JP7320388B2 - Glass cloth, prepreg, and printed wiring board - Google Patents

Description

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

Most printed wiring boards are usually made by impregnating a base material such as glass cloth with a thermosetting resin such as epoxy resin and drying it to form a prepreg. It is manufactured by a method of forming a laminated plate by heating and pressing after stacking, and then forming a circuit pattern made of copper foil on the laminated plate by photolithography and etching or plating. Furthermore, a method of using the above-mentioned printed wiring board as a core substrate, overlaying a prepreg on the surface layer, and further overlaying a copper foil on the outer side, forming a multilayer board by heating and pressing, and then forming a circuit on the surface of the multilayer board. etc. to produce a multilayer printed wiring board.

On the other hand, due to the high functionality and reduction in size and weight of digital equipment in recent years, there is a demand for further reduction in size, thickness, and density of printed wiring boards used therein. As a method for that purpose, the thickness of the glass cloth used as the base material is reduced and the number of layers of the multilayer printed wiring board is increased to achieve high density. Here, the thickness of the glass cloth is required to be as thin as 16 μm or less, for example, in order to achieve high performance, small size and light weight of state-of-the-art smartphones and wearable devices.

Here, as the thin glass cloth, for example, the glass cloths described in Patent Documents 1 to 6 have been proposed. Specifically, Patent Document 1 discloses a glass cloth having a thickness of 7 to 14 μm, Patent Document 2 discloses a glass cloth having a thickness of 14 μm or less, Patent Document 3 discloses a glass cloth having a thickness of 10 μm or more and 40 μm or less, and Patent Document 4. proposes a glass cloth having a thickness of 10 μm or more and 50 μm or less, Patent Document 5 proposes a glass cloth having a thickness of 5 to 15 μm, and Patent Document 6 proposes a glass cloth having a thickness of 25 μm or less.

The glass cloth described in Patent Document 1 has an average diameter of 3.5 to 4.4 μm for both warp and weft, 20 to 60 filaments, and 0.5×10 ⁻⁶ to 1.7×10 ⁻ per unit length. It is a glass cloth woven with ⁶ kg/m glass yarn, and the number of filaments of the weft is greater than that of the warp so that the ratio of the mass of the warp to the mass of the weft is in the range of 1.26 to 1.42. It is said that the problem of pinholes and warping when used as prepreg can be improved because the spacing between wefts becomes difficult to widen and the air permeability can be adjusted to be small within a specific range.

In the glass cloth described in Patent Document 2, the average filament diameter of the warp and weft is 3.0 to 4.3 μm, and the number of filaments is more in the weft than in the warp, and the ratio (weft/warp ratio) is 0.9. As described above, the degree of opening of the weft is greater than that of the warp. It is said that the occurrence of pinholes can be suppressed when used as a substrate because the distance between adjacent wefts is reduced.

The glass cloth described in Patent Document 3 is composed of glass yarns having a mass of 1.8 × 10 ^-6 kg / m or more and 14 × 10 ^-6 kg / m or less for the warp and weft, and the average filament diameter of the warp The glass cloth has an average filament diameter ratio (weft/warp ratio) of 1.01 or more and less than 1.20. and its weft/warp ratio within a specific range, a printed wiring board with little anisotropy in dimensional change and free from warping and twisting can be produced.

In the glass cloth described in Patent Document 4, the warp and the weft are composed of the same kind of glass yarn, the yarn width of the weft is close to the yarn width of the warp, and the ratio (weft/warp ratio) is 0.8 or more and 1.2. below, and the ratio of the elongation rate in the warp direction to the elongation rate in the weft direction when a load within the range of 25 N to 100 N per 25 mm of width is applied (the weft/warp ratio) is in the range of 0.8 or more and 1.2 or less. It is said that the film substrate using the glass cloth has excellent dimensional stability by using the same glass yarn for the warp and weft, and by making the cross-sectional shape and undulation state the same. .

The glass cloth described in Patent Document 5 is a glass composed of glass yarns having an average filament diameter of less than 4.5 μm in at least one of the warp and the weft, and in which both the number of filaments is 5 or more and 70 or less. Although it is a cloth and has a small number of glass filaments, it has excellent dimensional stability and mechanical properties by opening and widening under moderate conditions to make the surface glass coverage 50% or more and 100% or less. It is said that glass cloth can be obtained.

The glass cloth disclosed in Patent Document 6 is a glass cloth having an average filament diameter of 3 to 4 μm in at least one of the warp and the weft, and composed of glass yarns having a filament number of 70 to 200. At least one of the wefts and the wefts are adjacent to each other and are arranged substantially without gaps, so that the surface smoothness is excellent and the small hole workability is excellent.

Also, as the glass cloths registered in the ICP standard, thin glass cloths with a thickness of 1000 (12 μm), 1010 (11 μm), 1017 (14 μm), 1015 (15 μm), etc. are commercially available and can be used.

With the recent development of the information communication society, data communication and/or signal processing have become large-capacity and high-speed, and the reduction in the dielectric constant of printed wiring boards used in electronic devices has progressed remarkably. Therefore, many low-dielectric glass cloths have been proposed as glass cloths constituting printed wiring boards. For example, the low-dielectric glass cloth disclosed in Patent Document 9 contains a large amount of B ₂ O ₃ in the glass composition and at the same time contains other materials such as SiO ₂ , as opposed to the conventional E-glass cloth. A low dielectric constant is achieved by adjusting the blending amounts of the components.

5831665 publication 5936726 publication 5027335 publication 3897789 publication 4446754 publication 3756066 publication JP-A-10-245743 JP-A-2001-269931 JP-A-11-292567

Patent Document 6 describes a glass cloth having a thickness of 25 μm or less, but the glass cloth specifically disclosed in Examples 1 to 5 has a thickness of 17 to 21 μm, and the thinnest is 17 μm. Met. In the glass cloth disclosed in Patent Document 6, it is necessary to use glass yarns with a large number of filaments in order to arrange adjacent yarns without gaps, and as a result, it is difficult to reduce the thickness of the glass cloth. be. Specifically, in Examples 1 to 5 in Patent Document 6, 100 filament glass yarns were used for both the warp and the weft.

The glass cloth disclosed in Patent Document 5 has a thickness of 5 μm or more and less than 15 μm by reducing the average diameter of the glass filaments that make up the warp and weft and by reducing the number of filaments that make up the warp and weft. , has achieved a reduction in the thickness of the glass cloth. The glass cloths in Patent Documents 1 and 2 are also thin.
However, the glass cloth disclosed in Patent Document 1 uses thin glass yarns with a mass of 0.5×10 ⁻⁶ to 1.7×10 ⁻⁶ kg/m for the warp and weft. It has a problem of low rigidity and waviness during prepreg coating.
Also, in Patent Document 2, fine glass yarns having a weight of 1.65×10 ⁻⁶ kg/m or less for both warp and weft, specifically lighter than BC3000, BC3750, BC5000, and BC6000 are used. Therefore, the rigidity of the glass cloth is small, and there is a problem that waviness occurs during prepreg coating.
Furthermore, in the glass cloth disclosed in Patent Document 5 as well, since the number of filaments constituting the warp and weft is reduced, waviness is likely to occur.

Here, the waviness of the glass cloth is a phenomenon in which the prepreg is deformed into a shape as illustrated in FIG. . If the prepreg waviness is large, wrinkles may be generated due to the waviness, and positioning in the subsequent prepreg molding process may be difficult, resulting in misalignment. In addition, when prepregs are stacked and stored, or when the prepreg is rolled up and stored, the wavy protrusions come into contact with each other and rub against each other, so cracks occur in the B stage, that is, in the semi-cured curable resin. , there is also a problem that the resin peels off.

The rippling of the prepreg occurs because the stress caused by shrinkage of the thermosetting resin due to drying in the prepreg coating process is relieved by rippling in the weft direction where there is no binding force due to line tension. For example, Patent Document 7 discloses that waviness occurs when a prepreg having a thickness of 70 μm is produced using glass cloth having a mass per unit area of 48 g/m ² , and It is described that waviness occurs when producing a prepreg using the following glass cloth.

As described above, waviness occurs when the curable resin shrinks when cured, and the glass cloth is bent against the force of contraction in the weft direction where the glass cloth is not held in tension. Therefore, waviness is more likely to occur as the thickness of the glass cloth is thinner and the rigidity is lower. In addition, when the glass cloth becomes thinner and weaker in strength, the line tension applied in the warp direction also decreases, so that the glass cloth tends to flutter and/or bend during the prepreg coating process. Therefore, there is a problem that the thinner the glass cloth is, the more likely it is to be undulated.

The glass cloth described in Patent Document 4 can be made to have the same undulating structure of the warp and weft by performing the fiber opening process under low tension conditions, and the elongation rate of the warp and the weft when a tensile load is applied is different. It is considered to be equivalent and excellent in dimensional stability.
However, in the glass cloth described in Patent Document 4, since the same glass yarn is used for the warp and the weft, it is difficult to make the undulation structure of the warp and the weft equal. Also, the glass cloth stretches more in the weft direction than in the warp direction, and the dimensional stability effect in the weft direction during prepreg coating is not sufficient, and there is room for improvement in preventing waviness.

The glass cloth described in Patent Document 3 uses glass yarns having a larger filament diameter than the warp yarns for the weft yarns and adjusts the number of filaments to reduce strain (elongation) when a tensile load is applied, thereby reducing the difference in strain. It is a glass cloth that achieves a reduction in directionality. The glass cloth described in Patent Literature 3 has a reduced waviness structure of the weft yarns, and is therefore useful for improving waviness during prepreg coating.
However, in the glass cloth of Patent Document 3, it is necessary to use relatively thick glass yarns of 1.8 × 10 ^-6 kg / m or more for the warp and weft in order to reduce the strain when a tensile tension acts. , as specifically disclosed in the examples of the patent document, even the thinnest glass cloth has a minimum thickness of 17 μm, and a glass cloth having a thickness of 16 μm or less cannot be obtained.
In the glass cloth of Patent Document 3, as in the example of the patent document, a tensile tension was applied in the weft direction by using a thick yarn with a filament diameter of 4.5 μm or more and 100 filaments for the weft. It realizes the reduction of the distortion at the time. Therefore, there is also a problem that the interval between adjacent wefts becomes narrow. Usually, the glass cloth is impregnated with a resin, and after removing excess resin, the resin on the front and back of the glass cloth penetrates each other through the glass-free portions of the glass cloth and is homogenized. The glass cloth is not sufficiently impregnated with resin, and it is difficult to form a uniform resin layer on the front and back of the glass cloth.

In addition, glass cloths with a thickness of 16 μm or less such as 1000 (12 μm), 1010 (11 μm), 1017 (14 μm), 1015 (15 μm) registered in the ICP standard are commercially available. also has the problem of waviness during prepreg coating, and its improvement is desired.
Furthermore, in the manufacturing process of printed wiring boards, due to heat and pressure in the laminating process, and part of the copper foil being etched out in the circuit pattern forming process, dimensional changes, warping, and twisting of the copper-clad laminate may occur. known to occur. The 1000, 1010, 1017, and 1015 style glass cloths having a thickness of 16 μm or less have a weak mechanical strength, and thus have the problem that the above-mentioned dimensional change, warp, and twist tend to occur remarkably. In particular, the dimensional change tends to occur in the weft direction, and the amount of dimensional change varies greatly. The higher the density of the printed wiring board, the more important it is to be stable against dimensional changes. do.

In low dielectric glass, as disclosed in Patent Document 9, low dielectric properties appear by adjusting the glass composition, such as increasing the amount of B ₂ O ₃ in the glass composition. The control of the glass composition for the purpose of lowering the dielectric tends to reduce the specific gravity of the glass that constitutes the glass yarn and weaken the rigidity of the glass yarn. Therefore, compared with glass cloth made of conventional E-glass, low-dielectric glass cloth is prone to waviness and tends to be inferior in dimensional stability.

The present invention has been made in view of the above problems. It is an object of the present invention to provide a low-dielectric glass cloth having a thickness of 16 μm or less, and a prepreg and printed wiring board substrate using the low-dielectric glass cloth.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the low-dielectric glass cloth composed of warp and weft has a specific woven structure, while maintaining the thickness at 16 μm or less. It has been found that the rigidity of the prepreg is increased, waviness is small during prepreg coating and is excellent in handleability, the resin impregnation is excellent and the resin layer can be made uniform on the front and back of the glass cloth, and the dimensional stability is excellent. was completed.

That is, the present invention is as follows.
[1]
A glass cloth having a thickness of 8 μm or more and 16 μm or less, which is composed of glass threads composed of a plurality of glass filaments as warp and weft,
The average mass per unit length of the warp is 1.40 × 10 ^-6 kg/m or more and less than 1.60 × 10 ^-6 kg/m,
The average mass per unit length of the weft is 1.60 × 10 ^-6 kg/m or more and 3.00 × 10 ^-6 kg/m or less,
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 greater than 1.20 and less than or equal to 1.50;
The glass has a density of 2.1 g/cm ³ or more and 2.5 g/cm ³ or less.
Glass cloth.
[2]
The average number of filaments of the warp and weft is substantially the same, and
The average filament diameter of the warp is 3.7 μm or more and 4.3 μm or less,
The average filament diameter of the weft is 4.2 μm or more and 5.3 μm or less,
The ratio of the average filament diameter of the weft to the average filament diameter of the warp (weft/warp ratio) is 1.07 or more and 1.40 or less.
The glass cloth according to [1].
[3]
The average filament diameters of the warp and weft are substantially the same, and
The average number of filaments of the warp is 45 or more and 70 or less,
The average number of filaments of the weft is 55 or more and 80 or less,
The ratio of the average number of filaments of the weft to the average number of filaments of the warp (weft/warp ratio) is greater than 1.25 and not more than 1.50.
The glass cloth according to [1].
[4]
The coefficient (Y: weft occupancy) indicating the ratio of the portion where the weft exists in the longitudinal direction (MD direction) of the weft obtained by the formula (1) is 76% or more and 90% or less.
The glass cloth according to any one of [1] to [3].
Y=F/(25000/G)×100 (1)
(In formula (1), F is the weft width (μm), and G is the weft weaving density (thread/25 mm).)
[5]
The gap width between adjacent wefts in the longitudinal direction (MD direction) is 40 μm or more and 80 μm or less.
The glass cloth according to any one of [1] to [4].
[6]
having a dielectric constant of 5.0 or less at a frequency of 10 GHz;
The glass cloth according to any one of [1] to [5].
[7]
The glass cloth according to any one of [1] to [6];
a matrix resin;
prepreg.
[8]
A glass cloth composed of glass yarns composed of a plurality of glass filaments as warps and wefts, having a thickness of 8 μm or more and 16 μm or less, and a glass density of 2.1 g/cm ³ or more and 2.5 g/cm ³ or less. and a matrix resin, wherein
1) to 3) below;
1) the resin content is 50% or more and 83% by mass or less;
2) The ratio of the thickness of the first resin layer located on one side of the glass cloth to the thickness of the second resin layer located on the other side of the glass cloth is 0.7 or more and 1.3 or less. to be
3) waviness is less than 3 mm;
Prepreg that satisfies
[9]
The glass cloth is the glass cloth according to any one of [1] to [6],
The prepreg according to [8].
[10]
The gap width between adjacent wefts in the longitudinal direction (MD direction) is 40 μm or more and 80 μm or less.
The prepreg according to [8] or [9].
[11]
A printed wiring board comprising the prepreg according to any one of [7] to [10].

According to the present invention, there is provided a thin low-dielectric glass cloth having a thickness of 16 μm or less, which has less waviness during prepreg coating, excellent handleability, excellent resin impregnation when forming prepreg, and excellent dimensional stability. can do.

FIG. 2 is a schematic diagram of a prepreg having undulations; FIG. 4 is a diagram showing a method of measuring the height of waviness;

Hereinafter, an embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail, but the present invention is not limited to this, and various modifications are possible without departing from the gist thereof. is.

<Glass cloth>
The glass cloth of the present embodiment is a glass cloth having a thickness of 8 μm or more and 16 μm or less, which is composed of warp and weft yarns made of a plurality of glass filaments.
When the thickness of the glass cloth is 8 μm or more and 16 μm or less, it is possible to obtain a thin prepreg with a thickness of, for example, 18 μm or more and 35 μm, and it is possible to respond to high performance, small size and light weight of electronic devices. A printed wiring board is obtained.

In the glass cloth of the present embodiment, the mass per unit length of warps is 1.40×10 ⁻⁶ kg/m or more and less than 1.60×10 ⁻⁶ kg/m.
In the glass cloth of the present embodiment, the weft yarn has a mass per unit length of 1.60×10 ⁻⁶ kg/m or more and 3.00×10 ⁻⁶ kg/m or less.
The ratio of the average mass per unit length of the weft yarns to the average mass per unit length of the warp yarns, i.e. the mass ratio of the warp yarns to the weft yarns (weft/warp ratio) is greater than 1.20 and 1.50 It is below.

The density of the glass constituting the glass cloth of the present embodiment is 2.10 g/cm ³ or more and 2.50 g/cm ³ or less. The density of the glass is preferably 2.20 g/cm ³ or more and 2.45 g/cm ³ or less, more preferably 2.25 g/cm ³ or more and 2.45 g/cm ³ or less.

The density of E-glass cloth, which has been generally used, is 2.54 g/cm ³ . In order to reduce the dielectric constant and dielectric loss tangent _of the glass cloth, it is necessary to change the constituent composition _of the glass. is often blended. Therefore, the density of low-dielectric glass tends to be lower than that of E-glass, and the strength of glass threads tends to decrease.
In the manufacturing process of the glass cloth, a physical load is applied in the process of adjusting the coating amount of the silane agent after impregnation coating with the silane treatment agent, or in the fiber opening process. Also, when the glass cloth is used for prepreg coating, a physical load is applied to the glass cloth in the process of adjusting the amount of the resin varnish and drying after impregnation coating with the resin varnish. In order to stably and continuously convey the glass cloth without cutting it in the above process, it is necessary for the warp to have a certain strength or ^more . Warp strength can be maintained.
In addition, since the density of the glass is 2.10 g/cm ³ or more, the strength of the weft can be reinforced, and waviness can be avoided.
By setting the density of the glass to 2.50 g/cm ³ or less, excellent low dielectric properties are obtained.

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

The ranges of the mass per unit length of the warp, the mass per unit length of the weft, and the mass ratio of the warp and the weft are preferably 1.40 × 10 ^-6 kg/m or more and 1.57, respectively. × 10 ^-6 kg/m or less, weft: 1.65 × 10 ^-6 kg/m or more and 2.80 × 10 ^-6 kg/m or less, weft/warp ratio: 1.17 or more and 1.79 or less, More preferably, warp: 1.40×10 ⁻⁶ kg/m or more and less than 1.55×10 ⁻⁶ kg/m, weft: 1.70×10 ⁻⁶ kg/m or more and 2.50×10 ⁻⁶ kg/m or less, weft/warp ratio: 1.21 or more and 1.62 or less.

In the manufacturing process of the glass cloth, a physical load is applied in the process of adjusting the coating amount of the silane agent after impregnation coating with the silane treatment agent, or in the fiber opening process. Also, when the glass cloth is used for prepreg coating, a physical load is applied to the glass cloth in the process of adjusting the amount of the resin varnish and drying after impregnation coating with the resin varnish. In order to stably and continuously convey the glass cloth in the above process without cutting it, the warp must have a certain strength or more, so the average mass per unit length of the warp is 1.40 × 10. ^-6 kg/m or more. On the other hand, by using glass yarns having an average mass per unit length of less than 1.80×10 ⁻⁶ kg/m as warp yarns, the thickness can be maintained at 16 μm or less, and the weave density can be set to, for example, 90 or more. , and tends to suppress the occurrence of pinholes.

By using glass yarns having an average mass per unit length of 1.60 × 10 ^-6 kg/m or more as weft yarns, the reinforcing effect against the shrinkage of the thermosetting resin during prepreg coating is enhanced, and waviness occurs. It favors suppression. The larger the mass per unit length of the glass yarn used for the weft, the stronger the reinforcing effect tends to be, which is preferable. should be 3.00×10 ⁻⁶ kg/m or less.

In addition, when the mass ratio of the warp to the weft is greater than 1.20, the difference between the stiffness of the weft and the stiffness of the warp increases. swell can be kept small. In the weaving process, the waviness of the weft inserted without a binding force varies depending on the variation in the line tension acting on the warp. Due to this, fluctuations in the waviness structure of the weft can be kept small. Therefore, it is possible to enhance the dimensional stability effect against curing shrinkage of the thermosetting resin in the prepreg coating process.

On the other hand, when the mass ratio of the warp to the weft is 1.50 or less, the difference in rigidity between the warp and the weft is prevented from becoming extremely large, and the waviness structure of the weft is appropriately preserved. Since there is no large difference in the undulation structure, it is possible to prevent anisotropy in the dimensional stability when used as a printed wiring board.
The weight per unit length of the warp yarn, the weight per unit length of the weft yarn, and the weight ratio between the warp yarn and the weft yarn are in the ranges described above, so that the anisotropy of the dimensional stability of the printed wiring board is improved. It is possible to increase the rigidity in the warp and weft directions while preventing this. Therefore, it is possible to obtain a glass cloth having a thickness of 16 μm or less, which has the strength not to be cut during line transportation, can reduce waviness of the prepreg, and has excellent stability against dimensional change. In addition, by setting the mass ratio of the warp to the weft to 1.50 or less, the density of the glass constituting the glass cloth is 2.10 g/cm ³ or more and 2.50 g/cm ³ or less, and the glass cloth has a low dielectric. Even if there is, the waviness of the prepreg can be reduced, and the stability against dimensional change can be excellent.
The average mass per unit length of the warp yarns and the average mass per unit length of the weft yarns are adjusted, for example, by adjusting the filament diameter and/or the average number of filaments of the filaments that make up the warp and weft yarns. It can be controlled by

In the glass cloth of the present embodiment, the average number of filaments of the warp and the weft is substantially the same, the average filament diameter of the warp is 3.7 μm or more and 4.3 μm or less, and the average filament diameter of the weft is A glass cloth having an average filament diameter of 4.2 μm or more and 5.3 μm or less and a ratio of the average filament diameter of the weft to the average filament diameter of the warp (weft/warp ratio) of 1.07 or more and 1.40 or less (hereinafter referred to as glass cloth X Also called) is preferable.
By keeping the number of filaments of the warp and weft and the filament diameter within the above range, the thickness of the glass cloth is maintained at 16 μm or less, the anisotropy of the dimensional stability of the printed wiring board is prevented, and the rigidity in the weft direction is improved. can be a strong glass cloth.

More preferably, the average filament diameter of the warp and weft and the range of the weft/warp ratio are warp: 3.8 μm or more and 4.2 μm or less, weft: 4.3 μm or more and 5.2 μm or less, and weft with an average filament diameter. / warp ratio: 1.08 or more and 1.25 or less, more preferably each warp: 3.9 μm or more and 4.1 μm or less, weft: 4.4 μm or more and 5.1 μm or less, average filament diameter weft/warp ratio 1.09 or more and 1.20 or less.

The fact that the average number of filaments of warp and weft is substantially the same means that the ratio of the number of filaments of warp to the number of filaments of weft (weft/warp ratio) is in the range of 0.94 or more and 1.06 or less. . It is preferable that the weft/warp ratio of the average number of filaments is 0.94 or more and 1.06 or less because the effect of the large filament diameter of the weft, that is, the rigidity in the weft direction is exhibited.
Further, in the present embodiment, when the average number of filaments of the warp and the weft is substantially the same, the number of filaments of the warp and the weft is preferably 60 or less. When the number of filaments in the warp and weft is 60 or less, the filaments are easily diffused by physical processing in the glass cloth manufacturing process, and the filament distribution in the Z direction of the glass fiber bundle can be reduced, so the thickness of the glass cloth can be easily reduced. . In order to reduce the thickness of the glass cloth, it is preferable that the number of filaments is as small as possible. The lower limit of the number of filaments is preferably 44 or more, more preferably 46 or more, still more preferably 48 or more.

Further, in the glass cloth of the present embodiment, the average filament diameter of the warp and the weft is substantially the same, the average number of filaments of the warp is 45 or more and 70 or less, and the average number of filaments of the weft is , 55 or more and 80 or less, and the ratio of the average number of weft filaments to the average number of warp filaments (weft/warp ratio) is greater than 1.25 and 1.50 or less (hereinafter referred to as glass cloth Y Also called) is preferable.
By setting the number of filaments in the warp and weft and the filament diameter within the above range, the thickness of the glass cloth is maintained at 16 μm or less, and the dimensional stability of the printed wiring board is not impaired, and the rigidity in the weft direction is high. Glass cloth can be used.

More preferably, the average number of filaments of warp and weft and the ratio thereof (weft/warp ratio) are warp: 43 or more and 65 or less, weft: 57 or more and 75 or less, average filament number of weft/ Warp ratio: 1.27 or more and 1.45 or less, more preferably warp: 45 or more and 60 or less, weft: 60 or more and 70 or less, average filament number weft/warp ratio: 1.30 or more 1.40 or less.

The average filament diameter of the warp and the weft being substantially the same means that the ratio of the filament diameter of the warp to the filament diameter of the weft (weft/warp ratio) is in the range of 0.95 or more and 1.05 or less. . It is preferable that the weft/warp ratio of the average filament diameter is in the range of 0.95 or more and 1.05 or less, because the effect of increasing the number of filaments in the weft, that is, the rigidity in the weft direction is exhibited.
Further, in the present embodiment, when the average filament diameters of the warp and the weft are substantially the same, the filament diameter of the warp and the weft is preferably 3.8 μm or more. When the average filament diameter of the warp and weft is 3.8 μm or more, the rigidity of the glass cloth can be increased. In order to increase the rigidity of the glass cloth, it is preferable that the filament diameter is large. is preferably 4.4 μm or less, more preferably 4.3 μm or less, still more preferably 4.2 μm or less.

Among the glass cloth X and the glass cloth Y described above, the glass cloth X of the present embodiment is preferable because it is superior in dimensional stability.

In the glass cloth of the present embodiment, the coefficient (Y: weft occupancy) indicating the ratio of the portion where the weft exists in the longitudinal direction (MD direction) of the weft obtained by the formula (1) is 76% or more and 90%. The following are preferable.
Here, the weft occupancy Y is a value obtained by dividing the width of the weft by the sum of the width of the weft and the width of the gap between the wefts, and is the value obtained by the formula (1).
Y=F/(25000/G)×100 (1)
(In formula (1), F is the weft width (μm), and G is the weft weaving density (thread/25 mm).)
The weft width is the average value obtained by observing the surface of a glass cloth sample having a size of 100 mm×100 mm with a microscope and determining the width of all the wefts.
The weft occupancy Y is more preferably 78% or more and less than 89%, and still more preferably 79% or more and 88% or less.

In the glass cloth of the present embodiment, since the wefts are made of glass yarns having a larger mass than the warp yarns, the width of the weft yarns is wider than the width of the warp yarns, and the gap between the warp yarns The gaps between the wefts tend to be wider. Here, by securing an appropriate amount of space between the wefts and creating a part where glass does not exist, excess resin is removed to adjust the amount of resin when impregnating the glass cloth with resin. After that, the resin on one side and the other side permeate each other through the portion of the glass cloth where the glass does not exist. As a result, a prepreg is obtained in which the thickness of the resin with respect to the glass cloth is the target thickness. From the above point of view, the weft occupancy Y is preferably 90% or less.
In addition, since the weft yarn occupation ratio Y is 76% or more, the glass yarns are uniformly distributed over the entire glass cloth, and the basket is formed by the gaps between the warp yarns and the gaps between the weft yarns. It is possible to reduce the size of a portion called a hole where the glass thread does not exist, thereby suppressing the occurrence of pinholes.

Further, in the glass cloth of the present embodiment, the gap width between adjacent wefts in the longitudinal direction (MD direction) of the wefts, that is, the gap between the wefts is preferably 40 μm or more and 80 μm or less. , more preferably 45 μm or more and 75 μm or less, and still more preferably 50 μm or more and 70 μm or less.
By setting the distance between the wefts to 40 μm or more and 80 μm or less, the distribution of the glass cloth and the impregnation of the resin are properly balanced, the occurrence of pinholes is suppressed, and the resin is symmetrical with respect to the glass cloth. Can be filled at the same time to be coated.
The spacing between the weft threads can be controlled, for example, by adjusting the weft width and/or the weft density.
Also, the spacing between the wefts can be adjusted by flattening the yarns forming the glass cloth by performing a fiber opening process or the like to adjust the yarn width.
Examples of the fiber-opening treatment include fiber-opening by water flow pressure, fiber-opening by high-frequency vibration using liquid as a medium, processing by pressure of fluid having surface pressure, and processing by pressurization by rolls. Among these fiber-spreading methods, from the viewpoint of yarn width uniformity, fiber-spreading by water stream pressure and/or fiber-spreading by high-frequency vibration using liquid as a medium is preferable. In addition, from the viewpoint of enhancing the effect of the flattening process, it is preferable to carry out the fiber opening process or the like while reducing the tension applied to the glass cloth for transportation. Furthermore, the spacing between the wefts can be adjusted by using a glass cloth in which an organic substance exhibiting the properties of a lubricant is attached to the glass yarn, or a binder, a sizing agent, etc. used when weaving an ordinary glass cloth. It can also be carried out by performing a flattening process with a glass cloth in an adhered state, or by performing a surface treatment with a silane coupling agent after performing an opening treatment, and then performing an opening treatment.

The glass yarn 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, silica glass (Q glass), etc. can be used. .

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

Further, glass cloth constituting a laminate used for printed wiring boards and the like may be subjected to a surface treatment with a treatment liquid containing a silane coupling agent. Commonly used silane coupling agents can be used as the silane coupling agent, and if necessary, acids, dyes, pigments, surfactants, and the like may be added.

As the silane coupling agent, it is preferable to use, for example, a silane coupling agent represented by formula (2).
X(R) _{3-nSiYn (} 2)
In 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, and n is 1 or more and 3 Each R is an integer below, and each R is independently a group selected from the group consisting of a methyl group, an ethyl group and a phenyl group.

X is preferably an organic functional group having at least three or more of amino groups and unsaturated double bond groups, and X is an organic functional group having at least four or more of amino groups and unsaturated double bond groups. A functional group is more preferred.
Any form of the alkoxy group can be used, but an alkoxy group having 5 or less carbon atoms is preferable from the viewpoint of stabilizing the glass cloth.

Specific examples of the silane coupling agent include N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-vinylbenzylaminoethyl)- γ-Aminopropylmethyldimethoxysilane and its hydrochloride, N-β-(N-di(vinylbenzyl)aminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-di(vinyl benzyl)aminoethyl)-N-γ-(N-vinylbenzyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-benzylaminoethyl)-γ-aminopropyltrimethoxysilane and its Hydrochloride, N-β-(N-benzylaminoethyl)-γ-aminopropyltriethoxysilane and its hydrochloride, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl) Known simple substances such as aminopropyltriethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, or mixtures thereof can be mentioned.

The molecular weight of the silane coupling agent is preferably 100-600, more preferably 150-500, still more preferably 200-450. Among these, it is preferable to use two or more silane coupling agents having different molecular weights. By treating the glass fiber surface with two or more silane coupling agents having different molecular weights, the density of the treatment agent on the glass surface tends to increase and the reactivity with the matrix resin tends to be further improved.

The ignition loss value of the glass cloth is preferably 0.10% by mass or more and 1.20% by mass or less, more preferably 0.11% by mass or more and 1.10% by mass or less, and still more preferably 0.12. It is more than mass % and below 1.00 mass %. When the ignition loss value is 0.10% by mass or more and 1.2% by mass or less, the transportability of the prepreg, that is, the handling property can be improved more than before. In addition, it is possible to suppress the deterioration of the insulation reliability of the substrate due to the fact that the resin and the glass cloth are easily peeled off at the interface, and it is possible to suppress the deterioration of the insulation reliability of the substrate due to the plating solution permeating the glass cloth. tend to be able.
The term "loss on ignition" as used herein can be measured according to the method described in JIS R 3420. First, the glass cloth is placed in a drier at 110° C. and dried for 60 minutes. After drying, the glass cloth is transferred to a desiccator, left for 20 minutes, and allowed to cool to room temperature. After standing to cool, the glass cloth is weighed in units of 0.1 mg or less. Next, the glass cloth is heated in a muffle furnace at 625° C. for 20 minutes. After heating in a muffle furnace, the glass cloth is transferred to a desiccator, left for 20 minutes, and allowed to cool to room temperature. After standing to cool, the glass cloth is weighed in units of 0.1 mg or less. The amount of glass cloth treated with the silane coupling agent is defined by the ignition loss value determined by the above measuring method.

<Method for manufacturing glass cloth>
The method for producing the glass cloth of the present embodiment is not particularly limited. , a fixing step of fixing the silane coupling agent to the surface of the glass filaments by heat drying, and a fiber opening step of opening the glass fibers of the glass cloth.

As a solvent for dissolving or dispersing the silane coupling agent, either water or an organic solvent can be used, but from the viewpoint of safety and protection of the global environment, it is preferable to use water as the main solvent. Methods for obtaining a treatment liquid containing water as a main solvent include a method of directly adding a silane coupling agent to water, a method of dissolving a silane coupling agent in a water-soluble organic solvent to form an organic solvent solution, and then dissolving the organic solvent solution. A method of throwing in water is preferable. A surfactant may be used in combination to improve the water dispersibility and stability of the silane coupling agent in the treatment liquid.

Methods for applying the treatment liquid to the glass cloth include (a) a method in which the treatment liquid is stored in a bath and the glass cloth is immersed and passed through (hereinafter referred to as the "immersion method"), (b) a roll coater, a die coater, Alternatively, a method of directly applying the treatment liquid to a glass cloth using a gravure coater or the like can be used. When the coating is performed by the dipping method (a), it is preferable that the glass cloth is dipped in the treatment liquid for 0.5 seconds or more and 1 minute or less.

Further, as a method for heating and drying the solvent after the treatment liquid is applied to the glass cloth, known methods such as hot air and electromagnetic waves can be used.
The heat-drying temperature is preferably 90° C. or higher, more preferably 100° C. or higher so that the silane coupling agent and the glass react sufficiently. The heat drying temperature is preferably 300° C. or lower, more preferably 200° C. or lower, in order to prevent deterioration of the organic functional group of the silane coupling agent.

The method of opening the fibers in the opening step is not particularly limited, but examples thereof include a method of opening the glass cloth with spray water (high-pressure water opening), vibro washer, ultrasonic water, mangle, or the like. . In order to keep the total area of the basket holes within a certain range, it is preferable to carry out the opening process with spray water.
In the case of opening with spray water, the water pressure may be appropriately set, and it is preferable to keep the water pressure constant in order to adjust the total area of the basket holes present in the glass cloth. Here, keeping the water pressure constant means reducing the difference between the water pressure of the spray set for opening the fibers and the actual maximum and minimum values of the water pressure. Before and after the fiber opening step, a step of drying by heating may be included.

<Prepreg>
One of the present embodiments is a prepreg (hereinafter referred to as prepreg A) composed of the glass cloth of the present embodiment and a matrix resin. The matrix resin impregnates the glass cloth.

In addition, one of the present embodiments is a prepreg (hereinafter referred to as , prepreg B). The matrix resin impregnates the glass cloth.
In addition, the prepreg B has the following 1) to 3);
1) The resin content is 50% or more and 83% by mass or less,
2) The ratio of the thickness of the first resin layer located on one side of the glass cloth to the thickness of the second resin layer located on the other side of the glass cloth is 0.7 or more and 1.3 or less. to be,
3) waviness is less than 3 mm;
meet.

The glass cloth constituting the prepreg B of the present embodiment is a low-dielectric glass cloth, and the density of the glass constituting the glass cloth is 2.1 g/cm ³ or more and 2.5 g/cm ³ or less.

The glass cloth that is a component of the prepreg of the present embodiment is preferably the glass cloth of the present embodiment. By using the glass cloth of the present embodiment, waviness is reduced during prepreg coating, and a prepreg with excellent dimensional change stability can be obtained.

The resin content in the prepreg B of the present embodiment is 50% by mass or more and 83% by mass, preferably 52% by mass or more and 80% by mass or less, more preferably 54% by mass, when the total amount of the prepreg B is 100% by mass. It is more than mass % and below 76 mass %. When the resin content is 50% by mass or more and 83% by mass, it is possible to respond to high functionality of electronic devices.

Further, in the prepreg B of the present embodiment, the ratio of the thickness of the first resin layer located on one side of the glass cloth to the thickness of the second resin layer located on the other side of the glass cloth is It is 0.70 or more and 1.30 or less, preferably 0.80 or more and 1.20 or less, and more preferably 0.85 or more and 1.15 or less.
When the ratio of the thickness of the first resin layer to the thickness of the second resin layer is 0.70 or more and 1.30 or less, waviness of the prepreg is suppressed even in a thin glass cloth having a thickness of 16 μm or less.

The amount of waviness in the prepreg B of the present embodiment is 3 mm or less, preferably 2 mm or less, more preferably 1 mm or less.
It is presumed that the waviness of the prepreg is 3 mm or less, so that the occurrence of distortion such as bending of the glass yarn that forms the glass cloth can be suppressed when the prepreg is heat-pressed. It is preferable because it has excellent properties.
Here, the waviness of the prepreg is a value obtained as follows.
A prepreg is cut into a size of 340 mm×510 mm to obtain a test piece for measuring the amount of waviness. As shown in FIG. 2, the prepreg 2 is placed on a measuring table 1 having a flat surface, the height 3 of waviness generated in the prepreg 2 is measured, and the maximum value is defined as the "amount of waviness."

The prepreg of this embodiment can be manufactured according to a conventional method. For example, after impregnating a glass cloth with a varnish obtained by diluting a matrix resin with an organic solvent, the organic solvent is volatilized in a drying oven, and the thermosetting resin is cured to a B-stage state, that is, a semi-cured state. Resin impregnated prepregs can be made.

Both thermosetting resins and thermoplastic resins can be used as the matrix resin.
The thermosetting resin is not particularly limited. A compound having at least one hydroxyl group or the like is reacted and cured without a catalyst or with the addition of a catalyst having a reaction catalytic ability such as an imidazole compound, a tertiary amine compound, a urea compound, a phosphorus compound, etc. Epoxy resin; b) A radically polymerizable curable resin that cures a compound having at least one of an allyl group, a methacrylic group, and an acrylic group using a thermal decomposition catalyst or a photodecomposition catalyst as a reaction initiator; c) a maleimide triazine resin cured by reacting a compound having a cyanate group with a compound having a maleimide group; d) a thermosetting polyimide resin cured by reacting a maleimide compound with an amine compound; e) Benzoxazine resins, etc., in which a compound having a benzoxazine ring is crosslinked and cured by heat polymerization.
The thermoplastic resin is not particularly limited, but for example, polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyether sulfone, polyarylate, aromatic polyamide, polyether ether ketone, thermoplastic polyimide, insoluble polyimide, Examples include polyamideimide and fluororesin.
Also, a thermosetting resin and a thermoplastic resin may be used in combination.

<Printed wiring board>
One of the present embodiments is a printed wiring board manufactured using the prepreg of the present embodiment, that is, a printed wiring board manufactured using the prepreg of the present embodiment. By manufacturing a printed wiring board using the prepreg of the present embodiment, it is possible to provide a high-quality printed wiring board with an accurate wiring circuit.

EXAMPLES The present invention will be specifically described below with reference to examples.
In Examples and Comparative Examples, physical properties were measured by the following methods.

(1) Physical properties of glass cloth Physical properties of glass cloth, specifically thickness of glass cloth, mass of glass cloth, mass of warp and weft, diameter of filaments constituting warp and weft, number of filaments, weave of warp Density was measured according to JIS R3420. The warp width, the weft width, and the gap width between adjacent wefts in the longitudinal direction (MD direction) were obtained by observing an arbitrary position of the glass cloth having a size of 100 mm×100 mm or more.

(2) Evaluation of rippling of prepreg The prepregs obtained in Examples and Comparative Examples were cut into a size of 340 mm x 510 mm to obtain a test piece. As shown in FIG. 2, this test piece was placed on a measuring table 1 having a flat surface, and the height 3 of waviness generated in the prepreg 2 was measured.

(3) Pinholes The prepregs obtained in Examples and Comparative Examples were cut into a size of 500 mm x 500 mm to obtain test pieces. The number of pinholes was obtained by observing the test piece with a magnifying glass of 20 times.

(4) Evaluation of dimensional stability in the weft direction The prepregs obtained in Examples and Comparative Examples were cut to a size of 340 mm × 340 mm, two sheets of the prepreg were laminated, and then a copper foil having a thickness of 12 µm was placed on both surfaces. After placement, compression molding was performed at 195° C. and 40 kgf/cm ² to obtain a test substrate. The resulting test substrate was marked at a total of 9 locations, ie, 3 locations in the vertical direction and 3 locations in the horizontal direction, at intervals of 125 mm. Then, in each of the vertical direction and the horizontal direction, six gauge point intervals between two adjacent gauge points were measured (measured value a). The steel foil was then removed by etching, and after heating at 170° C. for 30 minutes, the gauge length was measured again (measured value b). For the weft direction, the ratio of the difference between the measured value a and the measured value b to the measured value a was calculated, and the dimensional change rate between each reference point in the weft direction was obtained (6 points in total). The above test was performed three times.
The average value of the dimensional change rate between each reference point for three times (6 points x 3 times = 18 dimensional change rate values) was obtained and used as the dimensional change rate in the weft direction. In addition, the standard deviation of the values of the dimensional change rate of all 18 was obtained and used as the variation of the dimensional change rate in the weft direction.

<Example 1>
As the warp, the average filament diameter is 4.0 μm, the number of filaments is 50, the number of twists is 1.0 Z, and the mass per unit length is 1.46×10 ⁻⁶ kg/m. The average filament diameter is 4 as the weft. .5 μm, 50 filaments, 1.0 Z twist, and a weight per unit length of 1.83×10 ⁻⁶ kg/m. A glass cloth was woven at a weaving density of 60 wefts/25 mm. The density of L glass (composition: SiO ₂ : 51%, Al ₂ O ₃ : 13%, CaO: 8%, B ₂ O ₃ : 23%) constituting the glass cloth is 2.30 g/cm ³ . there were. The resulting green fabric was heat-treated at 400° C. for 24 hours and desized. Next, the glass cloth was immersed in a treatment solution containing a silane coupling agent, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane; SZ6032 (manufactured by Dow Corning Toray Co., Ltd.). , dried at 120° C. for 1 minute after squeezing, and spread by high-pressure water spray to obtain a glass cloth A having a weight of 10.1 g/m ² and a thickness of 12 μm. The yarn widths of the warp and weft of the glass cloth A were 136 μm and 269 μm, respectively, the weft yarn occupation ratio was 65%, and the gap between the weft yarns was 148 μm.
Glass cloth A was processed to have a width of 650 mm for a coating test, and a prepreg coating test was performed using an epoxy resin varnish. The epoxy resin varnish includes 80 parts by mass of low-brominated bisphenol A type epoxy resin, 20 parts by mass of cresol novolac type epoxy resin, 2 parts by mass of dicyandiamide, 0.2 parts by mass of 2-ethyl-4-methylimidazole, 2-methoxy - Prepared by blending 100 parts by mass of ethanol. The glass cloth is conveyed at a speed of 3 m / min, the glass cloth A is immersed in the epoxy resin varnish, and the excess varnish is scraped off through a slit whose gap is adjusted so that the resin content is 68% by mass. Drying was carried out at 170° C. for 1 minute and 30 seconds for a drying time of 1 minute and 30 seconds to semi-harden the epoxy resin (to B stage) to obtain a prepreg A.

<Example 2>
The weaving of the glass cloth and the subsequent treatment were carried out in the same manner as in Example 1, except that the weft weaving density was ^70/25 mm. Obtained. The yarn widths of the warp and weft of the glass cloth B were 141 μm and 288 μm, respectively, the weft yarn occupation ratio was 81%, and the gap between the weft yarns was 69 μm.
A prepreg B was obtained in the same manner as in Example 1, except that the glass cloth B was used.

<Example 3>
Weaving of the glass cloth and subsequent treatments were carried out in the same manner as in Example 1, except that the weft weaving density was 75 threads/ ²⁵ mm. Obtained. The yarn widths of the warp and weft of the glass cloth C were 139 μm and 279 μm, respectively, the weft yarn occupation ratio was 84%, and the gap between the weft yarns was 54 μm.
A prepreg C was obtained in the same manner as in Example 1, except that the glass cloth C was used.

<Example 4>
The weaving of the glass cloth and the subsequent treatment were carried out in the same manner as in Example 1, except that the weft weaving density was 78 threads/ ²⁵ mm. Obtained. The yarn widths of the warp and weft of the glass cloth D were 138 μm and 277 μm, respectively, the weft yarn occupation ratio was 86%, and the gap between the weft yarns was 44 μm.
A prepreg D was obtained in the same manner as in Example 1, except that the glass cloth D was used.

<Example 5>
The weaving of the glass cloth and the subsequent treatment were carried out in the same manner as in Example 1, except that the weft weaving density was 81 threads/ ²⁵ mm. Obtained. The yarn widths of the warp and weft of the glass cloth E were 136 μm and 272 μm, respectively, the weft occupancy was 88%, and the gap between the wefts was 37 μm.
A prepreg E was obtained in the same manner as in Example 1, except that the glass cloth E was used.

<Example 6>
The weaving of the glass cloth and the subsequent treatment were carried out in the same manner as in Example 1, except that the weft weaving density was 85 threads/ ²⁵ mm. Obtained. The yarn widths of the warp and weft of the glass cloth F were 133 μm and 268 μm, respectively, the weft yarn occupation ratio was 91%, and the gap between the weft yarns was 26 μm.
A prepreg F was obtained in the same manner as in Example 1, except that the glass cloth F was used.

<Example 7>
L glass yarn with an average filament diameter of 4.0 μm, 67 filaments, 1.0 Z twist, and a mass per unit length of 1.95 × 10 ^-6 kg / m is used for the weft, and the weft is woven Weaving of the glass cloth and subsequent treatments were carried out in the same manner as in Example 1, except that the density was 65 threads/25 mm, to obtain a glass cloth G having a mass of 10.5 g/m ² and a thickness of 13 μm. The yarn widths of the warp and weft of the glass cloth G were 153 μm and 288 μm, respectively, the weft yarn occupation ratio was 75%, and the gap between the weft yarns was 97 μm.
A prepreg G was obtained in the same manner as in Example 1, except that the glass cloth G was used.

<Example 8>
Weaving of the glass cloth and subsequent treatments were carried out in the same manner as in Example 7, except that the weft weaving density was 72 threads/ ²⁵ mm. Obtained. The yarn widths of the warp and weft of the glass cloth H were 150 μm and 282 μm, respectively, the weft yarn occupation ratio was 81%, and the gap between the weft yarns was 65 μm.
A prepreg H was obtained in the same manner as in Example 1, except that the glass cloth H was used.

<Example 9>
Weaving of the glass cloth and subsequent treatments were carried out in the same manner as in Example 7, except that the weft weaving density was 75 threads/ ²⁵ mm. Obtained. The yarn widths of the warp and weft of the glass cloth I were 147 μm and 278 μm, respectively, the weft occupancy was 83%, and the gap between the wefts was 55 μm.
A prepreg I was obtained in the same manner as in Example 1, except that the glass cloth I was used.

<Example 10>
As the warp, a low dielectric glass yarn having an average filament diameter of 4.0 μm, 50 filaments, a twist number of 1.0 Z, and a mass per unit length of 1.41×10 ⁻⁶ kg/m, and as the weft, an average filament diameter A low dielectric glass yarn of 4.5 μm, 50 filaments, 1.0 Z twist, and a mass per unit length of 1.78×10 ⁻⁶ kg/m was used, and an air jet loom was used. A glass cloth was woven with a weaving density of 5 threads/25 mm and a weft thread of 75 threads/25 mm. The density of the low dielectric glass (composition: SiO ₂ : 51%, Al ₂ O ₃ : 17%, CaO: 3%, B ₂ O ₃ : 24%) constituting the glass cloth is 2.23 g/cm ^{3 .} Met.
Then, the treatment was performed in the same manner as in Example 1 to obtain a glass cloth J having a mass of 10.8 g/m ² and a thickness of 13 µm. The yarn widths of the warp and weft of the glass cloth J were 142 μm and 283 μm, respectively, the weft yarn occupation ratio was 85%, and the gap between the weft yarns was 50 μm.
A prepreg J was obtained in the same manner as in Example 1, except that the glass cloth J was used.

<Comparative Example 1>
L glass yarn with an average filament diameter of 4.0 μm, 50 filaments, 1.0 Z twist, and a mass per unit length of 1.46 × 10 ^-6 kg / m is used for the weft, and the weft is woven Glass cloth K was woven and treated in the same manner as in Example 1 except that the density was 93.5 threads/25 mm, and the mass was 11.1 g/m ² and the thickness was 14 µm. rice field. The yarn widths of the warp and weft of the glass cloth K were 134 μm and 223 μm, respectively, the weft occupancy was 83%, and the gap between the wefts was 44 μm.
Prepreg K was obtained in the same manner as in Example 1, except that glass cloth K was used.

<Comparative Example 2>
L-glass yarn having an average filament diameter of 4.0 μm, 40 filaments, 1.0 Z twist, and a mass per unit length of 1.17×10 ⁻⁶ kg/m is used for the weft and warp, and Glass cloth was woven and treated in the same manner as in Example ¹ , except that the weaving density of the warp and weft was 95 threads/25 mm. obtained L. The yarn widths of the warp and weft of the glass cloth L were 156 μm and 177 μm, respectively, the weft occupation ratio was 67%, and the gap between the wefts was 86 μm.
A prepreg L was obtained in the same manner as in Example 1, except that the glass cloth L was used.

<Comparative Example 3>
Average filament diameter 4.0 μm for warp, 40 filaments, twist number 1.0 Z, mass per unit length 1.17×10 ⁻⁶ kg/mL glass yarn, average filament diameter 4.0 μm for weft, filament 50 strands, 1.0 Z twist, and 1.46 × 10 ^-6 kg/m mass per unit length of L-glass yarn, and the weaving density of the warp yarn is 95 yarns/25 mm, and the weft yarn is woven Weaving of the glass cloth and subsequent treatments were carried out in the same manner as in Example 1, except that the density was 95 fibers/m, to obtain a glass cloth M having a mass of 8.2 g/m ² and a thickness of 13 μm. The yarn widths of the warp and weft of the glass cloth M were 157 μm and 213 μm, respectively, the weft occupancy was 81%, and the gap between the wefts was 50 μm.
A prepreg M was obtained in the same manner as in Example 1, except that the glass cloth M was used.

<Comparative Example 4>
Glass cloth weaving and subsequent treatments were performed in the same manner as in Comparative Example 3, except that the weft weaving density was 76 threads/ ²⁵ mm. Obtained. The yarn widths of the warp and weft of the glass cloth N were 162 μm and 232 μm, respectively, the weft occupancy was 71%, and the gap between the wefts was 97 μm.
Prepreg N was obtained in the same manner as in Example 1, except that glass cloth N was used.

<Comparative Example 5>
A glass cloth was woven in the same manner as in Comparative Example 1. The raw fabric thus obtained was subjected to a fiber opening process (processing pressure of 196 N/cm ² ) using a high-pressure water jet under a tension of 4.9 N/m. After that, it was heat-treated at 400° C. for 24 hours for desizing. Subsequently, a glass cloth was placed in a treatment solution containing a silane coupling agent, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane; SZ6032 (manufactured by Toray, Dow Corning). It was immersed, squeezed out, and dried at 120° C. for 1 minute to obtain a glass cloth O with a mass of 12.5 g/m ² and a thickness of 14 μm. The chemical and physical treatment of the glass cloth conformed to the method of Example 2 of Patent Document 4: Japanese Patent No. 3897789. The yarn widths of the warp and weft of the glass cloth O were 150 μm and 166 μm, respectively, the weft occupancy was 62%, and the gap between the wefts was 101 μm.
A prepreg O was obtained in the same manner as in Example 1, except that the glass cloth O was used.

<Comparative Example 6>
Both the warp and the weft are L glass yarns having an average filament diameter of 4.0 μm, 100 filaments, a twist number of 1.0 Z, and a mass per unit length of 2.93×10 ⁻⁶ kg/m. The weaving of the glass cloth and the subsequent treatment were performed in the same manner as in Example 1, except that the weaving density was ^100/25 mm for both wefts. got
A prepreg P was obtained in the same manner as in Example 1, except that the glass cloth P was used.

<Comparative Example 7>
The average filament diameter of the warp is 4.0 μm, the number of filaments is 100, the number of twists is 1.0 Z, and the mass per unit length is 2.93×10 ⁻⁶ kg/m. The average filament diameter of the weft is 4.5 μm. , the number of filaments is 100, the number of twists is 1.0 Z, and the mass per unit length is 3.65 × 10 ^-6 kg / m. Glass cloth Q with a mass of 17.7 g/m ² and a thickness of 19 μm was obtained by weaving and subsequent processing of the glass cloth in the same manner as in Example 1, except that the weave density was 60 threads/25 mm. rice field.
A prepreg Q was obtained in the same manner as in Example 1, except that the glass cloth Q was used.

<Comparative Example 8>
L glass yarn with an average filament diameter of 5.0 μm, 50 filaments, 1.0 Z twist, and a mass per unit length of 2.44 × 10 ^-6 kg / m is used for the weft, and the weft is woven Weaving of the glass cloth and subsequent treatments were carried out in the same manner as in Example 1, except that the density was 57 threads/25 mm, to obtain a glass cloth R having a mass of 11.2 g/m ² and a thickness of 15 µm. The yarn widths of the warp and weft of the glass cloth R were 162 μm and 273 μm, respectively, the weft yarn occupation ratio was 62%, and the gap between the weft yarns was 166 μm.
A prepreg R was obtained in the same manner as in Example 1, except that the glass cloth R was used.

<Comparative Example 9>
As the warp, a low dielectric glass yarn having an average filament diameter of 4.0 μm, 50 filaments, a twist number of 1.0 Z, and a mass per unit length of 1.40×10 ⁻⁶ kg/m, and as the weft, an average filament diameter A low dielectric glass yarn of 4.5 μm, 50 filaments, 1.0 Z twist, and a mass per unit length of 1.76×10 ⁻⁶ kg/m was used, and an air jet loom was used. A glass cloth was woven with a weaving density of 5 threads/25 mm and a weft thread of 75 threads/25 mm. The density of the low dielectric glass (composition: SiO ₂ : 51%, Al ₂ O ₃ : 12%, CaO: 4%, B ₂ O ₃ : 29%) constituting the glass cloth is 2.19 g/cm ^{3 .} Met.
Then, the same treatment as in Example 1 was performed to obtain a glass cloth S having a mass of 10.7 g/m ² and a thickness of 13 μm. The widths of the warp and weft of the glass cloth S were 142 μm and 284 μm, respectively, the weft occupancy was 85%, and the gap between the wefts was 50 μm.
A prepreg S was obtained in the same manner as in Example 1, except that the glass cloth S was used.

[performance test]
Various evaluations were performed on the prepregs A to S obtained in Examples 1 to 10 and Comparative Examples 1 to 9. The results are shown in Tables 1 and 2 together.

As can be seen from the results in Table 1, the prepregs A to J obtained in Examples 1 to 10 had little waviness, and the amount of dimensional change in the weft direction and its variation were small.
The prepregs K, L, and P of Comparative Examples 1, 2, and 6 have the same volume and weaving density as the 1017, 1010, and 1027 style E glass cloths that are IPC-registered on the market, respectively. It is a prepreg obtained from a low dielectric glass cloth adjusted to be Compared with the prepregs of Comparative Examples 1, 2, and 6, the prepregs of the examples had less waviness and were superior in terms of the amount of dimensional change in the weft direction and its variation.

The prepreg M of Comparative Example 3 is a low-dielectric glass cloth adjusted so that the volume occupied by the warp and weft and the weave density are the same as those of the E glass cloth of Example 1 of Patent Document 1 and Example 1 of Patent Document 2. It is a prepreg obtained from In the prepreg M of Comparative Example 3, compared with the glass cloth L of Comparative Example 2 (IPC registered 1010) having the same warp structure, the amount of dimensional change in the weft yarn was reduced, but the variation was large.

In Comparative Example 5, as disclosed in Patent Document 4, the opening process was performed under low tension conditions, and the weft and warp yarn widths were the same, that is, the weft/warp ratio was in the range of 0.8 to 1.2. It corresponds to the glass cloth and is a prepreg obtained from the glass cloth. Although it is described in Patent Document 4 that it has excellent dimensional stability, the prepreg O has large waviness and large variation in dimensional change.

Prepreg Q of Comparative Example 7 is a prepreg obtained from a low-dielectric glass cloth adjusted so that the volume occupied by the warp and weft and the weave density are the same as those of Example 3 of Patent Document 3. The thickness of the glass cloth Q was 19 μm, and the thickness of the glass cloth was not thin. Moreover, the prepreg Q lacked uniformity in the thickness of the resin layer on both sides of the glass cloth, and a little waving occurred. Variation in dimensional change was also large compared to Examples 1-9.

The prepreg R of Comparative Example 8 is a prepreg obtained from a low-dielectric glass cloth in which the average weight per unit length of the weft yarn is greatly increased compared to that of the warp yarn. In the prepreg R, the waviness and the dimensional change of the weft were kept relatively small, but the variation in the dimensional change was large.

The prepreg S of Comparative Example 9 is a low-dielectric glass cloth made by using a low-dielectric glass cloth yarn containing a large amount of B ₂ O ₃ in order to improve the dielectric properties of the glass cloth, and using the same yarn as in Example 3. It is a prepreg obtained from Compared with Example 3, the prepreg S was greatly wavy and greatly inferior in variation in dimensional change.

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

1: Measuring table 2: Prepreg 3: Height of undulation

Claims (10)

A glass cloth having a thickness of 8 μm or more and 16 μm or less, which is composed of glass threads composed of a plurality of glass filaments as warp and weft,
The average mass per unit length of the warp is 1.40 × 10 ^-6 kg/m or more and less than 1.60 × 10 ^-6 kg/m,
The average mass per unit length of the weft is 1.60 × 10 ^-6 kg/m or more and 3.00 × 10 ^-6 kg/m or less,
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 greater than 1.20 and less than or equal to 1.50;
The glass has a density of 2.1 g/cm ³ or more and 2.5 g/cm ³ or less.
Glass cloth. The average number of filaments of the warp and weft is substantially the same, and
The average filament diameter of the warp is 3.7 μm or more and 4.3 μm or less,
The average filament diameter of the weft is 4.2 μm or more and 5.3 μm or less,
The ratio of the average filament diameter of the weft to the average filament diameter of the warp (weft/warp ratio) is 1.07 or more and 1.40 or less.
The glass cloth according to claim 1. The average filament diameters of the warp and weft are substantially the same, and
The average number of filaments of the warp is 45 or more and 70 or less,
The average number of filaments of the weft is 55 or more and 80 or less,
The ratio of the average number of filaments of the weft to the average number of filaments of the warp (weft/warp ratio) is greater than 1.25 and not more than 1.50.
The glass cloth according to claim 1. The coefficient (Y: weft occupancy) indicating the ratio of the portion where the weft exists in the longitudinal direction (MD direction) of the weft obtained by the formula (1) is 76% or more and 90% or less.
The glass cloth according to any one of claims 1 to 3.
Y=F/(25000/G)×100 (1)
(In formula (1), F is the weft width (μm), and G is the weft weaving density (thread/25 mm).) The gap width between adjacent wefts in the longitudinal direction (MD direction) is 40 μm or more and 80 μm or less.
The glass cloth according to any one of claims 1 to 4. having a dielectric constant of 5.0 or less at a frequency of 10 GHz;
The glass cloth according to any one of claims 1 to 5. The Si content of the glass filaments is SiO ₂ It is 40 to 60 mass% in terms of conversion, and the B content is B ₂ O. ₃ 15 to 30% by mass in terms of
The glass cloth according to any one of claims 1 to 6. The glass filament is silica glass,
The glass cloth according to any one of claims 1 to 7. The glass cloth according to any one of claims 1 to 8 ,
a matrix resin;
prepreg. A printed wiring board comprising the prepreg according to claim 9 .