CN112626670A

CN112626670A - Glass cloth, prepreg, and printed wiring board

Info

Publication number: CN112626670A
Application number: CN202011055506.4A
Authority: CN
Inventors: 远藤正朗; 柿崎宏昂
Original assignee: Asahi Kasei Corp
Current assignee: Asahi Kasei Corp
Priority date: 2019-10-07
Filing date: 2020-09-30
Publication date: 2021-04-09
Anticipated expiration: 2040-09-30
Also published as: TWI787657B; JP2021059811A; CN112626670B; JP7448329B2; TW202120764A

Abstract

Glass cloth, prepreg and printed wiring board. Provided is a low dielectric glass cloth in which skewing is suppressed while the thickness is maintained at 16 [ mu ] m or less. Also provided are a prepreg and a printed wiring board, wherein the difference in signal propagation speeds between a plurality of transmission lines is reduced. A glass cloth having a thickness of 8 [ mu ] m or more and 16 [ mu ] m or less, which is formed by using glass filaments comprising a plurality of glass filaments as warps and wefts, wherein the ratio of existence of wefts in the longitudinal direction, which is determined by the formula (1), isY is 75% to 90%, Y is F/(25000/G). times.100 (1) (in the formula (1), F is the width (mum) of weft, G is the weaving density (root/25 mm) of weft), the sum of the width of warp and the width of weft is 380 μm to 500 μm, and the density of glass constituting the warp and weft is 2.10G/cm³Above and 2.50g/cm³The following.

Description

Glass cloth, prepreg, and printed wiring board

Technical Field

The invention relates to a glass cloth, a prepreg and a printed wiring board.

Background

In most printed wiring boards, a transmission line is formed by a copper foil in an insulator layer composed of a glass cloth and a matrix resin composition.

Glass cloth used in a printed wiring board is formed by plain-weaving glass filaments in the warp and weft directions. Therefore, in the insulator layer composed of the glass cloth and the resin composition, the presence ratio of glass increases at the portion where the filaments intersect, and the presence ratio of resin increases at the portion where no filaments overlap or no filaments overlap.

In general, there is a difference between the dielectric constant of the glass cloth and the dielectric constant of the resin composition. Therefore, it is known that a difference occurs between the signal propagation velocity in the transmission line passing through the portion where the existence ratio of the glass is high and the signal propagation velocity in the transmission line passing through the portion where the existence ratio of the resin composition is high. Therefore, in an electronic circuit that needs to synchronize a plurality of signals, if the arrival time of the signals is shifted, there is a possibility that a problem arises in signal processing.

With the development of information communication society in recent years, data communication and/or signal processing are performed at high speed with large capacity, and the speed of signals to be transmitted is increasing. The signal speed exceeds 10Gbps, and the signal speed is increasing in the gigabit region such as 28Gbps and 56Gbps, and the influence of the signal propagation speed difference is increasing and the demand for reducing the signal propagation speed difference is increasing as the signal speed increases.

It is known that, when a pair of wirings are formed in the same insulator layer, the positional relationship between the transmission line and the glass cloth is affected by the difference in the dielectric constant between the portion where the glass is present at a high ratio and the portion where the resin is present at a high ratio. Therefore, patent documents 1 to 3 propose techniques for reducing a change in propagation velocity due to a positional relationship between a glass cloth and a transmission line.

Specifically, patent document 1 discloses a technique of setting the line width to 75% to 95% of the interval between the glass cloth filaments.

Patent document 2 discloses a technique for matching the spacing of glass filaments with the spacing of signal lines.

Patent document 3 discloses a technique of setting the distance between the glass filaments and the wiring width to 50%.

As another attempt to reduce the difference in signal propagation velocity, many techniques have been proposed in which the dielectric constant of glass cloth is reduced to reduce the difference in dielectric constant between a portion having a high glass existence rate and a portion having a high resin existence rate. For example, in the low dielectric glass cloth disclosed in patent document 7, a large amount of B is added to a glass composition of a glass cloth, compared with a conventionally used E glass cloth₂O₃While adjusting SiO₂And the like, thereby achieving a low dielectric constant.

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

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2014-130860

Patent document 2: international publication No. 2016/117320

Patent document 3: international publication No. 2017/159649

Patent document 4: japanese patent No. 3756066

Patent document 5: japanese patent No. 4446754

Patent document 6: japanese patent No. 5936726

Patent document 7: japanese laid-open patent publication No. 11-292567

Disclosure of Invention

Problems to be solved by the invention

The glass fibers constituting the glass cloth have a characteristic that skewing may occur. In particular, since a thin glass cloth uses thin glass filaments as compared with a thick glass cloth, the width of warp and weft filaments is generally narrow, and the contact area between warp and weft filaments at the crossing point of warp and weft filaments is small. Therefore, the binding force between the warp yarns and the weft yarns becomes weak, and when the parallelism of rollers for conveying the glass cloth is slightly deviated in a process of producing the glass cloth or a process of producing the prepreg using the glass cloth, for example, a difference in the width direction, that is, the CD direction occurs in the tension acting on the warp yarns. As a result, there are the following problems: the warp yarns and weft yarns cross each other at right angles, and weft yarn inclination or warp yarn inclination is likely to occur.

In addition, in the process of producing a prepreg, in the step of passing through a narrow slit in order to control the amount of resin adhering during impregnation with a coating resin, there is a problem in that: in the glass cloth, a load is unevenly applied in the width direction, and skewing is likely to occur.

The smaller the thickness of the glass cloth, the more pronounced the skewness of the weft, and the smaller the number of filaments constituting the glass cloth.

In particular by controlling the glass composition to achieve low dielectric properties, in particular by adjusting the glass composition, for example by increasing B in the glass composition₂O₃The glass constituting the glass filaments has a low specific gravity due to the amount of the glass and the like, and the glass filaments tend to have low rigidity. The smaller the density of the glass and the smaller the rigidity of the glass, the more remarkable the skewing becomes.

Therefore, as disclosed in patent documents 1 to 3, when a method of reducing the difference in signal propagation speed is attempted by using a transmission line in which the arrangement of glass fibers is taken into consideration, the positional relationship between the transmission line and the glass fibers is shifted and/or deviated due to the skew of the glass fibers, and there is a problem that it is difficult to precisely control the signal propagation speed.

Examples 1 to 4 of patent document 4 specifically disclose glass cloths having an average value of weft skew amounts measured at 10 points per 10m of glass cloth having a length of 100m of 3 to 5mm and a thickness of 10 to 12 μm. Patent document 4 discloses that the average value of the skewness of the weft is small. However, since the skew amount is usually varied, if there is a portion with a large skew, a transmission line with a greatly varying signal propagation speed is generated, and a problem arises in signal processing in an electronic circuit that needs to synchronize a plurality of signals.

Specifically disclosed in examples 1 to 5 of patent document 5 are glass cloths having an average value of skewness measured per 10m of glass cloth of 100m length of 1 to 3mm and a thickness of 17 to 21 μm. In the glass cloth described in patent document 5, adjacent filaments are arranged without a gap in practice in order to improve the pinhole processability. Therefore, it is necessary to use glass filaments 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 has a used mass of both warp and weft of 1.65 × 10^- ⁶Fine glass filaments (lighter than ECBC3000, BC3750, BC5000, BC 6000) of kg/m or less, and also narrow in filament width of warp and weft. Therefore, the binding force between the crossing points of the warp yarns and the weft yarns is weak, and skewing easily occurs as in the conventional glass cloth.

The present invention has been made in view of the above problems, and an object thereof is to provide a low dielectric glass cloth in which skewing 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 in which a difference in signal propagation speed between a plurality of transmission lines using the glass cloth is reduced.

Means for solving the problems

The present inventors have intensively studied to solve the above problems, and as a result, have found that the occurrence of skewing is suppressed in a state where the thickness of a low dielectric glass cloth in which the presence ratio of weft in the longitudinal direction and the sum of the width of warp and the width of weft satisfy a specific range is maintained at 16 μm or less, and have completed the present invention.

The present inventors have also found that, when a low-dielectric glass cloth in which the ratio of weft existing in the longitudinal direction is within a specific range and the skew amount of weft and the pitch of weft satisfy a specific relationship is formed into a printed wiring board, it is possible to increase the distance by which the variation in the ratio of glass existing in an insulator layer through which a transmission line arranged parallel to the weft passes is suppressed to a small extent, and thus it is possible to reduce the variation in the signal propagation speed, and have completed the present invention.

Namely, the present invention is as follows.

[1] A glass cloth having a thickness of 8 to 16 [ mu ] m, which is formed by using glass filaments comprising a plurality of glass filaments as warp filaments and weft filaments,

the ratio Y of weft threads in the longitudinal direction determined by the formula (1) is 75% to 90%,

Y＝F/(25000/G)×100 (1)

(in the formula (1), F is the width (μm) of the weft, G is the weaving density (root/25 mm) of the weft),

the sum of the width of the warp and the width of the weft is 380 to 500 μm,

the density of the glass constituting the warp and weft is 2.10g/cm³Above and 2.50g/cm³The following.

[2] The glass cloth according to [1], wherein a sum of an elongation in the warp direction which is generated when a load of 5N is applied in the warp direction per 25mm width and an elongation in the weft direction which is generated when a load of 5N is applied in the weft direction per 25mm width is 0.50% or less.

[3] A glass cloth having a thickness of 8 to 16 [ mu ] m, which is formed by using glass filaments comprising a plurality of glass filaments as warp filaments and weft filaments,

Y＝F/(25000/G)×100 (1)

the weft skew amount of the weft is not more than a value obtained by dividing a value 10 times the interval (mum) of the weft by 500mm,

forming the warp yarn and the frontThe density of the glass of the weft is 2.10g/cm³Above and 2.50g/cm³The following.

[4] The glass cloth according to item [3], wherein the weft skew amount of the weft is equal to or less than a value obtained by dividing a value of 5 times an interval (μm) between the weft by 500 mm.

[5] The glass cloth according to item [3], wherein the weft skew amount of the weft is equal to or less than a value obtained by dividing a value 2.5 times the interval (μm) of the weft by 500 mm.

[6] The glass cloth according to item [3], wherein the weft skew amount of the weft is equal to or less than a value obtained by dividing a value 1.0 times the interval (μm) of the weft by 500 mm.

[7] The glass cloth according to any one of [3] to [6], wherein a sum of a filament width of the warp and a filament width of the weft is 380 μm or more and 500 μm or less.

[8] The glass cloth according to item [7], wherein a sum of an elongation in the warp direction which occurs when a load of 5N is applied in the warp direction per 25mm width and an elongation in the weft direction which occurs when a load of 5N is applied in the weft direction per 25mm width is 0.50% or less.

[9] The glass cloth according to item [1] or [2], wherein a ratio of a cross-sectional height in a warp direction to a cross-sectional height in a weft direction is 90% or more and 110% or less.

[10] The glass cloth according to any one of [3] to [6], wherein a sum of a filament width of the warp and a filament width of the weft is 380 to 500 μm,

the ratio of the cross-sectional height in the warp direction to the cross-sectional height in the weft direction is 90% to 110%.

[11] The glass cloth according to any one of [1] to [10], which has a dielectric constant of 5 or less at 10 GHz.

[12]According to [1]～[11]The glass cloth of any of claims, wherein the warp filaments have an average mass per unit length of 1.40 x 10^-6kg/m is more than or equal to and less than 1.60 multiplied by 10^-6kg/m，

The average mass per unit length of the weft is more than 1.65 x 10^-6kg/m and 3.00X 10^-6kg/m or less, and

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 to 1.50.

[13] The glass cloth according to any one of [1] to [12], wherein the average filament numbers of the warp and weft are substantially the same, and

the average filament diameter of the warp is more than 3.7 μm and less than 4.3 μm,

the average filament diameter of the weft is 4.2-5.3 μm,

the ratio of the average filament diameter of the weft to the average filament diameter of the warp (weft/warp ratio) is 1.07-1.40.

[14] The glass cloth according to any one of [1] to [12], wherein the warp and weft have substantially the same average filament diameter, and

the average number of filaments of the warp yarn is 45 to 70,

the average number of filaments of the weft is 55 to 80,

the ratio of the average number of filaments of the weft to the average number of filaments of the warp (weft/warp ratio) is greater than 1.25 and not more than 1.50.

[15] A prepreg comprising the glass cloth according to any one of [1] to [14] and a matrix resin.

[16] The prepreg according to [15], wherein a difference between a dielectric constant at 10GHz of the glass constituting the glass cloth and a dielectric constant at 10GHz of a cured product of the matrix resin is 3 or less.

[17] The prepreg according to [15], wherein a difference between a dielectric constant at 10GHz of the glass constituting the glass cloth and a dielectric constant at 10GHz of a cured product of the matrix resin is 2 or less.

[18] The prepreg according to [15], wherein a difference between a dielectric constant at 10GHz of the glass constituting the glass cloth and a dielectric constant at 10GHz of a cured product of the matrix resin is 1 or less.

[19] A printed wiring board having the prepreg according to any one of [15] to [18 ].

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a low dielectric glass cloth in which skewing is suppressed in a state where the thickness is maintained at 16 μm or less can be provided. The glass cloth of the present invention can reduce the positional relationship between the glass yarn and the transmission line when forming a printed wiring board. Further, according to the present invention, a prepreg and a printed wiring board having a small difference in signal propagation speed between a plurality of transmission lines can be provided.

Drawings

Fig. 1 is a graph showing a load-elongation curve as a result of measuring the elongation of a glass cloth G (type 1017 for L glass) obtained in comparative example 1.

Fig. 2 is a graph showing a load-elongation curve of the glass cloth C obtained in example 3.

Fig. 3 is a schematic view showing the width of weft and the interval between weft in the glass cloth according to the present embodiment.

Fig. 4 is a schematic view showing one form of the glass cloth of the present embodiment, and is a view showing one form of the weft.

Fig. 5 is a schematic view showing one form of the glass cloth of the present embodiment, and is a view showing one form of the weft.

Fig. 6 is a schematic view showing one form of the glass cloth of the present embodiment, and is a view showing one form of the weft.

Description of the reference numerals

a: width of weft

b: spacing of weft threads

Detailed Description

An embodiment of the present invention (hereinafter, referred to as "the present embodiment") will be described in detail below, but the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention.

The dielectric constant in the present embodiment is a value measured in a 10GHz band by a cavity resonator perturbation method (perturbation method cavity resonator/product of kanto electronic application development).

< glass cloth >

(thickness)

The glass cloth of the present embodiment is a glass cloth having a thickness of 8 μm to 16 μm, which is formed by using glass filaments including a plurality of glass filaments as warp filaments and weft filaments.

By setting the thickness to 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. The thickness of the glass cloth is preferably small, but since the thickness is small, the glass yarn to be formed needs to be thin, and the strength of the glass cloth is likely to be reduced and skewness of weft tends to occur. The thickness of 8 μm or more maintains the strength of the glass cloth and suppresses the occurrence of skewness.

(weft occupancy)

In the glass cloth of the present embodiment, the ratio of weft filaments existing in the longitudinal direction is 75% or more and 90% or less. The presence ratio of weft in the longitudinal direction is also referred to as weft occupancy, and is a value Y obtained by dividing the width of the weft by the interval between the wefts, which is obtained from equation (1).

Y＝F/(25000/G)×100 (1)

(wherein F is the width (μm) of weft and G is the weaving density (root/25 mm.) of weft.)

The width of the weft is an average value obtained by observing a glass cloth sample having a size of 100mm × 100mm from the surface by a microscope, determining the width of all the wefts, and dividing the total by the total number of the wefts. In this case, when the width of the weft varies within the sample, the width of the portion having the largest width is defined as the width of the weft.

One of the embodiments is a glass cloth having a thickness of 8 μm to 16 μm, which is formed by using glass filaments including a plurality of glass filaments as warp filaments and weft filaments,

Y＝F/(25000/G)×100 (1)

(wherein F is the width (. mu.m) of the weft and G is the weaving density (root/25 mm) of the weft),

the sum of the width of the warp and the width of the weft is 380 to 500 μm,

The glass cloth is also referred to as glass cloth P.

(sum of the filament widths of the warp and weft)

The sum of the widths of the warp yarns and the widths of the weft yarns in the glass cloth P of the present embodiment is 380 μm to 500 μm, preferably 380 μm to 480 μm, and more preferably 400 μm to 480 μm.

The sum of the width of the warp yarn and the width of the weft yarn is 380 [ mu ] m or more, so that the contact area between the warp yarn and the weft yarn at the crossing point of the warp yarn and the weft yarn is increased. Therefore, the frictional area between the warp and weft is increased, so that the binding force between the warp and weft is increased and the skewness of the weft is suppressed.

When the sum of the width of the warp yarn and the width of the weft yarn is 500 μm or less, the binding force between the warp yarn and the weft yarn at the crossing point of the warp yarn and the weft yarn is not so strong, and there is room for the warp yarn and the weft yarn to move properly. Therefore, in the thin glass cloth having a thickness of 16 μm or less, the warp yarns and the weft yarns move with the crossing points as base points when the stress is applied, so that the stress is relaxed, and the occurrence of wrinkles and breakage are suppressed.

In addition, a line width used for a multilayer wiring board or the like is generally about 0.1 mm. Therefore, in the glass cloth having a weft occupancy of 75% to 90%, in order to suppress a change in the percentage of glass in the insulator layer through which the transmission line arranged parallel to the weft passes, the width of the weft is preferably 300 μm or less, and the sum of the width of the warp and the width of the weft is preferably 500 μm or less.

The sum of the width of warp and the width of weft is 380-500 μm, and thus a glass cloth having no wrinkles and skewness and excellent handling properties is obtained.

(sum of elongation)

In the glass cloth of the present embodiment, the sum of the elongation in the warp direction when a load of 5N is applied in the warp direction per 25mm width and the elongation in the weft direction when a load of 5N is applied in the weft direction per 25mm width is preferably 0.50% or less.

The sum of the elongations is more preferably 0.48 or less, and still more preferably 0.45 or less.

Here, the elongation of the glass cloth is a value obtained as follows.

The elongation of the glass cloth when tension is applied in the warp direction or the weft direction is measured by the method described in the section of glass test general test method of JIS R3420 or 7.4 tensile strength. In the method prescribed in JIS, a test piece having a width of about 30mm and a length of about 250mm is collected from the warp direction and the weft direction of a woven fabric, the yarns at both ends of the test piece are unwound to have a width of about 25mm, the test piece is attached to a holding portion with a holding interval of about 150mm secured, and the test piece is stretched at a stretching speed of about 200 mm/min to determine a load at the time of breaking. In the present embodiment, a tensile test was performed under the same conditions as the method defined in JIS above except that the tensile speed was set to about 10 mm/min and the width of the collected test piece was set to about 35mm in order to improve the measurement accuracy, and the amount of displacement when a load of 5N was applied per 25mm width of the glass cloth was determined, and the value determined by using the following formula (2) was defined as "elongation of the glass cloth".

Elongation { (interval under load-interval under no load)/interval under no load } × 100(2)

The present inventors have studied the relationship between the woven structure of the glass cloth and the ease of occurrence of skewing, and as a result, they have found that there is a correlation between the "elongation of the initial deformed region" and the ease of occurrence of skewing when the tensile force is exerted, and that the occurrence of skewing is significantly suppressed in the normal handling of the glass cloth when the "elongation of the initial deformed region" is less than a specific range.

Fig. 1 shows the measurement results of the elongation of a glass cloth of 1017 type (glass cloth G obtained in comparative example 1) which is a conventional thin glass cloth and is often used for L glass of a printed wiring board, that is, a glass cloth having a thickness of 14 μm, that is, a load-elongation curve.

The load-elongation curve of a glass cloth of the type 1017 for L glass is characterized in that the elongation of the weft is increased as compared with the warp until the displacement is about 0 to 0.2%, the inclination is low, then the elongation gradually increases up to 0.4%, and the weft is swung up 0.4% and thereafter to form a constant inclination.

The low-inclination region reflects that the weft yarn is largely stretched to a state of close contact, that is, a state of tightening, by a very weak tensile tension because a gap is present between the weft yarn and the warp yarn at the crossing point of the weft yarn and the warp yarn and a state of sufficient close contact is not formed. The next gradually increasing slant region is a region where the warp yarn curls more and the weft yarn curls less. The region where the lift and the slope are constant is then the region where elastic deformation occurs in which the weft itself stretches.

As described above, the weft of the 1017 cloth of L glass has the initial deformation region before the elastic deformation occurs in the very weak tensile tension range up to 5N per 25mm, and the elongation of the initial deformation region increases.

The glass cloth of the present embodiment has a small elongation in the initial deformation region, as compared with a conventional glass cloth of the 1017 type for L glass. Fig. 2 shows a load-elongation curve of the glass cloth C obtained in example 3. The glass cloth C of the present invention has a small elongation up to 5N in the weft direction, and the elongation in the initial deformation region is suppressed to be small. This suggests that the warp and weft have a strong binding force with respect to each other at the crossing points of the warp and weft.

In order to obtain a thin glass cloth, particularly a glass cloth having a thickness of 16 μm or less, a thin glass fiber having a filament diameter of 4.0 μm or less and a filament number of 50 or less is generally used, and therefore, the binding force between the crossing points of the warp and weft is weak, and the weft is likely to be skewed, but when the sum of the elongations in the glass cloth is 0.50% or less, the binding force between the crossing points of the warp and weft is increased, and the generation of the skew tends to be suppressed.

As described above, when the sum of the elongation in the weft direction generated when a load of 5N is applied in the weft direction per 25mm width and the elongation in the warp direction generated when a load of 5N is applied in the warp direction per 25mm width is 0.50% or less, the binding force between the warp and weft at the crossing point increases, and a glass cloth in which skewing is not easily generated can be formed.

On the other hand, the lower limit of the sum of the elongations is preferably 0.30% or more, more preferably 0.33% or more, and still more preferably 0.35% or more. When the sum of the elongations is 0.30% or more, the glass cloth having a woven structure is likely to be relaxed because the deformation due to the stress applied to the glass cloth is reversibly changed by the structure of the glass cloth with the crossing points of the warp and weft as base points, and the generation of wrinkles and breakage can be suppressed.

When the sum of the elongations is in the range of 0.30% to 0.50%, the glass cloth tends to be free from wrinkles and skewness and to have excellent handling properties.

In addition, one of the embodiments is a glass cloth having a thickness of 8 μm to 16 μm, which is formed by using glass filaments including a plurality of glass filaments as warp filaments and weft filaments,

Y＝F/(25000/G)×100 (1)

the weft skew amount of the weft is not more than a value obtained by dividing a value 10 times the interval of the weft by 500mm,

The glass cloth is also referred to as glass cloth Q.

The skew amount of the weft is preferably equal to or less than a value obtained by dividing a value 5 times the interval of the weft by 500mm, more preferably equal to or less than a value obtained by dividing a value 2.5 times the interval of the weft by 500mm, and still more preferably equal to or less than a value obtained by dividing a value 1.0 times the interval of the weft by 500 mm. The unit of "weft pitch" in the "value obtained by dividing a value 10 times, 5 times, 2.5 times, or 1.0 times the weft pitch by 500 mm" is μm.

The weft yarn occupancy and the skew amount are preferably 77% to 87%, the skew amount is equal to or less than a value obtained by dividing a value 5 times the interval between weft yarns by 500mm, more preferably 79% to 85%, the skew amount is equal to or less than a value obtained by dividing a value 2.5 times the interval between weft yarns by 500mm, and still more preferably 80% to 84%, and the skew amount is equal to or less than a value obtained by dividing a value 1.0 times by 500 mm.

The interval of the weft in the present embodiment refers to the interval between the weft constituting the glass cloth, and the interval of the weft in the present specification includes the width of the weft itself. Here, fig. 3 is a schematic view showing the intervals of the weft in the glass cloth. a is the filament width and b is the spacing of the weft.

The weft pitch is determined from the weaving density G (root/25 mm) of the weft, and specifically, the weft pitch can be calculated from 25/G (mm) when the unit of the pitch is mm, and can be calculated from 25000/G (μm) when the unit of the pitch is μm.

When the weft occupancy is 75% or more and 90% or less and the weft skew is equal to or less than a value obtained by dividing a value 10 times the interval between the wefts by 500mm, a change in the percentage of glass in the insulator layer through which the transmission line arranged parallel to the wefts passes is suppressed small when forming a printed circuit board, and thus, there is a tendency that a variation in the signal propagation speed can be reduced.

Here, when the weft occupancy is 75% or more and 90% or less, if the weft skew is equal to or less than a value obtained by dividing a value 10 times the interval between the weft yarns by 500mm, the skew between the transmission line and the weft yarns arranged parallel to the weft yarns is suppressed to be small, specifically, the magnitude of the skew between the transmission line and the weft yarns is suppressed to be less than 0.5 times the interval between the weft yarns, and the presence ratio of glass around the transmission line can be maintained at the same transmission line in a long time.

The amount of skew is preferably small, and a skew amount of 0 is desirable, but may exceed 0.

The term "skew amount in the present specification means Z defined by the following formula (I)_N(Z₀、Z₁And Z₂) In order to obtain the maximum value of Z_N。

Z_N＝|(Y_N+1-Y_N)/(X_N+1-X_N)| (I)

(wherein N is 0 to 2, X_N+1-X_NWhen the value of (A) is 0, Z_NIs 0)

In the formula, X₀～X₃And Y₀～Y₃With (X)₀,Y₀)、(X₁,Y₁)、(X₂,Y₂) And (X)₃,Y₃) The combined expression of (a) is defined as shown below.

A glass cloth, a prepreg, or a printed wiring board formed of a plurality of warp yarns and a plurality of weft yarns is used as a sample to be tested, the warp yarn direction of the sample to be tested is set to be Y direction, the direction perpendicular to the Y direction is set to be X direction, and the weft yarn extending from the first warp yarn to the second warp yarn among the first and second warp yarns at both ends of the sample to be tested is defined with the contact point between the first warp yarn and the weft yarn as origin (0,0), that is, (X) is₀,Y₀) Y-axis and X-axis. In addition, the contact point of the second warp and the weft is set as an end point (X)₃,Y₃) With respect to the coordinate Y of the weft on the X-axis and the Y-axis, one of points at which the maximum value and the minimum value are obtained is defined as (X)₁,Y₁) The other is set as (X)₂,Y₂) In this case, the weft yarns are arranged in order (X)₀,Y₀)、(X₁,Y₁)、(X₂,Y₂) And (X)₃,Y₃)。

Z is exemplarily shown below with reference to FIGS. 4 to 6₀、Z₁And Z₂The method of (1). Fig. 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 in fig. 4 to 6.

In FIG. 4, the atoms are arranged in sequence on the weftDot (X)₀,Y₀) The point (X) at which the maximum value of Y is obtained₁,Y₁) Obtaining the point (X) of the minimum value of Y₂,Y₂) And end point (X)₃,Y₃)。Z₀By connecting adjacent 2 points (X)₀,Y₀) And (X)₁,Y₁) Substituted into the above formula (I) to calculate, Z₁By connecting adjacent 2 points (X)₁,Y₁) And (X)₂,Y₂) Substituted into the above formula (I) to calculate, Z₂By connecting adjacent 2 points (X)₂,Y₂) And (X)₃,Y₃) Substituted into the above formula (I).

In FIG. 5, the origin (X) is arranged in order on the weft₀,Y₀) The point (X) at which the maximum value of Y is obtained₁,Y₁) Obtaining the point (X) of the minimum value of Y₂,Y₂) And end point (X)₃,Y₃) Here, (X)₂,Y₂) And (X)₃,Y₃) The same coordinates are shown. Z₀、Z₁And Z₂The calculation can be performed in the same manner as described above with reference to fig. 4.

In addition, (X)₂,Y₂) And (X)₃,Y₃) Showing the same coordinates, Z₂A value of 0 is obtained for the above formula (I).

In FIG. 6, the origin (X) is arranged in order on the weft₀,Y₀) The point (X) at which the maximum value of Y is obtained₁,Y₁) Obtaining the point (X) of the minimum value of Y₂,Y₂) And end point (X)₃,Y₃) Here, (X)₀,Y₀) And (X)₁,Y₁) Show the same coordinates, and (X)₂,Y₂) And (X)₃,Y₃) Showing the same coordinates, Z₀、Z₁And Z₂The calculation can be performed in the same manner as described above with reference to fig. 4.

In addition, (X)₀,Y₀) And (X)₁,Y₁) Since the same coordinates are shown, Z₀A value of 0, Z, is obtained for the above formula (I)₂A value of 0 is also obtained.

While the weft skew amounts described in the examples of patent documents 4 and 5 are average values measured in several points, the maximum weft skew amount in the present embodiment is defined as the weft skew amount in the present embodiment. This is because, in an electronic circuit that needs to synchronize a plurality of signals, there is a possibility that even 1 signal has a deviation in the arrival time of the signal, which may cause a problem of a failure 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 to 500 μm, preferably 380 μm to 480 μm, and more preferably 400 μm to 480 μm.

When the sum of the width of the warp and the width of the weft is 380 μm or more, the contact area between the warp and the weft at the crossing point of the warp and the weft is increased, the binding force between the warp and the weft is increased, and the skewness of the weft is suppressed.

Since the sum of the warp yarn width and the weft yarn width is 500 μm or less, the warp yarn and the weft yarn are not excessively restrained at the crossing points of the warp yarn and the weft yarn, and there is room for the warp yarn and the weft yarn to move appropriately, in a thin glass cloth having a thickness of 16 μm or less, the crossing points are used as base points when stress is applied, and the warp yarn and the weft yarn move, whereby the stress is relaxed, and the occurrence of wrinkles and breakage are suppressed.

In addition, since the line width used in a multilayer wiring board or the like is generally about 0.1mm, in a glass cloth having a weft occupancy of 75% to 90%, the width of the weft is preferably 300 μm or less in order to suppress a change in the percentage of glass in the insulator layer through which the transmission line arranged parallel to the weft passes, and therefore the sum of the width of the warp and the width of the weft is preferably 500 μm or less.

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

(ratio of warp to weft in section 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% to 110%.

The ratio of the cross-sectional height in the warp direction to the cross-sectional height in the weft direction is more preferably 92% to 108%, and still more preferably 95% to 105%.

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 4 or more adjacent warps are continuously fed. Similarly, the cross-sectional height in the weft direction is the cross-sectional height of the glass cloth when the cross-sectional image of the glass cloth is observed so that 4 or more weft threads adjacent to each other continuously enter the glass cloth.

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 uniformity of the presence of the glass and the resin composition in the Z-axis direction, that is, the thickness direction, is improved at the portion where the glass filaments of the insulator layer are present, and thus the variation in 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 preferably 380 to 500 μm, and the ratio of the cross-sectional height in the warp yarn direction to the cross-sectional height in the weft yarn direction is preferably 90 to 110%.

(Density of glass)

The density of the glass constituting the glass cloth of the present embodiment is 2.10g/cm³Above and 2.50g/cm³Below, preferably 2.15g/cm³Above and 2.45g/cm³Less, more preferably 2.20g/cm³Above and 2.40g/cm³The following.

The specific gravity of the E glass cloth which has been generally used in the past is 2.54g/cm³. In order to reduce the dielectric constant and dielectric loss tangent of the glass cloth, the composition of the glass must be changed, and the low dielectric glass is blended with a larger amount of B than E glass cloth₂O₃And (4) substances with smaller specific gravity. Therefore, the density of the glass is reduced, glassThe rigidity of the glass filaments is also reduced. In addition, when glass fibers having a low density and low rigidity are used, deformation such as skewing is likely to occur in the glass cloth.

The passing density was 2.10g/cm³As described above, in the thread width structure of the present embodiment, the occurrence of skewness can be effectively suppressed.

The density through the glass was 2.50g/cm³The following are excellent in low dielectric characteristics.

As for the density of glass, a lot of B was compounded as described above₂O₃The composition of the glass-constituting component, which is a material having a relatively small specific gravity, is controlled to 2.10g/cm³Above and 2.50g/cm³Within the following ranges.

The composition of the glass may be appropriately adjusted, and for example, the glass may have the following composition.

For the Si content of the glass cloth, according to SiO₂The amount of the metal oxide is preferably 40 to 60 mass%, more preferably 45 to 55 mass%, further preferably 47 to 53 mass%, and further preferably 48 to 52 mass%.

For the B content of the glass cloth, according to B₂O₃The content is preferably 15 to 30% by mass, more preferably 17 to 28% by mass, still more preferably 20 to 27% by mass, still more preferably 21 to 25% by mass, and still more preferably 21 to 24% by mass.

For the Al content of the glass cloth, the Al content is₂O₃The content is preferably 10 to 20% by mass, more preferably 11 to 18% by mass, and further preferably 12 to 17% by mass.

The Ca content of the glass cloth is preferably 4 to 12 mass%, preferably 5 to 10 mass%, and more preferably 6 to 9 mass% in terms of CaO.

Examples of the other components include Mg, P, Na, K, Ti, and Zn.

The composition of the glass can be adjusted according to the amount of raw materials used in the production of the glass filaments.

(quality of glass yarn)

The glass cloth of the present embodiment preferably has a warp yarn mass per unit length of 1.40 × 10^-6kg/m is more than or equal to and less than 1.60 multiplied by 10^-6kg/m，The mass per unit length of the weft yarn exceeds 1.65 x 10^-6kg/m and 3.00X 10^-6kg/m or less, and the ratio of the average mass per unit length of the weft to the average mass per unit length of the warp, that is, the ratio of weft to warp (weft/warp ratio) is 1.20 or more and 1.50 or less.

The ratio of the mass per unit length of warp threads to the mass per unit length of weft threads to the above-mentioned average mass is preferably the ratio of warp threads: 1.40X 10^-6kg/m is more than or equal to and less than 1.57 multiplied by 10^-6kg/m, weft: 1.65X 10^-6kg/m is more than or equal to 2.80 multiplied by 10^-6kg/m or less, weft/warp ratio: 1.17 or more and 1.79 or less, and more preferably still warp yarns: 1.40X 10^- ⁶kg/m is more than or equal to and less than 1.55 multiplied by 10^-6kg/m, weft: 1.70X 10^-6kg/m is more than or equal to 2.50 multiplied by 10^-6kg/m or less, weft/warp ratio: 1.21 or more and 1.62 or less.

The glass cloth is subjected to a physical load during the production process, the step of impregnating the glass cloth with a silane treatment agent and then adjusting the amount of the silane agent applied, or the step of opening the glass cloth. In addition, when a prepreg is coated with a glass cloth, a physical load is applied to the glass cloth in a step of impregnating the glass cloth with a coating resin varnish, adjusting the amount of the resin varnish, and drying the resin varnish. In order to stably and continuously convey the glass cloth without cutting in the above-mentioned steps, the warp preferably has a strength of not less than a constant value, and for this purpose, 1.40 × 10 is preferably used^-6kg/m or more of glass fiber. On the other hand, as the warp, the warp yarn having an average mass per unit length of less than 1.60X 10 is used^-6The glass yarn of kg/m can maintain a thickness of 16 μm or less, and can increase the weaving density to 90 or more, for example, so that the occurrence of pinholes tends to be suppressed.

As weft, use is made of a weft having an average mass per unit length of more than 1.65X 10^-6The rigidity of the weft is increased by the kg/m glass yarn, and skewing tends to be easily reduced. The glass fiber used in the weft is preferably large in mass per unit length for excellent rigidity, but the average per unit length is preferably set so as to suppress the thickness of the glass cloth to 16 μm or lessMass of 3.00X 10^-6kg/m or less.

In addition, when the mass ratio of weft to warp is 1.20 or more, the difference between the rigidity of weft and the rigidity of warp increases, and therefore even when the filaments used for weft are thin and have no rigidity, the warp of weft is suppressed small during weaving, and both weft and warp crossing weft can be brought into close contact without any gap. In addition, although the warp state of the weft inserted without a binding force fluctuates in accordance with variations in thread tension acting on the warp in the weaving process, the fluctuation in the warp structure of the weft can be suppressed to be small by increasing the difference in rigidity between the warp and the weft. Therefore, the variation of the "elongation of the initial deformation region" when the stretching tension is applied is small, and the glass cloth having a small skewness tends to be stably obtained.

As a result of the warp yarns being bent more and less, the warp yarns are bent more and less, and the warp yarns and the weft yarns are close to each other in curl amplitude, so that the warp yarns tend to be adjusted in curl amplitude to a range of 50% to 80% of the thickness of the glass cloth and 60% to 90% of the thickness of the glass cloth.

On the other hand, when the mass ratio of the weft to the warp is 1.50 or less, the difference in rigidity between the warp and the weft is prevented from being extremely increased, and the warp structure of the weft is appropriately stored without causing a large difference in the warp structure between the warp and the weft, so that there is a tendency that the anisotropy of dimensional stability and warpage at the time of forming a printed wiring board due to the difference in rigidity between the warp and the weft can be prevented.

When the mass per unit length of the warp yarn, the mass per unit length of the weft yarn, and the mass ratio of the weft yarn to the warp yarn are within the above ranges, there is a tendency that the "elongation of the initial deformation region" at the time of tensile tension can be reduced to a specific range while preventing anisotropy of dimensional stability and warpage at the time of forming a printed wiring board.

(average filament diameter, average filament number)

In the glass cloth of the present embodiment, it is preferable that the average filament numbers of the warp and the weft are substantially the same, the average filament diameter of the warp is 3.7 to 4.3 μm, the average filament diameter of the weft is 4.2 to 5.3 μm, 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 to 1.30.

When the average number of warp and weft filaments and the average filament diameter are within the above ranges, the thickness of the glass cloth is maintained at 16 μm or less, and the printed wiring board is prevented from being anisotropic and warped in dimensional stability, and the rigidity in the weft direction is increased, thereby suppressing skewing.

The ranges of the average filament diameters of the warp and weft and the weft/warp ratio of the average filament diameters are more preferably warp: weft yarns of 3.8 to 4.2 μm: a weft/warp ratio of 4.3 μm or more and 5.2 μm or less in average filament diameter: 1.08 or more and 1.25 or less, and further preferably warp yarns: weft yarns of 3.9 to 4.1 μm: a weft/warp ratio of 4.4 μm or more and 5.1 μm or less in average filament diameter: 1.09 or more and 1.20 or less.

The fact that the average filament numbers of the warp and weft are substantially the same means that the ratio of the filament number of the warp to the filament number of the weft (weft/warp ratio) is in the range of 0.94 or more and 1.06 or less. When the weft/warp ratio of the average number of filaments is 0.94 or more and 1.06 or less, the effect achieved by the large filament diameter of the weft, that is, the rigidity in the weft direction tends to be excellent.

In the present embodiment, when the average number of filaments of the warp and weft is substantially the same, the number of filaments of the warp and weft is preferably 60 or less. When the number of filaments is 60 or less, the filaments are easily spread by physical processing in the glass cloth manufacturing process, and the distribution of the filaments in the Z direction of the glass fiber bundle can be reduced, so that the thickness of the glass cloth can be easily reduced. The number of filaments is preferably small in order to reduce the thickness of the glass cloth, but in the case where the average number of filaments of the warp and weft is substantially the same from the viewpoint of the strength and handling properties of the glass cloth, the lower limit of the number of filaments is preferably 44 or more, more preferably 46 or more, and further preferably 48 or more.

In the glass cloth of the present embodiment, it is preferable that the average filament diameters of the warp and weft are substantially the same, the average number of filaments of the warp is 43 or more and 70 or less, the average number of filaments of the weft is 55 or more and 80 or less, 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 more than 1.25 and 1.50 or less.

The ranges of the average number of filaments of the warp and weft and their ratio (weft/warp ratio) are more preferably warp: 43 or more and 65 or less weft yarns: a weft/warp ratio of 57 or more and 75 or less, the average number of filaments; 1.27 or more and 1.45 or less, and further preferably warp yarns: 45 or more and 60 or less wefts: a weft/warp ratio of 60 or more and 70 or less, average filaments: 1.30 or more and 1.40 or less.

The fact that the average filament diameters of the warp and weft are substantially the same means that the ratio of the filament diameter of the weft to the filament diameter of the warp (weft/warp ratio) is in the range of 0.95 to 1.05. When the weft/warp ratio of the average filament diameter is in the range of 0.95 to 1.05, the effect achieved by the large number of filaments of the weft, that is, the rigidity in the weft direction tends to be excellent.

In the present embodiment, when the average filament diameters of the warp and weft are substantially the same, the filament diameters of the warp and weft are preferably 3.8 μm or more. The rigidity of the glass cloth tends to be enhanced by the warp and weft having an average filament diameter of 3.8 μm or more. In order to increase the rigidity of the glass cloth, it is preferable that the filament diameter is large, but in the case where the average filament diameters of the warp and weft are substantially the same from the viewpoint of the thickness of the glass cloth, the upper limit of the average filament diameters of the warp and weft is preferably 4.4 μm or less, more preferably 4.3 μm or less, and further preferably 4.2 μm or less.

The glass fiber 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 quartz glass (Q glass) can be used.

By using glass fiber yarns having a dielectric constant close to that of the resin impregnated therein as warp yarns and weft yarns, the unevenness 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 nonuniformity 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, basket weave, satin weave, and twill weave. Further, a woven structure using different types of glass filaments may be used. Among them, a plain weave structure is preferable.

The glass cloth of the laminate used for a printed wiring board or the like is usually subjected to a surface treatment with a treatment liquid containing a silane coupling agent, and as the silane coupling agent, a commonly used silane coupling agent can be used, and an acid, a dye, a pigment, a surfactant, or the like can be added as necessary.

As the silane coupling agent, for example, a silane coupling agent represented by the formula (2) is preferably used.

X(R)_3-nSiY_n (2)

In the formula (2), X is an organic functional group having at least one of an amino group and an unsaturated double bond group, Y is each independently an alkoxy group, n is an integer of 1 or more and 3 or less, and R is each 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 3 or more of an amino group and an unsaturated double bond group, and X is more preferably an organic functional group having at least 4 or more of an amino group and an unsaturated double bond group.

The alkoxy group may be in any form, but is preferably an alkoxy group having 5 or less carbon atoms from the viewpoint of stable treatment of the glass cloth.

Specific examples of the silane coupling agent include N-beta- (N-vinylbenzylaminoethyl) -gamma-aminopropyltrimethoxysilane and hydrochloride thereof, N-beta- (N-vinylbenzylaminoethyl) -gamma-aminopropylmethyldimethoxysilane and hydrochloride thereof, N-beta- (N-bis (vinylbenzyl) aminoethyl) -gamma-aminopropyltrimethoxysilane and hydrochloride thereof, N-beta- (N-bis (vinylbenzyl) aminoethyl) -N-gamma- (N-vinylbenzyl) -gamma-aminopropyltrimethoxysilane and hydrochloride thereof, N-beta- (N-benzylaminoethyl) -gamma-aminopropyltrimethoxysilane and hydrochloride thereof, and mixtures thereof, N-beta- (N-benzylaminoethyl) -gamma-aminopropyltriethoxysilane and its hydrochloride, gamma- (2-aminoethyl) aminopropyltrimethoxysilane, gamma- (2-aminoethyl) aminopropyltriethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane and the like, or a mixture thereof.

The silane coupling agent preferably has a molecular weight of 100 to 600, more preferably 150 to 500, and further preferably 200 to 450. Among them, 2 or more silane coupling agents having different molecular weights are preferably used. When the surface of the glass yarn is treated with 2 or more silane coupling agents having different molecular weights, the density of the treating agent in the surface of the glass yarn increases, and the reactivity with the matrix resin tends to be further improved.

The value of the weight loss on ignition of the glass cloth is preferably 0.10 mass% or more and 2.00 mass% or less, more preferably 0.12 mass% or more and 1.50 mass% or less, and still more preferably 0.15 mass% or more and 1.20 mass% or less. The burning weight loss value of the glass cloth is an index for indirectly evaluating the surface treatment amount of the glass cloth by the silane coupling agent.

When the ignition loss weight value is 0.10 mass% or more, the glass cloth is uniformly surface-treated with a silane coupling agent, and therefore the glass cloth has a hard hand and is less likely to have skewness. When the ignition loss weight is 2.00% or less, the glass cloth has a suitably soft hand, and therefore wrinkles are not likely to occur. The ignition weight loss value of the glass cloth was determined according to the method described in JIS R3420.

< method for producing glass cloth >

The method for producing the glass cloth of the present embodiment is not particularly limited, and a method including, for example, the following steps can be suitably exemplified: a covering step of substantially completely covering the surface of the glass filament with a silane coupling agent using a treatment liquid having a silane coupling agent concentration of 0.1 to 3.0 wt%; a fixing step of fixing the silane coupling agent to the surface of the glass filaments by heating and drying; and a fiber opening step for opening the glass fibers of the glass cloth.

As the solvent for dissolving or dispersing the silane coupling agent, any of water and an organic solvent can be used, but water is preferably used as the main solvent from the viewpoint of safety and global environmental protection. As a method for obtaining a treatment liquid using water as a main solvent, a method in which a silane coupling agent is directly charged into water is preferable; a method in which a silane coupling agent is dissolved in a water-soluble organic solvent to form an organic solvent solution, and the organic solvent solution is then poured into water. In order to improve water dispersibility and stability of the silane coupling agent in the treatment liquid, a surfactant may be used in combination.

Examples of the method of applying the silane coupling agent treatment solution to the glass cloth include (i) a method of storing the treatment solution in a bath, and immersing and passing the glass cloth; and (II) a method of directly applying the treatment liquid to a glass cloth by using a roll coater, a die coater, a gravure coater, or the like. In the case of coating by the method (a), the immersion time of the glass cloth in the treatment solution is preferably selected to be 0.5 seconds to 1 minute.

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 cited.

The heating and drying temperature is preferably 90 ℃ or higher, more preferably 100 ℃ or higher so that the reaction between the silane coupling agent and the glass proceeds sufficiently. The heating and drying temperature is preferably 300 ℃ or lower, more preferably 200 ℃ or lower, in order to prevent deterioration of the organic functional group of the silane coupling agent.

The method for opening in the opening step is not particularly limited, and examples thereof include a method of opening a glass cloth by using spray water (high-pressure water opening), a vibration washer, ultrasonic water, a mangle, and the like. In order to keep the total area of the square mesh (baskethall) within a constant range, it is preferable to perform the opening step by spraying water.

When the fiber is opened with the 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 square meshes present in the glass cloth. Here, the water pressure is set to be constant, which means that the difference between the maximum value and the minimum value of the water pressure of the mist set for fiber opening and the actual water pressure is reduced. The step of heating and drying may be provided before or after the opening step.

< prepreg >

One of the embodiments is a prepreg including the glass cloth described in the embodiment and a matrix resin. The prepreg of the present embodiment is a prepreg having a small skewness and a small thickness, 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, and still more preferably 1.0 or less. The lower the difference in the dielectric constants, 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 when the presence ratio of glass and the presence ratio of resin in the insulator layer are different, the nonuniformity of dielectric constant can be reduced, and the variation in signal propagation speed tends to be reduced.

The prepreg using the glass cloth of the present embodiment can be manufactured according to a conventional method. As a method for producing the prepreg of the present embodiment, for example, a method in which a varnish prepared by diluting a matrix resin such as an epoxy resin with an organic solvent is impregnated into a glass cloth of the present embodiment, and then the organic solvent is volatilized in a drying furnace to cure the thermosetting resin to a B stage state, that is, a semi-cured state, thereby obtaining a resin-impregnated prepreg is exemplified.

Examples of the matrix resin include thermosetting resins such as bismaleimide resin, cyanate resin, unsaturated polyester resin, polyimide resin, bismaleimide triazine resin (also referred to as BT resin), and functionalized polyphenylene ether resin; thermoplastic resins such as polyphenylene ether resins, polyether imide resins, liquid crystal polymers (also referred to as LCP) of wholly aromatic polyesters, polybutadiene, and fluorine resins; or a mixed resin thereof. From the viewpoint of improving the dielectric characteristics, heat resistance, solvent resistance and press moldability, the thermoplastic resin may be modified with a thermosetting resin.

The matrix resin may be a resin obtained by mixing an inorganic filler such as silica or aluminum hydroxide, a flame retardant such as bromine, phosphorus, or a metal hydroxide, another silane coupling agent, a heat stabilizer, an antistatic agent, an ultraviolet absorber, a pigment, a colorant, a lubricant, or the like with the resin.

< printed wiring board >

One of the embodiments is a printed wiring board including the prepreg of the embodiment. The printed wiring board according to the present embodiment can be formed with a small positional relationship between the glass fiber and the transmission line, and a small difference in signal propagation speed between the plurality of transmission lines.

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, and still more preferably 1.0 or less. The smaller the difference in the dielectric constants, the more preferable, 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 when the presence ratio of glass in the insulator layer and the presence ratio of the resin composition are different, the nonuniformity of the dielectric constant can be reduced, and thus the variation in signal propagation speed tends to be reduced.

The printed wiring board of the present embodiment can be manufactured according to a conventional method. For example, a step of laminating the prepreg of the present embodiment one by one or a plurality of sheets, attaching copper foils to both surfaces of the resulting laminate, and heating and pressing the laminate to produce a cured copper-clad laminate; a step of forming circuit patterns formed of copper foil on both surfaces of the copper-clad laminate; then, a via hole is formed to ensure electrical connection between the circuit patterns on both sides, whereby a double-sided printed wiring board can be manufactured.

[ examples ]

The present invention will be specifically described below with reference to examples.

The physical properties of the glass cloths in the examples and comparative examples were measured according to JIS R3420.

The elongation in the warp direction and the elongation in the weft direction of the glass cloth were measured according to the method in accordance with JIS 3420.

The skewness of the glass cloth was measured by the method described above according to JIS L1096.

< example 1 >

The warp yarn used had an average filament diameter of 4.0 μm, a number of filaments of 50, a twist number of 1.0Z, and a mass per unit length of 1.46X 10^-6The weft yarn used was an L-glass yarn of kg/m having an average yarn diameter of 4.5 μm, a yarn number of 50, a twist number of 1.0Z and a mass per unit length of 1.83X 10^-6The glass cloth was woven with kg/m of L-glass filaments by using an air jet loom at a weaving density of 93.5 warp filaments/25 mm and 70 weft filaments/25 mm. The L glass (composition: SiO) constituting the glass cloth₂：51％、Al₂O₃：13％、CaO：8％、B₂O₃: 23%) of 2.30g/cm³. The glass cloth of the obtained raw fabric was subjected to heat treatment at 400 ℃ for 24 hours, and desizing was performed. Next, after using N- β - (N-vinylbenzylaminoethyl) - γ -aminopropyltrimethoxysilane: SZ6032(Dow Corning Toray company) in the treatment liquid impregnated with glass cloth, extrusion, dried at 120 degrees C for 1 minutes, and high pressure water spray implementation of fiber, get the quality of 10.7g/m²And a glass cloth A having a thickness of 13 μm.

The glass cloth a had warp and weft widths of 140 μm and 286 μm, respectively, a weft occupancy of 80%, an elongation in the warp direction of 0.22%, an elongation in the weft direction of 0.27%, and a ratio of a cross-sectional height in the warp direction to a cross-sectional height in the weft direction of 0.97. The glass cloth A had a weft bias of 3mm and was excellent in handling property.

The glass cloth A was processed to a width of 650mm for a coating test, and prepreg coating was performed using an epoxy resin varnish. The epoxy varnish was prepared as follows: the epoxy resin composition was compounded with 80 parts by mass of a low-brominated bisphenol a type epoxy resin, 20 parts by mass of a cresol novolak type epoxy resin, 2 parts by mass of dicyandiamide, 0.2 part by mass of 2-ethyl-4-methylimidazole, and 100 parts by mass of 2-methoxy-ethanol. The glass cloth was conveyed at a speed of 3 m/min, the glass cloth a was impregnated in the epoxy resin varnish, excess varnish was scraped off through a slit having gaps adjusted so that the resin content became 68 mass%, and then dried at a drying temperature of 170 ℃ for a drying time of 1 minute and 30 seconds to semi-cure (B stage) the epoxy resin, thereby obtaining a prepreg a.

The prepreg A was cut into a size of 550mm × 550mm, and then copper foils having a thickness of 35 μm were disposed on both surfaces of the prepreg A, followed by heating at 175 ℃ and 40kgf/cm²Compression molding was performed to obtain a substrate a. The obtained substrate a was subjected to etching treatment, and processed so that lines of copper foil having a width of 200 μm were arranged at right angles to the warp, to obtain an evaluation substrate a.

The distance at which the copper foil thread and the weft thread were shifted within 0.5 times the interval between the weft threads was evaluated based on the position 2cm from the end of the copper foil thread, and the result was 70 mm.

< example 2 >

Weaving of a glass cloth and subsequent treatment were carried out in the same manner as in example 1 except that the weaving density of weft was 75 threads/25 mm, to obtain a mass of 11.1g/m²And a glass cloth B having a thickness of 14 μm. The glass cloth B had warp and weft widths of 138 μm and 276 μm, respectively, a weft occupancy of 83%, an elongation in the warp direction of 0.19%, an elongation in the weft direction of 0.25%, and a ratio of a cross-sectional height in the warp direction to a cross-sectional height in the weft direction of 1.00. The glass cloth B had a weft bias of 1mm and was excellent in handling property.

An evaluation substrate B was produced in the same manner as in example 1, and the distance between the copper foil threads and the weft threads was within 0.5 times the interval between the weft threads, which was 202 mm.

< example 3 >

Weaving of a glass cloth and subsequent treatment were carried out in the same manner as in example 1 except that the weaving density of weft was set to 78 threads/25 mm, to obtain a mass of 11.2g/m²And a glass cloth C having a thickness of 14 μm. The glass cloth C had warp and weft widths of 138 μm and 277 μm, respectively, a weft occupancy of 86%, an elongation in the warp direction of 0.19%, an elongation in the weft direction of 0.23%, and a ratio of a cross-sectional height in the warp direction to a cross-sectional height in the weft direction of 1.03. The glass cloth C had a weft bias of 0.5mm and was excellent in handling property.

An evaluation substrate C was produced in the same manner as in example 1, and the distance between the copper foil threads and the weft threads was within 0.5 times the interval between the weft threads, which was 415 mm.

< example 4 >

The weft yarn used had an average filament diameter of 4.0 μm, a number of filaments of 67, a twist number of 1.0Z, and a mass per unit length of 1.95X 10^-6Weaving of a glass cloth and subsequent treatment were carried out in the same manner as in example 1 except that the weaving density of weft was 68 pieces/25 mm using a kg/m L glass yarn, to obtain a mass of 11.0g/m²And a glass cloth D having a thickness of 13 μm. The glass cloth D had warp and weft widths of 150 μm and 287 μm, respectively, a weft occupancy of 78%, an elongation in the warp direction of 0.19%, an elongation in the weft direction of 0.26%, and a ratio of a cross-sectional height in the warp direction to a cross-sectional height in the weft direction of 1.06. The glass cloth D had a weft bias of 2.5mm and was excellent in handling property.

An evaluation substrate D was produced in the same manner as in example 1, and the distance between the copper foil threads and the weft threads was within 0.5 times the interval between the weft threads, which was 91 mm.

< example 5 >

Weaving of a glass cloth and subsequent treatment were carried out in the same manner as in example 4 except that the weaving density of the weft was set to 72 threads/25 mm, to obtain a mass of 11.3g/m²And a glass cloth E having a thickness of 13 μm. The widths of the warp and weft of the glass cloth E were 152 μm and 285 μm, a weft occupancy of 82%, an elongation of 0.20% in the warp direction, an elongation of 0.25% in the weft direction, and a ratio of the cross-sectional height in the warp direction to the cross-sectional height in the weft direction of 1.03. The glass cloth E had a weft bias of 1.5mm and was excellent in handling property.

An evaluation substrate E was produced in the same manner as in example 1, and the distance at which the copper foil threads and the weft threads were deviated within 0.5 times the interval between the weft threads was evaluated to be 157 mm.

< example 6 >

Weaving of a glass cloth and subsequent treatment were carried out in the same manner as in example 4 except that the weaving density of weft was 75 threads/25 mm, to obtain a mass of 11.8g/m²And a glass cloth F having a thickness of 14 μm. The glass cloth F had yarn widths of the warp and weft of 149 μm and 282 μm, respectively, an occupancy of the weft of 85%, an elongation of 0.20% in the warp direction and an elongation of 0.24% in the weft direction, and a ratio of a cross-sectional height in the warp direction to a cross-sectional height in the weft direction was 1.03. The glass cloth F had a weft bias of 1.5mm and was excellent in handling property.

An evaluation substrate F was produced in the same manner as in example 1, and the distance between the copper foil threads and the weft threads was within 0.5 times the interval between the weft threads, which was 165 mm.

< comparative example 1 >

The warp and weft yarns used had an average filament diameter of 4.0 μm, a filament number of 50, a twist number of 1.0Z, and a mass per unit length of 1.47X 10^-6The glass cloth was woven with kg/m of L-glass filaments by using an air jet loom at a weaving density of 93.5 warp filaments/25 mm for both warp and weft filaments. The glass cloth of the obtained raw fabric was subjected to heat treatment at 400 ℃ for 24 hours, and desizing was performed. Next, after using N- β - (N-vinylbenzylaminoethyl) - γ -aminopropyltrimethoxysilane: SZ6032(Dow Corning Toray) treatment solution in soaking glass cloth, extruding, drying at 120 deg.C for 1 min, and high pressure water spray spreading, to obtain a mass of 11.1g/m²And a glass cloth G having a thickness of 14 μm.

The glass cloth G had a warp and weft width of 133 μm and 224 μm, respectively, a weft occupancy of 84%, an elongation in the warp direction of 0.19%, an elongation in the weft direction of 0.39%, and a ratio of a cross-sectional height in the warp direction to a cross-sectional height in the weft direction of 1.14. The glass cloth G had a weft inclination of 7mm and was a glass cloth with a large weft inclination.

An evaluation substrate G was produced in the same manner as in example 1, and the distance between the copper foil threads and the weft threads was within 0.5 times the interval between the weft threads, which resulted in 23 mm.

< comparative example 2 >

The warp yarn used had an average filament diameter of 4.0 μm, a number of filaments of 40, a twist number of 1.0Z, and a mass per unit length of 1.17X 10^-6The weft yarn used was an L-glass yarn of kg/m having an average yarn diameter of 4.0. mu.m, a yarn number of 50, a twist number of 1.0Z and a mass per unit length of 1.47X 10^-6The glass cloth was woven with kg/m of L-glass filaments by using an air jet loom at a weaving density of 95 warp filaments/25 mm for both warp and weft filaments. The glass cloth of the obtained raw fabric was subjected to heat treatment at 400 ℃ for 24 hours, and desizing was performed. Next, after using N- β - (N-vinylbenzylaminoethyl) - γ -aminopropyltrimethoxysilane: SZ6032(Dow Corning Toray) treatment solution in soaking glass cloth, extruding, drying at 120 deg.C for 1 min, and high pressure water spray spreading, to obtain quality of 9.2g/m²And a glass cloth H with a thickness of 14 μm.

The glass cloth H had warp and weft widths of 124 μm and 215 μm, respectively, a weft occupancy of 82%, an elongation of 0.25% in the warp direction, an elongation of 0.34% in the weft direction, and a ratio of a cross-sectional height in the warp direction to a cross-sectional height in the weft direction of 0.97. The glass cloth H has a skewness of 10mm and is a glass cloth with a large skewness.

An evaluation substrate H was produced in the same manner as in example 1, and the distance between the copper foil threads and the weft threads was 13mm as a result of the deviation satisfying 0.5 times or less the interval between the weft threads.

< comparative example 3 >

The warp and weft yarns used had an average filament diameter of 4.0 μm, a filament number of 50, a twist number of 1.0Z, and a mass per unit length of 1.47X 10^-6kg/m of L-glass yarn, using an air jet loom, with warp yarn,The wefts are all made of glass cloth with the weaving density of 85 pieces/25 mm. The glass cloth of the obtained raw fabric was subjected to a splitting process by a high-pressure water jet under a tension of 4.9N/m (processing pressure 196N/cm)²) A method. Then, heat treatment was performed at 400 ℃ for 24 hours to desize the fibers. Next, after using N- β - (N-vinylbenzylaminoethyl) - γ -aminopropyltrimethoxysilane: a glass cloth was immersed in a treatment solution of SZ6032 (manufactured by Dow Corning Toray Co., Ltd.), squeezed, and dried at 120 ℃ for 1 minute to obtain a mass of 9.7g/m²And a glass cloth I with a thickness of 12 μm. The chemical and physical treatment of the glass cloth is described in patent document 4: the method of example 2 of Japanese patent No. 3756066.

The glass cloth I had a warp and weft width of 185 μm and 202 μm, respectively, a weft occupancy of 69%, an elongation in the warp direction of 0.27%, an elongation in the weft direction of 0.42%, and a ratio of a cross-sectional height in the warp direction to a cross-sectional height in the weft direction of 1.06. The weft skew amount of the glass cloth I is 8mm, and the glass cloth I is glass cloth with large weft skew.

An evaluation substrate I was produced in the same manner as in example 1, and the distance between the copper foil threads and the weft threads was within 0.5 times the interval between the weft threads, which was 17 mm.

< comparative example 4 >

The warp and weft yarns used had an average filament diameter of 4.0 μm, a filament number of 40, a twist number of 1.0Z, and a mass per unit length of 1.17X 10^-6The glass cloth was woven with kg/m of L-glass filaments by using an air jet loom at a weaving density of 94.5 warp filaments/25 mm for both warp and weft filaments. The glass cloth of the obtained raw fabric was subjected to a splitting process by a high-pressure water jet under a tension of 4.9N/m (processing pressure 196N/cm)²) A method. Then, heat treatment was performed at 400 ℃ for 24 hours to desize the fibers. Next, a glass cloth was immersed in a treatment solution containing SZ6032 (manufactured by Dow Corning Toray Co.) as a silane coupling agent, squeezed, and dried at 120 ℃ for 1 minute to obtain a glass cloth having a mass of 9.0g/m²And a glass cloth J having a thickness of 11 μm. The chemical and physical treatment of the glass cloth is described in patent document 4: the method of example 2 of Japanese patent No. 3756066.

The glass cloth J had warp and weft widths of 158 μm and 177 μm, respectively, a weft occupancy of 67%, an elongation in the warp direction of 0.17%, an elongation in the weft direction of 0.37%, and a ratio of a cross-sectional height in the warp direction to a cross-sectional height in the weft direction of 1.09. The weft skew amount of the glass cloth J is 8mm, and the glass cloth is large in weft skew.

An evaluation substrate J was produced in the same manner as in example 1, and the distance between the copper foil threads and the weft threads was within 0.5 times the interval between the weft threads, which was 15 mm.

< comparative example 5 >

The weft yarn used had an average filament diameter of 4.5 μm, a number of filaments of 50, a twist number of 1.0Z, and a mass per unit length of 1.83X 10^-6Weaving of a glass cloth and subsequent treatment were carried out in the same manner as in comparative example 1 except that the weaving density of the L-shaped glass filaments of kg/m and the weft filaments was 60 filaments/25 mm, to obtain a mass of 10.1g/m²And a glass cloth K with a thickness of 12 μm.

The glass cloth K had warp and weft widths of 135 μm and 267 μm, respectively, a weft occupancy of 64%, an elongation in the warp direction of 0.21%, an elongation in the weft direction of 0.29%, and a ratio of a cross-sectional height in the warp direction to a cross-sectional height in the weft direction of 1.09. The weft skew amount of the glass cloth K is 6mm, and the glass cloth K is glass cloth with large weft skew.

An evaluation substrate K was produced in the same manner as in example 1, and the distance between the copper foil threads and the weft threads was 31mm as a result of the evaluation, which was within 0.5 times the interval between the weft threads.

Table 1 shows the characteristics and evaluation results of the glass cloths and substrates produced in examples and comparative examples.

[ Table 1]

Industrial applicability

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

Claims

1. A glass cloth having a thickness of 8 to 16 [ mu ] m, which is formed by using glass filaments comprising a plurality of glass filaments as warp filaments and weft filaments,

Y＝F/(25000/G)×100 (1)

in the formula (1), F is the width of the weft yarn and has a unit of μm, G is the weaving density of the weft yarn and has a unit of root/25 mm,

the sum of the width of the warp and the width of the weft is 380 to 500 μm,

the density of the glass constituting the warp and weft was 2.10g/cm³Above and 2.50g/cm³The following.

2. The glass cloth according to claim 1, wherein a sum of an elongation in the warp direction which occurs when a load of 5N is applied per 25mm width in the warp direction and an elongation in the weft direction which occurs when a load of 5N is applied per 25mm width in the weft direction is 0.50% or less.

3. A glass cloth having a thickness of 8 to 16 [ mu ] m, which is formed by using glass filaments comprising a plurality of glass filaments as warp filaments and weft filaments,

Y＝F/(25000/G)×100 (1)

the weft skew amount of the weft is not more than a value obtained by dividing a value 10 times the interval of the weft by 500mm, wherein the unit of the interval of the weft is mum,

4. Glass cloth according to claim 3, wherein the weft skew amount of the weft is a value obtained by dividing a value 5 times the interval of the weft by 500mm or less, wherein the unit of the interval of the weft is μm.

5. Glass cloth according to claim 3, wherein the weft skew amount of the weft is a value obtained by dividing a value 2.5 times the interval of the weft by 500mm or less, wherein the interval of the weft is in μm.

6. Glass cloth according to claim 3, wherein the weft skew amount of the weft is a value obtained by dividing a value 1.0 times the interval of the weft by 500mm or less, wherein the interval of the weft is in μm.

7. Glass cloth according to any one of claims 3 to 6, wherein the sum of the widths of the warp yarns and the weft yarns is 380 μm or more and 500 μm or less.

8. The glass cloth according to claim 7, wherein a sum of an elongation in the warp direction generated when a load of 5N is applied per 25mm width in the warp direction and an elongation in the weft direction generated when a load of 5N is applied per 25mm width in the weft direction is 0.50% or less.

9. The glass cloth according to claim 1 or 2, wherein a ratio of a cross-sectional height in the warp direction to a cross-sectional height in the weft direction is 90% or more and 110% or less.

10. Glass cloth according to any one of claims 3 to 6, wherein the sum of the widths of the warp yarns and the widths of the weft yarns is 380 μm or more and 500 μm or less,

11. The glass cloth according to any one of claims 1 to 10, having a dielectric constant of 5 or less at 10 GHz.

12. Glass cloth according to any of claims 1 to 11, wherein the warp filaments have an average mass per unit length of 1.40 x 10^-6kg/m is more than or equal to and less than 1.60 multiplied by 10^-6kg/m，

the ratio of the average mass per unit length of the weft to the average mass per unit length of the warp, i.e., the weft/warp ratio, is 1.20 to 1.50.

13. Glass cloth according to any of claims 1 to 12 wherein the average filament number of the warp and weft is substantially the same and

the average filament diameter of the weft is 4.2-5.3 μm,

the ratio of the average filament diameter of the weft to the average filament diameter of the warp, i.e., the weft/warp ratio, is 1.07 to 1.40.

14. Glass cloth according to any of claims 1 to 12 wherein the warp and weft have substantially the same average filament diameter and

the average number of filaments of the warp yarn is 45 to 70,

the average number of filaments of the weft is 55 to 80,

the ratio of the average number of weft filaments to the average number of warp filaments, i.e., the weft/warp ratio, is greater than 1.25 and not greater than 1.50.

15. A prepreg having the glass cloth according to any one of claims 1 to 14, and a matrix resin.

16. The prepreg according to claim 15, wherein a difference between a dielectric constant at 10GHz of glass constituting the glass cloth and a dielectric constant at 10GHz of a cured product of the matrix resin is 3 or less.

17. The prepreg according to claim 15, wherein a difference between a dielectric constant at 10GHz of glass constituting the glass cloth and a dielectric constant at 10GHz of a cured product of the matrix resin is 2 or less.

18. The prepreg according to claim 15, wherein a difference between a dielectric constant at 10GHz of glass constituting the glass cloth and a dielectric constant at 10GHz of a cured product of the matrix resin is 1 or less.

19. A printed wiring board having the prepreg of any one of claims 15 to 18.