Glass Cloth, Prepreg and Printed Wiring Board

Abstract

The present invention provides a glass cloth, a prepreg and a printed wiring board. This glass cloth can reduce the delay time difference of the printed wiring board and achieve high productivity. In this glass cloth, the diameters of the glass filaments of the warp and weft yarns are respectively 0.5 to 4.5 μm, the number of glass filaments is respectively 150 to 3000, the knitting densities are respectively in the range of 1.0 to 50.0 filaments / 25 mm or less, the average yarn widths are respectively 550 to 10000 μm, the fibrillation efficiency coefficients are respectively 0.600 to 1.500, the ratio of the number of filaments to the filament diameter is respectively 68.6 to 555.5, the geometric mean of the fibrillation efficiency coefficients of the warp and weft yarns is 0.770 to 1.200, and the thickness of the glass cloth is less than 10.0 μm.

Description

Technical Field

[0001] The present invention relates to a glass cloth, a prepreg, and a printed wiring board. Background Art

[0002] Conventionally, as an insulating material in a printed wiring board, a prepreg formed by impregnating a glass cloth with a resin such as epoxy resin or modified polyphenylene ether is used. The above glass cloth is composed of warp yarns and weft yarns, and these warp yarns and weft yarns are formed by bundling a plurality of glass filaments.

[0003] In order to miniaturize and thin the electronic device, the above printed wiring board and the above prepreg are also required to be thinned. Therefore, a glass cloth with a reduced thickness is required. As a glass cloth with a reduced thickness, the following glass cloth has been proposed (for example, refer to Patent Document 1): This glass cloth uses warp yarns and weft yarns formed by bundling a small number of glass filaments with a small fiber diameter, increases the warp knitting density and the weft knitting density, and performs a strong fibrillating treatment to increase the width of the warp yarns and the weft yarns.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent No. 6536764 Gazette Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In recent years, it has been known that as data communication becomes faster and higher in frequency, in the above printed wiring board, signal deterioration caused by distortion called skew, which reduces signal quality, has become significant, and thus it is required to suppress signal quality deterioration (reduction of delay time difference) during signal transmission. In addition, as the demand for thin printed wiring boards expands, an increase in the supply speed of glass cloth is required.

[0009] However, the conventional glass cloth described in Patent Document 1 has the following problems: Due to a small number of filaments, strong fibrillating treatment, etc., voids are generated between warp yarns or between weft yarns, particularly voids are generated between the glass filaments constituting the weft yarns, there are deviations in the yarn width of the warp yarns or the weft yarns, and parts where there is no glass cloth are generated in the printed wiring board. In addition, if parts where there is no glass cloth are generated in the above printed wiring board, there is a problem that a sufficient reduction in the delay time difference cannot be achieved. In addition, in the above conventional glass cloth, there is a problem that sufficient productivity cannot be achieved due to a high knitting density.

[0010] Therefore, an object of the present invention is to provide the following glass cloth: This glass cloth can eliminate the above problems, reduce the delay time difference of the printed wiring board, suppress signal quality deterioration, and achieve high productivity.

[0011] Means for Solving the Problems

[0012] In order to achieve the above object, the technical content of the glass cloth of the present invention is as follows. The glass cloth is composed of warp yarns and weft yarns respectively formed by bundling multiple glass filaments. The glass cloth is characterized in that the filament diameter Dt of the glass filaments constituting the warp yarns and the filament diameter Dy of the glass filaments constituting the weft yarns are each independently in the range of 0.5 μm or more and 4.5 μm or less. The number of filaments Ft of the glass filaments constituting the warp yarns and the number of filaments Fy of the glass filaments constituting the weft yarns are each independently in the range of 150 or more and 3000 or less. The knitting density Wt of the warp yarns and the knitting density Wy of the weft yarns are each independently in the range of 1.0 yarn / 25 mm or more and 50.0 yarns / 25 mm or less. The average yarn width Bt of the warp yarns and the average yarn width By of the weft yarns are each independently in the range of 550 μm or more and 10000 μm or less. The warp yarn fibrillation efficiency coefficient Pt calculated from the Dt, Ft, Wt, and Bt by the following formula (1) is in the range of 0.600 or more and 1.500 or less. The weft yarn fibrillation efficiency coefficient Py calculated from the Dy, Fy, Wy, and By by the following formula (2) is in the range of 0.600 or more and 1.500 or less. The ratio Ft / Dt of the number of filaments Ft of the glass filaments constituting the warp yarns to the filament diameter Dt of the glass filaments constituting the warp yarns, that is, Rt, and the ratio Fy / Dy of the number of filaments Fy of the glass filaments constituting the weft yarns to the filament diameter Dy of the glass filaments constituting the weft yarns, that is, Ry, are each independently in the range of 68.6 or more and 555.5 or less. The Pt and Py satisfy the following formula (3). The thickness of the glass cloth is less than 10.0 μm.

[0013] Pt = {(Bt / (Dt × Ft)) × Bt / (25000 / Wt)} 1 / 2 ×{(Dt × Ft) / (25000 / Wt)}…(1),

[0014] Py = {(By / (Dy × Fy)) × By / (25000 / Wy)} 1 / 2 ×{(Dy × Fy) / (25000 / Wy)}…(2),

[0015] 0.770 ≤ (Pt × Py) 1 / 2 ≤ 1.200…(3).

[0016] According to the glass cloth of the present invention, by having the above configuration, the glass cloth can reduce the delay time difference of the printed wiring board, suppress the deterioration of the signal quality, and achieve high productivity.

[0017] In addition, the glass cloth of the present invention is preferably such that the filament diameter Dt of the glass filaments constituting the warp yarn and the filament diameter Dy of the glass filaments constituting the weft yarn are each independently in the range of 2.0 μm or more and 3.8 μm or less, and the above Pt and Py satisfy the following formula (4).

[0018] 0.890 ≤ (Pt × Py) 1 / 2 ≤ 0.970…(4).

[0019] In addition, the present invention also relates to a prepreg containing the glass cloth of the present invention and a printed wiring board containing the glass cloth of the present invention. Detailed Embodiments

[0020] Next, the embodiments of the present invention will be further described in detail.

[0021] The glass cloth of this embodiment is composed of a warp yarn and a weft yarn respectively formed by bundling multiple glass filaments. The characteristics of this glass cloth are that the filament diameter Dt of the glass filaments constituting the warp yarn and the filament diameter Dy of the glass filaments constituting the weft yarn are each independently in the range of 0.5 μm or more and 4.5 μm or less, the number of filaments Ft of the glass filaments constituting the warp yarn and the number of filaments Fy of the glass filaments constituting the weft yarn are each independently in the range of 150 or more and 3000 or less, the knitting density Wt of the warp yarn and the knitting density Wy of the weft yarn are each independently in the range of 1.0 filaments / 25 mm or more and 50.0 filaments / 25 mm or less, the average yarn width Bt of the warp yarn and the average yarn width By of the weft yarn are each independently in the range of 550 μm or more and 10000 μm or less, the warp yarn fibrillation efficiency coefficient Pt calculated by the following formula (1) from Dt, Ft, Wt, and Bt is in the range of 0.600 or more and 1.500 or less, the weft yarn fibrillation efficiency coefficient Py calculated by the following formula (2) from Dy, Fy, Wy, and By is in the range of 0.600 or more and 1.500 or less, the ratio (Ft / Dt), that is, Rt, of the number of filaments Ft of the glass filaments constituting the warp yarn to the filament diameter Dt of the glass filaments constituting the warp yarn and the ratio (Fy / Dy), that is, Ry, of the number of filaments Fy of the glass filaments constituting the weft yarn to the filament diameter Dy of the glass filaments constituting the weft yarn are each independently in the range of 68.6 or more and 555.5 or less, the Pt and the Py satisfy the following formula (3), and the thickness of the glass cloth is less than 10.0 μm.

[0022] Pt = {(Bt / (Dt × Ft)) × Bt / (25000 / Wt)} 1 / 2 ×{(Dt × Ft) / (25000 / Wt)}…(1).

[0023] Py = {(By / (Dy × Fy)) × By / (25000 / Wy)} 1 / 2 ×{(Dy × Fy) / (25000 / Wy)}…(2)

[0024] 0.770 ≤ (Pt × Py) 1 / 2 ≤ 1.200…(3)

[0025] In the glass cloth of the present embodiment, when the filament diameter Dt of the glass filaments constituting the warp yarn or the filament diameter Dy of the glass filaments constituting the weft yarn is less than 0.5 μm, it is difficult to continuously carry out stable production. On the other hand, when the filament diameter Dt of the glass filaments constituting the warp yarn or the filament diameter Dy of the glass filaments constituting the weft yarn is independently greater than 4.5 μm, sufficient thinning of the glass cloth cannot be achieved.

[0026] The filament diameter Dt of the glass filaments constituting the above-mentioned warp yarn or the filament diameter Dy of the glass filaments constituting the above-mentioned weft yarn is preferably independently in the range of 2.0 to 3.8 μm, more preferably in the range of 2.5 to 3.7 μm, and further preferably in the range of 2.6 to 3.6 μm.

[0027] In addition, the ratio Dt / Dy of the filament diameter Dt of the glass filaments constituting the above-mentioned warp yarn to the filament diameter Dy of the glass filaments constituting the above-mentioned weft yarn is, for example, in the range of 0.90 or more and 1.10 or less, preferably in the range of 0.95 or more and 1.05 or less, more preferably in the range of 0.97 or more and 1.03 or less, further preferably in the range of 0.98 or more and 1.02 or less, particularly preferably in the range of 0.99 or more and 1.01 or less, and most preferably 1.00.

[0028] In addition, in the glass cloth of the present embodiment, if the number of filaments Ft of the glass filaments constituting the above-mentioned warp yarn and the number of filaments Fy of the glass filaments constituting the above-mentioned weft yarn are independently less than 150, gaps generated between the filaments may sometimes not be sufficiently suppressed. On the other hand, when the number of filaments Ft of the glass filaments constituting the above-mentioned warp yarn and the number of filaments Fy of the glass filaments constituting the above-mentioned weft yarn independently exceed 3000, sufficient thinning of the glass cloth cannot be achieved.

[0029] Preferably, the number of filaments Ft of the glass filaments constituting the above-mentioned warp yarn and the number of filaments Fy of the glass filaments constituting the above-mentioned weft yarn are independently in the range of 415 or more and 990 or less.

[0030] In addition, the ratio Ft / Fy of the number of filaments Ft of the glass filaments constituting the warp yarns to the number of filaments Fy of the glass filaments constituting the weft yarns is, for example, in the range of 0.90 or more and 1.10 or less, preferably in the range of 0.95 or more and 1.05 or less, more preferably in the range of 0.97 or more and 1.03 or less, further preferably in the range of 0.98 or more and 1.02 or less, particularly preferably in the range of 0.99 or more and 1.01 or less, and most preferably 1.00.

[0031] In addition, in the glass cloth of the present embodiment, if the weaving density Wt of the warp yarns and the weaving density Wy of the weft yarns are each independently less than 1.0 yarn / 25 mm, voids generated between the warp yarns or between the weft yarns may not be sufficiently suppressed. On the other hand, when the weaving density Wt of the warp yarns and the weaving density Wy of the weft yarns are each independently greater than 50.0 yarns / 25 mm, the productivity of the glass cloth cannot be sufficiently improved.

[0032] The weaving density Wt of the warp yarns and the weaving density Wy of the weft yarns are each independently preferably in the range of 2.0 yarns / 25 mm or more and 40.0 yarns / 25 mm or less, more preferably in the range of 3.0 yarns / 25 mm or more and 33.0 yarns / 25 mm or less, and further preferably in the range of 3.8 yarns / 25 mm or more and 29.0 yarns / 25 mm or less.

[0033] In addition, the ratio Wt / Wy of the weaving density Wt of the warp yarns to the weaving density Wy of the weft yarns is, for example, in the range of 0.90 or more and 1.10 or less, preferably in the range of 0.95 or more and 1.05 or less, more preferably in the range of 0.97 or more and 1.03 or less, further preferably in the range of 0.98 or more and 1.02 or less, particularly preferably in the range of 0.99 or more and 1.01 or less, and most preferably 1.00.

[0034] In addition, in the glass cloth of the present embodiment, if the average yarn width Bt of the warp yarns and the average yarn width By of the weft yarns are each independently less than 550 μm, voids generated between the warp yarns or between the weft yarns may not be sufficiently suppressed. On the other hand, if the average yarn width Bt of the warp yarns and the average yarn width By of the weft yarns are each independently more than 10,000 μm, voids generated between the filaments may not be sufficiently suppressed.

[0035] Preferably, the average yarn width Bt of the warp yarns and the average yarn width By of the weft yarns are each independently in the range of 1000 μm or more and 5500 μm or less, more preferably in the range of 1200 μm or more and 3450 μm or less.

[0036] In addition, the ratio Bt / By of the average yarn width Bt of the warp yarns to the average yarn width By of the weft yarns is, for example, in the range of 0.80 or more and 1.20 or less, preferably in the range of 0.85 or more and 1.15 or less, more preferably in the range of 0.90 or more and 1.10 or less, further preferably in the range of 0.93 or more and 1.07 or less, particularly preferably in the range of 0.95 or more and 1.05 or less, especially preferably in the range of 0.96 or more and 1.04 or less, and most preferably in the range of 0.97 or more and 1.03 or less.

[0037] The coefficient of variation of the yarn width of the warp yarns (standard deviation of the yarn width of the warp yarns / average yarn width Bt of the warp yarns) and the coefficient of variation of the yarn width of the weft yarns (standard deviation of the yarn width of the weft yarns / average yarn width By of the weft yarns) are each independently, for example, 0.20 or less, preferably 0.15 or less, more preferably 0.10 or less, and further preferably 0.05 or less. In addition, as the lower limit value of the coefficient of variation of the yarn width of the warp yarns and the coefficient of variation of the yarn width of the weft yarns, 0.01 can be cited. In addition, the average value of the coefficient of variation of the yarn width of the warp yarns and the coefficient of variation of the yarn width of the weft yarns is, for example, 0.20 or less, preferably 0.15 or less, more preferably 0.10 or less, and further preferably 0.05 or less.

[0038] In addition, in the glass cloth of the present embodiment, if the fibrillation efficiency coefficient Pt of the warp yarns is less than 0.600 or exceeds 1.500, it is difficult to reduce the delay time difference of the printed wiring board. The fibrillation efficiency coefficient Pt of the warp yarns is obtained from Dt, Ft, Wt, and Bt by the formula (1).

[0039] The fibrillation efficiency coefficient Pt of the warp yarns is preferably in the range of 0.770 or more and 1.200 or less, more preferably in the range of 0.800 or more and 1.100 or less, further preferably in the range of 0.890 or more and 1.000 or less, and particularly preferably in the range of 0.925 or more and 0.970 or less.

[0040] Here, the part "Bt / (Dt×Ft)" in the formula (1) reflects the degree of occurrence of the voids between the filaments or the overlap of the filaments with each other in the filaments constituting the warp yarns. There is a tendency that the larger "Bt / (Dt×Ft)" exceeds 1.000, the more voids are generated between the filaments, and it becomes difficult to reduce the delay time difference of the printed wiring board due to these voids. On the other hand, there is a tendency that the smaller "Bt / (Dt×Ft)" is less than 1.000, the more the filaments overlap with each other, and it becomes difficult to reduce the delay time difference of the printed wiring board due to this overlap.

[0041] In addition, in the above formula (1), the part "Bt / (25000 / Wt)" reflects the degree of occurrence of the gaps between the warp yarns or the overlap of the warp yarns with each other. There is the following tendency: the larger the value of "Bt / (25000 / Wt)" exceeds 1.000, the more likely the ends of the warp yarns will overlap with each other, and it becomes difficult to reduce the delay time difference of the printed wiring board due to this overlap. On the other hand, there is the following tendency: the smaller the value of "Bt / (25000 / Wt)" is less than 1.000, the more likely gaps will be generated between the warp yarns, and it becomes difficult to reduce the delay time difference of the printed wiring board due to these gaps.

[0042] In addition, in the above formula (1), for the part "(Dt×Ft) / (25000 / Wt)", as described above, it is preferred that both the part "Bt / (Dt×Ft)" and the part "Bt / (25000 / Wt)" are close to 1.000. When both the part "Bt / (Dt×Ft)" and the part "Bt / (25000 / Wt)" are close to 1.000, it can play a role in making the value of the above formula (1) close to 1.000. Therefore, the above formula (1) reflects the above tendency and represents the possibility of reducing the delay time difference of the printed wiring board caused by the gaps or overlaps between the filaments constituting the warp yarns, or the gaps or overlaps between the warp yarns.

[0043] In addition, in the glass cloth of the present embodiment, when the above weft yarn fibrillation efficiency coefficient Py is less than 0.600 or exceeds 1.500, it is difficult to reduce the delay time difference of the printed wiring board. The above weft yarn fibrillation efficiency coefficient Py is obtained from the above Dy, Fy, Wy, and By through the above formula (2).

[0044] The above weft yarn fibrillation efficiency coefficient Py is preferably in the range of 0.770 or more and 1.200 or less, more preferably in the range of 0.800 or more and 1.100 or less, further preferably in the range of 0.890 or more and 1.000 or less, and particularly preferably in the range of 0.925 or more and 0.970 or less.

[0045] Here, similar to the above formula (1), the above formula (2) represents the possibility of reducing the delay time difference of the printed wiring board caused by the gaps or overlaps between the filaments constituting the weft yarns, or the gaps or overlaps between the weft yarns.

[0046] In addition, the above formula (3) reflects the aforementioned characteristics of the above formula (1) and the above formula (2), and represents the possibility of reducing the delay time difference of the printed wiring board caused by the gaps or overlaps between the filaments, or the gaps or overlaps between the filaments in the entire glass cloth.

[0047] In addition, in the glass cloth of the present embodiment, if the above-mentioned Rt and Ry are each independently less than 68.6, it is difficult to improve the productivity of the glass cloth while reducing the delay time difference of the printed wiring board and thinning the glass cloth.

[0048] On the other hand, if the above-mentioned Rt and Ry are each independently more than 555.5, it is difficult to achieve a stable warp width or weft width, and it is difficult to reduce the delay time difference of the printed wiring board caused by the gaps between the warps or wefts due to the deviation of the yarn width.

[0049] The above-mentioned Rt is the ratio (Ft / Dt) of the number of filaments Ft of the glass filaments constituting the warp to the filament diameter Dt of the glass filaments constituting the warp. In addition, the above-mentioned Ry is the ratio (Fy / Dy) of the number of filaments Fy of the glass filaments constituting the weft to the filament diameter Dy of the glass filaments constituting the weft.

[0050] Preferably, the above-mentioned Rt and Ry are each independently in the range of 115.5 or more and 277.2 or less.

[0051] In addition, the ratio Rt / Ry of the above-mentioned Rt to the above-mentioned Ry is, for example, in the range of 0.90 or more and 1.10 or less, preferably in the range of 0.95 or more and 1.05 or less, more preferably in the range of 0.97 or more and 1.03 or less, further preferably in the range of 0.98 or more and 1.02 or less, particularly preferably in the range of 0.99 or more and 1.01 or less, and most preferably 1.00.

[0052] In addition, in the glass cloth of the present embodiment, the above-mentioned Pt and Py preferably satisfy the following formula (3-1), more preferably satisfy the following formula (3-2), and further preferably satisfy the following formula (3-3).

[0053] 0.800 ≤ (Pt × Py) 1 / 2 ≤ 1.100…(3-1),

[0054] 0.890 ≤ (Pt × Py) 1 / 2 ≤ 0.970…(3-2),

[0055] 0.900 ≤ (Pt × Py) 1 / 2 ≤ 0.952…(3-3).

[0056] In addition, the ratio of Pt to Py, i.e., Pt / Py, is, for example, in the range of 0.80 or more and 1.20 or less, preferably in the range of 0.85 or more and 1.15 or less, more preferably in the range of 0.90 or more and 1.10 or less, further preferably in the range of 0.93 or more and 1.07 or less, particularly preferably in the range of 0.95 or more and 1.05 or less, especially preferably in the range of 0.96 or more and 1.04 or less, and most preferably in the range of 0.97 or more and 1.03 or less.

[0057] In addition, in the glass cloth of the present embodiment, the tex count (tex number) (grams of mass per 1 km) of the above-mentioned warp and weft yarns are each independently, for example, in the range of 3.0 to 50.0 tex (g / km), more preferably in the range of 3.5 to 25.0 tex (g / km), and further preferably in the range of 4.0 to 18.0 tex (g / km).

[0058] In the glass cloth of the present embodiment, the warp or the weft can be twisted. At this time, the number of twists of the warp or the number of twists of the weft are each independently, for example, in the range of 1.00 turns / 25 mm or less, preferably in the range of 0.70 turns / 25 mm or less, more preferably in the range of 0.50 turns / 25 mm or less, further preferably in the range of 0.40 turns / 25 mm or less, particularly preferably in the range of 0.20 turns / 25 mm or less, especially preferably in the range of 0.09 turns / 25 mm or less, and most preferably 0.00 turns / 25 mm. Here, based on JIS R 3912∶2000, using a twist tester, the number of twists of the above-mentioned warp or the above-mentioned weft is calculated from the number of turns required to untwist the test piece and the length of the test piece under the standard tension before untwisting.

[0059] By having the above configuration, the glass cloth of the present embodiment has a thickness of less than 10.0 μm, preferably 9.4 μm or less, more preferably 9.0 μm or less, and further preferably 8.5 μm or less. As the lower limit of the thickness of the glass cloth of the present embodiment, 2.0 μm can be cited, for example.

[0060] The mass per unit area of the glass cloth of the present embodiment is, for example, in the range of 5.0 to 30.0 g / m 2 preferably in the range of 6.0 to 24.0 g / m 2 more preferably in the range of 7.0 to 21.0 g / m 2 particularly preferably in the range of 8.0 to 16.0 g / m 2 Here, the mass per unit area of the glass cloth is the following average value: The masses of 3 glass cloths cut into a size of 200 mm × 200 mm are measured using a scale based on JIS R3420∶2013, and each is converted into per 1 m2 The value of the quality, and take the average value of this value.

[0061] In the glass cloth of the present embodiment, the ratio of the mass per unit area of the glass cloth to the thickness of the glass cloth (mass per unit area of the glass cloth / thickness of the glass cloth) is, for example, in the range of 1.20 to 3.60, preferably in the range of 1.25 to 2.50, and more preferably in the range of 1.30 to 1.95.

[0062] In addition, in the glass cloth of the present embodiment, it is preferable that the filament diameter Dt of the glass filaments constituting the warp and the filament diameter Dy of the glass filaments constituting the weft are each independently in the range of 2.0 μm or more and 3.8 μm or less, and the above Pt and the above Py satisfy the following formula (4).

[0063] 0.890 ≤ (Pt × Py) 1 / 2 ≤ 0.970…(4).

[0064] The filament diameter of the above warp or the above weft is the average value of the following measured values: the measured values when measuring the diameters of 50 cross-sections of the glass filaments constituting the warp or the weft using a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, trade name: S-3400N, magnification: 3000 times). In addition, the number of glass filaments constituting the above warp or the above weft is the average value of the following measured values: the average value of the measured values when counting the number of glass filaments in 50 cross-sections of the glass filaments constituting the warp or the weft using a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, trade name: S-3400N, magnification: 500 times).

[0065] In addition, the weaving density of the above warp can be obtained by the following method: According to JIS R3420, use a fabric analysis mirror to count the number of the warp in a 25 mm range in the weft direction. In addition, the weaving density of the above weft can be obtained by the following method: According to JIS R3420, use a fabric analysis mirror to count the number of the weft in a 25 mm range in the warp direction.

[0066] In addition, the average yarn width of the above warp or the above weft is the average value of the following measured values: Cut out 3 samples of 100 mm × 100 mm from the respective separated positions of the glass cloth, and measure the yarn widths of 10 of the above warp or the above weft in each sample using a microscope (manufactured by KEYENCE Corporation, trade name: VHX-6000, magnification: 200 times).

[0067] In addition, the thickness of the above glass cloth is the measured value when measuring the thickness at 15 places on the glass cloth according to JIS R 3420∶2013 using a micrometer.

[0068] The above-mentioned glass filaments can be obtained by melting a specified glass batch (glass raw materials) and making it fibrillated. For example, glass filaments having compositions such as E glass fiber (general glass fiber) composition, high-strength glass fiber composition, and low dielectric constant glass fiber composition can be used.

[0069] Here, the above-mentioned E glass fiber composition is as follows: containing 52 to 56% by mass of SiO2, 5 to 10% by mass of B2O3, 12 to 16% by mass of Al2O3, a total of 20 to 25% by mass of CaO and MgO, and a total of 0 to 1% by mass of Na2O, K2O, and Li2O.

[0070] In addition, the above-mentioned high-strength glass fiber composition is as follows: containing 57 to 70% by mass of SiO2, 18 to 30% by mass of Al2O3, 0 to 13% by mass of CaO, 5 to 15% by mass of MgO, a total of 0 to 1% by mass of Na2O, K2O, and Li2O, 0 to 1% by mass of TiO2, and 0 to 2% by mass of B2O3.

[0071] In addition, the above-mentioned low dielectric constant glass fiber composition is as follows: containing 48 to 62% by mass of SiO2, 17 to 26% by mass of B2O3, 9 to 18% by mass of Al2O3, 0.1 to 9% by mass of CaO, 0 to 6% by mass of MgO, a total of 0.05 to 0.5% by mass of Na2O, K2O, and Li2O, 0 to 5% by mass of TiO2, 0 to 6% by mass of SrO, a total of 0 to 3% by mass of F2 and Cl2, and 0 to 6% by mass of P2O5.

[0072] From the viewpoint of versatility, the above-mentioned glass filaments are preferably the above-mentioned E glass fiber composition. From the viewpoint of suppressing warping after forming a prepreg, the above-mentioned glass filaments are preferably the above-mentioned high-strength glass fiber composition. At this time, the above-mentioned high-strength glass fiber composition further preferably contains 64 to 66% by mass of SiO2, 24 to 26% by mass of Al2O3, 9 to 11% by mass of MgO, and contains a total of 99% by mass or more of SiO2, Al2O3, and MgO.

[0073] The above-mentioned glass filaments having a number of filaments in the range of 150 to 3000 are bundled by a method which is well-known per se, wound around a winding tube, or further unwound from the above-mentioned winding tube to a bobbin. Sometimes, the material formed by winding the bundled above-mentioned glass filaments (glass rovings) around the above-mentioned winding tube is called a cheesecake. In addition, sometimes the device for winding the above-mentioned glass rovings around the above-mentioned bobbin is called a glass yarn package.

[0074] Here, the above-mentioned glass filaments usually have a circular cross-sectional shape, but may also have a flat cross-sectional shape such as an oval or an oblong shape. When the above-mentioned glass filaments have a flat cross-sectional shape, the ratio of the major axis to the minor axis is, for example, in the range of 1.1 to 10.0. In addition, when the above-mentioned glass filaments have a flat cross-sectional shape, the filament diameter refers to the diameter of a circle having the same area as the flat cross-sectional shape. It should be noted that when the above-mentioned glass filaments have a circular cross-sectional shape, the above ratio of the major axis to the minor axis is equivalent to 1.0.

[0075] Pull out the above-mentioned glass raw filaments from the above-mentioned spindles or pull out the above-mentioned glass yarns from the above-mentioned glass yarn packages, adjust the twist number of the above-mentioned glass raw filaments or the above-mentioned glass yarn packages as needed, and perform yarn splitting treatment, whereby the above-mentioned warp yarns and the above-mentioned weft yarns used for the glass cloth of the present embodiment can be obtained.

[0076] In order to facilitate splitting of the above-mentioned glass raw filaments or the above-mentioned glass yarn packages during the above-mentioned yarn splitting treatment, the twist number of the above-mentioned glass raw filaments or the above-mentioned glass yarn packages is adjusted. The twist number of the above-mentioned glass raw filaments or the above-mentioned glass yarn packages can be adjusted to, for example, 1.0 turn / 25 mm or less, and preferably the twist number is adjusted to 0.7 turn / 25 mm or less, and more preferably adjusted to 0.2 turn / 25 mm or less. A untwisting machine or a stranding machine can be used to adjust the twist number of the above-mentioned glass raw filaments or the above-mentioned glass yarn packages.

[0077] Examples of the above-mentioned yarn splitting treatment include: yarn splitting using water pressure, yarn splitting using high-frequency vibration such as ultrasonic waves with a liquid as a medium, yarn splitting using fluid pressure with surface pressure, and yarn splitting using pressure from rollers, etc.

[0078] The glass cloth of the present embodiment can be obtained by the following method: using the above-mentioned warp yarns and the above-mentioned weft yarns, weaving with a loom known per se and performing splitting treatment. Examples of the above-mentioned loom include: jet looms such as air jet looms or water jet looms, shuttle looms, rapier looms, etc. In addition, examples of the weaving method using the above-mentioned loom include plain weave, satin weave, basket weave, twill weave, etc.

[0079] Examples of the above-mentioned splitting treatment include: splitting using water pressure, splitting using high-frequency vibration such as ultrasonic waves with a liquid as a medium, splitting using fluid pressure with surface pressure, splitting using pressure from rollers, etc. In these splitting treatments, since the splitting treatment using water pressure or the splitting treatment using high-frequency vibration such as ultrasonic waves with a liquid as a medium can respectively reduce the yarn width deviation of the above-mentioned warp yarns and the above-mentioned weft yarns after the splitting treatment, the above-mentioned splitting treatment is preferred. In addition, by using a plurality of splitting treatment methods in combination as the above-mentioned splitting treatment, it is possible to suppress the occurrence of defects in the appearance of the glass cloth such as weft skew caused by the splitting treatment.

[0080] The glass cloth of the present embodiment can be subjected to surface treatment so that a treatment liquid containing a silane coupling agent adheres to the surface of the glass cloth. Here, the surface treatment can be carried out, for example, by the following method: coating a treatment liquid containing the above-mentioned silane coupling agent by a method known per se and drying it.

[0081] Examples of the silane coupling agent include: amino silane, chloro silane, epoxy silane, mercapto silane, vinyl silane, and (meth)acrylic acid silane. In the glass cloth of the present embodiment, the above-mentioned silane coupling agent can be used alone, or two or more of the above-mentioned silane coupling agents can be used in combination.

[0082] Examples of the above-mentioned amino silane include: γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-N’-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, etc.

[0083] Examples of the above-mentioned chloro silane include γ-chloropropyltrimethoxysilane, etc.

[0084] Examples of the epoxy silane include β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, etc.

[0085] Examples of the mercapto silane include γ-mercaptopropyltrimethoxysilane, etc.

[0086] Examples of the vinyl silane include vinyltrimethoxysilane and N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane.

[0087] Examples of the above-mentioned (meth)acrylic acid silane include γ-methacryloxypropyltrimethoxysilane, etc.

[0088] In addition, the treatment liquid containing the above-mentioned silane coupling agent may contain, for example, a surfactant and a pH adjuster in addition to the silane coupling agent.

[0089] Examples of the above-mentioned surfactant include nonionic surfactant, cationic surfactant, anionic surfactant, and amphoteric surfactant. In the glass cloth of the present embodiment, the above-mentioned surfactant can be used alone, or two or more of the above-mentioned surfactants can be used in combination.

[0090] Examples of the above nonionic surfactants include: ethylene oxide-propylene oxide alkyl ethers, polyoxyethylene alkyl ethers, polyoxyethylene-polyoxypropylene block copolymer ethers, alkyl polyoxyethylene-polyoxypropylene block copolymer ethers, polyoxyethylene fatty acid esters, polyoxyethylene fatty acid monoesters, polyoxyethylene fatty acid diesters, polyoxyethylene sorbitan fatty acid esters, ethylene oxide adducts of glycerol fatty acid esters, polyoxyethylene stearyl ethers, ethylene oxide adducts of hydrogenated castor oil, ethylene oxide adducts of alkylamines, ethylene oxide adducts of fatty acid amides, glycerol fatty acid esters, polyglycerol fatty acid esters, pentaerythritol fatty acid esters, sorbitol fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyol alkyl ethers, fatty acid alkanolamides, acetylenic diols, acetylene alcohols, ethylene oxide adducts of acetylenic diols, and ethylene oxide adducts of acetylene alcohols.

[0091] Examples of the above cationic surfactants include: alkyl dimethyl benzyl ammonium chlorides, alkyl trimethyl ammonium chlorides, alkyl dimethyl ethyl ammonium ethyl sulfates, higher alkylamine acetates, ethylene oxide adducts of higher alkylamines, condensates of higher fatty acids and polyalkylene polyamines, salts of esters of higher fatty acids and alkanolamines, higher fatty acid amide salts, imidazoline type cationic surfactants, and alkyl pyridinium salts. Examples of the above higher alkylamine acetates include acetates, hydrochlorides, etc.

[0092] Examples of the above anionic surfactants include: higher alcohol sulfates, higher alkyl ether sulfates, α-olefin sulfates, alkyl benzene sulfonates, α-olefin sulfonates, reaction products of fatty acid halides and N-methyl taurine, dialkyl sulfosuccinates, higher alcohol phosphates, and phosphates of ethylene oxide adducts of higher alcohols.

[0093] Examples of the above amphoteric surfactants include amino acid type amphoteric surfactants such as alkali metal salts of alkylaminopropanes, betaine type amphoteric surfactants such as alkyl dimethyl betaines, and imidazoline type amphoteric surfactants.

[0094] Examples of the pH adjusters include acetic acid, formic acid, and propionic acid.

[0095] When the glass cloth of this embodiment is surface-treated and an organic substance adheres thereto, the adhesion amount of the organic substance is, for example, in the range of 0.05 to 5.00 parts by mass relative to 100 parts by mass of the glass cloth to which the organic substance adheres. Here, the ratio of the mass of the above organic substance to the mass of the glass cloth to which the organic substance adheres can be obtained by measuring the mass of the test piece before and after heat drying in accordance with JIS R3420:2013. It should be noted that when the mass of the glass cloth decreases due to heat drying, the adhesion amount of the above organic substance is measured while taking this decrease amount into consideration.

[0096] The prepreg of the present embodiment contains the glass cloth of the present embodiment described above.

[0097] The prepreg of the present embodiment can be obtained by the following method: impregnating the above glass cloth with a resin by a method known per se and semi-curing it.

[0098] In the prepreg of the present embodiment, the resin impregnated in the above glass cloth is not particularly limited. Examples of such thermosetting resins include: epoxy resins, phenolic resins, unsaturated polyester resins, melamine resins, modified polyimide resins, maleimide resins, thermosetting polyphenylene ether resins, thermosetting modified polyphenylene ether resins, etc. In addition, examples of thermoplastic resins include: polyamide resins, polyimide resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polyphenylene sulfide resins, polyphenylene ether resins, thermoplastic modified polyphenylene ether resins, fluororesins, liquid crystal polymers (LCP), cycloolefin resins, etc.

[0099] In addition, the printed wiring board of the present embodiment is formed of a prepreg containing the glass cloth of the present embodiment described above.

[0100] The glass cloth of the present embodiment is applicable not only to printed wiring boards but also to cases of electronic devices, separators of fuel cells, etc.

[0101] Next, examples and comparative examples of the present invention are shown.

[0102] Examples

[0103] 〔Reference Example 1〕

[0104] In this reference example, first, glass filaments composed of E glass fibers were spun to obtain glass yarns that form the basis of the warp and weft. The above warp and the above weft are each formed by bundling 38 glass filaments with a filament diameter (Dt, Dy) of 3.6 μm and have a mass of 0.99 tex (g / km).

[0105] Next, the above warp and weft were woven using a rapier loom so that the weaving density (Wt) of the warp became 105 threads / 25 mm and the weaving density (Wy) of the weft became 110 threads / 25 mm to obtain a plain weave glass cloth. Next, the above plain weave glass cloth was subjected to degreasing treatment, surface treatment, and fibrillating treatment.

[0106] The following treatments are carried out as the above-mentioned defatting treatment: The above-mentioned plain weave glass is placed in a heating furnace with an atmosphere temperature of 350°C to 400°C for 60 hours, and the spinning sizing agent and weaving sizing agent attached to the plain weave glass cloth are subjected to thermal decomposition. In addition, as the above-mentioned surface treatment, methacrylsilane is coated on the above-mentioned plain weave glass cloth, and a curing treatment is carried out while continuously passing it through a heating furnace at 130°C. In addition, as the above-mentioned fibrillating treatment, a tension of 50 N is applied to the warp of the above-mentioned plain weave glass cloth, and fibrillating treatment is carried out after setting the water pressure to 1.0 Mpa.

[0107] It should be noted that the tension applied to the warp of the above-mentioned plain weave glass cloth in the processes other than the above-mentioned fibrillating treatment is 70 to 120 N. In the above-mentioned fibrillating treatment, the value of the tension detected by the tension detector is fed back to the guide roller for conveying the above-mentioned plain weave glass cloth, and the tension is adjusted by changing the position of the guide roller. As a result, the glass cloth shown in Table 2 is obtained.

[0108] Next, the glass cloth obtained in this reference example is impregnated with an epoxy resin (manufactured by DIC Corporation, trade name: EPICLON 121N-80N) diluted with methyl ethyl ketone, the resin is infiltrated into the glass cloth, and the excess resin is removed by passing it between slits with a width of 13 μm, and then it is held at a temperature of 150°C for 1 minute with a dryer to semi-cure the glass cloth impregnated with the above-mentioned epoxy resin, and a prepreg is prepared.

[0109] Next, 4 pieces of the obtained prepregs are overlapped and heated and pressed at 200°C and 3 Mpa for 2 hours to prepare Evaluation Substrate A as the cured product of the prepreg.

[0110] Next, 3 pieces of the obtained prepregs are overlapped, copper foils (manufactured by Furukawa Electric Co., Ltd., trade name: FV-WS) are arranged on both sides thereof, and heated and pressed at 200°C and 3 MPa for 2 hours to prepare Evaluation Substrate B. Among them, this Evaluation Substrate B is a copper-clad laminate (metal-clad laminate) with a thickness of 200 μm having copper foils bonded to both sides.

[0111] Next, one side of the metal foil (copper foil) of Evaluation Substrate B is processed to form 10 wirings with a yarn width of 100 to 300 μm, a wire length of 100 mm, and a wire pitch of 20 mm. A prepreg and a metal foil (copper foil) are secondarily laminated on the surface of the side of Evaluation Substrate B where the above-mentioned wirings are formed to form a three-layer board. It should be noted that the yarn width of the wiring is adjusted so that the characteristic impedance of the circuit after forming the three-layer board becomes 50 Ω.

[0112] Next, the delay time of the above-mentioned three-layer board at 20 GHz is measured, and the difference between the maximum value and the minimum value of the obtained delay time is calculated as the delay time difference.

[0113] Moreover, there is a tendency that when the above-mentioned delay time difference is large, deterioration of signal quality due to skew of the differential signal is likely to occur; when the delay time difference is small, deterioration of signal quality due to skew is less likely to occur. Therefore, the signal quality based on skew can be evaluated using the above-mentioned delay time difference as an index.

[0114] 〔Example 1〕

[0115] In this example, first, glass filaments having an E-glass fiber composition were spun to obtain glass yarns that form the basis of warp and weft yarns. The above-mentioned glass yarns are formed by bundling 496 glass filaments with a filament diameter of 3.6 μm and have a mass of 12.92 tex (g / km).

[0116] Next, while applying twist to the above-mentioned glass yarn wound around a bobbin in a direction opposite to the twist direction of the glass yarn, the glass yarn was pulled out from the bobbin, sent out in an untwisted state, and ultrasonic waves generated by an oscillator with a frequency of 100 kHz and an output power of 1.2 kW were applied to the glass yarn in a water bath at 60 °C to perform fibrillating of the glass yarn. Next, the fibrillated glass yarn (fibrillated glass yarn) was wound around a bobbin in such a manner that the fibrillating direction of the glass yarn was parallel to the length direction of the bobbin, and a fibrillated glass yarn package was obtained.

[0117] The average yarn width of the above-mentioned fibrillated glass yarn as the basis of warp and weft yarns is 1700 μm. Here, the measured values of the yarn width of the above-mentioned fibrillated glass yarn were measured at 30 positions every 10 cm using a microscope (manufactured by KEYENCE CORPORATION, trade name: VHX-6000), and the average yarn width of the above-mentioned fibrillated glass yarn was calculated based on the measured values.

[0118] Next, the above-mentioned fibrillated glass yarn was pulled out from a plurality of the above-mentioned fibrillated glass yarn packages to form warp or weft yarns, and a plain weave glass cloth with a warp knitting density (Wt) of 14.0 ends / 25 mm and a weft knitting density (Wy) of 14.0 ends / 25 mm was woven using a rapier loom. Next, the above-mentioned plain weave glass cloth was subjected to degreasing treatment, surface treatment, and fibrillating treatment in exactly the same manner as in Reference Example 1. As a result, the glass cloth shown in Table 1 was obtained.

[0119] Next, except for using the glass cloth of this example, prepregs, evaluation substrate A as a cured product of the prepreg, and a three-layer board composed of evaluation substrate B as a copper-clad laminate (metal-clad laminate) were prepared in exactly the same manner as in Reference Example 1, and the delay time difference of the three-layer board was calculated.

[0120] Next, the degree of reduction in the delay time difference, the stability of the glass cloth yarn width, and the productivity of the glass cloth of this example were evaluated in the following manner. The results are shown in Table 1.

[0121] [Degree of reduction in delay time difference]

[0122] Based on the delay time difference of Reference Example 1, the case where the delay time difference is 50% or less is evaluated as "A (excellent)", the case where the delay time difference exceeds 50% and is 90% or less is evaluated as "B (good)", and the case where the delay time difference exceeds 90% is evaluated as "C (acceptable to equivalent)".

[0123] [Width stability of glass cloth yarn]

[0124] Cut out 3 samples of 100 mm × 100 mm at separated positions of the glass cloth, and use a microscope (manufactured by Keyence Corporation, product name: VHX - 6000) to measure the yarn widths of 10 warp or weft yarns of each sample respectively. Based on the measured values, calculate the average value and standard deviation of the above - mentioned warp and weft yarns, and calculate the coefficient of variation (standard deviation / average value) based on this average value and this standard deviation. Then, calculate the average value (average coefficient of variation) of the coefficient of variation of the above - mentioned warp yarn and the coefficient of variation of the above - mentioned weft yarn. The case where the above - mentioned average coefficient of variation is 0.10 or less is evaluated as "A", and the case where the above - mentioned average coefficient of variation exceeds 0.10 is evaluated as "B".

[0125] [Productivity of glass cloth]

[0126] Measure the time required to weave 1000 m of glass cloth using a rapier loom (1000 m weaving time). Based on the 1000 m weaving time of Reference Example 1, the case where the 1000 m weaving time is 30% or less is evaluated as "OK", and the case where the 1000 m weaving time exceeds 30% is evaluated as "NG".

[0127] [Example 2]

[0128] In this example, first, spin glass filaments composed of E - glass fiber to obtain glass yarns that form the basis of warp and weft yarns. The glass yarns are formed by bundling glass filaments with a filament diameter of 3.6 μm and 334 filaments, and have a mass of 8.70 tex (g / km). Then, use the fibrillated glass yarn with an average yarn width of 1081 μm obtained by fibrillating the above - mentioned glass yarns. Set the warp knitting density (Wt) to 20.8 picks / 25 mm and the weft knitting density (Wy) to 20.8 picks / 25 mm. Except for this, produce the glass cloth shown in Table 1 in exactly the same manner as in Example 1.

[0129] Next, except for using the glass cloth of this example, prepregs were prepared in exactly the same manner as in Reference Example 1, an evaluation substrate A as a cured product of the prepreg, and a three-layer board composed of an evaluation substrate B as a copper-clad laminate (metal-clad laminate), and the delay time difference of the three-layer board was calculated.

[0130] Next, the degree of reduction in the delay time difference, the glass cloth yarn width stability, and the glass cloth productivity of the glass cloth of this example were evaluated in exactly the same manner as in Example 1. The results are shown in Table 1.

[0131] 〔Example 3〕

[0132] In this example, first, glass filaments composed of E glass fibers were spun to obtain glass yarns that form the basis of the warp and weft yarns. The glass yarns were formed by bundling 360 glass filaments with a filament diameter of 2.6 μm and had a mass of 4.89 tex (g / km). Next, using the fibrillated glass yarn with an average yarn width of 925 μm obtained by fibrillating the above glass yarns, the warp knitting density (Wt) was set to 26.0 threads / 25 mm, and the weft knitting density (Wy) was set to 26.0 threads / 25 mm. Except for this, the glass cloth shown in Table 1 was produced in exactly the same manner as in Example 1.

[0133] Next, except for using the glass cloth of this example, prepregs were prepared in exactly the same manner as in Reference Example 1, an evaluation substrate A as a cured product of the prepreg, and a three-layer board composed of an evaluation substrate B as a copper-clad laminate (metal-clad laminate), and the delay time difference of the three-layer board was calculated.

[0134] Next, the degree of reduction in the delay time difference, the glass cloth yarn width stability, and the glass cloth productivity of the glass cloth of this example were evaluated in exactly the same manner as in Example 1. The results are shown in Table 1.

[0135] 〔Example 4〕

[0136] In this example, first, glass filaments composed of E glass fibers were spun to obtain glass yarns that form the basis of the warp and weft yarns. The glass yarns were formed by bundling 1500 glass filaments with a filament diameter of 3.6 μm and had a mass of 39.08 tex (g / km). Next, using the fibrillated glass yarn with an average yarn width of 5260 μm obtained by fibrillating the above glass yarns, the warp knitting density (Wt) was set to 4.7 threads / 25 mm, and the weft knitting density (Wy) was set to 4.7 threads / 25 mm. Except for this, the glass cloth shown in Table 1 was produced in exactly the same manner as in Example 1.

[0137] Next, except for using the glass cloth of this embodiment, prepregs were prepared in exactly the same manner as in Reference Example 1, an evaluation substrate A as the cured product of the prepreg, and a three-layer board composed of an evaluation substrate B as a copper-clad laminate (metal-clad laminate), and the delay time difference of the three-layer board was calculated.

[0138] Next, the degree of reduction in the delay time difference, the stability of the glass cloth yarn width, and the productivity of the glass cloth of this embodiment were evaluated in exactly the same manner as in Example 1. The results are shown in Table 1.

[0139] 〔Example 5〕

[0140] In this embodiment, first, glass filaments composed of E glass fibers were spun to obtain glass yarns that form the basis of the warp and weft yarns. The glass yarns were formed by bundling 496 glass filaments with a filament diameter of 3.6 μm and had a mass of 12.92 tex (g / km). Next, except for using an oscillator with a frequency of 100 kHz and an output power of 1.6 kW, the above glass yarns were fibrillated in exactly the same manner as in Example 1 to obtain fibrillated glass yarns with an average yarn width of 2230 μm. In addition, except for setting the warp knitting density (Wt) to 14.0 threads / 25 mm and the weft knitting density (Wy) to 14.0 threads / 25 mm, the glass cloth shown in Table 1 was obtained in exactly the same manner as in Example 1.

[0141] Next, except for using the glass cloth of this embodiment, prepregs were prepared in exactly the same manner as in Reference Example 1, an evaluation substrate A as the cured product of the prepreg, and a three-layer board composed of an evaluation substrate B as a copper-clad laminate (metal-clad laminate), and the delay time difference of the three-layer board was calculated.

[0142] Next, the degree of reduction in the delay time difference, the stability of the glass cloth yarn width, and the productivity of the glass cloth of this embodiment were evaluated in exactly the same manner as in Example 1. The results are shown in Table 1.

[0143] 〔Example 6〕

[0144] In this embodiment, first, glass filaments composed of E glass fibers were spun to obtain glass yarns that form the basis of the warp and weft yarns. The glass yarns were formed by bundling 550 glass filaments with a filament diameter of 4.0 μm and had a mass of 17.69 tex (g / km). Next, fibrillated glass yarns with an average yarn width of 2120 μm obtained by fibrillating the above glass yarns were used, and the warp knitting density (Wt) was set to 11.3 threads / 25 mm and the weft knitting density (Wy) was set to 11.3 threads / 25 mm. Except for this, the glass cloth shown in Table 1 was obtained in exactly the same manner as in Example 1.

[0145] Next, except for using the glass cloth of this embodiment, prepregs were prepared in exactly the same manner as in Reference Example 1, an evaluation substrate A as a cured product of the prepreg, and a three-layer board composed of an evaluation substrate B as a copper-clad laminate (metal-clad laminate), and the delay time difference of the three-layer board was calculated.

[0146] Next, the degree of reduction in the delay time difference, the glass cloth yarn width stability, and the glass cloth productivity of the glass cloth of this embodiment were evaluated in exactly the same manner as in Example 1. The results are shown in Table 1.

[0147] 〔Comparative Example 1〕

[0148] In this comparative example, first, glass filaments made of E glass fiber were spun to obtain glass yarns that form the basis of warp and weft yarns. The glass yarns were bundled from 496 glass filaments with a filament diameter of 3.6 μm and had a mass of 12.92 tex (g / km). Next, except for using an oscillator with a frequency of 100 kHz and an output power of 0.6 kW, the above glass yarns were fibrillated in exactly the same manner as in Example 1 to obtain fibrillated glass yarns with an average yarn width of 891 μm. Also, except for setting the warp knitting density (Wt) to 28.0 threads / 25 mm and the weft knitting density (Wy) to 28.0 threads / 25 mm, a glass cloth shown in Table 2 was obtained in exactly the same manner as in Example 1.

[0149] Next, except for using the glass cloth of this comparative example, prepregs were prepared in exactly the same manner as in Reference Example 1, an evaluation substrate A as a cured product of the prepreg, and a three-layer board composed of an evaluation substrate B as a copper-clad laminate (metal-clad laminate), and the delay time difference of the three-layer board was calculated.

[0150] Next, the degree of reduction in the delay time difference, the glass cloth yarn width stability, and the glass cloth productivity of the glass cloth of this comparative example were evaluated in exactly the same manner as in Example 1. The results are shown in Table 2.

[0151] 〔Comparative Example 2〕

[0152] In this comparative example, first, glass filaments made of E glass fiber were spun to obtain glass yarns that form the basis of the warp and weft yarns. The glass yarns were formed by bundling 496 glass filaments with a filament diameter of 3.6 μm and had a mass of 12.92 tex (g / km). Next, except for using an oscillator with a frequency of 100 kHz and an output power of 0.8 kW, the above glass yarns were fibrillated in exactly the same manner as in Example 1 to obtain fibrillated glass yarns with an average yarn width of 1158 μm. And, except for setting the warp knitting density (Wt) to 14.0 threads / 25 mm and the weft knitting density (Wy) to 14.0 threads / 25 mm, the glass cloth shown in Table 2 was obtained in exactly the same manner as in Example 1 in other respects.

[0153] Next, except for using the glass cloth of this comparative example, prepregs, evaluation substrate A as the cured product of the prepreg, and a three-layer board composed of evaluation substrate B as a copper-clad laminate (metal-clad laminate) were prepared in exactly the same manner as in Reference Example 1, and the delay time difference of the three-layer board was calculated.

[0154] Next, the degree of reduction in the delay time difference, the stability of the glass cloth yarn width, and the productivity of the glass cloth of this comparative example were evaluated in exactly the same manner as in Example 1. The results are shown in Table 2.

[0155] 〔Comparative Example 3〕

[0156] In this comparative example, first, glass filaments made of E glass fiber were spun to obtain glass yarns that form the basis of the warp and weft yarns. The glass yarns were formed by bundling 2500 glass filaments with a filament diameter of 3.6 μm and had a mass of 65.13 tex (g / km). Next, fibrillated glass yarns with an average yarn width of 8760 μm obtained by fibrillating the above glass yarns were used, and the warp knitting density (Wt) was set to 2.8 threads / 25 mm and the weft knitting density (Wy) was set to 2.8 threads / 25 mm. Except for this, the glass cloth shown in Table 2 was obtained in exactly the same manner as in Example 1 in other respects.

[0157] Next, except for using the glass cloth of this comparative example, prepregs, evaluation substrate A as the cured product of the prepreg, and a three-layer board composed of evaluation substrate B as a copper-clad laminate (metal-clad laminate) were prepared in exactly the same manner as in Reference Example 1, and the delay time difference of the three-layer board was calculated.

[0158] Next, the degree of reduction in the delay time difference, the stability of the glass cloth yarn width, and the productivity of the glass cloth of this comparative example were evaluated in exactly the same manner as in Example 1. The results are shown in Table 2.

[0159] 〔Comparative Example 4〕

[0160] In this comparative example, first, glass filaments made of E glass fiber were spun to obtain glass yarns that form the basis of the warp and weft yarns. The glass yarns were formed by bundling 160 glass filaments with a filament diameter of 3.6 μm and had a mass of 4.17 tex (g / km). Next, using the fibrillated glass yarns with an average yarn width of 550 μm obtained by fibrillating the above glass yarns, the warp knitting density (Wt) was set to 43.4 threads / 25 mm, and the weft knitting density (Wy) was set to 43.4 threads / 25 mm. Other than this, a glass cloth shown in Table 2 was obtained in exactly the same manner as in Example 1.

[0161] Next, except for using the glass cloth of this comparative example, a prepreg, an evaluation substrate A as the cured product of the prepreg, and a three-layer board composed of an evaluation substrate B as a copper-clad laminate (metal-clad laminate) were prepared in exactly the same manner as in Reference Example 1, and the delay time difference of the three-layer board was calculated.

[0162] Next, the degree of reduction in the delay time difference, the stability of the glass cloth yarn width, and the productivity of the glass cloth of this comparative example were evaluated in exactly the same manner as in Example 1. The results are shown in Table 2.

[0163] [Comparative Example 5]

[0164] In this comparative example, first, glass filaments made of E glass fiber were spun to obtain glass yarns that form the basis of the warp and weft yarns. The glass yarns were formed by bundling 689 glass filaments with a filament diameter of 5.0 μm and had a mass of 34.63 tex (g / km). Next, using the fibrillated glass yarns with an average yarn width of 3250 μm obtained by fibrillating the above glass yarns, the warp knitting density (Wt) was set to 7.3 threads / 25 mm, and the weft knitting density (Wy) was set to 7.3 threads / 25 mm. Other than this, a glass cloth shown in Table 2 was obtained in exactly the same manner as in Example 1.

[0165] Next, except for using the glass cloth of this comparative example, a prepreg, an evaluation substrate A as the cured product of the prepreg, and a three-layer board composed of an evaluation substrate B as a copper-clad laminate (metal-clad laminate) were prepared in exactly the same manner as in Reference Example 1, and the delay time difference of the three-layer board was calculated.

[0166] Next, the degree of reduction in the delay time difference, the stability of the glass cloth yarn width, and the productivity of the glass cloth of this comparative example were evaluated in exactly the same manner as in Example 1. The results are shown in Table 2.

[0167] [Table 1]

[0168] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Warp filament diameter (μm); Dt 3.6 3.6 2.6 3.6 3.6 4.0 Number of warp filaments (pcs); Ft 496 334 360 1500 496 550 Warp knitting density (pcs / 25 mm); Wt 14.0 20.8 26.0 4.7 11.0 11.3 Average warp yarn width (μm); Bt 1690 1080 920 5250 2200 2100 Number of warp filaments / warp filament diameter; Rt 137.8 92.8 138.5 416.7 137.8 137.5 Warp fibrillation efficiency coefficient; Pt 0.946 0.899 0.944 0.994 0.858 0.947 Weft filament diameter (μm); Dy 3.6 3.6 2.6 3.6 3.6 4.0 Number of weft filaments (pcs); Fy 496 334 360 1500 496 550 Weft knitting density (pcs / 25 mm); Wy 14.0 20.8 26.0 4.7 11.0 11.3 Average weft yarn width (μm); By 1710 1083 930 5270 2250 2130 Number of weft filaments / weft filament diameter; Rv 137.8 92.8 138.5 416.7 137.8 137.5 Weft fibrillation efficiency coefficient; Py 0.958 0.901 0.954 0.998 0.878 0.960 <![CDATA[(Pt×Py) 1 / 2 > 0.952 0.900 0.949 0.996 0.868 0.953 Glass cloth thickness (μm) 8.0 8.0 5.7 8.4 8.0 9.2 Degree of reduction in delay time difference A A A A B A Glass cloth yarn width stability A A A B A A Glass cloth productivity OK OK OK OK OK OK

[0169] Pt; {(Bt / (Dt × Ft)) × Bt / (25000 / Wt)} 1 / 2 × (Dt × Ft) / (25000 / Wt)}

[0170] Py; {(By / (Dy × Fy)) × By / (25000 / Wy)} 1 / 2 × (Dy × Fy) / (25000 / Wy)}

[0171] [Table 2]

[0172] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Reference Example 1 Warp filament diameter (μm); Dt 3.6 3.6 3.6 3.6 5.0 3.6 Number of warp filaments (pcs); Ft 496 496 2500 160 689 38 Warp knitting density (pcs / 25 m); Wt 28.0 14.0 2.8 43.4 7.3 105 Average warp yarn width (μm); Bt 890 1155 8750 540 3250 137 Number of warp filaments / warp filament diameter; Rt 137.8 137.8 694.4 44.4 137.8 10.6 Warp fibrillation efficiency coefficient; Pt 1.410 0.647 0.984 0.937 0.952 0.436 Weft filament diameter (μm); Dy 3.6 3.6 3.6 3.6 5.0 3.6 Number of weft filaments (pcs); Fy 496 496 2500 160 689 38 Weft knitting density (pcs / 25 m); Wy 28.0 14.0 2.8 43.4 7.3 110 Average weft yarn width (μm); By 892 1160 8760 560 3250 185 Number of weft filaments / weft filament diameter; Ry 137.8 137.8 694.4 44.4 137.8 10.6 Weft fibrillation efficiency coefficient; Py 1.413 0.650 0.985 0.972 0.952 0.632 <![CDATA[(Pt×Py) 1 / 2 > 1.411 0.648 0.984 0.955 0.952 0.525 Glass cloth thickness (μm) 9.5 8.0 9.5 8.0 13.5 10.0 Degree of reduction in delay time difference C C C A A C Glass cloth yarn width stability A A B A A - Glass cloth productivity OK OK OK NG OK -

[0173] Pt; {(Bt / (Dt × Ft)) × Bt / (25000 / Wt)} 1 / 2 × (Dt × Ft) / (25000 / Wt)}

[0174] Py; {(By / (Dy × Fy)) × By / (25000 / Wy)} 1 / 2 × (Dy × Fy) / (25000 / Wy)}

[0175] It is obvious from Table 1 that for the glass cloths according to Embodiments 1 to 6 of the present invention, the yarn widths of the warp and weft yarns are stable, the delay time difference of the printed wiring board is reduced, the deterioration of the signal quality can be suppressed, and high productivity can be achieved.

[0176] On the other hand, it is obvious from Table 2 that for the glass cloths of Comparative Example 1 and Comparative Example 2 in which the warp yarn fibrillation efficiency coefficient Pt and the weft yarn fibrillation efficiency coefficient Py do not satisfy the above formula (3), the degree of reduction in the delay time difference is comparable to that of the glass cloth of Reference Example 1.

[0177] In addition, for the glass cloth of Comparative Example 3 in which the aforementioned Rt and Ry exceed 555.5, it is obvious that the degree of reduction in the delay time difference is comparable to that of the glass cloth of Reference Example 1, and the stability of the glass cloth yarn width is poor.

[0178] In addition, for the glass cloth of Comparative Example 4 in which the aforementioned Rt and Ry are less than 68.6, it is obvious that there is a problem of poor productivity of the glass cloth.

[0179] In addition, for the glass cloth of Comparative Example 5 in which the filament diameter Dt of the glass filaments constituting the warp yarn and the filament diameter Dy of the glass filaments constituting the weft yarn exceed 4.5 μm, it is obvious that its thickness exceeds 10.0 μm.

Claims

1. A glass cloth is composed of warp yarns and weft yarns respectively formed by bundling multiple glass filaments. The characteristics of this glass cloth are as follows: The filament diameter Dt of the glass filaments constituting the warp yarns and the filament diameter Dy of the glass filaments constituting the weft yarns are each independently in the range of 0.5 μm or more and 4.5 μm or less. The number of filaments Ft of the glass filaments constituting the warp yarns and the number of filaments Fy of the glass filaments constituting the weft yarns are each independently in the range of 150 or more and 3000 or less. The knitting density Wt of the warp yarns and the knitting density Wy of the weft yarns are each independently in the range of 1.0 yarn / 25 mm or more and 50.0 yarns / 25 mm or less. The average yarn width Bt of the warp yarns and the average yarn width By of the weft yarns are each independently in the range of 550 μm or more and 10000 μm or less. The warp yarn fibrillation efficiency coefficient Pt calculated from the Dt, Ft, Wt, and Bt by the following formula (1) is in the range of 0.600 or more and 1.500 or less. The weft yarn fibrillation efficiency coefficient Py calculated from the Dy, Fy, Wy, and By by the following formula (2) is in the range of 0.600 or more and 1.500 or less. The ratio Ft / Dt of the number of filaments Ft of the glass filaments constituting the warp yarns to the filament diameter Dt of the glass filaments constituting the warp yarns, that is, Rt, and the ratio Fy / Dy of the number of filaments Fy of the glass filaments constituting the weft yarns to the filament diameter Dy of the glass filaments constituting the weft yarns, that is, Ry, are each independently in the range of 68.6 or more and 555.5 or less. The Pt and the Py satisfy the following formula (3), and the thickness of the glass cloth is less than 10.0 μm. Pt = { (Bt / (Dt × Ft)) × Bt / (25000 / Wt)} 1 / 2 × { (Dt × Ft) / (25000 / Wt)}…(1), Py = {(By / (Dy × Fy)) × By / (25000 / Wy)} 1 / 2 ×{(Dy × Fy) / (25000 / Wy)}…(2), 0.770 ≤ (Pt × Py) 1 / 2 ≤ 1.200 … (3).

2. The glass cloth according to claim 1, characterized in that: The filament diameter Dt of the glass filaments constituting the warp yarns and the filament diameter Dy of the glass filaments constituting the weft yarns are each independently in the range of 2.0 μm or more and 3.8 μm or less, and the Pt and the Py satisfy the following formula (4). 0.890 ≤ (Pt × Py) 1 / 2 ≤ 0.970 … (4).

3. A prepreg, characterized in that, Comprising the glass cloth according to claim 1 or 2.

4. A printed wiring board, characterized in that, Comprising the glass cloth according to claim 1 or 2.