Glass cloth, prepreg, and printed circuit board

Abstract

Provided is a low-dielectric glass cloth that is less slack and has uniform characteristics of thickness, air permeability, and resin impregnation, and a prepreg and a printed circuit board obtained using the glass cloth. A glass cloth that is composed of a glass yarn formed of a plurality of glass filaments as warp and weft, the thickness of the glass cloth being 5 μm to 100 μm, the length in the width direction of the aforementioned glass cloth being 1000 mm or more, and the difference X between the width of the warp at the width direction end portion and the width of the warp at the width direction central portion of the aforementioned glass cloth being α or less, where α is the standard deviation of the width of the warp.

Description

Technical Field

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

[0002] With the development of the information and communication society in recent years, data communication and / or signal processing are increasingly characterized by high capacity and high speed. For example, the use of low-dielectric printed circuit boards (PCBs) in communication equipment or measuring instruments such as high-end servers, routers / switches, supercomputers, and base stations is being significantly promoted. Therefore, various low-dielectric glass cloths have also been proposed for the glass cloths that make up PCBs.

[0003] For example, the low dielectric glass cloth disclosed in Patent Document 1 achieves a low dielectric constant by mixing a large amount of boron oxide (B2O3) into the glass composition of conventionally used E glass cloth, while adjusting the mixing amount of other components such as silicon dioxide (SiO2).

[0004] As a method to improve the performance and quality of low dielectric glass cloth in the width direction deviation, Patent Document 2 discloses a glass cloth in which the end slack of low dielectric glass cloth is improved, and Patent Document 3 discloses a glass cloth in which the substrate warping is improved.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 2010-508226

[0008] Patent Document 2: International Publication No. 2021 / 124913

[0009] Patent Document 3: Japanese Patent Application Publication No. 2017-132651 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] During their research, the inventors discovered that the low-dielectric glass cloth made using this low-dielectric glass yarn has significantly different performance and quality compared to the E-glass cloth used previously.

[0012] The low-dielectric glass cloth exhibits a greater tendency to loosen compared to conventional E-glass cloth. This loosening is particularly noticeable at the ends and center of the width direction. This is presumably due to the low-dielectric glass cloth's low elastic modulus and soft texture. Furthermore, the inventors conducted detailed observations of the low-dielectric glass cloth and determined that there is a tendency for uneven thickness distribution along the width direction, with the thickness at the ends being approximately 10% greater than that at the center. This further revealed that properties such as air permeability and resin impregnation also differ along the width direction, especially at the ends. This deviation in the performance and quality of the glass cloth affects the characteristics and quality of prepregs and laminates for printed circuit boards obtained using it (resin content, heat resistance, copper foil peel strength, dimensional stability, etc.).

[0013] Regarding the glass cloth disclosed in Patent Document 2, it is disclosed that the end slack of the glass cloth is improved by suppressing the difference in slope between the end and the center of the stress-strain curve in the width direction parallel to the warp yarns to less than 10%. However, there is still room for improvement in the slack of low-dielectric glass cloths disclosed in Patent Document 2.

[0014] Regarding the glass cloth disclosed in Patent Document 3, a low-dielectric glass cloth is disclosed that improves substrate warping by suppressing the difference in the width direction of the elongation of the stress-strain curve in the warp direction to less than 10%. However, substrate warping is also significantly related to the elongation in the weft direction. Generally, glass cloth has the characteristic that the weft yarn elongates more significantly than the warp yarn. Therefore, controlling only the elongation of the warp yarn cannot improve substrate warping, and there is still room for improvement in terms of the relaxation of the glass cloth.

[0015] The present invention was made in view of the above-mentioned problems, and its object is to provide a low dielectric glass cloth with low slack and uniform thickness, air permeability and resin impregnation properties, and to obtain prepregs and printed circuit boards using the glass cloth.

[0016] Solution for solving the problem

[0017] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that by setting the difference between the warp width at the end and the center of the glass cloth and the deviation of the warp width relative to the warp width to a specified range, the above-mentioned problems can be solved, and thus the present invention was completed.

[0018] That is, the present invention is as follows.

[0019] [Item 1]

[0020] A type of glass cloth is constructed by using glass yarn, formed from multiple long glass filaments, as both warp and weft yarns. The thickness of the glass cloth is 5μm to 100μm.

[0021] The aforementioned glass cloth has a width of 1000mm or more, and

[0022] The difference X between the warp width at the end of the width direction and the center of the width direction of the aforementioned glass cloth is less than or equal to the standard deviation α of the warp width.

[0023] [Item 2]

[0024] According to the glass cloth described in item 1, the aforementioned difference in warp width X is less than 0.7 times the standard deviation α of the warp width.

[0025] [Item 3]

[0026] According to the glass cloth described in item 1 or 2, the aforementioned difference in warp width X is less than 0.5 times the standard deviation α of the warp width.

[0027] [Item 4]

[0028] The glass cloth according to any one of items 1 to 3, wherein the standard deviation α of the aforementioned warp width is less than 0.08 times the average value β of the warp width.

[0029] [Item 5]

[0030] The glass cloth according to any one of items 1 to 4, wherein the standard deviation α of the aforementioned warp width is less than 0.04 times the average value β of the warp width.

[0031] [Item 6]

[0032] The glass cloth according to any one of items 1 to 5, wherein the standard deviation α of the aforementioned warp width is less than 0.03 times the average value β of the warp width.

[0033] [Item 7]

[0034] The glass cloth according to any one of items 1 to 6, wherein the TEX of the aforementioned glass yarn is 1.0 or more and 25 or less.

[0035] [Item 8]

[0036] The glass cloth according to any one of items 1 to 7 is composed of glass yarn with an elastic modulus of 50 GPa or more and 70 GPa or less.

[0037] [Item 9]

[0038] The glass cloth according to any one of items 1 to 8 is composed of glass yarn with an elastic modulus of 50 GPa or more and 63 GPa or less.

[0039] [Item 10]

[0040] The glass cloth according to any one of items 1 to 9, wherein the sum of the boron content and the phosphorus content in the aforementioned glass cloth is 5% by mass or more and 20% by mass or less.

[0041] [Item 11]

[0042] The glass cloth according to any one of items 1 to 10, wherein the sum of the boron content and the phosphorus content in the aforementioned glass cloth is 6.5% by mass or more and 20% by mass or less.

[0043] [Item 12]

[0044] A prepreg comprising the glass cloth described in any one of claims 1 to 11, and a base resin composition impregnated in the aforementioned glass cloth.

[0045] [Item 13]

[0046] A printed circuit board comprising a glass cloth as described in any one of claims 1 to 11, and a cured product of a base resin composition impregnated in the aforementioned glass cloth.

[0047] The effects of the invention

[0048] According to the present invention, a low-dielectric glass cloth with minimal slack and uniform properties such as thickness, air permeability, and resin impregnation can be provided. Detailed Implementation

[0049] Hereinafter, embodiments of the present invention (hereinafter referred to as "this embodiment") will be described in detail, but the present invention is not limited thereto, and various modifications can be made without departing from its spirit.

[0050] [Glass cloth]

[0051] The glass cloth of this embodiment is composed of glass yarn formed by multiple glass filaments as warp and weft yarns. The thickness of the glass cloth is 5μm to 100μm, the length of the glass cloth in the width direction is 1000mm or more, and the difference between the warp width at the end in the width direction and the warp width at the center in the width direction is less than or equal to the standard deviation of the warp width.

[0052] Here, "end in the width direction" refers to the area from 100mm to 250mm from the very end of the glass cloth with a width length of 1000mm or more. "Central part in the width direction" refers to the area from the center of the glass cloth with a width length of 1000mm or more, extending 75mm towards both ends.

[0053] The difference between the warp width at the end of the width direction and the warp width at the center of the width direction, as well as the standard deviation of the warp width, are measured as described in the examples below.

[0054] Compared to E-glass cloth, low-dielectric glass cloth is more prone to loosening at both ends and the center in the width direction. Furthermore, there is a tendency for the thickness to increase by approximately 10% near the ends in the width direction. Moreover, properties such as air permeability and resin impregnation tend to differ in the width direction, especially at the ends. To address these problems with low-dielectric glass cloth, the inventors first investigated the causes of these problems and found that the fabric structure of the glass cloth at both ends in the width direction is significantly different from that in the center.

[0055] That is, in the case of glass cloth with a width length of 1000 mm or more, the warp yarns, from 100 mm from the outermost part of the width direction towards the center to a range of 150 mm (the area from 100 mm from the outermost part to 250 mm from the outermost part of the width direction), are arranged horizontally in a roughly straight line with almost no undulation. On the other hand, in the range from the outermost part towards the center to 100 mm and in the center, the warp yarns are alternately arranged vertically relative to the horizontal, exhibiting a undulating structure. It has been clarified that, due to this fabric structure, when the glass cloth is transported horizontally, in the range from the outermost part towards the center to about 100 mm and in the center, the warp yarns stretch due to gravity, causing the glass cloth to sag downwards (while in the range from 100 mm from the outermost part towards the center to 150 mm, the warp yarns are taut and therefore do not sag due to gravity). In other words, it has been clarified that the slack of the low-dielectric glass cloth is due to the uneven fabric structure in the width direction. Furthermore, it was found that by modifying the strain in the width direction of the aforementioned fabric structure, the relaxation of the low-dielectric glass cloth could be improved.

[0056] It was also clarified that from approximately 100 mm from the outermost edge towards the center to 150 mm, the thickness increased due to the significant fluctuations in the weft yarns caused by the warp yarns arranged in a roughly horizontal row. Similarly, it was found that by modifying the strain in the width direction of the fabric structure, the thickness of the low-dielectric glass cloth could be made uniform in the width direction. Furthermore, it was found that differences in air permeability, resin impregnation, and the elongation and slope of the warp yarns in the stress-strain curve in the width direction could also be improved by modifying the strain in the width direction of the fabric structure.

[0057] Furthermore, because the warp and weft yarns are densely packed, the thickness of the glass cloth can also be reduced.

[0058] As described above, in this embodiment of the glass cloth, the difference X between the warp width at the ends and the center in the width direction is less than or equal to the standard deviation α of the warp width. More preferably, the difference X is less than or equal to 0.7 times the standard deviation α of the warp width, and even more preferably, it is less than or equal to 0.5 times the standard deviation α of the warp width. If the difference X between the warp width at the ends and the center in the width direction is less than or equal to the standard deviation α of the warp width, the fabric structure becomes uniform in the width direction, and the differences in the width direction of the glass cloth's slack, thickness, resin impregnation, and air permeability are reduced to a smaller extent.

[0059] It is preferable for the difference X between the warp width at the ends and the center of the width direction to be small, and ideally, the warp width should be substantially the same. Even if the warp width at the ends of the width direction is greater than that at the center of the width direction, as long as it is less than 0.3 times the standard deviation of the warp width, the differences in the width direction of the glass cloth's looseness, thickness, resin impregnation, and air permeability can be improved. Therefore, the lower limit of the difference X between the warp width at the ends and the center of the width direction is preferably -0.3α (0.3 times the negative standard deviation).

[0060] The inventors have discovered that, according to the following mechanism, the strain of the fabric structure occurs during the flattening and fiber opening processes, as the filaments of the glass yarn bundle loosen and the yarn bundle expands, while the fabric structure is being re-formed.

[0061] Flattening and fiber opening processes are performed using high-pressure water spraying, vibration-based cleaning, or high-frequency vibration using liquid as a medium. These processes occur while tension is applied to the warp direction of the glass cloth and it is transported horizontally. During this process, the glass cloth experiences a downward force due to its own weight. Furthermore, since these processes utilize water, the weight of the water-containing glass cloth increases, thus amplifying the downward force. In this operation, the glass cloth is subjected to a combined force based on the support of the transport rollers, the warp tension, and the downward force due to its own weight. As a result, the warp tension is strongly applied locally from 100mm to 300mm from the end. Consequently, warp expansion does not occur from 100mm to 300mm from the end, and the warp remains taut. On the other hand, warp expansion occurs in the inner 100mm area from the end and in the central area, creating warp undulation during the fabric structure formation process. It can be seen that this results in strain in the width direction of the fabric structure.

[0062] Based on the understanding of the mechanism of strain in the width direction that forms the fabric structure, during the fiber opening treatment of glass cloth (grey cloth) based on sizing and high-pressure water spray, and the fiber opening treatment based on high-pressure water spray after silane coupling agent treatment, the width direction distribution of the pressure of the high-pressure water spray, the processing force of the sizing and high-pressure water, and the tension acting on the MD are adjusted as follows, so that the warp yarn expansion in the range from 100 mm from the end of the width direction to 300 mm from the end is the same as in other ranges.

[0063] • In the warping / weaving stage, the warp tension is set such that the tension of the warp yarns in the range from 100mm from the end to 300mm from the end is less than that in other ranges. The fabric is then made and flattened and splitted.

[0064] • A method to reduce the machining force in the range of 100mm from the end and the central part, and to increase the machining force in the range from 100mm from the end to 300mm from the end;

[0065] • Reduce tension during flattening and fiber opening processes, and decrease the tension difference between the warp yarns acting on the area from 100mm from the end to 300mm from the end during flattening / fiber opening processes and other areas.

[0066] • Methods to reduce the processing forces during flattening and fiber opening processes, thereby minimizing changes in the cross-sectional structure of the yarn bundle and the fabric structure.

[0067] Findings: By using them individually or in combination as appropriate, the deformation in the width direction of the fabric structure can be improved.

[0068] In this embodiment, the standard deviation α of the warp width of the glass cloth is preferably less than 0.08 times the average value β of the warp width.

[0069] If the standard deviation α of the warp width is less than 0.08 times the average value β of the warp width, the fabric structure is more likely to be uniform in the width direction, and the differences in the width direction of the glass cloth's slack, thickness, resin impregnation, and air permeability between the ends and the center are improved to a smaller extent.

[0070] The standard deviation α of the warp width is preferably less than 0.04 times the average value β of the warp width, and more preferably less than 0.03 times the average value β of the warp width.

[0071] The average warp width was measured as described in the examples described later.

[0072] When the standard deviation of the warp width is small, the fabric structure is more likely to become uniform in the width direction, which is therefore preferred. There is no particular limitation, but it is preferred to be 0 or above.

[0073] To set the standard deviation of the warp width within the aforementioned range, effective methods include: using raw yarn with small deviations in twist, filament diameter, TEX, etc., of the glass yarn used in the warp; ensuring that the tension and processing force in the warping and opening processes are nearly uniform in the width direction; and reducing variations in tension and processing force. Additionally, as mentioned above, methods to reduce the difference in yarn width between the ends and the center in the width direction are also effective.

[0074] The thickness of the glass cloth in this embodiment is 5 μm or more and 100 μm or less. If the thickness of the glass cloth in this embodiment is 100 μm or less, high density and high multilayering of the printed circuit board can be achieved. From the viewpoint of achieving thinner and higher density printed circuit boards, the aforementioned thinner thickness is preferred; from the viewpoint of maintaining practical strength, the lower limit of the thickness is 5 μm. The thickness of the glass cloth in this embodiment is preferably 6 μm or more, more preferably 8 μm or more. Furthermore, the thickness of the glass cloth in this embodiment is preferably 98 μm or less, more preferably 96 μm or less.

[0075] The thickness of the glass cloth in this embodiment can be measured using the method described in the examples.

[0076] The elastic modulus of the glass yarn constituting the glass cloth of this embodiment is preferably 50 GPa or more, more preferably 51 GPa or more, and even more preferably 52 GPa or more.

[0077] If the elastic modulus is above 50 GPa, the following tendencies exist: the rigidity of the glass yarn increases, it is easier to control the flattening process and the structural changes during fiber opening during glass cloth processing, and it is easier to make a fabric structure with uniform width.

[0078] On the other hand, the elastic modulus of the glass yarn is preferably 70 GPa or less, more preferably 65 GPa or less, and even more preferably 63 GPa or less. If the elastic modulus is 70 GPa or less, the glass yarn has moderate softness. Therefore, during the warping / weaving, flattening, and fiber opening processes in glass cloth processing, the fabric structure is easily altered by tension and processing forces. Thus, there is a tendency to easily produce a fabric structure with a uniform width direction. Furthermore, when the elastic modulus is 70 GPa or less, since both the glass yarn and glass cloth are soft, conventional glass cloth tends to experience strain in the fabric structure in the width direction. This embodiment is advantageous in producing a fabric structure with a uniform width direction.

[0079] The elastic modulus of the glass yarn can be determined using the method described in the examples.

[0080] The dielectric constant of the glass cloth in this embodiment is preferably 5.0 or less at a frequency of 1 GHz, more preferably 4.7 or less, even more preferably 4.5 or less, and particularly preferably 4.0 or less. It should be noted that, in this embodiment, the term "dielectric constant" refers to the value at a frequency of 1 GHz unless otherwise specified.

[0081] The weaving structure of the glass cloth in this embodiment is not particularly limited, and examples include plain weave, square weave, satin weave, and twill weave. Among these, a plain weave structure is more preferred.

[0082] The glass yarn constituting the glass cloth of this embodiment is obtained by bundling multiple filaments together and twisting them as needed. In this case, the glass yarn is classified as glass multifilament, and the filaments (glass filaments) contained in the glass yarn are classified as glass monofilament.

[0083] The drive density of the warp and weft yarns of the glass cloth constituting this embodiment is preferably 30 to 120 yarns / 25 mm, more preferably 40 to 110 yarns / 25 mm, and even more preferably 50 to 100 yarns / 25 mm.

[0084] The average diameter of the glass filaments constituting the warp and weft yarns 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 and used depending on the thickness of the target glass cloth.

[0085] The average number of glass filaments constituting the warp and weft yarns is preferably 20 to 250, more preferably 30 to 230, and even more preferably 33 to 220.

[0086] The preferred range for the thermal weight loss of the glass cloth in this embodiment is 0.25% to 1.5% by mass, more preferably 0.3% to 1.4% by mass, and even more preferably 0.35% to 1.3% by mass.

[0087] The composition of the glass cloth according to this embodiment will be described below. It should be noted that the composition of the glass cloth has the same meaning as the composition of the glass yarn 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).

[0088] The silicon (Si) content of the glass yarn, converted from 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 yarn.

[0089] Therefore, by making the Si content, converted to SiO2, more than 40% by mass, there is a tendency for the strength of the glass yarn to be further improved, and for subsequent processes such as the manufacturing process of the glass cloth and the process of using the glass cloth to manufacture prepreg to be further suppressed.

[0090] Furthermore, by setting the Si content to 40% by mass or more (converted to SiO2), there is a tendency to further reduce the dielectric constant of the glass cloth of this embodiment. On the other hand, by setting the Si content to 60% by mass or less (converted to SiO2), there is a tendency to further reduce the viscosity at melt during the manufacturing process of the glass filament, resulting in glass fibers with a more uniform glass composition.

[0091] Therefore, the resulting glass filaments are less prone to localized devitrification or areas where air bubbles are difficult to remove, and consequently, they are less likely to have areas of weak strength. As a result, glass cloth made from the glass yarn obtained using this method is less prone to breakage. The Si content can be adjusted according to the amount of raw material used to make the glass filaments.

[0092] The boron (B) content of the glass yarn, converted to B2O3, is preferably 15-40% by mass, more preferably 17-30% by mass, or preferably 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.

[0093] By making the boron content (converted to B2O3) 15% or more by mass, there is a tendency for the dielectric constant to decrease further. Furthermore, by making the boron content (converted to B2O3) 15% or more by mass, the brittleness resistance of the glass cloth in this embodiment is improved, and the glass cloth is given appropriate softness or extensibility. Therefore, there is a tendency for linting to be less likely to occur when the glass yarn comes into contact with weaving components such as yarn guides and reeds.

[0094] On the other hand, in order to maintain the strength of the glass yarn, the B content, converted to B2O3, is preferably 40% by mass or less. By keeping the B content at 40% by mass or less, the moisture resistance is improved, and it is easier to maintain the stability of the surface properties of the glass yarn described later.

[0095] In particular, by making the Si content in the glass yarn within the range of SiO2 and the B content within the range of B2O3, the aforementioned effects related to Si and B can be easily and synergistically exerted, and is therefore preferred.

[0096] 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 may change, these can be estimated in advance and the amount of raw materials fed can be adjusted accordingly.

[0097] The aluminum (Al) content of the glass filament, converted to Al2O3, is preferably 11-18% by mass, more preferably 11-17.5% by mass, and even more preferably 12-17.0% by mass. By keeping the Al content, converted to Al2O3, within the above range, there is a tendency to further improve the electrical properties and strength. The Al content can be adjusted by the amount of raw material used to make the glass filament (feed amount).

[0098] The calcium (Ca) content of the glass fiber, converted to 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. By setting the Ca content to 5.0% by mass or more, there is a tendency to further reduce the viscosity at melt during the manufacturing process of the glass filament, resulting in glass fibers with a more uniform glass composition. Furthermore, by setting the Ca content to 10% by mass or less, there is a tendency to further increase the dielectric constant. The Ca content can be adjusted by the amount of raw material used in the production of the glass filament (feed amount).

[0099] The phosphorus (P) content of the glass cloth, 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, calculated as P2O5, can exceed 0% by mass. By making the P content, calculated as P2O5, exceed 0% by mass, there is a tendency for the glass cloth to have better dielectric properties. Furthermore, by making the P content, calculated as P2O5, 8.0% by mass or less, there is a tendency for the heat resistance of the glass cloth to be improved. The P content can be adjusted by the amount of raw material used to produce the glass filament (feed amount).

[0100] From the viewpoints of easily reducing the dielectric constant and dielectric loss tangent of the glass cloth, and from the viewpoints of easily producing a fabric structure with uniformity in the width direction, the sum of the boron and phosphorus content in the glass cloth is preferably 5% by mass or more and 20% by mass or less. There is a tendency that the higher the sum of the boron and phosphorus content in the glass cloth, the more effectively the dielectric constant and dielectric loss tangent of the glass cloth can be reduced. By making the sum of the boron and phosphorus content 5% by mass or more, the dielectric constant and dielectric loss tangent are significantly reduced compared to laminates obtained using general E-glass cloth, thus improving its applicability in high-capacity and high-speed data communication or signal processing.

[0101] From the viewpoint that it is easier to reduce the dielectric constant and dielectric loss tangent of the glass cloth, and that it is easier to produce a fabric structure with uniformity in the width direction, the sum of the boron content and phosphorus content in the glass cloth is preferably 6.5% by mass or more and 20% by mass or less.

[0102] The higher the sum of boron and phosphorus content in the glass cloth, the greater the tendency to reduce the dielectric constant and dielectric loss tangent of the glass cloth. By making the sum of boron and phosphorus content 6.5% by mass or more, the dielectric constant and dielectric loss tangent are significantly reduced compared to laminates obtained using ordinary E glass cloth. Therefore, its applicability in high-capacity and high-speed data communication or signal processing is improved.

[0103] For example, the dielectric constant of E glass is around 7. In contrast, when the sum of boron and phosphorus content is 7.4% by mass, the dielectric constant is about 4.8. Furthermore, when the sum of boron and phosphorus content is 9.2% by mass, the dielectric constant is about 4.4, showing a tendency for the dielectric constant to decrease.

[0104] If the sum of boron and phosphorus content is 5% by mass or more, the glass cloth of this embodiment has moderate softness. Therefore, during the warping / weaving process, flattening process, and fiber opening process of the glass cloth, the fabric structure is easily affected by tension and processing force, and thus there is a tendency to easily produce a fabric structure with a uniform width direction.

[0105] Furthermore, if the sum of boron and phosphorus content is 6.5% by mass or more, the glass cloth of this embodiment has moderate softness. Therefore, during the warping / weaving process, flattening process, and fiber opening process of the glass cloth, the fabric structure is easily affected by tension and processing force, and thus there is a tendency to easily produce a fabric structure with a uniform width direction.

[0106] By keeping the sum of boron and phosphorus content at 20% by mass or less, the moisture resistance and / or heat resistance of the glass cloth of this embodiment can be maintained as equivalent to that of E glass with a sum of boron and phosphorus content of about 2% by mass.

[0107] The sum of boron and phosphorus content in glass cloth can be adjusted during the glass yarn manufacturing process based on the amount of boron and phosphorus-containing glass raw materials fed into the machine. Furthermore, the boron and phosphorus content in the glass changes during the melting of the glass raw materials in the glass yarn manufacturing process; therefore, this change can be taken into account to appropriately adjust the feeding amount.

[0108] It should be noted that the above contents can be determined by ICP emission spectroscopy. Specifically, the Si and B contents can be obtained as follows: the weighed glass cloth is melted with sodium carbonate, dissolved in dilute nitric acid to prepare a sample of the specified volume, and then measured by ICP emission spectroscopy.

[0109] Alternatively, the Fe content can be obtained as follows: the weighed glass cloth is dissolved using an alkaline dissolution method to prepare a specified capacity, and the resulting sample is measured using ICP emission spectroscopy.

[0110] 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 hydrogen fluoride, then dissolved in dilute nitric acid to prepare a sample of the specified capacity, and the resulting sample is measured using ICP emission spectroscopy.

[0111] It should be noted that the PS3520VDDII manufactured by Hitachi Advanced Scientific Corporation can be used as an ICP emission spectroscopy analyzer.

[0112] Here, the content of the aforementioned elements constituting the glass cloth of this embodiment described in this specification is the weight of the elements themselves if there is no description of oxide conversion, and the weight of the aforementioned elements when they are made into oxides if there is a description of oxide conversion.

[0113] In addition, if necessary, the content of the above elements can be calculated based on the weight of the elements themselves, rather than based on the oxide, even when recorded in terms of weight converted from oxides.

[0114] From the viewpoint that the thickness of the glass cloth in this embodiment can be easily adjusted to 5μm to 100μm, the TEX of the glass yarn is preferably 1.0 or more and 25 or less, more preferably 1.5 or more and 23 or less, and even more preferably 2.0 or more and 21 or less.

[0115] The glass cloth of this embodiment can be surface-treated using a surface treatment agent. There are no particular limitations on the surface treatment agent; examples include silane coupling agents, and water, organic solvents, acids, dyes, pigments, surfactants, etc., can be used in conjunction as needed.

[0116] As a silane coupling agent, there are no particular limitations, and examples such as the compound shown in formula (1) can be listed.

[0117] X(R) 3-n SiY n ···(1)

[0118] (In formula (1), X is an organic functional group having at least one of amino and unsaturated double bond groups, Y is an alkoxy group, n is an integer of 1 to 3, and R is a group selected from the group consisting of methyl, ethyl and phenyl.)

[0119] 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.

[0120] As described above, any form of alkoxy group can be used, but from the viewpoint of stabilizing the glass cloth of this embodiment, an alkoxy group with 5 or fewer carbon atoms is preferred.

[0121] 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. Known monomers or mixtures thereof, including their hydrochlorides, 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.

[0122] The molecular weight of the silane coupling agent is preferably 100–600, more preferably 150–500, and even more preferably 200–450. It is preferable to use two or more silane coupling agents with different molecular weights. By using two or more silane coupling agents with different molecular weights to treat the surface of the glass cloth, there is a tendency for the density of the surface treatment agent on the glass cloth surface to increase, and for the reactivity with the base resin to be further improved.

[0123] <Methods for manufacturing glass cloth>

[0124] The manufacturing method of the glass cloth in this embodiment is not particularly limited, and the following methods can be listed: using glass yarn as warp and weft yarns, weaving it using conventional methods, and then performing post-processing such as treating the glass cloth fabric with a silane coupling agent. The weaving structure of the glass cloth is not particularly limited, and examples include plain weave, square weave, satin weave, and twill weave. Furthermore, a blended weave structure obtained using different types of glass yarn can also be used. Among these, a plain weave structure is preferred.

[0125] The manufacturing method of the glass cloth in this embodiment is not particularly limited, and a suitable example is a method having the following steps: a covering step in which a treatment solution with a concentration of 0.1 to 3.0 wt% of silane coupling agent is applied to the glass cloth, thereby covering the surface of the glass filaments almost completely with silane coupling agent; a fixing step in which the silane coupling agent is fixed to the surface of the glass filaments by heating and drying; and a fiber opening step in which the glass yarn of the glass cloth is opened.

[0126] Water or organic solvents can be used as solvents to dissolve or disperse silane coupling agents, but from the viewpoint 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, any of the following methods are preferred: a method of directly adding the silane coupling agent to water; or a method of dissolving the silane coupling agent in a water-soluble organic solvent to prepare an organic solvent solution, and then adding the 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.

[0127] Methods for coating glass cloth with a silane coupling agent treatment solution include: (A) immersing the glass cloth in a bath by storing the silane coupling agent treatment solution (hereinafter referred to as the "immersion method"); and (B) 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 (A), it is preferable to set the immersion time of the glass cloth in the treatment solution to 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.

[0128] To ensure sufficient reaction between the silane coupling agent and the glass, the heating and drying temperature is preferably 90°C or higher, more preferably 100°C or higher. 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.

[0129] 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), vibration cleaner, ultrasonic water, and a mangle mill to process glass cloth. In order to keep the total area of ​​the basket holes within a specified range, it is preferable to use water spray for the fiber opening process.

[0130] When using water spray for fiber opening, the water pressure can be set appropriately. To adjust the total area of ​​the pores in the glass cloth, it is preferable to set the water pressure to a constant value. Here, setting the water pressure to a constant value means reducing the difference between the maximum and minimum values ​​of the spray water pressure set for fiber opening and the actual water pressure. A heating and drying process can also be included before or after the fiber opening process.

[0131] <Prepreg>

[0132] This embodiment is also a prepreg, which is a composite of the aforementioned glass cloth and base resin composition. The base resin composition is impregnated into the glass cloth.

[0133] Prepregs can be manufactured using conventional methods. For example, they can be produced by impregnating glass cloth with a varnish obtained by diluting a base resin composition with an organic solvent, followed by evaporating the organic solvent using a drying oven, thereby producing a prepreg impregnated with the base resin composition.

[0134] Both thermosetting resins and thermoplastic resins can be used as resins constituting the base resin composition. As thermosetting resins, there are no particular limitations, but examples include: a) epoxy resins that are cured by reacting an epoxy-containing compound with a compound having at least one of the following groups (amino, phenolic, anhydride, hydrazide, isocyanate, cyanate, and hydroxyl groups) under catalyst-free conditions or with the addition of a catalyst having reaction catalytic ability such as imidazole, tertiary amine, urea, or phosphorus compounds; b) free radical polymerization type cured resins that use a thermally decomposable catalyst or a photodecomposable catalyst as a reaction initiator to cure a compound having at least one of the following groups (vinyl, allyl, methacryloyl, and acryloyl); c) maleimide triazine resins that are cured by reacting a compound having a cyanate group with a compound having a maleimide group; d) thermosetting polyimide resins that are cured by reacting a maleimide compound with an amine compound; and e) benzoxazine resins that are cured by crosslinking a compound having a benzoxazine ring through heating polymerization.

[0135] 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.

[0136] The resin in the base resin composition of the prepreg, which constitutes one embodiment of this invention and is composed of glass cloth and a base resin composition, is preferably a polyphenylene ether resin. More preferably, it is a polyphenylene ether resin having 1.5 to 5 functional groups containing carbon-carbon double bonds, such as vinyl, allyl, methacryloyl, and acryloyl groups, per molecule at the end of the main chain. Furthermore, a polyphenylene ether resin with a number average molecular weight of 500 to 8000 is preferred. Since a polyphenylene ether resin is the base resin, it exhibits excellent dielectric properties and is therefore preferred.

[0137] Furthermore, it can be inferred that the resin constituting the base resin composition, by having the aforementioned functional groups and number-average molecular weight, allows the resin composition to easily penetrate into the interior of the glass cloth during the prepreg manufacturing process and the pressure molding process, ensuring a large number of bonding points with the glass cloth. Therefore, it has excellent dielectric properties. However, even in a system where the number of direct bonding points between the resin base layers formed above and below the glass cloth is reduced due to the high in-plane uniformity and low air permeability of the glass as in this embodiment, the heat resistance and insulation reliability are also improved by exhibiting strong adhesion at the interface between the glass cloth and the resin composition.

[0138] Printed Circuit Boards

[0139] This embodiment is also a printed circuit board having the aforementioned glass cloth and a cured product of a base resin composition impregnated in the aforementioned glass cloth.

[0140] Furthermore, the printed circuit board of this embodiment is manufactured using the aforementioned prepreg. That is, the printed circuit board of this embodiment is a printed circuit board formed from the prepreg of this embodiment. By using the prepreg of this embodiment to manufacture the printed circuit board, it is possible to provide a high-quality printed circuit board in which the difference in signal propagation speed among multiple transmission lines is reduced.

[0141] Example

[0142] The present invention will now be described in more detail using examples and comparative examples. The present invention is not limited to the following examples.

[0143] [Elastic modulus]

[0144] The elastic modulus of glass yarn is determined as follows: a glass block obtained by melting and cooling the glass yarn is used as a test piece, and the measurement is performed using the pulse-echo overlap method.

[0145] [Evaluation: Average warp width and standard deviation of warp width]

[0146] The camera scans along the direction perpendicular to the MD direction of the glass cloth to acquire images of the warp yarns representing the width of the glass cloth, and the width of each warp yarn is measured. The average value and standard deviation of the warp width representing the width of the glass cloth are then calculated.

[0147] [Evaluation: Warp width at the ends and center]

[0148] The camera is scanned along the direction perpendicular to the MD direction of the glass cloth to obtain an image of the warp yarns of the glass cloth width, and the width of each warp yarn is measured.

[0149] Calculate the average warp width of the glass cloth within a range from 100mm to 250mm from each end in the width direction, and take the smaller value as the warp width at the end. Additionally, calculate the average warp width from the center of the width direction, extending 75mm to the left and right, and take this as the warp width of the central section.

[0150] [Evaluation: Average thickness]

[0151] The thickness of the glass cloth was measured at three points along its width, with equal intervals between the two ends and the measurement points, according to JIS R 3420. The thicknesses at the three points were averaged, and the first decimal place was rounded to obtain the average thickness (μm).

[0152] [Evaluation: Thickness at the ends and in the center]

[0153] The thickness of the glass cloth is measured at 100mm inside each end along its width, according to JIS R3420. The larger of the two thicknesses is taken as the end thickness (μm).

[0154] In addition, the center of the glass cloth in the width direction is used as the measurement point, and the thickness is measured according to JIS R3420. The obtained thickness is taken as the thickness (mm) of the central part.

[0155] [Evaluation: Air permeability at the ends and in the center]

[0156] The air permeability of the glass cloth was measured at 100mm inside each end along its width, according to JIS R3420. The larger of the two measured air permeability values ​​was taken as the end air permeability (cm). 3 / cm 2 / s).

[0157] In addition, the air permeability was measured according to JIS R3420, using the center of the glass cloth in the width direction as the measurement point. The obtained air permeability was taken as the air permeability of the central part (cm). 3 / cm 2 / s).

[0158] [Evaluation: Evaluation of the resin impregnation properties of glass cloth]

[0159] Test pieces for permeation measurement were taken from the inner side of both ends of the glass cloth in the width direction, 100 mm from each end. Additionally, test pieces for permeation measurement were taken from the center of the glass cloth in the width direction.

[0160] Bisphenol A type epoxy resin was dissolved in benzyl alcohol at 23±2℃ to prepare a varnish for penetrability evaluation with a viscosity of 230±5 mPa·s. Then, glass cloth test pieces were immersed in the varnish, and the penetration of the varnish into the glass cloth was observed using an optical microscope while irradiating it from the side.

[0161] Furthermore, the number of pores (unimpregnated areas of the varnish used for evaluating the permeability) after the glass cloth test piece has been immersed in the varnish for a specified period of time is counted. At this time, the field of view of the glass cloth observed using an optical microscope is set to approximately 6.5 mm in the warp direction and approximately 9 mm in the weft direction.

[0162] Regarding the two ends in the width direction, the value with the larger number of voids is taken as the number of residual voids (roots) at the end.

[0163] For the glass cloth of Example 1 and Comparative Example 1, the number of voids was counted after 2 minutes.

[0164] For the glass cloths of Examples 2, 2B, 2C, 2D, 2E, 2F and Comparative Example 2, count the number of voids after 3 minutes.

[0165] For the glass cloths of Examples 3 and 4, Comparative Examples 3 and 4, and Reference Example 1, count the number of voids after 5 minutes.

[0166] For the glass cloths of Examples 5 and 6, and Comparative Examples 5 and 6, the number of voids was counted after 8 minutes.

[0167] [Evaluation: The slack in the fabric during handling]

[0168] When unwinding the glass cloth from the core under a tension of 150 N and carrying it for 2 m, a guide roller bends it at 90°. A displacement meter (a laser application sensor manufactured by Keyence) is used to measure the tackiness of the glass cloth from unwinding to the guide roller. The displacement meter is installed at two points 100 mm inside each end of the glass cloth in the width direction and at the center in the width direction. The difference between the maximum and minimum vertical positions of the glass cloth measured by the displacement meter is taken as the degree of tackiness (unit: mm).

[0169] [Evaluation: The difference (%) in the warp elongation under a 50 N / inch load in the stress-strain curve and the difference (%) in the slope of the stress-strain curve in the width direction]

[0170] The elongation and slope of glass cloth under tension along the warp direction were determined according to the method described in Section 7.4 Tensile Strength of the General Test Method for Glass in JIS R3420. In this JIS method, a test piece approximately 30 mm wide and 250 mm long was taken from the warp direction of the fabric. The yarns at both ends of the test piece were untied to a width of approximately 25 mm, and a clamping interval of approximately 150 mm was ensured. The piece was then mounted in the clamping section and stretched at a tensile speed of approximately 200 mm / min to determine the load at break. In this embodiment, to improve measurement accuracy, the tensile speed was set to approximately 5 mm / min. Otherwise, the tensile test was performed under the same conditions as the method specified in the JIS above.

[0171] Stress-strain curves were measured from within 50 mm to 200 mm of both ends of the glass cloth in the width direction. Additionally, stress-strain curves were measured from the center of the glass cloth in the width direction.

[0172] Calculate the displacement (mm) when a 50N load is applied to every 25mm width of the glass cloth, and calculate the ratio of the elongation at the ends to the center in the width direction. It should be noted that for the two ends in the width direction, the larger elongation value is taken as the elongation at the end (mm).

[0173] In addition, the slope (elongation (mm) / 50N) is calculated based on the elongation (mm) when a 50N load is applied to every 25mm width of the glass cloth, and the ratio of the slope at the ends to the slope at the center in the width direction is determined. It should be noted that, for the two ends in the width direction, the value with the larger slope is taken as the slope at the end.

[0174] <Comparative Example 1>

[0175] Both the warp and weft yarns use LCBC1700 low dielectric glass yarn (elastic modulus of 61 GPa, TEX of 2.92) manufactured by AGY Company. The glass cloth (grey fabric) is woven using an air-jet loom with a warp yarn drive-in density of 74 ends / 25 mm and a weft yarn drive-in density of 74 ends / 25 mm.

[0176] The resulting fabric was subjected to a fiber-opening treatment based on sizing water washing and high-pressure water spraying. Next, after desizing by heat treatment at 400°C for 24 hours, the glass cloth was immersed in a treatment solution using a silane coupling agent as a surface treatment agent. After squeezing out the liquid, it was dried at 120°C for 1 minute. Then, a fiber-opening process based on high-pressure water spraying was performed to obtain glass cloth with a width of 1300 mm.

[0177] <Example 1>

[0178] By adjusting the warp tension during warping and the pressure of the high-pressure water spray during fiber opening in the same manner as the warp width in the range from 100mm to 300mm from the end in the width direction, the linear tension during fiber opening based on sizing water washing and high-pressure water spray is adjusted to be low. Otherwise, glass cloth with a width of 1300mm is manufactured using the same method as Comparative Example 1.

[0179] Regarding the tension during warping, the tension in the range from 100mm to 300mm from the end in the width direction was set to 0.8 times the tension in other ranges. Regarding the pressure of the high-pressure water spray, the spray pressure in the range from 100mm to 300mm from the end in the width direction was set to 1.2 times the pressure in other ranges. The linear tension during the fiber opening process based on slurry washing and high-pressure water spray was set to 0.5 times that of Comparative Example 1.

[0180] <Comparative Example 2>

[0181] Both the warp and weft yarns use LCD1020 low-dielectric glass yarn manufactured by AGY (elastic modulus of 61GPa, TEX of 4.86), and are woven on an air-jet loom with a warp yarn drive density of 69 ends / 25mm and a weft yarn drive density of 69 ends / 25mm.

[0182] The resulting fabric was subjected to a fiber-opening treatment based on sizing water washing and high-pressure water spraying. Next, after desizing by heat treatment at 400°C for 24 hours, the glass cloth was immersed in a treatment solution using a silane coupling agent as a surface treatment agent. After squeezing out the liquid, it was dried at 120°C for 1 minute. Then, a fiber-opening process based on high-pressure water spraying was performed to obtain glass cloth with a width of 1300 mm.

[0183] <Example 2>

[0184] By adjusting the warp tension during warping and the pressure of the high-pressure water spray during fiber opening in the same manner as the warp width in the range from 100mm to 300mm from the end in the width direction, the linear tension during fiber opening based on sizing water washing and high-pressure water spray is adjusted to be low. Otherwise, glass cloth with a width of 1300mm is manufactured using the same method as Comparative Example 2.

[0185] Regarding the tension during warping, the tension in the range from 100mm to 300mm from the end in the width direction was set to 0.8 times the tension in other ranges. Regarding the pressure of the high-pressure water spray, the spray pressure in the range from 100mm to 300mm from the end in the width direction was set to 1.2 times the pressure in other ranges. The linear tension during the fiber opening process based on slurry washing and high-pressure water spray was set to 0.5 times that of Comparative Example 2.

[0186] <Example 2B>

[0187] Set the tension in the range from 100mm from the end of the width direction to 300mm from the end to 0.9 times the tension in other ranges.

[0188] Regarding the pressure of the high-pressure water spray, the spray pressure in the range from 100mm from the end of the width direction to 300mm from the end is set to 1.2 times that of other ranges.

[0189] The linear tension during the fiber opening process based on pulp washing and high-pressure water spraying was set to 0.5 times that of Comparative Example 2.

[0190] <Example 2C>

[0191] Set the tension in the range from 100mm from the end of the width direction to 300mm from the end to 0.8 times the tension in other ranges.

[0192] Regarding the pressure of the high-pressure water spray, the spray pressure in the range from 100mm from the end of the width direction to 300mm from the end is set to 1.1 times that of other ranges.

[0193] The linear tension during the fiber opening process based on pulp washing and high-pressure water spraying was set to 0.5 times that of Comparative Example 2.

[0194] <Example 2D>

[0195] Set the tension in the range from 100mm from the end of the width direction to 300mm from the end to 0.9 times the tension in other ranges.

[0196] Regarding the pressure of the high-pressure water spray, the spray pressure in the range from 100mm from the end of the width direction to 300mm from the end is set to 1.1 times that of other ranges.

[0197] The linear tension during the fiber opening process based on pulp washing and high-pressure water spraying was set to 0.5 times that of Comparative Example 2.

[0198] <Example 2E>

[0199] Set the tension in the range from 100mm from the end of the width direction to 300mm from the end to 0.9 times the tension in other ranges.

[0200] Regarding the pressure of the high-pressure water spray, the spray pressure in the range from 100mm from the end of the width direction to 300mm from the end is set to 1.1 times that of other ranges.

[0201] The linear tension during the fiber opening process based on pulp washing and high-pressure water spraying was set to 0.8 times that of Comparative Example 2.

[0202] <Example 2F>

[0203] After performing the fiber opening process based on high-pressure water spray, the two ends including the selvage are cut off and processed into a width of 1250mm. Otherwise, the glass cloth with a width of 1250mm is manufactured using the same method as in Example 2.

[0204] <Comparative Example 3>

[0205] Both the warp and weft yarns use LCD510 low-dielectric glass yarn (elastic modulus of 61 GPa, TEX of 9.73) manufactured by AGY Company. The glass cloth (grey fabric) is woven using an air-jet loom with a warp yarn drive density of 52.5 ends / 25mm and a weft yarn drive density of 52.5 ends / 25mm.

[0206] The resulting fabric was subjected to a fiber-opening treatment based on sizing water washing and high-pressure water spraying. Next, after desizing by heat treatment at 400°C for 24 hours, the glass cloth was immersed in a treatment solution using a silane coupling agent as a surface treatment agent. After squeezing out the liquid, it was dried at 120°C for 1 minute. Then, a fiber-opening process based on high-pressure water spraying was performed to obtain glass cloth with a width of 1300 mm.

[0207] <Example 3>

[0208] By adjusting the warp width in the width direction, from 100mm to 300mm from the end of the yarn in the width direction to the same width as in other directions, the tension during warping and the pressure of the high-pressure water spray during fiber opening are adjusted in the width direction to lower the linear tension during fiber opening based on sizing water washing and high-pressure water spray. Otherwise, a glass cloth with a width of 1300mm is manufactured using the same method as in Comparative Example 3.

[0209] Regarding the tension during warping, the tension in the range from 100mm from the end of the width direction to 300mm from the end is set to 0.8 times the tension in other ranges.

[0210] Regarding the pressure of the high-pressure water spray, the spray pressure in the range from 100mm from the end of the width direction to 300mm from the end is set to 1.2 times that of other ranges.

[0211] The linear tension during the fiber opening process based on pulp washing and high-pressure water spraying was set to 0.5 times that of Comparative Example 3.

[0212] <Comparative Example 4>

[0213] Both the warp and weft yarns used were LCD520 low-dielectric glass yarn manufactured by AGY Corporation (elastic modulus of 56 GPa, TEX of 9.47). In addition, a glass cloth with a width of 1300 mm was manufactured using the same method as in Comparative Example 3.

[0214] <Example 4>

[0215] Both the warp and weft yarns used were LCD520 low-dielectric glass yarn manufactured by AGY Corporation (elastic modulus of 56 GPa, TEX of 9.47). In addition, a glass cloth with a width of 1300 mm was manufactured using the same method as in Example 3.

[0216] <Comparative Example 5>

[0217] Both the warp and weft yarns use AGY's low dielectric glass yarn LCDE340 (elastic modulus of 61 GPa, TEX of 14.59), and are woven on an air-jet loom with a warp yarn drive-in density of 59 ends / 25 mm and a weft yarn drive-in density of 61 ends / 25 mm.

[0218] The resulting fabric was subjected to a fiber-opening treatment based on sizing water washing and high-pressure water spraying. Next, after desizing by heat treatment at 400°C for 24 hours, the glass cloth was immersed in a treatment solution using a silane coupling agent as a surface treatment agent. After squeezing out the liquid, it was dried at 120°C for 1 minute. Then, a fiber-opening process based on high-pressure water spraying was performed to obtain glass cloth with a width of 1300 mm.

[0219] <Example 5>

[0220] By adjusting the warp tension during warping and the pressure of the high-pressure water spray during fiber opening in the same manner as the warp width in the range from 100 mm to 300 mm from the end in the width direction, the linear tension during fiber opening based on sizing water washing and high-pressure water spray is adjusted to be low. Otherwise, glass cloth with a width of 1300 mm is manufactured using the same method as Comparative Example 5.

[0221] Regarding the tension during warping, the tension in the range from 100mm from the end in the width direction to 300mm from the end is set to 0.8 times the tension in other ranges.

[0222] Regarding the pressure of the high-pressure water spray, the spray pressure in the range from 100mm from the end of the width direction to 300mm from the end is set to 1.2 times that of other ranges.

[0223] The linear tension during the fiber opening process based on pulp washing and high-pressure water spraying was set to 0.5 times that of Comparative Example 5.

[0224] <Comparative Example 6>

[0225] Both the warp and weft yarns use AGY's low dielectric glass yarn LCE255 (elastic modulus of 61 GPa, TEX of 19.45), and are woven on an air-jet loom with a warp yarn drive-in density of 60 ends / 25mm and a weft yarn drive-in density of 57 ends / 25mm.

[0226] The resulting fabric was subjected to a fiber-opening treatment based on sizing water washing and high-pressure water spraying. Next, after desizing by heat treatment at 400°C for 24 hours, the glass cloth was immersed in a treatment solution using a silane coupling agent as a surface treatment agent. After squeezing out the liquid, it was dried at 120°C for 1 minute. Then, a fiber-opening process based on high-pressure water spraying was performed to obtain glass cloth with a width of 1300 mm.

[0227] <Example 6>

[0228] By adjusting the warp tension during warping and the pressure of the high-pressure water spray during fiber opening in the same manner as the warp width in the range from 100 mm to 300 mm from the end in the width direction, the linear tension during fiber opening based on sizing water washing and high-pressure water spray is adjusted to be low. Otherwise, glass cloth with a width of 1300 mm is manufactured using the same method as Comparative Example 6.

[0229] Regarding the tension during warping, the tension in the range from 100mm from the end of the width direction to 300mm from the end is set to 0.8 times the tension in other ranges.

[0230] Regarding the pressure of the high-pressure water spray, the spray pressure in the range from 100mm from the end in the width direction to 300mm from the end is set to 1.2 times that of other ranges.

[0231] The linear tension during the fiber opening process based on pulp washing and high-pressure water spraying was set to 0.5 times that of Comparative Example 6.

[0232] <Reference Example 1>

[0233] Both the warp and weft yarns are made of E glass yarn D450 (elastic modulus of 74 GPa, TEX of 11.05). Otherwise, a glass cloth with a width of 1300 mm was manufactured using the same method as in Comparative Example 3.

[0234] Compared to the glass cloth of the comparative example, the low-dielectric glass cloth of the embodiment exhibits less stickiness. Furthermore, compared to the glass cloth of the comparative example, the glass cloth of the embodiment has the same thickness at the ends and center in the width direction, air permeability, resin impregnation, elongation in the stress-strain curve, and slope.

[0235] The conventional high elastic modulus E glass cloth shown in the reference example is manufactured using the same method as Comparative Example 3. However, compared with the glass cloths of Comparative Examples 3 and 4, it is less sticky, and its thickness, air permeability, resin impregnation, elongation and slope in the stress-strain curve are also the same at the ends and center in the width direction.

[0236] High slackness and stickiness are unique problems of low-dielectric glass cloth with low elastic modulus, but it can be clearly seen that they are solved by this embodiment.

[0237] [Table 1]

[0238]

[0239] [Table 2]

[0240]

[0241] [Table 3]

[0242]

[0243] [Table 4]

[0244]

[0245] [Table 5]

[0246]

[0247] [Table 6]

[0248]

[0249] [Table 7]

[0250]

Claims

1. A type of glass cloth, comprising glass yarn formed from multiple glass filaments as warp and weft yarns, wherein the thickness of the glass cloth is 5μm to 100μm. The width of the glass cloth is 1000mm or more, and The difference X between the warp width at the end of the width direction and the center of the width direction of the glass cloth is less than or equal to the standard deviation α of the warp width of the glass cloth width.

2. The glass cloth according to claim 1, wherein, The difference X in warp width is less than 0.7 times the standard deviation α of the warp width of the glass cloth width.

3. The glass cloth according to claim 1, wherein, The difference X in warp width is less than 0.5 times the standard deviation α of the warp width of the glass cloth width.

4. The glass cloth according to claim 1 or 2, wherein, The standard deviation α of the warp width of the glass cloth width is less than 0.08 times the average value β of the warp width of the glass cloth width.

5. The glass cloth according to claim 1 or 2, wherein, The standard deviation α of the warp width of the glass cloth width is less than 0.04 times the average value β of the warp width of the glass cloth width.

6. The glass cloth according to claim 1 or 2, wherein, The standard deviation α of the warp width of the glass cloth width is less than 0.03 times the average value β of the warp width of the glass cloth width.

7. The glass cloth according to claim 1 or 2, wherein, The TEX of the glass yarn is above 1.0 and below 25.

8. The glass cloth according to claim 1 or 2, wherein, The TEX of the glass yarn is 1.5 or higher and 23 or lower.

9. The glass cloth according to claim 1 or 2, wherein, The TEX of the glass yarn is above 2.0 and below 21.

10. The glass cloth according to claim 1 or 2, wherein it is composed of glass yarn with an elastic modulus of 50 GPa or more and 70 GPa or less.

11. The glass cloth according to claim 1 or 2, wherein it is composed of glass yarn with an elastic modulus of 50 GPa or more and 63 GPa or less.

12. The glass cloth according to claim 1 or 2, wherein it is composed of glass yarn with an elastic modulus of 52 GPa or more and 63 GPa or less.

13. The glass cloth according to claim 1 or 2, wherein, The dielectric constant is below 5.0 at a frequency of 1 GHz.

14. The glass cloth according to claim 1 or 2, wherein, The warp and weft yarn density of the glass cloth is 30~120 yarns / 25mm.

15. The glass cloth according to claim 1 or 2, wherein, The average diameter of the glass monofilaments that make up the warp and weft yarns is independently 2.5~9μm.

16. The glass cloth according to claim 1 or 2, wherein, The average number of glass monofilaments that make up the warp and weft yarns is 20 to 250.

17. The glass cloth according to claim 1 or 2, wherein the thermal weight loss value ranges from 0.25% to 1.5% by mass.

18. The glass cloth according to claim 1 or 2, wherein, The sum of the boron and phosphorus content in the glass cloth is more than 5% by mass and less than 20% by mass.

19. The glass cloth according to claim 1 or 2, wherein, The sum of the boron and phosphorus content in the glass cloth is 6.5% by mass or more and 20% by mass or less.

20. A prepreg having the glass cloth of claim 1 or 2 and a base resin composition impregnated in the glass cloth.

21. A printed circuit board having a glass cloth as described in claim 1 or 2, and a cured product of a base resin composition impregnated in the glass cloth.

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