JP7796468B2 - Glass cloth manufacturing method and glass yarn - Google Patents

Description

The present invention relates to a method for manufacturing glass cloth and glass yarn.

With the recent development of the information and communications society, data communication and/or signal processing has become large-volume and high-speed, and the dielectric constant of printed wiring boards used in electronic devices has become significantly lower. As a result, many low-dielectric glass cloths have been proposed for use in printed wiring boards.

For example, the low dielectric glass cloth disclosed in Patent Document 1 achieves a low dielectric constant by incorporating a larger amount _{of B2O3} into the glass composition than the E-glass cloth that has been commonly used in the past, while simultaneously adjusting the amounts of other components such as _SiO2 .

Japanese Patent Application Publication No. 11-292567

The inventors' research has revealed that low-dielectric glass cloth made using such low-dielectric glass yarns varies greatly in performance and quality compared to conventionally used E-glass cloth. This variation in the performance and quality of glass cloth also affects the quality of prepregs, laminates for printed wiring boards, and other products made using the glass cloth.

The present invention was made in consideration of the above problems, and aims to provide a method for manufacturing low-dielectric glass cloth with uniform quality, and glass yarn suitable for manufacturing low-dielectric glass cloth.

After extensive research to solve the above problems, the inventors discovered that the above problems could be solved by setting the width of the glass yarn, the range of variation in width, and the uniformity of the range of variation in width to specific ranges, leading to the completion of the present invention.

That is, the present invention is as follows.
[1]
A method for producing a glass cloth, which is woven using glass yarns made of a plurality of glass filaments as warp yarns and weft yarns, comprising:
The density of the glass yarn to be the weft yarn is 2.2 g/cm ³ or more and less than 2.5 g/cm ³ ,
The yarn width dispersion coefficient indicating the yarn width variation of the glass yarn that becomes the weft yarn is 0.003 or more and
is less than or equal to 0.013, and/or
The yarn width distribution variation coefficient A, which indicates the yarn width distribution variation of the glass yarn that becomes the weft yarn, is 0
0.0002 or more and 0.0015 or less,
Glass cloth manufacturing method.
Yarn width variation coefficient = Value obtained by dividing the standard deviation of the yarn width (yarn width standard deviation A) by the average diameter of the glass filaments. Yarn width distribution variation coefficient A = Value obtained by dividing the standard deviation of the yarn width standard deviation B (yarn width standard deviation B) (yarn width distribution standard deviation) by the diameter of the glass filaments constituting the weft yarn when the standard deviation of the yarn width (yarn width standard deviation B) is obtained for every 0.5 m length [2].
The density of the glass yarn is more than 2.2 g/cm ³ and less than 2.5 g/cm ³ ;
The yarn width dispersion coefficient is more than 0.003 and less than 0.010,
And/or the yarn width distribution variation coefficient A is more than 0.0003 and less than 0.0012,
[1] A method for producing the glass cloth according to [1].
[3]
The yarn width distribution coefficient is 0.005 or more and 0.013 or less,
The yarn width distribution variation coefficient A is 0.0006 or more and 0.0015 or less,
And/or , the yarn width distribution variation coefficient B, which indicates the yarn width distribution variation of the glass yarn that becomes the weft yarn, is 0.013 or more and 0.027 or less;
[1] A method for producing the glass cloth according to [1].
Yarn width distribution variation coefficient B = A value obtained by dividing the yarn width distribution CV value, which is obtained by dividing the standard deviation of the yarn width standard deviation B (yarn width standard deviation B) every 0.5 m in length by the average value of the yarn width standard deviation B, by the diameter of the glass filaments constituting the weft yarn [4]
The average number of twists per 25 mm of the weft is 0.50 or more and 1.20 or less,
The standard deviation indicating the variation in the number of twists is 0.10 or more and 0.20 or less.
The method for producing a glass cloth according to any one of [1] to [3].
[5]
The weft yarn is a glass yarn formed by bundling 80 to 120 glass filaments having an average diameter of more than 4.5 μm and not more than 5.5 μm, and the average yarn width of the glass yarn is 90 μm to 130 μm.
0 μm or less,
[1] The method for producing a glass cloth according to any one of [1] to [4].
[6]
The weft yarn is made of 180 glass filaments having an average diameter of more than 4.5 μm and not more than 5.5 μm.
The glass yarn is a bundle of 220 or more glass yarns, and the average width of the glass yarns is 120 μm.
or more and 175 μm or less,
[1] The method for producing a glass cloth according to any one of [1] to [4].
[7]
The weft yarn is made of 180 glass filaments having an average diameter of more than 5.5 μm and not more than 6.5 μm.
The glass yarn is a bundle of 220 or more glass yarns, and the average yarn width of the glass yarn is 155 μm or more and 195 μm or less.
[1] The method for producing a glass cloth according to any one of [1] to [4].
[8]
The weft yarn is made of 180 glass filaments having an average diameter of more than 6.5 μm and not more than 7.5 μm.
The glass yarn is a bundle of 220 or more glass yarns, and the average yarn width of the glass yarn is 180 μm or more and 220 μm or less.
[1] The method for producing a glass cloth according to any one of [1] to [4].
[9]
The elastic modulus of the glass yarn is 50 to 70 GPa.
[1] The method for producing a glass cloth according to any one of [1] to [8].
[10]
The elastic modulus of the glass yarn is 50 to 63 GPa.
[9] A method for producing a glass cloth according to [9].
[11]
The glass cloth has a dielectric constant of 5.0 or less at a frequency of 1 GHz.
[11] The method for producing a glass cloth according to any one of [1] to [10].
[12]
The glass yarn,
The Si content is 40 to 60 mass% in terms of _SiO2 ,
The B content is 15 to 30 mass% calculated _{as B2O3} .
[12] The method for producing a glass cloth according to any one of [1] to [11].
[13]
The density is 2.2 g/cm ³ or more and less than 2.5 g/cm ³ ,
The yarn width dispersion coefficient, which indicates the yarn width variation, is 0.003 or more and 0.013 or less, and/or
The yarn width distribution variation coefficient A, which indicates the distribution variation of the yarn width, is 0.0002 or more and 0.0015 or less;
Glass thread.
Yarn width variation coefficient = Value obtained by dividing the standard deviation of the yarn width (yarn width standard deviation A) by the average diameter of the glass filaments. Yarn width distribution variation coefficient A = Value obtained by dividing the standard deviation of the yarn width standard deviation B (yarn width standard deviation B) (yarn width distribution standard deviation) by the diameter of the glass filaments constituting the weft yarn when the standard deviation of the yarn width (yarn width standard deviation B) is obtained for every 0.5 m length [14].
The density of the glass yarn is more than 2.2 g/cm ³ and less than 2.5 g/cm ³ ;
The yarn width dispersion coefficient is more than 0.003 and less than 0.010,
And/or the yarn width distribution variation coefficient A is more than 0.0003 and less than 0.0012,
The glass fiber according to [13].
[15]
The yarn width dispersion coefficient is 0.005 or more and 0.013 or less,
The yarn width distribution variation coefficient A is 0.0006 or more and 0.0015 or less,
And/or , the yarn width distribution variation coefficient B, which indicates the yarn width distribution variation of the glass yarn that becomes the weft yarn, is 0.013 or more and 0.027 or less;
The glass fiber according to [13].
Yarn width distribution variation coefficient B = A value obtained by dividing the yarn width distribution CV value, which is obtained by dividing the standard deviation of the yarn width standard deviation B (yarn width standard deviation B) calculated for each 0.5 m length by the average value of the yarn width standard deviation B, by the diameter of the glass filaments constituting the weft yarn [16]
The average number of twists per 25 mm is 0.50 or more and 1.20 or less,
The standard deviation indicating the variation in the number of twists is 0.10 or more and 0.20 or less.
[13] The glass fiber according to any one of [15] to [16].
[17]
The glass yarn is a bundle of 80 to 120 glass filaments having an average diameter of more than 4.5 μm and not more than 5.5 μm, and the average yarn width is 90 μm to 130 μm.
[13] The glass fiber according to any one of [16] to [17].
[18]
180 or more 220 glass filaments with an average diameter of more than 4.5 μm and less than 5.5 μm
The glass fibers are bundled together in a bundle of 100 or less strands, and the average fiber width is 120 μm or more and 175 μm or less.
[13] The glass fiber according to any one of [16] to [17].
[19]
180 or more 220 glass filaments with an average diameter of more than 5.5 μm and less than 6.5 μm
The glass yarn is bundled together in a bundle of 100 or less strands, and the average yarn width is 155 μm or more and 195 μm or less.
[13] The glass fiber according to any one of [16] to [17].
[20]
180 or more 220 glass filaments with an average diameter of more than 6.5 μm and less than 7.5 μm
The glass yarn is bundled together in a bundle of 100 or less strands, and the average yarn width is 180 μm or more and 220 μm or less.
[13] The glass fiber according to any one of [16] to [17].
[21]
The elastic modulus is 50 to 70 GPa.
[13] to [20] The glass fiber according to any one of [13] to [20].
[22]
The elastic modulus is 50 to 63 GPa.
[13] to [20] The glass fiber according to any one of [13] to [20].
[23]
having a dielectric constant of 5.0 or less at a frequency of 1 GHz;
[13] to [22] The glass fiber according to any one of [13] to [22].
[24]
The Si content is 40 to 60 mass% in terms of _SiO2 ,
The B content is 15 to 30 mass% calculated _{as B2O3} .
[13] to [23] The glass fiber according to any one of [13] to [23].

The present invention provides a method for producing low-dielectric glass cloth with uniform quality, and glass yarn suitable for producing low-dielectric glass cloth.

FIG. 2 is a perspective view showing one aspect of a weaving step in the manufacturing method of the present embodiment.

The following describes in detail an embodiment of the present invention (hereinafter referred to as the "present embodiment"); however, the present invention is not limited to this embodiment, and various modifications are possible without departing from the spirit of the present invention.

[Method for manufacturing glass cloth]
The method for producing a glass cloth of this embodiment is a method for producing a glass cloth obtained by weaving glass yarns consisting of a plurality of glass filaments as warp yarns and weft yarns, wherein the density of the glass yarns that form the weft yarns is 2.2 g/ ^cm3 or more and less than 2.5 g/ ^cm3 , the glass yarns that form the weft yarns have a yarn width dispersion coefficient that indicates a yarn width variation of 0.003 or more and 0.013 or less, and/or the yarn width distribution variation coefficient A that indicates a yarn width distribution variation of the glass yarns that form the weft yarns is 0.0002 or more and 0.0015 or less.

It has been found that glass cloth manufactured using low-dielectric glass yarns varies in quality compared to conventional E-glass cloth, and that in rare cases, glass cloth of inferior quality is produced. A detailed examination of relatively poor-quality glass cloth among these revealed that they have in common the presence of unevenly distributed wide and narrow glass yarns, and that they use glass yarns with large variations in yarn width. Furthermore, glass cloth made from glass yarns with such large variations in yarn width distribution often had weaving defects, such as areas where the filaments that make up the glass yarns had partially broken, creating a fuzz-like appearance, and areas where the weft yarns were loose.

The reason for this is not limited, but it is thought that glass yarns (weft yarns) with an uneven distribution of wide and thin yarn widths have difficulty achieving a stable flight trajectory when woven, making it difficult for them to pass straight between the warp yarns, which makes them more likely to produce fuzz and weaving defects.

The E-glass glass yarns used until now are heavier than low-dielectric glass yarns, and variations in yarn width have had little impact on weaving. However, with lighter low-dielectric glass yarns, the weft yarn is more susceptible to the effects of the yarn width shape when woven, which is thought to increase the occurrence of fuzz and weaving defects.

In addition, low-dielectric glass yarns have a small elastic modulus and are not strong against mechanical loads, which is thought to make the filaments more susceptible to breakage and promote the generation of fuzz. These effects are thought to be reflected in the quality of the woven glass cloth.

In contrast to this, in this embodiment, a weft yarn having a glass yarn density of 2.2 g/cm ^or more and less than 2.5 g/ ^cm3 , in which the weft yarn width variation range (yarn width distribution coefficient) is 0.003 or more and 0.013 or less, or the weft yarn width distribution range (yarn width distribution variation coefficient A) is 0.0002 or more and 0.0015 or less, is used, thereby reducing the influence of the yarn width shape during weaving even when a relatively light glass yarn with low dielectric constant is used. This makes it possible to suppress the occurrence of fluff and weaving defects and obtain a glass cloth of uniform quality.

(Glass thread density)
The density of the glass yarn in the weft is 2.2 g/cm or ^more and less than 2.5 g/ ^cm3 , preferably more than 2.2 g/ ^cm3 and less than 2.5 g/ ^cm3 , more preferably 2.22 g/ ^cm3 or more and 2.45 g/ ^cm3 or less, and even more preferably 2.25 g/ ^cm3 or more and 2.4 g/ ^cm3 or less. If the density of the glass yarn in the weft is less than 2.5 g/ ^cm3 , the flying trajectory is easily affected by the shape of the glass yarn when the weft is woven by being placed on the discharged air, and quality defects such as fuzz and weaving defects are likely to occur. However, by setting the yarn width dispersion coefficient and yarn width distribution variation coefficient A of the weft within the specific ranges of the present invention, the flying trajectory can be stabilized, and a high-quality glass cloth can be stably obtained. By setting the density of the glass yarn in the weft to 2.2 g/ ^cm3 or more, the flight trajectory of the weft yarn can be stabilized when the yarn width variation range and yarn width distribution variation range of the weft yarn are within the ranges of the present invention. The glass density of the warp yarn may be the same as or different from the above range, but is preferably within the same range from the viewpoint of uniforming the properties of the glass cloth, such as air permeability, resin impregnation, resin adhesion, and electrical properties, and from the viewpoint of obtaining a low-dielectric glass cloth. The density of the glass yarn can be determined as the density of a block of glass per 1 ^cm3 .

(Weft yarn bundle width dispersion coefficient)
The yarn width dispersion coefficient of the weft yarn bundle is 0.003 or more, preferably more than 0.003, more preferably 0.004 or more, even more preferably 0.005 or more, still more preferably 0.006 or more, and particularly preferably 0.007 or more. Furthermore, the yarn width dispersion coefficient of the weft yarn bundle is 0.013 or less, preferably less than 0.010, and more preferably 0.009 or less. When the yarn width dispersion coefficient is within the above range, excessive air pressure is not required when the weft yarn is driven into the air jet loom, and the weft yarn can be inserted along a stable flight trajectory from the driving side to the opposite side, thereby enabling a high-quality glass cloth with little fuzz or weaving defects to be consistently obtained.

The yarn width dispersion coefficient of a yarn bundle is a value obtained by dividing the standard deviation of the yarn width measurements of the yarn bundle by the average diameter of the glass filaments constituting the yarn bundle. The yarn width dispersion coefficient of the warp yarn bundle may be the same as or different from the above range, but is preferably in the same range from the viewpoint of further suppressing the occurrence of fluff and weaving defects.
Yarn width dispersion coefficient = Value obtained by dividing the standard deviation of the yarn width (yarn width standard deviation A) by the average diameter of the glass filaments

(Weft yarn width distribution variation coefficient A)
The weft width distribution variation coefficient A is 0.0002 or more, preferably more than 0.0003, and more preferably 0.0004 or more. The weft width distribution variation coefficient A is 0.0015 or less, preferably less than 0.0012, and more preferably 0.0010 or less. When the weft width distribution variation coefficient A is within the above range, the weft yarn is likely to fly straight and stably without disturbance of its flight trajectory, and a high-quality glass cloth with little fuzz or weaving defects can be stably obtained. This is presumably because the weft yarn can receive compressed air uniformly in the length direction. Furthermore, when the yarn width distribution variation coefficient A is within the above range, the unwinding resistance when unwinding the yarn bundle from the bobbin is kept within a small range, and a high-quality glass cloth with little fuzz or weaving defects can be stably obtained. This is presumably because excessive overlap of the yarns on the bobbin on which they are wound can be avoided. If the yarn bundle frays during unwinding and one or several filaments separate, the filaments will break at this location during weaving and subsequent processes, resulting in fuzz and weaving defects.

Furthermore, when it is desired to stabilize the flight characteristics of the weft yarn and place greater emphasis on weaving productivity, the weft yarn width distribution variation coefficient A is 0.0002 or more and 0.0015 or less, and preferably 0.0006 or more and 0.0015 or less.

The yarn width distribution variation coefficient A of the yarn bundle is a value obtained by using the standard deviation (standard deviation A) of yarn width measurements in a specific short length range (e.g., 0.5 m) to determine the yarn width distribution state in a long length range (e.g., 50 m) as the standard deviation (standard deviation B = standard deviation of standard deviation A), and dividing this by the average diameter of the filaments constituting the yarn bundle. Note that the yarn width distribution variation coefficient A of the warp yarn bundle may be the same as or different from the above range, but is preferably in the same range from the viewpoint of further suppressing the occurrence of fuzz and weaving defects.
Coefficient of variation of yarn width distribution A = Value obtained by dividing the standard deviation of yarn width standard deviation B (yarn width distribution standard deviation) when determining the standard deviation of yarn width (yarn width standard deviation B) for every 0.5 m length by the diameter of the glass filaments that make up the weft yarn

It is preferable that both the yarn width dispersion coefficient and yarn width distribution variation coefficient A of the yarn bundle be within the above ranges.

The yarn width dispersion coefficient, yarn width distribution variation coefficient A, and average value of a yarn bundle can be calculated from the yarn width data obtained by measuring the yarn width of glass yarns of 10 m or more at equal intervals shorter than 1 mm.

The method for measuring the thread width in this case is not particularly limited, but for example, an LED light beam can be irradiated from the side and the width of the glass thread can be obtained from the projected width of the part where the LED light beam is blocked by the glass thread. This method can be used to continuously measure the width while the glass thread is being continuously transported. The thread width can also be measured while observing it under a microscope.

(Weft yarn width distribution variation coefficient B)
The yarn width distribution variation coefficient B, which indicates the yarn width distribution variation of the glass yarn serving as the weft yarn, is preferably 0.013 or more, more preferably 0.014 or more, and even more preferably 0.015 or more. Furthermore, the yarn width distribution variation coefficient B is preferably 0.027 or less, more preferably 0.024 or less, and even more preferably 0.021 or less. When the yarn width distribution variation coefficient B is within the above range, the flying stability of the weft yarn tends to be further improved.

Yarn width distribution coefficient of variation B = The value calculated by dividing the standard deviation of the yarn width standard deviation B (yarn width standard deviation B) every 0.5 m of length (yarn width standard deviation B) by the average value of the yarn width standard deviation B (yarn width distribution standard deviation), and then dividing this value by the diameter of the glass filaments that make up the weft.

(average yarn width)
In the method for producing a glass cloth of the present invention, when a glass cloth having a thickness of 20 μm or more and 38 μm or less is produced, it is preferable that a glass yarn formed by bundling 80 to 120 glass filaments having an average diameter of more than 4.5 μm and not more than 5.5 μm is used as a weft yarn, and that the average yarn width of the weft yarn is 90 μm or more and 130 μm or less. In this case, the average yarn width is more preferably 95 μm or more, even more preferably 100 μm or more, and particularly preferably 102 μm or more. Furthermore, the average yarn width is more preferably 125 μm or less, even more preferably 122 μm or less, and particularly preferably 120 μm or less.

When manufacturing glass cloth with a thickness of 39 μm or more and 63 μm or less, it is preferable to use glass yarns for the weft, which are made by bundling 180 to 220 glass filaments with an average diameter of more than 4.5 μm and not more than 5.5 μm, and the average yarn width of the weft yarns is 120 μm or more and 175 μm or less. In this case, the average yarn width is more preferably 125 μm or more, and even more preferably 130 μm or more. Furthermore, the average yarn width is more preferably 170 μm or less, even more preferably 165 μm or less, and particularly preferably 150 μm or less.

When manufacturing glass cloth with a thickness of 64 μm or more and 83 μm or less, it is preferable to use glass yarns for the weft, which are made by bundling 180 to 220 glass filaments with an average diameter of more than 5.5 μm and 6.5 μm or less, and the average yarn width of the weft yarns is 155 μm or more and 195 μm or less. In this case, the average yarn width is more preferably 160 μm or more, and even more preferably 162 μm or more. Furthermore, the average yarn width is more preferably 191 μm or less, even more preferably 183 μm or less, and particularly preferably 170 μm or less.

When manufacturing glass cloth with a thickness of 84 μm or more and 100 μm or less, it is preferable to use glass yarns for the weft, which are made by bundling 180 to 220 glass filaments with an average diameter of more than 6.5 μm and 7.5 μm or less, and the average yarn width of the weft yarns is 180 μm or more and 220 μm or less. In this case, the average yarn width is more preferably 185 μm or more, and even more preferably 190 μm or more. Furthermore, the average yarn width is more preferably 215 μm or less, and even more preferably 210 μm or less.

By having the average weft width be equal to or less than the above upper limit, the effect of any variation in the width is reduced, and the occurrence of fuzz and weaving defects in the resulting glass cloth tends to be suppressed. Furthermore, by having the average width be equal to or greater than the above lower limit, the glass yarns are appropriately exposed to the injected air during weft insertion, allowing the weft to be blown out with a relatively gentle injection pressure, which tends to suppress the occurrence of fuzz and weaving defects in the resulting glass cloth. The average warp width may be the same as or different from the above range, but it is preferably within the same range from the perspective of further suppressing the occurrence of fuzz and weaving defects.

(variation in twist number)
The standard deviation indicating the variation in the number of twists per 25 mm of the weft yarn is preferably 0.03 or more, more preferably 0.05 or more, and even more preferably 0.10 or more. The standard deviation indicating the variation in the number of twists per 25 mm of the weft yarn is preferably 0.20 or less, more preferably 0.18 or less, even more preferably 0.15 or less, and particularly preferably 0.13 or less. When the standard deviation of the number of twists is within the above range, the influence of the shape of the yarn width during weaving is reduced, and the occurrence of fluff and weaving defects in the resulting glass cloth tends to be suppressed. Furthermore, when the standard deviation of the number of twists is within the above range, the glass cloth tends to have excellent solder heat resistance.

The standard deviation indicating the variation in the number of twists per 25 mm of the warp yarn is preferably 0.03 or more, more preferably 0.05 or more, and even more preferably 0.10 or more. Furthermore, the standard deviation indicating the variation in the number of twists per 25 mm of the warp yarn is preferably 0.20 or less, more preferably 0.18 or less, even more preferably 0.15 or less, and particularly preferably 0.13 or less. Having the standard deviation in the number of twists within the above range is preferable from the perspective of further suppressing the occurrence of fuzz and weaving defects. Furthermore, having the standard deviation in the number of twists within the above range tends to result in excellent solder heat resistance. The standard deviations in the number of twists of the weft and warp yarns may be the same or different.

The reason why excellent solder heat resistance is achieved when the standard deviation indicating the variation in the number of twists per 25 mm of the weft and/or warp yarns is within the above range is not particularly limited, but is thought to be as follows: When the standard deviation indicating the variation in the number of twists is 0.10 or more, adjacent yarns are prevented from coming into excessive contact with each other, and an appropriate gap is formed between adjacent yarns, which improves resin impregnation into the glass cloth and tends to improve adhesion between the glass yarns and the resin. It is therefore believed that solder heat resistance is further improved. Furthermore, when the standard deviation indicating the variation in the number of twists is 0.20 or less, the distribution of glass yarns becomes more uniform in the resulting glass cloth and in the substrate obtained by impregnating glass cloth with resin, which tends to prevent the occurrence of locally weak areas. It is therefore believed that solder heat resistance is further improved.

(Average number of twists)
The average number of twists per 25 mm of the weft yarn is preferably 0.50 to 1.20, more preferably 0.60 to 1.10, and even more preferably 0.65 to 1.05. When the average number of twists is within the above range, the influence of the shape of the yarn width during weaving becomes smaller, and the occurrence of fluff and weaving defects in the obtained glass cloth tends to be suppressed.

The average number of twists per 25 mm of the warp yarns is preferably 0.50 to 1.20, more preferably 0.60 to 1.10, and even more preferably 0.65 to 1.05. Having the average number of twists within the above range is preferable from the perspective of further suppressing the occurrence of fuzz and weaving defects. The average number of twists of the weft and warp yarns may be the same or different.

(Configuration of glass yarn)
Next, the structure of the glass yarn will be explained. The glass yarn is obtained by bundling a plurality of glass filaments and twisting them as necessary. In this case, the glass yarn is classified as a multifilament, and the glass filament is classified as a monofilament.

The average diameter of the glass filaments that make up the warp and weft threads is preferably 2.5 to 9 μm, more preferably 3.0 to 7.5 μm, and even more preferably 3.5 to 5.4 μm. Having an average diameter of 9 μm or less improves processability, enabling the creation of thin, high-density printed wiring boards. Furthermore, having an average diameter of 3.5 μm or more tends to make the glass cloth less susceptible to breakage.

Elements that make up glass fibers include Si, B, Al, Ca, Mg, P, Na, K, Ti, Zn, Fe, F, etc.

The Si content of the glass yarn, calculated as _SiO2 , is preferably 40 to 60% by mass, more preferably 45 to 55% by mass, even more preferably 47 to 53% by mass, and even more preferably 48 to 52% by mass. Si is a component that forms the skeletal structure of the glass yarn. When the Si content is 40% by mass or more, the strength of the glass yarn is further improved, and breakage of the glass cloth tends to be further suppressed in the glass cloth manufacturing process and in subsequent processes such as the production of prepregs using the glass cloth. Furthermore, when the Si content is 40% by mass or more, the dielectric constant of the glass cloth tends to be further reduced. On the other hand, when the Si content is 60% by mass or less, the viscosity at the time of melting is further reduced in the glass filament manufacturing process, and glass fibers with a more homogeneous glass composition tend to be obtained. Therefore, the resulting glass filaments are less likely to have parts that are prone to devitrification or parts that are difficult to remove bubbles from, and therefore the glass filaments are less likely to have locally weak parts. As a result, glass cloths composed of glass yarns obtained using this are less likely to break. The Si content can be adjusted depending on the amount of raw material used to prepare the glass filaments.

The B content of the glass yarn, calculated as _B2O3 , is preferably 15 to ₃₀ mass%, more preferably 17 to 28 mass%, even more preferably 20 to 27 mass%, still more preferably 21 to 25 mass%, and even more preferably 21.5 to 24 mass%. A B content of 15 mass% or more tends to further reduce the dielectric constant. Furthermore, a B content of 30 mass% or less tends to improve moisture absorption resistance and insulation reliability. The B content can be adjusted depending on the amount of raw material used in producing the glass filaments. Note that if the B content may fluctuate during glass filament production, the amount charged can be adjusted in advance in anticipation of this.

The Al content of the glass filament is preferably 11 to 18 mass%, more preferably 11 to 16 mass%, and even more preferably 12 to 16 mass%, calculated as _Al2O3 . The _Al content within the above range tends to further improve electrical properties and strength. The Al content can be adjusted depending on the amount of raw material used to produce the glass filament.

The Ca content of the glass yarn is preferably 5 to 10 mass%, preferably 5 to 9 mass%, and more preferably 5 to 8.5 mass%, calculated as CaO. When the Ca content is 4 mass% or more, the viscosity at the time of melting tends to be lower in the manufacturing process of the glass filament, and glass fibers with a more homogeneous glass composition tend to be obtained. Furthermore, when the Ca content is 10 mass% or less, the dielectric constant tends to be improved. The Ca content can be adjusted depending on the amount of raw material used to manufacture the glass filament.

The above contents can be measured by ICP atomic emission spectroscopy. Specifically, the Si content and B content can be obtained by melting a weighed glass cloth sample with sodium carbonate, dissolving it in dilute nitric acid to a constant volume, and measuring the resulting sample by ICP atomic emission spectroscopy. The Fe content can be obtained by dissolving a weighed glass cloth sample using an alkaline dissolution method to a constant volume, and measuring the resulting sample by ICP atomic emission spectroscopy. The Al content, Ca content, and Mg content can be obtained by thermally decomposing a weighed glass cloth sample with sulfuric acid, nitric acid, and hydrogen fluoride, dissolving it in dilute nitric acid to a constant volume, and measuring the resulting sample by ICP atomic emission spectroscopy. The ICP atomic emission spectroscopy analyzer that can be used is the PS3520VDD II manufactured by Hitachi High-Tech Science Corporation.

The elastic modulus of the glass yarn is preferably 50 to 70 GPa, more preferably 50 to 63 GPa, and even more preferably 53 to 63 GPa. An elastic modulus of 50 GPa or more improves the rigidity of the glass yarn, and tends to make it less likely to fluff during the manufacturing process. Furthermore, an elastic modulus of 70 GPa or less improves the brittleness resistance of the glass yarn, and tends to make it less likely to fluff during the manufacturing process. Furthermore, an elastic modulus within the above range gives the glass yarn appropriate flexibility, making it less likely to experience filament breakage when mechanical load is applied, and less likely to produce fluff or weaving defects.

The dielectric constant of the resulting glass cloth is preferably 5.0 or less at a frequency of 1 GHz, more preferably 4.8 or less, even more preferably 4.6 or less, and particularly preferably 4.0 or less. The dielectric constant can be measured, for example, by a cavity resonance method. In this embodiment, the dielectric constant refers to the value at a frequency of 1 GHz unless otherwise specified. A glass cloth with a dielectric constant of 5.0 or less at a frequency of 1 GHz is preferred because it can meet the demand for a low dielectric constant.

The manufacturing method of the glass cloth of this embodiment is not particularly limited as long as it uses the above-mentioned weft yarn, but examples include a method having a yarn width adjustment process in which the yarn width of the weft yarn is adjusted so that the yarn width dispersion coefficient is 0.003 to 0.013 and/or the yarn width variation coefficient is 0.0002 to 0.0015; a weaving process in which glass yarns are woven to obtain glass cloth; and a fiber-opening process in which the glass yarns of the glass cloth are opened. Furthermore, if necessary, the method may also have a desizing process in which sizing agent adhering to the glass yarns of the glass cloth is removed, and a surface treatment process using a silane coupling agent. Each step of this embodiment will be described in more detail below.

[Thread width adjustment process]
The yarn width adjusting step is a step of adjusting the yarn width distribution coefficient of the weft yarn to be used to be 0.003 or more and 0.013 or less and/or the yarn width distribution variation coefficient A to be 0.0002 or more and 0.0015 or less. More specifically, in the yarn width adjusting step, the yarn width distribution coefficient and/or yarn width distribution variation coefficient A of the weft yarn are measured, and if the yarn width distribution coefficient is 0.003 or more and 0.013 or less and/or the yarn width distribution variation coefficient A is 0.0002 or more and 0.0015 or less, the yarn is used in the subsequent weaving step, and if it is outside the range, the yarn is discarded or adjusted by untwisting or untwisting so that the yarn width distribution coefficient is 0.003 or more and 0.013 or less and/or the yarn width distribution variation coefficient A is 0.0002 or more and 0.0015 or less. Alternatively, it is also possible to provide feedback to the glass yarn manufacturing process and adjust the yarn manufacturing conditions. The width of the glass yarn is affected by variations in the number of twists, such as between high and low twist density parts, and variations in the width of the glass filaments. Therefore, the coefficient of variation of the glass yarn to be used in the weaving process can be adjusted by untwisting or untwisting. Furthermore, if the measurement of the yarn width distribution coefficient and/or yarn width distribution coefficient of variation A of the weft yarn shows that the quality of the glass yarn exceeds the range of the coefficient of variation that can be adjusted by twisting, the glass yarn itself can be replaced as part of the adjustment of the coefficient of variation.

[Weaving process]
The weaving process is a process in which glass yarns are woven to obtain a glass cloth. The weaving method is not particularly limited as long as it weaves weft yarns and warp yarns to form a predetermined weave structure. The weaving structure of the glass cloth is not particularly limited, and examples thereof include plain weave, sash weave, satin weave, twill weave, etc. Among these, a plain weave structure is more preferred.

Figure 1 shows a perspective view of one aspect of the weaving process in the manufacturing method of this embodiment. Figure 1 illustrates one aspect of the weaving process using an air jet loom system. Parallel-pulled warp yarns 1 are opened above and below the opening, and yarns fed from a weft storage device 2 are sent through the opening by a jet of air from a nozzle 3, resulting in weaving. In this weaving process, lightweight weft yarns with a large yarn width dispersion coefficient and/or yarn width distribution variation coefficient A are difficult to send straight, potentially resulting in fuzz and weaving defects in the resulting glass cloth. In contrast, this embodiment uses weft yarns with a yarn width dispersion coefficient of 0.003 to 0.013 and/or a yarn width distribution variation coefficient A of 0.0002 to 0.0015, achieved by, for example, the yarn width adjustment process, thereby suppressing the occurrence of fuzz and weaving defects when the weft yarns are woven. This improves the in-plane and lot-to-lot quality of the glass cloth. The weaving method is not limited to the air jet loom method, but may also be a water jet loom method or a shuttle method.

The spacing density of the warp and weft threads that make up the glass cloth is preferably 30 to 120 threads/inch, more preferably 40 to 110 threads/inch, and even more preferably 50 to 100 threads/inch. The spacing density of the warp threads can be controlled by adjusting the spacing between the parallel warp threads, and the spacing density of the weft threads can be controlled by the number of times the weft threads are sprayed from the nozzle per unit time and the flow speed of the warp threads.

Furthermore, the thickness of the glass cloth finally obtained after the fiber-opening process, etc. is preferably 8 to 100 μm, more preferably 9 to 90 μm, and even more preferably 9.5 to 80 μm. Having a glass cloth thickness within the above range tends to result in a thin glass cloth with relatively high strength.

The fabric weight (basis weight) of the glass cloth is preferably 8 to 250 g/m ² , more preferably 8 to 130 g/m ² , even more preferably 8 to 100 g/m ² , and particularly preferably 8 to 90 g/m ² .

[Opening process]
The opening step is a step of opening the glass fibers of the glass cloth. The opening method is not particularly limited, but examples thereof include opening processing using spray water (high-pressure water opening), a vibro washer, ultrasonic water, a mangle, etc.

[Desizing process]
The desizing step is a step of removing the sizing agent attached to the glass yarns of the glass cloth. The desizing method is not particularly limited, but for example, a method of removing the sizing agent by heating can be mentioned.

[Surface treatment process]
The surface treatment step is a step of performing a surface treatment using a silane coupling agent. Examples of the surface treatment method include contacting a surface treatment agent containing a silane coupling agent with glass cloth and drying the resulting mixture. Examples of contacting the glass cloth with the surface treatment agent include immersing the glass cloth in the surface treatment agent, or applying the surface treatment agent to the glass cloth using a roll coater, a die coater, a gravure coater, or the like. The method for drying the surface treatment agent is not particularly limited, and examples thereof include hot air drying and drying using electromagnetic waves.

(Surface treatment)
The glass cloth may be surface-treated with a surface treatment agent. The surface treatment agent is not particularly limited, but examples thereof include a silane coupling agent, and water, an organic solvent, an acid, a dye, a pigment, a surfactant, and the like may be used in combination as needed.

The silane coupling agent is not particularly limited, but examples thereof include compounds represented by formula (1).
X(R) _3-n SiY _n ...(1)
(In formula (1), X represents an organic functional group having at least one of an amino group and an unsaturated double bond group; each Y represents independently an alkoxy group; n represents an integer of 1 to 3; and each R represents independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.)

X is preferably an organic functional group having at least three or more amino groups and unsaturated double bond groups, and more preferably an organic functional group having at least four or more amino groups and unsaturated double bond groups.

The above alkoxy group can be in any form, but from the perspective of stabilizing the treatment of glass cloth, alkoxy groups with 5 or fewer carbon atoms are preferred.

Specific examples of silane coupling agents include N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropylmethyldimethoxysilane and its hydrochloride, N-β-(N-di(vinylbenzyl)aminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-di(vinylbenzyl)aminoethyl)-N-γ-(N-vinylbenzyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, and N-β Examples include known simple substances such as N-(N-benzylaminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-benzylaminoethyl)-γ-aminopropyltriethoxysilane and its hydrochloride, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, and acryloxypropyltrimethoxysilane, or mixtures thereof.

The molecular weight of the silane coupling agent is preferably 100 to 600, more preferably 150 to 500, and even more preferably 200 to 450. Among these, it is preferable to use two or more silane coupling agents with different molecular weights. Treating the surface of the glass yarn with two or more silane coupling agents with different molecular weights increases the density of the surface treatment agent on the surface of the glass cloth, which tends to further improve reactivity with the matrix resin.

[Other methods for producing glass cloth]
In the present embodiment, as another aspect, a method for producing a glass cloth may be used, which is obtained by weaving glass yarns consisting of a plurality of glass filaments as warp yarns and weft yarns, in which the average number of twists per 25 mm of the weft yarns is 0.50 or more and 1.20 or less, the standard deviation of the number of twists is 0.03 or more and 0.18 or less, and the density of the glass yarns that become the weft yarns is 2.2 g/ ^cm3 or more and less than 2.5 g/ ^cm3 .

[Glass thread]
The glass yarn of this embodiment is the glass yarn used in the above-mentioned method for producing a glass cloth, particularly the glass yarn used as a weft. The configuration of the glass yarn may be the same as that described above.

The glass cloth of this embodiment is obtained by the above-mentioned glass cloth manufacturing method and has the above-mentioned glass yarn as at least the weft yarn.

[Prepreg]
The prepreg of this embodiment comprises the glass cloth obtained as described above and a matrix resin composition impregnated into the glass cloth. Prepregs containing the glass cloth have little variation in quality and a high yield of final products. Furthermore, because they have excellent dielectric properties and moisture absorption resistance, they can provide printed wiring boards with little variation in dielectric constant under the influence of the usage environment, particularly in high-humidity environments.

The prepreg of this embodiment can be manufactured according to conventional methods. For example, it can be manufactured by impregnating the glass cloth of this embodiment with a varnish made by diluting a matrix resin such as epoxy resin with an organic solvent, volatilizing the organic solvent in a drying oven, and curing the thermosetting resin to a B-stage state (semi-cured state).

In addition to the epoxy resins mentioned above, examples of matrix resin compositions include thermosetting resins such as bismaleimide resin, cyanate ester resin, unsaturated polyester resin, polyimide resin, BT resin, and functionalized polyphenylene ether resin; thermoplastic resins such as polyphenylene ether resin, polyetherimide resin, wholly aromatic polyester liquid crystal polymer (LCP), polybutadiene, and fluororesin; and mixed resins thereof. From the perspective of improving dielectric properties, heat resistance, solvent resistance, and press moldability, resins obtained by modifying a thermoplastic resin with a thermosetting resin may also be used as the matrix resin composition.

The matrix resin composition may also contain inorganic fillers such as silica and aluminum hydroxide; flame retardants such as bromine-based, phosphorus-based, and metal hydroxide; silane coupling agents; heat stabilizers; antistatic agents; ultraviolet absorbers; pigments; colorants; lubricants, etc.

[Printed wiring board]
The printed wiring board of this embodiment includes the prepreg. A printed wiring board including the prepreg of this embodiment has little variation in quality and a high yield of final products. Furthermore, because the prepreg has excellent dielectric properties and moisture absorption resistance, it also has the effect of minimizing fluctuations in the dielectric constant due to the influence of the usage environment, particularly in high humidity environments.

The present invention will be explained in more detail below using examples and comparative examples. The present invention is not limited in any way by the following examples.

[Physical properties of glass cloth]
The physical properties of the glass cloth, specifically, the thickness of the glass cloth, the diameter of the filaments constituting the warp and weft, the number of filaments, and the weaving density of the warp and weft (weave density) were measured in accordance with JIS R3420.

[Elastic modulus]
The elastic modulus was measured by the pulse-echo overlap method.

[Composition of glass yarn]
The composition of the glass fiber was measured by ICP optical emission spectroscopy. Specifically, the Si content and B content were obtained by melting a weighed glass cloth sample with sodium carbonate, dissolving it in dilute nitric acid to a constant volume, and measuring the resulting sample by ICP optical emission spectroscopy. The Fe content was obtained by dissolving a weighed glass cloth sample by an alkaline dissolution method to a constant volume, and measuring the resulting sample by ICP optical emission spectroscopy. The Al content, Ca content, and Mg content were obtained by thermally decomposing a weighed glass cloth sample with sulfuric acid, nitric acid, and hydrogen fluoride, then dissolving it in dilute nitric acid to a constant volume, and measuring the resulting sample by ICP optical emission spectroscopy. The ICP optical emission spectroscopy analyzer used was a PS3520VDD II manufactured by Hitachi High-Tech Science Corporation.

[Measurement of standard deviation A and average value of yarn width]
While conveying the glass yarn at a speed of 1 m/min, the width of 50 m of the glass yarn was measured using an LED projection type transmission dimension measuring instrument (HIGH ACCURACY CMOS MICROMETER LS-9006MR / manufactured by Keyence Corporation), and the standard deviation of the yarn width of the glass yarn (yarn width standard deviation A) and the average value of the yarn width were calculated from the obtained yarn width data.

The tension acting on the glass yarn when it is transported is a tension measured with a tension meter (Control instruments ETPB-100-C0585 manufactured by SCHMIDT),
Examples 1 to 18, Comparative Example 1, and Reference Examples 1 to 3 are 0.12 to 0.18 N
In Examples 19 to 29 and Comparative Examples 2 and 3, the pressure was 0.10 to 0.17N.
In Examples 30 to 40 and Comparative Examples 4 and 5, the pressure was 0.08 to 0.16N.
In Examples 41 to 48 and Comparative Examples 6 and 7, the pressure was 0.07 to 0.14N.
It was.

[Measurement of yarn width standard deviation B and yarn width distribution standard deviation]
The yarn width data of 50 m of glass yarn obtained as described above was divided into 100 equal parts in the length direction, and 100 pieces of yarn width data of the glass yarn were obtained every 0.5 m. Based on this yarn width data of the glass yarn every 0.5 m, the standard deviation (yarn width standard deviation B) was calculated. Then, in order to confirm the variation of the yarn width standard deviation B, the standard deviation was calculated based on the obtained 100 yarn width standard deviations B, and the yarn width distribution standard deviation was obtained.

[Variation in twist count]
The number of twists of 50 cm of the glass yarn was measured using a twist detector (manufactured by Technos Co., Ltd.) and converted into the number of twists per 25 mm. The standard deviation calculated from 30 pieces of twist data obtained (measurements were made at 10 points on the outer layer side of the bobbin, 10 points in the middle, and 10 points on the inner layer side) was used as the variation in the number of twists.

[Evaluation 1: Fluff, weaving defects quality]
1000 m of glass cloth was unwound from the glass cloth rolls obtained in the Examples and Comparative Examples, and the presence or absence of fluff and weaving defects was checked, and the quality was evaluated according to the following evaluation criteria.
5: Three or fewer fluffs or weaving defects were observed.
4: 3 to 5 fluffs or weaving defects were observed.
3: 6 to 15 fluffs or weaving defects were observed.
2: 15 to 30 fluffs or weaving defects were observed.
1: 30 or more fluffs or weaving defects were observed.

[Evaluation 2: Weaving ability]
In the weaving process using the air jet loom in the Examples and Comparative Examples, the number of times weaving stopped during the weaving of 2100 glass cloths was counted, and the weavability was evaluated according to the following evaluation criteria.
5: Stopped 0 times.
4: Stop 1-2 times.
3: Stop 3-4 times.
2: Stop 5 to 7 times.
1: Stopped 8 times or more.

[Evaluation 3: Heat resistance]
The glass cloth obtained in each of the examples and comparative examples was impregnated with polyphenylene ether resin varnish, and then the excess varnish was scraped off by passing it through a predetermined slit. The cloth was then dried for a predetermined time in a drying oven at 105°C to remove the toluene, thereby obtaining a prepreg.

Eight sheets of the resulting prepreg were stacked, and copper foil (FV-WS foil, manufactured by Furukawa Electric Co., Ltd.) with a thickness of 12 μm and a surface roughness Rz of 2.0 μm was stacked on both sides. Next, vacuum pressing was performed under conditions of a pressure of 5 kg/ ^cm2 while heating from room temperature at a temperature increase rate of 3°C/min, and once the temperature reached 130°C, vacuum pressing was performed under conditions of a pressure of 40 kg/ ^cm2 while heating at a temperature increase rate of 3°C/min, and once the temperature reached 200°C, vacuum pressing was performed under conditions of a pressure of 40 kg/ ^cm2 for 60 minutes while maintaining the temperature at 200°C to produce a copper-clad laminate.

The copper foil on one side was removed by etching, and a heat resistance test was conducted. For the heat resistance test, test pieces were cut into 50 mm squares, then placed in a 105°C oven and dried for two hours, after which a pressure cooker test was conducted at two atmospheres for four hours. The heat resistance test was then conducted by dipping the test pieces in a solder bath at 260°C or 288°C for 20 seconds, this being repeated 30 times. The dip interval was 20 seconds.

In the heat resistance test, evaluation was carried out by visual observation based on the following criteria.
5: Laminate in which no blistering, peeling, or whitening was observed under the condition of 288°C. 3: Laminate in which no blistering, peeling, or whitening was observed under the condition of 260°C. (Note that under the condition of 288°C, any of blistering, peeling, or whitening occurred.)
1: Laminate that showed swelling, peeling, or whitening at 260°C

[Examples 1 to 18, Comparative Example 1, Reference Examples 1 to 3]
Glass yarns (average diameter of glass filaments: 5.0 μm, number of filaments: 100) having the composition shown in Table 1 were woven using an air jet loom to obtain glass cloths having a warp pick density of 65/25 mm, a weft pick density of 67/25 mm, and a thickness of 30 μm. Next, a desizing treatment was performed by heating, and a fiber-opening process was carried out using a high-pressure water spray. Subsequently, a surface treatment was performed using a silane coupling agent to produce glass cloths. Similarly, glass cloths were produced using E-glass as Reference Examples 1 to 3.

[Examples 19 to 29, Comparative Examples 2 and 3]
Glass yarns having the composition shown in Table 2 (average diameter of glass filaments: 5.0 μm, number of filaments: 200) were woven to obtain glass cloths having warp and weft pick densities of 52.5/25 mm and a thickness of 45 μm.

[Examples 30 to 40, Comparative Examples 4 and 5]
Glass yarns (average diameter of glass filaments: 6.0 μm, number of filaments: 200) having the composition shown in Table 2 were woven to obtain a glass cloth having a warp pick density of 59/25 mm, a weft pick density of 61/25 mm, and a thickness of 70 μm.

[Examples 41 to 48, Comparative Examples 6 and 7]
Glass yarns (average diameter of glass filaments: 7.0 μm, number of filaments: 200) having the composition shown in Table 2 were woven to obtain a glass cloth having a warp pick density of 60/25 mm, a weft pick density of 57/25 mm, and a thickness of 88 μm.

The present invention has industrial applicability as a method for manufacturing glass cloth for use in prepregs, etc.

Claims (24)

A method for producing a glass cloth, which is woven using glass yarns made of a plurality of glass filaments as warp yarns and weft yarns, comprising:
The density of the glass yarn to be the weft yarn is 2.2 g/cm ³ or more and less than 2.5 g/cm ³ ,
The yarn width dispersion coefficient indicating the yarn width variation of the glass yarn that becomes the weft yarn is 0.003 or more and 0.013 or less, and/or
The yarn width distribution variation coefficient A, which indicates the yarn width distribution variation of the glass yarn that becomes the weft yarn, is 0.0002 or more and 0.0015 or less.
Glass cloth manufacturing method.
Yarn width dispersion coefficient = Value obtained by dividing the standard deviation of the yarn width (yarn width standard deviation A) by the average diameter of the glass filaments. Yarn width distribution variation coefficient A = Value obtained by dividing the standard deviation of the yarn width standard deviation B (yarn width standard deviation B) for every 0.5 m length by the diameter of the glass filaments constituting the weft. The density of the glass yarn is more than 2.2 g/cm ³ and less than 2.5 g/cm ³ ;
The yarn width dispersion coefficient is more than 0.003 and less than 0.010,
And/or the yarn width distribution variation coefficient A is more than 0.0003 and less than 0.0012,
The method for producing the glass cloth according to claim 1. The yarn width dispersion coefficient is 0.005 or more and 0.013 or less,
The yarn width distribution variation coefficient A is 0.0006 or more and 0.0015 or less,
And/or , the yarn width distribution variation coefficient B, which indicates the yarn width distribution variation of the glass yarn that becomes the weft yarn, is 0.013 or more and 0.027 or less;
The method for producing the glass cloth according to claim 1.
Coefficient of variation of yarn width distribution B = A value obtained by dividing the yarn width distribution CV value, which is obtained by dividing the standard deviation of yarn width standard deviation B (yarn width distribution standard deviation) by the average value of yarn width standard deviation B when the standard deviation of yarn width (yarn width standard deviation B) is calculated for each 0.5 m length, by the diameter of the glass filaments constituting the weft yarn. The average number of twists per 25 mm of the weft is 0.50 or more and 1.20 or less,
The standard deviation indicating the variation in the number of twists is 0.10 or more and 0.20 or less.
The method for producing the glass cloth according to any one of claims 1 to 3. the weft is a glass yarn formed by bundling 80 to 120 glass filaments having an average diameter of more than 4.5 μm and not more than 5.5 μm, and the average yarn width of the glass yarn is 90 μm to 130 μm;
The method for producing the glass cloth according to any one of claims 1 to 4. the weft is a glass yarn formed by bundling 180 to 220 glass filaments having an average diameter of more than 4.5 μm and not more than 5.5 μm, and the average yarn width of the glass yarn is 120 μm to 175 μm;
The method for producing the glass cloth according to any one of claims 1 to 4. the weft is a glass yarn formed by bundling 180 to 220 glass filaments having an average diameter of more than 5.5 μm and not more than 6.5 μm, and the average yarn width of the glass yarn is 155 μm to 195 μm;
The method for producing the glass cloth according to any one of claims 1 to 4. the weft is a glass yarn formed by bundling 180 to 220 glass filaments having an average diameter of more than 6.5 μm and not more than 7.5 μm, and the average yarn width of the glass yarn is 180 μm to 220 μm;
The method for producing glass cloth according to any one of claims 1 to 4. The elastic modulus of the glass yarn is 50 to 70 GPa.
The method for producing glass cloth according to any one of claims 1 to 8. The elastic modulus of the glass yarn is 50 to 63 GPa.
The method for producing glass cloth according to claim 9. The glass cloth has a dielectric constant of 5.0 or less at a frequency of 1 GHz.
The method for producing glass cloth according to any one of claims 1 to 10. The glass yarn,
The Si content is 40 to 60 mass% in terms of SiO2,
The B content is 15 to 30 mass% in terms of B2O3.
The method for producing glass cloth according to any one of claims 1 to 11. The density is 2.2 g/cm or more and less than 2.5 g/cm,
The yarn width dispersion coefficient, which indicates the yarn width variation, is 0.003 or more and 0.013 or less, and/or
The yarn width distribution variation coefficient A, which indicates the distribution variation of the yarn width, is 0.0002 or more and 0.0015 or less;
Glass thread.
Yarn width dispersion coefficient = Value obtained by dividing the standard deviation of the yarn width (yarn width standard deviation A) by the average diameter of the glass filaments. Yarn width distribution variation coefficient A = Value obtained by dividing the standard deviation of the yarn width standard deviation B (yarn width standard deviation B) for every 0.5 m length by the diameter of the glass filaments constituting the weft. The density of the glass yarn is more than 2.2 g/cm ³ and less than 2.5 g/cm ³ ;
The yarn width dispersion coefficient is more than 0.003 and less than 0.010,
And/or the yarn width distribution variation coefficient A is more than 0.0003 and less than 0.0012,
The glass thread according to claim 13. The yarn width dispersion coefficient is 0.005 or more and 0.013 or less,
The yarn width distribution variation coefficient A is 0.0006 or more and 0.0015 or less,
And/or , the yarn width distribution variation coefficient B, which indicates the yarn width distribution variation of the glass yarn that becomes the weft yarn, is 0.013 or more and 0.027 or less;
The glass thread according to claim 13.
Coefficient of variation of yarn width distribution B = A value obtained by dividing the yarn width distribution CV value, which is obtained by dividing the standard deviation of yarn width standard deviation B (yarn width distribution standard deviation) by the average value of yarn width standard deviation B when the standard deviation of yarn width (yarn width standard deviation B) is calculated for each 0.5 m length, by the diameter of the glass filaments constituting the weft yarn. The average number of twists per 25 mm is 0.50 or more and 1.20 or less,
The standard deviation indicating the variation in the number of twists is 0.10 or more and 0.20 or less.
The glass fiber according to any one of claims 13 to 15. The glass yarn is a bundle of 80 to 120 glass filaments having an average diameter of more than 4.5 μm and not more than 5.5 μm, and the average yarn width is 90 μm to 130 μm.
The glass fiber according to any one of claims 13 to 16. The glass yarn is a bundle of 180 to 220 glass filaments having an average diameter of more than 4.5 μm and not more than 5.5 μm, and the average yarn width is 120 μm to 175 μm.
The glass fiber according to any one of claims 13 to 16. The glass yarn is a bundle of 180 to 220 glass filaments having an average diameter of more than 5.5 μm and not more than 6.5 μm, and the average yarn width is 155 μm to 195 μm.
The glass fiber according to any one of claims 13 to 16. The glass yarn is a bundle of 180 to 220 glass filaments having an average diameter of more than 6.5 μm and not more than 7.5 μm, and the average yarn width is 180 μm to 220 μm.
The glass fiber according to any one of claims 13 to 16. The elastic modulus is 50 to 70 GPa.
The glass filament according to any one of claims 13 to 20. The elastic modulus is 50 to 63 GPa.
The glass filament according to any one of claims 13 to 20. having a dielectric constant of 5.0 or less at a frequency of 1 GHz;
The glass filament according to any one of claims 13 to 22. The Si content is 40 to 60 mass% in terms of SiO2,
The B content is 15 to 30 mass% in terms of B2O3.
The glass filament according to any one of claims 13 to 23.