or less, and more preferably 3.0% or less. If the coefficient of variation of the TEX of the glass yarn is 4.0% or less, variations in the dielectric constant of the glass cloth can be effectively suppressed, and as a result, the skew characteristics of the printed circuit board can be further improved. The coefficient of variation of the TEX of the glass yarn can be reduced by methods such as increasing the frequency of replacing the nozzle (bushing) when spinning the glass yarn. The lower limit of the coefficient of variation of TEX is not limited, but may be greater than 0%, for example, 1.0% or more.

[0049] [Glass Type A] As one of the glass yarn compositions (glass type A), it is preferable that the glass yarn contains, based on the total mass of the glass yarn, SiO2 in the range of 45 to 55 mass%, B2O3 in the range of 17 to 27 mass%, Al2O3 in the range of 11 to 21 mass%, CaO and MgO in total in the range of 2.7 to 5.7 mass%, and Li2O, K2O and Na2O in total in the range of 0 to 0.15 mass%. Having the glass composition within the above range makes it easier to provide glass cloth exhibiting low dielectric constant and dielectric loss tangent. From the viewpoint of easily obtaining glass cloth with even lower dielectric loss tangent, the range of SiO2 is more preferably 46 to 54 mass%, even more preferably 47 to 53 mass%, and particularly preferably 48 to 52 mass%. The range of B2O3 is more preferably 18 to 26 mass%, even more preferably 19 to 25 mass%, and particularly preferably 20 to 24 mass%. The amount of Al2O3 is more preferably in the range of 12 to 20 mass%, even more preferably in the range of 13 to 19 mass%, and particularly preferably in the range of 14 to 18 mass%. The total amount of CaO and MgO is more preferably in the range of 3.0 to 5.4 mass%, even more preferably in the range of 3.3 to 5.1 mass%, and particularly preferably in the range of 3.6 to 4.8 mass%. Alternatively, the total amount of CaO and MgO may be in the range of 1.5 to 4.5 mass%, 2.0 to 4.0 mass%, 2.5 to 3.5 mass%, or 2.7 to 3.3 mass%. The total amount of Li2O, K2O, and Na2O is more preferably in the range of 0.01 to 0.13 mass%, even more preferably in the range of 0.02 to 0.11 mass%, and particularly preferably in the range of 0.03 to 0.09 mass%. The above contents can be measured by ICP emission spectrometry as described in the examples.

[0050] From the viewpoint of increasing the productivity of glass yarn (glass type A), it is preferable that the glass yarn contains, based on its total mass, TiO2 in the range of 0.15 to 0.45 mass%, P2O5 in the range of 2.5 to 7.5 mass%, and SrO in the range of 0 to 0.02 mass% in terms of oxides. From the viewpoint of easily obtaining better productivity, the range of TiO2 is more preferably 0.17 to 0.43 mass%, even more preferably 0.20 to 40 mass%, and particularly preferably 0.25 to 0.35 mass%. The range of P2O5 is more preferably 3.0 to 7.0 mass%, even more preferably 3.5 to 6.5 mass%, and particularly preferably 4.0 to 6.0 mass%. The SrO content is more preferably in the range of 0.0005 to 0.015 mass%, even more preferably in the range of 0.001 to 0.010 mass%, and particularly preferably in the range of 0.0015 to 0.005 mass%. The above content can be measured by ICP emission spectrometry as described in the examples.

[0051] [Glass Type B] As one of the glass yarn compositions (glass type B), it is preferable that the glass yarn contains, based on the total mass of the glass yarn, 48 to 58 mass% of SiO2, 18 to 28 mass% of B2O3, 8 to 18 mass% of Al2O3, a total of 3.4 to 6.4 mass% of CaO and MgO, and a total of 0 to 0.15 mass% of Li2O, K2O, and Na2O. Having the glass composition within the above range makes it easier to provide glass cloth exhibiting low dielectric constant and dielectric loss tangent. From the viewpoint of easily obtaining glass cloth with even lower dielectric loss tangent, the range of SiO2 is more preferably 49 to 57 mass%, even more preferably 50 to 56 mass%, and particularly preferably 51 to 55 mass%. The range of B2O3 is more preferably 19 to 27 mass%, even more preferably 20 to 26 mass%, and particularly preferably 21 to 25 mass%. The amount of Al2O3 is more preferably in the range of 9 to 17 mass%, even more preferably in the range of 10 to 16 mass%, and particularly preferably in the range of 11 to 15 mass%. The total amount of CaO and MgO is more preferably in the range of 3.6 to 6.2 mass%, even more preferably in the range of 3.8 to 6.0 mass%, and particularly preferably in the range of 4.0 to 5.8 mass%. The total amount of Li2O, K2O, and Na2O is more preferably in the range of 0.01 to 0.13 mass%, even more preferably in the range of 0.03 to 0.11 mass%, and particularly preferably in the range of 0.05 to 0.09 mass%. The above contents can be measured by ICP emission spectrometry as described in the examples.

[0052] From the viewpoint of improving the desmear resistance (resistance to glass leaching in desmear solution) of glass yarn (glass type B), it is preferable that the glass yarn contains, based on its total mass, 0.9 to 2.9 mass% of TiO2, 0 to 0.03 mass% of P2O5, and 0 to 3 mass% of SrO in terms of oxides. From the viewpoint of obtaining better productivity, the range of TiO2 is more preferably 1.1 to 2.7 mass%, even more preferably 1.3 to 2.5 mass%, and particularly preferably 1.5 to 2.3 mass%. The range of P2O5 is more preferably 0.001 to 0.025 mass%, even more preferably 0.002 to 0.023 mass%, and particularly preferably 0.003 to 0.020 mass%. The SrO content is more preferably in the range of 0.2 to 2.5 mass%, even more preferably in the range of 0.2 to 2.0 mass%, and particularly preferably in the range of 0.4 to 1.5 mass%. The above content can be measured by ICP emission spectrometry as described in the examples.

[0053] [Glass Type C] As one of the glass yarn compositions (glass type C), it is preferable that the glass yarn contains, based on the total mass of the glass yarn, 48 to 58 mass% of SiO2, 17 to 27 mass% of B2O3, 11 to 21 mass% of Al2O3, a total of 3.5 to 6.5 mass% of CaO and MgO, and a total of 0 to 0.1 mass% of Li2O, K2O, and Na2O. Having the glass composition within the above range makes it easier to provide glass cloth exhibiting low dielectric constant and dielectric loss tangent. From the viewpoint of easily obtaining glass cloth with even lower dielectric loss tangent, the range of SiO2 is more preferably 49 to 57 mass%, even more preferably 50 to 56 mass%, and particularly preferably 51 to 55 mass%. The range of B2O3 is more preferably 18 to 26 mass%, even more preferably 19 to 25 mass%, and particularly preferably 20 to 24 mass%. The amount of Al2O3 is more preferably in the range of 12 to 20% by mass, even more preferably in the range of 13 to 19% by mass, and particularly preferably in the range of 14 to 18% by mass. The total amount of CaO and MgO is more preferably in the range of 3.7 to 6.3% by mass, even more preferably in the range of 4.0 to 6.0% by mass, and particularly preferably in the range of 4.5 to 5.5% by mass. The total amount of Li2O, K2O, and Na2O is more preferably in the range of 0.005 to 0.09% by mass, even more preferably in the range of 0.01 to 0.08% by mass, and particularly preferably in the range of 0.02 to 0.07% by mass. The above contents can be measured by ICP emission spectrometry as described in the examples.

[0054] From the viewpoint of increasing the productivity of glass yarn (glass type C), it is preferable that the glass yarn contains, based on its total mass, TiO2 in the range of 0 to 0.3 mass%, P2O5 in the range of 0 to 4.2 mass%, and SrO in the range of 0 to 1 mass% in terms of oxides. From the viewpoint of easily obtaining better productivity, the range of TiO2 is more preferably 0.005 to 0.25 mass%, even more preferably 0.01 to 0.20 mass%, and particularly preferably 0.013 to 0.15 mass%. The range of P2O5 is more preferably 1.0 to 4.0 mass%, even more preferably 1.3 to 3.7 mass%, and particularly preferably 1.6 to 3.4 mass%. The range of SrO is more preferably 0.05 to 0.9 mass%, even more preferably 0.1 to 0.8 mass%, and particularly preferably 0.14 to 0.7 mass%. The above-mentioned content can be measured by ICP emission spectrometry, as described in the examples.

[0055] [Glass Type D] As one of the glass yarn compositions (glass type D), it is preferable that the glass yarn contains, based on the total mass of the glass yarn, 47 to 57 mass% of SiO2, 22 to 32 mass% of B2O3, 8 to 18 mass% of Al2O3, a total of 1.4 to 4.4 mass% of CaO and MgO, and a total of 0.1 to 1.0 mass% of Li2O, K2O, and Na2O. Having the glass composition within the above range makes it easier to provide glass cloth exhibiting low dielectric constant and dielectric loss tangent. From the viewpoint of easily obtaining glass cloth with even lower dielectric loss tangent, the range of SiO2 is more preferably 48 to 56 mass%, even more preferably 49 to 55 mass%, and particularly preferably 50 to 54 mass%. The range of B2O3 is more preferably 23 to 31 mass%, even more preferably 24 to 30 mass%, and particularly preferably 25 to 29 mass%. The amount of Al2O3 is more preferably in the range of 9 to 17 mass%, even more preferably in the range of 10 to 16 mass%, and particularly preferably in the range of 11 to 15 mass%. The total amount of CaO and MgO is more preferably in the range of 1.6 to 4.2 mass%, even more preferably in the range of 1.8 to 4.0 mass%, and particularly preferably in the range of 2.0 to 3.8 mass%. The total amount of Li2O, K2O, and Na2O is more preferably in the range of 0.12 to 0.9 mass%, even more preferably in the range of 0.14 to 0.7 mass%, and particularly preferably in the range of 0.16 to 0.5 mass%. Alternatively, the total amount of Li2O, K2O, and Na2O may be in the range of 0.1 to 0.5 mass%, 0.12 to 0.48 mass%, 0.14 to 0.46 mass%, or 0.16 to 0.44 mass%. The above contents can be measured by ICP emission spectrometry as described in the examples.

[0056] From the viewpoint of preventing air bubbles from forming inside the glass yarn (glass type D), it is preferable that the glass yarn contains, based on its total mass, 0 to 1 mass% of TiO2, 0 to 0.2 mass% of P2O5, and 0 to 0.3 mass% of SrO in terms of oxide equivalent. From the viewpoint of making it easier to produce a more uniform glass yarn with fewer air bubbles, the range of TiO2 is more preferably 0.1 to 0.9 mass%, even more preferably 0.2 to 0.8 mass%, and particularly preferably 0.3 to 0.7 mass%. The range of P2O5 is more preferably 0.003 to 0.18 mass%, even more preferably 0.006 to 0.16 mass%, and particularly preferably 0.008 to 0.14 mass%. The SrO content is more preferably in the range of 0.001 to 0.25 mass%, even more preferably in the range of 0.01 to 0.20 mass%, and particularly preferably in the range of 0.02 to 0.15 mass%. The above content can be measured by ICP emission spectrometry as described in the examples.

[0057] [Glass type E] One of the glass yarn compositions according to this embodiment (glass type E) is preferably composed of SiO2 in the range of 47 to 57 mass%, B2O3 in the range of 18 to 28 mass%, Al2O3 in the range of 9 to 19 mass%, CaO and MgO in total in the range of 3.4 to 6.4 mass%, and Li2O, K2O and Na2O in total in the range of 0 to 0.3 mass%, based on the total mass of the glass yarn. Having the glass composition within the above range makes it easier to provide glass cloth exhibiting a low dielectric constant and dielectric loss tangent. From the viewpoint of easily obtaining glass cloth with an even lower dielectric loss tangent, the range of SiO2 is more preferably 48 to 56 mass%, even more preferably 49 to 55 mass%, and particularly preferably 50 to 54 mass%. The range of B2O3 is more preferably 19 to 27 mass%, even more preferably 20 to 26 mass%, and particularly preferably 21 to 25 mass%. Alternatively, B2O3 may be in the range of 19-29 mass%, 20-28 mass%, 21-27 mass%, or 22-26 mass%. Al2O3 is more preferably in the range of 10-18 mass%, even more preferably in the range of 11-17 mass%, and particularly preferably in the range of 12-16 mass%. Alternatively, Al2O3 may be in the range of 7-17 mass%, 8-16 mass%, 9-16 mass%, or 10-15 mass%. The total value of CaO and MgO is more preferably in the range of 3.6-6.2 mass%, even more preferably in the range of 3.8-6.0 mass%, and particularly preferably in the range of 4.1-5.7 mass%. The total value of Li2O, K2O, and Na2O is more preferably in the range of 0.01-0.25 mass%, even more preferably in the range of 0.02-0.20 mass%, and particularly preferably in the range of 0.03-0.15 mass%. The above-mentioned content can be measured by ICP emission spectrometry, as described in the examples.

[0058] From the viewpoint of preventing air bubbles from forming inside the glass yarn (glass type E) and improving the fluff quality of the glass yarn, it is preferable that the glass yarn contains TiO2 in the range of 0.01 to 0.3 mass%, P2O5 in the range of 0 to 0.2 mass%, and SrO in the range of 0 to 0.3 mass%, based on its total mass, in terms of oxide equivalent. From the viewpoint of not only making it easier to produce glass yarn with fewer air bubbles and more uniformity, but also making it easier to control the fluff quality, the range of TiO2 is more preferably 0.02 to 0.25 mass%, even more preferably 0.03 to 0.2 mass%, and particularly preferably 0.04 to 0.15 mass%. The range of P2O5 is more preferably 0.001 to 0.15 mass%, even more preferably 0.0015 to 0.12 mass%, and particularly preferably 0.002 to 0.08 mass%. The SrO content is more preferably in the range of 0.0001 to 0.25 mass%, even more preferably in the range of 0.0005 to 0.20 mass%, and particularly preferably in the range of 0.001 to 0.10 mass%. The above content can be measured by ICP emission spectrometry as described in the examples.

[0059] [Glass type F] One of the glass yarn compositions according to this embodiment (glass type F) is preferably composed of SiO2 in the range of 47 to 57 mass%, B2O3 in the range of 20 to 30 mass%, Al2O3 in the range of 8 to 18 mass%, CaO and MgO in total in the range of 3.0 to 7.0 mass%, and Li2O, K2O and Na2O in total in the range of 0 to 0.3 mass%, based on the total mass of the glass yarn. Having the glass composition within the above range makes it easier to provide glass cloth exhibiting low dielectric constant and dielectric loss tangent. From the viewpoint of easily obtaining glass cloth with an even lower dielectric loss tangent, the range of SiO2 is more preferably 48 to 56 mass%, even more preferably 49 to 55 mass%, and particularly preferably 50 to 54 mass%. The range of B2O3 is more preferably 21 to 29 mass%, even more preferably 22 to 28 mass%, and particularly preferably 23 to 27 mass%. The amount of Al2O3 is more preferably in the range of 9 to 17 mass%, even more preferably in the range of 10 to 16 mass%, and particularly preferably in the range of 11 to 15 mass%. The total amount of CaO and MgO is more preferably in the range of 3.2 to 6.8 mass%, even more preferably in the range of 3.4 to 6.6 mass%, and particularly preferably in the range of 3.6 to 6.4 mass%. The total amount of Li2O, K2O, and Na2O is more preferably in the range of 0.001 to 0.25 mass%, even more preferably in the range of 0.002 to 0.2 mass%, and particularly preferably in the range of 0.003 to 0.1 mass%. The above contents can be measured by ICP emission spectrometry as described in the examples.

[0060] From the viewpoint of good spinning stability due to the fact that air bubbles are less likely to enter the interior of the glass yarn (glass type E) and the glass can be melted uniformly, it is preferable that the glass yarn contains TiO2 in the range of 1.0 to 5.0 mass%, P2O5 in the range of 0 to 0.1 mass%, and SrO in the range of 0 to 0.2 mass%, based on its total mass, in terms of oxide. From the viewpoint of making it easier to produce glass yarn with fewer air bubbles and more uniformity, and to obtain glass yarn with excellent spinning stability, it is even more preferable that the TiO2 is in the range of 1.2 to 4.8 mass%, even more preferably in the range of 1.5 to 4.5 mass%, and particularly preferable in the range of 1.8 to 4.2 mass%. It is even more preferable that the P2O5 is in the range of 0 to 0.08 mass%, even more preferably in the range of 0 to 0.05 mass%, and particularly preferable in the range of 0 to 0.03 mass%. The SrO content is more preferably in the range of 0 to 0.01% by mass, even more preferably in the range of 0 to 0.005% by mass, and particularly preferably in the range of 0 to 0.001% by mass. The above content can be measured by ICP emission spectrometry as described in the examples.

[0061] [Na ion amount and Mg ion amount] The amounts of Na ions and Mg ions adhering to the surface of the glass cloth before heat degreasing are preferably in the range of 0 to 50 ppm and 0 to 30 ppm, respectively. The inventors' research revealed that when the glass cloth is heat degreasing at a high temperature of 300 to 400°C, the Na ions and Mg ions adhering to the glass surface are absorbed into the glass. This absorption of Na ions and Mg ions into the glass alters the original glass composition, resulting in changes to the dielectric constant and dielectric loss tangent of the glass. Therefore, controlling the amount of Na ions and Mg ions adhering to the surface of the glass cloth before heat degreasing within a certain range suppresses the occurrence of dielectric constant differences in the longitudinal and width directions of the glass cloth, making it easier to provide glass cloth with excellent skew characteristics. From the viewpoint of easily obtaining an improvement in skew characteristics, the amount of Na ions adhering to the surface of the glass cloth is preferably 40 ppm or less, more preferably 30 ppm or less, even more preferably 20 ppm or less, and particularly preferably 10 ppm or less. Furthermore, the amount of Mg ions adhering to the surface of the glass cloth is preferably 25 ppm or less, more preferably 20 ppm or less, even more preferably 15 ppm or less, and particularly preferably 10 ppm or less.

[0062] The amount of Na ions and Mg ions adhering to the surface of the glass cloth can be controlled by the glass cloth manufacturing method described later. Specifically, it can be controlled by washing the glass cloth, the ion content of the solvent used for washing, and the amount of sizing agent adhering to it. The amount of Na ions and Mg ions is measured by the method described in the examples.

[0063] [Sizing agent] The glass cloth before heat de-oiling may be surface-treated with a sizing agent. That is, the glass yarn may be surface-treated with a sizing agent. From the viewpoint of improving the convergence of the glass yarn, reducing fluff, and improving weaving properties, the sizing agent is preferably one that mainly consists of at least one selected from the group consisting of starch, PVA resin, polyurethane resin, epoxy resin, and acrylic resin. From the viewpoint of suppressing fluff of the glass cloth, the sizing agent is more preferably one that mainly consists of starch and / or PVA resin. Here, "main component" means the component that accounts for the largest mass % in the sizing agent, for example, a component that accounts for 50% or more by mass, 65% or more by mass, 80% or more by mass, or 95% or more by mass.

[0064] Method for manufacturing glass cloth The method for manufacturing glass cloth according to the present disclosure includes a step of weaving glass yarn, which consists of a plurality of glass filaments, as warp and weft threads to obtain glass cloth (weaving step). Preferably, the method includes an inspection step (TEX inspection step) before the weaving step in which all glass yarns used are inspected to see if the coefficient of variation of TEX is 4.0% or less. Preferably, the method further includes a step of opening the glass yarn before heating and de-oiling (pre-heating and de-oiling opening step), a step of washing the glass yarn with a solvent before heating and de-oiling (pre-heating and de-oiling washing step), and a step of heating and de-oiling the glass yarn afterwards (heating and de-oiling step), either before, during, or after the weaving step. This makes it possible to suppress variations in the dielectric loss tangent of the glass cloth not only due to the effect of TEX fluctuations in the glass cloth, but also due to fluctuations in the glass composition caused by the heating and de-oiling step. The method for manufacturing glass cloth according to the present disclosure may further include a step of washing and opening the washed and heat-de-oiled glass yarn while transporting it at a speed of 50 m / min or less in a liquid irradiated with ultrasonic waves (washing and opening step). This makes it easier to adjust the warp and weft widths of the glass cloth, as well as their standard deviations, to the preferred range described above, thereby providing a glass cloth that has excellent resin impregnation properties and can improve the heat resistance of printed circuit boards and the like.

[0065] The above glass processing method (pre-heating de-oiling fiber opening step, pre-heating de-oiling washing step, heat-based oiling step, and washing fiber opening step) can be applied to glass yarn before weaving, and can also be applied to woven glass cloth. In other words, the step of weaving glass yarn to obtain glass cloth may be provided before, in the middle of, or after the glass processing method. The method may further include a surface treatment step and a post-surface treatment fiber opening step after the heat-based oiling step. The following description will use as an example an embodiment in which the TEX inspection step, pre-heating de-oiling fiber opening step, pre-heating de-oiling washing step, heat-based oiling step, washing fiber opening step, surface treatment step, and post-surface treatment fiber opening step are included in this order. However, the glass cloth manufacturing method of this disclosure is not limited thereto.

[0066] [TEX inspection process for glass fiber] It is preferable to measure the TEX of all glass yarns used in the glass cloth of this disclosure and use only glass yarns with a coefficient of variation of 4.0% or less. The TEX of the glass yarn is measured by the method described in JIS 3420 7.1. Smaller variation in the TEX value of the glass yarn can further reduce variations in dielectric constant and dielectric loss tangent within the printed circuit board surface, thereby improving skew characteristics.

[0067] [Opening process before heat deoiling] It is preferable that the glass cloth of this disclosure undergoes a fiber-opening treatment before heat de-oiling. By performing a fiber-opening treatment on the glass cloth before heat de-oiling, it is possible to efficiently widen the yarn width while minimizing the occurrence of fuzz on the surface of the glass cloth. The fiber-opening method is not particularly limited, and examples include methods using spray water (high-pressure water fiber-opening), a vibro-washer, ultrasonic water, mangle, etc. From the viewpoint of performing a fiber-opening treatment and facilitating the washing of sizing agents adhering to the surface of the glass yarn, spray water (high-pressure water fiber-opening) and vibro-washer fiber-opening methods are preferred.

[0068] [Pre-heating and de-oiling cleaning process] The pre-heating de-oiling washing step includes a step of reducing the adhesive by washing the glass cloth with a solvent before heating de-oiling. This reduces adhesion caused by the adhesive on the glass filaments and the combustion residue of the adhesive during heating de-oiling, thereby improving the resin impregnation properties of the resulting glass cloth. From the viewpoint of washing efficiency, water is preferred as the solvent used for washing in this process, and the temperature is preferably 50°C or higher. By using water at 50°C or higher, it is possible to wash away excess adhesive while leaving the amount of adhesive necessary to protect the glass yarn until the heating de-oiling step. The water temperature is preferably 50°C or higher and less than 100°C. The lower limit of the water temperature is more preferably 55°C or higher, even more preferably 60°C or higher, and even more preferably 65°C or higher. The upper limit of the water temperature that can be combined with these lower limits is more preferably 95°C or lower, and even more preferably 90°C or lower. The washing method for raw glass cloth is not particularly limited, but for example, methods such as ultrasonic methods (e.g., methods using ultrasonic transducers), spraying (e.g., spraying with high-pressure spray), and steam spraying can be considered. From the standpoint of low processing cost, a preferred method is to immerse the raw glass cloth in a tank containing a washing solution, remove excess washing solution with a squeeze roller or the like, and then dry the raw glass cloth. In this case, the immersion time may be, for example, 2 seconds or more, 5 seconds or more, 10 seconds or more, or 15 seconds or more, and 120 seconds or less, 90 seconds or less, 60 seconds or less, or 45 seconds or less.

[0069] To facilitate controlling the coefficient of variation of the dielectric constant of the glass cloth to 8.0% or less, it is preferable to use water with low impurities, such as RO water, ion-exchanged water, or distilled water, for the washing process before heating and de-oiling. Specifically, the amount of Na ions in the washing water is preferably 20 ppm or less, more preferably 15 ppm or less, even more preferably 12 ppm or less, even more preferably 10 ppm or less, particularly preferably 7 ppm or less, and most preferably 1.5 ppm or less. If the amount of Na ions in the washing solution is 20 ppm or less, it is easier to reduce the amount of Na ions adhering to the glass cloth surface. Also, the amount of Mg ions is preferably 18 ppm or less, more preferably 12 ppm or less, even more preferably 8 ppm or less, even more preferably 6 ppm or less, particularly preferably 3 ppm or less, and most preferably 1 ppm or less. If the amount of Mg ions in the washing solution is 18 ppm or less, it is easier to reduce the amount of Mg ions adhering to the glass cloth surface. The inventors have shown that by reducing the amount of Na ions and Mg ions, it is possible to suppress the ion exchange reaction between the glass composition and the Na ions and Mg ions adhering to the surface of the glass fibers during the heat de-oiling treatment of the glass cloth, and as a result, the variation in the dielectric constant and dielectric loss tangent of the glass cloth is further reduced. Therefore, by washing the glass cloth with washing water containing the above-mentioned ranges of Na ions and Mg ions, the skew characteristics can be further improved.

[0070] [Heat deoiling process] The heat de-oiling process can utilize known heating methods, heating media, heating mechanisms, heating devices, and heating components, as long as the heat de-oiling temperature can be appropriately controlled. However, from a productivity standpoint, it is generally known to process multiple rolls of glass cloth together in a batch oven while the glass cloth is wound around a metal core tube (batch oven method). In this batch oven method, the surface of the glass cloth roll is easily heated, while the inner layer is not, resulting in different thermal histories between the surface and inner layers. In this regard, the inventors focused on suppressing variations in dielectric constant within the glass cloth surface by reducing the difference in thermal histories between the surface and inner layers, which had not been considered important in the past. As a result of diligent research, the inventors found that performing the heat de-oiling treatment multiple times is effective in making the difference in thermal histories of the glass cloth rolls as uniform as possible. Specifically, by rewinding the heat-de-oil treated glass cloth onto another metal core tube, the inner and outer layers of the glass cloth are reversed, and then the same heat-de-oil treatment is performed again. This makes it possible to perform a heat-de-oil treatment that equalizes the thermal history in both the width and length directions of the glass cloth.

[0071] To reduce variations in the dielectric constant of the glass cloth, the temperature for the heat de-oiling treatment is preferably 330 to 450°C, more preferably 340 to 440°C, even more preferably 350 to 430°C, and particularly preferably 360 to 420°C. The heating time is preferably 24 to 72 hours, more preferably 30 to 60 hours, and even more preferably 40 to 55 hours, in order to sufficiently remove the sizing agent adhering to the surface of the glass cloth. By reducing the number of times the glass cloth is turned over and the heat de-oiling treatment is performed, variations in the dielectric constant of the glass cloth can be suppressed while maintaining good fluff quality, so it is particularly preferable to turn the cloth over once and perform the heat de-oiling treatment twice to achieve both variations in dielectric constant and fluff quality.

[0072] [Washing and fiber opening process] The cleaning and fiber-opening step is preferably a step (ultrasonic cleaning) in which ultrasonic waves are irradiated onto the glass cloth in a liquid after the heating and oil-removal step and before the surface treatment step to mainly clean the combustion residue from the heating and oil-removal step and to open the fibers from the glass cloth. Preferably, the glass cloth is transported in a roll-to-roll manner in a liquid irradiated with ultrasonic waves by an ultrasonic oscillator and processed.

[0073] For ultrasonic cleaning, either water or an organic solvent can be used as the liquid, but from the standpoint of safety and environmental protection, it is preferable to use a liquid with water as the main component. Surfactants and pH adjusters can also be added to the cleaning liquid to improve cleaning efficiency.

[0074] There are no particular restrictions on the temperature of the liquid used in ultrasonic cleaning, but a temperature of 5°C or higher is preferable from the viewpoint of enhancing the cleaning effect. Furthermore, from the viewpoint of safety, a temperature of 60°C or lower is preferable for the liquid used in cleaning.

[0075] By running a glass cloth through a liquid irradiated with ultrasonic waves by an ultrasonic oscillator, the glass cloth can be cleaned by irradiating it with ultrasonic waves in the liquid. The line tension acting on the warp threads during the cleaning process is preferably 30N to 500N / 1m.

[0076] Ultrasonic cleaning can use ultrasound with a frequency of 20 kHz to 200 kHz. The ultrasonic frequency is preferably between 20 kHz and 50 kHz, and more preferably between 20 kHz and 30 kHz. Using ultrasound with a frequency of 20 kHz to 200 kHz is preferable because it allows for cleaning without major defects such as distortion of the glass cloth.

[0077] For ultrasonic cleaning, use 0.07 W / cm². 2 The above is 3.60 W / cm². 2 Ultrasound with the following output levels can be preferably used. A more preferable range for ultrasonic output is 0.14 W / cm². 2 More than 2.16W / cm 2 A more preferable range is 0.21 W / cm².2 More than 1.44W / cm 2 The following applies: Ultrasonic output is 0.07 W / cm². 2 The above steps ensured effective cleaning, with an ultrasonic output of 3.60 W / cm². 2 The following method is preferable because it allows for uniform cleaning without the occurrence of distortions or other issues.

[0078] The transport speed of the glass cloth in ultrasonic cleaning is preferably 50 m / min or less, more preferably 40 m / min or less, and particularly preferably 30 m / min or less. A transport speed of 50 m / min or less allows for effective cleaning and unfiberization of the glass cloth or its intermediates. It is also preferable because it suppresses fuzzing and misalignment caused by damage during transport.

[0079] The liquid used for ultrasonic cleaning usually contains dissolved air, mainly composed of nitrogen and oxygen. The amount of dissolved oxygen (by weight) is preferably between 1 ppm and 20 ppm, more preferably between 3 ppm and 17 ppm, and even more preferably between 4 ppm and 14 ppm. By controlling the amount of dissolved oxygen, it is possible to indirectly control the amount of dissolved gas, thereby controlling the degree to which the ultrasound is attenuated by the dissolved gas. A dissolved oxygen level of 1 ppm or higher is preferable because it allows for uniform fiber opening. A dissolved oxygen level of 20 ppm or less is preferable because it provides a good cleaning effect to the textile. A dissolved oxygen level in the range of 1 ppm to 20 ppm is preferable because it provides a uniform and good fiber opening effect.

[0080] [Surface treatment process] The surface treatment process involves applying a surface treatment agent, such as a silane coupling agent, to the glass cloth. For example, it may include at least one of the following steps: a coating step in which the surface treatment agent is applied to the surface of the glass, and a fixing step in which the surface treatment agent is fixed to the surface of the glass by heat drying. This makes it easier to suitably surface treat the glass.

[0081] Methods for applying a surface treatment agent include applying a treatment solution containing the surface treatment agent to the glass cloth, or immersing the glass cloth in the treatment solution. Methods for applying the treatment solution to the glass in the coating process include (a) immersing or passing the glass through a treatment solution stored in a bath (hereinafter referred to as the "immersion method"), and (b) applying the treatment solution to the glass using a roll coater, die coater, or gravure coater. When using the immersion method, it is preferable to select an immersion time of 0.5 seconds to 1 minute for the glass in the treatment solution. Furthermore, when using the immersion method, the glass can be passed through the treatment solution at a transport speed of 10 to 50 m / min while applying a predetermined tension (e.g., 100 to 250 N) to the glass. After applying the treatment solution to the glass, the solvent contained in the treatment solution can be heated and dried using methods such as hot air or electromagnetic waves.

[0082] The concentration of the surface treatment agent in the treatment solution is preferably 0.1 to 1.0% by mass, more preferably 0.1 to 0.8% by mass, and even more preferably 0.1 to 0.5% by mass. This makes it easier to surface treat the glass more effectively.

[0083] In the fixing process, the heating and drying temperature is preferably 80°C or higher, and more preferably 90°C or higher, so that the reaction between the surface treatment agent, such as a silane coupling agent, and the glass can proceed sufficiently. Furthermore, the heating and drying temperature is preferably 300°C or lower, and more preferably 180°C or lower, to prevent deterioration of the organic groups of the surface treatment agent, such as a silane coupling agent.

[0084] [Fiber opening process after surface treatment] As a process for opening the bonded glass filaments with a surface treatment agent, for example, a method can be employed in which the glass cloth is opened using spray water (high-pressure water opening), a vibro-washer, ultrasonic water, or a mangle. By reducing the tension on the glass cloth during this opening process, it tends to be possible to widen the yarn width. In order to suppress the generation of fluff in the glass cloth due to the opening process, it is preferable to take measures such as reducing friction with the contact material when weaving the glass yarn, and optimizing and increasing the amount of surface treatment agent applied.

[0085] The processes described above do not necessarily have to be performed separately; multiple processes can be combined into a single process. The composition of the glass cloth usually does not change before and after fiber opening. Furthermore, the manufacturing method of glass cloth can include any other processes besides those described above. For example, a slitting process can be added after the fiber opening process. Also, if possible, the order of the above processes can be changed.

[0086] Prepreg The prepreg of this disclosure contains the glass cloth of this disclosure and a matrix resin. This makes it possible to provide a prepreg that can improve the skew characteristics of printed circuit boards. Examples of matrix resins include thermosetting resins, thermoplastic resins, and combinations thereof.

[0087] Examples of thermosetting resins include: a) epoxy resins obtained by reacting a compound having an epoxy group with a compound having at least one of the following groups that react with the epoxy group: an amino group, a phenol group, an acid anhydride group, a hydrazide group, an isocyanate group, a cyanate group, and a hydroxyl group, without a catalyst, or by adding a catalyst with catalytic activity such as an imidazole compound, a tertiary amine compound, a urea compound, or a phosphorus compound, and then curing the reaction; b) radical polymerization-type curing resins obtained by curing a compound having at least one of an allyl group, a methacrylic group, and an acrylic group using a thermal decomposition catalyst or a photodecomposition catalyst as a reaction initiator; c) maleimidotriazine resins obtained by reacting a compound having a cyanate group with a compound having a maleimide group and curing the reaction; d) thermosetting polyimide resins obtained by reacting a maleimide compound with an amine compound and curing the reaction; and e) benzoxazine resins obtained by crosslinking and curing a compound having a benzoxazine ring by heat polymerization.

[0088] Examples of thermoplastic resins include polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, aromatic polyamide, polyetheretherketone, thermoplastic polyimide, insoluble polyimide, polyamideimide, LCP, polyester, cycloolefin polymer, and fluororesin.

[0089] The prepreg may further contain inorganic fillers. Examples of inorganic fillers include aluminum hydroxide, zirconium oxide, calcium carbonate, alumina, mica, aluminum carbonate, magnesium silicate, aluminum silicate, silica, talc, glass short fibers, aluminum borate, and silicon carbide. Inorganic fillers can be used in combination with thermosetting resins, thermoplastic resins, or both.

[0090] Printed circuit board The printed circuit board of this disclosure includes the prepreg of this disclosure. This provides a printed circuit board with excellent skew characteristics and other properties.

[0091] "Integrated Circuit and Electronic Device" The integrated circuit of the present disclosure includes the printed wiring board of the present disclosure. Also, the electronic device of the present disclosure includes the printed wiring board of the present disclosure. Thereby, an integrated circuit and an electronic device excellent in skew characteristics and the like are provided. Examples of the electronic device include information terminals such as smartphones, and the integrated circuit can be used for high-performance of the electronic device and high-speed communication represented by 5G communication.

Example

[0092] Next, examples and comparative examples of the present disclosure will be described. The present disclosure is not limited in any way by the following examples and comparative examples. Various evaluation methods will also be described below.

[0093] "Measurement Method" 〔Measurement method of the thickness of the glass cloth〕 In accordance with 7.10 of JIS R 3420, which stipulates general test methods for products such as glass long fibers and glass cloth using glass long fibers, a micrometer was used, the spindle was gently rotated and lightly contacted parallel to the measurement surface, and the scale after the ratchet made three clicking sounds was read.

[0094] 〔Measurement method of basis weight (glass cloth weight)〕 The basis weight of the cloth was obtained by cutting the cloth into a predetermined size and dividing its weight by the sample area. In this example, the glass cloth was cut into a size of 10 cm 2 and its weight was measured to obtain the basis weight of each glass cloth.

[0095] 〔Number of filaments and filament diameter (μm) of warp and weft〕 The number of filaments and the diameter of each filament in the warp and weft threads were determined by observing cross-sectional images of glass filaments. Specifically, cross-sectional images of glass filaments used as warp (or weft) threads were acquired, and the number of filaments and the diameter of the filaments in the warp (or weft) threads were measured in these cross-sectional images. Similarly, the acquisition of images of glass filaments and the measurement of the number of filaments were repeated, and the average of the five obtained measurements was treated as the number of filaments and the diameter of the filaments in the warp (or weft) threads.

[0096] [Converted thickness] Since glass cloth is a discontinuous planar material composed of air and glass, the equivalent thickness required for measurement using the resonance method was calculated by dividing the basis weight of each glass cloth by the bulk density of the glass. Equivalent thickness (μm) = Basis weight (g / m²) 2 ) ÷ bulk density of glass (g / cm³) 3 )

[0097] [Method for measuring the dielectric constant and dielectric loss tangent of glass cloth] In accordance with JIS R1641 / IEC 62562, which specifies a method for measuring the dielectric properties of fine ceramic materials used as dielectric substrates, primarily for microwave circuits, in the microwave band, the dielectric loss tangent of each glass cloth was measured. Specifically, glass cloth samples sampled to the size required for measurement in each resonator were conditioned by storing them in a constant temperature and humidity oven at 23°C and 50%RH for more than 8 hours, and then measured using a split cylinder resonator (EM Labs) and an impedance analyzer (Agilent Technologies). A total of 27 samples were taken from the glass cloth roll, with three samples taken in the width direction at lengths corresponding to 5%, 10%, 20%, 30%, 50%, 70%, 80%, 90%, and 95% from the surface in the longitudinal direction. From the measurement results of the 27 points obtained, the average value and coefficient of variation of the dielectric constant and dielectric loss tangent at 10 GHz were determined. The thickness of each sample was measured using the above-mentioned converted thickness. Coefficient of variation (%) = Standard deviation ÷ Mean × 100

[0098] [Warp width and weft width] The warp and weft widths of the glass cloth were determined using the following method. First, five glass cloth samples were cut from the cloth, each measuring 100 mm in the warp direction and 100 mm in the weft direction. Each cut sample was observed vertically using a macroscope at 100x magnification. For each sample, the width of 250 warp (or weft) threads was randomly measured, and the average value and standard deviation of the obtained 250 warp (or weft) thread widths were calculated. The calculated average value was treated as the warp (or weft) width.

[0099] [Measurement of Na ion, Mg ion, and SO4 ion content in the washing solution] The amounts of Na ions, Mg ions, and SO4 ions in the washing solution used to clean the glass cloth before heating and degreasing were measured using an ion chromatograph. <Pretreatment conditions> Samples were prepared by diluting them with distilled water as needed. <Cation Ion Chromatography Conditions> Equipment:Tosoh,IC-2010 Separation column: Tosoh, TSKgel-Super IC-Cation / P (4.6mm x 150mm) Separated solution: 2.5 mM HNO3 + 0.5 mM L-histidine Flow rate: 1.0mL / min Detection: Electrical conductivity Column temperature: 40℃ Injection volume: 30μL <Anion Ion Chromatography Conditions> Equipment:Tosoh,IC-2010 Separation column: Tosoh, TSKgel-Super IC-AZ (4.6mm x 150mm) Eluent: 6.3mM NaHCO3+1.7mM Na2CO3 Flow rate: 0.8mL / min Detection: Electrical conductivity Column temperature: 40℃ Injection volume: 30μL

[0100] [Measurement of the amount of Na ions, Mg ions, and SO4 ions adhering to the surface of the glass cloth before heating and degreasing.] The amounts of Na ions, Mg ions, and SO4 ions adhering to the surface of glass cloth (raw material cloth) before heating and de-oiling were measured using an ion chromatograph. <Pretreatment conditions> A piece of glass cloth cut to 18cm x 7cm was placed in a clean bottle (Wakayama CIC Laboratory Clean Pack Good Boy 100ml (SCC: ultrapure water washed), AS ONE part number: 7-2214-01). Next, it was immersed in 10ml of distilled water at room temperature and then irradiated with ultrasound for 30 minutes. After that, it was left to stand overnight at room temperature of 20℃~25℃ (for example, 23℃), and then centrifuged (12000rpm x 15 minutes). The supernatant liquid, from which foreign matter from the glass cloth had been removed, was used as the sample. The supernatant liquid obtained by performing the same procedure without glass cloth was used as a blank. The amount of Na ions, Mg ions, and SO4 ions (ppm) attached to the surface of the glass cloth was determined using the following formula. The amount of each ion (ppm) adhering to the surface of the glass cloth = (Amount of each ion in the supernatant containing the glass cloth (μg / ml) - Amount of each ion in the supernatant of the blank (μg / ml)) × 10 (ml) / Mass of the glass cloth (g) <Cation Ion Chromatography Conditions> Equipment:Tosoh,IC-2010 Separation column: Tosoh, TSKgel-Super IC-Cation / P (4.6mm x 150mm) Eluent: 2.5 mM HNO3 + 0.5 mM L-histidine Flow rate: 1.0mL / min Detection: Electrical conductivity Column temperature: 40℃ Injection volume: 30μL <Anion Ion Chromatography Conditions> Equipment:Tosoh,IC-2010 Separation column: Tosoh, TSKgel-Super IC-AZ (4.6mm x 150mm) Eluent: 6.3mM NaHCO3+1.7mM Na2CO3 Flow rate: 0.8 mL / min Detection: Electrical conductivity Column temperature: 40 °C Injection volume: 30 μL

[0101] [Content of each element contained in the glass fiber] The content of each element constituting the glass fiber was determined by the absolute calibration curve method using an ICP mass spectrometer.

[0102] <Content (% by mass) of SiO2, B2O3, and Al2O3>[[]] In order to reduce impurities (such as sizing agents, etc.) adhering to the glass cloth, glass fiber or its raw materials, the calibration solution was adjusted by the following method. That is, the glass fiber (sample) was weighed, hydrolyzed with sodium hydroxide, and then dissolved with dilute nitric acid to adjust the calibration solution.

[0103] For the obtained calibration solution, the content of silicon was measured using an ICP emission spectrometer (PS3520VDDII manufactured by Hitachi High-Technologies Corporation), and then the content of SiO2, B2O3, and Al2O3 contained in the sample was determined by converting it to the oxide value.

[0104] <Content (% by mass) of CaO, MgO, Li2O, K2O, Na2O, TiO2, P2O5, and SrO>[[]] The weighed glass cloth or glass fiber (sample) was decomposed by heating with sulfuric acid, nitric acid, and hydrofluoric acid, and then dissolved by warming with dilute nitric acid to adjust the calibration solution. For the obtained calibration solution, the content in the data of each element was determined by ICP emission spectrometry and converted to the oxide value (ICP emission spectrometer PS3250VDDII manufactured by Hitachi High-Technologies Corporation, atomic absorption spectrometer ZA3300 manufactured by Hitachi High-Technologies Corporation).

[0105] [TEX of glass fiber] The TEX of the glass fiber was measured in accordance with R 3420:2013. The average value and standard deviation were obtained from the values obtained by performing the TEX measurement operation 15 times.

[0106] Examples of glass cloth manufacturing [Manufacturing of Cross Type P] Glass cloth P was obtained by weaving glass yarn using an air jet loom to achieve a weave density of 65 warp threads / 25 mm and 67 weft threads / 25 mm. The glass cloth was woven to a width of 1300 mm. Glass yarn with an average filament diameter of 5.0 μm, 100 filaments, and 1.0 Z twist was used for both the warp and weft threads.

[0107] [Manufacturing of Cross Type Q] Glass cloth P was obtained by weaving glass yarn using an air jet loom to achieve a weave density of 53 warp threads / 25 mm and 53 weft threads / 25 mm. The glass cloth was woven to a width of 1300 mm. Glass yarn with an average filament diameter of 5.0 μm, 200 filaments, and a twist count of 1.0 Z was used for both the warp and weft threads.

[0108] [Manufacturing of Cross Type R] Glass cloth R was obtained by weaving glass yarn using an air jet loom to achieve a weave density of 94 warp threads / 25 mm and 94 weft threads / 25 mm. The glass cloth was woven to a width of 1300 mm. Glass yarn with an average filament diameter of 4.0 μm, 50 filaments, and a twist count of 1.0 Z was used for both the warp and weft threads.

[0109] [Manufacturing of Cross Type S] Glass cloth S was obtained by weaving glass yarn using an air jet loom to achieve a weave density of 74 warp threads / 25 mm and 74 weft threads / 25 mm. The glass cloth was woven to a width of 1300 mm. Glass yarn with an average filament diameter of 4.0 μm, 100 filaments, and a twist count of 1.0 Z was used for both the warp and weft threads.

[0110] [Manufacturing of Cross Type T] Glass cloth T was obtained by weaving glass yarn using an air jet loom to achieve a weave density of 69 warp threads / 25 mm and 72 weft threads / 25 mm. The glass cloth was woven to a width of 1300 mm. Glass yarn with an average filament diameter of 4.5 μm, 100 filaments, and a twist count of 1.0 Z was used for both the warp and weft threads.

[0111] [Ion content in the cleaning solution] The amounts of Na ions and Mg ions in washing solution 1 are as shown in the table below. Na ion content = 1.6 ppm Mg ion content = 0.0 ppm

[0112] Examples and Comparative Examples (Example 1) Glass cloth type P, created by selecting only glass yarn A1 with a coefficient of variation of 2.5% or less using TEX testing, is then subjected to high-pressure spraying (pressure = 3.0 kg / cm²). 2 The glass cloth was opened using a vibro-washer (multi-blade rotor rotation speed = 400 rpm) to remove sizing agents adhering to the surface of the glass yarn and to open the warp and weft threads (pre-heat de-oiling fiber opening process). Then, the glass cloth was transported at a line speed that allowed it to be immersed in a water tank containing washing water 1 for 20 seconds (transport speed = 20 m / min) to wash away ions adhering to the glass surface. After that, the moisture adhering to the glass cloth was removed by heating it at 110°C for 10 seconds in a dryer installed on the same line (pre-heat de-oiling washing process). 2000 m of the obtained glass cloth was wound onto a metal core tube and subjected to a heat de-oiling treatment at 370°C for 30 hours. After the first de-oiling treatment was completed, the glass cloth was wound onto the metal core tube again and subjected to another heat de-oiling treatment at 370°C for 30 hours to completely remove the sizing agents from the surface of the glass yarn (heat de-oiling process). Next, the glass cloth is moved through the water with a conveying tension of 200N and a line speed of 30m / min, while the frequency is 25GHz and the output is 0.72W / cm². 2The cloth was irradiated with ultrasound to wash away the residue (washing and fiber opening process). Next, a treatment solution was prepared by dispersing 0.3% by mass of 3-methacryloyloxypropyltrimethoxysilane; Z6030 (manufactured by Dow-Toray) in pure water adjusted to pH=3 with acetic acid. The cloth was immersed in the treatment solution, squeezed, and then heated and dried at 130°C for 60 seconds to fix the silane coupling agent (surface treatment process). The dried cloth was sprayed at a rate of 3.0 kg / cm². 2 The glass cloth was obtained by high-pressure fiber opening (fiber opening process after surface treatment) under pressure, and then drying at 130°C for 1 minute.

[0113] (Examples 2-13, Comparative Examples 1-9) Glass cloth was obtained in the same manner as in Example 1, except that the items listed in the table below were changed as shown in the table below.

[0114] (Example 14) In the fiber opening process before heat de-oiling, high-pressure spray (pressure = 4.0 kg / cm²) is used. 2 The following points were noted: the fiber opening process was performed using a vibro-washer (multi-blade rotor rotation speed = 500 rpm), the conveying tension was set to 100 N in the washing and fiber opening process, and 3.5 kg / cm² of spray was applied in the post-surface treatment fiber opening process. 2 Glass cloth was obtained in the same manner as in Example 1, except that high-pressure fiber opening was performed at a specific pressure.

[0115] (Example 15) Glass cloth type Q, created by selecting only glass yarn A2 with a coefficient of variation of 1.7% or less in TEX testing, is then subjected to high-pressure spraying (pressure = 4.0 kg / cm²). 2The glass cloth was opened using a vibro-washer (multi-blade rotor rotation speed = 500 rpm) to remove sizing agents adhering to the surface of the glass yarn and to open the warp and weft threads (pre-heat de-oiling fiber opening process). Then, the glass cloth was transported at a line speed that allowed it to be immersed in a water tank containing washing water 1 for 20 seconds (transport speed = 20 m / min) to wash away ions adhering to the glass surface. After that, the moisture adhering to the glass cloth was removed by heating it at 110°C for 10 seconds in a dryer installed on the same line (pre-heat de-oiling washing process). 2000 m of the obtained glass cloth was wound onto a metal core tube and subjected to a heat de-oiling treatment at 370°C for 30 hours. After the first de-oiling treatment was completed, the glass cloth was wound onto the metal core tube again and subjected to another heat de-oiling treatment at 370°C for 30 hours to completely remove the sizing agents from the surface of the glass yarn (heat de-oiling process). Next, the glass cloth is moved through the water with a conveying tension of 200N and a line speed of 30m / min, while the frequency is 25GHz and the output is 0.95W / cm². 2 The cloth was irradiated with ultrasound to wash away the residue (washing and fiber opening process). Next, a treatment solution was prepared by dispersing 0.3% by mass of 3-methacryloyloxypropyltrimethoxysilane; Z6030 (manufactured by Dow-Toray) in pure water adjusted to pH=3 with acetic acid. The cloth was immersed in the treatment solution, squeezed, and then heated and dried at 130°C for 60 seconds to fix the silane coupling agent (surface treatment process). The dried cloth was sprayed at 4.5 kg / cm². 2 The glass cloth was obtained by high-pressure fiber opening (fiber opening process after surface treatment) under pressure, and then drying at 130°C for 1 minute.

[0116] (Examples 16-27, Comparative Examples 10-18) Glass cloth was obtained in the same manner as in Example 15, except that the items listed in the table below were changed as shown in the table below.

[0117] (Example 28) In the fiber opening process before heat de-oiling, high-pressure spray (pressure = 4.3 kg / cm²) is used. 2The following points were noted: the fiber opening process was performed using a vibro-washer (multi-blade rotor rotation speed = 500 rpm), the conveying tension was set to 130 N in the washing and fiber opening process, and 3.8 kg / cm² of spray was applied in the post-surface treatment fiber opening process. 2 Glass cloth was obtained in the same manner as in Example 15, except that high-pressure fiber opening was performed at a specific pressure.

[0118] (Example 29) Glass cloth type R, created by selecting only glass yarn A13 with a coefficient of variation of 1.6% or less using TEX testing, is then subjected to high-pressure spraying (pressure = 2.0 kg / cm²). 2 The glass yarn surface was opened using a vibro-washer (multi-blade rotor rotation speed = 450 rpm) to remove sizing agents adhering to the surface of the glass yarn and to open the warp and weft threads (pre-heat de-oiling fiber opening process). Then, the glass yarn surface was washed by transporting it at a line speed that allowed it to be immersed in a tank of washing water 1 for 20 seconds (transport speed = 20 m / min) to remove ions adhering to the glass surface. After that, the moisture adhering to the glass cloth was removed by heating it at 110°C for 10 seconds in a dryer installed on the same line (pre-heat de-oiling washing process). 2000 m of the obtained glass cloth was wound onto a metal core tube and subjected to a heat de-oiling treatment at 370°C for 30 hours. After the first de-oiling treatment was completed, the glass cloth was wound onto the metal core tube again and subjected to another heat de-oiling treatment at 370°C for 30 hours to completely remove the sizing agents from the surface of the glass yarn (heat de-oiling process). Next, the glass cloth is moved through the water with a conveying tension of 200N and a line speed of 30m / min, while the frequency is 25GHz and the output is 0.55W / cm². 2 The cloth was irradiated with ultrasound to wash away the residue (washing and fiber opening process). Next, a treatment solution was prepared by dispersing 0.3% by mass of 3-methacryloyloxypropyltrimethoxysilane; Z6030 (manufactured by Dow-Toray) in pure water adjusted to pH=3 with acetic acid. The cloth was immersed in the treatment solution, squeezed, and then heated and dried at 130°C for 60 seconds to fix the silane coupling agent (surface treatment process). The dried cloth was sprayed at a rate of 3.0 kg / cm². 2The glass cloth was obtained by high-pressure fiber opening (fiber opening process after surface treatment) under pressure, and then drying at 130°C for 1 minute.

[0119] (Examples 30-41, Comparative Examples 19-27) Glass cloth was obtained in the same manner as in Example 29, except that the items listed in the table below were changed as shown in the table below.

[0120] (Example 42) In the fiber opening process before heat de-oiling, high-pressure spray (pressure = 3.5 kg / cm²) is used. 2 The following points were noted: the fiber opening process was performed using a vibro-washer (multi-blade rotor rotation speed = 500 rpm), the conveying tension was set to 100 N in the washing and fiber opening process, and 3.0 kg / cm² of spray was applied in the post-surface treatment fiber opening process. 2 Glass cloth was obtained in the same manner as in Example 29, except that high-pressure fiber opening was performed at a specific pressure.

[0121] (Example 43) Glass cloth type S, created by selecting only glass yarn A14 with a coefficient of variation of 1.5% or less using TEX testing, is then subjected to high-pressure spraying (pressure = 3.0 kg / cm²). 2The glass yarn surface was opened using a vibro-washer (multi-blade rotor rotation speed = 450 rpm) to remove sizing agents adhering to the surface of the glass yarn and to open the warp and weft threads (pre-heat de-oiling fiber opening process). Then, the glass yarn surface was washed by transporting it at a line speed that allowed it to be immersed in a tank of washing water 1 for 20 seconds (transport speed = 20 m / min) to remove ions adhering to the glass surface. After that, the moisture adhering to the glass cloth was removed by heating it at 110°C for 10 seconds in a dryer installed on the same line (pre-heat de-oiling washing process). 2000 m of the obtained glass cloth was wound onto a metal core tube and subjected to a heat de-oiling treatment at 370°C for 30 hours. After the first de-oiling treatment was completed, the glass cloth was wound onto the metal core tube again and subjected to another heat de-oiling treatment at 370°C for 30 hours to completely remove the sizing agents from the surface of the glass yarn (heat de-oiling process). Next, the glass cloth is moved through the water with a conveying tension of 200N and a line speed of 30m / min, while the frequency is 25GHz and the output is 0.60W / cm². 2 The cloth was irradiated with ultrasound to wash away the residue (washing and fiber opening process). Next, a treatment solution was prepared by dispersing 0.3% by mass of 3-methacryloyloxypropyltrimethoxysilane; Z6030 (manufactured by Dow-Toray) in pure water adjusted to pH=3 with acetic acid. The cloth was immersed in the treatment solution, squeezed, and then heated and dried at 130°C for 60 seconds to fix the silane coupling agent (surface treatment process). The dried cloth was sprayed at a rate of 3.0 kg / cm². 2 The glass cloth was obtained by high-pressure fiber opening (fiber opening process after surface treatment) under pressure, and then drying at 130°C for 1 minute.

[0122] (Examples 44-55, Comparative Examples 28-36) Glass cloth was obtained in the same manner as in Example 43, except that the items listed in the table below were changed as shown in the table below.

[0123] (Example 56) In the fiber opening process before heat de-oiling, high-pressure spray (pressure = 4.0 kg / cm²) is used. 2The following points were noted: the fiber opening process was performed using a vibro-washer (multi-blade rotor rotation speed = 500 rpm), the conveying tension was set to 100 N in the washing and fiber opening process, and 3.0 kg / cm² of spray was applied in the post-surface treatment fiber opening process. 2 Glass cloth was obtained in the same manner as in Example 43, except that high-pressure fiber opening was performed at a specific pressure.

[0124] (Example 57) Glass cloth type T, created by selecting only glass yarn A15 with a coefficient of variation of 1.3% or less in TEX testing, is then subjected to high-pressure spraying (pressure = 3.5 kg / cm²). 2 The glass yarn surface was opened using a vibro-washer (multi-blade rotor rotation speed = 480 rpm) to remove sizing agents adhering to the surface of the glass yarn and to open the warp and weft threads (pre-heat de-oiling fiber opening process). Then, the glass yarn surface was washed by transporting it at a line speed that allowed it to be immersed in a tank of washing water 1 for 20 seconds (transport speed = 20 m / min) to remove ions adhering to the glass surface. After that, the moisture adhering to the glass cloth was removed by heating it at 110°C for 10 seconds in a dryer installed on the same line (pre-heat de-oiling washing process). 2000 m of the obtained glass cloth was wound onto a metal core tube and subjected to a heat de-oiling treatment at 370°C for 30 hours. After the first de-oiling treatment was completed, the glass cloth was wound onto the metal core tube again and subjected to another heat de-oiling treatment at 370°C for 30 hours to completely remove the sizing agents from the surface of the glass yarn (heat de-oiling process). Next, the glass cloth is moved through the water with a conveying tension of 200N and a line speed of 30m / min, while the frequency is 25GHz and the output is 0.60W / cm². 2 The cloth was irradiated with ultrasound to wash away the residue (washing and fiber opening process). Next, a treatment solution was prepared by dispersing 0.3% by mass of 3-methacryloyloxypropyltrimethoxysilane; Z6030 (manufactured by Dow-Toray) in pure water adjusted to pH=3 with acetic acid. The cloth was immersed in the treatment solution, squeezed, and then heated and dried at 130°C for 60 seconds to fix the silane coupling agent (surface treatment process). The dried cloth was sprayed at a rate of 3.0 kg / cm². 2The glass cloth was obtained by high-pressure fiber opening (fiber opening process after surface treatment) under pressure, and then drying at 130°C for 1 minute.

[0125] (Examples 58-69, Comparative Examples 37-45) Glass cloth was obtained in the same manner as in Example 57, except that the items listed in the table below were changed as shown in the table below.

[0126] (Example 70) In the fiber opening process before heat de-oiling, high-pressure spray (pressure = 4.0 kg / cm²) is used. 2 The following points were noted: the fiber opening process was performed using a vibro-washer (multi-blade rotor rotation speed = 520 rpm), the conveying tension was set to 100 N in the washing and fiber opening process, and 3.0 kg / cm² of spray was applied in the post-surface treatment fiber opening process. 2 Glass cloth was obtained in the same manner as in Example 57, except that high-pressure fiber opening was performed at a specific pressure.

[0127] Evaluation Method [Method for evaluating fluffiness] The glass cloth is placed on a roll-to-roll inspection table, under a tension of 100N / 1000mm, and visually inspected for 1 meter while being illuminated with a halogen lamp. 2 The number of protrusions of 0.8 mm or more per unit area was determined. The surface and inner layers of the obtained roll-shaped long glass cloth were evaluated separately, and the average number of fibers was evaluated according to the following criteria. A: Number of feathers: 3 or less B: Number of feathers: 4 to 8 C: Number of feathers: 9 to 10 D: Number of feathers: 11 or more

[0128] [Method for evaluating resin impregnation properties] Glass cloth samples were taken to a size of 50mm x 50mm or larger. During sampling, the measurement area was not bent or touched. Castor oil (manufactured by Hayashi Pure Chemical Industries, Ltd., product number: 03001535, static viscosity at 24°C = 560 mPa·s × g / cm²) was measured at a liquid temperature of 24°C. 3The evaluation was performed by counting the number of voids when a sampled glass cloth was impregnated for a predetermined time. A high-precision camera (frame size: 5120 x 5120 pixels) was placed perpendicular to the glass cloth, and an LED light (Power Flash bar-type lighting manufactured by CCS Corporation) was used as a light source, illuminating the glass cloth from both sides, 15 cm away from the glass cloth. The number of voids larger than 160 μm present between the glass filaments in a 32 mm x 32 mm field of view was counted, and the average of three measurements was taken as the void count. Voids correspond to the unimpregnated portion of the matrix resin. Therefore, a low number of voids in the glass cloth means that the glass cloth has excellent impregnation properties into the matrix resin.

[0129] The resin impregnation properties were evaluated according to the following criteria. The time from immersion of the glass cloth test piece in the impregnation varnish to counting the number of unimpregnated areas was set to 5 minutes. A: Number of unimpregnated areas: 30 or less B: Number of unimpregnated areas: 31 or more and 45 or less C: Number of unimpregnated areas: 45 or more

[0130] [Method for manufacturing laminated boards] To the glass cloth obtained in the examples and comparative examples, 45 parts by mass of polyphenylene ether (SABIC, Noryl (trade name) SA9000), 10 parts by mass of triallyl isocyanurate, 45 parts by mass of toluene, and 0.6 parts by mass of 1,3-di(tert-butylisopropylbenzene) were added to a stainless steel container and stirred at room temperature for 1 hour to prepare a varnish. The glass cloth was impregnated with the prepared varnish, and after drying at 115°C for 1 minute, a prepreg was obtained. Ten of the obtained prepregs were stacked, and copper foil (Furukawa Electric Co., Ltd., model: F2-WS, 12 μm) was placed on top and bottom, and the mixture was dried at 200°C and 40 kg / cm². 2 The laminate was obtained by heating and pressurizing for 120 minutes.

[0131] [Method for evaluating the heat resistance of laminated boards] The copper foil of the laminate obtained as described above was removed by etching, and then it was heated and water-absorbed in a pressure cooker container at 133°C for 50 hours. Furthermore, the water-absorbed laminate was immersed in a 288°C solder bath for 20 seconds, and 0.03 cm was removed due to delamination at the interface between the glass cloth and the resin. 2 The presence or absence of the above-mentioned blistering was visually inspected. Six tests were conducted on each laminate. The evaluation of heat resistance is as follows. Note that the less blistering the laminate tends to be, the better its heat resistance. A: There were two or fewer bulges in the laminated boards. B: There were 3 to 4 layers of laminated board that were bulging. C: There were five or more bulges in the laminated boards.

[0132] [Method for evaluating skew characteristics] Fifteen microstrip lines with a circuit length of 10 cm were fabricated by etching only the copper foil on one side of the laminate obtained by the above method. The transmission speed of the fifteen copper foil lines (impedance = 100 Ω, wiring angle = 0 degrees) was measured from 10 GHz to 24 GHz, and the ratio of the maximum and minimum values ​​at that time was determined as the skew characteristic of the glass cloth. Skew characteristics = Maximum value ÷ Minimum value

[0133] [Table 1-1]

[0134] [Table 1-2]

[0135] [Table 1-3]

[0136] [Table 2-1]

[0137] Table 2-2

[0138] Table 2-3

[0139] Table 3

[0140] Table 4

[0141] Table 5

[0142] Table 6

[0143] Table 7

[0144] Table 8

[0145] Table 9

[0146] Table 10

[0147] Table 11

[0148] [Table 12]

[0149] [Table 13]

[0150] [Table 14]

[0151] [Table 15]

[0152] [Table 16]

[0153] [Table 17] [Industrial applicability]

[0154] The glass cloth of this disclosure can be used in printed circuit boards, particularly in high-speed communication printed circuit boards. Furthermore, the printed circuit board of this disclosure can be used in integrated circuits and for high-speed communication in electronic devices such as smartphones.

Claims

1. A glass cloth composed of glass threads made of multiple glass filaments as warp and weft threads, The thickness of the glass cloth is in the range of 26 to 36 μm, The warp and weft widths of the aforementioned glass cloth are in the ranges of 211 to 300 μm and 326 to 400 μm, respectively. The glass cloth having a coefficient of variation of dielectric constant at 10 GHz of 8.0% or less, as measured using a split-cylinder resonator.

2. A glass cloth composed of glass threads made of multiple glass filaments as warp and weft threads, The thickness of the glass cloth is in the range of 42 to 58 μm, The warp and weft widths of the aforementioned glass cloth are in the ranges of 267 to 385 μm and 425 to 550 μm, respectively. The glass cloth having a coefficient of variation of dielectric constant at 10 GHz of 8.0% or less, as measured using a split-cylinder resonator.

3. A glass cloth composed of glass threads made of multiple glass filaments as warp and weft threads, The thickness of the glass cloth is in the range of 13 to 19 μm, The warp and weft widths of the aforementioned glass cloth are in the range of 125 to 135 μm and 200 to 240 μm, respectively. The glass cloth having a coefficient of variation of dielectric constant at 10 GHz of 8.0% or less, as measured using a split-cylinder resonator.

4. A glass cloth composed of glass threads made of multiple glass filaments as warp and weft threads, The thickness of the glass cloth is in the range of 17 to 25 μm, The warp and weft widths of the aforementioned glass cloth are in the range of 178 to 198 μm and 310 to 342 μm, respectively. The glass cloth having a coefficient of variation of dielectric constant at 10 GHz of 8.0% or less, as measured using a split-cylinder resonator.

5. A glass cloth composed of glass threads made of multiple glass filaments as warp and weft threads, The thickness of the glass cloth is in the range of 20 to 30 μm, The warp and weft widths of the aforementioned glass cloth are in the range of 176 to 232 μm and 329 to 353 μm, respectively. The glass cloth having a coefficient of variation of dielectric constant at 10 GHz of 8.0% or less, as measured using a split-cylinder resonator.

6. The glass cloth according to any one of claims 1 to 5, wherein the dielectric constant is in the range of 3.8 to 4.

5.

7. The glass fiber contains 45 to 55% by mass of SiO2 based on its total mass. ２ And B in the range of 17-27 mass% ２ O ３ and Al in the range of 11 to 21 mass% ２ O ３ In addition, CaO and MgO in a total range of 2.7 to 5.7 mass%, and Li in a total range of 0 to 0.15 mass%. ２ O, K ２ O and Na ２ A glass cloth according to any one of claims 1 to 5, comprising O.

8. The glass fiber contains, based on its total mass, in terms of oxide conversion, TiO in the range of 0.15 to 0.45% by mass ２ and P in the range of 2.5 to 7.5% by mass ２ O ５ and SrO in the range of 0 to 0.02% by mass, the glass cloth according to claim 7

9. The glass fiber, based on its total mass, contains 48 to 58% by mass in terms of oxides. ２ and B in the range of 18-28% by mass ２ O ３ and Al in the range of 8 to 18 mass% ２ O ３ In addition, CaO and MgO in a total range of 3.4 to 6.4 mass%, and Li in a total range of 0 to 0.15 mass%. ２ O, K ２ O and Na ２ A glass cloth according to any one of claims 1 to 5, comprising O.

10. The aforementioned glass yarn contains, based on its total mass, 0.9 to 2.9% by mass in terms of oxides, TiO ２ and P in the range of 0 to 0.03 mass% ２ O ５ The glass cloth according to claim 9, further comprising 0 to 3 mass% of SrO.

11. The glass fiber, based on its total mass, contains 48 to 58% by mass in terms of oxides. ２ And B in the range of 17-27 mass% ２ O ３ and Al in the range of 11 to 21 mass% ２ O ３ In addition, CaO and MgO in a total range of 3.5 to 6.5 mass% and Li in a total range of 0 to 0.1 mass% ２ O, K ２ O and Na ２ A glass cloth according to any one of claims 1 to 5, comprising O.

12. The aforementioned glass fiber contains, based on its total mass, 0 to 0.3% by mass in terms of oxides, TiO ２ and P in the range of 0 to 4.2 mass% ２ O ５ The glass cloth according to claim 11, further comprising 0 to 1 mass% of SrO.

13. The aforementioned glass fiber contains 47 to 57% by mass of SiO2 based on its total mass. ２ And B in the range of 22-32 mass% ２ O ３ and Al in the range of 8 to 18 mass% ２ O ３ In addition, CaO and MgO in a total range of 1.4 to 4.4 mass%, and Li in a total range of 0.1 to 1.0 mass% ２ O, K ２ O and Na ２ A glass cloth according to any one of claims 1 to 5, comprising O.

14. The glass fiber, based on its total mass, contains 0 to 1% by mass in terms of oxides. ２ and P in the range of 0 to 0.2 mass% ２ O ５ The glass cloth according to claim 13, further comprising SrO in the range of 0 to 0.3 mass%.

15. The aforementioned glass fiber contains 47 to 57% by mass of SiO2 based on its total mass. ２ and B in the range of 18-28% by mass ２ O ３ and Al in the range of 9 to 19 mass% ２ O ３ In addition, CaO and MgO in a total range of 3.4 to 6.4 mass%, and Li in a total range of 0 to 0.3 mass%. ２ O, K ２ O and Na ２ A glass cloth according to any one of claims 1 to 5, comprising O.

16. The glass fiber, based on its total mass, contains 0.01 to 0.3% by mass in terms of oxides. ２ and P in the range of 0 to 0.2 mass% ２ O ５ The glass cloth according to claim 15, further comprising 0 to 0.3 mass% of SrO.

17. The aforementioned glass fiber contains 47 to 57% by mass of SiO2 based on its total mass. ２ And B in the range of 20-30 mass% ２ O ３ and Al in the range of 8 to 18 mass% ２ O ３ In addition, CaO and MgO in a total range of 3.0 to 7.0 mass%, and Li in a total range of 0 to 0.3 mass%. ２ O, K ２ O and Na ２ A glass cloth according to any one of claims 1 to 5, comprising O.

18. The glass fiber, based on its total mass, contains 1.0 to 5.0% by mass of TiO2 in terms of oxides. ２ and P in the range of 0 to 0.1 mass% ２ O ５ The glass cloth according to claim 17, further comprising SrO in the range of 0 to 0.2 mass%.

19. The glass cloth according to claim 6, wherein the dielectric constant is in the range of 4.0 to 4.

3.

20. The glass cloth according to any one of claims 1 to 5, wherein the dielectric loss tangent of the glass cloth at 10 GHz, as measured using a split-cylinder resonator, is 0.0025 or less.

21. The glass cloth according to any one of claims 1 to 5, wherein the dielectric loss tangent of the glass cloth at 10 GHz, as measured using a split-cylinder resonator, is 0.0023 or less.

22. The glass cloth according to any one of claims 1 to 5, wherein the dielectric loss tangent of the glass cloth at 10 GHz, as measured using a split-cylinder resonator, is 0.0020 or less.

23. The glass cloth according to any one of claims 1 to 5, wherein the dielectric loss tangent of the glass cloth at 10 GHz, as measured using a split-cylinder resonator, is in the range of 0.0010 to 0.0018.

24. The glass cloth according to any one of claims 1 to 5, wherein the dielectric loss tangent of the glass cloth at 10 GHz, as measured using a split-cylinder resonator, is in the range of 0.0018 to 0.0020.

25. The glass cloth according to any one of claims 1 to 5, wherein the coefficient of variation of the dielectric constant is 6.0% or less.

26. The glass cloth according to any one of claims 1 to 5, wherein the coefficient of variation of the dielectric constant is 4.0% or less.

27. The glass cloth according to any one of claims 1 to 5, wherein the coefficient of variation of the dielectric constant is 2.0% or less.

28. The glass cloth according to claim 1, wherein the warp width and weft width of the glass cloth are in the range of 213 to 290 μm and 335 to 390 μm, respectively.

29. The glass cloth according to claim 1, wherein the warp width and weft width of the glass cloth are in the range of 215 to 275 μm and 345 to 380 μm, respectively.

30. The glass cloth according to claim 1, wherein the warp width and weft width of the glass cloth are in the range of 218 to 260 μm and 350 to 375 μm, respectively.

31. The glass cloth according to claim 1, wherein the standard deviations of the warp width and weft width of the glass cloth are in the range of 16 μm or less and 34 μm or less, respectively.

32. The glass cloth according to claim 2, wherein the warp width and weft width of the glass cloth are in the range of 270 to 370 μm and 440 to 540 μm, respectively.

33. The glass cloth according to claim 2, wherein the warp width and weft width of the glass cloth are in the range of 275 to 360 μm and 450 to 530 μm, respectively.

34. The glass cloth according to claim 2, wherein the warp width and weft width of the glass cloth are in the range of 285 to 350 μm and 460 to 500 μm, respectively.

35. The glass cloth according to claim 2, wherein the standard deviations of the warp width and weft width of the glass cloth are 26 μm or less and 39 μm or less, respectively.

36. The glass cloth according to claim 3, wherein the warp width and weft width of the glass cloth are in the range of 126 to 134 μm and 204 to 236 μm, respectively.

37. The glass cloth according to claim 3, wherein the warp width and weft width of the glass cloth are in the range of 127 to 133 μm and 208 to 232 μm, respectively.

38. The glass cloth according to claim 3, wherein the standard deviations of the warp width and weft width of the glass cloth are in the range of 15 μm or less and 24 μm or less, respectively.

39. The glass cloth according to claim 4, wherein the warp width and weft width of the glass cloth are in the range of 180 to 196 μm and 313 to 339 μm, respectively.

40. The glass cloth according to claim 4, wherein the warp width and weft width of the glass cloth are in the range of 182 to 194 μm and 316 to 336 μm, respectively.

41. The glass cloth according to claim 4, wherein the standard deviations of the warp width and weft width of the glass cloth are in the range of 20 μm or less and 40 μm or less, respectively.

42. The glass cloth according to claim 5, wherein the warp width and weft width of the glass cloth are in the range of 183 to 225 μm and 332 to 350 μm, respectively.

43. The glass cloth according to claim 5, wherein the warp width and weft width of the glass cloth are in the range of 190 to 218 μm and 335 to 347 μm, respectively.

44. The glass cloth according to claim 5, wherein the standard deviations of the warp width and weft width of the glass cloth are in the range of 20 μm or less and 43 μm or less, respectively.

45. The glass cloth according to any one of claims 1 to 5, wherein the coefficient of variation of the TEX of the glass yarn is 4.0% or less.

46. The glass cloth according to any one of claims 1 to 5, wherein the coefficient of variation of the TEX of the glass yarn is 3.0% or less.

47. A prepreg comprising a glass cloth according to any one of claims 1 to 5 and a matrix resin.

48. A printed circuit board comprising the prepreg described in claim 47.

49. An integrated circuit comprising a printed circuit board as described in claim 48.

50. An electronic device comprising a printed circuit board as described in claim 48.

Images