Glass cloth, prepreg and printed circuit board

Abstract

According to the present application, provided are: a silica glass cloth which comprises glass yarns having a high silica (SiO2) content and which has little fluff; and a prepreg, a printed wiring board, and the like, each of which comprises the silica glass cloth. The glass cloth according to the present application is configured from glass yarns comprising a plurality of filaments as warp yarns and weft yarns, wherein the glass yarns have a silicon (Si) content of 95.0-100 mass% in terms of silica (SiO2). The glass cloth has a thickness (T) of 80 [mu] m or less, and satisfies {the number of warp bundle segments (N)-0.2} / thickness (T) [[mu] m] lt; and 0.056%.

Description

Technical Field

[0001] This application relates to glass cloth, prepreg, printed circuit board, etc. This international application claims priority based on Japanese Patent Application No. 2023-023729, filed on February 17, 2023, the entire contents of which are incorporated herein by reference. Background Art

[0002] Now, the high performance of information terminals such as smart phones and the high-speed communication represented by 5G communication are developing.Along with this background, especially for high-speed communication printed circuit board, it is not only desirable to improve the high density, extreme thinning, heat resistance sought all the time, it is also desirable to further improve the dielectric properties (such as low dielectric loss tangent) of the insulating material.Similarly, for the prepreg used in the insulating material of printed circuit board, the glass cloth included in the prepreg and the glass yarn constituting the glass cloth, it is also desirable to improve dielectric properties.

[0003] To improve the dielectric properties of prepregs, it is known to use low-dielectric glass to form prepregs. Patent Documents 1 and 2 use glass yarns containing 98-100% by mass of silicon dioxide (SiO2). Patent Document 3 also describes a sizing agent for suppressing fuzzing in such glass yarns.

[0004] On the other hand, opening glass cloth reduces the formation of air bubbles known as voids in prepregs and printed circuit boards, improving resin impregnation. Reducing voids and improving resin impregnation are known to improve the heat resistance and insulation properties of printed circuit boards. Therefore, the opening process is crucial in the glass cloth manufacturing process. Patent Documents 4 and 5 describe glass cloth opening techniques using water pressure, such as water jets, and glass cloth opening techniques using ultrasound, for example.

[0005] Patent Document 6 describes that by setting the yarn width unevenness within a specific range, voids can be reduced and fuzzing can be suppressed. Patent Document 7 describes improving the smoothness and resin impregnation properties of glass cloth by utilizing a woven structure.

[0006] Glass cloth has various IPC standards that specify warp and weft weave density, filament diameter, and filament count, and is typically woven according to these standards. Generally speaking, using yarn with a fine filament diameter facilitates reducing the thickness of the glass cloth and ensures a sufficient weave density, making problems like mesh shifting less likely to occur. Therefore, thin glass cloth is woven using yarn with a fine filament diameter.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2018-127747

[0010] Patent Document 2: Japanese Patent Application Publication No. 2018-127752

[0011] Patent Document 3: Japanese Patent Application Laid-Open No. 2015-78079

[0012] Patent Document 4: Japanese Patent Application Laid-Open No. 2009-263824

[0013] Patent Document 5: Japanese Patent Application Laid-Open No. 2020-158945

[0014] Patent Document 6: Japanese Patent Application Laid-Open No. 2022-181738

[0015] Patent Document 7: Japanese Patent Application Laid-Open No. 2003-82562 Summary of the Invention

[0016] Problems to be solved by the invention

[0017] The present inventors have found through research that there is room for further improvement in the fuzzing when using quartz glass having a high silicon dioxide (SiO2) content in the prior art techniques described in Patent Documents 1 to 7. This will be described in detail below.

[0018] One of the objects of the present application is to provide a quartz glass cloth composed of glass yarn having a high silica (SiO2) content and having little fuzz, as well as a prepreg and a printed circuit board containing the same.

[0019] Solutions for solving problems

[0020] Some aspects of the present application are exemplified in the following items [1] to

[16] .

[0021] [1] A glass cloth comprising glass yarns comprising a plurality of filaments as warp yarns and weft yarns,

[0022] The silicon (Si) content of the glass yarn is 95.0% to 100% by mass as calculated as silicon dioxide (SiO2).

[0023] The glass cloth has a thickness (T) of 80 μm or less and satisfies the following formula (A1):

[0024] {Number of warp yarn segments (N) - 0.2} / Thickness (T) [μm] < 0.056…(A1)

[0025] In formula (A1), the number of warp yarn segments (N) is a value obtained by: warp yarn filament diameter [μm] × number of warp yarn filaments [pieces] ÷ warp yarn width [μm].

[0026] [2] The glass cloth according to item 1, wherein after embedding the glass cloth with an epoxy resin and curing the epoxy resin, when observing a cross section of the glass cloth, the warp yarn bonding ratio calculated by the following formula exceeds 0 and is 0.80 or less,

[0027] Warp yarn bonding ratio = number of bonding points of filaments bonded to each other in the warp yarn / number of warp yarn filaments.

[0028] [3] The glass cloth according to item 1 or 2, which is treated with a surface treatment agent containing a silane coupling agent.

[0029] [4] The glass cloth according to item 3, wherein the silane coupling agent comprises a compound represented by the following formula (C).

[0030] X(R) 3-n SiE n …(C)

[0031] {In formula (C), X is an organic group having at least one of an amino group and an unsaturated double bond group having free radical reactivity, 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 a methyl group, an ethyl group, and a phenyl group.}

[0032] [5] The glass cloth according to item 4, wherein X in the formula (C) is an organic group having one or more methacryloxy groups or acryloyloxy groups.

[0033] [6] The glass cloth according to any one of items 1 to 5, wherein the average filament diameter (D) of the glass yarn is 4 μm or more.

[0034] [7] The glass cloth according to any one of items 1 to 6, wherein when the thickness of the glass cloth is 20 μm or more and 80 μm or less, the following formula (B1) is satisfied, and when the thickness of the glass cloth is less than 20 μm, the following formula (B6) is satisfied.

[0035] 24×average filament diameter (D) [μm]-thickness (T) [μm]>96…(B1)

[0036] 14×average filament diameter (D) [μm] - thickness (T) [μm] > 46… (B6)

[0037] [8] The glass cloth according to any one of items 1 to 7, wherein the glass cloth has a thickness (T) of 60 μm or less.

[0038] [9] The glass cloth according to any one of items 1 to 8, wherein the glass cloth has a loss on ignition value in the range of 0.01% by mass to 0.30% by mass.

[0039]

[10] The glass cloth according to any one of items 1 to 9, which is used for a printed circuit board.

[0040]

[11] A prepreg comprising the glass cloth according to any one of items 1 to 10, a thermosetting resin, and an inorganic filler.

[0041]

[12] A printed circuit board comprising the prepreg according to item 11.

[0042]

[13] An integrated circuit comprising the printed circuit board described in item 12.

[0043]

[14] An electronic device comprising the printed circuit board described in item 12.

[0044]

[15] A method for manufacturing glass cloth, wherein the method comprises:

[0045] A process of weaving glass yarns containing a plurality of filaments and having an Si content in the range of 95.0% by mass to 100% by mass as SiO2 as warp and weft to obtain glass cloth.

[0046] The aforementioned method further includes:

[0047] Prior to the weaving step, the glass yarn bundle is flattened, and then a warping step of sizing is performed; and

[0048] After the warping step and before, during or after the weaving step, the following steps are also included:

[0049] The process of washing glass yarn with water above 50°C;

[0050] a step of heating and deoiling the washed glass yarn; and

[0051] The process of washing and opening the glass yarn that has been heated and deoiled is carried out in a liquid irradiated with ultrasonic waves at a speed of 50 m / min or less.

[0052] The thickness (T) of the glass cloth after the fiber opening treatment is 80 μm or less.

[0053] When the thickness of the glass cloth after the fiber-spreading treatment is 20 μm or more and 80 μm or less, the following formula (B1) is satisfied. When the thickness of the glass cloth after the fiber-spreading treatment is less than 20 μm, the following formula (B6) is satisfied:

[0054] 24×average filament diameter (D) [μm]-thickness (T) [μm]>96…(B1)

[0055] 14×average filament diameter (D) [μm]-thickness (T) [μm]>46…(B6).

[0056]

[16] The method according to item 15 further comprises: a step of surface treating the glass cloth that has been cleaned and opened using a surface treatment agent.

[0057] Effects of the Invention

[0058] The present application can provide quartz glass cloth composed of glass yarn with a high silica (SiO2) content and low fuzzing, as well as prepreg and printed circuit board containing the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 (a) and (b) are SEM images for explaining the calculation method of the "bonding ratio" in the present application. DETAILED DESCRIPTION

[0060] Hereinafter, embodiments of the present application will be described, but the present application is not limited thereto and various modifications can be made without departing from the spirit and scope of the present application.

[0061] In this application, the numerical range recorded using "to" represents a numerical range that includes the numerical values before and after "to" as the lower limit and upper limit. In addition, within the numerical range recorded in stages, the upper limit or lower limit recorded in a certain numerical range can be replaced with the upper limit or lower limit of the numerical range recorded in other stages. Furthermore, the upper limit or lower limit recorded in a certain numerical range can also be replaced with the value shown in the embodiment. In addition, the term "process" not only includes independent processes, but also includes processes as long as the function of the process is achieved, even if it cannot be clearly distinguished from other processes.

[0062] Glass Cloth

[0063] The glass cloth of the present application is a glass cloth comprising glass yarns containing a plurality of filaments as warp and weft yarns. The silicon (Si) content of the glass yarns, calculated as silicon dioxide (SiO2), is 95.0% by mass or more and 100% by mass or less, the thickness (T) of the glass cloth is 80 μm or less, and the following formula (A1) is satisfied:

[0064] {Number of warp yarn segments (N) - 0.2} / T [μm] < 0.056…(A1).

[0065] In formula (A1), "number of warp yarn segments (N)" refers to the number of filament segments contained in the warp yarn bundle of the glass cloth, calculated based on the warp filament diameter [μm], the number of warp filaments [pieces], and the warp width [μm]. Regarding the glass cloth of the present application, in a preferred embodiment, after embedding the glass cloth with an epoxy resin and curing the resin, when observing a cross-section of the glass cloth, the warp yarn bonding ratio calculated using the following formula is greater than 0 and less than 0.80.

[0066] Warp bonding ratio = number of bonding points of filaments bonded to each other in the warp yarn / number of filaments in the warp yarn

[0067] The object embedded with the epoxy resin may be at least a portion of the glass cloth.

[0068] As described in Patent Documents 1 and 2, glass with a high SiO2 content generally has low bending resistance and lacks flexibility even in the form of glass cloth. Therefore, it is more prone to fuzzing and wrinkling than other types of glass, which poses a problem. Regarding this issue, Patent Document 1 describes a method for suppressing fuzzing in prepregs by surface treating the glass cloth. Separately, Patent Document 2 describes a method for suppressing fuzzing in glass cloth by using glass yarn coated with a specified amount of paste. However, the inventors' research has shown that the method in Patent Document 1 cannot suppress fuzzing that occurs before surface treatment, and there is room for improvement. Furthermore, it has been found that the methods described in Patent Documents 1 and 2, in particular, have room for improvement in the resin impregnation properties of the glass cloth.

[0069] Patent Document 3 describes a method for suppressing fuzzing by using a glass fiber sizing agent having a specific composition. However, the present inventors' research revealed that the method of Patent Document 3 suppresses fuzzing without requiring heating for degreasing or fiber opening. Therefore, there is room for improvement in terms of the resin impregnation properties of the glass cloth.

[0070] Patent document 6 states that yarns with thin filament diameters have poor mechanical strength compared to yarns with thick filament diameters, are prone to fuzzing, and need to be opened under relatively mild conditions. In addition, patent document 6 states that fuzzing and voids occur in uneven portions (uneven portions) of yarn width, and further states that by controlling the twist count, sizing agent, tension in the weaving process, etc. of the glass filaments, the fuzzing and voids can be reduced. However, patent document 6 only shows the effect of glass cloths with a thickness of less than 20 μm. The research results of the present inventors show that glass cloths with a thickness exceeding 20 μm have room for improvement in terms of fuzzing and voids (resin impregnation). In addition, patent document 6 only lists E glass, T glass, S glass, UT glass, D glass, NE glass, and L glass as glass types. The research results of the present inventors show that quartz glass with lower dielectric properties has room for improvement in terms of fuzzing and voids (resin impregnation).

[0071] Patent Documents 4 and 5 describe glass cloth opening techniques based on water pressure, such as water jets, and glass cloth opening techniques based on ultrasound. Opening the glass cloth can reduce voids and improve resin impregnation. However, research by the present inventors has shown that glass cloth containing a high SiO2 content in the glass that makes up the glass yarn has lower mechanical strength than other glass types. Therefore, even glass cloth thicker than 80 μm, which is comparable to glass cloth previously studied and applied under mild opening conditions, is susceptible to fuzzing using the conventional opening methods described in Patent Documents 4 and 5. Furthermore, it is clear that quartz glass is difficult to open under mild opening conditions due to its high hardness. Consequently, fuzzing and voids occur not only in areas with uneven yarn widths, but also in areas with less uneven yarn widths.

[0072] As an alternative to physical processing, Patent Document 7 describes a method for improving resin impregnation by using yarn with a larger filament diameter and reducing the weave density to reduce interlacing points and smooth the surface. However, the present inventors' research revealed that there is room for improvement in terms of fuzzing and resin impregnation.

[0073] In contrast, according to the application, it is possible to provide the glass yarn that uses silicon dioxide (SiO 2 ) content is high and suppress the glass cloth that fuzzing occurs and the prepreg and printed circuit board (PCB) etc. that comprise it.The glass cloth of the application is because of silicon dioxide (SiO 2 ) content is high and can improve the dielectric properties (such as reducing dielectric loss tangent) of prepreg and PCB. In addition, in a preferred embodiment, the glass cloth of the application has excellent resin impregnation, therefore, can improve the heat resistance of the composite, i.e. prepreg and PCB, of itself and matrix resin.

[0074] While not being bound by theory, the present inventors conducted extensive research on suppressing fuzzing in glass cloth using quartz glass as glass yarn. Since warp yarns are less prone to opening than weft yarns, the inventors focused on the number of filament segments in the warp yarn bundle (the number of warp segments). They discovered that controlling this number within a specified range can suppress fuzzing. As described in detail below, reducing the number of warp segments relative to the thickness can suppress fuzzing. Furthermore, they conducted extensive research on suppressing fuzzing and improving resin impregnation in glass cloth using quartz glass as glass yarn. Since warp yarns are less prone to opening than weft yarns, the inventors focused on the bonding ratio between filaments in the warp yarn bundle. They discovered that controlling the number of filament segments in the warp yarn bundle (the number of warp segments) and the bonding ratio between filaments within specified ranges can suppress fuzzing and improve resin impregnation. Lowering the warp bonding ratio improves resin impregnation. Furthermore, the improvement in resin impregnation contributes to the improvement in the heat resistance of the prepreg and the printed wiring board.

[0075] While not limited to a specific production method, preferred methods for controlling the number of warp yarn bundles within a specified range include: using yarns with filament diameters larger than the thickness of the glass cloth; reducing the number of filaments; flattening the yarn bundles during warping and then applying sizing (sizing); and washing the glass cloth with water at a specified temperature or higher before heat-deoiling the glass cloth. Furthermore, while not limited to a specific production method, preferred methods for controlling the number of warp yarn bundles and the warp yarn bonding ratio within specified ranges include: in addition to the above methods, ultrasonically washing the sizing agent combustion residue and performing fiber-opening treatment before surface-treating the glass cloth; and controlling the conveying speed of the glass cloth to a specified speed or lower.

[0076] 〔Glass yarn〕

[0077] The glass yarn constituting the glass cloth is obtained from glass having a Si content in the range of 95.0% to 100% by mass, as calculated as SiO2. The use of such glass yarn can improve the dielectric properties of the resulting glass cloth. The Si content in the range of 98.0% to 100% by mass, as calculated as SiO2, is preferably in the range of 99.0% to 100% by mass, more preferably 99.5% to 100% by mass, and particularly preferably 99.9% to 100% by mass.

[0078] The average filament diameter of the glass filaments constituting the glass yarn (also referred to as "filament diameter") is preferably 4.0 μm or more and 11.0 μm or less. The lower limit of the filament diameter is more preferably 4.5 μm or more, further preferably 5 μm or more, and particularly preferably 5.5 μm or more. The upper limit of the filament diameter that can be combined with these lower limits is more preferably 10.0 μm or less, and further preferably 9.5 μm or less. In addition, in order to satisfy formula (A1), although it also depends on the number of filaments, the filament diameter is preferably 5.0 μm or more, more preferably 5.5 μm or more, and particularly preferably 6.0 μm or more. If the filament diameter is above the above lower limit, the breaking strength of the filament becomes higher, and therefore, the resulting glass cloth is less likely to fuzz. If the filament diameter is below the above upper limit, the mass of the glass cloth becomes smaller, and therefore, it is easy to carry or process. In addition, if the filament diameter is within the above range, it is easy to obtain the effects of suppressing fuzzing and improving resin impregnation. In this application, the term "average filament diameter" (or "filament diameter") refers to the average filament diameter (D) of the filaments constituting the warp yarns alone. MD ) or the average filament diameter of the filaments constituting the weft yarn only (D TD ), not the average filament diameter (D) obtained by combining the warp and weft yarns.

[0079] The average filament diameter (D) is calculated as follows: MD ) and the average filament diameter of the weft yarn (D TD ) and the value calculated.

[0080] D=(D MD +D TD ) / 2

[0081] The average filament diameter (D) is preferably 4.0 μm or more and 11.0 μm or less. The lower limit of the average filament diameter (D) is preferably 4.0 μm or more, more preferably 4.5 μm or more, further preferably 5 μm or more, and particularly preferably 5.5 μm or more. The upper limit of the filament diameter (D) that can be combined with these lower limits is more preferably 10.0 μm or less, and further preferably 9.5 μm or less. In addition, in order to satisfy formula (A1), although it also depends on the number of filaments, the filament diameter (D) is preferably 5.0 μm or more, more preferably 5.5 μm or more, and particularly preferably 6.0 μm or more. If the filament diameter (D) is above the lower limit, the breaking strength of the filament becomes higher, and therefore, the resulting glass cloth is less likely to fuzz. If the filament diameter (D) is below the upper limit, the mass of the glass cloth becomes smaller, and therefore, it is easy to carry or process. In addition, if the filament diameter (D) is within the above range, it is easy to obtain the effects of suppressing fuzzing and improving resin impregnation.

[0082] The average number of glass filaments constituting the glass yarn (also referred to as "filament number") is preferably 10 to 250, more preferably 15 to 200, further preferably 18 to 150, and particularly preferably 20 to 120. By making the number of filaments 10 or more, there is a tendency to suppress yarn breakage. In addition, if the average number of filaments of the glass filaments is within the above range, it is easy to obtain the effects of suppressing fuzzing and improving resin impregnation. In particular, in order to satisfy formula (A1), although it also depends on the filament diameter, it is preferred to set the number of filaments of the glass yarn used in the warp yarn to be 150 or less, more preferably to be 120 or less, and particularly preferably to be 100 or less. In the present application, the average number of filaments is the average value of the filaments of the glass yarn constituting only the warp yarn or the average value of the filaments of the glass yarn constituting only the weft yarn, and is not the average value obtained by combining the warp yarn and the weft yarn.

[0083] 〔Weaving structure, etc〕

[0084] Glass cloth is composed of glass yarns containing multiple glass filaments as warp and weft yarns. Examples of the weaving structure of glass cloth include plain weave, basket weave, satin weave, and twill weave. Among them, plain weave is preferred.

[0085] The weaving density of the warp and weft yarns constituting the glass cloth (weave density) is preferably 10 to 120 yarns / inch (= 10 to 120 yarns / 25.4 mm), more preferably 40 to 120 yarns / inch. When the weaving density is within this range, the effects of suppressing fuzzing and improving resin impregnation are easily achieved.

[0086] The weight per unit area of the glass cloth (mass of the glass cloth) is preferably 8 g / m 2 ~90g / m 2 , more preferably 8g / m 2 ~80g / m 2 , more preferably 8g / m 2 ~70g / m 2 , particularly preferably 8g / m 2 ~60g / m 2 When the weight per unit area of the glass cloth is within the above range, the effects of suppressing fuzzing and improving resin impregnation properties are easily obtained.

[0087] The thickness (T) of the glass cloth is greater than 0 μm and less than 80 μm. The upper limit of the thickness (T) is preferably less than 60 μm, more preferably less than 55 μm, and even more preferably less than 50 μm. When the thickness of the glass cloth is within this range, the effects of suppressing fuzzing and improving resin impregnation are easily achieved. The lower limit of the thickness (T) of the glass cloth that can be combined with these upper limits is preferably 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more.

[0088] 〔Number of warp yarn segments〕

[0089] The thickness (T) of the glass cloth and the number of warp yarn segments (N) satisfy the following equation (A1). When the thickness of the glass cloth and the number of warp yarn segments satisfy this equation (A1), the warp yarns have fewer overlapping filaments than the thickness, resulting in uniform unevenness on the glass cloth surface and within the yarn bundles, which can suppress fuzzing. Furthermore, the warp yarns have fewer gaps formed by overlapping filaments than the thickness, improving resin impregnation.

[0090] {Number of warp yarn segments (N) - 0.2} / T [μm] < 0.056…(A1)

[0091] Glass cloth is difficult to open due to the tension applied to the warp yarns during transport. This makes it more prone to unevenness and voids in the yarn bundles than the weft yarns. Consequently, fuzz and voids are more likely to form. Therefore, adjusting the number of warp yarn segments is effective in suppressing fuzz and improving resin impregnation.

[0092] The number of warp yarn segments (N) is calculated by the warp yarn width [μm] and the warp yarn filament diameter (D MD ) [μm], and the number of warp filaments [pieces].

[0093] Number of warp yarn segments (N) = warp yarn filament diameter (D MD )[μm]×number of warp filaments[pieces]÷warp width[μm]

[0094] Here, it is preferred that formula (A1) is more easily satisfied by setting the filament diameter to be large, setting the number of filaments to be small, flattening the yarn bundle before sizing in warping, and washing the sizing agent with water at 50°C or above before heating and deoiling the glass cloth.

[0095] The relationship between the thickness (T) (μm) of the glass cloth and the number of warp yarn segments (N) preferably satisfies formula (A2), more preferably satisfies formula (A3), further preferably satisfies formula (A4), and particularly preferably satisfies formula (A5).

[0096] {N-0.2} / T[μm]<0.054…(A2)

[0097] {N-0.2} / T[μm]<0.052…(A3)

[0098] {N-0.2} / T[μm]<0.050…(A4)

[0099] {N-0.2} / T[μm]<0.048…(A5)

[0100] 〔Warp bonding ratio〕

[0101] The warp bonding ratio is a value calculated from the number of warp filaments and the number of bonding points of the filaments bonded to each other, as described below.

[0102] Warp bonding ratio = number of bonding points of filaments bonded to each other in the warp yarn / number of filaments in the warp yarn

[0103] The number of bonding points is measured as detailed in the Examples section by embedding a glass cloth in epoxy resin, curing the epoxy resin, and then observing a cross-section of the glass cloth. The warp bonding ratio of the glass cloth of the present application, calculated using the above formula, is preferably greater than 0 and less than 0.80. The warp bonding ratio is more preferably greater than 0 and less than 0.70, and even more preferably greater than 0 and less than 0.60.

[0104] Glass cloth with a warp bonding ratio less than a specified value is less likely to hinder the resin from penetrating between the multiple filaments, thus achieving good resin impregnation. Here, in order to control the warp bonding ratio and formula (A1) in a manner that simultaneously satisfies the above-mentioned filament diameter and number adjustment, yarn bundle flattening, and sizing agent cleaning, for example, prior to surface treatment of the glass cloth, ultrasonic cleaning of sizing agent combustion residue and fiber opening treatment can be used; and the number of filament bonding points can be controlled by controlling the conveying speed of the glass cloth to below a specified speed.

[0105] In the above formula, "filaments bonded to each other" also includes any of the following situations: a glass filament is in contact with other glass filaments; a surface-treated layer in a glass filament is in contact with other glass filaments; and a surface-treated layer in a glass filament is in contact with a surface-treated layer in other glass filaments.

[0106] The "epoxy resin" used in measuring the warp yarn bonding ratio is a resin that can be used to calculate the bonding ratio according to the present invention. More specifically, the resins described in the Examples are used. If such resins are not available, epoxy resins that cure in a static state are used.

[0107] Figure 1(a) and (b) are SEM images used to illustrate the calculation method of the "bonding ratio" in this application. In the figure, the epoxy resin is represented by black, and the cross section of the filament is represented by a white circle.

[0108] Figure 1 In (a), the portion indicated by arrow a1 corresponds to the bonding point between the filaments, and the portion indicated by arrow a2 does not correspond to the bonding point. Here, when observing the cross section of the glass cloth at a magnification of 2000x using a scanning electron microscope, the portion where the cross sections of the filaments (i.e., the white circles representing the cross sections of the filaments on the SEM photograph) are in contact for 50 nm or more is defined as a "bonding point."

[0109] The "total number of filaments" and "number of bonding points" in this application are counted based on the filaments whose cross sections are completely within the observed image. Filaments whose cross sections are not visible in the observed image and the bonding points provided by such filaments are not counted in the "total number of filaments" and "number of bonding points". Figure 1 Taking (b) as an example, the total number of filaments whose cross sections all fall within the observation image is 30 (refer to the numbers in white), and the total number of bonding points between such filaments is 18 (refer to the "×" mark). Filaments that cannot be observed in the observation image are not counted as "total number of filaments" and "number of bonding points". Figure 1 In the example of (b), the bonding ratio is calculated to be 18 / 30=0.6.

[0110] In addition, the glass cloth preferably has the warp yarn bonding ratio exceeding 0 and not more than 0.80 when averaged over a plurality of cross sections, and may have cross sections partially not meeting the range of the warp yarn bonding ratio.

[0111] 〔Filament diameter and glass cloth thickness〕

[0112] Glass cloth preferably uses glass yarn having a diameter larger than the thickness of the glass cloth, for example, glass yarn having a filament diameter larger than that specified in the IPC standard. More specifically, when the thickness of the glass cloth is 20 μm or more and 80 μm or less, the average filament diameter (D) (μm) of the glass yarn constituting the glass cloth and the thickness (T) (μm) of the glass cloth preferably satisfy the following formula (B1), more preferably the following formula (B2), and particularly preferably the following formula (B3), (B4), or (B5). When the thickness of the glass cloth is less than 20 μm, the following formula (B6) is preferably satisfied, more preferably the following formula (B7), and particularly preferably the following formula (B8) or (B9).

[0113] 24×DT>96…(B1)

[0114] 24×DT>98…(B2)

[0115] 24×DT>100…(B3)

[0116] 24×DT>104…(B4)

[0117] 24×DT>108…(B5)

[0118] 14×DT>46…(B6)

[0119] 14×DT>48…(B7)

[0120] 14×DT>50…(B8)

[0121] 14×DT>52…(B9)

[0122] Thereby, the strength per filament becomes higher than the thickness of the glass cloth, and the occurrence of fuzzing can be suppressed.

[0123] 〔Filament diameter and number of filaments〕

[0124] Glass cloth preferably uses glass yarn with a filament diameter thicker than the thickness of the glass cloth and a smaller number of filaments. As long as the number of warp yarn segments satisfies formula (A1), the filament diameter and the number of roots are not particularly limited. It is preferred that: regarding the number of filaments when the filament diameter is thickened, the TEX of the glass yarn is made to be the same as before, for example, the TEX specified in the IPC standard is the same, or the cross-sectional area of the glass yarn (cross-sectional area of 1 filament × number of filaments) is made to be the same as before, for example, the cross-sectional area of the yarn species specified in the IPC standard. The same degree here means that a difference of ±30% or ±20% is allowed. In this way, a sufficient weave density can be ensured relative to the thickness, and problems such as mesh deviation are less likely to occur.

[0125] 〔Silane coupling agent〕

[0126] From the viewpoint of improving resin impregnation, the glass yarn (including glass filaments) constituting the glass cloth is preferably surface-treated with a surface treatment agent. The surface treatment agent for the glass yarn preferably includes a silane coupling agent. As the silane coupling agent, for example, a silane coupling agent represented by the following formula (C) is preferably used.

[0127] X(R) 3-n SiE n …(C)

[0128] {In formula (C), X is an organic group having at least one of an unsaturated double bond group having free radical reactivity and an amino group, wherein the unsaturated double bond group having free radical reactivity is, for example, a carbon-carbon double bond having free radical reactivity, Y is each independently an alkoxy group, n is an integer from 1 to 3, and R is a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.}

[0129] As the reason why the dielectric loss tangent of the glass cloth increases, it is considered that:

[0130] (i) a very small amount of thermally oxidized degraded products of the sizing agent remaining in a state of being physically attached to the surface of the glass filaments; and

[0131] (ii) Residues of the surface treatment agent or its modified products that do not form a chemical bond with the glass surface but are physically attached and cannot be removed by water-based cleaning.

[0132] From the perspective of suppressing the generation of (i) thermal oxidative degradation products and / or (ii) residues or modified products, X in formula (C) is preferably an organic group that does not form a salt with an ionic compound. Furthermore, from the perspective of reactivity with the matrix resin, X in formula (C) is more preferably an organic group having one or more methacryloyloxy groups or acryloyloxy groups.

[0133] Regarding Y in the above formula (C), an alkoxy group is preferably an alkoxy group having 1 to 5 carbon atoms (1, 2, 3, 4 or 5 carbon atoms) for stabilization of the glass cloth.

[0134] As the surface treatment agent, the silane coupling agent represented by formula (C) may be used alone or in combination with two or more silane coupling agents having different Xs in formula (C). Examples of the silane coupling agent represented by formula (C) include vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 5-hexenyltrimethoxysilane, and mixtures thereof.

[0135] The molecular weight of the silane coupling agent is preferably 100 to 600, more preferably 150 to 500, and even more preferably 200 to 450. Among these, it is particularly preferred to use two or more silane coupling agents having different molecular weights. By treating the surface of the glass yarn with two or more silane coupling agents having different molecular weights, the density of the treating agent on the glass surface tends to increase, further enhancing reactivity with the matrix resin.

[0136] From the perspective of minimizing reactivity with resins, nonionic silane coupling agents are preferably nonionic. Among nonionic silane coupling agents, those having at least one group selected from the group consisting of vinyl, methacryloxy, and acryloxy groups are preferred, with those having at least one methacryloxy or acryloxy group being particularly preferred. Since reactivity with resins is not impaired, the heat resistance and reliability of printed circuit boards can be improved.

[0137] In one embodiment, in formula (C), X is an organic group having at least one of the unsaturated double bond group and the amino group. Therefore, not only embodiments in which X has both the unsaturated double bond group and the amino group, but also embodiments in which X has the unsaturated double bond group but does not have the amino group, and embodiments in which X does not have the unsaturated double bond group but has the amino group also fall within the scope of formula (C). X in formula (C) is preferably the unsaturated double bond group, and preferably does not contain an amino group.

[0138] 〔Loss on ignition〕

[0139] The ignition loss value of the glass cloth is preferably in the range of 0.01% to 0.30% by mass. It is more preferably in the range of 0.02% to 0.26% by mass, further preferably in the range of 0.03% to 0.22% by mass, even more preferably in the range of 0.03% to 0.18% by mass, and particularly preferably in the range of 0.03% to 0.16% by mass. Although it also depends on the thickness of the glass cloth, if the ignition loss value is 0.30% or less, the amount of silane coupling agent chemically bonded to the surface of the glass yarn will not become excessive. In this case, the dielectric loss tangent of the glass cloth and, in turn, the dielectric loss tangent of the resulting printed circuit board will tend to decrease. In addition, if the ignition loss value is 0.01% or more by mass, the heat resistance of the resulting printed circuit board will not deteriorate easily.

[0140] Manufacturing Method of Glass Cloth

[0141] The manufacturing method of the glass cloth of the present application includes the steps of weaving glass yarns comprising a plurality of filaments and having a Si content in the range of 95.0% to 100% by mass, calculated as SiO2, as warp and weft yarns to obtain the glass cloth (weaving step). The method further includes: a warping step in which the glass yarns are straightened and flattened before the weaving step, and then coated with a sizing agent; a step of washing the glass yarns before heat deoiling with water at 50°C or higher after the warping step and before, during, or after the weaving step (pre-heat deoiling washing step); and a step of heat deoiling the glass yarns (heat deoiling step). Thus, the number of warp yarn segments and the thickness of the glass cloth can be adjusted so that they satisfy formula (A1), thereby providing quartz glass cloth with less fuzz. The method may further include the steps of washing and opening the washed and heat deoiled glass yarns while conveying them at a speed of 50 m / min or less in a liquid irradiated with ultrasonic waves (washing and opening step). Thus, the number of warp yarn bundles and the thickness of the glass cloth can be adjusted so as to satisfy the formula (A1) and the warp yarn bonding ratio is below a predetermined value, thereby providing a quartz glass cloth with less fuzzing, excellent resin impregnation, and improved heat resistance of printed circuit boards and the like.

[0142] The above-mentioned glass processing method (cleaning process before heating and deoiling, heating and deoiling process and cleaning and fiber opening process) can be applied to glass yarn before weaving, and can also be applied to the woven glass cloth. In other words, the process of weaving glass yarn to obtain glass cloth can be set before the glass processing method, can be set during the process, and can also be set after. It should be noted that in the glass processing method, "reduction" refers to the purpose of removing at least a part of the sizing agent or silane coupling agent, for example, and there may be residues that are not completely removed. The following is an example of a method that includes a warping process, a weaving process, a cleaning process before heating and deoiling, a heating and deoiling process and a cleaning and fiber opening process in sequence. However, the manufacturing method of the glass cloth of the present application is not limited to this.

[0143] [Glass yarn warping process]

[0144] The warping process of glass yarn includes: using glass yarn with Si content in the range of 95.0% by mass to 100% by mass as converted by SiO2, and after flattening the yarn bundle, sizing the glass yarn is performed. Through this treatment, sizing is performed in a state where the yarn width is widened, thereby easily widening the yarn width in the state of glass cloth after weaving, and the number of warp yarn bundles and the thickness of the obtained glass cloth can be controlled in a manner that satisfies formula (A1), and fuzzing can be suppressed. That is, the surface of the glass cloth and the unevenness in the yarn bundle are suppressed, and fuzzing is not easy. There is no special limitation on the flattening method of the glass yarn bundle, and methods such as processing under roller pressure can be listed. From the viewpoint of suppressing fuzzing and flattening the yarn bundle, the pressure is preferably 1.0 kg / cm 2 ~6.0kg / cm 2 , more preferably 2.0 kg / cm 2 ~5.0kg / cm 2 , more preferably 2.5kg / cm 2 ~5.5kg / cm 2 In addition, this warping step facilitates the removal of the paste in the cleaning step before the heating and deoiling process described later.

[0145] 〔Glass cloth weaving process〕

[0146] During the weaving process of glass cloth, a loom can be used to weave glass yarn with a Si content ranging from 95.0% to 100% by mass (calculated as SiO2) into the warp yarn prepared by the glass yarn warping process. This allows the production of glass cloth fabrics, for example, as plain-woven fabrics. To suppress fuzzing during spinning and warping, the glass yarn used in the glass cloth fabric is preferably surface-treated with a sizing agent primarily composed of starch, polyvinyl alcohol, or the like. It should be noted that, in this application, "glass cloth fabric" refers to glass cloth before it is heated and deoiled.

[0147] The glass yarn used in the above-mentioned steps, i.e., the warping step of the glass yarn and the weaving step of the glass cloth, is preferably a glass yarn having a diameter thicker than the thickness of the obtained glass cloth, for example, a glass yarn having a filament diameter thicker than the filament diameter specified in the IPC standard. More specifically, depending on the target thickness of the glass cloth, it is preferred to use a glass yarn having a filament diameter that satisfies at least one of the above-mentioned formulas (B1) to (B9). This makes it easy to suppress the occurrence of fuzzing and improve resin impregnation. Furthermore, the glass yarn used in the above-mentioned steps is preferably such that the TEX or cross-sectional area of the glass yarn is at a conventional level, for example, the TEX or cross-sectional area specified in the IPC standard, compared to the thickness of the obtained glass cloth. This ensures a sufficient weave density compared to the thickness, and makes it less likely that problems such as mesh deviation will occur.

[0148] [Cleaning process before heating and degreasing]

[0149] The pre-heat deoiling cleaning step includes a step of reducing the amount of adhesive by cleaning the glass cloth before heat deoiling with water at 50°C or higher. This reduces adhesion between the adhesive in the filaments and the residue from the combustion of the adhesive during heat deoiling, and allows the number of warp strands and the thickness of the resulting glass cloth to satisfy Formula (A1). Furthermore, it facilitates fiber opening of the glass cloth so that the warp adhesion ratio is below a predetermined value. From the perspective of cleaning efficiency, the cleaning solvent used in this treatment is preferably water, and the temperature is preferably 50°C or higher. Using water at 50°C or higher allows the amount of adhesive necessary to protect the glass yarn until the heat deoiling step to remain, while any excess adhesive is washed away. The water temperature is preferably 50°C or higher and below 100°C. The lower limit of the water temperature is more preferably 55°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher. The upper limit of the water temperature, which can be combined with these lower limits, is more preferably 95°C or lower, and even more preferably 90°C or lower. The solvent used for cleaning is not particularly limited. From the perspective of safety and cost, cleaning using water, reverse osmosis (RO) water, ion-exchanged water, etc. is preferred. The cleaning method for the glass cloth is not particularly limited. For example, ultrasonic methods (such as methods using ultrasonic oscillators), spray-based injection (such as injection based on high-pressure spray), steam spray, etc. can be considered. From the perspective of being able to process inexpensively, the following method is preferred: after immersing the glass cloth in a tank filled with a cleaning solution, using a squeeze roller to remove excess cleaning solution, and then drying the glass cloth. In this case, the immersion time can be, for example, 2 seconds or more, 5 seconds or more, 10 seconds or more, or 15 seconds or more and 120 seconds or less, 90 seconds or less, 60 seconds or less, or 45 seconds or less.

[0150] [Sizing agent reduction process (heating and deoiling process)]

[0151] The step of reducing the sizing agent may include, for example, a degumming step (heating and deoiling step) of heating the glass cloth at a temperature of 600°C to 1600°C. This facilitates the reduction of the sizing agent from the glass. By reducing the amount of thermally oxidized degraded sizing agent remaining physically attached to the glass surface, the increase in the dielectric loss tangent of the resulting glass cloth can be easily and effectively suppressed.

[0152] In the method for thermal degreasing of a glass cloth, the glass cloth can be thermally degreasing at a temperature of 600°C or higher. This makes it easier to reduce the dielectric loss tangent of the resulting glass cloth. The thermal degreasing temperature is preferably 600°C or higher and 1600°C or lower, more preferably 800°C or higher and 1300°C or lower, and even more preferably 900°C or higher and 1100°C or lower. If the thermal degreasing temperature is 600°C or higher, it is easier to fully remove the paste residue and the like adhering to the glass cloth after thermal degreasing, thereby easily reducing the dielectric loss tangent of the glass cloth. On the other hand, if the thermal degreasing temperature is 1500°C or lower, it is easier to suppress the devitrification of the glass, which can effectively prevent the strength of the glass cloth from decreasing.

[0153] The heating time can be appropriately selected, preferably from 1 second to 10 minutes. The upper limit of the heating time is more preferably 5 minutes or less, even more preferably 2 minutes or less, and particularly preferably 90 seconds or less. To facilitate high-temperature heating, a heating time of 10 minutes or less minimizes damage to the glass cloth, making problems such as localized hole formation or breakage during processing less likely to occur. To effectively remove paste residue, the lower limit of the heating time, which can be combined with these upper limits, is more preferably 5 seconds or more, 10 seconds or more, or 15 seconds or more.

[0154] As for the means for heating the glass cloth, as long as the heating is performed in a manner such that the degreasing temperature is within the range of 600°C to 1600°C, known heating methods, heating media, heating mechanisms, heating devices, and heating components can be used. Heating means include, for example, (1) heating the glass cloth in a heating furnace; (2) bringing the glass cloth into contact with a heating portion; or (3) blowing high-temperature steam onto the glass cloth. By heating the glass cloth in a manner such that the degreasing temperature is above 600°C, organic matter attached to the surface of the glass cloth can be efficiently removed or the time required to remove the organic matter can be shortened. The heating of the glass cloth can be performed sequentially or continuously in a closed system or an open system, or a closed system and an open system can be combined.

[0155] In the case of a closed system, from the perspective of suitable heating by the heating means, it is preferred to place the glass cloth in a heating furnace, and / or, from the perspective of storage space and heating range, it is preferred to heat the glass cloth while storing it in a rolled state. Furthermore, from the perspective of improving the removal efficiency of organic matter or shortening the removal time of organic matter, it is also preferred to heat the glass cloth while conveying it in a heating furnace.

[0156] In the case of an open system, it is preferred to heat the glass cloth while conveying it from the viewpoint of the heated area. The glass cloth can be conveyed by, for example, a roll-to-roll method using a take-up mechanism and a roll-out mechanism.

[0157] (Heating furnace)

[0158] As a heating method for the heating furnace, various methods such as electric heaters and burners can be considered as long as they can heat the heating deoiling temperature to 600°C to 1600°C, and are not limited to any specific method. In addition, a combination of multiple methods can be used for heating, and preferably a gas single radiant tube burner or an electric heater is used.

[0159] From the perspective of heating efficiency, the heating furnace preferably has a means for exhausting the gases generated within the furnace and / or an air circulation means. Examples of the gas exhaust means include nozzles, gas pipes, small holes, degassing valves, etc. Examples of the air circulation means include blades, air conditioning equipment, etc.

[0160] To efficiently remove organic matter adhering to the surface of the glass cloth, a continuous method in which the glass cloth is continuously passed through a heating furnace and heated is preferred over an intermittent method in which the glass fiber fabric is wound onto a winding core and then heated at a predetermined ambient temperature. Furthermore, a method that allows continuous cleaning of the glass cloth (glass cloth) prior to heating and degreasing is particularly preferred.

[0161] (Contact member for heating glass cloth)

[0162] As a method for heating the glass cloth, the above-mentioned heating furnace can be used. From the viewpoint of low running cost, the glass cloth can be heated by bringing a member heated to a predetermined temperature into contact with the glass cloth.

[0163] The shape of the contact member is not particularly limited as long as the glass cloth can be heated to a deoiling temperature within the range of 600°C to 1600°C. A roller shape is preferred for ease of handling the glass cloth. A roller that can be used in a high-temperature range and has minimal temperature variation across the width, heated by induction heating, is preferred. When the glass cloth is heated by the contact member, the temperature of the contact member is generally equal to the surface temperature of the glass cloth.

[0164] In order to remove carbides adhering to the heating roller as the glass cloth is continuously heated, the heating roller method is preferably a method including a mechanism such as a scraper to remove the adhering foreign matter.

[0165] (Method of applying high-temperature steam to glass cloth (steam application method))

[0166] The steam applied to the glass cloth can include, for example, volatile solvents, water vapor, and gases other than water vapor. Water vapor is preferred from the perspective of toxicity to the human body and the ease with which it promotes the decomposition of the sizing agent used in the glass fiber. Regarding the temperature of the high-temperature steam, in order to achieve a surface temperature of the glass cloth within the range of 600°C to 1600°C, a method that can supply high-temperature steam and heated air in any proportion can be used, if necessary. The temperature of the high-temperature steam is 500°C or higher, preferably 600°C or higher, more preferably 700°C or higher, even more preferably 800°C or higher, and particularly preferably 900°C or higher. The steam application method is not limited and can be spraying, shower diffusion, or jet nozzles. Alternatively, the gas exhausted from the heating furnace is sometimes reused as high-temperature steam.

[0167] (Heating and deoiling device for glass cloth)

[0168] As described above, the heating and deoiling device for glass cloth can heat the glass cloth so that the deoiling temperature is within the range of 600° C. to 1600° C. More specifically, the heating and deoiling device for glass cloth preferably includes a heating furnace having a reeling mechanism and a reeling mechanism, and capable of performing a process of heating the glass cloth while conveying the glass cloth so that the deoiling temperature is within the range of 600° C. to 1600° C.

[0169] The unwinding mechanism and the winding mechanism may be, for example, at least a pair of rollers, a roll-to-roll system, etc. The heating furnace, air circulation means, contact member, and steam application means are as described in the above-mentioned heating treatment step of the glass cloth.

[0170] From the viewpoint of production efficiency, it is preferred to include a cleaning device for washing off the sizing agent on the glass cloth immediately before the heating furnace.

[0171] [Glass cloth opening process]

[0172] The fiber-opening process of the glass cloth after heat deoiling includes the step of performing fiber-opening treatment on the glass cloth in such a manner that the number of warp yarn segments and the thickness of the obtained glass cloth satisfy the formula (A1) and the warp yarn bonding ratio becomes less than a specified value. This fiber-opening treatment can improve the impregnation of the resin into the glass cloth. Examples of such fiber-opening treatments include fiber-opening treatments that apply water flow pressure to the glass cloth; fiber-opening treatments based on high-frequency vibration using water (such as degassed water, ion exchange water, deionized water, electrolyzed cationic water or electrolyzed anionic water, etc.) as a medium; processing treatments under roller pressure, etc. This fiber-opening treatment can be performed simultaneously with weaving or after weaving. It can be performed before or after heat deoiling or simultaneously with heat deoiling, and can also be performed simultaneously with or after the surface treatment process.

[0173] From the perspective of controlling the number of warp bundles and the warp bond ratio of a glass cloth having a thickness of 80 μm or less, composed of glass yarns having relatively large filament diameters, i.e., those satisfying any of the above equations (B1) to (B9), within a specified range, the above-mentioned fiber-spreading step is preferably a step in which the glass cloth is washed and fiber-spread while being conveyed in a liquid, after the heat deoiling step and before the surface treatment step. Furthermore, the conveying speed of the glass cloth during this treatment is preferably 50 m / min or less. Glass yarns with large filament diameters are difficult to spread, and glass yarns with high hardness, such as quartz glass, are particularly difficult to spread. By washing and fiber-spreading the glass cloth after the heat deoiling step and before the surface treatment step, the combustion residue from the heat deoiling can be cleaned and removed, preventing the combustion residue from acting as an adhesive and causing adhesion between the filaments. Furthermore, by performing fiber-spreading before the surface treatment, adhesion between the filaments during the surface treatment step can also be prevented. Thus, the warp bond ratio of the glass cloth can be controlled so that it falls within a specified range, thereby improving resin impregnation. The fibers are not simply opened by strong processing force, but can be opened easily, so pilling is less likely to occur.

[0174] The cleaning and fiber-opening step of the glass cloth is preferably a step of irradiating the glass cloth in a liquid after the heat deoiling step and before the surface treatment step to primarily wash away combustion residues from the heat deoiling and perform fiber-opening (ultrasonic cleaning). The treatment is preferably performed while conveying the glass cloth in a roll-to-roll manner in a liquid irradiated with ultrasonic waves using an ultrasonic oscillator.

[0175] As the liquid used in ultrasonic cleaning, water or organic solvent can be used, but from the viewpoint of safety and protection of the global environment, it is preferred to use a liquid with water as the main component. In order to improve the efficiency of cleaning, the liquid used in cleaning can also be added with a surfactant or a pH adjusting agent.

[0176] The temperature of the liquid used in ultrasonic cleaning is not particularly limited, but is preferably 5° C. or higher from the viewpoint of improving the cleaning effect. Furthermore, from the viewpoint of safety, the temperature of the liquid used in cleaning is preferably 60° C. or lower.

[0177] The glass cloth can be cleaned by irradiating the glass cloth with ultrasonic waves in the liquid by running the glass cloth in a liquid irradiated with ultrasonic waves by an ultrasonic oscillator. The line tension acting on the warp yarn in the cleaning step is preferably 30N to 500N / 1m.

[0178] Ultrasonic cleaning can be performed using ultrasonic waves with a frequency of 20 kHz to 200 kHz. The ultrasonic frequency is preferably 20 kHz to 50 kHz, more preferably 20 kHz to 30 kHz. Ultrasonic waves with a frequency of 20 kHz to 200 kHz are preferred because they can be cleaned without causing significant defects such as mesh warping of the glass cloth.

[0179] Ultrasonic cleaning can preferably use an output power of 0.07W / cm 2 Above 3.60W / cm 2 The more preferred range of ultrasonic output power is 0.14 W / cm 2 Above and 2.16W / cm 2 Below, the further preferred range is 0.21W / cm 2 Above 1.44W / cm 2 Below. Ultrasonic output power is 0.07W / cm 2 When the ultrasonic output power is 3.60W / cm 2 When the amount is less than 50%, the mesh does not bend and uniform cleaning can be performed, which is preferred.

[0180] The conveying speed of the glass cloth during ultrasonic cleaning is preferably 50 m / min or less, more preferably 40 m / min or less, and particularly preferably 30 m / min or less. A conveying speed of 50 m / min or less allows for efficient cleaning and fiber-opening of the glass cloth or its intermediate, making it easier to control the number of warp yarn segments and the warp yarn bonding ratio within the specified range. Furthermore, this is preferred because it can suppress fuzzing and mesh shifting caused by damage during transport.

[0181] In the liquid used for ultrasonic cleaning, air with nitrogen and oxygen as main components is usually dissolved therein, but the dissolved oxygen amount (weight ratio) is preferably more than 1ppm and less than 20ppm, more preferably more than 3ppm and less than 17ppm, and further preferably more than 4ppm and less than 14ppm. By managing the dissolved oxygen amount, it is possible to indirectly control the dissolved gas amount, and it is possible to control the degree to which the ultrasonic wave attenuates due to the dissolved gas. When the dissolved oxygen amount is more than 1ppm, fiber opening is uniformly implemented, so it is preferred. When the dissolved oxygen amount is less than 20ppm, good cleaning action can be given to fiber fabric, so it is preferred. When the dissolved oxygen amount is more than 1ppm and the scope is less than 20ppm, uniform and good fiber opening effect can be obtained, so it is preferred.

[0182] 〔Surface treatment process of glass cloth〕

[0183] The glass cloth manufacturing method of the present application may further include a step of surface-treating the glass cloth with a surface treatment agent. This step of attaching the surface treatment agent may include, for example, at least one of the following steps: a covering step of attaching the surface treatment agent to the glass surface; and a fixing step of fixing the surface treatment agent to the glass surface by heating and drying. This facilitates appropriate surface treatment of the glass.

[0184] Methods for attaching the surface treatment agent include: applying a treatment liquid containing the surface treatment agent to the glass cloth, or immersing the glass cloth in the treatment liquid. Methods for applying the treatment liquid to the glass through a covering process include: (a) immersing the glass in or passing it through a bath of the treatment liquid (hereinafter referred to as the "immersion method"); (b) applying the treatment liquid to the glass using a roll coater, die coater, or gravure coater. When the immersion method is used, the immersion time of the glass in the treatment liquid is preferably selected to be 0.5 seconds or longer and 1 minute or shorter. Furthermore, when the immersion method is used, the glass can be passed through the treatment liquid at a conveying speed of 10 to 50 m / min while applying a predetermined tension (e.g., 100 to 250 N). Furthermore, after the treatment liquid is applied to the glass, the solvent contained in the treatment liquid can be heated and dried using methods such as hot air or electromagnetic waves.

[0185] The concentration of the surface treatment agent contained in the treatment liquid is preferably 0.1 to 1.0 mass %, more preferably 0.1 to 0.8 mass %, and even more preferably 0.1 to 0.5 mass %. This facilitates more suitable surface treatment of the glass.

[0186] In the fixing step, the heating and drying temperature is preferably 80°C or higher, more preferably 90°C or higher, to fully promote the reaction between the surface treatment agent, such as the silane coupling agent, and the glass. Furthermore, to prevent degradation of the organic groups contained in the surface treatment agent, such as the silane coupling agent, the heating and drying temperature is preferably 300°C or lower, more preferably 180°C or lower.

[0187] 〔Fiber opening process after surface treatment〕

[0188] As a process for opening the glass filaments bonded by the surface treatment agent, methods such as opening the glass cloth using a water spray (high-pressure water opening), a vibrating washer, ultrasonic water, or a mangle can be used. During this opening process, the yarn width tends to be further increased by reducing the tension applied to the glass cloth. It should be noted that to suppress the occurrence of fuzzing in the glass cloth caused by the opening process, it is preferable to implement measures such as reducing friction with the contacting members during weaving of the glass yarn, optimizing the surface treatment agent, and increasing the amount of adhesion.

[0189] The steps described above do not necessarily need to be performed in separate processes; multiple steps can be combined into a single process. The composition of the glass cloth often remains unchanged before and after fiber opening. Furthermore, the glass cloth manufacturing method may include optional steps in addition to the above steps. For example, a slit processing step may be included after the fiber opening step. Furthermore, the order of the above steps may be reversed if possible.

[0190] The above-described method for producing glass cloth can increase the filament diameter to suppress fuzzing, adjust the number of warp yarn segments and the warp yarn bonding ratio to a predetermined range, and improve resin impregnation. The glass cloth of the present application can be used as a material for producing printed circuit boards, for example.

[0191] Prepreg

[0192] The prepreg of the present application comprises the glass cloth and a matrix resin impregnated into the glass cloth, thereby providing a prepreg with few voids.

[0193] As the matrix resin, a thermosetting resin or a thermoplastic resin can be used, and if possible, both can be used in combination, or other resins can be contained.

[0194] Examples of the thermosetting resin include:

[0195] (a) an epoxy resin obtained by reacting a compound having an epoxy group with a compound having at least one group selected from the group consisting of an amino group, a phenol group, an acid anhydride group, a hydrazide group, an isocyanate group, a cyanate group, and a hydroxyl group that reacts with the epoxy group, and curing the reaction;

[0196] (b) a radical polymerizable curable resin obtained by curing a compound having at least one group selected from the group consisting of an allyl group, a methallyl group, and an acryloyl group;

[0197] (c) a maleimide triazine resin obtained by reacting a compound having a cyanate group with a compound having a maleimide group and curing the resulting compound;

[0198] (d) reacting a maleimide compound with an amine compound to cure the resulting thermosetting polyimide resin;

[0199] (e) Benzoxazine resins obtained by crosslinking and curing a compound having a benzoxazine ring by heat polymerization.

[0200] It should be noted that when obtaining (a) the epoxy resin, the compounds can be reacted without a catalyst. Alternatively, the compounds can be reacted by adding a catalyst having reaction catalytic ability, such as an imidazole compound, a tertiary amine compound, a urea compound, or a phosphorus compound. Furthermore, when obtaining (b) the free radical polymerization curable resin, a thermal decomposition catalyst or a photodecomposition catalyst can be used as a reaction initiator.

[0201] Examples of thermoplastic resins include polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, aromatic polyamide, polyetheretherketone, thermoplastic polyimide, insoluble polyimide, polyamideimide, and fluororesin. As insulating materials for printed circuit boards for high-speed communications, polyphenylene ether or modified polyphenylene ether having high free radical reactivity is preferred.

[0202] When the matrix resin used in printed circuit boards for high-speed communications has vinyl or methacryloyl groups, silane coupling agents having high hydrophobicity and functional groups such as methacryloyl groups that participate in radical reactions have good compatibility with the matrix resin.

[0203] As mentioned above, thermosetting resins and thermoplastic resins can be used in combination. In addition, the prepreg may further contain an inorganic filler. The inorganic filler is preferably used in combination with the thermosetting resin, and examples thereof include aluminum hydroxide, zirconium oxide, calcium carbonate, aluminum oxide, mica, aluminum carbonate, magnesium silicate, aluminum silicate, silicon dioxide, talc, short glass fibers, aluminum borate, and silicon carbide. The inorganic filler can be used alone or in combination of two or more.

[0204] Printed Circuit Board

[0205] The printed circuit board of the present application comprises one or more of the above-mentioned prepregs. Specifically, the printed circuit board comprises the above-mentioned glass cloth and a cured product of a matrix resin composition impregnated into the glass cloth. The printed circuit board exhibits high adhesion to the resin and excellent dielectric properties.

[0206] Integrated Circuits and Electronic Devices

[0207] The present application also provides an integrated circuit and an electronic device including the printed circuit board. The integrated circuit and the electronic device obtained using the printed circuit board of the present application have excellent various properties.

[0208] Example

[0209] Examples and comparative examples of the present application will be described, but the present application is not limited to the following examples and comparative examples.

[0210] Measurement and Evaluation Methods

[0211] [Physical Properties of Glass Yarn and Glass Cloth]

[0212] The physical properties of the glass yarn and glass cloth, specifically, the number of filaments, the weaving density of the warp and weft yarns (weave density), the thickness of the glass cloth, and the ignition loss of the glass cloth were measured in accordance with JIS R3420.

[0213] 〔Average filament diameter of glass yarn〕

[0214] The cross sections of 30 glass yarn bundles at arbitrary positions of the glass yarns were observed using a scanning electron microscope, and the average value was calculated to determine the average filament diameter.

[0215] 〔Average number of filaments in glass yarn〕

[0216] The average number of filaments measured in accordance with JIS R3420 was calculated to determine the average number of filaments.

[0217] 〔Wave and weft yarn width〕

[0218] A camera with a field of view of approximately 2.3 × 1.7 mm and a resolution of 2.26 μm / pixel was used to scan the glass cloth in the MD or TD direction at 1 mm intervals. The average yarn widths of the warp and weft yarns of the glass cloth were determined. The average yarn widths were calculated using the yarn widths of at least 100 glass yarns.

[0219] 〔Calculation of warp bonding ratio〕

[0220] Glass cloth was embedded in epoxy resin (EPOMOUNT (trade name), curing agent II, manufactured by REFINETEC) and cured. The cross-section of the glass cloth, along with the resin, was cut and ground until the roundness of the glass filaments reached 0.9 or greater. The cross-section of the glass cloth was then observed at a magnification of 2000 times using a scanning electron microscope SU3500 manufactured by Hitachi High-Technologies Corporation. Each warp yarn was divided into three equal parts, and a total of five cross-sectional images were taken. The total number of filaments in each image and the number of bonding points where the cross-sections of the filaments were in contact by 50 nm or more were then visually counted. The warp yarn bonding ratio was calculated using the following formula.

[0221] Warp bonding ratio = number of bonding points of filaments bonded to each other in the warp yarn / number of filaments in the warp yarn

[0222] The same operation was repeated for the 15 sheets thus obtained, and the average value was defined as the warp bonding ratio.

[0223] [Evaluation method for fuzzing]

[0224] For glass cloth, a tension of 100N / 1000mm was applied using a roll-to-roll inspection table, and the tension per 1m was determined by visual inspection while irradiating with a halogen lamp. 2 The number of protrusions of 1 mm or more was measured and the fuzzing was evaluated according to the following criteria.

[0225] A: The number of raised hairs is less than 10

[0226] B: The number of raised hairs is 11 or more and 30 or less

[0227] C: The number of raised fibers is 31 or more and 60 or less

[0228] D: The number of raised hairs is 61 or more

[0229] [Measurement / Evaluation Method of Resin Impregnation]

[0230] The glass cloth was sampled to a size of 50 mm x 50 mm or larger. The sample was taken so that the measurement site would not bend or touch. The static viscosity of the sampled glass cloth at 24°C in castor oil (manufactured by Hayashi Jun Chemical Industry Co., Ltd., Model No. 03001535, 24°C = 560 mPa·s×g / cm2) was measured. 3) for a predetermined time. A high-precision camera (frame size: 5120×5120 pixels) was placed perpendicular to the glass cloth. Using an LED light source (CCS, Powerflush Bar) as a light source, the glass cloth was sandwiched and illuminated from both sides from a horizontal position 15 cm away. Furthermore, within a 32 mm×32 mm viewing angle, the number of pores larger than 160 μm between the glass filaments was counted, and the average value of three measurements was defined as the pore count. Pores correspond to portions that have not been impregnated with the matrix resin. Therefore, a glass cloth with a low number of pores indicates excellent impregnation with the matrix resin.

[0231] The resin impregnation property was evaluated according to the following criteria: The time from immersing the glass cloth test piece in the impregnation varnish to counting the number of unimpregnated portions was set to 3 minutes later.

[0232] A: The number of unimpregnated areas is less than 80

[0233] B: The number of unimpregnated sites is 81 or more and 160 or less

[0234] C: The number of unimpregnated sites is 161 or more and 200 or less

[0235] D: The number of unimpregnated sites is 201 or more and 250 or less

[0236] E: The number of unimpregnated sites is 251 or more

[0237] [Method for producing laminated boards]

[0238] For the glass cloth obtained in the examples and comparative examples, 45 parts by mass of polyphenylene ether (manufactured by SABIC, Noryl (trade name) SA9000), 10 parts by mass of triallyl isocyanurate, 45 parts by mass of toluene, and 0.6 parts by mass of 1,3-di(tert-butylisopropylbenzene) were added to a stainless steel container and stirred at room temperature for 1 hour to prepare a varnish. After impregnating the glass cloth with the prepared varnish, it was dried at 115°C for 1 minute to obtain a prepreg. 8 sheets of the obtained prepreg were stacked, and copper foil with a thickness of 12 μm was stacked on top and bottom. The mixture was heated at 200°C and 40 kg / cm 2 The laminate was obtained by heating and pressing for 120 minutes.

[0239] [Evaluation Method for Heat Resistance of Laminated Sheets]

[0240] After the copper foil of the laminate obtained above was removed by etching, it was heated and water-absorbed at 133°C for 70 hours in a pressure cooker. The laminate after water absorption was then immersed in a solder bath at 288°C for 20 seconds and visually checked for the presence of 0.03 cm of cracks caused by peeling at the interface between the glass cloth and the resin. 2 The above expansion (bulging). Six tests were performed using each laminate. The heat resistance was evaluated as follows. It should be noted that the less the laminate expands, the better the heat resistance.

[0241] A: Among the six laminated sheets, none of the laminated sheets expanded.

[0242] B: One laminated plate has swelling.

[0243] C: There is swelling in the two laminated sheets.

[0244] D: There is swelling in the three laminated sheets.

[0245] E: There is expansion in 4 to 6 laminated sheets.

[0246] Manufacturing Example

[0247] [Example 1]

[0248] The warp was warped using silica glass yarn with a SiO2 content of more than 99.9% by mass, an average filament diameter of 7.5 μm, 50 filaments, and a twist of 1.0Z. 2 The warp yarns straightened at a conveying speed of 60 m / min are pressed by rollers under a load to flatten the glass yarn. Thereafter, a sizing agent having polyvinyl alcohol (PVA) resin as the main component is attached according to the following steps. That is, a 5% aqueous solution of PVA (trade name: PVA403, manufactured by Kuraray Co., Ltd.) is prepared, and 2% hydrogenated castor oil as a lubricant is mixed into the aqueous solution to obtain a sizing agent. After the sizing agent is kept warm at 60°C and attached to the glass yarn, it is dried to perform a sizing treatment. Thereafter, a glass cloth is woven using an air jet loom with a weaving density of 66 warp yarns / inch and 68 weft yarns / inch. It should be noted that the weaving is performed in a manner such that the cloth width becomes 1300 mm. As the weft yarn, a yarn of silica glass having an average filament diameter of 7.5 μm, a filament number of 50, and a twist number of 1.0Z is used.

[0249] The obtained glass cloth was transported at a line speed of 15 seconds while being immersed in a water tank containing ion exchange water at 60°C, while the sizing agent attached to the glass surface was cleaned (pre-deoiling cleaning process). Thereafter, the glass cloth was deoiled by heating at 1000°C for 30 seconds using a roll-to-roll method in a heating furnace installed on the same production line to obtain glass cloth (heating deoiling process). Next, the glass cloth was moved in water at a transport tension of 200N and a line speed of 30m / min while being irradiated at a frequency of 25GHz and an output power of 0.72W / cm 2 The residue was cleaned by ultrasonic wave (cleaning and fiber opening process). Next, a treatment solution was prepared in which 0.3% by mass of 3-methacryloxypropyltrimethoxysilane and Z6030 (manufactured by TORAY DOW) were dispersed in pure water adjusted to pH=3 with acetic acid. The cloth was immersed in the treatment solution and squeezed, then heated and dried at 130°C for 60 seconds to fix the silane coupling agent. The cloth was fixed by spraying at 3.0 kg / cm 2 The dried cloth was subjected to high-pressure opening (post-surface treatment opening step) at a pressure of 100°C and then dried at 130°C for 1 minute to obtain a glass cloth. The thickness, warp width, weft width, (number of warp segments - 0.2) / T value, warp bonding ratio, 24×DT value, 14×DT value, and loss on ignition of the obtained glass cloth were measured. Furthermore, fuzzing and resin impregnation were evaluated. Furthermore, laminated sheets were produced using the above method and their heat resistance was evaluated.

[0250] [Example 2]

[0251] The warp was warped using silica glass yarn with a SiO2 content of more than 99.9% by mass, an average filament diameter of 9.0 μm, 34 filaments, and a twist of 1.0Z. 2The warp yarns straightened at a conveying speed of 60 m / min are pressed by rollers under a load to flatten the glass yarn. Thereafter, a sizing agent having polyvinyl alcohol (PVA) resin as the main component is attached according to the following steps. That is, a 5% aqueous solution of PVA (trade name: PVA403, manufactured by Kuraray Co., Ltd.) is prepared, and 2% hydrogenated castor oil as a lubricant is mixed into the aqueous solution to obtain a sizing agent. After the sizing agent is kept warm at 60°C and attached to the glass yarn, it is dried to perform sizing treatment. Thereafter, a jet loom is used to weave the cloth with a weaving density of 66 warp yarns / inch and 68 weft yarns / inch. It should be noted that the cloth is woven in a manner such that the width is 1300 mm. As the weft yarn, a yarn of silica glass having an average filament diameter of 9.0 μm, a filament number of 34, and a twist number of 1.0Z is used. The obtained glass cloth was used to obtain the glass cloth of Example 2 by the same method as in Example 1 except that the conditions described in the table were changed.

[0252] [Example 3]

[0253] The warp was warped using silica glass yarn with a SiO2 content of more than 99.9% by mass, an average filament diameter of 7.5 μm, 96 filaments, and a twist of 1.0Z. 2 The warp yarns straightened at a conveying speed of 60 m / min are pressed by rollers under a load to flatten the glass yarn. Thereafter, a sizing agent having polyvinyl alcohol (PVA) resin as the main component is attached according to the following steps. That is, a 5% aqueous solution of PVA (trade name: PVA403, manufactured by Kuraray Co., Ltd.) is prepared, and 2% of hydrogenated castor oil as a lubricant is mixed into the aqueous solution to obtain a sizing agent. After the sizing agent, which has been kept warm at 60°C, is attached to the glass yarn and then dried, sizing treatment is performed. Thereafter, a cloth is woven using an air jet loom with a weaving density of 54 warp yarns / inch and 54 weft yarns / inch. It should be noted that weaving is performed in a manner such that the cloth width becomes 1300 mm. As the weft yarn, a yarn of silica glass having an average filament diameter of 7.5 μm, a filament number of 96, and a twist number of 1.0Z is used. The obtained glass cloth was used to obtain the glass cloth of Example 3 by the same method as in Example 1 except that the tension in the cleaning and fiber-opening step was set to 250 N and the conditions were changed to those described in the table.

[0254] [Example 4]

[0255] The warp was warped using silica glass yarn with an SiO2 content of more than 99.9% by mass, an average filament diameter of 6.0 μm, 22 filaments, and a twist of 0.6Z. 2The warp yarns straightened at a conveying speed of 60 m / min are pressed by rollers under a load to flatten the glass yarn. Thereafter, a sizing agent having polyvinyl alcohol (PVA) resin as the main component is attached according to the following steps. That is, a 5% aqueous solution of PVA (trade name: PVA403, manufactured by Kuraray Co., Ltd.) is prepared, and 2% hydrogenated castor oil as a lubricant is mixed into the aqueous solution to obtain a sizing agent. After the sizing agent is kept warm at 60°C and attached to the glass yarn, it is dried to perform sizing treatment. Thereafter, a cloth is woven using an air jet loom with a weaving density of 95 warp yarns / inch and 95 weft yarns / inch. It should be noted that the cloth is woven in such a way that the width becomes 1300 mm. As the weft yarn, a yarn of silica glass having an average filament diameter of 6.0 μm, a filament number of 22, and a twist number of 0.6Z is used. The obtained glass cloth was used to obtain the glass cloth of Example 4 by the same method as in Example 1 except that the conditions described in the table were changed.

[0256] [Comparative Example 1]

[0257] The warp was warped using silica glass yarn with a SiO2 content of more than 99.9% by mass, an average filament diameter of 5.0 μm, 100 filaments, and a twist of 1.0Z. 2 The warp yarns straightened at a conveying speed of 60 m / min are pressed by rollers under a load to flatten the glass yarn. Thereafter, a sizing agent having polyvinyl alcohol (PVA) resin as the main component is attached according to the following steps. That is, a 5% aqueous solution of PVA (trade name: PVA403, manufactured by Kuraray Co., Ltd.) is prepared, and 2% hydrogenated castor oil as a lubricant is mixed into the aqueous solution to obtain a sizing agent. The sizing agent, which has been kept warm at 60°C, is attached to the glass yarn and then dried to perform a sizing treatment. Thereafter, a jet loom is used to weave a cloth with a weaving density of 66 warp yarns / inch and 68 weft yarns / inch. It should be noted that weaving is performed in a manner such that the cloth width becomes 1300 mm. As the weft yarn, a yarn of silica glass having an average filament diameter of 5.0 μm, a filament number of 100, and a twist number of 1.0Z is used. The obtained glass cloth was used in the same manner as in Example 1 to obtain the glass cloth of Comparative Example 1.

[0258] [Comparative Example 2]

[0259] The glass cloth of Comparative Example 2 was obtained by the same method as in Example 1 except that the conditions described in the table were changed by using the glass cloth obtained in Comparative Example 1.

[0260] [Comparative Example 3]

[0261] The warp was warped using silica glass yarn with a SiO2 content of more than 99.9% by mass, an average filament diameter of 5.0 μm, 200 filaments, and a twist of 1.0Z. 2 The warp yarns straightened at a conveying speed of 60 m / min are pressed by rollers under a load to flatten the glass yarn. Thereafter, a sizing agent having polyvinyl alcohol (PVA) resin as the main component is attached according to the following steps. That is, a 5% aqueous solution of PVA (trade name: PVA403, manufactured by Kuraray Co., Ltd.) is prepared, and 2% hydrogenated castor oil as a lubricant is mixed into the aqueous solution to obtain a sizing agent. After the sizing agent, which has been kept warm at 60°C, is attached to the glass yarn and then dried, sizing treatment is performed. Thereafter, a cloth is woven using an air jet loom with a weaving density of 54 warp yarns / inch and 54 weft yarns / inch. It should be noted that weaving is performed in a manner such that the cloth width becomes 1300 mm. As the weft yarn, a yarn of silica glass having an average filament diameter of 5.0 μm, a filament number of 200, and a twist number of 1.0Z is used. The obtained glass cloth was used in the same manner as in Example 3 to obtain the glass cloth of Comparative Example 3.

[0262] [Comparative Example 4]

[0263] The warp was warped using silica glass yarn with a SiO2 content of more than 99.9% by mass, an average filament diameter of 4.0 μm, 50 filaments, and a twist of 0.6Z. 2 The warp yarns straightened at a conveying speed of 60 m / min are pressed by rollers under a load to flatten the glass yarn. Thereafter, a sizing agent having polyvinyl alcohol (PVA) resin as the main component is attached according to the following steps. That is, a 5% aqueous solution of PVA (trade name: PVA403, manufactured by Kuraray Co., Ltd.) is prepared, and 2% hydrogenated castor oil as a lubricant is mixed into the aqueous solution to obtain a sizing agent. The sizing agent, which has been kept warm at 60°C, is attached to the glass yarn and then dried to perform sizing treatment. Thereafter, a cloth is woven using an air jet loom with a weaving density of 95 warp yarns / inch and 95 weft yarns / inch. It should be noted that the cloth is woven in such a way that the width becomes 1300 mm. As the weft yarn, a yarn of silica glass having an average filament diameter of 4.0 μm, a filament number of 50, and a twist number of 0.6Z is used. The obtained glass cloth was used in the same manner as in Example 4 to obtain the glass cloth of Comparative Example 4.

[0264] [Example 5]

[0265] The glass cloth obtained in Example 1 was used, and the glass cloth of Example 5 was obtained by the same method as in Example 1 except that ultrasonic irradiation was not performed before the surface treatment and the conditions described in the table were changed.

[0266] [Example 6]

[0267] The glass cloth of Example 6 was obtained by the same method as in Example 1 except that the glass cloth obtained in Example 1 was used and the line speed was set to 80 m / min.

[0268] [Comparative Example 5]

[0269] Silica glass yarn with an SiO2 composition of more than 99.9% by mass, an average filament diameter of 6.0 μm, 22 filaments, and a twist number of 0.6Z was used to warp the warp yarn. At this time, the warp yarn straightened at a conveying speed of 60 m / min was not pressed, and a sizing agent with polyvinyl alcohol (PVA) resin as the main component was attached according to the following steps. That is, a 5% aqueous solution of PVA (trade name: PVA403, manufactured by Kuraray Co., Ltd.) was prepared, and 2% hydrogenated castor oil as a lubricant was added to the aqueous solution to obtain a sizing agent. After the sizing agent was kept warm at 60°C and attached to the glass yarn, it was dried to perform a sizing treatment. Thereafter, a jet loom was used to weave the cloth with a weaving density of 95 warp yarns / inch and 95 weft yarns / inch. It should be noted that weaving was performed in a manner such that the cloth width became 1300 mm. As the weft yarn, a silica glass yarn having an average filament diameter of 6.0 μm, 22 filaments, and a twist of 0.6 Z was used. The glass cloth of Comparative Example 5 was obtained by the same method as in Example 4 except that the conditions described in the table were changed using the obtained glass cloth.

[0270] [Comparative Example 6]

[0271] The glass cloth of Comparative Example 6 was obtained by the same method as in Example 4 except that the glass cloth obtained in Example 4 was used and ion-exchanged water at 20° C. was used in the pre-deoiling washing step.

[0272] [Table 1]

[0273]

[0274] [Table 2]

[0275]

[0276] In the glass cloths of Examples 1 to 7, which used glass yarns with filament diameters larger than the thickness of the glass cloth, flattened the yarn bundles during warping, and then applied sizing, and washed with water at a temperature above a specified temperature before heat deoiling, the number of warp yarn bundles fell within the specified range, suppressing the occurrence of fuzz. Furthermore, in the glass cloths of Examples 1 to 4, which were ultrasonically cleaned at a specified conveying speed before the surface treatment step, the number of warp yarn bundles and the warp yarn bonding ratio fell within the specified range, achieving good resin impregnation and heat resistance of the laminated sheet.

[0277] In the glass cloths of Comparative Examples 1 to 4, produced according to the filament diameters specified in the IPC standard, the number of warp yarn segments increased, making it impossible to suppress the occurrence of fuzzing, and the resin impregnation was poor. In Comparative Example 2, increasing the processing force of the fiber opening treatment increased fuzzing.

[0278] Furthermore, in Comparative Example 5, in which glass yarn having a filament diameter larger than the thickness of the glass cloth was used but the yarn bundles were not flattened during warping, and in Comparative Example 6, in which the glass cloth was not washed with water at a temperature above the specified temperature before heat deoiling, the number of warp yarn bundles and the warp yarn bonding ratio could not be controlled within the specified ranges, resulting in increased fuzzing and poor resin impregnation.

Claims

1. A glass cloth comprising glass yarns containing a plurality of filaments as warp yarns and weft yarns, The silicon (Si) content of the glass yarn is 95.0% by mass to 100% by mass as calculated based on silicon dioxide (SiO2). The glass cloth has a thickness (T) of 80 μm or less and satisfies the following formula (A1): {Number of warp yarn segments (N) - 0.2} / Thickness (T) [μm] < 0.056…(A1) In the formula (A1), the number of warp yarn segments (N) is a value obtained by warp yarn filament diameter [μm]×number of warp yarn filaments [pieces]÷warp yarn width [μm].

2. The glass cloth according to claim 1, wherein After the glass cloth is embedded in an epoxy resin and the epoxy resin is cured, when a cross section of the glass cloth is observed, the warp yarn bonding ratio calculated by the following formula exceeds 0 and is 0.80 or less. Warp yarn bonding ratio = number of bonding points of filaments bonded to each other in the warp yarn / number of warp yarn filaments. 3 . The glass cloth according to claim 1 , which is treated with a surface treatment agent containing a silane coupling agent.

4. The glass cloth according to claim 3, wherein The silane coupling agent comprises a compound represented by the following formula (C), X(R) 3-n SiY n …(C) In formula (C), X is an organic group having at least one of an amino group and an unsaturated double bond group having free radical reactivity, 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 a methyl group, an ethyl group, and a phenyl group.

5. The glass cloth according to claim 4, wherein X in the formula (C) is an organic group having one or more methacryloyloxy groups or acryloyloxy groups.

6. The glass cloth according to any one of claims 1 to 5, wherein The average filament diameter (D) of the glass yarn is 4 μm or more.

7. The glass cloth according to any one of claims 1 to 6, wherein When the thickness of the glass cloth is 20 μm or more and 80 μm or less, the following formula (B1) is satisfied. When the thickness of the glass cloth is less than 20 μm, the following formula (B6) is satisfied. 24×average filament diameter (D) [μm]-thickness (T) [μm]>96…(B1) 14×average filament diameter (D) [μm]-thickness (T) [μm]>46…(B6).

8. The glass cloth according to any one of claims 1 to 5, wherein The glass cloth has a thickness (T) of 60 μm or less.

9. The glass cloth according to any one of claims 1 to 5, wherein The glass cloth has a loss on ignition value in the range of 0.01 mass % to 0.30 mass %.

10. The glass cloth according to any one of claims 1 to 5, which is used for a printed circuit board. 11 . A prepreg comprising the glass cloth according to claim 1 , a thermosetting resin, and an inorganic filler.

12. A printed circuit board comprising the prepreg according to claim 11.

13. An integrated circuit comprising the printed circuit board according to claim 12.

14. An electronic device comprising the printed circuit board according to claim 12.

15. A method for manufacturing glass cloth, wherein: The method comprises: A process of weaving glass yarns containing a plurality of filaments and having an Si content in the range of 95.0% by mass to 100% by mass as SiO2 as warp and weft to obtain glass cloth. The method further comprises: Before the weaving process, the glass yarn bundle is flattened, and then the warping process of sizing is carried out, and After the warping process and before, during or after the weaving process, the following process is also included: The process of washing glass yarn with water above 50°C; a step of heating and deoiling the cleaned glass yarn; and The step of washing and opening the heated and deoiled glass yarn while conveying it at a speed of 50 m / min or less in a liquid irradiated with ultrasonic waves, The thickness (T) of the glass cloth after the fiber opening treatment is 80 μm or less. When the thickness of the glass cloth after the fiber-spreading treatment is 20 μm or more and 80 μm or less, the following formula (B1) is satisfied. When the thickness of the glass cloth after the fiber-spreading treatment is less than 20 μm, the following formula (B6) is satisfied: 24×average filament diameter (D) [μm]-thickness (T) [μm]>96…(B1) 14×average filament diameter (D) [μm]-thickness (T) [μm]>46…(B6).

16. The method according to claim 15, further comprising: The process of surface treating the cleaned and opened glass cloth with a surface treatment agent.

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