JP2021059811A - Glass cloth, prepreg, and printed wiring board - Google Patents

Abstract

To provide a low dielectric glass cloth in which a stitch deflection is suppressed while the thickness is kept equal to or lower than 16 μm and to provide a prepreg and a printed wiring board in which the difference in signal propagation speeds of a plurality of transmission lines is reduced.SOLUTION: A glass cloth includes a glass yarn comprising a plurality of glass filaments as warp and weft and has a thickness 8 μm or more and 16 μm or less. In the glass cloth, a presence ratio Y of the weft in a longitudinal direction calculated by a formula (1): Y=F/(25000/G)×100 ...(1) (in the formula, F is a yarn width (μm) of the weft, G is a weaving density (yarns/25 mm) of the weft) is 75% or more and 90% or less, a sum of the yarn width of the warp and the yarn width of the weft is 380 μm or more and 500 μm or less, and a density of the glass constituting the warp and the weft is 2.10 g/cm3 or more and 2.50 g/cm3 or less.SELECTED DRAWING: None

Description

The present invention relates to glass cloths, prepregs, and printed wiring boards.

In many printed wiring boards, a transmission line is formed by copper foil in an insulator layer composed of a glass cloth and a matrix resin composition.
The glass cloth used for the printed wiring board is formed by plain weaving glass threads in the warp and weft directions. Therefore, in the insulator layer composed of the glass cloth and the resin composition, the abundance ratio of the glass is high at the portion where the threads intersect, and the abundance ratio of the resin is high at the portion where the threads do not overlap or where there is no thread. Become.
Usually, there is a difference between the permittivity of the glass of the glass cloth and the permittivity of the resin composition. Therefore, it is known that there is a difference between the signal propagation speed in the transmission line passing through the portion where the abundance ratio of the glass is high and the signal propagation speed in the transmission line passing through the portion where the abundance ratio of the resin composition is high. Has been done. Therefore, in an electronic circuit in which a plurality of signals need to be synchronized, signal processing may be inconvenient when the arrival times of the signals are deviated.

With the development of the information and communication society in recent years, data communication and / or signal processing has come to be performed at high speed with a large capacity, and the speed of transmitted signals is increasing. The signal speed exceeds 10 Gbps, and the speed is increasing in the giga region such as 28 Gbps and 56 Gbps. As the speed of the signal increases, the influence of the above signal propagation speed difference increases and the signal propagation speed difference is reduced. The demand to do is increasing.
Here, when a pair of wirings are formed on the same insulator layer, the signal propagation speed transmitted through each wiring is the dielectric between the portion where the abundance ratio of glass is high and the portion where the abundance ratio of resin is high as described above. Since the rates are different, it is known that the positional relationship between the transmission line and the glass cloth is affected. Therefore, Patent Documents 1 to 3 propose a technique for reducing the change in propagation speed caused by the positional relationship between the glass cloth and the transmission line.
Specifically, Patent Document 1 discloses a technique for adjusting the line width to 75% to 95% of the spacing between the threads of the glass cloth.
Patent Document 2 discloses a technique for matching the spacing between glass threads and the spacing between signal lines.
Patent Document 3 discloses a technique for reducing the distance between glass threads and the distance between wiring widths to 50%.

As another attempt to reduce the difference in signal propagation speed, the dielectric constant of the glass cloth is reduced in order to reduce the difference in dielectric constant between the portion where the abundance ratio of glass is high and the portion where the abundance ratio of resin is high. , It is often proposed to reduce the difference from the dielectric constant of the resin. For example, the low-dielectric glass cloth disclosed in Patent Document 7 contains a _{large amount of B 2} O ₃ in the glass composition with respect to the E glass cloth generally used conventionally, and at the same time, other other materials such as _{SiO 2} A low dielectric constant is achieved by adjusting the blending amount of the components.

On the other hand, in order to increase the functionality, size and weight of digital devices in recent years, the printed wiring boards used are also required to be further reduced in size, thickness and density. As a method of miniaturization, thinning, and high density, the glass cloth used as a base material is thinned and the number of layers of the multilayer printed wiring board is increased. Here, the thickness of the glass cloth is required to be reduced to, for example, 16 μm or less in order to achieve high functionality, small size and light weight of the most advanced smartphones and wearable devices. Patent Documents 4 to 6 disclose a glass cloth having a thin thickness.

Japanese Unexamined Patent Publication No. 2014-130860 International Publication No. 2016/117320 International Publication No. 2017/159649 Japanese Patent No. 3756066 Japanese Patent No. 4446754 Japanese Patent No. 5936726 Japanese Unexamined Patent Publication No. 11-292567

The glass threads that make up the glass cloth have the property of causing bending. In particular, in a thin glass cloth, since a thinner glass thread is used as compared with a thick glass cloth, the thread widths of the warp and the weft are generally narrow, and the warp and the weft at the intersection of the warp and the weft The contact area is small. Therefore, the mutual binding force between the warp and the weft becomes weak, and for example, in the process of manufacturing the glass cloth or the process of manufacturing the prepreg using the glass cloth, the parallelism of the rolls carrying the glass cloth is slightly deviated. If there is, there is a difference in the tension acting on the warp in the width direction, that is, in the CD direction. As a result, while the warp and the weft originally intersect at a right angle, there is a problem that the weft is likely to be bent or bent.
Further, in the process of manufacturing the prepreg, the load acts unevenly on the glass cloth in the width direction in the process of passing through a narrow slit in order to control the amount of resin adhered when the resin is impregnated and coated. , Has a problem that bending is likely to occur.

The bending becomes more remarkable as the thickness of the glass cloth becomes thinner and the number of filaments of the threads constituting the glass cloth decreases.
In particular, by controlling the glass composition for lowering the dielectric, specifically _{adjusting the glass composition such as increasing the amount of B 2} O ₃ blended in the glass composition, the specific gravity of the glass constituting the glass thread becomes lighter, and the glass becomes glass. The rigidity of the thread tends to be weakened. The lower the density of the glass and the lower the rigidity of the glass, the more remarkable the bending becomes.
Therefore, as disclosed in Patent Documents 1 to 3, in the method of trying to reduce the difference in signal propagation speed by the transmission line in consideration of the arrangement of the glass threads, the positional relationship between the transmission line and the glass threads is caused by the bending of the glass threads. There is a problem that it is difficult to precisely control the signal propagation speed due to deviation and / or variation.

The glass cloth specifically disclosed in Examples 1 to 4 of Patent Document 4 has an average value of 3 to 5 mm and a thickness of 10 to 10 mm, which is measured at 10 points every 10 m of a 100 m long glass cloth. It is a 12 μm glass cloth. Patent Document 4 discloses that the average value of the amount of bending is small. However, since the amount of bending usually varies, if there is a part with large bending, a transmission line in which the signal propagation speed fluctuates greatly occurs, and there is a problem in signal processing in an electronic circuit that needs to synchronize a plurality of signals. Occurs.

The glass cloth specifically disclosed in Examples 1 to 5 of Patent Document 5 is a glass having an average value of 1 to 3 mm and a thickness of 17 to 21 μm measured every 10 m of a 100 m long glass cloth. It is a cross. In the glass cloth described in Patent Document 5, in order to improve the workability of small holes, adjacent threads are practically arranged without gaps. Therefore, it is necessary to use a glass thread having a large number of filaments, and it is difficult to reduce the thickness of the glass cloth.

The glass cloth specifically disclosed in the examples of Patent Document 6 is a thread lighter than a thin glass thread (ECBC3000, BC3750, BC5000, BC6000) ^{having a mass of 1.65 × 10 -6 kg / m or less for both the warp and the weft.} ) Is used, and the width of the warp and weft threads is also narrow. Therefore, the mutual binding force at the intersection of the warp and the weft is weak, and bending is likely to occur as in the conventional glass cloth.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a low-dielectric glass cloth in which bending is suppressed while maintaining a thickness of 16 μm or less.
Another object of the present invention is to provide a prepreg and a printed wiring board using the above glass cloth in which the difference in signal propagation speed of a plurality of transmission lines is reduced.

As a result of diligent studies to solve the above problems, the present inventors have found that a low-dielectric glass cloth satisfying that the abundance ratio of weft yarns in the longitudinal direction and the sum of the yarn widths of the warp yarns and the yarn widths of the weft yarns are within a specific range. It has been found that the occurrence of bending is suppressed while maintaining the thickness at 16 μm or less, and the present invention has been completed.
Further, the present inventors consider that the low-dielectric glass cloth, in which the abundance ratio of the weft in the longitudinal direction is in a specific range and the amount of bending of the weft and the interval of the weft satisfy a specific relationship, is a printed wiring board. When this is done, it is possible to increase the distance at which the change in the abundance of glass in the insulator layer through which the transmission line arranged parallel to the weft passes can be suppressed, so that the fluctuation in the signal propagation speed can be reduced. The present invention has been completed.

That is, the present invention is as follows.
[1]
A glass cloth having a thickness of 8 μm or more and 16 μm or less, which is composed of glass threads composed of a plurality of glass filaments as warp threads and weft threads.
Equation (1);
Y = F / (25000 / G) x 100 ... (1)
(In the formula, F is the yarn width (μm) of the weft, and G is the weaving density of the weft (book / 25 mm).)
The abundance ratio Y of the weft in the longitudinal direction, which is obtained in the above, is 75% or more and 90% or less.
The sum of the warp yarn width and the weft yarn width is 380 μm or more and 500 μm or less.
The density of the warp and the glass constituting the weft is 2.10 g / cm ³ or more and 2.50 g / cm ³ or less.
Glass cloth.
[2]
The sum of the elongation rate in the warp direction when a load of 5 N per 25 mm width is applied in the warp direction and the elongation rate in the weft direction generated when a load of 5 N per 25 mm width is applied in the weft direction is 0.50% or less. Is,
The glass cloth according to [1].
[3]
A glass cloth having a thickness of 8 μm or more and 16 μm or less, which is composed of glass threads composed of a plurality of glass filaments as warp threads and weft threads.
Equation (1);
Y = F / (25000 / G) x 100 ... (1)
(In the formula, F is the yarn width (μm) of the weft, and G is the weaving density of the weft (book / 25 mm).)
The abundance ratio Y of the weft in the longitudinal direction, which is obtained in the above, is 75% or more and 90% or less.
The amount of weft bending is less than or equal to the value obtained by dividing the value of 10 times the weft spacing (μm) by 500 mm.
The density of the warp and the glass constituting the weft is 2.10 g / cm ³ or more and 2.50 g / cm ³ or less.
Glass cloth.
[4]
The amount of weft bending is less than or equal to the value obtained by dividing the value of 5 times the weft spacing (μm) by 500 mm.
The glass cloth according to [3].
[5]
The amount of weft bending is less than or equal to the value obtained by dividing the value of 2.5 times the weft spacing (μm) by 500 mm.
The glass cloth according to [3].
[6]
The amount of weft bending is less than or equal to the value obtained by dividing the value of 1.0 times the weft spacing (μm) by 500 mm.
The glass cloth according to [3].
[7]
The sum of the warp yarn width and the weft yarn width is 380 μm or more and 500 μm or less.
The glass cloth according to any one of [3] to [6].
[8]
The sum of the elongation rate in the warp direction when a load of 5 N per 25 mm width is applied in the warp direction and the elongation rate in the weft direction generated when a load of 5 N per 25 mm width is applied in the weft direction is 0.50% or less. Is,
The glass cloth according to [7].
[9]
The ratio of the cross-sectional height in the warp direction to the cross-sectional height in the weft direction is 90% or more and 110% or less.
The glass cloth according to [1] or [2].
[10]
The sum of the warp yarn width and the weft yarn width is 380 μm or more and 500 μm or less.
The glass cloth according to any one of [3] to [6], wherein the ratio of the cross-sectional height in the warp direction to the cross-sectional height in the weft direction is 90% or more and 110% or less.
[11]
The permittivity of 10 GHz is 5 or less.
The glass cloth according to any one of [1] to [10].
[12]
The average mass per unit length of the warp is 1.40 × 10 ^-6 kg / m or more ^{and less than 1.60 × 10 -6} kg / m.
The average mass per unit length of the weft is 1.65 × 10 ^-6 kg / m ^{and more than 3.00 × 10 -6} kg / m.
The ratio of the average mass per unit length of the weft to the average mass per unit length of the warp (weft / warp ratio) is 1.20 or more and 1.50 or less.
The glass cloth according to any one of [1] to [11].
[13]
The average number of filaments of the warp and weft is substantially the same, and
The average filament diameter of the warp is 3.7 μm or more and 4.3 μm or less.
The average filament diameter of the weft is 4.2 μm or more and 5.3 μm or less.
The ratio of the average filament diameter of the weft to the average filament diameter of the warp (weft / warp ratio) is 1.07 or more and 1.40 or less.
The glass cloth according to any one of [1] to [12].
[14]
The average filament diameters of the warp and weft are substantially the same, and
The average number of warp filaments is 45 or more and 70 or less.
The average number of weft filaments is 55 or more and 80 or less.
The ratio of the average number of filaments of the weft to the average number of filaments of the warp (weft / warp ratio) is larger than 1.25 and 1.50 or less.
The glass cloth according to any one of [1] to [12].
[15]
The glass cloth according to any one of [1] to [14] and
With matrix resin,
Prepreg.
[16]
The difference between the dielectric constant of the glass constituting the glass cloth at 10 GHz and the dielectric constant of the cured product of the matrix resin at 10 GHz is 3 or less.
The prepreg according to [15].
[17]
The difference between the dielectric constant of the glass constituting the glass cloth at 10 GHz and the dielectric constant of the cured product of the matrix resin at 10 GHz is 2 or less.
The prepreg according to [15].
[18]
The difference between the dielectric constant of the glass constituting the glass cloth at 10 GHz and the dielectric constant of the cured product of the matrix resin at 10 GHz is 1 or less.
The prepreg according to [15].
[19]
Having the prepreg according to any one of [15] to [18].
Printed wiring board.

According to the present invention, it is possible to provide a low-dielectric glass cloth in which bending is suppressed while maintaining a thickness of 16 μm or less. When the glass cloth of the present invention is used as a printed wiring board, the deviation of the positional relationship between the glass thread and the transmission line can be reduced. Further, according to the present invention, it is possible to provide a prepreg and a printed wiring board having a small difference in signal propagation speed between a plurality of transmission lines.

It is a figure which shows the load-elongation curve which is the result of the elongation amount measurement of the glass cloth of the glass cloth G (1017 style of L glass) obtained in the comparative example 1. FIG. It is a figure which shows the load-elongation curve of the glass cloth C obtained in Example 3. FIG. It is a schematic diagram which shows the thread width of the weft and the interval of the weft in the glass cloth of this embodiment. It is a schematic diagram which shows one form of the glass cloth of this embodiment, and is the figure which shows one form of the weft thread. It is a schematic diagram which shows one form of the glass cloth of this embodiment, and is the figure which shows one form of the weft thread. It is a schematic diagram which shows one form of the glass cloth of this embodiment, and is the figure which shows one form of the weft thread.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited thereto, and various modifications can be made without departing from the gist thereof. Is.
The permittivity in the present embodiment indicates a value measured in the 10 GHz band by the cavity resonator perturbation method (perturbation method cavity resonator / manufactured by Kanto Denshi Applied Development Co., Ltd.).

<Glass cloth>
(thickness)
The glass cloth of the present embodiment is a glass cloth having a thickness of 8 μm or more and 16 μm or less, which is composed of glass threads composed of a plurality of glass filaments as warp threads and weft threads.
When the thickness is 16 μm or less, the number of layers of the multilayer printed wiring board can be increased, and the density of the transmission line can be increased while maintaining the thickness of the multilayer printed wiring board. It is preferable that the thickness of the glass cloth is thin, but as the thickness becomes thin, it is necessary to make the glass thread to be a thin thread, and the strength of the glass cloth is lowered and the bending of the eyes is likely to occur. When the thickness is 8 μm or more, the strength of the glass cloth can be maintained and the occurrence of bending can be suppressed.

(Weft occupancy)
In the glass cloth of the present embodiment, the abundance ratio of weft threads in the longitudinal direction is 75% or more and 90% or less. The abundance ratio of the weft yarns in the longitudinal direction is also called the weft yarn occupancy ratio, which is obtained from the equation (1) and is a value Y obtained by dividing the yarn width of the weft yarns by the weft yarn spacing.
Y = F / (25000 / G) x 100 ... (1)
(In the formula, F is the yarn width (μm) of the weft, and G is the weaving density of the weft (book / 25 mm).)
The weft yarn width is an average value obtained by observing a glass cloth sample having a size of 100 mm × 100 mm from the surface with a microscope, determining the widths of all the weft yarns, and dividing the total by the total number of the weft yarns. At this time, if the yarn width of the weft fluctuates within the sample, the width of the portion having the widest width is defined as the yarn width of the weft.

One of the present embodiments is a glass cloth having a thickness of 8 μm or more and 16 μm or less, which is composed of glass threads composed of a plurality of glass filaments as warp threads and weft threads.
Equation (1);
Y = F / (25000 / G) x 100 ... (1)
(In the formula, F is the yarn width (μm) of the weft, and G is the weaving density of the weft (book / 25 mm).)
The abundance ratio Y of the weft in the longitudinal direction, which is obtained in the above, is 75% or more and 90% or less.
The sum of the warp yarn width and the weft yarn width is 380 μm or more and 500 μm or less.
The density of the warp and the glass constituting the weft is 2.10 g / cm ³ or more and 2.50 g / cm ³ or less.
It is a glass cloth.
The glass cloth is also referred to as a glass cloth P.

(Sum of warp yarn width and weft yarn width)
The sum of the warp yarn width and the weft yarn width in the glass cloth P of the present embodiment is 380 μm or more and 500 μm or less, preferably 380 μm or more and 480 μm or less, and more preferably 400 μm or more and 480 μm or less.
When the sum of the yarn width of the warp and the yarn width of the weft is 380 μm or more, the contact area between the warp and the weft becomes large at the intersection of the warp and the weft. Therefore, as the friction area between the warp and the weft increases, the mutual binding force becomes stronger and the bending of the eyes is suppressed.
When the sum of the warp yarn width and the weft yarn width is 500 μm or less, the mutual binding force between the warp yarn and the weft yarn does not become too strong at the intersection of the warp yarn and the weft yarn, and the warp yarn and the weft yarn become appropriate. There is room for movement. Therefore, in a thin glass cloth having a thickness of 16 μm or less, when stress is applied, the warp and weft move from the intersection point to alleviate the stress, and the occurrence and breakage of wrinkles are suppressed.

Further, the line width generally used for a multilayer wiring board or the like is about 0.1 mm. Therefore, in a glass cloth having a weft occupancy of 75% or more and 90% or less, in order to suppress a change in the abundance of glass in the insulator layer through which a transmission line arranged parallel to the weft passes, the weft The yarn width of the warp yarn is preferably 300 μm or less, and the sum of the yarn width of the warp yarn and the yarn width of the weft yarn is preferably 500 μm or less.
When the sum of the yarn width of the warp yarn and the yarn width of the weft yarn is 380 μm or more and 500 μm or less, a glass cloth having no wrinkles or bending and excellent handleability can be obtained.

(Sum of growth rate)
The glass cloth of the present embodiment has an elongation rate in the warp direction generated when a load of 5 N per 25 mm in width is applied in the warp direction and an elongation rate in the weft direction generated when a load of 5 N per 25 mm in width is applied in the weft direction. The sum is preferably 0.50% or less.
The sum of the elongation rates is more preferably 0.48 or less, and the still more preferable range is 0.45 or less.
Here, the elongation rate of the glass cloth is a value obtained as follows.

The amount of elongation when tension is applied to the glass cloth in the warp or weft direction is measured by applying the method described in JIS R3420, General Test Method for Glass Test, 7.4 Tensile Strength mutatis mutandis. In the method specified by JIS, a test piece having a width of about 30 mm and a length of about 250 mm is taken from the warp and weft directions of the woven fabric, and the threads at both ends of the test piece are loosened to have a width of about 25 mm and a grip of about 150 mm. Attach it to the grip with a sufficient interval, pull it at a pulling speed of about 200 mm / min, and determine the load at the time of breakage. In the present embodiment, the tensile test is performed under the same conditions as the method specified in JIS except that the tensile speed is set to about 10 mm / min and the width of the test piece to be collected is set to about 35 mm in order to improve the measurement accuracy. Then, the amount of displacement when a load of 5 N is applied per 25 mm width of the glass cloth is obtained, and the value obtained by using the following formula (2) is defined as the “elongation rate of the glass cloth”.
Elongation rate = {(interval with load-interval with no load) / interval with no load} x 100 (2)

As a result of examining the relationship between the woven structure of the glass cloth and the susceptibility to bending, the present inventors have found that the "elongation amount of the initial deformation region" and the susceptibility to bending when tensile tension is applied. It was found that there is a correlation between the two, and that when the "elongation amount of the initial deformation region" is made smaller than the specific range, the occurrence of bending of the eyes is remarkably suppressed in the normal handling of the glass cloth.

FIG. 1 shows the 1017 style of L glass (glass cloth G obtained in Comparative Example 1), which is often used for printed wiring boards as a conventional thin glass cloth, that is, the amount of elongation of a glass cloth having a thickness of 14 μm. The load-elongation curve, which is the measurement result, is shown.
The load-elongation curve of L-glass 1017 style glass cloth is characterized by a larger elongation of the weft than the warp, with a low slope up to around 0-0.2% displacement, followed by about 0.4%. It gradually increases up to, and after 0.4%, it swings up and becomes a constant inclination.
In the region where the slope is low, there is a gap between the weft and the warp at the intersection of the weft and the warp, and the weft and the warp are not in sufficient contact with each other. It is reflected that it is pulled greatly until it becomes. The region where the next slope gradually increases is the region where the crimping of the weft is progressing while the crimp of the warp is increased. The region where the weft is swung up and the inclination becomes constant is the region where the weft itself is stretched and elastically deformed.

As described above, the weft of the 1017 cloth of L glass has an initial deformation region before elastic deformation in a very weak tensile tension range of up to 5N per 25 mm, and the amount of elongation in the initial deformation region is large. ..
Compared with the conventional glass cloth such as the 1017 style of L glass, the glass cloth of the present embodiment has a smaller amount of elongation in the initial deformation region. FIG. 2 shows the load-elongation curve of the glass cloth C obtained in Example 3. The glass cloth C of the present invention has a small elongation amount up to 5N even in the weft direction, and the elongation amount in the initial deformation region is suppressed to be small. This suggests that the warp and weft have a strong mutual binding force at the intersection of the warp and the weft.
A thin glass cloth, particularly a glass cloth having a thickness of 16 μm or less, usually uses a thin glass thread having a filament diameter of 4.0 μm or less and a number of filaments of 50 or less in order to express the thickness. , The mutual binding force at the intersection of the warp and the weft is weak and it is easy to bend the eyes, but the sum of the elongation rates in the glass cloth is 0.50% or less, so that the mutual binding at the intersection of the warp and the weft is restrained. It tends to be a glass cloth with increased force and less bending of the eyes.

As described above, the sum of the elongation rate in the weft direction generated when a load of 5 N per 25 mm width is applied in the weft direction and the elongation rate in the warp direction generated when a load of 5 N per 25 mm width is applied in the warp direction is 0. By setting the content to 50% or less, the mutual binding force at the intersection of the warp and the weft becomes high, and the glass cloth can be made into a glass cloth in which bending is unlikely to occur.
On the other hand, the lower limit of the sum of the elongation rates is preferably 0.30% or more, more preferably 0.33% or more, still more preferably 0.35% or more. When the sum of the elongation rates is 0.30% or more, the glass cloth having a woven structure is reversible in the strain due to the application applied to the glass cloth, and the structure of the glass cloth is reversible based on the intersection point of the warp and the weft. It is alleviated by changing to, and tends to suppress the occurrence and breakage of wrinkles.
When the sum of the elongation rates is in the range of 0.30% or more and 0.50% or less, a glass cloth having no wrinkles and bending and excellent handleability tends to be obtained.

Further, one of the present embodiments is a glass cloth having a thickness of 8 μm or more and 16 μm or less, which is composed of glass threads composed of a plurality of glass filaments as warp threads and weft threads.
Equation (1);
Y = F / (25000 / G) x 100 ... (1)
(In the formula, F is the yarn width (μm) of the weft, and G is the weaving density of the weft (book / 25 mm).)
The abundance ratio Y of the weft in the longitudinal direction, which is obtained in the above, is 75% or more and 90% or less.
The amount of weft bending is less than or equal to the value obtained by dividing the value of 10 times the weft spacing by 500 mm.
The density of the warp and the glass constituting the weft is 2.10 g / cm ³ or more and 2.50 g / cm ³ or less.
It is a glass cloth.
The glass cloth is also referred to as glass cloth Q.

The amount of weft bending is preferably less than or equal to the value obtained by dividing the value of 5 times the weft spacing by 500 mm, and more preferably less than or equal to the value obtained by dividing the value of 2.5 times the weft spacing by 500 mm. It is more preferable that the value is 1.0 times the weft spacing divided by 500 mm or less. Here, the unit of "weft spacing" in "a value obtained by dividing a value of 10 times, 5 times, 2.5 times, or 1.0 times the weft spacing by 500 mm" is μm.

The weft occupancy rate and the amount of bending are preferably 77% or more and 87% or less, and the amount of bending is preferably equal to or less than a value obtained by dividing 5 times the weft spacing by 500 mm, and the occupancy rate is 79. % Or more and 85% or less, the amount of bending is more preferably less than or equal to the value obtained by dividing the value 2.5 times the weft spacing by 500 mm, the occupancy rate is 80% or more and 84% or less, and the amount of bending is 1. It is more preferable that the value is 0 times the value divided by 500 mm or less.
The weft spacing in the present embodiment is the spacing between the wefts constituting the glass cloth, and the weft spacing in the present specification includes the yarn width itself. Here, FIG. 3 is a schematic view showing the spacing between the weft threads in the glass cloth. a is the yarn width and b is the weft spacing.
Further, the weft spacing is obtained from the weft density G (book / 25 mm), and specifically, the weft spacing is calculated from 25 / G (mm) when the unit of the spacing is mm. When the unit of the interval is μm, it can be calculated from 25000 / G (μm).

The weft occupancy rate is 75% or more and 90%, and the amount of bending is equal to or less than the value obtained by dividing the value of 10 times the weft spacing by 500 mm, so that the printed wiring plate is parallel to the weft. Since the change in the abundance rate of the glass in the insulator layer through which the transmission lines arranged so as to pass is suppressed to a small extent, the fluctuation of the signal propagation speed tends to be reduced.

Here, when the weft occupancy rate is 75% or more and 90%, if the amount of bending is less than or equal to the value obtained by dividing the value of 10 times the weft spacing by 500 mm, the transmission arranged so as to be parallel to the weft. Keep the deviation between the line and the weft small, specifically, keep the amount of deviation from the weft of the transmission line within a range smaller than 0.5 times the spacing between the wefts, and make the abundance ratio of glass around the transmission line equal. The transmission line that can be maintained at can be lengthened.
The amount of bending is preferably small, and ideally the amount of bending is 0, but it may be more than 0.

The "bending amount" in the present specification means the one having the maximum value among the _Zn (Z ₀ , Z ₁ , and Z _{2) defined by the following formula (I).}

Z _N = | (Y _{N + 1} −Y _N ) / (X _{N + 1} −X _N ) | (I)
(In the equation, N is 0 to 2, and _{if the value of X N + 1} −X _N is 0, then Z _N is assumed to be 0).

In the formula, X _{0 to} X ₃ and Y _{0 to Y 3} are combinations of (X ₀ , Y ₀ ), (X ₁ , Y ₁ ), (X ₂ , Y ₂ ), and (X ₃ , Y ₃ ). It is expressed by and is defined as shown below.
A glass cloth or prepreg composed of a plurality of warp threads and a plurality of weft threads, or a printed wiring board is used as a sample to be tested, the warp direction of the sample to be tested is the Y direction, and the direction perpendicular to the Y direction is the X direction. Of the first and second warp threads at both ends of the sample to be tested, with respect to the weft threads extending from the first warp threads to the second warp threads, the contact point between the first warp threads and the above weft threads is the origin (0,0). That is, the Y-axis and the X-axis to be _{(X 0} , Y _{0) are defined.} Further, the contact point between the second warp and the weft is set as the end point (X ₃ , Y ₃ ), and one of the points having the maximum value and the minimum value with respect to the coordinate Y of the weft on the X axis and the Y axis is (X). _{Let 1} , Y ₁ ) and the other side be (X ₂ , Y ₂ ). In this case, (X ₀ , Y ₀ ), (X ₁ , Y ₁ ), (X ₂ , Y ₂ ) on the above weft. , And (X ₃ , Y ₃ ) are arranged in this order.

Hereinafter, with reference to FIGS. 4 to 6, the calculation methods of _{Z 0} , Z ₁ , and Z _{2 are exemplified.} 4 to 6 are schematic views showing one form of weft. The form of the weft in the present embodiment is not limited to the form of the weft of FIGS. 4 to 6.

In FIG. 4, the origin (X ₀ , Y ₀ ), the point where the maximum value of Y is taken (X ₁ , Y ₁ ), the point where the minimum value of Y is taken (X ₂ , Y ₂ ), and the end point (X 2, Y 2) are on the weft. X ₃ , Y ₃ ) are arranged in this order. Z ₀ is calculated by substituting two adjacent points (X ₀ , Y ₀ ) and (X ₁ , Y ₁ ) into the above equation (I), and Z ₁ is two adjacent points (X _1). , Y ₁ ) and (X ₂ , Y ₂ ) are calculated by substituting the above equation (I), and Z ₂ is two adjacent points (X ₂ , Y ₂ ) and (X ₃ , Y _3). ) Is substituted into the above equation (I).

In FIG. 5, on the weft, the origin (X ₀ , Y ₀ ), the point having the maximum value of _{Y (X 1} , Y ₁ ), the point having the minimum value of _{Y (X 2} , Y ₂ ), and the end point (X 2, Y 2). X ₃ , Y ₃ ) are arranged in this order, where (X ₂ , Y ₂ ) and (X ₃ , Y ₃ ) indicate the same coordinates. Z ₀ , Z ₁ , and Z ₂ can be calculated in the same manner as described in FIG. 4 above.
Since (X ₂ , Y ₂ ) and (X ₃ , Y ₃ ) indicate the same coordinates, Z ₂ takes a value of 0 with respect to the above equation (I).

In FIG. 6, the origin (X ₀ , Y ₀ ), the point where the maximum value of Y is taken (X ₁ , Y ₁ ), the point where the minimum value of Y is taken (X ₂ , Y ₂ ), and the end point (X 2, Y 2) are on the weft. X ₃ , Y ₃ ) are arranged in this order, where (X ₀ , Y ₀ ) and (X ₁ , Y ₁ ) indicate the same coordinates, and (X ₂ , Y ₂ ) and (X). ₃ , Y ₃ ) indicate the same coordinates, and Z ₀ , Z ₁ , and Z ₂ can be calculated in the same manner as in FIG. 4 above.
Since (X ₀ , Y ₀ ) and (X ₁ , Y ₁ ) indicate the same coordinates, Z ₀ takes a value of 0 with respect to the above equation (I), and Z ₂ is also 0. Takes the value of.

While the amount of bending described in the examples of Patent Documents 4 and 5 is an average value measured at several points, in the present embodiment, the maximum value is defined as the amount of bending in the present embodiment. This is because in an electronic circuit in which it is necessary to synchronize a plurality of signals, even one deviation in the arrival time of the signals may lead to inconvenience in signal processing.

The sum of the warp yarn width and the weft yarn width in the glass cloth Q of the present embodiment is preferably 380 μm or more and 500 μm or less, preferably 380 μm or more and 480 μm or less, and more preferably 400 μm or more and 480 μm or less. ..
When the sum of the yarn width of the warp and the yarn width of the weft is 380 μm or more, the contact area between the warp and the weft becomes large at the intersection of the warp and the weft, the mutual binding force becomes strong, and the stitch bends. Is suppressed.
When the sum of the warp yarn width and the weft yarn width is 500 μm or less, the mutual binding force between the warp yarn and the weft yarn does not become too strong at the intersection of the warp yarn and the weft yarn, and the warp yarn and the weft yarn become appropriate. Since there is room for movement, in a thin glass cloth having a thickness of 16 μm or less, when stress is applied, the warp and weft move from the intersection point as a base point, so that the stress is relaxed and the occurrence and breakage of wrinkles are suppressed.

Further, since the line width generally used for a multilayer wiring board or the like is about 0.1 mm, a transmission line arranged so as to be parallel to the weft in a glass cloth having a weft occupancy of 75% or more and 90% or less. Since the yarn width of the weft yarn is preferably 300 μm or less in order to suppress the change in the abundance rate of the glass of the insulator layer through which the warp yarn passes, the sum of the yarn width of the warp yarn and the yarn width of the weft yarn is 500 μm or less. Is preferable.
When the sum of the yarn width of the warp yarn and the yarn width of the weft yarn is 380 μm or more and 500 μm or less, a glass cloth having no wrinkles or bending and excellent handleability can be obtained.

In the glass cloth Q of the present embodiment, the sum of the warp yarn width and the weft yarn width is 380 μm or more and 500 μm or less, and the elongation rate in the warp yarn direction generated when a load of 5 N per 25 mm width is applied in the warp yarn direction. The sum with the elongation rate in the weft direction generated when a load of 5 N per 25 mm in width is applied in the weft direction is preferably 0.50% or less.

(Ratio of warp and weft at cross-sectional height)
In the glass cloth of the present embodiment, the ratio of the cross-sectional height in the warp direction to the cross-sectional height in the weft direction is preferably 90% or more and 110% or less.
The ratio of the cross-sectional height in the warp direction to the cross-sectional height in the weft direction is more preferably 92% or more and 108% or less, and further preferably 95% or more and 105% or less.
The cross-sectional height in the warp direction is the cross-sectional height of the glass cloth when the cross-sectional image of the glass cloth is observed so that four or more adjacent warp threads are continuously inserted. Similarly, the cross-sectional height in the weft direction is the cross-sectional height of the glass cloth when observing the cross-sectional image of the glass cloth so that four or more adjacent weft threads are continuously inserted.
When the ratio of the cross-sectional height in the warp direction to the cross-sectional height in the weft direction is 90% or more and 110% or less, the glass and resin in the Z-axis direction, that is, in the thickness direction, at the portion where the glass thread in the insulator layer exists. Since the uniformity of presence with the composition is improved, the fluctuation of the signal propagation speed tends to be small.

In the glass cloth Q of the present embodiment, the sum of the warp yarn width and the weft yarn width is 380 μm or more and 500 μm or less, and the ratio of the cross-sectional height in the warp direction to the cross-sectional height in the weft direction is 90% or more and 110. % Or less is preferable.

(Glass density)
Density of the glass constituting the glass cloth of the present embodiment is 2.10 g / cm ³ or more 2.50 g / cm ³ or less, preferably 2.15 g / cm ³ or more 2.45 g / cm ³ or less, more preferably is 2.20 g / cm ³ or more 2.40 g / cm ³ or less.
The specific gravity of E glass cloth, which has been generally used conventionally, is 2.54 g / cm ³ . In order to reduce the dielectric constant and dielectric loss tangent of glass cloth, it is necessary to change the composition of glass, and low-dielectric glass is a substance with a relatively small specific gravity such as _{B 2} O _{3 as compared with E glass cloth.} Is mixed in a large amount. Therefore, the density of the glass is reduced, and the rigidity of the glass thread is also reduced. Further, when a glass thread having a low density and a low rigidity is used, distortion such as bending of the eyes is likely to occur in the glass cloth.
When the density is 2.10 g / cm ³ or more, it is possible to effectively suppress the occurrence of bending in the yarn width structure of the present embodiment.
By setting the density of the glass to 2.50 g / cm ³ or less, the low dielectric property is excellent.

As described above, the density of glass is ^{2.10 g / cm 3} by blending a large amount of substances having a relatively small specific gravity such as _{B 2} O _{3, that is, by controlling the composition of the components constituting the glass.} It is controlled in the range of 2.50 g / cm ^{3 or less.}
The composition of the glass can be adjusted as appropriate, and may have, for example, the following composition.
The Si content of the glass cloth is preferably 40 to 60% by mass, more preferably 45 to 55% by mass, still more preferably 47 to 53% by mass, and 48 to 52% by mass in terms of _{SiO 2.} is there.
The B content of the glass cloth is preferably 15 to 30% by mass, more preferably 17 to 28% by mass, still more preferably 20 to 27% by mass, and even more preferably 20 to 27% by mass in terms of _{B 2} O _3. It is 21 to 25% by mass, and even more preferably 21 to 24% by mass.
The Al content of the glass cloth is preferably 10 to 20% by mass, more preferably 11 to 18% by mass, and further preferably 12 to 17% by mass in terms of _{Al 2} O _3.
The Ca content of the glass cloth is preferably 4 to 12% by mass, preferably 5 to 10% by mass, and more preferably 6 to 9% by mass in terms of CaO.
As another composition, for example, Mg, P, Na, K, Ti, Zn and the like may be contained.
The composition of the glass can be adjusted according to the amount of the raw material used for producing the glass filament.

(Mass of glass thread)
In the glass cloth of the present embodiment, the mass per unit length of the warp is 1.40 × 10 ^-6 kg / m or more ^{and less than 1.60 × 10 -6} kg / m, and the mass per unit length of the weft is The mass is 1.65 × 10 ^-6 kg / m ^{and more than 3.00 × 10 -6} kg / m, and the average mass per unit length of the weft is relative to the average mass per unit length of the warp. The ratio, that is, the ratio of the weft to the warp (weft / warp ratio) is preferably 1.20 or more and 1.50 or less.
Mass per unit length of the warp, the mass per unit length of the weft yarn, and the ratio of the average mass of the above, preferably each warp; 1.40 × 10 ^-6 kg / m or more 1.57 × 10 ^{- Less than 6} kg / m, weft; 1.65 × 10 ^-6 kg / m or more 2.80 × 10 ^-6 kg / m or less, weft / warp ratio: 1.17 or more and 1.79 or less, even more preferable. Warp; 1.40 x 10 ^-6 kg / m or more and ^{less than 1.55 x 10 -6} kg / m, weft: 1.70 x 10 ^-6 kg / m or more and 2.50 x 10 ^-6 kg / m m or less, weft / warp ratio; 1.21 or more and 1.62 or less.

In the manufacturing process of the glass cloth, a physical load is applied in a step of adjusting the coating amount of the silane agent after impregnating the silane treatment agent or a fiber opening processing step. Further, even when the prepreg is applied using the glass cloth, a physical load is applied to the glass cloth in a step of adjusting the amount of the resin varnish and drying after the impregnation coating of the resin varnish. In order to stably and continuously convey the glass cloth without cutting it in the above step, it is preferable that the warp yarn has a certain strength or more, and for that purpose, ^{a glass yarn of 1.40 × 10 -6} kg / m or more is used. Is preferable. ^{On the other hand, by using a glass yarn having an average mass of less than 1.60 × 10 -6} kg / m per unit length as the warp, the thickness can be maintained at 16 μm or less, and the weaving density can be set to, for example, 90 or more. The number can be increased, and the occurrence of pinholes tends to be suppressed.

By using a glass yarn having an average mass of more than 1.65 × 10 ^-6 kg / m per unit length as the weft, the rigidity of the weft tends to be increased and it tends to be easy to reduce the bending of the weft. A large mass per unit length of the glass yarn used for the weft is preferable because it has excellent rigidity. However, in order to keep the thickness of the glass cloth to 16 μm or less, the average mass per unit length is 3.00 × 10. ^-6 kg / m or less is preferable.

Further, when the mass ratio of the weft to the warp is 1.20 or more, the difference between the rigidity of the weft and the rigidity of the warp becomes large. Therefore, even if the thread used for the weft is thin and has no rigidity, the weft is used in the weaving process. The swell can be suppressed to a small size, and the warp threads intersecting the weft threads can be kept in close contact with each other with few gaps. Further, the swelling state of the weft thread inserted without binding force fluctuates according to the variation in the line tension acting on the warp thread in the weaving process, but the difference in rigidity between the warp thread and the weft thread becomes large, so that the weft thread is used. Fluctuations in the swell structure can be suppressed to a small extent. Therefore, the fluctuation of the "elongation amount in the initial deformation region" when the tensile tension acts is small, and there is a tendency to stably obtain a glass cloth having a small amount of bending.
Further, as a result of the swell of the weft becoming smaller and the swell of the warp becoming larger, the crimp amplitude of the weft and the warp becomes closer, and the crimp amplitude of the warp is 50% or more and 80% or less of the glass cloth thickness, and the crimp of the weft is increased. There is a tendency that the amplitude can be adjusted in the range of 60% or more and 90% or less of the glass cloth thickness.

On the other hand, when the mass ratio of the weft to the warp is 1.50 or less, it is possible to prevent the difference in rigidity between the warp and the weft from becoming extremely large, and the swell structure of the weft is appropriately preserved with the warp. Since there is no significant difference in the swell structure from the weft, there is a tendency to prevent anisotropy and warpage of dimensional stability when the printed wiring board is formed due to the difference in rigidity between the warp and the weft.
The mass per unit length of the warp, the mass per unit length of the weft, and the ratio of the mass of the weft to the warp are within the above range, so that the anisotropy of dimensional stability when used as a printed wiring board and While preventing warpage, there is a tendency that the "elongation amount in the initial deformation region" when tensile tension acts can be reduced to a specific range.

(Average filament diameter, average number of filaments)
In the glass cloth of the present embodiment, the average number of filaments of the warp and the weft is substantially the same, the average filament diameter of the warp is 3.7 μm or more and 4.3 μm or less, and the average filament diameter of the weft is It is preferably 4.2 μm or more and 5.3 μm or less, and the ratio of the average filament diameter of the weft to the average filament diameter of the warp (weft / warp ratio) is 1.07 or more and 1.30 or less.

By keeping the average number of filaments and the average filament diameter of the warp and weft in the above range, the thickness of the glass cloth is maintained at 16 μm or less, and the anisotropy and warpage of the dimensional stability of the printed wiring board are prevented. It tends to increase the rigidity in the weft direction and suppress the bending of the eyes.
The average filament diameter of the warp and weft, and the range of the weft / warp ratio of the average filament diameter are more preferably 3.8 μm or more and 4.2 μm or less, weft; 4.3 μm or more and 5.2 μm or less, average filament, respectively. Weft / warp ratio of diameter: 1.08 or more and 1.25 or less, more preferably warp: 3.9 μm or more and 4.1 μm or less, weft: 4.4 μm or more and 5.1 μm or less, weft with average filament diameter. / Warp ratio: 1.09 or more and 1.20 or less.

The fact that the average number of filaments of the warp and the weft is substantially the same means that the ratio of the number of filaments of the warp to the number of filaments of the weft (weft / warp ratio) is in the range of 0.94 or more and 1.06 or less. Point to. When the weft / warp ratio of the average number of filaments is 0.94 or more and 1.06 or less, the effect of increasing the filament diameter of the weft, that is, the rigidity in the weft direction tends to be excellent.
Further, in the present embodiment, when the average number of filaments of the warp and the weft is substantially the same, the number of filaments of the warp and the weft is preferably 60 or less. When the number of filaments is 60 or less, the filaments are easily diffused by physical processing in the glass cloth manufacturing process, and the filament distribution in the Z direction of the glass yarn bundle can be reduced, so that the thickness of the glass cloth can be easily reduced. In order to reduce the thickness of the glass cloth, it is preferable that the number of filaments is small, but from the viewpoint of the strength and handleability of the glass cloth, when the average number of filaments of the warp and weft is substantially the same, the lower limit of the number of filaments is , More preferably 44 or more, more preferably 46 or more, still more preferably 48 or more.

In the glass cloth of the present embodiment, the average filament diameters of the warp and the weft are substantially the same, the average number of warp filaments is 43 or more and 70 or less, and the average number of weft filaments is 55. It is preferable that the number is 80 or more and the ratio of the average number of filaments of the weft to the average number of filaments of the warp (weft / warp ratio) is larger than 1.25 and 1.50 or less.
By keeping the average number of filaments of the warp and weft and the average filament diameter within the above range, the thickness of the glass cloth is maintained at 16 μm or less, and the anisotropy and warpage of the dimensional stability of the printed wiring board are prevented. , The rigidity in the weft direction is increased, and the bending of the eyes tends to be suppressed.
The average number of filaments of the warp and the weft, and the range of the ratio (weft / warp ratio) are more preferably 43 or more and 65 or less for the warp, 57 or more and 75 or less for the weft, and the average number of wefts / Warp ratio: 1.27 or more and 1.45 or less, more preferably warp; 45 or more and 60 or less, weft: 60 or more and 70 or less, average filament weft / warp ratio: 1.30 or more 1 It is .40 or less.

The fact that the average filament diameters of the warp and the weft are substantially the same means that the ratio of the filament diameter of the warp to the filament diameter of the weft (weft / warp ratio) is in the range of 0.95 or more and 1.05 or less. .. When the weft / warp ratio of the average filament diameter is in the range of 0.95 or more and 1.05 or less, the effect of increasing the number of filaments of the weft, that is, the rigidity in the weft direction tends to be excellent.
Further, in the present embodiment, when the average filament diameters of the warp and the weft are substantially the same, the filament diameter of the warp and the weft is preferably 3.8 μm or more. When the average filament diameter of the warp and weft is 3.8 μm or more, the rigidity of the glass cloth tends to be increased. It is preferable that the filament diameter is large in order to increase the rigidity of the glass cloth, but from the viewpoint of the thickness of the glass cloth, when the average filament diameters of the warp and weft are substantially the same, the average filament diameter of the warp and weft The upper limit is preferably 4.4 μm or less, more preferably 4.3 μm or less, still more preferably 4.2 μm or less.

The glass thread constituting the glass cloth of the present embodiment is not particularly limited, and low dielectric constant glass such as D glass, L glass, NE glass, and silica glass (Q glass) may be used.
By using glass fiber yarn having a dielectric constant close to that of the impregnated resin as the warp and weft, the non-uniformity of the dielectric constant tends to be further reduced. The dielectric constant of the glass cloth is preferably 5.0 or less, more preferably 4.5 or less, from the viewpoint of reducing the non-uniformity of the dielectric constant.

The woven structure of the glass cloth is not particularly limited, and examples thereof include woven structures such as plain weave, Nanako weave, satin weave, and twill weave. Further, a mixed weave structure using different types of glass threads may be used. Of these, a plain weave structure is preferable.

Further, the glass cloth of the laminated board used for a printed wiring board or the like is usually subjected to surface treatment with a treatment liquid containing a silane coupling agent, and the silane coupling agent generally used as the silane coupling agent is silane coupling. Agents can be used, and if necessary, acids, dyes, pigments, surfactants and the like may be added.

As the silane coupling agent, for example, it is preferable to use the silane coupling agent represented by the formula (2).
X (R) _3-n SiY _n ... (2)
In formula (2), X is an organic functional group having at least one of an amino group and an unsaturated double-bonding group, Y is an alkoxy group independently of each other, and n is 1 or more and 3 The following integers, R is a group independently 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 3 or more of an amino group and an unsaturated double bond group, and X is an organic having at least 4 or more of an amino group and an unsaturated double bond group. It is more preferably a functional group.
Although any form can be used as the above-mentioned alkoxy group, an alkoxy group having 5 or less carbon atoms is preferable from the viewpoint of stabilizing the glass cloth.

Specific examples of the silane coupling agent include N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane and its hydrochloride salt, and N-β- (N-vinylbenzylaminoethyl)-. γ-Aminopropylmethyldimethoxysilane and its hydrochloride, N-β- (N-di (vinylbenzyl) aminoethyl) -γ-aminopropyltrimethoxysilane and its hydrochloride, N-β- (N-di (vinyl)) Benzyl) Aminoethyl) -N-γ- (N-vinylbenzyl) -γ-aminopropyltrimethoxysilane and its hydrochloride, N-β- (N-benzylaminoethyl) -γ-aminopropyltrimethoxysilane and its hydrochloride Hydrochloride, N-β- (N-benzylaminoethyl) -γ-aminopropyltri-ethoxysilane and its hydrochloride, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) Known simple substances such as aminopropyltriethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, metharoxypropyltrimethoxysilane, and acryloxipropyltrimethoxysilane, or a mixture thereof can be mentioned.

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 kinds of silane coupling agents having different molecular weights. By treating the surface of the glass yarn with two or more kinds of silane coupling agents having different molecular weights, the density of the treatment agent on the glass surface tends to be increased, and the reactivity with the matrix resin tends to be further improved.

The ignition loss value of the glass cloth is preferably 0.10% by mass or more and 2.00% by mass or less, more preferably 0.12% by mass or more and 1.50% by mass or less, and further preferably 0.15. It is mass% or more and 1.20 mass% or less. The ignition loss value of glass cloth is an index for indirectly evaluating the amount of surface treatment of glass cloth with a silane coupling agent.
When the ignition loss value is 0.10% by mass or more, the silane coupling agent is uniformly surface-treated on the glass cloth, the texture of the glass cloth becomes hard, and it becomes difficult to bend the eyes, which is preferable. When the ignited residual value is 2.00% or less, the texture of the glass cloth is kept appropriately soft, so that wrinkles are less likely to occur, which is preferable. The ignition loss value of the glass cloth is a value obtained according to the method described in JIS R 3420.

<Manufacturing method of glass cloth>
The method for producing the glass cloth of the present embodiment is not particularly limited, but for example, the surface of the glass filament is almost completely covered with the silane coupling agent by a treatment liquid having a concentration of the silane coupling agent of 0.1 to 3.0 wt%. A method having a coating step of covering with glass, a fixing step of fixing the silane coupling agent to the surface of the glass filament by heat drying, and a fiber opening step of opening the glass thread of the glass cloth can be preferably mentioned.

As the solvent for dissolving or dispersing the silane coupling agent, either water or an organic solvent can be used, but from the viewpoint of safety and protection of the global environment, it is preferable to use water as the main solvent. As a method of obtaining a treatment liquid using water as a main solvent, a method of directly adding a silane coupling agent to water, a method of dissolving the silane coupling agent in a water-soluble organic solvent to prepare an organic solvent solution, and then using the organic solvent solution. Any method of adding water to water is preferable. It is also possible to use a surfactant in combination in order to improve the water dispersibility and stability of the silane coupling agent in the treatment liquid.

As a method of applying the silane coupling agent treatment liquid to the glass cloth, (a) a method of collecting the treatment liquid in a bath and dipping and passing the glass cloth, (b) treatment with a roll coater, a die coater, a gravure coater or the like. Examples thereof include a method of directly applying the liquid to the glass cloth. When applying by the method (a) above, it is preferable to select the immersion time of the glass cloth in the treatment liquid to be 0.5 seconds or more and 1 minute or less.

Further, as a method of applying the silane coupling agent treatment liquid to the glass cloth and then heating and drying the solvent, known methods such as hot air and electromagnetic waves can be mentioned.
The heating and drying temperature is preferably 90 ° C. or higher, more preferably 100 ° C. or higher so that the reaction between the silane coupling agent and the glass is sufficiently carried out. The heat-drying temperature is preferably 300 ° C. or lower, more preferably 200 ° C. or lower, in order to prevent deterioration of the organic functional groups of the silane coupling agent.

The method for opening the fiber in the fiber opening step is not particularly limited, and examples thereof include a method for opening the glass cloth with spray water (high pressure water opening), vibro washer, ultrasonic water, mangle, or the like. .. In order to keep the total area of the basket hole within a certain range, it is preferable to carry out the fiber opening step with spray water.
When the fiber is opened with spray water, the water pressure may be appropriately set, and it is preferable that the water pressure is constant in order to adjust the total area of the basket holes existing in the glass cloth. Here, to make the water pressure constant means to reduce the difference between the water pressure of the spray set for carrying out the fiber opening and the maximum and minimum values of the actual water pressure. A step of heating and drying may be provided before and after the fiber opening step.

<Prepreg>
One of the present embodiments is a prepreg having the glass cloth and the matrix resin described in the present embodiment. The prepreg of the present embodiment is a prepreg having a small thickness and little bending, and can be preferably used as a prepreg for a printed wiring board.
Here, the difference in dielectric constant between the glass cloth and the matrix resin is preferably 3.0 or less, more preferably 2.0 or less, still more preferably 1.0 or less. The smaller the difference in dielectric constant, the more preferable, and the lower limit of the dielectric constant may be 0 or more. By reducing the difference in dielectric constant between the glass cloth and the cured resin, even if there is a variation in the abundance of glass and the abundance of resin in the insulator layer, the non-uniformity of the dielectric constant can be reduced. This tends to reduce fluctuations in the signal propagation speed.

The prepreg using the glass cloth of the present embodiment can be produced according to a conventional method. As a method for producing the prepreg of the present embodiment, for example, the glass cloth of the present embodiment is impregnated with a varnish obtained by diluting a matrix resin such as an epoxy resin with an organic solvent, and then the organic solvent is volatilized in a drying furnace. Then, the thermosetting resin is cured to a B stage state, that is, a semi-cured state to obtain a resin-impregnated prepreg.
As the matrix resin, in addition to the above-mentioned epoxy resin, heat curing of bismaleimide resin, cyanate ester resin, unsaturated polyester resin, polyimide resin, bismaleimide triazine resin (also referred to as BT resin), functionalized polyphenylene ether resin and the like Properties; Polyphenylene ether resin, polyetherimide resin, liquid crystal polymer of all aromatic polyester (also referred to as LCP), thermoplastic resin such as polybutadiene and fluororesin; or a mixed resin thereof and the like can be mentioned. From the viewpoint of improving the dielectric properties, heat resistance, solvent resistance, and press moldability, the thermoplastic resin may be modified with a thermosetting resin.

In addition, the matrix resin contains inorganic fillers such as silica and aluminum hydroxide, flame retardants such as bromine-based, phosphorus-based, and metal hydroxides, other silane coupling agents, heat stabilizers, and antistatic agents. A resin in which an ultraviolet absorber, a pigment, a colorant, a lubricant and the like are mixed may be used.

<Printed circuit board>
One of the present embodiments is a printed wiring board having the prepreg of the present embodiment. The printed wiring board of the present embodiment can be a printed wiring board in which the deviation of the positional relationship between the glass thread and the transmission line is small in the printed wiring board and the signal propagation speed difference between the plurality of transmission lines is small.
Here, the difference in dielectric constant between the glass cloth and the matrix resin is preferably 3.0 or less, more preferably 2.0 or less, still more preferably 1.0 or less. The smaller the difference in dielectric constant, the more preferable, and the lower limit of the dielectric constant may be 0 or more. By reducing the difference in dielectric constant between the glass cloth and the cured resin, the non-uniformity of the dielectric constant is reduced even if the abundance of glass in the insulator layer and the abundance of the resin composition vary. Therefore, there is a tendency that fluctuations in the signal propagation speed can be reduced.

The printed wiring board of this embodiment can be manufactured according to a conventional method. For example, a step of laminating one or more prepregs of the present embodiment, attaching copper foils to both sides of the obtained laminated board, and heating and pressurizing to produce a cured copper-clad laminate, the copper-clad laminate. A double-sided printed wiring board can be manufactured through a step of producing a circuit pattern made of copper foil on both sides of the plate, and then a step of forming a through hole and securing an electrical connection between the circuit patterns on both sides.

Hereinafter, the present invention will be specifically described with reference to Examples.
The physical characteristics of the glass cloth in Examples and Comparative Examples were measured according to JIS R3420.
The elongation rate in the warp direction and the elongation rate in the weft direction of the glass cloth were measured according to a method conforming to JIS 3420.
The amount of bending of the glass cloth was measured according to the above-mentioned method in accordance with JIS L1096.

<Example 1>
Average filament diameter 4.0 μm for warp, 50 filaments, 1.0 Z twist, mass 1.46 × 10 ^-6 kg / m per unit length L glass thread, average filament diameter 4.5 μm for weft , Filament number 50, twist number 1.0Z, mass 1.83 × 10 ^-6 kg / m per unit length using L glass thread, using air jet room, warp thread 93.5 thread / 25 mm , A glass cloth was woven with a weaving density of 70 weft threads / 25 mm. The density of L glass (composition: SiO ₂ : 51%, Al ₂ O ₃ : 13%, CaO: 8%, B ₂ O ₃ : 23%) constituting the glass cloth is 2.30 g / cm ³ . there were. The obtained glass cloth of the raw machine was heat-treated at 400 ° C. for 24 hours to deglue. Next, the glass cloth was immersed in a treatment liquid using N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane; SZ6032 (manufactured by Toray Dow Corning), which is a silane coupling agent. After squeezing, the solution was dried at 120 ° C. for 1 minute, and the fibers were further opened by spraying with high-pressure water to obtain a glass cloth A having ^{a mass of 10.7 g / m 2 and a thickness of 13 μm.}
The warp and weft widths of the glass cloth A are 140 μm and 286 μm, respectively, and the weft occupancy is 80%, the elongation in the warp direction is 0.22%, the elongation in the weft direction is 0.27%, and the cross section in the warp direction. The ratio of the height to the cross-sectional height in the weft direction was 0.97. The amount of bending of the glass cloth A was 3 mm, and the glass cloth was excellent in handleability.
The glass cloth A was processed to a width of 650 mm for a coating test, and prepreg coating was performed using an epoxy resin varnish. The epoxy resin varnish was composed of 80 parts by mass of low brominated bisphenol A type epoxy resin, 20 parts by mass of cresol novolac type epoxy resin, 2 parts by mass of dicyandiamide, 0.2 parts by mass of 2-ethyl-4-methylimidazole, and 2-methoxy. -100 parts by mass of ethanol was blended and prepared. The glass cloth is conveyed at a speed of 3 m / min, the glass cloth A is immersed in the epoxy resin varnish, and the excess varnish is scraped off through a slit whose gap is adjusted so that the resin content is 68% by mass, and then the drying temperature is reached. The epoxy resin was dried under the conditions of 170 ° C. and a drying time of 1 minute and 30 seconds, and the epoxy resin was semi-cured (B-staged) to obtain prepreg A.
The prepreg A was cut to a size of 550 mm × 550 mm, and then copper foils having a thickness of 35 μm were placed on both surfaces of the prepreg A, and then compression molding was performed at ^{175 ° C. and 40 kgf / cm 2 to obtain a substrate A.} The obtained substrate A was subjected to an etching treatment and processed so that a line of a copper foil having a width of 200 μm was arranged at a right angle to the warp to obtain an evaluation substrate A.
Based on the position 2 cm from the end of the copper foil wire, the distance between the copper foil wire and the weft was evaluated to be within 0.5 times the distance between the wefts, and as a result, it was 70 mm.

<Example 2>
The weaving of the glass cloth and the subsequent treatment were performed by the same method as in Example 1 except that the weft density was 75 threads / 25 mm, and ^{the glass cloth B having a mass of 11.1 g / m 2} and a thickness of 14 μm was obtained. Obtained. The warp and weft widths of the glass cloth B are 138 μm and 276 μm, respectively, and the weft occupancy is 83%, the elongation in the warp direction is 0.19%, the elongation in the weft direction is 0.25%, and the cross section in the warp direction. The ratio of the height to the cross-sectional height in the weft direction was 1.00. The amount of bending of the glass cloth B was 1 mm, and the glass cloth was excellent in handleability.
As a result of producing the evaluation substrate B in the same manner as in Example 1 and evaluating the distance that the deviation between the copper foil wire and the weft was within 0.5 times the interval between the wefts, the result was 202 mm.

<Example 3>
A glass cloth was woven and then processed by the same method as in Example 1 except that the weft density was 78 threads / 25 mm, and ^{a glass cloth C having a mass of 11.2 g / m 2} and a thickness of 14 μm was obtained. Obtained. The warp and weft widths of the glass cloth C are 138 μm and 277 μm, respectively, and the weft occupancy is 86%, the elongation in the warp direction is 0.19%, the elongation in the weft direction is 0.23%, and the cross section in the warp direction. The ratio of the height to the cross-sectional height in the weft direction was 1.03. The amount of bending of the glass cloth C was 0.5 mm, and the glass cloth was excellent in handleability.
As a result of producing the evaluation substrate C in the same manner as in Example 1 and evaluating the distance that the deviation between the copper foil wire and the weft was within 0.5 times the interval between the wefts, it was 415 mm.

<Example 4>
The weft is made of L glass with an average filament diameter of 4.0 μm, 67 filaments, 1.0 Z twist, and a mass of 1.95 x 10 ^{-6 kg / m per unit length.} A glass cloth was woven and then processed by the same method as in Example 1 except that the size was 68 pieces / 25 mm, to obtain a glass cloth D having ^{a mass of 11.0 g / m 2 and a thickness of 13 μm.} The warp and weft widths of the glass cloth D are 150 μm and 287 μm, respectively, and the weft occupancy is 78%, the elongation in the warp direction is 0.19%, the elongation in the weft direction is 0.26%, and the cross section in the warp direction. The ratio of the height to the cross-sectional height in the weft direction was 1.06. The amount of bending of the glass cloth D was 2.5 mm, and the glass cloth was excellent in handleability.
As a result of producing the evaluation substrate D in the same manner as in Example 1 and evaluating the distance that the deviation between the copper foil wire and the weft was within 0.5 times the interval between the wefts, it was 91 mm.

<Example 5>
The weaving of the glass cloth and the subsequent treatment were performed by the same method as in Example 4 except that the weft density was 72 threads / 25 mm to obtain ^{a glass cloth E having a mass of 11.3 g / m 2} and a thickness of 13 μm. Obtained. The warp and weft widths of the glass cloth E are 152 μm and 285 μm, respectively, and the weft occupancy is 82%, the elongation in the warp direction is 0.20%, the elongation in the weft direction is 0.25%, and the cross section in the warp direction. The ratio of the height to the cross-sectional height in the weft direction was 1.03. The amount of bending of the glass cloth E was 1.5 mm, and the glass cloth was excellent in handleability.
As a result of producing the evaluation substrate E in the same manner as in Example 1 and evaluating the distance that the deviation between the copper foil wire and the weft was within 0.5 times the interval between the wefts, it was 157 mm.

<Example 6>
A glass cloth was woven and then processed by the same method as in Example 4 except that the weft density was 75 threads / 25 mm, and ^{a glass cloth F having a mass of 11.8 g / m 2} and a thickness of 14 μm was obtained. Obtained. The warp and weft widths of the glass cloth F are 149 μm and 282 μm, respectively, and the weft occupancy is 85%, the elongation in the warp direction is 0.20%, the elongation in the weft direction is 0.24%, and the cross section in the warp direction. The ratio of the height to the cross-sectional height in the weft direction was 1.03. The amount of bending of the glass cloth F was 1.5 mm, and the glass cloth was excellent in handleability.
As a result of producing the evaluation substrate F in the same manner as in Example 1 and evaluating the distance that the deviation between the copper foil wire and the weft was within 0.5 times the interval between the wefts, it was 165 mm.

<Comparative example 1>
The air jet room uses L glass threads with an average filament diameter of 4.0 μm, 50 filaments, 1.0 Z twists, and a mass of 1.47 x 10 ^{-6 kg / m per unit length for both warp and weft.} Was used to weave a glass cloth with a weaving density of 93.5 threads / 25 mm for both warp and weft. The obtained glass cloth of the raw machine was heat-treated at 400 ° C. for 24 hours to deglue. Next, the glass cloth was immersed in a treatment liquid using N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane; SZ6032 (manufactured by Toray Dow Corning), which is a silane coupling agent. After squeezing, the solution was dried at 120 ° C. for 1 minute, and the fibers were further opened by spraying with high-pressure water to obtain a glass cloth G having ^{a mass of 11.1 g / m 2 and a thickness of 14 μm.}
The warp and weft widths of the glass cloth G are 133 μm and 224 μm, respectively, and the weft occupancy is 84%, the elongation in the warp direction is 0.19%, the elongation in the weft direction is 0.39%, and the cross section in the warp direction. The ratio of the height to the cross-sectional height in the weft direction was 1.14. The amount of bending of the glass cloth G was 7 mm, and the glass cloth had a large bending.
As a result of producing the evaluation substrate G in the same manner as in Example 1 and evaluating the distance that the deviation between the copper foil wire and the weft was within 0.5 times the interval between the wefts, it was 23 mm.

<Comparative example 2>
Average filament diameter 4.0 μm for warp, 40 filaments, 1.0 Z twist, mass 1.17 × 10 ^-6 kg / m per unit length L glass thread, average filament diameter 4.0 μm for weft , Filament number 50, twist number 1.0Z, mass 1.47 x 10 ^-6 kg / m per unit length L glass thread is used, and an air jet room is used, and both warp and weft are 95 threads / A glass cloth was woven with a weaving density of 25 mm. The obtained glass cloth of the raw machine was heat-treated at 400 ° C. for 24 hours to deglue. Next, the glass cloth was immersed in a treatment liquid using N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane; SZ6032 (manufactured by Toray Dow Corning), which is a silane coupling agent. After squeezing, the solution was dried at 120 ° C. for 1 minute, and the fibers were further opened by spraying with high-pressure water to obtain a glass cloth H having ^{a mass of 9.2 g / m 2 and a thickness of 14 μm.}
The warp and weft widths of the glass cloth H are 124 μm and 215 μm, respectively, and the weft occupancy is 82%, the elongation in the warp direction is 0.25%, the elongation in the weft direction is 0.34%, and the cross section in the warp direction. The ratio of the height to the cross-sectional height in the weft direction was 0.97. The amount of bending of the glass cloth H was 10 mm, and the glass cloth had a large bending.
As a result of producing the evaluation substrate H in the same manner as in Example 1 and evaluating the distance that the deviation between the copper foil wire and the weft was within 0.5 times the interval between the wefts, it was 13 mm.

<Comparative example 3>
The air jet room uses L glass threads with an average filament diameter of 4.0 μm, 50 filaments, 1.0 Z twists, and a mass of 1.47 x 10 ^{-6 kg / m per unit length for both warp and weft.} The glass cloth was woven with a weaving density of 85 threads / 25 mm for both the warp and the weft. The glass cloth of the obtained raw machine was subjected to a ^{fiber-spreading process (processing pressure 196 N / cm 2} ) by a high-pressure sprinkling flow under a tension of 4.9 N / m. Then, it was heat-treated at 400 ° C. for 24 hours to deglue. Subsequently, a glass cloth was added to a treatment liquid using N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane; SZ6032 (manufactured by Toray Dow Corning), which is a silane coupling agent. After immersion and squeezing, the mixture was dried at 120 ° C. for 1 minute to obtain a glass cloth I having ^{a mass of 9.7 g / m 2 and a thickness of 12 μm.} The chemical and physical treatment of the glass cloth was based on the method of Example 2 of Patent Document 4: Japanese Patent No. 3756066.
The warp and weft widths of the glass cloth I are 185 μm and 202 μm, respectively, and the weft occupancy is 69%, the elongation in the warp direction is 0.27%, the elongation in the weft direction is 0.42%, and the cross-sectional height in the warp direction. The ratio of the cross-sectional height in the weft direction to the cross-sectional height was 1.06. The amount of bending of the glass cloth I was 8 mm, and the glass cloth had a large bending.
As a result of producing the evaluation substrate I in the same manner as in Example 1 and evaluating the distance that the deviation between the copper foil wire and the weft was within 0.5 times the interval between the wefts, it was 17 mm.

<Comparative example 4>
The air jet room uses L glass threads with an average filament diameter of 4.0 μm, 40 filaments, 1.0 Z twists, and a mass of 1.17 x 10 ^{-6 kg / m per unit length for both the warp and weft threads.} Was used to weave a glass cloth with a weaving density of 94.5 threads / 25 mm for both warp and weft. The glass cloth of the obtained raw machine was subjected to a ^{fiber-spreading process (processing pressure 196 N / cm 2} ) by a high-pressure sprinkling flow under a tension of 4.9 N / m. Then, it was heat-treated at 400 ° C. for 24 hours to deglue. Subsequently, a glass cloth was dipped in a treatment liquid using SZ6032 (manufactured by Toray Dow Corning Co., Ltd.), which is a silane coupling agent, squeezed, dried at 120 ° C. for 1 minute, and massed at 9.0 g / m ^2. , A glass cloth J having a thickness of 11 μm was obtained. The chemical and physical treatment of the glass cloth was based on the method of Example 2 of Patent Document 4: Japanese Patent No. 3756066.
The warp and weft widths of the glass cloth J are 158 μm and 177 μm, respectively, and the weft occupancy is 67%, the elongation in the warp direction is 0.17%, the elongation in the weft direction is 0.37%, and the cross section in the warp direction. The ratio of the height to the cross-sectional height in the weft direction was 1.09. The amount of bending of the glass cloth J was 8 mm, and the glass cloth had a large bending.
As a result of producing the evaluation substrate J in the same manner as in Example 1 and evaluating the distance that the deviation between the copper foil wire and the weft was within 0.5 times the interval between the wefts, it was 15 mm.

<Comparative example 5>
The weft is made of L glass with an average filament diameter of 4.5 μm, 50 filaments, 1.0 Z twist, and a mass of 1.83 x 10 ^{-6 kg / m per unit length.} A glass cloth was woven and then processed by the same method as in Comparative Example 1 except that the size was 60 pieces / 25 mm, to obtain a glass cloth K having ^{a mass of 10.1 g / m 2 and a thickness of 12 μm.}
The warp and weft widths of the glass cloth K are 135 μm and 267 μm, respectively, and the weft occupancy is 64%, the elongation in the warp direction is 0.21%, the elongation in the weft direction is 0.29%, and the cross section in the warp direction. The ratio of the height to the cross-sectional height in the weft direction was 1.09. The amount of bending of the glass cloth K was 6 mm, and the glass cloth had a large bending.
As a result of producing the evaluation substrate K in the same manner as in Example 1 and evaluating the distance that the deviation between the copper foil wire and the weft was within 0.5 times the interval between the wefts, it was 31 mm.

Table 1 shows the characteristics and evaluation results of the glass cloths and substrates produced in Examples and Comparative Examples.

The glass cloth of the present invention has industrial applicability as a base material used for a printed wiring board used in the electronic and electrical fields.

a: Thread width of weft thread b: Spacing of weft threads

Claims (19)

A glass cloth having a thickness of 8 μm or more and 16 μm or less, which is composed of glass threads composed of a plurality of glass filaments as warp threads and weft threads.
Equation (1);
Y = F / (25000 / G) x 100 ... (1)
(In the formula, F is the yarn width (μm) of the weft, and G is the weaving density of the weft (book / 25 mm).)
The abundance ratio Y of the weft in the longitudinal direction, which is obtained in the above, is 75% or more and 90% or less.
The sum of the warp yarn width and the weft yarn width is 380 μm or more and 500 μm or less.
The density of the warp and the glass constituting the weft is 2.10 g / cm ³ or more and 2.50 g / cm ³ or less.
Glass cloth. The sum of the elongation rate in the warp direction when a load of 5 N per 25 mm width is applied in the warp direction and the elongation rate in the weft direction generated when a load of 5 N per 25 mm width is applied in the weft direction is 0.50% or less. Is,
The glass cloth according to claim 1. A glass cloth having a thickness of 8 μm or more and 16 μm or less, which is composed of glass threads composed of a plurality of glass filaments as warp threads and weft threads.
Equation (1);
Y = F / (25000 / G) x 100 ... (1)
(In the formula, F is the yarn width (μm) of the weft, and G is the weaving density of the weft (book / 25 mm).)
The abundance ratio Y of the weft in the longitudinal direction, which is obtained in the above, is 75% or more and 90% or less.
The amount of weft bending is less than or equal to the value obtained by dividing the value of 10 times the weft spacing (μm) by 500 mm.
The density of the warp and the glass constituting the weft is 2.10 g / cm ³ or more and 2.50 g / cm ³ or less.
Glass cloth. The amount of weft bending is less than or equal to the value obtained by dividing the value of 5 times the weft spacing (μm) by 500 mm.
The glass cloth according to claim 3. The amount of weft bending is less than or equal to the value obtained by dividing the value of 2.5 times the weft spacing (μm) by 500 mm.
The glass cloth according to claim 3. The amount of weft bending is less than or equal to the value obtained by dividing the value of 1.0 times the weft spacing (μm) by 500 mm.
The glass cloth according to claim 3. The sum of the warp yarn width and the weft yarn width is 380 μm or more and 500 μm or less.
The glass cloth according to any one of claims 3 to 6. The sum of the elongation rate in the warp direction when a load of 5 N per 25 mm width is applied in the warp direction and the elongation rate in the weft direction generated when a load of 5 N per 25 mm width is applied in the weft direction is 0.50% or less. Is,
The glass cloth according to claim 7. The ratio of the cross-sectional height in the warp direction to the cross-sectional height in the weft direction is 90% or more and 110% or less.
The glass cloth according to claim 1 or 2. The sum of the warp yarn width and the weft yarn width is 380 μm or more and 500 μm or less.
The glass cloth according to any one of claims 3 to 6, wherein the ratio of the cross-sectional height in the warp direction to the cross-sectional height in the weft direction is 90% or more and 110% or less. The permittivity of 10 GHz is 5 or less.
The glass cloth according to any one of claims 1 to 10. The average mass per unit length of the warp is 1.40 × 10 ^-6 kg / m or more ^{and less than 1.60 × 10 -6} kg / m.
The average mass per unit length of the weft is 1.65 × 10 ^-6 kg / m ^{and more than 3.00 × 10 -6} kg / m.
The ratio of the average mass per unit length of the weft to the average mass per unit length of the warp (weft / warp ratio) is 1.20 or more and 1.50 or less.
The glass cloth according to any one of claims 1 to 11. The average number of filaments of the warp and weft is substantially the same, and
The average filament diameter of the warp is 3.7 μm or more and 4.3 μm or less.
The average filament diameter of the weft is 4.2 μm or more and 5.3 μm or less.
The ratio of the average filament diameter of the weft to the average filament diameter of the warp (weft / warp ratio) is 1.07 or more and 1.40 or less.
The glass cloth according to any one of claims 1 to 12. The average filament diameters of the warp and weft are substantially the same, and
The average number of warp filaments is 45 or more and 70 or less.
The average number of weft filaments is 55 or more and 80 or less.
The ratio of the average number of filaments of the weft to the average number of filaments of the warp (weft / warp ratio) is larger than 1.25 and 1.50 or less.
The glass cloth according to any one of claims 1 to 12. The glass cloth according to any one of claims 1 to 14 and
With matrix resin,
Prepreg. The difference between the dielectric constant of the glass constituting the glass cloth at 10 GHz and the dielectric constant of the cured product of the matrix resin at 10 GHz is 3 or less.
The prepreg according to claim 15. The difference between the dielectric constant of the glass constituting the glass cloth at 10 GHz and the dielectric constant of the cured product of the matrix resin at 10 GHz is 2 or less.
The prepreg according to claim 15. The difference between the dielectric constant of the glass constituting the glass cloth at 10 GHz and the dielectric constant of the cured product of the matrix resin at 10 GHz is 1 or less.
The prepreg according to claim 15. The prepreg according to any one of claims 15 to 18.
Printed wiring board.

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