Glass cloth, prepreg and printed wiring board

Abstract

Glass cloth, prepreg, and printed wiring board. [Problem] To provide a glass cloth suitable for consistently achieving sufficient adhesive strength even with a combination of low-roughness metal foil and low-dielectric resin. [Solution] A glass cloth of 5-100 μm thickness, woven from glass filaments containing multiple glass filaments as warp and weft, wherein the aforementioned weft filament filament filament filament percentage (%), which represents the proportion of the portion containing weft filaments in the MD direction, obtained by formula (1): weft filament ... 95％ -W 5％ ) / W 50％ The aforementioned wire width variation coefficient A obtained by formula (2) is the following value obtained by formula (3): 0.0056×e(-0.160×T)….

Description

Technical Field

[0001] This invention relates to glass cloth, prepreg, and printed wiring boards. Background Technology

[0002] With the rapid development of information and communication technology in recent years, and the high-capacity and high-speed data communication and / or signal processing, the transmission speed of signals on electronic circuit boards has increased dramatically. As signal speeds increase, there is a need to reduce transmission losses in printed circuit boards. Methods for reducing transmission losses in printed circuit boards include methods for reducing the dielectric of the matrix resin constituting the insulating substrate and the glass cloth; and methods for reducing the surface roughness of the metal foil (see, for example, Patent Documents 1 and 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-127144

[0006] Patent Document 2: International Publication No. 2020 / 027189 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] However, the adhesion between metal foils with small surface roughness and low-dielectric substrates made of low-dielectric resin and low-dielectric glass cloth is reduced compared to the case of using metal foils with large surface roughness.

[0009] Patent Document 1 discloses a laminate with a metal foil peel strength of 0.6 N / mm or higher for a metal foil having a surface roughness Rz of 2.0 μm or less. However, the laminate described in Patent Document 1 suffers from difficulty in achieving sufficient adhesion when the polarity of the matrix resin decreases due to the demand for high-speed signals.

[0010] Patent Document 2 discloses a laminate that attempts to improve adhesion by using a low-dielectric matrix resin, a metal foil with a surface roughness (Rz) of less than 2.0 μm, and core-shell polymer particles with a volume average particle size of 10 nm to 400 nm. However, the laminate described in Patent Document 2 still has room for improvement in terms of peel strength from the metal foil, and there is a problem that it is difficult to obtain sufficient adhesion.

[0011] The present invention was made in view of the above-mentioned problems, and its object is to provide a glass cloth suitable for consistently achieving sufficient adhesive strength even with a combination of low-roughness metal foil and low-dielectric resin. Furthermore, the present invention aims to provide prepregs and printed wiring boards using this glass cloth.

[0012] Solution for solving the problem

[0013] One aspect of the present invention is described below. [1]

[0015] A type of glass cloth, which is woven from glass filaments containing multiple long glass filaments as warp and weft yarns, and has a thickness of 5-100 μm.

[0016] The weft yarn percentage (%), which represents the proportion of the portion containing weft yarns in the MD direction, calculated using the following formula (1), is 86.0%–107.0%.

[0017] Weft yarn occupancy rate = W / (25000 / G)×100…Equation (1)

[0018] {In the formula, W is the average width of the weft yarn (μm), and G is the fabric density of the weft yarn (yarns / 25mm).}

[0019] The following wire width variation coefficient A, obtained using formula (2), is the value obtained using formula (3).

[0020] The weft width variation coefficient A = (W 95％ -W 5％ ) / W 50％ / F…Formula (2)

[0021] In the formula, W 95％ To determine the cumulative 95% weft width (μm) in the cumulative weft width distribution measured along the weft direction from one end to the opposite end, using the smaller side as the starting point, W 5％ To accumulate 5% weft width (μm), W 50％ To accumulate 50% of the weft width (μm), F represents the number of weft filaments.

[0022] 0.0056×e(-0.160×T)…Equation (3)

[0023] In the formula, T represents the TEX of the weft yarn. [2]

[0025] According to the glass cloth described in Project 1, the sum of the following warp occupancy rate (%), which represents the proportion of warp yarns in the TD direction, calculated using the following formula (4), and the aforementioned weft occupancy rate is 150 to 200%.

[0026] Warp yarn occupancy rate = X / (25000 / H)×100…Equation (4)

[0027] {In the formula, X is the warp width (μm), and H is the fabric density of warp yarns (yarns / 25mm).} [3]

[0029] According to the glass cloth described in Project 1 or 2, the following wire width variation coefficient α, obtained by formula (5), is the value obtained by formula (6).

[0030] The coefficient of variation of the weft width is α = W / F…Equation (5)

[0031] {In the formula, W is the standard deviation of the weft width (μm), and F is the number of weft filaments.}

[0032] 0.5×e(-0.1×T)…Equation (6)

[0033] In the formula, T represents the TEX of the weft yarn. [4]

[0035] The glass cloth according to any one of items 1 to 3, wherein the elastic modulus of the aforementioned glass filaments is 50 to 70 GPa. [5]

[0037] The glass cloth according to any one of items 1 to 3, wherein the elastic modulus of the aforementioned glass filaments is 50 to 63 GPa. [6]

[0039] A prepreg comprising glass cloth and thermosetting resin as described in any one of items 1 to 5. [7]

[0041] A printed wiring board containing the prepreg described in item 6.

[0042] The effects of the invention

[0043] According to the present invention, a glass cloth suitable for consistently achieving sufficient adhesive strength even with a combination of low-roughness metal foil and low-dielectric resin can be provided.

[0044] In addition, according to the present invention, a prepreg and a printed wiring board using the glass cloth can be provided. Detailed Implementation

[0045] The embodiments of the present invention (hereinafter referred to as "this embodiment") will be described in detail below. The present invention is not limited to this embodiment, and various modifications can be made without departing from its spirit. In this specification, within a numerical range recorded in stages, the upper or lower limit value recorded in a certain numerical range can be replaced with the upper or lower limit value of other numerical ranges recorded in stages. Furthermore, in this specification, the upper or lower limit value recorded in a certain numerical range can also be replaced with the values ​​shown in the embodiments.

[0046] In this embodiment, the inventors thoroughly investigated and identified one of the reasons for the reduced adhesion between the low-roughness metal foil and the low-dielectric substrate as being related to the deviation in the resin layer thickness in the composite of the low-dielectric resin and the glass cloth. Furthermore, they discovered that when the variation in the weft width of the glass cloth is within a specific range, the deviation in the resin layer thickness decreases, and the adhesion between the metal foil and the low-dielectric substrate improves. This embodiment is achieved based on the above findings.

[0047] [Glass cloth]

[0048] The glass cloth in this embodiment is a glass cloth with a thickness of 5 to 100 μm, woven from glass filaments containing multiple glass filaments as warp and weft yarns respectively.

[0049] The weft occupancy rate (%), which represents the proportion of the portion containing weft threads in the MD direction, obtained using the following formula (1), is 86.0% to 107.0%.

[0050] Weft yarn occupancy rate = W / (25000 / G)×100…Equation (1)

[0051] {In the formula, W is the average width of the weft yarn (μm), and G is the fabric density of the weft yarn (yarns / 25mm).}

[0052] The following wire width variation coefficient A, obtained using formula (2), is the value obtained using formula (3).

[0053] The weft width variation coefficient A = (W 95％ -W 5％ ) / W 50％ / F…Formula (2)

[0054] In the formula, W 95％ To determine the cumulative 95% weft width (μm) in the cumulative weft width distribution measured along the weft direction from one end to the opposite end, using the smaller side as the starting point, W 5％ To accumulate 5% weft width (μm), W 50％ To accumulate 50% of the weft width (μm), F represents the number of weft filaments.

[0055] 0.0056×e(-0.160×T)…Equation (3)

[0056] In the formula, T represents the TEX of the weft yarn.

[0057] In printed circuit boards used for high-speed communications, glass cloth with increased uniformity of glass distribution in the planar direction is typically used to reduce differences in signal propagation speeds within the transmission lines. Generally, because the glass cloth is subjected to tensile tension during transport and fiber opening, the weft yarns are easier to widen compared to the tension-constrained warp yarns. Therefore, the weft yarns are typically widened and arranged in the MD direction, thereby increasing the weft yarn occupancy rate and improving the glass distribution in the planar direction.

[0058] However, it is known that in low-dielectric glass, for low-dielectric glass cloths with a high weft fiber ratio, the adhesion to low-roughness metal foils is worse compared to conventional E-glass cloths. Furthermore, a detailed investigation of low-dielectric glass cloths with worse adhesion to low-roughness metal foils reveals a common characteristic: compared to conventional E-glass cloths, low-dielectric glass cloths with a high weft fiber ratio exhibit decreased surface smoothness. While the reasoning is not theoretically confined, it is believed that for glass cloths with decreased surface smoothness, there are localized areas of thin matrix resin layers in the substrate within the composite with the matrix resin. Stress concentrates at these areas, thus becoming the starting point for adhesion failure between the metal foil and the matrix resin.

[0059] Furthermore, the inventors conducted a detailed investigation into the reasons for the deterioration of the surface smoothness of low dielectric glass cloth with a high weft fiber content. The results showed that during the process of forming a fabric structure by widening / flattening the glass fiber bundles through the fiber opening process of the glass cloth, unevenness between the fine and coarse parts is generated in the same weft fiber, which in turn causes large deformation in the undulating structure, resulting in unevenness.

[0060] In contrast, even the glass cloth of this embodiment, which has a high glass distribution in the face direction based on the weft yarns, such as a weft yarn percentage (%) of 86.0% to 107.0%, exhibits improved surface smoothness by keeping the weft yarn width variation coefficient A within a specific range, thereby improving adhesion to low-roughness metal foils. It should be noted that the weft yarn percentage (%) is the ratio of the portion containing weft yarns in the MD direction, and the weft yarn width variation coefficient A is an indicator of the difference between the wide and narrow portions of the weft yarn width.

[0061] [Weft yarn market share]

[0062] For the glass cloth of this embodiment, the weft yarn percentage (%) calculated using the above formula (1) is 86.0 to 107.0%.

[0063] The preferred range for the weft yarn percentage is 88.0%–106.0%, the more preferred range is 89.0%–105.0%, and the even more preferred range is 90.0%–104.5%.

[0064] If the weft yarn content is 86% or higher, interference occurs between adjacent weft yarns during the yarn width widening process in the fiber opening step. This results in increased unevenness between thin and thick portions within the same weft yarn. Consequently, the surface roughness increases, leading to reduced adhesion to low-roughness metal foil. In this embodiment, even with a weft yarn content of 86% or higher, by keeping the weft yarn width variation coefficient within a specific range, a glass cloth with excellent surface smoothness is obtained, thereby achieving strong adhesion to low-roughness metal foil, which is therefore preferable.

[0065] Furthermore, by controlling the weft yarn occupancy rate to be below 107% as described above, the weft yarn width variation coefficient in this embodiment can be maintained, thereby maintaining a small surface smoothness.

[0066] The weft yarn occupancy rate can be controlled within the above range, for example, by adjusting the fabric density of the weft yarn or by adjusting the yarn width through the opening of the weft yarn.

[0067] [The sum of weft yarn percentage and warp yarn percentage]

[0068] In this embodiment, the sum of the following warp occupancy rate (%), which represents the ratio of warp filaments in the TD direction, obtained by formula (4), and the weft occupancy rate obtained by formula (1) is preferably 150 to 200%.

[0069] Warp yarn occupancy rate = X / (25000 / H)×100…Equation (4)

[0070] {In the formula, X is the warp width (μm), and H is the fabric density of warp yarns (yarns / 25mm).}

[0071] If the sum of the weft and warp occupancy rates is 150% or more, the interference of the warp occupancy rates with the undulating structure of the weft occupancy rates tends to increase. This makes it easier to promote deformation of the uneven weft occupancy structure, which has both thick and thin sections, resulting in increased surface roughness and consequently reduced adhesion to low-roughness metal foils. In this embodiment, by keeping the weft occupancy rate variation coefficient within a specific range, excellent surface smoothness is achieved. Therefore, even when the sum of the weft and warp occupancy rates is 150% or more, strong adhesion to low-roughness metal foils is obtained, which is preferable.

[0072] Furthermore, by controlling the weft yarn width variation coefficient in this embodiment to be less than 200% of the sum of the weft yarn occupancy rate and the warp yarn occupancy rate, it is easier to maintain a small surface smoothness, which is therefore preferred.

[0073] The sum of the weft yarn percentage and the warp yarn percentage is more preferably 151% or more, further preferably 152% or more, and most preferably 153% or more. More preferably, it is 198% or less, further preferably 196% or less, and most preferably 195% or less. The warp yarn percentage is preferably 60% or more, more preferably 60.5% or more, and further preferably 61% or more. More preferably, it is 98% or less, more preferably 97% or less, and even more preferably 96% or less. The sum of the warp yarn percentage and the weft yarn percentage can be controlled within the above range, for example, by adjusting the fabric density of the warp and weft yarns, or by adjusting the yarn width through the opening of the warp and weft yarns.

[0074] [Weft yarn width variation coefficient A]

[0075] In this embodiment, the weft width variation coefficient A obtained using the above formula (2) is less than or equal to the value shown in the above formula (3). The preferred weft width variation coefficient A is the following formula (6A):

[0076] 0.0056×e(-0.165×T)…Equation (6A)

[0077] The values ​​shown are as follows, and more preferably, the following formula (7):

[0078] 0.0056×e(-0.170×T)…Equation (7)

[0079] The values ​​shown are below, and the following formula (8) is further preferred:

[0080] 0.0056×e(-0.175×T)…Equation (8)

[0081] The values ​​shown are below.

[0082] It should be noted that in the formula, T represents the TEX of the weft yarn.

[0083] The weft yarn width variation coefficient A is determined using the following method. A CCD camera is used to scan the glass fiber bundle from one end of the glass cloth to the other along a direction orthogonal to the warp yarns (TD direction). Simultaneously, the weft yarn width is measured at a frequency of at least once every 0.5 mm along the TD direction. A cumulative yarn width distribution is created by arranging the weft yarn width data in descending order of width. This data is then...

[0084] W is defined as 5% of the accumulated wire width value starting from the side with the smaller wire width. 5％ : Cumulative 5% weft width (μm)

[0085] W is defined as 50% of the cumulative silk width value starting from the smaller side. 50％ : Cumulative 50% weft width (μm)

[0086] W is defined as 95% of the cumulative silk width value starting from the smaller side. 95％ Cumulative 95% weft width (μm)

[0087] To obtain. Use the obtained W 5％ W 50％ W 95％ The number of filaments of the weft and the length of the weft yarn: F, is calculated using the above formula (2) and is treated as the weft yarn width variation coefficient A.

[0088] As a method that sets the weft width variation coefficient A to a value below that shown in Equation (3), it is effective in adjusting the conditions of the glass fibers constituting the glass cloth, coating the glass fibers with sizing agent, the desizing process, and the fiber opening process in processes such as high-pressure water spray flow, oscillating washing machine, and high-frequency vibration with liquid as medium, in order to widen the warp fibers before the weft fibers, and to make the widening of the warp fibers sufficient and uniform.

[0089] In addition, methods that reduce the amount of sizing agent applied during glass fiber manufacturing and during the warping process by promoting warp widening are also effective. On the other hand, methods that reduce the amount of sizing agent applied during glass fiber manufacturing, promote the widening of glass filaments, and use glass filaments with mild bundle properties and relatively wide widths for warp are also effective.

[0090] In addition, in order to widen the warp yarns fully and evenly, methods to ensure uniform tension of the warp yarns and improve yarn quality such as twist count during the fabric manufacturing process are also effective.

[0091] In addition, reducing the tension of the yarn during the desizing and fiber opening processes is also an effective way to promote the widening of the warp yarns.

[0092] By combining these methods, the weft width variation coefficient A can be set to the value shown in equation (3) or below.

[0093] [Weft width variation coefficient α]

[0094] In this embodiment, the wire width variation coefficient α obtained by formula (5) is preferably a value obtained by formula (6) or below.

[0095] The coefficient of variation of the weft width is α = W / F…Equation (5)

[0096] {In the formula, W is the standard deviation of the weft width (μm), and F is the number of weft filaments.}

[0097] 0.5×e(-0.1×T)…Equation (6)

[0098] In the formula, T represents the TEX of the weft yarn.

[0099] The preferred range for the weft width variation coefficient α is the value shown in equation (9) below.

[0100] 0.51×e(-0.105×T)…Equation (9)

[0101] A further preferred range is below the value shown in formula (10).

[0102] 0.52×e(-0.110×T)…Equation (10)

[0103] The optimal range is below the value shown in equation (11).

[0104] 0.53×e(-0.115×T)…Equation (11)

[0105] It should be noted that in the formula, W is the standard deviation of the weft width (μm), and F is the number of weft filaments.

[0106] The weft width variation coefficient α is obtained using the following method. The standard deviation W is calculated using the weft width data obtained by the same measurement as that used to determine the weft width variation coefficient A. The value obtained by using the standard deviation W and the number of weft filaments F is calculated using the above formula (5) and treated as the weft width variation coefficient A.

[0107] If the weft width variation coefficient α is less than or equal to the value obtained using equation (6), then in a glass cloth densely filled with weft fibers (with a weft fiber content of 86% or more), the overall surface smoothness of the glass cloth can be easily suppressed. As a result, in the composite substrate of glass cloth and matrix resin, a sufficient resin layer thickness can be easily ensured while maintaining the overall resin content, thus exhibiting a tendency for enhanced adhesion to the metal foil, which is therefore preferable. Furthermore, the in-plane glass distribution and resin distribution tend to become more uniform, thus reducing the difference in signal propagation speed on the substrate, which is also preferable.

[0108] [Glass cloth]

[0109] (Brief Structure)

[0110] Glass fibers are obtained by bundling multiple long filaments and twisting them as needed. At this point, glass fibers are classified as multi-glass filaments, and the filaments (glass filaments) contained in the glass fiber are classified as single-glass filaments.

[0111] The elastic modulus of the glass fiber is preferably 50–70 GPa, more preferably 50–63 GPa, and even more preferably 53–63 GPa. If the elastic modulus is above 50 GPa, the glass fiber has high rigidity, thus preventing excessive widening of the fiber bundle during the fiber opening process of the glass cloth, and easily suppressing deformation of the undulating structure caused by uneven fiber width. If the elastic modulus is below 70 GPa, the glass fiber has appropriate softness, thus making it easier to appropriately control the fiber opening during the glass cloth fiber opening process, and thus easily suppressing deformation of the undulating structure caused by uneven fiber width.

[0112] The average diameter of the single glass filaments constituting the warp and weft is preferably 2.5–9 μm, more preferably 3.0–8 μm, and even more preferably 3.5–7.5 μm. The appropriate filament can be selected based on the desired thickness of the glass cloth.

[0113] The weft density of the warp and weft yarns constituting the glass cloth is preferably 30-120 yarns / 25mm, more preferably 40-110 yarns / 25mm, and even more preferably 50-100 yarns / 25mm.

[0114] The average diameter of the single glass filaments constituting the warp and weft is preferably 2.5–9 μm, more preferably 3.0–8 μm, and even more preferably 3.5–7.5 μm. The appropriate filament can be selected based on the desired thickness of the glass cloth.

[0115] The average number of single glass filaments constituting the warp and weft is preferably 20 to 250, more preferably 30 to 230, and even more preferably 33 to 220.

[0116] The thickness of the glass cloth is 5–100 μm, preferably 6–90 μm, and more preferably 7–80 μm. By ensuring the thickness of the glass cloth is within the above range, a thin glass cloth with relatively high strength is obtained.

[0117] The preferred weight of the glass cloth (weight per unit area) is 8–250 g / m². 2 More preferably 8-100g / m 2 Further optimization of 8-50 g / m 2 , with a preferred concentration of 8-35 g / m 2 .

[0118] The preferred range for the weight loss on ignition of the glass cloth is 0.25–1.5% by mass, more preferably 0.3–1.4% by mass, and even more preferably 0.35–1.3% by mass. The upper limit for the weight loss on ignition of the glass cloth can be 1.2% by mass, 1.0% by mass, or 0.9% by mass. When the weight loss on ignition of the glass cloth is above the lower limit mentioned above, sufficient reactivity with the matrix resin is easily obtained during substrate manufacturing, and the moisture absorption resistance is further improved. As a result, the insulation reliability is easily further improved, which is therefore preferred. In addition, when the weight loss on ignition of the glass cloth is below the upper limit mentioned above, the resin's impregnation of the glass cloth is easily further improved, which is also preferred. The weight loss on ignition can be determined according to the method described in JIS R 3420.

[0119] There are no particular limitations on the weaving structure of the glass cloth; examples include plain weave, mat weave, satin weave, and twill weave. Among these, a plain weave structure is preferred.

[0120] (Composition of glass cloth)

[0121] The composition of the glass cloth of this embodiment will be described below. It should be noted that the composition of the glass cloth is synonymous with the composition of the glass fibers constituting the glass cloth. As elements constituting the glass cloth, at least one can be selected from the group consisting of silicon (Si), boron (B), aluminum (Al), calcium (Ca), magnesium (Mg), phosphorus (P), sodium (Na), potassium (K), titanium (Ti), zinc (Zn), iron (Fe), and fluorine (F).

[0122] The silicon (Si) content of the glass filament, calculated as SiO2, is preferably 40-60% by mass, more preferably 45-55% by mass, even more preferably 47.0-53.5% by mass, and even more preferably 48.0-52.0% by mass. Si is the component that forms the skeletal structure of the glass filament. Therefore, with a Si content of 40% by mass or more, the strength of the glass filament is further improved, and in subsequent processes such as the manufacturing process of the glass cloth and the manufacturing process of the prepreg using the glass cloth, there is a tendency to further suppress the breakage of the glass cloth. In addition, with a Si content of 40% by mass or more, there is a tendency to further reduce the dielectric constant of the glass cloth. On the other hand, with a Si content of 60% by mass or less, the viscosity at melt time is further reduced during the manufacturing process of the glass filament, and there is a tendency to obtain glass fibers with a more uniform glass composition. Therefore, it is less likely that the obtained glass filament will have areas that are prone to partial devitrification or areas where it is difficult to remove bubbles, and thus it is less likely that the glass filament will have areas of localized weakness. As a result, glass cloth made from the glass filament obtained therefrom is less prone to breakage. The Si content can be adjusted according to the amount of raw materials used in the production of glass filaments.

[0123] The boron (B) content of the glass fiber, calculated based on B2O3, is preferably 15-40% by mass, more preferably 17-30% by mass, or 20-40% by mass, even more preferably 18-28% by mass, even more preferably 19-26% by mass, even more preferably 20-25% by mass, and most preferably 20.5-24.5% by mass.

[0124] With a boron content of 15% by mass or more, there is a tendency for the dielectric constant to decrease further. In addition, with a boron content of 15% by mass or more, the brittleness resistance of the glass cloth is improved. Furthermore, the glass cloth is given appropriate softness or gentleness, so when the glass fibers come into contact with weaving components such as guides and reeds, there is a tendency for fuzzing to occur.

[0125] On the other hand, in order to maintain the strength of the glass fiber, it is preferable that the boron content is 40% by mass or less. By having a boron content of 40% by mass or less, the moisture absorption resistance is improved, and it is easier to maintain the stability of the surface properties of the glass fiber described later.

[0126] In particular, when the Si content and the B content in the glass fiber are within the above-mentioned range, the effects related to Si and B can be easily exerted synergistically, and therefore it is preferred.

[0127] The B content can be adjusted by the amount of raw materials used in the production of glass filaments (feed amount). It should be noted that in the production of glass filaments, if the production conditions, amount, or content can be varied, the amount of raw materials fed can be estimated in advance to adjust the feed amount.

[0128] The aluminum (Al) content of the glass filament, calculated as Al2O3, is preferably 11–18% by mass, more preferably 11–17.5% by mass, and even more preferably 12–17.0% by mass. Within the above range, the electrical properties and strength tend to be further improved. The Al content can be adjusted by the amount of raw materials used in the production of the glass filament (feed amount).

[0129] The calcium (Ca) content of the glass filament, converted from CaO, is preferably 5.0 to 10% by mass, more preferably 5.0 to 9.0% by mass, and even more preferably 5.0 to 8.5% by mass. With a Ca content of 5.0% by mass or more, the viscosity at melt time is further reduced during the manufacturing process of the glass filament, tending to result in glass fibers with a more uniform glass composition. Furthermore, with a Ca content of 10% by mass or less, there is a tendency to further improve the dielectric constant. The Ca content can be adjusted by the amount of raw materials used in the production of the glass filament (feed amount).

[0130] The phosphorus (P) content of the glass filament, calculated as P2O5, is preferably 8.0% by mass or less, more preferably 7.0% by mass or less, and even more preferably 6.0% by mass or less. The P content can exceed 0% by mass. With a P content exceeding 0% by mass, the dielectric properties of the glass cloth tend to improve. Furthermore, with a P content of 8.0% by mass or less, the heat resistance of the glass cloth tends to improve. The P content can be adjusted by the amount of raw material used in the production of the glass filament (feed amount).

[0131] It should be noted that the above contents can be determined using ICP emission spectroscopy. Specifically, the Si and B contents can be obtained as follows: The weighed glass cloth is dissolved in sodium carbonate, then dissolved in dilute nitric acid to form a specified volume, and the resulting sample is measured using ICP emission spectroscopy to obtain the Si and B contents. Similarly, the Fe content can be obtained as follows: The weighed glass cloth is dissolved using an alkaline dissolution method to form a specified volume, and the resulting sample is measured using ICP emission spectroscopy to obtain the Fe content. Furthermore, the Al, Ca, P, and Mg contents can be obtained as follows: The weighed glass cloth is heated and decomposed using perchloric acid, sulfuric acid, nitric acid, and hydrofluoric acid, then dissolved in dilute nitric acid to form a specified volume, and the resulting sample is measured using ICP emission spectroscopy to obtain the Al, Ca, P, and Mg contents. It should be noted that the Hitachi High-Tech Corporation PS3520VDDII can be used as the ICP emission spectroscopy apparatus.

[0132] (Surface treatment)

[0133] Fiberglass cloth can be surface-treated using surface treatment agents. There are no particular limitations on surface treatment agents; examples include silane coupling agents, which can be combined with water, organic solvents, acids, dyes, pigments, surfactants, etc., as needed. There are no particular limitations on silane coupling agents; examples include compounds shown in formula (10).

[0134] X(R) 3-n SiY n (10)

[0135] (In the formula, X is an organic functional group having at least one of amino and unsaturated double bond groups, Y is each independently an alkoxy group, n is an integer of 1 to 3, and R is each independently a group selected from the group consisting of methyl, ethyl, and phenyl.)

[0136] X is preferably an organic functional group having at least three of the amino and unsaturated double bond groups, and X is more preferably an organic functional group having at least four of the amino and unsaturated double bond groups.

[0137] Any of the above-mentioned alkoxy groups can be used, but from the viewpoint of stabilizing the glass cloth, alkoxy groups with 5 or fewer carbon atoms are preferred.

[0138] As silane coupling agents, examples 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, and N-β-(N-di(vinylbenzyl)aminoethyl)-N-γ-(N-vinylbenzyl)-γ-aminopropyltrimethoxysilane. The known individual compounds or mixtures thereof, 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)aminopropyltriethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, methacryloyloxypropyltrimethoxysilane, acryloyloxypropyltrimethoxysilane, etc.

[0139] The molecular weight of the silane coupling agent is preferably 100–600, more preferably 150–500, and even more preferably 200–450. Preferably, two or more silane coupling agents with different molecular weights are used. By treating the surface of the glass fiber with two or more silane coupling agents with different molecular weights, the surface treatment agent density on the glass cloth surface increases, and there is a tendency for further improvement in reactivity with the matrix resin.

[0140] [Method for manufacturing glass cloth]

[0141] The manufacturing method of the glass cloth in this embodiment is not particularly limited, and examples include using glass fibers as warp and weft, weaving using conventional methods, and then treating the glass cloth fabric with a silane coupling agent for post-processing. The weaving structure of the glass cloth is not particularly limited, and examples include plain weave, twill weave, satin weave, and other weave structures. Furthermore, an interlaced structure using dissimilar glass fibers can also be used. A plain weave structure is preferred.

[0142] As one method of manufacturing the glass cloth according to this embodiment, a method having the following steps can be listed as an example:

[0143] In the covering process, a treatment solution with a concentration of 0.1 to 3.0% by mass of silane coupling agent is applied to the glass cloth, thereby using the silane coupling agent to roughly and completely cover the surface of the glass filament.

[0144] The fixing process involves heating and drying to fix the silane coupling agent onto the surface of the glass filament; and

[0145] The fiber-opening process involves opening the glass fibers in the glass cloth.

[0146] As a solvent for dissolving or dispersing the silane coupling agent, either water or an organic solvent can be used. From the perspective of safety and environmental protection, water is preferred as the main solvent. As a method for obtaining a treatment solution with water as the main solvent, the preferred method is either directly adding the silane coupling agent to water, or dissolving the silane coupling agent in a water-soluble organic solvent to form an organic solvent solution and then adding that organic solvent solution to water. Surfactants can also be used in combination to improve the water dispersibility and stability of the silane coupling agent in the treatment solution.

[0147] Methods for coating glass cloth with a silane coupling agent treatment solution include (i) immersing the glass cloth in a bath by storing the silane coupling agent treatment solution (hereinafter referred to as the "immersion method"); and (ii) directly coating the glass cloth with the silane coupling agent treatment solution using a roller coater, die coater, or gravure coater. When using the immersion method described above (i), it is preferable to immerse the glass cloth in the treatment solution for 0.5 seconds or more and 1 minute or less. Furthermore, known methods such as hot air and electromagnetic waves can be used to heat and dry the solvent after coating the glass cloth with the treatment solution.

[0148] The heating and drying temperature is preferably 90°C or higher, more preferably 100°C or higher, to ensure sufficient reaction between the silane coupling agent and the glass. Furthermore, to prevent the degradation of the organic functional groups in the silane coupling agent, the heating and drying temperature is preferably 300°C or lower, more preferably 200°C or lower.

[0149] There are no particular limitations on the fiber opening method used in the fiber opening process. Examples include using water spray (high-pressure water fiber opening), vibrating washing machine, ultrasonic water, and liquid rolling mill to open fiber cloth. In order to keep the total area of ​​the baskethole within a constant range, it is preferable to use water spray for the fiber opening process.

[0150] When using water spray for fiber opening, the water pressure can be set appropriately. To adjust the total area of ​​the square-shaped pores in the glass cloth, it is preferable to keep the water pressure constant. Here, keeping the water pressure constant means reducing the difference between the spray water pressure set for fiber opening and the actual maximum and minimum water pressure. Heating and drying processes can also be performed before or after the fiber opening process.

[0151] [Prepreg]

[0152] One embodiment of this invention uses a prepreg as a composite of the aforementioned glass cloth and matrix resin. The matrix resin is impregnated into the glass cloth.

[0153] Prepregs can be manufactured using conventional methods. For example, resin-impregnated prepregs can be produced by impregnating glass cloth with a varnish made by diluting a base resin with an organic solvent and then evaporating the organic solvent using a drying oven.

[0154] As the base resin, any type of thermosetting resin or thermoplastic resin can be used. As thermosetting resins, there are no particular limitations, but examples include: a) epoxy resins formed by reacting and curing compounds having epoxy groups and compounds having at least one of the following groups (amino, phenolic, anhydride, hydrazide, isocyanate, cyanate, and hydroxyl groups) that react with epoxy groups, either without a catalyst or with a catalyst having reaction catalytic ability such as imidazole, tertiary amine, urea, or phosphorus compounds; b) free radical polymerizable cured resins formed by using thermally decomposable or photodecomposable catalysts as reaction initiators to cure compounds having at least one of the following groups (vinyl, allyl, methacryloyl, and acryloyl); c) maleimide triazine resins formed by reacting and curing compounds having cyanate groups and compounds having maleimide groups; d) thermosetting polyimide resins formed by reacting and curing maleimide compounds and amine compounds; e) benzoxazine resins formed by crosslinking and curing compounds having benzoxazine rings through heating polymerization, etc.

[0155] Furthermore, as a thermoplastic resin, there are no particular limitations, and examples include polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, aromatic polyamide, polyetheretherketone, thermoplastic polyimide, insoluble polyimide, polyamide-imide, fluoropolymers, etc. Additionally, thermosetting resins and thermoplastic resins can be used in combination.

[0156] In one embodiment of this invention, the matrix resin in the prepreg composed of glass cloth and matrix resin is preferably a polyphenylene ether resin. More preferably, it is a polyphenylene ether resin with 1.5 to 5 carbon-carbon double bond functional groups, such as vinyl, allyl, methacryl, and acryloyl, at the end of the main chain per molecule. Furthermore, a polyphenylene ether with a number average molecular weight of 500 to 8000 is preferred. Since a polyphenylene ether resin is used as the matrix resin, it exhibits excellent dielectric properties and is therefore preferred.

[0157] Furthermore, since the matrix resin has the aforementioned functional groups and number-average molecular weight, the resin composition can easily penetrate into the interior of the glass cloth during the prepreg manufacturing process and the compression molding process, ensuring a large number of bonding points with the glass cloth. Therefore, it is presumed that the dielectric properties are excellent. Moreover, as in this embodiment, the glass has high in-plane uniformity and low air permeability. Therefore, even if the number of direct bonding points between the upper and lower resin matrix layers formed on the glass cloth is reduced, strong adhesion of the interface between the glass cloth and the resin composition is still exhibited, thereby improving heat resistance and insulation reliability.

[0158] Printed wiring board

[0159] Another aspect of this embodiment is a printed wiring board manufactured using the aforementioned prepreg, that is, a printed wiring board formed from the prepreg of this embodiment. By using the prepreg of this embodiment to manufacture the printed wiring board, a high-quality printed wiring board with reduced signal propagation speed differences among multiple transmission lines can be provided.

[0160] [Example]

[0161] The following describes in more detail the embodiments and comparative examples of the present invention. The present invention is not limited to the following embodiments.

[0162] [Physical properties of glass cloth and glass fiber]

[0163] Specifically, the physical properties of glass cloth, including its thickness, TEX of warp and weft yarns, diameter of the filaments constituting the warp and weft yarns, number of warp and weft filaments, fabric density of warp and weft yarns, and loss on ignition (LOI), are determined according to JIS R 3420.

[0164] (Average and standard deviation of warp width in glass cloth)

[0165] A scanning camera is used to obtain images of the warp threads across the entire width of the glass cloth, along a direction orthogonal to the warp threads (TD direction). The width of each warp thread is measured. The average and standard deviation of the warp thread widths across the entire width of the glass cloth are calculated.

[0166] (Average and standard deviation of the weft width in the glass cloth)

[0167] A scanning camera is used to obtain images of the weft fibers over a length range of 1300 mm along a direction orthogonal to the weft fibers of the glass cloth (MD direction), and the width of each weft fiber is measured. The average value and standard deviation of the weft fiber widths over the 1300 mm length range are then calculated.

[0168] (Cumulative width of weft yarns in glass cloth)

[0169] A CCD camera is used to scan the glass fiber bundle from one end of the glass cloth to the other along a direction orthogonal to the warp threads (TD direction). Simultaneously, the weft fiber width is measured at a frequency of at least once every 0.5 mm along the TD direction. A cumulative fiber width distribution is then created by arranging the weft fiber width data in descending order of width.

[0170] The yarn width value accumulated from the smaller side of the yarn width is taken as W. 5％ : Cumulative 5% weft width (μm)

[0171] The width of the yarn is accumulated by 50% from the side with the smaller yarn width as W. 50％ : Cumulative 50% weft width (μm)

[0172] The cumulative width value of 95% from the narrower side is taken as W. 95％ Cumulative 95% weft width (μm)

[0173] To obtain.

[0174] (Width of the glass fiber precursor)

[0175] While the glass fiber is being transported at a speed of 1 m / min, the width of the 50 m glass fiber is measured using a transmission-type dimension measuring instrument with LED projection (HIGH ACCURACY CMOS MICROMETER LS-9006MR / KEYENCE CORPORATION). The average width of the glass fiber is then calculated from the obtained fiber width data.

[0176] The wire width was measured using a transmission-type size measuring device with LED projection. The measurement was performed at a rate of 1934 points per 1m. In cases where errors occurred due to misalignment of the LED focus (represented by a value of -9999), the measured value was deleted to calculate the average wire width and / or the wire width distribution.

[0177] The tension acting on the glass fiber during transport is 0.12 to 0.18 N, measured using a tension meter (SCHMIDT Corporation Control Instruments ETPB-100-C0585).

[0178] (Elastic modulus of glass fiber)

[0179] The elastic modulus of glass fiber is determined by melting and cooling the glass fiber to obtain a glass block, which is then used as a test piece and measured using the pulse-echo re-evaluation method.

[0180] [Copper foil peel strength (N / mm)]

[0181] (The preparation of resin varnish)

[0182] A resin varnish was obtained by mixing 38.6 parts by weight of polyphenylene ether resin (SA9000, manufactured by SABIC), 9.7 parts by weight of triallyl isocyanurate (TAIC, manufactured by Nippon Kasei Corporation), 0.22 parts by weight of bis(1-tert-butylperoxy-1-methylethyl)benzene (PERBUTYL P, manufactured by Nippon Yushu Co., Ltd.), 13.6 parts by weight of aluminum tris(diethylphosphino)acid (OP945, manufactured by Clariant Japan K.K.), 0.5 parts by weight of benzoguanamine (manufactured by Tokyo Kasei Corporation), 33 parts by weight of hydrogenated styrene-based thermoplastic resin (Tuftec N525, manufactured by Asahi Kasei Corporation), and 4.3 parts by weight of spherical silica (manufactured by Ryusen Co., Ltd.) in 200 parts by weight of toluene.

[0183] (Preparation of prepreg)

[0184] After impregnating the glass cloth obtained in the examples and comparative examples with the above-mentioned resin varnish, excess varnish was scraped off through a specified slit. The prepreg was then dried in a drying oven at 105°C for a specified time to remove toluene, thereby obtaining a prepreg. The prepreg was cut to a specified size, and its weight was compared with the weight of glass cloth of the same size. The solid content of the resin composition in the prepreg was calculated. The results showed that Examples 1-4 and Comparative Example 1 had a solid content of 66%, Examples 5 and 6 and Comparative Example 2 had a solid content of 72%, Examples 7 and 8 and Comparative Example 3 had a solid content of 58%, and Examples 9 and 10 and Comparative Example 4 had a solid content of 56%.

[0185] (Fabrication of double-sided copper-clad laminates)

[0186] Two sheets of the obtained prepreg were overlapped, and then 18 μm thick copper foil (FZ-WS, Rz1.1, manufactured by Furukawa Electric Industries Co., Ltd.) was overlapped on top and bottom. The overlapped material was then subjected to a temperature of 200°C and a pressure of 40 kg / cm². 2 Under certain conditions, a double-sided copper-clad laminate is produced by vacuum pressing for 60 minutes.

[0187] (Determination and evaluation of copper foil peel strength)

[0188] The obtained copper-clad laminate was cut into dimensions of 10 mm wide and 100 mm long to serve as test pieces for copper foil peel strength testing. Using a universal testing machine (Autograph) (AG-5000D, manufactured by Shimadzu Corporation), the average load was measured when the copper foil was peeled from the removal surface at a 90° angle and a speed of 50 mm / min. The average value of five measurements was calculated, and the following benchmarks were used for evaluation.

[0189] E(◎): 0.9 N / mm or higher

[0190] G(〇): ≥0.8 N / mm and <0.9 N / mm

[0191] A(△): Above 0.7 N / mm and less than 0.8 N / mm

[0192] P(×): less than 0.7 N / mm

[0193] <Comparative Example 1>

[0194] Both warp and weft yarns use AGY's low-dielectric glass fiber LCD510 (elastic modulus 61 GPa, TEX 9.73), woven on an air-jet loom with a warp and weft yarn density of 52.5 ends / 25 mm and a weft yarn density of 52.5 ends / 25 mm (grey fabric). For the warp yarns, spools with an LOI of 1.4–1.5 and an average yarn width in the range of 145–155 μm are selected. After applying a sizing agent to achieve an LOI of 3.0–3.1 during the warping process, the yarn is then used for weaving. For the weft yarns, spools with an LOI of 1.4–1.5 and an average yarn width in the range of 145–155 μm are also selected.

[0195] The obtained fabric was subjected to sizing and washing, followed by fiber opening treatment using high-pressure water spray. After desizing by heat treatment at 400°C for 24 hours, the glass cloth was impregnated in a treatment solution using a silane coupling agent as a surface treatment agent, squeezed out, and dried at 120°C for 1 minute. Then, fiber opening processing using high-pressure water spray was performed to obtain glass cloth with a thickness of 48 μm and a width of 1300 mm. The average fiber width of the glass cloth was adjusted through dehydration and washing, fiber opening treatment, and fiber opening treatment following silane coupling agent treatment.

[0196] <Example 1>

[0197] In the warping process, a sizing agent was applied with an LOI of 2.5 to 2.6. Glass fibers with an LOI of 1.6 to 1.7 and an average fiber width of 140 to 145 μm were used for the weft. Based on Comparative Example 1, the linear tension in the sizing washing of the fabric and the fiber opening treatment using high-pressure water spray was adjusted to 0.8 times. Otherwise, the glass cloth was manufactured using the same method as Comparative Example 1, and a glass cloth with a thickness of 46 μm and a width of 1300 mm was obtained.

[0198] <Example 2>

[0199] The weft yarn is made of glass fiber with an LOI of 1.7 to 1.8 and an average width of 135 to 140 μm. Otherwise, the glass cloth is manufactured using the same method as in Example 1 to obtain a glass cloth with a thickness of 45 μm and a width of 1300 mm.

[0200] <Example 3>

[0201] The warp yarns are glass fibers with an LOI of 1.1 to 1.2 and an average width of 155 to 160 μm. In the warping process, a sizing agent is applied with an LOI of 2.1 to 2.2. Otherwise, the glass cloth is manufactured using the same method as in Example 2, resulting in a glass cloth with a thickness of 44 μm and a width of 1300 mm.

[0202] <Example 4>

[0203] The weft yarn used was glass fiber with an LOI of 1.8 to 1.9 and an average width of 130 to 135 μm. Based on Comparative Example 1, the linear tension in the sizing and washing of the fabric and the fiber opening process using high-pressure water spray was adjusted to 0.6 times. Otherwise, the glass cloth was manufactured using the same method as in Example 3, and a glass cloth with a thickness of 43 μm and a width of 1300 mm was obtained.

[0204] <Comparative Example 2>

[0205] Both the warp and weft yarns use LCD1020 low-dielectric glass fiber (elastic modulus 61GPa, TEX 4.86) manufactured by AGY Company. The glass cloth (grey fabric) is woven using an air-jet loom with a warp yarn bend density of 69 threads / 25mm and a weft yarn bend density of 69 threads / 25mm.

[0206] The obtained fabric was subjected to sizing and washing, followed by fiber opening treatment using high-pressure water spray. After desizing by heat treatment at 400°C for 24 hours, the glass cloth was impregnated in a treatment solution using a silane coupling agent as a surface treatment agent, squeezed out, and dried at 120°C for 1 minute. Finally, fiber opening processing using high-pressure water spray was performed to obtain a glass cloth with a thickness of 31 μm and a width of 1300 mm.

[0207] The warp yarns are made of glass fibers with an LOI of 1.8–1.9 and an average width of 110–120 μm. During the warping process, a sizing agent is applied to achieve an LOI of 3.4–3.5 before weaving. The weft yarns are also made of glass fibers with an LOI of 1.8–1.9 and an average width of 110–120 μm.

[0208] <Example 5>

[0209] The warp yarns are glass fibers with an LOI of 1.5 to 1.6 and an average width of 120 to 130 μm. In the warping process, a sizing agent is applied with an LOI of 2.4 to 2.5. The weft yarns are glass fibers with an LOI of 2.0 to 2.1 and an average width of 105 to 110 μm. Based on Comparative Example 1, the linear tension in the sizing washing of the fabric and the fiber opening treatment using high-pressure water spray is adjusted to 0.8 times. Otherwise, the glass cloth is manufactured using the same method as Comparative Example 2, and a glass cloth with a thickness of 29 μm and a width of 1300 mm is obtained.

[0210] <Example 6>

[0211] The weft yarn used was glass fiber with an LOI of 2.2 to 2.3 and an average width of 100 to 105 μm. Based on Comparative Example 1, the linear tension in the sizing and washing of the fabric and the fiber opening process using high-pressure water spray was adjusted to 0.6 times. Otherwise, the glass cloth was manufactured using the same method as in Example 5, and a glass cloth with a thickness of 29 μm and a width of 1300 mm was obtained.

[0212] <Comparative Example 3>

[0213] Both the warp and weft yarns use LCDE340 low-dielectric glass fiber (elastic modulus 61GPa, TEX 14.59) manufactured by AGY Company. The glass cloth (grey fabric) is woven using an air-jet loom with a warp yarn bedding density of 59.0 ends / 25mm and a weft yarn bedding density of 61.0 ends / 25mm.

[0214] The obtained fabric was subjected to sizing and washing, followed by fiber opening treatment using high-pressure water spray. After desizing by heat treatment at 400°C for 24 hours, the glass cloth was impregnated in a treatment solution using a silane coupling agent as a surface treatment agent, squeezed out, and dried at 120°C for 1 minute. Finally, fiber opening processing using high-pressure water spray was performed to obtain a glass cloth with a thickness of 76 μm and a width of 1300 mm.

[0215] The warp yarns are made of glass fibers with an LOI of 1.5–1.6 and an average width of 170–180 μm. During the warping process, a sizing agent is applied to achieve an LOI of 2.9–3.0 before weaving. The weft yarns are also made of glass fibers with an LOI of 1.5–1.6 and an average width of 170–180 μm.

[0216] <Example 7>

[0217] The warp yarns are glass fibers with an LOI of 1.1 to 1.2 and an average width of 180 to 190 μm. In the warping process, a sizing agent is applied with an LOI of 2.0 to 2.1. The weft yarns are glass fibers with an LOI of 1.7 to 1.8 and an average width of 165 to 170 μm. Based on Comparative Example 1, the linear tension in the sizing washing of the fabric and the fiber opening treatment using high-pressure water spray is adjusted to 0.8 times. Otherwise, the glass cloth is manufactured using the same method as Comparative Example 3, resulting in a glass cloth with a thickness of 73 μm and a width of 1300 mm.

[0218] <Example 8>

[0219] The weft yarn used was glass fiber with an LOI of 1.9 to 2.0 and an average fiber width of 160 to 165 μm. Based on Comparative Example 1, the linear tension in the sizing and washing of the fabric and the fiber opening process using high-pressure water spray was adjusted to 0.6 times. Otherwise, the glass cloth was manufactured using the same method as in Example 7, and a glass cloth with a thickness of 70 μm and a width of 1300 mm was obtained.

[0220] <Comparative Example 4>

[0221] Both the warp and weft yarns are made of low dielectric glass fiber LCE255 (elastic modulus 61GPa, TEX 19.45) manufactured by AGY Company. The glass cloth (grey fabric) is woven on an air-jet loom with a warp yarn bedding density of 60.0 ends / 25mm and a weft yarn bedding density of 57.0 ends / 25mm.

[0222] The obtained fabric was subjected to sizing and washing, followed by fiber opening treatment using high-pressure water spray. After desizing by heat treatment at 400°C for 24 hours, the glass cloth was impregnated in a treatment solution using a silane coupling agent as a surface treatment agent, squeezed out, and dried at 120°C for 1 minute. Finally, fiber opening processing using high-pressure water spray was performed to obtain a glass cloth with a thickness of 91 μm and a width of 1300 mm.

[0223] The warp yarns are made of glass fibers with an LOI of 1.4–1.5 and an average width of 180–190 μm. During the warping process, a sizing agent is applied to achieve an LOI of 3.0–3.1 before weaving. The weft yarns are also made of glass fibers with an LOI of 1.4–1.5 and an average width of 180–190 μm.

[0224] <Example 9>

[0225] The warp yarns are glass fibers with an LOI of 1.1 to 1.2 and an average width of 200 to 210 μm. In the warping process, a sizing agent is applied with an LOI of 2.0 to 2.1. The weft yarns are glass fibers with an LOI of 1.6 to 1.7 and an average width of 175 to 180 μm. Based on Comparative Example 1, the linear tension in the sizing washing of the fabric and the fiber opening treatment using high-pressure water spray is adjusted to 0.8 times. Otherwise, the glass cloth is manufactured using the same method as Comparative Example 4, resulting in a glass cloth with a thickness of 87 μm and a width of 1300 mm.

[0226] <Example 10>

[0227] The weft yarn used was glass fiber with an LOI of 1.8 to 1.9 and an average fiber width of 170 to 175 μm. Based on Comparative Example 1, the linear tension in the sizing and washing of the fabric and the fiber opening process using high-pressure water spray was adjusted to 0.6 times. Otherwise, the glass cloth was manufactured using the same method as in Example 9, and a glass cloth with a thickness of 84 μm and a width of 1300 mm was obtained.

[0228] The results are shown in the table below.

[0229] [Table 1]

[0230]

[0231] [Table 2]

[0232]

Claims

1. A type of glass cloth, comprising glass fibers containing multiple glass filaments woven together as warp and weft fibers, with a thickness of 5-100 μm. The weft yarn percentage (%), which represents the proportion of the portion containing weft yarns in the MD direction, calculated using the following formula (1), is 86.0%~107.0%. Weft yarn occupancy rate = W / (25000 / G)×100%···Equation (1) In the formula, W is the average width of the weft yarn, G is the fabric density of the weft yarn, W is in μm, and G is in yarns / 25mm. The wire width variation coefficient A obtained using formula (2) is the same as the value obtained using formula (3). The coefficient of variation of the weft width is A = (W 95% -W 5% ) / W 50% / F···Form (2) In the formula, W 95% To determine the cumulative 95% weft width in the cumulative weft width distribution measured along the weft direction from one end to the opposite end, using the smaller side as the starting point, W 5% To accumulate 5% weft width, W 50% To accumulate 50% weft width, W 95% W 5% W 50% The unit is μm, and F is the number of weft filaments, with F measured in filaments. 0.0056×e (-0.160×T) ...Formula (3) In the formula, T represents the TEX of the weft yarn.

2. The glass cloth according to claim 1, wherein, The weft yarn occupancy rate (%) is 90.0~104.5%.

3. The glass cloth according to claim 1, wherein, The wire width variation coefficient A obtained using equation (2) is below the value obtained using equation (8). 0.0056×e (-0.175×T) ...Formula (8) In the formula, T represents the TEX of the weft yarn.

4. The glass cloth according to claim 1, wherein, The thickness of the glass cloth is 7~80μm.

5. The glass cloth according to claim 1, wherein, The weight loss on ignition of the glass cloth is 0.25~1.5% by mass.

6. The glass cloth according to claim 1, wherein, The sum of the following warp occupancy rate (%), which represents the proportion of warp yarns in the TD direction, obtained using formula (4), and the weft occupancy rate, is 150-200%. Warp yarn occupancy rate = X / (25000 / H)×100%···Equation (4) In the formula, X is the width of the warp yarn, H is the fabric density of the warp yarn, the unit of X is μm, and the unit of H is yarns / 25mm.

7. The glass cloth according to claim 6, wherein, The sum of the warp yarn percentage (%) and the weft yarn percentage is 153-195%.

8. The glass cloth according to claim 6, wherein, The warp yarn percentage is above 60% and below 98%.

9. The glass cloth according to claim 1, wherein, The wire width variation coefficient α obtained using formula (5) is the same as the value obtained using formula (6). The coefficient of variation of the weft width is α = W / F···Equation (5) In the formula, W is the standard deviation of the weft width, and F is the number of weft filaments. The unit of W is μm, and the unit of F is filaments. 0.5×e (-0.1×T) ...Formula (6) In the formula, T represents the TEX of the weft yarn.

10. The glass cloth according to claim 9, wherein, The wire width variation coefficient α obtained using equation (5) is below the value obtained using equation (11). 0.53×e (-0.115×T) ...Formula (11) In the formula, T represents the TEX of the weft yarn.

11. The glass cloth according to claim 1, wherein, The elastic modulus of the glass fiber is 50~70 GPa.

12. The glass cloth according to claim 1, wherein, The elastic modulus of the glass fiber is 50~63 GPa.

13. The glass cloth according to claim 1, wherein, The elastic modulus of the glass fiber is 53~63 GPa.

14. A prepreg comprising glass cloth and thermosetting resin as described in any one of claims 1 to 13.

15. A printed wiring board comprising the prepreg of claim 14.

Images