CN117904775A

CN117904775A - Glass cloth, prepreg and printed wiring board

Info

Publication number: CN117904775A
Application number: CN202311353382.1A
Authority: CN
Inventors: 远藤正朗; 鹤田弘司; 三品一志; 横江智之
Original assignee: Asahi Kasei Corp
Current assignee: Asahi Kasei Corp
Priority date: 2022-10-19
Filing date: 2023-10-19
Publication date: 2024-04-19
Also published as: JP2024060591A

Abstract

Glass cloth, prepreg, and printed wiring board. The object of the present invention is to provide a low dielectric glass cloth with reduced anisotropy of stress-strain characteristics, and a prepreg and a printed wiring board using the low dielectric glass cloth. [ solution ] to provide a glass cloth which is obtained by weaving glass filaments having a filament count of 120 or more and 500 or less as warp filaments and weft filaments and has a thickness of 40 [ mu ] m or more and 100 [ mu ] m or less, wherein the difference between the filament count of warp filaments and the filament count of weft filaments is 3 or less, and the lower limit value of the filament width of warp filaments is represented by the following formula (1): 40 xα+102 … formula (1) { wherein α represents a value obtained by dividing the ratio of the filament width of the warp yarn to the filament width of the weft yarn (warp yarn width/weft yarn width) by the average diameter of the filaments, and the ratio of the warp yarn width to the weft yarn width is 0.125 to 0.142.

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

With the recent advancement of mobile communication systems, AI and IoT, for example, printed wiring boards used in communication devices such as high-end servers, high-end routers and switches, supercomputers, and base stations, and testers, have been demanded to have high-capacity and high-speed data communication and/or signal processing, and to have high reliability. Therefore, there is also a strong demand for glass cloths constituting printed wiring boards, in which dimensional changes, warpage/warpage generation reduction in the printed wiring board manufacturing process, or anisotropy of thermal dimensional changes are reduced.

As a method for improving the dimensional change, warpage and warpage in the printed wiring board manufacturing process, or anisotropy of the heated dimensional change, for example, glass cloths of patent documents 1 to 9 and the like have been proposed.

Patent document 1 discloses a glass cloth having a difference in the warp direction of the glass cloth of 10% or less in the elongation in the warp direction at the time of applying a load of 50N/inch in a stress-strain curve as a glass cloth for improving warp of a substrate at the time of molding a printed wiring board.

Patent document 2 discloses a glass cloth having a thickness of 10 to 50 μm, in which anisotropy in the XY direction is improved, by flattening the glass cloth at a low tension (at least 49n/m per 1 mm) and the cross-sectional shape and the undulation state of warp and weft are the same.

Patent document 3 discloses that a glass cloth having warp and weft filaments that are opened in a balanced manner and having no wrinkles or loop bending is obtained by performing the opening under a condition in which tension does not act.

Patent document 4 discloses that a glass cloth having a yarn diameter larger than that of warp yarn and a weft/warp ratio of 1.01 or more and less than 1.27, which has little anisotropy in dimensional change and little warp/twist, is obtained.

Patent document 5 discloses that a glass cloth excellent in dimensional stability is formed by setting the fabric density to be equal to the warp/weft (the warp/weft ratio is 0.9 to 1.1).

Patent document 6 discloses that a glass cloth having small variation in dimensional change and small anisotropy in the longitudinal and transverse directions can be obtained by adjusting the relationship between the interval between glass filaments, the fabric density and the knitting shrinkage and the bulk density to a specific range.

Patent documents 7 and 8 disclose that glass cloths having large filament widths and small filament gaps for warp and weft yarns reduce variations in dimensional changes.

Patent document 9 discloses that glass filaments having small dimensional changes and glass cloths having small dimensional changes are formed by reducing the deflection of filament widths for warp filaments and weft filaments and by reducing the angle of deflection of mutually intersecting filaments while flattening filament bundles for warp filaments and weft filaments.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2017-132651

Patent document 2: international publication No. 2004/027136

Patent document 3: japanese patent laid-open No. 2002-38367

Patent document 4: international publication No. 2011/024870

Patent document 5: japanese patent laid-open No. 11-10711

Patent document 6: japanese patent laid-open No. 11-10712

Patent document 7: japanese patent laid-open No. 5-28065

Patent document 8: japanese patent laid-open No. 10-37038

Patent document 9: japanese patent laid-open No. 2006-52473

Disclosure of Invention

Problems to be solved by the invention

The glass cloth described in patent document 1 describes that warpage is improved, but anisotropy of stress-strain curve of not even the glass cloth may also be improved. Since the glass cloth is composed of warp and weft, it is not only possible to equalize the elongation in the width direction when a constant load is applied to the warp, but also to improve the anisotropy. Therefore, there is still room for improvement in terms of warpage of the glass cloth described in patent document 1.

The method for improving anisotropy described in patent document 2 is effective for reducing anisotropy in a thin glass cloth having a small number of filaments, but leaves room for improvement in terms of anisotropy of stress-strain curve in a glass cloth having a thickness of 40 μm or more and having a number of filaments exceeding 200.

The method for producing a glass cloth described in patent document 3 describes that the glass cloth is carried while being opened while being held by a support at the upper limit thereof, and that suppression of bending of the coil is effective, but there is a problem that anisotropy of stress-strain curve is not improved.

Although the glass cloth described in patent document 4 has improved anisotropy in stress-strain (SS) characteristics, glass filaments having different numbers of warp filaments and weft filaments are used, and therefore, there are problems such as in-plane variation in resin content and large variation in hole accuracy, and there is a problem of poor practicality.

The glass cloth described in patent document 5 has a problem of anisotropy that SS characteristics cannot be improved even if the fabric densities of warp and weft are the same.

The glass cloths described in patent documents 6 and 7 have a problem in that the difference in fabric density between warp and weft yarns is large, and the hole workability and XY anisotropy of dimensional change by heating are large. In addition, there is a problem in both documents that the anisotropy of the stress-strain curve is not improved if the difference between the densities of the fabrics is large.

The glass cloth described in patent document 8 has a description that variation in dimensional change is suppressed, but is insufficient in anisotropy of stress-strain curve and variation in dimensional change. In addition, since weft occupies a small space and the uniformity of glass distribution in the glass cloth surface is poor, there is a problem of skew, which is not suitable for high-speed mobile communication applications.

The glass cloth described in patent document 9 reduces the dimensional change by reducing the undulation angle at which warp and weft intersect with each other, but does not improve the anisotropy in the warp and weft directions.

The present invention has been made in view of the above-described problems, and an object thereof is to provide a low dielectric glass cloth having reduced anisotropy of stress-strain characteristics, and a prepreg and a printed wiring board using the low dielectric glass cloth.

Solution for solving the problem

The present inventors have intensively studied to solve the above problems, and as a result, have found that the above problems can be solved by setting the warp width and the ratio of the warp width to the weft width within a predetermined range according to the filament diameter, and have completed the present invention.

Namely, the present invention is as follows.

(1)

A glass cloth having a thickness of 40 μm or more and 100 μm or less, which is obtained by weaving glass filaments having a filament count of 120 or more and 500 or less as warp filaments and weft filaments,

The difference between the number of filaments constituting the warp yarn and the number of filaments constituting the weft yarn is 3 or less,

The lower limit value of the yarn width of the warp yarn is equal to or more than a value obtained by the following formula (1),

40 Xα+102 … (1)

{ Formula, α: average diameter (μm) of filaments of warp yarn

The ratio of the width of the warp yarn to the width of the weft yarn (warp yarn width/weft yarn width) divided by the average diameter of the filaments is 0.125 to 0.142.

(2)

The glass cloth according to item 1, wherein a warp width thickness curl shape index obtained by dividing a thickness of the glass cloth by a yarn width of the warp yarn is a value obtained by the following formula (2),

0.2305 Xln (. Alpha.) -0.227 … (2)

{ Formula, α: average diameter (μm) of filaments of warp filaments.

(3)

40 Xα+102 … (1)

{ Formula, α: average diameter (μm) of filaments of warp yarn

The warp width thickness curl shape index obtained by dividing the thickness of the glass cloth by the warp width of the warp is a value obtained by the following formula (2),

0.2305 Xln (. Alpha.) -0.227 … (2)

{ Formula, α: average diameter (μm) of filaments of warp filaments.

(4)

The glass cloth according to any one of items 1 to 3, wherein a difference between a fabric density of the warp yarn and a fabric density of the weft yarn is 5 or less.

(5)

The glass cloth according to any one of items 1 to 4, wherein a sum of a filament width of the warp filaments and a filament width of the weft filaments is 720 μm or more.

(6)

The glass cloth according to any one of items 1 to 5, wherein a weft occupancy Y, which is obtained by the following formula (3) and indicates a ratio of a portion where weft exists in the MD direction, is 88% to 104%,

Y=f/(25000/G) ×100 … (3)

In the expression, F is weft width (μm), and G is fabric density (root/25 mm) of weft.

(7)

The glass cloth according to any one of items 1 to 6, wherein a ratio (A/B ratio) of elongation A in a weft direction, which occurs when a load of 50N is applied to each 25mm width in the weft direction, to elongation B in a warp direction, which occurs when a load of 50N is applied to each 25mm width in the warp direction, is 1.0 to 1.9.

(8)

The glass cloth according to any one of items 1 to 7, wherein the elongation A in the weft direction, which is generated when a load of 50N is applied to each 25mm width in the weft direction, and the elongation B in the warp direction, which is generated when a load of 50N is applied to each 25mm width in the warp direction, are each 0.3% or more and 0.95% or less.

(9)

The glass cloth according to any one of items 1 to 8, which is composed of glass filaments having an elastic modulus of 50GPa to 70 GPa.

(10)

The glass cloth according to any one of items 1 to 9, which is composed of glass filaments having an elastic modulus of 50GPa to 64 GPa.

(11)

A glass cloth having warp and weft yarns composed of glass filaments having a filament count of 120 to 500 inclusive and a thickness of 40 to 100 μm inclusive,

A difference between the number of filaments constituting the warp yarn and the number of filaments constituting the weft yarn is 3 or less, and

The ratio (A/B ratio) of the elongation A in the weft direction generated when a load of 50N is applied to the weft direction per 25mm width to the elongation B in the warp direction generated when a load of 50N is applied to the warp direction per 25mm width is 1.0 to 1.9.

(12)

A glass cloth comprising warp and weft yarns, each of which comprises glass filaments having an average filament number of 120 to 500 and a thickness of 40 μm to 100 μm,

The elongation A in the weft direction generated when a load of 50N is applied to the weft direction per 25mm width and the elongation B in the warp direction generated when a load of 50N is applied to the warp direction per 25mm width are both 0.3% to 0.95%.

(13)

The glass cloth according to item 11 or 12, wherein a weft occupancy Y representing a ratio of a portion where weft exists in the MD, which is obtained by the following formula (3), is 88% or more and 104% or less,

Y=f/(25000/G) ×100 … (3)

(14)

The glass cloth according to any one of items 11 to 13, which is composed of glass filaments having an elastic modulus of 50GPa to 70 GPa.

(15)

The glass cloth according to any one of items 11 to 14, which is composed of glass filaments having an elastic modulus of 50GPa to 64 GPa.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a glass cloth excellent in isotropy of stress-strain characteristics, and a prepreg and a printed wiring board using the glass cloth can be provided.

Drawings

Fig. 1 is a graph showing measurement results of elongation characteristics of 1017 type low dielectric glass cloth (conventional).

Fig. 2 is a graph showing measurement results of elongation characteristics of 1027 type low dielectric glass cloth (conventional).

Fig. 3 is a graph showing measurement results of elongation characteristics of a 1037-type low dielectric glass cloth (conventional).

Fig. 4 is a graph showing measurement results of elongation characteristics of a 1067 type low dielectric glass cloth (conventional).

Fig. 5 is a graph showing measurement results of elongation characteristics of 1078 type low dielectric glass cloth (conventional, comparative example 3).

Fig. 6 is a graph showing measurement results of elongation characteristics of 3313 type low dielectric glass cloth (conventional, comparative example 6).

Fig. 7 is a graph showing measurement results of elongation characteristics of a 2116 type low dielectric glass cloth (conventional, comparative example 8).

Fig. 8 is a graph showing the measurement results of elongation characteristics of 1078 type low dielectric glass cloth (application, example 4).

Fig. 9 is a graph showing the measurement results of elongation characteristics of 3313 type low dielectric glass cloth (application, example 6).

Fig. 10 is a graph showing measurement results of elongation characteristics of a 2116 type low dielectric glass cloth (application, example 8).

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 may be made without departing from the gist thereof.

The technical features of the present embodiment will be described in more detail below.

The glass cloth according to the first embodiment is a glass cloth having a thickness of 40 [ mu ] m or more and 100 [ mu ] m or less, wherein the warp filaments and the weft filaments are composed of glass filaments having a filament count of 120 or more and 500 or less, and a difference between the filament count of the warp filaments and the filament count of the weft filaments is 3 or less.

The lower limit value of the yarn width of the warp yarn is equal to or greater than a value obtained by the following formula (1).

40 Xα+102 … (1)

{ Formula, α: average diameter (μm) of filaments of warp yarn

The glass cloth according to the present embodiment has a warp yarn and weft yarn width as an index within a specific range, and the undulating structure of the warp yarn and weft yarn is within a specific range, whereby the anisotropy of stress-strain characteristics can be reduced. Further, the glass cloth according to the present embodiment is also characterized in that the bulk is eliminated by forming the undulating structure of the warp yarn and the weft yarn within a specific range, and a glass cloth having a small thickness and excellent smoothness can be obtained.

In order to reduce the dimensional change of the printed wiring board or the occurrence of warpage or twist, and to reduce the anisotropy of the dimensional change by heating, a method of enhancing the resistance of the glass cloth as a reinforcing material to tensile stress and simultaneously reducing the longitudinal/transverse anisotropy thereof is effective. The glass cloth has a fabric structure, and has a tensile elongation property in one direction of the X-Y plane, and the elongation thereof is large in a portion depending on the undulation state of the glass yarn in addition to the reinforcing effect derived from the rigidity of the glass yarn. Therefore, it can be said that one of the methods of adjusting the balance of the undulation of the glass filaments constituting the glass cloth and optimizing the elongation characteristics of the X-Y plane is to improve the dimensional stability of the printed wiring board.

The glass cloth according to the present embodiment has a thickness of 40 μm or more and 100 μm or less. The thickness of 40 μm or more can provide strength required for a large-sized printed wiring board or a high-multilayer printed wiring board used for communication equipment such as a high-end server, a high-end router/switch, a supercomputer, a base station, and the like, or a tester. In addition, the number of layers of the high multilayer printed wiring board can be increased by the thickness of 100 μm or less, and the density of the transmission line can be increased while maintaining the thickness of the high multilayer printed wiring board. The thickness of the glass cloth is preferably more than 40 μm, more preferably 41 μm or more, still more preferably 42 μm or more, and on the other hand, preferably 98 μm or less, still more preferably 96 μm or less. The thickness of the glass cloth can be measured by the method described in examples described below.

The glass cloth according to the present embodiment is a glass cloth woven by using glass filaments having a filament number of 120 or more and 500 or less as warp filaments and weft filaments. In the present specification, the filament number may be an average filament number. The average filament number is preferably 140 to 400, more preferably 160 to 300, and still more preferably 180 to 250.

The difference between the number of filaments constituting the warp yarn and the number of filaments constituting the weft yarn is 3 or less, preferably 2 or less, more preferably 1 or less, and still more preferably 0.

The number of filaments is 120 to 500, the difference between the number of filaments of warp and weft is 3 or less, and other conditions according to the present embodiment are satisfied, whereby the elongation behavior when a load is applied to the X-Y plane can be made to approach the warp direction and the weft direction without impairing the surface smoothness, the in-plane uniformity of glass distribution, the hole workability, and the like.

By using glass filaments having 120 filaments or more as warp filaments and weft filaments, a printed wiring board having a large size or a printed wiring board having a high multilayer can be obtained. In addition, although the conventional glass cloth made of glass filaments having an average filament number of 120 or more has a problem of an increase in anisotropy of stress-strain characteristics, the present invention improves the anisotropy of stress-strain characteristics, and thus suppresses dimensional changes or warpage/warpage in the printed wiring board manufacturing process, and/or reduces anisotropy of thermal dimensional changes, thereby improving the reliability of printed wiring.

The average diameter of the filaments of the glass filaments constituting the warp filaments and the weft filaments is preferably 4 μm or more and 9 μm or less. The average diameter of the filaments is more preferably in the range of 4.3 μm to 8 μm, and still more preferably in the range of 4.5 μm to 7.6 μm. When the filament diameter is within the above range and the average number of filaments is within the above range, a glass cloth having a thickness of 40 μm to 100 μm can be formed, and a strength required for a large-sized printed wiring board or a high-multilayer printed wiring board can be obtained, which is preferable.

The average diameter of the filaments can be measured by the method described in examples described later.

The glass cloth according to the present embodiment has a warp yarn width equal to or greater than a value obtained by the following formula (1).

40 Xα+102 (. Mu.m) … formula (1)

{ Formula, α: average diameter (μm) of filaments of warp yarn

The preferred range of the filament width of the warp yarn is not less than the value obtained by the following formula (1B), more preferred range is not less than the value obtained by the following formula (1C), and still more preferred range is not less than the value obtained by the following formula (1D).

40 Xα+103 (. Mu.m) … formula (1B)

40 Xα+104 (. Mu.m) … formula (1C)

40 Xα+105 (. Mu.m) … type (1D)

In the formula, alpha is as defined in the formula (1)

If the width of the warp yarn is equal to or greater than the lower limit value obtained by the above equation 1, the thickness of the warp yarn in the z direction is reduced, and hence the fluctuation of the weft yarn is reduced. In addition, as the fluctuation of the weft yarn decreases, the weft yarn acts on the force that opens the warp yarn alternately in the up-down direction at the intersection point of the warp yarn and the weft yarn, and the fluctuation of the warp yarn increases. Therefore, the fluctuation of the warp yarn and the weft yarn is close, the elongation characteristics of the warp yarn and the weft yarn are close, and the anisotropy of the stress-strain curve is reduced.

In the glass cloth according to the present embodiment, the yarn width of the warp yarn is equal to or less than a value obtained by the following formula (4).

30 Xα+250 (. Mu.m) … type (4)

{ Formula, α: average diameter (μm) of filaments of warp yarn

The preferred range of the filament width of the warp yarn is equal to or less than the value obtained by the following formula (4B), the more preferred range is equal to or less than the value obtained by the following formula (4C), and the more preferred range is equal to or less than the value obtained by the following formula (4D).

30 Xα+240 (. Mu.m) … type (4B)

30 Xα+230 (. Mu.m) … type (4C)

30 Xα+220 (. Mu.m) … type (4D)

{ Formula, α is as defined in formula (4) above }

If the warp width exceeds the upper limit, the weft is required to be greatly fluctuated so as to avoid the warp expanding in the XY direction, and therefore the fluctuated weft is large and the anisotropy of the stress-strain curve is increased. When the warp width is equal to or less than the upper limit, the waviness of the weft is reduced, and the anisotropy of the stress-strain curve is reduced.

There are a plurality of steps such as a pulp washing step and a fiber opening step for producing a glass cloth, in which filament arrangement of filaments constituting warp filaments is varied to change the shape of the filament bundle, for example, a step of performing processing in a state of being initially arranged in water is performed, and in which the warp filaments are uniformly and largely widened, whereby in the subsequent steps, the processing force is reduced as much as possible, and the tension acting on the warp filaments is adjusted to be small to suppress shrinkage of the warp filaments, whereby the lower limit value of the filament width of the warp filaments can be controlled to a value obtained by the formula (1) or more.

In addition, for control of the lower limit value of the warp width, it is also effective to use glass filaments for warp that have uniform twisting quality and that have a small number of portions with narrow twisting intervals due to variation.

The filament widths of warp and weft in the glass cloth are obtained by observing the surface of a glass cloth sample having a size of 100mm×100mm by a microscope, and dividing the total filament width by the total number of the filaments to obtain an average value. In this case, when the filament width of the glass filaments varies in the sample, the width of the portion having the largest width is set as the filament width of the filaments.

In the glass cloth according to the present embodiment, the ratio of the width of the warp yarn to the width of the weft yarn (warp yarn width/weft yarn width) divided by the average diameter of the filaments is 0.125 to 0.142. The preferred range of the warp/weft ratio coefficient is 0.129 to 0.142, more preferred range is 0.132 to 0.141, and still more preferred range is 0.133 to 0.140.

If the warp width is within the range of the present invention and the warp/weft width ratio coefficient is equal to or higher than the lower limit value, the thickness in the z direction of the weft is small, so that the fluctuation of the weft is small, and as a result, the fluctuation of the warp increases, so that the anisotropy of the stress-strain curve is reduced.

If the warp width is within the range of the present invention and the warp/weft width ratio coefficient is equal to or less than the upper limit value, the rigidity of the weft is kept high, and therefore, when the fluctuation of the weft is reduced, the force for opening the warp to the upper limit acts at the intersection point with the warp, and the fluctuation of the warp is increased. The anisotropy of the stress-deformation curve is reduced.

If the warp width is within the range of the present invention and the warp/weft width ratio coefficient is within the above range, the warp is given a undulation, and the undulation of the weft is reduced, so that the anisotropy of the stress-strain curve is reduced.

There are a plurality of steps such as a pulp washing step and a fiber opening step for producing a glass cloth, in which filament arrangement of filament bundles constituting warp filaments is varied to change a filament bundle shape, for example, a step of performing processing in a state of being initially arranged in water, in which the warp filaments are uniformly and largely widened, whereby in the subsequent steps, a processing force is reduced as much as possible, and tension acting on the warp filaments is adjusted to be small to suppress shrinkage or the like, whereby the width of the warp filaments is widened as described above, and simultaneously, by utilizing a weft widening suppressing action by performing the widening of the warp filaments and a weft widening suppressing action by reducing a processing force of the fiber opening step, the weft width is suppressed from being excessively widened, whereby the warp/weft width ratio coefficient can be controlled within the above range.

In addition, for control of the warp/weft width ratio coefficient, it is also effective to use glass filaments having uniform twisting quality and small twisting intervals due to the deviation for warp filaments and/or glass filaments having small twisting intervals due to the deviation for weft filaments.

The glass cloth of the present embodiment preferably has a sum of the warp yarn width and the weft yarn width of 720 μm or more. The sum of the warp width and the weft width is more preferably 730 μm or more, still more preferably 740 μm or more, still more preferably 750 μm or more. The sum of the warp width and the weft width is 720 μm or more, so that the thickness due to the overlapping of the thicknesses of the warp and the weft in the z direction is preferably kept small at the intersection point of the warp and the weft, and the rise and fall of the warp and the rise and the fall of the weft are suppressed, and the elongation of the warp and the weft is preferably reduced.

The glass cloth according to the present embodiment preferably has a weft yarn presence ratio in the longitudinal direction (MD) of 88% or more and 104% or less. The presence ratio of weft yarn in the longitudinal direction is more preferably in the range of 90% to 103%, still more preferably in the range of 91% to 102%, still more preferably in the range of 92% to 102%.

The existence ratio of weft in the longitudinal direction is the weft occupancy, and is obtained by the following formula (3), and is a value Y obtained by dividing the width of weft by the interval of weft.

Y＝F/(25000/G)×100…(3)

(Wherein F is the width of weft yarn (. Mu.m), and G is the fabric density of weft yarn (root/25 mm))

When the weft occupancy is 88.0% or more, the in-plane uniformity and surface smoothness of the glass cloth are excellent, and therefore, the presence ratio of glass and resin becomes more uniform in the insulator layer composed of the glass cloth and resin. Therefore, since the propagation speeds of signals of the plurality of transmission lines formed on the insulator layer tend to be equal, the deviation of arrival times of signals is small, and stable signal processing is possible, and therefore, the glass cloth is preferable for mobile communication systems, AI, ioT applications.

For example, the existence ratio of weft in the longitudinal direction can be controlled within the above range by adjusting the fabric density of weft and adjusting the width of weft in the opening step.

The warp yarn of the glass cloth preferably has a fabric density of 40 yarns/25 mm or more and 70 yarns/25 mm or less. The fabric density of the warp yarn is more preferably in the range of 45 yarns/25 mm to 65 yarns/25 mm, still more preferably in the range of 47 yarns/25 mm to 63 yarns/25 mm, still more preferably in the range of 48 yarns/25 mm to 62 yarns/25 mm.

The difference between the fabric density of warp and weft is preferably 5 or less. The difference between the fabric density of warp yarn and that of weft yarn is more preferably in the range of 4.5 or less, still more preferably in the range of 4.0 or less, still more preferably in the range of 3.5 or less, and particularly preferably in the range of 3.0 or less.

The glass cloth using glass filaments having a filament count within the range of the present invention is preferable because the glass cloth has excellent strength and a thickness of 40 μm or more and 100 μm or less.

By the difference between the fabric density of the warp yarn and the fabric density of the weft yarn being within the above-described range, the yarn width of the warp yarn and the yarn width of the weft yarn are within the scope of the present invention, whereby the anisotropy of the stress-strain characteristics is improved.

The glass cloth of the present invention preferably has a warp width, thickness, and curl shape index, which is obtained by dividing the thickness of the glass cloth by the width of the warp, of a value obtained by the following formula (2).

0.2305 Xln (. Alpha.) -0.227 … (2)

{ Formula, α: average diameter (μm) of filaments of warp yarn

If the curl shape index is smaller than or equal to the value obtained by the formula (2), the fluctuation of the warp yarn and the weft yarn approaches, the elongation characteristics of the warp yarn and the weft yarn approach, and the anisotropy of the stress-strain curve is reduced. Namely, the elongation of the warp yarn increases and the elongation of the weft yarn decreases.

In order to set the warp width, thickness and curl shape index to a value equal to or smaller than the value obtained by the formula (2), a method of controlling the warp width within the range of the present invention is effective. By widening the width of the warp, the thickness of the warp in the z-direction is reduced, as the undulations of the weft along the warp are reduced. By reducing the fluctuation of the weft, the force with which the weft alternately opens the warp in the up-down direction becomes stronger at the intersection point of the warp and the weft, and thus the fluctuation of the warp increases. As a result, the irregularities of the undulations of the warp and weft are smoothly combined, and the thickness is reduced, so that the warp width-thickness curl shape index is easily equal to or less than the value obtained by the formula (2).

In the step of changing the filament arrangement of the filament constituting the warp yarn such as the pulp washing step and the opening step, the condition between the steps is controlled so that the tension or the working force applied to the glass cloth becomes uniform in the width direction, and the warp width variation is adjusted so as to reduce the warp width variation, whereby the warp width thickness crimp coefficient can be controlled within the above range.

When the processing force is increased in the step of performing the processing in a state where the glass cloth or the yarn bundle is immersed in water, it is preferable to widen the yarn width and suppress the variation in the yarn width to be small. The processing force of the subsequent processing is not increased as compared with the processing in a state immersed in water, and is also preferable from the viewpoint of suppressing the expansion of the warp width variation.

As a second embodiment of the glass cloth according to the present invention, there is provided a glass cloth having a thickness of 40 μm or more and 100 μm or less, which is obtained by weaving glass filaments having a filament count of 120 or more and 500 or less as warp filaments and weft filaments, wherein a difference between the filament count of warp filaments and the filament count of weft filaments is 3 or less.

40 Xα+102 … (1)

{ Formula, α: average diameter (μm) of filaments of warp yarn

The warp width, thickness, and curl shape index obtained by dividing the thickness of the glass cloth by the warp width is equal to or less than a value obtained by the following formula (2).

0.2305 Xln (. Alpha.) -0.227 … (2)

{ Formula, α: average diameter (μm) of filaments of warp yarn

The glass cloth according to the first and second embodiments is characterized in that the difference between the elongation in the weft direction and the elongation in the warp direction is small, and the ratio (a/B ratio) between the elongation a in the weft direction generated when a load of 50N is applied to each 25mm width in the weft direction and the elongation B in the warp direction generated when a load of 50N is applied to each 25mm width in the warp direction can be suppressed to 1.0 to 1.9. The ratio (a/B ratio) of the elongation a in the weft direction to the elongation B in the warp direction is preferably 1.0% or more and 1.8% or less, and more preferably 1.0% or more and 1.7% or less.

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

The elongation is a value obtained as follows.

The elongation of the glass cloth when tension is applied in the warp direction or the weft direction was measured according to the method described in general test methods for glass test and items of 7.4 tensile strength in JIS R3420. In the method specified in JIS, test pieces having a width of about 30mm and a length of about 250mm were collected from the warp and weft directions of a fabric, filaments at both ends of the test pieces were unwound to form test pieces having a width of about 25mm, and the test pieces were attached to a nip portion with a nip interval of about 150mm secured, and were stretched at a stretching speed of about 200 mm/min to determine a load at break. In the present invention, in order to improve measurement accuracy, a tensile test was performed under the same conditions as those defined in the above JIS except that the tensile speed was set to about 5 mm/min, and a displacement amount when a 50N load was applied to the glass cloth per 25mm width was obtained, and a value obtained by using the following formula was defined as "elongation".

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

When the ratio (a/B) of the elongation a in the weft direction to the elongation B in the warp direction is within the above range, warpage and warpage in the processing step of the printed wiring board, anisotropy of dimensional change in the processing step, and anisotropy of dimensional change upon heating tend to be improved, and a printed wiring board with high reliability can be obtained, which is preferable.

The glass cloth of the present invention is also characterized in that the elongation in the weft direction and the elongation in the warp direction are both small, and the elongation a in the weft direction and the elongation B in the warp direction, which are both generated when a load of 50N is applied per 25mm width in each yarn direction, can be suppressed to 0.3% or more and 0.95% or less, preferably 0.4% or more, and more preferably 0.5% or more. Further, the elongations a and B are each preferably 0.94% or less, more preferably 0.93% or less.

The elongation a in the weft direction and the elongation B in the warp direction, which are generated when a load of 50N is applied per 25mm width in each yarn direction, can be controlled within the above-described ranges by adjusting the warp width, weft width, and crimp coefficient to be within the scope of the present invention.

When the elongation in the weft direction and the elongation in the warp direction are both equal to or less than the upper limit value, the reinforcing effect of the glass cloth is large, and the occurrence of warpage and warpage of the printed wiring board, dimensional change, and thermal expansion coefficient can be suppressed to be small, which is preferable. In addition, if the elongation in the weft direction and the elongation in the warp direction are both equal to or less than the upper limit value, variations in stress-strain characteristics in the width direction of the glass cloth are suppressed to be small, and the occurrence of defects such as bending of the glass cloth coil, oblique wrinkles, winding wrinkles, and slackening in the glass cloth manufacturing process or in the manufacturing process of the prepreg using the glass cloth is suppressed.

When the elongation in the weft direction and the elongation in the warp direction are both equal to or greater than the lower limit value, stress relaxation such as curing shrinkage or softening of the resin during processing of the printed wiring board is preferable, and warpage and distortion are suppressed. In addition, if the elongation in the weft direction and the elongation in the warp direction are both equal to or greater than the lower limit values described above, the external stress is relaxed even when the glass cloth is processed or when the prepreg using the glass cloth is processed, and therefore, the occurrence of wrinkles and winding wrinkles is preferably suppressed.

As a third embodiment of the present invention, there is provided a glass cloth comprising warp and weft, each of which is composed of glass filaments having a filament count of 120 to 500 inclusive and a thickness of 40 to 100 μm inclusive, wherein a difference between the filament count constituting the warp and the filament count constituting the weft is 3 or less, and a ratio (a/B ratio) of elongation a in the weft direction generated when a load of 50N is applied to the weft direction per 25mm width to elongation B in the warp direction generated when a load of 50N is applied to the warp direction per 25mm width is 1.0 to 1.9.

As a fourth embodiment of the present invention, there is provided a glass cloth comprising warp and weft, each of which is made of glass filaments having an average filament count of 120 to 500 inclusive and a thickness of 40 μm to 100 μm inclusive, wherein a difference between the filament count constituting the warp and the filament count constituting the weft is 3 or less, and wherein both an elongation a in the weft direction, which occurs when a load of 50N is applied to the weft direction per 25mm width, and an elongation B in the warp direction, which occurs when a load of 50N is applied to the warp direction per 25mm width, are 0.3% to 0.95%.

The glass cloths of the third and fourth embodiments may be common to the glass cloths of the first and second embodiments in technical features as necessary. The elastic modulus of glass filaments constituting the glass cloth according to the first to fourth embodiments is preferably 50GPa to 70GPa, more preferably 50GPa to 64GPa, still more preferably 52GPa to 64GPa, still more preferably 54GPa to 60 GPa.

Glass filaments having an elastic modulus of 50GPa to 70GPa tend to have an increased elongation when a load is applied as compared with glass filaments of E glass having an elastic modulus of 74GPa, and the anisotropy of stress-strain characteristics tends to be increased as compared with E glass. Therefore, the effect of reducing the anisotropy of the stress-strain characteristics is large by the present invention, and is preferable. In addition, glass filaments having an elastic modulus in the range of 50GPa to 70GPa are preferable from the viewpoint of easy control of the warp width and weft width within the structural range of the present embodiment because they are easily subjected to external stress.

The elastic modulus of the glass yarn was measured by the method described in examples below.

(Other technical features of glass cloth)

The weave structure of the glass cloth is not particularly limited, and examples thereof include weave structures such as plain weave, basket weave, satin weave, twill weave, and the like. Of these, plain weave structures are more preferred.

The cloth weight (weight per unit area) of the glass cloth is preferably 8 to 250g/m ², more preferably 20 to 150g/m ², still more preferably 30 to 110g/m ², particularly preferably 36 to 100g/m ².

(Surface treatment)

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

The silane coupling agent is not particularly limited, and examples thereof include compounds represented by the formula (I).

X(R)_3-nSiY_n…(I)

(Wherein X is an organic functional group having at least one or more of an amino group and an unsaturated double bond group, Y is an alkoxy group, n is an integer of 1 or more and 3 or less, R is a group selected from the group consisting of methyl, ethyl and phenyl.)

In the formula (I), X is preferably an organic functional group having at least 3 or more of amino groups and unsaturated double bond groups, and X is more preferably an organic functional group having at least 4 or more of amino groups and unsaturated double bond groups.

In the formula (I), any of the above-mentioned alkoxy groups may be used as the Y, but from the viewpoint of stabilizing the glass cloth, an alkoxy group having 5 or less carbon atoms is preferable.

Specific examples of the silane coupling agent include known individual substances such as N- β - (N-vinylbenzyl aminoethyl) - γ -aminopropyl trimethoxysilane and its hydrochloride, N- β - (N-vinylbenzyl aminoethyl) - γ -aminopropyl methyldimethoxysilane and its hydrochloride, N- β - (N-di (vinylbenzyl) aminoethyl) - γ -aminopropyl trimethoxysilane and its hydrochloride, N- β - (N-di (vinylbenzyl) aminoethyl) -N- γ - (N-vinylbenzyl) - γ -aminopropyl trimethoxysilane and its hydrochloride, N- β - (N-benzyl aminoethyl) - γ -aminopropyl triethoxysilane, γ - (2-aminoethyl) aminopropyl trimethoxysilane, γ - (2-aminoethyl) aminopropyl triethoxysilane, aminopropyl trimethoxysilane, vinyltrimethoxysilane, methacryloxypropyl trimethoxysilane, acryloxypropyl trimethoxysilane and the like, and mixtures thereof.

[ Method for producing glass cloth ]

The method for producing the glass cloth according to the present embodiment is not particularly limited, and examples thereof include a weaving step of weaving glass filaments to obtain the glass cloth and a fiber-opening step of opening the glass filaments of the glass cloth. The method for producing a glass cloth may further include a desizing step of removing a sizing agent of glass filaments attached to the glass cloth and a surface treatment step using a silane coupling agent, as required.

The weaving method is not particularly limited as long as the weft yarn and the warp yarn are woven so as to form a predetermined weaving structure. The fiber opening method is not particularly limited, and examples thereof include a method of opening using spray water (high-pressure water for fiber opening), a vibration washer, ultrasonic water, a calender, and the like. Further, the desizing method is not particularly limited, and examples thereof include a method of washing and removing the sizing agent with spray water (high-pressure water-splitting), a vibration washer, ultrasonic water, or the like; and (3) a method for heating and removing the sizing agent. Further, as a surface treatment method, a method of bringing a surface treatment agent containing a silane coupling agent into contact with a glass cloth, drying the glass cloth, and the like can be mentioned. The contact of the surface treatment agent with the glass cloth may be a method of immersing the glass cloth in the surface treatment agent; a method of applying a surface treatment agent to a glass cloth using a roll coater, a die coater, a gravure coater, or the like. The method of drying the surface treatment agent is not particularly limited, and examples thereof include hot air drying and drying using electromagnetic waves.

The yarn width of the warp yarn and the yarn width of the weft yarn can be adjusted by adjusting the fabric density during weaving, the tension applied to the warp yarn during weaving, the weft yarn beating-up pressure during weaving, the opening force applied to the warp yarn during the opening process, the tension applied to the warp yarn, the desizing force applied to the desizing process, and the tension applied to the warp yarn.

[ Prepreg ]

The prepreg of the present embodiment includes the glass cloth described above and a matrix resin composition impregnated into the glass cloth.

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

Examples of the matrix resin composition include thermosetting resins such as bismaleimide resins, cyanate resins, unsaturated polyester resins, polyimide resins, bismaleimide-triazine resins (BT resins), and functionalized polyphenylene ether resins, in addition to the epoxy resins described above; thermoplastic resins such as polyphenylene ether resins, polyetherimide resins, liquid Crystal Polymers (LCPs) of wholly aromatic polyesters, polybutadiene, and fluororesin; and their mixed resins, etc. From the viewpoints of improving dielectric characteristics, heat resistance, solvent resistance, and press formability, a resin obtained by modifying a thermoplastic resin with a thermosetting resin can be used as the matrix resin composition.

In addition, the matrix resin composition may contain in the resin: inorganic fillers such as silica and aluminum hydroxide; flame retardants such as brominated flame retardants, phosphorus flame retardants, metal hydroxides, and the like; other silane coupling agents; a heat stabilizer; an antistatic agent; an ultraviolet absorber; a pigment; a colorant; lubricants, and the like.

[ Printed wiring Board ]

The printed wiring board of the present embodiment includes the prepreg. The printed wiring board provided with the prepreg according to the present embodiment has a high yield of the final product and can provide supply stability.

Examples (example)

The present invention will be specifically described below by way of examples.

< Properties of glass cloth >

The physical properties of glass filaments and glass cloth, specifically, the thickness of glass cloth, and the beat-up density (fabric density) of warp filaments and weft filaments were measured according to JIS R3420. The filament width of the warp yarn and the filament width of the weft yarn of the glass cloth were measured according to the methods described above. The elongation in the warp direction and the elongation in the weft direction of the glass cloth were measured according to the method described above in accordance with JIS 3420.

[ Average diameter of filaments of glass filaments ]

Measured according to the A method of JIS R3420.

The sizing agent was removed from the glass strands by first heat treatment with an electric furnace at 625℃for 20 minutes. The glass filaments were then cut to a length of 25mm or less, placed on a slide, and then opened to a filament state. The diameter of the filaments was measured as the distance between the contours of the filaments by observation with a microscope. The diameters of 25 filaments were randomly measured, and the average value thereof was found as the average diameter of the filaments.

[ Modulus of elasticity ]

The elastic modulus was measured by a pulse echo method using a glass block obtained by melting and cooling glass filaments used for warp filaments and weft filaments as a test piece.

Comparative example 1 >

The warp yarn and weft yarn were each made of a low dielectric glass yarn (LCD 510, manufactured by AGY corporation) having an average filament diameter of 5.1 μm and a filament count of 200 filaments, and a glass cloth (grey cloth) having a warp yarn count of 53 filaments/25 mm and a weft yarn count of 53 filaments/25 mm was woven using an air jet loom.

The obtained grey cloth was subjected to pulp washing with an oscillating washer and fiber opening with high-pressure water spray. Then, the glass cloth was immersed in a treatment solution using a silane coupling agent as a surface treatment agent after desizing by heating at 400℃for 24 hours, and dried at 120℃for 1 minute after squeezing. Further, a glass cloth having a width of 1285mm was obtained by conducting a fiber opening process by high-pressure water spraying.

The average value of the number of turns of the glass yarn used in the warp yarn of comparative example 1 was 0.89 to 1.05, and the standard deviation of the number of turns was 0.05 to 0.33.

Example 1 >

Glass yarns having a standard deviation of 0.135 or less (average value of twist number of 0.93 to 1.02) were used as selected yarns, and glass cloths were produced in the same manner as in comparative example 1 except that the working force (rotational speed of the chrysanthemum roller was 1.5 times as compared with comparative example 1 and the punching ratio was 1.04 times as compared with comparative example 1) by the oscillating washer in the slurry washing step was increased, and the line tension and the spray pressure (line tension: 0.6 times as compared with comparative example 1 and spray pressure: 0.5 times as compared with comparative example 1) in the fiber opening step after the silane coupling agent treatment were reduced, to obtain glass cloths having a width of 1285 mm.

When the glass cloth is conveyed in the air, a difference occurs in tension acting on the warp yarn in the width direction due to the influence of the self weight acting on the glass cloth. If processing for changing the filament arrangement of the warp yarn is performed in this state, the processing state of the warp yarn differs in the width direction. In this embodiment, the processing force of the oscillating washer for immersing the glass cloth in water to process is enhanced, and the opening processing force for processing while conveying the glass cloth in air is reduced, thereby controlling the processing to vary the filament arrangement of the warp filaments so as to be uniform in the width direction.

Example 2 >

Glass cloth was produced in the same manner as in comparative example 1 except that the working force (the rotational speed of the chrysanthemum roller was 1.7 times as high as that of comparative example 1 and the punching ratio was 1.06 times as high as that of comparative example 1) by the oscillating washer in the slurry washing step was increased, and the line tension and the spray pressure (line tension: 0.55 times as high as that of comparative example 1 and spray pressure: 0.4 times as high as that of comparative example 1) in the fiber opening step after the silane coupling agent treatment were reduced, whereby glass cloth having a width of 1285mm was obtained.

Example 3 >

Glass cloth was produced in the same manner as in example 2 except that the working force (the rotational speed of the chrysanthemum roller was 2.0 times as high as that of comparative example 1 and the punching ratio was 1.09 times as high as that of comparative example 1) by the oscillating washer in the slurry washing step was increased, and the line tension and the spray pressure (line tension: 0.5 times as high as that of comparative example 1 and spray pressure: 0.3 times as high as that of comparative example 1) in the fiber opening step after the silane coupling agent treatment were reduced, to thereby obtain glass cloth having a width of 1285 mm.

Example 4 >

Glass cloth was produced in the same manner as in example 2 except that the working force (the rotational speed of the chrysanthemum roller was 2.5 times as high as that of comparative example 1 and the punching ratio was 1.14 times as high as that of comparative example 1) by the oscillating washer in the slurry washing step was increased, and the line tension and the spray pressure (line tension: 0.4 times as high as that of comparative example 1 and spray pressure: 0.2 times as high as that of comparative example 1) in the fiber opening step after the silane coupling agent treatment were reduced, to thereby obtain glass cloth having a width of 1285 mm.

Comparative example 2 >

Glass cloth was produced in the same manner as in comparative example 1 except that the processing force (the rotational speed of the chrysanthemum roller was 0.5 times as high as that of comparative example 1 and the punching ratio was 0.96 times as high as that of comparative example 1) by the oscillating washer in the slurry washing step was reduced, and glass cloth having a width of 1285mm was obtained.

Comparative example 3 >

Glass cloth was produced in the same manner as in comparative example 1 except that glass filaments having a standard deviation of the number of turns of 0.135 or less (average value of the number of turns: 0.93 to 1.02) were used, to obtain glass cloth having a width of 1285 mm.

Comparative example 4 >

Glass cloth was produced in the same manner as in comparative example 1 except that the processing force (the rotational speed of the chrysanthemum roller was 2.5 times as high as that of comparative example 1 and the punching ratio was 1.14 times as high as that of comparative example 1) by the oscillating washer in the slurry washing step was increased, and glass cloth having a width of 1285mm was obtained.

Comparative example 5 >

Glass cloth was produced in the same manner as in comparative example 1 except that the line tension and the spray pressure (line tension: 0.4 times as compared with comparative example 1, spray pressure: 0.2 times as compared with comparative example 1) in the fiber opening step after the silane coupling agent treatment were reduced, and glass cloth having a width of 1285mm was obtained.

Example 5 >

Glass cloth having a width of 1285mm was obtained in the same manner as in example 4, except that glass filaments (manufactured by AGY Co., ltd., LCD520, elastic modulus 56 GPa) having an average filament diameter of 5.1 μm and a filament number of 200 were used as both warp and weft, and glass filaments having a standard deviation of the selected twist number of warp of 0.135 or less (average value of twist number of 0.93 to 1.02) were used.

Comparative example 6 >

The warp yarn and weft yarn were each made of a low dielectric glass yarn (LCDE, manufactured by AGY Co., ltd., elastic modulus: 61 GPa) having an average filament diameter of 6.2 μm and a filament count of 200, and a glass cloth (grey cloth) having a warp yarn count of 59 pieces/25 mm and a weft yarn count of 61.5 pieces/25 mm was woven using an air jet loom.

The obtained grey cloth was subjected to pulp washing and fiber opening treatment by high-pressure water spraying. Then, the glass cloth was immersed in a treatment solution using a silane coupling agent as a surface treatment agent after desizing by heating at 400℃for 24 hours, and dried at 120℃for 1 minute after squeezing. Further, a glass cloth having a width of 1285mm was obtained by conducting a fiber opening process by high-pressure water spraying.

The average value of the number of turns of the glass yarn used in the warp yarn of comparative example 6 was 0.90 to 1.05, and the standard deviation of the number of turns was 0.05 to 0.29.

Example 6 >

Glass yarns having a standard deviation of 0.135 or less (average value of twist number of 0.92 to 1.02) were used as selected yarns, and glass cloths were produced in the same manner as in comparative example 6 except that the working force (the rotational speed of the chrysanthemum roller was 2.0 times as compared with comparative example 6 and the punching ratio was 1.04 times as compared with comparative example 1) by the oscillating washer in the slurry washing step was increased, and the line tension and the spray pressure (line tension: 0.8 times as compared with comparative example 6 and spray pressure: 0.6 times as compared with comparative example 6) in the fiber opening step after the silane coupling agent treatment were reduced, to obtain glass cloths having a width of 1285 mm.

Example 7 >

Glass cloth was produced in the same manner as in example 6 except that the working force (the rotational speed of the chrysanthemum roller was 2.5 times as high as that of comparative example 6 and the punching ratio was 1.08 times as high as that of comparative example 6) by the oscillating washer in the slurry washing step was increased, and the line tension and the spray pressure (line tension: 0.6 times as high as that of comparative example 6 and spray pressure: 0.2 times as high as that of comparative example 6) in the fiber opening step after the silane coupling agent treatment were reduced, whereby glass cloth having a width of 1285mm was obtained.

Comparative example 7 >

Glass cloth was produced in the same manner as in comparative example 6 except that the line tension and the spray pressure (line tension: 0.6 times as compared with comparative example 6 and spray pressure: 0.2 times as compared with comparative example 6) in the fiber opening step after the silane coupling agent treatment were reduced, and glass cloth having a width of 1285mm was obtained.

Comparative example 8 >

The warp yarn and weft yarn were each made of a low dielectric glass yarn (LCE 255, 61GPa, manufactured by AGY Co., ltd.) having an average filament diameter of 7.1 μm and a filament count of 200, and a glass cloth (grey cloth) having a warp yarn beating-up density of 60/25 mm and a weft yarn beating-up density of 57/25 mm was woven using an air jet loom.

The average value of the number of turns of the glass yarn used in the warp yarn of comparative example 8 was 0.90 to 1.07, and the standard deviation of the number of turns was 0.06 to 0.30.

Example 8 >

Glass yarns having a standard deviation of 0.135 or less (average value of twist number of 0.92 to 1.03) were used as selected twist number of yarns, and the processing force (the rotational speed of the chrysanthemum roller was 2.0 times as compared with comparative example 8 and the punching ratio was 1.04 times as compared with comparative example 8) by the oscillating washer in the slurry washing step was increased, and the line tension and the spray pressure (line tension: 0.7 times as compared with comparative example 8 and spray pressure: 0.6 times as compared with comparative example 8) in the fiber opening step after the silane coupling agent treatment were reduced, whereby glass cloths having a width of 1285mm were obtained in the same manner as in comparative example 8.

Example 9 >

Glass cloth was produced in the same manner as in example 8 except that the working force (the rotational speed of the chrysanthemum roller was 2.5 times as high as that of comparative example 8 and the punching ratio was 1.08 times as high as that of comparative example 8) by the oscillating washer in the slurry washing step was increased, and the line tension and the spray pressure (line tension: 0.5 times as high as that of comparative example 8 and spray pressure: 0.2 times as high as that of comparative example 8) in the fiber opening step after the silane coupling agent treatment were reduced, to thereby obtain glass cloth having a width of 1285 mm.

Comparative example 9 >

Glass cloth was produced in the same manner as in comparative example 8 except that the line tension and the spray pressure (line tension: 0.5 times as compared with comparative example 8 and spray pressure: 0.2 times as compared with comparative example 8) in the fiber opening step after the silane coupling agent treatment were reduced, and glass cloth having a width of 1285mm was obtained.

Comparative example 10 >

Glass cloth was produced in the same manner as in comparative example 8 except that the working force (the rotational speed of the chrysanthemum roller was 0.5 times as high as that of comparative example 8 and the punching ratio was 0.96 times as high as that of comparative example 1) by the oscillating washer in the slurry washing step was reduced, and the line tension and the spray pressure (line tension: 1.5 times as high as that of comparative example 8 and spray pressure: 1.2 times as high as that of comparative example 8) in the fiber opening step after the silane coupling agent treatment were increased, whereby glass cloth having a width of 1285mm was obtained.

The glass fiber compositions, the wire width compositions of the glass cloths, the glass cloth structures, and the stress-strain characteristics of the glass cloths of the examples and comparative examples are shown in tables 1 to 4. The measurement results of the elongation characteristics of the conventional low dielectric glass cloth, the low dielectric glass cloths of comparative examples 3,6, and 8, and the low dielectric glass cloths of examples 4, 6, and 8 are shown in fig. 1 to 10. In the figure, the broken line represents the elongation of the warp yarn, and the solid line represents the elongation of the weft yarn.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

In the glass cloths of examples 1 to 7, the elongation in the warp direction and the elongation in the weft direction were both small, and the ratio of the elongation in the warp direction to the elongation in the weft direction was both small and the anisotropy was both small in the stress-strain curves.

In the glass cloths of comparative examples 1 to 10, in the stress-strain curve, one of the elongation in the warp direction and the elongation in the weft direction was large, and the ratio of the elongation in the warp direction to the elongation in the weft direction was large, and the anisotropy was large.

FIGS. 1 to 7 show a 1017 type (thickness: 15 μm, filament diameter of glass yarn: 4.0 μm, filament number of glass yarn: 50, warp yarn density: 94.5/25 mm, weft yarn density: 95.5/25 mm), a 1027 type (thickness: 21 μm, filament diameter of glass yarn: 4.0 μm, filament number of glass yarn: 100, warp yarn density: 74.0/25 mm, weft yarn density: 74.0/25 mm), a 1037 type (thickness: 25 μm, filament diameter of glass yarn: 4.5 μm, filament number of glass yarn: 100, warp yarn density: 69.0/25 mm, weft yarn density: 72.0/25 mm), a 1067 type (thickness: 31 μm, filament diameter of glass yarn: 5.1 μm, filament number of glass yarn: 100, a warp yarn density: 100 the elongation characteristics of low dielectric glass cloths of the warp yarn fabric density 69.0/25 mm, weft yarn fabric density 69.0/25 mm), 1078 type (thickness 47 μm, filament diameter of glass yarn 5.1 μm, filament number of glass yarn 200, warp yarn fabric density 52.5/25 mm, weft yarn fabric density 52.5/25 mm), 3313 type (thickness 74 μm, filament diameter of glass yarn 6.2 μm, filament number of glass yarn 200, warp yarn fabric density 59.0/25 mm, weft yarn fabric density 61.0/25 mm), 2116 type (thickness 89 μm, filament diameter of glass yarn 7.1 μm, filament number of glass yarn 200, warp yarn fabric density 60.0/25 mm, weft yarn fabric density 57.0/25 mm) were measured. For these glass cloths, warp and weft are made of the same glass filaments, but for the following purposes: (1) Glass filaments with the same rigidity are used as the warp filaments and the weft filaments, so that the strengthening effects of dimensional stability, thermal expansion coefficient and the like are the same in the warp filament direction and the weft filament direction; (2) improving surface smoothness; (3) The distribution of the insulating resin and glass is uniform when forming the substrate for the printed wiring board; (4) Ensuring the hole precision achieved by drilling, laser machining, etc. As the filament diameter of the glass filaments constituting the glass cloth increases, and the number of filaments increases, if the same glass filaments are not used for the warp filaments and the weft filaments, the above-described characteristics are greatly impaired, and therefore, in general, the glass cloth for high-speed communication uses the glass cloth in which the warp filaments and the weft filaments are the same.

As is clear from fig. 1 to 7, the conventional low dielectric glass cloth has a characteristic that the weft direction is greatly elongated compared with the warp direction when the same tensile load is applied, and the difference is a ratio (rounded 2 th or less decimal point) of the elongation in the weft direction to the elongation in the warp direction when the load is 50N, and is large for the types 1017, 1027, 1037, 1067, 1078, 3313, 2116, and is 1.1, 1.2, 1.3, 2.0, and 2.3, respectively.

This is because the conventional glass cloth uses the same glass filaments for warp filaments and weft filaments, and the weft filaments have a larger undulation state than the warp filaments. This difference in relief state is due to the following reasons: the warp yarn is held by tension during weaving, so that the warp yarn is not easy to undulate, and on the other hand, the weft yarn is greatly undulated to the extent that the warp yarn is held by tension and is not easy to undulate. In addition, when the width of the warp yarn is widened by the flattening and opening, the warp yarn is held in tension, and the undulating structure is maintained, and the weft yarn is staggered so that the warp yarn is widened to draw a large arc along the warp yarn, and the undulation increases, and the difference between the warp yarn and the weft yarn of the elongation characteristic increases even further. In addition, when the flattening and opening processing are repeatedly performed in a state where the warp yarn is once widened by the flattening and opening processing, the warp yarn is stretched in tension, so that the fluctuation is eliminated together with the shrinkage of the yarn width, and the weft yarn further forms a large fluctuation along the warp yarn, and therefore, the difference between the warp yarn and the weft yarn of the elongation characteristic further increases.

Further, the undulating structure of the weft yarn has a feature that the larger the number of filaments of the glass yarn is, the larger the cross-sectional area of the glass yarn bundle is, the more significantly it is. As is clear from the examples of fig. 1 to 7, the ratio of the elongation in the weft direction to the elongation in the warp direction (rounding 2 bits or less) was 1.1 for 1017 of 50 filaments, and 1.2, and 1.3 for 1027, 1037, and 1067 of 100 filaments, whereas the ratio was 2.0, and 2.3 for 1078, 3313, and 2116 of 200 filaments, and the number of filaments was 200. This is because, in the case of a glass yarn having 200 filaments, the thickness of the warp yarn in the z direction is also increased, and the weft yarn itself is also thick, and therefore the weft yarn needs to be greatly undulated.

That is, a glass cloth of the prior art, particularly a glass cloth having a thickness of 40 μm or more and composed of glass filaments having 200 filaments, has a characteristic that the weft direction is easily elongated by about 2 times under the same tensile stress. Therefore, there is a tendency that the effect of reinforcing dimensional changes during printed wiring board processing is reduced in the weft direction, and there is a problem that warpage and warpage in the processing step, anisotropy of dimensional changes, and anisotropy of dimensional changes upon heating tend to occur.

Further, referring to fig. 4, it is clear that the low dielectric glass cloth of 1067 type described in the example of japanese patent application laid-open No. 2017-132651 (patent document 1) has an anisotropy of SS characteristics that is large even if the difference in the width direction elongation is 10% or less, and the ratio (transverse/longitudinal ratio) of the elongation in the weft direction generated when a load of 50N is applied every 25mm width in the weft direction to the elongation in the warp direction generated when a load of 50N is applied every 25mm width in the warp direction is 1.31.

In contrast to the above-described conventional glass cloths, the glass cloth of the present invention is characterized in that the anisotropy of the stress-strain curve is reduced. The ratio of the elongation in the weft direction to the elongation in the warp direction (transverse/longitudinal) is preferably 1.0 to 1.9. The ratio of the elongation in the weft direction to the elongation in the warp direction (transverse/longitudinal) is more preferably in the range of 1.0 to 1.8, and still more preferably in the range of 1.0 to 1.7.

The results of the elongation characteristics measurements of example 4 (type 1078, thickness 44 μm, filament diameter of glass filaments 5.1 μm, filament number of glass filaments 200, warp yarn fabric density 53/25 mm, weft yarn fabric density 53/25 mm), example 6 (type 3313, thickness 67 μm, filament diameter of glass filaments 6.2 μm, filament number of glass filaments 200, warp yarn fabric density 59.0/25 mm, weft yarn fabric density 61.5/25 mm), example 8 (type 2116, thickness 83 μm, filament diameter of glass filaments 7.1 μm, filament number of glass filaments 200, warp yarn fabric density 60.0/25 mm, weft yarn fabric density 57.0/25 mm) are shown in FIGS. 8 to 10. The ratio (transverse/longitudinal) of elongation in the weft direction to elongation in the warp direction (rounding 2 bits below the decimal point) was 1.4 and 1.6, 1.4, respectively, and the anisotropy of the stress-strain curve was significantly improved as compared with conventional glass cloths. Further, since the warp yarn and weft yarn have a well-balanced undulating structure and are tightly woven into the glass yarn in the Z-axis direction, they are also characterized by being thinner to several micrometers than conventional glass cloths using the same yarn.

Claims

1. A glass cloth having a thickness of 40 μm or more and 100 μm or less, which is obtained by weaving glass filaments having a filament count of 120 or more and 500 or less as warp filaments and weft filaments,

The lower limit value of the width of the warp yarn is equal to or more than a value obtained by the following formula (1),

40 Xα+102 … (1)

Wherein, alpha: the average diameter of the filaments of the warp threads, in μm,

The ratio of the width of the warp yarn to the width of the weft yarn, i.e., the ratio of the width of the warp yarn to the width of the weft yarn divided by the average diameter of the filaments, is 0.125 to 0.142.

2. The glass cloth according to claim 1, wherein a warp width thickness curl shape index obtained by dividing a thickness of the glass cloth by a yarn width of the warp yarn is a value of 0.2305 ×ln (α) -0.227 … formula (2) or less obtained by using the following formula (2)

Wherein, alpha: the average diameter of the filaments of the warp threads is given in μm.

3. A glass cloth having a thickness of 40 μm or more and 100 μm or less, which is obtained by weaving glass filaments having a filament count of 120 or more and 500 or less as warp filaments and weft filaments,

40 Xα+102 … (1)

The warp width, thickness and curl shape index obtained by dividing the thickness of the glass cloth by the width of the warp yarn is a value obtained by the following formula (2),

0.2305 Xln (. Alpha.) -0.227 … (2)

4. The glass cloth according to any one of claims 1 to 3, wherein a difference between a fabric density of the warp filaments and a fabric density of the weft filaments is 5 or less.

5. A glass cloth according to claim 1 or 3, wherein the sum of the filament width of the warp filaments and the filament width of the weft filaments is 720 μm or more.

6. The glass cloth according to claim 1 or 3, wherein a weft occupancy Y representing a ratio of a portion where weft exists in the MD, which is obtained by the following formula (3), is 88% or more and 104% or less,

Y=f/(25000/G) ×100 … (3)

Wherein F is weft yarn width, G is weft yarn fabric density, F is μm, and G is root/25 mm.

7. The glass cloth according to claim 1 or 3, wherein a ratio of elongation a in a weft direction, which is a ratio of elongation a in the weft direction when a load of 50N is applied per 25mm width in the weft direction, to elongation B in a warp direction, which is a ratio of elongation B in the warp direction when a load of 50N is applied per 25mm width in the warp direction, is 1.0 or more and 1.9 or less.

8. The glass cloth according to claim 1 or 3, wherein the elongation a in the weft direction generated when a load of 50N is applied per 25mm width in the weft direction and the elongation B in the warp direction generated when a load of 50N is applied per 25mm width in the warp direction are each 0.3% or more and 0.95% or less.

9. The glass cloth according to claim 1 or 3, which is composed of glass filaments having an elastic modulus of 50GPa or more and 70GPa or less.

10. The glass cloth according to claim 1 or 3, which is composed of glass filaments having an elastic modulus of 50GPa or more and 64GPa or less.

11. A glass cloth having warp and weft yarns composed of glass filaments having a filament count of 120 to 500 inclusive and a thickness of 40 to 100 μm inclusive,

The ratio of the elongation A in the weft direction, which is generated when a load of 50N is applied to the weft direction per 25mm width, to the elongation B in the warp direction, which is generated when a load of 50N is applied to the warp direction per 25mm width, is 1.0 to 1.9.

12. A glass cloth comprising warp and weft yarns, each of which comprises glass filaments having an average filament number of 120 to 500 and a thickness of 40 μm to 100 μm,

13. The glass cloth according to claim 11 or 12, wherein a weft occupancy Y representing a ratio of a portion where weft exists in the MD, which is obtained by the following formula (3), is 88% or more and 104% or less,

Y=f/(25000/G) ×100 … (3)

14. The glass cloth according to claim 11 or 12, which is composed of glass filaments having an elastic modulus of 50GPa or more and 70GPa or less.

15. The glass cloth according to claim 11 or 12, which is composed of glass filaments having an elastic modulus of 50GPa or more and 64GPa or less.