Glass cloth, prepreg, and printed wiring board

Abstract

The purpose of the present disclosure is to provide a glass cloth that is capable of realizing excellent dielectric properties and excellent insulation reliability, and that makes it possible to obtain a resin substrate having a small whitening distance.　The glass cloth according to the present disclosure is obtained by weaving glass thread. This glass cloth is surface-treated by a surface treatment agent. A formula A is obtained from the total carbon content in the glass cloth and the carbonyl group-derived peak height as measured by Fourier transform infrared spectroscopy. Formula A: carbonyl group-derived peak height / total glass-cloth carbon content is 10 or greater; and the number of white spots P is 10 pcs. / m2 or less.

Description

[Technical Field]

[0001] The present disclosure relates to glass cloth, prepregs, printed wiring boards, and the like. [Background technology]

[0002] Currently, information terminals such as smartphones are becoming more powerful, and high-speed communications, such as those typified by 5G communications, are becoming more common. Accordingly, in printed wiring boards for high-speed communications, the dielectric constant and dissipation factor of insulating materials used to reduce transmission loss are becoming significantly lower, and higher levels of insulation reliability are also being demanded.

[0003] Examples of insulating materials for printed wiring boards for high-speed communication are reported in Patent Documents 1 and 2. Specifically, Patent Documents 1 and 2 describe a method of impregnating a glass cloth with a low-dielectric thermosetting resin (hereinafter collectively referred to as "matrix resin") that is crosslinked and cured by a radical reaction, such as polyphenylene ether whose terminals are modified with vinyl or methacryloxy groups, and then drying the resin to obtain a prepreg. A laminate is known that is produced by laminating the prepregs obtained in this manner and curing them by heating and applying pressure. Patent Documents 1 and 2 aim to achieve a low dielectric constant and low dielectric dissipation factor for the laminate by combining the prepreg with a glass cloth that has a low dielectric constant and low dielectric dissipation factor.

[0004] Here, Patent Documents 3 and 4 report that the amount of silanol groups on the glass surface is reduced by heating silica glass cloth at a high temperature in order to reduce the dielectric loss tangent of the glass cloth. Also, Patent Document 5 reports that glass yarn is obtained by spinning glass fibers with a softening point of 1000 to 1600°C in order to extend the drill life in the glass cloth drilling process, and that glass cloth is produced using such glass yarn. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 065940 [Patent Document 2] International Publication No. 2019 / 065941 [Patent Document 3] Patent Publication No. 2021-63320 [Patent Document 4] Japanese Patent Publication No. 2021-195689 [Patent Document 5] Japanese Patent Application Publication No. 2023-131220 Summary of the Invention [Problem to be solved by the invention]

[0006] However, compared to the conventional technologies described in Patent Documents 1 to 5, there has been a strong demand for the creation of a technology that can produce a resin substrate with a small whitening distance, while also realizing a glass cloth with excellent dielectric properties and excellent insulation reliability. Here, the "whitening distance" that the present inventors focused on is one of the indicators that represents the degree of interfacial peeling between the glass cloth and the matrix resin. The more excellent the insulation reliability of a glass cloth, the more likely it is to provide a resin substrate with a small whitening distance.

[0007] An object of the present disclosure is to provide a glass cloth that can realize excellent dielectric properties and excellent insulation reliability, and that can also provide a resin substrate with a small whitening distance. Another object of the present disclosure is to provide a prepreg and a printed wiring board that are realized using the glass cloth, and to provide a method for producing the glass cloth. [Means for solving the problem]

[0008] According to one example of the aspects of the present disclosure, it is possible to reduce the whitening distance in a resin substrate while maintaining the dielectric properties of the glass cloth. That is, the present inventors have discovered for the first time that an example of an embodiment of the present disclosure can provide a glass cloth that has excellent dielectric properties and also has excellent insulation reliability, in that the whitening distance of the resulting resin substrate is small. An example of an aspect of the present disclosure is as follows.

[0009] [1] A glass cloth made by weaving glass yarn, the glass cloth is surface-treated with a surface treatment agent, The following formula A is calculated from the total carbon amount of the glass cloth and the peak height derived from carbonyl groups measured by Fourier transform infrared spectroscopy: Formula A = peak height derived from carbonyl groups / total carbon content of glass cloth is greater than or equal to 10, 10 white spots / m 2 Below is glass cloth. [2] A glass cloth made by weaving glass yarn, The glass cloth is surface-treated with a surface treatment agent, The following formula B is calculated from the ignition loss value of the glass cloth and the peak height derived from a carbonyl group measured by Fourier transform infrared spectroscopy: Formula B = carbonyl group peak height / glass cloth ignition loss value is greater than or equal to 11, 10 white spots / m 2 Below is glass cloth. [3] 3. The glass cloth according to item 1 or 2, wherein the silicon (Si) content in the glass yarn is 95.0 to 100 mass % in terms of silicon dioxide (SiO2). [4] 4. The glass cloth according to any one of items 1 to 3, which has a dielectric loss tangent at 10 GHz of 0.002 or less. [5] 5. The glass cloth according to any one of items 1 to 4, wherein the bulk dielectric loss tangent at 10 GHz of the glass constituting the glass yarns is 0.002 or less. [6] 6. The glass cloth according to any one of items 1 to 5, wherein the surface treatment agent contains a silane coupling agent. [7] The surface treatment agent is represented by the following formula (1): X 3-n SiY n ···(1) (In the formula, each X is independent and may contain a different organic functional group, and is composed of a functional group having a total of two or more carbonyl groups and two or more unsaturated carbon-carbon double bonds; each Y is independently an alkoxy group; and n is an integer of 1 or more and 3 or less.) 7. The glass cloth according to any one of items 1 to 6, comprising a silane coupling agent represented by the formula: [8] 8. The glass cloth according to item 7, wherein the unsaturated carbon-carbon double bond is a bond derived from at least one of an acryloyl group and a methacryloyl group. [9] 9. The glass cloth according to any one of items 1 to 8, wherein the ignition loss value of the glass cloth is in the range of 0.01 to 0.5% by mass.

[10] 10. The glass cloth according to any one of items 1 to 9, wherein the average degree of opening calculated from the yarn width of each of the warp and weft yarns of the glass cloth exceeds 40%.

[11] 11. The glass cloth according to any one of items 1 to 10, wherein the total carbon content of the glass cloth is in the range of 0.01 to 0.8 mass %.

[12] A prepreg comprising the glass cloth according to any one of items 1 to 11 and a matrix resin.

[13] Item 13. A printed wiring board comprising the prepreg according to item 12.

[14] Item 14. An integrated circuit comprising the printed wiring board according to item 13.

[15] Item 14. An electronic device comprising the printed wiring board according to item 13.

[16] A method for producing glass cloth by weaving glass yarns, a surface treatment step of treating the glass fiber with a surface treatment liquid containing a surface treatment agent having a molecular weight of 200 or more; The surface treatment step includes: a step of adding a solvent to the surface treatment agent to prepare the surface treatment liquid; controlling the temperature of the surface treatment solution; controlling the pH of the surface treatment solution; and filtering the surface treatment liquid; A method for producing glass cloth, comprising at least one of the steps:

[17] The surface treatment step includes: The method includes a step of surface-treating the deoiled glass fiber with a surface treatment agent, The surface treatment agent has the following formula (1): X 3-n SiY n ···(1) (In the formula, each X is independent and may contain a different organic functional group, and is composed of a functional group having a total of two or more carbonyl groups and two or more unsaturated carbon-carbon double bonds; each Y is independently an alkoxy group; and n is an integer of 1 or more and 3 or less.) Item 16. The method for producing glass cloth according to item 15, comprising a silane coupling agent represented by the formula:

[18] The surface treatment step includes: controlling the temperature and pH of the surface treatment solution; Item 18. The method for producing glass cloth according to Item 16 or 17, further comprising the step of filtering the surface treatment liquid.

[19] 19. The method for producing a glass cloth according to any one of items 16 to 18, further comprising a step of subjecting the glass yarns to an opening treatment after the surface treatment step.

[20] 20. The method for producing a glass cloth according to any one of items 16 to 19, further comprising inspecting the glass cloth for white spots. [twenty one] 21. A method for producing a glass cloth according to any one of items 16 to 20, comprising a step of measuring the height of a peak derived from a carbonyl group in the glass cloth by Fourier transform infrared spectroscopy. [twenty two] A test method for glass cloth made by weaving glass yarn, the glass cloth is surface-treated with a surface treatment agent, The test method comprises: a step of inspecting the glass cloth for white spots based on the height of a peak derived from a carbonyl group in the glass cloth and the total carbon content of the glass cloth or the ignition loss value of the glass cloth. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a glass cloth that can realize excellent dielectric properties and excellent insulation reliability, and further, can obtain a resin substrate with a small whitening distance. Furthermore, according to the present disclosure, it is possible to provide a prepreg, a printed wiring board, an integrated circuit, and an electronic device that are realized using the glass cloth, and to provide a method for manufacturing the glass cloth, etc. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 4 is a diagram for explaining a calibration curve in this embodiment. [Figure 2] 5A and 5B are diagrams for explaining white spots in the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present disclosure (hereinafter referred to as "the present embodiment") will be described. However, the present invention is not limited to the present embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0013] In the present specification, when a plurality of structures represented by the same symbol exist in the same formula, the structures may be independently selected and may be the same or different from each other, unless otherwise specified. When a plurality of structures represented by the same symbol exist in different formulas, the structures may be independently selected and may be the same or different from each other, unless otherwise specified. In the present specification, various measurements are carried out based on the methods described in the Examples unless otherwise specified. In the present specification, the upper or lower limit of a numerical range described in a stepwise manner may be replaced by the upper or lower limit of a corresponding numerical range described in another stepwise manner, and may further be replaced by the corresponding value described in the Examples.

[0014] In this specification, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps, as long as the function of the step is achieved. In the contents shown in the drawings, the scale, shape, and length may be exaggerated for clarity.

[0015] [Glass cloth] The glass cloth of this embodiment is a glass cloth made by weaving glass yarns, for example, a glass cloth made by weaving glass yarns made of a plurality of glass filaments as warp and weft yarns.

[0016] In one aspect of this embodiment, The glass cloth is surface treated with a surface treatment agent. The carbon content of the glass cloth is calculated from the total carbon content and the peak height derived from the carbonyl group measured by Fourier transform infrared spectroscopy using the following formula A: Formula A = peak height derived from carbonyl groups / total carbon content of glass cloth is greater than or equal to 10, 10 white spots / m 2 Less than (e.g., 10.0 pieces / m 2 (See below).

[0017] In addition, in a further aspect of this embodiment, The glass cloth is surface treated with a surface treatment agent. The following formula B is calculated from the ignition loss value of the glass cloth and the peak height derived from the carbonyl group measured by Fourier transform infrared spectroscopy: Formula B = carbonyl group peak height / glass cloth ignition loss value is greater than or equal to 11, 10 white spots / m 2 (For example, 10.0 pieces / m 2 (below) is below.

[0018] According to this embodiment, it is possible to provide a glass cloth that can provide a resin substrate (typically a printed wiring board) with a small whitening distance and that can exhibit excellent dielectric properties and insulation reliability. The glass cloth of this embodiment is suitable as a material for producing prepregs, printed wiring boards, integrated circuits, electronic devices, etc.

[0019] [Surface treatment] The glass cloth of this embodiment is surface-treated with a surface treatment agent. A surface-treated glass cloth has a surface treatment agent attached to its surface. Conversely, when a surface treatment agent is attached to the surface of a glass cloth, this corresponds to "surface-treated with a surface treatment agent" in the present disclosure. Here, "the surface of the glass cloth" includes "the surface of the glass yarn that constitutes the glass cloth." Specific examples of the surface treatment, such as a method for detecting a surface treatment agent, types of surface treatment agents, and surface treatment techniques, will be described later.

[0020] [Peak height derived from carbonyl group] Surface treatment agents with excellent radical reactivity contain components having carbonyl groups, such as acryloyl groups and methacryloyl groups. Fourier transform infrared spectroscopy detects clear peaks at specific positions due to carbonyl groups, and therefore, can be used to evaluate the extent to which acryloyl groups, methacryloyl groups, etc. have been introduced into the glass cloth.

[0021] When using Fourier transform infrared spectroscopy, the results obtained may vary due to the sensitivity of the light-receiving unit, measurement errors, etc. In this regard, it is preferable to prepare a calibration curve based on glass cloth that has been surface-treated with a known surface treatment agent and has a known amount of the surface treatment agent attached. By using such a calibration curve, the peak height derived from carbonyl groups can be easily obtained with good reproducibility.

[0022] [Total carbon content of glass cloth] The total carbon content of the glass cloth is measured by a method for measuring the amount of carbon dioxide generated when the glass cloth is pyrolyzed, specifically, by the method described in the Examples. Since the total carbon content tends to increase as the amount of surface treatment agent attached to the glass cloth increases, the measurement method of the present disclosure makes it easy to simply evaluate the amount of surface treatment agent attached to the glass cloth.

[0023] The total carbon content of the glass cloth is preferably 0.01 to 0.8% by mass, more preferably 0.01 to 0.6% by mass, more preferably 0.01 to 0.5% by mass, even more preferably 0.01 to 0.4% by mass, and particularly preferably 0.01 to 0.3% by mass, 0.02 to 0.20% by mass, 0.03 to 0.15% by mass, or 0.03 to 0.10% by mass. If the total carbon content is less than 0.01% by mass, the amount of surface treatment agent attached to the glass cloth is often insufficient, which tends to result in poor insulation. If the total carbon content of the glass cloth exceeds 0.8% by mass, the dielectric loss tangent of the glass cloth is often high, which makes it difficult to reduce the dielectric loss tangent of the glass cloth.

[0024] (Relationship between the peak height derived from carbonyl groups and the total carbon content of the glass cloth) The glass cloth of this embodiment is The carbon content of the glass cloth is calculated from the total carbon content and the peak height derived from the carbonyl group measured by Fourier transform infrared spectroscopy using the following formula A: Formula A = peak height derived from carbonyl groups / total carbon content of glass cloth The value of is 10 or greater.

[0025] A value of 10 or more in formula A means that the proportion of highly reactive components (components having carbonyl groups) in the surface treatment agent adhered to the glass cloth is high. One of the ideas of the present inventors is to focus on the "peak height derived from carbonyl groups" and the "total carbon content of the glass cloth" and to define the ratio between them (peak height derived from carbonyl groups / total carbon content of the glass cloth). Based on one of the ideas of the present inventors, a glass cloth having a high value of 10 or more in the formula A can be specified. According to this embodiment, since the value of formula A is high, it is possible to provide a glass cloth that can give a resin substrate with a small whitening distance, and also to provide a glass cloth that exhibits excellent dielectric properties and insulation reliability.

[0026] The value of formula A is 10 or more (e.g., 10.0 or more), preferably greater than 10 (e.g., greater than 10.0), preferably 11 or more (e.g., 11.0 or more), more preferably 12 or more (e.g., 12.0 or more), even more preferably 13 or more (e.g., 13.0 or more), even more preferably 15 (e.g., 15.0 or more), and particularly preferably 19 (e.g., 19.0 or more). When the value of formula A is 10 or more, adhesion between the glass cloth and the matrix resin can be ensured, thereby reducing the whitening distance in the resulting resin substrate. The value of formula A may be 60 or less (e.g., 60.0 or less).

[0027] [Ignition loss value of glass cloth] The ignition loss value of the glass cloth is measured by a method of thermally deoiling the glass cloth (glass cloth after surface treatment), specifically, by the method described in the Examples. Since the ignition loss value tends to increase as the amount of surface treatment agent attached to the glass cloth increases, the measurement method of the present disclosure makes it easy to simply evaluate the amount of surface treatment agent attached to the glass cloth.

[0028] The ignition loss value of the glass cloth is preferably 0.01 to 0.5% by mass, 0.01 to 0.4% by mass, or 0.01 to 0.3% by mass, more preferably 0.02 to 0.25% by mass, even more preferably 0.03 to 0.22% by mass, even more preferably 0.03 to 0.17% by mass, and particularly preferably 0.04 to 0.15% by mass. When the ignition loss value is 0.01% by mass or more, the adhesion between the resin and the glass cloth in the resulting prepreg is likely to be good. In this case, when a printed wiring board is produced, heat resistance and insulation reliability are likely to be ensured. When the ignition loss value of the glass cloth is 0.5% by mass or less, it is likely to be avoided that a large amount of surface treatment agent (or its residue) physically adhered to the glass cloth surface without forming a chemical bond with the glass cloth, a surface treatment agent (or its residue) that cannot be removed from the glass cloth surface by washing with water, and / or modified products thereof are present on the glass cloth surface. In this case, it is easy to reduce the dielectric loss tangent of the glass cloth.

[0029] (Relationship between the peak height derived from carbonyl groups and the ignition loss value of glass cloth) The glass cloth of this embodiment is The following formula B is calculated from the ignition loss value of the glass cloth and the peak height derived from the carbonyl group measured by Fourier transform infrared spectroscopy: Formula B = carbonyl group peak height / glass cloth ignition loss value The value of is 11 or greater.

[0030] A value of 11 or more in formula B means that the proportion of highly reactive components (components having carbonyl groups) in the surface treatment agent adhered to the glass cloth is high. Here, one of the ideas of the present inventors is to focus on the "peak height derived from carbonyl groups" and the "ignition loss value of glass cloth" and to define the ratio between them (peak height derived from carbonyl groups / ignition loss value of glass cloth). Based on one of the ideas of the present inventors, a glass cloth having a high value of 11 or more in formula B can be specified. According to this embodiment, since the value of formula B is high, it is possible to provide a glass cloth that can give a resin substrate with a small whitening distance, and also to provide a glass cloth that exhibits excellent dielectric properties and insulation reliability.

[0031] The value of formula B is 11 or more (e.g., 11.0 or more), preferably greater than 11 (e.g., greater than 11.0), preferably 12 or more (e.g., 12.0 or more), more preferably 13 or more (e.g., 13.0 or more), even more preferably 14 or more (e.g., 14.0 or more), and particularly preferably 15 or more (e.g., 15.0 or more). When the value of formula B is 11 or more, adhesion between the glass cloth and the matrix resin can be ensured, thereby reducing the whitening distance of the resulting resin substrate. The value of formula B may be 60 or less (e.g., 60.0 or less).

[0032] [Dielectric loss tangent] (Dielectric loss tangent of glass cloth) The glass cloth of this embodiment preferably has a dielectric loss tangent of 0.002 or less at 10 GHz. Such a glass cloth can provide a prepreg and a printed wiring board with improved dielectric properties. From the viewpoint of improving the dielectric properties, the dielectric loss tangent of the glass cloth at 10 GHz is preferably 0.0015 or less, 0.0010 or less, 0.0007 or less, 0.0006 or less, 0.0005 or less, 0.0004 or less, 0.0003 or less, or 0.0002 or less. The dielectric loss tangent of the glass cloth may be greater than 0.

[0033] (Method for measuring dielectric loss tangent) The dielectric loss tangent at 10 GHz of the glass cloth of this embodiment is measured by a method using a split cylinder resonator (a method using a resonance method), specifically, by the method described in the Examples. This method allows for simpler and more accurate measurement than conventional methods in which a substrate is fabricated as a measurement sample and the dielectric properties are evaluated. The reason for this, without being limited by theory, is that the resonance method is suitable for evaluation in the high frequency range, particularly for evaluation of low-loss materials. Other than the resonance method, other methods for evaluating dielectric properties include the lumped parameter method and the reflection transmission method. However, the lumped parameter method requires the measurement sample to be sandwiched between two electrodes to form a capacitor, which can be a problem in that the operation can be cumbersome. Furthermore, when evaluating low-loss materials, the reflection transmission method is subject to the strong influence of the port matching characteristics, making it difficult to evaluate the dielectric loss tangent of the measurement sample with high accuracy. From the above, it is possible to easily and accurately measure the dielectric loss tangent of a glass cloth by using a technique that uses a resonance method, specifically, by using the technique described in the examples.

[0034] For glass cloth used in printed wiring boards, particularly glass cloth used in printed wiring boards for high-speed communication, it is preferable that a measuring device for measuring the dielectric properties thereof has a predetermined measurable range. For example, for the dielectric constant (Dk) and the dielectric loss tangent (Df), the measuring device should have a measurable range of Dk=1.1 Fm -1 ~50Fm -1 , and Df = 1.0 × 10 -6 ~1.0×10 -1 It is preferable that the measurable range is Dk=1.5Fm -1 ~10Fm -1 , and Df = 1.0 × 10 -5 ~5.0×10 -1 It is more preferable that the measurable range is Dk=2.0Fm -1 ~5Fm -1 , and Df = 5.0 × 10 -5 ~1.0×10 -2It is more preferable that the measurable range is .gtoreq..times ...

[0035] Furthermore, the frequency that can be measured by the measuring device for measuring the dielectric properties is preferably 10 GHz or higher, which makes it easier to evaluate the characteristics in the frequency band region, particularly the characteristics in the frequency band region expected when the glass cloth is actually used as a glass cloth for printed wiring boards for high-speed communication.

[0036] The measurement area for dielectric properties is 10 mm 2 It is preferable that it is 15 mm or more. 2 More preferably, it is 20 mm or more. 2 This makes it easier to improve the reliability of the measurement results obtained, and therefore makes it easier to determine whether the measurement results obtained are within a range of preset reference values.

[0037] The thickness of the measurement sample is preferably 3 μm to 300 μm, more preferably 5 μm to 200 μm, and even more preferably 7 μm to 150 μm.

[0038] (Bulk dielectric loss tangent) In the glass cloth of this embodiment, the bulk dielectric loss tangent at 10 GHz of the glass raw materials constituting the glass cloth is measured by a method using a split cylinder resonator (a method using a resonance method), specifically, by the method described in Examples. Here, the glass raw materials may be, for example, glass threads, glass filaments, and glass seeds.

[0039] The bulk dielectric loss tangent at 10 GHz is preferably 0.002 or less, more preferably 0.0015 or less, even more preferably 0.001 or less, even more preferably 0.0005 or less, and particularly preferably 0.0004 or less, which makes it easier to achieve the effects of the present disclosure.

[0040] (Method for controlling dielectric loss tangent and bulk dielectric loss tangent) The dielectric loss tangent and bulk dielectric loss tangent of the glass cloth are, for example, A process of removing deteriorated materials and residues present on the glass surface; can be controlled based on Here, one embodiment of the deteriorated product and the residue, etc., is, for example, the following (i) to (ii): (i) Degraded sizing agent physically attached to the glass surface is thermally oxidized (ii) Residues of surface treatment agents that physically adhere to the glass surface without forming a chemical bond with the surface and remain on the surface even after washing with water, or modified products thereof is.

[0041] [Glass thread] The glass yarn may be composed of a plurality of glass filaments. The glass yarn may be woven as a warp yarn and a weft yarn to produce a glass cloth.

[0042] [Average filament diameter] The average filament diameter of the glass filaments is preferably 2.5 to 9.0 μm, more preferably 2.5 to 7.5 μm, even more preferably 3.5 to 7.0 μm, still more preferably 3.5 to 6.0 μm, and particularly preferably 3.5 to 5.0 μm.

[0043] [Placement density] The density of the glass yarns (warp and weft) constituting the glass cloth is preferably 10 to 120 yarns / inch (=10 to 120 yarns / 25.4 mm), more preferably 40 to 100 yarns / inch, and even more preferably 40 to 100 yarns / inch.

[0044] [Metsuke] The weight of the glass cloth is preferably 8 to 250 g / m 2 and more preferably 8 to 100 g / m 2 and more preferably 8 to 80 g / m 2 and particularly preferably 8 to 50 g / m 2 is.

[0045] [Glass type] Conventionally, glass cloth used in prepregs (laminates) is usually a glass raw material called E-glass (alkali-free glass). On the other hand, for the glass cloth of this embodiment, glass raw materials such as L-glass, NE-glass, D-glass, L2-glass, T-glass, silica glass, and quartz glass may be used. From the viewpoint of excellent dielectric properties, glass raw materials such as L-glass, L2-glass, silica glass, and quartz glass are preferably used, and among them, silica glass and quartz glass are particularly preferred. Furthermore, from the viewpoint of improving the dimensional stability of laminates containing glass cloth, glass raw materials such as S-glass, T-glass, silica glass, and quartz glass are preferably used, and among them, silica glass and quartz glass are particularly preferred.

[0046] The silicon (Si) content of the glass fibers constituting the glass cloth, calculated as silicon dioxide (SiO), is preferably 95.0 to 100% by mass or 99.0 to 100% by mass, more preferably 99.5 to 100% by mass, and even more preferably 99.9 to 100% by mass. A particularly preferred embodiment of the SiO content of the glass fibers constituting the glass cloth is greater than 99.9% by mass. A Si content of 95.0% by mass or greater facilitates ensuring the dielectric properties of the glass cloth and the dimensional stability of the laminate. The silicon content can be determined using known measurement techniques such as atomic absorption spectrometry, inductively coupled plasma (ICP), and optical emission spectroscopy. Specifically, using an apparatus such as ICP-AES or ICP-MS, a calibration curve can be prepared from standard samples with known silicon content, and the silicon content of the sample to be measured can then be determined from the prepared calibration curve.

[0047] It has been conventionally recognized that when the Si content is within the above range, the hardness of the glass is so high that the glass cloth produced using the glass yarn has poor drilling processability, and that a resin substrate using a glass cloth with poor drilling processability is subjected to a strong impact during drilling, resulting in a long whitening distance of the resin substrate. In contrast to this, according to this embodiment, a resin substrate with a small whitening distance can be obtained despite the use of glass cloth with an Si content within the above range.

[0048] [Weave structure] Examples of weave structures for the glass cloth include plain weave, sieve weave, satin weave, and twill weave, with plain weave structures being more preferred.

[0049] [Surface treatment agent (surface treatment liquid)] The surface treatment liquid may contain a surface treatment agent. In this embodiment, the surface treatment is performed, for example, by a method using a surface treatment liquid.

[0050] (Concentration of surface treatment agent) The surface treatment liquid may contain a surface treatment agent and a mother liquid (e.g., an aqueous acetic acid solution). The concentration of the surface treatment agent (e.g., a silane coupling agent) in the surface treatment liquid is preferably 0.1 to 2.0 mass %, more preferably 0.2 to 1.0 mass %. By keeping the concentration of the surface treatment agent within the above range, the glass surface can be suitably treated.

[0051] (Silane coupling agent) In this embodiment, the surface treatment agent preferably contains a silane coupling agent. That is, the glass threads (including glass filaments) constituting the glass cloth are preferably surface-treated with a silane coupling agent.

[0052] The surface treatment agent is, for example, a compound represented by the following formula (1): X 3-n SiY n ···(1) (In the formula, each X is independent and may contain a different organic functional group, and is composed of a functional group having a total of two or more carbonyl groups and two or more unsaturated carbon-carbon double bonds; each Y is independently an alkoxy group; and n is an integer of 1 or more and 3 or less.) It is preferable that the compound contains a silane coupling agent represented by the formula:

[0053] With regard to the above X, the unsaturated carbon-carbon double bond is preferably a bond derived from at least one of an acryloyl group and a methacryloyl group, from the viewpoint of easily improving the adhesion between the glass cloth and the matrix resin and easily reducing the whitening distance of the resin substrate. A particularly preferred embodiment of the unsaturated carbon-carbon double bond is a bond derived from a methacryloyl group.

[0054] As for the alkoxy group Y, from the viewpoint of stability of the surface treatment of the glass cloth, an alkoxy group having 1 to 5 carbon atoms (1, 2, 3, 4 or 5 carbon atoms) is preferred.

[0055] As the silane coupling agent contained in the surface treatment agent, the silane coupling agent represented by the above formula (1) may be used alone or in combination. For example, two or more silane coupling agents having different X may be used in combination.

[0056] Examples of the silane coupling agent represented by the general formula (1) include: 2-Propenoic acid, 2-methyl-, (dimethoxysilylene)bis(oxy-2,1-ethanediyl) ester, 2-Propenoic acid, 2-methyl-, 1-[(trimethoxysilyl)methyl]-1,2-ethanediyl ester, 2-Propenoic acid, 2-methyl-, 2-[(trimethoxysilyl)methyl]-1,3-propanediyl ester, 1,1′-[2-[3-(Trimethoxysilyl)propoxy]-1,3-propanediyl] bis(2-methyl-2-propenoate), 1,1′-[2-[[(2-Methyl-1-oxo-2-propen-1-yl)oxy]methyl]-2-[[3-(triethoxysilyl)propoxy]methyl]-1,3-propanediyl] bis(2-methyl-2-propenoate)、 1-[2-[(2-Methyl-1-oxo-2-propen-1-yl)oxy]-1-[[(2-methyl-1-oxo-2-propen-1-yl)oxy]methyl]ethyl] 2-[3-(triethoxysilyl)propyl]butanedioate、 9,9-Diethoxy-2-[[2-[(2-methyl-1-oxo-2-propen-1-yl)oxy]ethoxy]methyl]-4-oxo-3,10-dioxa-5-aza-9-siladodec-1-yl 2-methyl-2-propenoate、 1,1′-[2-[[(2-Methyl-1-oxo-2-propen-1-yl)oxy]methyl]-2-[6-(trimethoxysilyl)hexyl]-1,3-propanediyl] bis(2-methyl-2-propenoate)、 Acrylic acid, [[2-[(trimethoxysilyl)methoxy]ethyl]imino]diethylene ester、 2-Propenoic acid, 1,1′-[2-(8,8-dimethoxy-3-oxo-2,9-dioxa-6-thia-8-siladec-1-yl)-2-[[(1-oxo-2-propen-1-yl)oxy]methyl]-1,3-propanediyl] ester、 1,1′-[2-Methyl-2-[[[[3-(trimethoxysilyl)propyl]amino]carbonyl]amino]-1,3-propanediyl] di-2-propenoate、 1,1′-[2-[[2-(9,9-Dimethoxy-4-oxo-3,10-dioxa-5-aza-9-silaundec-1-yl)-11,11-dimethoxy-1,6-dioxo-5,12-dioxa-2,7-diaza-11-silatridec-1-yl]amino]-2-methyl-1,3-propanediyl] di-2-propenoate, etc.

[0057] The silane coupling agent that can be used can be appropriately adjusted depending on the dielectric loss tangent of the glass cloth before surface treatment, the matrix resin used in the resin substrate, etc. Of course, the silane coupling agent represented by the above formula (1) may be used in combination with a silane coupling agent other than that represented by the above formula (1). On the other hand, it is preferable to use two or more silane coupling agents represented by the above formula (1) that have different molecular weights. By using two or more silane coupling agents that have different molecular weights, the density of the treatment agent on the glass surface tends to increase, and as a result, the reactivity with the matrix resin tends to be further improved.

[0058] (molecular weight) The molecular weight of the surface treatment agent, for example, the molecular weight of the silane coupling agent, is preferably 200 to 900, more preferably 230 to 800, still more preferably 260 to 700, and particularly preferably 300 to 600. If the molecular weight is 900 or less, dispersibility in water tends to be good, and therefore, the occurrence of white spots on the glass cloth is easily suppressed. When two or more surface treatment agents (e.g., silane coupling agents) are used, it is preferable that the weighted average value of the molecular weights of the surface treatment agents, where the weight is the mass of each surface treatment agent, is within the above range, and it is more preferable that the molecular weights of all of the multiple surface treatment agents used are within the above range. For example, when a surface treatment agent is formulated so that silane coupling agents having molecular weights of 300 and 500 are present at 0.5 mass % and 1.0 mass %, the weighted average value is calculated by the following formula: Weighted average value = {(300 x 0.5) / (0.5 + 1.0)} + {(500 x 1.0) / (0.5 + 1.0)} = 433 It is calculated as follows (for ease of explanation, decimal points are omitted):

[0059] [Average opening degree of glass cloth] The average degree of opening of the glass cloth is, for example, 35% or more, preferably more than 40%, more preferably more than 43%, even more preferably more than 46%, more than 50%, more than 53%, more than 56%, or more than 60%, and particularly preferably more than 65%. When the average degree of opening of the glass cloth is more than 35% or 40%, it is easy to prevent air bubbles called voids from remaining in the bundle of glass yarns when a resin substrate is produced, and as a result, it is less likely to have an adverse effect on solder heat resistance, insulation reliability, etc. The silane coupling agent represented by the formula (1) tends to exert relatively strong intermolecular forces, and therefore tends to be less effective in impregnating the glass cloth with the matrix resin than silane coupling agents other than those represented by the formula (1). Therefore, in order to fully obtain the effect of improving the insulation reliability of glass cloth surface-treated with the silane coupling agent represented by the formula (1), it is preferable that the average degree of opening is 35% or more, or exceeds 40%.

[0060] [White spots on glass cloth] White stains (white spots) may be observed on the surface of the surface-treated glass cloth. These white spots tend to repel the matrix resin used in the preparation of the prepreg, which may result in poor appearance of the resulting prepreg and, in turn, poor solder heat resistance and insulation reliability in the resulting resin substrate. It has been previously believed that the cause of these white spots is unknown.

[0061] In this regard, the present inventors have clarified that one of the white spots is an aggregate of a surface treatment agent (for example, a silane coupling agent) or a modified product thereof. In particular, the present inventors have found that the silane coupling agent represented by the above formula (1) has a relatively large molecular weight, and therefore is relatively highly hydrophobic, and therefore tends to easily generate aggregates, and that when the solvent in the surface treatment solution contains water, the frequency of white spots occurring on the glass cloth after surface treatment tends to increase (for example, 10.0 spots / m 2 The above was made clear.

[0062] To suppress white spots, as described below, Mixing the surface treatment solution by a predetermined method; Temperature and pH control of the surface treatment solution, and filtering the surface treatment liquid to remove aggregates in the surface treatment liquid; Techniques such as those described above are suitable.

[0063] The frequency of white spots on glass cloth is 7.0 / m 2 Preferably less than 4.0 pieces / m 2 Less than 2.0 pieces / m is more preferable. 2 Less than or equal to 0.1 pieces / m 2 More preferably, 0.05 particles / m or less 2 The following is particularly preferable. This makes it easy to realize a prepreg with excellent appearance. Theoretically, the frequency of white spots is greater than 0.

[0064] [Glass cloth manufacturing method] One aspect of this embodiment is a manufacturing method for manufacturing the glass cloth of this embodiment. The manufacturing method of this embodiment is as follows: a surface treatment step of treating the glass fiber with a surface treatment liquid containing a surface treatment agent having a molecular weight of 200 or more; The surface treatment process is a step of adding a solvent to a surface treatment agent to prepare a surface treatment liquid; adjusting the temperature of the surface treatment solution; adjusting the pH of the surface treatment solution; and filtering the surface treatment solution; The method includes at least one of the steps.

[0065] Here, the manufacturing method of this embodiment may optionally include the following steps: a step of heating the glass yarn to reduce the amount of fiber sizing agent adhering to the glass yarn (thermal deoiling step); A step of washing the glass filaments with water (washing step), and / or The process of opening glass threads (opening process).

[0066] At least one of the surface treatment step, the opening step, and the cleaning step may be performed on the glass yarn before the step of weaving the glass yarn to obtain a glass cloth (weaving step), or may be performed on the glass cloth after the weaving step. The order of the thermal deoiling step, the surface treatment step, the opening step, and the cleaning step may be reversed. When the cleaning step is performed after the weaving step, the cleaning step can also serve as the opening step by using a high-pressure water spray or the like. The composition of the glass cloth usually does not change before and after opening.

[0067] [Heat deoiling process] In this step, by heating the glass yarn, it is possible to reduce, and preferably remove, any fiber sizing agent (sizing agent) and its residues, as well as modified products thereof, that are attached to the glass yarn. By carrying out the thermal deoiling step, it is possible to form a surface treatment layer on the surface of the glass yarn (glass filament) after reducing organic substances that can increase the dielectric tangent, and therefore it is easy to produce glass cloth with excellent dielectric properties. As a means for thermal deoiling, known means (heating means, heating medium, heating mechanism, heating device, heating component, etc.) can be used.

[0068] One embodiment of the thermal deoiling step is, for example, A method of heating glass cloth at a temperature of 600 to 1600°C. etc. are known.

[0069] In the heat treatment step, by heating a glass cloth greige having a glass yarn softening point of 900°C or higher in a temperature range of 600 to 1600°C, damage to the glass cloth can be easily suppressed and the dielectric loss tangent of the glass cloth can be easily reduced. From the viewpoint of suitably achieving the effects of the present disclosure, the thermal deoiling temperature is preferably 700 to 1500°C, more preferably 800 to 1400°C, even more preferably 900 to 1300°C, and particularly preferably 1000 to 1200°C. When the thermal deoiling temperature is 600°C or higher, sizing agents and the like adhering to the glass cloth greige can be easily removed effectively, making it easy to produce a glass cloth with excellent dielectric properties. When the thermal deoiling temperature is 1600°C or lower, devitrification of the glass can be easily suppressed, and as a result, a decrease in the strength of the glass cloth can be easily prevented.

[0070] The heating time is preferably 30 minutes or less, more preferably 15 minutes or less, even more preferably 5 minutes or less, and particularly preferably 90 seconds or less. Because the heat treatment is performed at a high temperature, a heating time of 30 minutes or less tends to reduce damage to the glass cloth, making it easier to avoid problems such as partial holes being formed in the glass cloth or the glass cloth being cut during processing. From the viewpoint of effectively removing the sizing agent and the like, the heating time may be, for example, 1 second or more, 5 seconds or more, 10 seconds or more, or 15 seconds or more.

[0071] When the thermal deoiling of the glass cloth is carried out in a closed system, it is preferable to place the glass cloth in a heating furnace from the viewpoint of suitable heating by a heating means. Also, from the viewpoint of efficient storage space and heating range, it is preferable to heat the glass cloth while storing it in a rolled state. Furthermore, from the viewpoint of increasing the efficiency of removing organic substances and shortening the time required for removing organic substances, it is preferable to heat the glass cloth while transporting it in the heating furnace. The transportation of the glass cloth can be carried out, for example, by a combination of an unwinding mechanism and a winding mechanism.

[0072] When the thermal deoiling of the glass cloth is carried out in an open system, it is preferable to heat the glass cloth while transporting it, from the viewpoint of ensuring a heated area. The transportation of the glass cloth can be carried out, for example, by a combination of an unwinding mechanism and a winding mechanism.

[0073] The mode of the thermal deoiling step is not limited to the above. As another embodiment of the thermal deoiling step, for example, Heating in a vacuum or gas with a dew point of 15°C or less under conditions where the heating amount, expressed as heating temperature (°C) x heating time (h), is 450 (°C·h) or more (provided that the maximum heating temperature is 100-600°C). etc. are also known.

[0074] (heating means) The heating means may be, for example, a heating furnace, an electric heater, a burner, etc., and among these, a gas single radiant tube burner or an electric heater is preferred. A plurality of different heating means may be combined.

[0075] From the viewpoint of efficiently removing organic matter adhering to the surface of the glass cloth, a continuous system in which the glass cloth is heated by continuously passing it through a heating furnace is preferred over a batch system in which the glass cloth wound around a core is heated at a predetermined atmospheric temperature. A system in which the glass cloth can also be washed continuously using washing water with a low metal ion content, such as reverse osmosis (RO) water or ion-exchanged water, is more preferred.

[0076] Furthermore, from the viewpoint of low running costs, the heating means may be such that the glass cloth is heated by bringing a member (contact member) heated to a predetermined temperature into contact with the glass cloth.

[0077] The contact member is preferably one that can heat the glass cloth at a high temperature. The shape of the contact member is preferably a roll because it allows for easy transport of the glass cloth. Specifically, the contact member is preferably, for example, a roll that can be used in a high-temperature range and heats by an induction heating method, which has relatively little temperature variation in the width direction. When the glass cloth is heated by the contact member, the temperature of the contact member and the surface temperature of the glass cloth are considered to be approximately equal.

[0078] When the glass cloth is continuously heated, in order to remove carbides adhering to the roll, the method using the roll is preferably a method equipped with a mechanism for removing adhering foreign matter, such as a mechanism such as a blade.

[0079] (Means for applying steam) The means for applying the above to the glass cloth (steam application means) may be spraying, shower diffusion, jet nozzle, etc. Alternatively, the gas exhausted from the heating furnace can be reused as high-temperature steam.

[0080] The steam applied to the glass cloth may contain, for example, a volatile solvent, water vapor, or a gas other than water vapor. However, water vapor is preferred from the viewpoint of reducing toxicity to the human body and facilitating decomposition of the sizing agent used in the glass fiber. The temperature of the high-temperature steam may be a temperature at which the surface temperature of the glass cloth is higher than 650°C. In this case, if necessary, a method may be adopted in which the high-temperature steam and heated air can be supplied in any ratio. The temperature of the high-temperature steam may be 400°C or higher, 450°C or higher, 550°C or higher, 600°C or higher, or 650°C or higher.

[0081] [Surface treatment process] In the surface treatment step, the glass filaments are treated with a surface treatment solution containing a surface treatment agent having a molecular weight of 200 or more. Methods for treating glass filaments with a surface treatment solution (for example, methods for applying a surface treatment solution to glass filaments) include: (A) A method in which a glass cloth is transported while being immersed in a surface treatment solution stored in a bath (hereinafter referred to as the "immersion method"); (a) A method of directly applying the surface treatment liquid to the glass cloth using a roll coater, die coater, gravure coater, etc. When the immersion method is employed, the immersion time of the glass cloth in the surface treatment solution is preferably selected to be 0.5 seconds or more and 1 minute or less.

[0082] In the method of this embodiment, in the surface treatment step, the glass fiber is surface treated using a surface treatment agent having a molecular weight of 200 or more, particularly using a silane coupling agent represented by the above formula (1). The silane coupling agent used in the method of this embodiment has a larger molecular weight than general silane coupling agents, and therefore is relatively hydrophobic. As described above, the present inventors have revealed that when the solvent in the surface treatment liquid contains water, aggregates of the surface treatment agent tend to be easily generated, and that when the solvent in the surface treatment liquid contains water, the frequency of occurrence of white spots on the glass cloth after surface treatment tends to increase.

[0083] The present inventors have found that in a surface treatment liquid using a surface treatment agent having a molecular weight of 200 or more, particularly a silane coupling agent represented by the above formula (1), it is possible to form white spots on a glass cloth by taking the following measures (A) to (C): (A) Adding a solvent (e.g., a weakly acidic aqueous solution as a mother liquor) to the surface treatment agent in small amounts; (B) controlling the temperature and / or pH of the surface treatment solution during the surface treatment; (C) Filtering the surface treatment solution during surface treatment.

[0084] (A) Preparation of surface treatment solution Since typical silane coupling agents have excellent compatibility with and dispersibility in water, they are prepared by adding the silane coupling agent in small amounts to weakly acidic water with a pH of about 3 to 5 while stirring. On the other hand, in the method of this embodiment, a pre-solution of the surface treatment agent can be obtained by adding a small amount of surfactant and a solvent (e.g., a 60% aqueous acetic acid solution) to a diluted solution obtained by diluting the surface treatment agent with a small amount of methanol. The solvent added to the pre-solution is added to hydrolyze the alkoxide groups of the silane coupling agent, and the amount of solvent added is preferably adjusted according to the amount of hydrolysis. Then, an aqueous solution adjusted to a pH of 3 to 4 (also referred to as the "mother liquor" in the present disclosure) is added little by little to the pre-solution while stirring, thereby uniformly dispersing the surface treatment agent in the aqueous solution. In this case, it is easy to suppress agglomerations in the surface treatment solution.

[0085] The surfactant may be selected from a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant, and different types of surfactants may be used in combination.

[0086] The amount of the surfactant is preferably 0.2 to 10 mass % relative to the surface treatment agent (for example, silane coupling agent), more preferably 0.4 to 9 mass %, even more preferably 0.6 to 8 mass %, and particularly preferably 1 to 6 mass %. When the amount of the surfactant satisfies the above range, it becomes easier to uniformly disperse the silane coupling agent.

[0087] Examples of nonionic surfactants include glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polyoxypropylene glycols, fatty acid polyethylene glycols, fatty acid polyoxyethylene sorbitan, and fatty acid alkanolamides.

[0088] Examples of anionic surfactants include fatty acid monocarboxylates, polyoxyethylene alkyl ether carboxylates, N-acylsarcosinates, N-acylglutamates, dialkyl sulfosuccinates, alkanesulfonates, alpha-olefin sulfonates, linear alkylbenzenesulfonates, alkylbenzenesulfonates, naphthalenesulfonate-formaldehyde condensates, alkylnaphthalenesulfonates, N-methyl-N-acyltaurates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fat and oil sulfate esters, alkyl phosphates, polyoxyethylene alkyl ether phosphates, and polyoxyethylene alkyl phenyl ether phosphates.

[0089] Examples of cationic surfactants include monoalkylamine salts, dialkylamine salts, trialkylamine salts, alkyltrimethylammonium chloride, and alkylbenzalkonium chloride.

[0090] Examples of amphoteric surfactants include 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, alkyl betaine, fatty acid amidopropyl betaine, alkyldiethylenetriaminoacetic acid, and alkylamine oxide.

[0091] (B) Temperature control and / or pH control of the surface treatment solution From the viewpoint of suppressing aggregation in the surface treatment liquid, the temperature of the surface treatment liquid is preferably controlled at 10 to 30°C, more preferably at 13 to 27°C, even more preferably at 15 to 25°C, and particularly preferably at 17 to 23°C during the surface treatment process.

[0092] Furthermore, during the surface treatment process, the pH of the surface treatment solution may fluctuate due to trace amounts of impurities such as alkali metals contained in the glass cloth. From the viewpoint of suppressing agglomeration in the surface treatment solution, it is preferable to minimize the pH fluctuation range of the surface treatment solution. During the surface treatment process, the pH of the surface treatment solution is preferably controlled to be between 2.5 and 5.5, more preferably between 2.8 and 5.2, and even more preferably between 3.0 and 5.0. Examples of methods for controlling the pH within a predetermined range include bubbling carbon dioxide into the surface treatment solution.

[0093] Either one of the temperature control and the pH control of the surface treatment liquid may be performed, or both may be performed. From the viewpoint of suitably suppressing the formation of aggregates in the surface treatment liquid, it is preferable to perform both the temperature control and the pH control of the surface treatment liquid.

[0094] Here, "temperature control of the surface treatment liquid" is a concept that includes not only an operation of increasing and / or decreasing the temperature of the surface treatment liquid, but also an operation of maintaining the temperature of the surface treatment liquid at a predetermined value, and an operation of detecting the temperature of the surface treatment liquid to confirm whether the temperature is within a predetermined range. Furthermore, the concept of "pH control of the surface treatment solution" includes not only an operation for increasing and / or decreasing the pH of the surface treatment solution, but also an operation for maintaining the pH of the surface treatment solution at a predetermined value, and an operation for detecting the pH of the surface treatment solution to determine whether the pH is within a predetermined range.

[0095] (C) Filtration of surface treatment solution From the viewpoint of reliably collecting the aggregates in the surface treatment solution, it is preferable to filter the surface treatment solution while the surface treatment process is being carried out. At this time, it is preferable to collect the aggregates that may be generated in the surface treatment solution by filtration while circulating the surface treatment solution.

[0096] From the viewpoint of increasing the efficiency of collecting the aggregates, it is preferable to perform filtration in multiple stages. For example, two-stage filtration is preferable, in which the aggregates are first removed using a filter with a relatively coarse mesh, and then the surface treatment liquid is filtered again using a filter with a finer mesh than the primary filter. Such multiple-stage filtration makes it easy to prevent clogging of the filter, and as a result, it is easy to avoid interruptions in the glass cloth production process.

[0097] (drying process) The surface treatment process is a step of applying a surface treatment liquid to the glass filament and then drying the solvent contained in the surface treatment liquid (drying step); It may further include: The drying step makes it easy to fix the surface treatment agent to the surface of the glass yarn (surface of the glass filaments), and in particular makes it easy to fix the surface treatment agent to the surface of each individual glass yarn (surface of each individual glass filament). Examples of methods for drying the solvent include known methods such as drying by heating, specifically, methods of heating and drying by hot air, electromagnetic waves, etc.

[0098] The drying temperature is preferably 80° C. or higher, more preferably 90° C. or higher, from the viewpoint of sufficiently reacting the surface treatment agent with the glass, and is preferably 300° C. or lower, more preferably 180° C. or lower, from the viewpoint of preventing deterioration of the organic functional groups of the surface treatment agent.

[0099] [Opening process] The manufacturing method of this embodiment preferably includes a fiber-opening step after the surface treatment step. Examples of the spreading method in the spreading step include spreading the glass cloth with spray water (high-pressure water spreading), a vibro washer, ultrasonic water, a mangle, or the like. By reducing the tension applied to the glass cloth during this spreading process, the width of the glass yarns can be easily increased and the surface treatment agent that has not chemically bonded to the glass surface can be easily removed to some extent. In order to prevent a decrease in the tensile strength of the glass cloth due to the spreading process, it is preferable to take measures such as reducing the friction of contacting members when weaving the glass yarns, optimizing the sizing agent and increasing the amount of adhesion.

[0100] In the spreading step, it is preferable to spread the glass fiber bundles using a plurality of spreading methods, which makes it easy to control the average spread degree of the glass cloth within a predetermined range even if the glass cloth tends to have poor impregnation with a matrix resin.

[0101] [Cleaning process] The washing step (finish washing step) is preferably a method capable of reducing the residue of the surface treatment agent that has not formed a chemical bond with the surface of the glass filaments, modified substances, etc., such as a method of washing the glass filaments with an organic solvent. By carrying out the washing step, even if a glass raw material with a high silicon (Si) content, such as quartz glass, is used, it becomes easy to adjust the difference between the dielectric loss tangent and bulk dielectric loss tangent of the obtained glass cloth to within a predetermined range.

[0102] In the washing step, washing with a highly hydrophobic organic solvent is preferred in order to reduce the above-mentioned residues that are difficult to reduce with water, and washing with an organic solvent that has a high affinity for silane coupling agent residues having hydroxyl groups is also preferred. Examples of the washing method include known methods such as immersion and shower spraying, and washing may be performed while heating or cooling as necessary. In order to prevent the dissolved deposits from re-adhering to the glass cloth, it is preferable to reduce the excess solvent from the washed glass cloth using a squeeze roller or the like before finish drying. Suitable organic solvents, for example, highly hydrophobic organic solvents, include: saturated chain aliphatic hydrocarbons such as n-pentane, i-pentane, n-hexane, i-hexane, n-heptane, i-heptane, n-octane, i-octane, 2,2,4-trimethylpentane (isooctane), n-nonane, i-nonane, n-decane, i-decane, and 2,2,4,6,6-pentamethylheptane (isododecane); saturated cyclic aliphatic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, and ethylcyclohexane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, diethylbenzene, trimethylbenzene, and triethylbenzene; Halogen-containing solvents such as chloroform, dichloromethane, and dichloroethane; etc.

[0103] Examples of organic solvents that have a high affinity with modified surface treatment agents (e.g., silane coupling agents) include: Alcohols such as methanol, ethanol, butanol, etc.; ketones such as acetone and methyl ethyl ketone; ethers such as methyl ethyl ether and diethyl ether; Amides such as N,N-dimethylformamide and N,N-dimethylacetamide; Dimethyl sulfoxide; etc.

[0104] Among the above, aromatic hydrocarbons, alcohols or ketones are preferred, and methanol or toluene is more preferred, from the viewpoint of easily adjusting the difference between the dielectric loss tangent and bulk dielectric loss tangent of the resulting glass cloth to fall within a predetermined range.

[0105] The manufacturing method of this embodiment preferably includes a step of drying the washed glass cloth (post-washing drying step) in order to reduce the amount of organic solvent after washing, and from the viewpoint of facilitating reduction of the organic solvent by drying, the organic solvent used for washing preferably has a boiling point of 120° C. or less. Known methods such as heat drying and air drying can be used to dry the organic solvent.

[0106] When heat drying is performed to reduce the amount of organic solvent in the post-wash drying step, hot air drying using low-pressure steam or heat transfer oil as a heat source is preferred from a safety standpoint. The drying temperature is preferably equal to or higher than the boiling point of the washing solvent, and is preferably 180°C or lower from the standpoint of suppressing deterioration of the silane coupling agent.

[0107] [Optional step] The manufacturing method of this embodiment may optionally include other steps in addition to the steps described above. Other steps include, for example, a step of processing the glass cloth into slits (slit processing step).

[0108] (Inspection process or measurement process) In addition, other processes include: Inspecting the glass cloth for white spots; and measuring the height of the peak derived from the carbonyl group in the glass cloth using Fourier transform infrared spectroscopy; At least one of the steps above can be mentioned. The manufacturing method of this embodiment includes such a step, which makes it easy to realize the glass cloth of this embodiment.

[0109] [Test method] Another aspect of this embodiment is a test method for a glass cloth made by weaving glass yarns. The glass cloth to be tested is surface-treated with a surface treatment agent, The above test method is The method includes a step of inspecting the glass cloth for white spots based on the peak height derived from the carbonyl group in the glass cloth and the total carbon content of the glass cloth or the ignition loss value of the glass cloth.

[0110] In the test method of this embodiment, the glass cloth to be tested, the peak height derived from carbonyl groups, the total carbon content, the ignition loss value, and the white spots may be determined by referring to the descriptions in the above section [Glass Cloth]. According to the test method of this embodiment, it is possible to evaluate the properties of the glass cloth based on the white spots noticed by the inventors.

[0111] [Prepreg] The prepreg of this embodiment contains glass cloth, a matrix resin, and an inorganic filler. The prepreg of this embodiment can be made by using the glass cloth of this embodiment as the glass cloth. This provides a prepreg with excellent properties (for example, a prepreg with few voids).

[0112] The matrix resin may be either a thermosetting resin or a thermoplastic resin, and may be used in combination with a thermosetting resin and a thermoplastic resin.

[0113] Examples of thermosetting resins include: a) an epoxy resin obtained by reacting a compound having an epoxy group with a compound having at least one group reactive with the epoxy group, such as an amino group, a phenol group, an acid anhydride group, a hydrazide group, an isocyanate group, a cyanate group, or a hydroxyl group, without a catalyst or with the addition of a catalyst having a reaction catalytic ability, such as an imidazole compound, a tertiary amine compound, a urea compound, or a phosphorus compound, followed by curing; b) a radical polymerization type curable resin obtained by curing a compound having at least one of an allyl group, a methacryl group, and an acrylic group using a thermal decomposition type catalyst or a photodecomposition type catalyst as a reaction initiator; 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 mixture; d) a thermosetting polyimide resin obtained by reacting and curing a maleimide compound with an amine compound; e) a benzoxazine resin obtained by crosslinking and curing a compound having a benzoxazine ring through thermal polymerization; Examples include:

[0114] Examples of thermoplastic resins include polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyether sulfone, polyarylate, aromatic polyamide, polyether ether ketone, thermoplastic polyimide, insoluble polyimide, polyamide imide, LCP, polyester, and fluororesin.

[0115] Since an acryloyl group or a methacryloyl group has good reactivity, it is preferable to use at least one of polyphenylene ether and modified polyphenylene ether as the matrix resin.

[0116] The prepreg may contain an inorganic filler. Examples of the inorganic filler include aluminum hydroxide, zirconium oxide, calcium carbonate, alumina, mica, aluminum carbonate, magnesium silicate, aluminum silicate, silica, talc, short glass fiber, aluminum borate, and silicon carbide. The inorganic filler may be used in combination with the thermosetting resin.

[0117] [Printed wiring board] The printed wiring board of this embodiment includes a prepreg. In particular, the printed wiring board of this embodiment includes the prepreg of this embodiment as the prepreg. This can provide a printed wiring board with excellent properties (for example, a printed wiring board with excellent insulation reliability).

[0118] [Integrated circuits and electronic devices] The integrated circuit of this embodiment includes the printed wiring board of this embodiment. Also, the electronic device of this embodiment includes the printed wiring board of this embodiment. These provide an integrated circuit and electronic device with various excellent characteristics. [Example]

[0119] The present embodiment will be described below with reference to examples and comparative examples. However, the present embodiment is not limited to the following examples. Regarding the examples and comparative examples, various productions, measurements, evaluations, etc. were carried out by the following methods.

[0120] [Thickness] In accordance with 7.10 of JIS R 3420, a micrometer was used to gently rotate the spindle, bringing it into light contact parallel to the measurement surface, and the scale was read after the ratchet made three clicks. JIS R 3420 also specifies general test methods for long glass fibers and products such as glass cloth that use long glass fibers.

[0121] [Metsuke] The glass cloth was cut to a predetermined size to obtain a sample. The mass of the sample was divided by the area of ​​the sample to determine the basis weight. Here, the glass cloth was cut to a size of 10 cm x 10 cm to obtain a sample, and the mass was measured to determine the basis weight (g / m 2 ) was sought.

[0122] [Converted thickness] Since glass cloth is a discontinuous planar body made of air and glass, the converted thickness required for measurement by the resonance method was calculated by dividing the basis weight of each glass cloth by the density of the glass. The calculation formula is as follows: Converted thickness (μm) = basis weight (g / m 2 ) / Glass density (g / cm 3 ) As follows.

[0123] [Dielectric loss tangent] The dielectric loss tangent of each glass cloth was measured in accordance with IEC 62562. Specifically, glass cloth samples were sampled to the size required for measurement with each split cylinder resonator and stored in a constant temperature and humidity oven at 23°C and 50% RH for 8 hours to condition the humidity. The dielectric properties were then measured at 10 GHz using a split cylinder resonator (EM Lab) and an impedance analyzer (Agilent Technologies). Measurements were performed five times for each sample, and the average value was calculated. The thickness of each sample was calculated using the equivalent thickness. IEC 62562 specifies a method for measuring the dielectric properties of fine ceramic materials for dielectric substrates, primarily used in microwave circuits, in the microwave band.

[0124] A 300 μm thick glass plate having the same type and composition as each glass cloth for which the dielectric loss tangent was measured was prepared. The thickness obtained from the thickness measurement of the glass plate was used to measure the bulk dielectric loss tangent at 10 GHz in the same manner as in the measurement of the dielectric loss tangent.

[0125] [Ignition loss value] The ignition loss value of the glass loss was determined in accordance with JIS R3420. Specifically, the glass cloth was dried at a temperature of 110°C ± 5°C for 60 minutes. The test piece was then transferred to a desiccator and allowed to cool at room temperature for 20 minutes, after which the mass of the test piece was measured to the nearest 0.1 mg (A mg). The dried test piece was then heat-treated at a temperature of 625°C ± 20°C for 20 minutes. The test piece was then transferred to a desiccator and allowed to cool for 20 minutes, after which the mass of the test piece was measured to the nearest 0.1 mg (B mg). The ignition loss value was calculated using the following formula, rounded to the fourth decimal place, and expressed to the third decimal place. Ignition loss (%) = [{A (mg) - B (mg)} / A (mg)] x 100

[0126] [Average opening degree] The opening degree of the warp yarn of the glass cloth is calculated by the following formula: Warp opening rate (%) = [warp width (μm) / {number of warp filaments × warp filament diameter (μm)}] × 100 It was calculated by: The degree of opening of the weft yarn of the glass cloth was calculated using the following formula: Weft opening rate (%) = [weft width (μm) / {number of weft filaments × weft filament diameter (μm)}] × 100 It was calculated by:

[0127] Using the calculated warp yarn opening rate (%) and weft yarn opening rate (%), the following formula: Average opening rate (%) = {opening rate of warp yarn (%) + opening rate of weft yarn (%)} / 2 The average degree of opening was calculated by the above.

[0128] (Number of warp and weft filaments, and filament diameter) In calculating the average degree of opening, the number of filaments in the warp and weft yarns was determined by observing a cross-sectional image of the glass yarn. Specifically, a cross-sectional image of the glass yarn as the warp yarn (or the weft yarn) was obtained, and the number of filaments and the filament diameter of the warp yarn (or the weft yarn) were measured in the cross-sectional image. Similarly, image acquisition of the glass yarn and measurement of the number of filaments were repeated, and the average values ​​of the five measurements obtained were used as the number of filaments and filament diameter of the warp (or weft).

[0129] (Warp width and weft width) In calculating the average degree of opening, the warp width and the weft width were determined by the following method. First, five glass cloth test pieces each measuring 70 mm in the warp direction and 70 mm in the weft direction were cut out from the glass cloth. Each cut specimen was observed vertically using a macroscope at 100x magnification. For each specimen, the widths of 250 warp (or weft) yarns were randomly measured, and the average value of the widths of the 250 warp (or weft) yarns was calculated. The calculated average value was used as the warp width (or weft width).

[0130] [Total carbon content] The glass cloth was cut into a square shape with a mass of approximately 80 mg. The cut glass cloth was heated at approximately 800°C for 1 minute, and the amount of carbon dioxide in the generated gas was measured by gas chromatography to determine the amount of carbon dioxide in the generated gas. In addition, the amount of carbon dioxide generated when acetanilide (C8H9NO) having a specified mass W (mg) was heated at approximately 800°C for 1 minute was also determined. The amount of carbon dioxide was measured using SUMIGRAPH NC-TR22 (manufactured by Sumika Chemical Analysis Center Co., Ltd.). The molecular weight and carbon ratio of acetanilide were determined as follows: Molecular weight of acetanilide = 135.17 Carbon percentage of acetanilide = 71.09% was used.

[0131] The total carbon content per mass of the glass cloth is calculated using the following formula: Total carbon content (mass%) = [{mass of acetanilide W (mg) × (carbon ratio of acetanilide / 100)} / peak area due to carbon dioxide generated from acetanilide] × [{peak area of ​​carbon dioxide generated from glass cloth / mass of glass cloth (mg)} × 100] It was calculated based on the following.

[0132] The position from which the glass cloth was cut was changed, and the total carbon amount was measured for each of the resulting 10 different samples, and the average value was used as the total carbon amount.

[0133] [Making heat cloth] Follow steps 1 to 3 below: Procedure 1: The glass cloth was heated at 615°C for 1 hour to remove oil. Procedure 2: After procedure 1, the ignition loss of the glass cloth was measured. Procedure 3: If the ignition loss value obtained in Procedure 2 exceeded 0.01% by mass, Procedure 1 was repeated (Procedures 1 and 2 were repeated until the ignition loss value obtained in Procedure 2 became 0.01% by mass or less). By carrying out the above steps, a heat cloth from which the surface treatment agent had been removed was obtained.

[0134] [Carbonyl group peak height] Using a glass cloth and the heat cloth obtained by the above method, the peak height derived from the carbonyl group contained in the surface treatment agent attached to the glass cloth was measured by Fourier transform infrared spectroscopy. The measuring device and measuring method are as follows.

[0135] (Measurement equipment: Fourier transform infrared spectrophotometer (FT-IR)) Model: Agilent Technologies, Inc. variant 670-IR Measurement method: transmission method Accumulation count: 64 times Wavenumber resolution: 4cm ―1 Measurement wave number: 400cm -1 ~4000cm -1

[0136] (Measurement method) (1) Variant 670-IR was calibrated and preparations were made for transmission measurements. (2) Four heat cloths were stacked to form a sample, which was then fixed in a holder and set on the sample stage inside the apparatus, and the infrared spectrum of the heat cloths was measured by the transmission method. (3) Four sheets of glass cloth were stacked to form a sample, and the infrared spectrum of the glass cloth was measured by the transmission method in the same manner as in (2) above. (4) From the results of (2) and (3) above, the difference spectrum of the infrared spectrum was obtained.

[0137] (5) From the difference spectrum obtained in (4) above, 1600 cm ―1 ~1900cm ―1 The height of the peak derived from the carbonyl group present in the range was determined. The peak height derived from the carbonyl group was then divided by the number of stacked glass cloths (four in this example) to determine the peak height per glass cloth.

[0138] Here, the baseline was obtained in accordance with the baseline drawing method described in JIS K 0117:2017. Specifically, as shown in Figure 18 d) described in JIS K 0117:2017, a tangent line was drawn to two base points (in this example, the base point located on the right side of the peak derived from the carbonyl group in (5) above and the base point located on the left side), and this was treated as the baseline. The difference between the baseline and the peak top was then obtained as the height of the peak derived from the carbonyl group.

[0139] (6) The above operations (2) to (5) were carried out in the same manner using a heat cloth and a sample obtained by the following method. A calibration curve was obtained, plotting the total carbon content (mass%) or ignition loss (mass%) of the sample (x-axis) against the peak height of the carbonyl group per glass cloth (y-axis). The calibration curve passed through the origin and was approximated as a straight line.

[0140] Fig. 1 shows the calibration curve L prepared in this example. Fig. 1(a) shows the relationship between peak height and total carbon content, and Fig. 1(b) shows the relationship between peak height and ignition loss.

[0141] (7) In the calibration curve obtained in (6) above, the y-axis value (peak height derived from carbonyl groups) when the total carbon content or ignition loss value of the sample was 0.1% by mass was set to 1.00. The "peak height per glass cloth" obtained in (5) above was calculated using the following formula: "Peak height per glass cloth" after relative value conversion = ("Peak height per glass cloth" before relative value conversion x 1.00) / Peak height of sample (when the total carbon content or ignition loss value is 0.1 mass%) The relative values ​​were calculated according to the following formula: The "peak height per glass cloth" after the relative value calculation was calculated. In the formula, the "peak height per glass cloth" before conversion into a relative value is the "peak height per glass cloth" obtained in (5) above.

[0142] (8) Using the total carbon content or ignition loss value of the glass cloth treated as a sample in (3) above and the relative value-converted "peak height per glass cloth" obtained in (7) above, the following value is calculated using the following formula: Value A = Peak height per glass cloth / Total carbon content of glass cloth (mass%) Value B = Peak height per glass cloth / Ignition loss value of glass cloth (mass%) were calculated respectively.

[0143] (9) The number of overlapping glass cloths was changed to 5, and the operations (1) to (8) above were repeated. In this case, the number of overlapping heat cloths in (2) above was 5, and the number of overlapping specimen samples in (6) above was 5. As a result, values ​​A and B when the number of glass cloths was 5 were obtained.

[0144] (10) In addition, the number of overlapping glass cloths was changed to six, and the operations (1) to (8) above were repeated. In this case, the number of overlapping heat cloths in (2) above was six, and the number of overlapping specimen samples in (6) above was six. As a result, values ​​A and B when the number of glass cloths was six were obtained.

[0145] (11) The difference spectrum obtained when the number of glass cloths was four, the difference spectrum obtained when the number of glass cloths was five, and the difference spectrum obtained when the number of glass cloths was six were compared. Then, the number of glass cloths that gave the difference spectrum with the least distortion in the shape of the difference spectrum was specified, and the values ​​A and B obtained for that number of glass cloths were used as the evaluation values.

[0146] In this example, steps (1) to (11) were performed, but as long as the measurement results are not affected, any steps that can be omitted may be omitted, and the order of steps may be reversed.

[0147] [Specimen sample] Glass yarns with a SiO2 content of over 99.9% by mass (average filament diameter 5.0 μm, 100 filaments, 1.0 twist) were used for the warp and weft. An air jet loom was used to obtain a glass cloth with a weave density of 66 warp / 25 mm and 68 weft / 25 mm. The resulting glass cloth was deoiled by heating at 1000°C for 20 seconds. The glass cloth was then immersed in a surface treatment solution containing purified water adjusted to pH 3 with acetic acid and a silane coupling agent (5-hexenyltrimethoxysilane; Z6161 (Dow-Toray Industries, Inc.) and 3-methacryloxypropyltrimethoxysilane; Z6030 (Dow-Toray Industries, Inc.)). After immersion, the glass cloth was removed and heated and dried at 110°C for 1 minute, thereby completing the surface treatment with the silane coupling agent. In this way, a sample glass cloth was prepared.

[0148] The total mass% of the silane coupling agent in the surface treatment solution was adjusted while the mass ratio of 5-hexenyltrimethoxysilane:3-methacryloxypropyltrimethoxysilane was fixed at 1.00:2.83 so that the total carbon content of the sample samples was 0.05 mass%, 0.07 mass%, 0.1 mass%, 0.12 mass%, and 0.15 mass%. Glass cloths with adhesion amounts of silane coupling agent roughly close to the five points on the calibration curve were then produced.

[0149] [Glass Cloth P] The warp and weft yarns were composed of glass yarns with an SiO2 composition of more than 99.9% by mass. Specifically, the warp and weft yarns used were glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and a twist of 1.0Z. Then, using an air jet loom, 2000 m of glass cloth with a plain weave structure was woven with a weave density of 66 warp yarns / 25 mm and 68 weft yarns / 25 mm, and a cloth width of 1300 mm. The bulk dielectric loss tangent of the glass constituting the glass yarns used was 0.00020 at 10 GHz.

[0150] [Glass Cloth Q] The warp and weft yarns were composed of glass yarns with an SiO2 composition of more than 99.9% by mass. Specifically, the warp and weft yarns used were glass yarns with an average filament diameter of 5.0 μm, 200 filaments, and a twist of 1.0Z. Then, using an air jet loom, 2000 m of glass cloth with a plain weave structure was woven, with a warp density of 54 / 25 mm and a weft density of 54 / 25 mm, and a cloth width of 1300 mm. The bulk dielectric loss tangent of the glass constituting the glass yarns used was 0.00020 at 10 GHz.

[0151] [Glass Cloth R] The warp and weft yarns were composed of glass yarns with an SiO2 composition of more than 99.9% by mass. Specifically, the warp and weft yarns used were glass yarns with an average filament diameter of 4.0 μm, 50 filaments, and a twist of 1.0Z. Then, using an air jet loom, 2000 m of glass cloth with a plain weave structure was woven with a warp density of 95 / 25 mm and a weft density of 95 / 25 mm, and a cloth width of 1300 mm. The bulk dielectric loss tangent of the glass constituting the glass yarns used was 0.00020 at 10 GHz.

[0152] [Preparation of surface treatment solution] The surface treatment liquid was prepared according to the following methods 1) to 5). 1) The silane coupling agent was weighed. 2) Methanol in the same amount as that weighed out in 1) above was mixed with the silane coupling agent weighed out in 1) above to prepare a silane coupling agent solution. 3) The silane coupling agent solution was mixed with 0.8% by mass of polyoxyethylene alkyl ether relative to the silane coupling agent and stirred. After stirring for 1 minute, an aqueous solution of acetic acid (concentration: 60% by mass) at 20% by mass relative to the silane coupling agent was added to the silane coupling agent solution. This hydrolyzed the silane coupling agent. 4) A mother liquor of an aqueous acetic acid solution (pH = 3 to 4) was prepared. The silane coupling agent solution (pre-solution) obtained in 3) above was stirred for 15 minutes at room temperature of 20 to 25°C. The mother liquor was then added dropwise to the stirred silane coupling agent solution, thereby dispersing the silane coupling agent. The amount of mother liquor added (dropping rate) was set so that the entire amount of mother liquor was added in 10 minutes. 5) After step 4), the silane coupling agent solution was stirred at room temperature of 20 to 25° C. for 2 hours to obtain a surface treatment liquid.

[0153] In one embodiment, the "solvent" in the "step of adding a solvent to a surface treatment agent to prepare a surface treatment liquid" of the present disclosure is the mother liquid. Here, an example of the mother liquid is a weakly acidic aqueous solution with a pH of 3 to 4, which is added for the purpose of dispersing the hydrolyzed silane coupling agent. It is defined as follows.

[0154] [Examples and Comparative Examples] Example 1 The glass cloth P was washed with ion-exchanged water and then dried. This removed alkali metal ions and the like adhering to the surface of the glass cloth. Thereafter, the glass cloth P was heated at 1000°C for 15 seconds to perform thermal deoiling (thermal deoiling step).

[0155] A surface treatment liquid was prepared by the above method using 1,1'-[2-[[(2-Methyl-1-oxo-2-propen-1-yl)oxy]methyl]-2-[6-(trimethoxysilyl)hexyl]-1,3-propanediyl] bis(2-methyl-2-propenoate) (CAS NO: 1248412-07-8, Silane Coupling Agent A) as the silane coupling agent, so that the concentration of the silane coupling agent in the surface treatment liquid was 0.5 mass%.

[0156] The glass cloth after heat deoiling was immersed in the obtained surface treatment solution. Then, excess surface treatment solution was squeezed out with an NBR rubber roll at a pressure of 0.22 MPa. Thereafter, the glass cloth was heated and dried at 135°C for 1 minute, thereby fixing the silane coupling agent to the surface of the glass cloth.

[0157] In this example, during the surface treatment of the glass cloth, temperature control (e.g., cooling) was performed so that the temperature of the surface treatment liquid was in the range of 17 to 23° C. Furthermore, during the surface treatment of the glass cloth, carbon dioxide was bubbled into the surface treatment liquid so that the pH of the surface treatment liquid was in the range of 3.0 to 4.0.

[0158] In this example, the surface treatment solution used for the surface treatment of the glass cloth was filtered using an HDCII filter (manufactured by Nippon Pall Co., Ltd.). That is, the surface treatment solution was first passed through a filter with a mesh size of 10 μm, and then passed through a filter with a mesh size of 4.5 μm. This allowed for the collection of aggregates that may be present in the surface treatment solution. The filtered surface treatment solution was used for the surface treatment of the glass cloth.

[0159] After surface treatment, the spray nozzle was used to spray 5.0 kg / cm onto the glass cloth. 2 Then, in water, the fiber was opened at a frequency of 25 kHz and an output of 0.60 W / cm. 2 The glass cloth was further opened by irradiating it with ultrasonic waves at 1000 Hz, reducing the excess silane coupling agent that had physically adhered to the glass cloth. It was then dried by heating at 130°C for 1 minute. The glass cloth was then immersed in toluene for a final wash, reducing the amount of modified silane coupling agent that had not formed a chemical bond with the surface of the glass filaments. As a result, 2,000 m of surface-treated glass cloth was obtained.

[0160] Example 2 A surface-treated glass cloth of 2000 m was obtained in the same manner as in Example 1, except that acrylic acid, [[2-[(trimethoxysilyl)methoxy]ethyl]imino]diethylene ester (CAS NO: 3390-52-1, silane coupling agent B) was used as the silane coupling agent and the concentration of silane coupling agent B was set to 0.8 mass%.

[0161] Example 3 A surface-treated glass cloth (2000 m) was obtained in the same manner as in Example 2, except that 2-Propenoic acid, 1,1'-[2-(8,8-dimethoxy-3-oxo-2,9-dioxa-6-thia-8-siladec-1-yl)-2-[[(1-oxo-2-propen-1-yl)oxy]methyl]-1,3-propanediyl] ester (CAS NO: 1801441-80-4, silane coupling agent C) was used as the silane coupling agent.

[0162] Example 4 A surface-treated glass cloth (2000 m) was obtained in the same manner as in Example 2, except that 1,1'-[2-Methyl-2-[[[[3-(trimethoxysilyl)propyl]amino]carbonyl]amino]-1,3-propanediyl] di-2-propenoate (CAS NO: 1239892-42-2, silane coupling agent D) was used as the silane coupling agent.

[0163] Example 5 A surface-treated glass cloth of 2000 m was obtained in the same manner as in Example 2, except that 2-Propenoic acid, 2-methyl-, 1-[(trimethoxysilyl)methyl]-1,2-ethanediyl ester (CAS NO: 143414-45-3, silane coupling agent E) was used as the silane coupling agent.

[0164] Example 6 As the silane coupling agent, 1,1'-[2-[[2-(9,9-Dimethoxy-4-oxo-3,10-dioxa-5-aza-9-silaundec-1-yl)-11,11-dimethoxy-1,6-dioxo-5,12-dioxa-2,7-diaza-11-silatridec-1-yl]amino]-2-methyl-1,3-propanediyl] di-2-propenoate (CAS NO: 1558048-41-1, silane coupling agent F) was used. In the same manner as in Example 2, except that a surface-treated glass cloth of 2000 m was obtained.

[0165] Example 7 2000 m of surface-treated glass cloth was obtained in the same manner as in Example 1, except that glass cloth Q was used and the silane coupling agents A and B were used at concentrations of 0.4% by mass each, for a total of 0.8% by mass.

[0166] Example 8 A surface-treated glass cloth of 2000 m was obtained in the same manner as in Example 1, except that Glass Cloth R was used and the concentration of Silane Coupling Agent A was set to 0.8 mass %.

[0167] Example 9 After the surface treatment, 2000 m of surface-treated glass cloth was obtained in the same manner as in Example 1, except that high-pressure spreading using a spray nozzle was not carried out.

[0168] Example 10 After surface treatment, spray with 2.5 kg / cm 2 A surface-treated glass cloth of 2000 m was obtained in the same manner as in Example 1, except that the fibers were opened at a high pressure of 1000 psi.

[0169] Example 11 A surface-treated glass cloth of 2000 m was obtained in the same manner as in Example 1, except that the silane coupling agents used were silane coupling agent A and 3-(methacryloyloxy)propyltrimethoxysilane (CAS NO: 2530-85-0, silane coupling agent G), each of which had a concentration of 0.4 mass%, for a total of 0.8 mass%.

[0170] (Comparative Example 1) A surface-treated glass cloth of 2000 m was obtained in the same manner as in Example 2, except that silane coupling agent G was used.

[0171] (Comparative Example 2) A surface-treated glass cloth of 2000 m was obtained in the same manner as in Example 1, except that a surface treatment liquid was prepared by dropping a silane coupling agent solution into a mother liquor of an aqueous acetic acid solution under stirring, that the surface treatment liquid was not filtered but the surface treatment of the glass cloth was carried out, that the surface treatment liquid was not cooled even when the temperature of the surface treatment liquid exceeded 23°C, and that carbon dioxide bubbling was not carried out even when the pH exceeded 4.0.

[0172] (Comparative Example 3) A surface-treated glass cloth of 2000 m was obtained in the same manner as in Example 2, except that 3-acryloxypropyltrimethoxysilane (CAS NO: 4369-14-6, silane coupling agent H) was used as the silane coupling agent.

[0173] [Frequency of white spots] The frequency of occurrence of white spots on the surface of the glass cloth was evaluated by irradiating glass cloth of A4 size (210 mm × 297 mm) or more with a halogen lamp. When observing a sheet-like glass cloth, the halogen lamp was placed directly above the glass cloth, and the number of white spots was calculated by the following formula while changing the direction of observation of the glass cloth: White spot occurrence frequency (pieces / m 2 ) = Number of white spots / {Area of ​​glass cloth (m 2 )} The frequency of occurrence of white spots was calculated according to the following. In addition, in the case of observing a glass cloth roll, a tension of 100 N / 1300 mm was applied to the glass cloth on a roll-to-roll inspection table, and the number of white spots on the glass cloth was counted over a length of 2000 m while irradiating it with a halogen lamp. Then, the inspection area and the number of white spots found in the inspection were calculated using the following formula: White spot occurrence frequency (pieces / m 2 ) = Number of white spots / {Width of glass cloth (m) × Inspected length of glass cloth (m)} The frequency of occurrence of white spots was calculated according to the following.

[0174] Figure 2 is a photograph for explaining the "white spot" in this example. Of these, Figure 2(a) shows a photograph of a location without a white spot, and Figure 2(b) shows a photograph of a location with a white spot P. In this example, a white outline was observed by irradiating the sample with UV light, and the area enclosed by the outline (the area including the outline) was 0.8 cm 2 The defects are defined as "white spots", where the contour is, for example, circular. The area enclosed by the contour line was calculated using known image analysis software.

[0175] [Prepreg manufacturing method] 45 parts by mass of polyphenylene ether (SABIC, Noryl 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. The glass cloths obtained in the Examples and Comparative Examples were impregnated with the prepared varnish and then dried at 115°C for 1 minute to obtain prepregs.

[0176] [Method for manufacturing resin substrate] The obtained prepreg was sampled to a size of 20 cm x 20 cm. Eight of the obtained samples were stacked, and copper foil with a thickness of 12 μm was placed on the top and bottom layers. Then, the samples were heated at 200°C and 40 kg / cm. 2 The mixture was heated and pressed at room temperature for 120 minutes to prepare a resin substrate.

[0177] [Solder heat resistance] The top and bottom copper foils were removed from the resin substrate to obtain a laminate. The resulting laminate was cut into a total of 10 pieces measuring 5 cm x 5 cm. The laminate was then heated at 133°C for 72 hours in a pressure cooker and allowed to absorb water. The water-absorbed laminate was then immersed in a solder bath at 288°C for 20 seconds, and each of the 10 laminate samples was visually inspected for blistering due to peeling at the glass cloth / resin interface.

[0178] The laminated plate samples that showed blistering due to peeling at the glass cloth / resin interface were rated as "failed," and the number of "failed" laminated plate samples was evaluated. The fewer the number of glass cloths listed in the table, the more excellent the heat resistance.

[0179] [Whitening distance] The laminate was cut into a size of 7 cm x 4 cm, and two 2 cm slits were made vertically and horizontally using a diamond cutter to prepare test pieces. The test pieces were prepared according to the method described in JP 2020-158364 A.

[0180] The obtained test piece was immersed in a 1 mol / L NaOH aqueous solution and heated at 60°C for 30 hours. A whitening distance test was then conducted using a digital microscope (manufactured by Keyence Corporation) at 100x magnification to measure the whitening distance due to peeling between the resin and glass interface in the warp and weft directions. In the whitening distance test, the whitening distance was measured at 24 points in each of the warp and weft directions, and the average value was calculated. The whitening distance for each level was evaluated as a relative value, with the value for Comparative Example 1 set at 1.0. Reducing the whitening distance indicates improved insulation reliability in printed wiring boards. The results are shown in the table below.

[0181] The manufacturing conditions and evaluation results for the Examples and Comparative Examples are shown in the table below. Note that, using the glass cloth of the Examples, prepregs, printed wiring boards (resin substrates), integrated circuits, and electronic devices could be manufactured by conventional methods.

[0182] [Table 1]

[0183] [Table 2]

[0184] According to the examples, it was possible to provide a glass cloth that can realize excellent dielectric properties and excellent insulation reliability, and further improve the properties of the resin substrate produced using the glass cloth (for example, reduce the whitening distance of the resin substrate). On the other hand, in all the comparative examples, it was not possible to reduce the whitening distance of the obtained resin substrate, and in particular, in comparative example 2, it was not possible to obtain excellent properties regarding solder heat resistance. [Industrial Applicability]

[0185] The present invention can be used in fields related to glass cloth, printed wiring boards (particularly printed wiring boards for high-speed communication), and the like. [Explanation of symbols]

[0186] P: White spot

Claims

1. A glass cloth made by weaving glass yarn, the glass cloth is surface-treated with a surface treatment agent, The following formula A is calculated from the total carbon amount of the glass cloth and the peak height derived from the carbonyl group measured by Fourier transform infrared spectroscopy: Formula A = peak height derived from carbonyl group / total carbon content of glass cloth is 10 or more, The surface treatment agent is represented by the following formula (1): X 3-n Yes n ・・・(1) (In the formula, each X is independent and may contain a different organic functional group, and is composed of a functional group having a total of two or more carbonyl groups and two or more unsaturated carbon-carbon double bonds in X; each Y is independently an alkoxy group; and n is an integer of 1 or more and 3 or less.) A glass cloth containing a silane coupling agent represented by the formula:

2. A glass cloth made by weaving glass yarn, The glass cloth is surface-treated with a surface treatment agent, The following formula B is calculated from the ignition loss value of the glass cloth and the peak height derived from the carbonyl group measured by Fourier transform infrared spectroscopy: Formula B = peak height derived from carbonyl group / ignition loss value of glass cloth is 11 or more, The surface treatment agent is represented by the following formula (1): X 3-n Yes n ・・・(1) (In the formula, each X is independent and may contain a different organic functional group, and is composed of a functional group having a total of two or more carbonyl groups and two or more unsaturated carbon-carbon double bonds in X; each Y is independently an alkoxy group; and n is an integer of 1 or more and 3 or less.) A glass cloth containing a silane coupling agent represented by the formula:

3. The silicon (Si) content in the glass fiber is silicon dioxide (SiO 2 3. The glass cloth according to claim 1, wherein the total mass of the glass fiber is 95.0 to 100 mass % in terms of the total mass of the glass fiber.

4. 3. The glass cloth according to claim 1, which has a dielectric loss tangent at 10 GHz of 0.002 or less.

5. 3. The glass cloth according to claim 1, wherein the glass constituting the glass yarns has a bulk dielectric loss tangent of 0.002 or less at 10 GHz.

6. The glass cloth according to claim 1 or 2, wherein the surface treatment agent comprises a silane coupling agent.

7. 3. The glass cloth according to claim 1, wherein the unsaturated carbon-carbon double bond is a bond derived from at least one of an acryloyl group and a methacryloyl group.

8. 3. The glass cloth according to claim 1, wherein the ignition loss of the glass cloth is in the range of 0.01 to 0.5 mass %.

9. 3. The glass cloth according to claim 1, wherein an average degree of opening calculated from the yarn widths of the warp and weft of the glass cloth is more than 40%.

10. 3. The glass cloth according to claim 1, wherein the total carbon content of the glass cloth is in the range of 0.01 to 0.8 mass %.

11. A prepreg comprising the glass cloth according to claim 1 or 2 and a matrix resin.

12. A printed wiring board comprising the prepreg of claim 11.

13. An integrated circuit comprising the printed wiring board of claim 12.

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

15. A method for producing glass cloth by weaving glass yarns, a surface treatment step of treating the glass fiber with a surface treatment liquid containing a surface treatment agent having a molecular weight of 200 or more; The surface treatment step includes: a step of adding a solvent to the surface treatment agent to prepare the surface treatment liquid; controlling the temperature of the surface treatment solution; controlling the pH of the surface treatment solution; and filtering the surface treatment liquid; and The surface treatment step includes: The method includes a step of surface-treating the deoiled glass fiber with a surface treatment agent, The surface treatment agent has the following formula (1): X 3-n Yes n ・・・(1) (In the formula, each X is independent and may contain a different organic functional group, and is composed of a functional group having a total of two or more carbonyl groups and two or more unsaturated carbon-carbon double bonds in X; each Y is independently an alkoxy group; and n is an integer of 1 or more and 3 or less.) A method for producing glass cloth, comprising the silane coupling agent represented by the formula:

16. The surface treatment step includes: controlling the temperature and pH of the surface treatment solution; The method for producing glass cloth according to claim 15, further comprising the step of filtering the surface treatment liquid.

17. The method for producing a glass cloth according to claim 15 or 16, further comprising a step of subjecting the glass yarns to an opening treatment after the surface treatment step.

18. The method for producing a glass cloth according to claim 15 or 16, further comprising the step of inspecting the frequency of occurrence of white spots in the glass cloth. The frequency of occurrence of the white spots is evaluated by irradiating a glass cloth of A4 size (210 mm x 297 mm) or larger with a halogen lamp. In the case of observing a sheet-like glass cloth, a halogen lamp was placed directly above the glass cloth, and the number of white spots was calculated using the following formula while changing the direction of observation of the glass cloth: Frequency of white spots (pieces / m ２ ) = number of white spots / {area of ​​glass cloth (m ２ ) The frequency of occurrence of the white spots is calculated according to the following formula. In the case of observing a glass cloth roll, a tension of 100 N / 1300 mm is applied to the glass cloth on a roll-to-roll inspection table, and the number of white spots occurring on the glass cloth is counted over a length of 2000 m while irradiating the glass cloth with a halogen lamp. Then, the inspection area and the number of white spots found in the inspection are calculated using the following formula: Frequency of white spots (pieces / m ２ ) = number of white spots / {width of glass cloth (m) × length of inspected glass cloth (m)} The frequency of occurrence of the white spots is calculated according to the following formula. However, the white spot has a white outline that can be observed when irradiated with UV light, and the area enclosed by the outline (the area including the outline) is 0.8 cm ２ The defects defined above are counted as the white spots.

19. 17. The method for producing a glass cloth according to claim 15, further comprising a step of measuring a peak height derived from a carbonyl group in the glass cloth by Fourier transform infrared spectroscopy.

20. A test method for glass cloth made by weaving glass yarn, the glass cloth is surface-treated with a surface treatment agent, The test method comprises: The test method includes a step of inspecting the frequency of occurrence of white spots on the glass cloth. The frequency of occurrence of the white spots is evaluated by irradiating a glass cloth of A4 size (210 mm x 297 mm) or larger with a halogen lamp. In the case of observing a sheet-like glass cloth, a halogen lamp was placed directly above the glass cloth, and the number of white spots was calculated using the following formula while changing the direction of observation of the glass cloth: Frequency of white spots (pieces / m ２ ) = number of white spots / {area of ​​glass cloth (m ２ ) The frequency of occurrence of the white spots is calculated according to the following formula. In the case of observing a glass cloth roll, a tension of 100 N / 1300 mm is applied to the glass cloth on a roll-to-roll inspection table, and the number of white spots occurring on the glass cloth is counted over a length of 2000 m while irradiating the glass cloth with a halogen lamp. Then, the inspection area and the number of white spots found in the inspection are calculated using the following formula: Frequency of white spots (pieces / m ２ ) = number of white spots / {width of glass cloth (m) × length of inspected glass cloth (m)} The frequency of occurrence of the white spots is calculated according to the following formula. However, the white spot has a white outline that can be observed when irradiated with UV light, and the area enclosed by the outline (the area including the outline) is 0.8 cm ２ The defects defined above are counted as the white spots.

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